[Spontaneous course of femorotibial osteoarthritis]

Medial femorotibial osteoarthritis (MFTO) is characterised by progressive deterioration resulting, in 6 out of 10 cases, in an inability to walk after 10 to 15 years. At the surgical stage, AP films show subchondral bone wear on the edge of the medial tibial plateau with lateral tibial dislocation and lateral films show obliqueness of the medial tibial plateau possibly exceeding 10 degrees and accompanied by anterior subluxation of the tibial or even rupture of the anterior cruciate ligament. Lateral femorotibial osteoarthritis (LFTO), more frequent in women, occurs an average of 7 years later than MFTO, at an average age of 70 years. Instability is often severe. 72% of cases develop clinical valgus deformity of 10 degrees to 20 degrees after an average of 13 years. Recurvatum is also possible. The combination of femoropatellar osteoarthritis, generally lateral, is observed in 23 to 41% of cases, depending on the author, while osteoarthritis of the hip is observed in 10% of cases and chondrocalcinosis is present in 20% of cases. These figures must be interpreted in relation to the usual ageing of the subjects.