Release of the Lateral Structures of the First Metatarsophalangeal Joint during Hallux Valgus Surgery

PURPOSE OF THE STUDY Operations of hallux valgus deformity are very well known in orthopaedic surgery. The important part of these procedures is the release of soft tissue on the lateral side of the first metatarsophalangeal joint. Soft tissue procedures became routinely used in the 1920s and 1930s and several techniques of soft tissue release have been published in the past seventy years. We found several inaccuracies between the anatomy published and the routine clinical performance. The purpose of the study was to describe the anatomy of the first metatarsophalangeal joint's lateral part, especially the adductor hallucis muscle attachment, and to assess to what extent the lateral structures of the first metatarsophalangeal joint should be released to correct hallux valgus deformity. MATERIAL We described and compared the anatomy of the lateral part of the first metatarsophalangeal joint on 30 dissected specimens obtained from cadavers that met the criteria of hallux valgus deformity. METHODS The standard preparation method was used for anatomical dissection; whole leg specimens including the pelvic girdle were fixed in formaldehyde, acetone, ethyl-alcohol and glycerol. The detailed course and shape of the adductor muscle attachment was described as well as its relation to the lateral sesamoid bone, lateral portion of the flexor hallucis brevis and the transverse metatarsal ligament. Dissection of the joint's lateral capsule was used to show the course of the lateral collateral ligament, sesamoid ligament and conjoined tendon of the adductor hallucis and flexor hallucis brevis muscles. Subsequently, we released the lateral sesamoid ligament with a standard longitudinal cut and then released the conjoined tendon and lateral collateral ligament at the level of the joint gap in the frontal plane. We evaluated the proposed technique in terms of the extent of soft tissue release and the size of tenotomy necessary to correct the deformity. RESULTS The mean valgus deformity was 32 degrees (range, 18 degrees to 50 degrees). We were not able to define space between the medial border of the adductor hallucis and the flexor hallucis brevis in 23 cases (77%). The mean size of release was 6.4 mm (range, 5 to 15 mm) and the width of a conjoined tendon at the level of release was 11.2 mm (range, 8 to 15 mm). We did not achieve satisfactory release with our technique in two cases (7%, deviation 45 degrees and 50 degrees). DISCUSSION We compared our results with those of similar anatomical studies. We found several inaccuracies in anatomical descriptions of the adductor hallucis attachment. We confirmed the difficulty in separation of the adductor hallucis from the lateral head of the flexor hallucis brevis in total tenotomy of the adductor. Our technique was successful in releasing the first metatarsophalangeal joint's lateral structures. CONCLUSIONS Our study showed than even partial tenotomy of the conjoined tendon of the adductor hallucis and flexor hallucis brevis muscles is successful in correcting hallux valgus deformity. The release has to be combined with release of the lateral sesamoid ligament.