What is the recommended management for full‑thickness chondral fissuring of the knee?

Management of Full-Thickness Chondral Fissuring of the Knee

For full-thickness chondral fissuring of the knee, microfracture is the recommended first-line surgical treatment for focal, contained lesions smaller than 4 cm² in patients with minimal osteoarthritis (Tönnis grade ≤1). 1

Classification and Diagnostic Framework

Full-thickness chondral fissuring corresponds to Outerbridge Grade 4 lesions, characterized by complete loss of cartilage with exposed subchondral bone. 2 This classification system guides treatment decisions and helps predict outcomes. 1

The natural history of untreated full-thickness cartilage defects typically results in progressive disability and further cartilage loss. 3 Subchondral bone changes occur dynamically after cartilage injury, with bone resorption peaking around 14 days post-injury, followed by sclerotic changes that correlate with increased pain levels. 4

Treatment Algorithm Based on Lesion Characteristics

Lesions <4 cm² with Minimal Osteoarthritis

Microfracture is the indicated procedure, involving the following technical steps: 1

• Debride all friable cartilage using a shaver to remove unstable tissue 2
• Create a perpendicular edge of healthy, well-attached cartilage around the defect using ringed curettes 2
• Penetrate subchondral bone with an awl to create 3-4 mm deep holes spaced 3-4 mm apart 2, 1
• Preserve subchondral bone bridges between holes to maintain structural integrity 2

The mechanism relies on bringing pluripotent marrow cells and growth factors from underlying bone marrow into the defect, which form fibrocartilage to fill the lesion. 2 Studies demonstrate mean 93% ± 17% fill at second-look arthroscopy with macroscopically good-quality cartilage. 1

Lesions 2-6 cm²

• Microfracture remains first-line for acetabular lesions 1
• Mosaicplasty or single-plug osteochondral allograft should be considered for femoral head lesions 1

Lesions >6 cm²

Conversion to total joint arthroplasty should be considered in appropriate surgical candidates, as the defect size exceeds the reliable treatment threshold for cartilage repair techniques. 1

Critical Contraindications

Microfracture must NOT be performed for partial-thickness chondral delamination with an intact basal layer, as the technique requires exposed subchondral bone and is reserved exclusively for contained, full-thickness defects. 1 Attempting microfracture on partial-thickness lesions violates the fundamental principle that subchondral bone must be accessible for marrow cell recruitment.

Non-Surgical Adjuncts

Pain Management

• Acetaminophen (paracetamol) is the preferred first-line oral analgesic, though efficacy is uncertain and likely small 1
• NSAIDs can be used when acetaminophen is insufficient, but long-term use carries gastrointestinal and cardiovascular risks 1
• Intra-articular anesthetic and steroid injections serve both diagnostic and therapeutic purposes 5

Bracing and Orthoses

• Patellofemoral braces are conditionally recommended for patients with significant impact on ambulation, joint stability, or pain 1
• Kinesiotaping is conditionally recommended for knee joint involvement 1
• Optimal bracing requires clinician familiarity with various brace types and expertise in fitting 1

Interventions to Avoid

Stem cell injections for cartilage regeneration are NOT recommended due to concerns regarding heterogeneity and lack of standardization, with low-quality supporting evidence. 1

Common Pitfalls and Monitoring

The primary pitfall is attempting microfracture on inappropriate lesions—either those with intact basal cartilage layers or those in patients with advanced osteoarthritis (Tönnis grade >1). 1 The subchondral bone plate must be exposed and intact for the procedure to succeed. 2

Long-term monitoring is essential as chondromalacia may progress to osteoarthritis if not properly managed. 1 Patients with more extensive cartilage damage have less favorable outcomes and may require additional interventions. 5

At second-look arthroscopy, the wave sign (indicating chondral delamination) resolves in approximately 85% of successfully treated cases. 6 Persistent delamination at revision is associated with residual impingement, age ≥58 years, or delayed revision >6 months. 6

The repair tissue formed after microfracture is fibrocartilage rather than native hyaline cartilage, which is less durable and smooth than the original tissue. 7 However, this fibrocartilage can achieve biomechanical properties similar to normal articular cartilage by 12 weeks post-procedure. 8