DISLOCATION OF TOTAL KNEE ARTHROPLASTY - A REPORT OF 6 CASES WITH 2 PATTERNS OF INSTABILITY

We report 6 cases of dislocation of total knee arthroplasty (TKA). We identified 2 patterns of instability in the sagittal plane, one with p osterior translation of the tibia, occurring mainly in the postoperati ve period and usually resulting from a trauma, and the other with ante rior translation of the tibia, occurring 6 months to 7 years postopera tively and with no preceding trauma. In the latter group, instability was manifested gradually as a lengthening of the posterior cruciate li gament and the posterior capsule, leading to a recurvatum deformity of the knee.