Coa/cors combined paper session 4: joints and arthritis ●

COA Paper Session 17: Knee Reconstruction 2
Moderators Bas A. Masri, BC, and Clare Marx, President of the British
Orthopaedic Association
156 –
The Effect of Prophylactic Pre-operative IV Antibiotics on Intra-
operative Cultures in Infected TKA- A Prospective Clinical Trial

R. Stephen J. Burnett, Division of Orthopaedic Surgery, Victoria; Ajay
Aggarwal, University of Missouri; Stephanie A. Givens, Washington
University - Department of Orthopaedic Surgery; J. Thomas McClure,
Nashville Orthopaedic Specialists; Robert L. Barrack, Washington University
Department of Orthopaedic Surgery
Purpose: Prophylactic antibiotics are frequently withheld until cultures are
obtained in revision TKA. A prospective study was undertaken to determine
whether prophylactic pre-operative IV antibiotics would affect the results of
cultures obtained intra-operatively. Method: A consecutive series of 25
TKA’s with a known infecting organism were enrolled over 36 months.
Inclusion criteria: clinically infected TKA, a known preoperative infecting
organism, and no recent antibiotic therapy. Re-aspiration of the infected TKA
was performed following anesthesia and sterile prep. IV antibiotic
prophylaxis was then administered and the tourniquet was then inflated.
Intra-operative culture swabs and tissue were obtained at arthrotomy. The
timing of events was recorded. Pre/post antibiotic culture data were analyzed
to determine the effect of IV preoperative prophylactic antibiotics on cultures
obtained intra-operatively. Results: Mean time from end of antibiotic infusion
to tourniquet inflation was 15 minutes; to arthrotomy culture was 25 minutes.
In all 25 knees the organism(s) cultured at arthrotomy were the same as
obtained at pre-operative aspiration. In 24 knees the organism cultured was
sensitive to the preoperative prophylactic antibiotics given (Ancef and
Vancomycin); one patient grew Candida albicans. Conclusion: Pre-
operative prophylactic antibiotics did not affect the results of intra-operative
cultures, and should not be withheld prior to infected TKA surgery when an
organism has been identified on aspiration. Based on these results, holding
pre-operative antibiotics prior to revision TKA is rarely justified.
157 –
Antibiotic Bone Cement and the Incidence of Deep Infection Following
Total Knee Arthroplasty

Rajiv Gandhi, University of Toronto; Fahad Razak, University of Toronto; J
Roderick Davey, University of Toronto; Khalid Syed, University of Toronto;
Rubini Pathy, University of Toronto; Nizar N. Mahomed, University of
Purpose: Prophylactic use of antibiotic-laden bone cement (ALBC) has been
proposed to decrease the incidence of deep infections. We asked if the use
of antibiotic laden bone cement decreased the deep infection rate following
primary total knee replacement (TKA) as compared to plain bone cement
(PBC). Method: We surveyed 1,625 consecutive patients undergoing
cemented, primary knee replacement with either ALBC or PBC. Relevant
covariates including age, body mass index (BMI), gender, education, and
medical co-morbidity were collected. Joint pain and functional status were
assessed at baseline and at 1 year follow up with the respective Western
Ontario McMaster University Osteoarthritis Index (WOMAC) scores. The
incidence of deep infection at 1 year follow up was recorded. Results: There
were 811 (49.9%) patients in the ALBC group and 814(50.1%) in the PBC
group. There were no differences in age, gender, BMI, education or
comorbidity between groups at baseline (p>0.05). We found a deep infection
rate of 3.1% in the ALBC group and 2.2% in the PBC group (p=0.27).
Adjusted analysis showed that ALBC was not predictive of a lower infection
rate at 1 year (p=0.84). Conclusion: ALBC did not reduce the incidence of
deep infection following primary TKA at 1 year follow up. Further studies are
needed to define any high risk groups for which ALBC might be beneficial.
158 –
Metabolic Syndrome and the Incidence of Deep Vein Thrombosis
Following Total Knee Arthroplasty

Rajiv Gandhi, University of Toronto; Fahad Razak, University of Toronto;
Peggy Tso, University of Toronto; J Roderick Davey, University of Toronto;
Nizar N. Mahomed, University of Toronto
Purpose: Metabolic syndrome (MS) is defined as central adiposity, elevated
fasting glucose, hypertension, and dyslipidemia defined as high triglyceride
and low high-density lipoprotein (HDL) cholesterol. MS is associated with a
systemic proinflammatory and prothrombotic state. We asked if patients with
MS undergoing total knee arthroplasty (TKA) have an increased risk for
symptomatic deep vein thrombosis at 3 months follow-up (DVT). Method:
1,460 consecutive patients were reviewed from our joint registry undergoing
primary, unilateral TKA between the years of 1998-2006. Demographic
variables of age, gender, comorbidity, and education were retrieved.
Metabolic syndrome (MS) was defined as body mass index above 30 kg/m2,
diabetes, hypertension, and hypercholesterolemia. Logistic regression was
used to examine the relationship of MS on the incidence of DVT. Results:
The overall incidence of symptomatic DVT was 4.4% (65/1460). Patients
with MS had an increased incidence of DVT as compared to those without
MS(15.5% vs 3.4%). Adjusted analysis showed that MS increased the risk of
symptomatic DVT by 3.2(95% CI [1.0,15.4], p=0.04) times compared to
those without MS. Conclusion: Hospital protocols developed for
prophylactic anti-coagulation following TKR should give special consideration
to patients with MS.
159 –
The RECORD4 Study: Oral, Once-daily Rivaroxaban Compared to
Subcutaneous, Twice-daily Enoxaparin for Prevention of Venous
Thromboembolism After Total Knee Replacement

William D. Fisher, McGill University Health Centre; Michael Gent, McMaster
University; Bruce L. Davidson, Weill Cornell Medical College; Michael R.
Lassen, Hoersholm Hospital; Louis M. Kwong, Harbor-UCLA Medical Center;
Fred D. Cushner, Insall Scott Kelly Center for Orthopaedics and Sports
Medicine; Paul A. Lotke, University of Pennsylvania Medical Center; Frank
Misselwitz, Bayer Health Care AG; Tiemo J. Bandel, Bayer Health Care AG;
Alexander G.G. Turpie, McMaster University
Purpose: Venous thromboembolism (VTE) after major orthopaedic surgery
remains an important clinical problem. Convenient, oral antithrombotic
agents that are both effective and safe could improve adherence to
guidelines for VTE prophylaxis. Recently, the focus has been on the
development of oral agents that target a single step in the coagulation
cascade and Factor Xa is a pivotal step. Rivaroxaban is an oral, direct Factor
Xa inhibitor. Four international phase III trials (the RECORD programme)
were undertaken to investigate the safety and efficacy of once-daily
rivaroxaban for thromboprophylaxis after major orthopaedic surgery. The
results of RECORD3 showed that rivaroxaban was more effective than
enoxaparin 40 mg once daily after total knee replacement (TKR), with a 48%
risk reduction in VTE and all cause mortality. RECORD4 was designed to
determine the efficacy and safety of 10 mg rivaroxaban od compared to 30
mg bid enoxaparin after total knee replacement (TKR). Method: This study
randomized 3148 patients to either rivaroxaban (10 mg od started 6–8 hours
after surgery) or enoxaparin (30 mg bid s.c. started 12–24 hours after
surgery) for 10–14 days. The primary efficacy outcome was the composite of
asymptomatic deep vein thrombosis (DVT) detected by mandatory, bilateral
venography and symptomatic DVT, non-fatal pulmonary embolism (PE), and
all-cause mortality up to day 13±4. Secondary outcomes included major VTE
(composite of proximal DVT, non-fatal PE, and VTE-related death) and
symptomatic VTE. Safety outcomes included on-treatment major and non-
major bleeding. Results: Rivaroxaban provided a 31% relative risk reduction
in the incidence of the primary efficacy outcome when compared to
enoxaparin (6.9% vs 10.1%, respectively; p=0.012). The corresponding rates
for major VTE were 1.2% and 2.0%, respectively (p=0.124) and for
symptomatic VTE were 0.7% and 1.2%, respectively (p=0.187). There were
no significant differences in bleeding incidence observed between
rivaroxaban and enoxaparin (major bleeding: 0.7% vs 0.3%, respectively,
p=0.110; clinically relevant non-major bleeding: 2.6% vs 2.0%, respectively,
p=0.279). Conclusion: Rivaroxaban 10 mg od is the first oral
thromboprophylactic agent to significantly reduce the incidence of VTE after
TKR compared to enoxaparin 30 mg bid, with a similar, low rate of bleeding.
160 –
Alignment to ACCP Prophylaxis Guidelines and VTE Outcomes in THR
and TKR Patients

Rita Selby, Division of Hematology, University of Toronto; Bijan Borah,
i3Innovus, Eden Prarie, USA; Heather McDonald, Bayer Inc., Canada; Joe
Henk, i3Innovus, Eden Prarie, USA; Mark Crowther, Department of
Hematology, St. Joseph’s Healthcare, Hamilton, Canada; Phil Wells, Division
of Hematology and Clinical Epidemiology, Ottawa Health Research Institute/
University of Ottawa, Ottawa
Purpose: A retrospective database analysis was conducted to a) determine
the extent to which the American College of Chest Physicians (ACCP)
guidelines for VTE prophylaxis are followed after total hip replacement (THR)
and total knee replacement (TKR) and b) evaluate the incidence of VTE for
patients receiving and not receiving prophylaxis according to ACCP
guidelines (‘ACCP’ and ‘non-ACCP’, respectively). Method: A claims
database associated with a large US health plan was linked to the Premier
database, which provides details of in-patient medication use. Patients ≥18
years undergoing TKR/THR and enrolled in the health plan 90 days before
and 90 days following discharge from hospitalization (or until death) were
included. Patients were considered to have received ACCP-guideline
prophylaxis if they: a) received LMWH, fondaparinux, or VKA following
surgery b) initiated prophylaxis within one day of surgery (for THR patients)
and c) were prescribed prophylaxis for a minimum of ten days, or until the
occurrence of major bleeding, VTE, or death. In addition, the number of
DVTs and PEs occurring in ACCP and non-ACCP patients was recorded.
Results: Of the 30,644 eligible patients from the health plan, 3,497 patients
were linked to the in-patient database. Except for geographic indicators,
there were no significant differences in demographics or baseline co-
morbidities between those included and excluded from the final study
sample. Of the 3,497 linked patients, 1,395 (40%) received ACCP
prophylaxis. The number of DVTs occurring in the ACCP and non-ACCP
groups were 28 (2.01%) and 79 (3.76%), suggesting that non-ACCP patients
were almost twice as likely as ACCP patients to have a DVT (p=0.0521). The
number of PEs occurring in the ACCP and non-ACCP groups were 2
(0.14%) and 25 (1.19%), respectively, suggesting that non-ACCP patients
were 8.5 times more likely than ACCP patients to experience a PE
(p<0.0001). Conclusion: This study offers a unique perspective on ‘real-
world’ prophylaxis patterns and clinical outcomes in THR/TKR patients. It
suggests that 40% of patients received ACCP prophylaxis and that patients
not receiving ACCP prophylaxis were almost twice as likely to have a DVT
and more than eight times as likely to experience a PE.
161 –
Introduction of a User-friendly Dose of Tranexamic Acid in Primary
Arthroplasty Patients

Fiona Ralley, London Health Sciences Center, University Hospital; James J.
Howard, London Health Sciences Center, University Hospital; Donna Berta,
London Health Sciences Center, University Hospital; Valerie Binns, London
Health Sciences Center, University Hospital; Douglas Naudie, London
Health Sciences Center, University Hospital
Purpose: Multiple studies have demonstrated the efficacy of Tranexamic
Acid (TA) in reducing blood loss and red blood cell transfusion in patients
undergoing primary total hip (THA) or knee (TKA) arthroplasty. However, the
dosing schedules of either an initial bolus followed by a 6-12 hour infusion or
multiple intravenous bolus doses are not 'user-friendly' for regular
application. The purpose of this study was to assess the efficacy and
acceptance of a single dose protocol for the use of TA in primary THA or
TKA. Method: We selected a single dosing schedule of 20mg/kg TA given
either prior to skin incision for THA or approximately ten minutes prior to
tourniquet release for TKA. The hospital pharmacy supplied the TA rounded
off to the nearest 5kg/100mg in a 100ml mini-bag. In March 2008, we
introduced the routine use of TA to all patients undergoing primary THA or
TKA at our institution. Mini-bags were pre-ordered at the time of the
preoperative clinic visit and delivered to the pre-surgical preparation area on
day of surgery. One month after implementation of this protocol we
compared blood loss, transfusion rates, and hemoglobin at discharge
between the patients operated on from April 1 to June 30, 2007 (when this
protocol was not in place) to those from April 1 to June 30, 2008. No other
routine patient care practices were altered during this time period. Results:
We found a significant reduction in the decrease in hemoglobin from 2007
compared to 2008 for both THA and TKA (46g/L to 39g/L, and 45g/L to
36g/L, respectively), which led to both a reduction in transfusion rates
(13.5% to 3.6%, and 13.1% to 2.0%, respectively) and higher hemoglobin
levels at discharge. All patients received the TA as ordered. Conclusion:
Dosing and timing of TA is critical to maximize its antifibrinolytic effect. Our
weight increment dose protocol led to minimal dose variability, facilitated
pharmacy drug preparation, and minimized wastage. This simple 'user-
friendly' protocol was found to reduce the decrease in hemoglobin and
transfusion rates, demonstrating similar efficacy to other more complex
dosing schedules. This protocol was well received and accepted by
surgeons, anesthesiologists, pharmacy, and nursing staff.
162 –
Stiffness Complicating Total Knee Arthroplasty: Computerized
Tomography Evaluation of Component Rotational Position and
Outcomes of Complete Revision for Restoration of Adequate Rotational

Martin Bedard, Laval University; Kelly G. Vince, University of Auckland;
John Redfern, University of Southern California
Purpose: Stiffness following TKA is devastating and poorly understood. This
study was conducted to determine if rotational positioning of tibial and/or
femoral components was related to the development of stiffness following
TKA. In addition, post-revision rotational alignment was studied to determine
if it contributed to improvement. Method: Patients who presented with
stiffness and either a fixed flexion contracture >15 and/or flexion <105
degrees were included in the study. 34 revisions were investigated
preoperatively by computerized tomography (CT) for rotational evaluation of
the components. Clinical and radiographic data were also recorded.
Results: All 34 revisions had some degree of combined internal rotation on
the preoperative CT-scan. The net combined angle averaged fourteen point
eight degrees of pathologic internal rotation (in excess of the normal
eighteen degrees)[1]. The most significant source of internal rotation was the
tibial component, with 33 of the 34 patients having internal rotation with a
mean pathological (in excess of the normal eighteen degrees) angle of 13.3
degrees (one to 35 degrees). Postoperatively, the combined rotation angle
was restored to an average of five point one degrees of external rotation for
the eighteen patients with available CT-scans (p < 0.0001). The 34 revised
knees were clinically followed for an average of 22 months. The mean
preoperative Knee Society knee and function scores were respectively 41.6
and 47.9. The mean preoperative range of motion was 61.4 degrees.
Postoperatively, the knee and function scores increased respectively to 77.3
and to 65.7 (p < 0.0045). The mean postoperative range of motion averaged
98.1 degrees (p < 0.0001). Conclusion: Rotational positioning of the
components should be investigated with CT-scan in stiff knees following
TKA. Revision surgery of all the components with restoration of an adequate
rotational alignment has been shown to improve range of motion, function
and pain.
163 –
Minimally-invasive Total Knee Arthroplasty: Potential Complications
Based on a Large Single-surgeon Cohort Review

Michael G. Zywiel, Rubin Institute for Advanced Orthopaedics; Peter M.
Bonutti, Bonutti Clinic; Slif D. Ulrich, Rubin Insititute for Advanced
Orthopaedics; Mike S. McGrath, Rubin Institute for Advanced Orthopaedics;
Michael A. Mont, Rubin Institute for Advanced Orthopaedics
Purpose: Minimally-invasive total knee arthroplasty has generated
tremendous recent interest, but there have been reports of complications
resulting from these new techniques. However, most studies have less than
one year follow-up and are anecdotal in their results. The purpose of this
study was to retrospectively evaluate a series of 1,000 consecutive minimally
invasive total knee arthroplasties, to describe the clinical and radiographic
complications of this technique, to determine whether complication rates
changed with experience, and finally to compare complication rates to a
match group operated by the same surgeon. Method: Clinical and
radiographic data were reviewed for the first 1,000 consecutive minimally-
invasive knees (820 patients) performed by a single surgeon with a minimum
2 year post-operative period. All patients were operated using the mid-vastus
approach, with a mean incision length of 10 cm (range, 8 to 13 cm). Nine
patients were lost prior to 2 year follow-up, leaving 990 knees (811 patients)
in this report with annual follow-up. After determining overall results, data
was stratified into 100-knee groups to determine whether complication rates
changed over time. Finally, complication rates were compared to a matched
group of 50 knees operated by the same surgeon. Results: There were a
total of 45 clinical complications (4.5%), including 20 (2.0%) manipulations
under anesthesia, 12 (1.2%) arthroscopies for painful crepitus, 4 (0.4%)
component changes, and 3 (0.3%) spacer changes. There were 3 (0.3%)
impending radiographic failures. Stratification of results showed a
complication rate of 6% over the first 200 knees, and 1% over the
subsequent 800 knees. In comparison, the matched group had a
complication rate of 4% over mean follow-up of 3 years (range, 2 to 4).
Conclusion: This large series with minimum two year follow-up describes
many of the long-term complications of this technique. Additionally, this large
series suggests that high volume knee surgeons may require as many as
200 minimally invasive arthroplasties before achieving optimum proficiency
with this technique. Nonetheless, comparison to a matched group suggests
that even with this learning curve, complication rates need not increase
markedly during this period if surgeons remain attentive to the potential
complications associated with minimally invasive techniques.
164 –
Incidence of Spinal Epimorph Related Complications in Total Joint

Aaron Bigham, University of Western Ontario; James J. Howard, UWO;
Sugantha Ganapathy, UWO
Purpose: Spinal epimorph is commonly used as part of multimodal
analgesia for patients undergoing total joint arthroplasty. Patients who
receive spinal epimorph are at risk for certain post- operative complications.
The purpose of this study was to determine the incidence of complications in
patients undergoing total joint arthroplasty with administration of spinal
epimorph compared to patients undergoing the same procedure who did not
receive spinal epimorph as part of their analgesia. Method: A retrospective
chart review of 72 patients in which two age, sex and procedure matched
groups were compared for differences in known spinal epimorph
complications. One group received spinal epimorph as part of their analgesia
while the comparative group did not receive spinal epimorph but rather
continuous infusion of local analgesia. Data extraction involved foley and
oxygen usage, documented nausea/vomiting and puritis, associated risk
factors and complications such as prostate disease and urinary tract
infections, and secondary outcome measures such as Gravol and Benadryl
usage. Results: Comparison of the two well-matched groups demonstrated
that patients who received spinal epimorph had increased rates of foley
insertion (p=0.0026), foley duration (p=0.015), oxygen usage (p=0.0053),
documented puritis (p=0.0006) and Benadryl usage (p=0.0053). Trends
towards increased nausea/vomiting (p=0.17), antiemetic use (p=0.16) and
urinary tract infections (p=0.15) were seen in the spinal epimorph group,
although these differences did not reach statistical significance. Conclusion:
The use of spinal epimorph as part of an analgesia protocol surrounding total
joint arthroplasty is associated with increased complications and patient
discomfort when compared to patients who received continuous local
infiltrative analgesia. Further research is needed to determine if alternate
modes of analgesia provide adequate pain relief when compared with spinal
epimorph and thus provide suitable alternatives with less complications.


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