Medial placement of the acetabular component in an alumina-on-alumina total hip arthroplasty: a comparative study with propensity score matching.

PURPOSE: In an alumina-on-alumina total hip arthroplasty (THA), recommended with a small inclination angle <45°, the acetabular component (cup) may be positioned more medially to be covered almost completely by host bone. The purpose of this study was to identify the correlating factors and to evaluate the outcomes of medial placement of the cup in patients with alumina-on-alumina THAs. METHODS: Using the propensity score matching with age, gender, body mass index, initial diagnosis, and the length of follow-up as variables, 38 hips with a medialized cup and 38 hips with a non-medialized one were identified from 389 hips in 347 who patients underwent primary alumina-on-alumina THA and followed up for more than 7 years. Clinical and radiological outcomes were compared between the two groups. RESULTS: Preoperative acetabular medial wall thickness and the cup inclination angle were significantly smaller in the medialization group compared to the non-medialization group. Center edge angle, cup size, and coverage by host bone were not significantly different between the two groups. The hip center of rotation was significantly medialized in the medialization group. The Harris hip scores were not significantly different between the two groups. No component loosening or osteolysis was observed and no revision was required in either groups. CONCLUSIONS: Thin acetabular medial wall and a small inclination angle of the cup were the correlating factors of medial placement of the cup in patients who underwent an alumina-on-alumina THA. Medial placement did not lead to differences in the clinical or radiological outcomes.

Alumina-on-alumina THA performed in patients younger than 30 years: a 10-year minimum followup study.

BACKGROUND: THA in patients younger than 30 years presents challenges because of uncertainties regarding the long-term survivorship of prostheses. Alumina-on-alumina bearings, which exhibit little long-term wear, may be a reasonable option but the long-term survivorship is unknown. QUESTIONS/PURPOSES: We determined (1) the survival rate of alumina-on-alumina bearings in patients younger than 30 years after a 10-year followup, (2) the incidence of audible hip clicking and squeaking, (3) radiographic evidence of osteolysis, and (4) the effects on pregnancy, childbirth, and career choice. METHODS: We retrospectively reviewed 62 patients who had 75 THAs with alumina-on-alumina bearings followed more than 10 years (average, 11.5; range, 10-13.5 years). Mean patient age at the time of surgery was 24 years (range, 18-30 years). All operations were performed using the same cementless implant at a single center. We determined survival, presence of osteolysis, and function (Harris hip score, WOMAC). RESULTS: The 10-year survival rate of alumina-on-alumina bearings in THAs, with revision for any reason as the end point, was 98.9%. Audible hip clicking and squeaking were identified in 10 hips and two hips, respectively. No osteolysis was detected. None of the 11 patients who became pregnant had been affected by their THA during pregnancy or childbirth. Seven of the 14 patients who were unemployed at the time of index surgery stated that their THA affected their job choice. CONCLUSIONS: We found a high 10-year survival of cementless alumina-on-alumina bearings in THAs in patients younger than 30 years. Lifetime events such as job choice, pregnancy, and childbirth should be considered when choosing THA for patients younger than 30 years. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Multiplanar reformation computed tomogram is better than MR imaging in decision making for apparently isolated fractures of the greater trochanter.

OBJECTIVES: We evaluated isolated fractures of the greater trochanter (IFGT) on plain radiographs with multiplanar reformation computed tomography (MPR CT). DESIGN: Retrospective review of patients. SETTING: University teaching hospital. PATIENTS: This study included 27 consecutive patients with apparently IFGT. MAIN OUTCOME MEASUREMENTS: The clinical results, X-ray, computed tomography, magnetic resonance imaging, bone scintigraphy findings were investigated. RESULTS: Four of 27 cases demonstrated anterior cortical breakage or extensive damage of the trabecular bone in the intertrochanteric area on MPR CT images. Surgical fixation was necessary for these 4 cases. The other 23 cases, in which no structural damage was detected, were treated conservatively, and the results were satisfactory without progression to a complete intertrochanteric fracture. All 9 cases evaluated with magnetic resonance imaging demonstrated extension into the intertrochanteric area. In 5 cases, the extension crossed the midline on the mid-coronal image. Two of the cases were treated surgically because of anterior cortical breakage and extensive trabecular impaction on MPR CT, respectively. However, the other 3 cases and 4 cases with mild intertrochanteric extension were treated conservatively without problem. CONCLUSIONS: The evaluation of IFGT with MPR CT was shown to be valuable for determining the optimal treatment method.