An original classification of congenital dislocation of the knee (CDK) was drawn up, based on neonatal semiology. The objective of the present study was to assess impact on treatment decision-making and prognosis.

Fifty-one CDKs in 40 patients were classified neonatally into 3 types: I, reducible (n=28); II, recalcitrant (n=16); and III, irreducible (n=7). Number of anterior skin grooves, range of motion (RoM), flexion deficit and reduction stability were recorded. Depending on reducibility, treatment comprised: physiotherapy with splints, traction with cast immobilization, or surgery. At follow-up, knees were assessed in terms of RoM and stability.

Mean age at first consultation was 5.6 days (range: 0–30). Mean age at follow-up was 9 years (range: 1–26). Physiotherapy with splinting achieved stable reduction in all type-I knees. Five type-II knees (31%) required traction, none of which needed surgery. Four type-III knees (57%) required surgery. Outcome was good or excellent in 82% of type-I knees, good in 68% of type II and poor in all type-III knees.

The study confirmed the relevance of the present neonatal classification to treatment, with increasing rates of surgical indication and decreasing rates of satisfactory outcome from types I to III. Therapeutic attitude can be graded according to severity of CDK.

IV, single-center retrospective series.