Background: Angular deformity around the knee joint in patients with multiple epiphyseal dysplasia (MED) causes alteration in knee biomechanics as well as cosmetic problem. We report angular correction by hemiepiphyseal stapling (HES) and physeal behavior after stapling removal in MED patients.
Methods: In 17 knees of 9 MED patients, 16 distal femoral and 8 proximal tibial physes were stapled. Age at operation ranged from 8.2 to 13.9 years. Thirteen knees were in valgus alignment and 3 in varus and were followed up for an average of 3.9 years. Angular deformity change was evaluated by the anatomical lateral distal femoral angle or anatomical medial proximal tibial angle. Mechanical axis deviation was defined as the percentage ratio of distance from the knee joint center to mechanical axis divided by half the width of the tibial plateau.
Results: Amount of angular correction by HES at the distal femur was 15.3 +/- 6.4 degrees for an average of 17.4 months, and at the proximal tibia, 8.6 +/- 2.0 degrees for an average of 13.4 months. Twelve distal femoral physes remained stationary (angular change <3 degrees) and 4 rebounded (loss of correction >3 degrees) after staple removal, whereas 5 proximal tibial physes remained stationary, 2 rebounded, and 1 was progressive. Neither hardware problems nor clinical complications other than overcorrection or undercorrection were encountered. At the latest follow-up, mechanical axis deviation remained within +/-50% in 14 of 17 knees. The remaining 3 knees failed because of premature closure of the distal femoral physis, causing undercorrection of the deformity, insufficient rebound of an overcorrected knee, or progressive angular change after staple removal.
Conclusions: Hemiepiphyseal stapling is effective for angular correction in MED with minimal surgical insult. However, as physeal behavior after staple removal is rather unpredictable, overcorrection over zone 1 should be avoided, and close monitoring is mandatory until skeletal maturity.