Crepitus is a completely harmless condition that feels quite similar to cracking your knuckles or back. Squats and lunges, for example, can squish any gas trapped in the synovial fluid surrounding your knee (synovial fluid protects and lubricates your joints), resulting in a popping sensation or even an audible “crack,” explains Mike T. Nelson, an exercise physiologist and certified strength and conditioning specialist based in Minnesota.
While this kind of crepitus may be unsettling if you are unfamiliar with it, it is usually neither painful or dangerous. It is frequent in individuals of all ages, and a 2013 Clinical Orthopedics and Related Research research found that painless popping is not a reason for concern even in patients who have crepitus after knee surgery. “If you are in your 30s and are at the gym lifting weights or doing squats and hear popping sounds and creaking in your knees, this does not always indicate anything is wrong,” says Dr. Rebecca Shepherd, head of rheumatology at Lancaster General Health/Penn Medicine. “However, if you are 65 and your knees ache when you ascend and descend stairs, and you have a grinding sensation, you may have osteoarthritis,” which is the common, ‘wear-and-tear’ kind of arthritis.
Crepitus may really be the sound of your joint structures grinding against one another – and that’s a warning of impending knee issues, says Tony D’Angelo, senior vice president of clinical operations at Professional Physical Therapy in New York.
“Cracking, or ‘crepitus,’ may occur as a result of improper alignment of the knee cap, or patella, inside the groove created by the knee joint’s bones,” D’Angelo explains. “It may result in the gradual deterioration of the joint’s protecting cartilage. The wearing progressively increases over time, and when the fragile cartilage is worn away enough, it becomes very painful and eventually results in an arthritic joint.” In a research of almost 3,500 participants published May 4, 2017, in the journal Arthritis Care & Research, individuals who first had greater knee crepitus – but no other symptoms – were more likely to develop knee osteoarthritis than those who initially experienced less or no crepitus.
According to a research published in the November-December 2019 edition of the Brazilian Journal of Physical Therapy, individuals with knee crepitus reported somewhat poorer physical function and knee-related quality of life than those without crepitus. Additionally, 2014 research published in Osteoarthritis and Cartilage, the official journal of the Osteoarthritis Research Society International, determined that crepitus is a precursor to patellofemoral joint (where your knee cap meets your thigh bone) lesions and future osteoarthritis in the area when combined with knee cap pain.
Knee osteoarthritis, which affects about 13% of women and 10% of men aged 60 and older, is a major cause of disability in the United States, according to a study published in the Caspian Journal of Internal Medicine.