Suzie Cro

Material Loss at the Taper Junction of Retrieved Large Head Metal-on-Metal Total Hip Replacements

It has been speculated that material loss, either as corrosion or wear, at the head–stem taper junction is implicated in the high revision rates reported for metal‐on‐metal total hip replacements. We measured the volume of material loss from the taper and bearing surfaces of retrieved devices, and investigated the associations with blood metal ion levels and the diagnosis of a cystic or solid pseudotumor. The median volumes of material lost from the female and male taper surfaces were 2.0 and 0.29 mm3, respectively, while the median volumes of wear from the cup and head bearing surfaces were 1.94 and 3.44 mm3, respectively. Material loss from the female taper was similar to that from the acetabular bearing surface (p = 0.55), but significantly less than that from the femoral bearing surface (p < 0.001). Material loss from the male taper was less than that from both bearing surfaces (p < 0.001). Multivariable analysis demonstrated no significant correlations between the volume of material lost from the taper surfaces and either blood cobalt or chromium ions, or the presence of pseudotumor. While a substantial volume of material is lost at the taper junction, the clinical significance of this debris remains unclear.

Postoperative spinal epidural hematoma (SEH): incidence, risk factors, onset, and management

BACKGROUND CONTEXT Spinal epidural hematoma (SEH) is a rare, yet potentially devastating complication of spinal surgery. There is limited evidence available regarding the risk factors and timing for development of symptomatic SEH after spinal surgery. PURPOSE To assess the incidence, risk factors, time of the onset, and effect of early evacuation of symptomatic SEH after spinal surgery. STUDY DESIGN Multicenter case control study. PATIENT SAMPLE All patients who underwent open spinal surgery between October 1, 1999, and September 30, 2006, at the National Hospital For Neurology and Neurosurgery (NHNN) and the Wellington Hospital (WH) were reviewed. OUTCOME MEASURES Frankel grade. METHODS Patients who developed SEH and underwent evacuation of the hematoma were identified. Two controls per case were selected. Each control had undergone a procedure with similar complexity, at the same section of the spine, at the same hospital, and under the same surgeon within 6 months of the initial operation. RESULTS A total of 4,568 open spinal operations were performed at NHNN and WH. After spinal surgery, 0.22% of patients developed symptomatic SEH. Alcohol greater than 10 units a week (p=.031), previous spinal surgery (p=.007), and multilevel procedures (p=.002) were shown to be risk factors. Initial symptoms of SEH presented after a median time of 2.7 hours (interquartile range [IQR], 1.1-126.1). Patients who had evacuation surgery within 6 hours of the onset of initial symptoms improved a median of 2 (IQR, 1.0-3.0) Frankel grades, and those who had surgery more than 6 hours after the onset of symptoms improved 1.0 (IQR, 0.0-1.5) Frankel grade, p=.379. CONCLUSIONS Symptomatic postoperative SEH is rare, occurring in 0.22% of cases. Alcohol consumption greater than 10 units a week, multilevel procedure, and previous spinal surgery were identified as risk factors for developing SEH. Spinal epidural hematoma often presents early in the postoperative period, highlighting the importance of close patient monitoring within the first 4 hours after surgery. This study suggests that earlier surgical intervention may result in greater neurological recovery.

Predicting wear and blood metal ion levels in metal‐on‐metal hip resurfacing

Suboptimal component position and design are thought to lead to edge wear and raised blood metal ion levels in metal‐on‐metal hip resurfacing (MOM‐HR). These factors are thought to influence the “contact patch to rim distance” (CPRD), and calculation of this distance may improve prediction of wear and blood metal ion levels. We measured blood cobalt and chromium ion levels and the wear rates of the bearing surfaces in 165 MOM‐HR retrieval cases. We then determined the contribution and effect sizes of cup inclination and version angles, component size and design, and CPRD (calculated from case‐specific data) on blood metal ion levels and component wear rates. Acetabular orientation explained between 16.3% and 28.5% of the variation in wear rates and metal ion levels, whereas component size and design explained between 7.3% and 21.8% of the variability. In comparison, CPRD explained up to 67.7% of the variability, significantly greater than any other variable (all p < 0.0001). CPRD is a good predictor of wear and improves our understanding of wear performance and the mechanisms leading to edge loading.

A comparison of the diagnostic accuracy of MARS MRI and ultrasound of the painful metal-on-metal hip arthroplasty.

Background and purpose — Metal artifact reduction sequence (MARS) MRI and ultrasound scanning (USS) can both be used to detect pseudotumors, abductor muscle atrophy, and tendinous pathology in patients with painful metal-on-metal (MOM) hip arthroplasty. We wanted to determine the diagnostic test characteristics of USS using MARS MRI as a reference for detection of pseudotumors and muscle atrophy. Patients and methods — We performed a prospective cohort study to compare MARS MRI and USS findings in 19 consecutive patients with unilateral MOM hips. Protocolized USS was performed by consultant musculoskeletal radiologists who were blinded regarding clinical details. Reports were independently compared with MARS MRI, the imaging gold standard, to calculate predictive values. Results — The prevalence of pseudotumors on MARS MRI was 68% (95% CI: 43–87) and on USS it was 53% (CI: 29–76). The sensitivity of USS in detecting pseudotumors was 69% (CI 39–91) and the specificity was 83% (CI: 36–97). The sensitivity of detection of abductor muscle atrophy was 47% (CI: 24–71). In addition, joint effusion was detected in 10 cases by USS and none were seen by MARS MRI. Interpretation — We found a poor agreement between USS and MARS MRI. USS was inferior to MARS MRI for detection of pseudotumors and muscle atrophy, but it was superior for detection of joint effusion and tendinous pathologies. MARS MRI is more advantageous than USS for practical reasons, including preoperative planning and longitudinal comparison.

Levels of evidence in foot and ankle surgery literature: progress from 2000 to 2010?

BACKGROUND The focus on evidence-based medicine has led to calls for increased levels of evidence in surgical journals. The purpose of the present study was to review the levels of evidence in articles published in the foot and ankle literature and to assess changes in the level of evidence over a decade. METHODS All of the articles in the literature from the years 2000, 2005, and 2010 in Foot & Ankle International and Foot and Ankle Surgery, as well as all foot and ankle articles from The Journal of Bone and Joint Surgery (JBJS, American [A] and British [B] Volumes) were analyzed. Animal, cadaver, and basic science articles; editorials; surveys; special topics; letters to the editor; and correspondence were excluded. Articles were ranked by a five-point level-of-evidence scale, according to guidelines from the Centre for Evidence-Based Medicine. RESULTS A total of 720 articles from forty-three different countries were analyzed. The kappa value for interobserver reliability showed very good agreement between the reviewers for types of evidence (κ = 0.816 [p < 0.01]) and excellent agreement for levels of evidence (κ = 0.869 [p < 0.01]). Between 2000 and 2010, the percentage of high levels of evidence (Levels I and II) increased (5.2% to 10.3%) and low levels of evidence (Levels III, IV, and V) decreased (94.8% to 89.7%). The most frequent type of study was therapeutic. The JBJS-A produced the highest proportion of high levels of evidence. CONCLUSION There has been a trend toward higher levels of evidence in foot and ankle surgery literature over a decade, but the differences did not reach significance.

Does source of funding and conflict of interest influence the outcome and quality of spinal research

BACKGROUND/CONTEXT There has been longstanding controversy surrounding the influence of funding source on the conduct and outcome of medical research. In 2011, a systematic review of the use of recombinant bone morphogenetic protein-2 revealed underreporting of unfavorable outcomes in some industry-sponsored trials. We hypothesize that Industrial funding and the presence of potential conflict of interest will be associated with low levels of evidence (LOE) and greater proportions of favorable outcomes in spinal research. PURPOSE The aim of this study is to investigate the association between funding source and potential conflict of interest on the LOE and study outcome in the current spinal research. STUDY DESIGN/SETTING Systematic review of all the spinal publications in five leading spinal, orthopedics, neurosurgery, and general medical journals during 2010 (print and online). Supplements were included. OUTCOME MEASURE Outcome and the LOE of research papers. METHODS Two reviewers independently assessed all publications. Commentaries, editorials, letters, open operating theatres, case reports, narrative reviews, and study protocols were excluded. The self-reported potential conflict of interest and type of funding was extracted from each paper. Funding type was classified as foundation, industry, public, intramural, multiple (including industry), multiple (without industry), and unfunded. The outcome of each study was classified as favorable, unfavorable, equivocal, or not applicable. Clinical publications were ranked using the LOE guidelines produced by the Oxford Center for Evidence-Based Medicine. RESULTS Overall, 1356 papers were analyzed, out of which 864 were suitable for LOE grading. There was good interobserver reliability for assignment of LOE grade, κ=0.897 (p<.01) and study outcome κ=0.804 (p<.01). A significant association was found between LOE and source of funding (p<.01). Industry-funded studies had the greatest proportion of level IV evidence (65%). There was a significant association between the funding source and study outcome (p=.01). The proportion of industry-funded studies with favorable outcomes (88%) was higher than that of publicly and foundation-funded studies (73% and 74%, respectively). The associated odds ratio for reporting favorable outcomes in industry-funded studies compared with studies with public and foundation funding was 2.7 (95% confidence interval [CI], 1.4-5.3), and 2.6 (95% CI, 1.3-5.2), respectively. A significant association between LOE and study outcome (p<.01) was also identified. Level I studies had the highest proportions of unfavorable (14%) and equivocal (23%) outcomes. Level IV studies had the highest proportion of favorable outcome (85%). There was no association between self-reported conflict of interest and LOE (p=.83) or study outcome (p=.25). CONCLUSION We demonstrated a significant association between source of funding, study outcome, and LOE in spinal research. A large proportion of industry funded research was shown to provide level IV evidence and report favorable outcome.

Reducing bias in open-label trials where blinded outcome assessment is not feasible: strategies from two randomised trials.

BackgroundBlinded outcome assessment is recommended in open-label trials to reduce bias, however it is not always feasible. It is therefore important to find other means of reducing bias in these scenarios.MethodsWe describe two randomised trials where blinded outcome assessment was not possible, and discuss the strategies used to reduce the possibility of bias.ResultsTRIGGER was an open-label cluster randomised trial whose primary outcome was further bleeding. Because of the cluster randomisation, all researchers in a hospital were aware of treatment allocation and so could not perform a blinded assessment. A blinded adjudication committee was also not feasible as it was impossible to compile relevant information to send to the committee in a blinded manner. Therefore, the definition of further bleeding was modified to exclude subjective aspects (such as whether symptoms like vomiting blood were severe enough to indicate the outcome had been met), leaving only objective aspects (the presence versus absence of active bleeding in the upper gastrointestinal tract confirmed by an internal examination).TAPPS was an open-label trial whose primary outcome was whether the patient was referred for a pleural drainage procedure. Allowing a blinded assessor to decide whether to refer the patient for a procedure was not feasible as many clinicians may be reluctant to enrol patients into the trial if they cannot be involved in their care during follow-up. Assessment by an adjudication committee was not possible, as the outcome either occurred or did not. Therefore, the decision pathway for procedure referral was modified. If a chest x-ray indicated that more than a third of the pleural space filled with fluid, the patient could be referred for a procedure; otherwise, the unblinded clinician was required to reach a consensus on referral with a blinded assessor. This process allowed the unblinded clinician to be involved in the patient’s care, while reducing the potential for bias.ConclusionsWhen blinded outcome assessment is not possible, it may be useful to modify the outcome definition or method of assessment to reduce the risk of bias.Trial registrationTRIGGER: ISRCTN85757829. Registered 26 July 2012.TAPPS: ISRCTN47845793. Registered 28 May 2012.

Return to Play After Lateral Meniscectomy Compared With Medial Meniscectomy in Elite Professional Soccer Players

Background: Meniscectomy is frequently performed in elite soccer athletes to allow return to a high level of performance as early as possible. Although lateral meniscectomy is known to have more serious long-term sequelae than medial meniscectomy, little is known about the effect of lateral meniscectomy on the time to return to play during the early recovery phase in professional soccer players. Hypothesis: Lateral meniscectomy results in longer times to return to preinjury level of competition and a higher incidence of adverse outcomes compared with medial meniscectomy in elite professional soccer players. Study Design: Cohort study; Level of evidence, 3. Methods: A single-surgeon database containing the injury history and operative details of elite soccer athletes from 2005 to 2009 was used to identify players who had undergone an isolated partial lateral or medial meniscectomy. The time to return to preinjury level of competition, the incidence of adverse events during early recovery, and the need for further arthroscopy were recorded. Time to return to play was analyzed by using the Kaplan-Meier method. A multivariate analysis was used to control for age, location of meniscectomy, percentage of meniscus excised, and type of tear. Results: Ninety soccer players were identified, of which 42 had a lateral meniscectomy and 48 had a medial meniscectomy. The median time to return to play, to the nearest week, was longer in the lateral group than the medial group (7 vs 5; P < .001). At all time points after surgery, the cumulative probability of returning to play was 5.99 times greater (95% confidence interval, 3.34-10.74; P < .001) after medial meniscectomy. More lateral meniscectomy cases experienced adverse events related to pain/swelling—29 (69%) vs 4 (8%) (P < .001)—and required a second arthroscopy: 3 (7%) vs 0 (P = .098). Conclusion: The time to return to preinjury level of competition is significantly longer after lateral than medial meniscectomy in elite professional soccer athletes. Lateral meniscectomy has a higher incidence of adverse events in the early recovery period, including pain/swelling and the need for further arthroscopy. It is also associated with a significantly lower rate of return to play. These findings form the basis of an important discussion that must be had with player and club before a lateral meniscectomy is performed in elite soccer athletes.

Rehabilitation Following Surgery for Lumbar Spinal Stenosis A Cochrane Review

Study Design. A systematic review of randomized controlled trials. Objective. To determine the effects of active rehabilitation on functional outcome after lumbar spinal stenosis surgery when compared with “usual postoperative care.” Summary of Background Data. Surgery rates for lumbar spinal stenosis have risen, yet outcomes remain suboptimal. Postoperative rehabilitation has been suggested as a tool to improve postoperative function but, to date, there is limited evidence to support its use. Methods. CENTRAL (The Cochrane Library), the Cochrane Back Review Group Trials Register, MEDLINE, EMBASE, CINAHL, and PEDro electronic databases were searched. Randomized controlled trials comparing the effectiveness of active rehabilitation with usual care in adults with lumbar spinal stenosis who had undergone primary spinal decompression surgery were included. Two authors independently selected studies, assessed the risk of bias, and extracted the data in line with the recommendations of the Cochrane Back Review Group. Study results were pooled in a meta-analysis when appropriate using functional status as the primary outcome, with secondary outcomes including measures of leg pain, low back pain, and global improvement/general health. The GRADE approach was used to assess the quality of the evidence. Results. Our searches yielded 1726 articles, of which 3 studies (N = 373 participants) were suitable for inclusion in meta-analysis. All included studies were deemed to have low risk of bias; no study had unacceptably high dropout rates. There was moderate evidence suggesting that active rehabilitation was more effective than usual care in improving both short- and long-term functional status after surgery. Similar findings were noted for secondary outcomes, including short-term improvement in low back pain and long-term improvement in both low back pain and leg pain. Conclusion. We obtained moderate-quality evidence indicating that postoperative active rehabilitation after decompression surgery for lumbar spinal stenosis is more effective than usual care. Further work is required particularly with respect to the cost-effectiveness of such interventions. Level of Evidence: 1

Associations Between Clinical Evidence of Inflammation and Synovitis in Symptomatic Knee Osteoarthritis: A Cross-Sectional Substudy.

Painful knee osteoarthritis (KOA) has been associated with joint inflammation. There is, however, little literature correlating signs of localized inflammation with contrast‐enhanced (CE) magnetic resonance imaging (MRI) of synovium. This study examined the relationship between clinical and functional markers of localized knee inflammation and CE MRI–based synovial scores.