Through-tunnel reconstruction with Ligament Augmentation and Reconstruction System (LARS) for managing post-arthroplasty patellofemoral instability

Background: Despite advancements in prosthetic designs and surgical techniques, patellar dislocation remains a rare but significant complication following total knee arthroplasty, with an incidence ranging between 0.15% and 0.5%. This condition often requires revision surgery to alleviate discomfort and restore joint function. Among the methods to address patellofemoral instability, medial patellofemoral ligament reconstruction has gained attention. In this case, we present the first report of using the synthetic Ligament Augmentation and Reconstruction System (LARS; Surgical Implants and Devices, Arc-sur-Tille, France) for medial patellofemoral ligament reconstruction following patellar dislocation after total knee arthroplasty, offering a novel approach to avoid donor site morbidity.

Case presentation: An 87-year-old man with no significant comorbidities underwent NexGen posterior-stabilized-total knee arthroplasty (Zimmer Biomet, Warsaw IN) for advanced osteoarthritis in his left knee. Three months postoperatively, he experienced a persistent giving-way sensation and swelling in the knee after a fall. Physical examination revealed patellar subluxation, confirmed by imaging studies. A computed tomography scan showed no malrotation of the femoral or tibial components. The patient was diagnosed with a medial patellar retinacular tear and medial patellofemoral ligament rupture. He underwent medial patellofemoral ligament reconstruction using a Ligament Augmentation and Reconstruction System (LARS; Surgical Implants and Devices, Arc-sur-Tille, France) synthetic ligament, and the medial retinaculum was repaired. After a year of follow-up, the patient reported satisfactory knee stability, with no recurrence of patellar dislocation.

Conclusion: This case demonstrates the successful use of a synthetic Ligament Augmentation and Reconstruction System for Medial patellofemoral ligament reconstruction in managing post-arthroplasty patellar dislocation. It offers a less invasive alternative to autograft harvesting, reducing donor site morbidity while providing effective stabilization of the extensor mechanism. This approach could have significant clinical implications, particularly for elderly patients with compromised bone healing capacity.