Risk of acetabular protrusion is low in rheumatoid arthritis patients treated with bipolar hemiarthroplasty for displaced femoral neck fractures without rheumatoid change in hip joints.

OBJECTIVES: The aim of this study was to analyze the radiological outcomes of bipolar hemiarthroplasty after displaced femoral neck fractures of non-arthritic hip joints in rheumatoid arthritis patients. METHODS: We retrospectively investigated 25 hip joints in 23 rheumatoid arthritis patients who underwent bipolar hemiarthroplasty for displaced femoral neck fracture of non-arthritic hip joints. All patients were female with an average age of 69.8 years (range 51-83 years). Mean follow-up duration was 8.4 years (range 5-12 years). Radiographs taken immediately, 1 year after surgery and most recently, were collected for each case. Radiographic measurement of the migration distance of the outer-head prosthesis in the direction of vertical, horizontal and medial to Köhler's line was undertaken at 1 year after surgery and most recently. RESULTS: No patients had hip-related pain after surgery. No case indicated apparent central migration and >3-mm migration of the hemisphere in each direction. There was no significant change in migration distance between evaluation at 1 year after surgery and most recently. CONCLUSIONS: We conclude that risk of acetabular protrusion appears to be low in patients of rheumatoid arthritis treated with bipolar hemiarthroplasty for displaced femoral neck fractures of non-arthritic hip joints in the medium term.

In vivo determination of knee kinematics for Japanese subjects having either a low contact stress rotating platform or an anteroposterior glide total knee arthroplasty.

The objective of this study was to work with a consecutive series of patients having Hospital for Special Surgery scores higher than 90 to evaluate kinematic patterns, under in vivo conditions, for 20 Japanese subjects implanted with 2 different mobile-bearing (MB) total knee arthroplasties (TKAs). Femorotibial contact paths for the medial and lateral condyles were then determined using a computer-automated model-fitting technique. This present study has shown that kinematic patterns for subjects having 2 different MB TKA designs differed but were not statistically different. Subjects implanted with a rotating platform (RP) MB TKA experienced minimal anteroposterior (AP) motion and larger axial rotation (RP). Subjects implanted with an anterior glide MB TKA experienced both femoral rotation and femoral translation (AP glide). There was minimal variability in the kinematic patterns for subjects implanted with an RP, whereas subjects implanted with an AP glide experienced more variable kinematic patterns. Key words: total knee arthroplasty, in vivo, fluoroscopy, kinematics.

Autosomal dominant precocious osteoarthropathy due to a mutation of the cartilage oligomeric matrix protein (COMP) gene: further expansion of the phenotypic variations of COMP defects.

We report on a Japanese family of four generations with an autosomal dominant precocious osteoarthropathy. The cardinal clinical manifestations of affected individuals were painful weight-bearing large joints, which started in late childhood or adolescence. The radiological hallmarks included coxa plana, mild epiphyseal dysplasia of the knee, and round talar domes with tibiotalar slant in childhood, which evolved into degenerative joint diseases in adulthood. The disease phenotype was cosegregated with a mutation of the cartilage oligomeric matrix protein (COMP) gene in the family members, who underwent molecular evaluation. COMP mutations have been reported in a mild form of multiple epiphyseal dysplasia (MED), Ribbing type, as well as allied disorders with more severe manifestations, such as MED Fairbank type and pseudoachondroplasia. Unlike previously reported cases with the Ribbing type, the present patients did not have short stature or brachydactyly. This report expands further the phenotypic variations of COMP defects.