Chondral lesion is focal damage to the hyaline cartilage covering the articular surface. It can be traumatic (acute osteochondral fracture, impaction) or degenerative (cartilage erosion in osteoarthritis). Osteochondritis dissecans (OCD) is separation of a cartilage + bone fragment from parent bone due to avascular necrosis of subchondral bone — most commonly seen in medial femoral condyle (lateral surface, 85%) and more common in young athletes. Chondral lesions are graded by Outerbridge (I-IV arthroscopic) or ICRS (0-4) classifications. On MRI, cartilage defect, thinning, surface irregularity, and subchondral bone exposure changes are evaluated. Quantitative MRI techniques like T2 mapping and dGEMRIC can detect early cartilage degeneration. Treatment ranges from conservative management to microfracture, mosaicplasty (osteochondral graft), and autologous chondrocyte implantation (ACI) depending on lesion size, depth, and patient age.
Age Range
10-50
Peak Age
30
Gender
Male predominant
Prevalence
Common
Hyaline cartilage is a specialized connective tissue covering articular surfaces composed of collagen (primarily Type II), proteoglycans (aggrecan), and chondrocyte cells. Cartilage is avascular, alymphatic, and aneural — nutrition is entirely provided by diffusion from synovial fluid. This avascularity severely limits cartilage's post-damage healing capacity — full-thickness cartilage defects do not heal spontaneously. In traumatic chondral lesions, mechanical force (impaction, shearing) disrupts the cartilage matrix. When subchondral bone is exposed, bone marrow cells can migrate to the defect area and fill with fibrocartilage (Type I collagen) — however this tissue is not as durable as hyaline cartilage. In OCD, the vascular supply of subchondral bone is disrupted (repetitive microtrauma, genetic predisposition) and avascular necrosis develops. Cartilage over necrotic bone loses its support and fragment formation begins. In stable OCD, cartilage maintains connection with fragment; in unstable lesion, fragment separates as loose body into the joint. On MRI, filling of cartilage defect with hyperintense fluid on T2 reflects synovial fluid penetrating the defect area. Bright appearance of subchondral bone marrow edema on STIR indicates subchondral stress reaction.
Complete surrounding T2 hyperintense fluid line between OCD fragment and parent bone on T2 fat-sat/STIR MRI. This finding indicates synovial fluid has completely penetrated around the fragment and signals the fragment is detached (unstable) from parent bone. In stable OCD, T2 hyperintense line is absent or partial. Instability finding creates surgical intervention indication.
On T2 fat-suppressed sequences, focal defect in articular cartilage is seen — the defect area fills with synovial fluid appearing hyperintense. In full-thickness defects, subchondral bone is directly exposed to synovial fluid. Cartilage thinning is evaluated by comparison with surrounding normal cartilage. Size, depth, and location of defect are critical for treatment planning.
Report Sentence
A full-thickness cartilage defect measuring approximately ___ mm is seen on the weight-bearing surface of the medial femoral condyle with exposed subchondral bone.
On T2 fat-sat/STIR sequences, hyperintense fluid line is seen between subchondral bone fragment and parent bone — this is a finding of unstable OCD lesion. In stable lesion, T2 hyperintense line may be partial with fragment in close contact with parent bone. In unstable lesion, completely surrounding fluid line is seen, fragment may be displaced or seen as loose body in the joint. Overlying cartilage integrity should be evaluated.
Report Sentence
An OCD lesion measuring approximately ___ mm is seen on the lateral surface of the medial femoral condyle with complete fluid line around fragment suggesting instability.
On STIR/T2 fat-sat sequences, bone marrow edema is seen in subchondral bone underlying the cartilage defect. This edema represents subchondral stress reaction or avascular necrosis accompanying cartilage damage. In OCD, fragment and surrounding bone show edema. In degenerative chondral lesions, subchondral edema is an indicator of osteoarthritis progression.
Report Sentence
Subchondral bone marrow edema in an area of approximately ___ mm is seen underlying the cartilage defect, consistent with subchondral stress reaction.
On PD fat-suppressed sequences, linear hyperintense line (fissure) at cartilage surface or flap structure where cartilage layer is partially lifted is seen. Fissure represents partial cartilage damage, flap represents partial detachment of cartilage from subchondral bone. Cartilage flaps can cause mechanical symptoms (catching, locking) and may require arthroscopic treatment.
Report Sentence
A partial-thickness fissure/flap at the cartilage surface of the medial femoral condyle is seen, consistent with Outerbridge Grade ___ chondral lesion.
On T1-weighted sequences, loose body may be seen in the joint space — this is a displaced osteochondral fragment. Fragment containing bone carries bone marrow signal (high signal) on T1 while overlying cartilage shows intermediate signal. Loose bodies float within synovial fluid in the suprapatellar recess, posterior compartment, or intercondylar notch. Loose body surrounded by joint effusion is easily detected.
Report Sentence
A loose body measuring approximately ___ mm is seen in the suprapatellar recess/posterior compartment, consistent with displaced osteochondral fragment from OCD origin.
Criteria
Grade I: cartilage softening, Grade II: partial-thickness defect (<50%)
Distinct Features
Usually conservative treatment, signal increase and mild thinning on MRI
Criteria
Grade III: >50% thickness loss, Grade IV: full-thickness defect + subchondral bone exposure
Distinct Features
Surgical treatment needed (microfracture, mosaicplasty, ACI), significant symptoms
Criteria
Subchondral bone fragment + overlying cartilage — stable or unstable
Distinct Features
Common in young athletes, medial femoral condyle lateral surface (85%), T2 fluid line instability indicator, stable: conservative / unstable: surgical
Distinguishing Feature
Bone contusion is primarily bone marrow edema with cartilage integrity usually preserved; chondral lesion has defect/thinning at cartilage surface
Distinguishing Feature
Meniscal tear is intrameniscal pathology, chondral lesion is cartilage surface pathology — different anatomy but frequent coexistence
Distinguishing Feature
Baker cyst is popliteal fossa synovial fluid accumulation different from chondral lesion; however Baker cyst may develop in setting of chondral damage + osteoarthritis
Urgency
routineManagement
surgicalBiopsy
Not NeededFollow-up
specialist-referralChondral lesion treatment is planned based on lesion type, size, depth, and patient age/activity level. Small, asymptomatic, low-grade lesions are managed with conservative treatment (physical therapy, weight control, NSAIDs). For symptomatic full-thickness defects, surgical options include: microfracture (<2 cm2 defect), mosaicplasty/osteochondral graft (2-4 cm2), autologous chondrocyte implantation ACI (>4 cm2). In OCD, stable lesions (especially in children with open physis) may heal with conservative treatment. Unstable OCD requires surgical fixation (Herbert screw, bioabsorbable pin) or loose body removal + defect treatment. Untreated large chondral defects lead to progressive osteoarthritis.
Untreated chondral and osteochondral lesions lead to early osteoarthritis. Stable OCD lesions may be managed conservatively, while unstable lesions and loose bodies require arthroscopic intervention (microfracture, mosaicplasty, osteochondral graft). Outerbridge Grade III-IV lesions are typically surgical candidates.