Noises, clicks, and joint popping are very common in children and adolescents. If the joint is not painful, does not swell, and functions normally, an isolated noise often has little clinical significance. A hip click in a newborn or young infant is a separate issue: tell the child's doctor so it can be considered as part of hip screening.
Where the popping comes from
There isn't a single mechanism.
When fingers are voluntarily cracked, the most studied phenomenon is the rapid formation of a gas cavity in the synovial fluid during the separation of joint surfaces, known as tribonucleation. Some details about the exact mechanism of the sound remain debated. [1]
In other joints, the noise can result from the gliding of a tendon or a capsulo-ligamentous structure over a bony prominence. This can be more evident in very flexible or hypermobile children.
Does cracking knuckles cause arthritis?
Available studies in adults have not found an association between habitual knuckle cracking and hand osteoarthritis. These are mainly observational findings: reassuring for that specific question, but not long-term evidence about every joint in children. [1,3]
However, a movement that causes pain should not be repeatedly forced.
Knee noises
The knee can make noise during squats, climbing stairs, running, or after sitting for a while. Without pain, swelling, giving way, or locking, isolated crepitus is often benign.
A painful click or one associated with locking and swelling, however, warrants evaluation. Symptomatic discoid meniscus, patellofemoral problems, and osteochondral lesions can produce clicks, but the diagnosis depends on the overall symptoms and clinical examination.
Hip click in newborns and young infants
A small click is not equivalent to the 'clunk' that a doctor may detect in an unstable hip. However, parents cannot reliably make that distinction from the sound at home and should not repeat hip examination manoeuvres themselves.
Studies of infants referred for an isolated click have produced differing results. A 2017 study was reassuring, whereas a prospective study in 2023 also found ultrasound abnormalities in infants without other known risk factors. These were selected groups referred to specialist centres: their results do not give the probability of dysplasia for every infant whose parent hears a click. [2,4]
Tell the child's doctor, who can consider the hip examination, risk factors and screening pathway. The sound alone can neither diagnose nor rule out hip dysplasia. [2,4]
When to get it checked
It is appropriate to investigate further if the popping is associated with persistent pain, swelling, warmth, limping, reduced activity, joint locking, loss of movement, a painful click always in the same spot, significant recent trauma, or fever with joint pain.
Fever with a swollen or very painful joint, refusal to bear weight or a child who appears unwell needs urgent assessment rather than a routine appointment. Septic arthritis is an emergency; joint sounds should not distract from these warning signs. RCH guidance
In an older child who runs, jumps and uses the joint normally, without the warning signs above, no specific tests, supplements or exercises are needed just to eliminate a painless noise. This reassurance does not replace hip assessment in a newborn or young infant.
References
[1] Rizvi A, Loukas M, Oskouian RJ, Tubbs RS. Let's get a hand on this: Review of the clinical anatomy of "knuckle cracking". Clinical anatomy (New York, N.Y.). 2018 Sep. doi:10.1002/ca.23243. PMID: 30080300.
[2] Nie K, Rymaruk S, Paton RW. Clicky hip alone is not a true risk factor for developmental dysplasia of the hip. Bone Joint J. 2017;99-B(11):1533-1536. doi:10.1302/0301-620X.99B11.BJJ-2017-0416.R1. PMID: 29092995.
[3] deWeber K, Olszewski M, Ortolano R. Knuckle cracking and hand osteoarthritis. J Am Board Fam Med. 2011;24(2):169–174. DOI: 10.3122/jabfm.2011.02.100156. PMID 21383216.
[4] Morris WZ, Mayfield LM, Ellis HB, et al. The Significance of Isolated Hip Click as a Sign of DDH: Implications on Referral Guidelines. J Pediatr Orthop. 2023;43(6):e411–e415. DOI: 10.1097/BPO.0000000000002404. PMID 36998168.
Disclaimer: this content is for informational purposes only and does not replace an individual clinical evaluation.
