Calcar-guided short stems - there's no getting around in modern THA

Background: Total hip arthroplasty (THA) is increasingly performed in younger, active patient populations who require optimized postoperative function. While conventional stems provide reliable long-term outcomes, the demand for bone-conserving and soft-tissue-sparing techniques has led to the development of various short-stem femoral implants.

Objective: This review evaluates the classification, surgical philosophy, and clinical performance of calcar-guided short stems, focusing on their role in anatomical reconstruction and minimally invasive surgery (MIS).

Key Points: Short stems are classified by the level of femoral neck resection: neck-retaining, partially neck-retaining (calcar-guided), and neck-resecting. Calcar-guided designs represent the current generation, utilizing an individualized resection level to facilitate anatomical reconstruction of the femoro-acetabular offset and center-collum-diaphysis (CCD) angle. These implants support "round-the-corner" insertion, which preserves the greater trochanter and abductor musculature. Primary stability is achieved through metaphyseal anchoring; however, surgeons must avoid undersizing in valgus femoral morphologies to prevent implant subsidence. National registry data indicate that specific calcar-guided models demonstrate one-year revision rates between 0.3% and 0.8%, which are comparable to or lower than those of conventional straight stems (1.5%).

Conclusion: Calcar-guided short stems facilitate precise anatomical restoration and soft-tissue preservation through individualized positioning. Although long-term data are still emerging, current registry evidence supports their efficacy as a viable alternative to conventional designs in modern THA, particularly when combined with minimally invasive approaches and appropriate intraoperative imaging to ensure stable metaphyseal fixation.