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What is Medial Patellar Instability?

Medial patellar instability is a disabling condition characterized by medial subluxation of the patella which occurs as a complication of lateral retinacular release surgery. Lateral retinacular release is a surgical procedure employed for the treatment of lateral patellar instability. However, disruption of the lateral patellar structures during this surgery has been associated with medial patellar instability.

Anatomy of the Patella

The patella (kneecap) is a small piece of bone in front of the knee that slides up and down the groove in the femur bone during bending and stretching movements. The ligaments on the inner and outer sides of the patella hold it in the femoral or trochlear groove and prevent dislocation of the patella from the groove.

Causes of Medial Patellar Instability

The dynamic and static lateral patellar stabilizers, including lateral epicondylopatellar ligament and lateral patellotibial ligament, can be compromised at the time of a lateral retinacular release procedure. Any damage to the supporting ligaments of the knee may cause the patella to slip out of the groove either partially (subluxation) or completely (dislocation). Most cases of medial patellar instability are iatrogenic (caused by the treatment of a condition) in nature; however, some spontaneous and traumatic cases can also cause medial patellar instability.

Signs and Symptoms of Medial Patellar Instability

Medial patellar instability causes pain when standing up from a sitting position and a feeling that the knee may buckle or give way. When the kneecap slips partially or completely you may have severe pain, swelling, bruising, visible deformity, and loss of function of the knee. You may also have changes in sensation such as numbness or even partial paralysis below the dislocation because of pressure on the nerves and blood vessels.

Diagnosis of Medial Patellar Instability

To diagnose medial patellar instability, your doctor will review your symptoms, medical history, and conduct a thorough physical examination. Other diagnostic tests such as X-rays, MRI, and CT scan may be ordered to evaluate structural damages around the patella, determine the cause of your pain and instability, and rule out other conditions.

Treatment for Medial Patellar Instability

The treatment for medial patellar instability depends on the severity of the condition and is based on 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 an unsatisfactory response, surgical correction may be recommended.

Several surgical techniques have been recommended for correcting medial patellar instability, including arthroscopic medial retinacular release, direct lateral ligament repair, lateral patellofemoral ligament reconstruction, lateral retinacular reconstruction with augmentation of soft tissue, and lateral patellotibial ligament reconstruction. Your surgeon will decide the best option for you based on your condition.

Surgery is followed by postoperative rehabilitation for a period of 6 weeks and strengthening exercises thereafter for a specified period of time. Progression to full activities may require at least 4 to 6 months.

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