Sequentially Irradiated and Annealed Highly Cross-Linked Polyethylene: Clinical and Radiographic Outcomes in Total Knee Arthroplasty at 10-Year Follow-up.

Highly cross-linked polyethylene (HXLPE) has become the preferred bearing surface in total hip arthroplasty. However, its acceptance in total knee arthroplasty (TKA) has not been as robust because of concerns pertaining to wear and its impact on implant failure. Therefore, this multicenter study was purposed to evaluate the 10-year (1) radiographic outcomes; (2) complications; and (3) implant survivorship in patients with TKA receiving a sequentially irradiated and annealed HXLPE. A retrospective, multi-center study was performed on 139 patients (171 TKAs) who underwent primary TKA with HXLPE and possessed a minimum of 10-year follow-up. Radiographs were analyzed for radiolucencies along the implant-fixation interface using the Modern Knee Society Radiographic Evaluation System. Kaplan-Meier analysis determined implant survivorship when the end points were revision for polyethylene wear and polyethylene revision for any reason. Sixteen TKAs (9.9%) demonstrated periprosthetic linear radio-lucencies. Seventeen TKAs (9.9%) required additional surgeries, 9 (5.3%) of which were revisions, with 1 (0.6%) TKA requiring revision because of polyethylene wear. Other causes of revision included instability (1.8%), infection (1.6%), and arthrofibrosis (1.6%). The mean time to revision was 5.9 years (range, 0.1-11.1 years). Survivorship pertaining to polyethylene revision for wear was 99.4%, whereas all-cause polyethylene revision was 94.7%. This study in patients undergoing primary TKA using a second-generation HXLPE demonstrated excellent results with respect to polyethylene wear characteristics and strength with a 99.4% survivorship at 10 years. [Orthopedics. 2023;46(2):e111-e117.].

Sequentially Irradiated and Annealed Highly Cross-Linked Polyethylene: Linear Vector and Volumetric Wear in Total Hip Arthroplasty at 10 Years.

BACKGROUND: There is a paucity of data on the long-term performance of highly cross-linked polyethylene (HXLPE). Therefore, this study evaluated 10-year 1) functional, 2) radiographic, and 3) surgical outcomes in patients who underwent total hip arthroplasty with sequentially irradiated and annealed HXLPE. METHODS: A retrospective, multicenter study was conducted on patients who underwent primary total hip arthroplasty and received HXLPE polymer (n = 151). Two-dimensional radiographic linear and volumetric wear analyses were quantified using the Martell Hip Analysis software, while functional outcomes were assessed by analyzing postoperative Short-Form-12 (SF-12) Physical and Mental Health Surveys and Harris Hip Scores. Radiographic outcomes included yearly linear (mm/y) and volumetric (mm3/y) wear rates. Surgical outcomes included additional operations and survivorship. RESULTS: SF-12 scores were within 1 standard deviation (SD) of the normal population (SF-12 Physical: 47.0; SF-12 Mental: 52.0), while the Harris Hip Scores of 89.5 was borderline between "good" and "excellent." Total and annual linear wear rates were 0.164 mm (SD: 0.199 mm) and 0.015 mm/y (SD: 0.018 mm/y), respectively. The mean total volumetric wear rate was 141.4 mm3 (SD: 165.0) and 12.6 mm3/y (SD: 14.9 mm3/y) when broken down into a yearly rate. Eleven patients required revisions, resulting in an all-cause polyethylene survivorship of 92.7%, with a polyethylene wear survivorship of 100.0%. CONCLUSIONS: Our results demonstrate clinically undetectable linear and volumetric wear rates after 10 years in those who received the unique sequentially irradiated and annealed HXLPE. Furthermore, high rates of survivorship coupled with low all-cause revision rates illustrate the polymers' capability to potentially increase implant longevity.

Mid-Term Follow Up of Newer-Generation Morphometric Wedge Stems for Total Hip Arthroplasty (THA).

INTRODUCTION: Proximally coated, morphometric wedge femoral stems illustrated excellent survivorship and clinical outcomes at a minimum five-year postoperative follow up. MATERIALS AND METHODS: We completed a retrospective review of 186 THA patients from three high-volume surgeons to assess clinical- and patient-reported outcomes five years after implantation with a cementless, proximally coated morphometric wedge femoral stem. We reviewed Gruen zones on early postoperative and mid-term radiographs for signs of osteolysis, loosening, and wear. Clinical- and patient-reported outcomes were compared with previously published two-year outcomes for these femoral stems. RESULTS: No progression of radiolucencies or loosening was observed radiographically when comparing minimum one-year and five-year follow up. Reactive radiodense lines were observed in 23 cases (12.64%), and 13 cases (7.14%) exhibited true radiolucencies of 1-3mm, and all remained unchanged between follow ups or were no longer present on the five-year film. Cortical hypertrophy was noted in Gruen zones 3 and/or 5 in 11 cases (6.04%). No stems were revised for mechanical loosening or for periprosthetic fracture. Nine (9) patients (4.87%) underwent revisions during the follow-up period for periprosthetic infection, femoral head and/or acetabular component revisions, and impingement requiring release and femoral head change. Average Harris Hip Scores were excellent at five years and improved slightly when compared to a two-year follow up; however, this change was not statistically significant. Health-related quality of life mental component and physical component scores were a mean of 48.45 and 43.10 at 5 years, respectively. All cause Kaplan-Meier survivorship of the femoral stem was calculated at 98.4% at an average 65.7 months post implantation. Additionally, this cohort exhibited 100% aseptic survivorship during the follow-up period. CONCLUSION: Newer-generation morphometric wedge femoral stems for THA exhibit excellent radiographic stability, patient satisfaction, and clinical outcomes five years post implantation.

A Comparison Study of Two Cruciate-Retaining Total Knee Designs: A Preliminary Report.

Cruciate-retaining total knee arthroplasties have had high success rates. The purpose of this study was to compare a newer cruciate-retaining design to a previously used implant to determine if there were any changes in clinical or functional outcome. A total of 461 patients (553 knees) were identified who had total knee arthroplasty with this newer design. At latest 2-year follow-up, the mean range of motion was 121 degrees (range 105 to 140 degrees), the mean Knee Society pain score was 91 points (range, 57 to 100 points) and the functional score was 76 points (45 to 100 points). The comparison group of 211 patients (225 knees) had a mean range of motion of 119 degrees at 2 years (range, 90 to 142 degrees) with Knee Society pain and functional scores of 95 and 85 points, respectively (ranges 57 to 100, and 0 to 100, respectively). The use of the newer cruciate-retaining total knee arthroplasty showed comparable results to the previously used design at short-term follow-up. The cruciate-retaining design used in this study had no early failures, though further study is needed to make assessments regarding longer-term functional results and outcomes.