Location of anterior knee pain affects load tolerance in isometric single leg knee extension.

OBJECTIVES: To investigate relationships between load tolerance of single leg isometric knee extension and athlete reported knee pain location and severity during the single leg decline squat. DESIGN: Cross-sectional study. METHODS: 175 college basketball athletes (99 women, 76 men) in Alberta, Canada participated at the start of the 2018-19 season. Knee pain location (dichotomized into focal/diffuse pain), and severity (numerical rating scale 0-10) were collected during the single leg decline squat. Athletes completed a standardized single leg isometric knee extension to determine load tolerance (defined by pain or reduced form). A quantile regression model was used to examine the association between load tolerance and pain location adjusting for sex, years played, body mass index and team. RESULTS: Athletes with diffuse pain had a significantly lower median load tolerance (-0.89 kg) than athletes without pain (95% confidence interval [-1.49, -0.29]; p = 0.003). Athletes with focal pain tolerated similar median loads (-0.42 kg) to those without pain (95% confidence interval [-1.17, 0.33]; p = 0.26). Higher knee pain severity was associated with a non-linear but consistent reduction in load tolerance (p < 0.001). CONCLUSIONS: Athlete-reported knee pain location during the single leg decline squat influenced load tolerance to isometric knee extension. Athletes with focal pain tolerated similar isometric loads to their pain free teammates. Clinicians should consider load selection of isometric knee extension for athletes with diffuse pain given their lower load tolerance. Future research should consider reporting pain location in addition to pain severity to differentiate clinical presentations and response to exercise.

Prevalence and Pain Distribution of Anterior Knee Pain in Collegiate Basketball Players.

CONTEXT: Causes of anterior knee pain (AKP) in jumping athletes include patellofemoral pain and patellar tendinopathy. The differential diagnosis of AKP is challenging, with variations in clinical presentations. No previous research has used pain location to describe AKP in basketball players. OBJECTIVE: To (1) describe the prevalence and pain distribution of AKP in collegiate basketball players and (2) report the prevalence of focal inferior pole pain using 2 outcome measures. DESIGN: Cross-sectional study. SETTING: University and collegiate basketball facilities in Alberta, Canada. PATIENTS OR OTHER PARTICIPANTS: A total of 242 collegiate basketball athletes (138 women, 104 men). MAIN OUTCOME MEASURE(S): The single-legged decline squat test (SLDS) was used to capture pain location via pain mapping (dichotomized as focal or diffuse) and pain severity (numeric rating scale). The Oslo Sports Trauma Research Centre Knee questionnaire (OSTRC-Knee) and adapted version for patellar tendinopathy (OSTRC-Patellar Tendinopathy Questionnaire [OSTRC-P]) were used to report the prevalence of AKP and patellar tendinopathy, respectively. Focal inferior pole pain during the SLDS was used to classify patellar tendinopathy. RESULTS: Of the 242 players, 146 (60%) reported pain with the SLDS (unilateral = 64 [26%]; bilateral = 82 [34%]). A total of 101 (43%) described knee pain using the OSTRC-Knee. Pain mapping captured the variability in pain locations. Diffuse pain was more prevalent (left, 70%; right, 72%) than focal pain (left, 30%; right, 28%). Low prevalence of patellar tendinopathy was noted using the OSTRC-P (n = 21, 8.7%) and inferior pole pain during the SLDS (n = 25, 10.3%). CONCLUSIONS: Diffuse AKP was common in Canadian basketball players; however, pain mapped to the inferior pole of the patella was not common. Few players reported tendinopathy using the OSTRC-P, suggesting that patellar tendinopathy was not a primary knee pain presentation in this jumping cohort. Pain location, rather than the presence or severity of pain alone, may better describe the clinical presentation of AKP in jumping athletes.

Nearly 40% of adolescent athletes report anterior knee pain regardless of maturation status, age, sex or sport played.

OBJECTIVE: To report point prevalence of anterior knee pain (AKP) in adolescent athletes by (1) maturation status, (2) chronological age, (3) sex, and (4) primary sport. DESIGN: Cross-sectional. METHODS: Male and female participants aged 11-15 years were recruited from specialised sports programs for basketball, volleyball, Australian Rules Football and tennis. Standing height, sitting height, and body mass were measured and used to calculate maturity status. Past injury history, self-reported physical activity, and Victorian Institute of Sport Assessment Questionnaire Patellar Tendon (VISA-P) questionnaires were completed. Anterior knee pain was defined as any pain experienced on the anterior surface of the knee and recorded using a visual analogue scale (VAS). A single leg decline squat (SLDS) was performed for provocation of AKP. RESULTS: Two hundred and seventeen male and female adolescent athletes participated in this study. Twenty participants were excluded from data analysis. Point prevalence of AKP was 39% (N = 76). Average self-reported physical activity/week was 7.9 ± 4.1 h of their specialised sport and 2.0 ± 2.0 h of other physical activity/week. Maturation status, chronological age, sex nor primary sporting program was statistically significant in explaining the presence or absence of AKP. CONCLUSION: Due to the right-skewed maturation sample, the authors cannot state conclusively that maturation status was not associated with AKP. Nearly 40% of this cohort reported AKP during a pain provocation test. The presence of AKP was not explained by maturation status, age, sex or primary sport program. Given the chronic nature of AKP and future morbidity reported, this high prevalence provides rationale for intervention or prevention studies targeting younger athletes.

Explaining Variability in the Prevalence of Achilles Tendon Abnormalities: A Systematic Review With Meta-analysis of Imaging Studies in Asymptomatic Individuals.

OBJECTIVE: To estimate the prevalence of, and factors associated with, Achilles tendon abnormalities observed on imaging in asymptomatic individuals. DESIGN: Systematic review with stratified meta-analysis and meta-regression. LITERATURE SEARCH: Embase, Scopus, MEDLINE, CINAHL, SPORTDiscus, and Web of Science were searched from 1980 to August 2020. STUDY SELECTION CRITERIA: We included studies that reported the prevalence of Achilles tendon abnormalities, observed with any imaging modality, in an asymptomatic population. We excluded studies if participant mean age was younger than 12 years or if participants had current/previous lower-limb tendon injuries/symptoms or other systemic conditions. DATA SYNTHESIS: Random-effects proportion meta-analysis was used to estimate prevalence. We used meta-regression for continuous variables (mean age and body mass index [BMI], sample size, proportion of female participants) and stratified categorical variables (imaging modality and participation in physical activity) to explain between-study heterogeneity. RESULTS: We included 91 studies (10 156 limbs, 5841 participants). The prevalence of Achilles tendon abnormalities on imaging ranged from 0% to 80% per participant. Between-study heterogeneity was high (I2>90%, P<.001), precluding data pooling. Between-study heterogeneity was partly explained by participant mean BMI (slope, 2.8% per 1-unit increase in BMI; 95% confidence interval: 0.57%, 5.03%; P = .015) and participation in physical activity per limb, and mean age of 40 years old or older (P = .022) per participant. CONCLUSION: There was substantial variability in the prevalence of Achilles tendon abnormalities on imaging in asymptomatic individuals. Higher prevalence of abnormalities was associated with older age (40 years old or older), higher BMI, and participation in physical activity. A large proportion of heterogeneity remains unaccounted for, likely due to variations in abnormality definitions and study design. J Orthop Sports Phys Ther 2021;51(5):232-252. Epub 28 Mar 2021. doi:10.2519/jospt.2021.9970.

Physical Activity and Investigation With Magnetic Resonance Imaging Partly Explain Variability in the Prevalence of Patellar Tendon Abnormalities: A Systematic Review With Meta-analysis of Imaging Studies in Asymptomatic Individuals.

OBJECTIVE: To estimate the pooled prevalence of, and factors associated with, the presence of patellar tendon abnormalities observed on imaging in people without symptoms. DESIGN: Systematic review with stratified meta-analysis and meta-regression. LITERATURE SEARCH: We searched Embase, Scopus, MEDLINE, CINAHL, SPORTDiscus, and Web of Science from 1980 to August 2020. STUDY SELECTION CRITERIA: We included studies that reported the prevalence of asymptomatic patellar tendon abnormalities on imaging. We excluded studies of participants with current tendon pain, a history of tendon pain, or other systemic conditions. DATA SYNTHESIS: Stratification and meta-regression of studies based on study-level descriptive statistics (mean age, body mass index, proportion of female participants, physical activity participation, imaging modality) were performed using a random-effects model to account for between-study heterogeneity. Risk of bias was assessed using the modified Newcastle-Ottawa scale. RESULTS: Meta-analysis of 64 studies (7125 limbs from 4616 participants) found significant between-study heterogeneity (I2≥90%, P<.01), which precluded a summary prevalence estimate. Heterogeneity was partially explained by studies that included participants who were physically active and studies that assessed tendon abnormalities using magnetic resonance imaging compared to ultrasound (P<.05). Mean age, body mass index, proportion of female participants, and sample size did not explain the remaining heterogeneity. CONCLUSION: There was substantial variability in the reported prevalence of asymptomatic patellar tendon abnormalities. A clear and valid method is needed to assess and report the presence of patellar tendon abnormalities to increase research capacity and establish the clinical value of imaging the patellar tendon. J Orthop Sports Phys Ther 2021;51(5):216-231. Epub 28 Mar 2021. doi:10.2519/jospt.2021.10054.

Self-reported jumpers' knee is common in elite basketball athletes - But is it all patellar tendinopathy?

OBJECTIVES: To describe the prevalence and pain location of self-reported patellar tendinopathy and patellar tendon abnormality in a male elite basketball population. DESIGN: Cross-sectional. SETTING: Pre-season tournament. PARTICIPANTS: Sixty male athletes from the Australian National Basketball League. MAIN OUTCOME MEASURES: Self-reported patellar tendinopathy (PT) using the Oslo Sports Trauma Research Centre Overuse Questionnaire (OSTRC). Pain location using pain mapping (dichotomised: focal/diffuse) and severity during the single leg decline squat. Ultrasound tissue characterisation scans of both patellar tendons. RESULTS: Thirteen participants (22.7%) self-reported PT. Only 3 who reported PT had localised inferior pole pain. Thirty athletes reported pain during the decline squat, 15 described focal pain; 10 diffuse pain (5 missing data). Those with diffuse pain had greater years played [Md = 21 (13-24), n = 10 than focal pain (Md = 12 (7-26), n = 15), p = 0.042, r = 0.3]. Bilateral tendon abnormality was found in 45% of athletes and 15% had unilateral tendon abnormality. CONCLUSION: Elite male basketball athletes self-reporting PT had heterogeneity in pain location. When focal pain with loading was used as a primary definition of PT, 'jumpers' knee' was not common in this cohort. This study found that abnormality of the patellar tendon was common and did not correlate with symptoms.