Comparison of 5-year cup and stem migration between ceramic-on-ceramic and ceramic-on-polyethylene bearing in press-fit total hip arthroplasty: a randomised controlled trial using radiostereometric analysis.

INTRODUCTION: The inelasticity of ceramic bearings might affect primary stability and migration of implants in press-fit total hip arthroplasty (THA). This randomised controlled trial compares migration patterns of the uncemented Delta-TT cup and H-MAX S stem between ceramic and polyethylene liners, up to 5 years follow-up. METHODS: Patients receiving primary press-fit THA were randomly allocated to a ceramic (n = 28) or polyethylene (n = 25) liner. Migration was measured using model-based radiostereometric analysis (RSA) at baseline and 1.5, 3, 6, 12, 24 and 60 months postoperatively and compared between groups using mixed models statistical analysis. The focus of this study is on the 2- to 5-year migration of the Delta-TT cup and migration during complete follow-up of the H-MAX S stem up to 5-years. RESULTS: At 5-year follow-up, mean (95% CI) proximal cup translation was 0.56 (0.37-0.74) mm in ceramic and 0.58 (0.25-0.90) mm in polyethylene (p = 0.729). The mean change in adduction was 1.05° (0.27-1.82°) in ceramic and 0.78° (-0.16-1.71°) in polyethylene. Mixed modelling showed that all between-group effects were ⩽0.20 mm for translation and ⩽0.22° for rotation at 5 years postoperatively (p ⩾ 0.23). Mean cup migration between 2 and 5 years was limited (all parameters <0.17 mm and <0.30°). At 5-year follow-up, mean stem subsidence was 2.09 mm (0.89-3.29 mm) in ceramic and 2.55 (0.97-4.12) mm in polyethylene. The mean change in internal rotation was 3.69° (1.98-5.40°) in ceramic and 4.01° (2.20-5.81°) in polyethylene. Most stem migration occurred up to 1.5 months, stabilising afterwards. All between-group effects were ⩽0.75 mm for translations and ⩽1.41° for rotations (p ⩾ 0.26). CONCLUSIONS: 5-year migration patterns of press-fit cups and stems were similar between ceramic and polyethylene liners. The Delta-TT cup and H-MAX S stem showed secondary stabilisation and remained stable up to 5 years in both groups, which is promising for long-term survival with both liner types. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov (NCT03093038).

Mid-term clinical outcomes of the uncemented Robert Mathys pressfit cup.

BACKGROUND: The use of uncemented cups during total hip arthroplasty (THA) has gained popularity in recent years. The Robert Mathys (RM) pressfit cup, an uncemented monoblock implant is expected to preserve bone density due to its composition and external surface, while reducing backside wear with its monoblock construction. These factors should lead to a high survival rate of the implant. AIM: To evaluate the mid-term survival and functional outcome of the RM Pressfit cup in a large study population. METHODS: Between 2011 and 2020, we included 1324 patients receiving a primary THA using the RM pressfit cup. Final clinical follow-up was performed at 2 years postoperatively with the Dutch arthroplasty register used to assess implant status thereafter. Revision for acetabular failure and reason for revision were reported to evaluate implant survival, while the hip disability and osteoarthritis outcome score (HOOS) scores were used to assess functional outcome. RESULTS: The mean age at surgery was 64.9 years. The mean follow-up was 4.6 years. Of the 1324 THAs performed, 13 needed cup revisions within 5 years after index THA: 5 due to aseptic loosening, 6 due to infection, 2 due to dislocation and 2 due to other causes. This resulted in a 5-year cup survival of 98.8% (95%CI: 98.1-99.5). Nine of the cup revisions occurred within the first year after index THA. HOOS scores increased significantly in all domains during the first year and levelled out during the second year. CONCLUSION: In the present study, the RM pressfit cup demonstrated excellent clinical outcomes at mid-term follow-up; however, future studies are needed to assess the long-term outcomes of this acetabular implant.

Analyzing Learning Curve Effects: Total Ankle Replacement Design Switch and Long-Term Survival.

Different aspects of the learning curve in total ankle replacement (TAR) have been studied in the short to mid-term, with 30 cases often considered critical. However, its impact on long-term (10- and 15-year) survival remains unclear. Therefore, we retrospectively analyzed 77 consecutive TARs performed by one orthopedic surgeon. The main outcome was long-term survival between cases 1-30 and 31-77 using the Kaplan-Meier with Competing Risk Analyses. Secondarily, we used Moving Average Method with LOESS regression to confirm the learning curve based on the perioperative complications. Thirdly, associations between perioperative complications and operation time on long-term survival were assessed using Cox proportional hazard models. The 10-year survival of cases 1-30 was 89.9% (95% CI 70.4-96.5), and of 31-77, 92.4% (95% CI 7745- 97.5) (p = .58). The 15-year survival was 81.8% (95% CI 59.5-91.8) and 74.8% (95% CI 52.4-86.6), respectively (p = .97). The long-term survival rate for the TAR that endured perioperative complication was 96.70% (95% CI 90.28-103.12), and for the uncomplicated TAR 87.50% (95% CI 77.12-97.88%) (p = .24). Operating time nor occurrence of perioperative fractures were significantly associated with long-term survival (p = .11 and 0.26, respectively). However, moving average method revealed a significant decreasing trend with a cut-off value of 33 procedures regarding the marginal probability of perioperative osseous complications (p < .01). In conclusion, surgeons should note a learning curve when adapting arthroplasty procedures. After the prosthesis design switch, the learning curve regarding perioperative osseous complications was confirmed at 33 TAR. The switch did not affect long-term survival.

The minimal important change is not a universal fixed value across diagnoses when using the FAOS and FAAM in patients undergoing elective foot and ankle surgery.

PURPOSE: This study aimed to calculate region and diagnosis-specific minimal important changes (MICs) of the Foot and Ankle Outcome Score (FAOS) and the Foot and Ankle Ability Measure (FAAM) in patients requiring foot and ankle surgery and to assess their variability across different foot and ankle diagnoses. METHODS: The study used routinely collected data from patients undergoing elective foot and ankle surgery. Patients had been invited to complete the FAOS and FAAM preoperatively and at 3-6 months after surgery, along with two anchor questions encompassing change in pain and daily function. Patients were categorised according to region of pathology and subsequent diagnoses. MICs were calculated using predictive modelling (MICPRED) and receiver operating characteristic curve (MICROC) method and evaluated according to strict credibility criteria. RESULTS: Substantial variability of the MICs between forefoot and ankle/hindfoot region was observed, as well as among specific foot and ankle diagnoses, with MICPRED and MICROC values ranging from 7.8 to 25.5 points and 9.4 to 27.8, respectively. Despite differences between MICROC and MICPRED estimates, both calculation methods exhibited largely consistent patterns of variation across subgroups, with forefoot conditions systematically showing smaller MICs than ankle/hindfoot conditions. Most MICs demonstrated high credibility; however, the majority of the MICs for the FAOS symptoms subscale and forefoot conditions exhibited insufficient or low credibility. CONCLUSION: The MICs of the FAOS and FAAM vary across foot and ankle diagnoses in patients undergoing elective foot and ankle surgery and should not be used as a universal fixed value, but recognised as contextual parameters. This can help clinicians and researchers in more accurate interpretation of the FAOS and FAAM change scores. LEVEL OF EVIDENCE: Level IV.

Mid-term survival of the Optimys short stem: A prospective case series of 500 patients.

BACKGROUND: In recent years, there has been an increase in the number of total hip arthroplasty procedures in the younger patient population. This active group has higher expectations of their prosthesis in comparison to the older population, and there is a greater physical demand for the prosthesis. Short femoral stems were introduced to retain proximal bone stock and joint biomechanics and became more common to implant in this specific population. Currently, the long-term survival and functional outcomes of various short stems are still being investigated in different clinics. AIM: To determine the 5-year survival of the Optimys hip stem. METHODS: This was a prospective multicenter cohort study of 500 patients conducted in two hospitals in the Netherlands. All patients received the Optimys short stem (Mathys Ltd, Bettlach, Switzerland). The primary outcome measure was survival of the hip stem, with revision as the endpoint. The secondary outcome measurements included patient-reported outcome measures (PROMs). Kaplan-Meier analysis was used to calculate the 5-year survival rate. Log-minus-log transformation was performed to calculate the 95% confidence interval (95%CI). Mixed model analyses were performed to assess the course of the PROMs during the 1st 2 years after surgery. Analyses were modeled separately for the 1st and 2nd years to calculate the yearly change in PROMs during both follow-up periods with accompanying 95%CIs. RESULTS: The mean age of the total 500 patients was 62.3 years (standard deviation: 10.6) and 202 were male (40%). At a median follow-up of 5.5 years (interquartile range: 4.5-6.7), 7 patients were deceased and 6 revisions were registered, for infection (n = 3), subsidence (n = 2) and malposition (n = 1). This resulted in an overall 5-year survival of 98.8% (95%CI: 97.3-99.5). If infection was left out as reason for revision, a stem survival of 99.4% (95%CI: 98.1-99.8) was seen. Baseline questionnaires were completed by 471 patients (94%), 317 patients (63%) completed the 1-year follow-up questionnaires and 233 patients (47%) completed the 2-year follow-up. Both outcome measures significantly improved across all domains in the 1st year after the operation (P < 0.03 for all domains). In the 2nd year after surgery, no significant changes were observed in any domain in comparison to the 1-year follow-up. CONCLUSION: The Optimys stem has a 5-year survival of 98.8%. Patient-reported outcome measures increased significantly in the 1st postoperative year with stabilization at the 2-year follow-up.

Outcomes of Total Ankle Replacement with Preoperative Varus Deformity.

Historically, coronal plane deformities of greater than 10° to 15° have been deemed contraindications for total ankle replacement (TAR). However, recent studies show satisfactory results in TAR with severe preoperative varus deformity. When correctly applying ancillary procedures, preoperative varus deformity can be structurally corrected, resulting in similar clinical scores to those obtained with "regular TAR." However, complications and revisions appear to increase with increasing deformity. Unfortunately, results of TAR in varus ankles consist of heterogeneous data (eg, with regards to prosthetic brands, bearing-types, duration of follow-up, and ancillary procedures) precluding strict conclusions. This could be solved by an international consensus group.