Background: Anatomical variation in the proximal femur, due to dysplasia, Perthes disease, congenital maldevelopment, or trauma, presents significant challenges in total hip arthroplasty (THA). Standard implants may compromise biomechanics, fixation, or limb length restoration. Custom-made femoral stems designed with HIP-PLAN® 3D planning software and CT imaging offer a patient-specific solution that may improve reconstruction accuracy and long-term outcomes.

Methods: A retrospective review was conducted of 16 patients undergoing THA with Symbios custom uncemented femoral stems. Implant design was guided by HIP-PLAN® software, enabling three-dimensional planning of implant size, orientation, and bone-implant interface. Mean follow-up was 9.6 years (range 0.1–17.0). Etiologies included developmental dysplasia (43.8%), Perthes disease (25.0%), congenital maldevelopment (18.8%), and trauma (12.5%). Functional outcomes were measured using the Oxford Hip Score and UCLA Activity Score. Radiographic limb length discrepancy (LLD) was assessed pre- and postoperatively.

Results: Oxford Hip Scores improved from 6.4 preoperatively to 38.6 postoperatively (mean gain 32.2 points), while UCLA Activity Scores increased from 2.4 to 7.1 (mean gain 4.7 points). Preoperative LLD averaged 2.34 cm, reduced to 0.29 cm postoperatively (mean correction 2.05 cm). Seven patients achieved complete equalisation, and 88% had ≤0.3 cm residual discrepancy. No stem revisions, dislocations, or loosening were observed.

Conclusions: Custom-made femoral stems guided by HIP-PLAN® 3D planning enable precise anatomical reconstruction and durable functional recovery in patients with complex femoral morphology. These findings support the role of patient-specific implants in modern hip arthroplasty.