Association Between Patellar Tendon Abnormality and Land-Jump Biomechanics in Male Collegiate Basketball Players During the Preseason

Abstract

Background: Patellar tendinopathy is a degenerative condition that predominantly affects jumping athletes. Symptoms may be subtle or nonexistent at preseason, but structural abnormalities may be present. Assessing patellar tendon abnormality (PTA) through magnetic resonance imaging (MRI) and ultrasound (US) and classifying symptoms using the Victorian Institute for Sport Assessment-Patellar tendon (VISA-P) may provide useful insights if combined with biomechanics measurements.

Purpose: To (1) assess whether land-jump biomechanical patterns are associated with clinically pertinent PTA as seen on imaging and through VISA-P scores and (2) model the contributing risk and accuracy of biomechanics to classify PTA and symptomatic observations.

Study design: Cross-sectional study; Level of evidence, 3.

Methods: A total of 26 National Collegiate Athletic Association Division I and II male basketball players (n = 52 limbs) were recruited during the preseason. We collected VISA-P scores, bilateral PTA through US and MRI morphology measurements, and bilateral 3-dimensional lower extremity kinematics and kinetics measurements from a land-jump test from an 18-inch-high (45.7-cm-high) box. Statistically, each limb was treated independently. The association of biomechanics with PTA and symptoms (VISA-P score <80) was tested with multivariate models and post hoc tests. Logistic regression modeled relative risk and accuracy of biomechanical variables to classify PTA and symptomatic limbs.

Results: There were 19 to 24 limbs with PTA depending on US and MRI measurements. Differences in hip and knee kinematic strategies and ground-reaction loads were associated with PTA and symptomatic limbs. Peak landing vertical ground-reaction force was significantly decreased (169 ± 26 vs 195 ± 29 %body weight; P = .001), and maximum hip flexion velocity was significantly increased (416 ± 74 vs 343 ± 94 deg/s; P = .005) in limbs with versus without PTA on imaging. Knee flexion at the initial contact was decreased in symptomatic versus healthy limbs (17°± 5° vs 21°± 5°, respectively; P = .045). Regression models classified PTA limbs and symptomatic limbs with 71.2% to 86.5% accuracy. Hip and knee maximum flexion velocity and vertical ground-reaction force variables were most common across models observing clinically pertinent PTA.

Conclusion: Our findings suggested that functional kinematic and kinetic biomechanical strategies at the hip and knee were associated with PTA, identified on imaging, and symptomatic limbs.

Keywords: basketball; biomechanics; land-jump; magnetic resonance imaging; patellar tendinopathy; ultrasound.

Figure 1.

(A) Illustration of a patient in the supine position for the MRI and US measurements. (B) Sagittal MRI images of knees representing each morphology (grades 0-3) in the proximal tendon region. (C) US images of knees representing each morphology (grade 0-3) in the proximal tendon region. Red and white arrows indicate areas of patellar tendon degeneration. The tendon is inside the areas outlined by red dashes. (D) Illustration of the knee joint showing major structures and proximal and distal regions of the patellar tendon. DIST, distal; MID, medial; MRI, magnetic resonance imaging; PROX, proximal; US, ultrasound.

Figure 2.

Physical dimensions and arrangement of the land-jump test. (A) Illustration of the dynamic land-jump task at initial contact, midlanding, and final contact, with platform and force plate objects drawn to scale. The platform h was 18 inches (45.7 cm). The red arrow depicts a ground-reaction force vector. (B) A diagram from a top-down perspective of the physical arrangement for the wooden box, force plates, and staging platform; the foot placement depicted as dashed lines is approximate. (C) A frame from the 3-dimensional motion reconstruction program (Visual3D, Version 6; C-Motion) showing the virtual world and rigid-body model near the ML event along with blue ground-reaction force vector arrows. Note: the 2 adjacent force platforms in the immediate background were not used. IC, initial contact; ML, midlanding; FC, final contact; h, height.

Figure 3.

Details of intersecting 95th percentile regression model variables. (A) A stacked bar chart shows the individual and cumulative count of biomechanical variables per PTA outcome. (B) List of the top 10 cumulative variables and corresponding mean odds ratios per PTA outcome. The odds ratios were evaluated in each model with 2 other variables present. The VISA-P outcome was not shown because all regression models contained a single variable. See Table 1 for units of measure associated with the biomechanical variables. DIST, distal patellar tendon region; IC, initial contact; IP-VGRF, initial peak vertical ground-reaction force; MRI, magnetic resonance imaging; PROX, proximal patellar tendon region; PTA, patellar tendon abnormality; US, ultrasound; VGRF, vertical ground-reaction force; VISA-P, Victorian Institute for Sport Assessment–Patellar tendon; dashes indicate no data.