Osteochondral Defect Knee

An osteochondral defect, also commonly known as osteochondritis dissecans, of the knee refers to damage or injury to the smooth articular cartilage surrounding the knee joint and the bone underneath the cartilage.

The goal of conservative treatment is to reduce pain and inflammation in the joint. This can often be done with the use of non-steroidal anti-inflammatory medication, such as ibuprofen or naproxen. Hot and cold therapy, as well as rest, and activity modification are recommended. The common treatment strategies for symptomatic osteochondral lesions include nonsurgical treatment, with rest, cast immobilization, and the use of nonsteroidal anti-inflammatory drugs (NSAIDs).

When a cartilage defect or lesion is very large (for example > 1cm in size), we may consider cutting out the lesion and replacing it with a plug of bone and cartilage from another part of the joint that is not involved in joint motion. This treatment is known as an osteochondral transplant. The recovery period after an osteochondral lesion usually lasts six months to a year. Typically, you progress from range-of-motion exercises to light cardiovascular exercise and then strengthening exercises. If you experience episodes of minor swelling or pain while exercising, have your physician examine your ankle.

Other Names

  • Osteochondritis Dissecans
  • Osteochondritis Dissecans of the Knee
  • Osteochondral Defect of the Knee
  • Osteochondral Lesion
  • Osteochondral Fracture
  • Up to 10% of people over 40 will have osteochondral lesions (need citation)
  • A review of 1000 knee arthroscopies showed 61% had an OCD
  • A polish registry of 5233 found
    • Half of the patients undergoing knee arthroscopy had chondral defects; with 5.2% had Outerbridge Grade III or IV lesions. ** Of those with OCD, 37.5% were in the patella alone
  • Curl et al reviewed 31,516 knee arthroscopies
    • Over 53,000 hyaline cartilage lesions in over 19,000 patients
    • Most of the lesions found were actually grade III defects in the patella
  • Among asymptomatic professional basketball players, MRI found
    • 57% of all players had an abnormal chondral signal
    • 35% having high-grade patella, 25% with high-grade trochlea signal

Pathophysiology

    • The most common site of OCD in both children and adults is the knee
  • General
    • A broad term refers to the morphological change of a localized gap in the articular cartilage and subchondral bone
    • Can occur acutely or develop as a result of several chronic conditions
    • The etiology of symptomatic chondral/osteochondral pathology is complex and often multifactorial
    • Impaction forces greater than 24 MPa will disrupt normal cartilage (need citation)
  • Pediatric Considerations
    • Bilateral knee involvement is reported in up to 25% of the cases
    • Most juvenile OCDs are stable lesions that will heal without surgical intervention, long-term consequences

Causes

  • Acute Trauma
    • Rotational forces indirect trauma is commonly cited
    • Patella Dislocation
  • Other Trauma
    • Overuse leading to repetitive microtrauma
    • Osteochondral Impaction Fracture
    • Post-surgical
  • Biological factors
    • Osteochondritis dissecans
    • Osteonecrosis or Avascular necrosis
    • Subchondral Insufficiency Fracture (SIF)
  • Osteochondritis Dissecans
    • Pathology involving the osteochondral unit
    • Resulting in sequestration of subchondral bone
    • With or without articular cartilage involvement and instability.

Histology

  • General
    • These defects typically result in the production of type I collagen in the form of Fibrocartilage
    • Fibrocartilage has poorer characteristics with regard to resilience, stiffness, and wears properties
    • As opposed to type II collagen normally found in articular, hyaline cartilage

Associated Pathology

  • ACL Injury
    • Can result in OCD of the anterior aspect of lateral femoral condyle or posterolateral tibial plateau
  • Patella Dislocation
  • Patellofemoral Pain
  • Osteonecrosis (Main)
  • Subchondral Insufficiency Fracture (SIF)
  • Osteochondritis Dissecans
  • Obesity
  • Patellar Malalignment

Differential Diagnosis

  • Fractures
    • Distal Femur Fracture
    • Patellar Fracture
    • Tibial Plateau Fracture
  • Dislocations & Subluxations
    • Patellar Dislocation (and subluxation)
    • Knee Dislocation
    • Proximal Tibiofibular Joint Dislocation
  • Muscle and Tendon Injuries
    • Quadriceps Contusion
    • Iliotibial Band Syndrome
    • Quadriceps Tendonitis
    • Patellar Tendonitis
    • Popliteus Tendinopathy
    • Extensor Mechanism Injury
      • Patellar Tendon Rupture
      • Quadriceps Tendon Rupture
      • Patellar Fracture
  • Ligament Pathology
    • ACL Injury
    • PCL Injury
    • MCL Injury
    • LCL Injury
    • Meniscal Pathology
    • Posterolateral Corner Injury
    • Multiligament Injury
  • Arthropathies
    • Knee Osteoarthritis
    • Septic Arthritis
    • Gout
  • Bursopathies
    • Prepatellar Bursitis
    • Pes Anserine Bursitis
    • MCL Bursitis
    • Infrapatellar Bursitis
  • Patellofemoral Pain Syndrome (PFPS)/ Anterior Knee Pain)
    • Chondromalacia Patellae
    • Patellofemoral Osteoarthritis
    • Osteochondral Defect Knee
    • Plica Syndrome
    • Infrapatellar Fat Pad Impingement
    • Patellar Instability
  • Neuropathies
    • Saphenous Nerve Entrapment
  • Other
    • Bakers Cyst
    • Patellar Contusion
  • Pediatric Considerations
    • Patellar Apophysitis (Sinding-Larsen-Johnansson Disease)
    • Patellar Pole Avulsion Fracture
    • Tibial Tubercle Avulsion Fracture
    • Tibial Tuberosity Apophysitis (Osgood Schalatters Disease)

Clinical Features

  • History
    • Patients often have a history of trauma, depending on etiology may be mild or substantial
    • Patients will endorse pain, locking of the knee
    • Swelling is often present
    • Inability to walk, run or participate in sport
  • Physical Exam:
    • Quad muscle atrophy may occur in chronic cases
    • Important to perform the thorough structural exam
    • Evaluate for effusion, mechanical symptoms
  • Special Tests
Coronal MRI of an osteochondral lesion, demonstrating fluid signal behind the articular cartilage and edema within the subchondral bone

Radiographs

  • Standard Radiographs Knee
    • Recommended views include AP, Lateral, and notched/ tunnel view
    • Frequently normal in early stages
    • Easily diagnoses large or displaced defects
  • Findings
    • Abnormal bone contour (most commonly the lateral aspect of the medial femoral condyle)

MRI

  • The imaging modality of choice
    • Most sensitive/ specific modality for evaluating lesions
    • Useful to stage lesion
    • Evaluates other soft tissue structures
  • Can evaluate
    • Soft tissue competence
    • Chondral status
    • Trochlear morphology
    • Presence of loose bodies
    • Acuity of injury (i.e., bone bruise pattern)
    • Alignment parameters in multiple planes

CT

  • Benefits
    • Better evaluate bone loss
    • Measure tibial tubercle-trochlear groove (TT-TG)
    • Measure tibial tubercle-posterior cruciate ligament (TT-PCL)

Classification

International Cartilage Repair Society Classification

  • Grade 0: Normal
  • Grade 1: Nearly normal (superficial defect with soft indentation, fissures or cracks)
  • Grade 2: Abnormal (defect extending to < 50% of cartilage depth)
  • Grade 3: Severely abnormal (defect extending > 50% of cartilage, but not through subchondral bone)
  • Grade 4: Severely abnormal (defect penetrating through subchondral bone)

Outerbridge Arthroscopic Grading System

  • Grade 0: Normal cartilage
  • Grade I: Softening and swelling
  • Grade II: Superficial fissures
  • Grade III: Deep fissures, without exposed bone
  • Grade IV: Exposed subchondral bone

Treatment

Nonoperative

  • Indications
    • Not universally agreed upon
    • Mild symptoms
    • Absence of mechanical features (locking, swelling, instability, etc)
  • Restriction of physical activity
    • Stop activities that cause excessive repetitive, compressive stress on the affected knee
    • Includes all strenuous contact sports, running, jumping, squatting and long periods of standing
  • Physical Therapy
  • Modalities including Iontophoresis, Extracorporeal Shock Wave Therapy
  • Restricted weightbearing
    • partial with crutches
    • Total with wheelchair
  • Immobilization with cast or brace
  • Medications including NSAIDS
  • Viscosupplementation
    • Controversial due to unknown benefits
    • Considered safe for articular cartilage, should be considered
  • Corticosteroid Injections
    • Use is controversial
    • Should be used sparingly, especially in younger patients
    • Concerns over deleterious effects on articular cartilage over time
  • Platelet Rich Plasma
    • Growing in popularity
    • Has shown promise, especially with leukocyte poor formulations

Operative

  • Objectives
    • Re-establish the joint surface with hyaline cartilage
    • Provide a congruent joint with correct alignment
    • Symptomatic relief
    • Reduce the risk of progressive arthritic changes
  • Indications
    • High risk features
    • Mechanical symptoms (locking, swelling, instability, etc)
    • Large defect size (range in literature is 0.75 to 1.5 cm)
  • Technique
    • Debridement / Chondroplasty
    • Palliation (e.g. chondroplasty or microfracture)
    • Repair or Fixation of Unstable Fragments
    • Osteochondral autograft transplant (OAT) / Mosaicplasty
    • Osteochondral allograft transplant
    • Autologous matrix induced-chondrogenesis (AMIC)
    • Autologous chondrocyte implantation (ACI)
    • Subchondral bone drilling
    • Marrow Stimulation Techniques
    • Patellar cartilage unloading procedures
    • Arthroplasty may be considered in patients who are older with advanced osteoarthritis