Conclusions: Diabetic patients in the United States have significantly increased odds of observedsurgical and systemic complications, as well as potentially negative hospital course alterations afterprimary and revision total joint arthroplasties. These results indicate clinically relevant information forpatients, surgeons, and the US health care system in general, as these observational data suggest thatpatients undergoing joint arthroplasty procedures demonstrate fewer complications and use lessresources overall if they do not have the comorbidity of diabetes mellitus.

Level of evidence: prognostic level II.

doi:10.1016/j.arth.2008.01.254

PAPER #37

ANTIMICROBIAL EFFICACY OF FIVE COMMERCIALLY AVAILABLEANTIBIOTIC BONE CEMENTS: AN IN VITRO COMPARISONMatthew W. Squire, MD, MS, Brian Ludwig, MD, Jonathon Thompson, Jason Jagodzinski,David Andes, MD

Antibiotic bone cement (PMMA) can be used for primary total knee arthroplasty/total hip arthroplastyinfection prophylaxis as well as treatment and reconstruction of septic total knee arthroplasty/total hiparthroplasty. To date, no investigation has compared antimicrobial efficacies of commercially available,“pre-mixed” antibiotic PMMAs. This study compares the in vitro antibacterial activity of 5 antibioticPMMA formulations.

Highly standardized PMMA discs of Cemex Genta (Tecres Medical), Cobalt G-HV (Biomet), EnduranceGMV (DePuy), Palacos R+G (Zimmer), and Simplex P with Tobramycin (Stryker) were produced. Aquantitative Kirby-Bauer assay using the PMMA discs and a clinically relevant staphylococcal strain wasthen performed. For each PMMA above, 10 discs were assayed (n = 10), and the zone of bacterial growthinhibition was measured daily for 5 days. Analysis of variance was used to compare all data.

For all PMMAs, maximal staphylococcal antibacterial activity occurred on assay day 1 and rapidlydeclined to minimal levels by day 5. For assay days 1 to 4, all PMMAs containing gentamycin (Cemex,Cobalt, Endurance, and Palacos) demonstrated significantly greater antimicrobial activity (P b .01) thanPMMA containing tobramycin (Simplex). The antistaphylococcal activity of all gentamycin containingPMMAs was similar on days 1 to 4. On assay day 5, Cobalt and Endurance demonstrated significantlygreater (P b .01) bacterial growth inhibition than all other PMMAs. This in vitro study demonstrates thatcommercially available, “pre-mixed” antibiotic PMMAs produce substantial early antimicrobial activitythat rapidly diminishes. In addition, PMMAs containing gentamycin produce significantly greaterstaphylococcal antimicrobial activity than those containing tobramycin. Lastly, all PMMA formulationsare not equivalent with respect to the duration of their antimicrobial activity.

doi:10.1016/j.arth.2008.01.255

PAPER #38

LOCKED PLATING OF SUPRACONDYLAR PERIPROSTHETIC FEMURFRACTURESThomas Large, MD, Stephen Sims, MD, Michael Bosse, MD*, James Kellam, MD*, John L.Masonis, MD

Introduction: Assessment of locked condylar plating vs other treatment techniques for periprostheticsupracondylar femur fractures above a total knee arthroplasty (TKA).

Methods: Fifty above TKA fractures, with stable prosthesis (Lewis/Rorabeck type II), were treated withinternal fixation: group I (29 patients), locked condylar plating; group II (21 patients), 10 nonlockedplate systems, 4 rush rods, 7 retrograde intramedullary nails. Follow-up length was as follows: group I(25), 1.7 years; group II (15), 3.4 years. Outcomes measured were the following: operative data;revision, complication rates; range of motion; and radiographic parameters.

Results: Group I had 5 malunions (20%); group II, 9 (50%) (P b .05). Group I had zero nonunions; groupII, (16%) (P = .06). Group I had 3 complications (12%); group II, 8 (42%). Group I had significantly bettersagittal alignment with less shortening and greater knee flexion and total arc of motion. Each patientstreated with retrograde IMN had a malunion, nonunion, or complication.

Discussion: Locked plating is reliable treatment of supracondylar femur fractures above TKA.

doi:10.1016/j.arth.2008.01.256

PAPER #39

THE EFFECT OF PROPHYLACTIC PREOPERATIVE INTRAVENOUSANTIBIOTICS ON INTRAOPERATIVE CULTURES IN INFECTED TOTALKNEE ARTHROPLASTY: A PROSPECTIVE CLINICAL TRIALR. Stephen J. Burnett, MD, FRCS(C), Ajay Aggarwal, MD, Stephanie A. Givens, RN,J. Thomas McClure, MD, Robert L. Barrack, MD

Introduction: A prospective study was undertaken to determine whether prophylactic preoperativeintravenous (IV) antibiotics would affect the results of cultures obtained intraoperatively.

Methods: Eighteen total knee arthroplasties (TKAs) with a known infecting organism were enrolled atone institution for 24 months. Inclusion criteria were clinically infected TKA, known preoperativeinfecting organism, and no recent antibiotic therapy. ESR and CRP were performed preoperatively.Reaspiration of the infected TKA was performed after anesthesia induction. Intravenous antibioticprophylaxis was then administered. The tourniquet was inflated after prep and draping. Intraoperativeculture swabs and tissue were obtained at arthrotomy. The timing of events was recorded. Pre-/

postantibiotic culture data were analyzed to determine the effect of IV preoperative prophylacticantibiotics on cultures obtained intraoperatively.

Results: Infections were acute postoperative (2), chronic (14), and acute hematogenous (2). Total kneearthroplasty infection in women (14) outnumbered that of men (4). Mean time from end of antibioticinfusion to tourniquet inflation was 14 minutes and, to arthrotomy culture, 26 minutes Preoperative meanESR was 79; CRP, 98. The synovial fluid analysis revealed a mean nucleated cell count of 40000/mm

3

with 92% neutrophils. In all 18 knees, the organism(s) cultured at arthrotomy were the same aspreoperatively. In 17 knees, the organism cultured was sensitive to the preoperative prophylacticantibiotics given; 1 patient grew Candida albicans. Infecting organisms included: Staphylococcus aureus—oxacillin-sensitive (5), Streptococcus (2), MRSA (3), coagulase-negative Staphylococcus (3),pseudomonas (2), Candida (1), and mixed (N2 organisms) (2).

Conclusion: Prophylactic antibiotics did not affect the results of intraoperative cultures, and should notbe withheld before infected TKA surgery.

doi:10.1016/j.arth.2008.01.257

PAPER #40

FDG-PET IMAGING IN THE DIFFERENTIATION OF INFECTED FROMNONINFECTED PAINFUL HIP PROSTHESISThimothy Chryssikos, Elie Ghanem, MD, Javad Parvizi, MD*, Andrew Newberg, MD,Hongming Zhuang, MD, Abass Alavi, MD

Objectives: The accurate differentiation of aseptic loosening from periprosthetic infection in the painfulhip prosthesis is a major clinical challenge. FDG-PET imaging has shown great promise in variousclinical settings for detection of infection. This prospective study was designed to determine the efficacyof FDG-PET imaging in the assessment of patients with painful hip prosthesis.

Methods: One hundred thirteen patients with 127 painful hip prostheses were evaluated by FDG-PET.Approximately 60 minutes after the intravenous administration of FDG images of the lower extremitieswere acquired using a dedicated PET machine. FDG-PET images were interpreted by experiencednuclear medicine physicians. Images were considered positive for infection if PET demonstratedincreased FDG activity at the bone prosthesis interface of the femoral component of the prosthesis.Surgical findings, histopathology, and clinical follow-up served as the gold standard.

Results: FDG-PETwas positive for infection in 35 hips and negative in 92 hips. Among 35 positive PETstudies, 28were proven to be infected by surgical and histopathology findings aswell as follow-up tests. In 92hip prostheses with negative FDG-PET findings, 87 were proven to be aseptic. The sensitivity, specificity,and positive and negative predictive values for FDG-PETwere 0.85 (28/33), 0.93 (87/94), 0.80 (28/35), and0.95 (87/92), respectively. The overall accuracy of FDG-PET in this clinical setting was 90.5% (115/127).

Conclusions: The results demonstrate that FDG-PET is a highly accurate diagnostic test fordifferentiating infected from noninfected painful hip prosthesis. Therefore, FDG-PET imaging isconsidered the study of choice in the evaluation of patients with suspected hip prosthesis infection.

doi:10.1016/j.arth.2008.01.258

PAPER #41

MULTIMODAL PAIN MANAGEMENT AND ARTHROFIBROSIS IN PRIMARYTOTAL KNEE ARTHROPLASTYCarlos J. Lavernia, MD*, Michele D'Apuzzo, MD

Introduction: Pain management in arthroplasty has undergone significant changes in the last 3 years.Multimodal pain management in total knee arthroplasty (TKA) has been shown to significantly reduceopiate requirement after primary TKA. Our objective is to assess the effect of a multimodal painmanagement protocol on arthrofibrosis.

Methods: A cohort of 1136 primary TKAs was followed up (patients) prospectively as part of animplant registry. Patient oriented outcomes were collected before and after surgery. 358 consecutivepatients received multimodal pain management including preemptive analgesia and intraoperative localinjections and 778 patients had conventional pain management. Manipulation under anesthesia wasperformed on all patients bending less than 85 at week 6 in both groups. Statistical analysis included χ

2

and regression analysis. P b .05 was considered significant.

Results: The average age was 68 years ± 0.3 SE, 72.5% were women, and 90% had osteoarthritis asprimary diagnosis. In the multimodal pain management group 7 patients were manipulated vs 39 patientsin the other group (2% vs 5%; P = .01). The incidence in the number of manipulations was significantlyassociated with this new pain protocol in a regression model (P = .36). There were no complicationsrelated to the new pain management protocol.

Discussion: Pain response has been postulated to contribute to the development of arthrofibrosis afterprimary TKA. A balanced program of multimodal analgesia significantly reduces the incidence ofarthrofibrosis after primary TKA. In this cohort of patients, pain was probably an important etiologicfactor in the development of arthrofibrosis.

doi:10.1016/j.arth.2008.01.259

POSTER #200

HIGH PREOPERATIVE GLUCOSE AND NOT JUST DIABETES IS ANINDEPENDENT RISK FACTOR FOR PULMONARY EMBOLISMLuis Pulido, Javad Parvizi, MD*, Boris Mraovic, Jeffrey I. Joseph, DO*, Zvi Grunwald,Richard H. Rothman, MD*

AAHKS Abstracts � 323

We hypothesized that poor glycemic control preoperatively (blood glucose N200) may increase theincidence of pulmonary embolism (PE) after total joint arthroplasty. We retrospectively reviewed recordsof 7226 patients undergoing total joint arthroplasty from 2001 to 2006 at our institution. Multiple riskfactor were analyzed which included: age, sex, body mass index, ASA status, duration of surgery, type ofsurgery (hip vs knee, revision vs primary, bilateral vs unilateral), all comorbidities, perioperativeanticoagulation and preadmission glucose. The datawere analyzed using logistic regression. The incidenceof PE was 1.49% (108 patients). Multivariate analysis showed that preoperative glucose _200 mg/mLincreased risk of PE by 2.7 when compared with patients with glucose ??110 mg/dL; older age (N64 years)increased risk by 2.2; and body mass index above 40 kg/m

2increased risk by 2.2. Among cardiac

comorbidities, only congestive heart failure increased risk for PE by 2.5. Total knee arthroplasty carried 2.4times more risk than total hip arthroplasty. Bilateral procedure increased risk by 1.77. Revision surgeriesdid not increase risks compared with primary arthroplasty. All patients received postoperative deep venousthrombosis prophylaxis with warfarin per hospital protocol. Our data suggest that preoperativehyperglycemia is an independent risk factor for developing PE after major orthopedic surgery. Werecommend that target glycemia level should be less than 200 mg/dL before any major orthopedicprocedure. A prospective randomized controlled study would determine if tighter control of preoperativeglucose leads to a further decrease in the incidence of PE incidence in this clinical setting.

doi:10.1016/j.arth.2008.01.260

POSTER #201

ARTHROSCOPIC INDICATIONS FOR UNICOMPARTMENTAL KNEEARTHROPLASTYBarry J. Waldman, MD*, Esther Schaftel, James Stewart

Minimally invasive unicompartmental knee arthroplasty has been advocated as a treatment of medialunicompartmental arthritis. Patient selection is a crucial step in obtaining acceptable results ofunicompartmental arthroplasty. Some authors have advocated arthroscopy at the time of surgery, toevaluate the lateral compartment. Those patients with significant lateral wear or an unstable meniscusmight benefit from total knee arthroplasty instead of the planned unicompartmental arthroplasty. Thesenior author treated 100 consecutive patients with minimal incision unicompartmental knee arthroplastywith intraoperative evaluation to determine whether to proceed directly to total knee arthroplasty. In twocases, a decision was made to abandon the unicompartmental arthroplasty and proceed with total kneearthroplasty. All patients were evaluated at minimum 2-year follow-up with Knee Society Scores,radiographic evaluation, and clinical evaluation.

The authors feel that the small number of intraoperative changes in planning did not warrant the expenseand possible increased complication rate of arthroscopy performed during unicompartmental kneearthroplasty. Surgeons should rely on preoperative indications for patient selection in unicompartmentalknee arthroplasty.

doi:10.1016/j.arth.2008.01.261

POSTER #202

EARLY FAILURES OF UNICOMPARTMENTAL REPLACEMENTSC. Lowry Barnes, MD*

Introduction: Unicompartmental replacements have been recommended for isolated compartmentalknee arthritis. The purpose of this study was to prospectively study 1 design of unicompartmentalreplacement.

Materials and Methods: Prospective data were recorded for 30 consecutive patients (11 women and19 men) who met indications for unicompartmental arthroplasty. Two patients had bilateral procedures,allowing 32 knees for routine evaluation. The average age was 74 (range, 59-94) years. Patients werefollowed up for a minimum of 3 years or until revision.

Results: Six knees in 6 patients (19%) were revised in this short follow-up. In 5 of 6 knees, there wasloosening of tibial and/or femoral component(s).The remaining patient had progression of disease inother compartments. Those patients not requiring revision surgery had excellent results by Knee Societyscore standards.

Conclusion: We are reporting a significant early failure rate of almost 20% at 3 years for this group ofpatients treated with a unicompartmental design consisting of an all polyethylene on-lay tibialcomponent. We will discuss failures in selection as well as technique.

doi:10.1016/j.arth.2008.01.262

POSTER #203

CONTEMPORARY TOTAL HIP ARTHROPLASTY FOR THE DYSPLASTIC HIPChristopher L. Peters, MD*, Bryce Allen, MD, Jill Erickson, PA-C

Introduction: Treatment of the arthritic dysplastic hip has evolved from cemented implants andsubstantial use of autogenous or allogenic bone graft to modular cementless implants that allow forintraoperative flexibility with associated decrease need for bone graft. Alternative bearing surfacesdespite small component sizes have also changed management.

Materials and Methods: One hundred hips with Harris subtotal or total dislocation were treated withtotal hip arthroplasty of 741 primary total hip arthroplasties. Average age was 41 (range, 15-74). Averagefollow-up was 4.5 years (range, 2-10). Of the hips, 51% (51/100) were treated with a modular (SROM)femoral stem to adjust femoral anteversion, and 49, with a conventional proximal porous-coated device.Three percent had a femoral osteotomy. One hundred percent cementless porous-coated acetabularcomponents were placed in the anatomic center without the use of bone graft. Sixty percent were metal-on-metal; 40% were metal-on-polyethylene.

Results: Of 100 femoral and acetabular components, 99 remain in place. The Harris Hip Score improvedfrom 53 to 94. There were 3 revisions for dislocations (3%): 2 modular exchanges and 1 acetabular revision.There was 1 nonunion of a subtrochanteric osteotomy. There was 1 partial nerve palsy and 7 intraoperativefemoral fractures treated with cerclage wires at the time of the index procedure. Radiographically, allacetabular components and femoral components were bone-ingrown without eccentric wear or osteolysis.

Discussion: Contemporary arthroplasty for the arthritic dysplastic hip has evolved to the use ofcementless components placed without the need for supplemental bone graft. Component modularity hasfacilitated correction of femoral version and rotational deformities, and alternative bearing surfaces mayimprove wear-related complications. Combined, these advances have simplified arthroplasty treatmentof the dysplastic hip.

doi:10.1016/j.arth.2008.01.263

POSTER #204

NON–SEX-SPECIFIC TOTALKNEEARTHROPLASTY: A REVIEWOF 1000 CASESCOMPARING MEN AND WOMENMichael H. Bourne, MD*, E. Marc Mariani, MD*

Recent publicity concerning sex-specific knee arthroplasties and their potential advantages have caused usto analyze prospectively collected data on 1000 consecutive unilateral knee arthroplasties. The knee designused was a non–sex-specific knee arthroplasty sized in the anteroposterior dimension of the femur andsized specifically and independently for the tibia. We used a cemented posterior stabilized design with 1-mm incremental polyethylene spacers. Women represented 70% of the cases performed. Men and womenwere well-matched for anesthetic risk (age: women 69 years; men, 67 years), with the body mass indexbeing slightly higher for the women. We compared data at 1 year after knee arthroplasty.

The results showed significant benefit in both men and women with the same degree of improvement.The men began with higher knee scores and ended with higher knee scores; the women had overallgreater improvement than men with respect to knee motion. Men began with higher functional scoresand ended with higher functional scores but women showed the same degree of functional improvement.Patient satisfaction was essentially equivalent in men and women (women, 97.4% [good or excellent]compared with 96.0% in men).

We feel that a non–sex-specific total knee arthroplasty can give excellent results in both men and womenand attribute this in part to careful sizing of the anteroposterior femoral dimension and having a kneefemoral component which does not overhang in the ML dimension. This is consistent with previousreported excellent results in men and women undergoing knee arthroplasty with conventional devices.

doi:10.1016/j.arth.2008.01.264

POSTER #205

THE CHANGING ORGANISM PROFILE IN PERIPROSTHETIC INFECTIONElie Ghanem, Camilo Restrepo, Luis Pulido, Mary Tierney, James J. Purtill, MD,Peter F. Sharkey, MD*, Javad Parvizi, MD*

Introduction: Periprosthetic infection (PPI) continues to compromise the outcome of otherwisesuccessful joint arthroplasty. Current strategy for treatment of this dreadful problem is based onantibiotic sensitivity of the infecting organism. The objective of this study was to evaluate the profile oforganisms that cause PPI over the last few years.

Methods/Materials: All 351 patients with PPI who received surgical treatment at our institution during1999 to 2005 were included. The surgical treatment involved irrigation and debridement in 97 cases(28%), 1-stage exchange arthroplasty in 31 cases (9%) and 2-stage exchange arthroplasty in 217 cases(62%). Patients were included only once in the analysis unless an organism was grown during a secondrevision procedure that was different from the one cultured during the initial surgery.

Results: The burden of PPI at our institution has increased over the last few years. Gram-positive coccicause 92% of PPI, whereas the incidence of infection with Gram-negative organisms (8%) was relativelylow. A steady increase in the incidence of infections caused by methicillin-resistant Staphylococcus wasnoted with the incidence increasing from 13% in 1999 to more than twice that at 30% in 2005.

Discussion: Our data indicate that a change in the profile of infecting organisms resulting in PPI has occurredover the last few years, at least at our institution. The increase in the number of infections caused bymethicillin-resistant organisms could potentially compromise the success of current treatment of thisproblem.Although liberal use of antibiotic is likely to be themajor reason, future studies are needed to assessthe reason behind the worrisome rise in the incidence of methicillin resistant periprosthetic infections.

doi:10.1016/j.arth.2008.01.265

POSTER #206

LEARNING CURVE WITH MINIMALLY INVASIVE UNICOMPARTMENTALARTHROPLASTYWilliam G. Hamilton, MD*, Deborah J. Ammeen, BS*, Kevin B. Fricka, MD*,C. Anderson Engh, *, Gerard A. Engh, MD*

Introduction: We have previously reported the early rate of revision and reoperations using the samecomponent design with minimally unicompartmental arthroplasty. The purpose of this study was todetermine if this complication rate decreased with increasing experience.

Materials and Methods: A retrospective review was performed on the first 507 medialunicompartmental arthroplasties performed between 2001 and 2004 by 4 surgeons at our institutionusing the same implant design. Of these 507 patients, 445 have known clinical outcome at 2 years.

324 The Journal of Arthroplasty Vol. 23 No. 2 February 2008