Establish Implant Accuracy With X-PSI Knee System - A Multi-center, Prospective, Non-controlled Post Market Study
Phase: NA
Conditions: Knee Osteoarthritis, Post-traumatic Osteoarthritis
Sponsor: Zimmer, GmbH

 
 
 CLINICAL INVESTIGATION PLAN 
CIP ID: CSE2017-01K 
 
Establish implant accuracy with X-PSI Knee 
System 
 
A multi-center, prospective, non-controlled post market study 
 
 
Revision 02 
08.12.2017 
 
 
 
 
 
 
 
 
 
STUDY SPONSOR 
 
Zimmer GmbH 
Sulzerallee 8 
P.O. Box 
CH-8404 Winterthur 
Switzerland 
Tel. +41 58 854 80 00 
 
 
 
 
 

 
 
 
1 Synopsis 
Title:
Establish implant accuracy with X-PSI Knee System–   
A multi-center, prospective, non-controlled post market 
study 
Sponsor:
Manufacturer:
Zimmer GmbH  
Zimmer CAS 
Objectives:
The main purpose of this study is to evaluate the accuracy 
of the new X-PSI Knee System. This will be achieved by 
analyzing early postoperative imaging data with regards to 
the 
mechanical 
alignment 
and 
compare 
them 
with 
preoperative planning imaging data (reviewed and approved 
by the surgeon). 
Hypothesis:
The use of the new X-PSI Knee System achieves the same 
accuracy with respect to mechanical alignment as with 
conventional instrumentation.   
Endpoints:
Primary endpoint: Achievement of mechanical leg alignment 
in HKA frontal plane (± 3 degrees) with X-PSI Knee System 
is as accurate as with standard instrumentation at 4-6 weeks 
post operation. The X-PSI Knee System cohort will be 
compared with current literature (70% of cases within ± 3 
degrees). No control group will be studied.  
Secondary endpoint: Cost-effectiveness as assessed by OR 
set-up time, surgery time and post-processing time.  
Indication/  
Target Population:
Patients which are treated either with Persona, Vanguard or 
NexGen total knee system 
Inclusion Criteria: • Patient is 18 years of age or older. 
• Patient can follow the X-PSI Knee System imaging pro-
tocol as part of standard of care procedures. 
• Patient gets TKA treatment which follows the criteria of 
the appropriate Instruction for Use. 
• Patient is willing and able to cooperate in the required 
post-operative standard of care. 
• Patient is willing and able to complete scheduled follow-
up evaluations as described in the Informed Consent. 
• 
Patient has participated in the study-related Informed 

 
 
Consent process and has signed the Ethics Committee 
approved ‘Informed Consent’. 
Exclusion Criteria
• Patient is unwilling or unable to give consent or to com-
ply with the follow-up program.  
• Patient meets exclusion criteria of the appropriate In-
struction for Use 
• Patients who have any condition which would in the 
judgement of the Investigator place the patient at undue 
risk or interfere with the study. Any patient who is institu-
tionalized, or is a known drug abuser, a known alcoholic 
or anyone who cannot understand what is required from 
them 
• 
Patient is known to be pregnant 
Study Design:
Multi-centre, prospective, non-controlled 
Clinical Phase:
Post market 
Number of Subjects:
Data will be collected from 70 TKA cases implanted by use 
of the X-PSI Knee System in up to 5 study centers 
Length of Study:
1.5 years (0.5 year enrolment plus 1 year follow-up): follow-
up visits at 4-6 weeks and 1 year post-operatively. 
 
Study Device:
X-PSI Knee System 
Scores:
VAS (pain), EQ-5D, Oxford Knee Score  
Documentation:
Electronic Data Capture, Oracle 
 
2 Statistical Considerations/ Evaluation 
2.1 Handling of Missing and Incomplete Data 
Data will be considered “missing” for the primary endpoint if this outcome cannot be 
determined or is unavailable for a subject.  Every effort will be made to collect the data 
necessary to evaluate the primary endpoint.  Patients who have been lost to follow-up and 
do not have mechanical leg alignment in HKA frontal plane data at 4-6 weeks will not be 
included in the primary study analysis. 

 
 
Sensitivity analyses will be performed to assess the impact of missing data on the primary 
study analysis.  These analyses may include a best-case and worst-case imputation as 
well as a tipping point analysis. 
 
2.2 Data Analysis 
Data will be analyzed using SAS 9.4 or higher.  The Type I error rate for the primary study 
analysis will be 0.05.  Comparisons for secondary, exploratory, and safety analyses will be 
two-sided comparisons using α = 0.05, with no adjustment for multiple comparisons.   
  
Primary Analysis:  The primary analysis will be conducted on the as-treated data set. In 
the as-treated-analysis for the primary endpoint, missing data will be treated as described 
in Section 1.1. 
 
The primary endpoint is to show achievement of mechanical leg alignment in HKA frontal 
plane (± 3 degrees) with X-PSI Knee System is as accurate as with standard 
instrumentation at 4-6 weeks post operation. The X-PSI Knee System cohort will be 
compared with current literature (70% of cases within ± 3 degrees). 
 
To determine the upper and lower limits with 95% confidence that 70% of the X-PSI 
patients’ HKA frontal plane measurements are contained, a 70% tolerance interval will be 
constructed based on the mean and standard deviation of the HKA frontal plane 
measurements from patients in the study.  A tolerance interval is defined as “a statistical 
interval within which, with some confidence level, a specified proportion of a sampled 
population falls”.  In this study, we will claim with 95% confidence that 70% of the X-PSI 
patients fall within a computed tolerance interval.  This method allows us to state an upper 
and lower limit in which we can claim 70% of the alignments will fall within with a given 
confidence (95%).   
 
The upper and lower tolerance limits are defined as 
 
 
YL =  – K*s; YU =  + K*s; 
 
where YL and YU are the lower and upper tolerance limits respectively,  is the sample 
mean, s is the sample standard deviation and k is defined as 
 

 
 
 
K = 
 	

(	)/

	,

 
 
where p is the percentage (proportion) of the population we want to claim within the 
interval, ,

 is the critical value of the chi-square distribution with degrees of freedom v 
that is exceeded with probability y, and z(1-p) /2 is the critical value of the normal 
distribution associated with cumulative probability (1-p)/2. 
 
For this study, p = 0.7 (70%), and y = 0.95 (95%).  The study will be considered a success 
if both the upper and lower tolerance limits are within +/- 3 degrees. 
 
Secondary Analysis:  Analyses for secondary endpoints will be conducted on the as-
treated data set, and will only use those cases with complete data for the endpoint being 
analysed. 
  
Continuous data (e.g. age, BMI, VAS pain) will be reported using mean, standard 
deviation, median, and range.  Categorical data (e.g. gender) will be reported using 
frequency and percentage. 
   
2.3 Sample Size 
Based on preliminary U.S. IDE data, we estimate the standard deviation to be 1.62.  
Based on the above formula for calculating tolerance intervals, a sample size of 60 will 
allow us to claim that 70% of the alignments fall within +/- 2 degrees.  The sample size 
formula plans for +/- 2 degrees to account for the initial IDE data showing the average 
offset is about -1 degrees and our goal sit to show that 70% or more are within +/- 3 
degrees.  To account for loss to follow up and patient dropouts, enrolling 70 patients 
includes a 10% loss to follow-up to ensure there are 60 patients at the end of the study. 
 
2.4 Study Report 
The primary analysis will be performed after all patients reach the 4-6 weeks follow up 
time point.  Data will be analysed using the methods described in Section 1.2.