First metatarsal shortening after hallux valgus surgery: Benefits of treatment with distraction osteogenesis.

Introduction: Iatrogenic shortening and elevation of the first metatarsal (MT1) is a common complication of hallux valgus surgery, inducing metatarsalgia underneath the lesser rays, a reason for patient dissatisfaction. For resolving this problem, different types of revision surgery are described, of which lengthening MT1 by distraction osteogenesis is underreported and therefore undervalued.

Materials And Methods: We present three cases with iatrogenic shortening after hallux valgus surgery treated by distraction osteogenesis of MT1 using a custom-made frame, made of Ilizarov equipment. To evaluate the amount of lengthening, the length of the first and second metatarsal (MT2) and the parabolic distribution of the metatarsal heads were compared before and after distraction. To evaluate correction in the sagittal plane, Meary's angle was measured pre- and post-lengthening. Pain was noted by a visual analogic score during follow-up.

Results: In our series of three cases, lengthening of MT1 between 7 mm and 18 mm, resulted in an improved parabolic distribution of the MT heads. The average difference between the second and first MT-head, relative to the SM4 axis (M2-M1) improved from 9.4 mm (± 0.9 mm) to 2.8 mm (± 0.7 mm) resolving corresponding pain in all patients. Meary's angle was normalized in one case. The average duration of treatment was 116 days (± 9 days). Minimal follow up was 11 years.

Conclusion: Using Ilizarov equipment for distraction osteogenesis of MT1 is a low-cost and effective method. Over time, this technique has proven its utility in pronounced iatrogenic shortening of MT1. The possibility to lengthen more than 1 cm, to correct in multiple planes, as well as early mobilization and weight bearing are additional advantages, but one must be careful to avoid overcorrection. The need for strict follow-up with multiple radiographs and rigorous patient selection is mandatory.