Patellar instability following total knee arthroplasty (TKA) is a rare, yet serious complication, potentially requiring revision surgery or resulting in chronic dysfunction. When encountered, it is paramount to understand the etiologies, diagnostic approaches, treatment options, and outcomes of the selected treatment. The most common cause of patella instability is improper positioning of components, leading to lateral maltracking of the patella. Factors such as internal rotation and/or medialization of femoral or tibial components and lateralization of the patellar button have been identified as factors that contribute to instability. Additionally, a longstanding valgus deformity of the knee may exacerbate patella maltracking. Patients typically present with anterior knee pain, worsened by activities like stair climbing, and may report sensations of giving way. Radiographs and computed tomography scans aid in evaluating component positioning and rotation. Operative intervention is often necessary, with options ranging from soft tissue realignment to component revision. Lateral retinacular release is a common approach, although it is associated with complications such as osteonecrosis of the patella. Proximal or distal realignment procedures may be required if instability persists. Some recent case reports have also described medial patellofemoral ligament reconstruction as a treatment modality, but more investigation on the topic is still pending. It is important that the treatment strategy address the underlying cause, as failure to do so may result in recurrent instability. The best way to avoid patella instability is to pay attention to all the details of component position and soft tissue balance during the index procedure.

Patella maltracking is among the most frequent causes of poor outcomes and early failure after total knee arthroplasty (TKA), with an incidence that ranges from 1 to 20%. Even if there is agreement between authors regarding the preoperative and intraoperative management of patella maltracking in TKA, less clear are postoperative conducts. The purpose of this systematic review is to summarize and compare surgical techniques used to treat patella maltracking after TKA.

A systematic review of the literature was performed with a primary search on Medline through PubMed. The PRISMA 2009 flowchart and checklist were used to edit the review. Screened studies had to provide clinical, functional and radiological results and complications of the proposed treatment to be included in the review.

A total of 21 articles were finally included. Three main types of surgical procedures and other minor techniques have been identified to manage patella maltracking after TKA. The choice of the proper technique to use in the specific case depends on several factors, first of all the malpositioning of the prosthetic components.

Patella maltracking after TKA represents a frequent and challenging problem for orthopedic surgeons. Treatments described in the literature are often able to correct an abnormal patellar tracking; nevertheless, authors report variable percentages of residual knee pain and dissatisfaction in re-treated patients. Therefore, it would be desirable to prevent the maltracking condition at the time of primary arthroplasty, using proper surgical precautions.