Abstract
Introduction
Functional hallux limitus (FnHL) can arise from medial column instability caused by pathological compensation within the closed kinetic chain. This report presents a surgical case of FnHL attributed to instability at the naviculocuneiform joint (NCJ) following failed conservative management.
Methods
Medial column stability was addressed with a Cotton osteotomy, using the cuneiform articular angle (CAA) to determine appropriate graft size. An Austin osteotomy and proximal Akin were performed to correct a bunion deformity, while posterior muscle group lengthening was added to reduce rearfoot-driven strain on the medial column. Medial column integrity was evaluated preoperatively and at one year postoperatively via weight-bearing lateral radiographs, assessing the medial arch sag angle (MASA), CAA, medial cuneiform height (MCH), and Meary’s angle. Confirmation bias was reduced by using radiographic angles to support subjective outcomes of procedure.
Results
Postoperative imaging demonstrated notable improvement in CAA, Meary’s angle, and MCH, confirming correction of medial column instability. MASA remained unchanged. The bunion deformity was also corrected radiographically. Clinically, the patient showed improved 1st metatarsophalangeal joint (MPJ) function, with the metatarsophalangeal-interphalangeal (MTP-IP) score increasing from 62 to 90 at one year.
Conclusion
This appears to be the first report describing the combined use of a first metatarsal distal shaft osteotomy, Cotton osteotomy, and posterior muscle group lengthening to improve both 1st MPJ function and medial column stability during gait. A novel NC fault classification system is introduced to guide preoperative planning for medial column instability.
Introduction
Functional hallux limitus (FnHL) can be defined as reduced 1st MPJ dorsiflexion during weight-bearing, despite normal motion in the open-chain, making diagnosis challenging. Proper propulsion requires adequate ankle ROM and a stable medial column so the hallux can dorsiflex over the first metatarsal. FnHL arises from instability at the tarsometatarsal joint (TMTJ), NCJ, talonavicular joint (TNJ), or all three, often linked to abnormal pronation. , Recent work highlights the NCJ as a frequent site of medial column pathology.
Identifying the apex of deformity is essential for effective treatment. This can be evaluated clinically and with weight-bearing radiographs or CT. In this case, medial column stability was assessed with MASA, CAA, MCH, and Meary’s angle as seen in Fig. 1 . MASA is corrected when the proximal articular surface of the first metatarsal is plantarflexed compared with the proximal articular surface of the navicular. Castaneda et al. described the CAA as the angle between the medial cuneiform’s proximal and distal articular surfaces, with the ideal angle showing plantarflexion of the distal surface. These measurements, obtained on lateral weight-bearing radiographs, help gauge the effectiveness of a Cotton osteotomy, which improves medial column stability, plantar fascia tension, and 1st MPJ motion.
( A&B ) Preoperative and (C&D) One-year postoperative lateral weight-bearing radiographs of the patient’s left foot. (A) Preoperative angles: MASA (Pink) of 5 degrees, CAA (Orange) of 8 degrees, and an MCH (Green) of 20 mm. (B) Preoperative Meary’s angle (Blue) of 8 degrees. (C) One-year postoperative angles: MASA of 5 degrees, a CAA of 14 degrees, and an MCH of 27 mm. (D) One-year postoperative Meary’s angle of 2 degrees. Note the radiographically corrected medial column instability with improved NC sag, CAA, Meary’s, and MCH. The Cotton osteotomy demonstrated no effect on the MASA.
Ankle motion also influences FnHL: limited dorsiflexion increases plantar fascial tension during gait, restricting 1st MPJ dorsiflexion. Thus, evaluation of the gastrocnemius-soleus complex is critical. This study examines a combined approach—first metatarsal distal shaft osteotomy, Cotton osteotomy, and posterior muscle group lengthening—to improve medial arch stability and 1st MPJ function. A novel NC fault classification system is also proposed to guide correction.
Case
A 53-year-old man with HIV presented with painful left bunion deformity unresponsive to conservative therapy. He reported dull 1st MPJ pain with activity. Weight-bearing 1st MPJ ROM was 0° (75° non-weight-bearing). Hubscher maneuver showed medial arch collapse with reconstitution, and the reverse Coleman block test localized deformity to the NCJ with first-ray elevatus. A painful EHL-associated soft-tissue mass was also present. Ankle ROM with the left knee extended was 3 degrees and when flexed was 10 degrees, signifying gastrocnemius equinus.
All radiographic angles were accurately measured using the Cobbs angle function on Epic Systems Corporation software (Copyright © 2022). Pre-operative x-rays ( Figs. 1 A, 1 B) demonstrated Meary’s angle of 8° (apex plantar), NC sag, MASA 5°, CAA 8°, and MCH of 20 mm. Transverse plane deformities were also measured and can be seen in Fig. 2 A. Based on the proposed NC fault classification ( Table 1 ), the patient was stage 1, indicating need for a 6-mm Cotton osteotomy. Planned procedures included gastrocnemius recession, long-arm Austin bunionectomy, proximal Akin, and Cotton osteotomy.
Preoperative (A) and one-year postoperative (B) dorsal-plantar weight bearing radiographs of the patient’s left foot. (A) Preoperative angles: IM (purple) of 17 degrees, HI (olive) of 17 degrees, and HA (medial olive and medial purple lines) of 19 degrees. (B) One-year postoperative angles: IM of 2 degrees, HI of 14 degrees and HA of 1°. Note the radiographically corrected medial “bunion bump” by improvement of IM and HA angles.
Table 1
A Novel NC Fault Classification System.
| Stage | Deformity | Imaging studies | Treatment Options |
|---|---|---|---|
| 1 | Mild | The sag is mild or subtle on standard weight-bearing lateral radiography but evident on reverse Coleman block test radiograph or standing CT scan. Mild CAA and MASA | Cotton osteotomy with 4–6 mm graft or plantar closing wedge osteotomy of the medial cuneiform |
| 2 | Moderate | The sag is evident on standard weight-bearing lateral radiograph and exaggerated on reverse Coleman block test radiograph or standing CT scan. Moderate CAA and MASA | Cotton osteotomy with 6–8 mm graft placement or plantar closing wedge osteotomy of the medial cuneiform |
| 3 | Severe w/o arthritis | Collapse of the medial column with TNJ and NCJ sag evident on standard weight-bearing lateral radiograph or standing CT scan without arthrosis. Severe CAA and MASA | Isolated fusion of the NC joint or medial column fusion |
| 4 | Severe w/ arthritis | Collapse and arthrosis of the medial column with TNJ and NCJ sag evident on standard weight-bearing radiograph or standing CT scan. Severe CAA and MASA | Isolated fusion of the NC joint or medial column fusion |
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