Introduction/Purpose: Bunionectomy is one of the most common procedures performed in foot and ankle surgery, and the modified Lapidus has become a prominent technique for surgical correction of hallux valgus in the United States. The emerging minimally invasive (MIS) approach has sparked discussion regarding the comparative advantages and limitations over the established open technique for modified Lapidus. The clinical distinctions, including patient-reported outcomes, radiographic measurements, and complication rates between the two operative methods have not yet been well-described. To our knowledge, this is the first study to compare patient-reported outcomes measured by Patient-Reported Outcome Measurement Information System (PROMIS) scores between the two techniques. We hypothesize that at one year after surgery, the changes in clinical outcomes will be comparable between the MIS and open cohorts.
Methods: 140 severe hallux valgus patients (66 MIS, 74 open) between June 2017 – April 2024 with both pre- and post-operative weight-bearing CT (WBCT) scans, PROMIS scores, a minimum of one-year follow- up were identified via retrospective review. The MIS Lapidus was performed through three percutaneous 6mm incisions using two screws spanning the first TMT joint and one screw spanning the medial cuneiform and second metatarsal base following joint preparation with a burr through a small incision. In open Lapidus cases, joint preparation was performed using saw cuts and removal of a small lateral wedge from the medial cuneiform before dorsal plate and screw fixation across the first TMT joint. Hallux valgus angle (HVA) and 1-2 intermetatarsal angle (IMA) were measured on X-rays. Meary’s angle, first ray length, first ray elevation, first ray pronation, and sesamoid position were analyzed on WBCT. Surgical complications were identified through chart review and postoperative radiographic assessments.
Results: MIS Lapidus and open Lapidus patients reported clinically meaningful improvements in PROMIS physical function, pain interference, pain intensity, and global physical health scores at one year after surgery, along with modest changes in global mental health and depression scores. There were no statistically significant differences in PROMIS scores between either approach (adj. p > 0.05, 95% CI). Open Lapidus patients experienced statistically significant greater correction of HVA, IMA, and Meary’s angle of 3.82º, 2.02º, and -3.16º respectively (adj. p < 0.05). There were no statistically significant differences (MIS - Open) in correction of first ray length (-1.4 mm), elevation (0.445°), pronation (2.92°) or sesamoid position. Rates of postoperative events were not statistically significant between surgical cohorts (Table 2).
Conclusion: Our data show that there are no statistically significant differences between MIS and open Lapidus groups across all collected PROMIS measures, implying surgeons can expect to see similar patient- reported outcomes at one year postoperatively. Additionally, the statistically significant differences in HVA, IMA and Meary’s angle were small and thus not clinically significant. Though there were no statistically significant differences in complication rates, studies with larger patient samples are needed to better assess these rates clinically. Future studies comparing these surgical techniques should assess short-term patient recovery to capture and compare weight-bearing and return to work timelines among other functional outcomes.
