Medium-term results of inlay vs. onlay humeral components for reverse shoulder arthroplasty: a New Zealand Joint Registry study.

BACKGROUND: The purpose of this study was to compare medium-term results of inlay and onlay humeral components in reverse shoulder arthroplasty (RSA). Specifically, we report differences in revision rate and functional outcomes between the 2 designs. METHODS: The 3 most used inlay (in-RSA) and onlay (on-RSA) implants by volume from the New Zealand Joint Registry were included in the study. In-RSA was defined as having a humeral tray that recessed within the metaphyseal bone, whereas on-RSA was defined as having a humeral tray that rested on the epiphyseal osteotomy surface. The primary outcome was revision up to 8 years postsurgery. Secondary outcomes included the Oxford Shoulder Score (OSS), implant survival, and revision cause for in-RSA and on-RSA as well as individual prostheses. RESULTS: There were 6707 patients (5736 in-RSA; 971 on-RSA) included in the study. For all causes, in-RSA demonstrated a lower revision rate compared to on-RSA (revision rate/100 component years: in-RSA 0.665, 95% confidence interval [CI] 0.569-0.768; on-RSA 1.010, 95% CI 0.673-1.415). However, the mean 6-month OSS was higher for the on-RSA group (mean difference 2.20, 95% CI 1.37-3.03; P < .001). However, this was not clinically significant. At 5 years, there were no statistically or clinically significant differences between the 2 groups with respect to the OSS. CONCLUSION: The medium-term survival of in-RSA was higher than that of on-RSA. However, functional outcomes at 6 months were better for on-RSA compared to in-RSA. Further follow-up is required to understand the long-term survivorship and functional outcomes between these designs.

Outcomes of reverse shoulder arthroplasty in patients under 55 years old: Results from the New Zealand joint registry.

Background: The appropriate age at which to perform reverse shoulder arthroplasty is controversial. The aim of this study was to compare the outcomes of reverse shoulder arthroplasty between younger and older patients. Methods: Patients who underwent primary reverse shoulder arthroplasty between January 2000 and December 2019 were identified from New Zealand Joint Registry records. Patients were stratified into two cohorts according to age at the time of surgery: < 55 years and ≥ 55 years. These two groups were then compared with regard to baseline characteristics, indications for surgery, revision rates, and patient-reported outcomes using the Oxford Shoulder Score and American Shoulder and Elbow Score (ASES). Results: A total of 5518 primary reverse shoulder arthroplasty cases were identified, with 75 patients < 55 years at the time of surgery (range: 34-54 years). The mean duration of follow-up was 2.36 years (range: 0.11-13.37 years) in the younger cohort and 3.10 years (range: 0.01-16.22 years) in the older patient cohort. Indications for surgery differed significantly between the two groups, with younger patients having higher rates of inflammatory arthritis (p < 0.001), posttraumatic arthritis (p < 0.001), and avascular necrosis (p = 0.049). The younger cohort had an inferior 6-month postoperative Oxford Shoulder Score compared to the older cohort (mean: 28.5 [younger cohort] vs. 35.7 [older cohort]; p < 0.001). There was no significant difference in revision rate between the younger and older patient cohorts during the study period (1.56 [<55 years] vs. 0.74 [≥55 years] revisions per 100 component-years; p = 0.332). Conclusion: Our early results suggest that younger patients undergoing reverse shoulder arthroplasty demonstrate high implant retention rates, comparable to older patients. Longer-term patient-reported outcomes in younger patients are required to guide appropriate patient selection for reverse shoulder arthroplasty. Level of evidence: Level III, retrospective case-control study.

Assessing the Mortality Rate After Primary Total Knee Arthroplasty: An Observational Study to Inform Future Economic Analysis.

BACKGROUND: Previous research has focused on the perioperative or short-term (<1 year) mortality rate of total knee arthroplasty (TKA), leaving the long-term (>1 year) mortality rate unresolved. In this study, we calculated the mortality rate up to 15 years after primary TKA. METHODS: Data from the New Zealand Joint Registry from April 1998 to December 2021 were analyzed. Patients aged 45 years or older who underwent TKA for osteoarthritis were included. Mortality data were linked with national records from births, deaths, and marriages. To determine the expected mortality rates in the general population, age-sex-specific life tables from statistics New Zealand were used. Mortality rate was presented as standardized mortality ratios (SMRs) - a comparison of relative mortality rate between the TKA and general populations. In total, 98,156 patients with a median follow-up of 7.25 years (range, 0.00 to 23.74) were included. RESULTS: Over the entire follow-up period, 22,938 patients (23.4%) had died. The overall SMR for the TKA cohort was 1.08 (95% confidence interval (CI): 1.06 to 1.09), suggesting that TKA patients have an 8% higher mortality rate compared to the general population. However, a reduction in short-term mortality rate was observed for TKA patients up to 5 years post TKA (SMR 5 years post TKA; 0.59 95% CI: 0.57 to 0.60]). On the contrary, a significantly increased long-term mortality rate was observed in TKA patients with greater than 11 years of follow-up, particularly in men over the age of 75 years (SMR 11 to 15 years post TKA for males ≥ 75 years; 3.13 [95% CI: 2.95 to 3.31]). CONCLUSION: The results suggest a reduction in short-term mortality rate for patients who undergo primary TKA. However, there is an increased long-term mortality rate particularly in men over the age of 75 years. Importantly, the mortality rates observed in this study cannot be causally attributed to TKA alone.

The lifetime revision risk of primary anatomic and reverse total shoulder arthroplasty.

BACKGROUND: Implant survival in total shoulder arthroplasty (TSA) is currently defined with reference to a set time period (eg, 5-year implant survival). This is a difficult concept for patients to understand, especially for younger patients who have more years of life remaining. Our study aims to calculate a patient's lifetime revision risk after primary anatomic (aTSA) and reverse (rTSA) total shoulder arthroplasty-a more meaningful projection of revision risk over a patient's remaining lifetime. METHODS: The New Zealand Joint Registry (NZJR) and national death data was used to calculate the incidence of revision and mortality in all patients who underwent primary aTSA and rTSA in New Zealand between 1999 and 2021. Lifetime revision risk was calculated using previously described methods, and this risk was stratified by age (46-90 years, 5-year bins), sex, and procedure type (aTSA and rTSA). RESULTS: In total, there were 4346 patients in the aTSA cohort and 7384 patients in the rTSA cohort. Lifetime revision risk was highest in the youngest age group (46-50 years) at 35.8% (95% CI 34.5%-37.0%) for aTSA and 30.9% (95% CI 29.9%-32.0%) for rTSA, with risk decreasing with increasing age. Across all age groups, the lifetime revision risk was higher for aTSA compared to rTSA. By sex, females reported higher lifetime revision risk for each age group in the aTSA cohort whereas males reported higher lifetime revision risk for each group in the rTSA cohort. CONCLUSIONS: Our study demonstrates that younger patients have higher lifetime revision risk after total shoulder arthroplasty. Our results highlight the long-term revision risks associated with the trend of offering shoulder arthroplasty to younger patients. The data may be used among various health care stakeholders to inform the surgical decision-making process and plan for future health care resource use.

Quadriceps tendon autograft is comparable to hamstring tendon and bone-patella-tendon-bone up to 2 years after isolated primary anterior cruciate ligament reconstruction.

PURPOSE: To evaluate the functional and graft survivorship outcomes of the three most common autograft options for primary anterior cruciate ligament reconstruction (ACLR)-hamstring tendon (HT), bone-patella-tendon-bone (BPTB), and quadriceps tendon (QT). METHODS: Patients captured by the New Zealand ACL registry who underwent a primary ACLR from 2014 to 2020 were considered for the study. Patients with associated knee injury (including meniscus, chondral, osseous, and additional ligamentous injury) and previous knee surgery were excluded. Comparison was made between HT, BPTB, and QT autografts with respect to Marx and KOOS (Knee Osteoarthritis Outcome Score) scores at minimum 2 years follow-up. In addition, graft survivorship was evaluated by comparing all-cause revision per 100 graft years and revision-free proportion at 2 years post-surgery. RESULTS: 2,582 patients (1,921 HT, 558 BPTB, 107 QT) were included in the study. Differences in adjusted functional outcomes between HT and BPTB were found at 12 months (mean Marx; HT 6.2; BPTB 7.1; P < 0.001) (mean KOOS Sport and Recreation; HT 75.1; BPTB 70.5; n.s.) and 24 months (mean KOOS Sports and Recreation; HT 79.2; BPTB 73.9; P < 0.001). QT was comparable to HT and BPTB in all functional scores at 12 months and 2 years. No statistically significant differences were found in revision rate between all three autograft groups up to 2 years post-surgery (revision rate per 100 graft years; HT 1.05; BPTB 0.80; QT 1.68; n.s. HT vs. BPTB; n.s. HT vs. QT; n.s. QT vs. BPTB). CONCLUSIONS: QT was found to be comparable to both HT and BPTB in all functional scores and revision rates up to 2 years post-surgery. LEVEL OF EVIDENCE: Level III.

Medium-term results of stemless, short, and conventional stem humeral components in anatomic total shoulder arthroplasty: a New Zealand Joint Registry study.

BACKGROUND: The purpose of this study was to compare the medium-term results for anatomic total shoulder arthroplasty by humeral component stem length. We hypothesize that the newer stemless implants may have comparable results to short-stem and conventional stemmed implants. METHODS: The 12 most used anatomic total shoulder arthroplasty implants on the New Zealand Joint Registry were included in the study. Implants were categorized by stem length-conventional, short, and stemless. The primary outcome was revision up to 7 years postsurgery. Secondary outcomes included revision cause, implant survival, and early functional outcomes as evaluated by the Oxford Shoulder Score. Analysis was stratified by age and surgeon volume to control for potential confounding. RESULTS: A total of 3952 patients (conventional, 3114; short, 360; stemless, 478) were included in the study. No significant difference in revision rate per 100 component-years was found between stemless, short-stem, and conventional stemmed implants (revision rate per 100 component-years: conventional, 1.01 [95% confidence interval (CI) 0.89-1.14]; short, 0.54 [95% CI 0.25-1.03]; stemless, 0.99 [95% CI 0.51-1.74]). This finding was irrespective of patient age or surgeon volume. There were no cases of humeral loosening up to 7 years' follow-up and no cases of intraoperative humeral fracture in the stemless group. Functional outcomes at 6 months postsurgery suggested better outcomes in the stemless group compared with the conventional stem group (mean Oxford Shoulder Score: conventional, 39.4; stemless, 40.7; P value = .023). CONCLUSION: The medium-term survival of stemless implants for anatomic total shoulder arthroplasty appears comparable to short-stem and conventional stemmed implants. Further follow-up is required to understand the long-term survivorship and functional outcomes between these groups.

The outcomes of shoulder arthroplasty in those aged ≥70 years with glenohumeral arthritis: a New Zealand Joint Registry study.

INTRODUCTION: Reverse total shoulder arthroplasty (RTSA) was traditionally reserved for the patient with rotator cuff tear arthropathy. As the indications for RTSA continue to expand, the role of RTSA in patients aged >70 years with glenohumeral arthritis and an intact rotator cuff remains unclear. AIM: To study the New Zealand Joint Registry (NZJR) and compare the outcomes of a primary Total Shoulder Arthroplasty (TSA), a primary RSA and an RSA performed for revision of a failed TSA in patients aged >70 years, to determine if there is clear evidence to support a primary RSA in those aged >70 years instead of a primary TSA METHOD: This is a retrospective study of the NZJR from 2000 to 2018. We included all primary TSAs, primary RTSAs, and those RTSAs that were performed for the revision of a failed TSA. We excluded those RTSAs that were performed for the revision of an RTSA or hemiarthroplasty. The primary outcome was the Oxford Shoulder Score (OSS) at 6 months and 5 years, with a secondary outcome being the subsequent revision rate. RESULTS: A total of 3449 primary TSAs, 4681 primary RTSAs, and 104 revision RTSAs were identified. The mean OSSs at 6 months for a primary TSA, a primary RTSA, and a revision RTSA were 39.5 ± 9.0, 35.5 ± 9.4, and 32.5 ± 9.7, respectively (P < .001, primary TSA vs. primary RSTA; P <.001, primary TSA vs. revision RTSA; P = .0252 primary RTSA vs. revision RTSA). The mean OSSs at 5 years for a primary TSA and a primary RTSA were 42.1 ± 7.5 vs. 39.8 ± 8.4, respectively (P < .001), with no results available for revision RTSA. The secondary outcome was the revision rate for those aged >70 years with osteoarthritis as their primary indication for surgery. The revision rates for a primary TSA and a primary RTSA were 0.53/100 component-years (95% confidence interval [CI] 0.38-0.72) and 0.51/100 component-years (95% CI 0.31-0.79), respectively (P = .193), which was not statistically significant. CONCLUSION: The TSA remains the gold standard for primary shoulder arthroplasty. For those individuals aged >70 years with osteoarthritis as their primary diagnosis, a primary TSA is associated with a higher OSS than and similar revision rates to a primary RTSA's. However, these patients must be counseled regarding the risk of subsequent cuff failure, as the outcomes from a revision RTSA are significantly inferior than those from a primary RTSA.

Cemented vs. uncemented glenoid fixation in total shoulder arthroplasty for osteoarthritis: a New Zealand Joint Registry study.

BACKGROUND: Total shoulder arthroplasty (TSA) is commonly performed for shoulder osteoarthritis (OA). Uncemented metal-backed (MB) glenoid components were introduced in an attempt to avoid glenoid loosening. New Zealand and Australian Joint Registry studies have shown significantly higher revision rates when uncemented MB glenoids are used. We used the New Zealand Joint Registry (NZJR) to compare all-cause revision rates and functional scores for TSA and investigated the trends of glenoid fixation used in New Zealand. METHODS: The NZJR was accessed for all primary TSA undertaken for OA from January 2000 to December 2017. Patient demographics were collated. All-cause revision rates were reported as rate per 100 component-years. Analysis was repeated excluding the uncemented SMR L2 glenoid (LimaCorporate), as it was a potential confounder. Kaplan-Meier survival analysis was performed. Oxford Shoulder Scores at both 6 months and 5 years were analyzed. RESULTS: A total of 2613 TSAs were performed for OA during the study period, representing 85.0% of all TSAs in New Zealand. Overall, 62.1% of the patients were female. In addition, 69.6% of glenoids were cemented and 30.4% uncemented. The most common uncemented MB glenoid was SMR 86.6% (LimaCorporate), and cemented was Global (DePuy) 49.8%. The revision rate for TSA with uncemented glenoids was significantly higher at 2.03 compared with cemented at 0.41 per 100 component-years (P < .001). Hazard ratio 5.0 for revision of uncemented glenoids. No significant difference was found in Oxford Scores at 6 months (39.7 vs. 40.3, P = .13) or 5 years (42.1 vs. 42.8, P = .22). The most common mode of failure was glenoid loosening in cemented glenoids (44.4%), and component failure in uncemented (34.8%). Revision for rotator cuff, deep infection, and instability were comparable between groups. When excluding SMR L2, uncemented MB glenoid all-cause revision rates remained significantly higher than cemented (1.42 vs. 0.41 per 100 component-years, P < .001). SMR L1 uncemented MB glenoids had a higher revision rate than the non-SMR uncemented glenoids (1.61 vs. 0.18 per 100 component-years, P = .009). Uncemented glenoid use peaked in New Zealand in 2011 at 46.7% of TSAs but declined to 20.1% in 2017. CONCLUSIONS: In the NZJR, primary TSAs undertaken for OA have a significantly higher all-cause revision rate when the glenoid component is uncemented. Uncemented glenoids have a 5.0 times higher revision rate. Excluding SMR L2 glenoids from the analysis, the significantly higher revision rate remained for uncemented glenoids. These data reaffirm that uncemented MB glenoids are associated with higher revision rates.