Correlation of clinical tests and patient-reported measures in adolescents with Osgood Schlatter: a cross-sectional study

Background
A common knee complaint during adolescence is Osgood Schlatter (OS). As research into OS is only just emerging, little is known on how findings from clinical tests correlates with self-reported measures.

Purpose / Aim of Study
To capture how clinical tests correlates with self-reported factors in OS patients.

Materials and Methods
Adolescent OS patients from a specialized orthopedic clinic completed patient-reported surveys within 6 domains (dependent outcome variables) on pain (maximal numerical pain rating past week and past 24 hours, KOOS child ‘pain’, EQ-D5-Y-4), mental health (EQ-D5-Y-5), kinesiophobia (Tampa Scale), quality of life (KOOS child ‘QoL’), sports function (KOOS child ‘sport/rec’), self-rated health (EQ-D5-Y-VAS), and underwent a test battery of knee function containing 5 tests (independent predictor variables). For continuous variables correlations were computed using Pearsons r, and Spearmans rank for non-continuous variables.

Findings / Results
Thirty-three patients (age 13.5±1.7 years, symptom-duration 23.6±16.1 months) participated. Lower normalized isometric knee extension strength (Nm/kg) correlated with self-reported pain (past 24 hours, r=0.595; EQ-D5-Y-4, r=0.509), and satisfaction with sport participation level (r=0.430). Decreased pressure-pain threshold at the tibial tubercle correlated with other pain measures, and level of kinesiophobia (r=0.447). Higher pain evoked from the Anterior Knee Pain Provocation Test correlated with other pain measures, problems with sports participation (r=0.548), and QoL (r=0.396). Pain during maximal isometric knee extension correlated with other pain measures, problems with sports participation (r=0.600), mental health (r=0.411), and QoL (r=0.593). Knee extensor flexibility was not associated with any self-reported measures (p>0.05). No tests were associated with self-rated health (p>0.05).

Conclusions
There is moderate to strong correlation between clinical test results and self-reported measures of pain, mental health, QoL, sports function, and self-rated health. This can help clinicians to more easily gauge an understanding of potentially affected self-reported factors, based of a few clinical measures.