Australian Orthopaedic Association Research Articles

What Is the Risk of Revision Surgery in Hydroxyapatite-coated Femoral Hip Stems? Findings From a Large National Registry.

Despite wide adoption of hydroxyapatite (HA)-coated femoral stems in THA, no studies have found differences in the risk of revision surgery with its use or investigated the interaction of different prosthesis designs with stem coating. The purpose of this study was to evaluate the risk of revision in THAs with HA-coated stems compared with non-HA-coated. To achieve this purpose, we asked: (1) What is the difference in risk of revision of THAs with HA-coated femoral stems compared with non-HA-coated using an aggregate analysis? (2) What is the difference in risk of revision of THAs with HA-coated femoral stems compared with non-HA-coated for five prosthesis types that used the same femoral and acetabular component combination but where the femoral stem had both a HA and non-HA coating option? The Australian Orthopaedic Association National Joint Replacement Registry analyzed cementless primary THA registered between September 1, 1999, and December 31, 2014. Of the 147,645 cases that fit our selection criteria, 81.1% (N = 119,673) had HA-coated stems. Overall (that is, all procedures with any prostheses in the registry) and five prosthesis designs where both an HA-coated stem and non-HA-coated stem exist (Zimmer's VerSys®/Trilogy® [N = 3924], Biomet's Mallory-Head®/Mallory-Head [N = 2538], Smith & Nephew's SL-Plus/EP Fit-Plus [N = 2028], Biomet's Taperloc®/Exceed [N = 1668], and Biomet's Taperloc/Mallory-Head [N = 1240]) were evaluated. Revision surgery was the outcome of interest. Survival analyses were conducted and hazard ratios (HRs) were adjusted for age, sex, bearing surface, femoral head size, and acetabular component HA coating. In the overall cohort, HA stems had a lower any-cause revision risk after 6 months (HR, 0.83; 95% confidence interval [CI], 0.72-0.95; p = 0.007). However, the risk of revision varied when we evaluated the effect of HA on revision for specific prothesis combinations that had both HA and non-HA options for the femoral stem. VerSys/Trilogy, Mallory-Head/Mallory-Head, Taperloc/Exceed, and Taperloc/Mallory-Head did not have a lower risk of any-cause revision with HA-coated stems compared with non-HA-coated. Only the SL-Plus/EP Fit-Plus subgroup showed a lower risk of revision for loosening (HR, 0.17; 95% CI, 0.06-0.44 between 0 and 7 years; p < 0.001) with HA- compared with non-HA-coated stems, but this was observed after an early (< 6 months) higher risk of revision for any reason (HR, 2.88; 95% CI, 1.15-7.21; p = 0.024). Overall, HA coating of femoral stems was found to be associated with a 17% lower risk of revision for any reason. However, the lower risk of revision associated with HA was not consistent for all prosthesis designs where both HA- and non-HA-coated femoral stem versions were available. Some HA-coated stems have higher revision rates compared with their non-HA-coated versions. Our findings suggest that the effect of HA coating on revision risk varies depending on prosthesis design. Level II, therapeutic study.

Cross-Linked Polyethylene for Total Hip Arthroplasty: A Model for Evaluation of a Medical Device: Commentary on an article by R. de Steiger, MBBS, FRACS, FAOrthA, et al.: "Cross-Linked Polyethylene for Total Hip Arthroplasty Markedly Reduces Revision Surgery at 16 Years".

Commentary The article by Professor de Steiger and associates describes an important study providing clinical confirmation of the promise of improved survivorship with highly cross-linked polyethylene (XLPE) liners in total hip arthroplasty (THA). The authors report the results of their survivorship analysis comparing 41,171 THAs performed with ultra-high molecular weight conventional polyethylene (CPE) and 199,131 performed with gamma, or electron beam, irradiated XLPE between 1999 and 2016. The 16-year cumulative percentage of revisions was 11.7% (95% confidence interval [CI] = 11.1% to 12.3%) for CPE compared with 6.2% (95% CI = 5.7% to 6.7%) for XLPE. The hazard ratio at 9 years was 3.02. Reduced in vitro wear of XLPE liners had previously been reported with preclinical testing1, but laboratory testing of earlier polyethylene enhancements, such as Hylamer, did not accurately predict clinical performance2. Early clinical experience with XLPE was encouraging as the devices were not identified as outliers in large national registries such as the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Reduced wear of XLPE liners in vivo was reported in radiostereometric analysis (RSA) studies3, resulting in further optimism for this bearing surface. Improved survivorship with XLPE liners was recently reported in a randomized controlled trial (RCT) with a 10-year follow-up that demonstrated a revision rate of 1.9% with Marathon liners compared with 14.6% with Enduron liners4. This was a single-center study of 122 THAs performed with cemented stems and cementless Duraloc cups by 2 experienced surgeons in 1 medical center. The Kaiser Permanente Total Joint Replacement Registry previously reported improved survivorship of XLPE liners compared with CPE liners5. The cumulative incidence of revision was 5.4% of 1,815 THAs with a CPE liner compared with 2.8% of 25,008 with an XLPE liner at 7 years; the hazard ratio for aseptic failure was 1.9. The study by de Steiger et al. utilized cases from the AOANJRR and expanded on this earlier report with longer follow-up, larger sample sizes, and a greater variety of hip implants. The AOANJRR was initiated in 1999, about the time that several highly cross-linked irradiated polyethylene products became commercially available. This timely coincidence allowed for a longitudinal clinical study of a large number of THA cases representing the gradual transition from CPE to XLPE. The registry quickly collected a large volume of cases performed by many surgeons, in many different hospitals, with a variety of implants. However, unlike prospective trials, in which interventions are performed concurrently, there are temporal differences between cohorts in registry analyses. At the beginning of the study period examined by de Steiger et al., most THAs were done with a CPE liner, whereas at the end of the study period most were performed with XLPE. During the 17-year study period, there may have been differences in patient selection, perioperative care protocols, and possibly surgeon experience. Although the authors speculated that any patient selection likely favored the use of XLPE in younger individuals, the opposite may be true because the study samples represented only 74% of the THAs performed for osteoarthritis. Until the AOANJRR formally recalled the ASR (Articular Surface Replacement) in 2009, surgeons may have chosen metal-on-metal or ceramic-on-ceramic bearings—not necessarily XLPE liners—for younger and more active patients. Despite this limitation, the subanalysis performed by de Steiger et al. showed a reduced risk of revision with XLPE cups even in patients under the age of 55 years. The strengths of this observational registry study include data that are generalizable to the “real world,” unlike the findings from an RCT, which may involve limited numbers of patients, few implant types, and limited numbers of surgeons in a single center. In the community, THA procedures are performed by a variety of surgeons with varying skills and specializations. Additionally, in the community, multiple implant combinations are utilized and procedures are performed in a variety of hospital settings. The story of XLPE liners is a good example of how new implants should be introduced and monitored: with careful preclinical testing, rigorous early clinical studies, widespread surveillance, and carefully performed mid-term clinical investigations. The current study is an important, and reassuring, contribution to the orthopaedic literature as XLPE has been widely used throughout the world in millions of patients.

Correction to: Geographic region, socioeconomic position and the utilisation of primary total joint replacement for hip or knee osteoarthritis across western Victoria: a cross-sectional multilevel study of the Australian Orthopaedic Association National Joint Replacement Registry.

The names of the co-authors Steven Graves and Michelle Lorimer were missing from the manuscript supplied for publication. The lead authors regret this error and apologize for any inconvenience.

What is the Benefit of Optimum Prosthesis Combination Selection in Total Knee Replacement? An Analysis of 482373 Prostheses from the Australian Orthopaedic Association National Joint Replacement Registry

What is the Benefit of Optimum Prosthesis Combination Selection in Total Knee Replacement? An Analysis of 482373 Prostheses from the Australian Orthopaedic Association National Joint Replacement Registry

Relationship of weight and obesity with the risk of knee and hip arthroplasty for osteoarthritis across different levels of physical performance: a prospective cohort study

Objective: To examine the association between obesity and knee and hip arthroplasty for osteoarthritis across a range of physical performance.Method: The body mass index and physical performance (on the 36-item Short Form Health Survey) of 9135 Australian Diabetes, Obesity and Lifestyle Study participants were measured in 1999–2000. The incidence of knee and hip arthroplasty during 2002–2011 was determined by linking the cohort records to the Australian Orthopaedic Association National Joint Replacement Registry.Results: Over 9.1 ± 2.3 years (mean ± sd)) of follow-up, 317 participants had knee and 202 had hip arthroplasty for osteoarthritis. Using those with neither obesity nor significantly impaired physical performance as the reference group, participants with both obesity and significantly impaired physical performance had a higher knee arthroplasty risk [hazard ratio (HR) = 5.25, 95% confidence interval (CI) 3.85–7.14] than those with obesity alone (HR = 2.49, 95% CI 1.81–3.44) or impaired physical performance alone (HR = 2.19, 95% CI 1.59–3.02). Similar results were observed for hip arthroplasty (obesity and impaired physical performance: HR = 2.67, 95% CI 1.72–4.15; obesity alone: HR = 1.65, 95% CI 1.08–2.51; impaired physical performance alone: HR = 1.83, 95% CI 1.26–2.66). Among overweight/obese patients, 5 kg greater baseline weight increased the knee arthroplasty risk across all levels of physical performance, and hip arthroplasty risk in those with the highest level of physical performance.Conclusion: Although impaired physical performance is an independent risk factor for knee and hip arthroplasty, greater weight increased knee arthroplasty for overweight/obese participants at all levels of physical performance, but hip arthroplasty only in those with good physical performance. Targeting weight loss has the potential to reduce the risk of knee arthroplasty and improve patient outcomes, even in those with poor physical performance.

Progression to total hip arthroplasty following hip arthroscopy.

Hip arthroscopy is a minimally invasive surgical technique increasingly being used to treat hip pathology. There is evidence that a proportion of patients require total hip arthroplasty in the years immediately following arthroscopy, suggesting that these patients have derived only a limited benefit from the procedure. Identification of risk factors for early progression to hip arthroplasty may enable refinement of hip arthroscopy indications and more informed decision making. The aim of this study is to identify the proportion of patients in a hip arthroscopy cohort who progress to total hip arthroplasty within 2 years of arthroscopy, and to analyse risk factors for this early progression. A retrospective cohort analysis was conducted on all patients who underwent hip arthroscopy at one tertiary institution from 2004 to 2013. Hospital data were linked to the Australian Orthopaedic Association National Joint Replacement Registry in 2016 to identify subsequent hip arthroplasty. There were 989 arthroscopies performed on 947 patients; 447 were female (48.1%), the mean age was 41.1 years (SD: 14.23) and osteoarthritis was present at arthroscopy in 31.5%. Total hip arthroplasty occurred in 129 patients (13%) within 2 years. Multivariable logistic regression revealed osteoarthritis, age >50 years and previous arthroscopy were significant risk factors for arthroplasty within 2 years (adjusted odds ratios (confidence intervals): 4.6 (2.91-7.16), 3.8 (2.44-5.87), 2.5 (1.16-5.81)). Osteoarthritis, older age and history of arthroscopy were independent risk factors for early progression to arthroplasty; these factors should be considered within clinical decision-making, and when discussing potential arthroscopy outcomes with patients.

Mortality and Implant Survival With Simultaneous and Staged Bilateral Total Knee Arthroplasty Experience From the Australian Orthopaedic Association National Joint Replacement Registry

BackgroundTotal knee arthroplasty (TKA) is an effective procedure for relieving pain and restoring function in osteoarthritis, with a significant proportion of patients having severe disease bilaterally. However, although there are differences in patient selection criteria for bilateral procedures, there is no consensus regarding the optimal timing for bilateral TKA. The aim of this study was to compare rates and causes of revision and 30-day mortality between simultaneous and staged bilateral TKA using data from the Australian Orthopaedic Association National Joint Replacement Registry. MethodsData for over 36,000 bilateral TKAs were collected from September 1999 to December 2015. Rates and causes of revision and 30-day mortality rates were obtained for simultaneous bilateral and staged procedures with intervals of 1 day-6 weeks, 6 weeks-3 months, and 3-6 months. Yearly cumulative percent revision or cumulative percent survival with 95% confidence intervals calculated using the Kaplan-Meier method and adjusted hazard ratios were used for comparisons. ResultsThere was no significant difference between revision rates or reasons for revision between staged bilateral and simultaneous TKA (hazard ratio 1.09 [95% confidence interval {CI} 0.85-1.40; P = .511] for 1 day-6 weeks, 0.93 [95% CI 0.77-1.14; P = .494] for 6 weeks-3 months, and 1.10 [95% CI 0.98-1.23; P = .115] for 3-6 months). The most common reasons for revision were loosening/lysis and infection. The 30-day mortality rates were lower in the 6 weeks-3 months group than simultaneous bilaterals (P = .007). ConclusionThis study demonstrates that simultaneous and staged bilateral TKA have similar rates of revision over the medium term but that 30-day mortality is reduced in the 6 weeks-3 months group.

Female Reproductive and Hormonal Factors and Incidence of Primary Total Knee Arthroplasty Due to Osteoarthritis

To examine the associations of female reproductive and hormonal factors with incidence of total knee arthroplasty (TKA) for osteoarthritis (OA), and to determine whether the associations differ according to overweight/obesity status. This study included 22,289 women in the Melbourne Collaborative Cohort Study. Data on age at menarche, pregnancy, parity, years of menstruation, oral contraceptive (OC) use, menopausal status, and hormone replacement therapy (HRT) were collected in 1990-1994. Incidence of TKA during 2001-2013 was determined by linking cohort records to the Australian Orthopaedic Association National Joint Replacement Registry. All analyses were adjusted for age, body mass index (BMI) at midlife, change in BMI (from early reproductive age to midlife), country of birth, physical activity, smoking, and education level. Over the course of 12.7 years, 1,208 TKAs for OA were identified. Ever being pregnant was associated with increased risk of TKA (hazard ratio [HR] 1.32 [95% confidence interval (95% CI) 1.06-1.63]). Parity was positively associated with risk of TKA (P for trend = 0.003). OC users had increased risk of TKA compared with non-users (for OC use of <5 years, HR 1.25 [95% CI 1.08-1.45]; for OC use of ≥5 years, HR 1.17 [95% CI 1.00-1.37]). A 1-year increase in menstruation was associated with a 1% decrease in risk of TKA (HR 0.99 [95% CI 0.97-0.99]). These associations remained significant only in women of normal weight at early reproductive age. Current HRT users had increased risk of TKA compared with non-users (HR 1.37 [95% CI 1.14-1.64]); the association was significant only in non-obese women at midlife. Reproductive and hormonal factors were associated with risk of knee OA. These associations remained significant in women of normal weight at early reproductive age and in non-obese women at midlife. Further work is needed to understand the complex effect of these factors on knee OA.

Cementless versus cemented glenoid components in conventional total shoulder joint arthroplasty: analysis from the Australian Orthopaedic Association National Joint Replacement Registry

Glenoid loosening is a common mode of failure after total shoulder arthroplasty (TSA). Newer cementless glenoid components have been introduced to promote biological fixation with the aim to decrease glenoid loosening. Limited data are available comparing revision rates between cemented and cementless glenoid fixation in TSA. The study aim was to compare the revision rates of cemented and cementless design glenoid components used in conventional TSA performed for the diagnosis of osteoarthritis. The secondary aim was to compare various subclasses of glenoid components. Data were obtained between April 16, 2004, and December 31, 2016, from the Australian Orthopaedic Association National Joint Replacement Registry. Within the study period, 10,805 primary conventional TSAs were identified. The analysis was undertaken for the diagnosis of osteoarthritis, which represented 95.8% of all conventional TSA procedures. At 5 years, in patients with primary TSA procedures, those with cemented glenoids had a lower revision rate than those with cementless glenoids: 3.7% versus 17.9% (hazard ratio for entire period, 4.77). The most common revision diagnosis for primary conventional TSA with cementless glenoid fixation was rotator cuff insufficiency (4.4% for cementless vs 0.4% for cemented), instability and/or dislocation (3.8% for cementless vs 0.8% for cemented), and loosening and/or lysis (1.1% for cementless vs 1.1% for cemented). Cementless glenoid components in conventional TSA had a significantly higher revision rate than cemented glenoid components. The loosening rates between cemented and cementless glenoid components were similar. Glenoid design and fixation are important considerations when selecting a prosthesis for TSA.

Barriers to Completion of Research Projects Among Orthopaedic Trainees

It is a requirement of the Australian Orthopaedic Association (AOA) training program that surgical education training (SET) trainees demonstrate competency in clinical or basic science research as part of their teaching curriculum. The aim of this study is to identify barriers in completing research by the Victorian and Tasmanian Region AOA SET trainees. We designed a short qualitative survey which was distributed to all Victorian and Tasmanian orthopaedic trainees through the AOA. The survey consisted of 18 questions most of which were based on a 5-point Likert scale with options to add comments based on individual experience. Thirty-two (61%) orthopaedic trainees responded to the survey. Two did not give consent for their data to be used. Trainees were more likely to abandon their research projects if they had insufficient time to complete a project (p = 0.01), had fewer opportunities to take part in research (p = 0.011), were unable to complete a research project within their hospital rotation (p = 0.024), and did not have access to funding (p = 0.025). A large amount of research is abandoned by trainees. The barriers to research completion are similar to those found in the literature, however, not all barriers identified in the literature were found to be barriers to the Victorian and Tasmanian Orthopaedic trainees. By identifying barriers to research completion within training programs, we hope to assist efficiency and help improve the likelihood of project completion as well as assist mentors in their guidance of trainees while conducting research.

Female reproductive and hormonal factors and incidence of primary total knee arthroplasty due to osteoarthritis

OBJECTIVE: To examine the associations of female reproductive and hormonal factors with incidence of total knee arthroplasty (TKA) for osteoarthritis (OA), and to determine whether the associations differ according to overweight/obesity status. METHODS: This study included 22,289 women in the Melbourne Collaborative Cohort Study. Data on age at menarche, pregnancy, parity, years of menstruation, oral contraceptive (OC) use, menopausal status, and hormone replacement therapy (HRT) were collected in 1990-1994. Incidence of TKA during 2001-2013 was determined by linking cohort records to the Australian Orthopaedic Association National Joint Replacement Registry. All analyses were adjusted for age, body mass index (BMI) at midlife, change in BMI (from early reproductive age to midlife), country of birth, physical activity, smoking, and education level. RESULTS: Over the course of 12.7 years, 1,208 TKAs for OA were identified. Ever being pregnant was associated with increased risk of TKA (hazard ratio [HR] 1.32 [95% confidence interval (95% CI) 1.06-1.63]). Parity was positively associated with risk of TKA (P for trend = 0.003). OC users had increased risk of TKA compared with non-users (for OC use of <5 years, HR 1.25 [95% CI 1.08-1.45]; for OC use of ≥5 years, HR 1.17 [95% CI 1.00-1.37]). A 1-year increase in menstruation was associated with a 1% decrease in risk of TKA (HR 0.99 [95% CI 0.97-0.99]). These associations remained significant only in women of normal weight at early reproductive age. Current HRT users had increased risk of TKA compared with non-users (HR 1.37 [95% CI 1.14-1.64]); the association was significant only in non-obese women at midlife. CONCLUSION: Reproductive and hormonal factors were associated with risk of knee OA. These associations remained significant in women of normal weight at early reproductive age and in non-obese women at midlife. Further work is needed to understand the complex effect of these factors on knee OA.

MRI-detected subchondral bone marrow lesions: does using two mri sequences improve detection and clinical relevance?

Purpose: Fluid-sensitive MRIs are preferred in scoring BMLs compared to gradient recalled echo (GRE)-type MRI sequences. However, whether one sequence correlates better with clinical osteoarthritis (OA) outcomes than the other is unknown. We aim to describe the association of bone marrow lesions (BMLs) present on two different MRI sequences with pain, physical function limitation, stiffness, cartilage defect progression, cartilage volume loss over 2.7 years, and total knee replacement (TKR) over 13.3 years in older adults. Methods: 394 community-dwelling adults aged 50–80 years were assessed at baseline and 2.7 years. BML presence at baseline was scored on T1-weighted fat-suppressed 3D gradient-recalled acquisition (T1-w GRE) and T2-weighted fat-suppressed 2D fast spin-echo (T2-w FSE) MRI sequences, at the tibial, femoral, and patellar sites. Knee pain, physical function limitation, and stiffness were assessed using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scales. Cartilage volume and defect scores were assessed using validated methods. The incidence of TKR was determined by data linkage to the Australian Orthopaedic Association National Joint Replacement Registry. Ordinal logistic, linear, log binomial, and mixed-effects regression were used for analysis. Results: BMLs were mostly present on both MRI sequences (86%) and appeared slightly larger on T2-w FSE MRI. BMLs present on T2-w FSE, T1-w GRE, and both MRI sequences were associated with increased odds of moving to a higher category of knee pain and physical function limitation (odds ratio (OR) = 1.49 to 1.70; all P < 0.05) but not stiffness. Longitudinally, BMLs present on T2-w FSE, T1-w GRE, and both MRI sequences were associated with worsening knee pain (β = 1.12 to 1.37, respectively; P < 0.05) and worsening stiffness (β = 0.45 to 0.52, respectively; all P < 0.05) but not worsening physical function limitation or total WOMAC. BMLs present on T2-w FSE, T1-w GRE, and both MRI sequences predicted site-specific cartilage defect progression (relative risk (RR) = 1.22 to 4.63; all P < 0.05) except at the medial tibial and inferior patellar sites. Lateral tibial and superior patellar BMLs present on T2-w FSE, T1-w GRE, and both MRI sequences predicted site-specific cartilage volume loss (β = −174.77 to −140.67; P < 0.05). BMLs present on T2-w FSE, T1-w GRE, and both MRI sequences were strongly associated with incident TKR. Conclusions: BMLs can be assessed on either T2-w FSE or T1-w GRE MRI sequence alone with no predictive advantage of performing both sequences, even though BMLs appear smaller on T1-w GRE MRI.

Is Climate Associated With Revision for Prosthetic Joint Infection After Primary TKA?

Climate factors have been shown to be associated with spontaneous musculoskeletal and some surgical site infections with increased rates of infection during warmer periods. To date, little research has been performed to determine if this phenomenon is associated with differences in the risk of revision for prosthetic joint infection (PJI) in primary TKA. (1) Does the rate of revision for early PJI within the first year after primary TKA differ between tropical and nontropical regions? (2) Is there a seasonal variation in the rate of revision for PJI? (3) Is the geographic and seasonal variation (if present) associated with the sex, age, and/or American Society of Anesthesiologists (ASA) grade of the patient? All 219,983 primary TKAs performed for osteoarthritis over a 5-year period (2011-2015) in the Australian Orthopaedic Association National Joint Replacement Registry were examined based on the month of the primary procedure to determine the rate of revision for PJI within 12 months. The data were analyzed to determine the differences in the risk of revision for PJI based on geographic region and season of the primary procedure adjusting for sex, age, and ASA grade of the patient. The early revision rate for PJI was higher in the tropical compared with the nontropical region of Australia (0.73% versus 0.37%; odds ratio [OR], 1.87; 95% confidence interval [CI], 1.44-2.42; p < 0.001). The tropical region of Australia demonstrated a seasonal variation in the rate of revision for PJI with a higher rate during the warmer monsoon wet season of summer and fall (summer/fall 0.98% versus winter/spring 0.51%; OR, 1.88; 95% CI, 1.12-3.16; p = 0.02). A seasonal variation was not seen in the nontropical region (OR, 1.03; 95% CI, 0.90-1.19; p = 0.64). The regional and seasonal changes were independent of sex, age, and ASA grade. Climate factors are associated with the risk of early revision for PJI in patients undergoing primary TKA with rates of such revisions approximately double in tropical regions compared with nontropical regions. Additionally, tropical regions demonstrate a seasonal variation with the risk of PJI doubling during the warmer, monsoonal wet season of summer and fall. These findings should be confirmed in further studies that can better control for possible confounding variables. The mechanism for this phenomenon is not clear, and further research into this subject is also indicated. Level III, therapeutic study.

The association between ambulatory activity, body composition and hip or knee joint replacement due to osteoarthritis: a prospective cohort study

To examine the association between ambulatory activity (AA), body composition measures and hip or knee joint replacement (JR) due to osteoarthritis. At baseline, 1082 community-dwelling older-adults aged 50-80 years were studied. AA was measured objectively using pedometer and body composition by dual-energy X-ray absorptiometry. The incidence of primary (first-time) JR was determined by data linkage to the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Log binomial regression with generalized estimating equations were used to estimate the risk of JR associated with baseline AA and body composition measures, adjusting for age, sex, X-ray disease severity, and pain. Over 13 years of follow-up, 74 (6.8%) participants had a knee replacement (KR) and 50 (4.7%) a hip replacement (HR). AA was associated with a higher risk of KR (RR 1.09/1000 steps/day, 95% CI 1.01, 1.16) and a lower risk of HR (RR 0.90/1000 steps/day, 95% CI 0.81, 0.99). Body mass index (BMI) (RR 1.07/kg/m2, 95% CI 1.03, 1.12), total fat mass (RR 1.03/kg, 95% CI 1.01, 1.06), trunk fat mass (RR 1.05/kg, 95% CI 1.00, 1.09), and waist circumference (RR 1.02/cm, 95% CI 1.00, 1.04) were associated with a higher risk of KR. Body composition measures were not associated with HR. An objective measure of AA was associated with a small increased risk of KR and a small reduced risk of HR. Worse body composition profiles were associated with KR, but not HR. Altogether this may suggest different causal pathways for each site with regard to habitual activity and obesity.

Clinical Faceoff: Instability After THA: The Potential Role of the Bearing Surface.

Clinical Faceoff: Instability After THA: The Potential Role of the Bearing Surface.

What Is the Long-term Survival for Primary THA With Small-head Metal-on-metal Bearings?

Large-head metal-on-metal (MoM) bearing hip replacements have been shown to have a much higher rate of revision than other bearing surfaces. However, small-head (≤ 32 mm) MoM bearing surfaces have been in use for many years with several reports of satisfactory mid- to long-term survivorship. It is unclear whether the long-term survival of small-head MoM devices will continue to be satisfactory or whether the same concerns seen with the large-head MoM devices will ultimately become more prevalent. We analyzed a large national registry to ask: (1) What is the 15-year Kaplan-Meier survivorship of primary conventional THA using small-head (≤ 32 mm) MoM bearing surfaces compared with large-head MoM bearing surfaces in primary THA? (2) Is there an increased rate of revision for adverse reaction to metal debris (ARMD) in this group of patients over time? The Australian Orthopaedic Association National Joint Replacement Registry longitudinally maintains data on all primary and revision joint arthroplasties with nearly 100% capture. We analyzed all conventional primary THAs performed from Registry inception in September 1999 until December 31, 2015, in patients with a diagnosis of osteoarthritis and using MoM bearing surfaces ≤ 32 mm in diameter, defined as small-head MoM. The study group included 4838 primary THA with ≤ 32-mm MoM bearing surfaces. There were 2506 (51.8%) male patients and the median age of patients undergoing THA with a small-head MoM bearing surface was 64 years (range, 20-92 years of age). The outcome measure was the cumulative percent revision defined as the time to first revision using Kaplan-Meier estimates of survivorship at 15 years; reasons for revision and type of revision were also examined. We specifically investigated whether there was an increased risk of revision for ARMD in this MoM group compared with all other bearing surfaces. We compared these results with large-head MoM THAs (femoral head size > 32 mm). The cumulative percent revision for small-head MoM designs at 15 years was 8.5% (95% confidence interval [CI], 7.3-9.9). The cumulative percent revision for large-head MoM at 14 years was 27.4% (95% CI, 24.8-30.2). Prostheses with a large-head MoM articulation have a higher rate of revision than small-head MoM bearing surfaces (hazard ratio after 6 years, 5.14; 95% CI, 4.1-6.5; p < 0.001). Over time, there was a gradual increase in the diagnosis of ARMD for small-head MoM and the cumulative incidence of revision for ARMD was 0.8% at 15 years. Despite survival that is substantially greater than that of large-head MoM THAs, there has been a marked decrease in the use of small-head MoM designs in our registry. Although the reasons for this are likely multifactorial, the increasing incidence of revisions for ARMD among small-head MoM THAs is concerning. Level III, therapeutic study.

Current Role of Computer Navigation in Total Knee Arthroplasty

BackgroundComputer-assisted surgical (CAS) navigation has been developed with the aim of improving the accuracy and precision of total knee arthroplasty (TKA) component positioning and therefore overall limb alignment. The historical goal of knee arthroplasty has been to restore the mechanical alignment of the lower limb by aligning the femoral and tibial components perpendicular to the mechanical axis of the femur and tibia. Despite over 4 decades of TKA component development and nearly 2 decades of interest in CAS, the fundamental question remains; does the alignment goal and/or the method of achieving that goal affect the outcome of the TKA in terms of patient-reported outcome measures and/or overall survivorship? The quest for reliable and reproducible achievement of the intraoperative alignment goal has been the primary motivator for the introduction, development, and refinement of CAS navigation. Numerous proprietary systems now exist, and rapid technological advancements in computer processing power are stimulating further development of robotic surgical systems. Three categories of CAS can be defined: image-based large-console navigation; imageless large-console navigation, and more recently, accelerometer-based handheld navigation systems have been developed. ConclusionA review of the current literature demonstrates that there are enough well-designed studies to conclude that both large-console CAS and handheld navigation systems improve the accuracy and precision of component alignment in TKA. However, missing from the evidence base, other than the subgroup analysis provided by the Australian Orthopaedic Association National Joint Replacement Registry, are any conclusive demonstrations of a clinical superiority in terms of improved patient-reported outcome measures and/or decreased cumulative revision rates in the long term. Few authors would argue that accuracy of alignment is a goal to ignore; therefore, in the absence of clinical evidence, many of the arguments against the use of large-console CAS navigation center on the prohibitive cost of the systems. The utilization of low-cost, handheld CAS navigation systems may therefore bridge this important gap, and over time, further clinical evidence may emerge.

Fellowship exit examination in orthopaedic surgery in the commonwealth countries of Australia, UK, South Africa and Canada. Are they comparable and equivalent? A perspective on the requirements for medical migration

ABSTRACTInternational migration of healthcare professionals has increased substantially in recent decades. In order to practice medicine in the recipient country, International Medical Graduates (IMG) are required to fulfil the requirements of their new countries medical registration authorities. The purpose of this project was to compare the final fellowship exit examination in Orthopaedic Surgery for the UK, Australia, Canada and South Africa.The curriculum of the Australian Orthopaedic Association (SET) was selected as a baseline reference. The competencies and technical modules specified in the training syllabus, as well as the specifics of the final fellowship examination as outlined in SET, were then compared between countries.Of the nine competencies outlined in SET, the curricula of the UK, South Africa and Canada were all compatible with the Australian syllabus, and covered 97.7%, 86% and 93%, respectively, of all competencies and sub-items. The final fellowship examinations of Australia, South Africa and the UK were all highly similar in format and content. The examination in Canada was substantially different, and had two written sessions but combined the oral and clinical component into a structured OSCE using standardized patients and the component included unmanned stations. There were no significant differences for completion certificate of training and/or board certification observed between these countries.The results of this study strongly suggest that core and technical competencies outlined in the training and education curriculum and the final fellowship examination in Orthopaedic Surgery in Australia, South Africa and the UK are compatible. Between country reciprocal recognition of these fellowship examinations should not only be considered by the relevant Colleges, but should also be regulated by the individual countries health practitioner registration boards and governing bodies.

The Infection Rate of Metal-on-Metal Total Hip Replacement Is Higher When Compared to Other Bearing Surfaces as Documented by the Australian Orthopaedic Association National Joint Replacement Registry.

Despite the well-documented decline in the use of metal-on-metal (MoM) implants over the last decade, there are still controversies regarding whether all MoM implants are created equally. Complications such as elevated serum metal ion levels, aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) and pseudotumours have all been well documented, but recent studies suggest increased risk of infection with MoM bearing surfaces. Most of these studies however have small patient numbers. The purpose of this study was to examine the cumulative incidence of revision for infection of MoM bearing surfaces in primary hip arthroplasty at a national and single-surgeon level. Data was collected from the Australian Orthopaedic Association National Joint Replacement Registry, which contains over 98% of all arthroplasties performed in Australia since 2001. The cumulative incidence of revision for infection was extracted at a national level and single-surgeon level. Two hundred seventy-six thousand eight hundred seventy-eight subjects were documented in the Australian registry. The 10-year cumulative percent revision for infection of MoM bearing surfaces in primary total hip replacement (THR) was 2.5% at a national level, compared to 0.8% for other bearing surfaces. The senior author contributed 1755 subjects with 7-year follow-up and a cumulative percent revision for infection of MoM bearing surfaces in primary THR of 36.9%, compared to 2.0% for other bearing surfaces. The cumulative percent of revision of MoM bearing surfaces is higher compared to other bearing surfaces; this is especially pronounced in cumulative percent of revision for infection. There was a higher cumulative percent of revision for infection in MoM bearings surfaces (in particular, large-head MoM) compared to other bearing surfaces at both the national and individual-surgeon level.

Geographic region, socioeconomic position and the utilisation of primary total joint replacement for hip or knee osteoarthritis across western Victoria: a cross-sectional multilevel study of the Australian Orthopaedic Association National Joint Replacement Registry.

Compared to urban residents, those in rural and regional areas often experience inequitable healthcare from specialist service providers, often due to geographical issues. We investigated associations between socioeconomic position (SEP), region of residence and utilisation of primary total knee replacement (TKR) and/or total hip replacement (THR) for osteoarthritis. As part of the Ageing, Chronic Disease and Injury study, we extracted data from the Australian Orthopaedic Association National Joint Replacement Registry (2011-2013) for adults that utilised primary TKR (n=4179; 56% female) and/or THR (n=3120; 54% female). Residential addresses were matched with the Australian Bureau of Statistics (ABS) 2011 census data: region of residence was defined according to local government areas (LGAs), and area-level SEP (quintiles) defined using an ABS-derived composite index. The ABS-determined control population (n=591,265; 51% female) excluded individuals identified as cases. We performed multilevel logistic regression modelling using a stratified two-stage cluster design. TKR was higher for those aged 70-79years (AOR 1.4 95%CI 1.3-1.5; referent=60-69years) and in the most advantaged SEP quintile (AOR 2.1, 95%CI 1.8-2.3; referent=SEP quintile 3); results were similar for THR (70-79years=AOR 1.7, 95%CI 1.5-1.8; SEP quintile 5=AOR 2.5, 95%CI 2.2-2.8). Total variances contributed by the variance in LGAs were 2% (SD random effects±0.28) and 3% (SD±0.32), respectively. Independent of small between-LGA differences in utilisation, and in contrast to the expected greater prevalence of osteoarthritis in disadvantaged populations, we report greater TKR and THR in more advantaged groups. Further research should investigate whether more advantaged populations may be over-serviced.