Articular Cartilage Defects

2021-02-18 12:00 AM

Properties of Articular Cartilage

  • lacks blood supply and does not have innervation or lymphatic drainage
  • varies in thickness from 2 mm to 4 mm and is thickest at the periphery of concave surfaces and central portions of convex surfaces
  • composed of type 2 collagen, water, proteoglycans, and chondrocytes
  • collagen provides resistance against tensile stresses and transmits vertical loads
  • water and proteoglycans provide turgor and elasticity and help to limit friction
  • chondrocytes synthesize the cartilage matrix and control matrix turnover rate

 Aetiology

  • overt trauma or repeated minor trauma; most commonly from sports injuries
  • early-stage osteoarthritis
  • genetic degenerative diseases such as osteochondritis dissecans

 Clinical Features

  • very similar to symptoms of osteoarthritis (joint line pain with possible effusion, etc.)
  • often have predisposing factors such as ligament injury, malalignment of the joint (varus/ valgus), obesity, bone deficiency (avascular necrosis, osteochondritis dissecans, ganglion bone cysts), inflammatory arthropathy, and familial osteoarthropathy
  • may have symptoms of locking or catching related to the torn/displaced cartilage

 Investigations

  • arthroscopy to visualize focal pathology and guide treatment strategy
  • MRI may also be used to visualize the defect

 Table 21. Outer bridge Classification of Chondral Detects

Treatment

  • arthroscopic lavage and debridement of the joint
  • marrow stimulation techniques (microfracture, drilling, abrasion arthroplasty)
  • involves creating a site of bleeding where new growth/healing can take place
  • osteochondral grafts; also known as the OATS procedure or mosaicplasty
  • involves transferring osteochondral fragments from non-weight bearing surface to area of defect
  • autologous chondrocyte: implantation (ACI)
  • currently only available in the U.S. and Europe
  • involves harvesting patient's cartilage, growing it in culture: medium outside of the patient, then reinserting the newly cultured chondrocytes back to fill the chondral defect
  • osteochondral allograft; only used in limited circumstances when defect is very large