Biceps rerouting and derotational radial osteotomy: A technique for correcting forearm supination in NBPBP.

INTRODUCTION: Forearm supination deformity is a recognized late sequela of neonatal brachial plexus birth palsy (NBPBP) that can impair functional positioning of the hand and limit activities requiring forearm pronation. Surgical options include forearm osteotomy, tendon rerouting, tendon transfer, and combined procedures. We describe a modified technique combining derotational radial osteotomy with biceps tendon rerouting using cortical button fixation.

METHODS: This was a single-patient technical case report. An 18-year-old male with longstanding fixed forearm supination deformity secondary to NBPBP underwent radial derotational osteotomy and biceps tendon rerouting. The biceps tendon was detached with the forearm in maximal supination, rerouted through the interosseous space, and secured with a cortical button with the forearm in maximal pronation. A radial osteotomy was subsequently performed toward pronation with approximately 30° to 45° of rotational correction. Postoperative rehabilitation included protected immobilization followed by progressive range of motion and strengthening.

RESULTS: Preoperatively, the forearm rested in approximately 15° of supination, with active pronation limited to neutral and active supination to approximately 50°. Following surgery, the forearm rested in approximately 15° to 20° of pronation. Passive forearm rotation improved from 45° of supination to 40° of pronation preoperatively to 60° of supination to 75° of pronation postoperatively. At 12 months, active pronation improved from neutral to 55° of pronation. No postoperative complications were reported during follow-up. The patient participated in occupational therapy 1 to 2 times weekly during recovery.

CONCLUSION: This case demonstrates the technical feasibility of combining radial derotational osteotomy with biceps tendon rerouting using cortical button fixation for longstanding supination deformity following NBPBP. The technique provides an additional fixation option for tendon rerouting while addressing the underlying osseous rotational deformity. Given the single-patient design and absence of comparative or biomechanical data, further study is required to determine whether cortical button fixation offers advantages over established tendon fixation methods and to evaluate the reproducibility and clinical efficacy of this approach.