Knee cartilage damage is frustrating because it does not behave like muscle or skin. Articular cartilage has limited ability to heal on its own, so a “small spot” can remain a persistent source of swelling, catching, reduced performance, and eventually broader joint wear. That is why procedures such as microfracture, osteochondral autograft transfer, and matrix-induced autologous chondrocyte implantation exist—each aiming to restore a smoother joint surface and protect the knee over the long term.⁽⁷⁾

But these are not interchangeable. The best choice depends on defect size, defect depth, whether bone is involved, the exact knee location, and patient factors such as age, activity level, alignment, and ligament stability. A technique that performs well for a small, contained defect on the femoral condyle can be a poor match for a large lesion, a patella lesion, or a defect with underlying bone loss.^(7)(14)

This guide is written to help readers understand how surgeons commonly match each cartilage repair to the defect—so you can ask better questions and recognize why different knees get different procedures.

Quick orientation: what is a “knee cartilage defect”?

A knee cartilage defect is a localized area where the smooth articular cartilage surface has been damaged. It may be:

Partial thickness (surface fraying or fissuring)
Full thickness (the defect reaches the bone underneath)
Osteochondral (both cartilage and underlying bone are involved)

Cartilage repair procedures are usually considered when symptoms persist despite appropriate non-surgical care and when the defect is focal rather than widespread degenerative arthritis.⁽⁷⁾

Two concepts shape nearly every treatment decision:

1) Defect size and containment:

Smaller, well-contained defects generally have more options and better predictability. Outcomes for some techniques worsen as defects get larger. Microfracture outcomes, in particular, have been linked to lesion size, with smaller lesions tending to do better.^(0)(15)

2) What type of cartilage you are likely to get back:

Not all repairs recreate native “hyaline-like” cartilage. Microfracture stimulates a repair clot from bone marrow that tends to mature into fibrocartilage, which differs from native hyaline cartilage in structure and collagen composition.⁽¹⁵⁾ Osteochondral autograft transfer moves living hyaline cartilage and its underlying bone plug into the defect immediately.⁽⁷⁾ Matrix-induced autologous chondrocyte implantation uses a two-step cell-based method designed to restore a more hyaline-like surface architecture.^(6)(14)

The three main options—defined in plain language

Microfracture

Microfracture is a marrow stimulation technique. Small perforations are made in the bone underneath the cartilage defect to recruit marrow cells and form a repair clot.⁽¹⁵⁾ The repaired tissue is typically fibrocartilage rather than native hyaline cartilage, which has implications for durability in higher-demand knees.⁽¹⁵⁾

Osteochondral autograft transfer

Osteochondral autograft transfer involves taking small cylindrical plugs of cartilage-and-bone from a lower-load area of the knee and transplanting them into the defect. This provides an immediate fill with mature hyaline cartilage at the surface and structural bone underneath.⁽⁷⁾ It is also commonly referred to as mosaicplasty when multiple small plugs are used to fill a larger area.⁽²⁰⁾

Matrix-induced autologous chondrocyte implantation

Matrix-induced autologous chondrocyte implantation is a two-stage technique. Cartilage cells are harvested, cultured, and then implanted on a scaffold (matrix) to repair the defect. This approach is typically considered for larger full-thickness defects when other options are less suitable.^(10)(14)

Why “defect matching” matters more than the procedure name

If you only remember one idea, make it this: cartilage repair is defect-specific. Modern cartilage care is less about “best surgery overall” and more about “best fit for this exact lesion in this exact knee.” Reviews of knee cartilage restoration emphasize tailoring the method based on lesion depth and size, location, and patient factors.⁽⁷⁾⁽³⁾

Microfracture: best fit, weak fit, and what it is really repairing

When microfracture tends to fit best

Microfracture is usually considered for:

Small, contained full-thickness cartilage defects
Patients who can commit to a protected rehabilitation phase
Knees without major malalignment or instability

Clinical reviews consistently highlight that smaller lesions tend to have better outcomes after microfracture than larger ones.^(0)(15)

Why defect size matters so much in microfracture

Microfracture creates a fibrocartilage repair tissue that is biologically different from native hyaline cartilage.⁽¹⁵⁾ As defect size grows, it becomes harder for that repair tissue to withstand joint forces over time, and durability concerns rise.^(0)(19)

A practical takeaway for readers: microfracture is often discussed as a first-line surgical option for smaller focal defects, especially when cost, simplicity, and single-stage surgery matter—but long-term durability can be less predictable in larger lesions or high-demand athletes. ^(0)(15)

When microfracture is often a weak match

Microfracture may be less ideal when:

The defect is larger
The knee has high-demand athletic goals requiring durable surface properties
There is significant underlying bone involvement or an osteochondral lesion
The knee has unaddressed alignment or ligament problems

These are not absolute rules, but they reflect the general direction of outcome patterns and technique biology described in the literature.^(0)(15)(7)

Microfracture rehabilitation is not optional

Microfracture success depends heavily on protecting the developing repair clot early. That typically means a structured rehabilitation plan with restricted weight-bearing and carefully staged range-of-motion progression. Technique reviews stress that rehabilitation quality is central to outcomes.⁽¹⁵⁾

Osteochondral autograft transfer: when moving “real cartilage” makes the most sense

What osteochondral autograft transfer does exceptionally well

Osteochondral autograft transfer is attractive because it immediately fills the defect with mature hyaline cartilage and supporting bone from the patient’s own knee.⁽⁷⁾ For the right defect, it is a powerful “structural” solution.

Ideal defect profile for osteochondral autograft transfer

This procedure is commonly matched to:

Small-to-moderate focal cartilage defects
Especially when a durable hyaline cartilage surface is desired
Lesions where bone support is beneficial (osteochondral component)

A widely cited technique review notes that the treated area for osteochondral autograft transfer should generally not exceed about 4 square centimeters, and it flags donor-site morbidity as an important limitation.⁽⁷⁾

That size guidance is not a hard universal cutoff, but it captures the central issue: you cannot take unlimited donor plugs without consequences, and larger defects can push the technique beyond its practical limits.⁽⁷⁾

What makes osteochondral autograft transfer a weaker match

Osteochondral autograft transfer can be less ideal when:

The defect is too large (donor tissue becomes limiting)
The defect shape or location makes perpendicular access difficult (plug seating matters)
There is concern about donor-site pain or morbidity

Longer-term outcome reporting supports that mosaicplasty or osteochondral autograft transfer can improve subjective outcomes for many patients, with some studies reporting improvements lasting up to a decade in appropriate candidates.⁽¹⁾

A key nuance: surface congruity and plug alignment

For osteochondral autograft transfer, plug height and flush seating are critical because you are reconstructing a weight-bearing surface. Technique discussions emphasize restoring articular contour and contact pressures by ensuring proper access and plug alignment.⁽⁷⁾

Matrix-induced autologous chondrocyte implantation: where larger defects start to change the equation

Why cell-based repair enters the conversation

When defects are larger, marrow stimulation may struggle with durability, and osteochondral autograft transfer may be limited by donor tissue availability. This is where matrix-induced autologous chondrocyte implantation becomes more relevant.^(10)(14)

Typical situations where matrix-induced autologous chondrocyte implantation fits well

Matrix-induced autologous chondrocyte implantation is commonly considered for:

Isolated symptomatic full-thickness cartilage defects
Patients who have failed non-surgical care
Larger defects, especially when the goal is durable resurfacing^(6)(10)

A detailed review of autologous chondrocyte implantation indications describes this approach as particularly suited for cartilage defects starting around three to four square centimeters and above, especially in young, active patients with focal defects rather than diffuse degenerative disease.⁽¹⁰⁾

Other contemporary reviews note that cell-based cartilage repair, including matrix-induced autologous chondrocyte implantation, has been recommended for large defects and can be used for substantially larger surface areas in selected cases.⁽¹⁴⁾

What patients should know about “two-stage” reality

Matrix-induced autologous chondrocyte implantation is generally a two-stage pathway:

Cartilage biopsy/harvest
Implantation after cell expansion on a matrix scaffold

That means more planning and typically higher cost than microfracture, but it can expand what is treatable when lesions are larger.^(6)(14)

Outcomes and durability considerations

Clinical reports describe improved functional scores after matrix-induced autologous chondrocyte implantation in appropriately selected patients, including moderate-to-large defect sizes.⁽²⁾ Long-term reporting also highlights good outcomes and relatively low revision rates in many cohorts, while noting that factors such as body mass index and patient selection influence results.⁽²⁵⁾

The “fit” framework: how surgeons commonly decide between these three

Below is the practical decision logic that appears repeatedly in technique and management reviews.

1) Start with defect size: small, medium, or large

Small defect (often under about 2 square centimeters): microfracture may be considered when contained and when expectations match fibrocartilage repair biology.^(0)(15)
Small-to-moderate defect (often around 1 to 4 square centimeters): osteochondral autograft transfer is commonly considered, particularly when a hyaline cartilage surface is prioritized and donor availability is sufficient.⁽⁷⁾
Larger defect (often above about 3 to 4 square centimeters): matrix-induced autologous chondrocyte implantation becomes more relevant, as described in indication-focused reviews of autologous chondrocyte implantation.^(10)(14)

These size bands overlap because real knees are messy: location, bone involvement, and patient goals can shift the recommendation.

2) Next ask: is bone involved?

If there is an osteochondral component (cartilage plus bone damage), a bone-and-cartilage plug approach can be attractive because it restores both layers at once.⁽⁷⁾
Microfracture stimulates repair from bone but does not replace missing structural bone in a way that matches osteochondral transplantation.⁽¹⁵⁾

3) Location matters: femoral condyle is not the same as patella

Defect location affects contact pressures, tracking forces, and surgical access. It also affects which technique is technically easier and more predictable. Broad cartilage restoration reviews emphasize the importance of lesion location as a selection factor.⁽⁷⁾

4) The knee must be “set up” for success

Cartilage repair is not done in isolation. Malalignment, ligament instability, and meniscus deficiency can overload a repaired surface and contribute to failure. Treatment trend reviews emphasize the importance of addressing concomitant issues when managing cartilage defects.⁽²²⁾

Best-fit scenarios: common real-world examples readers search for

“I have a small focal cartilage defect in the femoral condyle”

For a small, contained full-thickness lesion, microfracture may be considered, especially when the patient can follow protective rehabilitation and accepts fibrocartilage repair biology.^(15)(0) If a more durable hyaline cartilage surface is preferred and the defect size is appropriate, osteochondral autograft transfer may be considered.⁽⁷⁾

“I have a medium defect and want to return to sport”

Medium-sized lesions often push clinicians to weigh osteochondral autograft transfer versus cell-based options depending on the exact size, location, and goals. Osteochondral autograft transfer offers immediate hyaline cartilage transfer but is limited by donor tissue and defect size.⁽⁷⁾ Autologous chondrocyte implantation approaches are often discussed as defect size increases beyond the smaller range.⁽¹⁰⁾

“My defect is large, and microfracture was discouraged”

That is a common story because microfracture outcomes are influenced by defect size and the fibrocartilage nature of the repair tissue.^(0)(15) For larger full-thickness defects, matrix-induced autologous chondrocyte implantation is frequently considered as part of the cartilage restoration toolbox.^(10)(14)

“I have been told I need mosaicplasty”

Mosaicplasty is a form of osteochondral autograft transfer using multiple small plugs. It is a well-described technique and is commonly positioned for focal defects where donor site and defect size make it feasible.^(20)(7)

Recovery expectations: why rehabilitation differs across procedures

Readers often underestimate how much the recovery plan influences outcomes.

Microfracture recovery: protect the clot early

Because microfracture relies on a marrow-derived clot that remodels into repair tissue, early overload can compromise fill and quality. Technique descriptions highlight the importance of rehabilitation protocols.⁽¹⁵⁾

Osteochondral autograft transfer recovery: protect integration and contour

The transplanted plugs must incorporate and maintain surface congruity. Proper seating and stable integration are emphasized in technique discussions, and rehabilitation is planned to protect the repair while restoring function.⁽⁷⁾

Matrix-induced autologous chondrocyte implantation recovery: protect the implant and maturation

Cell-based implants require time for integration and maturation. Long-term outcomes are strongly influenced by patient selection and adherence to structured rehabilitation.^(25)(14)

Common reasons cartilage repairs fail (and how to reduce the risk)

1) The wrong technique for the defect

A mismatch between defect size and repair biology can lead to inferior durability. The lesion-size effect is well described for microfracture.^(0)(15)

2) Uncorrected alignment or instability

Even a well-done repair can be overloaded by a bow-legged or knock-kneed alignment pattern or by ligament instability. Management reviews highlight the need to address concomitant pathologies.⁽²²⁾

3) Meniscus problems that raise contact pressure

Meniscus deficiency increases focal contact forces. If the meniscus is compromised, restoring cartilage without addressing meniscus status may reduce the chance of long-term success.^(7)(22)

4) Rehabilitation that is too aggressive too early

Microfracture is the clearest example, but all cartilage repairs require staged loading.⁽¹⁵⁾

Frequently asked questions people type into search

Is microfracture “outdated” for knee cartilage repair?

Microfracture remains widely used, particularly for small focal defects, but its limitations are well described—especially for larger lesions and high-demand patients—because the repair tissue differs from native cartilage.^(15)(0)

Is osteochondral autograft transfer better than microfracture?

It depends on the defect. Osteochondral autograft transfer can provide immediate hyaline cartilage transfer and structural support, but it is limited by donor tissue availability and is commonly recommended for defects that do not exceed a certain size range.⁽⁷⁾

When is matrix-induced autologous chondrocyte implantation preferred?

It is commonly discussed for larger full-thickness defects, particularly when other techniques are not ideal due to size or durability concerns. Reviews of autologous chondrocyte implantation indications commonly place it in the larger defect category.^(10)(14)

Can these procedures prevent osteoarthritis?

Cartilage restoration aims to reduce symptoms and improve function and may help delay progression in the right setting, but it is not a guaranteed prevention strategy. Untreated lesions can progress, and broader joint factors (alignment, meniscus, body weight) still matter.^(4)(22)

Bottom line: which cartilage repair fits which knee defect?

Think in “fit” rather than hype:

Microfracture tends to fit small, contained full-thickness cartilage defects when the knee environment is favorable and the patient can follow a protective rehabilitation plan, understanding that the repair tissue is typically fibrocartilage.^(15)(0)
Osteochondral autograft transfer tends to fit small-to-moderate focal defects where restoring an immediate hyaline cartilage surface is valuable and defect size is within donor tissue limits, commonly discussed around not exceeding about 4 square centimeters for practicality and morbidity concerns.^(7)(20)
Matrix-induced autologous chondrocyte implantation tends to fit larger full-thickness defects, especially when the goal is more durable resurfacing and donor tissue limitations make osteochondral autograft transfer less suitable; indication-focused reviews often discuss autologous chondrocyte implantation beginning around three to four square centimeters and above in appropriate patients.^(10)(14)(25)

If you are choosing between these procedures, the most useful next step is not asking “Which is best?” but asking: What is the exact defect size, depth, and location—and what knee factors (alignment, ligament stability, meniscus health) must be corrected to protect the repair?^(22)(7)

References:

(0) Microfracture outcomes and lesion size influence: review article in PubMed Central. PMC
(1) Mosaicplasty outcomes up to long-term follow-up: PubMed Central review. PMC
(2) Clinical outcomes reporting for matrix-induced autologous chondrocyte implantation: PubMed Central article. PMC
(3) Management and defect size considerations review: ScienceDirect article. ScienceDirect
(4) Microfracture considerations for larger defects and progression concerns: ESSKA journal article. esskajournals.onlinelibrary.wiley.com
(6) Technique and indications discussion for matrix-associated autologous chondrocyte implantation: ScienceDirect technique article. ScienceDirect
(7) Overview of knee cartilage repair and restoration techniques; osteochondral autograft transfer size guidance: PubMed Central review. PMC
(10) Indications for autologous chondrocyte implantation and defect size thresholds: The Knee journal article. thekneejournal.com
(14) Review of cartilage lesion management trends; large-defect positioning for autologous chondrocyte implantation and matrix-induced autologous chondrocyte implantation: MDPI review. MDPI
(15) Microfracture biology and fibrocartilage characteristics: PubMed Central review. PMC
(20) Mosaicplasty procedure description and context: National Institute for Health and Care Excellence evidence overview (PDF). NICE
(22) Treatment trends and outcomes discussion including technique positioning: Cartilage journal article. cartilagejournal.org
(25) Long-term outcomes and factors influencing matrix-induced autologous chondrocyte implantation: Sage journal article. SAGE Journals

Microfracture vs Osteochondral Autograft Transfer vs Matrix-Induced Autologous Chondrocyte Implantation: Which Cartilage Repair Fits Which Knee Defect?