Validity and reliability of hand-held dynamometers in hip, knee, and ankle strength testing in healthy adults: A systematic review and meta-analysis.

Background: Accurate assessment of muscle strength is crucial for clinical practice. While traditional methods like manual muscle testing (MMT) are accessible, isokinetic dynamometry (ID) is the gold standard due to its reliability, although it is expensive, space-consuming, and requires extensive training. Hand-held dynamometers (HHDs) have demonstrated a strong correlation with ID values, suggesting good to excellent validity. However, factors such as muscle group, evaluator proficiency, and protocol standardization can influence hand-held dynamometer (HHD) measurements. Objectives: This systematic review aimed to evaluate the inter- and intra-rater reliability and validity of HHDs for lower extremity strength assessment in healthy adults and to identify common test protocols. Methods: A comprehensive electronic search was conducted in six databases (PubMed, Medline and CINAHL via Ebsco host, ISI Web of Science, ProQuest, and Science Direct) from January 2017 to May 2023. Studies were included if they assessed asymptomatic participants using HHDs for isometric or concentric contractions of the hip, knee, or ankle and focused on psychometric properties. The QAREL and QUADAS-2 checklists were used to assess reliability and validity, respectively. To complement these 2 checklists, GRADE was used to determine the certainty of evidence. A meta-analysis was conducted to quantify the pooled reliability and validity of HHDs. Results: Eighteen studies were included. Sixteen investigated HHD reliability, with eight being solely reliability studies. Reliability was operationalized through the intraclass correlation coefficient (ICC). Eight studies received high QAREL scores, indicating strong methodological quality. The remaining studies received low QAREL scores, suggesting methodological weaknesses. These reliability studies revealed moderate to very high correlations for inter-rater and intra-rater reliability, indicating HHDs can be a dependable tool for evaluating lower limb muscle strength. Ten studies investigated the validity of HHD for measuring muscle strength in the lower limbs. Pearson correlation coefficients showed moderate to perfect positive correlations between HHD and ID measurements, suggesting alignment. Four studies provided data for meta-analysis. The pooled estimate for internal consistency for all hip and knee movement strength assessments across studies was high to very high, indicating minimal measurement error and reliable measurements. Conclusion: HHDs are reliable and valid for assessing lower extremity muscle strength in healthy adults. Their ease of use, affordability, and portability make them a valuable asset for clinical practice. This research was funded by DOST-SEI. The systematic review is registered in PROSPERO (CRD42023399215).