Clinical significance of the musculus gluteus minimus in total hip arthroplasty
Dislocation of the acetabular component is one of the most frequent complications of total hip arthroplasty. It is commonly attributed to implant malpositioning. However, not all dislocations can be explained by this hypothesis. The aim of our study was to elucidate the role of intraoperative injury to hip abductors (m. gluteus minimus in the first place, since it is reportedly an important hip stabilizer) in the development of postoperative hip dislocation. The experiment was conducted in 4 male and 3 female cadavers. A total of 12 THA were performed. The Hardinge and Watson-Jones approaches were used in equal proportion. On plain radiography, acetabular inclination was 40–47°, anteversion was 10–22°; technically and biomechanically, these values were within the normal range and did not depend on the type of surgical approach (for inclination, p = 0.94; for anteversion, p = 0.63), ruling out implant malpositioning as a risk factor for hip dislocation. Nevertheless, implant stability was significantly disrupted following transection of the anterior or posterior fascicle of m. gluteus minimus, leading to the dislocation of the acetabular component in standard rotation and flexion tests. Thus, our study shows the significant role of m. gluteus minimus in stabilizing the hip joint. Preservation or adequate repair of this muscle during surgery will reduce the risk or dislocation and help to restore the anatomy and biomechanics of the operated joint.
Keywords: hip dislocation after arthroplasty, m.gluteus minimus, hip abductor, hip arthroplasty, hip approach