Wolfram Käfer

Radiological evidence of femoroacetabular impingement in mild slipped capital femoral epiphysis: a mean follow-up of 14.4 years after pinning in situ.

Conventional treatment of mild slipped capital femoral epiphysis consists of fixation in situ with wires or screws. Recent contributions to the literature suggest that even a mild slip may lead to early damage of the acetabular labrum and adjacent cartilage by abutment of a prominent femoral metaphysis. It has been suggested that the appropriate treatment in mild slipped capital femoral epiphysis should not only prevent further slipping of the epiphysis, but also address potential femoroacetabular impingement by restoring the anatomy of the proximal femur. Between October 1984 and December 1995 we treated 16 patients for unilateral mild slipped capital femoral epiphysis by fixation in situ with Kirschner wires. In this study we have reviewed these patients for clinical and radiological evidence of femoroacetabular impingement. There was little clinical indication of impingement but radiological evaluation assessing the femoral head-neck ratio and measuring the Nötzli alpha angle on the anteroposterior and cross-table radiographs showed significant alterations in the proximal femur. None of the affected hips had a normal head-neck ratio and the mean alpha angle was 86 degrees (55 degrees to 99 degrees ) and 55 degrees (40 degrees to 94 degrees ) on the anteroposterior and lateral cross-table radiographs, respectively. While our clinical data favours conventional treatment, our radiological findings are in support of restoring the anatomy of the proximal femur to avoid or delay the development of femoroacetabular impingement following mild slipped capital femoral epiphysis.

Adjacent segment mobility after rigid and semirigid instrumentation of the lumbar spine.

Study Design. Retrospective radiographic analysis of lumbar spine range of motion (ROM) after monosegmental fusion and posterior dynamic stabilization at the level L4–L5. Objective. Comparison of segmental ROM at the index level and the cranial and caudal adjacent levels and of global lumbar spine ROM after monosegmental fusion and posterior dynamic stabilization. Summary of Background Data. The postulated advantage of nonfusion technology compared with fusion is based on the assumption that preservation of motion at the treated segment reduces the incidence of adjacent segment effects. Therefore, it is imperative to provide evidence that dynamic stabilization devices avoid hypermobility at the adjacent segments because this might substantiate a protective effect on the adjacent segments. Methods. Twenty-six patients with low back pain and claudication due to degenerative instability at the level L4–L5 with concomitant spinal stenosis were treated either with decompression and Dynesys (n = 11) or with decompression and fusion (n = 15). All patients underwent flexion/extension radiographs before surgery and at latest follow-up. ROM was assessed at the index level (L4–L5), the cranial/caudal adjacent levels (L3–L4/L5–S1), and at the lumbar spine from L2 to S1. Results. There was a significant reduction of the global ROM of the lumbar spine (L2–S1) and the segmental ROM at the index level (L4–L5) in the fusion group, whereas adjacent level ROM did not change significantly. In the Dynesys group, no significant changes of global lumbar spine ROM (L2–S1) and segmental ROM (index level and cranial/caudal adjacent levels) were seen. Conclusion. This study shows that neither monosegmental instrumented fusion nor monosegmental posterior dynamic stabilization with Dynesys alter the ROM of the cranial and caudal adjacent levels. Consequently, monosegmental posterior dynamic stabilization with Dynesys has no effect with regard to adjacent segment mobility compared with monosegmental fusion.

Overweight and Obesity: Two Predictors for Worse Early Outcome in Total Hip Replacement?

Objective: Doctors and patients assume that overweight and obesity are negative predictors for good and excellent early outcome after total hip replacement. It was the purpose of this prospective investigation to assess whether overweight or obese patients have worse early postoperative outcome in comparison with normal‐weight patients.

Evaluation of Lumbar Spine Motion With Dynamic X-ray–a Reliability Analysis

Study Design. Radiologic evaluation of lumbar range of motion (ROM) with dynamic radiograph. Objectives. To calculate 95% confidence intervals (CIs) for the measurement error accompanying different methods, different observers, and different levels of training when measuring sagittal plane segmental ROM in lumbar spine. In addition, to compare the 95% CI with frequently common statistical methods of reliability analysis. Summary of Background Data. Dynamic radiographs are commonly used for ROM calculation of the lumbar spine. Yet, the reliability of different measurement methods still remains unclear. Methods. In 24 patients, levels L4–L5 and L5–S1 were measured with the Cobb and superimposition methods on flexion-extension radiographs. There were 2 experienced and 1 inexperienced observer that performed the measurements. The 95% CIs were compared with the corresponding Pearson correlation coefficient and P value (t test). Results. The 95% CI of the superimposition method was ±4.0° for the experienced and ±4.7° for the inexperienced observer. The corresponding values for the Cobb method was ±4.2° for the experienced and ±6.8° for the inexperienced observer. The 95% CI for the measurement error became even worse when different methods or observers were compared, whereas a method constancy revealed superior reliability than observer constancy in experienced observers. Conclusions. For lumbar ROM measurement with dynamic radiograph, the superimposition method seems to be more reliable than the Cobb method. Study protocols dealing with ROM measurement have to calculate the 95% CI of the measurement method used because clinically valid conclusions can only be drawn with respect to these intervals.

Posterior component impingement after lumbar total disc replacement: a radiographic analysis of 66 ProDisc-L prostheses in 56 patients.

Study Design. Radiographic evaluation of lumbar total disc replacement (TDR). Objectives. To assess radiographically segmental angulation and mobility after lumbar TDR, to determine the rate of posterior component impingement, and to investigate the influence of implantation level and mono- versus bi-segmental implantations. Summary of Background Data. Polyethylene (PE)-wear can lead to inferior outcome after lumbar TDR due to aseptic loosening. One contributing factor might be increased segmental lordosis with component impingement. Methods. Fifty-six consecutive patients with 66 ProDisc-L (Synthes Spine, Solothurn, CH) prostheses (46 mono-segmental, 10 bi-segmental) were evaluated radiographically. All prostheses had 6° intrinsic angulation and a 10 mm PE-inlay. Segmental angulation and extension range of motion was measured twice on standing radiographs (neutral position and maximum extension) using the spike method. Component impingement was assumed if angulation of the prosthesis fins was >16°. Intraobserver variability was assessed using Pearson correlation coefficient and 95% confidence interval (95% CI). Results. The average angulation in neutral position was 9.9° (±4.8°) and 9.9° (±4.9°) at first and second measurement, respectively. In maximum extension it was 11.3° (±4.9°) and 11° (±4.9°). Pearson correlation coefficient suggested near perfect agreement (0.99) for measurement of angulation and good agreement for range of motion measurement (0.85). Ninety-five percent CI was ±1.2° and ±1.4°, respectively. Data were interpreted using absolute measurements (AM) and 95% CI, suggesting impingement if segmental angulation was >16° (AM) and >17.2° (95% CI). Regarding neutral position, 11% (AM) and 5% (95% CI) of the artificial discs showed component impingement. In extension, this increased to 15% (AM) and 9% (95% CI), respectively. Impingement was more frequent at L4/5 and in bi-segmental implantations. Extension according to AM was maintained in 52 prostheses (79%) with on average 1.4° ± 1.1°. According to the 95% CI, which required a change of >1.4°, extension was seen in 21 prostheses (32%) with on average 2.5° ± 1°. Conclusion. Posterior component impingement was seen in a considerable number of implants. With regard to potential consequences like PE-wear, further studies are needed to investigate the correlation between radiographic and clinical findings.

Posterior motion preserving implants evaluated by means of intervertebral disc bulging and annular fiber strains

BACKGROUND The aims of motion preserving implants are to ensure sufficient stability to the spine, to release facet joints by also allowing a physiological loading to the intervertebral disc. The aim of this study was to assess disc load contribution by means of annular fiber strains and disc bulging of intact and stiffened segments. This was compared to the segments treated with various motion preserving implants. METHODS A laser scanning device was used to obtain three-dimensional disc bulging and annular fiber strains of six lumbar intervertebral discs (L2-3). Specimens were loaded with 500N or 7.5Nm moments in a spine tester. Each specimen was treated with four different implants; DSS™, internal fixator, Coflex™, and TOPS™. FINDINGS In axial compression, all implants performed in a similar way. In flexion, the Coflex decreased range of motion by 13%, whereas bulging and fiber strains were similar to intact. The DSS stabilized segments by 54% compared to intact. TOPS showed a slight decrease in fiber strains (5%) with a range of motion similar to intact. The rigid fixator allowed strains up to 2%. In lateral bending, TOPS yielded range of motion values similar to intact, but maximum fiber strains doubled from 6.5% (intact) to 13.8%. Coflex showed range of motion, bulging and strain values similar to intact. The DSS and the rigid fixator reduced these values. The implants produced only minor changes in axial rotation. INTERPRETATION This study introduces an in vitro method, which was employed to evaluate spinal implants other than standard biomechanical methods. We could demonstrate that dynamic stabilization methods are able to keep fiber strains and disc bulging in a physiological range.

Circumferential dynamic stabilization of the lumbar spine: a biomechanical analysis

PurposeTo assess segmental angulation and mobility following implantation of the Charité artificial disc in combination with the posterior dynamic fixation device dynamic stabilization system (DSS) and the interspinous spacer Coflex at the L4–L5 segment, respectively.MethodsSix human L4–L5 specimens were loaded with pure moments of ±7.5 Nm in flexion/extension, lateral bending, and axial rotation in a custom-made spine tester. The testing protocol was as follows: (a) intact condition, (b) destabilization by resection of the anterior longitudinal ligament (ALL), (c) implantation of the Charité with retained posterior longitudinal ligament (PLL), (d) supplemental DSS implantation, (e) removal of DSS rods and PLL resection, (f) DSS rod re-implantation, (g) enlargement of rod length, and (h) removal of DSS and implantation of Coflex. Range of motion (ROM), neutral zone, and segmental angulation were determined.ResultsALL resection did not influence significantly ROM. TDR increased lateral bending and axial rotation only after resection of the PLL, whereas flexion/extension remained unchanged. DSS limited all degrees of freedom prior to and after PLL resection. Rod length enlargement had no significant effect. Coflex limited significantly flexion/extension compared to the intact state and TDR, whereas lateral bending and axial rotation remained unchanged. TDR increased lordosis, whereas Coflex had a substantial kyphosing effect.ConclusionsThis study demonstrates that posterior dynamic stabilization in combination with TDR reduces flexion/extension ROM and segmental lordosis in a monosegmental biomechanical model.

Index Level Mobility After Total Lumbar Disc Replacement : Is It Beneficial or Detrimental?

Study Design. Analysis of segmental and total lumbar range of motion (ROM) before and after total lumbar disc replacement. Objective. To examine the relationship between absolute segmental and total lumbar ROM and evolution of ROM on clinical outcome. Summary of Background Data. At the moment, data are scarce with regard to the evolution of total lumbar ROM (t-ROM) and segmental ROM (s-ROM) after total lumbar disc replacement. Moreover, the influence of ROM on clinical outcome still is unclear and remains a matter of controversial debate. Methods. Forty patients operated on for mono- or bisegmental symptomatic degenerative disc disease with a total of 45 artificial discs (ProDisc-L, Synthes) were analyzed. Pre- and postoperative s-ROM and t-ROM were measured on flexion/extension radiographs. The Oswestry Low Back Pain Disability Questionnaire and the Short Form 36 Health Survey were obtained pre- and postoperatively with a minimum follow-up of 3 years (37–64 months). Results. Neither the s-ROM (pre-/postoperatively: 6.9°/7.3°) nor the t-ROM (pre-/postoperatively: 34.9°/35.8°) did change significantly after implantation of an artificial disc. Postoperatively, there was an increase of s-ROM (t-ROM) in 40% (40%), a decrease in 35% (30%), and no change in 25% (30%) of the patients. A significant inferior clinical outcome only was observed in patients with decreased t-ROM. The resulting postoperatively s-ROM had no significant impact on outcome. Conclusion. Neither the absolute s-ROM nor the evolution of s-ROM (increase, decrease, unchanged) was positively correlated with better clinical outcome. Although a positive correlation was observed with regard to t-ROM.

Operative Therapie an der Halswirbelsäule bei rheumatoider Arthritis@@@Surgery of the cervical spine in rheumatoid arthritis. Diagnostics and indication: Diagnostik und Indikation

The cervical spine is often affected in rheumatoid arthritis. Beside destructive changes, instabilities can occur, mainly in the upper cervical spine. Typical symptoms are missing so that routine x-ray examinations are needed to prevent severe consequences up to death. AP/lateral cervical spine x-rays and lateral functional x-rays are the standard diagnostic tool. Depending on the findings, further neurological examination and MRI must be initiated. Aim is the early recognition, respectively prevention of myelopathy. Therapy includes stage dependent conservative and surgical measures.

Surgery of the cervical spine in rheumatoid arthritis. Diagnostics and indication

The cervical spine is often affected in rheumatoid arthritis. Beside destructive changes, instabilities can occur, mainly in the upper cervical spine. Typical symptoms are missing so that routine x-ray examinations are needed to prevent severe consequences up to death. AP/lateral cervical spine x-rays and lateral functional x-rays are the standard diagnostic tool. Depending on the findings, further neurological examination and MRI must be initiated. Aim is the early recognition, respectively prevention of myelopathy. Therapy includes stage dependent conservative and surgical measures.