Risk factors for intraoperative calcar fracture in cementless total hip arthroplasty.

BACKGROUND AND PURPOSE: Intraoperative periprosthetic femoral fracture is a known complication of cementless total hip arthroplasty (THA). We determined the incidence of--and risk factors for--intraoperative calcar fracture, and assessed its influence on the risk of revision. PATIENTS AND METHODS: This retrospective analysis included 3,207 cementless THAs (in 2,913 patients). 118 intraoperative calcar fractures were observed in these hips (3.7%). A control group of 118 patients/hips without calcar fractures was randomly selected. The mean follow-up was 4.2 (1.8-8.0) years. Demographic data, surgical data, type of implant, and proximal femur morphology were evaluated to determine risk factors for intraoperative calcar fracture. RESULTS: The revision rates in the calcar fracture group and the control group were 10% (95% CI: 5.9-17) and 3.4% (CI: 1.3-8.4), respectively. The revision rate directly related to intraoperative calcar fracture was 7.6%. The Hardinge approach and lower age were risk factors for calcar fracture. In the fracture group, 55 of 118 patients (47%) had at least one risk factor, while only 23 of118 patients in the control group (20%) had a risk factor (p = 0.001). Radiological analysis showed that in the calcar fracture group, there were more deviated femoral anatomies and proximal femur bone cortices were thinner. INTERPRETATION: Intraoperative calcar fracture increased the risk of revision. The Hardinge approach and lower age were risk factors for intraoperative calcar fracture. To avoid intraoperative fractures, special attention should be paid when cementless stems are used with deviant-shaped proximal femurs and with thin cortices.

Three metal-on-metal hip replacement devices from the same manufacturer--a short- to mid-term survival.

The aim of this retrospective study was to evaluate short- to mid-term results of three different metal-on-metal hip devices from the same manufacturer. A total of 329 hip operations were performed in a single academic unit between 2004 and 2010 using either Birmingham hip resurfacing or Synergy--Birmingham and Synergy--R3 total hip arthroplasty. The overall survival rate at the end of the follow-up time for Birmingham hip resurfacing was 88%, for Synergy--Birmingham total hip arthroplasty 95%, and for Synergy--R3 total hip arthroplasty 81% (p = 0.036). Five revision operations were performed due to adverse reaction to metal debris. Head sizes > 50 mm had lower revision rates compared to smaller ones. Synergy--R3 had a poor survival already at short-term. The mid-term survival of Birmingham hip resurfacing arthroplasty was inferior compared to previous studies.

Effect of femoral head size on risk of revision for dislocation after total hip arthroplasty: a population-based analysis of 42,379 primary procedures from the Finnish Arthroplasty Register.

BACKGROUND AND PURPOSE: Previous population-based registry studies have shown that larger femoral head size is associated with reduced risk of revision for dislocation. However, the previous data have not included large numbers of hip resurfacing arthroplasties or large metal-on-metal (> 36-mm) femoral head arthroplasties. We evaluated the association between femoral component head size and the risk of revision for dislocation after THA by using Finnish Arthroplasty Register data. PATIENTS AND METHODS: 42,379 patients who were operated during 1996-2010 fulfilled our criteria. 18 different cup/stem combinations were included. The head-size groups studied (numbers of cases) were 28 mm (23,800), 32 mm (4,815), 36 mm (3,320), and > 36 mm (10,444). Other risk factors studied were sex, age group (18-49 years, 50-59 years, 60-69 years, 70-79 years, and > 80 years), and time period of operation (1996-2000, 2001-2005, 2006-2010). RESULTS: The adjusted risk ratio in the Cox model for a revision operation due to dislocation was 0.40 (95% CI: 0.26-0.62) for 32-mm head size, 0.41 (0.24-0.70) for 36-mm head size, and 0.09 (0.05-0.17) for > 36-mm head size compared to implants with a head size of 28 mm. INTERPRETATION: Larger femoral heads clearly reduce the risk of dislocation. The difference in using heads of > 36 mm as opposed to 28-mm heads for the overall revision rate at 10 years follow-up is about 2%. Thus, although attractive from a mechanical point of view, based on recent less favorable clinical outcome data on these large heads, consisting mainly of metal-on-metal prostheses, one should be cautious using these implants.