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Knee Arthroplasty Performed With Conventional and Customized Instrumentation (CPI)

This study has been completed.
Information provided by (Responsible Party):
Nancy Parks, Anderson Orthopaedic Research Institute Identifier:
First received: May 12, 2010
Last updated: November 25, 2013
Last verified: November 2013

The main purpose of this study is to determine whether the surgical time required for primary total knee arthroplasty is significantly less when performed with Customized Patient Instrumentation (CPI) than with conventional instrumentation. Each case will be recorded by video camera, in order to time the length of surgery and each surgical step. The number of surgical trays required for each case will be recorded. As an additional endpoint, the investigators will measure limb and component alignment on x-rays to determine if these two methods achieve equivalent alignment results. The thickness of bone cuts will be compared to the surgical plan and to each other.

The primary hypothesis is that the use of customized patient instrumentation will reduce the operative time required for total knee arthroplasty.

Condition Intervention Phase
Knee Arthritis Device: Customized Patient Instrumentation Device: Traditional Instrumentation Phase 4

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: A Prospective, Randomized Evaluation of Total Knee Arthroplasty Performed With Conventional and Customized Patient Instrumentation

Resource links provided by NLM:

Further study details as provided by Nancy Parks, Anderson Orthopaedic Research Institute:

Primary Outcome Measures:
  • Length of Surgery [ Time Frame: 1 day ]
    Time elapsed from skin incision to wound closure (in seconds)

Secondary Outcome Measures:
  • Length of Each Surgical Step (in Seconds) [ Time Frame: 1 day ]
    surgical exposure, tibial alignment and resection, femoral distal cut, extension gap balancing, sizing the femur, 4 finishing femoral cuts, posterior releases, patellar resection, trial components, tibial tray preparation, cleanup/ prep for cement, cementing femur, cementing tibia, cementing patella, and closure

  • Number of Instrument Trays Required [ Time Frame: 1 day ]
  • Limb Alignment (Mechanical Axis) [ Time Frame: 4 months ]
    Alignment is measured on 4 month postoperative radiograph in degrees. The goal is a mechanical axis between and femur and tibia of 0 degrees. Varus alignment ("bow-legged") is shown as a negative number in degrees away from 0. Valgus alignment ("Knock-kneed") is expressed as a positive number in degrees away from 0.

Enrollment: 70
Study Start Date: May 2010
Study Completion Date: November 2012
Primary Completion Date: July 2012 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: Traditional Instrumentation
Control group: Cases performed with traditional surgical instruments
Device: Traditional Instrumentation
Traditional surgical instruments will be used to make bone cuts and size the components in this control group.
Experimental: Customized Patient Instrumentation
Experimental group: Cases performed with custom instruments specifically made for each patient using pre-op CT scans.
Device: Customized Patient Instrumentation
Custom cutting guides based on computed tomography (CT) images of the patient's leg are used to make the bone cuts and select the implant size.

Detailed Description:

Patient-specific instrumentation (PSI) has been developed for total knee arthroplasty (TKA) with several potential advantages over traditional instrumentation (TI). Shortened surgical time, fewer surgical instruments, and improved alignment are some of these proposed advantages. We sought to examine these assertions.

52 patients (26 per group) were enrolled in a prospective, randomized trial comparing CT-based PSI with TI. No difference was seen in average patient age (68 years) or BMI (31) between groups (p=0.84 and p=0.89), although there were more males in the PSI group (14 vs 7, p=0.002). A single surgeon and consistent staff performed the surgeries with the same knee prostheses, and all cases were videotaped to measure the length of surgery and each individual step. Any additional bone cuts, size changes, or ligament releases made to achieve correct alignment and balance were documented. The number of instrument trays opened for each case was recorded. Postoperative long alignment and lateral radiographs were taken to measure the coronal and sagittal plane component alignment and mechanical axis in each patient.


Ages Eligible for Study:   Child, Adult, Senior
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Patient requires unilateral primary total knee arthroplasty

Exclusion Criteria:

  • Body mass index greater than 41
  • Previous ipsilateral hip or ankle replacement
  • Knee flexion contracture greater than 20 degrees
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT01124305

United States, Virginia
Anderson Orthopaedic Research Institute
Alexandria, Virginia, United States, 22306
Sponsors and Collaborators
Anderson Orthopaedic Research Institute
Principal Investigator: William G Hamilton, MD Anderson Orthopaedic Research Institute
  More Information

Responsible Party: Nancy Parks, Knee Project Director, Anderson Orthopaedic Research Institute Identifier: NCT01124305     History of Changes
Other Study ID Numbers: AORI2010-0101
Study First Received: May 12, 2010
Results First Received: October 18, 2012
Last Updated: November 25, 2013

Keywords provided by Nancy Parks, Anderson Orthopaedic Research Institute:
Total Knee Arthroplasty
Instrumentation processed this record on September 19, 2017