Survey of New Zealand Arthroplasty Surgeons on Surgeon-Level Outcome Reporting.

BACKGROUND: Surgeon-specific outcome monitoring has become increasingly prevalent over the last 3 decades. The New Zealand Orthopaedic Association monitors individual surgeon performance through 2 mechanisms: arthroplasty revision rates derived from the New Zealand Joint Registry and a practice visit program. Despite remaining confidential, surgeon-level outcome reporting remains contentious. The purpose of this survey was to evaluate the opinions of hip and knee arthroplasty surgeons in New Zealand on the perceived importance of outcome monitoring, current methods used to evaluate surgeon-specific outcomes, and potential improvements identified through literature review and discussion with other registries. METHODS: The survey consisted of 9 questions on surgeon-specific outcome reporting, using a five-point Likert scale, and 5 demographic questions. It was distributed to all current hip and knee arthroplasty surgeons. There were 151 hip and knee arthroplasty surgeons who completed the survey, a response rate of 50%. RESULTS: Respondents agreed that monitoring arthroplasty outcomes is important and that revision rates are an acceptable measure of performance. Reporting risk-adjusted revision rates and more recent timeframes were supported, as was including patient-reported outcomes when monitoring performance. Surgeons did not support public reporting of surgeon-level or hospital-level outcomes. CONCLUSION: The findings of this survey support the use of revision rates to confidentially monitor surgeon-level arthroplasty outcomes and suggest that concurrent use of patient-reported outcome measures would be acceptable.

The Strongest Oxford Knee Score Predictors of Subsequent Revision are "Overall Pain," "Limping When Walking," and "Knee Giving Way".

BACKGROUND: The Oxford Knee Score (OKS) is used to measure knee arthroplasty outcomes; however, it is unclear which questions are more relevant. Our aims were to (1) identify which OKS question(s) were the strongest predictors of subsequent revision and (2) compare the predictive ability of the "pain" and "function" domains. METHODS: All primary total knee arthroplasties (TKAs) and unicompartmental knee arthroplasties (UKAs) in the New Zealand Joint Registry between 1999 and 2019 with an OKS at 6 months (TKA n = 27,708; UKA n = 8,415), 5 years (TKA n = 11,519; UKA n = 3,365) or 10 years (TKA n = 6,311; UKA n = 1,744) were included. Prediction models were assessed using logistic regressions and receiver operating characteristic analyses. RESULTS: A reduced model with 3 questions ("overall pain," "limping when walking," "knee giving way") showed better diagnostic ability than full OKS for predicting UKA revision at 6 months (area under the curve [AUC]: 0.80 versus 0.78; P < .01) and 5 years (0.81 versus 0.77; P = .02), and comparable diagnostic ability for predicting TKA revision at all time points (6 months, 0.77 versus 0.76; 5 years, 0.78 versus 0.75; 10 years, 0.76 versus 0.73; all not significant), and UKA revision at 10 years (0.80 versus 0.77; not significant). The pain domain had better diagnostic ability for predicting subsequent revision for both procedures at 5 and 10 years. CONCLUSION: Questions on "overall pain", "limping when walking", and "knee giving way" were the strongest predictors of subsequent revision. Attention to low scores from these questions during follow-up may allow for prompt identification of patients most at risk of revision.

The advances in nanomedicine for bone and cartilage repair.

With the gradual demographic shift toward an aging and obese society, an increasing number of patients are suffering from bone and cartilage injuries. However, conventional therapies are hindered by the defects of materials, failing to adequately stimulate the necessary cellular response to promote sufficient cartilage regeneration, bone remodeling and osseointegration. In recent years, the rapid development of nanomedicine has initiated a revolution in orthopedics, especially in tissue engineering and regenerative medicine, due to their capacity to effectively stimulate cellular responses on a nanoscale with enhanced drug loading efficiency, targeted capability, increased mechanical properties and improved uptake rate, resulting in an improved therapeutic effect. Therefore, a comprehensive review of advancements in nanomedicine for bone and cartilage diseases is timely and beneficial. This review firstly summarized the wide range of existing nanotechnology applications in the medical field. The progressive development of nano delivery systems in nanomedicine, including nanoparticles and biomimetic techniques, which are lacking in the current literature, is further described. More importantly, we also highlighted the research advancements of nanomedicine in bone and cartilage repair using the latest preclinical and clinical examples, and further discussed the research directions of nano-therapies in future clinical practice.

Surgical Helmet Systems Are Associated With a Lower Rate of Prosthetic Joint Infection After Total Knee Arthroplasty: Combined Results From the New Zealand Joint Registry and Surgical Site Infection Improvement Programme.

BACKGROUND: This study aimed to identify the risk factors, in particular the use of surgical helmet systems (SHSs), for prosthetic joint infection (PJI) after total knee arthroplasty (TKA). Data recorded by the New Zealand Surgical Site Infection Improvement Programme (SSIIP) and the New Zealand Joint Registry (NZJR) were combined and analyzed. METHODS: Primary TKA procedures performed between July 2013 and June 2018 that were recorded by both the SSIIP and NZJR were analyzed. Two primary outcomes were measured: (1) PJI within 90 days as recorded by the SSIIP and (2) revision TKA for deep infection within 6 months as recorded by the NZJR. Univariate and multivariate analyses were performed to identify risk factors for both outcomes with results considered significant at P < .05. RESULTS: A total of 19,322 primary TKAs were recorded by both databases in which 97 patients had a PJI within 90 days as recorded by the SSIIP (0.50%), and 90 patients had a revision TKA for deep infection within 6 months (0.47%) as recorded by the NZJR. An SHS was associated with a lower rate of PJI (adjusted odds ratio [OR] = 0.50, P = .008) and revision for deep infection (adjusted OR = 0.55, P = .022) than conventional gowning. Male sex (adjusted OR = 2.6, P < .001) and an American Society of Anesthesiologists score >2 were patient risk factors for infection (OR = 2.63, P < .001 for PJI and OR = 1.75, P = .017 for revision for deep infection). CONCLUSION: Using contemporary data from the SSIIP and NZJR, the use of the SHS was associated with a lower rate of PJI after primary TKA than conventional surgical gowning. Male sex and a higher American Society of Anesthesiologists score continue to be risk factors for infection.

Ballistic trauma caused by military rifles: experimental study based on synthetic skull proxies.

Rifles are often involved in violent deaths such as homicide and suicide. Consequently, expert knowledge and experimental forensic investigations are important to clarify the nature of ballistic trauma when applied to the human head and neurocranium. This study investigated differences in entrance wound morphology with Synbone® spheres which are described as being comparable to human flat bones. A series of ballistic experiments were conducted using two different rifle calibers (5.56 × 45 mm and 7.62 × 39 mm Full Metal Jacket (FMJ)). Synbone® spheres were used for close-range 0.3 m simulated executions as well as at 25 m and 35 m to simulate urban and military engagements. Results were compared with previously published experimental studies using similar military ammunition. In our study, entry wound morphology closely resembles real forensic cases compared to exit wound and overall shape morphology independently of the distance and the caliber. Circumferential delamination was clearly visible with full metal jacket (FMJ) rounds, yielding similar damage pattern morphology to the human crania. This study documented the presence of hydraulic burst or shock in all ten rounds from all three distances. Krönlein shots were also observed in some cases. Synbone® spheres constitute an acceptable synthetic surrogate for ballistic experiments. The present study offers new initial data on the behavior of Synbone® proxies in ballistic testing of military ammunitions; FMJ gunshot injuries to the human head, for distances that have not previously been published, suggesting that efficient tests can take place under these conditions. Further research on experimental ballistics with a larger number of controlled factors and multiple repetitions is recommended to verify the results of this pilot study before applied in forensic simulations.

Validation of Roebuck 1518 synthetic chamois as a skin simulant when backed by 10% gelatin.

INTRODUCTION: Synthetic skin simulants are used both in wound ballistics and forensic investigations and should display similar mechanical properties to human tissue and therefore need to be validated. It is recognised that skin simulants may have a significantly different performance when different backing combinations are used; therefore, it is essential to specify and control the backing material. Roebuck 1518 synthetic chamois (RBK) backed by 20% ballistic gelatin has been validated as a suitable skin simulant; this study looks at validating the RBK simulant when backed by 10% ballistic gelatin. METHODS: Two layers of RBK synthetic chamois backed by calibrated 10% ballistic gelatin were placed onto the long face of the block and secured. Steel spheres with various sectional densities were fired using a custom-made gas gun to determine the V50 of the simulants and compared with the predicted V50. RESULTS: The results demonstrate that for a sectional density between 2.1 and 6.6 g/cm2, the skin simulants backed by 10% gelatin are within the 35% error bounds predicted by James' patent equation. All samples had a close fit to the regression line (R2 = 0.9738), and a Spearman rho test indicates that there is a "strong" negative correlation between sectional density and the V50 (Rs =- 0.957, p = 0.00). CONCLUSIONS: This validation study confirms that RBK synthetic simulant backed by 10% gelatin is a suitable skin simulant when testing non-deforming projectiles with sectional densities ranging from 2.1 to 6.6 g/cm2. A predictive trend line also indicates that the skin simulant is suitable for non-deforming projectiles with sectional densities ranging from 0.6 to 20 g/cm2 although this needs to be confirmed.

A study into the viability of Synbone® as a proxy for Sus scrofa (domesticus) ribs for use with 5.56-mm open tip match ammunition in ballistic testing.

BACKGROUND: In ballistic testing and forensic reconstruction, there is a need to use repeatable and consistent simulants. While synthetic bone is mechanically similar to human bone, it does not have the same viscoelastic properties. In high-energy impact such as ballistic impacts, bone acts as a stiff, brittle material and fails instantaneously. Therefore, a suitable simulant for use in ballistic testing should have comparable energy deposition to mammalian bones. This preliminary study aims to determine if Synbone® could be a viable proxy for Sus scrofa (domesticus) ribs in ballistic testing. METHODOLOGY: Three thickness of Synbone® were embedded into 10% ballistic gelatin and shot using 5.56-mm ammunition. The models were then analysed to compare the Synbone® to a previous Sus scrofa (domesticus) rib study and focused on the number of fragments within the block, energy deposition, onset of yaw, angle of deviation, the temporary cavity as a percentage of the block and the depth to the temporary cavity centre, depth to maximum gelatin disruption and the permanent wound channel, including shear planes and wound tract diameter. RESULTS: There was no significant difference in the metrics that were compared between Sus scrofa (domesticus) ribs and the three thicknesses of Synbone®, except for a significant difference in the depth to maximum gelatin disruption between the 6 mm (p = 0.009) and 12 mm plate (p = 0.007) and the Sus scrofa (domesticus) ribs. CONCLUSION: This study indicates that the 5-mm Synbone® plate is a suitable proxy for Sus scrofa (domesticus) ribs for use with 5.56-mm OTM ammunition in ballistic testing.

Associations between comorbidity and quality of life outcomes after total joint replacement.

PURPOSE: We examined associations between self-reported and clinician-assessed comorbidity and quality of life (QOL) outcomes after hip and knee replacement. METHODS: This is a cross-sectional, questionnaire-based national survey. Participants aged 45 years or older (n = 409) were recruited from the New Zealand Joint Registry six months after a total hip (THR), total knee (TKR) or unicompartmental knee replacement (UKR). The main outcome QOL was measured using an 8-item short form of the World Health Organisation Quality of Life (WHOQOL-Bref) questionnaire six months following joint replacement surgery. The WHOQOL is a generic and non-health condition specific measure of QOL. RESULTS: Participants were on average 68 years of age, with more men (54%) than women (46%). Number of coexisting conditions and body mass index were correlated with age, pain and function scores, and QOL (p < 0.01), but not with each other. Linear regression analyses showed that comorbidities such as number of comorbid conditions and BMI had moderate associations with QOL outcomes. CONCLUSION: This study showed that general QOL outcomes following hip and knee joint replacement, while generally high, were associated with comorbidity burden and BMI. Future prospective research examining change in QOL before and following surgery would help to advance understandings of the various factors that contribute to patient satisfaction with their joint replacement.

International variation in distribution of ASA class in patients undergoing total hip arthroplasty and its influence on mortality: data from an international consortium of arthroplasty registries.

Background and purpose - A challenge comparing outcomes from total hip arthroplasty between countries is variation in preoperative characteristics, particularly comorbidity. Therefore, we investigated between-country variation in comorbidity in patients based on ASA class distribution, and determined any variation of ASA class to mortality risk between countries.Patients and methods - All arthroplasty registries collecting ASA class and mortality data in patients with elective primary THAs performed 2012-2016 were identified. Survival analyses of the influence of ASA class on 1-year mortality were performed by individual registries, followed by meta-analysis of aggregated data.Results - 6 national registries and 1 US healthcare organization registry with 418,916 THAs were included. There was substantial variation in the proportion of ASA class III/IV, ranging from 14% in the Netherlands to 39% in Finland. Overall, 1-year mortality was 0.93% (95% CI 0.87-1.01) and increased from 0.2% in ASA class I to 8.9% in class IV. The association between ASA class and mortality measured by hazard ratios (HR) was strong in all registries even after adjustment for age and sex, which reduced them by half in all registries. Combined adjusted HRs were 2.0, 6.1, and 22 for ASA class II-IV vs. I, respectively. Associations were moderately heterogeneous across registries.Interpretation - We observed large variation in ASA class distribution between registries, possibly explained by differences in background morbidity and/or international variation in access to surgery. The similar, strong mortality trends by ASA class between countries enhance the relevance of its use as an indicator of comorbidity in international registry studies.

A study into the viability of Synbone® as a proxy for Sus scrofa (domesticus) ribs for use with 7.62 × 51 mm Full Metal Jacket ammunition in ballistic testing.

Forensic reconstructions and ballistic testing requires the use of consistent and repeatable simulants. Synthetic bone has been developed to be mechanically similar to human bone; however, it does not have the same viscoelastic properties. Bone acts as brittle and stiff material and fails instantly under high-energy events such as ballistic impacts. Consequently, bone simulants for use in ballistic testing should show comparable energy deposition to mammalian bones. This study aims to determine if Synbone® flat plates could be a viable proxy for Sus scrofa (domesticus) ribs in ballistic testing with 7.62 × 51 mm Full Metal Jacket ammunition. 5 mm, 6 mm and 12 mm quartered Synbone® plates were embedded into 10% ballistic gelatin and shot using 7.62 mm ammunition. The models were then analysed to compare the Synbone® to a previous Sus Scrofa (domesticus) rib study and focused on energy deposition, the number of fragments within the block, angle of deviation, onset of yaw, the temporary cavity, and the permanent wound channel. No significant difference was seen between the Sus Scrofa (domesticus) and the 5 mm Sybone®. There were significant differences observed between Sus Scrofa (domesticus) ribs and 6 mm Synbone® for the number of fragments, energy deposition and projectile tract diameter, and significant differences seen between Sus scrofa (domesticus) ribs and 12 mm Synbone® for the depth of onset of yaw, energy deposition and projectile tract diameter. This study indicates that the 5 mm Synbone® plate is a suitable proxy for Sus scrofa (domesticus) ribs for use with 7.62 × 51 mm FMJ ammunition in ballistic testing.

Are Lipped Polyethylene Liners Associated with Increased Revision Rates in Patients with Uncemented Acetabular Components? An Observational Cohort Study.

BACKGROUND: Recurrent dislocation after THA remains a serious complication that carries with it a high risk of revision surgery. Previous studies have shown reduced dislocation rates with the use of lipped polyethylene (PE) liners in modular uncemented acetabular components, but there may be increased wear because of impingement, which may lead to aseptic loosening in the longer term; whether the aggregate benefit of lipped PE liners outweighs the risks associated with their use remains controversial. QUESTIONS/PURPOSES: We used data from the New Zealand Joint Registry to (1) compare Kaplan-Meier survival rates, (2) rates of revisions for dislocation between neutral and lipped PE liners, and (3) revision rates for aseptic loosening for the four most commonly used modular uncemented cups. METHODS: We used data from the New Zealand Joint Registry (NZJR) to identify 31,247 primary THAs using the four most commonly used uncemented modular acetabular implants from January 1, 1999 to December 31, 2018. The lipped liner group comprised 49% males (9924 of 20,240) compared with 42% (4669 of 11,007) in the neutral group (p < 0.001); 96% (19,382 of 20,240) of patients in the liner group had OA versus 95% (10,450 of 11,007) in the neutral group (p < 0.001). There was no difference in other patient characteristics such as age (mean 66.9 years), BMI (mean 29 ± 6 kg/m) and American Society of Anesthesiologists grade. The mean follow-up was 5.1 years (SD 3.9) and longest follow-up 19.3 years. The NZJR has more than 96% capture rate and data entry is a mandatory requirement of members of the New Zealand Orthopaedic Association. Kaplan-Meier survival rates were compared between 20,240 lipped and 11,007 neutral PE liners. Highly cross-linked polyethylene was used in 99% of lipped liner cups and 85% of neutral liner cups. Associated hazard ratios were calculated using a Cox regression analysis with a Kaplan-Meier revision-free estimates plot. RESULTS: The Kaplan-Meier survival at 10 years for lipped PE liners was 96% (95% confidence interval 95.4 to 96.2) and for neutral liners 95% (95% CI 94.7 to 95.9). After controlling for age, gender approach, femoral head size, and the use of image guidance, the all-cause revision risk was greater for neutral PE liners than that for lipped PE liners (HR 1.17 [95% CI 1.06 to 1.36]; p = 0.032). There was a higher risk of revision for dislocation in those with neutral PE liners than in those with lipped liners (HR 1.84 [95% CI 1.41 to 2.41]; p < 0.001) but no difference in the revision rate for aseptic acetabular component loosening (HR 0.85 [95% CI 0.52 to 1.38]; p = 0.511). CONCLUSIONS: The use of a lipped PE liner is not associated with a higher rate of aseptic loosening in patients who undergo primary THA compared with a neutral PE liner. Lipped PE liners are associated with lower rates of dislocation and lower all-cause revision rates without any increased association with revision rates for wear and aseptic loosening. LEVEL OF EVIDENCE: Level III, therapeutic study.

Knee replacement.

Knee replacement surgery is one of the most commonly done and cost-effective musculoskeletal surgical procedures. The numbers of cases done continue to grow worldwide, with substantial variation in utilisation rates across regions and countries. The main indication for surgery remains painful knee osteoarthritis with reduced function and quality of life. The threshold for intervention is not well defined, and is influenced by many factors including patient and surgeon preference. Most patients have a very good clinical outcome after knee replacement, but multiple studies have reported that 20% or more of patients do not. So despite excellent long-term survivorship, more work is required to enhance this procedure and development is rightly focused on increasing the proportion of patients who have successful pain relief after surgery. Changing implant design has historically been a target for improving outcome, but there is greater recognition that improvements can be achieved by better implantation methods, avoiding complications, and improving perioperative care for patients, such as enhanced recovery programmes. New technologies are likely to advance future knee replacement care further, but their introduction must be regulated and monitored with greater rigour to ensure patient safety.

Despite Improved Survivorship of Uncemented Fixation in Total Knee Arthroplasty for Osteoarthritis, Cemented Fixation Remains the Gold Standard: An Analysis of a National Joint Registry.

BACKGROUND: Total knee arthroplasty (TKA) numbers are increasing worldwide. While cement fixation for both femoral and tibial components is commonly used, alternatives include hybrid and uncemented TKAs. This study aimed to evaluate survivorship, revision rates, and patient-reported outcomes for cemented, hybrid, and uncemented TKAs using New Zealand Joint Registry (NZJR) data. METHODS: NZJR data relating to all TKAs performed during the 19 years up to the end of December 2017 were analyzed. Outcomes were assessed using prosthesis survivorship data (including reasons for revision) and Oxford scores at 6 months, 5 years, and 10 years postoperatively. RESULTS: A total 96,519 primary TKAs were performed during the period examined. Most (91.5%) were fully cemented with 4.8% hybrid and 3.7% uncemented. Mean Oxford scores at 6 months were highest in cemented and lowest in uncemented TKAs (P < .001). However, this was not clinically significant. There was no difference at 5 or 10 years. Ten-year survival rates were 97%, 94.5%, and 95.8% for cemented, uncemented, and hybrid TKAs, respectively. Revision rates were 0.47, 0.74, and 0.52 per 100 component years for cemented, uncemented, and hybrid prostheses, respectively. The revision rate for uncemented prostheses compared with cemented was higher (P < .001). When stratified by age group, there were differences in survival rates between cemented and uncemented groups (P = .001) and hybrid and uncemented groups (P = .038) in patients aged <55 years; between cemented and uncemented groups in those aged 55-64 years (P = .031); and between cemented and hybrid groups in those aged >75 years (P = .004). CONCLUSION: Uncemented TKAs had similar patient-reported outcomes but higher revision rates and worse survivorship compared with hybrid or fully cemented TKAs.

Growth Factor Delivery Systems for Tissue Engineering and Regenerative Medicine.

Growth factors (GFs) are often a key component in tissue engineering and regenerative medicine approaches. In order to fully exploit the therapeutic potential of GFs, GF delivery vehicles have to meet a number of key design criteria such as providing localized delivery and mimicking the dynamic native GF expression levels and patterns. The use of biomaterials as delivery systems is the most successful strategy for controlled delivery and has been translated into different commercially available systems. However, the risk of side effects remains an issue, which is mainly attributed to insufficient control over the release profile. This book chapter reviews the current strategies, chemistries, materials and delivery vehicles employed to overcome the current limitations associated with GF therapies.

Untangling chronic pain and post-concussion symptoms: the significance of depression.

OBJECTIVES: Post-concussion-like symptoms (PCS) are common in patients without a history of brain injury, such as those with chronic pain (CP). This exploratory study examined neuro-cognitive and psychological functioning in patients with PCS following mild traumatic brain injury (mTBI) or CP, to assess unique and overlapping phenomenology. METHODS: In this case-control study, participants (n = 102) with chronic symptoms after mTBI (n = 45) were matched with mTBI recovered (n = 31) and CP groups (n = 26), on age, gender, ethnicity and education. Psychological status, cognitive functioning, health symptoms, beliefs and behaviours were examined. RESULTS: Participants who had not recovered from an mTBI and participants with CP did not differ in terms of PCS symptoms, quality of life, distress or illness behaviours, however, the CP group endorsed fewer subjective cognitive problems, more negative expectations about recovery and more distress (p < 0.05). On cognitive testing participants who had not recovered from an mTBI demonstrated greater difficulties with attention (p < 0.01) although differences disappeared when depression was controlled in the analyses. CONCLUSIONS: Unique patterns associated with each condition were evident though caution is required in attributing PCS and cognitive symptoms to a brain injury in people with mTBI presenting with chronic pain and/or depression. Psychological constructs such as illness and recovery beliefs appear to be important to consider in the development of treatment interventions.

The Impact of Patient and Surgical Factors on the Rate of Postoperative Infection After Total Hip Arthroplasty-A New Zealand Joint Registry Study.

BACKGROUND: Periprosthetic joint infection (PJI) is a devastating complication after total hip arthroplasty (THA). The potential to define and modify risk factors for infection represents an important opportunity to reduce the incidence of PJI. This study uses New Zealand Joint Registry data to identify independent risk factors associated with PJI after primary THA. METHODS: Data on 91,585 THAs performed between 2000 and 2014 were analyzed. Factors associated with revision for PJI within 12 months were identified using univariate and multivariate analyses. RESULTS: Revision rates for PJI were 0.15% and 0.21% at 6 and 12 months, respectively. Multivariate analysis showed significant associations with the American Society of Anesthesiologists grade (odds ratio [OR] 6.13, 95% confidence interval [CI] 1.28-29.39), severe or morbid obesity (OR 2.15, CI 1.01-4.60 and OR 3.73, CI 1.49-9.39), laminar flow ventilation (OR 1.98, CI 1.38-2.85), consultant-supervised trainee operations (OR 1.94, CI 1.22-3.08), male gender (OR 1.68, CI 1.23-2.30) and anterolateral approach (OR 1.62, CI 1.11-2.37). Procedures performed in the private sector were protective for revision for infection (OR 0.68, CI 0.48-0.96). CONCLUSIONS: The PJI risk profile for patients undergoing THA is constituted of a complex of patient and surgical factors. Several patient factors had strong independent associations with revision rates for PJI. Although surgical factors were less important, these may be more readily modifiable in practice.

Quantitative imaging of excised osteoarthritic cartilage using spectral CT.

OBJECTIVES: To quantify iodine uptake in articular cartilage as a marker of glycosaminoglycan (GAG) content using multi-energy spectral CT. METHODS: We incubated a 25-mm strip of excised osteoarthritic human tibial plateau in 50 % ionic iodine contrast and imaged it using a small-animal spectral scanner with a cadmium telluride photon-processing detector to quantify the iodine through the thickness of the articular cartilage. We imaged both spectroscopic phantoms and osteoarthritic tibial plateau samples. The iodine distribution as an inverse marker of GAG content was presented in the form of 2D and 3D images after applying a basis material decomposition technique to separate iodine in cartilage from bone. We compared this result with a histological section stained for GAG. RESULTS: The iodine in cartilage could be distinguished from subchondral bone and quantified using multi-energy CT. The articular cartilage showed variation in iodine concentration throughout its thickness which appeared to be inversely related to GAG distribution observed in histological sections. CONCLUSIONS: Multi-energy CT can quantify ionic iodine contrast (as a marker of GAG content) within articular cartilage and distinguish it from bone by exploiting the energy-specific attenuation profiles of the associated materials. KEY POINTS: • Contrast-enhanced articular cartilage and subchondral bone can be distinguished using multi-energy CT. • Iodine as a marker of glycosaminoglycan content is quantifiable with multi-energy CT. • Multi-energy CT could track alterations in GAG content occurring in osteoarthritis.

Survivorship of Total Hip Joint Replacements Following Isolated Liner Exchange for Wear.

BACKGROUND: Liner exchange for articular component wear in total hip joint replacements (THJRs) is a common procedure, often thought to be benign with reliable outcomes. Recent studies, however, suggest high failure rates of liner exchange revisions with significant complications. The primary aim of this study was, therefore, to analyze the survivorship of isolated liner exchange for articular component wear, and secondarily to assess the influence of patient demographics (gender, age, and American Society of Anaesthesiologists [ASA] ratings) on rerevisions following isolated liner exchange for wear. METHODS: A retrospective review of the 15-year New Zealand Joint Registry (1999-2014) was performed, analyzing the outcomes of isolated liner exchange for articular component wear. The survivorship as defined as rerevision with component exchange was determined and 10-year Kaplan-Meier survivorship curves were constructed. These revision rates were compared to age, gender, and ASA rating groups using a log-rank test. RESULTS: The 10-year survivorship of THJR following liner exchange revision for liner wear was 75.3%. If a rerevision was required, the median time to rerevision was 1.33 years with a rerevision rate of 3.33 per 100 component years (95% confidence interval 2.68-4.08/100 component years). The principle reasons for rerevision were dislocation (48.4%) and acetabular component loosening (20.9%). There was no statistically significant difference in rerevision rates based on gender, age categories, or ASA scores. CONCLUSION: THJR isolated liner exchange for liner wear is not a benign procedure with a survivorship of 75.3% at 10 years. Surgeons contemplating liner exchange revisions should be cognisant of this risk and should adequately assess component position and stability preoperatively.

Evaluating quality of life outcomes following joint replacement: psychometric evaluation of a short form of the WHOQOL-Bref.

PURPOSE: Reducing participant burden is important in health research and clinical assessment. We examined the psychometric properties of the EUROHIS-QOL 8-item index, a short version of the 26-item World Health Organisation Quality of Life questionnaire (WHOQOL-Bref), in a sample of people receiving joint replacement surgery. METHODS: Participants (n = 1008) completed the WHOQOL-Bref at either 6, 12, 24 or 60 months after hip or knee replacement. The factor structure, differential item functioning (DIF) and unidimensionality of the EUROHIS-QOL 8-item index were examined using exploratory and confirmatory factor analyses and Rasch analyses. Convergent validity was examined using correlations with the parent measure and other patient-reported outcome measures (Oxford scores, Western Ontario and McMaster Universities Osteoarthritis Index). Discriminant validity was assessed between groups reporting high versus low pain and function, and by joint replaced. RESULTS: The measure demonstrated high internal consistency (α = 0.86), adequate convergent (r = 0.47-0.82, p < 0.001) and discriminant validity (p < 0.001). Factor and Rasch analyses supported a unidimensional structure. However, there were also indications of multidimensionality, with support for a two-factor model focusing on general health and function, and psychosocial aspects of QOL. There was minimal evidence of DIF, with just one item evaluating energy level showing DIF for age. CONCLUSIONS: The EUROHIS-QOL 8-item index demonstrated adequate properties as a unidimensional scale and as a two-factor scale evaluating general health and function, and psychosocial aspects of quality of life. It is low on clinical and participant burden, showed minimal ceiling effects and showed good concurrent and discriminant validity.

Does a titanium-coated polyethylene press-fit cup give reliable midterm results?

BACKGROUND: Uncemented acetabular components have demonstrated low revision rates and high patient satisfaction but with concerns regarding increased costs compared with monoblock cups. Some newer lower-cost uncemented monoblock options have become available in the last decade, but limited data are available on their performance. QUESTIONS/PURPOSES: (1) Does an uncemented, titanium-backed all-polyethylene acetabular cup provide reliable fixation? (2) What is the frequency and what are the causes for revision with this cup? METHODS: Between 2004 and 2008, we elected to use an uncemented, titanium-backed all-polyethylene acetabular cup in older patients with limited physical demands. We performed 615 hip replacements in 550 patients with greater than 5 years of clinical and radiographic followup. When patients who were dead (80 hips in 75 patients), lost to followup (98 hips in 93 patients), or revised (three hips in three patients) were excluded, there were 434 hips in 379 patients for comparison of the postoperative and 5-year radiographs. Two observers not involved in the index surgical procedures (NH, HS) assessed radiographs for signs of migration or loosening. Some degree of early movement sometimes is seen before cup stabilization; however, to be conservative, we defined cups with greater than 3° of change of position (even if they subsequently stabilized) as potentially at risk and report them separately. Revision surgery, time from the index procedure, and the reason for revision were recorded from the New Zealand Joint Registry. RESULTS: By 5 years there was a median change in inclination of 2° (range, 0°-13°; 95% confidence interval [CI], 2.0-2.4; p < 0.001) and 2° of anteversion (range, 0°-11°; 95% CI, 2.0-2.4; p < 0.001). Although at last followup all cups appeared to have stabilized with no radiolucent lines or medial migration, 22% of the cups (94 of 434) had moved more than 3° and so were deemed to be potentially at risk. There were 11 revision procedures (of 429 hips; 2.5%) of which six were for recurrent dislocation, four for femoral fracture, and one for femoral loosening to give an overall all-cause revision rate for all components of 0.25 per 100 component years (95% CI, 0.13-0.43). No revisions were performed for acetabular loosening. CONCLUSIONS: The short- to medium-term results of this all-polyethylene monoblock cup demonstrated a low frequency of revision. However, 94 cups were identified as potentially at risk based on movement of > 3° before apparent stabilization. Although those patients seem to be doing well enough now, the current duration of followup may not be sufficient to know that these cups will be durable, because other ongrowth designs have demonstrated a high frequency of late failure after apparent early success. LEVEL OF EVIDENCE: Level IV, therapeutic study.