Transection of the deep metatarsal transverse ligament in Morton's neuroma surgery does not increase risk of splayfoot development.

PURPOSE: Although operative excision is regarded as the treatment of choice in Morton's neuroma, it remains unclear whether transection of deep transverse metatarsal ligament (DTML) is a risk for metatarsal splaying and whether simultaneous surgery in adjacent intermetatarsal spaces is a risk for osteonecrosis of the adjacent metatarsals.

METHODS: Fifty-seven feet in 47 patients had excision of a Morton's neuroma, with a mean follow-up of 15.3 years. Feet were categorised depending upon whether the DTML was or was not divided. Pre-operative and post-operative intermetatarsal angles were measured on standardised weightbearing radiographs and inspected for evidence of osteonecrosis.

RESULTS: Comparison of pre- and post-operative intermetatarsal angles in patients with surgery in the second web space showed no significant increase (transected p = 0.659, preserved p = 0.142). In regards to comparison of pre- and post-operative radiographic intermetatarsal angles in patients with surgery in the third web space, statistical analysis also did not show a significance increase (transected p = 0.240, preserved p = 0.078). Radiological assessment showed no signs of osteonecrosis of metatarsal heads, not even in cases of double-space surgery.

CONCLUSIONS: In conclusion, DTML transection does not increase the intermetatarsal angle or the risk of splayfoot development. Moreover, transection is recommended due to an enhanced overview during surgery and better clinical outcome. Our data could also prove that double-space surgery is not a risk for avascular osteonecrosis.