Minimally invasive distal linear metatarsal osteotomy for correction of hallux valgus: a preliminary study of clinical outcome and analytical radiographic results via a mapping system.

PURPOSES: To date, actual results of a minimally invasive distal linear metatarsal osteotomy (DLMO) via more explicit radiographic delineation are poorly understood and radiographic findings and clinical results have not been systematically correlated. Purposes of this study were (1) to evaluate the effectiveness of DLMO using a precise radiographic mapping system; and (2) to determine the relationship between radiographic outcomes and clinical results.

MATERIALS AND METHODS: In 2008-2011, DLMO was performed in 30 patients (36 feet) who had reducible symptomatic hallux valgus. Clinical data were assessed using American Orthopaedic Foot and Ankle Society (AOFAS) score. Radiographs were reviewed at preoperative and final follow-up for delineations of first ray construct, hallux valgus angle (HVA), intermetatarsal angle (IMA), distal metatarsal articular angle, and other radiographic profiles. Correlation between postoperative AOFAS score and degree of malalignment was also analyzed.

RESULTS: A total of 36 feet had predominantly moderate hallux valgus (26 feet with HVA: 21-39°; 23 feet with IMA: 12-17°). Mean preoperative and postoperative AOFAS scores were 70.2 ± 11.3 and 95 ± 6.4, respectively (p < 0.001). Mapping system revealed improvements of first ray construct deformity (p < 0.05). Significant reductions in all angular measurements were observed at final follow-up period (p < 0.001) and correlated significantly with changes in AOFAS score (p < 0.001). Nine feet (25 %) were observed with recurrence of deformity which showed HVA >15°. Significant sesamoid lateralization was observed (p < 0.05). Twenty-four feet (66.7 %) showing overall sagittal malunions were found with significant plantar angulation (p = 0.026) and non-significant plantar displacement compared with preoperative reference (p = 0.43). These radiographic abnormalities were not related to clinical outcomes including postoperative AOFAS scores (p > 0.05).

CONCLUSION: DLMO is an acceptable procedure to correct reducible hallux valgus in most patients with moderate level of severity. Sagittal malunion, recurrence, and sesamoid lateralization are possibly radiographic abnormalities but are not associated with clinical impairments.