Noisy knees - knee crepitus prevalence and association with structural pathology: a systematic review and meta-analysis

Objective: Knee crepitus, the audible crackling or grinding noise during knee movement, can be experienced across the lifespan and create concern for underlying pathology. Our systematic review aims to provide a summary estimate of knee crepitus prevalence and its association with structural pathology among the general population and across knee conditions. Design: Systematic review and meta-analysis. Data sources: Medline, Embase, CENTRAL, Web of Science, SPORTDiscus and CINAHL. Eligibility criteria: Studies evaluating knee crepitus prevalence. Results: 103 studies involving 36 439 participants (42 816 knees) were included. Based on very low certainty evidence, the pooled prevalence of knee crepitus in the general population was 41% (7609 knees; 95% CI 36% to 45%; I2=92.6%); in pain-free persons 36% (852 knees; 95% CI 23% to 50%; I2=91.9%), and in those with osteoarthritis (OA) 81% (18 821 knees; 95% CI 75% to 87%; I2=97.9%). Across other musculoskeletal knee conditions, the pooled prevalence of knee crepitus ranged from 35% (ligament injury; 2740 knees; 95% CI 27% to 44%; I2=95.6%) to 61% (cartilage pathology; 1445 knees; 95% CI 40% to 81%; I2=98.2%). There was low to very low certainty evidence of an association between knee crepitus and radiographic OA (OR 3.79, 95% CI 1.99 to 7.24; 1725 knees; I2=53.0%) and several OA-related features on magnetic resonance imaging (MRI). Conclusion: In this review, knee crepitus was prevalent in the general population, pain-free persons, those with knee OA and other musculoskeletal knee conditions. Knee crepitus was associated with a more than threefold increased odds of radiographic OA diagnosis and several OA-related MRI features. The low to very low certainty of evidence informing our aggregated prevalence estimates and association outcomes suggest that results should be interpreted with caution.