Treatment of Full-Thickness Chondral Fissure of the Knee
Microfracture is the recommended first-line treatment for full-thickness chondral fissures of the knee when the lesion is focal, contained, and less than 4 cm² in patients with minimal osteoarthritis. 1, 2
Patient Selection Criteria
Before proceeding with any joint-preserving intervention, verify the patient meets these specific criteria 2:
- Age: Skeletal maturity to 50 years
- Osteoarthritis status: Minimal or no signs (Tönnis grade ≤1) 1
- Lesion characteristics: Full-thickness defect without bipolar involvement
- Functional capacity: Ability to perform rigorous postoperative physical therapy
- Inflammatory status: No inflammatory arthritis present
Treatment Algorithm Based on Lesion Size
Lesions <2 cm²
Microfracture is the definitive first-line treatment 1, 2. This technique achieves a mean 93% ± 17% defect fill with good-quality cartilage macroscopically at second-look arthroscopy 3, 1.
Lesions 2-6 cm²
- Femoral condyle/trochlear lesions: Microfracture remains first-line 1
- Femoral head lesions: Consider mosaicplasty or single-plug osteochondral allograft 1
- Acetabular lesions: Microfracture is preferred 1
Lesions >6 cm²
Conversion to total knee arthroplasty should be considered in appropriate candidates 1.
Microfracture Surgical Technique
The procedure follows this specific sequence 3:
- Debridement phase: Remove all friable cartilage using a shaver
- Edge preparation: Use ringed curets to create a well-contained lesion with perpendicular edges of healthy, well-attached cartilage
- Awl placement: Create 3-4 mm deep perpendicular holes in subchondral bone, spaced 3-4 mm apart to preserve subchondral bone bridges between holes
- Endpoint: Continue until bleeding is visualized from the marrow spaces
The mechanism works by releasing pluripotent marrow cells and growth factors from underlying bone marrow, which form fibrocartilage to fill the defect 3.
Expected Outcomes
Clinical improvement is substantial and sustained 4, 5:
- Pain reduction: Visual analog scale scores improve from mean 69.5 preoperatively to 11 postoperatively at 3.8-year follow-up 4
- Functional improvement: Lysholm scores increase from 73.7 to 86.1 4
- Structural fill: 93% defect fill with good-quality cartilage at second-look arthroscopy 3
Critical Caveats
Athletic patients face specific limitations 5. While 70% achieve good clinical and functional improvement, 80% show decline in sports participation over time at final follow-up, suggesting microfracture may not be definitive for high-level athletes and future procedures may be needed 5.
Avoid stem cell injections as the American College of Rheumatology/Arthritis Foundation does not recommend them due to heterogeneity and lack of standardization 1, 2.
Long-term monitoring is mandatory as chondromalacia may progress to osteoarthritis if not properly managed 1.
Adjunctive Conservative Management
While conservative treatment serves primarily as a temporizing measure and does not address the underlying cartilage defect 1, consider:
- First-line analgesia: Paracetamol (acetaminophen), though efficacy is uncertain and likely small 1
- Second-line analgesia: NSAIDs when paracetamol insufficient, but recognize long-term gastrointestinal and cardiovascular risks 1
- Bracing: Patellofemoral braces for significant impact on ambulation, joint stability, or pain 1