The audible clicking, grinding, or popping sensation in a joint is known as crepitus. While crepitus in the knee during squatting is common and usually harmless, the addition of pain fundamentally changes the situation. Discomfort indicates a mechanical issue where tissues are being irritated or damaged under the high compressive load of the squat. This combination of sound and pain signals an underlying physiological problem within the patellofemoral joint, which connects the kneecap and thigh bone.
The Underlying Causes of Painful Knee Crepitus
The primary reason for a painful click during a deep knee bend is friction or mechanical impingement within the joint. This occurs when the kneecap (patella) does not track smoothly within the groove of the femur. Improper movement under load causes the underside of the patella to rub against the bone, leading to a grinding sensation and pain.
Patellofemoral Pain Syndrome (PFPS)
The most frequent cause, especially in active younger individuals, is Patellofemoral Pain Syndrome (PFPS), sometimes called “runner’s knee.” This condition is characterized by the patella maltracking, often pulled slightly to the outside of the knee. This malalignment can be caused by muscle imbalances, such as weakness in the hip and gluteal muscles or tightness in the iliotibial band and lateral quadriceps muscles. When the knee bends deeply in a squat, the patella is pulled unevenly, leading to friction and pain.
Early-Stage Osteoarthritis (OA)
In older individuals, or those with a history of knee trauma, painful crepitus can point toward early-stage Osteoarthritis (OA). This degenerative process involves the breakdown of the smooth, protective articular cartilage that covers the ends of the bones. As this cartilage wears thin, the joint surfaces become rough and uneven, causing a grating sound and pain when the knee is flexed under pressure.
Meniscal Issues
A torn or degenerated meniscus can also produce a distinct, painful clicking or clunking sensation, particularly during deep flexion like squatting. The menisci are C-shaped pieces of cartilage that act as shock absorbers between the shinbone and thigh bone. A flap of torn meniscal tissue can occasionally catch or flip out of place as the knee joint moves, resulting in sharp, localized pain and an audible click or locking sensation.
Immediate Self-Management Strategies
The immediate goal when experiencing painful crepitus is to reduce irritation and inflammation without completely stopping movement. Activity modification is a foundational step, meaning you should temporarily avoid deep squatting and other high-load activities that reproduce the pain. Limit knee flexion to the point just before the clicking or pain begins, guided by the concept of a “pain-free range of motion.”
Using the RICE principles can help manage acute symptoms, primarily focusing on rest and ice. Applying ice to the front of the knee for 10 to 15 minutes after activities that caused discomfort can help calm inflammation. Over-the-counter Nonsteroidal Anti-Inflammatory Drugs (NSAIDs), such as ibuprofen or naproxen, can reduce pain and swelling. These should only be used temporarily and with caution, taken with food to reduce the risk of stomach irritation, and strictly adhering to dosage instructions.
Strengthening exercises should focus on low-impact movements that stabilize the knee without excessive compressive force on the patellofemoral joint. Quad sets, where you tighten the thigh muscle to press the back of the knee down, are excellent for rebuilding muscle activation. Straight leg raises, performed with a straight knee, also strengthen the quadriceps and hip flexors without requiring a deep bend. Hip and gluteal strengthening exercises, such as clamshells, are essential because hip weakness is often linked to poor knee alignment.
When Formal Medical Evaluation is Necessary
While self-care can address mild irritation, certain symptoms should prompt an evaluation by a healthcare professional. Seek prompt medical attention if the pain is sudden, severe, or prevents you from bearing weight. Other red flags include significant swelling, the knee feeling like it is locking or catching, or if the pain and clicking do not improve after two weeks of consistent self-management.
A medical evaluation typically begins with a physical examination to test the knee’s range of motion and stability. The physician or physical therapist will assess the tracking of the kneecap and look for tenderness along the joint line. Imaging, such as an X-ray, may be ordered to check for signs of advanced cartilage loss or bone spurs associated with Osteoarthritis. An MRI scan is generally reserved for cases where a soft tissue injury, like a significant meniscal tear, is suspected.
The primary professional treatment pathway is physical therapy (PT), which addresses the root cause of the malalignment. PT focuses on a structured program of strengthening the hip abductors, hip external rotators, and the vastus medialis obliquus (VMO) portion of the quadriceps to improve patellar tracking. For specific conditions like moderate OA, injections may be considered as an adjunct to therapy. Corticosteroid injections provide immediate, short-term relief by reducing acute inflammation, while Hyaluronic Acid injections supplement the joint’s natural lubricating fluid for longer-term pain management. Surgical intervention is typically reserved as a last resort for severe cases, such as large meniscal tears that cause persistent locking or advanced Osteoarthritis.