[Long-term results of midtarsal arthrodesis for flatfoot in adults]

Arthrodesis proposed for the surgical treatment of reducible pes planovalgus (flatfoot) in adults is designed to relieve pain and correct the deformity. The purpose of this work was to present the radiological and clinical results obtained with midtarsal arthrodesis performed in 22 cases of pes planovalgus.

This study concerned 22 cases of reducible flatfoot (Johnson grade 2) in 19 patients (11 males, 8 females, mean age 43 years, age range 15-75 years). Clinical outcome was assessed in terms of pain, function and motion using the AOFAS and Mann classifications. Radiological assessment (loaded anteroposterior and lateral views with Méary cerclage) noted the Djian angle, talometatarsal alignment, talar slope, calcaneal slope, calcaneal valgus, and osteoarthritis stage in adjacent joints.

Mean follow-up was 7 years 4 months (range 6 months-20 years 3 months). Two nonunions resolved favorable after cancellous grafting. The Kitaoka score was 73.5/100 points (range 53-94). Pain and function improved from 2.8 to 1.1 points (/4 points) and from 3.45 to 1.6 points (/4) on the Mann scale. Flexion-extension remained unchanged. The foot was aligned correctly in 68% of cases. The mean talar slope and the talocalcaneal divergence were normal at last follow-up but there was a persistent undercorrection of the Djian angle in 68% of the feet and a break in the Méary line in 41%. Calcaneal valgus was reduced 6.6 degrees (16.6 to 10 degrees ) but the podoscope footprint was still the flatfoot type in 86% of the feet. For 50%, the neighboring joints presented progressive osteoarthritic degeneration. Subjectively the patients were very satisfied or satisfied with minor reservations for 73%. None of the patients was disappointed with the results. The objective outcome was excellent or good in 68% of the feet.

The results in terms of pain relief, function, motion, complications, and rate of satisfaction were comparable with results presented in the literature. Midtarsal arthrodesis provides effective pain relief and satisfactory functional recovery without creating any morbidity greater than simple talonavicular fusion. Nevertheless, it was noted that while correct alignment is achieved in the majority of cases, the clinical and radiological restoration of plantar cavum is limited. Furthermore compensatory hypermobility of the adjacent joints leads to the development of moderate osteoarthritic remodeling which remains asymptomatic more than seven years after the operation.