The anatomical location of the flexor hallucis brevis as it pertains to implant arthroplasty.

BACKGROUND Hallux limitus/rigidus is a painful arthritic condition affecting the first metatarsophalangeal joint that can be treated by implant arthroplasty, which, ultimately, may cause loss of the anatomical insertion points of the flexor hallucis brevis muscle. Preparation of the base involves resection of bone, thus compromising the insertion of the flexor hallucis brevis muscle. METHODS We dissected 54 fresh-frozen cadaveric specimens and quantitatively measured the distalmost insertion point of the medial and lateral heads of the flexor hallucis brevis muscle. These measurements were performed for both heads. The measurements were performed three times by three separate examiners. In addition, taking into consideration the anatomical construct of the articular surface of the base of the proximal phalanx of the hallux, another measurement was performed to note the concavity using 44 of the specimens. Again, these measurements were performed three times by three separate investigators. RESULTS The mean length from the base of the proximal phalanx to the distalmost insertion of the medial and lateral heads of the flexor hallucis brevis muscle was found to be 7 mm. CONCLUSIONS This study provides precise anatomical data that can be used by foot and ankle surgeons when considering the use of implant arthroplasty for the treatment of hallux limitus/rigidus and the ability to maintain the insertion point of the flexor hallucis brevis muscle.