Acute shortening and re-lengthening (ASRL) procedure combined with RhBMP-2 to treat femur non-union with leg length discrepancy: a case report

Background: Femoral shaft non-union complicated by leg length discrepancy (LLD) and segmental bone loss remains a significant reconstructive challenge. Conventional bone transport techniques may involve long external fixation times, multiple surgeries, and soft-tissue morbidity. The acute shortening and re-lengthening (ASRL) method offers an alternative by achieving immediate bone contact and tissue closure, followed by gradual restoration of length. The adjunctive use of recombinant human bone morphogenetic protein-2 (rhBMP-2) may enhance osteogenesis at the docking and regenerate sites. Case presentation: We present a 24-year-old male patient with a femoral non-union and a 6 cm leg length discrepancy following multiple failed surgeries and hardware removal. The operative strategy comprised thorough debridement of the non-union site, acute shortening of the femur for direct end-to-end contact, application of rhBMP-2 at the docking interface, and placement of a monorail external fixator. A proximal femoral corticotomy was then performed for gradual distraction at 1 mm/day after a 10-day latency. Full-length restoration, radiographic union, and pain-free weight-bearing were achieved at 12 months. No major complications occurred. Clinical discussion: The ASRL technique, combined with rhBMP-2 on docking site, may represent a viable biomechanical-biological strategy for complex femoral non-union with LLD. Conclusions: The combined mechanical-biological strategy of ASRL with rhBMP-2 augmentation at docking site may offer a viable method for addressing femoral shaft non-union with leg length discrepancy.