Radiographic measurement of the posterior femoral offset is not precise.

PURPOSE: The posterior femoral offset may significantly impact the final flexion range after total knee arthroplasty (TKA). The purpose of the present study was to compare a conventional, radiologic-based technique with an intra-operative, surgical navigation-based technique for the measurement of posterior femoral offset. The tested hypothesis was that the two measurement techniques produce different results both before and after TKA. METHODS: One-hundred consecutive cases referred for end-stage knee osteoarthritis have been studied. Posterior femoral offsets, measured pre- and post-TKA from radiographs, as well as those measured from a navigation system intra-operatively, were analysed. The pre-TKA measured offsets, post-TKA measured offsets and the changes (pre- vs. post-TKA) in the offsets were statistically compared between the radiologic and the navigated measurement techniques at a 0.05 level of significance. RESULTS: The mean paired difference between pre-TKA radiologic and navigated measurement was 4 ± 4 mm (p < 0.001). There was a significant and moderate positive correlation with a good coherence between the two measurements. The mean paired difference between post-TKA radiologic and navigated measurement was 6 ± 5 mm (p < 0.001). There was a significant and moderate positive correlation but a poor coherence between the two measurements. CONCLUSIONS: The conventional radiologic technique for the measurement of the posterior femoral offset cannot be reliably used either for pre-TKA planning of the posterior femoral resection and antero-posterior sizing of the femoral component, or for post-TKA quality control of the reconstruction of the posterior femoral offset. LEVEL OF EVIDENCE: Level IV.

The intra- and inter-observer reliability of the CT-scan based X index to quantify glenoid bone loss in chronic anterior shoulder instability and its impact on decision making.

PURPOSE: The X index is a measure of the antero-inferior glenoid bone loss on unilateral 2D CT-scans in the preoperative analysis of chronic anterior shoulder instability. Recurrence rate was shown to be higher after stabilization surgery if X index is superior or equal to 0.4. The objective of this study was to assess the intra- and inter-observer reliability of the X index. METHODS: Sixty patients with an X index ≥0.4 were included retrospectively. The X index was measured twice by two independent evaluators, 15 days apart. The measurement was performed on a unilateral 2D CT-scan by dividing the length of the antero-inferior glenoid defect over the maximal antero-posterior diameter of the glenoid. Reliability of X index was assessed with intra-class correlation coefficient (ICC, ρ). Two points were added to the ISIS calculation if its glenoid criterion was "zero" and we compared this modified score to the original one. RESULTS: The intra-observer reliability of the X index measurement was "excellent" (ρ = 0.95 ± 0.01, p < 0.0001) while the inter-observer reliability was "good" (ρ = 0.59 ± 0.08, p < 0.0001). In patients with a glenoid bone loss visualized by the X index, 48.3 % had a negative sclerotic glenoid line sign. This proportion significantly decreased with the augmentation of the X index, p = 0.02. The average original ISIS score was 3.4 ± 1.9 and became 4.3 ± 1.7 (p < 0.00001) when the X index was incorporated. CONCLUSIONS: The X index is a reliable and simple unilateral 2D CT-scan measurement. AP shoulder radiographs significantly underestimated glenoid bony lesions.

Medium-term comparison of results in obese patients and non-obese hip prostheses with Metha® short stem.

INTRODUCTION: Total hip arthroplasty is one of the most successful orthopedic surgeries in terms of results. However, the prevalence of obesity has nearly doubled between 1980 and 2008. There is limited and controversial data on hip replacement results in obese patients. The Metha® prosthesis, introduced in 2004, is a short stem midway between devices maintaining the femoral neck and metaphyseal implants. The purpose of this study was to evaluate the influence of obesity on clinical and radiological results at medium term. MATERIALS AND METHODS: Eighty-two patients were retrospectively divided into two cohorts based on their BMI. Mean BMI were, respectively, 35.22 kg/m2 in the obese group [30.02-57.79] and 26.15 [23.25-28.72] in the other cohort. Follow-up were 47.16 [26.10-74.33] and 54.06 [28.17-77.73]. The mean ages at surgery were 55 years [39.8-67.8] and 54 [31.3-70.4]. We used self-assessment questionnaires WOMAC and Oxford; two clinical scores Harris Hip Score and Postel-Merle d'Aubigné. ARA score was used for osseointegration evaluation. RESULTS: Operative times were comparable. The self-assessment questionnaires and clinical scores showed significant poorer results in the obese cohort. HHS were 87.54 [56-100] and 92.49 [25-100]. However, the clinical improvement obtained between pre- and postoperative was identical in both groups: 52 [19-73] and 52 [-6 to 90]. Radiological ARA scores were good or excellent for 97.56 and 92.68%. Survival analysis was comparable with more than 0.96 at 50 months follow-up. CONCLUSION: The Metha® prosthesis can be implanted at the forefront of primary total hip arthroplasty in normal subjects as well as in obese subjects. However, we cannot yet claim we will reach the same durability we experience with standard prostheses.