Foot pain after a plantar fasciotomy: an MR analysis to determine potential causes.

PURPOSE: The purpose of this work was to determine potential causes of foot pain in patients who have had a surgical release of the plantar fascia for treatment of fasciitis. METHOD: We studied 17 patients (15 women, 2 men; age range 22-59 years, mean 40 years) with foot pain after undergoing a fasciotomy. Fourteen unilateral and three bilateral procedures accounted for the 20 ankles evaluated. Mean duration after surgery was 22 months (range 3-53 months). Each patient was instructed to localize the pain to a region of the foot; classify the pain as new onset, persistent, or recurrent; and characterize it as to the action that produced the greatest pain. T1-weighted sagittal and dual-echo T2-weighted images in the sagittal, coronal, and axial planes were obtained in a 1.5 T magnet. The MR studies were evaluated for abnormalities of the plantar fascia, perifascial soft tissues, tendons, and osseous structures. RESULTS: The plantar fascia appeared thick in all ankles (mean 8.0 mm, range 6-12 mm). A total of 25 symptomatic sites were assessed. An acute plantar fascia rupture explained plantar symptoms in two feet. In another 16 feet (12 with plantar heel pain and 4 with nonspecific heel pain), 6 had documentation of acute plantar fasciitis and 9 demonstrated perifascial edema. Of the latter nine feet, five demonstrated abnormalities of the posterior tibialis, peroneus longus, and peroneus brevis tendons. The pain localized to the medial arch in six feet; five feet had abnormalities of the posterior tibialis tendon and one foot demonstrated edema in the flexor digitorum brevis muscle. The pain localized to the lateral midfoot in one foot, which had a cuboid stress fracture. CONCLUSION: The cause of foot pain in patients who had a plantar fasciotomy appeared to be multifactorial. Three likely causes of pain were identified: persistent or recurrent acute plantar fasciitis, pathology related to arch instability, and structural failure from overload.