Positive pivot shift after ACL reconstruction predicts later osteoarthrosis: 63 patients followed 5-9 years after surgery.

BACKGROUND: Rupture of the anterior cruciate ligament (ACL) may cause osteoarthrosis (OA) and functional impairment. We wanted to find out whether the degree of knee stability obtained after ACL reconstruction correlates with radiographic and clinical outcome. PATIENTS AND METHODS: We examined 63 patients 2 and 5-9 years after anterior cruciate ligament (ACL) reconstruction. Knee stability was assessed 2 years after surgery by recording AP laxity using radiostereometric technique (RSA) and by performing the pivot shift test. Degeneration of the knee joint was evaluated with bone scintigraphy, and radiographically. Functional outcome was assessed with Lysholm score, Tegner activity scale and with the one-leg hop test.
RESULTS: Radiographic signs of osteoarthrosis at the most recent follow-up (5-9 years) did not correlate with knee stability. Patients with positive pivot shift test 2 years after surgery showed increased scintigraphic activity of the subchondral bone at the most recent follow-up, and inferior subjective functional outcome 2 years after surgery. Knees having had meniscus resections had more often OA. Radiographical signs of OA were associated with higher scintigraphic uptake in the operated knee relative to the contralateral knee.
INTERPRETATION: The ability to obliterate the pivoting by ACL reconstruction appears to be more important than normalizing the AP laxity in order to prevent later OA.