Zero Degree Knee Positioner for Improved Earley Knee Extension Following Total Knee Arthroplasty

NCT ID: NCT05678231

Last Updated: 2025-08-01

Basic Information

• Recruitment Status: ENROLLING_BY_INVITATION
• Clinical Phase: NA
• Total Enrollment: 154 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2023-02-10
• Study Completion Date: 2025-12-15

Brief Summary

Studies have demonstrated that early rehabilitation interventions following knee arthroplasty (TKA) can shorten the time needed to regain baseline extension/full extension and gait mechanics. As telehealth visits and home-based rehabilitation increases with advancements in technology, much of this rehabilitation is projected to be performed at home. The purpose of this study is to prospectively evaluate early post-operative knee extension and self-reported outcomes in patients using the Zero Degree Knee positioner (ZDK) compared to subjects not using the ZDK. Patients electing to undergo primary TKA will be recruited into the study and randomized to receive and follow the ZDK protocol post-operatively or standard of care rehabilitation instructions. Knee extension measurements will be recorded at 2 weeks post-op and patient-reported outcome measurements will be recorded pre-operatively and at various post-op timepoints.

Detailed Description

Total Knee Arthroplasty (TKA) remains one of the most commonly performed elective surgical procedures in the United States. The number of TKAs performed annually has increased steadily since 2005 and is projected to be more than 3 million procedures annually by 2030. This steady growth may be attributed to the increasing geriatric population which is expected to represent 17% of the world's population by 2050. TKA aims to reduce pain and restore motion from those with knee complications, and with the geriatric population continuing to rise, TKA procedures are projected to grow over the next decade and beyond.

Historically, one of the major concerns following TKA is joint stiffness and subsequent range of motion loss. Range of motion loss, or more specifically, the inability to regain full extension (flexion contracture) have a relatively high occurrence and may lead to gait abnormalities and associated complications of the hips and low back. Early rehabilitation interventions following TKA may shorten the time needed to regain baseline extension/full extension and gait mechanics which not only is this beneficial for patient reported outcomes, but early rehabilitation interventions may reduce the economic burden associated with TKA recovery.

In-home or virtual physical therapy (PT) has also helped offload the economic burden to patients following TKA comparted to traditional in-clinic physical therapy. More importantly, the rise in in-home/virtual PT has not compromised patient outcomes, rather, it has improved them. In-home/virtual PT has reported improvements in total cost of therapy, compliance with unsupervised therapy, and hospital readmission rates.

Patient positioning has always played a vital role in the effectiveness of postoperative therapy. Historically, a continuous passive motion (CPM) machine was the standard for initiating ROM exercises, however, this modality has fallen out of favor due to the inconsistency of patient position and appropriate fitting of the device. The Zero Degree Knee (ZDK) positioning device is a knee extension pillow designed to simplify knee extension exercise following TKA surgery. Following knee surgery, the patient often experiences postoperative surgical pain which may lead to apprehension to physical therapy and engaging knee musculature. This apprehension may lead to joint stiffness and ultimately, ROM loss. The ZDK is a pillow that elevates the lower extremity and allows gravity to pull the knee passively and gently into an extended position. Additionally, the ZDK has a sliding capability that allows a patient to work on knee extension exercises along with knee flexion exercises.

In this study, the investigators aim to prospectively evaluate early post-operative knee extension and self-reported outcomes in patients using the Zero Degree Knee positioner. Patients electing to undergo primary TKA will be recruited into the study and randomized to receive and follow the ZDK protocol post-operatively or standard of care rehabilitation instructions. Knee extension measurements will be recorded at 2 weeks post-op and patient-reported outcome measurements will be recorded pre-operatively and at various post-op timepoints.

Conditions

Osteoarthritis, Knee

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: NONE

Study Groups

Standard of Care

Patients will receive standard of care instructions rehabilitation instructions following total knee replacement.

Group Type: NO_INTERVENTION

No interventions assigned to this group

Zero Degree Knee

Patients will receive the Zero Degree Knee device and instructions for use following total knee replacement.

Group Type: EXPERIMENTAL

Zero Degree Knee Positioner

Intervention Type: DEVICE

The Zero Degree Knee (ZDK) positioning device is a knee extension pillow designed to simplify knee extension exercise following TKA surgery.

Interventions

Zero Degree Knee Positioner

The Zero Degree Knee (ZDK) positioning device is a knee extension pillow designed to simplify knee extension exercise following TKA surgery.

Intervention Type: DEVICE

Eligibility Criteria

Inclusion Criteria

• Men and women between the ages of 40-80 years
• Candidate for total knee arthroplasty
• Diagnosis of mild to advanced osteoarthritis
• The ability to walk independently at baseline

Exclusion Criteria

• History of knee replacement in operative limb (i.e. patients undergoing revision surgery)
• Neuromuscular/skeletal or connective tissue conditions that can alter gait or joint mechanics (joint infection, gout, rheumatoid arthritis)
• Pregnant women
• Prisoners
• Non-English speakers

• Minimum Eligible Age: 40 Years
• Maximum Eligible Age: 80 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Prisma Health-Midlands

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Locations

Prisma Health - Midlands

Columbia, South Carolina, United States

Countries

United States

References

Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am. 2007 Apr;89(4):780-5. doi: 10.2106/JBJS.F.00222.

Reference Type: BACKGROUND

PMID: 17403800 (View on PubMed)

Fortier LM, Rockov ZA, Chen AF, Rajaee SS. Activity Recommendations After Total Hip and Total Knee Arthroplasty. J Bone Joint Surg Am. 2021 Mar 3;103(5):446-455. doi: 10.2106/JBJS.20.00983.

Reference Type: BACKGROUND

PMID: 33337819 (View on PubMed)

Su EP. Fixed flexion deformity and total knee arthroplasty. J Bone Joint Surg Br. 2012 Nov;94(11 Suppl A):112-5. doi: 10.1302/0301-620X.94B11.30512.

Reference Type: BACKGROUND

PMID: 23118396 (View on PubMed)

Prvu Bettger J, Green CL, Holmes DN, Chokshi A, Mather RC 3rd, Hoch BT, de Leon AJ, Aluisio F, Seyler TM, Del Gaizo DJ, Chiavetta J, Webb L, Miller V, Smith JM, Peterson ED. Effects of Virtual Exercise Rehabilitation In-Home Therapy Compared with Traditional Care After Total Knee Arthroplasty: VERITAS, a Randomized Controlled Trial. J Bone Joint Surg Am. 2020 Jan 15;102(2):101-109. doi: 10.2106/JBJS.19.00695.

Reference Type: BACKGROUND

PMID: 31743238 (View on PubMed)

Harvey LA, Brosseau L, Herbert RD. Continuous passive motion following total knee arthroplasty in people with arthritis. Cochrane Database Syst Rev. 2014 Feb 6;2014(2):CD004260. doi: 10.1002/14651858.CD004260.pub3.

Reference Type: BACKGROUND

PMID: 24500904 (View on PubMed)

Other Identifiers

1983229

Identifier Type: -

Identifier Source: org_study_id