Articular Cartilage Lesions

• Why are articular cartilage lesions challenging for the medical field to treat?

  • Without intervention, they have no healing potential

• What are the components of articular cartilage?

  • Chondrocytes (maintenance; increase when injured)

  • Collagen (structure)

  • Ground substance (elasticity; increase when injured)

  • Water (lends flexibility, because the water is extracellular and moves when compressed

• What are the surgical options?

  • Debridement

  • Drilling

  • Abrasion arthroplasty

  • Microfracture

  • Osteochondral Autograft Trasplantation (OATS)

  • Autologous Chondrocyte Implantation (ACI

Microfracture

• What are the benefits of Microfracture?

  • Less technical

  • Cheap

  • Good for small lesions and young pts

  • Can do further surgeries without much damage

• Why is there a period of NWB following microfracture?

  • The healing times for chondral defects are not well known, so we are conservative with them

  • 6 weeks the repair is limited; 12 weeks there is more mature cartilage

• What influences the rehabilitation program?

  • Anatomic location

  • Size of defect

  • Age of patient

  • BMI

  • Prior activity level

• Protocol for femoral condyles or tibial plateau?

  • Crutches 6-8 weeks, TTWB; CPM?
    • PT exercises
      • Quad sets
      • 4-way SLR
      • Wall slides
      • Ankle pumps
      • Core stability
    • Patellar mobilizations, self-mobs
    • Biking without resistance, week 2, or aquatic therapy

  • Weeks 8-12 WBAT to train normal gait pattern
    • Resistance bike, walking, elliptical once pain-free
    • Endurance
      of Quads, HS, Calf, Glute, Core

  • Weeks 12-16
    • Agility on soft surfaces

  • Week 16+
    • Return to weight training

• When can you return the athlete to running, skiing, basketball, soccer, or football?

  • 6-9 months

  • Longer for jumping, cutting, twisting

• Protocol differences for trochlear groove or patella?

  • Difference: pts put in
    brace
    ROM 0-30° For 8 weeks to prevent median ridge of patella from engaging the trochlear groove

  • WBAT 2 weeks after surgery in brace

  • Passive ROM can be full

  • The angle of the patella engaging the groove is avoided for 4-6 months with strengthening.

• What are athletic results of trochlear/patellar microfracture?

  • 77% return to elite level (young do better)

  • 2 years of significant improvement

  • After 5 years, half have some decline – the repaired tissue may be less resilient

OATS

• What is it?

  • Osteochondral Autograft Transplantation (aka mosaicplasty) takes plugs of bone with articular cartilage on them from NWB parts of the knee (peripheral fem condyle) to the affected site.

• What are the limitations?

  • Donor has to have enough tissue to use

  • Small 1-4cm^2 lesion

  • Plugs can only be 10mm deep

• What’s it usually used for?

  • Femoral condylar lesion without any issue in meniscus, and no degeneration

• How does rehab differ from microfractue?

  • Can use progressive overload based on patient’s tolerance

  • Less change of degeneration

• What point in knee flexion do most articular lesions occur?

  • 30°-70° flexion

  • The fem condyles and tibial plateau are in constant articulation with roll and glide, and anterior shearing forces

• Why does a meniscus lesion change rehab?

  • Slow things down

  • The tibiofemoral contact area is decreased

  • The stress on the articulation is therefore greater

• How does the patella articulate with the trochlea at different angles?

  • 10°-20° flexion, inferior patella articulates

  • 30° flexion, odd facets

  • 60° flexion, middle facets on trochlea; superior facets on femoral condyles

• How does the contact area of the patellofemoral joint change with flexion?

  • More flexion is greater contact area

• How long is NWB after OATS?

  • Two weeks

• When can WBAT start

  • Weeks 6-8 based on subchondral integration times

• What forces should be protected against with condylar lesions vs patellofemoral lesions?

  • Tibiofemoral lesions be careful with compression

  • Patellofemoral lesions be careful with shearing

• What will patients get right after surgery? (2)

  • Knee orthotic locked in extension

  • 6-8 hours per day CPM 0-60°; or 500 wall slides per day

• How is ROM progressed?

  
  
  

ACI

• What is it?

  Autologous Chondrocyte Implantation takes a few cells from the NWB superomedial edge of the trochlea and cultures them in a lab before reimplanting

• Who is it good for?

  • Motivated, compliant, and young patient who’s already tried microfracture or mosaicplasty

• How long does it takes the cartilage cells to adhere to bone?

  • First 6 weeks

• What is done during that time for the patient?

  • TTWB

  • CPM

• What does the protocol look like?