Maximal Lower Limb Strength in Patellar Tendinopathy A Systematic Review With Meta-Analysis

Objective: To investigate whether lower limb strength is reduced in people with patellar tendinopathy (PT) compared with asymptomatic control individuals or the asymptomatic contralateral limb. Data Sources: MEDLINE, PubMed, Scopus, and Web of Science. Study Selection: To be included in the systematic review and meta -analysis, studies were required to be peer reviewed, published in the English language, and case control investigations; include participants with a clinical diagnosis of PT and an asymptomatic control or contralateral limb group; and include an objective measure of lower limb maximal strength. Data Extraction: We extracted descriptive statistics for maximal strength for the symptomatic and asymptomatic limbs of individuals with PT and the limb(s) of the asymptomatic control group, inferential statistics for between -groups differences, participant characteristics, and details of the strength -testing protocol. The risk of bias was assessed using the Joanna Briggs Institute critical appraisal tool for analytical cross-sectional studies. Data Synthesis: Of the 23 included studies, 21 reported knee strength, 3 reported hip strength, and 1 reported ankle strength. Random -effects models (Hedges g ) were used to calculate the pooled effect sizes (ESs) of muscle strength according to the direction of joint movement and type of contraction. The pooled ESs (95% CI) for maximal voluntary isometric contraction kneeextension strength, concentric knee -extension strength, and concentric knee -flexion strength were 0.54 (0.27, 0.80), 0.78 (0.30, 1.33), and 0.41 (0.04, 0.78), respectively, with all favoring greater strength in the asymptomatic control group. Researchers of 2 studies described maximal eccentric knee -extensor strength with no differences between the PT and asymptomatic control groups. In 3 studies, researchers measured maximal hip strength (abduction, extension, and external rotation), and all within -study ESs favored greater strength in the asymptomatic control group. Conclusions: Isometric and concentric knee -extensor strength are reduced in people with PT compared with asymptomatic control individuals. In contrast, evidence for reduced eccentric kneeextension strength in people with PT compared with asymptomatic control individuals is limited and inconsistent. Although evidence is emerging that both knee -flexion and hip strength may be reduced in people with PT, more examination is needed to confirm this observation.