Abstract
Congenital or acquired recurvatum genu might be caused by bone and/or soft tissue disorders. In bone recurvation, tibial deformity is more common; femoral deformity has clinical and X-ray features that are less important and often unidentified. We found this type of deformity in only four of 40 cases of bone recurvation.
Bone recurvation can follow a tibial or femoral fracture as well as injury with no X-ray signs. Some months later an anterior epiphysiolisis might be recognised on X-ray. This fact allows a retrospective diagnosis of fifth type Salter-Harris epiphysiolisis. Clinically a harmonious recurvatum genu would be recognised, which is difficult to distinguish from a capsulo-ligamentous disorder.
According to a subjective profile, it is featured with no objective laxity. On X-rays there are no peculiarities in the anterior view, but on the lateral view femoral condylar flattening with anterior rotation, in particular in the lateral one, can be observed. It might be useful to compare the X-ray findings to define a geometrical point termed the femoral diaphysealintercondylar angle. This has been already described and is measured between two lines, one which represents the axes of the femoral shaft, the other one the Blumensaat line; in a normal knee this angle measures 33° (±3). In knees with femoral recurvation this is higher: in our four patients the range of the angle was 45°–58°.
Procurving femoral osteotomy is the gold standard; in fact femoral closed wedge osteotomy allows a complete correction. Surgeons must avoid an overcorrection with subsequent femoral trochlear rotation and at the same time a tibial osteotomy must be avoided, which would lead to a double articular deformity, wherever it would fit with a capsulo-ligamentous recurvation.
