Patient and technical contributors to periprosthetic fracture around the CPT stem.

Introduction: The incidence of postoperative periprosthetic fracture has been reported to be higher in polished tapered femoral stems with the CPT stem possibly of greatest concern. We report on the patient and surgical factors in a consecutive cohort of 2892 CPT stems implanted as part of a total hip construct, either electively or for the treatment of a fractured neck of femur (NOF) over a 15-year period.

Methods: The Bluespier departmental database was used to identify any patients who been treated for a Vancouver B periprosthetic fracture around a CPT stem from 2008 to 2021. Patient demographics, mechanism of injury and fracture type were recorded. X-rays were reviewed to identify technical issues that may have contributed to the fracture.

Results: A total of 70 fractures were treated. For elective cases the fracture rate was 1.52% while for stems implanted for treatment of a neck of femur fracture (NOF) it was 2.86%. There was a male preponderance and almost all fractures were low energy. The majority (52.9%) were B1 fractures. Only 8 (11.4%) involved a truly loose construct (B2L). The presence of an undersized and varus stem increased the risk of fracture particularly in the NOF population.

Discussion: The results in this series are consistent with the registry data regarding the rate of failure of the CPT stem related to periprosthetic fracture. The patient population is typical of those who sustain a proximal femoral fracture in terms of age although we report a male preponderance. The importance of surgical technique in the placement of a correctly sized and aligned stem, particularly in those patients undergoing hip replacement for a neck of femur fracture is highlighted.