Twenty-year survivorship of a cemented mobile bearing Total Knee Arthroplasty.

BACKGROUND: Increasing numbers of Total Knee Arthroplasty (TKA) operations are carried out worldwide each year. This brings with it an ever-increasing revision burden and it is therefore important to appreciate both the functional outcome and survivorship of established arthroplasties when considering new designs. We aim to evaluate the long-term survivorship of a fully cemented mobile bearing Total Knee Arthroplasty. METHODS: This study prospectively analyses the 20-year survivorship of a cohort of 487 consecutive patients who underwent cemented TKA under the care of a single surgeon using the Low Contact Stress (LCS) rotating platform (RP) implant. These patients were followed up prospectively with patient reported and functional outcomes recorded at regular intervals postoperatively. RESULTS: Five hundred and forty-two consecutive primary TKAs were carried out in 487 patients. A total of 139 knees (25.6%) were reviewed at 20 years post-operation. Overall cumulative survivorship, using revision for any reason as primary endpoint, was 98.0%. Mean Knee Society Scores for the patient cohort were 87.3 (Clinical score) and 52.5 (Functional score). Eleven (2.0%) were revised within 20 years - two for aseptic loosening, two for unexplained pain, five secondary patellar resurfacings for anterior knee pain, one for late infection and one liner exchange following spin-out. CONCLUSION: This series demonstrates excellent survivorship and satisfactory outcome of a cemented mobile bearing TKA at 20 years.

Total Knee Arthroplasty in Severe Valgus Deformity Using a Modified Technique-A 10-Year Follow-Up Study.

BACKGROUND: Valgus knee deformity accounts for only 10% of total knee arthroplasties (TKAs), but is frequently considered the most challenging to manage. This study provides a 10-year follow-up on a previously reported series of severe valgus knees performed using an unconstrained mobile-bearing TKA with a modified technique to validate this technique. METHODS: A consecutive series of 275 predominantly cementless TKAs in 262 patients were performed for severe valgus (≥10°) deformity and prospectively followed to 10 years. Patient-reported outcome measures included the Oxford Knee Score, American Knee Society Score, Bartlett Patellar Score, and the Short Form 12 questionnaire. RESULTS: Average valgus deformity was reduced from 15.6° to 3.8° (P < .001). At a mean follow-up of 10.4 years (range, 9.5-14.1), 90 (34.4%) patients had died. Of the reviewed survivors, the mean Oxford Knee Score was 27.8 ± 9.8, with an American Knee Society clinical score of 85.6 ± 17.0 and a functional score of 65.1 ± 20.4, with 78% of patients reporting good to excellent results. To date, there has been 1 (0.36%) revision and 13 (4.73%) reoperations. Kaplan-Meier implant survival was 99.6% at 10 years. CONCLUSION: Despite its challenging nature, the valgus knee is associated with excellent survivorship and satisfactory long-term results using this modified technique. LEVEL OF EVIDENCE: Level IV.

Seventeen to Twenty Years of Follow-Up of the Low Contact Stress Rotating-Platform Total Knee Arthroplasty With a Cementless Tibia in All Cases.

BACKGROUND: Total knee arthroplasty designs can be categorized by bearing design and fixation method. The mobile-bearing concept was developed with the aim of increasing longevity and improving function by reduced polyethylene wear and closer replication of physiological knee motion. Cementless fixation has the goal of achieving a long-lasting "biological" fixation between prosthesis and bone. METHODS: Prospective analysis of the survivorship and patient-reported functional outcomes of a series of 500 low contact stress rotating-platform mobile-bearing total knee arthroplasties with a cementless tibial component with a minimum 17-year follow-up. RESULTS: Five hundred primary total knee arthroplasties were conducted in 467 patients. Mean follow-up was 18.1 (17.0-21.8) years and 141 (28.2%) knees were alive and available for review. Using revision for any cause as the end point, cumulative survivorship was 97.4%. Thirteen knees required revision: 3 for deep infection, 3 bearing only revisions for spinout, 3 for tibial tray subsidence, 2 secondary patella resurfacings, 1 aseptic loosening, and 1 for suspected aseptic loosening that was found to be well fixed. Mean American Knee Society Scores were 83 (evaluation) and 48 (function), Mean Oxford Knee Score was 32.1, and the mean Bartlett Patellar Score was 21.6. CONCLUSION: This series demonstrates excellent survivorship and acceptable patient-reported functional outcome scores of a mobile-bearing total knee arthroplasty with a cementless tibial tray at minimum 17-year follow-up.

A prospective evaluation of a largely cementless total knee arthroplasty cohort without patellar resurfacing: 10-year outcomes and survivorship.

BACKGROUND: The theoretical benefits of a mobile bearing design in Total Knee Arthroplasty (TKA) include increased articular surface conformity with a reduction in both polyethylene wear and implant interface shear. However, to date these theoretical advantages have not been translated into published evidence of superior survivorship. This paper presents the results of a prospective, non-comparative study evaluating the performance of the mobile bearing Low Contact Stress LCS Complete Rotating Platform TKA in a largely cementless cohort without patellar resurfacing. METHODS: 237 consecutive patients (240 knees) undergoing primary TKA were prospectively recruited. All received the LCS Complete Rotating Platform TKA (DePuy International, Leeds, UK). Clinical and radiographic assessments were performed at 3, 12, 60 and 120 months post-operatively. Radiographic evaluation was performed by an independent external surgeon. RESULTS: The mean age was 70.3 years. 77.5% of cases were cementless. Radiographic assessment suggested excellent femoral component fixation. 22 tibial radiolucent lines (RLLs) > 1 mm were observed in 12 knees. No RLLs were progressive. There have been two revisions; one for late infection and one for aseptic loosening. No patients underwent secondary patellar resurfacing. The cumulative implant survivorship, using component revision for any reason as the endpoint, was 98.9% (95% CI, 95.6 to 99.7%) at 10 years. CONCLUSIONS: The excellent survivorship at a minimum 10-year follow-up supports the use of uncemented porous coated fixation without patellar resurfacing with the non-posterior stabilized LCS Complete Rotating Platform TKA.

Spinout/Dislocation in Mobile-Bearing Total Knee Arthroplasty: A Report of 26 Cases.

BACKGROUND: Excellent medium-term to long-term results for function and survivorship have been shown with mobile-bearing (MB) total knee arthroplasty (TKA). One of the key arguments against its use is the risk of "spinout" or dislocation of the MB. The aim of this study is to discuss the etiology, prevention, incidence, management, and outcome of spinout. METHODS: Between October 1993 and February 2016, 8373 consecutive primary MB TKAs were performed irrespective of preoperative deformity. Before 2001, soft-tissue knee balancing was achieved by release of collateral ligaments and all spinouts were treated by open reduction. Thereafter, soft-tissue balancing was achieved without ligament release and with the use of a higher conformity MB and all spinouts were reduced closed, giving 2 comparative cohorts. RESULTS: Twenty-six spinouts occurred in 8373 (0.31%) patients. In the first cohort up until May 2001, there were 14 spinouts of 2379 (0.58%) cases. There were 12 in cohort 2, in those patients having surgery after May 2001, thus giving an incidence of 12 of 5994 (0.2%), which was significantly lower than in cohort 1 (P < .01). Spinout was associated with the valgus knee (P < .01) and most (73%) occurred within the first 6 months. There was 1 arthrodesis in cohort 1 and 1 both-component revision in cohort 2. CONCLUSION: The etiology of spinout is flexion gap instability. It can normally be reduced closed with recurrence being uncommon. Focus on soft-tissue balance necessary with an MB TKA can reduce the incidence of revision for instability as compared to a fixed-bearing TKA. Therefore, the risk of spinout should not be used as an argument against the MB TKA.

Comparison of hip and knee arthroplasty outcomes at early and intermediate follow-up.

A common perception among clinicians and patients is that recovery is similar following total hip arthroplasty (THA) and total knee arthroplasty (TKA). Improvement in the outcomes of 337 THAs and 256 TKAs implanted by the same surgeon between April 2003 and November 2005 were compared. Improvement was measured using changes in Oxford hip and knee scores measured preoperatively, at first follow-up, and 1 year postoperatively for each patient. Improvements between preoperative review and first follow-up and between preoperative review and 1-year postoperative follow-up were significantly greater for THA compared to TKA patients. Improvements between first postoperative follow-up and 1-year postoperative follow-up were not significantly different between THA and TKA patients. Although THA patients displayed a significantly worse score preoperatively, they displayed a significantly better score at both first follow-up and 1-year postoperative follow-up. While both procedures improve postoperative pain and physical function, as measured by the Oxford score, improvements measured relative to preoperative levels were significantly smaller for TKA compared to THA patients. Despite recent advances in knee arthroplasty surgery, a significant proportion of TKA patients achieve relatively poor outcome scores postoperatively. This study shows that pain and function improve less and more slowly in the early and intermediate postoperative periods for knee compared to hip arthroplasty patients.