Clinical and functional outcomes of neo-adjuvant zoledronic acid therapy and valgus osteotomy in proximal femoral fibrous dysplasia.

BACKGROUND

Fibrous dysplasia (FD) is characterised by structurally weak bone due to disorganized fibro-osseous matrix, leading to pain, deformities and pathological fractures. While traditional treatments like curettage and bone grafting are ineffective due to graft resorption and lesion persistence, intramedullary fixation is currently preferred method to prevent recurrent deformities and fractures. This study aimed to evaluate the clinical and functional outcomes of neo-adjuvant zoledronic acid (ZA) therapy combined with valgus osteotomy in proximal femoral FD, and to assess changes in neck-shaft angle (NSA) and limb length discrepancy (LLD).

METHODS

This single centre, retrospective study included eight patients with proximal femoral monostotic/polyostotic FD treated between January 2021 and December 2023. All patients received three doses of intravenous ZA at 4-week intervals, followed by valgus osteotomy performed 8 weeks after the final ZA dose. Pre- and post-operative NSA and LLD were recorded and compared. Functional outcomes were assessed using the modified Guille criteria.

RESULTS

The mean age was 21.8 ± 6.68 years. Three patients had monostotic and 5 had polyostotic FD. Mean follow-up was 24.5 ± 6.4 months. All patients experienced pain relief post-ZA without serious adverse events, although only 2 showed radiological improvement. The mean modified Guille score improved from 3.5 ± 1.51 to 8.25 ± 1.48 (p = 0.01). The mean NSA improved from 100.75 ± 17.05° to 125.75 ± 8.31° (p = 0.044) and LLD reduced from 1.93 ± 0.72 cm to 0.93 ± 0.49 cm (p < 0.001). Union was achieved in all cases with a mean healing time of 6.25 ± 1.66 months.

CONCLUSION

Combining neo-adjuvant ZA therapy and valgus osteotomy offers significant functional improvement and deformity correction in proximal femoral FD. While ZA offers consistent pain relief, its radiological impact remains variable. Valgus osteotomy, stabilized with intra- or extramedullary fixation remains a valuable technique for managing FD-associated deformities. Further prospective studies are warranted to refine treatment protocols and validate long-term outcomes.