Tibial polyethylene post fractures at ten-years in a bicruciate stabilised (BCS) total knee arthroplasty design.

INTRODUCTION: This short paper reports a potential emerging mode of failure in three patients with a bicruciate stabilised (BCS) total knee arthroplasty. METHODS: Three patients presented to our institution with late instability ten years after undergoing total knee arthroplasty (Journey BCS) and were asymptomatic up to this point. Retrieval analysis was performed by an external body commissioned by the NHS and all three cases were reported to the UK Medicines and Healthcare Products Regulatory Agency (MHRA). RESULTS: Two patients were revised through simple exchange with a polyethylene tibial insert. One patient underwent a full revision of femoral and tibial components. Intra-operative findings revealed that the polyethylene post had fractured in an identical manner in all three cases. Retrieval analysis demonstrated posterior impingement and wear of the polyethylene post resulting in fatigue failure. CONCLUSIONS: This short paper highlights a potential emerging mode of failure with Journey BCS that requires wider dissemination to raise awareness among surgeons and calls for long-term follow up of those patients who received this specific implant. Early revision with polyethylene exchange is a successful treatment in patients when femoral and tibial components are well-positioned and well-fixed.

The Journey Bicruciate Knee Replacement: Design Modifications Yield Better Early Functional Results and Reduce Complications.

The Journey-I total knee replacement was designed to improve knee kinematics but had several complications including early dislocation. The Journey-II modification was introduced to reduce these while maintaining high function. To assess whether the modified Journey-II prosthesis has succeeded in its designers aims, we undertook an observational study of prospectively recorded data to analyze and compare the two knees. A total of 217 Journey-I and 129 Journey-II knees were identified from the department's prospectively collated registry and were assessed at 1 year by a comparative statistical analysis using numerous factors including pain, functional activity, physical assessment, Short Form-12 (SF-12), Western Ontario and McMaster Universities Arthritis Index (WOMAC), and Oxford scores. The statistical tests included Chi-square, Wilcoxon's rank and Mann-Whitney U-tests with the level of significance set at p < 0.05. There was a variation in primary patella resurfacing between the two groups with 14.3% in the Journey-I cohort and 66.7% in the Journey-II cohort. Both replacements demonstrated excellent postoperative function, but the Journey II performed significantly better than Journey I with fewer complications (37 vs. 10) and better improvement in almost all clinical scores including pain (p < 0.01), mobility outcomes (p = 0.018), Oxford (p = 0.004), and WOMAC (p = 0.039) scores but not with flexion improvement and SF-12 score. There was significant improvement in patellofemoral pain postoperatively in both the Journey I (p = 0.011) and Journey II (p = 0.042) arthroplasty; however the primarily resurfaced patella in a Journey-II implant had better postoperative scores. The main complication of dislocation in the Journey I was not seen in the modified Journey-II implant with stiffness requiring intervention reduced in Journey II. These results suggest that the Journey II has improved short-term clinical outcomes compared with Journey I with reduction of dislocation and other complications.

The Medium-Term Survival Analysis of an All-Polyethylene Tibia in a Single-Series Cohort of Over 1000 Knees.

BACKGROUND: Total knee arthroplasty is a successful elective orthopedic procedure with an increasing number being undertaken. Original knee arthroplasties used an all-polyethylene tibia; however, with concerns over tibial loosening, the trend moved toward the metal-backed variety. Modern designs providing more conformity and changes in manufacturing of the polyethylene make it an equivalent but cheaper option. METHODS: We analyzed the medium-term outcome in 1092 patients with an all-polyethylene tibial component in their total knee arthroplasty. RESULTS: Twenty-six patients had further surgery on their knee for a variety of reasons. Assessing reoperation for any reason, the 7-year survival rate was 96.96% with an overall infection rate of 0.37%. Seven-year survival analysis using aseptic loosening as a criteria was 99.28%. Both the Short Form 12 physical score and Western Ontario and McMaster Universities Osteoarthritis Index score significantly improved and was sustained at 7 years. Body mass did not correlate to either outcomes or complications. CONCLUSION: An all-polyethylene tibia in a total knee arthroplasty has good outcome data and high patient satisfaction with good survivorship in the medium term, coupled with potential cost-saving benefits.

Mid- to long-term survivorship of oxidised zirconium total knee replacements performed in patients under 50years of age.

BACKGROUND: Oxidised zirconium has the wear properties of ceramic with the breakage resistance of metal. This results in less wear and is of benefit to younger, higher demand patients. We report the short- to mid-term survival of 103 Profix zirconium total knee replacements performed in patients under 50years of age at time of surgery. METHODS: Data was collected prospectively and survival analysis undertaken with strict end points used. SF (Short Form) 12 and WOMAC (Western Ontario and McMaster University) scores were recorded at pre-operatively and at twelve months, one, three, five, seven and ten years. RESULTS: The average age at operation was 43.21years (range 20-50years) with a mean follow-up of 8.56years (range five to 15years). No patients died with one patient lost to follow-up after seven year review. The mean WOMAC score improved from 53 to 29, and the mean SF12 physical component improved from 29 to 36. The five year survivorship for implant related complications was 99.03% (95% CI 94.64-100.0) due to tibial component aseptic loosening at year one. Reoperation for any cause at five years including stiffness was 94.09% (95% CI 88.69-98.11). Forty-four patients were at least ten years post-operative at the time of analysis, with no aseptic loosening of either component giving 10year femoral component survival of 100% and all cause revision of 95.4%. The only zirconium femoral failure was at 12years. CONCLUSIONS: Our data shows excellent mid-term survivorship of oxidised zirconium total knee replacements in younger, higher demand patients.

Five year survival analysis of an oxidised zirconium total knee arthroplasty.

BACKGROUND: Zirconium total knee arthroplasties theoretically have a low incidence of failure as they are low friction, hard wearing and hypoallergenic. We report the five year survival of 213 Profix zirconium total knee arthroplasties with a conforming all polyethylene tibial component. METHODS: Data was collected prospectively and multiple strict end points were used. SF12 and WOMAC scores were recorded pre-operatively, at three months, at twelve months, at 3 years and at 5 years. RESULTS: Eight patients died and six were "lost to follow-up". The remaining 199 knees were followed up for five years. The mean WOMAC score improved from 56 to 35 and the mean SF12 physical component score improved from 28 to 34. The five year survival for failure due to implant related reasons was 99.5% (95% CI 97.4-100). This was due to one tibial component becoming loose aseptically in year zero. CONCLUSIONS: Our results demonstrate that the Profix zirconium total knee arthroplasty has a low medium term failure rate comparable to the best implants. Further research is needed to establish if the beneficial properties of zirconium improve long term implant survival.

Ten-year survival analysis of the PFC total knee arthroplasty--a surgeon's first 99 replacements.

Ninety-seven patients with 99 total knee arthroplasties were operated on by a surgeon in the first 3 years of his surgical career. Complete survival data were available for all 99 knees. The cases were reviewed at a minimum of 10 years after their initial operation, but as 37 patients had died before reaching 10 years, the average follow-up was 8 years 8 months with a maximum of 12 years 4 months. Ninety-one patients had osteoarthritis, five had rheumatoid arthritis, and three had juvenile chronic arthritis. No patients were lost to follow-up. Four required revision. The 10-year survival rate, using revision for all causes as an end-point, was 94.96%. The survival rate for aseptic loosening was 97.04%. The survival rate for loose joints that had not been revised was 94.13%. Three of the four revisions occurred in the first 6 patients operated upon, suggesting there may be a learning curve for surgeons at this stage in their career.