Magnetic Resonance Imaging and Functional Performance Outcome After ACL Repair With Internal Brace Technique

Lesions of the anterior cruciate ligament (ACL) are the most common ligamentous injuries with an increasing incidence. 77% of ACL insufficient knees result in moderate to high physical limitations. Different surgical treatments have been described. ACL reconstruction with either a semitendinosus or patella tendon graft is regarded as the gold standard of operative therapy. Despite numerous studies representing good and excellent outcome after ACL reconstruction, a recent Meta-analysis of Biau et al. 2006 revealed that only 40% of patients gain full functional recovery.

Since the native ACL is considered to be an important factor for the proprioceptive sensation, a removal during the reconstruction might have an adverse influence on muscular stabilisation, rehabilitation and functional performance of the knee joint. Thus a primary repair of the native ACL seems reasonable.

For tears of the anterior cruciate ligament near the femoral attachment a new method of surgical treatment can be applied. The InternalBrace method by Arthrex is performed arthroscopically and involves reattaching of the ACL that has avulsed off the femoral wall using a FiberTape by Arthrex. To the authors knowledge the augmentation with FiberTape by Arthrex has not been systematically evaluated. Promising results have been presented recently using a comparable method, which showed a high patient satisfaction, faster rehabilitation and a high rate of return to pre-injury sports level.

To assess the functional performance, a further aim of the study is to develop a new test battery consisting of strength tests and single-leg hop tests with the ability to distinguish between the functional performance of the injured and the uninjured leg in patients with ACL deficiency. Test batteries consisting of several hop tests has been described in the previous literature indicating a good test-retest reliability measuring lower leg performance. The functional performance is defined using the limb symmetry index in percent between each individuals lower limbs. This study aims to determine the LSI of healthy subjects using the values achieved by the subjects in the control group. A limb symmetry index (LSI) between 85% and 95% is considered sufficient for return to pivoting sports in patients after knee injury.

Inclusion criteria

• Female and male subjects
• Age between 18 and 60 years
• Patients who sustained an isolated rupture of the anterior cruciate ligament at least 12 month after injury (for the subjects who received conservative therapy), respectively surgery (for the two groups in which subjects underwent surgery)
• MRI-confirmed tear of the anterior cruciate ligament near the femoral attachment
• Surgical treatment of the InternalBrace group must have been performed within the first six weeks after injury
• Women of reproductive age
• Confirmed written consent of each subject

Exclusion criteria

• Injury to the other knee
• Previous knee injuries which required treatment
• Concomitant injuries such as fractures, articular cartilage lesions reaching subchondral bone, meniscal tears or lesions of the collateral ligaments which required an additional surgical intervention and therefore an extended post-op rehabilitation protocol
• Pregnant and nursing women
• Claustrophobia
• Existing contraindication against performing an MRI scan
• Taking certain concomitant medication(s) (especially cortisone), or conditions that interfere with a patient's ability to comply with all procedures
• Circumstances that interfere with the participant's ability to give informed consent (diminished understanding or comprehension, or a language other than German or English spoken