Patellar Instability after Total Knee Arthroplasty

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Reconstructive Surgery

Background:

• Patellar instability is a rare but serious complication following total knee arthroplasty (TKA).
• It can lead to chronic dysfunction and necessitate revision surgery.
• Understanding its causes, diagnosis, and treatment is critical for patient outcomes.

Purpose of the Study:

• To review the etiologies, diagnostic methods, treatment options, and outcomes for patellar instability post-TKA.
• To emphasize the importance of accurate component positioning and soft tissue balance during the primary surgery.

Main Methods:

• Review of common causes, including component malpositioning (femoral, tibial, patellar) and pre-existing knee deformities.
• Discussion of diagnostic tools such as radiographs and computed tomography (CT) scans.
• Overview of surgical interventions, including soft tissue realignment, component revision, and lateral retinacular release.

Main Results:

• Improper component positioning, such as internal rotation or medialization of femoral/tibial components and lateralization of the patellar button, is the most common cause.
• Valgus knee deformity can exacerbate patellar maltracking.
• Surgical options vary, with potential complications like patellar osteonecrosis from lateral retinacular release.

Conclusions:

• Addressing the underlying cause of instability is paramount to prevent recurrence.
• Meticulous attention to component positioning and soft tissue balance during the index TKA procedure is the most effective preventive strategy.
• Further research is needed for emerging treatments like medial patellofemoral ligament reconstruction.