Trochlear Contact Pressures after Straight Anteriorization of the Tibial Tuberosity

Abstract

Background:

Anteromedialization of the tibial tuberosity has been shown to decrease mean total contact pressures of the lateral trochlea and to shift contact pressures to the medial trochlea.

Hypothesis:

Modifying the anteromedialization osteotomy to a straight anteriorization osteotomy of the tibial tuberosity can decrease trochlear contact pressures without a resultant medial shift of forces to the medial trochlear contact area.

Study Design:

Controlled laboratory study.

Methods:

Ten cadavers were tested before and after straight anteriorization tibial tuberosity osteotomy by loading the extensor mechanism with 89.1 and 178.2 N at 0°, 30°, 60°, and 90° of flexion following a validated patellofemoral joint loading protocol. Contact pressures were measured with electroresistive pressure sensors placed directly on the trochlea.

Results:

The mean trochlear contact pressures after osteotomy decreased significantly (P < .05) for loads of 89.1 and 178.2 N at both 30° (23% and 20%, respectively) and 60° (18.7% and 31.9%, respectively) of knee flexion. The peak contact pressures decreased significantly (P < .05) for loads of 89.1 and 178.2 N at 30° (24.3% and 27.0%, respectively) and 60° (31.9% and 24.5%, respectively) and for loads of 89.1 N at 90° (13.4%) of knee flexion.

Conclusion:

The authors demonstrated significantly decreased trochlear contact forces after straight anteriorization osteotomy of the tibial tuberosity, without a significant resultant medial shift of the center of force.

Clinical Relevance:

Straight anteriorization of the tibial tuberosity may be a useful adjunct for patients with medial articular defects of the patellar or trochlea in whom anteromedialization would be otherwise contraindicated.