Rare Asymptomatic Posterior Dislocation of Mobile Bearing Insert in Unicondylar Knee Arthroplasty: A Case Report.

Dislocation of polyethylene insert is a common complication of mobile bearing uniconylar knee arthroplasty (UKA). Dislocation, when occurs is common in anterior, lateral or medial direction. The authors report a case of posterior dislocation in which patient remained asymptomatic and the dislocation was detected in a routine follow-up radiograph done at 18 months after surgery. UKA was subsequently converted into total knee arthroplasty and patient had a stable knee at two years follow-up with no signs of loosening or instability. Posterior meniscal bearing dislocation may remain asymptomatic and continued examination with high index of suspicion is needed to disclose such complications in the absence of symptoms.