Osteoarthritis, KneeNCT03671213
Calypso Knee System Clinical Study
A study testing Calypso Knee System (Implantable Shock Absorber) in people with Osteoarthritis, Knee, run by Moximed at 5 sites in United States.
Trial summary
A clinical study to evaluate the safety and effectiveness of the Calypso Knee System when used in subjects with symptomatic osteoarthritis of the medial compartment of the knee. Read more about this study
- Who is it for?
- Ages 25 to 65 years
- Conditions the study is for
- Osteoarthritis, Knee
- What is being tested?
- Calypso Knee System (Implantable Shock Absorber)
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 81 participants
- Where
- 5 sitesUnited States
- Study dates
- 19 Sep 2018to 14 Mar 2025
- Phase
- Interventional
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
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 25 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Participants age - 25 to 65 years
- Body Mass Index (BMI) of < 35, Weight < 300 lbs
- Knee osteoarthritis pain on the inner side of knee that has continued after at least 6 months of non-operative treatment
Who cannot join
- Symptoms of osteoarthritis in the other knee or in lateral (outer) or patellofemoral compartments of the target knee
- Knee ligament or meniscal instability
- Other bone or joint conditions such as Rheumatoid arthritis, Paget's disease, Charcot's disease or general conditions such as allergy or hypersensitivity to certain metals, active infection, certain neurological conditions, use of medication such as steroids or chemotherapy that could impact study participation or results
Trial locations and contacts
5 sites in 1 country.
5 sites in 1 country
United States5 sites
University of Virginia
Charlottesville, Virginia, 22903
Missouri Orthopaedic Institute
Columbia, Missouri, 65212
Jameson Crane Sports Medicine Institute
Columbus, Ohio, 43202
Hospital for Special Surgery
New York, New York, 10021
Oregon Health and Science University
Portland, Oregon, 97239
About this study
Official title: Evaluation of the Calypso Knee System for Symptom Relief in Subjects With Medial Knee Osteoarthritis
A clinical study to evaluate the safety and effectiveness of the Calypso Knee System when used in subjects with symptomatic osteoarthritis of the medial compartment of the knee.
Read the detailed description
Prospective, multicenter clinical study of the Calypso Knee System. 81 subjects were enrolled in this study. Male or female subjects age 25 to 65 years, with a diagnosis of medial knee osteoarthritis and study knee pain with an overall WOMAC pain score ≥ 40 (scale 0-100).
The Calypso group was investigated under two clinical protocols, CP0001 in the USA, and CP0002 in Europe. Both clinical protocols followed the same supporting protocols and plans, such as radiographic, statistical, Clinical Events Committee (CEC), etc. The results from the combined analysis have been reported in both NCT03671213 (CP0001) and NCT03838978 (CP0002).
- Conditions
- Osteoarthritis, Knee
- Being tested
- Calypso Knee System (Implantable Shock Absorber)
- Medical subject headings
- Osteoarthritis, Knee
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Calypso Knee System (Implantable Shock Absorber)Device
Also called MISHA® Knee System
The Calypso Knee System is an extra-capsular knee implant designed to fill the therapeutic gap between conservative care and more invasive surgical interventions for knee osteoarthritis.
| Study group | Role | What they receive |
|---|---|---|
| Calypso | Experimental | Calypso Knee System Receives: Device: Calypso Knee System (Implantable Shock Absorber) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Composite Clinical Success (CCS)
A subject is considered a Composite Clinical Success (CCS), at 24 months, if the subject meets all of the following:
- Clinically significant improvement of at least 20% from baseline on the WOMAC pain questions in the KOOS Knee questionnaire with a change of ≥10 points
- Clinically significant improvement of at least 20% from baseline on the WOMAC function questions in the KOOS Knee questionnaire with a change of ≥10 points
- Freedom from the following device-related serious adverse events:
- Deep infection requiring surgical intervention (Both arms)
- Damage to adjacent neurovascular or ligament structures necessitating reconstruction (Both arms)
- Non-union (HTO only)
- Maintenance of implant integrity as evaluated by radiographic assessment
- Endpoint Subsequent Surgical Intervention (SSI)
Measured: From baseline to 24 months
Secondary outcomes (5)
Time to Full Weight Bearing (Days)
Any subject that had evaluable data was deemed eligible for effectiveness evaluation and included in the analysis.
Measured: Through study completion (Number of days to full weight bearing)
WOMAC Pain Percent Change to Month 3
Any subject that had evaluable data, yet had not undergone a conversion to arthroplasty was deemed eligible for effectiveness evaluation and included in the analysis.
The Knee Injury and Osteoarthritis Outcome Score (KOOS) Knee Survey includes the Western Ontario and McMasters University Osteoarthritis Index (WOMAC) in its complete and original format (with permission), and WOMAC scores can be calculated from the KOOS Knee questionnaire. The response to each question is summed and the resultant scores are transformed to a 0-100 scale. A WOMAC score of zero (0) represents no knee problems and one hundred (100) represents extreme knee problems.
Measured: From baseline to 3 months
WOMAC Pain Percent Change to Month 24
Any subject that had evaluable data, yet had not undergone a conversion to arthroplasty was deemed eligible for effectiveness evaluation and included in the analysis.
The Knee Injury and Osteoarthritis Outcome Score (KOOS) Knee Survey includes the Western Ontario and McMasters University Osteoarthritis Index (WOMAC) in its complete and original format (with permission), and WOMAC scores can be calculated from the KOOS Knee questionnaire. The response to each question is summed and the resultant scores are transformed to a 0-100 scale. A WOMAC score of zero (0) represents no knee problems and one hundred (100) represents extreme knee problems.
Measured: From baseline to 24 months
WOMAC Function Percent Change to Month 3
Any subject that had evaluable data, yet had not undergone a conversion to arthroplasty was deemed eligible for effectiveness evaluation and included in the analysis.
The Knee Injury and Osteoarthritis Outcome Score (KOOS) Knee Survey includes the Western Ontario and McMasters University Osteoarthritis Index (WOMAC) in its complete and original format (with permission), and WOMAC scores can be calculated from the KOOS Knee questionnaire. The response to each question is summed and the resultant scores are transformed to a 0-100 scale. A WOMAC score of zero (0) represents no knee problems and one hundred (100) represents extreme knee problems.
Measured: From baseline to 3 months
WOMAC Function Percent Change to Month 24
Any subject that had evaluable data, yet had not undergone a conversion to arthroplasty was deemed eligible for effectiveness evaluation and included in the analysis.
The Knee Injury and Osteoarthritis Outcome Score (KOOS) Knee Survey includes the Western Ontario and McMasters University Osteoarthritis Index (WOMAC) in its complete and original format (with permission), and WOMAC scores can be calculated from the KOOS Knee questionnaire. The response to each question is summed and the resultant scores are transformed to a 0-100 scale. A WOMAC score of zero (0) represents no knee problems and one hundred (100) represents extreme knee problems.
Measured: From baseline to 24 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Sep 2018
- Study start19 Sep 2018
- Primary completion17 Jan 2022
- Study completion14 Mar 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (2)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
- Not applicable
- Intervention model
- Single group
- Model description
- Single Arm Study Design
- Masking
- None (open label)
- Enrolment
- 81 participants (actual)
Sponsor and investigators
- Lead sponsor
- Moximed
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- David Flanigan, MD, Principal investigator, Ohio State University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03671213
- Sponsor's protocol ID
- CP0001 (formerly CLIN102837)
- Status last verified
- Jul 2026
- First submitted
- 4 Sep 2018
- Last updated
- 29 Jul 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- Yes
- Individual data sharing
- No
Publications
Diduch DR, Crawford DC, Ranawat AS, Victor J, Flanigan DC. Implantable Shock Absorber Provides Superior Pain Relief and Functional Improvement Compared With High Tibial Osteotomy in Patients with Mild-to-Moderate Medial Knee Osteoarthritis: A 2-Year Report. Cartilage. 2023 Jun;14(2):152-163. doi: 10.1177/19476035231157335. Epub 2023 Feb 23.
PubMed 36823955Ranawat A, Flanigan D, Crawford D, Sherman S, Walawski J, Zdanowicz U, Janik M, Slynarski K, Domzalski M, Victor J, Diduch D, Gomoll A. 5-Year Results of an Implantable Shock Absorber Demonstrate Durable Outcomes in Patients with Medial Knee Osteoarthritis. JB JS Open Access. 2026 Jun 15;11(2):e25.00187. doi: 10.2106/JBJS.OA.25.00187. eCollection 2026 Apr-Jun.
PubMed 42299375
Study at a glance
From the registry record, last updated by the sponsor on 29 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Evaluation of the Calypso Knee System for Symptom Relief in Subjects With Medial Knee Osteoarthritis
- ClinicalTrials.gov ID
- NCT03671213
- Acronym / sponsor ID
- CP0001 (formerly CLIN102837)
- Conditions
- Osteoarthritis, Knee
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 81 participants (actual)
- Lead sponsor
- MoximedIndustry (pharma, biotech, devices)
- Study start
- 19 Sep 2018 (actual)
- Primary completion
- 17 Jan 2022 (actual)
- Study completion
- 14 Mar 2025 (actual)
- First posted
- 14 Sep 2018 (actual)
- Results
- Posted 27 Jun 2023
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
A clinical study to evaluate the safety and effectiveness of the Calypso Knee System when used in subjects with symptomatic osteoarthritis of the medial compartment of the knee.
Detailed description
Prospective, multicenter clinical study of the Calypso Knee System. 81 subjects were enrolled in this study. Male or female subjects age 25 to 65 years, with a diagnosis of medial knee osteoarthritis and study knee pain with an overall WOMAC pain score ≥ 40 (scale 0-100).
The Calypso group was investigated under two clinical protocols, CP0001 in the USA, and CP0002 in Europe. Both clinical protocols followed the same supporting protocols and plans, such as radiographic, statistical, Clinical Events Committee (CEC), etc. The results from the combined analysis have been reported in both NCT03671213 (CP0001) and NCT03838978 (CP0002).
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Single Arm Study Design
| Arm | Type | Receives |
|---|---|---|
| Calypso | Experimental | Device: Calypso Knee System (Implantable Shock Absorber)Calypso Knee System |
Who may qualify
- Ages
- 25 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- Participants age - 25 to 65 years
- Body Mass Index (BMI) of < 35, Weight < 300 lbs
- Knee osteoarthritis pain on the inner side of knee that has continued after at least 6 months of non-operative treatment
Key exclusion criteria (3 listed)
- Symptoms of osteoarthritis in the other knee or in lateral (outer) or patellofemoral compartments of the target knee
- Knee ligament or meniscal instability
- Other bone or joint conditions such as Rheumatoid arthritis, Paget's disease, Charcot's disease or general conditions such as allergy or hypersensitivity to certain metals, active infection, certain neurological conditions, use of medication such as steroids or chemotherapy that could impact study participation or results
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 |
|---|---|---|
| Calypso Knee System (Implantable Shock Absorber)Also: MISHA® Knee SystemThe Calypso Knee System is an extra-capsular knee implant designed to fill the therapeutic gap between conservative care and more invasive surgical interventions for knee osteoarthritis. | Device | Calypso |
Primary outcome
Composite Clinical Success (CCS)
Time frame: From baseline to 24 months
A subject is considered a Composite Clinical Success (CCS), at 24 months, if the subject meets all of the following: 1. Clinically significant improvement of at least 20% from baseline on the WOMAC pain questions in the KOOS Knee questionnaire with a change of ≥10 points 2. Clinically significant improvement of at least 20% from baseline on the WOMAC function questions in the KOOS Knee questionnaire with a change of ≥10 points 3. Freedom from the following device-related serious adverse events: * Deep infection requiring surgical intervention (Both arms) * Damage to adjacent neurovascular or ligament structures necessitating reconstruction (Both arms) * Non-union (HTO only) 4. Maintenance of implant integrity as evaluated by radiographic assessment 5. Endpoint Subsequent Surgical Intervention (SSI)
5 secondary outcomes
Time to Full Weight Bearing (Days)
Time frame: Through study completion (Number of days to full weight bearing)
WOMAC Pain Percent Change to Month 3
Time frame: From baseline to 3 months
WOMAC Pain Percent Change to Month 24
Time frame: From baseline to 24 months
WOMAC Function Percent Change to Month 3
Time frame: From baseline to 3 months
WOMAC Function Percent Change to Month 24
Time frame: From baseline to 24 months
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 29 Jul 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Results publication: PubMed 36823955Diduch DR, Crawford DC, Ranawat AS, Victor J, Flanigan DC. Implantable Shock Absorber Provides Superior Pain Relief and Functional Improvement Compared With High Tibial Osteotomy in Patients with Mild-to-Moderate Medial Knee Osteoarthritis: A 2-Year Report. Cartilage. 2023 Jun;14(2):152-163. doi: 10.1177/19476035231157335. Epub 2023 Feb 23.
- Results publication: PubMed 42299375Ranawat A, Flanigan D, Crawford D, Sherman S, Walawski J, Zdanowicz U, Janik M, Slynarski K, Domzalski M, Victor J, Diduch D, Gomoll A. 5-Year Results of an Implantable Shock Absorber Demonstrate Durable Outcomes in Patients with Medial Knee Osteoarthritis. JB JS Open Access. 2026 Jun 15;11(2):e25.00187. doi: 10.2106/JBJS.OA.25.00187. eCollection 2026 Apr-Jun.
- 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.
David Flanigan, MD principal investigator
Ohio State University
5 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Calypso Knee System (Implantable Shock Absorber) in people with Osteoarthritis, Knee, run by Moximed at 5 sites 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 3 inclusion and 3 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: finished, as of the sponsor's last update on 29 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 5 sites 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?
Yes. Results are posted in the registry (first posted 27 Jun 2023). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
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?
Composite Clinical Success (CCS) (time frame: From baseline to 24 months). 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 NCT03671213, which also lists 2 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 29 Jul 2026.