[Ankle instability with involvement of the subtalar joint demonstrated by MRI. Results with the Castaing procedure in 45 cases].

The authors report 46 cases of instability of the hindfoot involving the subtalar joint, with or without combined involvement of the tibiotalar ligaments, which were treated using Castaing's technique of ligament plasty between 1988 and 1999. Preoperatively, the patients complained of instability, recurrent sprains and pain. A tarsal sinus syndrome was present in 39%. Forty six patients underwent NMR examination which demonstrated capsuloligamentous lesions in every case. The results were evaluated using Kitaoka's score. With an average follow-up of 5.7 years after operation, instability was no more present in 80% and 63% were painfree. Clinical examination showed a reduction in the range of inversion of the hindfoot in 43%, with values between 50 and 70% of the contralateral foot, but without any significant clinical repercussion. Incipient osteoarthritis was noted on xrays in three patients. The overall results were very good in 82%, fair in 11% and poor in 7%. Eighty seven percent of the patients were satisfied with the result of the operation. The authors found a significant correlation between fair or poor results and a body mass index above 26 kg/m2 or constitutional laxity. Besides, results got worse as the time interval between the first sprain and the operative treatment increased. Comparison of these results with those of other techniques shows that they are essentially similar. Ligament plasty using Castaing's technique is a reliable operation but direct repair of ruptured ligaments at the subtalar joint should be preferred for primary treatment, leaving the possibility for secondary ligament plasty if necessary.