Anterior Cruciate Ligament (ACL) TearNCT07318272
Clinical and Functional Outcomes After ACL Reconstruction Versus Primary Repair
An observational study of Anterior Cruciate Ligament (ACL) Tear and Anterior Cruciate Ligament Reconstruction, run by Gazi University at 1 site in Turkey (Türkiye).
Trial summary
The anterior cruciate ligament (ACL) is the primary structure responsible for controlling anterior-posterior translation and rotational stability of the knee joint. Although ACL reconstruction has long been considered the gold standard among surgical interventions following ACL injury, arthroscopic primary repair… Read more about this study
- Who is it for?
- Ages 18 to 40 yearsHealthy volunteers can take part
- Conditions the study is for
- Anterior Cruciate Ligament (ACL) Tear, Anterior Cruciate Ligament Reconstruction, Isokinetic Test
- How many people
- 45 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 4 Aug 2026to 30 Nov 2027
- Phase
- Observational
- 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 to 40 years
- All sexes
- Healthy volunteers accepted
- Adult
Study population: The study will include a total of 45 participants. All participants will be adults aged 18-40 who meet the study's eligibility criteria, are able to comply with the assessment procedures, and provide informed consent.
Who may be able to join
- Age 18-40 years
- History of complete ACL rupture treated with ACL reconstruction
- Surgery performed at Gazi University Department of Orthopedics and Traumatology
- At least 12 months postoperative at the time of evaluation
- Ability to comply with all study procedures
- Signed informed consent
Show all 18Show fewer
- Age 18-40 years
- Complete ACL rupture treated with arthroscopic primary ACL repair
- Surgery performed at Gazi University Department of Orthopedics and Traumatology
- Minimum 12 months postoperative at the time of assessment A-bility to follow and complete study procedures
- Signed informed consent
- Age 18-40 years
- No significant lower-extremity malalignment (e.g., varus/valgus deformity)
- No history of lower-extremity injury within the past 12 months
- No known chronic systemic disease
- No history of knee surgery or diagnosed knee pathology
- Ability to understand and comply with study procedures
- Signed informed consent
Who cannot join
- Previous surgery for partial or chronic ACL tear
- Concomitant multi-ligament knee injuries
- Prior surgery on the ipsilateral or contralateral knee
- Lower extremity malalignment (e.g., significant varus/valgus)
- Tibial avulsion-type ACL injury
- Neurological or musculoskeletal disorders affecting lower limb function
Show all 20Show fewer
- Any medical condition that may interfere with test performance or safety
- Previous surgery for partial or chronic ACL injury
- Multi-ligament knee injuries
- History of surgery on either knee
- Lower extremity malalignment
- Tibial avulsion-type ACL rupture
- Neuromuscular or musculoskeletal diseases affecting lower limb function or balance
- Any condition that may affect participation or compromise safety
- Presence of clinically significant lower-extremity malalignment
- Lower-extremity musculoskeletal injury within the last 12 months
- Any chronic systemic or metabolic disease
- History of knee injury, knee surgery, or diagnosed knee pathology
- Neurological, vestibular, or musculoskeletal disorder affecting balance or gait
- Inability to complete study procedures
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Turkey (Türkiye)1 site, 1 recruiting
- Recruiting
Gazi University Faculty of Health Sciences Department of Physiotherapy and Rehabilitation
Ankara, Çankaya, 06490
Dudu Ozdemir Can, MSc, 90 5534448492, duduozdemir@gazi.edu.tr
About this study
Official title: Comparison of Clinical and Functional Outcomes After Anterior Cruciate Ligament Reconstruction and Primary Repair Surgery
The anterior cruciate ligament (ACL) is the primary structure responsible for controlling anterior-posterior translation and rotational stability of the knee joint. Although ACL reconstruction has long been considered the gold standard among surgical interventions following ACL injury, arthroscopic primary repair techniques have recently regained interest. With advances in minimally invasive surgical procedures, refined patient selection criteria, and improved rehabilitation strategies, the clinical effectiveness of primary repair is once again being re-evaluated. However, there remains a limited body of literature directly comparing the medium- to long-term effects of these two surgical techniques on neuromuscular performance, fatigue tolerance, and functional outcomes.
The aim of this study is to comparatively investigate postoperative muscle strength and endurance, isokinetic fatigue response, muscle oxygenation, proprioception, knee stability, postural control, and patient-reported outcome measures in individuals who have undergone ACL reconstruction or primary repair. Assessments will include low- and high-velocity tests performed on the Cybex Norm isokinetic dynamometer, a 33-repetition fatigue protocol at 300°/s, muscle oxygenation analysis using Train.Red NIRS, knee laxity measurement via the GNRB arthrometer, single-leg balance and landing evaluations using the KFORCE force platform, and subjective outcome measures (IKDC, ACL-RSI).
The findings of this study are expected to provide a more comprehensive understanding of how surgical technique influences physiological, biomechanical, and functional outcomes. This knowledge may contribute to the development of individualized rehabilitation approaches and evidence-based return-to-sport criteria.
Read the detailed description
The anterior cruciate ligament (ACL), one of the key stabilizers of the knee joint, plays a crucial role in maintaining both anteroposterior and rotational stability. The increasing popularity of recreational and competitive sports has contributed to a rising incidence of ACL injuries in recent years. Until the late 1980s, primary repair was widely accepted as the standard treatment for ACL injuries. Although short-term outcomes were generally satisfactory, this technique was largely abandoned due to high failure rates observed in medium- and long-term follow-ups. The probable causes of these unfavorable outcomes include suboptimal patient selection, invasive open repair techniques performed with absorbable sutures, and nonfunctional rehabilitation approaches characterized by prolonged cast immobilization. Considering the limited healing potential of the ligament, reconstruction surgery-performed using allografts or autologous tendon grafts-emerged as the new standard for the treatment of ACL injuries.
However, several disadvantages associated with reconstruction have raised the notion that a single surgical method may not be appropriate for all patients. These drawbacks include graft rerupture or contralateral ACL injury, loss of proprioception, physeal disturbances in pediatric populations, donor site morbidity in autografts or higher failure rates in allografts, the potential need for complex revision surgery, and the risk of early-onset osteoarthritis. In recent years, advances in patient selection criteria, minimally invasive surgical techniques, and modern rehabilitation protocols have renewed interest in arthroscopic primary ACL repair. This method preserves the native ligament and its proprioceptive properties while avoiding donor site morbidity, thereby offering the potential for a smoother and more accelerated postoperative rehabilitation process. Additionally, if primary repair fails, ACL reconstruction remains a viable subsequent treatment option. Primary repair has been described as a less morbid surgical alternative for patients presenting with acute proximal ACL tears, although high-quality evidence for its use is still limited.
Recent studies have shown improved success rates following primary repair of proximal ACL tears. In one investigation, researchers reported a 0% failure rate among 75 patients treated with primary ACL repair. Furthermore, 88% of patients demonstrated a negative pivot-shift test, 87% exhibited 0 or +1 Lachman test findings, and 89% successfully returned to sport. Similarly, numerous studies have evaluated the clinical effectiveness of ACL repair, and several recent systematic reviews have suggested that primary repair may be an effective treatment strategy with reasonable clinical outcomes compared to ACL reconstruction. Nonetheless, concerns remain that some evidence includes older cohorts that may not reflect contemporary surgical practices. A systematic review of only five comparative studies found no significant differences between treatments regarding clinical outcome scores, knee laxity, or graft rerupture rates. More recent randomized controlled trials have yielded conflicting results; some authors report that ACL repair provides non-inferior clinical outcomes compared to reconstruction, while others emphasize higher rates of adverse events and failure associated with repair. These issues underscore the need for further research comparing the medium- to long-term outcomes of ACL repair and ACL reconstruction.
Given the recent increase in clinical studies evaluating ACL repair versus reconstruction, synthesizing and expanding evidence from such research is critical for achieving a comprehensive and transparent understanding of the advantages, disadvantages, and clinical implications of both procedures.
The purpose of the present study is to compare postoperative clinical outcomes and patient-reported measures in individuals undergoing ACL reconstruction or primary ACL repair. Long-term outcomes of both procedures will be examined in terms of knee flexor and extensor muscle strength and endurance, torque-generating capacity and fatigue resistance, muscle oxygenation, knee joint proprioception, lower-extremity balance, and knee laxity. In this context, the findings of this study aim to provide valuable insights that may inform postoperative rehabilitation strategies and contribute to evidence-based clinical decision-making.
- Conditions
- Anterior Cruciate Ligament (ACL) Tear, Anterior Cruciate Ligament Reconstruction, Isokinetic Test
- Keywords
- ACL Injury, Anterior Cruciate Ligament, ACL Reconstruction, ACL Primary Repair, Postoperative Outcomes, Muscle Oxygenation, Isokinetic Testing
- Medical subject headings
- Lacerations, Anterior Cruciate Ligament Injuries
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| ACL Reconstruction Group | Demographic data, injury history, and surgical details will be recorded for all participants. The International Physical Activity Questionnaire, IKDC, and ACL-RSI scales will be administered. Assessments will be completed over two days. Isokinetic knee flexor/extensor strength, fatigue protocol, and H/Q ratios will be measured using the Cybex Norm dynamometer. Quadriceps and hamstring muscle oxygenation will be assessed with Train.Red NIRS. Knee proprioception will be evaluated via active joint repositioning, and postural control and dynamic stability will be measured using the KFORCE force platform. Knee laxity will be assessed with the GNRB arthrometer. | |
| Primary ACL Repair Group | Demographic data, injury history, and surgical details will be recorded for all participants. The International Physical Activity Questionnaire, IKDC, and ACL-RSI scales will be administered. Assessments will be completed over two days. Isokinetic knee flexor/extensor strength, fatigue protocol, and H/Q ratios will be measured using the Cybex Norm dynamometer. Quadriceps and hamstring muscle oxygenation will be assessed with Train.Red NIRS. Knee proprioception will be evaluated via active joint repositioning, and postural control and dynamic stability will be measured using the KFORCE force platform. Knee laxity will be assessed with the GNRB arthrometer. | |
| Healthy Control Group | Demographic data and physical activity levels will be recorded for healthy participants. All individuals will complete the International Physical Activity Questionnaire, IKDC, and ACL-RSI scales. Assessments will be conducted over two days. Knee flexor/extensor strength and H/Q ratios will be measured using the Cybex Norm isokinetic dynamometer. Quadriceps and hamstring muscle oxygenation will be assessed with the Train.Red NIRS device. Knee proprioception will be measured using an active joint repositioning test, while postural control and dynamic stability will be evaluated with the KFORCE force platform. Knee laxity will be assessed using the GNRB arthrometer. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Peak Torque (Isokinetic Strength)
Peak torque of the knee flexor and extensor muscles will be measured using an isokinetic dynamometer (Cybex NORM® isokinetic dynamometer, Humac, CA, USA). Measurements will be performed in the following modes: concentric contraction at 60°/s, eccentric contraction at 60°/s, concentric contraction at 180°/s, and concentric contraction at 300°/s. Peak torque values will be recorded for each testing velocity and contraction mode and expressed in Newton-meters (Nm).
Unit of Measure: Newton-meter (Nm)
Measured: First Day
Extremity Symmetry Index (ESI)
Extremity Symmetry Index will be calculated by comparing the involved and uninvolved limbs using peak torque values obtained from isokinetic testing.
Unit of Measure: Percentage (%)
Measured: First day
Conventional Hamstring-to-Quadriceps Ratio (H/Q Ratio)
The conventional H/Q ratio will be calculated as the ratio of concentric hamstring peak torque to concentric quadriceps peak torque. Unit of Measure: Ratio
Measured: First day
Functional Hamstring-to-Quadriceps Ratio
The functional H/Q ratio will be calculated as the ratio of eccentric hamstring peak torque to concentric quadriceps peak torque. Unit of Measure: Ratio
Measured: First day
Functional Range
Functional range will be defined as the angular range in which at least 85% of peak torque is maintained during isokinetic testing. Unit of Measure: Percentage (%)
Measured: First Day
Fatigue-Induced Peak Torque Decline
Fatigue-related performance decline will be calculated as the percentage decrease in peak torque following a 33-repetition isokinetic fatigue protocol at 300°/s. Unit of Measure: Percentage (%)
Measured: First Day
Muscle Oxygenation
Muscle oxygenation will be assessed using the Train.Red FYER wireless near-infrared spectroscopy (NIRS) system (Train.Red, Gelderland, Netherlands). The device provides continuous, non-invasive measurements of tissue oxygen saturation (StO₂) and the oxy-deoxyhemoglobin difference (HbDiff). Sensors will be placed over the quadriceps and hamstring muscles following SENIAM guidelines. Muscle oxygenation will be recorded before and immediately after the isokinetic fatigue protocol to evaluate changes in local oxygen utilization and metabolic stress.
Measured: First Day
Secondary outcomes (6)
Knee Joint Proprioception
Knee proprioception will be assessed using an active joint repositioning test performed on the Cybex NORM® isokinetic system (Humac, CA, USA). Participants will actively reproduce a target angle (30° knee flexion) starting from 90° flexion. Three trials will be recorded, and the absolute angular error will be calculated as the mean difference between the target angle and the reproduced angles. This measure reflects the accuracy of joint position sense and will be used to evaluate proprioceptive function.
Measured: First Day
Single Leg Balance
Postural control will be assessed using the KFORCE Plates force platform (Kinvent, Montpellier, France). Participants will perform a single-leg balance task, and Center of Pressure (CoP)-based variables such as mean CoP velocity, path length, sway area, and stabilization time will be recorded. Measurements will be obtained under standardized testing conditions for both limbs.
Measured: Second Day
Single Leg Landing
Dynamic stability will be assessed using the KFORCE Plates force platform. Participants will perform a single-leg landing task, and Center of Pressure (CoP)-based variables including stabilization time, CoP displacement, sway area, and CoP velocity will be analyzed. This measure evaluates the participant's ability to achieve stable posture following landing.
Measured: Second Day
Knee Laxity
Knee anterior laxity will be assessed using the GNRB® arthrometer at 20° of knee flexion. The primary outcome variable will be Anterior Tibial Translation (ATT) measured in millimeters under standardized forces (134 N and 200 N). The side-to-side difference in ATT and the slope value (stiffness index) will also be recorded to evaluate anterior cruciate ligament integrity. These parameters provide an objective and quantitative measure of ligamentous stability.
Measured: First Day
IKDC Subjective Knee Evaluation
The International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form will be used to assess patient-reported knee symptoms, function, and sports activity levels. Scores range from 0 to 100, with higher scores indicating better knee function and fewer symptoms. This measure provides a validated assessment of functional recovery following ACL surgery.
Measured: First Day
ACL-RSI (Return to Sport Index)
The Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI) scale will be administered to evaluate psychological readiness to return to sport. The 12-item scale assesses emotions, confidence, and risk appraisal related to returning to physical activity. Scores range from 0 to 100, with higher scores indicating greater psychological readiness. This measure allows comparison of psychological recovery after ACL reconstruction and primary repair.
Measured: First Day
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted5 Jan 2026
- Study start4 Aug 2026
- Primary completion1 Jul 2027 (estimated)
- Study completion30 Nov 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (7)Papers the sponsor has linked to this study.
- Other trials for Anterior Cruciate Ligament (ACL) TearStudies of the same condition, open and under way.
- More trials run by Gazi UniversityThe sponsor's other registered studies.
- 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
- Observational
- Observational model
- Other
- Time perspective
- Prospective
- Enrolment
- 45 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Gazi University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Dudu Özdemir, Gazi University
- Investigators
- Nihan Karatas, Prof. Dr., Study director, Gazi UniversityDudu Ozdemir Can, MSc, Principal investigator, Gazi University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07318272
- Sponsor's protocol ID
- Gazi2025
- Status last verified
- Aug 2026
- First submitted
- 8 Dec 2025
- Last updated
- 25 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Hoogeslag RAG, Brouwer RW, Boer BC, de Vries AJ, Huis In 't Veld R. Acute Anterior Cruciate Ligament Rupture: Repair or Reconstruction? Two-Year Results of a Randomized Controlled Clinical Trial. Am J Sports Med. 2019 Mar;47(3):567-577. doi: 10.1177/0363546519825878.
PubMed 30822124Szwedowski D, Paczesny L, Zabrzynski J, Gagat M, Domzalski M, Huri G, Widuchowski W. The Comparison of Clinical Result between Primary Repair of the Anterior Cruciate Ligament with Additional Internal Bracing and Anatomic Single Bundle Reconstruction-A Retrospective Study. J Clin Med. 2021 Aug 31;10(17):3948. doi: 10.3390/jcm10173948.
PubMed 34501400Kunze KN, Pareek A, Nwachukwu BU, Ranawat AS, Pearle AD, Kelly BT, Allen AA, Williams RJ 3rd. Clinical Results of Primary Repair Versus Reconstruction of the Anterior Cruciate Ligament: A Systematic Review and Meta-analysis of Contemporary Trials. Orthop J Sports Med. 2024 Jun 11;12(6):23259671241253591. doi: 10.1177/23259671241253591. eCollection 2024 Jun.
PubMed 38867918Vermeijden HD, van der List JP, O'Brien R, DiFelice GS. Patients Forget About Their Operated Knee More Following Arthroscopic Primary Repair of the Anterior Cruciate Ligament Than Following Reconstruction. Arthroscopy. 2020 Mar;36(3):797-804. doi: 10.1016/j.arthro.2019.09.041. Epub 2020 Jan 7.
PubMed 31919026Schneider KN, Schliemann B, Gosheger G, Theil C, Weller J, Buddhdev PK, Ahlbaumer G. Good to Excellent Functional Short-Term Outcome and Low Revision Rates Following Primary Anterior Cruciate Ligament Repair Using Suture Augmentation. J Clin Med. 2020 Sep 23;9(10):3068. doi: 10.3390/jcm9103068.
PubMed 32977649Duong JKH, Bolton C, Murphy GT, Fritsch BA. Anterior cruciate ligament repair versus reconstruction: A clinical, MRI and patient-reported outcome comparison. Knee. 2023 Dec;45:100-109. doi: 10.1016/j.knee.2023.09.008. Epub 2023 Nov 3.
PubMed 37925800Ciceklidag M, Kaya I, Ayanoglu T, Ayas IH, Ozer M, Ataoglu MB, Kanatli U. Proprioception After Primary Repair of the Anterior Cruciate Ligament. Am J Sports Med. 2024 Apr;52(5):1199-1208. doi: 10.1177/03635465241228839. Epub 2024 Mar 4.
PubMed 38557260
Study at a glance
From the registry record, last updated by the sponsor on 25 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Comparison of Clinical and Functional Outcomes After Anterior Cruciate Ligament Reconstruction and Primary Repair Surgery
- ClinicalTrials.gov ID
- NCT07318272
- Acronym / sponsor ID
- Gazi2025
- Conditions
- Anterior Cruciate Ligament (ACL) Tear, Anterior Cruciate Ligament Reconstruction, Isokinetic Test
- Keywords
- ACL Injury, Anterior Cruciate Ligament, ACL Reconstruction, ACL Primary Repair, Postoperative Outcomes, Muscle Oxygenation, Isokinetic Testing
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 45 participants (estimated)
- Lead sponsor
- Gazi UniversityUniversity, hospital or other
- Study start
- 4 Aug 2026 (actual)
- Primary completion
- 1 Jul 2027 (estimated)
- Study completion
- 30 Nov 2027 (estimated)
- First posted
- 5 Jan 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.
The anterior cruciate ligament (ACL) is the primary structure responsible for controlling anterior-posterior translation and rotational stability of the knee joint. Although ACL reconstruction has long been considered the gold standard among surgical interventions following ACL injury, arthroscopic primary repair techniques have recently regained interest. With advances in minimally invasive surgical procedures, refined patient selection criteria, and improved rehabilitation strategies, the clinical effectiveness of primary repair is once again being re-evaluated. However, there remains a limited body of literature directly comparing the medium- to long-term effects of these two surgical techniques on neuromuscular performance, fatigue tolerance, and functional outcomes.
The aim of this study is to comparatively investigate postoperative muscle strength and endurance, isokinetic fatigue response, muscle oxygenation, proprioception, knee stability, postural control, and patient-reported outcome measures in individuals who have undergone ACL reconstruction or primary repair. Assessments will include low- and high-velocity tests performed on the Cybex Norm isokinetic dynamometer, a 33-repetition fatigue protocol at 300°/s, muscle oxygenation analysis using Train.Red NIRS, knee laxity measurement via the GNRB arthrometer, single-leg balance and landing evaluations using the KFORCE force platform, and subjective outcome measures (IKDC, ACL-RSI).
The findings of this study are expected to provide a more comprehensive understanding of how surgical technique influences physiological, biomechanical, and functional outcomes. This knowledge may contribute to the development of individualized rehabilitation approaches and evidence-based return-to-sport criteria.
Detailed description
The anterior cruciate ligament (ACL), one of the key stabilizers of the knee joint, plays a crucial role in maintaining both anteroposterior and rotational stability. The increasing popularity of recreational and competitive sports has contributed to a rising incidence of ACL injuries in recent years. Until the late 1980s, primary repair was widely accepted as the standard treatment for ACL injuries. Although short-term outcomes were generally satisfactory, this technique was largely abandoned due to high failure rates observed in medium- and long-term follow-ups. The probable causes of these unfavorable outcomes include suboptimal patient selection, invasive open repair techniques performed with absorbable sutures, and nonfunctional rehabilitation approaches characterized by prolonged cast immobilization. Considering the limited healing potential of the ligament, reconstruction surgery-performed using allografts or autologous tendon grafts-emerged as the new standard for the treatment of ACL injuries.
However, several disadvantages associated with reconstruction have raised the notion that a single surgical method may not be appropriate for all patients. These drawbacks include graft rerupture or contralateral ACL injury, loss of proprioception, physeal disturbances in pediatric populations, donor site morbidity in autografts or higher failure rates in allografts, the potential need for complex revision surgery, and the risk of early-onset osteoarthritis. In recent years, advances in patient selection criteria, minimally invasive surgical techniques, and modern rehabilitation protocols have renewed interest in arthroscopic primary ACL repair. This method preserves the native ligament and its proprioceptive properties while avoiding donor site morbidity, thereby offering the potential for a smoother and more accelerated postoperative rehabilitation process. Additionally, if primary repair fails, ACL reconstruction remains a viable subsequent treatment option. Primary repair has been described as a less morbid surgical alternative for patients presenting with acute proximal ACL tears, although high-quality evidence for its use is still limited.
Recent studies have shown improved success rates following primary repair of proximal ACL tears. In one investigation, researchers reported a 0% failure rate among 75 patients treated with primary ACL repair. Furthermore, 88% of patients demonstrated a negative pivot-shift test, 87% exhibited 0 or +1 Lachman test findings, and 89% successfully returned to sport. Similarly, numerous studies have evaluated the clinical effectiveness of ACL repair, and several recent systematic reviews have suggested that primary repair may be an effective treatment strategy with reasonable clinical outcomes compared to ACL reconstruction. Nonetheless, concerns remain that some evidence includes older cohorts that may not reflect contemporary surgical practices. A systematic review of only five comparative studies found no significant differences between treatments regarding clinical outcome scores, knee laxity, or graft rerupture rates. More recent randomized controlled trials have yielded conflicting results; some authors report that ACL repair provides non-inferior clinical outcomes compared to reconstruction, while others emphasize higher rates of adverse events and failure associated with repair. These issues underscore the need for further research comparing the medium- to long-term outcomes of ACL repair and ACL reconstruction.
Given the recent increase in clinical studies evaluating ACL repair versus reconstruction, synthesizing and expanding evidence from such research is critical for achieving a comprehensive and transparent understanding of the advantages, disadvantages, and clinical implications of both procedures.
The purpose of the present study is to compare postoperative clinical outcomes and patient-reported measures in individuals undergoing ACL reconstruction or primary ACL repair. Long-term outcomes of both procedures will be examined in terms of knee flexor and extensor muscle strength and endurance, torque-generating capacity and fatigue resistance, muscle oxygenation, knee joint proprioception, lower-extremity balance, and knee laxity. In this context, the findings of this study aim to provide valuable insights that may inform postoperative rehabilitation strategies and contribute to evidence-based clinical decision-making.
Study design
- Observational model
- Other
- Time perspective
- Prospective
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| ACL Reconstruction Group | – | –Demographic data, injury history, and surgical details will be recorded for all participants. The International Physical Activity Questionnaire, IKDC, and ACL-RSI scales will be administered. Assessments will be completed over two days. Isokinetic knee flexor/extensor strength, fatigue protocol, and H/Q ratios will be measured using the Cybex Norm dynamometer. Quadriceps and hamstring muscle oxygenation will be assessed with Train.Red NIRS. Knee proprioception will be evaluated via active joint repositioning, and postural control and dynamic stability will be measured using the KFORCE force platform. Knee laxity will be assessed with the GNRB arthrometer. |
| Primary ACL Repair Group | – | –Demographic data, injury history, and surgical details will be recorded for all participants. The International Physical Activity Questionnaire, IKDC, and ACL-RSI scales will be administered. Assessments will be completed over two days. Isokinetic knee flexor/extensor strength, fatigue protocol, and H/Q ratios will be measured using the Cybex Norm dynamometer. Quadriceps and hamstring muscle oxygenation will be assessed with Train.Red NIRS. Knee proprioception will be evaluated via active joint repositioning, and postural control and dynamic stability will be measured using the KFORCE force platform. Knee laxity will be assessed with the GNRB arthrometer. |
| Healthy Control Group | – | –Demographic data and physical activity levels will be recorded for healthy participants. All individuals will complete the International Physical Activity Questionnaire, IKDC, and ACL-RSI scales. Assessments will be conducted over two days. Knee flexor/extensor strength and H/Q ratios will be measured using the Cybex Norm isokinetic dynamometer. Quadriceps and hamstring muscle oxygenation will be assessed with the Train.Red NIRS device. Knee proprioception will be measured using an active joint repositioning test, while postural control and dynamic stability will be evaluated with the KFORCE force platform. Knee laxity will be assessed using the GNRB arthrometer. |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
- Study population
- The study will include a total of 45 participants. All participants will be adults aged 18-40 who meet the study's eligibility criteria, are able to comply with the assessment procedures, and provide informed consent.
Key inclusion criteria (18 listed)
- Age 18-40 years
- History of complete ACL rupture treated with ACL reconstruction
- Surgery performed at Gazi University Department of Orthopedics and Traumatology
- At least 12 months postoperative at the time of evaluation
- Ability to comply with all study procedures
Key exclusion criteria (20 listed)
- Previous surgery for partial or chronic ACL tear
- Concomitant multi-ligament knee injuries
- Prior surgery on the ipsilateral or contralateral knee
- Lower extremity malalignment (e.g., significant varus/valgus)
- Tibial avulsion-type ACL injury
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Peak Torque (Isokinetic Strength)
Time frame: First Day
Peak torque of the knee flexor and extensor muscles will be measured using an isokinetic dynamometer (Cybex NORM® isokinetic dynamometer, Humac, CA, USA). Measurements will be performed in the following modes: concentric contraction at 60°/s, eccentric contraction at 60°/s, concentric contraction at 180°/s, and concentric contraction at 300°/s. Peak torque values will be recorded for each testing velocity and contraction mode and expressed in Newton-meters (Nm). Unit of Measure: Newton-meter (Nm)
Extremity Symmetry Index (ESI)
Time frame: First day
Extremity Symmetry Index will be calculated by comparing the involved and uninvolved limbs using peak torque values obtained from isokinetic testing. Unit of Measure: Percentage (%)
Conventional Hamstring-to-Quadriceps Ratio (H/Q Ratio)
Time frame: First day
The conventional H/Q ratio will be calculated as the ratio of concentric hamstring peak torque to concentric quadriceps peak torque. Unit of Measure: Ratio
Functional Hamstring-to-Quadriceps Ratio
Time frame: First day
The functional H/Q ratio will be calculated as the ratio of eccentric hamstring peak torque to concentric quadriceps peak torque. Unit of Measure: Ratio
Functional Range
Time frame: First Day
Functional range will be defined as the angular range in which at least 85% of peak torque is maintained during isokinetic testing. Unit of Measure: Percentage (%)
Fatigue-Induced Peak Torque Decline
Time frame: First Day
Fatigue-related performance decline will be calculated as the percentage decrease in peak torque following a 33-repetition isokinetic fatigue protocol at 300°/s. Unit of Measure: Percentage (%)
Muscle Oxygenation
Time frame: First Day
Muscle oxygenation will be assessed using the Train.Red FYER wireless near-infrared spectroscopy (NIRS) system (Train.Red, Gelderland, Netherlands). The device provides continuous, non-invasive measurements of tissue oxygen saturation (StO₂) and the oxy-deoxyhemoglobin difference (HbDiff). Sensors will be placed over the quadriceps and hamstring muscles following SENIAM guidelines. Muscle oxygenation will be recorded before and immediately after the isokinetic fatigue protocol to evaluate changes in local oxygen utilization and metabolic stress.
6 secondary outcomes
Knee Joint Proprioception
Time frame: First Day
Single Leg Balance
Time frame: Second Day
Single Leg Landing
Time frame: Second Day
Knee Laxity
Time frame: First Day
IKDC Subjective Knee Evaluation
Time frame: First Day
ACL-RSI (Return to Sport Index)
Time frame: First Day
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 25 Aug 2026.
- Background: PubMed 30822124Hoogeslag RAG, Brouwer RW, Boer BC, de Vries AJ, Huis In 't Veld R. Acute Anterior Cruciate Ligament Rupture: Repair or Reconstruction? Two-Year Results of a Randomized Controlled Clinical Trial. Am J Sports Med. 2019 Mar;47(3):567-577. doi: 10.1177/0363546519825878.
- Background: PubMed 34501400Szwedowski D, Paczesny L, Zabrzynski J, Gagat M, Domzalski M, Huri G, Widuchowski W. The Comparison of Clinical Result between Primary Repair of the Anterior Cruciate Ligament with Additional Internal Bracing and Anatomic Single Bundle Reconstruction-A Retrospective Study. J Clin Med. 2021 Aug 31;10(17):3948. doi: 10.3390/jcm10173948.
- Background: PubMed 38867918Kunze KN, Pareek A, Nwachukwu BU, Ranawat AS, Pearle AD, Kelly BT, Allen AA, Williams RJ 3rd. Clinical Results of Primary Repair Versus Reconstruction of the Anterior Cruciate Ligament: A Systematic Review and Meta-analysis of Contemporary Trials. Orthop J Sports Med. 2024 Jun 11;12(6):23259671241253591. doi: 10.1177/23259671241253591. eCollection 2024 Jun.
- Background: PubMed 31919026Vermeijden HD, van der List JP, O'Brien R, DiFelice GS. Patients Forget About Their Operated Knee More Following Arthroscopic Primary Repair of the Anterior Cruciate Ligament Than Following Reconstruction. Arthroscopy. 2020 Mar;36(3):797-804. doi: 10.1016/j.arthro.2019.09.041. Epub 2020 Jan 7.
- Results publication: PubMed 32977649Schneider KN, Schliemann B, Gosheger G, Theil C, Weller J, Buddhdev PK, Ahlbaumer G. Good to Excellent Functional Short-Term Outcome and Low Revision Rates Following Primary Anterior Cruciate Ligament Repair Using Suture Augmentation. J Clin Med. 2020 Sep 23;9(10):3068. doi: 10.3390/jcm9103068.
- Results publication: PubMed 37925800Duong JKH, Bolton C, Murphy GT, Fritsch BA. Anterior cruciate ligament repair versus reconstruction: A clinical, MRI and patient-reported outcome comparison. Knee. 2023 Dec;45:100-109. doi: 10.1016/j.knee.2023.09.008. Epub 2023 Nov 3.
- Results publication: PubMed 38557260Ciceklidag M, Kaya I, Ayanoglu T, Ayas IH, Ozer M, Ataoglu MB, Kanatli U. Proprioception After Primary Repair of the Anterior Cruciate Ligament. Am J Sports Med. 2024 Apr;52(5):1199-1208. doi: 10.1177/03635465241228839. Epub 2024 Mar 4.
- 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.
Nihan Karatas, Prof. Dr. study director
Gazi University
Dudu Ozdemir Can, MSc principal investigator
Gazi University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Anterior Cruciate Ligament (ACL) Tear and Anterior Cruciate Ligament Reconstruction, run by Gazi University at 1 site in Turkey (Türkiye).
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 18 inclusion and 20 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 25 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 1 site in Turkey (Türkiye). 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 Dudu Ozdemir Can, Msc (90 5534448492, duduozdemir@gazi.edu.tr), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Peak Torque (Isokinetic Strength) (time frame: First Day). The study lists 7 primary outcomes in all. 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 NCT07318272, which also lists 7 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 25 Aug 2026; AzTrials last refreshed its copy on 7 Nov 2026.