A spectrum of anterolateral rotatory laxity exists in anterior cruciate ligament (ACL) injured knees. Understanding of the factors contributing to a high-grade pivot shift continues to be refined. The effect of a high-grade pivot shift on baseline patient reported outcome measures (PROMs) is unclear.
To investigate factors associated with a high-grade pre-operative pivot shift and to evaluate the relationship between a high-grade pivot shift and baseline PROMs.
A post hoc analysis of 618 ACL deficient patients deemed high risk for re-injury enrolled in a randomised trial was performed. A binary logistic regression model was developed with a high-grade pivot shift (International Knee Documentation Committee [IKDC] Grade 3) as the dependent variable. Age, sex, Beighton score, chronicity, posterior third medial or lateral meniscus injury and tibial slope were selected as independent variables. The importance of knee hyperextension as a component of the Beighton score was assessed using receiver operator characteristic curves. Baseline PROMs were compared between patients with and without a high-grade pivot.
Six factors were associated with a high-grade pivot shift. These were Beighton score (each additional point, OR 1.17, 95%CI 1.06–1.30, p=0.002), male sex (OR 2.30, 95%CI 1.28–4.13, p=0.005), the presence of a posterior third medial (OR 2.55, 95%CI 1.11–5.84, p=0.03) or lateral meniscal injury (OR 1.76, 95%CI 1.01–3.08, p=0.05), tibial slope >9° (OR 2.35, 95%CI 1.09–5.07, p=0.03) and chronicity >6 months (OR 1.70, 95%CI 1.00–2.88, p=0.05). The presence of knee hyperextension improved the diagnostic utility of Beighton score as a predictor of a high-grade pivot shift. There was an interaction between tibial slope and posterior third medial meniscus pathology; tibial slope <9 degrees was only associated with a high-grade pivot in the presence of posterior third medial meniscus injury. Patients with a high-grade pivot shift had higher baseline 4-Item Pain Intensity Measure (P4) pain scores (11 ?13 vs. 8 ?14, p=0.04); however, there was no difference between baseline IKDC, ACL-Quality of life (ACL-QOL), Knee Injury and Osteoarthritis Outcome Score (KOOS) or KOOS sub-scales.
Ligamentous laxity, male sex, posterior third medial or lateral meniscal injury, increased posterior tibial slope and chronicity are associated with a high-grade pivot shift in this population deemed high risk for repeat ACL injury. Knee hyperextension improves the prognostic utility of the Beighton score. The effect of tibial slope may be accentuated by the presence of meniscal injury, supporting the need for meniscal preservation. Baseline PROMs are similar between patients with and without a high-grade pivot shift.