The knee joint connects the thigh bone (femur) to the shin bone (tibia), with the kneecap (patella) at the front. While designed for stability, parts of this joint can sometimes shift from their normal position. This article focuses on patellar subluxation, where the kneecap partially moves out of alignment, and discusses its treatment.
Understanding Knee Subluxation
Knee subluxation most commonly refers to patellar subluxation, an incomplete dislocation of the kneecap (patella). The patella acts as a protective shield for the knee joint and plays a significant role in knee extension by increasing the quadriceps tendon’s leverage.
The patella normally glides within the patellofemoral or trochlear groove, a shallow V-shaped channel on the thigh bone. When subluxation occurs, the patella typically shifts toward the outside of the leg, though it can sometimes move inward.
Why It Happens and How It Feels
Patellar subluxation results from various factors, including anatomical predispositions, muscle imbalances, and injuries. Weakness or tightness in hip and thigh muscles, or ligament laxity, can increase kneecap shifting. Common triggers include sudden twisting motions of the knee or a direct impact. Anatomical variations like a shallow patellofemoral groove or patella alta also increase susceptibility.
When subluxation occurs, individuals describe the knee “giving way” or the kneecap “shifting” to the side. Pain around the kneecap is a common symptom, often worsening with activity or prolonged sitting. Other signs include swelling, stiffness, and a popping or grinding sensation within the knee.
Getting a Diagnosis and Initial Care
A healthcare professional diagnoses patellar subluxation through a comprehensive evaluation. This involves a detailed medical history, including the incident and symptoms, followed by a physical examination. During the exam, the doctor checks for tenderness, swelling, and assesses the kneecap’s movement.
Imaging tests confirm diagnosis and rule out other injuries. X-rays evaluate bone alignment and detect fractures. MRI scans assess soft tissue damage, such as ligament tears (e.g., MPFL) or cartilage damage.
Following an acute subluxation, initial care focuses on managing pain and swelling. The RICE method—Rest, Ice, Compression, and Elevation—is commonly recommended. Rest involves avoiding aggravating activities; ice reduces swelling and discomfort. Compression controls inflammation, and elevation drains fluid. A brace may also stabilize the knee during initial healing.
Paths to Recovery
Non-surgical treatments are often the first approach for patellar subluxation. Physical therapy plays a central role, focusing on exercises to strengthen the muscles surrounding the knee and hip, including the quadriceps, hamstrings, and hip abductors. These exercises improve patellar tracking and kneecap stability. Bracing or taping provides external support and guides kneecap movement. Pain management strategies, such as nonsteroidal anti-inflammatory drugs (NSAIDs), and activity modification are also important.
Surgical options are considered for recurrent patellar subluxations unresponsive to non-surgical efforts, or significant structural damage. One common procedure is Medial Patellofemoral Ligament (MPFL) reconstruction, which replaces a torn or stretched MPFL, a key kneecap-stabilizing ligament. Another approach is tibial tuberosity transfer, where a shin bone prominence is repositioned to improve kneecap alignment. These procedures realign or stabilize the kneecap, preventing future episodes.
Rehabilitation is crucial for long-term recovery, whether treatment is non-surgical or surgical. This program, often guided by a physical therapist, restores full range of motion, strength, and function. Adherence to protocols is important for optimal outcomes and safely returning to activities.