Mechanical Alignment vs Kalipered Kinematic Alignment Total Knee Arthroplasty

A Prospective, Randomized, Single-blinded Clinical Trial Comparing Mechanical Alignment vs Kalipered Kinematic Alignment Total Knee Arthroplasty Using Medacta Spherika

Knee replacement surgery can be performed in one of two ways. Traditionally the goal was for the new joint to be in a neutral position with respect to the femur (thigh bone). This is called Mechanical Alignment (MA). The neutral position is different than the human knee's natural position, so MA often requires the surgeon to make additional cuts to the ligaments and other soft tissue around the knee. More recently surgeons have started to place the new joint in a position that more closely replicates the natural alignment of the human knee. This is called Kinemetic Alignment (KA). KA can be done without additional soft tissue dissection but the procedure requires a higher level of precision that can be difficult to achieve in every case.

Some studies have found no difference in outcomes between MA and KA, whereas others have found KA to be superior. But these were small studies or studies that did not consider patient-rated outcomes.

Study Overview

• Status: Recruiting
• Conditions: Knee Osteoarthritis; Knee Arthropathy
• Intervention / Treatment: Procedure: Mechanical Alignment (MA); Procedure: Kinematic Alignment (KA) Interventions:

Detailed Description

Up to 20% of patients that report dissatisfaction and chronic pain following Total knee arthroplasty (TKA). Prior research has identified patient demographic, comorbidity, and expectations as factors that are associated with dissatisfaction. Emerging literature has also suggested that surgical factors including component alignment, soft tissue balance, and kinematics may play a role in patient satisfaction, and that modifications to alignment may result in better function than performing soft tissue releases. Personalized alignment strategies have been proposed that aim to more closely recreate native knee morphology and kinematics. Kinematic alignment (KA) describes a technique that aims to restore the pre-arthritic joint surfaces and alignment of the femur and tibia by removing the bone and cartilage thickness that will be replaced by the implant, taking into account cartilage wear. KA can therefore be conceptualized as a resurfacing procedure, wherein native joint surfaces are replaced by prosthetic surfaces but the position and alignment of the joint surfaces are not changed. This contrasts with mechanical alignment (MA), in which implants are positioned perpendicular to the mechanical axes of the femur and tibia in a manner independent of the pre-arthritic joint surfaces, and soft tissue releases are performed to bring limb alignment into mechanical neutral.

There have been prior randomized trials comparing kinematic and mechanical alignment, and these have had mixed results regarding the superiority of one approach over the other. The majority of these trials did not use the same operative modality for both groups (manual vs computer-assisted techniques) or did not include relevant patient reported outcomes (PROs). There is a need for a prospective, randomized trial comparing outcomes following kinematic vs mechanical alignment TKA, with the same operative modality used in both groups with inclusion of relevant PROs.

• Study Type: Interventional
• Enrollment (Estimated): 95
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Melissa Shauver, MPH; Phone Number: 312-472-6024; Email: melissa.shauver@northwestern.edu
• Study Contact Backup: Name: Megan VanDyke, BSN; Phone Number: 312-472-3445; Email: megan.vandyke@nm.org

Study Locations

• United States
  • Illinois
    • Chicago, Illinois, United States, 60611
      • Recruiting
      • Northwestern Medicine
      • Contact: Melissa Shauver, MPH; Phone Number: 312-472-6024; Email: melissa.shauver@northwestern.edu
      • Contact: Megan VanDyke, BSN; Phone Number: 312-472-3445; Email: megan.vandyke@nm.org

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patient undergoing primary TKA with a medially-stabilized SpheriKA knee system
• Able to read and understand consent form and PRO instruments and willing to return for follow up visits

Exclusion Criteria:

• Varus or Valgus malalignment >15 degrees to mechanical axis
• Flexion contracture >15 degrees or flexion <90 degrees
• BMI >40
• Revision TKA or other prior knee surgery other than arthroscopy or arthroscopic-assisted ligament reconstruction

• Diagnosis or history of any of the following

  • inflammatory arthritis
  • infection in study knee
  • chronic pain
  • chronic opioid use
  • metabolic musculoskeletal disorder other than osteopenia/osteoporosis
• Patients receiving workers' compensation for study condition
• Patients who cannot complete questionnaires in English
• Patients with comorbidities preventing surgery
• Patients who are not able to provide informed consent

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Mechanical Alignment (MA); Primary TKA with the Medacta SpheriKA, utilizing either MA methodology.	Procedure: Mechanical Alignment (MA); Primary TKA with the Medacta SpheriKA, utilizing either MA methodology.
Active Comparator: Kinematic Alignment (KA); Primary TKA with the Medacta SpheriKA, utilizing either KA methodology.	Procedure: Kinematic Alignment (KA) Interventions: Primary TKA with the Medacta SpheriKA, utilizing either KA methodology.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
6-week Knee Injury and Osteoarthritis - Joint Replacement Score (KOOS-JR)	The Knee Injury and Osteoarthritis Score - Joint Replacement (KOOS-JR) score; range: 0 (worst knee health) - 100 (perfect knee health)	6 weeks postoperative

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Forgotten Joint Score (FJS)	Forgotten Joint Score (FJS) questionnaire score; range: 0 (worst outcome) - 100 (best outcome)	1 year postoperative

Collaborators and Investigators

• Sponsor: Northwestern University
• Collaborators: Medacta International SA
• Investigators: Principal Investigator: Adam Edelstein, MD, Assistant Professor of Orthopaedic Surgery

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2024
• Primary Completion (Estimated): July 1, 2028
• Study Completion (Estimated): December 1, 2028

Study Registration Dates

• First Submitted: September 25, 2024
• First Submitted That Met QC Criteria: September 25, 2024
• First Posted (Actual): October 1, 2024

Study Record Updates

• Last Update Posted (Actual): March 24, 2026
• Last Update Submitted That Met QC Criteria: March 20, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: randomized trial; knee arthroplasty
• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Arthritis; Joint Diseases; Rheumatic Diseases; Osteoarthritis; Osteoarthritis, Knee; Investigative Techniques; Methods
• Other Study ID Numbers: STU00219231

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Aggregate data will be shared via ClinicalTrials.gov
• IPD Sharing Time Frame: Supporting information will be available after all manuscripts have been published.
• IPD Sharing Access Criteria: Contact study PI
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: Yes