Can computer-assisted surgery help restore leg length and offset during THA? A continuous series of 321 cases.

INTRODUCTION: Total hip arthroplasty (THA) can bring about complications - particularly leg length differences - that are becoming increasingly litigious. Computer-assisted orthopedic surgery (CAOS) can help optimize the procedure, but its ability to effectively restore leg length is controversial. As a consequence, we carried out a study to determine: (1) its contribution to meeting leg length and offset objectives, (2) its reliability, by evaluating the correlation between radiological and navigation data, (3) its safety, by evaluating navigation-specific and non-specific complications. HYPOTHESIS: CAOS will help to restore leg length within ± 5 mm in more than 80% of cases. MATERIAL AND METHODS: A series of 321 continuous cases of cementless THA implanted through the posterolateral approach using CAOS was analyzed retrospectively. With a minimum 1 year follow-up, we evaluated whether the leg length and offset goals were achieved, how well the navigation and radiology data were correlated and whether navigation-specific and non-specific complications occurred. Based on our hypothesis that 80% of patients would have less than 5 mm leg length difference and the null hypothesis (PA = P0) with an alpha of 0.05, 200 observations were required to achieve a power of 90%. RESULTS: The leg length and offset objectives were achieved in 83.3% and 88% of cases, respectively. Twenty-two patients required a heel wedge to compensate for leg length differences. The correlation between the radiology and surgical navigation data was satisfactory - the Pearson coefficient was 0.79 for length and 0.74 for offset. Intraoperative and postoperative complications or adverse events were found in 14.6% of cases; these were specific to CAOS in 12.1% of cases and non-specific in 2.5% of cases. CONCLUSION: This study shows the relevance of CAOS for achieving preoperative leg length objectives, with good correlation between navigation and radiology data, and without major complications. LEVEL OF EVIDENCE: IV - retrospective study.

Median nerve compression in carpal tunnel caused by a giant lipoma.

A lipoma is a common, benign soft-tissue tumor that rarely arises in the upper limb. When one does occur in the hand, the location of the lipoma can cause nerve compression, which can mimic carpal tunnel symptoms. Magnetic resonance imaging is the visualization modality of choice for diagnosis and surgical planning of lipomas. Surgical resection is recommended to relieve the neurological manifestations of this disease. The surgeon should always suspect liposarcoma first before voluminous, atypical, or recurrent tumors are considered.

Medial unicompartmental knee arthroplasty: does tibial component position influence clinical outcomes and arthroplasty survival?

INTRODUCTION: In several recent studies, unicompartmental knee arthroplasty (UKA) produced better functional outcomes than did total knee arthroplasty with 10-year prosthesis survival rates greater than 95%. Nevertheless, UKA is still widely viewed as producing inconsistent results. Tibial component loosening is the leading cause of failure. We consequently sought to identify tibial component position criteria associated with outcomes of medial UKA. MATERIAL AND METHODS: We conducted a retrospective multicentre study of 559 medial UKAs performed between 1988 and 2010 in 421 patients (262 females and 159 males) with a mean age of 69.51±8.72 years at surgery. We recorded the following radiographic parameters: joint space height, obliquity and slope of the tibial implant, whether the tibial component was perpendicular to the femoral component, and lower limb malalignment. The International Knee Society (IKS) score was used to assess clinical outcomes. Mean follow-up at re-evaluation was 5.17±4.33 years. RESULTS: The mean 10-year prosthesis survival rate was 83.7±3.5%. Factors associated with decreased prosthesis survival were a greater than 2-mm change in joint space height, a greater than 3° change in tibial component obliquity, a slope value greater than 5° or a change in slope greater than 2°, and more than 6° of divergence between the tibial and femoral components. Residual mechanical varus of 5° or more was also associated with mechanical failure. The only factor associated with worse functional score values was joint space elevation by more than 2mm. DISCUSSION: The high level of accuracy required for optimal positioning of the tibial component during medial UKA indicates a need for considerable technical expertise and emphasises the conservative nature of the procedure. Optimal positioning is crucial to restore normal knee kinematics and to prevent implant wear and lesions to adjacent compartments. LEVEL OF EVIDENCE: IV, retrospective study.

[Total trapeziectomy and suspension ligamentoplasty: is there any interest to interpose a pyrocarbon Pi2® implant?]. / Trapézectomie totale et ligamentoplastie de suspension : une interposition par un implant Pi2® en pyrocarbone a-t-elle un intérêt ?

Total trapeziectomy with suspensioplasty remains one of the most widely used techniques in thumb osteoarthritis. Nevertheless, such a technique does not completely prevent collapse of the trapezial space. We wanted to know whether adding a pyrocarbon spacer allowed better keeping trapezial space and increasing strength. We compared two groups of patients matched on sex, age, manual labor and dominant side. In each group, they were 23 patients suffering from CMC1 osteoarthrosis, mean age was 62 years. Surgical technique consisted in a total trapeziectomy and suspensioplasty with a Gore-Tex(®) slip without spacer (group A) or associated with spacer Pi2(®) (group B). The follow-up was 25 months for group A and 15 months for group B. Height of the scaphometacarpal space represented 81.5% of trapezium height in group B versus 61.6% in group A. Better correction of hyperextension of the metacarpophalengeal joint was noted in group B. Between group A and group B, no difference was found according to pain (VAS 1.6 versus 1/10), mobility (opposition 9.44 versus 9.31; commissural opening 35.2° versus 37.2°) or strength (Jamar 19.1kg/F versus 16.8kg/F, pinch 4.35kg/F versus 4.67kg/F). DASH score was 16.9 and 25.1/100 respectively. We deplore three symapthetic reflex dystrophies in group A and seven radiological subluxations of the implant in group B. The total trapeziectomy with suspensioplasty gave satisfactory results for both series. The implant Pi2(®) seems to contribute keeping trapezial height, without functional advantages and with a risk of dislocation.