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author:("billroth, Kaj")
2.  Long-term results of surgery for lumbar spinal stenosis: a randomised controlled trial 
European Spine Journal  2011;20(7):1174-1181.
We randomised a total of 94 patients with long-standing moderate lumbar spinal stenosis (LSS) into a surgical group and a non-operative group, with 50 and 44 patients, respectively. The operative treatment comprised undercutting laminectomy of stenotic segments, augmented with transpedicular-instrumented fusion in suspected lumbar instability. The primary outcome was the Oswestry disability index (ODI), and the other main outcomes included assessments of leg and back pain and self-reported walking ability, all based on questionnaire data from 85 patients at the 6-year follow-up. At the 6-year follow-up, the mean difference in ODI in favour of surgery was 9.5 (95% confidence interval 0.9–18.1, P-value for global difference 0.006), whereas the intensity of leg or back pain did not differ between the two treatment groups any longer. Walking ability did not differ between the treatment groups at any time. Decompressive surgery of LSS provided modest but consistent improvement in functional ability, surpassing that obtained after non-operative measures.
doi:10.1007/s00586-010-1652-y
PMCID: PMC3175822  PMID: 21240530
Spinal stenosis; Surgical treatment; Non-operative treatment; Randomised controlled trial
3.  Changing from analog to digital images: Does it affect the accuracy of alignment measurements of the lower extremity? 
Acta Orthopaedica  2011;82(3):351-355.
Background and purpose
Medical imaging has changed from analog films to digital media. We examined and compared the accuracy of orthopedic measurements using different media.
Methods
Before knee arthroplasty, full-length standing radiographs of 52 legs were obtained. The mechanical axis (MA), tibio-femoral angle (TFA), and femur angle (FA) were measured and analyzed twice, by 2 radiologists, using (1) true-size films, (2) short films, (3) a digital high-resolution workstation, and (4) a web-based personal computer. The agreement between the 4 media was evaluated using the Bland-Altman method (limits of agreement) using the true-size films as a reference standard.
Results
The mean differences in measurements between the traditional true-size films and the 3 other methods were small: for MA –0.20 to 0.07 degrees, and for TFA –0.02 to 0.18 degrees. Also, the limits of agreement between the traditional true-size films and the three other methods were small.
Interpretation
The agreement of the alignment measurements across the 4 different media was good. Orthopedic angles can be measured as accurately from analog films as from digital screens, regardless of film or monitor size.
doi:10.3109/17453674.2011.570670
PMCID: PMC3235315  PMID: 21619504
4.  Dextrocardia and coronal alignment of thoracic curve: a population study 
European Spine Journal  2009;18(12):1941-1945.
The objective of this study was to evaluate the coronal alignment of the thoracic spine in persons with dextrocardia. Generally, the thoracic spine is slightly curved to the right. It has been suggested that the curve could be triggered by pulsation forces from the descending aorta. Since no population study has focused on the alignment of the thoracic spine in persons with situs inversus, dextrocardia, and right-sided descending aorta, we compared the radiographs of the thoracic spine in persons with dextrocardia to those having normal levocardia. Among 57,440 persons in a health survey, 11 cases of dextrocardia were identified through standard radiological screening. The miniature chest radiographs of eight persons were eligible for the present study. The study was carried out as a nested case–control study. Four individually matched (age, gender, and municipality) controls with levocardia were chosen for each case. Coronal alignment of the thoracic spine was analyzed without knowledge of whether the person had levo- or dextrocardia. A mild convexity to the left was found in all persons with dextrocardia and right-sided descending aorta (mean Cobb angle 6.6° to the left, SD 2.9). Of the 32 normal levocardia persons, 29 displayed a convexity to the right, and the remaining three had a straight spine (mean Cobb angle 5.2° to the right, SD 2.3). The difference (mean 11.8°, SD 3.5) differed significantly from unity (P = 0.00003). In conclusion, it seems that a slight left convexity of the thoracic spine is frequent in dextrocardia. We assume that the effect of the repetitive pulsatile pressure of the descending thoracic aorta, and the mass effect of the heart may cause the direction of the convexity to develop opposite to the side of the aortic arch.
doi:10.1007/s00586-009-1049-y
PMCID: PMC2899440  PMID: 19506918
Situs inversus; Dextrocardia; Left thoracic curve; Aorta
5.  Allelic variants of IL1R1 gene associate with severe hand osteoarthritis 
BMC Medical Genetics  2010;11:50.
Background
In search for genes predisposing to osteoarthritis (OA), several genome wide scans have provided evidence for linkage on 2q. In this study we targeted a 470 kb region on 2q11.2 presenting the locus with most evidence for linkage to severe OA of distal interphalangeal joints (DIP) in our genome wide scan families.
Methods
We genotyped 32 single nucleotide polymorphisms (SNPs) in this 470 kb region comprising six genes belonging to the interleukin 1 superfamily and monitored for association with individual SNPs and SNP haplotypes among severe familial hand OA cases (material extended from our previous linkage study; n = 134), unrelated end-stage bilateral primary knee OA cases (n = 113), and population based controls (n = 436).
Results
Four SNPs in the IL1R1 gene, mapping to a 125 kb LD block, provided evidence for association with hand OA in family-based and case-control analysis, the strongest association being with SNP rs2287047 (p-value = 0.0009).
Conclusions
This study demonstrates an association between severe hand OA and IL1R1 gene. This gene represents a highly relevant biological candidate since it encodes protein that is a known modulator of inflammatory processes associated with joint destruction and resides within a locus providing consistent evidence for linkage to hand OA. As the observed association did not fully explain the linkage obtained in the previous study, it is plausible that also other variants in this genome region predispose to hand OA.
doi:10.1186/1471-2350-11-50
PMCID: PMC2859817  PMID: 20353565
6.  Outcome of periacetabular osteotomy 
Acta orthopaedica  2005;76(3):303-313.
Background
Due to wide variations in acetabular structure of individuals with hip dysplasia, the measurement of the acetabular orientation may not be sufficient to predict the joint loading and pressure distribution across the joint. Addition of mechanical analysis to preoperative planning, therefore, has the potential to improve the clinical outcome.
We analyzed the effect of periacetabular osteotomy on hip dysplasia using computer-aided simulation of joint contact pressure on regular AP radiographs. The results were compared with the results of surgery based on realignment of acetabular angles to the normal hip.
Patients and methods
We studied 12 consecutive periacetabular osteotomies with no femoral head deformity. The median age of patients, all females, was 35 (20−50) years. The median follow-up was 2 years (1.3−2.2). Patient outcome was measured with the total score of a self-administered questionnaire (q-score) and with the Harris hip score. The pre- and postoperative orientation of the acetabulum was defined using reconstructed 3D CT-slices to measure angles in the three anatomical planes. Peak contact pressure, weight-bearing area, and the centroid of the contact pressure distribution (CP-ratio) were calculated.
Results
While 9 of 12 cases showed decreased peak pressure after surgery, the mean changes in weight-bearing area and peak contact pressure were not statistically significant. However, CP-ratio changed (p < 0.001, paired t-test) with surgery. For the optimal range of CP-ratio (within its mid-range 40−60%), the mechanical outcome improved significantly.
Interpretation
Verifying the correlation between the optimal CP-ratio and the outcome of the surgery requires additional studies on more patients. Moreover, the anatomically measured angles were not correlated with the ranges of CP-ratio, suggesting that they do not always associate with objective mechanical goals of realignment osteotomy. Mechanical analysis, therefore, can be a valuable tool in assessing two-dimensional radiographs in hip dysplasia.
PMCID: PMC2745131  PMID: 16156455
7.  Evaluation of a computerized measurement technique for joint alignment before and during periacetabular osteotomy 
Periacetabular osteotomy (PAO) is intended to treat a painful dysplastic hip. Manual radiological angle measurements are used to diagnose dysplasia and to define regions of insufficient femoral head coverage for planning PAO. No method has yet been described that recalculates radiological angles as the acetabular bone fragment is reoriented. In this study, we propose a technique for computationally measuring the radiological angles from a joint contact surface model segmented from CT-scan data. Using oblique image slices, we selected the lateral and medial edge of the acetabulum lunate to form a closed, continuous, 3D curve. The joint surface is generated by interpolating the curve and the radiological angles are measured directly using the 3D surface. This technique was evaluated using CT data for both normal and dysplastic hips. Manual measurements made by three independent observers showed minor discrepancies between the manual observations and the computerized technique. Inter-observer error (mean difference±standard deviation) was 0.04±3.53° Observer 1; −0.46±3.13° for Observer 2; and 0.42±2.73° for Observer 3. The measurement error for the proposed computer method was −1.30±3.30°. The computerized technique demonstrates sufficient accuracy compared to manual techniques, making it suitable for planning and intraoperative evaluation of radiological metrics for periacetabular osteotomy.
doi:10.1080/10929080701541855
PMCID: PMC2716292  PMID: 17786597
Periacetabular osteotomy; inter-observer error; radiographic angles; preoperative planning; acetabular coverage; cartilage segmentation
8.  Cementless total hip arthroplasty in patients with severely dysplastic hips and a previous Schanz osteotomy of the femur 
Acta Orthopaedica  2009;80(3):263-269.
Background and purpose Historically, a Schanz osteotomy of the femur has been used to reduce limp in patients with severely dysplastic hips. In such hips, total hip arthroplasty is a technically demanding operation. We report the long-term results of cementless total hip arthroplasty in a group of patients who had all undergone a Schanz osteotomy earlier.
Patients and methods From 1988 through 1995, 68 total hip replacements were performed in 59 consecutive patients previously treated with a Schanz osteotomy. With the cup placed at the level of the true acetabulum, a shortening osteotomy of the proximal part of the femur and distal advancement of the greater trochanter were performed in 56 hips. At a mean of 13 (9–18) years postoperatively, we evaluated these patients clinically and radiographically.
Results The mean Harris hip score had increased from 51 points preoperatively to 93 points. Trendelenburg sign was negative and there was good or slightly reduced abduction strength in 23 of 25 hips that had not been revised. There were 12 perioperative complications. Only 1 cementless press-fit porous-coated cup was revised for aseptic loosening. However, the 12-year survival rate of these cups was only 64%, as 18 cups underwent revision for excessive wear of the polyethylene liner and/or osteolysis. 6 CDH femoral components had to be revised due to technical errors.
Interpretation Our results suggest that cementless total hip arthroplasty combined with a shortening osteotomy of the femur and distal advancement of the greater trochanter can be recommended for most patients with a previous Schanz osteotomy of the femur. Because of the high incidence of liner wear and osteolysÍs of modular cementless cups in this series, nowadays we use hard-on-hard articulations in these patients.
doi:10.3109/17453670902967273
PMCID: PMC2823216  PMID: 19421907
9.  Three-dimensional mechanical evaluation of joint contact pressure in 12 periacetabular osteotomy patients with 10-year follow-up 
Acta orthopaedica  2009;80(2):155-161.
Background and purpose
Because of the varying structure of dysplastic hips, the optimal realignment of the joint during periacetabular osteotomy (PAO) may differ between patients. Three-dimensional (3D) mechanical and radiological analysis possibly accounts better for patient-specific morphology, and may improve and automate optimal joint realignment.
Patients and methods
We evaluated the 10-year outcomes of 12 patients following PAO. We compared 3D mechanical analysis results to both radiological and clinical measurements. A 3D discrete-element analysis algorithm was used to calculate the pre- and postoperative contact pressure profile within the hip. Radiological angles describing the coverage of the joint were measured using a computerized approach at actual and theoretical orientations of the acetabular cup. Quantitative results were compared using postoperative clinical evaluation scores (Harris score), and patient-completed outcome surveys (q-score) done at 2 and 10 years.
Results
The 3D mechanical analysis indicated that peak joint contact pressure was reduced by an average factor of 1.7 subsequent to PAO. Lateral coverage of the femoral head increased in all patients; however, it did not proportionally reduce the maximum contact pressure and, in 1 case, the pressure increased. This patient had the lowest 10-year q-score (70 out of 100) of the cohort. Another hip was converted to hip arthroplasty after 3 years because of increasing osteoarthritis.
Interpretation
The 3D analysis showed that a reduction in contact pressure was theoretically possible for all patients in this cohort, but this could not be achieved in every case during surgery. While intraoperative factors may affect the actual surgical outcome, the results show that 3D contact pressure analysis is consistent with traditional PAO planning techniques (more so than 2D analysis) and may be a valuable addition to preoperative planning and intraoperative assessment of joint realignment.
doi:10.3109/17453670902947390
PMCID: PMC2689368  PMID: 19404795
10.  Three-dimensional mechanical evaluation of joint contact pressure in 12 periacetabular osteotomy patients with 10-year follow-up 
Acta Orthopaedica  2009;80(2):155-161.
Background and purpose Because of the varying structure of dysplastic hips, the optimal realignment of the joint during periacetabular osteotomy (PAO) may differ between patients. Three-dimensional (3D) mechanical and radiological analysis possibly accounts better for patient-specific morphology, and may improve and automate optimal joint realignment.
Patients and methods We evaluated the 10-year outcomes of 12 patients following PAO. We compared 3D mechanical analysis results to both radiological and clinical measurements. A 3D discrete-element analysis algorithm was used to calculate the pre- and postoperative contact pressure profile within the hip. Radiological angles describing the coverage of the joint were measured using a computerized approach at actual and theoretical orientations of the acetabular cup. Quantitative results were compared using postoperative clinical evaluation scores (Harris score), and patient-completed outcome surveys (q-score) done at 2 and 10 years.
Results The 3D mechanical analysis indicated that peak joint contact pressure was reduced by an average factor of 1.7 subsequent to PAO. Lateral coverage of the femoral head increased in all patients; however, it did not proportionally reduce the maximum contact pressure and, in 1 case, the pressure increased. This patient had the lowest 10-year q-score (70 out of 100) of the cohort. Another hip was converted to hip arthroplasty after 3 years because of increasing osteoarthritis.
Interpretation The 3D analysis showed that a reduction in contact pressure was theoretically possible for all patients in this cohort, but this could not be achieved in every case during surgery. While intraoperative factors may affect the actual surgical outcome, the results show that 3D contact pressure analysis is consistent with traditional PAO planning techniques (more so than 2D analysis) and may be a valuable addition to preoperative planning and intraoperative assessment of joint realignment.
doi:10.3109/17453670902947390
PMCID: PMC2689368  PMID: 19404795
11.  Direct repair for treatment of symptomatic spondylolysis and low-grade isthmic spondylolisthesis in young patients: no benefit in comparison to segmental fusion after a mean follow-up of 14.8 years 
European Spine Journal  2006;15(10):1437-1447.
The aim of the present study was to assess the long-term clinical, functional, and radiographic outcome of direct repair of spondylolysis using cerclage wire fixation according to Scott in young patients with symptomatic spondylolysis or low-grade isthmic spondylolisthesis as compared to the outcome after uninstrumented posterolateral in situ fusion. Twenty-five out of 28 patients of the direct repair group (89%) and 23 out of 28 of the fusion group (82%) were available for follow-up examination. The assessment by independent observers included a structured interview (Oswestry questionnaire [ODI], visual analogue scale, SRS questionnaire), a clinical examination, functional testing, plain radiography, and MRI. The groups were comparable as to the mean age at operation (18.2 vs. 16.2 years.), the follow-up time (14.8 vs. 15.0 years), and the amount of preoperative slip (7.2 vs. 13.1%). The mean ODI and SRS total scores were significantly better in the fusion group (4.3 [0–16] and 96 [57–117]) as compared to the direct repair group (11.4[0–52] and 87[53–107]; P=0.02 and P=0.011, respectively). In functional testing, both groups reached normal values for abdominal and back muscle strength. The lumbar spine flexion and extension ROM was decreased in both groups showing no statistical difference between the groups. Significant progressive narrowing of the olisthetic disc was detected on the plain radiographs after direct repair. On the flexion-extension radiographs, in the direct repair group, the mobility in the lytic/olisthetic segment was decreased in comparison to normal values from the literature. The mobility at the level above the operated segment was decreased in the direct repair group as compared to the fusion group (P=0.057). On T2-weighted MR images in the direct repair group, the signal intensity of the disc below the affected vertebra was decreased in 17/23 (74%) patients. There was no difference between the groups in the nucleus signal intensity of the adjacent disc above the operated segment. No association between the disc degeneration on MRI and the outcome of the patients could be established. In the direct repair group the following complications were seen: transient nerve root irritation (2), superficial infection (1), UTI (1); in the fusion group the complications were: subcutaneous seroma (2) and UTI (1). There were six re-operations, cerclage removal(4), conversion into segmental fusion(2) in the direct repair group, and one re-operation, instrumented respondylodesis, in the fusion group. In conclusion, the results of direct repair of the spondylolysis using cerclage wire fixation according to Scott were very satisfactory in 76% of the patients after a mean follow-up of 14.8 years. After direct repair, the ODI deteriorated with time leading to a clinically moderate but statistically significant difference in favour of segmental fusion. Lumbar spine mobility was decreased after direct repair. Secondary segmental instability above the spinal fusion was not detected. The procedure does not seem to be capable of preventing the olisthetic disc from degeneration. The theoretical benefits of direct repair could not be proven.
doi:10.1007/s00586-006-0072-5
PMCID: PMC3241827  PMID: 16463195
Spondylolysis; Isthmic spondylolisthesis; Operative treatment; Direct repair; Posterolateral fusion; Comparative study

Results 1-11 (11)