[Atraumatic dislocation in mobile-bearing total knee arthroplasty: two case reports].
BACKGROUND
Atraumatic dislocation following total knee arthroplasty (TKA) is a rare condition. Severe complications after dislocation are lesion of the vascular-nerve bundle, compartment syndrome or amputation. The benefit of TKA with mobile-bearing are an improvement of the range of motion and better articulation. In comparison to fixed-bearing TKA there is the risk of dislocation or breakage of the polyethylene insert.


METHODS
We present two cases with dislocation following TKA with mobile-bearing. In both cases preoperatively there was a significant weakening of the function of the quadriceps muscle. During revision of the TKA severe damage with multiple scratches of the polyethylene onlay could be detected. The damage of the PE onlay could especially be found at the tibial aspect. Follow-up showed an uneventful course after conversion to fixed-bearing polyethylen component.


CONCLUSIONS
In cases of dislocation following TKA with mobile-bearing operative revision is recommended to exchange the damaged PE onlay and prevent increased wear. TKA with mobile-bearing should be reserved only for cases with a good quadriceps muscle function.
Schuh
A
A
Research Unit Orthopädie und Chirurgie, Klinikum Neumarkt, Lehrkrankenhaus der Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany. alexander.schuh@klinikum.neumarkt.de
Hönle
W
W
D000368:Aged; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D009133:Muscular Atrophy / Q000150:complications; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000601:surgery*; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000532:radiotherapy / Q000601:surgery*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D052097:Quadriceps Muscle / Q000473:pathology; D011859:Radiography; D012008:Recurrence; D012086:Reoperation