Traumatic anterior knee dislocation after total knee arthroplasty

Abstract

This article describes a traumatic complete anterior knee dislocation of a previously well-functioning total knee arthroplasty. A thorough physical examination with appropriate radiographic imaging study is required for proper evaluation and treatment of this injury, as it is often associated with neurovascular injury and subsequent global instability of the injured knee is likely.

Traumatic Anterior Dislocation of the Knee Without Any Neurovascular Complication-Case Report

“…We are not aware of any other reports of such a combination of injuries. However similar cases are reported after total knee replacement with and without neurovascular compromise [6,7].…”

Knee-Spanning External Fixation for Recurrent Traumatic Anterior Prosthetic Knee Dislocation With Associated Vascular Injury

“…Posterior dislocation has occurred in prior reports in posterior stabilized designs with a combined flexion and varus moment that causes the femoral component to “jump the post.” The incidence for a posterior stabilized TKA dislocation was 1%-2%, but this has decreased to below 0.5% with redesigned components and techniques [ 2 ]. Anterior prosthetic knee dislocation is limited to several small case series and reports [ [3] , [4] , [5] , [6] , [7] , [8] , [9] , [10] , [11] , [12] ] and represented only 11% of all prosthetic knee dislocations in one recent systematic review [ 1 ]. It occurs by a different mechanism of combined valgus, external rotation, and hyperextension [ 8 ].…”

“…This causes medial collateral and posterior cruciate ligament failure, resulting in anterior instability [ 8 ]. Contributing factors include flexion instability, component malpositioning, extensor mechanism dysfunction [ 5 ], and polyethylene wear [ 4 , 9 , 11 , 12 ]. Patient-related risk factors for instability in TKA include greater preoperative deformities necessitating aggressive ligament releases, neuromuscular pathology resulting in recurvatum (quadriceps weakness) or valgus thrust (weak hip abductors), hip or foot deformity resulting in a valgus moment on the knee, and obesity that complicates exposure, risking collateral ligament injury and component malposition during the index surgery [ 2 , 13 ].…”

Traumatic anterior dislocation of a prosthetic knee, from trauma to delayed onset of vascular injury

“…Different types of etiological factors were reported, and they were not always traumatic factors; the authors focused especially on instability factors. A greater laxity in flexion than in extension, malposition of components, extensor mechanism dysfunction [5] , valgus deformity of the knee [6] , and fracture of polyethylene [7] were all recognized as risk factors. Regardless of these factors, in case of trauma, the scenario could change and traumatic anterior dislocation of a TKA could happen also in a previously well-functioning implant.…”

“…The injured leg should be placed in a brace for 6 weeks. In case of permanent instability, the prosthesis revision with a more constrained implant should be delayed by at least 3 months to reduce the risk of neurovascular bundle damage (already involved in the previous trauma) [5] .…”