Knee Cartilage and Meniscal Injury

This page is the dedicated Knee sub-section for cartilage and meniscal injury. It summarizes the new source document and focuses on triage, tissue preservation, and when surgery is genuinely appropriate.

Primary resources:

• Knee Meniscus and Cartilage reference library (PDFs)
• Knee cartilage and meniscal injury source document
• Back to Knee Overview

The Evolution of Meniscal Thinking

The historical story is important: the meniscus was once considered expendable, and total meniscectomy became standard practice because it was thought to prevent later degeneration. That understanding reversed after long-term follow-up showed that removing meniscal tissue actually increases joint loading, accelerates degenerative change, and exposes the articular cartilage to earlier failure.

Modern teaching should therefore emphasize meniscal preservation whenever realistically possible. Arthroscopy still has a role, but routine arthroscopic partial meniscectomy for degenerative tears has been heavily challenged by high-level trials showing that structured rehabilitation is commonly non-inferior to surgery in non-obstructive degenerative tears.

Articular Cartilage Across the Lifespan

• Children and adolescents: cartilage is thicker, more cellular, and has better intrinsic repair potential. Important presentations include osteochondritis dissecans, acute osteochondral injury, and discoid meniscus-related problems.
• Younger and middle-aged adults: mature cartilage is avascular and has limited healing potential, so focal traumatic defects, chondral flaps, and osteochondral lesions can become persistent sources of pain, swelling, and mechanical symptoms.
• Older adults: matrix dehydration, chondrocyte senescence, and degenerative meniscal tearing become more common, often alongside osteoarthritis and mixed symptom patterns.

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Pathology and Classification

Cartilage and meniscal presentations are easier to understand when divided into broad clinical buckets:

• Acute traumatic lesions: a clear injury event, rapid swelling, and more sharply defined structural lesions such as osteochondral fractures, unstable meniscal tears, or acute chondral injury.
• Chronic overload or repetitive impaction lesions: cartilage thinning, matrix disruption, and wear-related symptoms that develop gradually.
• Joint disorder presentations: osteochondritis dissecans, osteoarthritis, inflammatory disease, or mixed degenerative states where the meniscal change may not be the dominant pain driver.

For meniscal lesions, the key teaching distinction is between:

• General knee pain plus a meniscal tear: often not enough to justify surgery on its own.
• A non-osteoarthritic knee with a clearly unstable tear and matching mechanical symptoms: this is the classic group where arthroscopic treatment may be more justified.
• Advanced structural osteoarthritis: meniscal surgery is usually inappropriate because the arthritic joint is the real problem.

High-Yield Clinical Profiles

Locked Knee

A true locked knee with inability to extend is a different triage category from vague clicking or intermittent pain. This pattern suggests a displaced tear, often a bucket-handle lesion, and usually warrants urgent orthopaedic review.

Acute Injury with a Target Lesion

Young, active patients with an acute twist, hemarthrosis, joint-line pain, and compatible MRI findings may have a meniscal lesion with real repair potential. The preservation question matters more than the simple question of whether surgery is possible.

Degenerative Tears

In middle-aged and older adults, degenerative tears frequently coexist with osteoarthritis and may be incidental. Mechanical words in the history do not automatically mean the meniscus is the dominant pain generator. This is the setting where trials repeatedly show that good rehabilitation competes very well with arthroscopy.

Cartilage Lesions

Chondral and osteochondral lesions more often present with effusion, stiffness, pain with loading, and true intra-articular symptoms. In younger patients, osteochondral injury and OCD deserve a higher index of suspicion; in older patients, cartilage loss is more likely to be part of an osteoarthritic continuum.

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Management Principles

• Start with classification: decide whether the patient has a repairable traumatic lesion, a likely incidental degenerative tear, a cartilage lesion, or established osteoarthritis.
• Use optimized non-surgical care first for most non-locked degenerative cases: progressive exercise, quadriceps/hamstring/calf strength work, balance, activity modification, and symptom control.
• Do not let MRI dictate treatment in isolation: imaging findings often outstrip symptoms.
• Reserve arthroscopy carefully: especially for locked knees, unstable target lesions, and selected non-osteoarthritic mechanical tears that have failed a reasonable trial of rehabilitation.
• In advanced OA: arthroscopy is rarely helpful; management should target the arthritic joint instead.

Optimized Non-Surgical Care

• Structured physiotherapy: strength, endurance, mobility, and graded reloading.
• Education and load modification: reduce provocative pivoting, deep flexion, or impact while maintaining useful activity.
• Symptom management: temporary bracing, gait aids, ice or heat, simple analgesia, and selected injections when appropriate.
• OA overlap: weight management and longer-term exercise adherence matter when cartilage degeneration is part of the picture.

Special Presentations

Meniscal Root Lesions

Root tears behave very differently from ordinary small meniscal tears because loss of the root disrupts hoop stress transmission and makes the knee behave biomechanically more like it has undergone a total meniscectomy. This is why untreated root tears are associated with rapid cartilage overload and arthritic progression.

• Lateral root tears: more often traumatic and associated with ACL injury in younger patients.
• Medial posterior root tears: more often degenerative, lower-energy, and seen in middle-aged or older adults with varus alignment, increased BMI, or existing OA.
• MRI clues: truncation sign, ghost sign, radial signal at the root, and meniscal extrusion.

Discoid Meniscus

A discoid meniscus is a congenital shape variant, usually lateral, that is more prone to tearing and instability. Many are asymptomatic, but symptomatic cases can produce snapping, locking, pain, and extension block in children or adolescents. The modern goal is again preservation, typically with saucerization plus repair or stabilization when required.

Patient-Friendly Framing

When people hear “torn meniscus” or “cartilage damage,” they often assume surgery is unavoidable. Usually that is not true. Many meniscal changes are part of aging and can appear on MRI even when they are not the main pain source. The more useful questions are: Is the knee truly locked? Is there a repairable traumatic lesion? Is osteoarthritis the bigger driver? What can the knee currently tolerate?

For many patients, the best first step is not an operation but a carefully structured rehabilitation plan that improves strength, confidence, movement quality, and symptom tolerance. Surgery becomes more compelling when the knee is mechanically blocked, clearly unstable, or the tissue can realistically be preserved and repaired.

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