Assessing the Clinical Value of Objective and Patient-Reported Audiovestibular Outcome Measures in the Risk Estimation of Systemic Cobalt Toxicity for Patients With a Metal-on-Metal Hip Implant.

OBJECTIVES: Based on limited evidence from case reports and small cohort studies of metal-on-metal (MoM) hip implant patients with presumed systemic cobalt (Co) toxicity, and a few animal studies on Co-induced damage to the otovestibular system, it was hypothesised that Co exhibits an ototoxic potential alongside other systemic manifestations. Preliminary investigations from our research group in MoM patients confirmed this assumption for the auditory system, whereas no signs of Co-induced vestibular impairment were detected, and a clear dose-response relationship between the auditory function and the blood Co levels was lacking. Therefore, the current study aimed to extend and validate these findings in a larger sample of MoM patients and control subjects, to explore the potential clinical value of audiovestibular outcome measures in the risk estimation of systemic Co toxicity in this patient population. DESIGN: Fifty patients (32 to 68 years) with a primary unilateral/bilateral MoM hip implant were matched for age, gender, and noise exposure to 50 nonimplanted control subjects. Both groups underwent the same protocol, consisting of an objective auditory [i.e., conventional and high-frequency audiometry, transient-evoked and distortion (TEOAEs and DPOAEs), auditory brainstem responses] and vestibular (i.e., cervical and ocular vestibular evoked myogenic potentials, horizontal and vertical video head impulse tests) test battery, a questionnaire inquiring auditory, balance, and general neurological symptoms, and a blood sample collection to determine the plasma Co concentration. RESULTS: The auditory test battery presented consistently higher audiometric thresholds in the MoM patient group, with group differences ranging from 2.1 to 5.7 dB in the lower frequencies (0.25 to 6.0 kHz) and from 4.6 to 9.3 dB in the high frequencies (8.0 to 14.0 kHz). Group differences at high frequencies were statistically significant ( p ≤ 0.001). Additionally, significantly lower TEOAE ( p = 0.009) and DPOAE ( p < 0.001) amplitudes were observed in the MoM patients when the better ear was included in the analysis, and more absent TEOAE and DPOAE responses were found between 1.0 and 4.0 kHz (0.008 ≤ p ≤ 0.039). Within the vestibular test battery, the MoM patients showed longer N1 and P1 ocular vestibular evoked myogenic potentials latencies for the left ear, and lower video head impulse test gains for the left anterior and right posterior semicircular canals (0.005 ≤ p ≤0.035). The patient-reported (questionnaire) outcome delivered no significant group differences ( p > 0.01). Six patients had elevated Co levels according to our local institutional threshold (>4 or 5 µg/l for unilateral or bilateral MoM hip implants, resp.), but their audiovestibular outcome measures did not differ significantly from those of the other patients. CONCLUSIONS: Corresponding to our preliminary investigations, the results indicate possibly Co-induced (predominantly high-frequency) auditory impairment, probably triggered by toxic damage to the cochlear structures. However, the low mean difference values, the lack of group differences for the patient-reported outcome measures, and the lack of any relationship with the blood Co levels strongly reduce the clinical relevance of these findings. Therefore, the risk of Co-induced ototoxic impairment is considered to be clinically negligible for the majority of MoM hip implant patients, and the use of auditory tests in the risk estimation of systemic Co toxicity should be decided on a case-by-case basis.

The concept of justifiable healthcare and how big data can help us to achieve it.

Over the last decades, the face of health care has changed dramatically, with big improvements in what is technically feasible. However, there are indicators that the current approach to evaluating evidence in health care is not holistic and hence in the long run, health care will not be sustainable. New conceptual and normative frameworks for the evaluation of health care need to be developed and investigated. The current paper presents a novel framework of justifiable health care and explores how the use of artificial intelligence and big data can contribute to achieving the goals of this framework.

The ototoxic potential of cobalt from metal-on-metal hip implants: a pilot study on the patient-reported auditory, vestibular, and general neurological outcome.

OBJECTIVE: This study aimed to systematically investigate the ototoxic potential of cobalt in patients with a metal-on-metal (MoM) hip implant, using objective auditory and vestibular assessments and a questionnaire. The results of the objective evaluation were published previously, whereas the current study focused on the questionnaire outcome and its relationship to the blood cobalt level. Design and study sample: Twenty patients (33-65 years) with a primary MoM hip implant and 20 non-implanted control subjects, matched for age, gender, and noise exposure, received a questionnaire to evaluate the presence of several hearing and balance symptoms (part 1) and general neurological issues (part 2). RESULTS: Concerning part 1, the proportion of auditory-related symptoms in general (p = 0.022) and tinnitus (p = 0.047) was significantly higher in the MoM patient group, whereas no group difference was found for hyperacusis, increased listening effort, and decreased speech understanding. Concerning part 2, no significant group differences were detected. Within the MoM patient group, the questionnaire outcome was not significantly different between the low-exposure and high-exposure subgroups according to the blood Co level. CONCLUSIONS: In line with our previous study, these results potentially imply Co-induced impairment to the auditory system, despite the lack of a clear dose-response relationship.

The Ototoxic Potential of Cobalt From Metal-on-Metal Hip Implants: Objective Auditory and Vestibular Outcome.

OBJECTIVES: During the past decade, the initial popularity of metal-on-metal (MoM) hip implants has shown a progressive decline due to increasingly reported implant failure and revision surgeries. Local as well as systemic toxic side effects have been associated with excessive metal ion release from implants, in which cobalt (Co) plays an important role. The rare condition of systemic cobaltism seems to manifest as a clinical syndrome with cardiac, endocrine, and neurological symptoms, including hearing loss, tinnitus, and imbalance. In most cases described in the literature, revision surgery and the subsequent drop in blood Co level led to (partial) alleviation of the symptoms, suggesting a causal relationship with Co exposure. Moreover, the ototoxic potential of Co has recently been demonstrated in animal experiments. Since its ototoxic potential in humans is merely based on anecdotal case reports, the current study aimed to prospectively and objectively examine the auditory and vestibular function in patients implanted with a MoM hip prosthesis. DESIGN: Twenty patients (15 males and 5 females, aged between 33 and 65 years) implanted with a primary MoM hip prosthesis were matched for age, gender, and noise exposure to 20 non-implanted control subjects. Each participant was subjected to an extensive auditory (conventional and high-frequency pure tone audiometry, transient evoked and distortion product otoacoustic emissions [TEOAEs and DPOAEs], auditory brainstem responses [ABR]) and vestibular test battery (cervical and ocular vestibular evoked myogenic potentials [cVEMPs and oVEMPs], rotatory test, caloric test, video head impulse test [vHIT]), supplemented with a blood sample collection to determine the plasma Co concentration. RESULTS: The median [interquartile range] plasma Co concentration was 1.40 [0.70, 6.30] µg/L in the MoM patient group and 0.19 [0.09, 0.34] µg/L in the control group. Within the auditory test battery, a clear trend was observed toward higher audiometric thresholds (11.2 to 16 kHz), lower DPOAE (between 4 and 8 kHz), and total TEOAE (1 to 4 kHz) amplitudes, and a higher interaural latency difference for wave V of the ABR in the patient versus control group (0.01 ≤ p < 0.05). Within the vestibular test battery, considerably longer cVEMP P1 latencies, higher oVEMP amplitudes (0.01 ≤ p < 0.05), and lower asymmetry ratio of the vHIT gain (p < 0.01) were found in the MoM patients. In the patient group, no suggestive association was observed between the plasma Co level and the auditory or vestibular outcome parameters. CONCLUSIONS: The auditory results seem to reflect signs of Co-induced damage to the hearing function in the high frequencies. This corresponds to previous findings on drug-induced ototoxicity and the recent animal experiments with Co, which identified the basal cochlear outer hair cells as primary targets and indicated that the cellular mechanisms underlying the toxicity might be similar. The vestibular outcomes of the current study are inconclusive and require further elaboration, especially with respect to animal studies. The lack of a clear dose-response relationship may question the clinical relevance of our results, but recent findings in MoM hip implant patients have confirmed that this relationship can be complicated by many patient-specific factors.

Are TKA Kinematics During Closed Kinetic Chain Exercises Associated with Patient-reported Outcomes? A Preliminary Analysis.

BACKGROUND: Kinematic patterns after TKA can vary considerably from those of the native knee. It is unknown, however, if there is a relationship between a given kinematic pattern and patient satisfaction after TKA. QUESTIONS/PURPOSES: Is there an association between kinematic patterns as measured by AP translation during open kinetic chain flexion-extension and closed kinetic chain exercises (rising from a chair and squatting) and a custom aggregate of patient-reported outcome measures (PROMs) that targeted symptoms, pain, activities of daily living (ADL), sports, quality of life (QOL), and patient satisfaction after TKA? METHODS: Thirty patients who underwent TKA between 2014 and 2016 were tested at a minimum follow-up of 6 months. As three different implants were used, per implant the first 10 patients who presented themselves at the follow-up consultations and were able to bend the knee at least 90°, were recruited. Tibiofemoral kinematics during an open kinetic chain flexion-extension and closed kinetic chain exercises-rising from a chair and squatting-were analyzed using fluoroscopy. A two-step cluster analysis was performed, resulting in two clusters of patients who answered the Knee Injury and Osteoarthritis Outcome Score and the satisfaction subscore of the Knee Society Score questionnaires. Cluster 1 (CL1) consisted of patients with better (good-to-excellent) patient-reported outcome measures scores (high-PROMs cluster); Cluster 2 (CL2) consisted of patients with poorer scores (low-PROMs cluster). Tibiofemoral kinematics were compared between patients in these clusters by performing a Mann-Whitney U test with Bonferroni correction. RESULTS: Concerning open kinetic chain flexion-extension, there was no difference in kinematic patterns between the patients in the high-PROMs cluster and those in the low-PROMs cluster, with the numbers available. However, during the closed-chain kinetic exercises, medially, initial anterior translation (femur relative to tibia) was found in patients in Cluster 1 during early flexion, but in those in Cluster 2, translation was steeper and ran more anteriorly (CL1 -1.5 ± 7.3%; CL2 -8.5 ± 4.4%); mean difference 7.0% [95% CI 0.1 to 13.8]; p = 0.046). In midflexion, the femur did not translate anterior nor posterior in relation to the tibia, resulting in a stable medial compartment in Cluster 1, whereas Cluster 2 had already started translating posteriorly (CL1 -0.7 ± 3.5%; CL2 3.4 ± 3.6%; mean difference -4.1% [95% CI -7.0 to -1.2]; p = 0.008). There was no difference, with the numbers available, between the two clusters with respect to posterior translation in deep flexion. Laterally, there was small initial anterior translation in early flexion, followed by posterior translation in midflexion that continued in deep flexion. Patients in Cluster 1 demonstrated more pronounced posterior translation in deep flexion laterally than patients in Cluster 2 did (CL1 8.3 ± 5.2%; CL2 3.5 ± 4.5%); mean difference 4.9% [95% CI 0.6 to 9.1]; p = 0.026). CONCLUSIONS: This study of total knee kinematics suggests that during closed kinetic chain movements, patients with poor PROM scores after TKA experience more anterior translation on the medial side followed by a medial mid-flexion instability and less posterior translation on the lateral side in deep flexion than patients with good PROM scores. The relationship of kinematic variations with patient-reported outcomes including satisfaction must be further elaborated and translated into TKA design and position. Reproduction of optimal kinematic patterns during TKA could be instrumental in improving patient satisfaction after total knee replacement. Future expansion of the study group is needed to confirm these findings.Level of Evidence Level II, therapeutic study.

An evaluation of the influence of force- and weight bearing (a)symmetry on patient reported outcomes after total knee arthroplasty.

It has been reported that balance impairments and asymmetrical movement patterns occur in patients after total kne arthroplasty (TKA). The purpose of this study was to evaluate if force- and weight-bearing asymmetry correlate with patient-reported outcomes (PROMs). Twenty patients were prospectively analysed up to 6 months after TKA. Quadriceps- and hamstring force were measured using a hand-held dynamometer. Vertical ground reaction forces during sit-to-stand, stair descending and squatting were assessed by force plates. Patients were asked to complete the KOOS, OKS and 2011 KSS. The symmetry-ratios during sit-to-stand, squat and stair-descent improved significantly. Preopera-tive quadriceps-force was positively correlated with KOOS-Symptoms (r=0.583, p=0.037). The pre-operative load-symmetry ratio during STS was negatively correlated with improvement in KOOS Pain (r=-0.675, p=0.011) and Symptoms (r=-0.674, p=0.008). In deep flexion, preoperative bodyweight ratio was positively correlated with postoperative OKS (r=0.601, p=0.039), KSS-Satisfaction (r=0.675, p=0.011) and improvement in KSS-Satisfaction (r=0.684, p=0.029). Weight bearing and force asymmetry do exist before TKA and take up to at least 6-months to fully recover. The more symmetry in muscle-force and weight-bearing is found preoperatively, the better the PROMs will be at 6 months after surgery.

Detection of maturity and ligament injury using magic angle directional imaging.

PURPOSE: To investigate whether magnetic field-related anisotropies of collagen may be correlated with postmortem findings in animal models. METHODS: Optimized scan planning and new MRI data-processing methods were proposed and analyzed using Monte Carlo simulations. Six caprine and 10 canine knees were scanned at various orientations to the main magnetic field. Image intensities in segmented voxels were used to compute the orientation vectors of the collagen fibers. Vector field and tractography plots were computed. The Alignment Index was defined as a measure of orientation distribution. The knees were subsequently assessed by a specialist orthopedic veterinarian, who gave a pathological diagnosis after having dissected and photographed the joints. RESULTS: Using 50% less scans than reported previously can lead to robust calculation of fiber orientations in the presence of noise, with much higher accuracy. The 6 caprine knees were found to range from very immature (< 3 months) to very mature (> 3 years). Mature specimens exhibited significantly more aligned collagen fibers in their patella tendons compared with the immature ones. In 2 of the 10 canine knees scanned, partial cranial caudal ligament tears were identified from MRI and subsequently confirmed with encouragingly high consistency of tractography, Alignment Index, and dissection results. CONCLUSION: This method can be used to detect injury such as partial ligament tears, and to visualize maturity-related changes in the collagen structure of tendons. It can provide the basis for new, noninvasive diagnostic tools in combination with new scanner configurations that allow less-restricted field orientations.

Better governance, better access: practising responsible data sharing in the METADAC governance infrastructure.

BACKGROUND: Genomic and biosocial research data about individuals is rapidly proliferating, bringing the potential for novel opportunities for data integration and use. The scale, pace and novelty of these applications raise a number of urgent sociotechnical, ethical and legal questions, including optimal methods of data storage, management and access. Although the open science movement advocates unfettered access to research data, many of the UK's longitudinal cohort studies operate systems of managed data access, in which access is governed by legal and ethical agreements between stewards of research datasets and researchers wishing to make use of them. Amongst other things, these agreements aim to respect the reasonable expectations of the research participants who provided data and samples, as expressed in the consent process. Arguably, responsible data management and governance of data and sample use are foundational to the consent process in longitudinal studies and are an important source of trustworthiness in the eyes of those who contribute data to genomic and biosocial research. METHODS: This paper presents an ethnographic case study exploring the foundational principles of a governance infrastructure for Managing Ethico-social, Technical and Administrative issues in Data ACcess (METADAC), which are operationalised through a committee known as the METADAC Access Committee. METADAC governs access to phenotype, genotype and 'omic' data and samples from five UK longitudinal studies. FINDINGS: Using the example of METADAC, we argue that three key structural features are foundational for practising responsible data sharing: independence and transparency; interdisciplinarity; and participant-centric decision-making. We observe that the international research community is proactively working towards optimising the use of research data, integrating/linking these data with routine data generated by health and social care services and other administrative data services to improve the analysis, interpretation and utility of these data. The governance of these new complex data assemblages will require a range of expertise from across a number of domains and disciplines, including that of study participants. Human-mediated decision-making bodies will be central to ensuring achievable, reasoned and responsible decisions about the use of these data; the METADAC model described in this paper provides an example of how this could be realised.

The patient results and satisfaction of knee arthroplasty in a validated grading system.

INTRODUCTION: The validated Knee Osteoarthritis Grading System (KOGS) was implemented and clinical results were compared with patient satisfaction data and implant survivorship in a multi-centre study with surgeons familiar with unicompartmental knee arthroplasty (UKA), patellofemoral arthroplasty (PFA) and total knee arthroplasty (TKA). This is also the first study to evaluate the prevalence of UKA and TKA in consecutive osteoarthritis (OA) knee arthroplasties assessed by this system.. METHOD: A consecutive cohort of knees was gathered at three different institutions as categorized by KOGS and surgically treated with the recommended implant unless clinical reasons or patient preference precluded such an option. One thousand one hundred seventy-seven consecutive knees were evaluated including 311 TKA (26%), 695 medial UKA (59%), 154 lateral UKA (13%) and 17 PFA (2%) and the results of the categories evaluated with the Oxford Knee Score (OKS) and the complications reflected in the different categories. RESULTS: The failure rate of the UKA (3.5%) or TKA (1.6%) is not higher than accepted results in the literature and the difference in complications is negligible between the UKA (72%) and TKA (26%) cohorts. Revision of a UKA to a TKA as an endpoint was 0.58% with ipsilateral progression at 0.8% over a period of five to 84 months (mean follow-up of 36 months) despite the 'excessive' proportion of UKA in this cohort. The Oxford Score improvement is significant in TKA and UKA and contributes to the acceptable outcomes (The OKS for TKA improved from 20 pre-operatively to 36 post-operatively and the UKA improved from 22 pre-operatively to 39 post-operatively). CONCLUSION: KOGS achieves acceptable early survival and functional results when implemented and is a suitable tool for identifying the preferred implant as was validated.

Improved walking distance and range of motion predict patient satisfaction after TKA.

PURPOSES: The focus in the evaluation of total knee arthroplasty has shifted from objective measures of implant position and knee function, to patient-reported outcome measures (PROMs). The relation between these two measures was investigated and the possibility of prediction of the patient satisfaction level was evaluated by defining thresholds for improvement of (1) range of motion (ROM), (2) 6-min walk test (6MWT), (3) sit-to-stand test (STS) and (4) quadriceps force after TKA? METHODS: Fifty-seven patients were prospectively tested at preoperative and 6 months postoperative intervals. The ROM, 6MWT, STS-test and quadriceps force were evaluated. Two clusters were created based on the postoperative KOOS, OKS and the satisfaction subscore of the new KSS, cluster 1 consisted of patients with good to excellent PROMs, cluster 2 of patients with poorer PROMs. Patients in each cluster were more similar to each other than to those in the other cluster. Receiver operating characteristic (ROC)-curve analysis was used to identify thresholds for the functional outcomes that established cluster allocation. Multiple logistic regression was used to define a model to predict cluster allocation. RESULTS: Patients with high postoperative PROMs (cluster 1 allocation) showed higher postoperative functional outcomes (p < 0.05). Thresholds for the improvement of ROM (≥ 5°, OR 6.3, 95% CI 1.23-31.84), 6MWT (≥ 50 m, OR 8.2, 95% CI 1.61-42.18) STS (≥ 1.05 s, OR 3, 95% CI 0.56-16.07) and normalized Q4 force (≥ 1.5 N/BMI, OR 2.5, 95% CI 0.49-12.89) were found to be predictors of cluster allocation. A model to predict the cluster allocation contained gender, ROM improvement and 6MWT improvement (sensitivity 91.1%, specificity 75%). CONCLUSIONS: Thresholds for improvement of functional parameters can predict the patient satisfaction cluster. Patients, who are male, improve on the 6-min walk test with 50 m or more and have an increased range of motion of 5° or more, compared to the preoperative situation, are 6-8 times more likely of being satisfied after TKA. These tests are easy to use in clinical practice and can predict the level of patient satisfaction after TKA. LEVEL OF EVIDENCE: Level II, prognostic study.

Economic Evaluation of Antibacterial Coatings on Healthcare Costs in First Year Following Total Joint Arthroplasty.

BACKGROUND: Antibacterial coatings (ABCs) of implants have proven safe and effective to reduce postsurgical infection, but little is known about their possible economic impact on large-scale use. This study evaluated the point of economic balance, during the first year after surgery, and the potential overall annual healthcare cost savings of 3 different antibacterial technologies applied to joint arthroplasty: a dual-antibiotic-loaded bone cement (COPAL G + C), an antibacterial hydrogel coating (DAC), and a silver coating (Agluna). METHODS: The variables included in the algorithm were average cost and number of primary joint arthroplasties; average cost per patient of the ABC; incidence of periprosthetic joint infections and expected reduction using the ABCs; average cost of infection treatment and expected number of cases. RESULTS: The point of economic balance for COPAL G + C, DAC, and Agluna in the first year after surgery was reached in patient populations with an expected postsurgical infection rate of 1.5%, 2.6%, and 19.2%, respectively. If applied on a national scale, in a moderately high-risk population of patients with a 5% expected postsurgical infection rate, COPAL G + C and DAC hydrogel would provide annual direct cost savings of approximately €48,800,000 and €43,200,000 (€1220 and €1080 per patient), respectively, while the silver coating would be associated with an economic loss of approximately €136,000,000. CONCLUSION: This economic evaluation shows that ABC technologies have the potential to decrease healthcare costs primarily by decreasing the incidence of surgical site infections, provided that the technology is used in the appropriate risk class of patients.

Atypical Femoral Fractures : Three Cases And A Review Of Literature

In recent years, bisphosphonates and RANK-ligand inhibitors have become the mainstay of treatment for multiple types of osteoporosis, as well as several other metabolic bone diseases. Although rare, atypical femoral fracture is a recent but clearly defined complication of antiresorptive therapy with bisphosphonates, and likely also with denosumab. In this article, we present 3 different cases of atypical femoral fracture: an incomplete fracture linked to a bisphosphonate, an incomplete fracture linked to denosumab, and a complete atypical femoral fracture. Specific diagnostic steps and therapy are described. We also offer a complete overview of available literature concerning diagnosis, epidemiology, pathogenesis, treatment and future outlooks concerning this entity. Although antiresorptive therapy offers a very significant benefit in the prevention of osteoporotic fractures, clinicians should be aware of the possible complications, especially with long-term therapy.

A New Prediction Model for Patient Satisfaction After Total Knee Arthroplasty.

BACKGROUND: Total knee arthroplasty (TKA) is a proven and cost-effective treatment for osteoarthritis. Despite the good to excellent long-term results, some patients remain dissatisfied. Our study aimed at establishing a predictive model to aid patient selection and decision-making in TKA. METHODS: Using data from our prospective arthroplasty outcome database, 113 patients were included. Preoperatively and postoperatively, the patients completed 107 questions in 5 questionnaires: Knee Injury and Osteoarthritis Outcome Score, Oxford Knee Score, Pain Catastrophizing Scale, Euroqol questionnaire, and Knee Scoring System. First, outcome parameters were compared between the satisfied and dissatisfied group. Second, we developed a new prediction tool using regression analysis. Each outcome score was analyzed with simple regression. Subsequently, the predictive weight of individual questions was evaluated applying multiple linear regression. Finally, 10 questions were retained to construct a new prediction tool. RESULTS: Overall satisfaction rate in this study was found to be 88%. We identified a significant difference between the satisfied and dissatisfied group when looking at the preoperative questionnaires. Dissatisfied patients had more preoperative symptoms (such as stiffness), less pain, and a lower quality of life. They were more likely to ruminate and had a lower preoperative Knee Scoring System satisfaction score. The developed prediction tool consists of 10 simple but robust questions. Sensitivity was 97% with a positive-predictive value of 93%. CONCLUSIONS: Based upon preoperative parameters, we were able to partially predict satisfaction and dissatisfaction after TKA. After further validation, this new prediction tool for patient satisfaction following TKA may allow surgeons and patients to evaluate the risks and benefits of surgery on an individual basis and help in patient selection.

Impact of drying and thiel embalming on mechanical properties of achilles tendons.

Biomechanical research and orthopedic training is regularly carried out on human cadavers. Given the post-mortem decay, these cadavers were usually frozen or embalmed. The embalming method according to Dr. Thiel was often praised for the preservation of natural texture. The main aim of this article was to quantitatively analyze the impact of this embalming technique on the biomechanical properties. To that extent, Achilles tendons (calcaneal tendons) of seven cadavers have been tested. For each cadaver, a first tendon was tested following a fresh-frozen conservation, the other following the Thiel embalming process. The results indicated a significant difference in Young's modulus between both groups (P values = 0.046). The secondary aim of this article was to analyze the impact of exposure to room conditions and associated dehydration on the biomechanical properties of cadaver tissue. Therefore, each tendon was tested before and after 2 hr of exposure to room conditions. The resulting dehydration caused a significant increase of the Young's modulus for the thawed fresh-frozen tendons. The properties of the Thiel embalmed tendons were not significantly altered. In conclusion, this research promoted the use of fresh-frozen specimens for biomechanical testing. Effort should, however, be made to minimize dehydration of the tested specimens.

Outcome of patellofemoral arthroplasty, determinants for success.

The primary aim of this study is to document whether patellofemoral arthroplasty is a good treatment option for patellofemoral osteoarthritis and to identify prognostic outcome factors. Secondary aim is to investigate the influence of preoperative tibiofemoral osteoarthritis on the clinical outcome. From 2004 to 2010, 37 Avon patellofemoral prostheses were implanted in 32 patients. Clinical outcome was evaluated with five questionnaires: KOOS, Kujala, VAS, OKS and Satisfaction Score. Radiographs were analyzed using the IWANO and Kellgren-Lawrence classification. To identify determinants of outcome, subgroups were examined according to sex, age, diagnosis, BMI and prior surgery. Patellofemoral arthroplasty is a valuable treatment for patellofemoral osteoarthritis. After prosthesis placement, KOOS, Kujala, VAS and OKS improved significantly (all p < 0.001). Patients with prior patellofemoral surgery were clinically worse (p < 0.05). Patients with preoperative Kellgren-Lawrence grade 2 tibiofemoral osteoarthritis had a significantly worse outcome compared to grade 1 (p < 0.05). Further research is necessary to determine whether patellofemoral arthroplasty is indicated in these patients.

Comparative study of innovative postoperative wound dressings after total knee arthroplasty.

PURPOSE: Postoperative wound complications, especially surgical site infections, influence the outcome after total knee arthroplasty. The purpose of our study was to compare four different wound dressings. Following research questions were asked : (1) Which dressing is associated with least wound complications? (2) Which dressing application is the cheapest? (3) Which dressing is most comfortable for the patient? METHODS: 111 patients undergoing a total knee arthroplasty were randomized in 4 groups. Each group received a different dressing with its specific wound management protocol : (1) Zetuvit® with Cosmopor E®, (2) Zetuvit® with Opsite Post-Op Visible®, (3) Aquacel Surgical® and (4) Mepilex Border®. Follow-up evaluations were performed on the fifth postoperative day and included assessment of the wound, status of the wound dressing and the patient's own judgment. Cumulative costs were calculated. RESULTS: Clinically Mepilex Border®, a silicone dressing, scored the best. No wound complications were seen in this group. The mean number of dressing renewals was 1.9 for the standard dressing which was significantly higher (p<.0001) compared to the other dressings. Opsite Post-op Visible® was the cheapest dressing. Mepilex Border® had the best scores for pain, freedom of movement and general comfort. CONCLUSIONS: Mepilex Border® is the most skin-friendly dressing. The number of dressing renewals is a defining factor to calculate the costs. Mepilex Border® appeared to be the best dressing to use after a total knee arthroplasty.

Total knee arthroplasty at 15-17 years: does implant design affect outcome?

PURPOSE: A study was conducted to compare minimum 15-year survivorship and outcome of the Genesis I and II implants for total knee arthroplasty (TKA). METHODS: We retrospectively reviewed 245 consecutive TKA implanted between January 1995 and October 1997. Genesis I was implanted in 156 knees and Genesis II in 89 knees. RESULTS: At 15-17 years, 75 patients (31%) had died, 28 patients (11%) were lost to follow-up and 11 TKA were revised (4.6%), including ten Genesis I (6.4%) and one Genesis II (1.1%); 131 TKA (53%) were available for follow-up. Cumulative survivorship was 92.4% at 15.7 years. Survival in patients <69 years at surgery was lower (88.0%) compared with patients ≥69 years (98.5%; p = 0.023). In patients <69 years, Genesis I survival (84.3%) was worse compared with Genesis II (97.1%) (p = 0.018). Polyethylene (PE) Insert thickness ≤11 mm had significantly better survivorship (97.1%) compared with PE >11 mm (56.7%) (p < 0.0001) CONCLUSIONS: At a minimum of 15 years, the overall (92.4%) survivorship of Genesis TKA was good, with excellent (98.1%) survivorship of the Genesis II design. Revision rates were higher with Genesis I in the younger age group and with insert thickness >11 mm, possibly due to longer shelf life of less frequently used sizes.

Translation and validation of the Dutch new Knee Society Scoring System ©.

BACKGROUND: A new version of The Knee Society Knee Scoring System(©) (KSS) has recently been developed. Before this scale can be used in non-English-speaking populations, it has to be translated and validated for a particular population. QUESTIONS/PURPOSES: We evaluated the construct and content validity, the test-retest reliability, and the internal consistency of the Dutch version of the New Knee Society KSS. METHODS: A Dutch translation was performed using a forward-backward translation protocol. We tested the construct validity of the Dutch New KSS by comparing it with the Dutch versions of the WOMAC, Knee Injury and Osteoarthritis Outcome Score (KOOS), and SF-12 scores in 137 patients undergoing total knee arthroplasty (TKA). Content validity was assessed by comparing pre- and postoperative scores and by checking floor and ceiling effects. To evaluate test-retest reliability and consistency, 47 patients completed the questionnaire a second time with a mean of 8 days interval (range, 2-20 days) between tests. RESULTS: Construct validity was demonstrated because the Dutch New KSS correlated well with the Dutch WOMAC (r = -0.751; p < 0.001), Dutch KOOS (r = -0.723; p < 0.001), and Dutch SF-12 (r = 0.569; p < 0.001). There was a significant difference between pre- and postoperative scores (p < 0.001) in line with the other scores. Test-retest reliability proved excellent with an intraclass correlation coefficient between 0.73 and 0.92 depending on the domain tested. Consistency as indicated by Cronbach's alpha ranging from 0.84 to 0.96 was good to excellent. CONCLUSIONS: As demonstrated by the validation procedure, the Dutch New KSS is an excellent instrument to evaluate TKA outcome in Dutch-speaking patients.

The 2012 Otto Aufranc Award: The interpretation of metal ion levels in unilateral and bilateral hip resurfacing.

BACKGROUND: The interpretation of metal ion concentrations and their role in clinical management of patients with metal-on-metal implants is still controversial. QUESTIONS/PURPOSES: We questioned whether patients undergoing hip resurfacing with no clinical problems could be differentiated from those with clinical (pain, loss of function) and/or radiographic (component malpositioning, migration, bone loss), problems based on metal ion levels, and if there was a threshold metal level that predicted the need for clinical intervention. Furthermore, we asked if patient and implant factors differed between these functional groups. METHODS: We retrospectively identified 453 unilateral and 139 bilateral patients with ion measurements at minimum followup of 12 months (mean, 4.3 years; range, 1-12.9 years). Patients were designated as well functioning or poorly functioning based on strict criteria. The acceptable upper levels within the well-functioning group were determined from the 75th percentile plus 1.5× interquartile range. The sensitivity and specificity of these levels to predict clinical problems were calculated. RESULTS: Well-functioning group ions were lower than the poorly functioning group ion levels. The acceptable upper levels were: chromium (Cr) 4.6 µg/L, cobalt (Co) 4.0 µg/L unilateral and Cr 7.4 µg/L, Co 5.0 µg/L bilateral. The specificity of these levels in predicting poor function was high (95%) and sensitivity was low (25%). There were more males in the well-functioning group and more females and smaller femoral components in the poorly functioning group. CONCLUSIONS: Metal levels higher than these proposed safe upper limits can predict problems with metal-on-metal resurfacings and are important parameters in the management of at-risk patients. LEVEL OF EVIDENCE: Level II, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Informed Consent: Research Staff's Perspectives and Practical Recommendations to Improve Research Staff-Participant Communication.

Informed consent (IC) is the process of communication between research staff and potential research participants. However, ensuring that participants clearly understand what research participation entails, raises significant challenges. The aim of this study is to provide insight into some communication barriers that research staff are confronted with and make practical recommendations to improve communication between research staff and participants. A qualitative research study using semi-structured interviews (n = 13) with research staff from Ghent University Hospital was conducted. Data were transcribed verbatim and coded thematically. Our results indicate that communication- and process-related factors affect the IC process. Emergent recommendations include communication training, more interactive information materials and the use of digital alternatives, increasing general knowledge about research participation and patient- and public involvement.