Clin Orthop Surg.  2014 Jun;6(2):165-172. 10.4055/cios.2014.6.2.165.

Results of Revision Surgery and Causes of Unstable Total Knee Arthroplasty

Affiliations
  • 1Department of Orthropaedic Surgery, Sun General Hospital, Daejeon, Korea. mydangjang@naver.com

Abstract

BACKGROUND
The aim of this study was to evaluate causes of unstable total knee arthroplasty and results of revision surgery.
METHODS
We retrospectively reviewed 24 knees that underwent a revision arthroplasty for unstable total knee arthroplasty. The average follow-up period was 33.8 months. We classified the instability and analyzed the treatment results according to its cause. Stress radiographs, postoperative component position, and joint level were measured. Clinical outcomes were assessed using the Hospital for Special Surgery (HSS) score and range of motion.
RESULTS
Causes of instability included coronal instability with posteromedial polyethylene wear and lateral laxity in 13 knees, coronal instability with posteromedial polyethylene wear in 6 knees and coronal and sagittal instability in 3 knees including post breakage in 1 knee, global instability in 1 knee and flexion instability in 1 knee. Mean preoperative/postoperative varus and valgus angles were 5.8degrees/3.2degrees (p = 0.713) and 22.5degrees/5.6degrees (p = 0.032). Mean postoperative alpha, beta, gamma, delta angle were 5.34degrees, 89.65degrees, 2.74degrees, 6.77degrees. Mean changes of joint levels were from 14.1 mm to 13.6 mm from fibular head (p = 0.82). The mean HSS score improved from 53.4 to 89.2 (p = 0.04). The average range of motion was changed from 123degrees to 122degrees (p = 0.82).
CONCLUSIONS
Revision total knee arthroplasty with or without a more constrained prosthesis will be a definite solution for an unstable total knee arthroplasty. The solution according to cause is very important and seems to be helpful to avoid unnecessary over-constrained implant selection in revision surgery for total knee instability.

Keyword

Unstable total knee; Total knee instability; Revision arthroplasty

MeSH Terms

Aged
Aged, 80 and over
Arthroplasty, Replacement, Knee/*adverse effects
Female
Humans
Joint Instability/*etiology
Knee Joint/*surgery
Knee Prosthesis
Male
Middle Aged
*Prosthesis Failure
Reoperation
Retrospective Studies
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