The role of diagnostic block in the management of Morton's neuroma.

OBJECTIVE: To determine the outcome of surgical excision of Morton's neuroma after a local anesthetic diagnostic block into the neuroma has relieved symptoms.

DESIGN: A cohort study.

SETTING: A university affiliated hospital.

PATIENTS: A sequential series of 37 patients who underwent 41 excisions with at least 2 years' follow-up. Seven patients had undergone repeat excision of a neuroma, and 34 primary excisions were performed. Surgery was performed by a specialist in orthopedic surgery of the foot and ankle.

INTERVENTION: Excision of the Morton's neuroma after a positive diagnostic block.

MAIN OUTCOME MEASURES: Grade of symptoms at follow-up done by independent review on a 4-point scale.

RESULTS: Of 41 procedures, 11 had an unfavourable outcome: 4 procedures were graded 3, and 7 procedures were graded 4. Eight (24%) of the 34 primary procedures were reported as failures, and 3 (43%) of the 7 revision procedures were reported as failures. Most patients reported poor results owing to persistent pain.

CONCLUSIONS: Diagnostic blocks do not improve the results of surgery for excision of Morton's neuroma and are not recommended. Because failure rates are greater than 20%, surgery for Morton's neuroma should only be offered after a full course of nonoperative management.