Effect of Blood Flow of the Metatarsal Head with Hallux Valgas after Minimally Invasive Distal Linear Metatarsal Osteotomy

Abstract

Category: Hindfoot Introduction/Purpose: Distal first metatarsal osteotomies are recommended for surgical treatment of mild to severe hallux valgus (HV) deformities. Angthong et al. reported that minimally invasive distal linear metatarsal osteotomy (DLMO) exhibited good outcomes, with no major complications. However, avascular necrosis of the metatarsal head following a distal osteotomy has been reported, because an aggressive plantar cut can disrupt the soft tissue plantarly, thereby disrupting the blood supply of digital arteries. The purpose of this study was to evaluate the in vivo blood flow of the pre- and post-osterotomy metatarsal head in patients with HV using laser Doppler flowmetry (LDF). Methods: Between April and November 2015, DLMO was performed on seven patients with HV. The patients comprised one male and four females, with a mean age at surgery of 43.4 (21–62) years. The primary surgical indications for DLMO were all levels of severity of possible manual correction in patients with foot pain. The patients were placed in the supine position, and without a tourniquet, a 1.5-cm skin incision was centered over the medial aspect of the first metatarsal neck. A 2.0-mm Kirschner wire was inserted manually from the wound to the medial side of the hallux using a retrograde technique. Under direct vision, the Kirschner wire was introduced into the medullary canal of the first metatarsal shaft. Blood flow measurements of the pre- and post-osteotomy first metatarsal head in the seven patients were performed by LDF (ALF21 N; ADVANCE Co., Tokyo, Japan). The probe was touched to the first metatarsal head. The blood flow measurements were repeated three times, and the mean values were calculated. Results: On preoperative plain radiographs, the mean hallux valgus angle was 38.0° (range: 22.4–45.8°), and the mean intermetatarsal angle was 17.0° (range: 10.4–21.9°). The mean pre- and post-DLMO systolic blood pressure at the time of the measurements was 87.3±7.76 and 88.1±8.25 mmHg, respectively (P=0.85). The mean pre- and post-DLMO blood flow rate was 1.71±0.68 and 1.66±0.49 ml/min/100 g, respectively (P=0.90). Conclusion: Steven et al. reported that a distal osteotomy can lead to avascular necrosis of the metatarsal head, because an aggressive plantar cut can disrupt the soft tissue plantarly, thereby disrupting the blood supply of digital arteries. However, we found that blood flow of the pre- and post-osteotomy metatarsal head was present in all patients examined, with no significant difference in the blood flow rates of the metatarsal head before and after DLMO. Based on the present results, it is possible to avoid major complications, such as avascular necrosis of the metatarsal head, because DLMO is minimally invasive and involves less release of the soft tissue.