Implementation of outpatient hip and knee arthroplasty in a multicenter public healthcare setting.

BACKGROUND AND PURPOSE: Length of hospital stay after hip and knee arthroplasty is about 1 day in Denmark with few patients discharged on the day of surgery. Hence, a protocol for multicenter implementation of discharge on day of surgery has been instituted. We aimed to describe the implementation of outpatient hip and knee arthroplasty in a multicenter public healthcare setting. METHODS: We performed a prospective multicenter study from 7 public hospitals across Denmark. Patients were screened using well-defined in- and exclusion criteria and were discharged on day of surgery when fulfilling functional discharge criteria. The study period was from September 2022 to February 2023 with variable start of implementation. Data from the same centers in a 6-month period before the COVID pandemic from July 2019 to December 2019 was used for baseline control. RESULTS: Of 2,756 primary hip and knee arthroplasties, 37% (95% confidence interval [CI] 35-39) were eligible (range 21-50% in centers) and 52% (range 24-62%) of these were discharged on day of surgery. 21% (CI 20-23) of all patients (eligible and non-eligible) were discharged on day of surgery with a range of 10-31% within centers. This was an additional 15% (CI 13-17, P < 0.001) compared with patients discharged in the control period (6% in 2019). CONCLUSION: We found it possible to perform outpatient hip and knee replacement in 21% of patients in a public healthcare setting, probably to be increased with further center experience.

Protocol for a prospective multicentre cohort study to address the question whether diabetes and its management is still a risk factor in fast-track joint arthroplasty.

INTRODUCTION: Perioperative glycaemic control is important. However, the complexity of guidelines for perioperative diabetes management is complicated due to different and novel antihyperglycaemic medications, limited procedure-specific data and lack of data from implemented fast-track regimens which otherwise are known to reduce morbidity and glucose homeostasis disturbances. Consequently, outcome in patients with diabetes mellitus (DM) after surgery and the influence of perioperative diabetes management on postoperative recovery remains poorly understood. METHODS AND ANALYSIS: A prospective observational multicentre study involving 8 arthroplasty centres across Denmark with a documented implemented fast-track programme (median length of hospitalisation (LOS) 1 day). We will collect detailed perioperative data including preoperative haemoglobin A1c and antidiabetic treatment in 1400 unselected consecutive patients with DM undergoing hip and knee arthroplasty from September 2022 to December 2025, enrolled after consent. Follow-up duration is 90 days after surgery. The primary outcome is the proportion of patients with DM with LOS >4 days and 90-day readmission rate after fast-track total hip arthroplasty (THA), total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA). The secondary outcome is the association between perioperative diabetes treatment and LOS >2 days, 90-day readmission rate, other patient demographics and Comprehensive Complication Index for patients with DM after THA/TKA/UKA in a fast-track regimen. ETHICS AND DISSEMINATION: The study will follow the principles of the Declaration of Helsinki and ICH-Good Clinical Practice guideline. Ethical approval was not necessary as this is a non-interventional observational study on current practice. The trial is registered in the Region of Southern Denmark and on ClinicalTrials.gov. The main results and all substudies of this trial will be published in peer-reviewed international medical journals. TRIAL REGISTRATION NUMBER: NCT05613439.

"Pain without loosening"-revisions of knee arthroplasties in the Danish Knee Arthroplasty Register.

INTRODUCTION: We aimed to investigate "pain without loosening" as an indication for knee arthroplasty revisions and to screen for other indications potentially hidden in this category to improve future registration and enhance data quality in the Danish Knee Arthroplasty Register. METHODS: We included 104 patients undergoing revision knee arthroplasty for the indication "pain without loosening" from 1 January 2016 to 31 December 2018 at five Danish centres. Medical records, radiographs and computed tomographies were reviewed. RESULTS: In 103 of 104 cases, we confirmed "pain without loosening" as an indication for revision. We found hidden indications in 44 cases; malposition of components (n = 19), stiffness (n = 13), progression of arthrosis (n = 6), instability (n = 3), liner dislocation (n = 1), residual cement (n = 1) and aseptic loosening (n = 1). The Kellgren-Lawrence arthrosis grades prior to primary knee arthroplasty were 1-2 (31%) and 3-4 (69%). CONCLUSIONS: The indication "pain without loosening" covered patients revised due to pain, but other hidden indications were also present. Stiffness and malposition of components were hidden indications and these are not provided as indication options in the DKR and other registers. The relatively high frequency of arthrosis grade 1-2 prior to primary knee arthroplasty is concerning and may explain the occurrence of knee pain without any other pathology present. FUNDING: The Danish Rheumatism Association, the Region of Southern Denmark, the Research Fund of Region Zeeland and Region of Southern Denmark, and the University of Southern Denmark. TRIAL REGISTRATION: Not relevant.

Tibial Component Undersizing Is Related to High Degrees of Implant Migration Following Cementless Total Knee Arthroplasty: A Study of Radiostereometric Analysis Data for 111 Patients with 2-Year Follow-up.

Radiostereometric analysis (RSA) studies have shown that the continuous migration of tibial components is predictive of aseptic loosening following total knee arthroplasty (TKA). In the present study, we investigated whether accurate sizing and placement of tibial components are related to the degree of implant migration as measured with use of RSA. Methods: A total of 111 patients who underwent TKA surgery with a cementless tibial component were followed for a period of 2 years postoperatively, during which implant migration was assessed with use of RSA. RSA was performed within 7 days postoperatively and after 3, 6, 12, and 24 months. Postoperative radiographs were evaluated for component size and placement in the tibia. The evaluations were performed by experienced knee surgeons who were blinded to the migration data and clinical outcomes. A multivariable linear regression analysis was conducted. Results: Continuous implant migration (i.e., migration occurring between 12 and 24 months postoperatively) had a negative association with tibial component size (coefficient [B], -0.2; 95% confidence interval [CI], -0.33 to -0.08). Subsidence was associated with the absence of posterior cortical bone support (B, -0.7; 95% CI, -1.09 to -0.28), the absence of lateral cortical bone support (B, 0.8; 95% CI, 0.29 to 1.37), frontal-plane varus malalignment (B, 0.6; 95% CI, 0.12 to 1.16), and component undersizing (B, -0.4; 95% CI, -0.06 to -0.68). Posterior tilt was associated only with undersizing (B, 0.6; 95% CI, 0.27 to 1.11). Conclusions: Undersized cementless tibial components are at a higher risk for poor fixation with continuous migration following TKA. Therefore, a higher risk of aseptic loosening should be expected. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Study protocol for discharge on day of surgery after hip and knee arthroplasty from the Center for Fast-track Hip and Knee Replacement.

BACKGROUND AND PURPOSE: Limited data exists on the implementation process and safety of discharge on the day of surgery after primary hip and knee arthroplasty in a multicenter setting. We report our study protocol on the investigation of the feasibility, safety, and socioeconomic aspects following discharge on day of surgery after hip and knee arthroplasty across 8 fast-track centers. PATIENTS AND METHODS: This is a study protocol for a prospective cohort study on discharge on day of surgery from the Center for Fast-track Hip and Knee Replacement. The collaboration includes 8 centers covering 40% of the primary hip and knee arthroplasty procedures undertaken in Denmark. All patients scheduled for surgery are screened for eligibility using well-defined inclusion and exclusion criteria. Eligible patients fulfilling discharge criteria will be discharged on day of surgery. We expect to screen 9,000 patients annually. Duration and outcome: Patients will be enrolled over a 3-year period from September 2022 and reporting of results will run continuously until December 2025. We shall report the proportion of eligible patients and patients discharged on day of surgery as well as limiting factors. Readmissions and complications within 30 days are recorded with real-time follow-up by research staff. Furthermore, patient-reported information on willingness to repeat discharge on day of surgery, contacts with the healthcare system, complications, and workability is registered 30 days postoperatively. EQ-5D, Oxford Knee Score, and Oxford Hip Score are completed preoperatively and after 3 months and 1 year. Finally, outcome data will be used in the development of a prediction model for successful discharge on the day of surgery.

Bone Remodeling of the Distal Femur After Uncemented Total Knee Arthroplasty-A 2-Year Prospective DXA Study.

Loss of bone stock as a response to the bone trauma, immobilization, and stress shielding related to joint replacement surgery increases the risk of fracture of the distal femur after total knee arthroplasty. Previous studies of uncemented femoral components have reported very high levels of bone loss in the distal femur. This study investigates the adaptive bone remodeling of the distal femur after uncemented total knee arthroplasty. We performed a 2-year follow-up of 53 patients (mean age 61.5 [38-70] years, F/M = 27/26, body mass index 29.5) who because of osteoarthritis received an uncemented total knee arthroplasty. All patients received a NexGen CR-Flex Porous Femoral Component. Measurements of bone mineral density of the distal femur using dual-energy X-ray absorptiometry were performed postoperatively and after 3, 6, 12, and 24 months. Bone mineral density (g/cm2) was measured in 3 regions of interest in the periprosthetic bone of the distal femur. Repeated measures analysis of variance and Tukey post hoc test for bone mineral density changed over time (p < 0.05 were considered significant). In the distal femur, significant changes in bone mineral density were seen after 24 months of follow-up, and bone mineral density decreased by 23.6% in the anterior region behind the anterior flange of the prosthesis (p < 0.001), 10.1% in the posterior region (p < 0.001), and 5.5% in the most proximal region (p < 0.001). We found highly significant bone mineral change in the distal femur after uncemented total knee arthroplasty, most pronounced in the anterior region, where a decrease in bone mineral density of almost 25%, was seen. Taking the expected age-related decay in bone mineral density in this age group into consideration, the decrease was substantial and must be considered to predispose to periprosthetic fractures.

Monoblock versus modular polyethylene insert in uncemented total knee arthroplasty.

Background and purpose - Backside wear of the polyethylene insert in total knee arthroplasty (TKA) can produce clinically significant levels of polyethylene debris, which can lead to loosening of the tibial component. Loosening due to polyethylene debris could theoretically be reduced in tibial components of monoblock polyethylene design, as there is no backside wear. We investigated the effect of 2 different tibial component designs, monoblock and modular polyethylene, on migration of the tibial component in uncemented TKA. Patients and methods - In this randomized study, 53 patients (mean age 61 years), 32 in the monoblock group and 33 in the modular group, were followed for 2 years. Radiostereometric analysis (RSA) was done postoperatively after weight bearing and after 3, 6, 12, and 24 months. The primary endpoint of the study was comparison of the tibial component migration (expressed as maximum total point motion (MTPM)) of the 2 different implant designs. Results - We did not find any statistically significant difference in MTPM between the groups at 3 months (p = 0.2) or at 6 months (p = 0.1), but at 12 and 24 months of follow-up there was a significant difference in MTPM of 0.36 mm (p = 0.02) and 0.42 mm (p = 0.02) between groups, with the highest amount of migration (1.0 mm) in the modular group. The difference in continuous migration (MTPM from 12 and 24 months) between the groups was 0.096 mm (p = 0.5), and when comparing MTPM from 3-24 months, the difference between the groups was 0.23 mm (p = 0.07). Interpretation - In both study groups, we found the early migration pattern expected, with a relatively high initial amount of migration from operation to 3 months of follow-up, followed by stabilization of the implant with little migration thereafter. However, the modular implants had a statistically significantly higher degree of migration compared to the monoblock. We believe that the greater stiffness of the modular implants was the main reason for the difference in migration, but an initial creep in the polyethylene metal-back locking mechanism of the modular group could also be a possible explanation for the observed difference in migration between the 2 study groups.