Aims. Patients with cauda equina syndrome (CES) require emergency imaging and surgical decompression. The severity and type of symptoms may influence the timing of imaging and surgery, and help predict the patient’s prognosis. Categories of CES attempt to group patients for management and prognostication purposes. We aimed in this study to assess the inter-rater reliability of dividing patients with CES into categories to assess whether they can be reliably applied in clinical practice and in research. Methods. A literature review was undertaken to identify published descriptions of categories of CES. A total of 100 real anonymized clinical vignettes of patients diagnosed with CES from the Understanding Cauda Equina Syndrome (UCES) study were reviewed by consultant spinal surgeons, neurosurgical registrars, and medical students. All were provided with published category definitions and asked to decide whether each patient had ‘suspected CES’; ‘early CES’; ‘incomplete CES’; or ‘CES with urinary retention’. Inter-rater agreement was assessed for all categories, for all raters, and for each group of raters using Fleiss’s kappa. Results. Each of the 100 participants were rated by four medical students, five neurosurgical registrars, and four consultant spinal surgeons. No groups achieved reasonable inter-rater agreement for any of the categories. CES with retention versus all other categories had the highest inter-rater agreement (kappa 0.34 (95% confidence interval 0.27 to 0.31); minimal agreement). There was no improvement in inter-rater agreement with clinical experience. Across all categories, registrars agreed with each other most often (kappa 0.41), followed by medical students (kappa 0.39). Consultant spinal surgeons had the lowest inter-rater agreement (kappa 0.17). Conclusion. Inter-rater agreement for categorizing CES is low among clinicians who regularly manage these patients. CES categories should be used with caution in clinical practice and research studies, as groups may be heterogenous and not comparable. Cite this article: Bone Joint J 2023;105-B(9):1007–1012

The diagnostic sub-categorization of cauda equina syndrome (CES) is used to aid communication between doctors and other healthcare professionals. It is also used to determine the need for, and urgency of, MRI and surgery in these patients. A recent paper by Hoeritzauer et al (2023) in this journal examined the interobserver reliability of the widely accepted subcategories in 100 patients with cauda equina syndrome. They found that there is no useful interobserver agreement for the subcategories, even for experienced spinal surgeons. This observation is supported by the largest prospective study of the treatment of cauda equina syndrome in the UK by Woodfield et al (2023). If the accepted subcategories are unreliable, they cannot be used in the way that they are currently, and they should be revised or abandoned. This paper presents a reassessment of the diagnostic and prognostic subcategories of cauda equina syndrome in the light of this evidence, with a suggested cure based on a more inclusive synthesis of symptoms, signs, bladder ultrasound scan results, and pre-intervention urinary catheterization.

Cite this article: Bone Joint J 2024;106-B(3):227–231.

Aims. Prior studies have identified that malseating of a modular dual mobility liner can occur, with previous reported incidences between 5.8% and 16.4%. The aim of this study was to determine the incidence of malseating in dual mobility implants at our institution, assess for risk factors for liner malseating, and investigate whether liner malseating has any impact on clinical outcomes after surgery. Methods. We retrospectively reviewed the radiographs of 239 primary and revision total hip arthroplasties with a modular dual mobility liner. Two independent reviewers assessed radiographs for each patient twice for evidence of malseating, with a third observer acting as a tiebreaker. Univariate analysis was conducted to determine risk factors for malseating with Youden’s index used to identify cut-off points. Cohen’s kappa test was used to measure interobserver and intraobserver reliability. Results. In all, 12 liners (5.0%), including eight Stryker (6.8%) and four Zimmer Biomet (3.3%), had radiological evidence of malseating. Interobserver reliability was found to be 0.453 (95% confidence interval (CI) 0.26 to 0.64), suggesting weak inter-rater agreement, with strong agreement being greater than 0.8. We found component size of 50 mm or less to be associated with liner malseating on univariate analysis (p = 0.031). Patients with malseated liners appeared to have no associated clinical consequences, and none required revision surgery at a mean of 14 months (1.4 to 99.2) postoperatively. Conclusion. The incidence of liner malseating was 5.0%, which is similar to other reports. Component size of 50 mm or smaller was identified as a risk factor for malseating. Surgeons should be aware that malseating can occur and implant design changes or changes in instrumentation should be considered to lower the risk of malseating. Although further follow-up is needed, it remains to be seen if malseating is associated with any clinical consequences. Cite this article: Bone Jt Open 2021;2(10):858–864

Distal radius fractures are common in South Africa. Accurate, decisive radiographic parameter interpretation is key in appropriate management. Digital radiographic facilities are rare in the public setting and goniometer usage is known to be low, thus, visual estimates are the primary form of radiographic assessment. Previous research associated orthopaedic experience with accuracy of distal radius fracture parameter estimation but, oftentimes, doctors treating orthopaedic patients are not experienced in orthopaedics. A cross-sectional questionnaire including four distal radius fracture radiographs administered to 149 orthopaedic doctors at three Johannesburg teaching hospitals. Participants grouped into ranks of: consultants (n=36), registrars (n=41), medical officers (n=20) and interns (n=52). Participants visually estimated values of distal radius fracture parameters, stated whether they would accept the position of the fractures and stated their percentage of routine usage of goniometers in real practice. The registrar group was most accurate in visually estimating radial height, whilst the interns were least accurate (p=0.0237). The consultant, registrar and medical officer groups were equally accurate in estimating radial inclination whilst the intern group was the least accurate (p<0.0001). The consultant and registrar group were equally accurate at estimating volar tilt, whilst the medical officer and intern groups were least accurate (p<0.0001). The Gwet's AC agreement was 0.1612 (p=0.047) for acceptance of position of the first radiograph, 0.8768 (p<0.0001) for the second, 0.8884 (p<0.0001) for the third and 0.8064 (p<0.0001) for the fourth. All groups showed no difference in goniometer usage, using them largely 0–25% of practice (p=0.1937). The study found that accuracy in visual estimations of distal radius fracture parameters was linked to orthopaedic experience but not linked to routine practice goniometer usage, which was minimal across all groups. Inter-rater agreement on acceptability of fracture position is potentially dependent on severity of deviation from acceptable parameters

Aims. Accurate measurement of the glenoid version is important in performing total shoulder arthroplasty (TSA). Our aim was to evaluate the Ellipse method, which involves formally defining the vertical mid-point of the glenoid prior to measuring the glenoid version and comparing it with the ‘classic’ Friedman method. Methods. This was a retrospective study which evaluated 100 CT scans for patients who underwent a primary TSA. The glenoid version was measured using the Friedman and Ellipse methods by two senior observers. Statistical analyses were performed using the paired t-test for significance and the Bland-Altman plot for agreement. Results. The mean glenoid version was -3.11° (-23.8° to 17.9°) using the Friedman method and -1.95° (-29.8° to 24.6°) using the Ellipse method (p = 0.002). In 16 patients the difference between methods was greater than 5°, which we considered to be clinically significant. There was poor agreement between methods with relatively large 95% limits of agreement. There was excellent inter-rater agreement between the observers for the Ellipse method and similarly, the intrarater agreement was excellent with a repeatability coefficient of 0.94. Conclusion. We recommend the use of the Ellipse modification to define the mid glenoid point prior to measuring the glenoid version in patients undergoing TSA. Cite this article: Bone Joint J 2020;102-B(2):232–238

Purpose: The Instability Severity Index Score (ISIS) is a 6-item questionnaire that has been reported to predict failure of arthroscopic Bankart repair among patients treated for recurrent anterior glenohumeral instability. Two of the ISIS items pertain to radiographic features (presence of a Hill-Sachs lesion, loss of glenoid contour). These, however have yet to be validated. The goal of this study was to examine the inter – and intra-rater agreement and corresponding reliability of the radiographic aspects of the ISIS. Method: Fifty-two plain, randomly selected, true antero-posterior radiographs in 45° gleno-humeral external rotation were evaluated by five assessors (three upper extremity orthopaedic surgeons, one senior orthopaedic resident and one musculoskeletal radiologist). Radiographs were retrieved for patients with documented recurrent shoulder instability requiring surgical stabilization and placed in a blinded Microsoft Powerpoint presentation for evaluation. Assessors were asked to determine the presence/absence of a Hill-Sachs lesion and if a loss of glenoid contour was present. Radiographs were evaluated in random order on two occasions, separated by a one-week time interval. Intra – and inter-rater reliability was assessed using percentage of agreement and kappa statistics. Results: For session one, the number of Hill-Sachs lesions observed among raters ranged from 11 to 32. This resulted in inter-rater agreement ranging from 48% to 78% (k = 0.07 to 0.42), indicating poor to fair reliability. Cases with loss of glenoid contour ranged from seven to 14 with inter-rater agreement of 66% and 90% (k = 0.01 to 0.61), suggesting poor to moderate reliability. Session two led to modest increases in inter-rater agreement. The number of Hill-Sachs lesions observed ranged from four to 30 (agreement of 48% to 84%; k = 0.11 to 0.60) indicating fair to moderate reliability and the number of cases with loss of glenoid contour ranged from three to 14 (agreement of 66% to 94%; k = – 0.04 to 0.69), ranging from poor to moderate reliability. With respect to intra-rater reliability, agreement ranged from 71% to 94% (k = 0.41 to 0.86) for Hill-Sachs lesions, indicating fair to good reliability and 76% to 94% (k= 0.20 to 0.74) for loss of glenoid contour, ranging from fair to good reliability. Intra-rater agreement and corresponding kappa values were highest among the upper extremity surgeons and the musculoskeletal radiologist, particularly for loss of glenoid contour (85% to 94%; k = 0.56 to 0.74) suggesting there is moderate to good reliability in this measurement. Conclusion: Our results indicate that the intra-rater reliability of the ISIS radiographic features was highest among upper extremity specialists and the musculoskeletal radiologist, suggesting that the ISIS may have utility in an experienced clinician’s individual practice. As the inter-rater reliability appears low, particularly for Hill-Sachs lesions, its wide-spread use across surgeons should be examined in further research

Movement dysfunction resulting in a knee valgus position during weight bearing activity is associated with increased risk of Anterior Cruciate Ligament injury and Patellofemoral Pain Syndrome especially in young active females. In clinical practice determining the critical knee flexion angle (CKFA) during a single leg squat (SLS) test is used to assess this dysfunction, yet its reliability is unknown. This study aimed to determine rater agreement in determining the presence of knee valgus movement (yes/no) during a SLS test in recreational females (n = 16, age 24.3 ±7.9 yrs, height 165.7±4.8m, mass 62.5±6.4kg) and the intra and inter-rater reliability of measuring CKFA using SiliconCoach™. Three experienced physiotherapists viewed 48 randomised SLS test videos. One physiotherapist repeated the viewing for test-retest analysis. Test-retest agreement for rating SLS test was acceptable (weighted kappa (k) = 0.667). Inter-rater agreement was moderate to substantial (weighted k = 0.284–0.613). Intra-rater reliability of CKFA was acceptable for all three raters (ICC>0.6). Inter-rater absolute reliability was below 5% of the mean CKFA (SEM 4.26 degrees). As previous research reports intra-rater agreement is better than inter-rater agreement when assessing movement dysfunction during functional activity via visual rating. Intra-rater within session and between session reliability for measuring the CKFA using SiliconCoach™ was acceptable and better than inter-rater reliability. Further research is needed to assess the concurrent and construct validity of the protocols used in this study. It is recommended that qualitative research be performed to identify factors that affect physiotherapist's rating of functional activities

Aims. Joint registries classify all further arthroplasty procedures to a knee with an existing partial arthroplasty as revision surgery, regardless of the actual procedure performed. Relatively minor procedures, including bearing exchanges, are classified in the same way as major operations requiring augments and stems. A new classification system is proposed to acknowledge and describe the detail of these procedures, which has implications for risk, recovery, and health economics. Methods. Classification categories were proposed by a surgical consensus group, then ranked by patients, according to perceived invasiveness and implications for recovery. In round one, 26 revision cases were classified by the consensus group. Results were tested for inter-rater reliability. In round two, four additional cases were added for clarity. Round three repeated the survey one month later, subject to inter- and intrarater reliability testing. In round four, five additional expert partial knee arthroplasty surgeons were asked to classify the 30 cases according to the proposed revision partial knee classification (RPKC) system. Results. Four classes were proposed: PR1, where no bone-implant interfaces are affected; PR2, where surgery does not include conversion to total knee arthroplasty, for example, a second partial arthroplasty to a native compartment; PR3, when a standard primary total knee prosthesis is used; and PR4 when revision components are necessary. Round one resulted in 92% inter-rater agreement (Kendall’s W 0.97; p < 0.005), rising to 93% in round two (Kendall’s W 0.98; p < 0.001). Round three demonstrated 97% agreement (Kendall’s W 0.98; p < 0.001), with high intra-rater reliability (interclass correlation coefficient (ICC) 0.99; 95% confidence interval 0.98 to 0.99). Round four resulted in 80% agreement (Kendall’s W 0.92; p < 0.001). Conclusion. The RPKC system accounts for all procedures which may be appropriate following partial knee arthroplasty. It has been shown to be reliable, repeatable and pragmatic. The implications for patient care and health economics are discussed. Cite this article: Bone Jt Open 2021;2(8):638–645

Aims. Deep surgical site infection (SSI) is common after lower limb fracture. We compared the diagnosis of deep SSI using alternative methods of data collection and examined the agreement of clinical photography and in-person clinical assessment by the Centers for Disease Control and Prevention (CDC) criteria after lower limb fracture surgery. Methods. Data from two large, UK-based multicentre randomized controlled major trauma trials investigating SSI and wound healing after surgical repair of open lower limb fractures that could not be primarily closed (UK WOLLF), and surgical incisions for fractures that were primarily closed (UK WHiST), were examined. Trial interventions were standard wound care management and negative pressure wound therapy after initial surgical debridement. Wound outcomes were collected from 30 days to six weeks. We compared the level of agreement between wound photography and clinical assessment of CDC-defined SSI. We are also assessed the level of agreement between blinded independent assessors of the photographs. Results. Rates of CDC-defined deep SSI were 7.6% (35/460) after open fracture and 6.3% (95/1519) after closed incisional repair. Photographs were obtained for 77% and 73% of WOLLF and WHiST cohorts respectively (all participants n = 1,478). Agreement between photographic-SSI and CDC-SSI was fair for open fracture wounds (83%; k = 0.27 (95% confidence interval (CI) 0.14 to 0.42)) and for closed incisional wounds (88%; k = 0.29 (95% CI 0.20 to 0.37)) although the rate of photographically detected deep SSIs was twice as high as CDC-SSI (12% vs 6%). Agreement between different assessors for photographic-SSI (WOLLF 88%, k = 0.63 (95% CI 0.52 to 0.72); WHiST 89%; k = 0.61 (95% CI 0.54 to 0.69)); and wound healing was good (WOLLF 90%; k = 0.80 (95% CI 0.73 to 0.86); WHiST 87%; k = 0.57 (95% CI 0.50 to 0.64)). Conclusion. Although wound photography was feasible within the research context and inter-rater assessor agreement substantial, digital photographs used in isolation overestimated deep SSI rates, when compared to CDC criteria. Wound photography should not replace clinical assessment in pragmatic trials but may be useful for screening purposes where surgical infection outcomes are paramount. Cite this article: Bone Joint J 2021;103-B(12):1802–1808

The objective of this study was to compare differences in alignment following robotic arm-assisted bi-unicompartmental knee arthroplasty (Bi-UKA) and conventional total knee arthroplasty (TKA). This was a prospective, randomised controlled trial of 70 patients. 39 TKAs were implanted manually, as per standard protocol at our institution, and 31 Bi-UKA patients simultaneously received fixed-bearing medial and lateral UKAs, implanted using robotic arm-assistance. Preoperative and 3-month postoperative CT scans were analysed to determine hip knee ankle angle (HKAA), medial distal femoral angle (MDFA), and medial proximal tibial angle (MPTA). Analysis was repeated for 10 patients by a second rater to validate measurement reliability by calculating the intra-class correlation coefficient (ICC). Mean change in HKAA towards neutral was 2.7° in TKA patients and 2.3° in Bi-UKA patients (P=0.6). Mean change in MDFA was 2.5° for TKA and 1.0° for Bi-UKA (P<0.01). Mean change in MPTA was 3.7° for TKA and 0.8° for Bi-UKA (P<0.01). Mean postoperative MDFA and MPTA for TKAs were 89.8° and 89.6° respectively, indicating orientation of femoral and tibial components perpendicular to the mechanical axis. Mean postoperative MDFA and MPTA for Bi-UKAs were 91.0° and 86.9° respectively, indicating a more oblique joint line orientation. Inter-rater agreement was excellent (ICC>0.99). Early functional activities, according to the new Knee Society Scoring System, favoured Bi-UKAs (P<0.05). Robotic arm-assisted, cruciate-sparing Bi-UKA better maintains the natural anatomy of the knee in the coronal plane and may therefore preserve normal joint kinematics, compared to a mechanically aligned TKA. This has been achieved without significantly altering overall HKAA

To determine if there are osteochondritis dissecans (OCD) lesions of the knee that are so unstable on MRI that they are incapable of healing without operative intervention. A secondary objective was to determine the ability of orthopaedic residents to accurately grade OCD lesions according to the Kijowski criteria of stable and unstable. A retrospective review was performed of patients who had femoral condyle OCD lesions from 2009-present. Only patients with open growth plates and serial MRIs were included. Each MRI was classified according to the Kijowski classification by a junior orthopaedic surgery resident as well as an MSK trained radiologist. A weighted kappa value was used to assess the inter-rater agreement. The final analysis included 16 patients (17 knees) with 49 MRI's. The weighted kappa agreement between reviewers for overall lesion stability was moderate (0.570 [95% CI 0.237–0.757]). The initial MRI lesion was graded as stable in 59% (10/17) of the knees. Two of these 10 knees became unstable during the study period, however, both stabilised again on subsequent MRIs, one with surgery and the other without surgery. The initial MRI was graded as unstable in 41% (7/17) of the knees. Two of the seven knees (29%) later demonstrated MRI evidence of lesion stability without surgical intervention. The most important finding in this study was the ability of unstable OCD lesions on MRI to heal without operative intervention. The ability of an orthopaedic surgery resident to grade these lesions on MRI was moderate

Introduction. The prevalence of adverse reactions to metal debris (ARMD) associated with metal on metal (MoM) hip arthroplasty has been reported to be as high as 69%. Such findings promoted the development of metal-artefact reducing sequence (MARS)-magnetic resonance imaging (MRI) classifications, with the aim of stratifying soft lesions by severity of disease. The Modified Oxford Classification is a straightforward system that has been shown to correlate with disease progression. Methods. The aim of this study was to test the reliability of this classification between observers. Seven observers were recruited, all with a musculoskeletal background. Using the PACS image analysis system, 20 MARS-MRI scans were provided for interpretation. Observers reviewed these scans in random order at two separate intervals over the course of five weeks. They classified them according to the Modified Oxford Classification as: ‘normal’, ‘trochanteric fluid, ‘effusion’, ‘ARMD type 1’, ‘ARMD type 2’ and ‘ARMD type 3’. Results. Statistical tests using kappa co-efficients were performed to get intra and inter observer reliabilities. Our results were compared against the grading system proposed by Landis and Koch. Our inter-rater agreement was 0.61. This is considered substantial agreement. Our intra observer scores ranged for 0.57 to 1.00 indicating consistency between the observers as individuals and as a group. Conclusion. The modified oxford classification is simple and easy to remember and has substantial reliability. It is proving to be effective in communicating, classifying and providing an understanding of disease progression

The Radiographic Union Score for Hip (RUSH) is an outcome instrument designed to describe radiographic healing of femoral neck fractures. The ability to identify fractures that have not healed is important for defining non-union in clinical trials and predicting patients that likely require additional surgery to promote fracture healing. We sought to determine a RUSH threshold score that defines nonunion at 6-months post-injury. Our secondary objective was to determine if this threshold was associated with increased risk for non-union surgery. A sample of 248 patients with adequate six-month hip radiographs and complete two-year clinical follow-up were analysed from a multi-national hip fracture trial (FAITH). All patients had a femoral neck fracture and were treated with either multiple cancellous screws or a sliding hip screw. Two reviewers independently determined the RUSH score based on the six-month post-injury radiographs, and agreement was assessed using the Interclass Correlation Coefficient (ICC). Fracture healing was determined by two independent methods: 1) prospectively by the treating surgeon using clinical and radiographic assessments, and 2) retrospectively by a Central Adjudication Committee using radiographs alone. Receiver Operator Curve analysis was used to define a RUSH threshold score that was specific for fracture nonunion. RUSH score inter-rater agreement was high (ICC: 0.81, 95% CI 0.76 to 0.85). The mean six-month RUSH score for all included patients was 24.4 (SD 3.4). A threshold score of <18 was associated with a greater than 98% specificity for nonunion. Furthermore, patients with a six-month RUSH score below 18 were more the seven-times more likely to require revision surgery for nonunion (Relative Risk: 7.25, 95% CI 2.62 to 20.00). The six-month RUSH score can effectively be used to communicate when a femoral neck fracture has not healed. The validity of our conclusions was further supported by the increased risk of nonunion surgery for patients below the RUSH threshold. We believe our findings can standardise a definition of nonunion for clinical trials and recommend the use of the RUSH and its <18-point threshold when describing femoral neck nonunion

Anatomic studies have demonstrated that bipolar glenoid and humeral bone loss have a cumulative impact on shoulder instability, and that these defects may engage in functional positions depending on their size, location, and orientation, potentially resulting in failure of stabilisation procedures. Determining which lesions pose a risk for engagement remains a challenge, with Itoi's 3DCT based glenoid track method and arthroscopic assessment being the accepted approaches at this time. The purpose of this study was to investigate the interaction of humeral and glenoid bone defects on shoulder engagement in a cadaveric model. Two alternative approaches to predicting engagement were evaluated; 1) CT scanning the shoulder in abduction and external rotation 2) measurement of Bankart lesion width and a novel parameter, the intact anterior articular angle (IAAA), on conventional 2D multi-plane reformats. Hill-Sachs and Bony Bankart defects of varying size were created in 12 cadaveric upper limbs, producing 45 bipolar defect combinations. The shoulders were assessed for engagement using cone beam CT in various positions of function, from 30 to 90 degrees of both abduction and external rotation. The humeral and glenoid defects were characterised by measurement of their size, location, and orientation. The abduction external rotation scan and 2D IAAA approaches were compared to the glenoid track method for predicting engagement. Engagement was predicted by Itoi's glenoid track method in 24 of 45 specimens (53%). The abduction external rotation CT scan performed at 60 degrees of glenohumeral abduction (corresponding to 90 degrees of abduction relative to the trunk) and 90 degrees of external rotation predicted engagement accurately in 43 of 45 specimens (96%), with sensitivity and specificity of 92% and 100% respectively. A logistic model based on Bankart width and IAAA provided a prediction accuracy of 89% with sensitivity and specificity of 91% and 87%. Inter-rater agreement was excellent (Kappa = 1) for classification of engagement on the abduction external rotation CT, and good (intraclass correlation = 0.73) for measurement of IAAA. Bipolar lesions at risk for engagement can be identified using an abduction external rotation CT scan at 60 degrees of glenohumeral abduction and 90 degrees of external rotation, or by performing 2D measurements of Bankart width and IAAA on conventional CT multi-plane reformats. This information will be useful for peri-operative decision making around surgical techniques for shoulder stabilisation in the setting of bipolar bone defects

Purpose. Radial head implant over-lengthening, a common cause of capitellar wear and clinical failure, is difficult to diagnose using radiographs of the injured elbow. The purpose of this study was to determine if a novel measurement technique based on contralateral elbow radiographs, termed the RACER method, could be used to accurately estimate the magnitude of radial head implant over-lengthening. Part I of this study examined the side-to-side consistency of radiographic landmarks used in the measurement technique. Part II of this study validated the technique using simulated radial head implant over-lengthening in a cadaveric model. Method. Part I: A side-to-side comparison of elbow joint dimensions was performed in 50 patients (100 radiographs). Part II: Radial head prostheses of varying lengths (0,+2mm,+4mm,+6mm,+8mm) were implanted in 4 paired cadaveric specimens (8 elbows). Radiographs were obtained and measurements were performed by 2 examiners blinded to implant size to determine if contralateral radiographs could diagnose and provide a valid estimate of the magnitude of implant over-lengthening. Intra and inter-rater reliability was determined. Results. No significant side-to-side differences (p>0.2) in radiographic measurements were identified between paired elbows. The RACER measurement technique using contralateral radiographs was successful in predicting the implant size (1mm) in 104 of 120 (87%) of scenarios tested. The sensitivity of the technique, the ability of the test to correctly identify over-lengthening when it was present within 1mm, was 98%. The intra-rater agreement for a single orthopaedic surgeon measuring on 2 separate occasions was excellent (ICC>0.90). The inter-rater agreement between two separate surgeons was also excellent, with the 95% lower confidence interval exceeding 0.90 in all cases. Conclusion. A novel measurement technique based on contralateral elbow radiographs can be used to diagnose and calculate the magnitude of radial head implant over-lengthening. Clinical Significance: Implantation of an incorrectly sized radial head prosthesis is not uncommon. The described technique can be used to effectively diagnose and determine the magnitude of over-lengthening

Introduction. UHMWPE particle-induced osteolysis is one of the major causes of arthroplasty revisions. Recent in vitro findings have suggested that UHMWPE wear particles containing vitamin-E (VE) may have reduced functional biologic activity and decreased potential to cause osteolysis (Bladed C. L. et al, JBMR B 2012 and 2013). This is of significant importance since VE-stabilized cross-linked UHMWPEs were recently introduced for clinical use, and there is no in vivo data determining the effects of wear debris. In this study we hypothesized that particles from VE-stabilized, radiation cross-linked UHMWPE (VE-UHMWPE) would cause reduced levels of osteolysis in a murine calvarial bone model when compared to virgin gamma irradiated cross-linked UHMWPE. Methodology. Study groups were the following: 1). Radiation cross-linked VE-UHMWPE (0.8% by weight) diffused after 100 kGy; 2). Radiation cross-linked virgin UHMWPE (virgin UHMWPE); 3). Sham controls. Particle generation and implantation: UHMWPE was sent to Bioengineering Solutions (Oak Park, IL) for particle generation. After IACUC approval, C57BL/6 mice (n=12 for each group) received equal amount of particulate debris (3mg) overlying the calvarium and were euthanized after 10 days. Micro-CT scans: High resolution micro-CT scans were performed using a set voltage of 70 kV and current of 70 µA. Topographical Grading Scale: Each calvarial bone was blindly scored using the following scale: 0=No osteolysis, defined as intact bone; 1=Minimal osteolysis, affecting 1/3 or less of the bone area; 2=Moderate osteolysis, affecting at least 2/3 of the bone area; 3=Severe osteolysis, defined as completely osteolytic bone. Histology: H&E and TRAP staining was done on tissue to confirm micro-CT findings and quantify osteoclasts. Statistical Analysis: Inter-rater analysis was done using Cohen's kappa analysis. An inter-rater coefficient >0.65 was considered as high inter-rater agreement. Comparison between groups was made using one-way ANOVA with post hoc Bonferroni correction for multiple comparisons. Correlations are reported as Spearman's rho. P-value<0.05 was considered statistically significant. Results. More than 83% of the VE-UHMWPE and more than 85% of the virgin UHMWPE particles measured less than 1 µm in mean particle size. There was a statistically significant greater level of osteolysis visualized on the topographical grading scale in calvaria implanted with virgin UHMWPE wear particles. Micro-CT findings were confirmed histologically (Fig. 1). A greater amount of inflammatory tissue overlaying the calvaria was observed in the virgin UHMWPE group when compared to both shams and VE-UHMWPE groups. Post hoc analysis revealed significant difference between VE-UHMWPE and virgin UHMWPE for the topographical osteolysis grading score (p=0.002) but no difference in osteoclast counts (p=0.293). Discussion and Conclusion. This is the first in vivo study reporting the effects of clinically-relevant UHMWPE particles generated from a VE-UHMWPE implant that is in current clinical use. These results suggest that VE-UHMWPE particles have reduced osteolysis potential in vivo when compared to virgin, highly cross-linked UHMWPE in a murine calvarial bone model. Arthroplasty procedures using VE-UHMWPE might be less susceptible to peri-prosthetic loosening caused by wear debris

Heterotopic ossification (HO) occurs commonly after total hip arthroplasty (THA). Its severe form can result in impaired range of motion with reduced functional outcome. The rate and severity of HO after hip surface replacement arthroplasty (SRA) have never been well studied. Two hundred and ten hips were randomised to receive uncemented metal-on-metal THA or metal-on-metal SRA. Standard radiographs of the pelvis were assessed for HO by two reviewers at the latest follow-up (minimum of six months), using Brooker severity grading and Kjaersgaard-Andersen regional classification. The incidence of HO was 38.5% in the SRA group compared to 32.6% in the THA group (p=0.5). However, there was a significant difference in severity grades for the two groups (chi square, p=0.02). According to Brooker’s classification, nearly half of HO was of grade two in SRA and of grade one in THA. SRA was associated with significantly higher rates of severe HO (grades three and four) than THA (12.5% vs. 2.2%; p=0.009). Inter-rater agreement for Brooker grading was excellent (Cohen’s kappa, 0.88; p< 0.01). The incidence of HO after hip arthroplasty seems to be determined by patient-related factors. However, HO severity appears to be associated with local surgical factors and thereby SRA may result in more severe HO than THA. An extensive surgical approach, additional soft tissue release and the blunt damage occurring in gluteal muscles with SRA may signal the induction of more severe HO. Peri-operative deposition of bone debris derived from femoral head preparation may also play a role by transplanting osteoprogenitor cells. Surgeons must be aware of this risk of severe HO when offering SRA as an alternative treatment to younger patients. Routine prophylaxis with NSAIDs needs to be considered in these patients. A meticulous surgical technique to reduce muscle damage, pulsed lavage to clear bone debris, and debridement of necrotic tissue, may help to decrease the risk of severe HO in SRA

Introduction. In vitro findings (Bladed CL et al. ORS 2011 and J Biomed Mater Res B Appl Biomater, 2012) have suggested that UHMWPE wear particles containing vitamin-E (VE) may have reduced functional biologic activity and decreased osteolytic potential. Currently, there is no in vivo data determining the effects of wear debris from this new generation of implants. In this study we hypothesized that particles from VE-stabilized, radiation cross-linked UHMWPE (VE-UHMWPE) would cause reduced levels of osteolysis in a murine calvarial bone model when compared to virgin gamma irradiated cross-linked UHMWPE. Methods. Study groups: 1). Radiation cross-linked VE-UHMWPE, 0.8% by weight, diffused after 100 kGy; 2). Radiation cross-linked virgin UHMWPE (virgin UHMWPE); 3). Shams. Particle generation and implantation: UHMWPE was sent to Bioengineering Solutions for particle generation. After IACUC approval, C57BL/6 mice (n = 12 for each group) received 3 mg of particulate debris overlying the calvarium and euthanized after 10 days. Micro-CT scans: Performed using an X-Tek-HMX-ST-225 with 70 kV voltage and 70 μA current. Topographical Grading Scale: Each calvarial bone was blindly scored with the following scale: 0 = No osteolysis, defined as intact bone; 1 = Minimal osteolysis, affecting 1/3 or less of the bone area; 2 = Moderate osteolysis, affecting at least 2/3 of the bone area; 3 = Severe osteolysis, defined as completely osteolytic bone. Histology H&E and TRAP staining was performed. Statistical Analysis: Inter-rater analysis was performed using Cohen's kappa analysis. Inter-rater coefficient >0.65 was considered as high inter-rater agreement. Comparison between groups was made using one-way ANOVA with post hoc Bonferroni correction for multiple comparisons. Correlations are reported as Spearman's rho. A p-value<0.05 was considered statistically significant. Results. More than 83% of the VE-UHMWPE and more than 85% of the virgin UHMWPE particles measured less than 1 μm in mean particle size. There was a statistically significant greater level of osteolysis visualized on the topographical grading scale in calvaria implanted with virgin UHMWPE wear particles. The micro-CT findings were confirmed histologically (Fig. 1). A greater amount of inflammatory tissue overlaying the calvaria was observed in the virgin UHMWPE group when compared to both shams and VE-UHMWPE groups. Post hoc analysis revealed significant difference between VE-UHMWPE and virgin UHMWPE for the topographical osteolysis grading score (p = 0.002) but no difference in osteoclast count (p = 0.293). Discussion/Conclusion. This is the first in vivo study reporting the effects of clinically-relevant UHMWPE particles generated from a VE-UHMWPE implant that is in current clinical use. These results suggest that VE-UHMWPE particles have reduced osteolysis potential in vivo when compared to virgin, highly cross-linked UHMWPE in a murine calvarial bone model

Introduction: Heterotopic ossification (HO) occurs commonly after total hip arthroplasty (THA). Its severe form can result in impaired range of motion with reduced functional outcome. The rate and severity of HO after hip surface replacement arthroplasty (SRA) have never been well studied. Methods: Two hundred and ten hips (194 patients) were randomized to receive uncemented metal-on-metal THA (103) or metal-on-metal SRA (107). Standard antero-posterior radiographs of the pelvis were assessed for HO by 2 reviewers at the latest follow-up (minimum of 6 months), using Brooker severity grading and Kjaersgaard-Andersen regional classification. Results: Pre-operative and post-operative data were similar for both groups. The incidence of HO was 38.5% in the SRA group compared to 32.6% in the THA group (p=0.5). However, there was a significant difference in severity grades for the 2 groups (chi square, p=0.02). According to Brooker_s classification, nearly half of HO was of grade 2 in SRA and of grade 1 in THA. SRA was associated with significantly higher rates of severe HO (grades 3 and 4) than THA (12.5% vs. 2.2%; p=0.009). Inter-rater agreement for Brooker grading was excellent (Cohen_s kappa, 0.88; p< 0.01). HO in SRA involved both the central and lateral regions in 26% of cases, whereas only 3% of HO in THA showed such a pattern (p=0.025). Risk factors, such as male gender, osteoarthritis, bilateral predilection, and previous history of HO, were observed in both groups. Patients with HO had reduced internal hip rotation (16.4° vs. 22.2°; p=0.02) and a higher incidence of postoperative hip pain (52% vs. 30%; p=0.04), but comparable functional outcome scores. Discussion: The incidence of HO after hip arthroplasty seems to be determined by patient-related factors. However, HO severity appears to be associated with local surgical factors and thereby SRA may result in more severe HO than THA. An extensive surgical approach, additional soft tissue release and the blunt damage occurring in gluteal muscles with SRA may signal the induction of more severe HO. Peri-operative deposition of bone debris derived from femoral head preparation may also play a role by transplanting osteoprogenitor cells. Surgeons must be aware of this risk of severe HO when offering SRA as an alternative treatment to younger patients. Routine prophylaxis with NSAIDs needs to be considered in these patients. A meticulous surgical technique to reduce muscle damage, pulsed lavage to clear bone debris, and debridement of necrotic tissue, may help to decrease the risk of severe HO in SRA

We have developed a comprehensive system of assessment of patients undergoing total hip and total knee replacement. This new unified scoring system provides a single instrument to measure the disability of patients suffering from primary osteoarthritis of either hip or knee. This instrument will be used to prioritize these patients for a single waiting list and it will be used as an outcome measure to assess their progress after their hip or knee replacement surgery. The scoring system is comprised of two parts carrying equal point value. The subjective part is an assessment tool completed by the patients themselves. It is comprised of 12 Items covering every aspect of the disability associated with hip and knee arthritis. The objective part is an assessment tool completed by the treating physician or a trained joint arthroplasty nurse. The first stage of this project comprised of formulation of a preliminary questionnaire after a thorough assessment of 50 patients suffering from hip or knee arthritis. We then organised multiple clinical sessions with focus groups to critically appraise the content of our new questionnaire. The focus group patients were invited to give their comments about any issues not discussed previously. This preliminary questionnaire was then converted into a set of closed questions and was divided into a subjective and an objective part. The second stage of this project involved assignment of scales and scale grading for different components of the objective part. This involved the process of magnitude estimation. 75 patients, 25 consultants and 5 nurses were involved in this process. The third stage of this project involved a comprehensive assessment of this new scoring system in terms of internal consistency, internal consistency reliability, inter-observer reliability, test-retest reliability, face validity, content validity and construct validity. The process of validation involved comparison of our scoring system with the relevant parts of SF36, Oxford knee score, WOMAC and AIMS. It has also been tested on the first subset of post operative patients to measure its responsiveness. Cronbach’s alpha was used for internal consistency and Pearson’s correlation coefficients were used for different correlation studies. Our new scoring system has shown a very satisfactory internal consistency. The inter-rater agreement and the test-retest reliability data on the first set of 100 patients are very promising as well. The instrument has shown a significant effect size in the first set of post-op patients 4 months after their surgery. Our new scoring system will provide an easy to apply and comprehensive instrument for a need based waiting list for patients undergoing either THR or TKR. It will also be a reliable and sensitive outcome measure to monitor these patients’ progress in the post-operative period