Analysis of Competitive PCR and PS Total Knee Arthroplasty
Conditions: Knee Osteoarthritis, Total Knee Arthroplasty, Knee
Sponsor: The University of Tennessee, Knoxville

Analysis of Competitive Posterior Cruciate Retaining (PCR) and 
Posterior Stabilized (PS) Total Knee Arthroplasty (TKA)  
 
NCT04321356 
12/19/2019 
 
Richard D Komistek, PhD 
University of Tennessee 
310 Perkins Hall 
Knoxville, TN 37996  
Phone: (865) 974-2093  
Fax: (865) 946-1787  
Email: rkomiste@utk.edu 
 
In vivo knee kinematics will be assessed for 100 subjects that have been implanted with either a 
Stryker or a Zimmer PS or CR TKA.  All TKAs should be judged clinically successful (KSS > 
80).  A KSS score of greater than 90 is deemed to be excellent by the Knee Society.  Each 
subject should have a well-functioning prosthesis, be at least three months post-operative, and 
should have good-to-excellent post-operative passive flexion.  
    
Deciding which patients received which kind of implant was up to the discretion of Dr. Harold 
Cates, according to his professional opinion. The determination as to which type of implant 
patients received is outside the scope of this particular study. Subjects will already have the knee 
implants and must be at least three months post-operative. Bilateral subjects will not be included 
in the study populations. 
 
Inclusion criteria: 
1. Subjects will have required type of TKA. 
2. Patients must be at least three months post-operative. 
3. Participants must be judged clinically successful with their most recent new Knee Society 
score equal to or greater than 80. 
4. Weigh < 250  
5. BMI < 40 
6. Must be >40 years of age 
7. Participants must be able to perform the required activities without concern.  
8. Patients must be willing to sign the Informed Consent (IC) form to participate in the 
study.  
 
Exclusion criteria: 
1. 
Pregnant, potentially pregnant, lactating females or of childbearing age. To satisfy 
radiation protocol, each female subject will be asked if she is pregnant, or possibly 
could be pregnant. A pregnant person will not be allowed to participate in the study. 
2. 
Subjects without the required type of knee implant. 
3. 
Cannot not have pain in other parts of the body that would prohibit the patient from 
performing the activities 
4. 
Cannot have ligamentous pain and/or laxity. 
5. 
Unwilling to sign IC form. 

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6. 
Does not speak English. 
 
 
Study locations 
Subject Recruitment will take place at the Research Foundation of Dr. Harold Cates: 
9330 Park West Blvd., Suite 208B 
Knoxville, TN 37923 
Phone: (865) 373-1811 
 
Fluoroscopic exams will be performed on all subjects at:  
Tennessee Orthopaedic Clinic 
9430 Park West Blvd. 
Knoxville, TN 37923 
 
Study data analysis: 
Science and Engineering Research Facility 
1414 Circle Dr. 
Knoxville, TN 37996 
 
CMR Administrative offices: 
310 Perkins Hall 
1506 Middle Dr. 
Knoxville, TN 37996 
(865) 974-2093 
 
Data Collection 
University of Tennessee researchers with experience conducting fluoroscopic research studies, as 
well as either a PI or Co-PI for the study, and possibly Dr. Cates’ staff will be present during the 
fluoroscopy procedure to walk subjects through the activities. A radiation technician (RT) 
employed by Parkwest Medical Center will collect fluoroscopic video while subjects perform the 
following activities: deep knee bend.  For the DKB activity, the subjects were instructed to begin 
at full extension on a raised platform and take a step back while flexing their knee as far as they 
could, in order to obtain a maximum flexion value for each subject. For this activity, images 
were taken at 30° increments from full extension (0°) to maximum flexion (MAX) for the entire 
flexion/extension cycle. Patients were examined while performing these activities using a C-Arm 
type fluoroscopic unit. The fluoroscopic videos were captured digitally and transferred to a 
secure lab network for subsequent analysis. 
 
 
 
If a subject does not meet the inclusion criteria, s/he will not be tested. If the participant still 
meets all study criteria, s/he will be asked to practice the activities to ensure s/he can 
comfortably complete them and experience no pain with the hospital fluoroscopy machine off 
(no radiation).  The practice portion of the data collection without radiation will not be video-
recorded. During the fluoroscopy procedure, the RT will follow the motion of the implanted knee 
with the fluoroscopy machine; only the knee joint (from the fluoroscopy machine) will be 
recorded on the fluoroscopy footage. The participant will be allowed to rest as necessary and be 
instructed to stop the activity at the first sign of pain.  

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Multiple trials of each activity may be conducted to ensure usable images have been acquired to 
complete the study. Radiation time will be kept as low as reasonably achievable (ALARA) and 
will not exceed two minutes. The RT will start the fluoroscope just prior to the subject beginning 
each activity trial and will stop the fluoroscope immediately after the subject completes each 
activity trial to ensure that the subject is not exposed during idol periods. Fluoroscopy on-time 
will be recorded on each subject’s IC. 
 
The fluoroscopic footage for these activities will be stored on digital video files on a secure 
computer workstation, uploaded onto the secure CMR database by the UT researcher that 
attended data collection, where identifiable data will be removed and substituted for data that 
cannot identify the subject (e.g., dates of birth will be removed and replaced with number of 
months the individual has been alive). Subjects will be assigned study and subject-specific 
identifiers which is how the system will distinguish the datasets.   
 
DATA ANALYSIS  
 
The kinematic variables of interest included the femoral and tibial 3D rotational and translational 
kinematics. The relative motion of the femoral component and tibial component were calculated 
based on the transformation matrices of each rigid body. This information was then used to 
extract anterior/posterior low points and contact points as well as internal/external rotation of the 
femoral component with respect to the tibial component. 
 
Once the subjects have completed the activity, the fluoroscopic videos will be stored  
digitally and specific frames of interest will be captured from the video and exported into the 
preprocessing software. The specific frames of interested will be full extension, maximum knee 
flexion (both inclusive), and 30º knee flexion increments during the complete flexion cycle.  
 
Our 3D to 2D registration technique will be used to overlay the 3D models of the implanted 
components on their projection in the 2D fluoroscopic image. The fluoroscopic video would be 
digitized into frames and corrected for distortion. From here, the distortion-free images would be 
used with the 3D to 2D registration technique to extract in vivo patient femorotibial kinematics, 
which involves overlaying the 3D models of the components on their projection in the 2D 
fluoroscopic image.  
 
Statistical analysis of the data will be carried out to analyze the two cohorts. All variables, except 
for lift-off and VAG, will be denoted as continuous. The data will be first checked for normality 
using the Shapiro-Wilk test. Only when the data is found to be normally distributed will 
parametric tests be used; otherwise, non-parametric tests will be used. The data will also be 
tested for equality of variance using the Barlett’s test and Levene’s test. The final selection 
criterion for the type of test to conduct will be based on the check for normality, as well as the 
check for equal variance. Therefore, for all the continuous variables, the following tests will be 
used: 
 
1. 
Student’s t-test (when the data is normally distributed and has equal variance). 
2. 
Welch Anova test (when the data is normally distributed but has unequal variance). 

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3. 
Wilcoxon Mann Whitney U-test (when the data is not normally distributed). 
 
Lift-off, as applicable, will be treated as a categorical variable in this study and a contingency 
analysis using the Fisher’s exact test will be carried out. All statistical tests will be carried out at 
95% confidence level (α=0.05) and will be performed using JMP® Statistical DiscoveryTM 
(SAS Institute Inc., Cary, NC) software. 
   
SPECIFIC RISKS AND PROTECTION MEASURES 
 
1. Fluoroscopic Procedures 
 
As with every clinical study, there may be some risks.  However, doses of radiation exposure 
received will be much lower than those known to produce detectable health effects.  Previously 
reported literature shows that fluoroscopy-based procedure (angiography) on the lower limb 
result in a typical effective dose of 0.83 mSv per min (0.083 rem per min) (Verdun1).  Mettler, et 
al have reported that the typical effective dose for a conventional knee procedure is 0.005 mSv 
(0.0005 rem)2.  According to either estimate, the additional risk of a fluoroscopic procedure 
involving the knee ranges between "Negligible" to "Low" for a 2 minute exam (Verdun).  A 
previous fluoroscopy TKA study conducted at another hospital with a 2 minute on-time limit 
shows that the average effective dose was 0.14 mSv (0.0014 rem) with a maximum dose of 0.27 
mSv (0.027 rem).  The additional risk for all subjects in this previous study would be considered 
"Negligible".  To account for patient variability and differences in imagining techniques, all 
subjects enrolled in this study will receive less than 2 rem.  2 rem is considered "Low" risk.  It is 
unlikely that anyone in this study will approach the 2 rem limit. Since the fluoroscopy data will 
be collected in one session, there will only be one day in which the participants will be exposed 
to this amount of radiation. 
 
In conclusion, a participant who will be fluoroscoped for less than two minutes will be exposed 
to a maximum amount of only 2.0 rems of radiation. This means that the maximum total 
exposure rate will be less than 2 rems per subject for the entire experiment. The participant's 
knee joint will be fluoroscoped using negligible to low risk levels of radiation according to 
published literature.  
  
The participant has the right to stop the procedure at any time; researchers or the RT can end the 
procedures at any time if they feel the participant is at risk, but the participant can choose to 
remain in the study if s/he feels that there is no risk to her/his surgical procedure or recuperation.  
 
We are estimating a total maximum time of 45 minutes to permit the subject time to complete the 
IC form, ask any questions s/he may have, practice the activities or repeat any activities that 
could not be completed, and collect all necessary fluoroscopy data from each subject.  
 
 
1 Verdun FR, Bochud F, Gundinchet F, Aroua A, Schnyder P, Meuli R. Quality Initiatives Radiation Risk: What 
You Should Know to Tell Your Patient 1. Radiographics 2008 Nov 28(7):1807-16. 
2 Mettler, et al. “Effective Doses in Radiology and Diagnostic Nuclear Medicine.” Radiology 248.1 (2008): 254-263. 
http://radiology.rsna.org/content/248/1/254.full.pdf+html 
 

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2. Participant Confidentiality  
The investigator will ensure patient confidentiality to the extent that is permissible by law is 
maintained throughout the study and after. Complete confidentiality cannot be guaranteed. 
 
Hard Copy 
In compliance with HIPAA regulations, all participants will have their identities withheld from 
all public files. The personnel in the following list will have access to participant PHI for the 
purposes of recruitment or compliance and/or may have contact with patients: 
 
List of Persons Involved in Research affiliated with Covenant Health: 
• Dr. Harold Cates, Study Doctor/Co-PI, Tennessee Orthopaedic Clinics 
• Ms. Jane Smith, Research Director, TOFER 
• Clinical Research Staff 
• Radiation technician(s) will operate the fluoroscopy machine. 
• Institutional Review Board of Covenant Health 
 
List of Persons Involved in Research affiliated with the University of Tennessee: 
• Richard D. Komistek, PI, UT Professor  
• Researchers present during data collection at the University of Tennessee and/or the lead 
graduate student(s) appointed by Dr. Komistek.  
• * Undergraduate student researchers employed by the Center for Musculoskeletal 
Research (CMR) will be involved in analyzing the data after it has been collected, 
transferred to a computer workstation and stored in CMR’s digital data collection. Since 
participant information will be removed and replaced with identifiers (a code that is 
assigned to each individual research subject) before the data is transferred to the secure 
server, it will not be possible for these undergraduate students to be able to identify 
subjects. These student researchers will never have contact with subjects, unless they are 
part of the data collection team. 
• Institutional Review Board of the University of Tennessee 
 
Clinical Observations: 
There are no clinical observations made during this data collection or from the images obtained 
through data collection. There will be no radiology report generated for this procedure conducted 
as a result of this study. Therefore, no RT will review such a report for the procedures, which 
would be the only way such a “significant problem” would be determined. It is not anticipated 
that the imaging collected during this study would potentially provide benefit to specific subjects 
by influencing Cr. Cates’ treatment plan. 
 
BENEFITS 
The potential benefits from this study include, but are not limited to: 
• Better understanding of the joints analyzed with the same technique in the past. 
• Future implant design improvements based on the kinematic findings. 
• New and advanced surgical techniques for TKA based on the results.  

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• There is no intention of any direct benefit to participants of the study accept they will be 
able to see their implant on the video monitor and the fluoroscopic video will be assessed 
by the research team.