| 61. |
- Sandén, Bengt, et al.
(författare)
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Hydroxyapatite coating enhances fixation of loaded pedicle screws : a mechanical in vivo study in sheep
- 2001
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Ingår i: European spine journal. - : Springer Science and Business Media LLC. - 0940-6719 .- 1432-0932. ; 10:4, s. 334-9
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Tidskriftsartikel (refereegranskat)abstract
- Loosening of the pedicle screws with subsequent non-union or loss of correction is a frequent problem in spinal instrumentation. In a clinical pilot study, coating of pedicle screws with plasma-sprayed hydroxyapatite (HA) resulted in a significant increase of removal torque. An experimental study was performed to investigate the effects of HA coating on the pull-out resistance. Thirteen sheep were operated on with destabilising laminectomies at two levels, L2-L3 and L4-L5. Two instrumentations with four pedicle screws in each were used for stabilisation. Uncoated screws (stainless steel) or the same type of screws coated with plasma-sprayed HA were used in either the upper or the lower instrumentation in a randomised fashion. Four sheep were examined immediately after the application of the screws, three sheep at 6 weeks and four sheep at 12 weeks. Two sheep were euthanised early due to complications. The pull-out resistance was recorded in two HA-coated and two standard screws in each animal. The maximum pull-out resistance was higher for the HA-coated screws at 0 weeks (P< 0.02) and at 12 weeks (P<0.01) when compared to the uncoated screws, while there was no significant difference between the groups at 6 weeks. We believe that the higher pull-out resistance for HA-coated screws at 0 weeks was mainly caused by differences in surface roughness, while the difference at 12 weeks was due to a favourable bone reaction around the HA-coated screws. At 12 weeks, the average stiffness was significantly higher for the HA-coated screws, while there was no significant differences in stiffness between the two screw types at 0 and 6 weeks. Energy to failure was significantly higher for coated screws when compared to the uncoated screws at all three time points. HA coating improves fixation of loaded pedicle screws, with increased pull-out resistance and reduced risk of loosening.
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| 62. |
- Sandén, Bengt, et al.
(författare)
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Hydroxyapatite coating improves fixation of pedicle screws : A clinical study
- 2002
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Ingår i: Journal of Bone and Joint Surgery. - 0301-620X .- 2044-5377. ; 84:3, s. 387-91
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the effects of hydroxyapatite (HA) coating on the purchase of pedicle screws. A total of 23 consecutive patients undergoing lumbar fusion was randomly assigned to one of three treatment groups. The first received uncoated stainless-steel screws, the second screws which were partly coated with HA, and the third screws which were fully coated. The insertion torque was recorded. After 11 to 16 months, 21 screws had been extracted. The extraction torque was recorded. Radiographs were taken to assess fusion and to detect loosening of the screws. At removal, the extraction torques exceeded the upper limit of the torque wrench (600 Ncm) for many HA-coated screws. The calculated mean extraction torque was 29 +/- 36 Ncm for the uncoated group, 447 +/- 114 Ncm for the partly-coated group and 574 +/- 52 Ncm for the fully-coated group. There were significant differences between all three groups (p < 0.001). There were more radiolucent zones surrounding the uncoated screws than the HA-coated screws (p < 0.001). HA coating of pedicle screws resulted in improved fixation with reduced risk of loosening of the screws.
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| 63. |
- Sandén, Bengt, et al.
(författare)
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Improved bone-screw interface with hydroxyapatite coating : an in vivo study of loaded pedicle screws in sheep
- 2001
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Ingår i: Spine. - 0362-2436 .- 1528-1159. ; 26:24, s. 2673-8
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Tidskriftsartikel (refereegranskat)abstract
- STUDY DESIGN: An in vivo sheep model with loaded pedicle screws was used, wherein each animal served as its own control. OBJECTIVES: To examine the effects of hydroxyapatite (HA) coating on the bone-to-implant interface in loaded spinal instrumentations. SUMMARY OF BACKGROUND DATA: Spinal instrumentation improves the healing rate in spinal fusion, but screw loosening constitutes a problem. HA coating of other implants has resulted in favorable effects on the bone-to-implant interface. METHODS: Nine sheep were operated on with destabilizing laminectomies at two levels: L2-L3 and L4-L5. Each level was stabilized separately with a four-screw instrumentation. Uncoated screws (stainless steel) or the same type of screws coated with plasma-sprayed HA were used in either the upper or the lower instrumentation in a randomized fashion. The animals were killed at 6 or 12 weeks after surgery. The specimens were embedded in resin, ground to approximately 10 microm, and stained with toluidine blue. Histomorphometric evaluation was carried out in a Leitz Aristoplan (Wetzlar, Germany) light microscope equipped with a Leitz Microvid unit. RESULTS: The average percentage of bone-to-implant contact after 6 weeks was 69 +/- 10 for the HA-coated screws and 18 +/- 11 for the uncoated screws (P < 0.03), and after 12 weeks 64 +/- 31 (HA-coated) and 9 +/- 13 (uncoated, P < 0.02). The average bone volume in the area close to the screw was significantly higher for the HA-coated screws at both 6 and 12 weeks. CONCLUSIONS: HA coating improved the bone-to-implant interface significantly, indicating that HA coating can become useful for improving the purchase of pedicle screws.
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| 64. |
- Sandén, Bengt, et al.
(författare)
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Improved extraction torque of hydroxyapatite-coated pedicle screws
- 2000
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Ingår i: European spine journal. - : Springer Science and Business Media LLC. - 0940-6719 .- 1432-0932. ; 9:6, s. 534-7
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Tidskriftsartikel (refereegranskat)abstract
- Loosening of the screws is a problem in instrumentation with pedicle screws. Coating with hydroxyapatite improves the holding characteristics for metal implants, but the possible effects on the anchorage of pedicle screws have not been described. In this study, seven patients were operated on with spinal instrumentation using four stainless steel pedicle screws. Hydroxyapatite-coated screws were used in either the upper or the lower of the instrumented levels. The insertion torque was measured. In four cases the screws were removed after 10-22 months and the extraction torque was measured. The mean insertion torque was found to be significantly greater in the hydroxyapatite-coated screws (107 Ncm) than in the standard screws (76 Ncm). In three cases, the extraction torque for the hydroxyapatite-coated screws exceeded the range for the torque wrench (600 Ncm), while the conventional screws were loose (< 5 Ncm). In one case, the extraction torque was 475 and 550 Ncm for the coated screws, and 5 and 25 Ncm for the conventional screws. The difference in extraction torque was significant. Hydroxyapatite coating was shown to have improved the purchase of pedicle screws very effectively. By using fully coated screws, as in the present study, extraction was extremely difficult compared to extraction of conventional stainless steel screws, which were regularly loose. By reducing the area of the screws that is coated, it may be possible to achieve an enhanced purchase while extraction will be easier when compared to fully coated screws.
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| 65. |
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| 66. |
- Skeppholm, Martin, et al.
(författare)
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Comparison of dysphagia between cervical artificial disc replacement and fusion : data from a randomized controlled study with two years of follow-up
- 2013
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Ingår i: Spine. - 0362-2436 .- 1528-1159. ; 38:24, s. E1507-E1510
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Tidskriftsartikel (refereegranskat)abstract
- STUDY DESIGNProspective randomized controlled trial.OBJECTIVETo determine and explain any differences in self-reported dysphagia between patients treated with artificial disc replacement and anterior cervical decompression and fusion (ACDF).SUMMARY OF BACKGROUND DATADysphagia after anterior cervical spine surgery has in previous studies been evaluated regarding different influencing factors. Surgical technique, number of treated levels, and type of implant has been shown to be of possible importance.METHODSOne hundred thirty-six patients from a randomized controlled trial between artificial disc replacement and ACDF in 1 or 2 surgical levels were evaluated regarding dysphagia. Evaluation was done with the dysphagia short questionnaire preoperatively, at 4 weeks, 3 months, and 1 and 2 years postoperatively. Reconstruction in the artificial disc replacement group was performed with the Discover artificial disc. Bone graft and anterior plating was used in the ACDF group. Type of implant was blinded to the patients and the surgeon until time of implantation.RESULTSDemographics and dysphagia short questionnaire levels were similar in both groups preoperative. At 4 weeks of follow-up postoperatively, dysphagia was significantly higher in both groups than baseline levels, P < 0.01. No significant differences were seen between the groups until follow-up at 2 years, which showed significantly higher dysphagia short questionnaire levels in the ACDF group, P = 0.04. The difference was statistically significant in both patients treated with 1- and 2-level surgery, P = 0.029 and P = 0.032, respectively. A logistic regression model showed a stronger association to type of implant than to number of surgical levels. Duration of surgery was highly associated to number of surgical levels but did not differ significantly between types of implant.CONCLUSIONLong-term postoperative dysphagia could be explained by bulk of implant or decreased motion in the cervical spine. However, it is doubtful if differences between the groups in this study can be interpreted as a clinically important difference.
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| 67. |
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| 68. |
- Skeppholm, Martin, et al.
(författare)
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Evaluation of mobility and stability in the Discover artificial disc : an in vivo motion study using high-accuracy 3D CT data
- 2015
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Ingår i: Journal of Eurosurgery. - : AMER ASSOC NEUROLOGICAL SURGEONS. - 1547-5654 .- 1547-5646. ; 23:3, s. 383-389
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Tidskriftsartikel (refereegranskat)abstract
- OBJECT Artificial disc replacement (ADR) devices are unlike implants used in cervical fusion in that they are continuously exposed to stress not only within the implant site but also at their site of attachment to the adjacent vertebra. An imaging technique with higher accuracy than plain radiography and with the possibility of 3D visualization would provide more detailed information about the motion quality and stability of the implant in relation to the vertebrae. Such high-accuracy studies have previously been conducted with radiostereometric analysis (RSA), which requires implantation of tantalum markers in the adjacent vertebrae. The aim of this study was to evaluate in vivo motion and stability of implanted artificial discs. A noninvasive analysis was performed with CT, with an accuracy higher than that of plain radiographs and almost as high as RSA in cervical spine. METHODS Twenty-eight patients with ADR were included from a larger cohort of a randomized controlled trial comparing treatment of cervical radiculopathy with ADR or anterior cervical decompression and fusion. Surgical levels included C4-7; 18 patients had 1-level surgery and 10 patients had 2-level surgery. Follow-up time ranged from 19 to 50 months, with an average of 40 months. Two CT volumes of the cervical spine, 1 in flexion and 1 in extension, were obtained in each patient and then spatially registered using a customized imaging tool, previously used and validated for the cervical spine. Motion between the components in the artificial disc, as well as motion between the components and adjacent vertebrae, were calculated in 3 planes. Intraclass correlation (ICC) between independent observers and repeatability of the method were also calculated. RESULTS Intrinsic motion, expressed as degrees in rotation and millimeters in translation, was detectable in a majority of the ADRs. In the sagittal plane, in which the flexion/extension was performed, sagittal rotation ranged between 0.2 and 15.8 and translation between 0.0 and 5.5 mm. Eight percent of the ADRs were classified as unstable, as motion between at least 1 of the components and the adjacent vertebra was detected. Five percent were classified as ankylotic, with no detectable motion, and another 8% showed very limited motion due to heterotopic ossification. Repeatability for the motion in the sagittal plane was calculated to be 1.300 for rotation and 1.29 mm for translation (95% confidence level), ICC 0.99 and 0.84, respectively. All 3 patients with unstable devices had undergone 1-level ADRs at C5-6. They all underwent revision surgery due to increased neck pain, and instability was established during the surgery. CONCLUSIONS The majority of the artificial discs in this study showed intrinsic mobility several years after implantation and were also shown to be properly attached. Implant instability was detected in 8% of patients and, as all of these patients underwent revision surgery due to increasing neck pain, this might be a more serious problem than heterotopic bone formation.
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| 69. |
- Skeppholm, M, et al.
(författare)
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Pain from donor site after anterior cervical fusion with bone graft : a prospective randomized study with 12 months of follow-up
- 2013
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Ingår i: European spine journal. - : Springer Science and Business Media LLC. - 0940-6719 .- 1432-0932. ; 22:1, s. 142-147
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION:Harvesting bone graft from the iliac crest in spinal fusion surgery is a widely used technique. However, complications can occur and there are also reports of patients with persistent graft site pain after surgery. The aim of this study was to evaluate pain from the donor site (DS) over time, and register associated complications and if it affected health-related quality of life (HRQoL).MATERIAL AND METHODS:One hundred and seven patients participating in an RCT between two different methods of reconstruction after cervical decompression were included in this study. One group underwent surgery with bone graft (BG) from the iliac crest and the other with no bone graft (NBG). All patients were evaluated concerning pain at DS and HRQoL preoperatively, at 4 weeks, 3 months and 1 year. Pain was evaluated with visual analog scale (VAS) and HRQoL with EQ-5D.RESULTS: A statistically significant difference was found at all times of follow-up in the BG group compared to preoperative levels and the NBG group. The VAS levels at follow-ups at 3 months and 1 year were however of questionable clinical importance. Two patients in the BG group had superficial wound infections postoperatively and five patients still had sensory disturbance in the area of graft site at 12 months. No major complications were registered. No difference could be seen in EQ-5D at any time of follow-up between the groups.CONCLUSION:Harvesting of iliac crest bone graft is associated with significant pain. However, at 3 months postoperatively, the negative effect of clinical importance seemed to have disappeared compared to when no bone graft was harvested. The pain from bone graft harvesting does not seem to affect the quality of life at 4 weeks postoperatively and onward.
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| 70. |
- Skeppholm, Martin, et al.
(författare)
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The association between preoperative mental distress and patient-reported outcome measures in patients treated surgically for cervical radiculopathy
- 2017
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Ingår i: The spine journal. - : Elsevier BV. - 1529-9430 .- 1878-1632. ; 17:6, s. 790-798
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND CONTEXT: Previous research indicates that there might exist a link between the experience of pain and mental distress. Pain can possibly trigger anxiety and chronic pain, as well as also depression. On the other hand, anxiety and depression might also be risk factors for painful conditions and more pronounced subsequent disability and thus, the pathways may be bidirectional. Expanded knowledge of how different factors affect pain and function may help surgeons in preoperative decision-making.PURPOSE: The aim of this study was to evaluate the impact of potential preoperative risk factors with special reference to mental distress.STUDY DESIGN/SETTING: This is a prospective outcome study in a cohort from a multicenter randomized controlled trial comparing anterior cervical decompression and fusion with disc replacement.PATIENT SAMPLE: The sample included 151 patients with cervical radiculopathy planned for surgery.OUTCOME MEASURES: Surgical outcome was evaluated with Neck Disability Index (NDI), health related quality-of-life with European Quality of Life-5 Dimensions, and pain with visual analogue scale for arm and neck. Mental distress was preoperatively measured with the Hospital Anxiety and Depression (HAD) scale.METHODS: Preoperative data regarding possible risk factors for poor outcome were analyzed in multiple linear regression models with postoperative NDI and change of NDI as dependent factors. Patients with high preoperative levels of anxiety or depression (H-HAD), indicating mental distress, were compared with patients scoring low/moderate levels (L-HAD) regarding patient-reported outcome measures (PROMs) preoperatively and at 1- and 2-year follow-up.RESULTS: Outcome data were available for 136 patients at the 2-year follow-up. No statistically significant difference in any outcome data could be demonstrated between the two surgical treatment groups. Mental distress was the variable most strongly associated with NDI at 2 years in the regression analysis. There were 42 patients classified as H-HAD and 94 as L-HAD. The average improvement in NDI was 16.9 in the H-HAD group and 26.3 in the L-HAD group, p=.02. The H-HAD patients showed a tendency for poorer baseline data and worse outcome overall in all PROMs at follow-up at both 1 and 2 years.CONCLUSIONS: Preoperative mental distress measured with HAD was associated with worse outcome overall. More research is needed to investigate whether patients with mental distress may achieve better results if other treatments are offered, either as non-surgical treatment alone or as an adjunct to surgery.
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