Meniscus repair

The meniscus is a crucial fibrocartilaginous structure in the knee that contributes to joint stability, load distribution, and shock absorption. Meniscus tears are common injuries that can result in pain, mechanical symptoms, and long-term joint degeneration. Meniscus repair aims to restore its function and prevent osteoarthritis.

Anatomy of the Meniscus

Gross Anatomy

The knee contains two menisci: medial and lateral. These crescent-shaped structures sit between the femoral condyles and tibial plateau, conforming to the joint surfaces and facilitating smooth movement.

• Medial meniscus: C-shaped, more firmly attached to the joint capsule, and less mobile.
• Lateral meniscus: O-shaped, more mobile, and covers a larger portion of the lateral tibial plateau.
• Attachments: Anchored anteriorly and posteriorly to the tibial plateau and connected to the joint capsule at the periphery.

Vascular Supply and Zones

Blood supply to the meniscus is limited and varies by region, influencing healing potential after injury.

• Red-red zone: Outer third with good vascularity, high healing potential.
• Red-white zone: Middle third with intermediate vascularity, moderate healing potential.
• White-white zone: Inner third with minimal vascularity, poor healing potential.

Innervation and Function

Menisci are innervated primarily at the periphery and contain mechanoreceptors important for proprioception. Functionally, they provide:

• Load distribution and shock absorption during weight-bearing.
• Joint stability and congruity between femoral and tibial surfaces.
• Proprioceptive feedback contributing to coordinated knee movement.

Pathophysiology of Meniscal Tears

Types of Tears

Meniscal tears can vary in pattern, size, and displacement, affecting treatment decisions.

• Longitudinal tears: parallel to the circumferential fibers.
• Radial tears: perpendicular to the circumferential fibers, often disrupting hoop stress.
• Horizontal tears: split the meniscus into superior and inferior portions.
• Flap tears: unstable fragments that can cause mechanical symptoms.
• Complex tears: combination of patterns, often degenerative.
• Bucket-handle tears: displaced longitudinal tears causing joint locking.

Etiology

• Traumatic tears: Typically occur in young, active individuals due to twisting or impact injuries.
• Degenerative tears: Occur in older adults due to chronic wear and reduced meniscal integrity.

Consequences of Meniscal Injury

• Altered knee biomechanics leading to abnormal load distribution.
• Increased risk of early osteoarthritis due to loss of shock absorption.
• Joint instability, pain, swelling, and mechanical symptoms such as locking or catching.

Clinical Presentation

Symptoms

Patients with meniscal tears typically present with a combination of pain, mechanical symptoms, and functional limitations.

• Knee pain, often localized to the joint line.
• Swelling or effusion, particularly after activity.
• Locking, catching, or a sensation of the knee giving way.
• Reduced range of motion and difficulty with squatting or twisting movements.

Physical Examination

Examination of the knee helps localize the tear and assess associated ligamentous injury.

• Joint line tenderness, medial or lateral, depending on tear location.
• McMurray’s test: pain or clicking with rotation and flexion-extension of the knee.
• Thessaly test: reproduction of pain during single-leg stance with rotation.
• Apley’s grind test: pain with compression and rotation of the tibia while prone.
• Assessment of overall knee stability, including ligament testing.

Diagnostic Evaluation

Imaging

Imaging studies are essential to confirm the diagnosis, characterize the tear, and plan treatment.

• MRI: Gold standard for non-invasive evaluation of tear type, location, and tissue quality.
• X-ray: Useful to rule out concomitant bony injury or osteoarthritis.
• Ultrasound: Occasionally used to evaluate peripheral meniscal tears.

Arthroscopy

Arthroscopy is both a diagnostic and therapeutic tool for meniscal tears.

• Direct visualization of tear pattern, size, and tissue quality.
• Assessment of repairability based on location, vascularity, and tissue integrity.
• Allows simultaneous repair or partial meniscectomy if indicated.

Indications and Contraindications for Meniscus Repair

Indications

Meniscus repair is considered when there is a reasonable likelihood of healing and restoration of function.

• Tear located in the red-red or red-white vascular zones.
• Longitudinal or bucket-handle tear patterns with preserved tissue quality.
• Young, active patients with high functional demands.
• Associated ligament reconstruction, such as anterior cruciate ligament (ACL) repair, which improves healing potential.

Contraindications

Meniscus repair is not recommended in certain situations due to poor healing potential or high risk of failure.

• Degenerative or complex tears in older adults.
• White-white zone tears with minimal vascularity.
• Advanced osteoarthritis or significant joint degeneration.
• Poor patient compliance with postoperative rehabilitation protocols.

Surgical Techniques for Meniscus Repair

Inside-Out Technique

This traditional method involves passing sutures from the inner meniscus through the capsule to the outside of the knee.

• Provides strong fixation for tears in the posterior horn.
• Requires small posterior incisions to retrieve sutures.
• Advantages include reliable healing and low risk of suture loosening; limitations include more invasive approach.

Outside-In Technique

Used primarily for anterior horn and mid-body tears, this technique passes sutures from outside the capsule into the meniscus.

• Less invasive than inside-out for anterior tears.
• Reduces risk to neurovascular structures compared to posterior sutures.
• Suitable for small to moderate tears in accessible locations.

All-Inside Technique

This minimally invasive method uses specialized devices to place sutures entirely within the joint.

• Eliminates the need for accessory incisions.
• Shorter operative time and less postoperative pain.
• Device cost may be higher; appropriate for posterior horn tears.

Repair Augmentation

Biological and mechanical enhancements can improve healing in select cases.

• Fibrin clot or platelet-rich plasma to promote vascularization.
• Scaffold materials for tissue regeneration.
• Used in combination with standard repair techniques for challenging tears.

Postoperative Management

Rehabilitation Protocols

Successful meniscus repair depends on structured rehabilitation to protect the repair and restore function.

• Weight-bearing status: Partial or non-weight-bearing initially, progressing as healing permits.
• Range of motion exercises: Controlled flexion and extension to prevent stiffness while protecting the repair.
• Strengthening exercises: Quadriceps, hamstrings, and hip musculature to support knee stability.
• Proprioception training: Balance and neuromuscular exercises to restore joint control.

Return to Activity

Return to sports or high-demand activities is guided by tissue healing and functional recovery.

• Light activities typically allowed at 6-8 weeks postoperatively.
• Progressive strengthening and sport-specific drills between 3-6 months.
• Full return to competitive sports usually at 6 months, depending on tear type and repair quality.

Outcomes and Complications

Success Rates

Meniscus repair generally provides favorable outcomes, particularly for tears in well-vascularized zones.

• Healing rates are higher for red-red and red-white zone tears.
• Bucket-handle and longitudinal tears have better repair success than complex or degenerative tears.
• Concurrent ACL reconstruction improves healing potential.

Complications

Although relatively safe, meniscus repair carries potential risks that should be discussed with patients.

• Infection, though rare, can occur at portal or incision sites.
• Stiffness or loss of knee motion.
• Re-tear of the repaired meniscus, especially with early return to high-impact activities.
• Neurovascular injury, particularly with inside-out techniques near posterior structures.

Long-Term Prognosis

Successful meniscus repair preserves knee function and reduces the risk of osteoarthritis compared to meniscectomy.

• Maintains load distribution and shock absorption.
• Improves long-term joint stability and activity levels.
• Early intervention and adherence to rehabilitation protocols enhance outcomes.

Recent Advances and Future Directions

Biological Augmentation and Tissue Engineering

Recent innovations aim to enhance meniscus healing using biological materials and regenerative techniques.

• Use of platelet-rich plasma or growth factors to stimulate vascularization and tissue repair.
• Scaffold materials and hydrogels to support cellular ingrowth and matrix regeneration.
• Stem cell therapies for meniscal regeneration in complex or avascular tears.

Minimally Invasive Techniques

Advancements in arthroscopic instruments and repair devices have improved safety and outcomes.

• All-inside repair devices with improved suture anchors and deployment systems.
• Enhanced visualization and access with high-definition arthroscopy.
• Reduced operative time and postoperative pain compared to traditional techniques.

Improved Repair Devices and Suture Materials

Technological improvements in suture materials and fixation devices have increased repair strength and reliability.

• Ultra-high-strength sutures that reduce risk of pull-out or loosening.
• Bioabsorbable anchors and implants for secure fixation without long-term foreign material.
• Customizable devices for different tear patterns and locations.

References

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