Lower limb strength in patellar tendinopathy - A systematic review with meta-analysis

This review aimed to investigate whether lower limb strength is reduced in people with patellar tendinopathy (PT) compared to asymptomatic controls.

This study was a systematic review and meta-analysis of peer-reviewed, English language case-control studies. MEDLINE, PubMed, Scopus, and Web of Science were searched to identify all English-language studies published prior to the 26^th of October 2022. Eligible studies included participants with a clinical diagnosis of PT, and asymptomatic controls, who had an objective measure of lower limb maximal strength. Random-effects models (Hedges' g) were used to calculate the pooled effect size (ES) of muscle strength according to the direction of joint movement and type of contraction.

Twenty-three studies were included. Twenty studies reported knee strength, three reported hip strength, and one reported ankle strength. The pooled ESs (95%CI) for maximal voluntary isometric knee extension 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), all favoring greater strength in the asymptomatic control group. Two studies reported maximal eccentric knee extensor strength with no differences between PT and asymptomatic controls. Three studies reported maximal hip strength (abduction, extension, and external rotation) and all within-study ESs favored greater strength in the asymptomatic control group.

Isometric and concentric knee extensor strength is reduced in people with PT compared to asymptomatic controls. In contrast there is limited and inconsistent evidence for reduced knee extension eccentric strength in PT, compared with asymptomatic controls. While there is emerging evidence that both knee flexion strength and hip strength may be reduced in PT more research is needed to confirm this observation.