Abstract
Introduction
It has been postulated that the larger femoral head size may be associated with reduced risk of dislocation after total hip arthroplasty(THA). However, Dislocation after THA has a multifactorial etiology with variables such as femoral head size, type of cup, stem and surgical approach.
Objectives
The objectives of this study is to evaluate the association between femoral head component head size, surgical approach, surgeon's experience and the rate of dislocation after THA.
Methods
From 2004 to 2013, 4,423 primary THA with varying femoral head sizes were performed at our institution. The operative approaches were Mini-One approach in 3,140 arthroplasties, OCM approach in 753, Hardinge in 483, and 2-incision approach in 47. The femoral head diameters were 26-mm in 2,965 of the procedures, 28-mm in 797, 32-mm in 516, 36-mm in 133, and 38-mm in 12. We compared the dislocation rates differences in surgical approach and the diameter of the femoral head. Statistical analysis was used by Chi-square test.
Results
Dislocation occurred in 32 hips (0.72%) of the 4,423 hips. The rate of the dislocation was 0.64% following Mini-One approaches, 1.06% following OCM approaches, and 0.83% following Hardinge approaches. There was no dislocation in 2-inciision approaches. There was no significant difference in rate of dislocation between Mini-One group (0.64%) and non-Mini-One group (0.94%) (p=0.34). There was no significant difference in rate of dislocation between OCM group (1.06%) and non-OCM group (0.65%) (p=0.23). There was no significant difference in rate of dislocation between Hardinge group (0.83%) and non Hardinge group (0.71%) (p=0.77). Dislocation occurred in 23 hips (0.78%) with a 26-mm femoral head and in 7 hips (0.88%) with a 28-mm femoral head and in 2 hips (0.39%) with a 32-mm head. No dislocation occurred with a 36-mm head and 38-mm head. There was no significant difference in rate of dislocation between 32-mm and over head group and below 32-mm head group (p=0.22). In 3,265 cases, 55mm and under diameter of the cups were used by four high volume surgeons who experienced above 500 cases of THA. No dislocation occurred in this 3,265 cases with a 32-mm and over head diameter.
Conclusion
Dislocation rate was 0.72%. Although this rate was too low to be statistical significant differences between femoral head component head size, surgical approach and the rate of dislocation, No dislocation was occurred in 55mm and under diameter of the cups and 32-mm head and over cases with experienced surgeons.
