Numerous studies have compared metal-backed components (MBTs) and all-polyethylene tibial components (APTs), but none of them specifically analysed the clinical results and the overall patient preference in patients who had undergone a staged bilateral knee replacement. The purpose of this study is to compare clinical results, perceived range of motion, and overall implant preference among patients who had undergone staged bilateral knee replacement with an APT and contralateral knee replacement with MBTs. A dataset of 62 patients from a single centre who underwent staged bilateral TKA between 2009 and 2022 was selected and retrospectively analysed. Tibial component removal was performed in three knees overall, all of which had MBTs. The mean measured Knee Score (KS) of knees with APTs was 78.37 and that of contralateral knees with MBTs was 77.4. The mean measured Function (FS) of knees with APTs was 78.22, and that of contralateral knees with MBs was 76.29. The mean flexion angle of knees with APTs was 103.8 and that for knees with MBTs was 101.04 degrees. A total of 54.8% of the patients preferred the knee that received APTs over contralateral MBTs. In our cohort, TKA with an APT in one knee and an MBT in the contralateral knee recorded similar clinical results and perceived ranges of motion. Patients in general preferred the knee that received an APT over contralateral knee with an MBT.

Limited literature exists on complications specific to the all-polyethylene tibial component in distal femoral replacement (DFR). Unlike in primary arthroplasty with polyethylene components, polyethylene granuloma has not been reported in DFR with an all-polyethylene tibia. Here, we report 2 cases of polyethylene granuloma in patients with primary bone sarcoma who underwent DFR with an all-polyethylene tibia. Radiologically, evidence of intraosseous granuloma formation and periprosthetic osteolysis was observed at the anterior tibial metaphysis. Both patients underwent an operative debridement of polyethylene granuloma and necrotic tissues, followed by a revision to a long-stem, cemented metal-backed tibia with impacted allograft to fill the defect. Polyethylene granuloma should be considered a differential diagnosis in the presence of a periprosthetic lytic lesion after DFR with an all-polyethylene tibial component.

BACKGROUND: All-polyethylene (AP) tibial components have demonstrated equivalent or improved long-term survivorship and reduced cost compared with metal-backed (MB) components in primary total knee arthroplasty; however, there is a lack of data comparing these outcomes in the setting of an oncologic endoprosthetic reconstruction.
METHODS: A total of 115 (88 AP:27 MB) patients undergoing cemented distal femur endoprosthetic reconstruction following oncologic resection were reviewed. Mean age was 40 years and 51% were females. Cumulative incidences of all-cause revision, tibial component revision, reoperation, and infection were calculated utilizing a competing risk analysis with death as the competitor. Mean follow-up was 14 years.
RESULTS: The 10-year cumulative incidence of all-cause revision was 19.9% in the AP group and 16.3% in the MB group (hazard ratio [HR] = 0.93, p = 0.88). The cumulative incidence of tibial component revision was significantly lower in AP compared with MB at 10 years (1.1% vs. 12.5%, HR = 0.18, p = 0.03). There was no difference in infection-free survival when comparing the two groups (p = 0.72).
CONCLUSIONS: Reconstruction utilizing an MB or AP tibia component resulted in equivalent overall outcome; however, the tibial component in the AP group was less likely to be revised. AP tibial component should be considered for all primary oncologic reconstructions in the distal femur. LEVEL OF EVIDENCE: Level III Therapeutic.

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.
We analyzed the medium-term outcome in 1092 patients with an all-polyethylene tibial component in their total knee arthroplasty.
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.
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.

Biomechanical studies have suggested improved stress distribution in metal-backed (MB) compared to all-polyethylene (AP) tibias, but such potential benefits have not been realized clinically. The purpose of this investigation was to analyze the outcomes of AP components in patients with primary osteoarthritis and compare the results to those obtained with MB tibial components in total knee arthroplasty (TKA).
We reviewed 11,653 patients undergoing primary TKA for osteoarthritis. There were 9999 (86%) MB (8470 modular and 1529 monoblock) and 1654 (14%) AP tibial components. All patients had at least 2 years of clinical follow-up with mean follow-up of 8 years (range, 2-30 years).
Mean survivorship for all primary TKAs at the 5-year, 10-year, 15-year, and 20-year time points was 97%, 92%, 86%, and 78%. AP tibial components were found to have improved survivorship when compared to modular and monoblock MB counterparts (P < .0001). Likewise, AP tibial components were found to have lower rates of tibial component loosening (P < .0001), tibial osteolysis, and component fracture. Furthermore, the AP group had improved survival rates in most age-groups except <55 years where there was no difference. AP tibial components demonstrated improved survival for all body mass index (BMI) groups except in patients with a BMI ≤25 kg/m2 where there was no difference.
AP tibial components had significantly improved implant survival across all age-groups and most BMI categories in patients who underwent TKA for osteoarthritis. Given these outcomes, AP tibias are a reasonable option, regardless of patient age and BMI.