Survivorship Analysis of the Kinematic Stabilizer Total Knee Replacement

Abstract

The Kinematic Stabilizer is a posterior-cruciatesubstituting design of total knee replacement. We have reviewed 109 primary total knee replacements in 95 patients at a mean follow-up time of 12.7 years (10 to 14). We used survival analysis with failure defined as revision of the implant. This gave a cumulative survival rate of 95% (95% CI± 5%) at ten years and 87% (± 10%) at 13 years.These results from an independent centre confirm the value of an established design of cemented total knee replacement and question the wisdom of the introduction of modifications and new designs without properly controlled trials. There are few reports from independent centres of total knee replacement with follow-up longer than ten years and we could find no long-term reports of knee replacement using the Kinematic Stabilizer design. We describe our 10-to 14-year results with this posterior stabilised total knee replacement. PATIENTS AND METHODSFrom 1980 to 1983 inclusive we performed 109 primary total knee replacements on 95 patients, most with rheumatoid arthritis, using the Kinematic Stabilizer prosthesis (Howmedica, Rutherford, New Jersey). In the first year, this implant was used for all knee replacements performed at this hospital. Subsequently, other types became available and the Kinematic Stabilizer was used only when the posterior cruciate ligament was absent or not functioning. All revisions were excluded from the series. All the operations were performed by the senior author (IMP) using the Universal-1 instrumentation and a standard operating technique. No patellae were resurfaced and all components were cemented.The Kinematic Stabilizer total knee replacement is a posterior-cruciate-substituting design (Walker 1980) in which a contoured central post on the tibial polyethylene tray engages a housing in the femoral component. The guiding surfaces provide anteroposterior stability from full extension to 30° of flexion. Posterior stability is maintained as flexion proceeds and the surfaces act to guide femoral rollback (Figs 1 and 2).Our series included 78 women and 17 men; their average age was 64 years (37 to 86) and 17 were under 55. The primary diagnosis was rheumatoid arthritis in 63, osteoarthritis in 29 and psoriatic arthritis in 3.All patients were reviewed annually. Those who did not attend at ten years were traced and contacted. Four patients (six knees) were unwilling to attend but provided information over the telephone. Patients were assessed according to the Knee Society clinical rating system , in which points are allocated for pain, range of motion and stability. Deductions are made for flexion contracture, extensor lag and poor coronal alignment. For the function score, points are gained for walking distance and stair-climbing, and deducted for the use of walking-aids. Each score is given out of a possible 100. Radiographs were obtained and assessed according to the Knee Society Radiological Evaluation Form (Ewald 1989).We performed survival analysis by constructing a life table (Armitage and Berry 1994) ...

Unicompartmental Versus Total Knee Arthroplasty Database Analysis: Is There a Winner?

“…Early survival studies of UKA demonstrated revision rates of 15% to 28% [23,34,44]. More recent articles report substantial increases in survival, with midterm survivorship for UKA of 84% to 98% (Table 1) [10,12,14,19,39,40,42,46,48,[57][58][59][60][61]. O'Rourke et al [43] followed by Price and Svard [49] documented long-term survival rates of UKA at 20 years of 84% and 91%, respectively.…”

A randomised, controlled trial of cemented versus cementless press-fit condylar total knee replacement

“…Many survival analyses of TKR include a number of patients lost to follow-up ranging from 3% to 13% of the initial cohort. [13][14][15][16][17] The reported cumulative survival rates in these series may be an overestimation of the true survival rate. 21 Implant survival data for patients who have died are often not included and some of these prostheses may have been revised before death.…”

“…Other published survival analyses include only limited data concerning clinical outcome. In these reports either clinical assessment is collected and not reported, 22 postoperative scores are reported but not compared with preoperative scores, 14,17,23 or only preoperative scores are included. 13,16 The number of implants with clinical assessment at ten years in our series is only 16% of the original cohort and therefore represents only a minor indication of the clinical outcome.…”

Comparative Epidemiology of Revision Arthroplasty: Failed THA Poses Greater Clinical and Economic Burdens Than Failed TKA

“…These differences carry implications for guiding care and resource allocation. New approaches to capturing the diagnoses and procedures that physicians and hospitals code as part of the billing process, such as the those used by the Nationwide Inpatients Sample (NIS), allow for larger-scale evaluations of the epidemiology of revision total joint arthroplasties than previously could be performed [13,14,17,37,51,56]. Prior studies [7,8] have been done that investigated the revised coding scheme in a national sample [1] to more clearly identify the indications for revision, procedure frequencies, and degree of adoption of the new diagnosis and procedure codes.…”