Hallux metatarsophalangeal joint arthrodesis with a hybrid locking plate and a plantar neutralization screw: a prospective study.

BACKGROUND

Many techniques have been described for arthrodesis of the first metatarsophalangeal (MTP) joint. The purpose of this study was to determine the results of fixation using a low-profile dorsal titanium plate with locking screws in the phalanx, nonlocking screws in the metatarsal, and a plantar neutralization screw.

METHODS

Forty-nine consecutive patients (51 feet) underwent a first MTP joint arthrodesis during an enrollment period of 1 year from October 2010 to November, 2011. All patients were evaluated preoperatively for primary pathology, pain, function, radiographic findings, AOFAS scores, and physical exam findings. First MTP joint arthrodesis was performed with a precontoured dorsal titanium plate with preset valgus and dorsiflexion after the joint surfaces were prepared with dome-shaped power reamers to achieve congruous cancellous bone surfaces. At a minimum of 1-year follow-up, patients returned for postoperative evaluation of pain, function, radiographic findings, satisfaction, AOFAS scores, and physical exam findings.

RESULTS

Forty-six of 49 (48 feet) patients returned for final follow-up examination at least 12 months after operative intervention. Forty-one patients (89%) reported good to excellent results. Visual analog pain scores improved from an average of 6.6 preoperatively to an average of 1.6 postoperatively (t = -9.3339, df = 45, P < .001). Functional capacity scores improved from a preoperative mean of 2.5 to a postoperative mean of 1.4 (t = -5.2648, df = 46, P < .001). AOFAS hallux MTP joint scores improved from a preoperative mean of 45 to a postoperative mean of 77 (t = 9.9498, df = 46, P < .003). Eighteen of 48 great toes (38%) had preoperative pronation whereas, 2 of 48 great toes (4%) had postoperative pronation. Eleven of 46 patients (24%) were unable to perform preoperative toe rise, and 8 of 46 (17%) were unable to perform postoperative toe rise. Twenty-five of 46 patients (54%) had gait improvement, while 19 patients (44%) had no change in gait, and 2 patients (4%) had gait deterioration. The mean preoperative hallux valgus angle of 27 degrees improved to a mean postoperative angle of 13 degrees (t = -6.1982, df = 46, P < .001). The mean preoperative 1-2 intermetatarsal angle of 12 degrees improved to a mean postoperative angle of 9 degrees (t = -5.2614, df = 46, P < .001). There was 1 delayed union (2%) and 1 nonunion (2%).

CONCLUSION

Our outcome scores indicate that first MTP joint arthrodesis with a precontoured dorsal titanium plate with locking screws in the phalanx and nonlocking screws in the first metatarsal is both reliable and reproducible with a very high bony union rate.

LEVEL OF EVIDENCE

Level IV, prospective case series.