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°. We assessed functional and anatomic outcome.

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°. 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° 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.

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.

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°. The procedure is simple and morbidity is relatively low compared with the regularly successful results. When the flexion contracture exceeds 30°, 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.

Le flexum poliomyélitique du genou entraîne un handicap majeur dans les performances fonctionnelles du handicapé moteur. Parmi les différentes méthodes de correction des flexums du genou, l'ostéotomie fémorale supra-condylienne d'extension est la plus utilisée et ses résultats méritent d'être évalués et estimés par rapport aux autres méthodes thérapeutiques.

Quatre-vingt-treize ostéotomies supra-condyliennes réalisées chez 87 patients ont été revues avec un recul moyen de deux ans. L'extension du genou a été obtenue par impaction diaphyso-métaphysaire après résection d'un coin antérieur supra-condylien et la stabilité de la correction a été assurée par le respect d'une charnière postérieure et une ostéosynthèse par agrafes.

La correction peropératoire du flexum a été obtenue dans tous les cas.

Les complications les plus sévères ont été 3 cas d'arthrite septique du genou ayant entraîné une raideur en extension. Deux paralysies du nerf fibulaire commun ont récupéré spontanément. Les récidives, au nombre de 5, peuvent être accessibles aux ostéotomies itératives (3 cas de reprises). Le secteur de mobilité du genou est resté sensiblement le même mais a subi un transfert vers l'extension : ce que le patient gagne en extension, il le perd en flexion.

L'amélioration de la fonction globale du patient a été considérable : la marche devient autonome sans stabilisation du genou par la main et l'appareillage devient aisé pour les patients chez lesquels l'importance des paralysies rend l'appareillage indispensable. Cependant, l'ostéotomie supra-condylienne du genou garde des limites

• les flexums de plus de 30° nécessitent une libération des parties molles en raison de la tension excessive sur le paquet vasculo-nerveux ;
• chez le jeune enfant, en dessous de 12 ans, le risque de récidive du flexum est important par la migration du foyer d'ostéotomie et du fait du remodelage du cal de l'ostéotomie.