Anterior Knee Pain & Patella Instability
Patellofemoral Pain Syndrome
Anterior knee pain
Anterior knee pain is a characterized by a chronic pain over the front and centre of the knee joint. It is common in athletes, active adolescents (especially girls) and overweight individuals. Anterior knee pain refers to a variety of conditions which include runner’s knee or patellar tendinitis and chondromalacia of the patella. There is an inter-individual variation in the duration and presentation of pain.
The knee joint is a large, complex joint in the body comprising of three bones, i.e. the lower end of the thigh bone or femur, upper end of the shinbone or tibia, and the kneecap or patella. The patella moves over the joint and allows bending of the knee and straightening of the leg. There are a few major ligaments situated around the knee joint which hold the joint firmly in position and contribute to the stability of the knee.
Anterior knee pain usually develops due to improper movement of the knee cap causing it to rub against the lower end of the femur bone. This may occur secondary to an imbalance or poor flexibility of the thigh muscles that stabilize the knee joint, problems with alignment of the knee joint, flat foot, tightness or weakness of the front and back muscles of the thigh, excessive sports activities, improper sports training techniques or improper use of equipment. Other possible causes for anterior knee pain include arthritis, cartilage injury and dislocation or fracture of the patella or knee cap.
Pain is the predominant symptom and is usually gradual in onset. Patients may experience a dull aching pain around the sides, below or behind the knee cap. Sometimes, climbing stairs and standing up or walking after prolonged sitting may produce a popping or cracking sound in the knee. The pain may also be present at night and be exaggerated by any repetitive knee bending activity such as jumping, squatting, running or weight lifting. Any changes in the activity level, playing surface or equipment may also result in pain.
Diagnosis of anterior knee pain includes a medical history and physical examination along with imaging tests such as X-ray and MRI scan. Physical examination determines the cause of pain and other related problems while X-rays and MRI scan aid in confirming the condition by providing visualization of the internal structures.
A majority of patients respond to conservative treatment which includes application of ice, rest and well programmed rehabilitation exercises. Ice helps to relieve the swelling and inflammation, rest protects the joint from repetitive injury while stretching and mobilization exercises improve muscle strength, flexibility and range of motion. Sometimes, if needed, pain relieving medication and anti-inflammatory drugs may also be used. Surgical treatment is rarely indicated.
Chronic persistent pain needs to be reported to the doctor immediately. Once the pain has been treated, a recurrence can be prevented by following a few simple measures which include:
- Wearing appropriate shoes for your sporting activities
- Performing warm up exercises before any physical activity
- Discontinue any activity causing pain in your knees
- Modulating the intensity of activity depending on your condition
Patellar (knee cap) instability results from one or more dislocations or partial dislocations (subluxations). Patella is the small piece of bone in front of the knee that slides up and down the femoral groove (groove in the femur bone) during bending and stretching movements. The ligaments on the inner and outer sides of patella hold it in the femoral groove and avoid dislocation of patella from the groove.
Any damage to these ligaments may cause patella to slip out of the groove either partially (subluxation) or completely (dislocation). This misalignment can damage the underlying soft structures such as muscles and ligaments that hold the knee cap in place. Once damaged, these soft structures are unable to keep the patella (knee cap) in position. Repeated subluxation or dislocation makes the knee unstable and the condition is called as knee instability.
Patients with knee instability experience different signs and symptoms such as:
- Pain, especially when standing up from a sitting position
- Feeling of unsteadiness or tendency of the knee to “give way” or “buckle”
- Recurrent subluxation
- Recurrent Dislocation
- Severe pain, swelling and bruising of the knee immediately following subluxation or dislocation
- Visible deformity and loss of function of the knee often occurs after subluxation or dislocation
- Sensation changes such as numbness or even partial paralysis can occur below the dislocation as a result of pressure on nerves and blood vessels
Various factors and conditions may cause patellar instability. Often a combination of factors can cause this abnormal tracking and include the following:
Anatomical defect: Flat feet or fallen arches and congenital abnormalities in the shape of the patella bone can cause misalignment of the knee joint.
Abnormal “Q” Angle: The “Q” angle is a medical term used to describe the angle between the hips and knees. The higher the “Q” angle, such as in patients with Knock Knees, the more the quadriceps pull on the patella causing misalignment.
Patellofemoral Arthritis: Patellar misalignment causes uneven wear and tear and can eventually lead to arthritic changes to the joint.
Improper Muscle Balance: Quadriceps, the anterior thigh muscles, function to help hold the kneecap in place during movement. Weak thigh muscles can lead to abnormal tracking of the patella, causing it subluxate or dislocate.
Your surgeon diagnoses the condition by collecting your medical history and physical findings. He may also order certain tests such as X-rays, MRI or CT scans to confirm the diagnosis.
Treatment for instability depends on the severity of condition and based on the diagnostic reports. Initially your surgeon may recommend conservative treatments such as physical therapy, use of braces and orthotics. Pain relieving medications may be prescribed for symptomatic relief. However when these conservative treatments yield unsatisfactory response surgical correction may be recommended.
Considering the type and severity of injury surgeon decides on the surgical correction. A lateral retinacular release may be performed where your surgeon releases, or cuts, the tight ligaments on the lateral side (outside) of the patella enabling the patella to slide more easily in the femoral groove.
Your surgeon may also perform a procedure to realign the quadriceps mechanism by tightening the tendons on the inside or medial side of the knee.
If the misalignment is severe tibial tubercle transfer (TTT) will be performed. This procedure involves the surgeon removing a section of bone where the patellar tendon attaches on the tibia. The bony section is then shifted and properly realigned with the patella and reattached to the tibia with two screws.
Following the surgery rehabilitation program may be recommended for better outcomes and quicker recovery.