| 1. |
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| 2. |
- Bjorling, Patrik, et al.
(författare)
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Ten Year Follow-up After Total Wrist Arthroplasty
- 2017
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Konferensbidrag (refereegranskat)abstract
- Hypothesis Total wrist arthroplasty (TWA) is an option in the management of wrist arthritis. The aim of the study was to evaluate the long-term results of TWA.Methods In this cohort study, we followed 56 cases that underwent TWA (Avanta, Biax, Universal 2 and Maestro) between 2005 and 2006 at a single-center. Data was collected preoperatively and 10 years postoperatively. Patient-related outcome measures, grip strength, range of motion (ROM), VAS pain scores were analyzed.Results VAS pain scores and patient-related measures were significantly improved at the 10-year follow-up. Jamar grip strength was also significantly improved. ROM remained largely unchanged, except for extension which improved significantly at the 10-year follow-up. Five of 56 TWAs were revised. Five patients died of unrelated causes and 10 were lost to follow-up.Summary Points This study shows good long-term results after TWA with a high level of patient satisfaction. The revision rate was acceptable.
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| 3. |
- Blenckner, Thorsten, et al.
(författare)
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Climatic change and the risk of lake eutrophication
- 2006
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Ingår i: Verh. Int. Verein. Limnol.. ; 29, s. 1837-1841
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Tidskriftsartikel (refereegranskat)abstract
- Climatic variation and change affect the dynamics of nutrients and ecosystem processes.The aim is to quantitatively evaluate changes in phosphorus dynamics resulting from a climate warming in lakes. Long-term data and the results of a regional climate model, a physical lake model and a phosphorus model generated for three Swedish lakes with different morphometry and trophic status were analysed. The analysis of the long-term data and the models varied greatly with respect to the variability and the response of the phosphorus dynamics to past and future climate scenarios. The risk of lake eutrophication will be discussed.
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| 4. |
- Blenckner, Thorsten, et al.
(författare)
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Preface
- 2011
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Ingår i: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 660:1, s. 1-2
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Tidskriftsartikel (refereegranskat)
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| 5. |
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| 6. |
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| 7. |
- Fischer, Per, 1981-, et al.
(författare)
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Functional and kinematic analysis of a wrist radial hemiarthroplasty design
- 2017
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Konferensbidrag (refereegranskat)abstract
- Hypothesis A radial hemiarthroplasty could obviate difficulties related to distal component loosening of the total wrist arthroplasty. The aim of this study is to investigate kinematically, the feasibility of a new design for radial wrist hemiarthroplasty.Methods Six, fresh-frozen cadaveric wrist specimens were used. Testing was performed on the native wrist, after insertion of a radial hemi-arthroplasty with intact proximal carpal row (Hemi) and with proximal row carpectomy (Hemi+PRC). Each wrist was fixed to an experimental table with the tendons of the extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor carpi ulnaris (ECU), flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), and abductor pollicis longus (APL) attached to the apparatus. Range of motion, axis of rotation, and muscle moment arms were recorded in manually controlled movements in wrist flexion/extension, radial/ulnar deviation, dart throwers motion, and circumduction.Results A statistically significant decrease in flexion range of motion occurred between the intact and Hemi conditions and between the intact and Hemi+PRC conditions with no significant differences in flexion range of motion occurring between the Hemi and Hemi+PRC conditions. No statistically significant changes in range of motion occurred in extension, radial deviation, ulnar deviation, flexion/ulnar deviation component of the dart throw, extension/radial deviation component of the dart throw, or circumduction functional tests.Summary Points This study indicates that the new wrist radial hemiarthroplasty can produce a stable wrist with range of motion similar to the native wrist. Overall, wrist kinematics appears to be equally acceptable in hemiarthroplasty with and without resection of the proximal row.
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| 8. |
- Fischer, Per, 1981-
(författare)
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Hemi and total wrist arthroplasty
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aim: To study implant survival and implant loosening following primary total wrist arthroplasty (TWA) using four different implants. To report outcome following wrist revision arthroplasty. To evaluate a new radial wrist hemi arthroplasty (RWHA) design clinically and biomechanically.Method: The studies included 136 primary TWAs and 16 revision TWAs, both studies with prospectively collected data. Six fresh frozen cadaveric wrist specimen were used for biomechanical analysis. The RHWA was evaluated clinically in a pilot series of 20 cases.Results: Total implant survival was 92% but with high frequency of implant loosening of surviving Re-Motion implants. None of the surviving Maestro implants were considered radiographically loose. Implant survival following revision arthroplasty was 75%, considerably lower than following primary TWAs. However, none of the patients with surviving revision implants had pain at rest and little or no pain in activity. The surgical procedure and placement of the RHWA was feasible. Overall, the kinematic and functional changes appeared acceptable compared to the native wrist. None of the patients underwent revision following RHWA but reoperation was performed in 7 patients on the indication of persistent pain. However, patients reported relief of pain and improvement of patient-reported outcome measures.Conclusion: High long-term implant survival and no signs of radiographic loosening was found for the Maestro implant. However, the Maestro implant is no longer available on the market and we believe there is a need for new TWA designs. Revision arthroplasty is a valid option in the management of failed TWA. However, implant survival is lower than for primary TWAs and as many as 25% require additional surgery. Promising results were found using the new RHWA design but the implant needs modification before further testing.
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| 9. |
- Fischer, Per, 1981-, et al.
(författare)
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Revision Arthroplasty of the Wrist in Patients With Rheumatoid Arthritis, Mean Follow-Up 6.6 Years
- 2018
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Ingår i: Journal of Hand Surgery-American Volume. - : Elsevier. - 0363-5023 .- 1531-6564. ; 43:5, s. 489.e1-489.e7
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Management of failed total wrist arthroplasty (TWA) can be challenging; surgical treatment options include salvage arthrodesis, revision arthroplasty, and resection arthroplasty. There are few studies regarding salvage arthrodesis, and revision arthroplasty has been infrequently investigated. The aim of the study was to report the outcome after revision arthroplasty of the wrist.METHODS: A retrospective cohort of 16 revision TWAs was evaluated between 2003 and 2016. Data were collected before surgery and 1 and 5 years after surgery. The indication for revision arthroplasty was failed TWA. The primary end point was implant survival. Secondary outcome measures included visual analog scale (VAS) pain scores, range of motion, handgrip strength, and functional scoring with the Canadian Occupational Performance Measure (COPM), Patient-Rated Wrist Evaluation (PRWE), and Disabilities of the Arm, Shoulder, and Hand (DASH).RESULTS: Mean follow-up was 6.6 years. Synthetic bone graft was used in 9 cases, allograft corticocancellous bone graft in 1 case, and cement in 6 cases. Of the 16 revision TWAs, 4 were re-revised, 1 because of infection, and 3 cases underwent total wrist arthrodesis. In the non-re-revised cases, range of motion and grip strength was preserved compared with preoperative results. The VAS pain score in activity improved, but not significantly, at 1 (median, 1; range, 0-4.5) and 5 years after surgery (median, 0) compared with before surgery (median, 5). The COPM performance and satisfaction as well as PRWE scores improved significantly at 1 year (median COPM performance, 4.8; COPM satisfaction, 5.6; and PRWE, 24) and improved, but not significantly, at the 5-year follow (median COPM performance, 4.8; COPM satisfaction, 5.0; and PRWE, 37) in the non-re-revised cases.CONCLUSIONS: Revision arthroplasty of the wrist is a valid motion-preserving option to wrist arthrodesis in the management of failed TWA. However, the outcome is uncertain and as many as 25% require additional surgery.TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Gupta, Anil, et al.
(författare)
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Patient controlled regional analgesia after carpal tunnel release: a double-blind study using distal perineural catheters
- 2011
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Ingår i: JOURNAL OF HAND SURGERY-EUROPEAN VOLUME. - : Elsevier Science B. V., Amsterdam. - 1753-1934 .- 2043-6289. ; 36E:3, s. 219-225
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Tidskriftsartikel (refereegranskat)abstract
- This study was done to assess the efficacy of a perineural catheter for pain relief following carpal tunnel release (CTR). Sixty-six patients undergoing open CTR under local anaesthesia (LA) were randomly divided into three groups: Groups A and B had a perineural catheter and Group C served as non-blinded control group. Postoperative pain relief was by self-administration of either ropivacaine (Group A) or saline (Group B) via an elastometric pump and by oral paracetamol in Group C. Patients in Group A had a significantly greater difference in summed pain intensity than Group B. Fewer patients in Group A requested supplementary analgesics than in Group C. Patient satisfaction was higher in Group A than in Group B on day 1. However better analgesia was not associated with better functional recovery.
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| 14. |
- Hooke, Alexander W., et al.
(författare)
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An anatomic and kinematic analysis of a new total wrist arthroplasty design
- 2015
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Ingår i: Journal of wrist surgery. - New York : Thieme Medical Publishers. - 2163-3916 .- 2163-3924. ; 4:2, s. 121-127
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: Total wrist arthroplasty (TWA) is a viable surgical treatment for disabling wrist arthritis. While current designs are a notable improvement from prior generations, radiographic loosening and failures remain a concern.Purpose: The purpose of this investigation is to evaluate a new total wrist arthroplasty design kinematically. The kinematic function of a native, intact cadaveric wrist was compared with that of the same wrist following TWA.Method: Six, fresh-frozen wrist cadaveric specimens were utilized. Each wrist was fixed to an experimental table and its range of motion, axis of rotation, and muscle moment arms were calculated. The following tendons were attached to the apparatus to drive motion: extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor carpi ulnaris (ECU), flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), and abductor pollicis longus (APL). The wrist was then manually moved along a guide by an experimenter through a series of motions including flexion-extension, radial-ulnar deviation, and circumduction. The experiment was then performed on the specimen following implantation of the TWA.Results: Following the TWA procedure, there were statistically significant decreases in the ulnar deviation and the flexion/ulnar deviation component of dart throw ranges of motion. There were no statistically significant changes in flexion, extension, radial deviation, the extension/radial deviation component of the dart thrower motion, or the circumduction range of motion.Conclusions: Kinematic analysis of the new TWA suggests that a stable, functional wrist is achievable with this design.Clinical Relevance: While appreciating the limitations of a cadaveric study, this investigation indicates that the TWA design studied merits study in human populations.
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| 15. |
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| 16. |
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| 17. |
- Johansson, Torbjörn
(författare)
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Phosphorus Emissions from Fish Farms : Observed and Predicted Effects
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During the last decades, fish farming has been a rapidly increasing industry in many European and North American countries. Sweden has a large potential for aquaculture, but there is also a strong concern about the effects on the environment that an increased aquaculture production may cause. This thesis focuses on the eutrophication effects of fish farming in lakes and in coastal areas of the Baltic Sea.Possible eutrophication effects related to marine fish farm emissions were found in small and semi-enclosed bays in the Åland archipelago of the Baltic Sea. Fish farming did not have any measurable large scale effect on TN in the Åland archipelago, but there were indications of a large scale effect on TP.Nutrient concentrations and other eutrophication indicators in lakes with fish farms correlated well with the variations in farm load among the lakes and with distance from the fish farms within lakes. In a majority of the observed cases the effects on phosphorus concentrations were smaller than expected from the most commonly used models. Besides overestimating the effects, these old models described the variation between lakes adequately. It was therefore possible to construct farm specific steady state models based on the same model structures, that should be simple and accurate enough to be useful.The observed effects on phosphorus concentrations tended to be higher in lakes where fish farms had been active for a long time, compared to lakes with new fish farms. Earlier investigations have shown that there is a considerable time lag in the response of changed phosphorus loads in many lakes. Empirical data and model simulations suggest that this is the case also for fish farm lakes.
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| 18. |
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| 19. |
- Karlsson-Elfgren, Irene, et al.
(författare)
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Recruitment and pelagic growth of Gloeotrichia echinulata (Chyanophyceae) in Lake Erken
- 2003
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Ingår i: Journal of Phycology. - : Wiley. - 0022-3646 .- 1529-8817. ; 39:6, s. 1050-1056
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Tidskriftsartikel (refereegranskat)abstract
- Different parameters in the life cycle of the colony forming cyanobacterium Gloeotrichia echinulata (J.E. Smith) Richter was evaluated in Lake Erken, Sweden. Recruitment of colonies from the sediments and pelagic abundance were measured during 2 years. These data were then used in a model to evaluate and estimate parameters of the life cycle. In our study, recruitment alone only contributed to a small part (<5%) of the maximum G. echinulata abundance that occurred during late summer. However, recruitment from shallow sediments forms the important seed for the pelagic population. Together with measured rates of migration from the sediment, variations in either pelagic colony division rate or pelagic residence time could explain variations in the measured abundance of G. echinulata in situ.
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| 20. |
- Karlsson Elfgren, Irene
(författare)
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Studies on the Life Cycles of Akinete Forming Cyanobacteria
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cyanobacteria which can form resting cells (in this case akinetes) are common in meso-eutrophic lakes in temperate regions, often dominating the phytoplankton communities during summer. The life cycles of akinete-forming cyanobacteria has been studied with Gloeotrichia echinulata as a model organism. Anabaena and Aphanizomenon were also included in a migration study. The focus of this thesis has been the factors influencing the processes of germination and subsequent growth, the factors influencing migration from the sediment, and the amount of growth occurring in the water. Germination of G. echinulata was strongly favoured by light, and recruitment was highest from organic-rich sediments in shallow, sheltered littoral areas, between 0-3 m. Recruitment of Anabaena and Aphanizomenon was less light dependent, yet the highest recruitment occurred from shallow sediments (0-2 m). This means that organic-rich sediments (0-3 m) in shallow areas are the most important seed-banks of akinete-forming cyanobacteria. The inocula contributed only to a minor extent to the maximum pelagic populations. 4% for G. echinulata in the mesotrophic Lake Erken, and 0.03% for both Anabaena and Aphanizomenon in the eutrophic Lake Limmaren. This implies that processes of growth and division in the water are important for the maximum size of the pelagic population. Prolonged recruitment from the sediment strongly promoted establishment of the species in the water, especially G. echinulata.
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| 21. |
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| 22. |
- Lundqvist, Eva, 1985-, et al.
(författare)
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Volar Locking Plate Compared With Combined Plating of AO Type C Distal Radius Fractures : A Randomized Controlled Study of 150 Cases
- 2022
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Ingår i: Journal of Hand Surgery-American Volume. - : Elsevier. - 0363-5023 .- 1531-6564. ; 47:9, s. 813-822
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The optimal way to stabilize intra-articular distal radius fractures is unclear despite recent advances in surgical management. Volar plating is the most common treatment but may not be sufficient for more complex intra-articular AO type C fractures. The purpose of this randomized controlled study was to evaluate the radiographic and clinical outcomes following surgical treatment of AO type C distal radius fractures, comparing volar with combined plating.METHODS: In this study, 150 patients were randomized to volar locking plate (n = 75) or combined plating (n = 75) following a distal radius fracture AO type C. The 1-year follow-up included radiographic outcome (Batra score), visual analog scale pain score, hand grip strength, wrist range of motion, Patient-Rated Wrist Evaluation score, and Quick Disabilities of the Arm, Shoulder, and Hand score.RESULTS: Overall, 147 patients (median age 61 years) completed the 1-year follow-up (73 patients with volar plate and 74 with combined plating). No difference was found in radiographic outcome between the treatment groups. The volar plate group had significantly better Patient-Rated Wrist Evaluation scores, Quick Disabilities of the Arm, Shoulder, and Hand scores, hand grip strength, visual analog scale scores during activity, and flexion, extension, ulnar and radial deviation than the combined plate group. Hardware removal was performed in 10% in the volar plate group and in 31% in the combined plate group. There was no postoperative infection in the volar plate group but 3 cases in the combined plate group.CONCLUSIONS: In patients with complex AO type C intra-articular fractures, volar and combined plating yielded the same radiographic result. The differences in Patient-Rated Wrist Evaluation and Quick Disabilities of the Arm, Shoulder, and Hand scores between the groups did not reach the thresholds for minimal clinically important differences, suggesting similar clinical outcome. The combined plating group had a considerably higher frequency of hardware removal and postoperative infections.TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic I.
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| 23. |
- Malmaeus, Jan Mikael, 1971-
(författare)
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Predictive Modeling of Lake Eutrophication
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents predictive models for important variables concerning eutrophication effects in lakes. The keystone is a dynamic phosphorus model based on ordinary differential equations. By calculating mass fluxes of phosphorus into, within and out from a lake, the concentrations of different forms of phosphorus in different compartments of the lake are estimated.The dynamic phosphorus model is critically tested and several improvements are presented, including two new compartments for colloidal phosphorus, a sub-model for suspended particulate matter (SPM) and new algorithms for lake outflow, water mixing, diffusion, water content and organic content of accumulation sediments are implemented. Predictions with the new version show good agreement against empirical data in five tested lakes.The sub-model for SPM uses the same driving variables as the basic phosphorus model, so the inclusion of this model as a sub-model does not require any additional variables. The model for SPM may also be used as a separate model giving monthly predictions of suspended particulate matter in two water compartments and one compartment with SPM available for resuspension in ET-sediments.Empirical data from Lake Erken (Sweden) and Lake Balaton (Hungary) are used to evaluate the variability in settling velocity of SPM. It is found that the variability is substantial and may be accounted for by using a dimensionless moderator for SPM concentration. Empirical data from accumulation area sediments in Lake Erken are used to develop a model for the dynamics of phosphorus sedimentation, burial and diffusion in the sediments. The model is shown to provide reasonable monthly predictions of four functional forms of phosphorus at different sediment depths.Simulations with the lake phosphorus model using two different climate scenarios indicate that lakes may respond very differently to climate change depending on their physical character. Lake Erken, with a water retention time of 7 years, appears to be much more sensitive than two basins of Lake Mälaren (Sweden) with substantially shorter retention times. The implication would be that in eutrophic lakes with long water retention times, eutrophication problems may become serious if the future becomes warmer. This will be important in contexts of lake management when remedial measures against lake eutrophication have to be taken.
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| 24. |
- Markensten, Hampus, 1967-
(författare)
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Climate Effects on Phytoplankton Biomass and Functional Groups
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Future climate in temperate regions is projected to get warmer and in many cases wetter. This poses questions about how phytoplankton in our lakes will respond. A dynamic modeling approach based on an allometric description of phytoplankton characteristics was used to investigate how the biomass of different functional groups of phytoplankton will respond to a changed future climate. Simulations based on a warmer future climate scenario suggest that we will experience an increase in phytoplankton biomass in northern temperate lakes. Moreover, phytoplankton groups are projected to shift towards a dominance of cyanobacteria at the expense of diatoms. Climate may affect phytoplankton, either via in-lake changes in temperature and stratification, or due to altered processes at the watershed level, which influence rates of nutrient export and water discharge. This study found that changes in lake temperature and stratification are the major causes of the projected increase in phytoplankton biomass, but that changes in the timing of nutrient export did influence the succession of diatoms. Variation in SPIM (suspended particulate inorganic matter) can have an important role in influencing the depth of the euphotic zone in a turbid lake, and hence the light climate experienced by phytoplankton. Wind and river discharge were found to regulate SPIM in this study, not only wind as in many other studies. Variations in SPIM could be adequately described by a few governing equations. This thesis suggests that, as a result of climate change, lakes close to the limit of becoming eutrophied may be pushed past a threshold beyond which water quality problems will become more prevalent. Finally it is important to bear in mind that all models are simplifications of the reality as we understand it. Still, the use of models can often give a good indication as to what might be expected in the future.
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| 25. |
- Moore, Karen, 1958-
(författare)
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Climate Change Impacts on the Catchment Contribution to Lake Water Quantity and Quality
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A key question related to climate change projections is how will aquatic systems respond to changes in variables such as temperature and precipitation? This thesis uses GWLF, a simple catchment scale model to explore potential impacts of climate change on water quantity and quality.River discharge and nutrient loads were modelled for several warmer world scenarios. For one catchment in New York, USA changes in annual dissolved phosphorus loads decreased along with annual streamflow, and particulate phosphorus loads increased for a single future climate scenario. For the Galten catchment of Lake Mälaren, Sweden, the spring melt peak observed historically was reduced for six future scenarios. Peak runoff and dissolved phosphorus and nitrogen load maxima occurred in winter rather than early spring.A synthesis of model results for dissolved inorganic nitrogen (DIN) loadings for five European catchments showed changes in the timing and magnitude of peak DIN load for several future scenarios. In northern Europe, changes were largely due to increased winter streamflow and reduced snow pack and spring melt runoff. In western Europe, DIN loads increased in winter or early spring due to increased precipitation.The biological response for a warmer future scenario was modelled for the Galten basin of Lake Mälaren using GWLF coupled to a lake phytoplankton model and a physical lake model. An increase in cyanobacteria biomass accompanied by a decline in diatom biomass resulted from changes in the timing of nutrient export from the catchment. The projected increase in lake temperature favored an overall increase in total phytoplankton biomass.Lastly, a method based on hourly measurements of colored dissolved organic matter (CDOM) fluorescence provides the appropriate data for dissolved organic carbon (DOC) model parameterization and may also be used for surveillance of organic matter inputs to lakes.
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| 26. |
- Moore, Karen, et al.
(författare)
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Effects of Warmer World Scenarios on Hydrologic Inputs to Lake Mälaren, Sweden and Implications for Nutrient Loads
- 2008
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Ingår i: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 599, s. 191-199
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Tidskriftsartikel (refereegranskat)abstract
- A simple, rapid, and flexible modelling approach was applied to explore the impacts of climate change on hydrologic inputs and consequent implications for nutrient loading to Lake Malaren, Sweden using a loading function model (GWLF). The first step in the process was to adapt the model for use in a large and complex Swedish catchment. We focused on the Galten basin with four rivers draining into the western region of Malaren. The catchment model was calibrated and tested using long-term historical data for river discharge and dissolved nutrients (N, P). Then multiple regional climate model simulation results were downscaled to the local catchment level, and used to simulate possible hydrological and nutrient loading responses to warmer world scenarios. Climate change projections for the rivers of Galten basin show profound changes in the timing of discharge and nutrient delivery due to increased winter precipitation and earlier snow melt. Impacts on total annual discharge and load are minimal, but the alteration in river flow regime and the timing of nutrient delivery for future climate scenarios is strikingly different from historical conditions.
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| 27. |
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| 28. |
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| 29. |
- Naddafi, Rahmat, et al.
(författare)
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Effects of the zebra mussel, an exotic freshwater species, on seston stoichiometry
- 2008
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Ingår i: Limnology and Oceanography. - : American Society of Limnology and Oceanography. - 0024-3590 .- 1939-5590. ; 53:5, s. 1973-1987
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Tidskriftsartikel (refereegranskat)abstract
- We examined the effect of the zebra mussel, Dreissena polymorpha, an exotic species, on seston stoichiometry by conducting laboratory experiments in which we varied nutrient composition of seston and mussels over time. Zebra mussels altered the stoichiometry of seston through removal of particulate organic nutrients and changed the stoichiometry of the dissolved nutrient pool through nutrient excretion. Grazers had stronger effects on carbon : phosphorus (C : P) and nitrogen (N) : P ratios than on the C:N ratio of seston. Elemental residence time in tissue and high mass-specific nutrient excretion by small mussels caused small mussels to be more efficient nutrient recyclers than larger mussels. Zebra mussels reduced P availability through enhancing C: P and N: P molar ratios of seston during the period extending from June to August, when P was limited in the lake, and increased the C:N molar ratio of seston in June, when N was at the minimum level in the lake. C: P and N: P molar ratios for zebra mussel tissue were higher in August and somewhat in September than in all other months. N was retained more efficiently than P in Dreissena tissue. Nutrient mass-specific uptake rate was higher than excretion rate by zebra mussels.
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| 30. |
- Naddafi, Rahmat, et al.
(författare)
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Non-lethal predator effects on the feeding rate and prey selection of the exotic zebra mussel (Dreissena polymorpha)
- 2007
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Ingår i: Oikos. - 0030-1299 .- 1600-0706. ; 116:8, s. 1289-1298
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Tidskriftsartikel (refereegranskat)abstract
- Predators may induce changes in prey feeding that indirectly influence both the impact of prey on resource abundances and their interactions with other species in their community. We evaluated whether clearance and excretion (faeces plus pseudofaeces) of phytoplankton by zebra mussels were affected by the presence of predatory cues from roach (Rutilus rutilus) and signal crayfish (Pasifastacus leniusculus). We found that non-lethal effects of predators can alter zebra mussel clearance rate and thus the impact of zebra mussels on phytoplankton. Risk cues released by both predators had similar negative effects on clearance rate of zebra mussels and cascading positive indirect effects on phytoplankton resources. Predation risk had a stronger effect on zebra mussels' clearance rate of cyanobacteria and diatoms than cryptophytes and chrysophytes. The presence of predators did not significantly affect the rate at which zebra mussels expelled and excreted phytoplankton, although there was a tendency for more chlorophyll to be expelled and excreted in the presence of predators. Our results contribute to the growing evidence that predators indirectly affect resource dynamics and food web structure through their non-lethal effects on consumers. Our results suggest that exotic species such as zebra mussels can show behavioural responses to both native (e.g., roach) and exotic (e.g., crayfish) predators.
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| 31. |
- Naddafi, Rahmat, et al.
(författare)
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Physical and chemical properties determine zebra mussel invasion success in lakes
- 2011
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Ingår i: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 669:1, s. 227-236
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Tidskriftsartikel (refereegranskat)abstract
- To address the question whether the abundance of an invasive species can be explained by physical and chemical properties of the invaded ecosystems, we gathered density data of invasive zebra mussels and the physical and chemical data of ecosystems they invaded. We assembled published data from 55 European and 13 North American lakes and developed a model for zebra mussel density using a generalized additive model (GAM) approach. Our model revealed that the joint effect of surface area, total phosphorus and calcium concentrations explained 62% of the variation in Dreissena density. Our study indicates that large and less productive North American lakes can support larger local populations of zebra mussels. Our results suggest that the proliferation of an exotic species in an area can partially be explained by physical and chemical properties of the recipient environment.
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| 32. |
- Naddafi, Rahmat, et al.
(författare)
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Predation and physical environment structure the density and population size structure of zebra mussels
- 2010
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Ingår i: Journal of The North American Benthological Society. - : University of Chicago Press. - 0887-3593 .- 1937-237X. ; 29:2, s. 444-453
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Tidskriftsartikel (refereegranskat)abstract
- The zebra mussel (Dreissena polymorpha) provides one example of successful invaders in novel environments. However, little attention has been devoted to exploring the factors regulating zebra mussel density and population size structure at the local scale. We tested effects of physicochemical factors and fish predation on the density of zebra mussels at several sites and between years in a natural lake. Water depth and roach (Rutilus rutilus) density were the most important variables affecting local zebra mussel density. Substrate was also an important factor but affected Dreissena density only at the shallowest depth examined (2 m), which also supported a large population of the mussels. Mean shell length of Dreissena increased with water depth. Our results indicate that predation pressure, intraspecific competition, and food limitation might be responsible for variation in zebra mussel density and population size structure in space and time and that fish predation might have strong top-down effects on zebra mussel populations.
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| 33. |
- Naddafi, Rahmat, 1975-, et al.
(författare)
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Stoichiometric constraints do not limit successful invaders : zebra mussels in Swedish lakes
- 2009
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 4:4, s. e5345-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Elemental imbalances of carbon (C): nitrogen (N): phosphorus (P) ratios in food resources can constrain the growth of grazers owning to tight coupling between growth rate, RNA allocation and biomass P content in animals. Testing for stoichiometric constraints among invasive species is a novel challenge in invasion ecology to unravel how a successful invader tackles ecological barriers in novel ecosystems.Methodology/Principal Findings: We examined the C:P and N:P ratios and the condition factor of a successful invader in lakes, the zebra mussel (Dreissena polymorpha), collected from two Swedish lakes. Concurrently, we analyzed the elemental composition of the food (seston) and tissue of the mussels in which nutrient composition of food and mussels varied over time. Zebra mussel condition factor was weakly related to the their own tissue N:P and C:P ratios, although the relation with the later ratio was not significant. Smaller mussels had relatively lower tissue N:P ratio and higher condition factor. There was no difference in C:P and N:P ratios between seston and mussels' tissues. Our results indicated that the variation in nutrient stoichiometry of zebra mussels can be explained by food quality and quantity. Conclusions/Significance: Our study suggests that fitness of invasive zebra mussels is not constrained by nutrient stoichiometry which is likely to be important for their proliferation in novel ecosystems. The lack of imbalance in C:P and N:P ratios between seston and mussels along with high tissue C:P ratio of the mussel allow them to tolerate potential P limitation and maintain high growth rate. Moreover, zebra mussels are able to change their tissue C:P and N:P ratios in response to the variation in elemental composition of their food. This can also help them to bypass potential nutrient stoichiometric constraints. Our finding is an important step towards understanding the mechanisms contributing to the success of exotic species from stoichiometric principles.
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| 34. |
- Naddafi, Rahmat, et al.
(författare)
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The effect of seasonal variation in selective feeding by zebra mussels (Dreissena polymorpha) on phytoplankton community composition
- 2007
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Ingår i: Freshwater Biology. - : Wiley. - 0046-5070 .- 1365-2427. ; 52:5, s. 823-842
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the impact of zebra mussels (Dreissena polymorpha) on phytoplankton community composition, temporal variability in selective feeding by the mussels was determined from April to November 2005 in a natural lake using Delayed Fluorescence (DF) excitation spectroscopy. Selective grazing by zebra mussels varied in relation to seasonal phytoplankton dynamics; mussels showed a consistent preference for cryptophytes and avoidance of chlorophytes and cyanobacteria. Diatoms, chrysophytes and dinoflagellates responded differentially to zebra mussel grazing depending on their size. Analysis of excreted products of the zebra mussels revealed that in addition to chlorophytes and cyanobacteria, phytoplankton >50 μm and very small phytoplankton (≤7 μm) were largely expelled in pseudofaeces. The zebra mussel is a selective filter-feeder that alters its feeding behaviour in relation to phytoplankton composition to capture and ingest high quality phytoplankton, especially when phytoplankton occur in preferred size ranges. Flexibility of zebra mussel feeding behaviour and variation in susceptibility among phytoplankton groups to mussel ingestion indicate that invading zebra mussels could alter phytoplankton community composition of lakes and have important ecosystem consequences.
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| 35. |
- Naddafi, Rahmat, 1975-
(författare)
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The Invasion of the Zebra Mussel - Effects on Phytoplankton Community Structure and Ecosystem Function
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biological invasion has become a major threat to economy, ecology, global biodiversity and ecosystem function of aquatic ecosystems. The main aim of the thesis was to study the effects of the zebra mussel (Dreissena polymorpha), a versatile invasive species, on phytoplankton dynamics and ecosystem function of lakes.In a first attempt, I compared the density of Dreissena and the physicochemical data of ecosystems that it invaded among North American and European lakes to identify important factors in its invasion success. Secondly, I investigated the impact of zebra mussels on phytoplankton community composition in a natural lake. Thirdly, I evaluated whether zebra mussel feeding behavior were affected by the presence of predatory waterborne cues. Finally, I examined the effect of Dreissena on seston stoichiometry.A Generalized Additive Model revealed that a joint effect of surface area, mean depth, total phosphorus and calcium concentrations can explain the variability in Dreissena density. Selective grazing by zebra mussels varied in relation to seasonal phytoplankton dynamics. Risk cues released by predators affected both feeding rate and prey selection of the mussels and had cascading indirect effects on phytoplankton biomass and community structure. I found that the flux in nutrients caused by differences in zebra mussel consumption lead to a variation in phytoplankton nutrient limitation.The flexibility of zebra mussel feeding behavior and variation in susceptibility among phytoplankton groups to mussel ingestion indicate that invading zebra mussels could alter phytoplankton community composition of lakes and have important ecosystem consequences. The results of this thesis contribute to the growing evidence that predators indirectly affect resource dynamics and food web structure through their non-lethal effects on consumers. The results suggested that zebra mussel can indirectly both reduce and increase the energy transfer efficiency from primary producers to upper trophic levels in the pelagic and benthic food webs, respectively.
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| 36. |
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| 37. |
- Niklasson, Johan, et al.
(författare)
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Pulp-to-palm distance is associated with functional outcome 3 months after combined plating for distal radius fracture
- 2019
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Ingår i: Abstract book IFSHT. - Freiburg : Intercongress GmbH. - 9783000635854
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Konferensbidrag (refereegranskat)abstract
- Clinical issue/s: Objective: The Distal Radius Fracture (DRF) is the most common fracture in adults. After surgical management, extensive rehabilitation programs are common in order to restore function. Some patients are not able to fully move their fingers during the first month after a DRF-surgery (Pulp-to-palm distance=PTP).Clinical reasoning: The purpose of this study was to investigate if increased PTP 4 weeks after DRF surgery is associated with an inferior functional outcome 3 months postoperatively after DRF-surgery.innovative, analytical or new approach: Materials and Methods: This prospective study involved 53 DRF-patients with intra-articular type C fractures according to the AO-classification. All patients were treated with combined volar and dorsal plating. The patients were assessed at 4 weeks and 3 months postoperatively according to PTP-distance, wrist range of motion, grip strength, VAS pain scores and self-assessed hand function. Rehabilitation was the same for all patients with focus on self-training instructions, regardless of individual finger and wrist status.Results: 20 patients had a PTP > 0 cm 4 weeks after surgery. Three months after surgery, all patients had regained full fingermotion. The group with PTP > 0 cm showed significantly inferior range of motion regarding dorsal- and volar flexion, radial- and ulnar deviation as well as grip strength and quick-DASH 3 months after surgery. Inferior outcomes for pro- and supination and PRWE-scores was seen but were not significant. Pain at rest and during activity showed no significant differences between the groups.Contribution to advancing HT practice: Conclusions: Impaired finger motion 4 weeks postoperatively is a significant predictor of functional outcome 3 months postoperatively in surgically treated DRFs. Measuring the PTP-distance can assist the physiotherapist in the allocation of rehabilitation resources.
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| 38. |
- Oskarsson, Eva, et al.
(författare)
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Decreased intramuscular blood flow in patients with lateral epicondylitis
- 2007
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Blackwell Munksgaard. - 0905-7188 .- 1600-0838. ; 17:3, s. 211-215
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this pilot study was to investigate intramuscular microcirculation in extensor carpi radialis brevis (ECRB) in patients with lateral epicondylitis. Ten patients with unilateral epicondylitis, mean duration of symptoms of 39 (12-96) months participated. The diagnosis was based on clinical examination and none was under treatment for the last 6 months. Isometric handgrip strength, 2-pinch grip strength and muscle strength during radial deviation and dorsal extension was determined. Functional perceived pain was evaluated by a modified BRS and perceived pain during contraction by VAS. Intramuscular and skin blood flow was recorded by a laser-Doppler flowmetry system technique (LDF) during stable temperature condition. Intramuscular blood flow was significantly lower in the affected side, 22.7 ± 9.8 PU as compared to 35.2 ± 11.9 PU in the control side (P = 0.01). There was no difference in skin blood flow or temperature between affected and control side. A positive correlation was found between duration of symptoms and the difference in intramuscular blood flow between affected and control arm (r = 0.65, P = 0.06). The present data indicate that decreased microcirculation and anaerobic metabolism in ECRB may contribute to the lateral epicondylitis symptoms.
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| 39. |
- Oskarsson, Eva, 1959-, et al.
(författare)
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Intramuscular pressure in the ECRB muscle of patients with lateral epicondylitis
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Annan publikation (populärvet., debatt m.m.)abstract
- An increased tension and a low intramuscular blood flow in the extensor carpi radialis (ECRB) muscle in patient with lateral epichondylitis has been suggested to contribute to the symptoms. The reason for the lower blood flow may be increased intramuscular pressure. The purpose of this pilot study was to determine intramuscular pressure and blood flow in affected and unaffected ECRB in ten patients with unilateral epicondylitis, with a mean duration of symptoms of 24 (13-48) months. Intramuscular pressure (IMP) was measured using the microcapillary infusion technique and intramuscular blood flow using the laser Doppler flowmetry technique, bilaterally with the non-affected arm serving as a control. The recordings were performed at rest, during isometric dorsal extension of the wrist for 1 min at 40 % and 2 min at 20 % of maximal voluntary contraction (MVC) and during recovery after contractions. At rest the median IMP was 7-8 mm Hg regardless of arm while the median intramuscular blood flow was lower on the affected side compared with the unaffected side (P=0.03). During contraction the IMP and blood flow increased regardless of arm. The IMP fell to pre-contraction level within 2 s after contraction, independent of arm and contraction force. Recovery, regarding the intramuscular blood flow, tended to be faster on the unaffected side than on the affected after contraction at 20 % MVC. After contraction at 40 % MVC the blood flow was equal on both sides. When the IMP value in the unaffected muscle was corrected for the higher force elicited compared to affected muscle the adjusted IMP was significantly lower (P=0.006) at 20 % MVC. In summary, affected ECRB has a lower intramuscular blood flow during rest and a higher intramuscular pressure in relation to the unaffected muscle at contraction for 2 min at 20 % MVC.
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| 40. |
- Oskarsson, Eva, 1959-, et al.
(författare)
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Microvascular response in the ECRB muscle of patients with lateral epicondylitis
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The microvascular response in extensor carpi radialis brevis (ECRB) muscle was studied in thirteen patients with unilateral epicondylitis. At rest the intramuscular blood flow was significantly lower in the affected arm than in the unaffected (P = 0.006). During dorsal extension for 1 min at 40% maximal voluntary contraction (MVC) and 2 min at 20% MVC, blood flow increased significantly in both arms (P = 0.02). Microcirculation remained above resting level both 1 and 2 min after contraction at 40% MVC but was back to the precontraction level 2 min after contraction at 20 % MVC. The reactive hyperaemic response after occlusion of the brachial artery for 5 min, showed no significant difference between the arms. The reason for the hampered microcirculation in ECRB at rest does not seem to be due to a decreased ability of the vessel wall to dilate. Other plausible reasons merits further investigation.
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| 41. |
- Pettersson, Kurt, et al.
(författare)
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Arthrodesis for chronic static scapholunate dissociation : a prospective study in 12 patients
- 2004
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Ingår i: Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery. - Oslo : Taylor & Francis. - 0284-4311 .- 1651-2073. ; 38:3, s. 166-171
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Tidskriftsartikel (refereegranskat)abstract
- Twelve patients had limited arthrodesis between the scaphoid and the lunate for chronic static scapho-lunate dissociation using internal plate osteosynthesis. The median time between the injury and surgery was 50 months (range 9-180). They were followed up for a year postoperatively. Preoperative symptoms were pain, functional impairment, and restricted movement. During operation the scapholunate interosseous ligament was completely torn and the scaphoid malrotated in all patients. The range of motion was measured preoperatively and postoperatively, and the unaffected side used for control. For all patients except one postoperative extension, flexion, and radial deviation had considerably decreased. However, supination increased in seven of 12 patients postoperatively and so did pronation in seven of 12 patients. One patient (case 12) had an improved range of motion postoperatively in all directions. The mean grip strength was 76% of the unaffected side preoperatively, and has increased to 85% postoperatively. We found that bone healing was rare and most arthrodeses healed by a fibrous union. We found no correlation with preoperative arthrosis and clinical outcome. One patient had retired from work before operation because of back pain and one because of age. Two patients had taken early retirement because of wrist pain, and one patient was still on sick-leave at the follow-up a year postoperatively. Five patients returned to full-time work and two patients to part-time work. Four patients were on long-term sick-leave preoperatively and three of them returned to their previous occupations. Analysis of the patients' subjective outcome (including pain and functional scores) showed overall satisfaction, and objective data show that scapholunate arthrodesis for chronic static scapholunate dissociation provides substantial improvement over the preoperative condition.
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| 42. |
- Pettersson, Kurt, et al.
(författare)
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Early spring development of phytoplankton in Lake Erken, Sweden, as monitored by delayed fluorescence
- 2005
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Ingår i: Verh. Internat. Verein. Limnol. ; 29, s. 377-381
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Tidskriftsartikel (refereegranskat)abstract
- A new technique, delayed fluoresence, developed within the EC-project ”Phytoplankton on line”, was used to follow the phytoplankton succession under the ice and through the ice-breakup in Lake Erken, Sweden. The monitoring was done automatically with high frequency measurements. A complementary weekly monitoring of chlorophyll a, phytoplankton composition and nutrient concentrations was performed and used to interprete the results.An interesting diurnal pattern of delayed fluorescence was shown under the ice and getting stronger as the light conditions improved through the melting of the snow and ice cover. Peaks in fluorescence occured in early morning and in late afternoon-evening.
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| 43. |
- Pettersson, Kurt, et al.
(författare)
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Horizontal distribution patterns during a cyanobacterial bloom
- 1995
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Ingår i: WATER SCIENCE AND TECHNOLOGY. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0273-1223. ; 32:4, s. 139-142
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Tidskriftsartikel (refereegranskat)abstract
- A hierarchical sampling was performed in order to give a picture of the horizontal distribution of cyanobacterial colonies. It showed how the importance of different scales in distance changed during the summer bloom of Gloeotrichia echinulata in the mode
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| 44. |
- Pettersson, Kurt
(författare)
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Mechanisms for internal loading of phosphorus in lakes
- 1998
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Ingår i: HYDROBIOLOGIA. - : KLUWER ACADEMIC PUBL. - 0018-8158. ; 374, s. 21-25
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Tidskriftsartikel (refereegranskat)abstract
- Lake sediments play an important role in the phosphorus metabolism in lakes. The impact depends on the tendencies to retain and to release phosphorus. The internal loading will often determine the eutrophication status of the lake and the time lag for rec
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| 45. |
- Pettersson, Kurt, et al.
(författare)
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NeuFlex compared with Sutter prostheses : A blind, prospective, randomised comparison of Silastic metacarpophalangeal joint prostheses
- 2006
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Ingår i: Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery. - Oslo : Taylor & Francis. - 0284-4311 .- 1651-2073. ; 40:5, s. 284-290
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Tidskriftsartikel (refereegranskat)abstract
- Forty patients (156 metacarpophalangeal joints) with mutilating rheumatoid arthritis were randomly allocated in a blinded manner to have either NeuFlex or Sutter implants. Indications for operation were pain and severe deformity. Thirty-nine patients were followed up postoperatively for one year. An independent physiotherapist and occupational therapist examined each one. Grip strength, range of motion, and pain during activity and at rest were measured. The Canadian Occupational Performance Measure (COPM) assessed the patients' evaluation of their occupational performance. Both groups had overall good results, but it seems that though patients' mobility and grip strength improve considerably, pain seems to do so only relatively. Most patients seem to be satisfied with the operation and their functional gain. Five out of 78 Sutter and two out of 78 NeuFlex implants broke. We found no major differences between the two designs, but the patients in the NeuFlex group seemed to be more satisfied with their occupational performance (COPM performance) ( p = 0.05).
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| 46. |
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| 47. |
- Pettersson, Kurt, et al.
(författare)
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Pyrolytic Carbon Hemiarthroplasty in the Management of Proximal Interphalangeal Joint Arthritis
- 2015
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Ingår i: Journal of Hand Surgery-American Volume. - : Elsevier BV. - 0363-5023 .- 1531-6564. ; 40:3, s. 462-468
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Tidskriftsartikel (refereegranskat)abstract
- Purpose To review clinical, subjective, and radiographic results of pyrocarbon hemiarthroplasty for proximal interphalangeal (PIP) joint arthritis. Methods A total of 42 fingers in 38 patients underwent PIP joint hemiarthroplasty between 2005 and 2011. Preoperative diagnoses included 28 with osteoarthritis or posttraumatic arthritis and 10 with inflammatory arthritis. Average age at the time of surgery was 56 years. Digits treated included: index (10), middle (20), ring (9), and little (3). Average follow-up was 4.6 years (minimum, 2 y). Results There was considerable improvement in patient satisfaction measures including Canadian Occupational Performance Measure for both performance and satisfaction and Disabilities of the Arm, Shoulder, and Hand and visual analog scale pain scores. There was no significant change in motion or grip and pinch strength after surgery. Four joints were revised for failure: 3 underwent arthrodesis and 1 was converted to a silicone PIP joint arthroplasty. Radiographic outcomes in surviving implants demonstrated a Sweets and Stern grade 0 in 37 implants and grade 3 in 1. Conclusions Pyrocarbon hemiarthroplasty appears to be a viable alternative to total joint arthroplasty in the treatment of PIP joint arthritis. Clinical and patient satisfaction outcomes compared favorably with published outcomes of arthroplasty. Radiographic outcomes of PIP joint hemiarthroplasty were encouraging with respect to implant position and loosening. Compared with total joint arthroplasty, proximal hemiarthroplasty is a simple procedure that preserves more bone stock and would allow for better success of salvage options such as arthrodesis and revision arthroplasty. Copyright (C) 2015 by the American Society for Surgery of the Hand. All rights reserved.
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| 48. |
- Pettersson, Kurt, et al.
(författare)
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Replacement of proximal interphalangeal joints with new ceramic arthroplasty : a prospective series of 20 proximal interphalangeal joint replacements
- 2006
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Ingår i: Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery. - Oslo : Taylor & Francis. - 0284-4311 .- 1651-2073. ; 40:5, s. 291-296
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Tidskriftsartikel (refereegranskat)abstract
- A prospective consecutive series of 20 proximal interphalangeal ( PIP) joints replaced with a new ceramic unconstrained prosthesis (MOJE) included 13 patients with osteoarthrosis, five with rheumatoid arthritis, and one each with posttraumatic infection and traumatic arthrosis. All patients were assessed preoperatively and postoperatively at one year by an independent physiotherapist and an occupational therapist who evaluated grip strength, range of motion, activities of daily living (ADL) and occupational scores (COPM Canadian Occupational Performance Measure). The mean range of motion of the PIP joint improved from 438 to 608 ( p = 0.001), and the mean grip strength from 169 - 199 N ( p = 0.002). The patients' self-perception of occupational performance, assessed by the COPM, improved significantly from 3.6 - 6.6 (p< 0.001) for satisfaction, and 3.8 - 6.3 (p< 0.001) for performance. The MOJE PIP joint replacement provides significant pain relief, improved strength and range of motion, and short-term satisfaction. Further long-term studies are therefore advocated.
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| 49. |
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| 50. |
- Pettersson, Kurt, 1964-
(författare)
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Whiplash injury : a clinical, radiographic and psychological investigation
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Whiplash injury is a common and troublesome disorder and approximately 10-40 per cent of its victims develop chronic symptoms. The annual incidence is estimated at 1/1000 inhabitants and the prevalence at 1%. The cause of chronic symptoms after whiplash injury is still unknown and no effective treatment has been presented so far.The present study is divided into two parts; the first part includes clinical, radiographic and psychological investigations, and the second part the effect of surgical intervention as well as intervention with medication.MRI studies (n=39) showed a larger proportion of pathologic findings compared to normal subjects, but no correlation with initial neurologic deficits was found. At the 2-year follow-up all patients with disc herniations with medullary impingement had persistent symptoms. Three patients had disc herniations that deteriorated from slight and moderate initial changes on the MRI to severe changes with medullary cord impingement. This deterioration might be a first sign of disc degeneration. Thus our results indicate that disc pathology is a contributing factor in the development of chronic symptoms.Measurements from standard lateral radiographs taken in neutral position were evaluated (n=48). A graphic digitizer connected to a microcomputer was used and the sagittal diameters were determined. Multivariate analysis of variance showed that the spinal canal was significantly smaller in patients with persistent symptoms indicating that a narrow spinal canal is unfavourable in patients subjected to whiplash injury.A psychological investigation (n=70) revealed no relationship between pre-existing personality traits and persistent symptoms. In our study, whiplash patients showed no differences in personality traits compared to normal controls.Our results after discectomy and anterior cervical fusion (n=20) because of chronic symptoms after whiplash injury were not satisfactory. We noticed that about half of the cases had less headache and neck pain but no beneficial effects on radicular pain, vertigo, visual and auditory symptoms were observed. Based on the criteria of a surgical evaluation, two patients were classified as good, nine as fair and nine as poor.A prospective randomised double-blind study of high-dose methyl-prednisolone compared to placebo was conducted (n=40). A clinical follow-up with repeated neurological examinations and a standardised questionnaire including VAS-scales and a pain sketch form were used for the evaluation of initial symptoms, before drug administration and at the follow-ups at 2 weeks, 6 weeks, and 6 months after the injury. At the 6-month follow-up there was a significant difference between the actively treated patients and placebo concerning disabling symptoms defined as inability to return to previous work, number of sick-days and sick-leave profile. All the actively treated patients had returned to work and none had multiple symptoms though three of them complained of intermittent neck pain. Our conclusion is therefore that acute treatment with high-dose corticosteroids might be beneficial to the prevention of disabling symptoms after whiplash injury.
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