Achilles Allograft With or Without InternalBrace for ACL Revision Surgery (ACL-AlloRev)

May 4, 2026 updated by: Medical University of Graz

Achilles Tendon Allografts With and Without InternalBrace Augmentation for Anterior Cruciate Ligament Revision Surgery: A Randomized Controlled Pilot Trial

This study evaluated outcomes after revision anterior cruciate ligament reconstruction using Achilles tendon allografts with a calcaneal bone block, with or without additional InternalBrace augmentation. Revision ACL reconstruction is often more complex than primary ACL reconstruction because previous surgery may leave widened bone tunnels or bone defects. Achilles tendon allografts with attached bone blocks may help address these defects and allow reconstruction in a single surgical procedure.

Participants with MRI-confirmed ACL graft re-tear and clinical knee instability were randomized to undergo revision ACL reconstruction either with InternalBrace augmentation or without InternalBrace augmentation. Clinical outcomes, patient-reported knee function, health-related quality of life, and MRI findings were assessed during 13 months of follow-up. The study was designed as a prospective randomized controlled pilot trial to compare whether additional InternalBrace augmentation improved functional, radiographic, or quality-of-life outcomes after revision ACL surgery.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Anterior cruciate ligament revision surgery remains challenging and may have less predictable outcomes than primary ACL reconstruction. In revision cases, prior bone tunnels and bone defects can complicate graft fixation. Achilles tendon allografts with calcaneal bone blocks provide a reliable graft configuration and may help fill pre-existing bone defects during a one-stage revision procedure. InternalBrace augmentation is intended to provide additional support to the reconstructed ligament during the healing period, but clinical evidence for its use with allograft ACL revision surgery is limited.

This prospective, randomized controlled pilot study enrolled patients from February 2017 to September 2020 at the Medical University of Graz. Eligible participants had MRI-confirmed re-tear of the ACL graft and clinical and patient-reported knee instability. Patients with advanced associated lesions requiring reconstruction or prolonged restricted weight bearing, signs of infection, advanced osteoarthritis, or neuromuscular disease were excluded. For all included participants, the procedure was the first revision surgery on the affected knee. The study was approved by the Ethics Committee of the Medical University of Graz, and written informed consent was obtained before participation.

All participants underwent revision ACL reconstruction using an Achilles tendon allograft with a calcaneal bone block. Participants were randomized in a 1:1 ratio to receive either additional InternalBrace augmentation or no InternalBrace augmentation. The InternalBrace group received a non-resorbable polyethylene FiberTape fixed separately and independently from the ACL graft. Apart from the additional InternalBrace fixation in one group, the surgical technique and postoperative rehabilitation protocol were the same for all participants.

Clinical and patient-reported outcomes were assessed preoperatively and at 6 weeks, 12 weeks, 6 months, and 13 months after surgery. Outcome measures included the International Knee Documentation Committee score, Lysholm Knee Questionnaire, Tegner Activity Scale, Knee Injury and Osteoarthritis Outcome Score, and Short Form-36. MRI scans were performed before surgery and 13 months after surgery to assess graft appearance, graft tightness, graft signal, ligament signs at the femoral and tibial tunnel insertions, and tunnel size.

The final analyzed study population included 30 participants, with 16 participants in the InternalBrace group and 14 participants in the non-InternalBrace group. Overall, clinical and patient-reported outcomes improved during follow-up. At the final 13-month follow-up, there were no clinically relevant differences between the InternalBrace and non-InternalBrace groups. Postoperative MRI showed elongated or insufficient ACL allografts in 15 of 30 participants, without significant differences between groups. The study concluded that ACL revision surgery using Achilles tendon allografts with bone blocks resulted in improved clinical outcomes at 13 months, but additional InternalBrace augmentation did not improve objective or subjective outcomes in this pilot trial.

Study Type

Interventional

Enrollment (Actual)

32

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Austria
    • Styria
      • Graz, Styria, Austria, 8036
        • Medical University of Graz

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • MRI-confirmed re-tear of the anterior cruciate ligament.
  • Clinical knee instability.
  • Patient-reported knee instability.
  • Planned first revision anterior cruciate ligament reconstruction of the affected knee.
  • Ability to undergo the standardized postoperative rehabilitation protocol.
  • Written informed consent for study participation and use of study data.

Exclusion Criteria:

  • Advanced associated knee lesions, such as pronounced meniscal tears or cartilage defects, requiring reconstruction or prolonged reduced weight bearing.
  • Signs of infection.
  • Advanced-stage osteoarthritis.
  • Neuromuscular disease.
  • Previous revision surgery on the affected knee.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: InternalBrace Augmentation
Participants underwent revision anterior cruciate ligament reconstruction using an Achilles tendon allograft with calcaneal bone block and additional InternalBrace augmentation. The InternalBrace consisted of non-resorbable polyethylene FiberTape fixed separately and independently from the ACL allograft.
Procedure: Revision ACL Reconstruction With Achilles Tendon Allograft and InternalBrace Augmentation
Revision anterior cruciate ligament reconstruction was performed using an Achilles tendon allograft with calcaneal bone block. In this group, a non-resorbable polyethylene FiberTape InternalBrace was additionally fixed separately and independently from the ACL allograft to support the graft during healing.
Other Names:
  • Revision ACL Reconstruction With InternalBrace
  • ACL Revision Surgery With InternalBrace Augmentation
  • Achilles Tendon Allograft ACL Revision With Suture Tape Augmentation
Active Comparator: No InternalBrace Augmentation
Participants underwent revision anterior cruciate ligament reconstruction using an Achilles tendon allograft with calcaneal bone block without additional InternalBrace augmentation. Apart from the InternalBrace augmentation, the surgical technique and postoperative rehabilitation protocol were the same as in the InternalBrace group.
Procedure: Revision ACL Reconstruction With Achilles Tendon Allograft Without InternalBrace Augmentation
Revision anterior cruciate ligament reconstruction was performed using an Achilles tendon allograft with calcaneal bone block. No additional InternalBrace or suture tape augmentation was used. Apart from the absence of InternalBrace augmentation, the surgical technique and postoperative rehabilitation protocol were the same as in the InternalBrace augmentation group.
Other Names:
  • Revision ACL Reconstruction Without InternalBrace
  • ACL Revision Surgery Without InternalBrace Augmentation
  • Achilles Tendon Allograft ACL Revision Without Suture Tape Augmentation

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
International Knee Documentation Committee Score
Time Frame: Preoperative baseline to 13 months after surgery
The International Knee Documentation Committee score was used to assess patient-reported knee symptoms, function, and sports activity after revision anterior cruciate ligament reconstruction. Scores range from 0 to 100, with higher scores indicating better knee function.
Preoperative baseline to 13 months after surgery

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Lysholm Knee Questionnaire Score
Time Frame: Preoperative baseline to 13 months after surgery
The Lysholm Knee Questionnaire was used to assess knee symptoms and functional limitations after revision anterior cruciate ligament reconstruction. Scores range from 0 to 100, with higher scores indicating better knee function.
Preoperative baseline to 13 months after surgery
Tegner Activity Scale Score
Time Frame: Preoperative baseline to 13 months after surgery
The Tegner Activity Scale was used to assess participant activity level after revision anterior cruciate ligament reconstruction. Scores range from 0 to 10, with higher scores indicating a higher activity level.
Preoperative baseline to 13 months after surgery
Knee Injury and Osteoarthritis Outcome Score
Time Frame: Preoperative baseline to 13 months after surgery
The Knee Injury and Osteoarthritis Outcome Score was used to assess knee-related pain, symptoms, activities of daily living, sport and recreation function, and knee-related quality of life. Subscale scores range from 0 to 100, with higher scores indicating better outcomes.
Preoperative baseline to 13 months after surgery
MRI Assessment of ACL Allograft Tightness
Time Frame: 13 months after surgery
Postoperative magnetic resonance imaging was used to assess anterior cruciate ligament allograft tightness. Grafts were categorized as tight, elongated, or insufficient.
13 months after surgery
MRI Assessment of Femoral and Tibial Tunnel Size
Time Frame: 13 months after surgery
Postoperative magnetic resonance imaging was used to measure femoral and tibial tunnel size after revision anterior cruciate ligament reconstruction. Tunnel size was measured in millimeters.
13 months after surgery
Short Form-36 Physical Component Summary Score
Time Frame: Preoperative baseline to 13 months after surgery
The Short Form-36 Physical Component Summary score was used to assess physical health-related quality of life after revision anterior cruciate ligament reconstruction. Scores range from 0 to 100, with higher scores indicating better physical health-related quality of life.
Preoperative baseline to 13 months after surgery
Short Form-36 Mental Component Summary Score
Time Frame: Preoperative baseline to 13 months after surgery
The Short Form-36 Mental Component Summary score was used to assess mental health-related quality of life after revision anterior cruciate ligament reconstruction. Scores range from 0 to 100, with higher scores indicating better mental health-related quality of life.
Preoperative baseline to 13 months after surgery

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Medical University of Graz

Investigators

  • Principal Investigator: Paul Ruckenstuhl, MD, Department of Orthopaedics and Trauma, Medical University of Graz

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

February 1, 2017

Primary Completion (Actual)

September 30, 2021

Study Completion (Actual)

September 30, 2021

Study Registration Dates

First Submitted

April 27, 2026

First Submitted That Met QC Criteria

April 27, 2026

First Posted (Actual)

May 4, 2026

Study Record Updates

Last Update Posted (Actual)

May 8, 2026

Last Update Submitted That Met QC Criteria

May 4, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 29-201 ex 16/17

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

De-identified individual participant data underlying the results reported in the publication will be shared upon reasonable request. Shared data may include baseline characteristics, group allocation, clinical outcome scores, patient-reported outcome measures, health-related quality-of-life scores, and MRI assessment data.

IPD Sharing Time Frame

Data will be available upon reasonable request after publication, with no predetermined end date.

IPD Sharing Access Criteria

Qualified researchers may request access by contacting the corresponding author. Requests will be reviewed based on scientific purpose, ethical approval where applicable, and compliance with applicable data protection requirements. Only de-identified data relevant to the approved request will be shared.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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