Abstract
Objectives:
Patellar tendinopathy is prevalent in elite jumping athletes, with a particularly high risk in basketball players. Previous prospective research has demonstrated that ultrasound (US) findings, primarily the presence of hypoechoic regions within the tendon, are prevalent in both symptomatic and asymptomatic elite jumping athletes and thus do not necessarily indicate patellar tendon pathology.
Other studies have suggested that hypoechoic regions within asymptomatic tendons are predictive of new onset symptomatic patellar tendinopathy. None of these previous studies evaluated the utility of patellar tendon thickness as a predictive measure. The purpose of this study is to build on the previous literature to identify whether preseason US is a clinically relevant preseason screening tool in elite basketball players. We hypothesized that increased preseason anteroposterior (AP) thickness of the proximal patellar tendon, as well as hypoechoic regions, are predictive of symptomatic patellar tendinopathy and associated sequelae.
Methods:
Thirty-one male National Collegiate Athletic Association (NCAA) Division I basketball players voluntarily participated in this prospective cohort study. Both patellar tendons of each athlete were evaluated at preseason, midseason, and postseason time points, resulting in a total of 52 patellar tendons from 27 athletes included in this analysis after exclusion of 4 tendons that were previously operated on and 6 tendons from 3 athletes who transferred to a new team during the season.
Basic demographic data were collected for each athlete. At each time point, Victorian Institute of Sports Assessment – Patellar Tendon (VISA-P) scores, patellar tendon AP thickness, and presence of proximal patellar tendon hypoechoic regions were evaluated. Outcome measures included 1) proximal patellar tendon hypoechoic region, 2) trip to the training room (TTR), 3) time-loss symptomatic patellar tendinopathy (TLPT), and 4) patellar tendon rupture. TTR was defined as symptomatic patellar tendinopathy causing the athlete to seek evaluation by team medical staff. TLPT was a binary outcome that involved 1 or more missed game due to patellar tendinopathy symptoms.
Measurement of patellar tendon AP thickness was performed using the Butterfly iQ portable US probe (Butterfly Network, Inc., Burlington, MA) and accompanying iPhone mobile application (Apple, Cupertino, CA) (Figure 1). Two distinct images were saved for each patellar tendon at each time point. Each of these images were independently evaluated by two reviewers, one of which was a fellowship- trained musculoskeletal radiologist. Intra- and interrater reliability was calculated. Covariates evaluated in multivariate regression model included age and body mass index (BMI). Significance was set to p<.05.
Results:
Of the total of 52 tendons (mean age 20.67 ± 1.22 years, mean BMI 24.1 ± 1.57), the mean preseason AP thickness was 4.78 ± 1.22 mm. Intra- and interrater reliability for AP thickness were both excellent (ICC=0.99, p<.01 and ICC=0.98, p<.01, respectively). Compared to preseason values, there was a significant increase in mean AP thickness at both midseason (p<.01) and postseason (p<.01) evaluation (Table 1, Figure 2). VISA-P scores decreased from preseason to midseason (p=.04), but increased from midseason to postseason (p=.03) (Table 1).
A total of 9 patellar tendons resulted in a TTR (17.31%) (Table 2). Preseason AP thickness was associated with an increased odds of TTR (aOR=7.58 [2.09, 29.66], p<.01). Assuming mean age and BMI, an 8mm tendon at baseline predicted a 97.19% probability of a TTR during the season, while a 4mm tendon predicted a 0.90% probability. Of the 9 tendons that demonstrated preseason hypoechoic regions, 5 (55.56%) resulted in a TTR (aOR=12.60, p<.01). Preseason VISA-P scores (p=.36) were not predictive of TTR.
There were 4 cases of TLPT (7.69%) (Table 2). There was a significant association between preseason AP thickness and increased odds of TLPT (aOR=1.61 [1.02, 2.54], p=.04). Assuming mean age and BMI, an 8mm tendon at baseline demonstrated a 24.83% probability of resulting in TLPT, while a 4mm tendon demonstrated a 4.26% probability. Preseason VISA-P scores (p=.39) were not predictive of TLPT.
Conclusions:
This is the first analysis evaluating patellar tendon thickness and patellar tendon sequelae in elite basketball players at more than two time points. This study demonstrated the ability for preseason US screening to identify symptomatic patellar tendinopathy and associated sequelae during the season. Additionally, there was a significant increase in mean AP thickness from preseason to midseason as well as from midseason to postseason. This is in contrast to VISA-P scores, which initially increased, but then decreased to preseason levels at postseason evaluation. Patellar tendon AP thickness may thus serve as a more stable and precise measure of patellar tendinopathy severity when compared to VISA-P scores. Further research with increased sample size may establish US as a clinically relevant screening tool in elite jumping athletes.
