A Double-blinded, Randomized, Controlled Trial of Total Knee Replacement Using Custom Cutting Block Instrument vs Regular Instrumentation
Phase: NA
Conditions: Osteoarthritis, Knee
Sponsor: Orthopaedic Innovation Centre

 
 
 
 
 
 
 
 
A Double-blinded, Randomized, Controlled Trial of Total 
Knee Replacement Surgery Using Custom Cutting Block 
Instrumentation versus Regular Instrumentation 
 
NCT03416946 
 
 
Version submitted 13 June 2011 
 
 
Dr. Thomas Turgeon BSc MD MPH FRCSC 
 
Assistant Professor, Section of Orthopedics 
University of Manitoba 
Concordia Hip and Knee Institute 
Suite 310, 1155 Concordia Ave. 
Winnipeg, MB 
R2K 2M9 
(204) 926-1230 
tturgeon@cjrg.ca 
 
 
Co-Investigators 
 
Dr. David Hedden 
Dr. Colin Burnell 
Dr. Eric Bohm

Introduction & Background 
Total knee replacement (TKR) is a common operation used for the treatment of 
knee arthritis.  Its effectiveness relieving pain and improving function has been well 
documented[1, 2]. While the majority of knee replacements last 10-15 years {Lidgren, 
2004 #334}, some do not [3] leading to early revision and poorer function [1];Lidgren, 
2004 #334}.  One of the main determinants of knee implant survivorship and function is 
adequate correction of limb alignment and proper component placement at time of 
surgery [4-7].  Traditional surgical instrumentation for knee replacement surgery has 
relied on the intramedullary canal of the femur and tibia, or on external landmarks such 
as the ankle, tibial tubercle, symphysis pubis and anterior iliac crest for positioning of the 
bone cutting guides.  The bony cuts made with these guides ultimately determine the 
amount of correction of leg alignment and the position of the knee replacement 
components.  Unfortunately, these instruments are imperfect, and malalignment of the leg 
and components can occur in the hands of even the most skilled surgeon [8, 9]. 
 
In an effort to address this problem, a variety of technologies have been 
developed to assist with positioning of the cutting blocks and balancing of knee 
ligaments.  One of the newest technologies uses magnetic resonance imaging to create a 
three-dimentional computer model of the cartilage and bone of a disease knee. A 3-foot 
standing radiograph determines the mechanical alignment of the limb.  The data from 
these two imaging modalities is combined to determine the ideal position for cutting both 
the tibia and the femur.  The computer model and proposed cut locations are then 
forwarded in electronic file format for adjustment and approval by the treating surgeon.  
Because of the varying anatomy of each patient coupled with the unique nature of each 
patient’s osteophyte pattern, patient-specific cutting blocks can then be rapidly 
manufactured.  These cutting blocks sit on the patient’s unique anatomical landmarks and 
position the bone cuts in the optimal locations based on the pre-operative imaging.  The 
cutting blocks are held in place with traditional pins.  In the case of an intra-operative 
discrepancy, the pins can be left in place with the cutting blocks removed and traditional 
instruments can be used to complete the procedure. 
 
Custom-cutting blocks are touted to have several advantages over traditional 
instrumentation.  With bone cuts being determined by pre-operative imaging, the 
alignment can be customized to the individual patients.  Also, errors in alignment 
stemming from the intra- and extra-medullary alignment rods are removed.  The 
preservation of the femoral and tibial canals may reduce blood loss in the perioperative 
period and reduce post-operative hemarthrosis and pain, thereby improving mobility and 
potentially leading to earlier discharge from hospital.  One of the limitations of this new 
technology is additional cost.  The cutting blocks themselves cost $500 per patient.  This 
is in addition to the cost of the MRI for pre-operative planning.  While these costs are 
significant, if clinical outcome can be improved by either reduced length of stay or 
avoidance of mal-alignment by 3 degrees, then the cost would be mitigated immediately 
(in the case of length of stay) or in the long-term (based on reduced need for revision).  
While several companies currently are under taking similar studies with competitive 
products, each technique differs from the others and need to be assessed independently. 
   

The purpose of this study is to compare the outcomes between traditional and 
patients-specific custom cutting blocks using the Smith and Nephew Visionaire system. 
 
 
Study Objective 
 
Primary objective: To determine if the use of patient-specific custom cutting blocks for 
implantation of total knee components results in improved limb 
alignment and component positioning compared to regular 
instrumentation. 
 
Secondary objectives: To determine if the use of patient-specific custom cutting blocks 
for implantation of total knee components results in improved knee 
function as measured by the EuroQol questionnaire, Oxford 12 
Knee questionnaire, Pain Catastrophizing Scale, Knee 
Replacement Expectations Survey, visual analogue scales (VAS) 
for pain and satisfaction, and the UCLA Activity Level Scale. 
 
Methods 
Study design 
  This is a randomized controlled trial.  Patients will be randomized to have their knee 
implanted using either the patient-specific custom cutting blocks or the regular 
instrumentation system.  Functional and radiographic outcomes will be assessed in a 
blinded fashion.  The Smith and Nephew Legion Primary® total knee system will be 
used in both groups; this is an implant with a good long term track record based on the 
GII design {Lidgren, 2004 #334}.  The four surgeons participating in this study are Drs 
Turgeon, Hedden, Burnell and Bohm; together they form the Concordia Joint 
Replacement Group.  All surgeons have used and are familiar with the regular 
instrumentation.  They will be instructed in the use of the patient-specific custom cutting 
blocks prior to study initiation.  Outcome measures include post operative limb and 
component alignment, as well as knee functional scores. 
Subjects 
Inclusion Criteria: 
1) All patients from the Concordia Joint Replacement Group (CJRG) booked for 
primary total knee replacement surgery who had agreed to be contacted 
regarding participation in research.  Subjects will be contacted approximately 
3-5 months prior to their surgical date to invite them to participate.  This will 
provide adequate time for MRI imaging and production of the custom cutting 
blocks.   
 
Exclusion Criteria: 
1) Deformity of the femur preventing use of the intra-medullary guide utilized in 
the regular instrumentation set. 

2) Necessity for the use of constrained implants.  These types of implants have 
intra-medullary stems, therefore all bone cuts need to be referenced off 
intramedullary guides, making image guided bone cuts inappropriate. 
3) Patients undergoing knee replacement revision surgery.  Theses types of 
implants also have stems, making the use of image guided bone cuts 
inappropriate for the same reasons. 
4) Patients scheduled for bilateral knee surgery (simultaneous or staged) 
Procedure 
Recruitment:   
Potential participants will be identified by our group’s research staff from the 
surgical booking list kept by the Concordia Replacement Group.  Permission to review 
their medical chart for purposes of research and to contact them regarding participation in 
research will have been obtained using the group’s database consent form (HREB 
approval H2003:004).   
 
Research staff will contact potential participants by telephone approximately 3-5 
months before their surgical date to explain the study and ask if they would like to 
participate.  If they agree, they will be sent a cover letter, two copies of the study consent 
form, and copies of the clinical outcome scores to complete.  They will be asked to sign 
the consent form (if no questions) and complete the questionnaires before meeting with 
study staff  at the pre-anesthetic clinic, who will collate the forms and answer any further 
questions.   
 
Randomization: 
 
Randomization will occur after enrolment and subjects will be blinded to 
assignment group.  All subjects will be scheduled for and receive the same MRI 
experience.  It is not possible to blind the surgeon to the surgical technique.  The block 
randomization process will be stratified by surgeon to ensure equal distribution between 
the two surgical techniques. 
 
Surgery: 
 
Anesthetic and surgical technique will be identical for both groups, and will only 
differ in type of instrumentation used.  Patients are normally given an spinal anaesthetic 
for intra-operative anesthesia.  Patients are placed supine with a 5L saline bag beneath the 
buttock on the operated side and a tourniquet around the thigh.  After appropriate 
prepping and draping, the tourniquet is inflated and a midline skin incision is used, 
followed by a medial para-patellar arthrotomy.  This allows access to the joint for bone 
cuts using the appropriate instrumentation, soft tissue balancing, and component 
implantation.  To reduce the incidence of infection, all patients are given 1 pre-op and 3 
post-op doses of cephazolin or vancomycin (if penicillin allergic), and body exhaust suits 
are used by all surgical staff in the operating room.  As per our group’s normal routine, 
AP and lateral x-rays of the knee are performed in the recovery room to assess for any 
undetected intra-operative complications (fracture or gross component malposition).  
These are not the x-rays used for formal assessment of component position – these are 
done at the 6 month office follow up visit. 

 
Hospital care: 
Patient in-hospital care and rehabilitation is standardized using our group’s total 
knee replacement care map. Deep venous prophylaxis consists of sequential compression 
devices for 24 hours with elastic stockings while in hospital and rivaroxaban for a 
minimum of 2 weeks post-surgery.  Analgesia is obtained oral narcotics and 
acetaminophen with patient-controlled intravenous analgesia used when necessary.  
 
Follow up: 
 
All patients will follow our group’s pre-existing routine follow-up schedule: a 
fracture clinic visit 2 weeks post-op for surgical staple removal and wound check, a 8 
week office visit for clinical, radiological examination and completion of the clinical 
outcome questionnaires, a 6 month post-op office visit for clinical & radiographic 
examination and completion of the clinical outcome questionnaires, followed by yearly 
visits for clinical & radiographic examination and completion outcome questionnaires.  
For the purposes of this study, data will be gathered until subjects reach two years from 
surgery. 
 
 
The only change from our normal clinical follow-up will be at the 8 weeks 
follow-up radiological examination.  A 3 foot standing AP x-ray of the leg will be 
substituted for the routine AP x-ray of the knee, and a 3 foot lateral x-ray of the leg will 
be substituted for the lateral knee x-ray.  These modified views increase x-rays exposure 
minimally, while providing proper standardized films for assessment of limb alignment 
and component alignment {Hewitt, 2001 #206;Jeffery, 1991 #210}.   
 
Special Sub-group follow up: 
15 patients from each arm of the study (30 patients in total) will be asked to 
participate in a CT scan sub-group to assess component rotation.  While standardized 
plain x-rays are good for assessing component alignment in the coronal and saggital 
planes, CT scans are required to assess component rotation relative to the long axes of the 
femur and tibia {Jazrawi, 2000 #209;Berger, 1998 #196}.  To minimize time 
commitment from patients, a single CT scan will be undertaken during the hospital stay 
using a standardized technique {Berger, 1998 #196}.  This CT scan is in addition to the 
plain x-rays as previously described.  This sample size of 30 patients was chosen based 
upon previously published work {Berger, 1998 #196}.   
 
Data storage 
 
Data for this study will be stored in the Concordia Joint Replacement Group’s 
PHIA compliant database (HREB approval H2003:004).  Data will be exported to SAS 
statistical analysis software in a de-identified fashion for statistical analysis. 
Outcome Measures 
Primary outcome measures: 
1. Leg alignment  
a. Frontal limb alignment as measured on the 3 foot standing film 
(fig.1-A). 

b. Sagittal limb alignment as measured on the 3 foot lateral film 
(fig.1-D & E). 
2. Femoral component position 
a. Varus/valgus alignment relative to mechanical axis of femur as 
measured on the 3 foot AP film (fig.1-A). 
b. Flexion/extension alignment relative to mechanical axis of femur 
as measured on the 3 foot lateral film (fig.1-D). 
c. Rotation relative to epicondylar axis as measured by CT scan  
3. Tibial component position 
a. Varus/valgus alignment relative to mechanical axis of tibia as 
measured on the 3 foot AP film (fig.1-C). 
b. Amount of posterior slope as measured on the 3 foot lateral film 
(fig.1-E). 
c. Rotation relative to tibial tubercle as measured by CT scan 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 1 - Limb Alignment 
 
 
 

 
Secondary outcome measures: 
1. EuroQol score at 1 and 2 years 
2. Oxford 12 score at 1 and 2 years 
3. Pain Catastrophizing Scale score at 1 and 2 years 
4. Knee Replacement Expectations score at 1 and 2 years 
5. Visual analogue scales (VAS) for pain and satisfaction at 1 and 2 years 
6. UCLA Activity Level score at 1 and 2 years. 
 
Miscellaneous measures: 
1. Surgical and tourniquet time 
2. Number of instrument pans used 
3. Length of hospital stay 
4. Peri-operative complications such as deep venous thrombosis, 
pulmonary emboli, wound complications and cardiac events.   
Sample Size 
This trial is powered to detect a difference in post-operative frontal limb alignment 
between the two groups.  The CJRG have recently had a computer navigation study 
accepted for publication assessing alignment with the same protocol as outlined in the 
study.  The standard deviation for frontal plane alignment in the traditional 
instrumentation group was 3.1 degrees.  Previous studies have indicated increased risk of 
early revision with alignment more than 3 degrees from the mechanical axis{Ritter, 1994 
#334}.   Assuming p=0.05 and power of 95%, a sample size of 29 per arm is required.  
Allowing for 20% drop-out requires 35 subjects per arm total. 
  
Study End Points 
The study will end when all enrolled patients are followed out clinically and 
radiographically to two years.  No interim analysis is planned, as this would adversely 
affect significance testing.  The surgeons involved in this study follow their patients 
closely in the post-operative period; any unforeseen significant complications arising 
from using the patient-specific custom cutting blocks that cannot be resolved would 
prompt cessation of the trial.  This process is facilitated by the Concordia Joint 
Replacement Group’s weekly planning & post-operative x-ray review rounds. 
 
 
Analysis 
Data for this study will be stored in the Concordia Joint Replacement Group’s PHIA 
compliant database (HREB approval H2003:004).  Data will be exported to SAS 
statistical analysis software in a de-identified fashion for statistical analysis.  The two 
groups will be compared to assess the adequacy of randomization, relevant data will be 
assessed for normalcy, and the appropriate parametric and non-parametric tests will be 
used for comparing means and proportions between the two groups.  Multiple regression 
analysis will be used to look for other factors that may affect post operative limb 
alignment and component position. 

 
Dissemination 
The results of this study will be submitted to peer reviewed journals and presented at 
orthopedic conferences. 
  
Budget 
There is no set budget for this study.  The 35 patient-specific custom cutting blocks 
required for this study will be provided free-of-charge by Smith and Nephew Canada.  
The MRI imaging required for this study will be provided by Dr. Michael Davidson at the 
Pam Am clinic.  Clinical research will be performed using existing funding from the 
research accounts of the Concordia Joint Replacement Group. 
 
Table 1.  Data Collection Summary 
 
 
Preop 
Intra-
operative 
8 weeks 
(1week) 
6 months 
(2weeks) 
12 months 
(1month) 
24 months 
(2months) 
Leg Alignment 
 
 
 
 
 
 
Questionnaires & 
Functional 
Assessment 
 
 
 
 
 
 
Surgical variables 
 
 
 
 
 
 
CT Scan 
 
* 
 
 
 
 
Complication/Adverse 
Event 
 
 
 
 
 
 
* CT Scan will be completed during hospital stay. 
 
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