An evaluation of Trapezoidal-28 femoral stem fractures.

Fourteen patients sustaining femoral stem fractures of cold rolled wrought stainless steel Trapezoidal-28 prostheses (Zimmir, Warsaw, Indiana) were compared statistically with 259 successful hip replacements of the same type of prosthesis to determine possible factors predisposing to prosthetic fracture. Varus alignment was the highest contributing factor in these femoral stem fractures. Calcar resorption and insufficient distal lateral cement support also were contributory. Medial cement support was less for patients sustaining a fracture, but this was not statistically significant. Patients prone to encounter a fracture were men who were young and/or overweight. There was no significant correlation of fracture to preoperative diagnosis, laterality, trochanteric osteotomy, nonunion of the greater trochanter, or wire breakage.