Medically reviewed guide · Last updated: 1 September 2026 · Reading time: approx. 10 min

Cracking Joints: When the Cracking Is Harmless — and When It Needs Treatment

The most common noises compared

The causes in detail

Joints are not silent hinges. Noises when moving (the technical term is crepitus) are very common and are not in themselves a sign of disease. Three questions are decisive: Does it hurt? Is the joint swollen? Does it work normally? If pain is the main issue, the guide to joint pain will help you further.

The "pop": a gas cavity in the joint fluid

Joint fluid contains dissolved gases. When a joint is pulled apart — as when you crack your knuckles — the pressure in the joint space drops and a cavity suddenly forms. Real-time MRI images support this explanation, but the details are still the subject of research. Typical is a single, loud noise, then a pause until it works again, often with a feeling of looseness. And the osteoarthritis question? Studies that compared people with a knuckle-cracking habit with others found no increased risk of osteoarthritis in the hand. The data are based on rather small observational studies — but they give no cause for concern.

Snapping tendons and ligaments

When a tendon or a sheet of tendon slides over a bony prominence, it produces a snap that can be repeated with every identical movement. The classic example is "snapping hip" (coxa saltans): on the outside, when a sheet of tendon jumps over the bony bump at the top of the thigh bone (greater trochanter), or on the inside in the groin, caused by the hip flexor tendon. Similar things happen at the knee, the shoulder and behind the outer ankle bone, more often in dancers and runners. If it is painless, it is harmless. If pain develops, for example from an irritated bursa, stretching and strengthening usually help; more on hip problems under hip pain.

Crunching in the knee: kneecap and cartilage

Grinding behind the kneecap when climbing stairs, squatting or getting up is very common, including in young people without symptoms. If there is also pain at the front of the knee, often in young, sporty people, this is called patellofemoral pain syndrome; here, strengthening the thigh and hip muscles has the best evidence (see knee pain). In older people, crunching, pain on exertion and brief stiffness when starting to move can point to osteoarthritis. Crunching alone, however, does not prove osteoarthritis.

Cracking with locking: meniscus and loose bodies

In younger people a meniscus tear often results from a twisting injury; in older people it is frequently due to wear and tear without a clear accident. Typical are clicking with shooting pain at the joint line, swelling and sometimes genuine locking: suddenly the knee can no longer be fully straightened. Detached fragments of cartilage and bone (loose bodies) cause similar symptoms. To be honest: for degenerative meniscus damage without genuine locking, current studies show that keyhole surgery (arthroscopy) usually offers no advantage over targeted physiotherapy.

Instability: when something pops out

Cracking with the feeling that the joint briefly pops out points to instability — for example of the kneecap, of the shoulder after a previous dislocation or of the ankle after repeatedly going over on it. Very mobile joints (hypermobility) also often crack. Here, targeted strength and coordination training provides stability; with repeated dislocations, an orthopaedic assessment makes sense.

Trigger finger and tendon sheaths

In trigger finger (stenosing tenosynovitis), the flexor tendon is thickened or the band that guides it is too tight: the finger gets stuck when straightening and then snaps out with a noticeable jerk, often worse in the morning, sometimes with a nodule you can feel in the palm. It is more common with diabetes and rheumatoid arthritis. It is treated with rest, a splint, a cortisone injection or a minor procedure. Crunching over the wrist during movement can point to inflammation of a tendon sheath, see wrist pain.

Jaw and neck

Cracking in the jaw joint when opening the mouth is often caused by a displaced disc of cartilage and is usually harmless as long as it does not hurt and you can open your mouth freely. With pain, earache or headache, or if the jaw locks, it belongs in a dental practice. Cracking in the neck when turning the head is also usually harmless (see neck pain) — but forcefully cracking your own neck with a jerk is not a good idea: very rarely, injuries to the neck arteries have been reported in connection with forceful manipulation of the cervical spine.

Self-tests: first clues at home

These observations do not replace a diagnosis. But they help you tell harmless cracking apart from symptoms that need treatment.

• The pain check: the most important criterion. Cracking without pain, swelling or restricted function generally needs no treatment.
• The repeat test: if the noise cannot be repeated straight away, that points to the harmless "pop". If it comes with every identical movement, it points more to a snapping tendon.
• The hand-on test: place your hand on the joint while you move it. Fine crunching points to joint surfaces rubbing, a coarse sideways snap to a tendon, a click deep in the joint space with pain more to the meniscus.
• The side-by-side comparison: is the joint swollen, warmer or red, or can it be moved less than on the other side? Then it is more than just a noise.
• The function and stiffness check: does the joint lock or give way? How long does stiffness last in the morning? Short, under about half an hour, fits better with osteoarthritis. Considerably longer, with several swollen joints, points more to an inflammatory condition such as rheumatoid arthritis.

Warning signs: when not to wait

• An audible bang during an accident, with immediate swelling or the feeling that the joint no longer holds
• A locked joint: the knee can no longer be straightened, the mouth can no longer be opened or closed
• A hot, red, very swollen joint, especially with fever, after a joint injection or an operation
• A bang in the heel or calf with the feeling of having been kicked, and being unable to stand on tiptoe — typical of an Achilles tendon rupture
• New cracking, squeaking or instability in an artificial joint, with pain
• Several swollen joints with prolonged morning stiffness

The treatment pathway: step by step

Most joint noises need no treatment. If they do, the approach usually works from the simple to the more elaborate.

1. Accept painless cracking. No cause for concern, no reason for imaging. Just do not force anything.
2. Tackle mild symptoms actively. Adjust the load rather than resting completely, plus strengthening and stretching over a few weeks.
3. Examination at a GP or orthopaedic practice. With pain, swelling, instability or locking. Ultrasound shows fluid in the joint and the tendons, an X-ray shows signs of osteoarthritis; an MRI makes sense if a meniscus or ligament injury with locking or instability is suspected.
4. Physiotherapy. For pain at the front of the knee, snapping hip or unstable joints, strength and coordination training is the core of treatment.
5. Specialist assessment. Rheumatology for signs of inflammation, hand surgery for a stubborn trigger finger, a dental practice for a painful jaw joint.
6. Surgery only with a clear reason. For example with genuine locking due to a meniscus tear, repeated dislocation or a trigger finger that does not improve. The decision is always made by the practice treating you.

The medication angle: when tablets affect tendons and joints

Cracking joints themselves are rarely a side effect. Painful tendons and joints are, though — and they are often not linked to the medicine.

Fluoroquinolones: tendons at risk

Antibiotics such as ciprofloxacin, levofloxacin or moxifloxacin can trigger tendon inflammation and tendon ruptures, most often of the Achilles tendon — sometimes even months after taking them. The risk increases with age, with simultaneous cortisone treatment, with reduced kidney function and after an organ transplant. For this reason, the BfArM (German Federal Institute for Drugs and Medical Devices) warned in 2019 of serious, sometimes long-lasting side effects; these antibiotics should not be used for mild infections. At the first signs in a tendon — pain or swelling — contact the prescribing practice immediately.

Cortisone

Repeated cortisone injections into or next to tendons can weaken them. Cortisone taken long term, such as prednisolone, promotes osteoporosis and, in rare cases, especially at high doses, can disrupt the blood supply to the head of the thigh bone (avascular necrosis of the femoral head). New groin or hip pain during prolonged cortisone treatment therefore needs to be assessed by a doctor.

Joint pain as a side effect

Statins such as atorvastatin mainly cause muscle pain, sometimes joint pain too. Aromatase inhibitors such as anastrozole or letrozole, which are used after breast cancer, often lead to joint pain and stiffness; trigger finger and carpal tunnel syndrome also occur more often on them. With DPP-4 inhibitors such as sitagliptin, severe joint pain that subsided after stopping the medicine has rarely been reported. Isotretinoin for acne and bisphosphonates can also trigger joint and muscle pain. Diuretics such as hydrochlorothiazide and low-dose acetylsalicylic acid (aspirin) raise uric acid and can encourage an attack of gout.

Painkillers: targeted rather than across the board

Painless cracking does not need medication. For painful osteoarthritis of the knee or fingers, anti-inflammatory gels such as diclofenac are a well-studied option with fewer side effects than tablets. Tablets such as ibuprofen should not be taken for pain for longer than four days without medical advice. The choice of long-term treatment is made by the practice treating you.

How to keep your joints healthy

• Movement feeds your joints — cartilage has no blood vessels of its own and is nourished by the alternation of loading and unloading. Regular, moderate exercise does joints good.
• Stabilise with muscle — strong thighs take the load off the knee, strong trunk and hip muscles take it off the hip. With very mobile joints, the rule is: strength before stretching.
• Increase the load gradually — warm up and build up training volumes step by step. Sudden jumps in training are a common trigger of tendon irritation.
• Keep an eye on your weight — excess weight increases the load on the knees and hips and is considered an important risk factor for osteoarthritis.
• Do not force anything — cracking that happens by itself is fine. You should avoid forcibly cracking joints, especially the neck.

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