Acute, recurrent total knee dislocation: Polyethylene dislocation and malreduction

Abstract

A 62-year-old man underwent total knee arthroplasty using a mobile-bearing prosthesis. Four days post-operatively the patient experienced the first of several acute knee dislocations. Closed reduction was performed at an outside hospital a total of three times prior to presentation at this institution. A two-stage exchange of the TKA was recommended due to the clinical suspicion for an infected prosthesis. Upon surgical exploration, it was discovered that the polyethylene insert had spun out completely to 180°. Closed reduction attempts of a posterior dislocation of a mobile-bearing knee prosthesis may contribute to complete 180° spinout of the polyethylene insert.

Complete 180-Degree Dislocation of a Rotating Platform after Closed Reduction for Mobile Bearing Spinout

“…The RP TKA was designed to help decrease backside polyethylene wear and allow maximal conformity between the femoral and tibial component [1,2]. There have been multiple reports of dislocation and spinout of these implants at various time intervals after the index procedure [3][4][5][6]. Spinout of RPs is most commonly due to flexion gap asymmetry or a tight posterior cruciate ligament [2].…”

“…[ 3 ] occurred with a PS mobile-bearing device. Two subsequent cases involving cruciate-retaining mobile-bearing devices have also been reported, one in which the initial event of dislocation may have occurred 6 years previously at the index procedure [ 5 , 6 ].…”

“…A spinout, or rotational dislocation of the polyethylene insert, is a rare occurrence due to external rotation or valgus/varus stress with the knee in flexion [3]. Three case reports of 180 rotatory dislocation of the polyethylene component occurred during relocation of an RP device, with only one prior case in a PSRP device [3][4][5]. Here, we describe an instance of platform rotation after patellar dislocation in a PSRP implant knee.…”

Spontaneous 180-Degree Rotatory Dislocation of Rotating-Platform Total Knee Arthroplasty

“…Risk factors for TKA dislocation including female gender, obesity, and valgus deformity were described by Fisher et al who documented characteristics of dislocation in 7 out of 1255 cruciate-retaining mobile-bearing TKAs [8]. Additional risk factors include advanced age and previous patellectomy [9]. This suggests that special precaution must be taken in certain patient populations during follow-up of TKA.…”

The role of mediation in present day practice : illustrations from case studies

“…X-rays of the right knee revealed a valgus deformity of the knee with spinout of the whole tibial insert, which is a rare complication of knee replacement. 7 Immediately following this consultation, the patient consulted a lawyer and instituted a negligence and malpractice claim of several million rands against Dr A, who was instructed not to contact the patient again. The case dragged on, without progress being made, between 2013 and 2018.…”