Comparison of Knee Kinematics for Subjects Implanted With Either a ConforMIS or Traditional Knee Implant

In Vivo Determination & Comparison of Knee Kinematics for Subjects Implanted With Either a Personalized ConforMIS or Traditional Knee Implant

A better understanding of knee joint kinematics is important to explain the premature polyethylene wear failures within total knee arthroplasties (TKAs) and to help design a prosthesis that most closely approximates the normal knee. Previously, most experimental studies of knee kinematics have involved cadaveric, in vitro analyses, or have not tested the knee in a weight-bearing mode. Others have used exoskeletal linkages and skin markers that permit error due to undesired motions between markers and the underlying bone. More recently, fluoroscopy has been used to assess in vivo kinematics for subjects having a TKA.

ConforMIS has attempted to follow a clearly different path than the major orthopaedic companies. They have chosen to offer patients a personalized knee implant based off of each patient's femoral and tibial bone geometry. The hypothesis is that these subjects will experience a more normal-like kinematic pattern, eliminating paradoxical anterior sliding during weight-bearing knee flexion. Therefore, the objective for this study is to analyze the in vivo kinematics for 25 patients implanted with a personalized ConforMIS TKA and 25 patients implanted with a traditional TKA design to determine if there are any kinematic differences between these TKA designs.

Study Overview

• Status: Completed
• Conditions: Osteoarthritis

Detailed Description

Each subject will be asked to perform five activities in one continuous sequence: (1) stand up from a chair, (2) walk up stairs, (3) walk down stairs, (4) level walking, and (5) a deep knee bend. Subjects will be video recorded from the waist down while performing the activities. The speed level of each trial will be based on the comfort level of the patient. The fluoroscopic images will be stored digitally for subsequent analysis on secure servers and workstations at the University of Tennessee.

• Study Type: Observational
• Enrollment (Actual): 66

Contacts and Locations

Study Locations

• United States
  • Tennessee
    • Knoxville, Tennessee, United States, 37996
      • University of Tennessee
    • Nashville, Tennessee, United States, 37203
      • Tennessee Orthopedic Alliance

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 40 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Patients who are at least 6 month post-op with a ConforMIS knee replacement or a standard total knee replacement who meets the inclusion/exclusion criteria

Description

Inclusion Criteria:

• At least 6 months post-op with no other surgical procedures conducted within the past 6 months
• Between 40-70 years of age
• Body weight of less than 250lbs
• BMI of less than 38
• Pregnant females will be excluded
• TKA patients will be judged Clinically successful with an American Knee Society score of greater than 90
• Must have 100 degrees post-op passive flexion with no ligamentous laxity or pain
• Participants must be able to walk on level ground without aid of any kind and ascend/descend stairs without assistance.
• All potential subjects will have either a personalized ConforMIS™ TKA or a traditional TKA manufactured by an orthopaedic company other than ConforMIS.
• Patients from the physician's list who do not meet the study requirements will not be considered.
• Patients must be willing to sign the Informed Consent and HIPAA forms to participate in the study.
• Patients must be between 160cm (5'3) and 193cm (6'4) tall.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
ConforMIS; Patients with ConforMIS implants
Standard Total Knee Implant; Patients implanted with standard total knee implant

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Post-operative Range of Motion	Comparison of amount of flexion achieved by the knee between the two arms	at least 6 months post-surgery

Collaborators and Investigators

• Sponsor: Restor3D
• Investigators: Principal Investigator: Richard D Komistek, PhD, Univeristy of Tennessee; Principal Investigator: William Kurtz, MD, Tennessee Orthopedic Alliance

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2012
• Primary Completion (Actual): August 1, 2014
• Study Completion (Actual): August 1, 2014

Study Registration Dates

• First Submitted: October 26, 2012
• First Submitted That Met QC Criteria: October 26, 2012
• First Posted (Estimated): October 30, 2012

Study Record Updates

• Last Update Posted (Actual): October 25, 2023
• Last Update Submitted That Met QC Criteria: October 23, 2023
• Last Verified: October 1, 2023

More Information

Terms related to this study

• Keywords: kinematics; knee joint
• Additional Relevant MeSH Terms: Joint Diseases; Musculoskeletal Diseases; Rheumatic Diseases; Arthritis; Osteoarthritis
• Other Study ID Numbers: Komistek 1

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO