Clinical and Functional Outcomes After ACL Reconstruction Versus Primary Repair

NCT ID: NCT07318272

Last Updated: 2026-01-05

Basic Information

• Recruitment Status: NOT_YET_RECRUITING
• Total Enrollment: 45 participants
• Study Classification: OBSERVATIONAL
• Study Start Date: 2026-01-01
• Study Completion Date: 2027-08-30

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.

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

Study Design

• Observational Model Type: OTHER
• Study Time Perspective: PROSPECTIVE

Study Groups

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.

No interventions assigned to this group

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.

No interventions assigned to this group

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.

No interventions assigned to this group

Eligibility Criteria

Inclusion Criteria

• 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

• 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

Exclusion Criteria

• 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

• 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

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 40 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Gazi University

OTHER

Sponsor Role: lead

Responsible Party

Dudu Özdemir

MSc.

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Nihan Karatas, Prof. Dr.

Role: STUDY_DIRECTOR

Gazi University

Dudu Ozdemir Can, MSc

Role: PRINCIPAL_INVESTIGATOR

Gazi University

Locations

Gazi University Faculty of Health Sciences Department of Physiotherapy and Rehabilitation

Ankara, Çankaya, Turkey (Türkiye)

Countries

Turkey (Türkiye)

Central Contacts

Dudu Ozdemir Can, Msc

Role: CONTACT

duduozdemir@gazi.edu.tr

90 5534448492

Facility Contacts

Dudu Ozdemir Can, MSc

Role: primary

duduozdemir@gazi.edu.tr

90 5534448492

References

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.

Reference Type: BACKGROUND

PMID: 30822124 (View on PubMed)

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.

Reference Type: BACKGROUND

PMID: 34501400 (View on PubMed)

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.

Reference Type: BACKGROUND

PMID: 38867918 (View on PubMed)

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.

Reference Type: BACKGROUND

PMID: 31919026 (View on PubMed)

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.

Reference Type: RESULT

PMID: 32977649 (View on PubMed)

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.

Reference Type: RESULT

PMID: 37925800 (View on PubMed)

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.

Reference Type: RESULT

PMID: 38557260 (View on PubMed)

Other Identifiers

Gazi2025

Identifier Type: -

Identifier Source: org_study_id