Clinical and Functional Outcomes After ACL Reconstruction Versus Primary Repair

NCT07318272 | Not Yet Recruiting

• 1 other identifier: Gazi2025
• Study Type: observational
• Target: 45
• Locations: 1 country
• Sites: 1

Brief 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 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.

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

Outcome Measures

Primary Outcomes (7)

• 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)

  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 (%)

  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

  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

  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 (%)

  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 (%)

  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.

  First Day

Secondary Outcomes (6)

• Knee Joint Proprioception

  First Day

• Single Leg Balance

  Second Day

• Single Leg Landing

  Second Day

• Knee Laxity

  First Day

• IKDC Subjective Knee Evaluation

  First Day

Study Arms (3)

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.

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)
• Sampling Method: Non-Probability Sample

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.

You may qualify if:

• 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

You may not qualify if:

• 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
• Any medical condition that may interfere with test performance or safety
• 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
• Previous surgery for partial or chronic ACL injury
• Multi-ligament knee injuries
• History of surgery on either knee

Sponsors & Collaborators

• Gazi University: lead

Study Sites (1)

Gazi University Faculty of Health Sciences Department of Physiotherapy and Rehabilitation

Ankara, Çankaya, 06490, Turkey (Türkiye)

Location

Related Publications (7)

• 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.

  PMID: 30822124 BACKGROUND

• Szwedowski 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.

  PMID: 34501400 BACKGROUND

• Kunze 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.

  PMID: 38867918 BACKGROUND

• Vermeijden 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.

  PMID: 31919026 BACKGROUND

• Schneider 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.

  PMID: 32977649 RESULT

• Duong 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.

  PMID: 37925800 RESULT

• Ciceklidag 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.

  PMID: 38557260 RESULT

MeSH Terms

Conditions

Lacerations; Anterior Cruciate Ligament Injuries

Condition Hierarchy (Ancestors)

Wounds and Injuries; Knee Injuries; Leg Injuries

Study Officials

• Nihan Karatas, Prof. Dr.

  Gazi University

  STUDY DIRECTOR

• Dudu Ozdemir Can, MSc

  Gazi University

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Dudu Ozdemir Can, Msc

CONTACT

90 5534448492; duduozdemir@gazi.edu.tr

Study Design

• Study Type: observational
• Observational Model: OTHER
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: MSc.

Study Record Dates

• First Submitted: December 8, 2025
• First Posted: January 5, 2026
• Study Start: January 1, 2026
• Primary Completion (Estimated): January 1, 2027
• Study Completion (Estimated): August 30, 2027
• Last Updated: January 5, 2026

Record last verified: 2025-12

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)