Discussion

The results of this systematic review suggest that the Zimmer Biomet CPS device may represent a useful alternative to traditional cemented stems, particularly with respect to the pattern and management of mechanical failure. In adult cohorts, reported periprosthetic fracture rates were generally low; however, direct comparisons with the long-term aseptic loosening rates of cemented stems should be interpreted cautiously because follow-up duration, patient populations, and failure endpoints differ across studies [36, 37].

Clinical implications of the temporal failure pattern

The incidence of fractures during the first 2 postoperative years has substantial clinical implications [11, 23]. It emphasizes the importance of the early osseointegration phase. The biomechanical stability of the CPS device relies on the hypertrophy of the host bone in response to a compressive load [38]. In the first few months before hypertrophy is achieved, the construct is at risk of peak loads or torsional forces [39]. This trend highlights the need to adhere to protected weight-bearing protocols during the early postoperative period. Avedian et al. [40] demonstrated that chemotherapy can delay the initial osseointegration, potentially extending the vulnerable period. However, once osseointegration is achieved, as evidenced by cortical hypertrophy on radiographs [41], the construct demonstrates excellent durability.

Ease of revision and bone stock preservation

One of the key benefits identified is the potential of the device to provide a “fail-safe” mechanism. When failure occurs, loss of the implant itself is rare; instead; a fractures typically occur in the bone proximal to the anchor plug [11]. Revision does not require the removal of a long intramedullary stem because the device uses a short intramedullary footprint (approximately 4–8 cm) [42]. Surgeons may resect the fractured segment and re-implant a CPS device or convert it into a stemmed implant with ample remaining bone stock. This contrasts sharply with the “catastrophic” failure mode of cemented stems, whereby extensive osteolysis causes a hollow shell of bone to form, leading to arduous reconstruction [43, 44]. Compression revision requires a mean bone resection of less than 3–4 mm on average, in contrast to the potential for extensive bone loss with stemmed implant removal.

Risk factor analysis

Table 4 summarizes the identified risk factors of periprosthetic fractures. Interestingly, traditional demographic risk factors such as age, body mass index, and sex have not been consistently associated with an increased fracture risk [25, 26]. However, certain device-specific and surgical factors are also relevant: (1) cortical thickness < 2.5 mm represents a relative contraindication [7]; (2) limited surgeon experience < 5 cases) may be associated with higher failure rates [28]; (3) early weight bearing before osseointegration appears to increase fracture risk [11]; and (4) chemotherapy timing may delay osseointegration but does not appear to increase fracture risk once integration occurs [40].

Clinical interpretation of identified risk factors

These risk factors should be interpreted cautiously because they were derived from small and heterogeneous observational cohorts, often without consistent definitions or adjustment for confounding factors. Nevertheless, the available evidence suggests that device- and treatment-related factors may be more important than demographic variables in determining fracture risk after compressive osseointegration.

Limitations

This study has some limitations. The small number of patient cohorts in individual studies limited our ability to detect risk factors. The heterogeneity of patient populations (oncological vs. traumatic vs. revision indications) makes direct comparisons challenging. Additionally, the learning curve associated with the technique may have influenced the reported complication rates, particularly in earlier studies. Long-term data beyond 10 years remain limited, and comparative studies directly contrasting the CPS device with traditional cemented stems using matched patient populations are lacking. Most data are from high-volume oncologic centers, which may limit their generalizability to broader orthopedic practice. In addition, the included studies were predominantly retrospective and of moderate methodological quality, which should be considered when interpreting the findings.