Arthrofibrosis of KneeLDI TKR RCTNCT07767097
Stiffness and Low Dose Irradiation RCT
A study testing Low-Dose External Beam Irradiation and Hinged Revision Total Knee Arthroplasty in people with Arthrofibrosis of Knee, run by Mount Sinai Hospital, Canada at 4 sites in 2 countries.
Trial summary
Acquired idiopathic stiffness (AIS) is a common complication following total knee arthroplasty (TKA). It is caused by excessive scar formation, which leads to pain, loss of motion, and functional impairment. When early noninvasive treatments fail, some patients require more surgery. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Arthrofibrosis of Knee
- What is being tested?
- Low-Dose External Beam Irradiation and Hinged Revision Total Knee Arthroplasty
- Type of treatment
- Pill or oral medicine, Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 36 participants
- Where
- 4 sitesin 2 countries
- Study dates
- 1 Apr 2026to 31 Jan 2029
- 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 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Adults (≥18 years) undergoing revision TKA with a hinged prosthesis for AIS after primary TKA
- Patient with a ROM arc <70 degrees or flexion contracture of >20 degrees without any identifiable cause for stiffness (e.g. component oversizing, malrotation, infection, or periprosthetic fracture).
Who cannot join
- Revision for causes other than AIS (e.g., component malposition, infection, periprosthetic fracture)
- Prior ipsilateral knee infection
- Revision to non-hinged prosthesis
- Medical contraindications to surgery
- Medical contraindications to irradiation
- Currently pregnant or planning to become pregnant during the study period
Trial locations and contacts
4 sites in 2 countries. Contact the study team or a site near you to ask about taking part.
4 sites in 2 countries
United States2 sites, 2 recruiting
- Not yet recruiting
University of Southern California
Los Angeles, California, 90007
Nathanael Heckmann, MD, 323-442-6984, nathanael.heckmann@med.usc.edu
Nathanael Heckmann, MD
- Not yet recruiting
University of Utah
Salt Lake City, Utah, 84112
Lucas Anderson, MD, 801-587-7109, lucas.anderson@hsc.utah.edu
Lucas Anderson, MD
Canada2 sites, 2 recruiting
- Not yet recruiting
Humber River Hospital
Toronto, Ontario, M3M 0B2
Justin Chang, MD, 416-291-5553, JuChang@hrh.ca
Justin Chang, MD
- Recruiting
Mount Sinai Hospital
Toronto, Ontario, M5G 1X5
Jesse Wolfstadt, MD, 416-586-4800 ext. 8457, jesse.wolfstadt@sinaihealth.ca
Ravianne Tuazon, BSc, 416-586-4800 ext. 4759, Ravianne.Tuazon@sinaihealth.ca
About this study
Official title: Treatment of Acquired Idiopathic Stiffness in Revision Total Knee Arthroplasty With Hinged Knee Prosthesis With or Without Low Dose Irradiation: A Multicentre Prospective Randomized Controlled Trial
Acquired idiopathic stiffness (AIS) is a common complication following total knee arthroplasty (TKA). It is caused by excessive scar formation, which leads to pain, loss of motion, and functional impairment. When early noninvasive treatments fail, some patients require more surgery. In these cases, surgeons often use a special type of replacement called a hinged prosthesis, which allows more thorough removal of scar tissue and stiffened ligaments. Unfortunately, even after more surgery, many patients continue to struggle with stiffness, pain, and impaired function. Low-dose irradiation (LDI) is a safe, established therapy for conditions with abnormal scar formation. Its role in the setting of AIS has not been defined. The goal of this study is to compare outcomes of revision TKA with or without the addition of LDI. The primary outcome is range of motion at one year following surgery. Secondary outcomes include patient-reported functional scores, repeat surgeries, and complications like wound breakdown or infection. This project has the potential to address a common, debilitating complication after TKA, improve outcomes, reduce repeat interventions and healthcare costs, and broader implementation and standardization of care.
Read the detailed description
Acquired idiopathic stiffness (AIS), or arthrofibrosis, is a rare but potentially devastating complication after total knee arthroplasty (TKA), occurring in approximately 1-6% of cases. It is characterized by pathological fibroblast and myofibroblast proliferation leading to excessive scar tissue deposition within and around the knee joint, resulting in restricted range of motion (ROM), pain, and functional impairment.
When conservative management (physiotherapy, manipulation under anesthesia) fails, operative intervention is required. Full component revision to a hinged prosthesis - which permits complete synovectomy, posterior capsule release, and debridement of fibrosed collateral ligaments - has demonstrated superior ROM outcomes compared to partial revision strategies.
Perioperative low-dose irradiation (LDI) has an established role in the prophylaxis of heterotopic ossification following total hip arthroplasty and is used as adjunctive therapy for keloid prevention. Mechanistically, LDI at 700-800 cGy inhibits myofibroblast proliferation and modulates fibrotic signaling pathways, addressing the underlying pathophysiology of arthrofibrosis. A retrospective review of 60 patients undergoing hinged revision TKA with LDI demonstrated a median ROM improvement of 60°, with acceptable complication rates.
Despite this evidence, no prospective randomized controlled trial has compared hinged revision TKA with and without LDI.
- Conditions
- Arthrofibrosis of Knee
- Being tested
- Low-Dose External Beam Irradiation, Hinged Revision Total Knee Arthroplasty
- Keywords
- arthrofibrosis, stiffness, revision knee, low dose irradiation, hinged knee prosthesis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Low-Dose External Beam IrradiationRadiation
A single session of external beam irradiation (800 cGy) delivered to the operative knee on post-operative day 1 (or post-operative day 2 if medically necessary). At Mount Sinai Hospital and Humber River Hospital, LDI is delivered at Princess Margaret Cancer Centre. US sites coordinate through local radiation oncology departments.
Hinged Revision Total Knee ArthroplastyProcedure or surgery
Full component revision to a rotating hinge knee prosthesis, including synovectomy, posterior capsule debridement, and release of fibrosed collateral ligaments, performed by the treating orthopaedic surgeon at each participating site.
| Study group | Role | What they receive |
|---|---|---|
| Hinged Revision TKA + Low-Dose Irradiation | Experimental | Patients undergo hinged revision total knee arthroplasty (TKA) with a rotating hinge prosthesis, followed by a single session of external beam low-dose irradiation (LDI) delivering 800 cGy to the operative knee on post-operative day 1 (or post-operative day 2 if medically necessary), coordinated with radiation oncology. Receives: Radiation: Low-Dose External Beam Irradiation; Procedure: Hinged Revision Total Knee Arthroplasty |
| Hinged Revision TKA Alone | Active comparator | Patients undergo hinged revision total knee arthroplasty (TKA) with a rotating hinge prosthesis and receive standard postoperative care without low-dose irradiation. All perioperative care, rehabilitation, and follow-up protocols are identical to the experimental arm. Receives: Procedure: Hinged Revision Total Knee Arthroplasty |
What is being measured
The primary outcome is the main question the study is designed to answer.
Total arc of knee range of motion (ROM)
Goniometric measurement of total arc of motion (flexion minus extension deficit) performed by treating surgeon at each follow-up visit, per standard clinical protocol.
Measured: Baseline (pre-operative), intraoperative, 2 weeks, 6 weeks, 3 months, and1 year post-operatively.
Secondary outcomes (8)
Oxford Knee Score (OKS)
Measured: Pre-op, 2 weeks, 6 weeks, 3 months, 1 year
EQ-5D-5L (health-related quality of life)
Measured: Pre-op, 2 weeks, 6 weeks, 3 months, 1 year
Visual Analogue Scale (VAS) - Pain
Measured: Pre-op, 2 weeks, 6 weeks, 3 months, 1 year
Patient Satisfaction (numeric rating)
Measured: 6 weeks, 3 months, 1 year
Wound complications (requiring intervention)
Measured: 2 weeks, 6 weeks, 3 months, 1 year
Infection rate
Measured: 2 weeks, 6 weeks, 3 months, 1 year
Reoperation Rate
Measured: 2 weeks, 6 weeks, 3 months, 1 year
Medical complications
Measured: 2 weeks, 6 weeks, 3 months, 1 year
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Aug 2026
- Study start1 Apr 2026
- Primary completion31 Dec 2028 (estimated)
- Study completion31 Jan 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (4)Papers the sponsor has linked to this study.
- Other trials for Arthrofibrosis of 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
- Masking
- None (open label)
- Enrolment
- 36 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Mount Sinai Hospital, Canada
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Jesse Wolfstadt, Mount Sinai Hospital, Canada
- Investigators
- Jesse Wolfstadt, MD, MSc, Principal investigator, MOUNT SINAI HOSPITAL
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07767097
- Sponsor's protocol ID
- 1572
- Acronym
- LDI TKR RCT
- Status last verified
- Mar 2026
- First submitted
- 11 Aug 2026
- Last updated
- 17 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be shared publicly. De-identified aggregate data supporting the findings of this study will be available upon reasonable request to the corresponding author following publication of primary results.
Publications
Liow MHL, Flevas DA, Braun S, Nocon A, Lee GC, Sculco PK; TKAF Consortium. Rotating Hinge Revision Total Knee Arthroplasty Provides Greater Arc of Motion Gains for Patients Who Have Severe Arthrofibrosis. J Arthroplasty. 2025 Jan;40(1):198-202. doi: 10.1016/j.arth.2024.06.056. Epub 2024 Aug 9.
PubMed 39128782Haffar A, Goh GS, Fillingham YA, Torchia MT, Lonner JH. Treatment of arthrofibrosis and stiffness after total knee arthroplasty: an updated review of the literature. Int Orthop. 2022 Jun;46(6):1253-1279. doi: 10.1007/s00264-022-05344-x. Epub 2022 Mar 18.
PubMed 35301559Lex JR, Entezari B, Backstein DJ, Wolfstadt JI. Reliable Outcomes Provided by a Rotating Hinge Knee Arthroplasty for Patients Who Have Moderate-To-Severe Arthrofibrosis. J Arthroplasty. 2026 Mar;41(3):862-868. doi: 10.1016/j.arth.2025.07.041. Epub 2025 Jul 24.
PubMed 40714210Schneider AM, Rice SJ, Lancaster N, McGraw M, Farid Y, Finn HA. Low-Dose Irradiation and Rotating-Hinge Revision for the Treatment of Severe Idiopathic Arthrofibrosis Following Total Knee Arthroplasty: A Review of 60 Patients With a Mean 6-Year Follow-Up. J Arthroplasty. 2024 Apr;39(4):1075-1082. doi: 10.1016/j.arth.2023.10.021. Epub 2023 Oct 18.
PubMed 37863275
Study at a glance
From the registry record, last updated by the sponsor on 17 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Treatment of Acquired Idiopathic Stiffness in Revision Total Knee Arthroplasty With Hinged Knee Prosthesis With or Without Low Dose Irradiation: A Multicentre Prospective Randomized Controlled Trial
- ClinicalTrials.gov ID
- NCT07767097
- Acronym / sponsor ID
- LDI TKR RCT / 1572
- Conditions
- Arthrofibrosis of Knee
- Keywords
- arthrofibrosis, stiffness, revision knee, low dose irradiation, hinged knee prosthesis
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 36 participants (estimated)
- Lead sponsor
- Mount Sinai Hospital, CanadaUniversity, hospital or other
- Study start
- 1 Apr 2026 (actual)
- Primary completion
- 31 Dec 2028 (estimated)
- Study completion
- 31 Jan 2029 (estimated)
- First posted
- 17 Aug 2026 (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.
Acquired idiopathic stiffness (AIS) is a common complication following total knee arthroplasty (TKA). It is caused by excessive scar formation, which leads to pain, loss of motion, and functional impairment. When early noninvasive treatments fail, some patients require more surgery. In these cases, surgeons often use a special type of replacement called a hinged prosthesis, which allows more thorough removal of scar tissue and stiffened ligaments. Unfortunately, even after more surgery, many patients continue to struggle with stiffness, pain, and impaired function. Low-dose irradiation (LDI) is a safe, established therapy for conditions with abnormal scar formation. Its role in the setting of AIS has not been defined. The goal of this study is to compare outcomes of revision TKA with or without the addition of LDI. The primary outcome is range of motion at one year following surgery. Secondary outcomes include patient-reported functional scores, repeat surgeries, and complications like wound breakdown or infection. This project has the potential to address a common, debilitating complication after TKA, improve outcomes, reduce repeat interventions and healthcare costs, and broader implementation and standardization of care.
Detailed description
Acquired idiopathic stiffness (AIS), or arthrofibrosis, is a rare but potentially devastating complication after total knee arthroplasty (TKA), occurring in approximately 1-6% of cases. It is characterized by pathological fibroblast and myofibroblast proliferation leading to excessive scar tissue deposition within and around the knee joint, resulting in restricted range of motion (ROM), pain, and functional impairment.
When conservative management (physiotherapy, manipulation under anesthesia) fails, operative intervention is required. Full component revision to a hinged prosthesis - which permits complete synovectomy, posterior capsule release, and debridement of fibrosed collateral ligaments - has demonstrated superior ROM outcomes compared to partial revision strategies.
Perioperative low-dose irradiation (LDI) has an established role in the prophylaxis of heterotopic ossification following total hip arthroplasty and is used as adjunctive therapy for keloid prevention. Mechanistically, LDI at 700-800 cGy inhibits myofibroblast proliferation and modulates fibrotic signaling pathways, addressing the underlying pathophysiology of arthrofibrosis. A retrospective review of 60 patients undergoing hinged revision TKA with LDI demonstrated a median ROM improvement of 60°, with acceptable complication rates.
Despite this evidence, no prospective randomized controlled trial has compared hinged revision TKA with and without LDI.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Hinged Revision TKA + Low-Dose Irradiation | Experimental | Radiation: Low-Dose External Beam Irradiation, Procedure: Hinged Revision Total Knee ArthroplastyPatients undergo hinged revision total knee arthroplasty (TKA) with a rotating hinge prosthesis, followed by a single session of external beam low-dose irradiation (LDI) delivering 800 cGy to the operative knee on post-operative day 1 (or post-operative day 2 if medically necessary), coordinated with radiation oncology. |
| Hinged Revision TKA Alone | Active comparator | Procedure: Hinged Revision Total Knee ArthroplastyPatients undergo hinged revision total knee arthroplasty (TKA) with a rotating hinge prosthesis and receive standard postoperative care without low-dose irradiation. All perioperative care, rehabilitation, and follow-up protocols are identical to the experimental arm. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (2 listed)
- Adults (≥18 years) undergoing revision TKA with a hinged prosthesis for AIS after primary TKA
- Patient with a ROM arc <70 degrees or flexion contracture of >20 degrees without any identifiable cause for stiffness (e.g. component oversizing, malrotation, infection, or periprosthetic fracture).
Key exclusion criteria (6 listed)
- Revision for causes other than AIS (e.g., component malposition, infection, periprosthetic fracture)
- Prior ipsilateral knee infection
- Revision to non-hinged prosthesis
- Medical contraindications to surgery
- Medical contraindications to irradiation
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 |
|---|---|---|
| Low-Dose External Beam IrradiationA single session of external beam irradiation (800 cGy) delivered to the operative knee on post-operative day 1 (or post-operative day 2 if medically necessary). At Mount Sinai Hospital and Humber River Hospital, LDI is delivered at Princess Margaret Cancer Centre. US sites coordinate through local radiation oncology departments. | Radiation | Hinged Revision TKA + Low-Dose Irradiation |
| Hinged Revision Total Knee ArthroplastyFull component revision to a rotating hinge knee prosthesis, including synovectomy, posterior capsule debridement, and release of fibrosed collateral ligaments, performed by the treating orthopaedic surgeon at each participating site. | Procedure or surgery | Hinged Revision TKA + Low-Dose Irradiation, Hinged Revision TKA Alone |
Primary outcome
Total arc of knee range of motion (ROM)
Time frame: Baseline (pre-operative), intraoperative, 2 weeks, 6 weeks, 3 months, and1 year post-operatively.
Goniometric measurement of total arc of motion (flexion minus extension deficit) performed by treating surgeon at each follow-up visit, per standard clinical protocol.
8 secondary outcomes
Oxford Knee Score (OKS)
Time frame: Pre-op, 2 weeks, 6 weeks, 3 months, 1 year
EQ-5D-5L (health-related quality of life)
Time frame: Pre-op, 2 weeks, 6 weeks, 3 months, 1 year
Visual Analogue Scale (VAS) - Pain
Time frame: Pre-op, 2 weeks, 6 weeks, 3 months, 1 year
Patient Satisfaction (numeric rating)
Time frame: 6 weeks, 3 months, 1 year
Wound complications (requiring intervention)
Time frame: 2 weeks, 6 weeks, 3 months, 1 year
Infection rate
Time frame: 2 weeks, 6 weeks, 3 months, 1 year
Reoperation Rate
Time frame: 2 weeks, 6 weeks, 3 months, 1 year
Medical complications
Time frame: 2 weeks, 6 weeks, 3 months, 1 year
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 17 Aug 2026.
- Background: PubMed 39128782Liow MHL, Flevas DA, Braun S, Nocon A, Lee GC, Sculco PK; TKAF Consortium. Rotating Hinge Revision Total Knee Arthroplasty Provides Greater Arc of Motion Gains for Patients Who Have Severe Arthrofibrosis. J Arthroplasty. 2025 Jan;40(1):198-202. doi: 10.1016/j.arth.2024.06.056. Epub 2024 Aug 9.
- Background: PubMed 35301559Haffar A, Goh GS, Fillingham YA, Torchia MT, Lonner JH. Treatment of arthrofibrosis and stiffness after total knee arthroplasty: an updated review of the literature. Int Orthop. 2022 Jun;46(6):1253-1279. doi: 10.1007/s00264-022-05344-x. Epub 2022 Mar 18.
- Background: PubMed 40714210Lex JR, Entezari B, Backstein DJ, Wolfstadt JI. Reliable Outcomes Provided by a Rotating Hinge Knee Arthroplasty for Patients Who Have Moderate-To-Severe Arthrofibrosis. J Arthroplasty. 2026 Mar;41(3):862-868. doi: 10.1016/j.arth.2025.07.041. Epub 2025 Jul 24.
- Background: PubMed 37863275Schneider AM, Rice SJ, Lancaster N, McGraw M, Farid Y, Finn HA. Low-Dose Irradiation and Rotating-Hinge Revision for the Treatment of Severe Idiopathic Arthrofibrosis Following Total Knee Arthroplasty: A Review of 60 Patients With a Mean 6-Year Follow-Up. J Arthroplasty. 2024 Apr;39(4):1075-1082. doi: 10.1016/j.arth.2023.10.021. Epub 2023 Oct 18.
- Individual participant dataSharing planned: No. Individual participant data will not be shared publicly. De-identified aggregate data supporting the findings of this study will be available upon reasonable request to the corresponding author following publication of primary results.
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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.
Jesse Wolfstadt, MD, MSc principal investigator
MOUNT SINAI HOSPITAL
4 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Low-Dose External Beam Irradiation and Hinged Revision Total Knee Arthroplasty in people with Arthrofibrosis of Knee, run by Mount Sinai Hospital, Canada at 4 sites in 2 countries.
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 2 inclusion and 6 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: looking for participants now, as of the sponsor's last update on 17 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 4 sites in United States, Canada. 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?
Contact Jesse Wolfstadt, MD, MSc (416-586-4800 ext. 8457, jesse.wolfstadt@sinaihealth.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Total arc of knee range of motion (ROM) (time frame: Baseline (pre-operative), intraoperative, 2 weeks, 6 weeks, 3 months, and1 year post-operatively.). 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 NCT07767097, which also lists 4 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 17 Aug 2026.