[Irreducible knee dislocation by medial capsulo-ligament incarceration].
OBJECTIVE
Irreducible dislocation of the knee is exceptional. Incarceration of the capsulo-ligamentary elements in the inter-condylar notch is a particular causal mechanism. We report four new cases and review the literature to describe the diagnostic and therapeutic approach.


METHODS
Between January 2001 and January 2002, four patients underwent surgery after trauma (wind surf, ski accidents) producing an irreducible knee dislocation. Mean patient age was 53 years and mean follow-up was 16 months. The IKDC classification was used to assess outcome.


RESULTS
Physical examination revealed characteristic signs: a groove facing the medial joint line with signs of cutaneous suffering just above and a fold line behind the medial condyle. Orthopedic reduction failed. Surgery was performed in all cases and revealed incarceration of the entire capsulo-ligamentary structure in the intercondylar notch with the medial condyle in an extra-articular position. After surgical reduction, healing was achieved in all cases without cutaneous necrosis. The mean subjective IKDC score was 53.9.


CONCLUSIONS
Orthopedic reduction is impossible in about 4% of all cases of knee dislocation. Clinical signs are characteristic when the medial capsulo-ligamentary structures are incarcerated in the intercondylar notch; the anatomic injury is almost always the same. Vasculonervous complications are exceptional but an emergency arteriography should be obtained to rule out an infra-clinical intimal lesion. Cutaneous necrosis is a specific complication of irreducible dislocation. Early and complete reduction is required to prevent necrosis. Arthroscopic management raises the risk of compartment syndrome since peripheral lesions are not healed. Satisfactory functional recovery requires associated repair of the cruciate ligaments.


CONCLUSIONS
This type of irreducible dislocation of the knee is a specific clinical entity. It usually results from postero-lateral rotation but may exceptionally occur after lateral dislocation. A groove associated with a fold line indicates the need for rapid surgical reduction to avoid the risk of cutaneous necrosis.
Chirpaz-Cerbat
J-M
JM
Service de Chirurgie Orthopédique et Traumatologique, CH d'Annecy, 1, avenue du Tresum, 74000 Annecy.
Rossi
J
J
Mélère
G
G
Martinez
T
T
D000328:Adult; D005500:Follow-Up Studies; D006801:Humans; D031221:Knee Dislocation / Q000150:complications / Q000601:surgery*; D008297:Male; D017888:Medial Collateral Ligament, Knee / Q000293:injuries*; D008875:Middle Aged