[Interspinous spacers--technique of Coflex™ implantation]. / Interspinöse Spacer--implantationstechnik von Coflex™.

OBJECTIVE: This surgical procedure addresses the reduction of spinal stenoses as a short-term result. In the long run, prevention of recurrent narrowing of the spinal canal and the development of sciatic pain is the goal by taking load from the facet joint and indirect extension of the neuroforamina. This is achieved by interspinous distraction of the described spacer. In addition, this implant leads to a dynamic limitation of a spinal motion segment. INDICATIONS: Spinal stenosis in conjunction with moderate spondylarthrosis without signs of spondylolisthesis (> Meyerding 1°). Other indications are revisions after nucleotomies and primary nucleotomies in cases of massive disk hernia. CONTRAINDICATIONS: Segmental instabilities (degeneration or spondylolisthesis), advanced spondylarthrosis, dysraphia of the vertebral arc, scoliosis at the segment to treat, significant osteoporosis, tumor, infection. SURGICAL TECHNIQUE: Interlaminar decompression and implantation of an interspinous spacer. POSTOPERATIVE MANAGEMENT: Mobilization not before 2 h postoperatively. Wound drain removal after approximately 24 h. In case of treatment of more than one segment as as well as in cases of revision and obesity, a lumbar orthesis for 6 weeks is recommended. Physiotherapy to improve active lumbar stabilization especially by isometric exercises. Lifting of heavy loads (> 5 kg) and extensive flexion should be avoided. RESULTS: So far, inconsistent results in currently available retrospective studies. Comparable short-term results in prospective studies of sole decompression without implantation of an interspinous spacer. Prospective randomized comparative studies are not yet available.

Femoral morphology due to impingement influences the range of motion in slipped capital femoral epiphysis.

Femoroacetabular impingement due to metaphyseal prominence is associated with the slippage in patients with slipped capital femoral epiphysis (SCFE), but it is unclear whether the changes in femoral metaphysis morphology are associated with range of motion (ROM) changes or type of impingement. We asked whether the femoral head-neck junction morphology influences ROM analysis and type of impingement in addition to the slip angle and the acetabular version. We analyzed in 31 patients with SCFE the relationship between the proximal femoral morphology and limitation in ROM due to impingement based on simulated ROM of preoperative CT data. The ROM was analyzed in relation to degree of slippage, femoral metaphysis morphology, acetabular version, and pathomechanical terms of "impaction" and "inclusion." The ROM in the affected hips was comparable to that in the unaffected hips for mild slippage and decreased for slippage of more than 30 degrees. The limitation correlated with changes in the metaphysic morphology and changed acetabular version. Decreased head-neck offset in hips with slip angles between 30 degrees and 50 degrees had restricted ROM to nearly the same degree as in severe SCFE. Therefore, in addition to the slip angle, the femoral metaphysis morphology should be used as criteria for reconstructive surgery.

Quantitative evaluation of angular measurements on plain radiographs in patients with slipped capital femoral epiphysis: a 3-dimensional analysis of computed tomography-based computer models of 46 femora.

BACKGROUND: In cases of slipped capital femoral epiphyses (SCFE) findings on plain radiographs help to determine the further necessary course of action. In severe cases possible surgical procedures are commonly indicated and planned using angular measurements on plain radiographs to describe the extent and direction of the slip. The aim of this study was to quantify the amount of angular errors deriving from this method. METHODS: Data and imaging of 23 consecutive patients with SCFE (31 affected and 15 unaffected femora) were included in this study. We determined shaft-neck/shaft-physis angles on antero-posterior and torsional angles on lateral radiographs in a clinical setting. As a reference we enabled similar angular measurements on CT-based three-dimensional computer models of the same femora bearing no projectional errors and malpositioning problems. RESULTS: In average, shaft-neck- and shaft-physis-angles were overestimated (6.5 degrees and 10.1 degrees ) on plain radiographs and neck torsion underestimated (-15.7 degrees ). In general the variability was high, especially for neck and physeal torsional measurements with standard deviations of +/-11.8 degrees and +/-16.7 degrees . Three out of four torsional measurements on affected femora were outside a +/-10 degrees window of error, about every third outside a +/-20 degrees window. CONCLUSION: Our results suggest to be careful when using plain radiographs as a source to determine the slippage extent in SCFE. Before using a plain radiograph to reject or indicate and plan a correction osteotomy in an individual case of SCFE the surgeon should reassure that radiographic method and patient positioning provide a reproducible and accurate depiction of the femoral geometry. LEVEL OF EVIDENCE: Level II; 23 consecutive patients with SCFE in the senior authors practice; evaluation of the reliability of angular measurements on plain radiographs; CT based 3D computer models of the same femora as a reference.

How does soft tissue distribution affect anteversion accuracy of the palpation procedure in image-free acetabular cup navigation? An ultrasonographic assessment.

Navigation of the acetabular cup in total hip replacement (THR) is used to improve the reproducibility of acetabular component positioning. When the palpation of anatomic landmarks, which is necessary to determine the pelvic coordinate system, is performed epicutaneously, the question as to how uneven soft tissue distribution can influence navigation accuracy arises. To obtain data, the questionable soft tissue thickness was measured in 72 patients scheduled for THR. In addition, distances between the landmarks were recorded. On the basis of this information, we were able to calculate the expected misinterpretation of the anteversion given by a navigation system for each patient. The calculations suggest that a navigation system would have underestimated the anteversion on average by 2.8 degrees +/- 1.8 degrees. The median of anteversion misinterpretation was 2.4 degrees and its 95% confidence interval was calculated to be 2.2 degrees -3.0 degrees. No correlation with substantial significance between anteversion misinterpretation and the patients' biometrical data could be found. According to the current knowledge, acetabular cups in THR should be positioned within a range of 30 degrees -50 degrees of inclination and 10 degrees -30 degrees of anteversion. In comparison with these permitted +/- 10 degrees windows, the amount of misinterpretation that was found due to uneven soft tissue distribution seems to be acceptable.