Hypersensitivity to metals in metal-on-metal hip arthroplasty: a prospective study of one hundred and thirty five lymphocyte transformation tests.

BACKGROUND: Metal allergy remains a controversial topic in the orthopaedic community. It is not known if or to what degree metal sensitivity contributes to inflammatory soft tissue failures, unexplained residual pain, or clinical complications after total joint replacement with metal prostheses. METHODS: We investigated the efficacy of the lymphocyte transformation test (LTT) in predicting adverse outcomes in patients after receiving a metal joint replacement. Our study cohort consists of 135 metal-on-metal hip resurfacing arthroplasty cases performed between 2013 and 2015. All study patients had an LTT preoperatively. We retrospectively analyzed clinical outcomes and failures for our cohort. RESULTS: There was no difference in LTT reactivity between men and women. Of the 135 patients tested, 46 (34.1% of cohort) tested positive to at least one of the materials comprising their implant, and 78 patients (57.8%) had at least one reactive score to any component of the LTT. After a minimum follow-up of two years, we did not observe an allergic response to the implant in any patients. There were no failures requiring revision. We observed a 2.2% rate of moderate residual pain; no patients with residual pain tested positive for metal sensitivity. When patients with moderate-high LTT reactivity (30.4% of cohort) were compared to the remainder of the study group, there was no difference in HHS or UCLA activity score. There was no correlation between blood metal ion levels and LTT reactivity. CONCLUSION: We were unable to prove any predictive value of the LTT. We failed to identify hypersensitivity to metals in patients with metal-on-metal hip resurfacing arthroplasty.

Femoral Fixation Methods in Hip Resurfacing Arthroplasty: An 11-Year Retrospective Comparison of 4013 Cases.

BACKGROUND: The optimal femoral fixation method remains unclear. To evaluate the role of femoral fixation techniques in hip resurfacing, we present a comparison of 2 consecutive groups: group 1 (739 hips) with cemented femoral components; group 2 (3274 hips) with uncemented femoral components. METHODS: We retrospectively analyzed our clinical database to compare failures, reoperations, complications, clinical results, and radiographic measurements. Groups were consecutive, so cemented cases had longer follow-up. However, all patients from both groups were at least 2 years out from surgery. Two-year clinical and radiographic data were compared. Longer-term comparison data as well as Kaplan-Meier implant survivorship curves specifically focusing on femoral failure modes were analyzed. RESULTS: Kaplan-Meier 10-year implant survivorship using nontraumatic femoral failure as an end point was 98.9% for the cemented and 100% for the uncemented femoral component. The uncemented, group 2 cases showed a significantly lower raw failure rate (1.1% vs 4.6%), 2-year failure rate (0.8% vs 2.8%), 2-year femoral failure rate (0.4% vs 0.9%), and a lower combined rate of femoral complications and failures (0.6% vs 1.8%). In cases that did not fail, patient mean clinical scores, pain scores, and combined range of motion were all significantly better for group 2. CONCLUSION: We have demonstrated that in the fully porous-coated ReCap device, uncemented femoral fixation is superior to cemented fixation at 11 years follow-up (0.0% vs 1.1% late femoral loosening) in this single-surgeon cohort. Early femoral fractures also reduced from 0.8% to 0.3%, but this may be partially or completely due to a new bone density management program. This study demonstrates better femoral implant survivorship for the uncemented device compared to the cemented femoral resurfacing component for this implant design.

Interventions for Improving Hip Resurfacing Outcomes in Women: A High-Volume, Retrospective Study.

BACKGROUND: Women seeking surgical intervention for their hip disorders will often find total hip arthroplasty (THA) presented as their only option. THA, when compared with hip resurfacing arthroplasty, removes substantially more bone-stock, limits range-of-motion, exhibits increased dislocation risk, and presents greater overall 10-year mortality rate. Despite these risks, most surgeons continue to select against women for hip resurfacing because registries notoriously report inferior survivorship when compared with men and THA. METHODS: We investigated the reasons for why resurfacing arthroplasty devices survive poorly in women to develop interventions which might improve hip resurfacing outcomes in women. Using these findings, we developed a series of surgical interventions to treat the underlying issues. Herein, we compare 2 study groups: women who received hip resurfacings before (group 1) and after (group 2) these interventions. RESULTS: Eight-year implant survivorship substantially improved from 89.6% for group 1 to 97.7% for group 2. Adverse wear-related failure, femoral component loosening, and acetabular component loosening were all significantly reduced in group 2, which we attribute to the implementation of our relative acetabular inclination limit guidelines, use of uncemented femoral fixation, and selection of the Tri-Spike acetabular component for supplemental fixation, respectively. Kaplan-Meier implant survivorship curves, grouped into 2-year time intervals, show that the disparity in failure rates between men and women is diminishing. CONCLUSION: When experienced surgeons use refined and proper surgical technique, women show promise as excellent candidates for hip resurfacing as an alternative treatment for their debilitating hip conditions.

Comparison of Cemented and Bone Ingrowth Fixation Methods in Hip Resurfacing for Osteonecrosis.

BACKGROUND: The optimal surgical treatment for osteonecrosis of the femoral head has yet to be elucidated. To evaluate the role of femoral fixation techniques in hip resurfacing, we present a comparison of the results for 2 consecutive groups: group 1 (75 hips) received hybrid hip resurfacing implants with a cemented femoral component; group 2 (103 hips) received uncemented femoral components. Both groups received uncemented acetabular components. METHODS: We retrospectively analyzed our clinical database to compare failures, reoperations, complications, clinical results, metal ion test results, and X-ray measurements. Using consecutive groups caused time interval bias, so we required all group 2 patients to be at least 2 years out from surgery; we compared results from 2 years and final follow-up. RESULTS: Patient groups matched similarly in age, body mass index, and percent female. Despite similar demographics, the uncemented, group 2 cases showed a lower raw failure rate (0% vs 16%; P < .0001), a lower 2-year failure rate (0% vs 7%; P = .04), and a superior 8-year implant survivorship (100% vs 91%; log-rank P = .0028; Wilcoxon P = .0026). In cases that did not fail, patient clinical (P = .05), activity (P = .02), and pain scores (P = .03), as well as acetabular component position (P < .0001), all improved in group 2, suggesting advancements in surgical management. There were no cases of adverse wear-related failure in either group. CONCLUSION: This study demonstrates a superior outcome for cases of osteonecrosis with uncemented hip resurfacings compared to cases employing hybrid devices.

Reducing the failure rate of hip resurfacing in dysplasia patients: a retrospective analysis of 363 cases.

BACKGROUND: Arthritis secondary to developmental hip dysplasia often mandates implant surgery at a relatively young age. Hip resurfacing arthroplasty (HRA), compared with standard stemmed total hip arthroplasty (THA), affords a more active lifestyle including extreme-motion activities but stimulates concerns pertaining to implant failure. METHODS: We addressed the primary modes of failure through a series of interventions, including a new guideline for achieving proper implant alignment through intraoperative x-rays. We then compared two sequential cohorts in a single-surgeon practice: patients with developmental dysplasia who underwent HRA before (Group 1; 121 hips in 105 patients) and after (Group 2; 242 hips in 210 patients) June 2008, at which time the four interventions were all in place. RESULTS: Implants in Group 2 failed less frequently within two years (0.8 % vs. 6.6 %, p = 0.002) and were more likely to have projected seven-year Kaplan-Meier survivorship (99 % vs. 89 %, p < 0.0001 by log-rank test). Patients in Group 2 were more likely to have normal metal ion levels (77 % vs. 56 %, p = 0.0008) and optimum metal ion levels (99 % vs. 86 %, p = 0.0008). Patients in Group 2 also benefited from a 19-min decrease in mean operation time, a 45 % decrease in mean estimated blood loss, and a 0.9-day decrease in mean hospital stay (p < 0.0001 in each instance). CONCLUSIONS: We believe the interventions reported here, combined with sufficient surgeon experience and properly designed implants, afford patients with mild developmental dysplasia a more active lifestyle with favorable implant survival.

Current status of modern fully porous coated metal-on-metal hip resurfacing arthroplasty.

Between March 2007 and July 2010, 1000 consecutive fully porous coated hip resurfacing arthroplasties (HRA) were performed by a single surgeon in 871 patients. The average length of follow-up was 3 ± 1 years. Three cases (0.3%) in three patients showed adverse wear related failures. Another 17 (1.7%) failures were identified at the time of this study. Using any failure of any component as the endpoint, the survivorship rate was 98.8% at two years and 97.4% at five years. Excluding the failed cases, all components were radiographically stable; there was only one partial femoral radiolucency seen. The clinical and radiological outcomes of this fully porous coated hip resurfacing were comparable to, if not better than, those reported by others using hybrid fixation methods at five years post-operatively.

Outcomes after revision of metal-on-metal hip resurfacing arthroplasty.

We report the results of 58 hip resurfacing arthroplasties (HRA) revised by a single surgeon with an average of 5.2±2.6 years follow-up. The four most common causes for revision were acetabular component loosening, femoral neck fracture, femoral component loosening, and adverse wear related failure (AWRF). In 95% of cases (55/58), the revision bearing was a large metal-on-metal type including all seven AWRF cases; three cases were revised to ceramic-on-polyethylene. There were two repeat revisions due to acetabular component loosening. Revision of AWRF had an excellent outcome using limited debridement and a stable large metal bearing placed in the correct position. The only problematic group was the one revised for acetabular loosening in which 2/16 (6%) required repeat revision for failure of acetabular fixation.

Feasibility of proactive medical device surveillance: the VA Clinical Assessment Reporting and Tracking (CART) program.

BACKGROUND: Timely identification and reporting of medical device problems is critical to postmarket device surveillance programs to maximize patient safety. Cardiac catheterization laboratories are high-device utilization areas well suited for device surveillance. OBJECTIVE: To demonstrate the feasibility of the national VA Clinical Assessment, Reporting, and Tracking (CART) system, embedded in the electronic health record of all 76 VA cardiac catheterization laboratories, to document unexpected problems with medical devices at the point of care. METHODS: We evaluated 260,258 consecutive cardiac catheterization and/or percutaneous coronary intervention procedures on 175,098 Veterans between August 2006 and February 2012. Unexpected device problems (UDPs) encountered for any equipment used during a procedure were entered by clinicians at the point of care as part of regular care documentation. All UDPs were reviewed in collaboration with the FDA to ascertain the likelihood of a device defect (eg, in manufacture or design) and/or contributing to a procedural complication (level I, unlikely; level II, possibly; level III, likely). RESULTS: Of the 260,258 procedure reports, 974 (0.37%) UDP's were reported by 71 (92.2%) of the 76 VA hospitals. After triage, 739 (75.9%) were deemed level I, 196 (20.1%) level II, and 39 (4.0%) level III. Of the 39 level III reports, 12 (30.7%) are in the submission phase as a FDA MedWatch report. The number of monthly UDP reports increased significantly from 2006 to 2012 (P<0.001). CONCLUSIONS: Leveraging a clinical application embedded in the electronic health record and in collaboration with FDA, a proactive national cardiac device surveillance program has been successfully implemented in the VA.

Total knee arthroplasty with fully porous-coated stems for the treatment of large bone defects.

Between February1999 and April 2006, 25 patients (28 knees) underwent a TKA by a single surgeon. At an average final follow-up of 7±2years (range, 3-10years), 34 (100%) of 34 fully porous stems had achieved bone ingrowth. However, one case (3%) had a component loosening due to the de-bonding of sheets of beads from the stem. The remaining cases remained well fixed. Three well-fixed stems in 2 patients failed from deep infection. There was one reoperation required for a femoral periprosthetic fracture. Our 10-year experience shows that fully porous-coated stems reliably achieve durable fixation in complex primary and revision TKA allowing the surgeon to bypass large bone defects and gain fixation in diaphyseal bone.

A safe zone for acetabular component position in metal-on-metal hip resurfacing arthroplasty: winner of the 2012 HAP PAUL award.

A safe zone for acetabular component positioning in hip resurfacing (RAIL: Relative Acetabular Inclination Limit) was calculated based on implant size and acetabular inclination angle (AIA). For AIA below the RAIL, there were no adverse wear failures or dislocations, and only 1% of cases with ion levels above 10 µg/L. Other than high inclination angle and small bearing size, female gender was the only other factor that correlated with high ion levels in the multivariate analysis. Seven hundred sixty-one hip resurfacing cases are included in this study. The UCLA activity score, femoral shaft angle, body mass index, weight, American Society of Anesthesiologists score, combined range of motion, diagnosis, age, gender, implant brand, AIA, bearing size, and duration of implantation were analyzed to determine the potential risk factors for elevated metal ion levels. These findings apply to sub hemispheric metal-on-metal bearings with similar coverage arcs as the Biomet and Corin hip resurfacing brands. Additional problems may occur when these bearings are connected with trunions on stems for total hip arthroplasty.

Long-term clinical outcomes of the Biomet M2a-38: a retrospective review of 335 total hip arthroplasty cases.

BACKGROUND: At the turn of the century, over one-third of total hip arthroplasties comprised metal-on-metal bearings. As this patient population and their implants age, it is crucial to understand associated late failure modes and expected long-term functional outcomes. We report the long-term results of a large metal-on-metal uncemented total hip arthroplasty system with unique design characteristics compared to others that have been reported with high failure rates. METHODS: We retrospectively analyze our prospective clinical database to determine overall implant survivorship and functional outcomes. Further, we compare these results to the clinical outcomes reported in orthopedic registries and in other published studies with similar metal-on-metal total hip arthroplasty cohorts. RESULTS: Implant survivorship at 10 years was 99.1% and continued to 97.6% survivorship at 20 years. Implant survivorship at 20 years did not vary significantly between sexes (Male: 98.3%, Female: 97.2%; log-rank p-value = 0.46). Mean whole blood cobalt levels were 2.6 µg/L in unilateral cases, 5.3 µg/L in bilateral patients, and 3.4 µg/L for the combined cohort. Average blood chromium levels were 1.4 µg/L in unilateral patients, 2.9 µg/L in bilateral patients, and 1.8 µg/L for group combined. We observed a 0.9% rate of failure due trunnion corrosion at a mean of 13.1 years postoperatively (10.6-15.6 years) but had no bearing wear failures. CONCLUSIONS: Our 20-year implant survivorship of 97.6% with the M2a-38 bearing surpassed registry benchmarks for THA. This large-bearing (38 mm), full hemisphere coverage metal-on-metal system had no bearing wear failures, one failure of instability, one failure of fixation, and three trunnion failures, perhaps suggesting an optimum balance between stability of the joint and the trunnion.

Hip resurfacing with the Biomet Hybrid ReCap-Magnum system: 7-year results.

The purpose of this study was to report our clinical outcome of a large series of metal-on-metal hip resurfacing arthroplasty (HRA) using the hybrid Biomet ReCap-Magnum system. This is a single-designer surgeon series with an average of 5 ± 1 years. Seven hundred forty consecutive hybrid HRAs were performed in 653 patients. Kaplan-Meier survivorship with any revision as an end point was 96.4% at 7 years. Twenty-five (3.4%) cases were revised: 8 due to acetabular component loosening, 6 due to femoral neck facture, 4 due to failure of femoral component fixation, 2 due to deep infection, 2 due to adverse wear, 1 due to psoas tendonitis, 1 due to recurrent dislocation, and 1 due to unexplained pain. Biomet ReCap and Magnum HRA components with hybrid fixation methods showed excellent survivorship for a minimally selected young patient cohort at 7 years.

Clinical outcome of the metal-on-metal hybrid Corin Cormet 2000 hip resurfacing system: an up to 11-year follow-up study.

This report extends the follow-up for the largest center of the first multicenter US Food and Drug Administration investigational device exemption study on metal-on-metal hip resurfacing arthroplasty up to 11 years. A single surgeon performed 373 hip resurfacing arthroplasties using the hybrid Corin Cormet 2000 system. The Kaplan-Meier survivorship at 11 years was 93% when revision for any reason was used as an end point and 91% if radiographic failures were included. The clinical results demonstrate an acceptable failure rate with use of this system. Loosening of the cemented femoral components was the most common source of failure and occurred at all follow-up intervals. A learning curve that persisted for at least 200 cases was confirmed. All femoral neck fractures occurred before 6 months postoperatively.

Prevalence of dysplasia as the source of worse outcome in young female patients after hip resurfacing arthroplasty.

PURPOSE: Smaller femoral component size has been implicated as underlying the risk factor that explains the higher failure rate in women who have a hip resurfacing arthroplasty (HRA). We suspect that the diagnosis of dysplasia may be a more important causative risk factor than either small component size or female gender. METHODS: From January 2002 to July 2008, a total of 1,216 HRA cases, 1,082 with the primary diagnosis of osteoarthritis and 134 with dysplasia, were included in this study. Of them, 867 cases were performed in men and 349 performed in women. The average femoral component size was 51 ± 4 mm. Cox proportional hazard regression models were used to evaluate the significance of each variable and determine the causative risk factors for failure. RESULTS: The average follow-up was 5 ± 2 years. Thirty-nine cases failed (20 in men vs. 19 in women). The failure rate for the whole group was 3.2% (2.3% in men vs. 5.4% in women; P = 0.01). Dysplasia (P = 0.05) was identified as the only significant risk factor in our multi-variable analysis; small femoral component size (P = 0.09) and gender (P = 0.76) were not significant risk factors. Women with the primary diagnosis of dysplasia had a survivorship rate of only 75% compared to 93% for the entire group at eight-year follow-up post-operatively. CONCLUSIONS: In our study, we found that the high incidence of dysplasia in young women undergoing HRA was the reason that women had a higher failure rate after HRA. In dysplasia, 70% of failures were due to acetabular problems, of which 50% were due to failure of fixation and 20% due to adverse wear.

Comparative study between patients with osteonecrosis and osteoarthritis after hip resurfacing arthroplasty.

The purpose of this study was to compare the clinical outcomes of osteonecrosis (ON) and osteoarthritis (OA) patients after metal-on-metal hip resurfacing arthroplasty (HRA). We retrospectively reviewed our database and identified a study group of 122 HRA cases with the primary diagnosis of ON. A control group of 122 OA cases were randomly selected by a computer program to match the surgical date, gender and the femoral component type and size with the study group. We compared the results between these two groups and also compared the clinical outcome between cemented and uncemented HRA in ON cases. Overall survivorship, using any revision as an endpoint, was 88% for ON, compared to 100% for OA at ten years. There were no femoral failures in 47 uncemented femoral cases. Our study suggests that HRA may not be suitable for everyone, such as ON patients.

Intraoperative radiographs for placing acetabular components in hip resurfacing arthroplasty.

BACKGROUND: Various clinical and biomechanical studies suggest certain acetabular positions may be associated with higher wear and failure rates in modern metal-on-metal hip resurfacing arthroplasties. However, there are no widely available, reliable, and cost-effective surgical techniques that ensure surgeons are able to place an acetabular component within the safe range of inclination angles after hip resurfacing surgeries. QUESTIONS/PURPOSES: We investigated the accuracy of intraoperative radiographs to determine the acetabular inclination angle in resurfacing arthroplasty procedures. PATIENTS AND METHODS: The study group included the first 100 resurfacing arthroplasties performed after we started routinely checking the intraoperative acetabular inclination angles. The acetabular component was repositioned if the intraoperative acetabular inclination angle was out of the target range of 30° to 50°. The control group included the previous 100 resurfacing arthroplasties performed without the benefit of intraoperative radiographs. A posterior minimally invasive surgical approach was used in both groups. Demographics and diagnoses were similar in both groups. RESULTS: The average (± SD) difference between the intraoperative and 6-week radiographs was 2.7° ± 2.5°. The acetabular inclination angles at 6-week followup were within the targeted range more frequently in the study group than in the control group (outliers: 4% versus 29%). CONCLUSIONS: These data suggest a single intraoperative radiograph is a quick, reliable, and cost-effective method for ensuring the acetabular inclination angle is within the targeted range.

Hip resurfacing in patients who have osteonecrosis and are 25 years or under.

BACKGROUND: Young patients with osteonecrosis (ON) treated with THA often have suboptimal function and radiographic failure with eventual revision. Resurfacing may be an option because of potentially increased functionality and decreased radiographic failure, although neither has been confirmed in the literature. QUESTIONS/PURPOSES: We therefore compared the clinical scores and radiographic failures of resurfacing patients 25 years or younger with osteonecrosis with those for patients with ON treated with THA. METHODS: We identified 17 patients (20 resurfaced hips) who were 25 years or younger and treated by resurfacing for ON. Mean followup was 62 months (range, 32-103 months). This group was matched by gender, age, BMI, and followup to 16 patients (20 hips) treated with THA with a mean 61 month followup (range, 34-88 months). Additionally, the group was compared to 78 patients (87 hips) with ON over age 25 who underwent resurfacing during the same time with a mean followup of 61 months (range, 27-112 months). RESULTS: The mean Harris score improved from 48 points preoperatively to 93 points with a 100% 7.5 year survivorship in the young resurfacing group. In the THA cohort, the mean score improved from 44 points preoperatively to 94 points postoperatively, with a 93.3% 7.5 year survivorship; similar to the results for all resurfacing patients. Radiographs did not reveal malalignment or progressive radiolucencies in any cohort. CONCLUSION: At approximately 5 year followup, young resurfacing patients were similar to other resurfacing patients and standard THA patients regarding clinical ratings and radiographic failures.

Is resurfacing arthroplasty appropriate for posttraumatic osteoarthritis?

BACKGROUND: High survival has been reported for resurfacing arthroplasty in patients with femoral deformities. Also, hardware removal may not always be necessary with resurfacing arthroplasty and may eliminate some of the difficulties performing total hip arthroplasty (THA) in patients with posttraumatic osteoarthritis. QUESTIONS/PURPOSES: We therefore asked: (1) are survivorship higher in patients who underwent resurfacing arthroplasty compared with patients with nontraumatic osteoarthritis; and (2) are those higher compared with all patients who have resurfacing? METHODS: We identified 29 patients (29 hips) who had hip resurfacing for posttraumatic arthritis. These were compared with a matched cohort who had hip resurfacings for nontraumatic osteoarthritis and to all patients who underwent hip resurfacing for osteoarthritis during this time. The mean age was 47 years and mean body mass index was 27 kg/m(2). Survivorship and Harris hip scores were compared. Radiographs were evaluated for signs of radiolucencies, penciling, or osteolysis. The mean followup was 39 months (range, 24-99 months). RESULTS: The 5-year survivorship was 90% in the posttraumatic group, 93% in the matched osteoarthritis group, and 97% in the entire osteoarthritis cohort. The mean Harris hip score for the posttraumatic group at last followup was 90 points. Other than the patients who underwent revision, we observed no radiographic radiolucencies or loosening in any of the groups. CONCLUSIONS: The survival of resurfacing arthroplasty appears comparable to THA in posttraumatic osteoarthritis and for resurfacing in patients with osteoarthritis. Therefore, resurfacing may present an alternative treatment to THA in these patients.

Evaluation of an automated safety surveillance system using risk adjusted sequential probability ratio testing.

BACKGROUND: Automated adverse outcome surveillance tools and methods have potential utility in quality improvement and medical product surveillance activities. Their use for assessing hospital performance on the basis of patient outcomes has received little attention. We compared risk-adjusted sequential probability ratio testing (RA-SPRT) implemented in an automated tool to Massachusetts public reports of 30-day mortality after isolated coronary artery bypass graft surgery. METHODS: A total of 23,020 isolated adult coronary artery bypass surgery admissions performed in Massachusetts hospitals between January 1, 2002 and September 30, 2007 were retrospectively re-evaluated. The RA-SPRT method was implemented within an automated surveillance tool to identify hospital outliers in yearly increments. We used an overall type I error rate of 0.05, an overall type II error rate of 0.10, and a threshold that signaled if the odds of dying 30-days after surgery was at least twice than expected. Annual hospital outlier status, based on the state-reported classification, was considered the gold standard. An event was defined as at least one occurrence of a higher-than-expected hospital mortality rate during a given year. RESULTS: We examined a total of 83 hospital-year observations. The RA-SPRT method alerted 6 events among three hospitals for 30-day mortality compared with 5 events among two hospitals using the state public reports, yielding a sensitivity of 100% (5/5) and specificity of 98.8% (79/80). CONCLUSIONS: The automated RA-SPRT method performed well, detecting all of the true institutional outliers with a small false positive alerting rate. Such a system could provide confidential automated notification to local institutions in advance of public reporting providing opportunities for earlier quality improvement interventions.