| 1. |
- Hareni, Niyaz, et al.
(author)
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Back pain is also improved by lumbar disc herniation surgery
- 2021
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In: Acta Orthopaedica. - : Taylor & Francis. - 1745-3674 .- 1745-3682. ; 92:1, s. 4-8
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Journal article (peer-reviewed)abstract
- Background and purpose: Indication for lumbar disc herniation (LDH) surgery is usually to relieve sciatica. We evaluated whether back pain also decreases after LDH surgery.Patients and methods: In the Swedish register for spinal surgery (SweSpine) we identified 14,097 patients aged 20-64 years, with pre- and postoperative data, who in 2000-2016 had LDH surgery. We calculated 1-year improvement on numeric rating scale (rating 0-10) in back pain (Nback) and leg pain (Nleg) and by negative binomial regression relative risk (RR) for gaining improvement exceeding minimum clinically important difference (MCID).Results: Nleg was preoperatively (mean [SD]) 6.7 (2.5) and Nback was 4.7 (2.9) (p < 0.001). Surgery reduced Nleg by mean 4.5 (95% CI 4.5-4.6) and Nback by 2.2 (CI 2.1-2.2). Mean reduction in Nleg) was 67% and in Nback 47% (p < 0.001). Among patients with preoperative pain ≥ MCID (that is, patients with significant baseline pain and with a theoretical possibility to improve above MCID), the proportion who reached improvement ≥ MCID was 79% in Nleg and 60% in Nback. RR for gaining improvement ≥ MCID in smokers compared with non-smokers was for Nleg 0.9 (CI 0.8-0.9) and -Nback 0.9 (CI 0.8-0.9), and in patients with preoperative duration of back pain 0-3 months compared with > 24 months for Nleg 1.3 (CI 1.2-1.5) and for Nback 1.4 (CI 1.2-1.5).Interpretation: LDH surgery improves leg pain more than back pain; nevertheless, 60% of the patients with significant back pain improved ≥ MCID. Smoking and long duration of pain is associated with inferior recovery in both Nleg and Nback.
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| 2. |
- Hareni, Niyaz, et al.
(author)
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Predictors of satisfaction after lumbar disc herniation surgery in elderly
- 2019
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In: BMC Musculoskeletal Disorders. - : Springer Science and Business Media LLC. - 1471-2474. ; 20:1, s. 1-6
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Journal article (peer-reviewed)abstract
- BACKGROUND: The aim of this study was to evaluate satisfaction and factors associated with satisfaction in elderly undergoing lumbar disc herniation surgery.METHODS: In the national Swedish register for spinal surgery (SweSpine) we identified 2095 patients aged > 65 years (WHO definition of elderly) whom during 2000-2016 had undergone LDH surgery and had pre- and one-year postoperative data (age, gender, preoperative duration and degree of back- and leg pain, quality of life (SF-36) and one-year satisfaction (dissatisfied, uncertain, satisfied). We utilized a logistic regression model to examine preoperative factors that were independently associated with low and high satisfaction and after LDH surgery.RESULTS: One year after surgery, 71% of the patients were satisfied, 18% uncertain and 11% dissatisfied. Patients who were satisfied were in comparison to others, younger, had shorter preoperative duration of leg pain, higher SF-36 mental component summary and more leg than back pain (all p < 0.01). Patients who were dissatisfied were compared to others older, had longer preoperative duration of leg pain and lower SF-36 scores (all p < 0.01). 81% of patients with leg pain up to 3 months were satisfied in comparison with 57% of patients with leg pain > 2 years (p < 0.001).CONCLUSION: Only one out of ten elderly, is dissatisfied with the outcome of LDH surgery. Age, preoperative duration of leg pain, preoperative SF 36 score, and for satisfaction also dominance of back over leg pain, are in elderly factors associated to good and poor subjective outcome after LDH surgery.
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| 3. |
- STRÖMQVIST, FREDRIK, et al.
(author)
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Dural lesions in decompression for lumbar spinal stenosis: incidence, risk factors and effect on outcome.
- 2012
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In: European Spine Journal. - : Springer Science and Business Media LLC. - 0940-6719 .- 1432-0932. ; 21:5, s. 825-828
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Journal article (peer-reviewed)abstract
- INTRODUCTION: Decompression for lumbar spinal stenosis is one of the most frequent operations on the spine today. The most common complication seems to be a peroperative dural lesion. There are few prospective studies on this complication regarding incidence and effect on long-term outcome; this is the background for the current study. MATERIALS AND METHODS: Swespine, the Swedish Spine Register documents the majority (>80%) of lumbar spine operations in Sweden today. Within the framework of this register, totally 3,699 operations for spinal stenosis during a 5-year period were studied regarding complications and 1-year postoperative outcome. Mean patient age was 66 (37-92) years and 44% were males. Fourteen percent were smokers and 19% had undergone previous lumbar spine surgery. RESULTS: The overall incidence of a peroperative dural lesion was 7.4%, 8.5% of patients undergoing decompressive surgery only and 5.5% of patients undergoing decompressive surgery + fusion (p < 0.001). A logistic regression analysis demonstrated that (high) age (p < 0.0004), previous surgery (p < 0.036) and smoking (p < 0.049) were significantly predictive factors for dural lesions. An odds ratio estimate demonstrated an age-related risk increase with 2.7% per year. The risk for dural lesions also increased with number of levels decompressed. The 1-year outcome was identical in the two groups with and without a dural lesion. CONCLUSION: A dural lesion was seen in 7.4% of decompressive operations for spinal stenosis. High age, previous surgery and smoking were risk factors for sustaining a lesion, which, however, did not affect the 1-year outcome negatively.
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| 4. |
- STRÖMQVIST, FREDRIK, et al.
(author)
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Dural lesions in lumbar disc herniation surgery: incidence, risk factors, and outcome.
- 2010
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In: European Spine Journal. - : Springer Science and Business Media LLC. - 0940-6719 .- 1432-0932. ; 19:3, s. 439-442
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Journal article (peer-reviewed)abstract
- In lumbar disc herniation surgery, dural lesions seem to be the most common complication today. Studies on incidence of and outcome after a dural lesion are mainly based on retrospective studies. In a prospective study within the framework of the Swedish Spine Register, 4,173 patients operated on for lumbar disc herniation were evaluated using pre- and 1-year postoperative protocols and complication registration. Mean patient age was 41 (18-81) years and 53% of the patients were male. 93% of the operations were performed on the two lowermost lumbar levels. The incidence of dural lesions in the material was 2.7%. In patients with previous disc surgery, the incidence was doubled, 5%, a significant increase (P = 0.02). Patients with dural lesions preoperatively had more back pain and inferior scores in general health and role emotional domains of the SF-36. These factors, however, were because they had been operated on previously, not related to the dural lesion as such. The relative improvement after surgery was similar whether a dural lesion had occurred or not. It is concluded that a dural lesion is a technical complication which must be solved at the time of surgery but which does not bear any negative implications on the long-term outcome for the patient.
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| 5. |
- Strömqvist, Fredrik, et al.
(author)
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Gender differences in lumbar disc herniation surgery
- 2008
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In: Acta Orthopaedica. - Basingstoke, Hampshire, UK : Medical Journals Sweden AB. - 1745-3682 .- 1745-3674. ; 79:5, s. 643-649
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Journal article (peer-reviewed)abstract
- BACKGROUND AND PURPOSE: Although there have been numerous publications on lumbar disc herniation (LDH) treated surgically, there has been little interest in sex differences. It has been shown in many studies that sex differences may be important in certain diseases. We therefore reviewed consecutive register material from one institution for possible gender differences in pre- and postoperative parameters in patients operated for lumbar disc herniation.PATIENTS AND METHODS: Pre- and postoperative parameters for all patients operated on at the Department of Orthopedics, Lund University Hospital over 6 years (2000-2005 inclusive) (301 patients, 165 males) were analyzed regarding sex differences.RESULTS: Statistically significant and clinically relevant sex differences were found. Preoperatively, females had more pronounced back pain and disability, and also lower quality of life in some respects. At 1-year followup, females reported a higher rate of consumption of analgesics, a higher degree of postoperative back and leg pain, and less improvement regarding disability and some aspects of quality of life. Relative improvement, rate of return to work, and satisfaction with the outcome of surgery were not, however, statistically significantly different between females and males.INTERPRETATION: There are statistically significant differences between the sexes in lumbar disc herniation surgery regarding basic demographic status and postoperative status, whereas the surgical effect is similar. Further investigations should focus on whether there is a true sex difference or whether these differences are due to selection for surgery, differences in proneness to seek medical advice or to accept/choose surgery, or other unknown factors.
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| 6. |
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| 7. |
- Strömqvist, Fredrik, et al.
(author)
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Gender differences in the surgical treatment of lumbar disc herniation in elderly
- 2016
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In: European Spine Journal. - : Springer Science and Business Media LLC. - 0940-6719 .- 1432-0932. ; 25:11, s. 3528-3535
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Journal article (peer-reviewed)abstract
- Purpose: Outcome after lumbar disc herniation (LDH) surgery in middle-aged patient is usually reported to fulfill the criteria for successful outcome. It is also known that women in these years have an inferior outcome compared to men. This study evaluates whether the same gender differences exist in elderly. Method: In the national Swedish register for spine surgery (SweSpine) we identified 1668 patients ≥65 years. 1250 of these patients had both pre- and 1-year postoperative data registered, 53 % males with mean age 70.6 ± 5.0 (mean ± SD) and 47 % females with mean age 71.3 ± 5.2. All were surgically treated due to LDH between 2000 and 2012. Results: Before surgery both men and women had severe impairment, compared to normative data, in all patient-reported outcome measures (PROMs), with women having inferior status to men. Improvement by surgery was similar in both genders but neither of them reached normative values in quality of life as compared to normative age-matched individuals. As a consequence of this women 1 year after surgery had more back and leg pain, higher consumption of analgesics, greater impairment in walking distance and inferior scoring in virtually all registered PROMs compared to men (all p <0.005). In spite of this women were as satisfied with the surgical outcome as the men. Conclusion: Elderly women with LDH surgery report inferior outcome compared to males, mainly as a result of being referred to surgery with an inferior status but are despite this as satisfied with outcome as the men.
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| 8. |
- Strömqvist, Fredrik, et al.
(author)
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Incidental durotomy in degenerative lumbar spine surgery – a register study of 64,431 operations
- 2019
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In: Spine Journal. - : Elsevier BV. - 1529-9430 .- 1878-1632. ; 19:4, s. 624-630
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Journal article (peer-reviewed)abstract
- BACKGROUND: Incidental durotomy (ID) is one of the most common intraoperative complications seen in spine surgery. Conflicting evidence has been presented regarding whether or not outcomes are affected by the presence of an ID. PURPOSE: To evaluate whether outcomes following degenerative spine surgery are affected by ID and the incidence of ID with different diagnoses and different surgical procedures. MATERIALS: By using SweSpine, the national Swedish Spine Surgery Register, preoperative, surgical and postoperative 1-year follow-up data were obtained for 64,431 surgeries. All patients were surgically treated due to lumbar spinal stenosis (LSS) without or with concomitant degenerative spondylolisthesis (DS) or lumbar disc herniation (LDH) between 2000 and 2015. Gender, age, smoking habits, walking distance, consumption of analgesics, back and leg pain (Visual Analogue Scale [VAS]), quality of life (EuroQol [EQ5D] and Short Form 36 [SF-36]), and disability (Oswestry Disability Index [ODI]) were recorded. RESULTS: Overall, incidence of ID during the study period was 5.0%. For the LDH, LSS, and DS subgroups, it was 2.8%, 6.5%, and 6.5%, respectively. Laminectomy was associated with a higher incidence of ID than discectomy (p<.001). ID was more common in all three subgroups if the patient had previously been subjected to spine surgery and with increasing age of the patients (p<.001). LDH patients with an ID reported a higher degree of residual leg pain, inferior mental quality of life (SF-36 MCS), and higher disability (ODI) than LDH patients without ID (all p<.001) 1-year after surgery. LSS patients with an ID reported inferior SF-36 MCS (p<.001) and DS patients with an ID had inferior SF-36 MCS and higher ODI compared to patients with the same diagnosis but without an ID (p<.001). However, these numerical differences are well below references for MCID, for all three subgroups. ID was associated with a higher frequency of patients being dissatisfied with the surgical outcome at 1-year follow-up. In patients who did not improve in back and leg pain following surgery (delta-value), ID was less common than in patients reporting improved back and leg pain from before as compared to following surgery. CONCLUSIONS: The overall occurrence of ID in the present study was 5%, with higher figures in LSS and DS and lower figures in LDH. Higher age of the patient and previous surgery were associated with higher frequencies of ID. The outcome at 1 year following surgery was not affected to a clinically relevant extent when an ID was obtained. However, ID was associated with a higher degree of patient dissatisfaction and a longer hospital length of stay.
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| 9. |
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| 10. |
- Strömqvist, Fredrik, et al.
(author)
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Lumbar disc herniation surgery in children: outcome and gender differences.
- 2016
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In: European Spine Journal. - : Springer Science and Business Media LLC. - 0940-6719 .- 1432-0932. ; 25:2, s. 657-663
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Journal article (peer-reviewed)abstract
- Lumbar disc herniation (LDH) in children is rare. Few studies have evaluated the outcome of surgery and none in a prospective study design.
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| 11. |
- Strömqvist, Fredrik, et al.
(author)
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Outcome of surgical treatment of lumbar disc herniation in young individuals.
- 2015
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In: The Bone & Joint Journal. - 2049-4408. ; 97B:12, s. 1675-1682
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Journal article (peer-reviewed)abstract
- Lumbar disc herniation (LDH) is uncommon in youth and few cases are treated surgically. Very few outcome studies exist for LDH surgery in this age group. Our aim was to explore differences in gender in pre-operative level of disability and outcome of surgery for LDH in patients aged ≤ 20 years using prospectively collected data. From the national Swedish SweSpine register we identified 180 patients with one-year and 108 with two-year follow-up data ≤ 20 years of age, who between the years 2000 and 2010 had a primary operation for LDH. Both male and female patients reported pronounced impairment before the operation in all patient reported outcome measures, with female patients experiencing significantly greater back pain, having greater analgesic requirements and reporting significantly inferior scores in EuroQol (EQ-5D-index), EQ-visual analogue scale, most aspects of Short Form-36 and Oswestry Disabilities Index, when compared with male patients. Surgery conferred a statistically significant improvement in all registered parameters, with few gender discrepancies. Quality of life at one year following surgery normalised in both males and females and only eight patients (4.5%) were dissatisfied with the outcome. Virtually all parameters were stable between the one- and two-year follow-up examination. LDH surgery leads to normal health and a favourable outcome in both male and female patients aged 20 years or younger, who failed to recover after non-operative management. Cite this article: Bone Joint J 2015;97-B:1675-82.
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| 12. |
- Strömqvist, Fredrik, et al.
(author)
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Predictive outcome factors in the young patient treated with lumbar disc herniation surgery
- 2016
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In: Journal of Neurosurgery: Spine. - 1547-5654 .- 1547-5646. ; 25:4, s. 448-455
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Journal article (peer-reviewed)abstract
- OBJECTIVE: The aim of this study was to evaluate predictive factors for outcome after lumbar disc herniation surgery in young patients. METHODS: In the national Swedish spine register, the authors identified 180 patients age 20 years or younger, in whom preoperative and 1-year postoperative data were available. The cohort was treated with primary open surgery due to lumbar disc herniation between 2000 and 2010. Before and 1 year after surgery, the patients graded their back and leg pain on a visual analog scale, quality of life by the 36-Item Short-Form Health Survey and EuroQol-5 Dimensions, and disability by the Oswestry Disability Index. Subjective satisfaction rate was registered on a Likert scale (satisfied, undecided, or dissatisfied). The authors evaluated if age, sex, preoperative level of leg and back pain, duration of leg pain, pain distribution, quality of life, mental status, and/or disability were associated with the outcome. The primary end point variable was the grade of patient satisfaction. RESULTS: Lumbar disc herniation surgery in young patients normalizes quality of life according to the 36-Item Short- Form Health Survey, and only 4.5% of the patients were unsatisfied with the surgical outcome. Predictive factors for inferior postoperative patient-reported outcome measures (PROM) scores were severe preoperative leg or back pain, low preoperative mental health, and pronounced preoperative disability, but only low preoperative mental health was associated with inferiority in the subjective grade of satisfaction. No associations were found between preoperative duration of leg pain, distribution of pain, or health-related quality of life and the postoperative PROM scores or the subjective grade of satisfaction. CONCLUSIONS: Lumbar disc herniation surgery in young patients generally yields a satisfactory outcome. Severe preoperative pain, low mental health, and severe disability increase the risk of reaching low postoperative PROM scores, but are only of relevance clinically (low subjective satisfaction) for patients with low preoperative mental health.
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| 13. |
- Strömqvist, Fredrik, et al.
(author)
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Surgical Treatment of Lumbar Disc Herniation in Different Ages : Evaluation of 11,237 Patients
- 2017
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In: The Spine Journal. - : Elsevier BV. - 1529-9430. ; 17:11, s. 1577-1585
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Journal article (peer-reviewed)abstract
- Surgical treatment of lumbar disc herniation (LDH) may lead to different outcomes in young, middle-aged, and elderly patients. However, no study has, by the same data ascertainment, evaluated referral pattern, improvement, and outcome in different age strata.
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| 14. |
- Strömqvist, Fredrik, et al.
(author)
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The outcome of lumbar disc herniation surgery is worse in old adults than in young adults : A study of 14,090 individuals in the Swedish Spine Surgery Register (SweSpine)
- 2016
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In: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 87:5, s. 516-521
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Journal article (peer-reviewed)abstract
- Background and purpose — The outcome of surgical treatment of lumbar disc herniation (LDH) has been thoroughly evaluated in middle-aged patients, but less so in elderly patients. Patients and methods — With validated patient-reported outcome measures (PROMs) and using SweSpine (the national Swedish Spine Surgery Register), we analyzed the preoperative clinical status of LDH patients and the 1-year postoperative outcome of LDH surgery performed over the period 2000–2012. We included 1,250 elderly patients (≥ 65 years of age) and 12,840 young and middle-aged patients (aged 20–64). Results — Generally speaking, elderly patients were referred for LDH surgery with worse PROM scores than young and middle-aged patients, they improved less by surgery, they experienced more complications, they had inferior 1-year postoperative PROM scores, and they were less satisfied with the outcome (with all differences being statistically significant). Interpretation — Elderly patients appear to have a worse postoperative outcome after LDH surgery than young and middle-aged patients, they are referred to surgery with inferior clinical status, and they improve less after the surgery.
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| 15. |
- Hareni, Niyaz, et al.
(author)
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A comparison study on patient-reported outcome between obese and non-obese patients with central lumbar spinal stenosis undergoing surgical decompression : 14,984 patients in the National Swedish Quality Registry for Spine Surgery
- 2022
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In: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 93, s. 880-886
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Journal article (peer-reviewed)abstract
- Background and purpose — Obesity has been associated with inferior outcomes after laminectomy due to central lumbar spinal stenosis (CLSS); we evaluated whether this occurs in surgery on national bases. Patients and methods — We retrieved pre-and 1-year postoperative data from the National Swedish Quality Registry for Spine Surgery regarding patients aged ≥ 50 with laminectomy due to CLSS in 2005–2018. 4,069 patients had normal weight, 7,044 were overweight, 3,377 had class I obesity, 577 class II obesity, and 94 class III obesity (“morbid obesity”). Patient-reported outcome included satisfaction after 1 year, leg pain (Numerical Rating Scale [NRS], rating 0–10), disability (Oswestry Disability Index [ODI], rating 0–100). Complications were also retrieved. Results — 1-year postoperatively, 69% of patient of normal weight, 67% who were overweight, and 62% with obesity (classes I–III aggregated) were satisfied (p < 0.001) and 62%, 60%, and 57% in obese groups I–III, respectively (p = 0.7). NRS leg pain improved in normal-weight patients by 3.5 (95% CI 3.4–3.6), overweight by 3.2 (CI 3.1–3.2), and obese by 2.6 (CI 2.5–2.7), and 2.8 (CI 2.7–2.9), 2.5 (CI 2.2–2.7), and 2.6 (CI 2.0–3.2) in obese classes I–III, respec-tively. ODI improved in normal weight by 19 (CI 19–20), overweight by 17 (CI 17–18), and obese by 14 (CI 13–15), and 16 (CI 15–17), 14 (CI 13–16), 14 (CI 11–18) in obese classes I–III, respectively. 8.1% of normal weight, 7.0% of overweight, and 8.1% of obese patients suffered complications (p = 0.04) and 8.1%, 7.0%, and 17% among obese classes I–III, respectively (p < 0.01). Conclusion — Most obese patients are satisfied after laminectomy due to CLSS, even if satisfaction rate is inferior compared with normal-weight patients. The morbidly obese have more complications than patients with lower BMI.
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| 16. |
- Hareni, Niyaz, et al.
(author)
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A study comparing outcomes between obese and nonobese patients with lumbar disc herniation undergoing surgery : a study of the Swedish National Quality Registry of 9979 patients
- 2022
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In: BMC Musculoskeletal Disorders. - : Springer Science and Business Media LLC. - 1471-2474. ; 23:1
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Journal article (peer-reviewed)abstract
- Background: This study aimed to evaluate whether an increasing grade of obesity is associated with inferior outcomes after lumbar disc herniation (LDH) surgery. Methods: We retrieved data from the Swedish register for spine surgery regarding patients aged 20–64 who underwent LDH surgery from 2006–2016 and had preoperative and one-year postoperative data. A total of 4156 patients were normal weight, 4063 were overweight, 1384 had class I obesity, 317 had class II obesity and 59 had class III obesity (“morbid obesity”). Data included patient satisfaction, improvement in leg pain (assessed using the National Rating Scale; NRS; rating 0–10), disability (assessed using the Oswestry Disability Index; ODI; rating 0–100) and complications. Results: At one year postsurgery, 80% of normal-weight patients, 77% of overweight patients and 74% of obese patients (class I-III evaluated together) were satisfied (p < 0.001) [75%, 71%, 75% in obesity classes I, II, and III, respectively (p = 0.43)]. On average, all groups improved by more than the minimal clinically important difference (MCID) in both NRS leg pain (> 3.5) and ODI (> 20). NRS leg pain improved by 4.8 in normal weight patients (95% CI 4.7–4.9), by 4.5 in overweight patients (4.5–4.6) and by 4.3 in obese patients (4.2–4.4) (p < 0.001) [4.4 (4.3–4.6), 3.8 (3.5–4.1) and 4.6 (3.9–5.3) in obesity classes I, II, and III, respectively (p < 0.001)]. The ODI improved by 30 in normal weight patients (30–31), by 29 in overweight patients (28–29) and by 26 in obese patients (25–27) (p < 0.001) [29 (28–29), 25 (22–27) and 27 (22–32) in obesity classes I, II, and III, respectively (p < 0.01)]. A total of 3.0% of normal-weight patients, 3.9% of overweight patients and 3.9% of obese patients suffered complications (p = 0.047) [3.8%, 4.4%, 3.5% in obesity classes I, II, and III, respectively (p = 0.90)]. Conclusions: LDH surgery is also generally associated with favourable outcomes and few complications in patients with morbid obesity.
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| 17. |
- Henriksson, Markus, et al.
(author)
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Tandem PPKTP and ZGP OPO for mid-infrared generation
- 2008
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In: Proceedings of SPIE, the International Society for Optical Engineering. - USA : SPIE - International Society for Optical Engineering. - 0277-786X .- 1996-756X. ; 7115, s. 71150O1-10
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Journal article (peer-reviewed)abstract
- Efficient laser sources in the 3-5 μrn wavelength range are needed for directed infrared countermeasures, but also have applications in remote-sensing, medicine and spectroscopy. We present new results on our tandem optical parametric oscillator (OPO) scheme for converting the radiation from a 1.06 μm Nd3+-laser to the mid-infrared. Multi Watt level output power in the 3-5 μm range at 20 kHz pulse repetition frequency is reported. Our setup uses a type I quasi phasematched PPKTP crystal in a near degenerate OPO to generate 2.13 μm radiation. A volume Bragg grating resonant close to, but not exactly at the degenerate wavelength, is used as a cavity mirror to reduce the bandwidth and ensure singly resonant operation. Both signal and idler from the PPKTP OPO are used to pump a ZGP OPO generating high power radiation in the 3-5μm region. Using this scheme for each pump photon it is possible to generate four photons for each pump photon, all in the interesting wavelength range, thus enabling high efficiency conversion.
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| 18. |
- Jang, Hoon, et al.
(author)
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Control of forward stimulated polariton scattering in periodically poled nonlinear crystals
- 2012
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In: 2012 Conference on Lasers and Electro-Optics, CLEO 2012. - Washington, D.C. : IEEE. - 9781467318396 ; , s. 6325627-
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Conference paper (peer-reviewed)abstract
- Periodic poling in KTP leads to periodic phase reversal of the polaritons generated in Cherenkov phase-matched direction. This is responsible for the dependence of stimulated Raman scattering threshold on crystal rotation angle and poling period.
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| 19. |
- Joelson, Anders, 1970-, et al.
(author)
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Single item self-rated general health : SF-36 based observations from 16,910 spine surgery procedures
- 2022
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In: Quality of Life Research. - : Springer. - 0962-9343 .- 1573-2649. ; 31:6, s. 1819-1828
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Journal article (peer-reviewed)abstract
- PURPOSE: In spine surgery single item patient-reported outcome assessment has been used for many years. Items 1 and 2 of SF-36 are used for assessment of general health. We used these items to explore single item, self-rated, general health assessment after spine surgery.METHODS: Patients operated for lumbar disc herniation or lumbar spinal stenosis between 2007 and 2017, were recruited from the national Swedish spine register. A total of 16,910 procedures were eligible for analysis. The responsiveness of the SF-36 general health assessment items to surgical treatment was evaluated with the standardized response mean (SRM). Improvement in self-rated general health was used to dichotomize SF-36 profiles and EQ VAS distributions.RESULTS: For disc herniation, 5852 (83%) patients reported improvement in general health 1 year after surgery. For spinal stenosis, the corresponding numbers were 6,482 (66%). The additional improvement after year 1 was small. The responsiveness of the SF-36 item 2 (the health transition item) to surgical treatment of disc herniation or spinal stenosis was substantial. There was a clear association between improvement in SF-36 item 2 and improvements in all domains of SF-36.CONCLUSIONS: Surgery for disc herniation or spinal stenosis improve patients' perception of general health 1 year after surgery. The improvement in general health after year 1 is limited. The SF-36 item 2 is a responsive measure of self-rated general health that may be used for dichotomization of SF-36 and EQ VAS data when evaluating surgical outcome in spine surgery.
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| 20. |
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| 21. |
- Masiello, Fabio, et al.
(author)
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Investigation by coherent X-ray section topography of ferroelectric domain behaviour as a function of temperature in periodically poled Rb:KTP
- 2011
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In: Journal of applied crystallography. - 0021-8898 .- 1600-5767. ; 44, s. 462-466
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Journal article (peer-reviewed)abstract
- The behaviour of ferroelectric domains at high temperatures near the Curie temperature in a periodically poled rubidium-doped potassium titanyl phosphate crystal (Rb:KTP) has been studied by Bragg-Fresnel X-ray diffraction imaging in situ using a compact coherence-preserving furnace. The development and partial disappearance of the inverted domain structure as the temperature increases has been successfully modelled, and is explained by invoking a built-in electric field produced under heating in a low vacuum by out-diffusion of atoms from the sample.
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| 22. |
- Pasiskevicius, Valdas, et al.
(author)
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Mirrorless OPO : first steps towards unlocking the potential of counter-propagating three-wave interactions
- 2008
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In: Nonlinear Frequency Generation and Conversion. - : SPIE. - 9780819470508 ; , s. 87508-87508
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Conference paper (peer-reviewed)abstract
- In this work we present the development of the sub-micron ferroelectric domain structuring technology in KTiOPO4. We used these structures to demonstrate second-order interactions involving counter-propagating waves. Of special interest is the mirrorless optical parametric oscillator, where distributed feedback between the counter-propagating signal and idler waves obviates the need for mirrors, surface coatings or precise cavity alignment. Mirrorless optical parametric oscillator also demonstrates some unique and useful spectral properties. These experimental demonstrations are but first steps towards a number of tantalizing applications which, however, require even smaller ferroelectric domain periodicities and further work on the material structuring technology.
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| 23. |
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| 24. |
- Pasiskevicius, Valdas, et al.
(author)
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Quasi-phase matched nonlinear media : Progress towards nonlinear optical engineering
- 2012
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In: Optical materials (Amsterdam). - : Elsevier. - 0925-3467 .- 1873-1252. ; 34:3, s. 513-523
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Research review (peer-reviewed)abstract
- Nonlinear optics has been enabled by the invention of the laser 50 years ago, and since then both technologies evolved together complementing and enabling each other. In this paper we attempt to briefly overview the historic development of second-order nonlinear materials and try to discern the trends which might dominate developments in the future. The advent of methods of quasi-phase matching and added degrees of freedom in managing three-wave mixing processes pushed the field of nonlinear optics into the realm of engineering. This trend, we believe will continue in the future. In this text we give a short description of design principles of one-dimensional and two-dimensional quasi-phase matched structures and emphasize the increased functionality afforded by such structures. We also overview the nonlinear media where engineering of nonlinear interactions has been demonstrated with the primary focus on ferroelectric and semiconductor nonlinear crystals.
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| 26. |
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| 27. |
- Sigmundsson, Freyr Gauti, 1972-, et al.
(author)
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Additional operations after surgery for lumbar disc prolapse : indications, type of surgery, and long-term follow-up of primary operations performed from 2007 to 2008
- 2022
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In: The Bone & Joint Journal. - : British Editorial Society of Bone and Joint Surgery (JBJS). - 2049-4394 .- 2049-4408. ; 104-B:5, s. 627-632
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Journal article (peer-reviewed)abstract
- AIMS: Lumbar disc prolapse is a frequent indication for surgery. The few available long-term follow-up studies focus mainly on repeated surgery for recurrent disease. The aim of this study was to analyze all reasons for additional surgery for patients operated on for a primary lumbar disc prolapse.METHODS: We retrieved data from the Swedish spine register about 3,291 patients who underwent primary surgery for a lumbar disc prolapse between January 2007 and December 2008. These patients were followed until December 2020 to record all additional lumbar spine operations and the reason for them.RESULTS: In total, 681 of the 3,291 patients (21%) needed one or more additional operations. More than three additional operations was uncommon (2%; 15/906). Overall, 906 additional operations were identified during the time period, with a mean time to the first of these of 3.7 years (SD 3.6). The most common reason for an additional operation was recurrent disc prolapse (47%; 426/906), followed by spinal stenosis or degenerative spondylolisthesis (19%; 176/906), and segmental pain (16%; 145/906). The most common surgical procedures were revision discectomy (43%; 385/906) and instrumented fusion (22%; 200/906). Degenerative spinal conditions other than disc prolapse became a more common reason for additional surgery with increasing length of follow-up. Most patients achieved the minimally important change (MIC) for the patient-reported outcomes after the index surgery. After the third additional spinal operation, only 20% (5/25) achieved the MIC in terms of leg pain, and 29% (7/24) in terms of the EuroQol five-dimension index questionnaire visual analogue scale.CONCLUSION: More than one in five patients operated on for a lumbar disc prolapse underwent further surgery during the 13-year follow-up period. Recurrent disc prolapse was the most common reason for additional surgery, followed by spinal stenosis and segmental pain. This study shows that additional operations after primary disc surgery are needed more frequently than previously reported, and that the outcome profoundly deteriorates after the second additional operation. The findings from this study can be used in the shared decision-making process. Cite this article: Bone Joint J 2022;104-B(5):627-632.
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| 28. |
- Sigmundsson, Freyr Gauti, 1972-, et al.
(author)
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Patients with no preoperative back pain have the best outcome after lumbar disc herniation surgery
- 2022
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In: European spine journal. - : Springer. - 0940-6719 .- 1432-0932. ; 31:2, s. 408-413
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Journal article (peer-reviewed)abstract
- PURPOSE: Most patients with lumbar disc herniations requiring surgery have concomitant back pain. The purpose of the current study was to evaluate the outcome of surgery for lumbar disc herniations in patients with no preoperative back pain (NBP) compared to those reporting low back pain (LBP).METHODS: 15,418 patients surgically treated due to LDH with primary discectomy from 1998 until 2020 were included in the study. Self-reported low back pain assessed with a numerical rating scale (NRS) was used to dichotomize the patients in two groups, patients without preoperative back pain (NBP, NRS = 0, n = 1333, 9%) and patients with preoperative low back pain (LBP, NRS > 0, n = 14,085, 91%). Patient reported outcome measures (PROMs) collected preoperatively and one-year postoperatively were used to evaluate differences in outcomes between the groups.RESULTS: At the one-year follow-up, 89% of the patients in the NBP group were completely pain free or much better compared with 76% in the LBP group. Significant improvement regarding leg pain was seen in all measured PROMs in both groups oneyear after surgery. In the NBP group, 13% reported clinically significant back pain (NRS difference greater than Minimally Clinical Important Difference (MICD)) at the one-year follow-up.CONCLUSIONS: Patients without preoperative back pain are good candidates for LDH surgery. 13% of patients without preoperative back pain develop clinically significant back pain one-year after surgery.
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| 29. |
- Sigmundsson, Freyr Gauti, 1972-, et al.
(author)
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Surgery for Lumbar Spinal Stenosis in Patients With Mild Leg Pain Levels Is Associated With Unsatisfactory Outcome
- 2021
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In: Global Spine Journal. - : Sage Publications. - 2192-5682 .- 2192-5690. ; 11:8, s. 1202-1207
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Journal article (peer-reviewed)abstract
- Study Design: Prospective register cohort study.Objectives: The indication for surgery in patients with lumbar spinal stenosis (LSS) is considered to be leg pain and neurogenic claudication (NC). Nevertheless, a significant part of patients operated for LSS have mild leg pain levels defined as leg pain <= minimally important clinical difference (MICD). Information is lacking on how to inform these patients about the probable outcome of surgery. The objective was to report the outcome of surgery for LSS in patients with a mild preoperative level of leg pain.Methods: A total of 2559 patients operated upon for LSS with preoperative leg pain <= 3 NRS (Numerical Rating Scale) were evaluated for outcome at the 1-year follow-up. NRS for back pain, the Oswestry Disability Index (ODI), and the EuroQol (EQ-5D) were used.Results: In the period 2007 to 2017, we identified 3239 patients (14%) who had mild leg pain (<= 3 on the NRS). In this cohort, leg pain increased 0.40 (0.56-0.37) and back pain decreased 1.0 (0.95-1.2) at the 1-year follow up. ODI decreased 11.1 (10.2-11.4) and the EQ-5D increased 0.15 (0.17-0.14). A total of 31% reached successful outcome in terms of back pain, 43% in terms of ODI and 48% in terms of EQ-5D. 63% of the patients were satisfied with the outcome.Conclusion: A minority of patients with mild leg pain levels operated upon for LSS attain MICD for back pain, ODI, and EQ-5D. The results from this study can aid the surgeon in the shared decision-making process before surgery.
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| 30. |
- Strömqvist, Fredrik
(author)
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Lumbar disc herniation surgery
- 2017
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Doctoral thesis (other academic/artistic)abstract
- Lumbar disc herniation (LDH) most commonly affects individuals in their early forties but can occur at any age. In most instances,the initial treatment is non-surgical and a clear majority of the patients recover with this management. Surgical treatment isgenerally an option first after 6-8 weeks of non-surgical management with unsuccessful outcome in terms of pain, disability andquality of life. The long-term outcome is not different when surgical- and non-surgical treatment are compared. Surgical treatmentgenerally yields a satisfying outcome and shortens the period with severe morbidity. There are however many factors that influencethe surgical outcome and by identifying these, it is possible to make a better patient selection for surgery. Further, the informationgiven to patients when scheduled for surgery is of significant importance for the patients expectations as well as the surgicaloutcome.In papers I, II and III we analyzed data from surgically treated LDH patients included in the national Swedish Spine Register, withspecial interest in the effect of age and gender. In paper IV we analyzed changes in clinical status in patients operated due to LDH,from before surgery to postoperatively and during the first two postoperative weeks. Preoperative SweSpine data was obtained asbaseline comparison and all patients were interviewed postoperatively at day 1, 7 and 14 following surgery (pain, consumption ofanalgesics and quality of life).In paper I we found that there was significant preoperative impairment in children and adolescents who were surgically treated dueto LDH, with girls reporting a more severe clinical impairment. Improvement by surgery was no different in boys and girls andsurgery was associated with a low complication rate. Pain, quality of life and disability was virtually normalized one year after theoperation.In paper II, we found that patients were with higher ages referred to surgery with a more severe preoperative clinical impairment,that the improvement after surgery was inferior in patients with higher age and that the one year outcome following this was inferiorwith increasing age of the patient. There was also a higher frequency of complications with increasing age.In paper III, we found that females surgically treated due to LDH report inferior preoperative clinical status, that both gendersimprove to a similar extent after surgery and that the one year outcome following this was inferior in females.In paper IV, we found that leg pain improved directly by surgery, that back pain improved gradually during the first twopostoperative weeks and that quality of life improved directly after surgery but also continued to improve during the following twoweeks. The patients had already at two weeks after the operation reached the in the literature defined criteria for “successfuloutcome” of LDH surgery.In conclusion, the outcome of LDH surgery is encouraging in children and adolescents. There is age- and gender related outcomedifferences, but these differences are of minor clinical relevance since both elderly and females in general reach the improvementthat in the literature is defined as a “clinical successful outcome” and this already within two weeks after the operation. We are ofthe opinion that age and gender should, if anything, only to minor extent influence the decision making regarding if LDH surgeryshould be performed or not.
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| 31. |
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| 32. |
- Strömqvist, Gustav, et al.
(author)
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Suppression of forward stimulated Raman scattering in periodically poled nonlinear crystals
- 2009
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In: Optics InfoBase Conference Papers. - Denver, CO, USA : Optical Society of America. - 9781557528643
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Conference paper (peer-reviewed)abstract
- Periodic ferroelectric domain inversion leads to modification of polariton dispersion and to efficient suppression of stimulated Raman scattering by phonon-polaritons. This physical mechanism can be employed for controlling stimulated Raman scattering.
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| 33. |
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| 34. |
- Triebel, Jan, et al.
(author)
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Women do not fare worse than men after lumbar fusion surgery : Two-year follow-up results from 4,780 prospectively collected patients in the Swedish National Spine Register with lumbar degenerative disc disease and chronic low back pain.
- 2017
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In: The spine journal. - : Elsevier BV. - 1529-9430 .- 1878-1632. ; 17:5, s. 656-662
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Journal article (peer-reviewed)abstract
- BACKGROUND CONTEXT: Proper patient selection is of outmost importance in surgical treatment of degenerative disc disease (DDD) with chronic low back pain (CLBP). Among other factors gender was previously found to influence lumbar fusion surgery outcome.PURPOSE: This study investigates whether gender affects clinical outcome after lumbar fusion.STUDY DESIGN: National registry cohort study PATIENT SAMPLE: Between 2001 and 2011, 2251 men and 2521 women were followed prospectively within the Swedish National Spine Registry (SWESPINE) after lumbar fusion surgery for DDD and CLBP.OUTCOME MEASURES: Patient-reported outcome measures (PROM) visual analogue scale (VAS) for leg and back pain, Oswestry Disability Index (ODI), quality-of-life (QoL) parameter EQ5D and labour status and pain medication were collected preoperatively, 1 and 2 years after surgery.METHODS: Gender-differences of baseline data and PROM improvement from baseline were analysed. The effect of gender on clinically important improvement of PROM was determined in a multivariate logistic regression model. Furthermore, gender-related differences in return-to-work were investigated.RESULTS: Preoperatively women had worse leg pain (p<0.001), back pain (p=0.002), lower QoL (p<0.001) and greater disability than men (p=0.001). Postoperatively women presented greater improvement 2 years from baseline for pain, function and QoL (all p<0.01). Women had better chances of a clinically important improvement than men for leg pain (OR=1.39, 95% C.I.: 1.19-1.61, p<0.01) and back pain (OR=1.20,95% C.I.:1.03-1.40, p=0.02) as well as ODI (OR=1.24, 95% C.I.:1.05-1.47, p=0.01), but improved at a slower pace in leg pain (p<0.001), back pain (p=0.009), and disability (p=0.008). No gender differences were found in QoL and return-to-work at 2 years postoperatively.CONCLUSIONS: Swedish women do not have worse results than men after spinal fusion surgery. Female patients present with worse pain and function preoperatively, but improve more than men do after surgery.
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| 35. |
- Zukauskas, Andrius, 1983-, et al.
(author)
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Fabrication of submicrometer quasi-phase-matched devices in KTP and RKTP [Invited]
- 2011
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In: Optical Materials Express. - : Optical Society of America. - 2159-3930. ; 1:7, s. 1319-1325
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Journal article (peer-reviewed)abstract
- We review the techniques used for fabrication of bulk submicrometer ferroelectric domain gratings in KTiOPO4 (KTP) and demonstrate that bulk Rb-doped KTiOPO4 (RKTP) is an excellent candidate for implementation of dense domain gratings. Compared to KTP, RKTP presents predominant domain propagation along the polar c-direction, substantially reduced lateral domain broadening, and higher poling yield. As a result we obtain homogeneous sub-μm periodic poling of RKTP with a period of 690 nm in 1 mm thick samples.
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