A Modified Extra-articular Lateral Column Lengthening Procedure for Adult Acquired Flatfoot Deformity.

BACKGROUND

Lateral column lengthening (LCL), originally described by Evans, is an established procedure to correct stage II adult acquired flatfoot deformity (AAFD). However, the relative position between the facets is violated, and other problems may include nonunion, malunion, and calcaneocuboid (CC) joint subluxation. Herein, we report a modified extra-articular technique of LCL with hockey-stick osteotomy, which preserves the subtalar joint as a whole, increases bony apposition to enhance healing ability, and preserves the insertion of the calcaneofibular ligament to stabilize the posterior fragment to promote adduction of the forefoot.

METHODS

We retrospectively recruited 24 patients (26 feet) with stage II AAFD who underwent extra-articular LCL. The mean age was 55.7 ± 15.7 years, and the mean follow-up period was 33.4 ± 12.1 months. Associated procedures of spring ligament repair/reconstruction and posterior tibial tendon plication or flexor digitorum longus transfer were routinely performed and may also include a Cotton osteotomy, heel cord lengthening, or hallux valgus correction. Clinical and radiographic outcomes at the final follow-up were compared with the preoperative assessments.

RESULTS

All patients achieved calcaneus union within 3 months of operation. The VAS pain score improved from 5.3 ± 0.75 preoperatively to 1.2 ± 0.79 at the final follow-up ( < .001), and the AOFAS Ankle-Hindfoot Scale from 63.5 ± 8.5 to 85.8 ± 4.8 points ( < .001). The radiographic measurements significantly improved in terms of the preoperative vs final angles of 8.9 ± 5.3 vs 15.2 ± 3.6 degrees for calcaneal pitch ( < .001), 20.5 ± 9.2 vs 4.9 ± 4.8 degrees for Meary angle ( < .001), 46.5 ± 5.2 vs 41.9 ± 3.2 degrees for lateral talocalcaneal angle ( < .001), 23.9 ± 8.5 vs 3.9 ± 3.1 degrees for talonavicular coverage angle ( < .001), and 18.2 ± 9.2 vs 7.3 ± 5.0 degrees for talus-first metatarsal angle ( = .002). The CC joint subluxation percentage was 7.0% ± 5.4% preoperatively compared with 8.5% ± 2.4% at the final follow-up ( = .101). No case showed progression of CC joint arthritis or CC joint subluxation (>15% CC joint subluxation percentage). One case showed transient sural nerve territory paresthesia, and 1 had pin tract infection. Three cases had lateral foot pain, which could be relieved by custom insoles.

CONCLUSION

Modified extra-articular LCL as part of AAFD correction is a feasible alternative technique without subtalar joint invasion and may be associated with less CC joint subluxation compared with the Evans osteotomy.

LEVEL OF EVIDENCE

Level IV, retrospective case series.