Is Functional Reconstruction Feasible With Modified Hip Transposition Using a Customized 3D-printed Femoral...

Functional reconstruction after resection of malignant pelvic tumors involving zones I + II ± IV remains a major challenge in orthopaedic oncology. Conventional hip transposition can reduce prosthesis-related complications, but it is often associated with limb shortening and femoral head malrotation. We propose a modified hip transposition technique-femoral lengthening and retroversion hip transposition with a customized three-dimensionally (3D) printed femoral prosthesis-to address deficiencies in limb length, femoral head positioning, and fixation stability, and we evaluate its effectiveness in reducing complications and improving functional outcomes.

In the context of a small, initial patient series, we asked: (1) What was the postoperative functional outcome, as assessed by Musculoskeletal Tumor Society 1993 (MSTS-93) score, after reconstruction using this technique? (2) What were the frequency and nature of complications associated with the method? (3) How well was limb length restored at a minimum follow-up of 3 years?

Between January 2019 and December 2021, a total of 49 patients underwent resection and reconstruction for pelvic zone I + II ± IV tumors. Of these, 18% (9) received the modified hip transposition with a customized 3D-printed femoral lengthening and retroversion prosthesis. This approach was selected for patients in whom sufficient proximal femur was preserved to allow controlled osteotomy and femoral lengthening, who were unsuitable for standard hemipelvic endoprosthetic reconstruction because of extensive bone or soft tissue defects, who had histologically confirmed primary malignant or aggressive pelvic tumors, and who were expected to have long-term survival without distant metastasis. The remaining 82% (40) of patients treated during the same period underwent alternative reconstruction strategies, including hemipelvic endoprosthetic reconstruction, external hemipelvectomy, or conventional hip transposition. No patients were lost to follow-up. Three patients died of pulmonary metastases during follow-up and were included in the analysis with their actual follow-up durations. The six surviving patients had a median (range) follow-up time of 43 months (37 to 50). Among the nine patients included in this study, three were male and six were female, with a median (range) age of 55 years (19 to 73). At final follow-up, functional outcomes were assessed using the MSTS-93 score, complications were recorded and categorized, and limb-length discrepancy (LLD) was measured radiographically.

The six surviving patients achieved a median (range) MSTS-93 score of 24 (21 to 27) with minimal or no pain. Four patients used a cane for ambulation, and two walked independently. Two patients experienced delayed wound healing, which resolved with dressing changes; no prosthetic infections or mechanical failures occurred. Median (range) postoperative LLD was 1.0 cm (0.5 to 2.0) after intraoperative prosthesis adjustment.

This modified hip transposition technique utilizing patient-specific osteotomy guides and a 3D-printed femoral lengthening and retroversion prosthesis allowed adjustment of limb length and femoral rotation in this small series, with minimal postoperative LLD and no major complications observed. Larger studies with longer follow-up times will be needed to confirm the feasibility and functional benefit of this method as a valuable complement to existing reconstructive options, particularly for patients with extensive soft tissue defects and high functional demands.

Level IV, therapeutic study.