High in-vivo accuracy of a novel robotic-arm-assisted system for total knee arthroplasty.

PURPOSE: Robotic-assisted total knee arthroplasty (TKA) has been shown to improve the accuracy and precision of bony resections and implant position. However, the in vivo accuracy of the full surgical workflow has not been widely reported. The primary objective of this study is to determine the accuracy and precision of a robotic-arm-assisted system throughout the intraoperative workflow. METHODS: This was a retrospective cohort study of adult patients who underwent primary TKA with various workflows and alignment targets by three arthroplasty-trained surgeons with previous experience using the ROSA® Knee System (Zimmer Biomet) over a 3-month follow-up period. Accuracy and precision were determined by measuring the difference between various workflow time points, including the final preoperative plan (PP), robot-validated (RV) resection angle and postoperative radiographs (PR). The absolute mean difference between the measurements determined accuracy, and the standard deviation represented precision. The lateral distal femoral angle, medial proximal tibial angle, femoral flexion angle and tibial slope were measured on postoperative coronal long-leg radiographs and true short-leg lateral radiographs. RESULTS: A total of 77 patients were included in the final analyses. The accuracy for the coronal femoral angle was 1.62 ± 1.11°, 0.75 ± 0.79° and 1.96 ± 1.29° for the differences between PP and PR, PP and RV and RV and PR. The tibial coronal accuracy was 1.44 ± 1.03°, 0.81 ± 0.67° and 1.57 ± 1.14° for PP/PR, PP/RV and RV/PR, respectively. Femoral flexion accuracy was 1.39 ± 1.05°, 0.83 ± 0.59° and 1.81 ± 1.21° for PP/PR, PP/RV and RV/PR, respectively. Tibial slope accuracy was 0.99 ± 0.72°, 1.19 ± 0.87° and 1.63 ± 1.11°, respectively. The proportion of patients within 3° was 93.2%, 95.3%, 97.3% and 94.6% for the distal femur, proximal tibia, femoral flexion and tibial slope angles when the final intraoperative plan was compared to PRs. No patients had a postoperative complication at the final follow-up. CONCLUSIONS: The ROSA Knee System has acceptable accuracy and precision of coronal and sagittal plane resections with few outliers at various steps throughout the platform's entire workflow in vivo. LEVEL OF EVIDENCE: Level III.

Systematic genetic analysis of early-onset gout: ABCG2 is the only associated locus.

OBJECTIVE: The aim of this study was to examine whether serum urate-associated genetic variants are associated with early-onset gout. METHODS: Participants with gout in the Genetics of Gout in Aotearoa study with available genotyping were included (n = 1648). Early-onset gout was defined as the first presentation of gout <40 years of age. Single nucleotide polymorphisms (SNPs) for the 10 loci most strongly associated with serum urate were genotyped. Allelic association of the SNPs with early-onset gout was tested using logistic regression in an unadjusted model and in a model adjusted for sex, body mass index, tophus presence, flare frequency, serum creatinine and highest serum urate. The analysis was also done in two replication cohorts: Eurogout (n = 704) and Ardea (n = 755), and data were meta-analysed. RESULTS: In the Genetics of Gout in Aotearoa study, there were 638 (42.4%) participants with early-onset gout. The ABCG2 rs2231142 gout risk T-allele was present more frequently in participants with early-onset gout compared with the later-onset group. For the other SNPs tested, no differences in risk allele number were observed. In the allelic association analysis, the ABCG2 rs2231142 T-allele was associated with early-onset gout in unadjusted and adjusted models. Analysis of the replication cohorts confirmed the association of early-onset gout with the ABCG2 rs2231142 T-allele, but not with other serum urate-associated SNPs. In the meta-analysis, the odds ratio (95% CI) for early-onset gout for the ABCG2 rs2231142 T-allele was 1.60 (1.41, 1.83). CONCLUSION: In contrast to other serum urate-raising variants, the ABCG2 rs2231142 T-allele is strongly associated with early-onset gout.

Higher Heart Weight in New Zealand Maori and Pacific Islanders.

Heart weight is dependent on sex, age, height, and weight. Although previous autopsy studies showed no differences in heart weight between different ethnic groups, none have examined the New Zealand population of Maori and Pacific Islanders (Polynesians). The presented study compared heart weights between 101 European and 85 Polynesian suicide hanging deaths from New Zealand. Univariate linear regression coefficients for age, male sex, height, body weight, body mass index, and Polynesian ethnicity were positive and significant (P < 0.05). Apart from body mass index, subsequent multivariate analysis showed that all regression coefficients remained positive and significant (P < 0.05). Polynesian ethnicity seemed to be an independent predictor for increased heart weight in the study population. Apart from possible genetic factors, the higher heart weight in Polynesians may have other underlying reasons. Caution is required when interpreting heart weight in cases of sudden natural deaths, especially in this population.

Introduction of ROSA robotic-arm system for total knee arthroplasty is associated with a minimal learning curve for operative time.

PURPOSE: The introduction of robotics for total knee arthroplasty (TKA) into the operating theatre is often associated with a learning curve and is potentially associated with additional complications. The purpose of this study was to determine the learning curve of robotic-assisted (RA) TKA within a multi-surgeon team. METHODS: This prospective cohort study included 83 consecutive conventional jig-based TKAs compared with 53 RA TKAs using the Robotic Surgical Assistant (ROSA) system (Zimmer Biomet, Warsaw, Indiana, USA) for knee osteoarthritis performed by three high-volume (> 100 TKA per year) orthopaedic surgeons. Baseline characteristics including age, BMI, sex and pre-operative Kellgren-Lawrence graded and Hip-Knee-Ankle Axis were well-matched between the conventional and RA TKA groups. Cumulative summation (CUSUM) analysis was used to assess learning curves for operative times for each surgeon. Peri-operative and delayed complications (infection, periprosthetic fracture, thromboembolism, and compromised wound healing) and revisions were reviewed. RESULTS: The CUSUM analysis for operative time demonstrated an inflexion point after 5, 6 and 15 cases for each of the three surgeons, or 8.7 cases on average. There were no significant differences (p = 0.53) in operative times between the RA TKA learning (before inflexion point) and proficiency (after inflexion point) phases. Similarly, the operative times of the RA TKA group did not differ significantly (p = 0.92) from the conventional TKA group. There was no discernible learning curve for the accuracy of component planning using the RA TKA system. The average length of post-operative follow-up was 21.3 ± 9.0 months. There was one revision for instability in the conventional TKA group and none in the RA TKA group. There were no significant difference (p > 0.99) in post-operative complication rates between the conventional TKA and RA TKA groups. CONCLUSIONS: The introduction of the RA TKA system was associated with a learning curve for operative time of 8.7 cases. Operative times between the RA TKA and conventional TKA group were similar. The short learning curve implies this RA TKA system can be adopted relatively quickly into a surgical team with minimal risks to patients.