Aims The success of total knee arthroplasty (TKA) is usually measured using functional outcome scores and revision-free survivorship. However, reporting the lifetime risk of revision may be more meaningful to patients when gauging risks, especially in younger patients. We aimed to assess the lifetime risk of revision for patients in different age categories at the time of undergoing primary TKA. Methods The New Zealand Joint Registry database was used to obtain revision rates, mortality, and the indications for revision for all primary TKAs performed during an 18-year period between January 1999 and December 2016. Patients were stratified into age groups at the time of the initial TKA, and the lifetime risk of revision was calculated according to age, sex, and the American Society of Anesthesiologists (ASA) grade. The most common indications for revision were also analyzed for each age group. Results The overall ten-year survival rate was 95.6%. This was lowest in the youngest age group (between 46 and 50 years) and increased sequentially with increasing age. The lifetime risk of requiring revision was 22.4% in those aged between 46 and 50 years at the time of the initial surgery, and decreased linearly with increasing age to 1.15% in those aged between 90 and 95 years at the time of surgery. Higher ASA grades were associated with increased lifetime risk of revision in all age groups. The three commonest indications for revision were aseptic loosening, infection, and unexplained pain. Young males, aged between 46 and 50 years, had the highest lifetime risk of revision (25.2%). Conclusion Lifetime risk of revision may be a more meaningful measure of outcome than implant survival at defined time periods when counselling patients prior to TKA. This study highlights the considerably higher lifetime risk of revision surgery for all indications, including infection, in younger male patients. Cite this article: Bone Joint J 2022;104-B(2):235–241.

Source of the study: University of Auckland, Auckland, New Zealand and University of Otago, Christchurch, New ZealandOutcomes following knee arthroplasty are typically defined as implant survivorship at defined timepoints, or revision incidence over time. These estimates are difficult to conceptualise, and lack context for younger patients with more remaining years of life. We therefore aimed to determine a ‘lifetime’ risk of revision as a more useful metric for total (TKA) and unicompartmental knee arthroplasty (UKA).The New Zealand Joint Registry was used to identify 96,497 primary TKAs and 13,481 primary UKAs performed between 1999 and 2019. Patient mortality and revision incidence were also extracted. Estimates of lifetime risk were calculated using an actuarial lifetable method. The estimates were stratified by age and gender. Reasons for revision were categorised using previously published standardised definitions.The lifetime risk of UKA revision was two-fold higher than TKA across all age groups (range 3.7-40.4% UKA, 1.6-22.4% TKA). Revision risk was higher for males with TKA (range 3.4%-25.2% males, 1.1%-20% females), but higher for females with UKA (range 4.3%-43.4% vs. 2.9%-37.4% for males). Revision due to infections were higher for TKA (1.5% males, 0.7% females) compared with UKA (0.4% males, 0.1% females). The increased risk in younger UKA patients was associated with higher incidence of aseptic loosening (UKA 2%, TKA 1%) and ‘unexplained pain’ (UKA 2%, TKA 0.2%).The risk for UKA was two-fold higher than TKA, and this was partially explained by a higher proportion of revisions due to ‘unexplained pain’. For TKA, males had higher risk of revision, in contrast to UKA where females had higher risk; this gender difference was associated with higher incidence of infections with TKA. Younger age, gender and higher ASA status were also associated with increased lifetime risk of UKA revision. Lifetime risk of revision can provide a meaningful measure of arthroplasty outcomes to aid patient counselling.

BACKGROUND Obesity has a significant association with renal cell carcinoma (RCC). Surgery is the preferred treatment of demarcated RCC. Obesity increases the complexity of surgical outcomes. There is a paucity of data regarding surgical technique outcomes in obese patients. OBJECTIVE We investigated short- and long-term renal outcomes in obese patients post-RCC surgery through open, laparoscopic, or robotic partial nephrectomy. METHODS This is a retrospective chart review of obese patients after open, laparoscopic, or robotic partial-nephrectomies over 12 years at a single center. The obese (BMI ≥ 30) and the non-obese (BMI< 30) patients were studied in 2-time frames: short (3-6 months post-surgery), or long (> 6 months) and followed up to 4 years. RESULTS Of the 140 patients, 75 were obese and 65 were non-obese. In the obese, 3-6 months after minimally-invasive surgery, the odds of having a decrease or no change in creatinine values were 0.62 times lower compared to open surgery. Over 6 months after minimally-invasive surgery, the odds were 1.24 times higher. Neither of these results were statistically significant. In the non-obese group, at 3-6 months after minimally-invasive surgery, the same odds were 4.86 times higher. This was statistically significant (P<0.05). Over 6 months after minimally invasive surgery, the odds were 4.13 times higher. This was not statistically significant. CONCLUSIONS We observed non-statistically significant preservation of renal function in obese patients undergoing OPN at 3-6 months postoperatively. Conversely, after 6 months, the same was true for MIPN, indicating a long-term benefit of MIPN. In the non-obese, MIPN was favored over OPN. CLINICALTRIAL na