Can wedge osteotomy correct depression of the lateral tibial plateau mimicking posterolateral rotatory knee instability?

Abstract

Background: The literature suggests rotatory knee instability (pseudolaxity) can be associated with depressions of the lateral tibial plateau in patients despite an intact arcuate ligament complex. Correcting this bone deformity by an open-wedge osteotomy of the lateral tibia plateau, elevating the depressed bone may restore knee stability.

Questions/purposes: We therefore asked whether: (1) knee stability is restored after this procedure; (2) Lysholm functional scores improve after this treatment; and (3) the limb alignment changes.

Patients and methods: We retrospectively evaluated 12 patients who underwent a subchondral open-wedge osteotomy of the lateral tibial plateau combined with a knee arthroscopic procedure for the treatment of a knee rotational instability secondary to a lateral compartment bone deficit between 2000 and 2007. Eleven patients with a mean age of 35 years were available for followup at a minimum of 2 years (average, 5.4 years; range, 2-9 years). Preoperatively and at last followup, patients were clinically and radiographically evaluated by the Lysholm score and with comparative knee radiographs. Complications were recorded.

Results: At last followup all patients rated their knees as stable. All osteotomies healed uneventfully. The Lysholm score improved from 62 to 87. Followup radiographs showed no changes in the femorotibial axis as result of the osteotomy.

Conclusions: Patients with chronic depression of the posterolateral tibial plateau may exhibit symptoms of posterolateral knee instability, a sort of pseudolaxity. In these patients, an open-wedge osteotomy of the lateral tibia plateau, elevating the depressed bone, and tensioning posterolateral structures improves this secondary posterolateral knee instability.

Level of evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Fig. 1A–D

(A) AP and (B) lateral radiographic view of Patient 1 showing chronic depression of the lateral tibial plateau (white and black arrows). (C) Coronal and (D) sagittal MRI view of the same patient. Note the absence of meniscal contact with the tibial articular surface at the lateral compartment.

Fig. 2

Arthroscopic view of the lateral compartment with a positive “floating meniscus” sign showing an abnormal increased distance between the lateral meniscus and the tibial plateau resulting from the chronic depression by the bony structure.

Fig. 3A–B

Schematic drawing of the knee in flexion with a chronic bone depression of the lateral compartment and the resulting pseudolaxity of the posterolateral complex (A) that is tensed after performing the osteotomy (B).

Fig. 4A–B

(A) Intraoperative picture of the opening wedge osteotomy with the structural allograft in place. (B) Postoperative radiograph at 2 years followup.