Patellar Instability (Kneecap Dislocation)

Patellar Instability: Understanding Kneecap Dislocation and Treatment Options

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Introduction

Patellar instability occurs when the kneecap (patella) slips out of its normal position, often moving to the side of the knee. This condition can cause pain, swelling, and a feeling that the knee might give way. It can happen after an injury or from ongoing weakness or looseness in the knee structures. Understanding the causes and treatments can help you regain stability and confidence in your knee.

What is Patellar Instability (Kneecap Dislocation)?

Patellar instability refers to the kneecap sliding out of place, usually toward the outside of the knee. This can range from a brief slip to a full dislocation where the kneecap moves completely out of its groove. People with this condition may experience repeated episodes or chronic instability, which can lead to pain, swelling, and difficulty walking or bending the knee.

What is the Medial Patellofemoral Ligament (MPFL)?

The MPFL is a key ligament on the inner side of the knee that helps keep the kneecap centered in its groove during movement. It acts as a strong tether, preventing the kneecap from sliding outwards. When the kneecap dislocates, the MPFL is often stretched or torn, reducing its ability to stabilize the knee.

Treatments for Patellar Instability in Adults vs. Children

Treatment depends on the patient’s age, activity level, and severity of instability.

In children and adolescents, non-surgical treatments like physical therapy to strengthen the muscles around the knee and improve coordination can be effective if the instability is due to an injury. Surgery is considered if instability persists, if there are repeated dislocations, or if there is an associated fracture. However, instability can also result from overall leg malalignment, which might require a more extensive workup and a conversation with your surgeon about surgical correction.
In adults, treatment often starts with physical therapy and bracing. If instability continues or the MPFL is damaged, surgery may be recommended to reconstruct the ligament and restore knee stability.

Recovery Following MPFL Reconstruction Surgery

Recovery after MPFL reconstruction involves a structured rehabilitation program. Physical therapy begins soon after surgery to restore motion, build strength, and improve stability. Most patients gradually return to normal activities over several months. Full recovery depends on following the rehab plan and avoiding activities that stress the healing ligament. With proper care, many people regain confidence and stability in their knee.

References

Pauyo T, Park JP, Bozzo I, Bernstein M. Patellofemoral Instability Part I: Evaluation and Nonsurgical Treatment. J Am Acad Orthop Surg. 2022;30(22):e1431-e1442. doi:10.5435/JAAOS-D-22-00254.

Drapeau-Zgoralski V, Swift B, Caines A, et al. Lateral Patellar Instability. J Bone Joint Surg Am. 2023;105(5):397-409. doi:10.2106/JBJS.22.00756.

Hurley ET, Colasanti CA, Anil U, et al. Management of Patellar Instability: A Network Meta-Analysis of Randomized Control Trials. Am J Sports Med. 2022;50(9):2561-2567. doi:10.1177/03635465211020000.

Colvin AC, West RV. Patellar Instability. J Bone Joint Surg Am. 2008;90(12):2751-2762. doi:10.2106/JBJS.H.00211.

Vavken P, Wimmer MD, Camathias C, et al. Treating Patella Instability in Skeletally Immature Patients. Arthroscopy. 2013;29(8):1410-1422. doi:10.1016/j.arthro.2013.03.075.