Joint Noise Demystified: Does Knuckle Cracking Cause Arthritis? Insights from Strange Health

This episode of Strange Health investigates the sounds our joints make when they crack, popping, creaking, and clunking. Katie Edwards and Dan Bamgar speak with physiotherapist Clodagh Toomey to understand what causes these noises inside the joint, how they relate to hypermobility, and whether knuckle cracking is dangerous. The conversation debunks common myths, including the idea that cracking releases toxins or causes arthritis, and offers practical guidance on when to seek medical evaluation and how to keep joints healthy through movement.

Introduction and Key Questions

Joint noises are a common source of curiosity and anxiety. In this Strange Health episode, host Katie Edwards and Dr Dan Bamgar discuss why our joints crack, what those sounds might indicate, and whether routine cracking contributes to long-term joint disease. The program features physiotherapist and associate professor Clodagh Toomey, who explains the science behind joint sounds and helps separate myth from mechanism. The goal is to understand when noises are normal and when they signal something requiring care.

Inside the Joint: What Causes Noises

Joints are complex structures with cartilage, ligaments, a joint capsule, and synovial fluid. When a joint moves beyond its typical range, the surrounding membranes stretch and gas dissolved in the synovial fluid forms a bubble through a process called cavitation. The audible pop is the release of gases such as carbon dioxide, oxygen, and nitrogen. This gas bubble needs time to re-dissolve, which is why a joint often cannot be cracked again for about 20 minutes.

Different Noises, Different Meanings

Experts distinguish among cracking, popping, clunking, crepitus, and grinding. Knuckle cracking is usually harmless if there is no accompanying pain or swelling. Crepitus around the knee or other joints can occur from normal cartilage movement, and clunking can relate to tendon movement or alignment issues. Importantly, not all noises imply injury or arthritis, but persistent, painful, or swollen joints warrant evaluation.

Hypermobility and Risk

Some individuals have hypermobility, allowing a wider range of motion. While this can be endearing and beneficial in activities like dance, it can also increase the risk of joint misalignment or dislocation in extreme positions. The discussion highlights that lax connective tissues can produce more audible noises, but stability and function remain key measures of joint health.

What the Evidence Says about Arthritis

Regarding the claim that cracking causes arthritis, the evidence is not supportive. The program references studies that track joint crackers over time and do not show a higher incidence of osteoarthritis in habitual crackers. One famous self-experiment, where a physician cracked one hand for 50 years and not the other, did not demonstrate arthritis in either hand. While some studies note changes in grip strength or joint laxity, there is no consistent link between cracking and arthritis development.

Relief, Dopamine, and Psychological Effects

The noises can provide a sense of relief or tension release, possibly mediated by neural pathways and transient changes in muscle tension. Some people describe dopamine-like rewards from the audible crack, which may contribute to a habit. The relief is typically temporary, and ongoing cracking without addressing root joint problems may not yield lasting benefits.

Spinal Manipulation: Benefits and Risks

The episode acknowledges that spinal manipulation can relieve certain pains in the short term but carries risk, particularly involving neck structures and blood flow to the brain. Properly trained practitioners and careful patient selection are essential, and such therapies should be considered as part of a broader treatment plan addressing underlying issues rather than a universal fix.

Management and Prevention

The consensus is clear: regular movement and exercise support joint health, especially for cartilage nutrition. There is no strong evidence for specific supplements to reduce joint noise. A balanced approach includes stretching, strengthening, load management, and mindful activity. For some, strategies like mindfulness can complement physical approaches to tension and pain.

Bottom Line

Most joint cracking is normal and not a predictor of arthritis. Noisy joints should not automatically cause alarm, but red flags such as persistent pain, swelling, instability, or reduced function warrant medical evaluation. The overarching message is to prioritize movement and strength, rather than chasing dramatic crack sounds, for long-term joint health.