Ronald E Delanois

Sinai Hospital, Baltimore, Maryland, United States

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Publications (53)82.9 Total impact

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    ABSTRACT: The effect of acetabular component positioning on the wear rates of metal-on-polyethylene articulations has not been extensively studied. Placement of acetabular cups at abduction angles of more than 40° has been noted as a possible reason for early failure caused by increased wear. We conducted a study to evaluate the effects of different acetabular cup abduction angles on polyethylene wear rate, wear area, contact pressure, and contact area. Our in vitro study used a hip joint simulator and finite element analysis to assess the effects of cup orientation at 4 angles (0°, 40°, 50°, 70°) on wear and contact properties. Polyethylene bearings with 28-mm cobalt-chrome femoral heads were cycled in an environment mimicking in vivo joint fluid to determine the volumetric wear rate after 10 million cycles. Contact pressure and contact area for each cup abduction angle were assessed using finite element analysis. Results were correlated with cup abduction angles to determine if there were any differences among the 4 groups. The inverse relationship between volumetric wear rate and acetabular cup inclination angle demonstrated less wear with steeper cup angles. The largest abduction angle (70°) had the lowest contact area, largest contact pressure, and smallest head coverage. Conversely, the smallest abduction angle (0°) had the most wear and most head coverage. Polyethylene wear after total hip arthroplasty is a major cause of osteolysis and aseptic loosening, which may lead to premature implant failure. Several studies have found that high wear rates for cups oriented at steep angles contributed to their failure. Our data demonstrated that larger cup abduction angles were associated with lower, not higher, wear. However, this potentially "protective" effect is likely counteracted by other complications of steep cup angles, including impingement, instability, and edge loading. These factors may be more relevant in explaining why implants fail at a higher rate if cups are oriented at more than 40° of abduction.
    American journal of orthopedics (Belle Mead, N.J.) 10/2014; 43(10):466-71.
  • Ronald E Delanois, Michael A Mont
    The Journal of Bone and Joint Surgery 11/2013; 95(22):e1791-2. · 3.23 Impact Factor
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    ABSTRACT: Symptomatic osteonecrosis of the joint is a frequent debilitating complication in patients who have been infected with the human immunodeficiency virus (HIV). In earlier reports, outcomes of primary total joint arthroplasty in such patients have been poor due to early failures, high infection rates, and increased complication rates. We report on the clinical and radiographic outcomes of primary total hip arthroplasty (THA) in nonhemophilic, HIV-infected patients as compared with the outcomes in a cohort of osteonecrosis patients who did not have this disease. Thirty-four HIV-infected patients (forty-four hips) who underwent primary THA for the treatment of osteonecrosis during the period of 2001 through 2008 were compared with a control cohort of seventy patients (seventy-eight hips) who also underwent THA for the treatment of osteonecrosis but did not have HIV or other high-risk factors for revision. The patients in the HIV study group (eleven women and twenty-three men) had a mean age of forty-eight years (range, thirty-four to eighty years) and were followed for a mean of seven years (range, four to eleven years). Evaluated outcomes included implant survivorship, Harris hip score, infection rate, activity score, postoperative Short-Form 36 (SF-36) health survey score, and radiographic outcome. Kaplan-Meier survival analysis demonstrated no significant difference in aseptic implant survivorship between the HIV and comparison cohorts at the five-year (100% vs. 98%, respectively) and ten-year (95% vs. 96.5%, respectively) follow-up times. In addition, at the time of final follow-up, the mean postoperative Harris hip scores (85 points in the HIV group vs. 87 points in the comparison group), activity scores (5.7 points in the HIV group vs. 6.1 points in the comparison group), and SF-36 physical (43 points in the HIV group versus 46 points in the comparison group) and mental component summary scores (54 points in the HIV group versus 57 points in the comparison group) were statistically similar between the two cohorts. There were two late infections in the HIV cohort as compared with none in the comparison cohort. Our results demonstrated excellent implant survivorship, clinical and radiographic outcomes, and minimal complications at the time of midterm follow-up in the HIV-infected patient group. We believe that the outcomes associated with primary THA are improving in this patient population as a result of better medical management; however, late infections are potential complications. Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.
    The Journal of Bone and Joint Surgery 10/2013; 95(20):1845-50. · 3.23 Impact Factor
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    ABSTRACT: The purpose of this study was to determine the clinical outcomes of manipulation under anesthesia (MUA) in a cohort who had developed knee stiffness following total knee arthroplasty (TKA). One-hundred and forty-five TKAs in 134 patients who had undergone MUA were compared to the remaining 1973 TKAs in 1671 patients who did not develop this condition. At a mean follow-up of 51months (range, 24 to 85months), the mean gains in flexion in the MUA cohort were 33° (range, 5° to 65°). The final range-of-motion in the MUA cohort was lower than the comparison cohort (114° versus 125°) however, this would meet the required flexion for activities of daily living. There were no differences in the Knee Society objective and functional scores between the two cohorts. It is encouraging that MUA cohort outcomes were comparable to outcomes of patients who did not develop knee stiffness.
    The Journal of arthroplasty 08/2013; · 1.79 Impact Factor
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    ABSTRACT: Dislocation remains the leading cause of revision THA. One approach to decreasing prosthetic dislocation risk has been the use of larger femoral head component sizes. The upper limit of head size in metal-on-polyethylene hip arthroplasty has historically been limited because of concerns about increased wear on thin polyethylene components. It is not known to what degree this concern should apply to more wear-resistant polyethylene components. We therefore determined (1) in vitro wear rates of polyethylene liners of varying thicknesses, (2) whether there were differences in the microscopic wear characteristics as a function of polyethylene thickness, and (3) whether thin polyethylene components resulted in early catastrophic failures. We used a hip wear simulator to compare the wear performance of 12 highly crosslinked polyethylene acetabular inserts. The internal diameter of all components was 36 mm, and there were three samples tested of each thickness (1.9, 3.9, 5.9, or 7.9 mm). Testing was conducted for 2.4 million cycles. Gravimetric mass loss was converted to volumetric loss, which was subsequently converted to theoretical linear penetration rates. Wear rates decreased with increasing polyethylene thickness. Mean ± SD wear rates for the 1.9-, 3.9-, 5.9-, and 7.9-mm groups were 5.0 ± 0.5, 3.2 ± 0.3, 2.5 ± 1.1, and 2.2 ± 1.3 mm(3)/million cycles, respectively (p < 0.016). Calculated penetration rates were 0.015, 0.012, 0.011, and 0.010 mm/million cycles, respectively (p < 0.016). There were no catastrophic failures in any group. Thinner polyethylene components demonstrated higher wear rates, although even the highest wear rate observed in the thinnest polyethylene specimen was lower than that commonly reported for noncrosslinked polyethylene components. While encouraging, these findings should be validated in vivo before clinical recommendations can be made.
    Clinical Orthopaedics and Related Research 07/2013; · 2.79 Impact Factor
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    ABSTRACT: The purpose of this study was to compare the outcomes of cementless primary total hip arthroplasty (THA) in sickle cell patients compared to the remaining cohort of osteonecrosis patients who did not have this disease. Thirty-two sickle cell patients (42 hips) who had a mean age of 37years and mean follow-up of 7.5years (range, 5-11years) were compared to 87 non-sickle cell osteonecrosis patients (102 hips) who had mean age of 43years and mean follow-up of 7years (range, 3-10.5years). Outcomes evaluated included implant survivorship, Harris hip scores, complication rates, radiographic outcomes, and Short Form-(SF-36) health questionnaire. There were no significant differences in aseptic implant survivorship (95 vs. 97%), Harris hip scores (87 vs. 88 points), SF-36 score, or radiographic findings between the two patient cohorts. In light of these findings, we believe that the outcomes of THA improved in sickle cell patients with optimized medical management and the use of cementless prosthetic devices.
    The Journal of arthroplasty 05/2013; · 1.79 Impact Factor
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    ABSTRACT: Nineteen patients (nineteen hips) who had undergone revision total hip arthroplasties using a proximally-coated primary cementless stem were evaluated to determine if a subset of revision arthroplasty patients could be identified where the use of this stem would be appropriate. Of these 19 revisions, 15 were performed for the second stage treatment of infection. The femoral bone deficiency was classified as Paprosky Type I in 6 hips and Type II in 13 hips. At a mean follow-up of 49months, aseptic stem survivorship was 95% with one revision due to aseptic stem failure. The mean Harris hip scores had improved from a mean of 44 points pre-operatively to 89 points post-operatively. Intra-operatively, there was one complication which included a peri-prosthetic fracture distal to the stem which was treated with an allograft strut with cerclage wires. The authors believe that in type I or II femoral defects, the use of this specific cementless stem may be beneficial in the setting of a revision total hip arthroplasty.
    The Journal of arthroplasty 05/2013; · 1.79 Impact Factor
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    ABSTRACT: The purpose of this study was to assess the clinical and radiographic outcomes of total hip arthroplasty (THA) in patients who had osteonecrosis to see if prior hip preserving surgery affected outcomes. Implant survivorship, Harris hip scores, and radiographic outcomes were compared between 87 patients (92 hips) who had undergone prior hip preserving procedures and 105 patients (121 hips) who had only undergone THA. Patients were also sub-stratified into low- and high-risk groups for osteonecrosis. At a mean follow-up of 75 months, there were no significant differences in survivorship, clinical, and radiographic outcomes among the cohorts. Higher revision rates were associated with patients who were in the high-risk group. The authors believe that hip joint preserving procedures may not adversely affect the outcomes of later THA in patients with osteonecrosis.
    The Journal of arthroplasty 05/2013; · 1.79 Impact Factor
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    ABSTRACT: The purpose of this study was to compare the dislocation rates, functional outcomes, and radiographic results between large- and small-diameter femoral head components. A total of 225 patients (248-hips) who received total hip arthroplasties with large-diameter components (36mm or greater) were compared to 501 patients (559-hips) who received smaller diameter components (less than 36mm). Rates of dislocation and revision, Harris hip score, radiographic findings, and complications were compared between the groups. At a mean follow-up of approximately 5years, a significantly higher rate of dislocation was noted in the small-diameter group (10 of 559) compared to the large-diameter group (0 of 248). The overall implant survivorship, mean Harris hip scores, complication rates, and radiographic outcomes were similar for the two groups. The authors believe that large-diameter components significantly reduced the risk of dislocation in susceptible patients, while preserving good to excellent functional outcomes.
    The Journal of arthroplasty 04/2013; · 1.79 Impact Factor
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    ABSTRACT: BACKGROUND: Surgeons are often trying to decreased reinfection rates following two-stage reimplantation arthroplasty, which range from 3.2% to 13% because multiple staged revision procedures for infection can be costly and have high morbidity. We therefore asked: (1) Did the use of postoperative oral antibiotics reduce reinfection rates after 2-staged revision of THA? And (2) how did this compare with the infection rate after aseptic revision procedures? METHODS: We identified all patients who underwent two-stage revision THA for a periprosthetic deep hip infection and found 66 patients (67 hips) who had a minimum 24 months' followup. Twenty-two of the 66 procedures (33%) were followed by a minimum of 14 days of postoperative oral antibiotics (mean, 36 days; range, 14 days to lifelong), while 44 were prescribed only immediate parenteral postoperative antibiotic therapy (mean, 1.3 days; range, 1--3 days). We then identified 407 patients (410 hips) who underwent aseptic revision hip arthroplasty and evaluated the infection rate in these patients for comparison; these patients were treated with 24 hours of postoperative parenteral antibiotics. The authors used previously described creteria to establish the presence of infection. RESULTS: There were no reinfections in the group receiving oral postoperative antibiotics compared to six reinfections (13.6%) in the 44 patients not receiving oral antibiotics. We observed infection in 2 of the 410 hips (0.5%) revised for aseptic reasons. CONCLUSIONS: We believe that our findings warrant further investigation for using postoperative oral antibiotics after reimplantation for periprosthetic infection in an effort to decrease the likelihood and risks associated with additional revision arthroplasty procedures.
    BMC Musculoskeletal Disorders 04/2013; 14(1):123. · 1.88 Impact Factor
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    ABSTRACT: Cementless acetabular cups for primary total hip arthroplasty have had excellent results, with failure rates typically less than 5% at up to 10-year follow-up. Tritanium is a 3-dimensional metal interface that has been used for porous biological fixation. The purpose of this study was to review the clinical and radiographic results of the use of Tritanium cups (Stryker Orthopaedics, Mahwah, New Jersey) for primary total hip arthroplasty. Two hundred eighty-eight total hip arthroplasties performed using a porous titanium acetabular cup in 252 patients between 2008 and 2010 were reviewed. One hundred thirty-three men and 119 women with a mean age of 58 years (range, 18-88 years) were included. Mean follow-up was 36 months (range, 24-56 months). Outcomes evaluated were implant survivorship, Harris Hip Score, complications, and radiographic outcomes. At final follow-up, no cup failures had occurred. Mean Harris Hip Score improved from 53 points (range, 33-82 points) preoperatively to 91 points (range, 64-100 points) postoperatively. One complication occurred; a 64-year-old woman with recurrent postoperative effusions underwent hip exploration and required abductor mechanism repair. On radiologic evaluation, no signs existed of progressive radiolucencies or changes in cup position. The survivorship of the Tritanium cup and the low complication rate is comparable with previous studies using other porous-metal prostheses. Longer follow-up study is needed and assessment of the results of using this implant in the revision setting is important.
    Orthopedics 04/2013; 36(4):e390-e394. · 1.05 Impact Factor
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    ABSTRACT: The purpose of this study was to compare the clinical and radiographic outcomes of primary total knee arthroplasty (TKA) in obese and nonobese patients. A total of 210 knees in 174 obese patients who had a mean body mass index (BMI) of 34 kg/m2 (range, 30 to 39.9 kg/m2) and who had undergone a primary TKA between 2006 and 2010 were reviewed. There were 115 women and 59 men who had a mean age of 62 years (range, 36 to 84 years) and a mean follow-up of 57 months (range, 24 to 82 months). These patients were compared with a group of nonobese patients who had a BMI of less than 30 kg/m2 (range, 19 to 29.9 kg/m2). The evaluated outcomes included implant survivorship, Knee Society objective and functional scores, complication rates, radiographic outcomes, University of California Los Angeles (UCLA) activity score, and the length of hospital stay between obese and nonobese patients. There were no significant differences in the overall septic and aseptic implant survivorship (98.8 vs. 98.6%) and mean postoperative Knee Society objective and function scores (90 and 87 points vs. 91 and 89 points), respectively. Obese patients had significantly higher complication rates (10.5 vs. 3.8%) and had achieved a significantly lower mean postoperative UCLA activity score (5 vs. 6 points). However, there were no differences in the length of hospital stay for the two cohorts. Although the authors encourage all patients to lose weight as much as possible prior to their TKA, it is encouraging that obese patients had achieved excellent clinical outcomes at early to mid-term follow-up.
    The journal of knee surgery 03/2013;
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    ABSTRACT: This report includes a series of eight cases in which a dual-mobility prosthesis was utilized for difficult acetabular reconstructive hip arthroplasty cases. Most of the patients described had multiple reasons for hip instability (including prior multiple surgeries, abductor muscle insufficiency, prior infection). All patients were successfully managed with this device and this report includes a brief description of its use compared with other surgical reconstruction methods for instability.
    Surgical technology international 12/2012; XXI:234-240.
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    ABSTRACT: The purpose of this study was to compare the clinical outcomes of total knee arthroplasty in patients who reported a history of tobacco use with those who were nonsmokers. Between 2006 and 2009, there were 131 total knee arthroplasties performed in patients who were smokers and 490 in patients who did not smoke. At a mean follow-up of 47 months (range, 24-79 months), the patients who were smokers had a statistically decreased overall survivorship of 90% (13 revisions) compared with 99% (5 revisions) in the nonsmokers. Surgical complication rates were not significantly different between the 2 groups; however, there was a significant difference in medical complications. Total knee arthroplasty in smokers has a higher risk of negative clinical outcomes compared with nonsmokers.
    The Journal of arthroplasty 05/2012; 27(9):1690-1695.e1. · 1.79 Impact Factor
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    ABSTRACT: The diagnosis of periprosthetic hip infections is often challenging. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level blood laboratory tests are commonly used to aid in the diagnosis. We studied the sensitivity, specificity, and false-negative rates of ESR and CRP level in a prospective group of patients who underwent revision total hip arthroplasty between 2000 and 2008. Seventy-seven patients with periprosthetic hip infections and ESR and CRP data were identified. Chi-square analysis was performed to determine the significance of false-negatives, compared with sex, body mass index, primary diagnosis, infection type, and immunity status. ESR had 89% sensitivity and 69% specificity. CRP level had 93% sensitivity and 40% specificity. The false-negative rate was 10.8% for ESR and 7% for CRP level. The false-negative rate for ESR and CRP level combined (with either result positive) was 3%. All false-negatives in the combined group were immunocompromised. Chi-square analysis did not find a significant correlation between false-negatives and any other variables. ESR and CRP level are useful in the diagnosis of periprosthetic hip infections. Ordering these tests concurrently reduces the chance of false-negative results.
    American journal of orthopedics (Belle Mead, N.J.) 04/2012; 41(4):160-5.
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    ABSTRACT: Total knee arthroplasty (TKA) is a procedure with excellent clinical results in older patients with a primary diagnosis of osteoarthritis. Many younger patients undergo unicompartmental or high tibial osteotomy rather than TKA, but are not always good candidates for these joint-preserving procedures. The purpose of this study was to review the outcomes of patients 40 years of age and under who underwent TKA. We identified 33 patients (38 knees) who were 40 years of age or less at the time of surgery. These patients had a mean age of 36 years (range, 23 to 40 years), and were followed for a mean of 49 months (range, 16 to 101 months). The survival rate in the study cohort was 97%. For the young patient who is not a candidate for other types of joint preserving procedures, in the senior authors' experience total knee arthroplasties have performed well.
    The journal of knee surgery 03/2012; 25(1):65-9.
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    ABSTRACT: We conducted this study to review the clinical and radiographic outcomes of patients 80 years of age or older who underwent total knee arthroplasty (TKA). We identified clinical results in 60 patients (66 knees) who had a mean age of 84 years (range, 80 to 95 years) and who underwent TKA. These were compared with a non-age-matched group of 63 patients (66 knees) who had a mean age of 69 years (range, 60 to 79 years). Four patients were lost to follow-up. After a mean 43-month follow-up (range, 24 to 117 months), Knee Society pain and function scores for the study group improved from 53 points (range, 25 to 70 points) and 53 points (range, 40 to 70 points), respectively, to 94 points (range, 75 to 100 points) and 87 points (range, 45 to 100 points). There were no implant failures, 2 surgical complications, and 13 medical complications. In the matching group, there were four surgical complications (two required revision) and two medical complications. There were no radiographic failures or progressive radiolucencies. Although the incidence of medical complications in the perioperative period may be higher, TKA is a safe and effective treatment for refractory joint pain in patients over 80 years of age.
    The journal of knee surgery 12/2011; 24(4):279-83.
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    ABSTRACT: Surgical site infections following elective knee arthroplasties occur most commonly as a result of colonisation by the patient's native skin flora. The purpose of this study was to evaluate the incidence of deep surgical site infections in knee arthroplasty patients who used an advance cutaneous disinfection protocol and who were compared to patients who had peri-operative preparation only. All adult reconstruction surgeons at a single institution were approached to voluntarily provide patients with chlorhexidine gluconate-impregnated cloths and a printed sheet instructing their use the night before and morning of surgery. Records for all knee arthroplasties performed between January 2007 and December 2008 were reviewed to determine the incidence of deep incisional and periprosthetic surgical site infections. Overall, the advance pre-operative protocol was used in 136 of 912 total knee arthroplasties (15%). A lower incidence of surgical site infection was found in patients who used the advance cutaneous preparation protocol as compared to patients who used the in-hospital protocol alone. These findings were maintained when patients were stratified by surgical infection risk category. No surgical site infections occurred in the 136 patients who completed the protocol as compared to 21 infections in 711 procedures (3.0%) performed in patients who did not. Patient-directed skin disinfection using chlorhexidine gluconate-impregnated cloths the evening before, and the morning of, elective knee arthroplasty appeared to effectively reduce the incidence of surgical site infection when compared to patients who underwent in-hospital skin preparation only.
    International Orthopaedics 07/2011; 35(7):1001-6. · 2.32 Impact Factor
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    ABSTRACT: One section of the Orthopaedic In-Training Examination (OITE) assesses knowledge about hip reconstruction. In the investigation reported here, we examined OITE hip reconstruction questions and sought to identify which literature can be recommended as study aids for this section of the test. All hip reconstruction questions on the OITE from 2002 to 2006 were characterized according to diagnosis and treatment. Journals cited most often in this section were identified from the OITE key. This content domain was compared with the literature in terms of overall proportion of questions/articles related to hip reconstruction and in terms of diagnoses and treatments. Of the 1375 OITE questions asked over the 5 years, 79 were related to hip reconstruction. More than half of these hip reconstruction questions were related to primary total hip arthroplasty, with complications being the diagnosis tested most often. The results of this study suggest that residents may benefit from using general orthopedic journals when preparing for the OITE hip reconstruction section. When preparing an educational program, however, one should be aware that clinical journals may not reflect the OITE in terms of proportion of basic science and biomechanics articles.
    American journal of orthopedics (Belle Mead, N.J.) 05/2011; 40(5):E88-91.
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    ABSTRACT: The Orthopaedic In-Training Examination (OITE) provides a standardized measure to assess the knowledge of orthopaedic residents regarding knee reconstruction surgery. However, there currently are limited resources for residents who are preparing for the knee reconstruction questions on the OITE. The present study assessed the character of the knee reconstruction questions tested and which literature resources may be recommended for residents preparing for this examination. All knee reconstruction-related questions found during a 5-year period (2002 to 2006) on the OITE were characterized by the diagnosis and treatment discussed. The most frequently referenced journals were identified from the OITE exam key. The character of the OITE questions was compared to the literature in terms of overall proportion of articles and questions that were related to knee reconstruction, as well as to categories of diagnosis and treatment modality. There were 59 out of 1375 questions (4%) on the OITE over the 5 years that were related to knee reconstruction. Over half of the questions (54%) were related to primary total knee arthroplasty, with osteoarthritis being the most frequently tested diagnosis (30%). The top three referenced orthopaedic journals were The Journal of Bone and Joint Surgery-American, Clinical Orthopaedics and Related Research, and The Journal of Arthroplasty. Compared to the OITE, these journals covered higher percentages of overall knee reconstruction-related questions (18% versus 4%). In addition, the journal literature had a greater focus on treatment modalities (65% versus 41%) and less emphasis on biomechanics, materials, and basic science (18% versus 34%) than the OITE, respectively. The two most frequently cited textbooks represented approximately 78% of the total number of provided textbook references: Orthopaedic Knowledge Update (39%) and Instructional Course Lectures (39%). The results of this study suggest that residents may benefit from using general orthopaedic journals such as The Journal of Bone and Joint Surgery-American in preparation for the OITE. However, residents and residency directors who are preparing their educational programs should be aware that clinical journals may not refect the OITE in terms of the proportion of basic science and biomechanics articles and additional study resources may be necessary.
    Bulletin of the NYU hospital for joint diseases 01/2011; 69(2):168-72.

Publication Stats

502 Citations
82.90 Total Impact Points

Institutions

  • 2008–2013
    • Sinai Hospital
      Baltimore, Maryland, United States
  • 2008–2010
    • University of South Florida
      • Department of Orthopaedics and Sports Medicine
      Tampa, FL, United States
  • 2009
    • Howard University Hospital
      Washington, Washington, D.C., United States
  • 2002
    • Naval Medical Center Portsmouth
      Portsmouth, Virginia, United States