Minimally Invasive Inlay Prosthesis Unicompartmental Knee Arthroplasty for the Treatment of Unicompartmental Osteoarthritis: A Prospective Observational Cohort Study with Minimum 2-Year Outcomes and up to 14-Year Survival.

There are limited medium-term outcome data available for the Repicci II device in unicompartmental knee arthroplasty (UKA). The purpose of this study was to report the medium-term (minimum 2 years) patient-reported outcomes and long-term (up to 14 years) procedure survival in a consecutive series of patients undergoing an inlay prosthesis UKA (Repicci II) at an independent orthopaedic clinic. Patients presenting with medially localized unicompartmental knee osteoarthritis and meeting the criteria appropriate for UKA were recruited to a clinical patient registry at the time of presentation. A cemented unicompartmental prosthesis (Repicci II) was implanted using minimally invasive techniques with rapid postoperative mobilization. Patients were asked to complete patient-reported outcomes preoperatively and annually postoperatively. A procedure list was cross-matched with the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), and an analysis of procedure survival was performed with comparison to the national data for UKA. Data from a cohort of 661 primary medial compartment UKA procedures performed in 551 patients over a 15-year period were extracted from the clinical patient registry. Significant improvements were maintained in general health, disease symptoms, pain, and function at an average follow-up of 9 years compared with preoperative data. Threshold analysis revealed that >65% of patients exceeded Patient Acceptable Symptom State at the latest follow-up, with >80% within or exceeding age-matched norms for general health. Cumulative revision rate was significantly lower than that reported for UKA in the AOANJRR at up to 13 years follow-up. This series represents a lower cumulative revision rate than previously reported, with >65% of patients reporting satisfactory functional outcomes at an average of 9 years from surgery. Surgical options for treating unicompartmental knee osteoarthritis could include UKA as a viable alternative; however, clear definitions of procedure success and its overall cost-benefit ratio in the context of ongoing management of knee osteoarthritis remain to be elucidated.

Multimodal thromboprophylaxis in low-risk patients undergoing lower limb arthroplasty: A retrospective observational cohort analysis of 1400 patients with ultrasound screening.

PURPOSE: This study reports the results of a multimodal thromboprophylaxis protocol for lower limb arthroplasty involving risk stratification, intraoperative calf compression, aspirin prophylaxis and early (within 4 h) post-operative mobilisation facilitated by the use of local infiltration analgesia. The study also aimed to identify risk factors for venous thromboembolism (VTE) within a 3-month period following surgery for patients deemed not at elevated risk. METHODS: Patients undergoing knee/hip arthroplasty or hip resurfacing were preoperatively screened for VTE risk factors, and those at standard risk were placed on a thromboprophylaxis protocol consisting of intraoperative intermittent calf compression during surgery, 300 mg/day aspirin for 6 weeks from surgery and early mobilisation. Patients were screened bilaterally for deep vein thrombosis (DVT) on post-operative days 10-14. If proximal DVT was detected, patients were anticoagulated and outcomes were recorded. Symptomatic VTE within 3 months of surgery were recorded separately. Patient notes were retrospectively collated and cross-validated against ultrasound reports. RESULTS: At initial screening, the rate of proximal DVT was 0.54% (1.1% for knee and 0.27% for hip), and distal DVT was 6.63% (20.11% for knee and 2.31% for hip). One small, nonfatal pulmonary embolism (PE) was detected within 3 months of surgery (0.28% of total knee arthroplasty patients or 0.07% of total). All proximal DVTs were treated successfully with anticoagulants; however, one patient suffered a minor PE approximately 10 months post-operatively. Regression analysis identified knee implant and advanced age as independent risk factors for VTE in this cohort. CONCLUSION: Although knee arthroplasty patients remained at higher risk than hip replacement/resurfacing patients, the incidence and outcomes of VTE remained positive compared with protocols involving extended immobilisation, and episodes of PE were extremely rare. Thus, we conclude that patients at standard preoperative risk of VTE may safely be taken through the post-operative recovery process with a combination of intraoperative mechanical prophylaxis, early mobilisation and post-operative aspirin, with closer attention required for older patients and those undergoing knee surgery.

Limited penetration of cobalt and chromium ions into the cerebrospinal fluid following metal on metal arthroplasty: a cross-sectional analysis.

Background: The purpose of this study was to determine the concentration of cobalt (Co) and chromium (Cr) ions in synovial fluid, blood plasma and cerebrospinal fluid (CSF) of patients with metal-on-metal (MoM) implants, and to assess the relationship between implant history and patient characteristics with ion concentrations in CSF.Methods: An observational, non-randomised cross-sectional study was conducted with patients presenting to a single surgeon for treatment of degenerative conditions of the hip and knee. Blood and fluid samples were collected intraoperatively and analysed for proteins and trace elements.Results: Overall, the presence of an implant was associated with significantly higher Co and Cr concentrations in plasma (controls 5-115 nmol/L Co, 5-232 nmol/L Cr; well-functioning implant recipients 5-469 nmol/L Co, 5-608 nmol/L Cr; hip revisions 6-546 nmol/L Co, 5-573 nmol/L Cr), and for Cr concentrations in CSF (controls 5-24 nmol/L; well-functioning implant recipients 6-36 nmol/L, hip revisions 7-32 nmol/L). In absolute terms, <1% of the levels observed in the joint fluid and <15% of plasma metals appeared in the CSF. Multivariable regression models suggested different transfer mechanisms of Co and Cr to the CSF, with the presence of an implant not associated with ion levels.Conclusion: The presence of MoM implants is associated with significantly higher plasma levels of Co and Cr but not CSF levels, and the CSF/plasma ratio appears to be influenced by the plasma concentration in a nonlinear fashion. Co and Cr may be transferred to the CSF by different mechanisms, and their concentrations appears dependent on other factors yet to be identified. Although higher levels of plasma ions are associated with above average CSF metal concentrations, the thresholds for neurotoxicity remain unclear and require further study.