Osteoarthritis, KneeNCT05678231
Zero Degree Knee Positioner for Improved Earley Knee Extension Following Total Knee Arthroplasty
A study testing Zero Degree Knee Positioner in people with Osteoarthritis, Knee, run by Prisma Health-Midlands at 1 site in United States.
Trial 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. Read more about this study
- Who is it for?
- Ages 40 to 80 years
- Conditions the study is for
- Osteoarthritis, Knee
- What is being tested?
- Zero Degree Knee Positioner
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 154 participants
- Where
- 1 siteUnited States
- Study dates
- 10 Feb 2023to 31 Dec 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 40 to 80 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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
Who cannot join
- 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
Trial locations and contacts
1 site in 1 country.
United States1 site
Prisma Health - Midlands
Columbia, South Carolina, 29203
About this study
Official title: Use of the Disposable Zero Degree Knee Postoperative Positioner for Improved Early Knee Extension and Self-Reported Outcomes Following Total Knee Arthroplasty
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.
Read the 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
- Being tested
- Zero Degree Knee Positioner
- Keywords
- Knee arthroplasty, Osteoarthritis, Total knee replacement
- Medical subject headings
- Osteoarthritis, Knee, Osteoarthritis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Zero Degree Knee PositionerDevice
The Zero Degree Knee (ZDK) positioning device is a knee extension pillow designed to simplify knee extension exercise following TKA surgery.
| Study group | Role | What they receive |
|---|---|---|
| Standard of Care | No intervention | Patients will receive standard of care instructions rehabilitation instructions following total knee replacement. |
| Zero Degree Knee | Experimental | Patients will receive the Zero Degree Knee device and instructions for use following total knee replacement. Receives: Device: Zero Degree Knee Positioner |
What is being measured
The primary outcome is the main question the study is designed to answer.
Effect of the Zero Degree Knee device on post-operative knee extension in patients at 2 weeks post-op following total knee replacement as measured by lateral radiograph and physician interpretation.
The degree of knee extension at the 2 week post-operative visit will be measured via lateral radiograph interpreted by an orthopedic surgeon.
Measured: 2 weeks
Secondary outcomes (4)
Effect of the Zero Degree Knee device on PROMIS Physical Function scores in patients undergoing total knee replacement surgery.
Patient reported outcomes will be collected utilizing the Patient Reported Outcome Measurement Information Systems (PROMIS) Physical Function assessment tool. Patients receiving either the Zero Degree Knee device or standard of care rehabilitation instructions will complete PROMIS Physical Function assessment at the time of enrollment and at 2 weeks, 4 weeks, and 3 months after surgery. As the PROMIS tool has national normative data for age, sex, and condition, collection of patient-reported outcomes in this manner will allow for comparison between patients receiving the Zero Degree Knee device and standard of care as well as the general population. PROMIS Physical Function scores range from 0 to 100 and an increased PROMIS Physical Function score indicates an improvement in patient-reported physical function.
Measured: 3 months
Effect of the Zero Degree Knee device on PROMIS Pain Interference scores in patients undergoing total knee replacement surgery.
Patient reported outcomes will be collected utilizing the Patient Reported Outcome Measurement Information Systems (PROMIS) Pain Interference assessment tool. Patients receiving either the Zero Degree Knee device or standard of care rehabilitation instructions will complete PROMIS Physical Function assessment at the time of enrollment and at 2 weeks, 4 weeks, and 3 months after surgery. As the PROMIS tool has national normative data for age, sex, and condition, collection of patient-reported outcomes in this manner will allow for comparison between patients receiving the Zero Degree Knee device and standard of care as well as the general population. PROMIS Pain Interference scores range from 0 to 100 and a decreased PROMIS Pain Interference score indicates an improvement in patient-reported pain interference.
Measured: 3 months
Effect of the Zero Degree Knee device on PROMIS Mobility scores in patients undergoing total knee replacement surgery.
Patient reported outcomes will be collected utilizing the Patient Reported Outcome Measurement Information Systems (PROMIS) Mobility assessment tool. Patients receiving either the Zero Degree Knee device or standard of care rehabilitation instructions will complete PROMIS Physical Function assessment at the time of enrollment and at 2 weeks, 4 weeks, and 3 months after surgery. As the PROMIS tool has national normative data for age, sex, and condition, collection of patient-reported outcomes in this manner will allow for comparison between patients receiving the Zero Degree Knee device and standard of care as well as the general population. PROMIS Mobility scores range from 0 to 100 and an increased PROMIS Mobility score indicates an improvement in patient-reported mobility.
Measured: 3 months
Effect of the Zero Degree Knee device on KOOS scores in patients undergoing total knee replacement surgery.
Patient reported outcomes will be collected utilizing the Knee Injury and Osteoarthritis Outcome Score (KOOS) tool. Patients receiving either the Zero Degree Knee device or standard of care rehabilitation instructions will complete the KOOS assessment at the time of enrollment and at 2 weeks, 4 weeks, and 3 months after surgery. The KOOS tool will allow for a comparison of scores of patients receiving the Zero Degree Knee device and standard of care. The maximum score a patient can achieve is 100, which indicates no knee problems. The minimum score a patient can achieve is zero, which indicates severe knee problems.
Measured: 3 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Jan 2023
- Study start10 Feb 2023
- Primary completion10 Feb 2026
- Study completion31 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (5)Papers the sponsor has linked to this study.
- Other trials for Osteoarthritis, KneeStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- 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.
- Masking
- None (open label)
- Enrolment
- 154 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Prisma Health-Midlands
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05678231
- Sponsor's protocol ID
- 1983229
- Status last verified
- Sep 2026
- First submitted
- 13 Dec 2022
- Last updated
- 18 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
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.
PubMed 17403800Fortier 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.
PubMed 33337819Su 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.
PubMed 23118396Prvu 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.
PubMed 31743238Harvey 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.
PubMed 24500904
Study at a glance
From the registry record, last updated by the sponsor on 18 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Use of the Disposable Zero Degree Knee Postoperative Positioner for Improved Early Knee Extension and Self-Reported Outcomes Following Total Knee Arthroplasty
- ClinicalTrials.gov ID
- NCT05678231
- Acronym / sponsor ID
- 1983229
- Conditions
- Osteoarthritis, Knee
- Keywords
- Knee arthroplasty, Osteoarthritis, Total knee replacement
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 154 participants (estimated)
- Lead sponsor
- Prisma Health-MidlandsUniversity, hospital or other
- Study start
- 10 Feb 2023 (actual)
- Primary completion
- 10 Feb 2026 (actual)
- Study completion
- 31 Dec 2026 (estimated)
- First posted
- 10 Jan 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- 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.
| Arm | Type | Receives |
|---|---|---|
| Standard of Care | No intervention | –Patients will receive standard of care instructions rehabilitation instructions following total knee replacement. |
| Zero Degree Knee | Experimental | Device: Zero Degree Knee PositionerPatients will receive the Zero Degree Knee device and instructions for use following total knee replacement. |
Who may qualify
- Ages
- 40 to 80 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- 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
Key exclusion criteria (5 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Zero Degree Knee PositionerThe Zero Degree Knee (ZDK) positioning device is a knee extension pillow designed to simplify knee extension exercise following TKA surgery. | Device | Zero Degree Knee |
Primary outcome
Effect of the Zero Degree Knee device on post-operative knee extension in patients at 2 weeks post-op following total knee replacement as measured by lateral radiograph and physician interpretation.
Time frame: 2 weeks
The degree of knee extension at the 2 week post-operative visit will be measured via lateral radiograph interpreted by an orthopedic surgeon.
4 secondary outcomes
Effect of the Zero Degree Knee device on PROMIS Physical Function scores in patients undergoing total knee replacement surgery.
Time frame: 3 months
Effect of the Zero Degree Knee device on PROMIS Pain Interference scores in patients undergoing total knee replacement surgery.
Time frame: 3 months
Effect of the Zero Degree Knee device on PROMIS Mobility scores in patients undergoing total knee replacement surgery.
Time frame: 3 months
Effect of the Zero Degree Knee device on KOOS scores in patients undergoing total knee replacement surgery.
Time frame: 3 months
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 18 Sep 2026.
- Results publication: PubMed 17403800Kurtz 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.
- Results publication: PubMed 33337819Fortier 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.
- Results publication: PubMed 23118396Su 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.
- Results publication: PubMed 31743238Prvu 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.
- Results publication: PubMed 24500904Harvey 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.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Zero Degree Knee Positioner in people with Osteoarthritis, Knee, run by Prisma Health-Midlands at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 18 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Effect of the Zero Degree Knee device on post-operative knee extension in patients at 2 weeks post-op following total knee replacement as measured by lateral radiograph and physician interpretation. (time frame: 2 weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05678231, which also lists 5 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 18 Sep 2026.