• There are certain factors to consider when contemplating which surgical procedure to utilize: (15, 20)

  • Patient morbidity (pain, stiffness, blood loss, and time off work)
  • Reproducibility of results
  • Surgical time
  • Cost
  • Technical difficulty
  • Clinical data
  • Postoperative rehabilitation
• To heal articular cartilage there are some basic requirements: (7)
• A source of cells
• Provision of a matrix
• The removal of stress concentration
• An intact subchondral plate
• Mechanical stimulation
• There are an array of open and arthroscopic techniques used to treat chondral defects. (1, 3, 4, 7, 10, 13, 15, 19, 20)
• Marrow stimulation techniques
  • Abrasion arthroplasty and subchondral drilling
    • Demonstrated some variable success in arthritic knees
  • Drilling arthroplasty
  • Microfracture
• Osteochondral autografts and allografts
  • Problems include donor site morbidity, loss of function, and limited supply of autologous cancellous bone
• Implantation of cultured chondrocytes
• Unicompartmental or total knee arthroplasty (TKA)
  • This strategy demonstrates favorable results in the treatment of arthritic knees
  • It is inappropriate for a patient who desires a high level of athletic activity
• Older methods of treatment such as abrasion chondroplasty and drilling, have not produced reliable cartilage repair, but newer techniques such as mosaicplasty, autologous chondrocyte transplantation, and osteochondral allograft transplantation have produced more encouraging results. Although many of these new techniques have promising results, they are invasive, expensive, and lack long term follow up studies. (1, 15)
  
  
  Mosaicplasty
  Permission granted by Mr. Pimpalnerkar of Orion Clinic
  
  
• Microfracture is low-risk, simple, inexpensive, and has long term studies to support its success rate. It is unique as it can treat both traumatic focal chondral defects and degenerative lesions. (1, 7)
• One study showed that both microfracture and osteochondral autologous transplantation gave encouraging clinical results for athletes under the age of 40. Other studies on autologous chondrocyte transplantation revealed inferior results in the patellofemoral joint when compared to microfracture. Autologous chondrocyte transplantation is limited by the size of the lesion, while microfracture is not. Compared to autologous cartilage transplantation, microfracture patients have a shorter absence from their athletic activity. (7, 10, 19)
  
  
  Autologous chondrocyte implantation to treat a localized defect
  Permission granted by Mr. Pimpalnerkar of Orion Clinic
  

• Osteoarticular transplantation is not successful in larger lesions due to the iatrogenic graft site morbidity. This technique also decreases the amount of options for future surgeries if it were to fail. Microfracture does not have this short coming. (7)
• Microfracture is preferred because it creates less thermal injury than drilling, can access difficult areas of the articular surface, and provides controlled depth penetration. (7)
• A study of abrasion arthroplasty patients with 2 to 5 years of follow-up showed that 76% had persistent complaints, 66% had pain, and 99% reported activity restrictions. In comparison to the 5.9% of patients in the microfracture study, 17.1% of the patients required TKA, osteotomy, or arthrotomy within 5 years of the abrasion. (13)

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