Articular Cartilage Injury of the Knee David Privitera, MD Sports Medicine Orthopaedic Surgeon Western NY Sports and Ortho

Articular Cartilage Injury of the Knee

Case Presentation 20 y/o male lacrosse player – History of R knee scope partial lateral meniscectomy a couple years ago – Had an occasional ache in the R lateral knee while playing lacrosse last year – Started lacrosse season this year (does faceoffs)  R lateral knee pain progresses, swelling and catching/popping

Case Presentation PE – Moderate effusion – Lat joint and LFC TTP – Stable knee – +mechanical mcmurray sign – Benign hip

Lateral meniscus tear extending to periphery in presence of lateral meniscal deficiency Cartilage defects LFC, Lat Tibial Plateau

What Now? Lateral meniscal deficiency Cartilage Defects of lat tibial plateau, LFC Stable knee in a 20 y/o active male???

What Now? Lateral meniscal deficiency Cartilage Defects of lat tibial plateau, LFC Stable knee in a 20 y/o active male???

What is Articular Cartilage? – Covers subchondral bone Absorbs pressure from WB Decreases friction – Critical to proper joint function – Limited ability to repair / regenerate

Composition Chondrocytes – Forms and maintains cartilage – Occupy < 10% total volume – Low mitotic activity – No nerve endings Extracellular matrix Proteoglycans Collagen (type 2) Water

Why doesn’t it heal well after injury? Hypocellular—Chondrocytes Avascular Gets nutrition by diffusion from synovial fluid via fluid turbulence

How does it present? Blunt trauma or shear stress Chronic repetitive impact Concomitant or prior injury (ACL/meniscus) History of Focal pain worse w impact, prolonged standing, kneeling, stairs Swelling, sometimes mechanical sx Present with Effusion, tenderness, crepitus, Rule out concomittant pathology Physical exam

XR screen for DJD – Standing AP, PA rosenberg, lateral and sunrise – Tunnel view for OCD in young – Mechanical axis Treatment considerations – Age, Functional level – BMI/obesity – Inflammatory arthritis – Smoking or narcotic addiction – Prior treatment – Associated injuries: ligament/meniscus – Effusion, mechanical symptoms – Mechanical axis Cartilage Signs and Symptoms

MRI…not all are created equally

Treatment for Cartilage Defects Nonop options – Rest, Activity Modifications – PT—address symptoms from weakness, contractures (hamstring, ITB, poor patellar mobility), poor mechanics (tracking, hip strength, etc) – NSAIDs – Viscosupplementation – Cortisone for older patients (chondrotoxic) – Unloader brace Operative <45-50y/o – Chondroplasty – Abrasion or Microfracture – Autologous Chondrocyte implantation/de Novo – OATS – Allograft – +/-osteotomy, patellar soft tissues

Surgical Tx for G3-4 I - Softening & swelling II- Partial thickness <50% III- Partial thickness >50%, IV- Full thickness-bone exposed

Treatment Algorithm Lesion SizeTreatment optionsOther considerations <2cm2Chondroplasty Microfx OATS ACI if prior intervention failed BMI >30 predicts microfx failure Opinion: Microfx for lower demand 2-4cm2ACI Osteochondral allograft +/-Microfx, OATS Prior microfx predicts higher failure rate for ACI >4cm2ACI Osteochondral allograft If subchondral bone changes  allograft vs sandwich technique for ACI

Microfracture Technique introduced by Steadman Debrided to stable edge Curette calcified cartilage layer Cortical penetration w awl Every 3-4 mm to depth of 2-4mm at rt. angles Should see fat globules or bleeding Clot formation stimulated

Repaired cartilage Normal rabbit Normal rabbit Late repair Late repair

Necessary rehab for optimal outcome CPM 6-8 hrs/day TTWB x 6-8 weeks

OATS - Miniarthrotomy Donor Recipient disadvantages – limited supply of donor sites – difficulty matching topography – “gap” tissue is fibrous – Robbing Peter to Pay Paul advantages – bone healing – Osteoarticular—hyaline cartilage

Autologous Chondrocyte Implantation Prior to last suture, seal with fibrin glue Inject saline to insure watertight seal Inject the cultured chondrocyte suspension Seal with final suture

Osteochondral allograft transplantation Fresh allografts superior – Harvest - 24 hrs, Transplant within 7 days Insignificant immune response

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