Which Tests Predict 6-Month Isokinetic Quadriceps Strength After ACL Reconstruction? An Examination of Isometric Quadriceps Strength and Functional Tests at 3 Months.
Nicholas Giampetruzzi, Adam P Weaver, Dylan P Roman and 2 others
PMID 38050543WHAT IT FOUND
Three-month isometric quadriceps strength predicted 36.6% of six-month isokinetic strength in adolescents after ACL reconstruction.
The Y-Balance Test and step-down test were poor predictors. Clinicians should not rely on these functional tests as proxies for isolated quadriceps strength.
Key findings
01Three-month isometric quadriceps peak torque significantly predicted six-month isokinetic quadriceps peak torque, accounting for 36.6% of the variance.
02The Y-Balance Test anterior reach was significantly correlated with six-month strength but added only 1.9% of predictive variance in the regression model.
03The anterior step-down test and other Y-Balance Test directions showed no significant correlation with six-month isokinetic quadriceps strength.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study had a small sample size of 36 patients. The retrospective design limits the ability to control for confounding variables such as activity level or adherence to rehabilitation protocols. Isometric testing was performed at 60 degrees of knee flexion using an isokinetic dynamometer, which may differ from the 90-degree angle often used with handheld dynamometers in clinical practice. The anterior step-down test used a fixed 12-inch box height, which did not standardize knee flexion angles across patients of different limb lengths. Findings are limited to adolescents with hamstring autografts and may not generalize to other graft types or adult populations.
The easy way to misread this
Do not interpret the significant correlation between Y-Balance anterior reach and later strength as evidence that the Y-Balance test is a useful screening tool for quadriceps strength. The test added only 1.9% of predictive value in the regression model, indicating it is a weak predictor compared to direct strength measures.