In the case of bipolar hemiarthroplasty, surgeons are often faced with only migration of outer head and severe osteolysis in acetabulum without loosening of femoral component. There has been much debate regarding the merits of removing or retaining stable femoral components in such cases. The purpose of this study was to determine whether revision of an isolated acetabular component without the removal of a well-fixed femoral component [Fig. 1] could be successfully performed. Thirty-four hips of 33 patients who were followed up for a minimum of 1 year were examined. There were 29 women and 4 men. The average time from primary operation to revision surgery was 12.5 years (range, 0.0 to 17.9 years), and the average follow-up time after revision was 5 years (range, 1.1 to 15.2 years). The average age of the patients at the time of the index revision was sixty-four years (range, thirty-two to seventy-eight years). The reason for acetabular revision was migration of outer head in twenty-eight hips, disassembly of bipolar cup in four hips and recurrent dislocation in two hips. Of the thirty-four femoral components, twenty-seven were cementless and seven were cemented. In nine hips, we performed bone grafting to osteolysis of the proximal femur around the stem. Acetabular components were revised to an acetabular reinforcement ring with a cemented cup in 26 hips, to cementless acetabular components in 8 hips, and to cemented cup in 1 hip.Introduction
Materials and methods
Restoration of joint line in total knee arthroplasty (TKA) is important for kinematics of knee and ligamentous balance. Especially in revision TKA, it may be difficult to identify the joint line. The aim of this study is to define the relationship between epicondyles and articular surface using CT based three-dimensional digital templating sofware $“Athena” (Soft Cube, Osaka, Japan). 137 knees with osteoarthritis, all caces were grade 2 or lower in Kellgren-Lawrence index, were investigated. Perpendicular lines were dropped from the prominences of the medial and lateral femoral epicondyles to the most distal points of articular surfaces and distances of the lines were measured on the axial and coronal planes. The femoral width was measured as the distance between medial and lateral epicondyles. Each of the distance described above was converted to a ratio by dividing by the femoral width. On the axial plane, the average distance from epicondyles to the posterior articular surfaces were 29.4±2.2mm on the medial side and 21.2±2.3mm on the lateral side. The average of the femoral width was 75.2±4.1mm. On coronal plane, the average distance from epicondyles to the distal articular surfaces were 25.2±2.8mm on the medial side and 21.4±2.5mm on the lateral side. The ratio for the distance from epicondyles to the distal and posterior joint line compared to femoral width was 0.39±0.02, 0.28±0.03, 0.33±0.03 and 0.28±0.03. The distance from epicondyles to the distal and posterior joint line correlates with the femoral width of the distal femur. This information can be useful in determining appropriate joint line.
