[Supracondylar femoral extension osteotomy for knee flexion contracture correction in poliomyelitic conditions].

PURPOSE OF THE STUDY

Knee flexion contracture due to quadriceps paralysis is a major handicap in poliomyelitis patients. The patient has to stabilize the knee with the ipsilateral hand to achieve weight bearing and the deformed knee precludes use of orthopedic devices. Extension can be achieved with supracondylar femoral osteotomy if the knee flexion contracture is less than 30 degrees. We assessed functional and anatomic outcome.

MATERIAL AND METHODS

We reviewed the files of 87 patients who had undergone 93 supracondylar femoral osteotomies for knee flexion contracture (6 bilateral cases); mean age was 18 years and mean flexion was 25 degrees. The surgical correction was achieved by diaphyseal metaphyseal impaction with resection of an anterior wedge and preservation of the posterior component of the articulation. If some gluteus maximus activity was retained and the tibiotarsal joint was in a slightly equine position, weight bearing in a stable locked position became an automatic postural event even in case of total paralysis of the quadriceps. Osteotomy was not possible if the contracture flexion was greater than 30 degrees due to excessive tension on the vaculonervous bundles. The procedure was equally impossible in children under 12 years of age due to the risk of recurrence subsequent to migration and callus remodeling with bone growth.

RESULTS

Complete extension of the knee was achieved peroperatively in all cases. The most serious complications were three cases of septic arthritis that led to an irreducible stiff knee. In addition, we had two cases of transient paralysis of the common fibular nerve that recovered spontaneously. Bone fusion was achieved in all cases within 30 days. Recurrent flexion contracture was observed in 5 cases and required a revision using the same procedure in 3 or them. Postoperatively, the amplitude gained in knee extension corresponded to the amplitude lost for flexion. Sixty-three patients were able to walk independently without manual stabilization and a knee extension orthesis could be installed for 19 others. Three patients were still unable to walk despite the correction of the knee flexion contracture due to failure of poorly accepted orthopedic devices.

DISCUSSION

Several conservative methods (physiotherapy, manipulations, successive corrective casts) and surgical procedures (release of posterior soft tissues, Ilizarov technique) have been proposed for the correction of paralytic knee flexion contracture. Supracondylar femoral osteotomy for extension can be useful after the end of growth if the flexion contracture remains below 30 degrees. The procedure is simple and morbidity is relatively low compared with the regularly successful results. When the flexion contracture exceeds 30 degrees, the supracondylar osteotomy cannot be employed due to the risk of stretching the vasculonervous bundles and due to the instability and disorganization of the lower femur. Progressive correction can be proposed for these patients: regular monitoring of the neurological and vascular situation is required. Functional improvement is considerable after correction of knee flexion contracture. The patients can walk more easily, no longer need to stabilize their knee with their hand, and can benefit from orthopedic devises due to the more favorable biomechanical conditions.