Award-Winning Posters from ICJR East

    The ICJR East meeting in New York featured posters on primary and revision hip and knee athroplasty, highlighting noninvasive treatments, surgical techniques and outcomes, new technologies, and management of complications.

    The review panel recognized five particularly outstanding posters, honoring them with the ICJR East Abstract Awards. The Awards were supported by a grant from Zimmer, Inc.

    Following are the winning abstracts:

    Cones for Severe Bone Loss in Revision Total Knee Arthroplasty
    Primary Author: Ivan De Martino
    Institution: Orthopaedic Unit – Catholic University of the Sacred Heart, Rome, Italy
    Co-Authors: Rocco D’Apolito (Orthopaedic Unit –Catholic University of Magna Graecia, Catanzaro,Italy), Carlo Fabbriciani (Orthopaedic Unit – Catholic University of Magna Graecia, Catanzaro, Italy),Giorgio Gasparini (Orthopaedic Unit – Catholic University of Magna Graecia, Catanzaro, Italy)

    We report the 5-year results of 26 porous tantalum cones (Trabecular Metal Cone, Zimmer Inc., Warsaw, IN) implanted for severe femoral and/or tibial bone loss in 18 patients (12 women and six men) during revision TKA. Patients had an average age of 73 years at the time of the procedure. In this series, patients had a mean of 2.5 prior total knee arthroplasties.

    According to the Anderson Orthopaedic Research Institute (AORI) bone defect classification, all femoral and tibial defects were rated 2B and 3. A femoral cone was inserted in six patients, a tibial cone was inserted in five, a double cone in five (femoral and tibial) (Fig.1), and a triple cone in one (one femoral and two tibial). Twenty-four cones were impacted and two were cemented. Five patients were revised for aseptic loosening and 13 for infection.

    A two-stage procedure was used in all septic cases. A constrained condylar implant (LCCK, Zimmer, Warsaw) was inserted in six patients and a rotating hinge knee implants (RHK, Zimmer, Warsaw) in 12. The diaphysis was cemented in three cases and the metaphysic in 15. Offset stems were used in half of cases. The average preoperative Knee Society Score improved from 31 to 76 at 5 years follow-up. Radiological follow-up revealed no evidence of loosening and implant migration. All the radiographs showed good osteo-integration after 1 year. There were two cases of recurrent infection. In both cases, cones were noted to be well fixed to the bone at the time of explant. This study reveals a low infection rate (11%). Our excellent clinical and radiological results indicate that metaphyseal tantalum cones represent a valid option in revision total knee with severe bone defect.

    Mobile-Bearing UKA: A Systematic Review and Meta-Analysis
    Primary Author: Geert Peersman
    Institution: ZNA Stuivenberg, Schilde Antwerp, Belgium
    Co-Authors: Bart Stuyts (St. Augustinus, Wilrijk, Belgium), Tom Vandenlangenbergh (ZNA Stuivenberg, Schilde Antwerp, Belgium), Philippe Cartier (Clinique Hartmann, Neuilly sur Seine, France)

    PURPOSE: Two design concepts are currently in use for unicondylar knee arthroplasty (UKA) prostheses: Fixed bearing (FB) and mobile bearing (MB). MB prostheses have become increasingly popular due to their theoretical advantages over the FB design, such as the congruent bearing, which reduces contact stresses and polyethylene wear rates, and the closer re-creation of native knee kinematics. However, it is not clear whether the MB design is indeed superior to that of FB prostheses for UKA. We conducted a systematic review to examine survivorship differences and differences in failure modes of between FB and MB designs.

    METHODS: PubMed and Scirus were searched for randomized clinical studies, cohort studies, and case series reporting clinical outcomes for medial and/or lateral UKA. There were no language restrictions. A total of 44 studies involving 9,894 knees were eligible, including four randomized clinical trials and eight cohort studies. Methodological quality was assessed using a specific UKA survival assessment score. Outcomes studied included knee function, survivorship, and the reasons for, and incidence of, revision for FB and MB prostheses. Where available, cause-specific time to revision was extracted. The revision rate was expressed as number of revisions per 100 component years and compared between prosthesis designs.

    RESULTS: Mean follow-up was 8.5 years for FB and 5.2 years for MB prostheses. There were no other relevant differences in baseline characteristics. The overall crude revision rate for FB and for MB prostheses was 1.01 and 1.24 per 100 component years, respectively. Cause- specific revision rates were not reported or were incomplete in 57% of studies. In the remaining studies, aseptic loosening accounted for 0.27 and 0.40 revisions per 100 component years for FB and MB prostheses, respectively. The mean time to revision for aseptic loosening was 7.7 years in the FB group and 3.8 years in the MB group. In the MB group, insert dislocation accounted for 0.30 revisions per 100 component years, at a mean time to revision of 2.0 years.

    Adjusting for follow-up time resulted in a comparable overall revision rate for FB and MB prostheses of 1.26 and 1.21 revisions per 100 component years, respectively. In the adjusted analysis, aseptic loosening accounted for 0.34 and 0.35 revisions per 100 component years, respectively. There was a large variation in methodological quality of the studies, but no apparent association between survival outcome and publication quality.

    CONCLUSION: Crude analysis suggests survival advantages with FB UKA. However, adjusting for follow-up time confirms the equivalence of MB and

    FB UKA designs. The risk of loosening decreases over time. While insert dislocation is an additional cause of revision in MB knees, it does not increase the overall risk of failure. As our study is based on predominantly observational data, with large variations in reporting standards, inferences should be drawn with caution.

    Pulmonary Embolism After Total Knee Arthroplasty
    Primary Author: Nicholas B. Schraut
    Institution: University of Illinois at Chicago – Department of Orthopaedic Surgery, Chicago, IL, USA
    Co-Authors: Vincent Moretti (University of Illinois at Chicago – Department of Orthopaedic Surgery, Chicago, IL, USA), Ritesh Shah (Illinois Bone and Joint Institute, Morton Grove, IL, USA)

    INTRODUCTION: Pulmonary embolism (PE) is a rare but potentially devastating complication of total knee arthroplasty (TKA). The purpose of this study was to assess recent national trends in PE occurrence after TKA and evaluate patient outcomes.

    METHODS: International Classification of Disease-9th Revision (ICD-9) procedure codes were used to search the National Hospital Discharge Survey (NHDS) for patients admitted to U.S. hospitals after primary TKA for the years 2001-2010. ICD-9 diagnosis codes were used to identify patients who developed an acute PE during the same admission.

    Data regarding patient demographics, hospitalization length, discharge disposition, lower-extremity deep vein thrombosis (DVT), mortality, and hospital size/location were gathered. Trends were evaluated by linear regression with Pearson’s correlation coefficient(r), and statistical comparisons were made using Student’s t-test, z-test for proportions, and chisquare analysis with a significance level of 0.05.

    RESULTS: 35,220 patients admitted for primary TKA were identified; 159 (0.045%) of these patients developed an acute PE during the same admission.

    After adjusting for fluctuations in annual TKA performed, the development of PE after TKA demonstrated a weak negative correlation with time (r=0.17, Figure 1), insignificantly decreasing from an average rate of 0.049% between 2001 and 2005 to 0.041% between 2006 and 2010 (p=0.26). The size of the hospital was found to significantly impact the incidence of PE and primary TKA, with the lowest rate seen in hospitals under 100 beds (0.23%) and the highest rate seen in those with over 500 beds (0.65%, p=0.01). No significant differences in PE incidence were noted based on U.S. region (p=0.38).

    The mean age of patients with PE was 67.7 years. This group included 54 men and 105 women. The non-PE group had a mean patient age that was insignificantly lower at 66.6 years (p=0.21) and included 12,450 men and 22,611 women. Gender was also not significantly different (p=0.68) between PE groups. The number of medical comorbidities was significantly higher in those with PE (mean 6.42 diagnoses) than those without PE (mean 4.89 diagnoses, p<0.01). Average hospitalization length also varied based on PE status, with significantly longer stays for those with PE (8.2 days versus 3.7 days, p<0.01). The rate of DVT was higher in the PE group (12.7% versus 0.48%, p<0.01). Mortality was also significantly higher for the PE group (3.9% versus 0.09%, p<0.01). Discharge disposition did not significantly vary based on PE status, with 61.5% of PE patients and 64.0% of non-PE patients able to go directly home (p=0.59) after their inpatient stay.

    DISCUSSION/CONCLUSION: This study demonstrates that PE can have a significant impact on patient outcomes and healthcare costs, with associated 43-fold increase in mortality and a doubling of the inpatient admission duration. Additionally, although the risk of PE after primary TKA remains rare, efforts to prevent or minimize this complication over the last 10 years have not had a significant impact on its occurrence. This risk of PE appears to be greatest in patients with multiple medical comorbidities and established DVTs. Interestingly, the PE rate also demonstrated variability based on hospital size.

    Higher Tissue Concentrations of Vancomycin with Low-Dose Intraosseous Regional Versus Systemic Prophylaxis in TKA – A Randomized Trial
    Primary Author: Simon W. Young
    Institution: Mayo Clinic Hospital, Phoenix, AZ, USA Co-Authors: John Mutu-Grigg (Auckland Hospital, Auckland, New Zealand), Grant A. Moore (Christchurch Hospital, Christchurch, New Zealand), Mei Zhang (Christchurch Hospital, Christchurch, New Zealand), Joshua T. Freeman (Auckland Hospital, Auckland, New Zealand), Paul Pavlou

    BACKGROUND: In response to increasing antibiotic resistance, vancomycin has been proposed as an alternative prophylactic agent in total knee arthroplasty (TKA). However, vancomycin requires a prolonged administration time, risks promoting further antibiotic resistance, and can cause systemic toxicity. Intraosseous regional administration (IORA) is known to achieve markedly higher antibiotic concentrations than systemic administration and may allow the use of a lower vancomycin dose.

    Figure 1.

    Figure 2.

    QUESTIONS/PURPOSES: To assess whether lowdose IORA vancomycin can achieve equal or superior tissue concentrations to systemic administration in TKA.

    PATIENTS AND METHODS: Thirty patients undergoing primary TKA were randomised into three groups. Group 1 received 250 mg and Group 2 received 500 mg of vancomycin via IORA. Group 3 received 1 g of systemic vancomycin over 1 hour prior to tourniquet inflation. IORA was performed as a bolus injection into a tibial intraosseous cannula below an inflated thigh tourniquet, and it occurred after prep and draping and immediately prior to skin incision. Subcutaneous fat and bone samples were taken at 15-minute intervals during the procedure, and antibiotic concentrations were measured using a validated technique involving liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). All bone samples were taken from the femur, distant from the tibial intraosseous injection site. Systemic serum vancomycin levels were measured intraoperatively and at 1, 4, 8, and 24 hours postoperatively.

    RESULTS: The overall mean tissue concentration of vancomycin in subcutaneous fat was 14 μg/g in the 250-mg IORA group, 44 μg/g in the 500-mg IORA group, and 3.2 μg/g in the systemic group. Mean concentrations in bone were 16 μg/g in the 250-mg IORA group, 38 μg/g in the 500-mg IORA group, and 4.0 μg/g in the systemic group. One patient in the systemic group developed “red man syndrome” during infusion.

    CONCLUSION: Low-dose IORA vancomycin results in equal or higher tissue concentrations to systemic administration.

    SIGNIFICANCE: IORA optimises timing of vancomycin administration, and the lower dose may reduce the risk of systemic side effects while providing equal or enhanced prophylaxis in TKA.

    Factors for Manipulation Under Anesthesia After Total Knee Arthroplasty
    Primary Author: Juliet N. Amene
    Institution: Michigan State University College of Human Medicine, Flint, MI, USA
    Co-Authors: Stephanie A. Frazier (Michigan State University College of Human Medicine, Flint, MI, USA), Nakia M. Hunter (Michigan State University College of Human Medicine, Flint, MI, USA), Jenny LaChance (Hurley Medical Center, Flint, MI, USA)

    BACKGROUND: Arthrofibrosis is the most prevalent early periprosthetic complication following total knee arthroplasty (TKA) and can result in decreased range of motion (ROM) and significant disability. Manipulation under anesthesia (MUA), which is the first line of treatment, can lead to complications from anesthesia, periprosthetic fracture, hemearthrosis, and no gain in ROM.

    OBJECTIVES: Literature indicates that the need for MUA can be prevented with a combination of adequate physical therapy and positive patient-motivation techniques. The relationship between key demographic risk factors and MUA after TKA has not been explored previously. The purpose of this study was to identify if any key demographic characteristics are risk factors for MUA after TKA. This may allow physicians to identify patients who would benefit from more aggressive preventative measures. We hypothesized that certain patient demographics, including age, gender, race, and insurance (public versus private) would alter the risk for MUA following TKA.

    METHODS: A total of 1,087 patients received TKA for osteoarthritis (OA) at an urban hospital in Michigan from 2005 to 2012. Forty of these patients underwent an MUA within 3 months of TKA. Patient demographics were extracted from the patient charts. To determine if there was a difference in those who received MUA by gender, race, or insurance status, chi-square analyses were performed. Additionally, an independent t-test was used to determine if there was a difference in age for those who had MUA compared to those who did not have MUA.

    RESULTS: The overall incidence of MUA following TKA for OA at our institution was 3.7%. There was a significant difference (p <0.001) in the average age of those who had MUA compared to those who did not have MUA. The mean age of patients who needed MUA was 55 years, while the mean age of patients who did not require a MUA was 65 years. No significant difference in MUA status was detected for gender (p = 0.874), race (p = 0.665), or insurance (p = 0.158).

    CONCLUSION: Our study suggests that MUA patients are significantly younger than patients not receiving MUA following TKA. This finding is especially concerning since the average age of patients requiring TKA is decreasing. Therefore, the incidence of MUA for arthrofibrosis following TKA may continue to increase in the future. Younger patients may need to be targeted with more-aggressive rehabilitation efforts, although there may be other confounding variables with age that were not examined in this study. We are planning future research that will examine the impact of other risk factors, such as obesity and ROM, on the development of arthrofibrosis and the need for MUA following TKA.