[Rotatory instability of the knee joint in cases of previously treated "Unhappy Triad" (author's transl)].

The combined injury of the ligaments and capsular structures of the knee joint always causes rotatory instability as the sum of all or some a.m. injuries (Slocum; Nicholas). This has to be taken into account in the operative treatment. We have followed 14 patients with old "unhappy triad" injuries who had been operated upon with the question in mind whether the usual procedures with reefing of the ligaments or plastic replacements including meniscectomies, but without paying attention to the lax posterior capsule could correct the typical anteromedial rotatory instability. The results showed that this was true only in about half the cases. The remaining patients continued to complain about instability in the operated knee joint. Objectively, the pre-operatively positive rotatory drawer sign remained unchanged. Therefore we conclude that the anteromedial rotatory instability of the knee joint can be improved by the procedure devised by Slocum and Nicholas.