Introduction

Massive endoprosthetic (EPP) reconstruction after oncological resection or complex trauma has raised critical concerns regarding implant fixation and longevity [1, 2]. Traditional long-stemmed cemented or press-fit implants are the gold standard of care but are associated with stress shielding and aseptic loosening, which can lead to challenging revision scenarios requiring substantial bone loss is required [3, 4]. The Zimmer Biomet Compress® Compliant Pre-Stress (CPS) device uses the Wolff law to maintain bone stock through compressive osseointegration, allowing a major departure in fixation technology [5, 6]. The CPS device gains fixation through a short intramedullary traction bar and spring-loaded spindle with a high compressive force at the bone–implant interface of approximately 400–800 pounds [7] (Fig. 1A-F). This mechanism is designed to protect against stress shielding and to stimulate cortical bone hypertrophy [8, 9]. The device comprises three central modules: an anchor plug fixed with transverse pins, a short spindle containing Belleville washers that provide compression, and an adaptor attached to the modular endoprosthetic components. Despite their biomechanical benefits, the high compressive forces generated at the implants increase the risk of potential periprosthetic fractures, particularly at the anchor plug site and the bone–implant interface [10]. Knowledge of the epidemiology and failure mechanisms of these devices is important for surgical decision making. Compressive osseointegration devices exhibit a failure profile distinct from that of cemented stems [11, 12]; the latter fails because of late-onset aseptic loosening and osteolysis [13, 14]. Therefore, this systematic review aimed to comprehensively evaluate the occurrence, timing, and management of postoperative periprosthetic fractures associated with the CPS device and compare these outcomes with those of the traditional cemented stem.

Fig. 1: Compress® Device: Mechanism and Failure Classification. Anatomically accurate schematic representation of the compressive osseointegration mechanism of the Compress® device and failure modes based on Healey et al.’s classification [3]. A Cross-sectional view of the Compress® device properly seated in the distal femur. The short intramedullary anchor plug (total length, approximately 80 mm) is fixed by three transverse pins penetrating both cortices. The Belleville washer stack within the spindle generates 400–800 PSI (181–363 kg) of continuous compression at the bone–implant interface. This compressive force promotes cortical hypertrophy and osseointegration while avoiding stress shielding. The spindle length ranges from 45–80 mm depending on bone diameter. B–D Lateral views of the distal femur illustrating the two primary periprosthetic fracture patterns observed in clinical series [1]. B Type I (interface failure with fracture), arising between the spindle and anchor plug. C Type IIA (proximal fracture), arising proximal to the anchor plug. D Type IIB (posterior cortical avulsion fracture), arising at the posterior cortex of the spindle. E,F Surgical management of post-implant fractures. E: Schematic illustration of the fracture; the red wavy line indicates the fracture line, and the blue solid line denotes the planned osteotomy for revision surgery. F Schematic illustration of the reconstructive procedure after fracture; the blue dotted line indicates the osteotomy site, and the resultant length deficiency is bridged with a spacer during reconstruction