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Knutsson, Björn
Publications (7 of 7) Show all publications
Mukka, S., Mellner, C., Knutsson, B., Sayed-Noor, A. & Sköldenberg, O. (2016). Substantially higher prevalence of postoperative periprosthetic fractures in octogenarians with hip fractures operated with a cemented, polished tapered stem rather than an anatomic stem: A prospective cohort study involving 979 hips. Acta Orthopaedica, 87(3), 257-261
Open this publication in new window or tab >>Substantially higher prevalence of postoperative periprosthetic fractures in octogenarians with hip fractures operated with a cemented, polished tapered stem rather than an anatomic stem: A prospective cohort study involving 979 hips
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2016 (English)In: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 87, no 3, p. 257-261Article in journal (Refereed) Published
Abstract [en]

Background and purpose - Recent studies have demonstrated a high incidence of postoperative periprosthetic femoral fracture (PPF) in elderly patients treated with 2 commonly used cemented, polished tapered stems. We compared the prevalence and incidence rate of PPF in a consecutive cohort of octagenerians with femoral neck fractures (FNFs) treated with either a collarless, polished tapered (CPT) stem or an anatomic matte stem (Lubinus SP2). Patients and methods - In a multicenter, prospective cohort study, we included 979 hips in patients aged 80 years and above (72% females, median age 86 (80-102) years) with a femoral neck fracture as indication for surgery. 69% of the patients were classified as ASA class 3 or 4. Hip-related complications and repeat surgery were assessed at a median follow-up of 20 (0-24) months postoperatively. Results - 22 hips (2.2%) sustained a PPF at a median of 7 (0-22) months postoperatively; 14 (64%) were Vancouver B2 fractures. 7 of the 22 surgically treated fractures required revision surgery, mainly due to deep infection. The cumulative incidence of PPFs was 3.8% in the CPT group, as compared with 0.2% in the SP2 group (p < 0.001). The risk ratio (RR) was 16 (95% CI: 2-120) using the SP2 group as denominator. Interpretation - The CPT stem was associated with a higher risk of PPF than the SP2 stem. We suggest that the tapered CPT stem should not be used for the treatment of femoral neck fractures in patients over 80 years.

National Category
Orthopaedics
Identifiers
urn:nbn:se:uu:diva-298855 (URN)10.3109/17453674.2016.1162898 (DOI)000377098700009 ()27045318 (PubMedID)
Available from: 2016-07-11 Created: 2016-07-11 Last updated: 2018-01-10Bibliographically approved
Knutsson, B., Sanden, B., Sjoden, G., Jarvholm, B. & Michaëlsson, K. (2015). Body Mass Index and Risk for Clinical Lumbar Spinal Stenosis: A Cohort Study. Spine, 40(18), 1451-1456
Open this publication in new window or tab >>Body Mass Index and Risk for Clinical Lumbar Spinal Stenosis: A Cohort Study
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2015 (English)In: Spine, ISSN 0362-2436, E-ISSN 1528-1159, Vol. 40, no 18, p. 1451-1456Article in journal (Refereed) Published
Abstract [en]

Study Design. A prospective cohort study that used a Swedish nationwide occupational surveillance program for construction workers (period of registration from 1971 to 1992). In all, 364,467 participants (mean age at baseline 34 yr) were included in the study. Objective. To determine whether overweight and obesity are associated with a higher risk of lumbar spinal stenosis (LSS). Summary of Background Data. During recent decades, LSS has become the most common indication for spine surgery, a change that coincides with a higher prevalence of obesity. Methods. A diagnosis of LSS was collected through individual linkage to the Swedish National Patient Register through December 31, 2011. Poisson regression models were employed to estimate multivariable-adjusted incidence rate ratios (IRRs) for LSS. Results. At baseline, 65% had normal weight (BMI [body mass index]: 18.5-24.99 kg/m(2)), 29% were overweight (BMI: 25-29.99 kg/m(2)), 5% were obese (BMI >= 30 kg/m(2)), and 2% were underweight (BMI <18.5 kg/m(2)). During 11,190,944 person-years of follow-up, with a mean of 31 years, 2381 participants were diagnosed with LSS. Compared with normal weight individuals, obese workers had an IRR of 2.18 (95% confidence interval, 1.87-2.53) for LSS and overweight workers had an IRR of 1.68 (95% confidence interval, 1.54-1.83). Workers who were underweight halved their risk of LSS (IRR: 0.52, 95% confidence interval, 0.30-0.90). Conclusion. Obese and overweight persons are at a higher risk of developing LSS. Furthermore, our results indicate that obesity might be a novel explanation for the increased number of patients with clinical LSS. Level of Evidence: 3

Place, publisher, year, edition, pages
Wolters Kluwer, 2015
Keywords
Bygghalsan, BMI, body mass index, cohort study, LSS, lumbar spinal stenosis, obesity, overweight, spine surgery
National Category
Orthopaedics
Identifiers
urn:nbn:se:uu:diva-264041 (URN)10.1097/BRS.0000000000001038 (DOI)000361107100009 ()
Available from: 2015-10-06 Created: 2015-10-05 Last updated: 2018-01-11Bibliographically approved
Knutsson, B. & Torstensson, T. (2015). [In Process Citation].. Läkartidningen, 112
Open this publication in new window or tab >>[In Process Citation].
2015 (Swedish)In: Läkartidningen, ISSN 0023-7205, E-ISSN 1652-7518, Vol. 112Article in journal (Refereed) Published
Abstract [sv]

There is a shortage of spine surgeons in Sweden. To guarantee the legal right to healthcare, many counties must hire doctors, with increasing costs. In our new out-patient department routine, the majority of the patients are examined by a physiotherapist at their first visit. History taking and clinical and radiographic examinations are discussed in a team conference, and possible candidates for spine surgery are selected for an appointment with a spine surgeon. Furthermore, the patients were more satisfied with the new routine and management plan.

Keywords
PET; Amyloid imaging; [F-18]flutemetamol; Parametric imaging
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-269627 (URN)26371481 (PubMedID)
Available from: 2015-12-17 Created: 2015-12-17 Last updated: 2017-12-01
Knutsson, B. (2015). Lumbar spinal stenosis: Body mass index and the patient's perspective. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Lumbar spinal stenosis: Body mass index and the patient's perspective
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

During recent decades, lumbar spinal stenosis (LSS) has become the most common indication for spine surgery, a change that coincides with a higher worldwide prevalence of overweight and obesity. Thus, surgical treatment of LSS in the overweight and obese population is common and increasing in scope.

The overall aim of this thesis was to investigate whether body mass index (BMI) is related to the development of LSS, and whether BMI is linked to outcome after surgery for LSS. We further evaluated whether there are specific experiences of LSS from a patient perspective.

Data were obtained for all patients registered in the Swedish Spine Register who had undergone surgery for LSS between January 1, 2006 and June 30, 2008. After adjusting for differences in baseline characteristics, patients with obesity showed both poorer results after surgery and a higher rate of dissatisfaction than patients with normal weight (odds ratio 1.73; 95% confidence interval, CI, 1.36-2.19).

Furthermore, patients with obesity in the cohort reported modest weight loss at follow-up (2.0 kg; 95% CI, 1.5-2.4), and only 8% reported a clinical important weight loss 2 years after surgery.

Our analysis of 389,132 construction workers, showed that overweight (incidence rate ratio, IRR 1.68; 95% CI, 1.54-1.83) and obesity (IRR 2.18; 95% CI, 1.87-2.53) were associated with an increased future risk in developing LSS when compared with patients with normal weight.

To gain insight into the patients' perspective of LSS, we performed interviews with 18 patients who were on a waiting list for LSS surgery. The transcripts, analyzed with content analysis, revealed that living with LSS is a physical, mental and social challenge in which resources to cope with the condition are of major importance.

In summary, obesity is associated with poorer results after surgery, and patients with obesity report modest weight loss during follow-up. In addition, obesity is associated with an increased risk to develop LSS. Our findings revealed that being a patient with LSS, naturally involves considerable suffering and pain, but it also implies being a person with his or her own resources who is able to cope with these adverse conditions.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. p. 70
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1148
Keywords
Antonovsky, back pain, BMI, body mass index, Bygghalsan, cohort study, coping, EQ-5D, excess weight, leg pain, LSS, lumbar spinal stenosis, obesity, ODI Oswestry disability index, overweight, patient-centered, patient-physician relationship, patient-perspective, patient-related-outcome-measure, PROMs, qualitative study, spinal stenosis, salutogenesis, salutogenic, sciatica, spine surgery, suffering, Swedish spine register, Swespine, VAS, weight loss, weight change
National Category
Orthopaedics
Research subject
Orthopaedics
Identifiers
urn:nbn:se:uu:diva-264589 (URN)978-91-554-9376-9 (ISBN)
Public defence
2015-12-04, Rosénsalen, Akademiska barnsjukhuset, ingång 95-96, 751 85, Uppsala, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2015-11-06 Created: 2015-10-15 Last updated: 2018-01-11
Fritzell, P., Knutsson, B., Sandén, B., Strömqvist, B. & Hägg, O. (2015). Recurrent Versus Primary Lumbar Disc Herniation Surgery: Patient-reported Outcomes in the Swedish Spine Register Swespine. Clinical Orthopaedics and Related Research, 473(6), 1978-1984
Open this publication in new window or tab >>Recurrent Versus Primary Lumbar Disc Herniation Surgery: Patient-reported Outcomes in the Swedish Spine Register Swespine
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2015 (English)In: Clinical Orthopaedics and Related Research, ISSN 0009-921X, E-ISSN 1528-1132, Vol. 473, no 6, p. 1978-1984Article in journal (Refereed) Published
Abstract [en]

BACKGROUND:

Lumbar disc herniation (LDH) is a common indication for lumbar spine surgery. The proportion of patients having a second surgery within 2 years varies in the literature between 0.5% and 24%, with recurrent herniation being the most common cause. Several studies have not found any relevant outcome differences between patients undergoing surgery for primary LDH and patients undergoing reoperation for a recurrent LDH, but these studies have limitations, including small sample size and retrospective design.

QUESTIONS/PURPOSES:

We (1) compared patient-reported outcomes between patients operated on for primary LDH and patients reoperated on for recurrent LDH within 1 year after index surgery and (2) determined risk factors for worse outcomes.

METHODS:

We obtained data from the Swedish National Spine Register, Swespine, where patient-reported outcomes are collected using mailed protocols at 1, 2, 5, and 10 years after surgery. Of the 13,562 patients identified who underwent LDH between January 2000 and May 2011, 13,305 (98%) underwent primary surgery for LDH and 257 (2%) underwent reoperation for a recurrent LDH within the first year. Patient-reported outcomes at 1 to 2 years were available for 8497 patients (63%), 8350 of 13,305 (63%) in the primary LDH group and 147 of 257 (57%) in the recurrent LDH group (p = 0.068). We compared leg and back pain (VAS: 0-100), function (Oswestry Disability Index [ODI]: 0-100), quality of life (EQ-5D: -0.59 to 1.0), patient satisfaction, and global assessment of leg pain between groups. We also analyzed rsik factors for worse global assessment and satisfaction.

RESULTS:

Mean (95% CI) differences in improvement between groups favoring patients with primary LDH were VAS leg pain 9 (4-14), ODI 6 (3-9), and EQ-5D 0.09 (0.04-0.15). While statistically significant, these effect sizes may be lower than the minimal clinically important differences often referred to. Percentage of satisfied patients was 79% and 58% in the primary and recurrent LDH groups, respectively (p < 0.001), and percentage of patients with no or better leg pain (global assessment) was 74% and 65%, respectively (p = 0.008). Reoperation for recurrent LDH represented the largest independent risk for dissatisfaction; this factor and smoking represented similar risks for less improvement in leg pain.

CONCLUSIONS:

Repeat surgery for a recurrent LDH was performed with good probability for improvement, although not as good as for primary LDH surgery, and patients undergoing repeated surgery were less satisfied. Studies on risk factors for recurrence are warranted.

LEVEL OF EVIDENCE:

Level II, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

National Category
Orthopaedics
Identifiers
urn:nbn:se:uu:diva-232355 (URN)10.1007/s11999-014-3596-8 (DOI)000354133000018 ()24711131 (PubMedID)
Available from: 2014-09-17 Created: 2014-09-17 Last updated: 2018-01-11Bibliographically approved
Knutsson, B., Michaëlsson, K. & Sandén, B. (2014). Obese patients report modest weight loss after surgery for lumbar spinal stenosis: a study from the Swedish spine register. Spine, 39(20), 1725-1730
Open this publication in new window or tab >>Obese patients report modest weight loss after surgery for lumbar spinal stenosis: a study from the Swedish spine register
2014 (English)In: Spine, ISSN 0362-2436, E-ISSN 1528-1159, Vol. 39, no 20, p. 1725-1730Article in journal (Refereed) Published
Abstract [en]

STUDY DESIGN:

SWESPINE, the Swedish Spine Register, was used for this cohort study.

OBJECTIVE:

Our primary aim was to determine weight change in obese patients after surgery for lumbar spinal stenosis (LSS). Our secondary aim was to study any possible associations between weight loss after surgery and improvement in patient-related outcome measures (PROMs).

SUMMARY OF BACKGROUND DATA:

Only meager evidence is available as to how surgery for LSS affects weight and whether weight loss is associated with improvement in PROMs after surgery for LSS.

METHODS:

All obese patients who underwent surgery for LSS from January 1, 2006 through June 30, 2008 with a completed 2-year follow-up in SWESPINE were included. Data for weight were collected before surgery and then 1 and 2 years after surgery. The cohort was divided into 3 subclasses (weight stable, weight loss, or weight gain).

RESULTS:

Totally, 538 obese patients were enrolled. Mean weight loss was 1.9 kg (95% confidence interval, 1.5-2.3) 1 year after surgery and 2.0 kg (95% confidence interval, 1.5-2.4) after 2 years after surgery. Only 8% of the patients reported a clinically important weight loss (≥10%). No significant differences in PROMs were observed. The weight-stable group reported a mean improvement of 0.22 (standard deviation, 0.36) in EQ-5D, 14 (18) units in the Oswestry Disability Index, 18 (33) units in back pain (visual analogue scale), and 23 (36) units in leg pain (visual analogue scale). The corresponding changes in the weight-loss group were 0.23 (0.35) in EuroQol 5D, 15 (19) in Oswestry Disability Index, 27 (29) in back pain, and 31 (36) in leg pain.

CONCLUSION:

Modest weight loss was reported 1 and 2 years postsurgery; a small proportion (8%) of these patients reported a clinically important weight loss at the 2-year follow-up. The weight loss was unrelated to changes in PROMs.

LEVEL OF EVIDENCE:

3.

National Category
Orthopaedics
Identifiers
urn:nbn:se:uu:diva-232356 (URN)10.1097/BRS.0000000000000464 (DOI)000342030800021 ()24921852 (PubMedID)
Available from: 2014-09-19 Created: 2014-09-17 Last updated: 2018-01-11Bibliographically approved
Knutsson, B., Michaëlsson, K. & Sandén, B. (2013). Obesity Is Associated With Inferior Results After Surgery for Lumbar Spinal Stenosis: A Study of 2633 Patients from the Swedish Spine Register. Spine, 38(5), 435-441
Open this publication in new window or tab >>Obesity Is Associated With Inferior Results After Surgery for Lumbar Spinal Stenosis: A Study of 2633 Patients from the Swedish Spine Register
2013 (English)In: Spine, ISSN 0362-2436, E-ISSN 1528-1159, Vol. 38, no 5, p. 435-441Article in journal (Refereed) Published
Abstract [en]

Study Design

A cohort study based on the Swedish Spine Register.

Objective

To determine the association between body mass index (BMI) and outcome of lumbar spine surgery for spinal stenosis.

Summary of Background Data

Several small studies have sought to evaluate the importance of obesity in relation to results after surgery for lumbar spinal stenosis (LSS) but the findings are inconsistent and relatively weak.

Methods

All patients who underwent surgery for LSS from January 1, 2006 to June 30, 2008 with a completed 2-year follow-up in the Swedish Spine Register were included. Logistic regression was used to assess the association between BMI and different outcomes.

Results

Of 2633 patients enrolled, 819 (31%) were normal weight, 1208 (46%) overweight and 606 (23%) obese. On average, all three BMI groups achieved significant improvements after surgery. A higher BMI, however, was associated with greater odds of dissatisfaction after surgery and inferior results at the 2-year follow-up. After adjusting for differences in baseline characteristics, the obese group demonstrated inferior function and quality of life (QoL) as measured by the Oswestry Disability Index (ODI) and the EuroQol group (EQ-5D), respectively. At the 2-year follow-up, obese patients had a mean ODI of 33 (95% confidence interval [CI], 31-34) and mean EQ-5D of 0.56 (95% CI, 0.54-0.59) compared with a mean ODI of 25 (95% CI 24-26) and mean EQ-5D of 0.64 (95% CI, 0.62-0.66) in the normal weight group. When compared with the normal weight patients, the adjusted odds ratio (OR) for dissatisfaction was 1.73 in the obese group (95% CI 1.36-2.19). Differences between the normal weight and overweight group were modest and therefore could not be considered clinically relevant.

Conclusion

Obese patients achieved significant pain reduction, better walking ability and improved QoL after surgical treatment for LSS. Nevertheless, obesity was associated with a higher degree of dissatisfaction and poorer outcomes after surgery for LSS.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-188778 (URN)10.1097/BRS.0b013e318270b243 (DOI)000315596800020 ()22941097 (PubMedID)
Available from: 2012-12-19 Created: 2012-12-19 Last updated: 2017-12-06Bibliographically approved
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