Component alignment and trochanteric detachment in total hip arthroplasty

The relationship between the type and alignment of the prosthetic components and detachment of the greater trochanter in a series of Charnley total hip replacements was investigated. Detachment occurred with increased frequency if the femoral component was positioned in valgus or the cup low in the acetabulum. Whether two or three wires were used to reattach the trochanter did not affect the incidence of detachment. Detachment was unrelated to the patients' weight. Surgical inexperience and a persistent postoperative limp, often effected by joints other than the replaced hip, predisposed to detachment. Detachment is produced by distractive forces arising from the abductor mechanism, acting through the trochanter across the wire fixation. These forces can be reduced by neutral positioning of the femoral stem with the lower pole of the cup 5 mms above the tear-drop.