Abstract
Unstable knee caused by an axial deformity mainly occurs in serious valgus cases, which is the result of a femoral external hypoplastic condylus defect and often seen in association with marked debris of the tibial plate and bone –loss. Tibial rotation related to the deficit causes lateral patellar subluxation, and soft tissue retraction fixes the deformity while the preconditions for an anteromedial ligamentous laxity are being created. On replacement the deformities develop because of bone-stock defects as well as ligamentous defects, which are often secondary to debris and/or to primary component misrotations.
In primary surgery the approach is medial for varus and lateral for valgus, in order to help the release. We use the GAP technique to implant semibonded prostheses. In revisions the previous approach is always followed. From 2000 to 2003 52 LCCK Zimmer were implanted. Tuberosity detachment was required in 20 cases.
The increase in TKS was significant.: from 40 to 180. The radiographic alignment supported by taproots centrage is excellent, and there are no signs of radiographical mobilisation in any of the cases.
There were two cases of intolerance, with decubitus of a screw utilised for the tibial tuberosity synthesis. A flexion-extension defect had to be repaired afterwards by surgery and two cases of endostal reaction to the tibial taproot were observed.
Despite the difficulty of treated cases, results appear promising; the combination between prosthesis type and GAP technique confers high stability to the system.
