Primary anterior cruciate ligament repair

OVERVIEW

Chapter synopsis

Anterior cruciate ligament (ACL) repair is not new. It has mixed short- and long-term results reported. The potential benefit of proprioceptive preservation makes a successful repair very appealing in the treatment of ACL injuries. A number of arthroscopic techniques have recently been described and popularized, but none currently have sufficient clinical or biomechanical data to support widespread use.

Important points

Isolated ACL repair without augmentation has yielded inferior results to ACL reconstruction over decades of clinical evaluation.
Augmentation has shown increased rates of ACL healing and superior biomechanical properties in preclinical trials.
Augmentation with biologic scaffold has shown promising early results (2 years) with a limited number of patients.
Quality clinical studies are needed before recommending ACL repair as the gold standard.

Clinical/surgical pearls

This technique is appropriate for femoral soft tissue avulsion injuries, ideally within 2 weeks of injury.
Tibial soft tissue avulsions can also be fixed with an analogous technique.
Place separate sutures in the anteromedial bundle and posterolateral bundle to distribute the force throughout the ACL remnant.
Consider augmentation with suture bridge (discussed here) or biologic scaffolding.
Strongly consider the addition of a lateral extra-articular tenodesis to protect the ligament while healing.

Clinical/surgical pitfalls

Patient selection is key.
Consent patients for possible ACL reconstruction in case tissue quality is poor or arthroscopy reveals a midsubstance tear.
Be gentle when manipulating the sutures passed into the ACL so as not to split the ligament.
Suture management is crucial. For this, a cannula is used in the medial portal.
If using suspensory fixation on the femur (not described here), must confirm knots and button on the lateral femur are down onto bone and not within soft tissue envelope.
If using suture bridge augmentation, it must be tensioned in full extension to prevent a flexion contracture.

Introduction

Anterior cruciate ligament (ACL) injuries are common and are increasing in frequency. ^, While treatment has evolved, outcomes such as re-rupture and return to play still leave significant room for improvement. The native ACL contains mechanoreceptors located in the tibial and femoral footprints. In activities of daily living, the ACL is stressed very little, functioning the majority of the time as a proprioceptive organ feeding back subtle changes in its tension to the motor regions of the brain that can then respond with appropriate neuromuscular fine-tuning. These proprioceptive sensors are sacrificed in ACL reconstructions, leading to long-standing proprioceptive deficits. ^, ACL repair potentially allows the chance of preservation of proprioception, while simultaneously restoring mechanical stability to the knee.

Historically, ACL repair yielded good to excellent short-term results that deteriorated after 2 to 3 years. With the addition of augmentation techniques that have demonstrated faster rates of ACL healing and improved biomechanical properties, ^, there is renewed interest in ACL repair.

A well-understood variation on ACL repair is of course the re-fixation of an avulsed bony fragment from the ACL attachment on the tibia. In contrast, repair of midsubstance tears, even with augmentation, has continued to yield inferior results to reconstruction. These will not be considered in the current chapter that is devoted to repair of soft tissue avulsion from the femur. In addition, we do not undertake repair of midsubstance ruptures close to the femur as some do.

While the gold standard for treatment of ACL tears remains reconstruction with autograft, successful ACL repair with augmentation is a technique that offers potential benefits but requires significantly more short- and long-term evaluation before recommending widespread use. Its proponents argue that repair ‘burns no bridges.’ This is an unjustifiable claim; failed repair can lead to repeat injury and deterioration of the joint. Since many of the patients having ACL repair are adolescents, that is of great concern.

Pre-operative considerations

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