First Metatarsal Rotation After Scarf Osteotomy for Hallux Valgus

Abstract

Background Recurrence after surgical correction of hallux valgus may be related to coronal rotation of the first metatarsal. The scarf osteotomy is a commonly used procedure for correcting hallux valgus but has limited ability to correct rotation. Using weight-bearing computed tomography (WBCT), we aimed to measure the coronal rotation of the first metatarsal before and after a scarf osteotomy, and correlate these to clinical outcome scores. Methods We retrospectively analyzed 16 feet (15 patients) who had a WBCT before and after scarf osteotomy for hallux valgus correction. On both scans, hallux valgus angle (HVA), intermetatarsal angle (IMA), and anteroposterior/lateral talus-first metatarsal angle were measured using digitally reconstructed radiographs. Metatarsal pronation angle (MPA), alpha angle, sesamoid rotation angle, and sesamoid position were measured on standardized coronal WBCT slices. Preoperative and postoperative (12 mo) clinical outcome scores (Manchester Oxford Foot Questionnaire and Visual Analogue Scores) were captured. Results Mean HVA was 28.6 ± 10.1° preoperatively and 12.1 ± 7.7° postoperatively (P < .001). Mean IMA was 13.7 ± 3.8° preoperatively and 7.5 ± 3.0° postoperatively (P < .001). Before and after surgery, there were no significant differences in MPA (11.4 ± 7.7 and 11.4 ± 9.9°, respectively; P = .75) or alpha angle (10.9 ± 8.0 and 10.7 ± 13.1°, respectively; P = .83). There were significant improvements in sesamoid rotation angle (SRA) (26.4 ± 10.2 and 15.7 ± 10.2°, respectively; P = .03) and sesamoid position (1.4 ± 1.0 and 0.6 ± 0.6, respectively; P = .04) after a scarf osteotomy. There were significant improvements in all outcome scores after surgery. Poorer outcome scores correlated with greater postoperative MPA and alpha angles (r = .76 (P = .02) and .67 (P = .03), respectively). Conclusion A scarf osteotomy does not correct first metatarsal coronal rotation, and worse outcomes are linked to greater postoperative metatarsal rotation. Rotation of the metatarsal needs to be measured and considered when planning hallux valgus surgery. Further work was needed to compare postoperative outcomes with rotational osteotomies and modified Lapidus procedures when addressing rotation. Level of Evidence: 4

Impact of Sesamoid Coverage on Clinical Foot Function Following Fourth-Generation Percutaneous Hallux Valgus Surgery

“…We were unable to find any studies reporting the relationship between clinical outcomes and sesamoid coverage/pronation in the context of percutaneous hallux valgus surgery. A series of 16 feet by Najefi et al 13 that investigated pronation 12 months following scarf osteotomy found poorer MOXFQ outcome scores in patients with higher postoperative pronation of the metatarsal, which is contradictory to our findings. Ferreira et al 5 evaluated the round sign post-percutaneous hallux valgus surgery in 45 feet and found the proportion of feet with mild or absent pronation increased from 29% to 55%; however, they did not evaluate if this had an impact on clinical PROMs.…”

“…There are current theories that failure to reduce the sesamoids and residual pronation of the first metatarsal may lead to increased recurrence rates, yet there are very limited studies reporting the clinical outcomes based on sesamoid coverage or residual pronation. 2 , 4 , 13 , 14 , 20 Chen et al 2 found correcting the tibial sesamoid position to less than grade IV (using the Hardy and Clapham classification) led to poorer functional outcome and patient satisfaction 2 years following surgery in a large series of 250 patients.…”

“…There are theories that residual rotational deformity or sesamoid coverage may predispose to recurrence, and the advent of weightbearing computed tomography has enabled assessment of the rotational deformity and correction that can be achieved during hallux valgus surgery. 4 , 13 , 14 , 19 , 20 …”

“…5 , 6 , 10 There are, however, very few studies investigating the outcomes in patients with residual sesamoid uncoverage with either open or minimally invasive techniques. 4 , 13 …”