Courtesy: Sachin Allahabadi MD, Houston, TX

Why Do Cartilage Defects Matter?

1. Poor Healing Potential

Articular cartilage has:

Limited blood supply
Low chondrocyte density
Dense extracellular matrix
Limited cell migration capacity

Additionally:

The knee undergoes repetitive multidirectional load
Healing is mechanically and biologically challenging

2. High Prevalence

Articular cartilage defects are found in ~60% of knee arthroscopies
More common in athletes
~48% of professional basketball players show cartilage defects on MRI

Notably:

MRI findings do not always correlate with symptoms
Imaging abnormalities alone should not drive treatment decisions

Natural History

Some defects enlarge over time
Many remain asymptomatic
79% of untreated defects return to sports
Cartilage defects found during ACL reconstruction often do not affect long-term outcomes

Key Principle:

Treat the symptomatic defect — not the MRI.

Skillful Neglect

A key concept emphasized:

Not all cartilage defects require intervention
Appropriate patient counseling is critical
Understand patient goals
Manage symptoms rather than imaging findings

Core Principles in Cartilage Management

Least invasive effective treatment first
Consider recovery timelines
Identify the cause of the defect
Address:
- Alignment
- Meniscus status
- Ligament stability
Preserve the osteochondral unit

Clinical Workup

Imaging

Weight-bearing radiographs (mandatory)
Flexion weight-bearing views
Long-leg alignment films
MRI (standard)
CT scan when indicated

Patient Factors to Consider

Age and skeletal maturity
Activity level and goals
Symptom severity
Mechanical symptoms
Lesion size (absolute and relative)
Subchondral bone involvement
Lesion location
Containment

Non-Surgical Management

Appropriate when:

Symptoms are mild
MRI findings are incidental
Acute flare-ups

Options include:

Observation (“regression to the mean”)
Physical therapy
Unloader bracing
Weight reduction
Injections

Surgical Options – Simplified Algorithm

1. Chondroplasty & Debridement

Dr. Alhabadi’s first-line surgical treatment.

Benefits:

Quick procedure
Low cost
Fast recovery
Does not burn bridges
~50% may improve with debridement alone

Return to play in NFL athletes: ~67%.

2. Marrow Stimulation (Microfracture / Drilling)

Produces fibrocartilage
Outcomes deteriorate over time
Poor performance in patella
May complicate future ACI

Drilling preferred over traditional awl technique.

Microfracture-plus options:

Micronized extracellular matrix (e.g., BioCartilage)
AMIC (Autologous Matrix-Induced Chondrogenesis)

3. Single-Stage Off-the-Shelf Options

a) Cryopreserved Cartilage

b) Minced Autologous Cartilage

c) Juvenile Cartilage (e.g., DeNovo)

d) Aragonite-Based Scaffolds (e.g., CartiHeal)

Aragonite scaffold shows promising results in:

Larger defects
Subchondral bone restoration
RCT showed improved fill vs microfracture

Long-term durability remains under evaluation.

4. Osteochondral Autograft Transfer (OATS)

Best for:

Small (<1–2 cm²) symptomatic lesions
High-demand athletes

Advantages:

Hyaline cartilage
Best return-to-sport rates
Cost-effective

Limitations:

Donor-site morbidity
Difficult for large defects

5. Autologous Chondrocyte Implantation (ACI / MACI)

Two-stage procedure
Cell-based therapy
Particularly useful in patellofemoral joint
Does not address subchondral bone

Limitations:

Cost
Logistics
Requires cartilage harvest
Less effective after failed microfracture

6. Osteochondral Allograft (OCA)

Dr. Alhabadi’s primary choice for:

Large defects
Deep lesions
Bone involvement
Bipolar lesions
Revision cartilage surgery

Advantages:

Restores osteochondral unit
No donor-site morbidity
Good long-term survivorship (~82% at 10 years after prior surgery)
87.5% return to sport in professional athletes (isolated OCA)

Technical Pearls for OCA

Submerge graft during reaming to reduce thermal necrosis
Minimize subchondral bone depth (4–6 mm)
Pulse lavage graft
Use pressurized CO? to reduce immunogenic elements
Soak graft in bone marrow aspirate concentrate
Minimize impaction forces

Address the “Other” Factors

1. Ligament Stability

Chronic instability increases cartilage damage
Reconstruction improves outcomes

2. Meniscus Preservation

Essential for load distribution
Meniscus transplant yields outcomes comparable to isolated OCA

3. Alignment & Osteotomy

Osteotomy improves graft survival
Consider >5° correction in tibiofemoral compartment
Tibial tubercle osteotomy for patellofemoral lesions
Osteotomy alone may improve symptoms in selected cases

Key Takeaways

Decision-making is harder than the procedure itself
Not every defect requires surgery
Chondroplasty remains a powerful tool
Microfracture role is decreasing
ACI is valuable but limited by bone involvement
OCA is highly effective for large/deep lesions
Alignment, meniscus, and stability must be addressed
Patient expectations must be carefully managed

Final Message

Cartilage surgery requires:

Thoughtful patient selection
Honest counseling
Biological and mechanical optimization
Willingness to learn from failures

Ultimately:

“Do the least you need to do for a successful outcome.”

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