Crosswalks between the Oxford hip and knee scores and the HOOS-12 and KOOS-12 instruments.

OBJECTIVE: To develop and validate bi-directional crosswalks between the Oxford Hip Score (OHS) and HOOS-12 summary impact score, and between the Oxford Knee Score (OKS) and KOOS-12 summary impact score. METHODS: Data were sourced from the Australian Orthopaedic Association National Joint Replacement Registry Patient-Reported Outcome Measures Program. Patients undergoing primary joint replacement for osteoarthritis who completed the OHS and HOOS-12 or OKS and KOOS-12 instruments were included in the analysis. An equipercentile method was used to create four crosswalks, with the distribution of scores smoothed using log-linear models prior to equating. Crosswalk validity was assessed through comparison of actual vs derived scores, Pearson correlation coefficients, root mean square errors (RMSE) and Bland-Altman plots. RESULTS: Paired OHS/HOOS-12 data and paired OKS/KOOS-12 data were available for 4,513 patients undergoing total hip replacement and 5,942 patients undergoing total knee replacement, respectively. Minimal differences were observed between actual and crosswalk-derived mean scores (actual OHS 27.55 vs derived OHS 27.56; actual HOOS-12 53.28 vs derived HOOS-12 53.31; actual OKS 27.34 vs derived OKS 27.34; actual KOOS-12 50.51 vs derived KOOS-12 50.58). High correlation was observed between actual and derived scores (Pearson's r for hip-specific instruments: 0.943-0.946; Pearson's r for knee-specific instruments: 0.925-0.931). Plotted actual vs mean derived scores also indicated robust concordance across the breadth of the instrument scales. CONCLUSION: These crosswalks provide close approximations of actual OHS, OKS, HOOS-12 and KOOS-12 scores, as indicated by multiple validation metrics. They offer a resource for clinicians, researchers and arthroplasty registries to support PROMs score conversion and data harmonisation efforts.

Rates, costs, return to work and reoperation following spinal surgery in a workers' compensation cohort in New South Wales, 2010-2018: a cohort study using administrative data.

BACKGROUND: Internationally, elective spinal surgery rates in workers' compensation populations are high, as are reoperation rates, while return-to-work rates following spinal surgery are low. Little information is available from Australia. The aim of this study was to describe the rates, costs, return to work and reoperation following elective spinal surgery in the workers' compensation population in New South Wales (NSW), Australia. METHODS: This retrospective cohort study used administrative data from the State Insurance Regulatory Authority, the government organisation responsible for regulating and administering workers' compensation insurance in NSW. These data cover all workers' compensation-insured workers in New South Wales (over 3 million workers/year). We identified a cohort of insured workers who underwent elective spinal surgery (fusion or decompression) between January 1, 2010 and December 31, 2018. People who underwent surgery for spinal fracture or dislocation, or who had sustained a traumatic brain injury were excluded. The main outcome measures were annual spinal surgery rates, cost of the surgical episode, cumulative costs (surgical, hospital, medical and physical therapy) to 2 years post-surgery, and reoperation and return-to-work rates 2 years post-surgery. RESULTS: There were 9343 eligible claims (39.1 % fusion; 59.9 % decompression); claimants were predominantly male (75 %) with a mean age of 43 (range 18 to 75) years. Spinal surgery rates ranged from 15 to 29 surgeries per 100,000 workers per year, fell from 2011-12 to 2014-15 and rose thereafter. The average cost in Australian dollars for a surgical episode was $46,000 for a spinal fusion and $20,000 for a decompression. Two years post-fusion, only 19 % of people had returned to work at full capacity; 39 % after decompression. Nineteen percent of patients underwent additional spinal surgery within 2 years of the index surgery, to a maximum of 5 additional surgeries. CONCLUSION: Rates of workers' compensation-funded spinal surgery did not rise significantly during the study period, but reoperation rates are high and return-to-work rates are low in this population at 2 years post- surgery. In the context of the poor evidence base supporting lumbar fusion surgery, the high cost, increasing rates, and the increased likelihood of poor outcomes in the workers' compensation population, we question the value of this procedure in this setting.

Observing the use of knee arthroplasty appropriateness tools in clinical practice: do appropriateness criteria tools predict surgeon decision-making?

OBJECTIVE: The primary aim of this study was to evaluate the agreement between surgeons and two validated total knee arthroplasty (TKA) appropriateness tools, and secondarily to compare Australian appropriateness rates to those reported internationally. METHODS: A consecutive sample of patients from one public hospital arthroplasty clinic and a convenience sample from private rooms of surgeons in New South Wales, Australia (n = 11), referred for surgical opinion regarding TKA were enrolled over 1 year. Surgeons applied appropriateness tools created by Escobar et al. and the American Academy of Orthopaedic Surgeons (AAOS). Correlation between the appropriateness tools and surgeon's decisions were evaluated. RESULTS: There were 368 patients enrolled, and contrasting rates of being "appropriate" for surgery were identified between the Escobar (n = 109, 29.6%) and AAOS (n = 292, 79.3%) tools. Surgeon agreement with the Escobar tool was substantial (ĸ = 0.61, 95%CI: 0.53-0.69) compared to slight with the AAOS tool (ĸ = 0.11, 95%CI: 0.06-0.16). Of those advised against TKA (n = 179, 48.6%), the AAOS tool suggested many patients (n = 111, 62.0%) were "appropriate" compared to the Escobar tool (n = 12, 6.7%). CONCLUSIONS: Surgeons rated patients seeking opinion for TKA as appropriate over half the time, however the AAOS tool had low correlation with surgeons as opposed to the Escobar tool. This was illustrated by both tools rating a majority of patients to be operated on as appropriate, but only the AAOS tool considering most patients not chosen for surgery to be appropriate. When comparing previously published appropriateness rates, appropriateness in Australia, USA, Spain and Qatar was found to be similar.

Performance of the HOOS-12 and KOOS-12 instruments for evaluating outcomes from joint replacement surgery.

OBJECTIVE: To evaluate the psychometric properties of the 12-item Hip disability and Osteoarthritis Outcome Score (HOOS-12) and Knee injury and Osteoarthritis Outcome Score (KOOS-12) for use in evaluating outcomes after joint replacement for osteoarthritis. DESIGN: Patient-reported outcomes data collected by the Australian Orthopaedic Association National Joint Replacement Registry were used for this analysis. HOOS-12 and KOOS-12 domain (pain, function, quality of life) and summary impact data were available. The Oxford Hip Score (OHS), Oxford Knee Score (OKS) and EQ-5D-5L were used as comparators. Instruments were administered pre-operatively and at 6 months post-operatively. Internal consistency reliability, floor and ceiling effects, convergent validity, known groups validity, and responsiveness were evaluated using standard psychometric techniques. RESULTS: Baseline HOOS-12 and KOOS-12 data were available for 3,023 patients undergoing primary total hip replacement and 4,010 patients undergoing primary total knee replacement. At baseline, high internal consistency was demonstrated for all domains and summary scores (Cronbach's alpha: HOOS-12 = 0.81-0.93; KOOS-12 = 0.82-0.92). Post-operative ceiling effects (>15% of patients scoring the best possible score) were identified for the HOOS-12 pain (46%), function (39%) and quality of life domains (26%) and summary score (17%), and for the KOOS-12 pain (21%) and function domains (18%). The HOOS-12 and KOOS-12 could differentiate between two known groups (lowest/highest OHS or OKS quartiles post-operatively; p < 0.001) and were highly responsive to change (effect sizes for HOOS-12: 2.20-2.83; KOOS-12: 1.82-2.35). CONCLUSION: The HOOS-12 and KOOS-12 have good psychometric properties for capturing joint replacement outcomes including excellent responsiveness, although ceiling effects may limit monitoring of post-operative improvement.

Implications for research and clinical use from a Rasch analysis of the HOOS-12 and KOOS-12 instruments.

OBJECTIVE: To evaluate the structural validity of the 12-item Hip disability and Osteoarthritis Outcome Score (HOOS-12) and 12-item Knee injury and Osteoarthritis Outcome Score (KOOS-12) using Rasch analysis and consider psychometric implications for research and clinical use. METHOD: Individual-level HOOS-12 and KOOS-12 data from the Australian Orthopaedic Association National Joint Replacement Registry, collected before and after primary total hip and knee replacement, were used for this analysis. Using the Rasch analytic approach, overall model fit and item fit were examined, together with potential reasons for misfit including response threshold ordering, differential item functioning, internal consistency, unidimensionality and item targeting. RESULTS: Overall misfit to the Rasch model was evident for both instruments. A degree of item misfit was also observed, although most items demonstrated logical sequencing of response options. Only two items (hip/knee pain frequency and awareness of hip/knee problems) displayed disordered response thresholds. The pain, function, and quality of life domains of the HOOS-12 and KOOS-12 demonstrated excellent internal consistency reliability (person separation index: 0.80-0.93) and unidimensionality. A mismatch between item difficulty and person ability scores at the highest end of the HOOS-12 and KOOS-12 scales contributed to post-operative ceiling effects (mean logit for HOOS-12: 3.57; KOOS-12: 2.58; ≈0 indicates well-targeted scale). CONCLUSION: We found evidence to support the structural validity of the three HOOS-12 and KOOS-12 domains for evaluating joint replacement outcomes. However, there may be missing content in both instruments particularly for high-functioning patients. Minor refinement of some response options may be warranted to improve item performance.

The effect of a multidisciplinary care bundle on the incidence of delirium after hip fracture surgery: a quality improvement study.

Delirium is a common complication following hip fracture surgery. We introduced a peri-operative care bundle that standardised management in the emergency department, operating theatre and ward. This incorporated: use of fascia iliaca blocks; rationalisation of analgesia; avoidance of drugs known to trigger delirium; a regular education program for staff; and continuous auditing of compliance. The study was conducted between June 2017 and December 2018. We recruited 150 patients before (control group) and 150 patients after (care bundle group) the introduction of the care bundle. In patients having surgery for a hip fracture, there was a lower incidence of delirium on the third postoperative day in the care bundle group compared with the control group (33 patients (22%) vs. 49 patients (33%)), respectively; p = 0.04). Patients in the care bundle group had an adjusted OR of 2.2 (95%CI 1.1-4.4) (p = 0.03) for the avoidance of delirium on the third postoperative day. There was no difference between groups for the secondary outcome measures (measured at 30 days postoperatively) including: all-cause mortality; composite morbidity; institutionalisation; and walking status. During the study period, compliance with elements of the care bundle improved in the emergency department (49 patients (33%) compared with 85 patients (59%); p < 0.001) and anaesthetic department (40 patients (27%) compared with 104 patients (69%); p < 0.001), while orthogeriatrics maintained a high level of compliance (140 patients (93%) compared with 143 patients (95%); p = 0.45). There was a clinically and statistically significant reduction in the incidence of delirium following hip fracture surgery in patients treated with a multidisciplinary care bundle.

Practice variation in total hip arthroplasty versus hemiarthroplasty for treatment of fractured neck of femur in Australia.

AIMS: Displaced femoral neck fractures (FNF) may be treated with partial (hemiarthroplasty, HA) or total hip arthroplasty (THA), with recent recommendations advising that THA be used in community-ambulant patients. This study aims to determine the association between the proportion of FNF treated with THA and year of surgery, day of the week, surgeon practice, and private versus public hospitals, adjusting for known confounders. PATIENTS AND METHODS: Data from 67 620 patients in the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) from 1999 to 2016 inclusive were used to generate unadjusted and adjusted analyses of the associations between patient, time, surgeon and institution factors, and the proportion of FNF treated with THA. RESULTS: Overall, THA was used in 23.7% of patients. THA was more frequently used over time, in younger patients, in healthier patients, in cases performed on weekdays (adjusted odds ratio (OR) 1.27; 95% confidence interval (CI) 1.14 to 1.41), in private hospitals (adjusted OR 4.34; 95% CI 3.94 to 4.79) and by surgeons whose hip arthroplasty practice has a relatively higher proportion of elective patients (adjusted OR 1.65; 95% CI 1.49 to 1.83). CONCLUSION: Practice variation exists in the proportion of FNF patients treated with THA due to variables other than patient factors. This may reflect variation in resources available and surgeon preference, and uncertainty regarding the relative indication.

A controlled before-after study to evaluate the effect of a clinician led policy to reduce knee arthroscopy in NSW.

BACKGROUND: Clinical evidence shows knee arthroscopy has little benefit for degenerative conditions and considerable variation in the incidence of knee arthroscopy in Australia has been identified. This study aimed to evaluate a clinician-led evidence-based policy which was implemented in one local health district in New South Wales (NSW) in 2012 to reduce the use of knee arthroscopy for patients aged 50 years or over. METHODS: Trends in rates and volume of knee arthroscopy for patients 50 years or over in NSW between 2004 and 2015 by district were examined. Changes at four hospitals that adopted the policy were assessed by a quasi-experimental before and after study design with control groups, using the generalised estimating equations (GEE) Poisson model. Each case hospital was matched with four control hospitals in terms of the volume of knee arthroscopy surgeries performed in the five years prior to the intervention. RESULTS: Between 2004 and 2015, the number of knee arthroscopies in NSW initially increased and then decreased after 2011, with considerable variation across districts. While an overall reducing trend in NSW was observed between 2011 and 2015 (39%), a 58% reduction (95% CI: 55-62%) was found in the intervention district, including the private sector, being the greatest reduction found in all districts. The GEE Poisson results show that, compared with control hospitals, the number of knee arthroscopy was significantly reduced by 56% (95% CI: 11%-79%) at four hospitals that adopted the policy during the follow-up period (p = 0.02). CONCLUSIONS: Clinicians in one local health district initiated a policy to restrict knee arthroscopy for patients aged 50 years or over, which may explain the greater reduction seen in that district compared to all others, despite an overall decrease noted in the state. A significant reduction found at intervened hospitals proved the effect of the policy, suggesting that the implementation of a simple clinical governance process may help reduce inappropriate surgery.

Arthroscopic surgery for degenerative knee arthritis and meniscal tears: a clinical practice guideline

The role of arthroscopic surgery in degenerative knee disease was evaluated in this guideline.

A Comparison of Plain Radiography with Computer Tomography in Determining Coronal and Sagittal Alignments following Total Knee Arthroplasty.

Introduction: Optimal coronal and sagittal component positioning is important in achieving a successful outcome following total knee arthroplasty (TKA). Modalities to determine post-operative alignment include plain radiography and computer tomography (CT) imaging. This study aims to determine the accuracy and reliability of plain radiographs in measuring coronal and sagittal alignment following TKA. Materials and Methods: A prospective, consecutive study of 58 patients undergoing TKA was performed comparing alignment data from plain radiographs and CT imaging. Hip-knee-angle (HKA), sagittal femoral angle (SFA) and sagittal tibial angle (STA) measurements were taken by two observers from plain radiographs and compared with CT alignment. Intra- and inter-observer correlation was calculated for each measurement. Results: Intra-observer correlation was excellent for HKA (r>0.89) with a mean difference of <1.9°. The least intra-observer correlation was for SFA (mean r=0.58) with a mean difference of 8°. Inter-observer correlation was better for HKA (r>0.95) and STA (r>0.8) compared to SFA (r=0.5). When comparing modalities (radiographs vs CT), HKA estimations for both observers showed the least maximum and mean differences while SFA observations were the least accurate. Conclusion: Radiographic estimation of HKA showed excellent intra- and inter-observer correlation and corresponds well with CT imaging. However, radiographic estimation of sagittal plane alignment was less reliably measured and correlated less with CT imaging. Plain radiography was found to be inferior to CT for estimation of biplanar prosthetic alignment following TKA.

An equivalence study: Are patient-completed and telephone interview equivalent modes of administration for the EuroQol survey?

BACKGROUND: To determine if the EuroQol Health Related Quality of Life survey produces equivalent results when administered by phone interview or patient-completed forms. METHODS: People awaiting hip or knee arthroplasty at a major metropolitan hospital participated. They were randomly assigned to receive the EuroQol Health Related Quality of Life survey via telephone, followed by a patient completed form 1 week later, or vice versa. Equivalence was determined using two one-sided tests (TOST) based on minimal clinically-important differences for the visual analogue scale (VAS) and the summary Utility Index. Cohen's Kappa scores were computed to determine agreement for the individual EuroQoL Likert scale items. RESULTS: Seventy-six from 90 (84%) participants completed the survey twice. Based on limits set at ±7 and ±0.11 for the VAS and Utility Index, respectively, equivalence was established between the two methods of administration for both the VAS (mean difference 0.05 [90% CI -3.76-3.67]) and the Utility Index (mean difference 0.06 [90% CI 0.02-0.11]). Varying levels of agreement, ranging from slight to substantial (κ = 0.17-0.67), were demonstrated for the individual health domains. The order of telephone and patient-completed survey administration had no significant effect on results. CONCLUSIONS: Equivalent results are obtained between telephone and patient-completed administration for the VAS and Utility Index of the EuroQol Survey in people with advanced hip or knee osteoarthritis. The limits of agreement for the individual health domains vary which prevents the accurate interpretation of real change in these items across modes.

Clinical and financial benefits of intra-articular tranexamic acid in total knee arthroplasty.

PURPOSE: To determine whether intra-articular tranexamic acid (TXA) use after total knee arthroplasty (TKA) results in decreased postoperative blood transfusion and length of hospital stay. METHODS: Medical records of 1981 patients (mean age, 69.2 years) who underwent primary TKA with (n=1006) or without (n=975) TXA use by any of 4 knee arthroplasty surgeons were reviewed. TXA (3000 mg/30ml) was administered via an epidural catheter into the knee joint after wound closure. Postoperative blood transfusion was given to patients with haemoglobin (Hb) level <80 g/dl on days 1 and 2 or with symptoms of acute anaemia. RESULTS: Intra-articular TXA use after TKA resulted in a lower blood transfusion rate (4.5% [45/1006] vs. 14.8% [144/975], p<0.0001), fewer units of blood transfused (86 vs. 313 units, p<0.0001), fewer units of blood transfused per 100 patients (8.5 vs. 32.1, p<0.0001), and shorter length of hospital stay (4.7±2.3 vs. 5.3±2.7 days, p<0.0001). Total cost savings with respect to the reduction in blood transfusion was AU$143.68 per patient. When the change in length of hospital stay and TXA costs were included, the overall saving was AU$631.36 per patient. CONCLUSION: Intra-articular TXA use can reduce costs as a result of decreased blood transfusion rate and length of hospital stay in patients undergoing TKA.

Presence and predictors of persistent pain among persons who sustained an injury in a road traffic crash.

BACKGROUND: There is a paucity of prospective studies with long follow-up that have examined a wide range of correlates associated with persistent pain outcomes in persons who sustained a mild or moderate injury in a road traffic crash. This study aimed to establish the independent predictors of pain severity over 24 months. METHODS: A total of 364, 284 and 252 persons with mild/moderate musculoskeletal injuries sustained in a vehicle-related crash participated in telephone interviews in the subacute phase, and at 12 and 24 months, respectively. The numeric rating scale (NRS) assessed pain severity. Pain-Related Self-Statements Scale-Catastrophizing (PRSS-Catastrophizing) and the Short Form Orebro Musculoskeletal Pain Screening Questionnaire (OMPSQ) were also administered. RESULTS: After multivariable adjustment, each 1 SD increase in Short Form-12 Physical Component Score (SF-12 PCS) in the subacute phase was associated with 0.73 (p = 0.002) and 1.11 (p < 0.0001) decrease in NRS scores after 12 and 24 months, respectively. Each unit increase in the PRSS-Catastrophizing score in the subacute phase was associated with 0.54 (p = 0.001) and 0.43 (p = 0.03) increase in NRS scores 12 and 24 months later, respectively. Subacute phase OMPSQ scores were positively associated with NRS scores at 12- and 24-month follow-ups (p < 0.0001). CONCLUSIONS: Self-perceived physical well-being, pain-related work disability and pain catastrophizing could play a role in determining long-term pain-related outcomes following traffic-related injuries.

Mail versus telephone administration of the Oxford Knee and Hip Scores.

Telephone and postal methods of administration of the Oxford Knee Score (OKS) and the Oxford Hip Score (OHS) were compared on 85 and 61 patients undergoing total knee arthroplasty (TKA) and total hip arthroplasty (THA), respectively. The test for equivalence was significant for both the knee (P<0.001) and hip participants (P<0.001) indicating that the modes of administration yielded similar results. The ICCs of the OKS and OHS were 0.79 (95% Confidence Interval (CI) 0.70, 0.86) and 0.87 (0.79, 0.92) respectively. The 95% limits of agreement were wide for both scores (OKS LOA, -8.6, 8.2; OHS LOA, -7.7, 5.3). The two modes of administration of the OKS and OHS produce equivalent survey responses at a group level but the same method of administration should be constant for individual monitoring in a clinical setting.

Practice variation in common fracture presentations: a survey of orthopaedic surgeons.

BACKGROUND: Practice variation may indicate a lack of clear evidence to guide treatment. This study aims to quantify practice variation for common orthopaedic fractures, and to explore possible predictors of the variation. MATERIALS AND METHODS: A nationwide electronic survey of Australian orthopaedic surgeons was performed. Five common fractures (ankle, scaphoid, distal radius, neck of humerus, and clavicle) were presented. Data on management preferences and surgeon background were gathered. Potential predictors of operative (vs. non-operative) treatment were explored. RESULTS: 358 of 760 (47%) surgeons responded. For the ankle, undisplaced scaphoid, distal radius, neck of humerus and clavicle fractures, operative treatment was chosen in 40%, 44%, 77%, 26% and 38%, respectively. Operative treatment was significantly more likely to be chosen by more junior surgeons, and by surgeons specialising in the affected area (i.e., shoulder surgeons for clavicle and neck of humerus fractures, and hand surgeons for scaphoid and distal radius fractures). CONCLUSIONS: Variations exist in the management of common fractures. Variation may represent legitimate improvisation for varying clinical scenarios, but it may reflect clinician bias, which in turn, may contribute to varying standards of care for the management of common conditions.

Orthopaedic trauma surgery performed by unsupervised and supervised trainees: complication rates compared.

PURPOSE: To compare the complication rates associated with orthopaedic trauma surgery performed by unsupervised and supervised trainees. METHODS: In our hospital, 6361 orthopaedic trauma operations were performed between 1 January 1998 and 31 December 2002. Data pertinent to the surgeon's supervision and postoperative complications were collected. Elective operations were excluded, as consultants were almost always present. Complication rates ensuing in unsupervised and supervised groups were compared using the Chi squared test. RESULTS: Of 6361 orthopaedic trauma operations performed, 3754 (59%) were by unsupervised trainees of varying experience, whereas 2494 (39%) were by supervised trainees or consultants. In 113 (2%) of the operations, the supervision status was not recorded. The complication rate was significantly higher in the supervised than unsupervised group (5.3 vs 3.3%, Chi squared=15, df=1, p=0.0001). CONCLUSION: The complication rate was not higher for operations performed by unsupervised trainees than those performed in the presence of a consultant.

Intramedullary nailing versus fixed angle blade plating for subtrochanteric femoral fractures: a prospective randomised controlled trial.

PURPOSE: To compare closed intramedullary nailing to open reduction and internal fixation using a fixed angle blade plate for the management of subtrochanteric femoral fractures. METHODS: 58 patients were equally randomised to undergo either an intramedullary nailing (IN) or fixed angle blade plating (BP). RESULTS: There were no significant differences between the 2 groups with regard to age, time to surgery, operating time, receipt of blood transfusions, duration of hospital stay, or fracture classification. The revision rate was 28% (8/29) in the BP group and none in the IN group; the difference was statistically significant. CONCLUSION: Internal fixation using a fixed angle blade plate for subtrochanteric femoral fractures has higher implant failure and revision rates, compared to closed intramedullary nailing.

Publication bias in abstracts presented to the annual meeting of the American Academy of Orthopaedic Surgeons.

PURPOSE: To examine possible causes of publication bias in the orthopaedic literature so as to avoid inappropriate clinical decisions based on reviews of the literature. METHODS: Two reviewers independently reviewed abstracts presented to the 1999 American Academy of Orthopaedic Surgeons annual meeting. Data pertaining to sample size, statistical significance, study setting, country of origin, outcome, study type, and sponsorship were extracted from each abstract. The publication rate was measured after 5 years, by electronic searching and author contact. Predictors of publication were identified using logistic regression analysis. RESULTS: Of the 318 abstracts listed in the proceedings, 175 (55%) were published within 5 years. Publication was associated with positive rather than neutral outcomes (odds ratio, 1.62; 95% confidence interval, 1.01-2.59; p<0.05) and with the reporting of statistical significance (odds ratio, 2.05; 95% confidence interval 1.24-3.39; p=0.005). Sponsorship, country of origin, sample size, study setting, and study type did not significantly influence the publication rate. CONCLUSION: Evidence of publication bias exists in abstracts presented at the 1999 American Academy of Orthopaedic Surgeons annual meeting. Clinical decisions based on the literature may be biased due to an over-representation of studies with positive outcomes.