Management of metacarpophalangeal bone defects after hand trauma by distraction osteogenesis with mini external fixation

Abstract

Objective To evaluate the outcomes of distraction osteogenesis with mini external fixation in management of metacarpophalangeal bone defects after hand trauma. Methods From June 2010 to December 2015, 16 patients with metacarpophalangeal bone defects after hand trauma received distraction osteogenesis at our department. They were 11 men and 5 women, from 20 to 45 years of age (average, 32.5 years). There were altogether 20 bone defects: 8 cases had single metacarpal bone defect, 2 unilateral second and third metacarpal bone defects and 6 phalangeal shortening after repair of digital stump (involving thumb in 4 cases, index finger in one and index and middle fingers in one). The metacarpophalangeal bone defects averaged 1.8 cm (from 1.0 to 3.1 cm). Under the fluoroscopic guide, 4 or 6 mini half-pins in one line were directly drilled into the dorsal aspect of the involved metacarpophalangeal bone before the Orthofix fixator was mounted. The proximal (18 digits) or distal (2 digits) osteotomy between the second and third pinholes was performed via the dorsal approach. The external fixator and pins were removed without anesthesia after callus maturation. Results Average follow-up period was 12.2 months (range, from 9 to 26 months). All the metacarpal bone defects were reconstructed and all the phalangeal shortenings were lengthened; the bony callus was completely calcified at the lengthened part. The mean lengthening was 1.9 cm (from 1.0 to 3.1 cm); the percentage of lengthening ranged from 26% to 51% (average, 34%). The bone lengthening index (time cost by average 1 cm) was 70.9 d/cm (from 60.0 to 87.1 d/cm). According to the Tentative Assessment Criteria for Upper Extremity Function by Hand Surgery Society, Chinese Medical Association, the total activity of motion (TAM) was excellent in 13 cases, good in 4, fair in 2, and poor in one, yielding an excellent to good rate of 85.0%. Conclusion Distraction lengthening using mini external fixation is a valid option with a minor rate of complications which allows for early functional exercise to help restore the appearance and function of the affected fingers. Key words: Hand; Injury; External fixators; Bone lengthening; Bone defect