Cartilage Injury

functions of cartilage

distribute joint loads over an area, minimize friction

hyaline cartilage

found in synovial joints to minimize friction

fibrocartilage

found in intervertebral discs and meniscus for durability

elastic cartilage

found in structures like the ear to maintain the shape

importance of glycosaminoglycans (gag)

imbibe (absorb) water to use for tissue stiffness, allow for nutrient delivery in connective tissue

nutrition of cartilage

mostly fed via diffusion from synovial fluid (compression/release), deep parts fed by capillaries

mechanism of cartilage with rapid loading

becomes stiffer for better protection

biphasic model of cartilage loading

fluid pressure sustains load initially then the solid matrix helps if needed

how does shear forces result in cartilage failure

rubbing side to side causes fluid to go side to side and not in and out of the cartilage

ROM vs moderate exercise effect on cartilage

ROM just allows fluid to flow in and out while moderate exercises increases the gag count

why do cartilage lesions have poor healing potential

they are avascular, aneural, and alymphatic and require specific biomechanical properties

cause of articular cartilage injury

acute or repetitive minor trauma

methods of operative care for articular cartilage

arthroscopic lavage/debridement, microfracture, autologous chondrocyte implantation, osteochondral autograft transplantation

grade I cartilage lesion

minimum disruption, 10% cartilage loss

grade II cartilage lesion

joint space narrowing, cartilage breakdown, osteophytes

grade III cartilage lesion

gaps in cartilage expand until they reach the bone

grade IV cartilage lesion

joint space greatly reduced, 60% of cartilage lost, large osteophytes

cartilage rehab protocol post repair

incorporate exercises based on perceived joint load and minimize shear to help graft maturation (more compression, less ROM)

progression of rehab phases

protection and joint activation → progressive loading and functional joint restoration → activity restoration

biologic phases of chondrocyte maturation post cartilage repair

graft integration and stimulation → matrix production and organization → cartilage maturation and adaptation

therapeutic interventions in phase 1 of rehab

cryotherapy and compression, passive motion, mobs, stationary cycling, partial WB, aquatic therapy, biofeedback

goals of phase 1 of rehab

education of expectations, minimize swelling, maintain ROM, start load compression, minimize muscle atrophy

requirements to progress to phase 2 of rehab

full PROM, minimal pain and effusion, recovery of muscle activation and normal gait

characteristics of first healing phase of cartilage (0-8 weeks)

repairing stage (cotton), no load, protection and activation, joint circulation

characteristics of second healing phase of cartilage (7-12 weeks)

healing stage (dough), low loading, functional restoration, maximum muscle control

characteristics of third healing phase of cartilage (11-52 weeks)

loading stage (rubber), progressively increase loads, movement quality, activity restoration

factors that influence the post-op outcome

successful cell culturing, proficiency of surgeon, pt compliance, safe and progressive rehab program

how to promote cartilage healing process

stimulate and protect the tissue by minimizing shear force and reducing high impact loads

what to do during the protection and activation phase of rehab

begin protective weight bearing (braces, crutches), restore ROM, maintain joint homeostasis, neuromuscular re-education, reduce effusion

strongest indicator of bad response to treatment progression

presence of effusion

what could too much swelling mean

not enough motion, too much WB, infection

normal time of swelling after cartilage repair

6 weeks

effusion grading

trace: small wave with downswipe, 1+: larger bulge with downswipe, 2+: effusion spontaneously returns, 3+: effusion cannot exit