Cartilage Repair

The treatment of cartilage (joint surface) injuries is frequently an important part of the treatment of knee injuries. Often serious knee injuries (torn ACL) are associated with injuries to the joint surface. The management of these injuries require that the surgeon become a BIOSURGEON. This involves the application of treatments and surgical techniques that promote healing or regeneration of the injured joint surface.

1. Lavage and Debridement
   This is a very limited process consisting of cleaning, smoothing or shaving an injured or damaged joint surface.

   Pro: Removes debris, spurs and rough spots on the joint surface which can, to a limited degree, reduce some of the mechanical symptoms of "catching", "locking" or "giving out".

   Con: This procedure does not promote "healing" or "regeneration" of the surface injury. If improvement occurs it is usually short lived and does not significantly alter the course of the underlying disease.

   Applications: May have limited use in treating either a minimal joint surface injury or in temporarily reducing mechanical symptoms in a severely injured joint surface.

2. Drilling and/or Abrasion Arthroplasty
   This technique involves araiding the exposed bone in order to stimulate healing and regeneration of tissue. This technique has largely been replaced by "Microfracture" technique described below.
3. Microfracture (Mesenchymal Stem Cell Stimulation)
   This procedure is often applied to relatively small, localized joint surface lesions. This is an arthroscopic procedure and consists of scraping or trimming away the loose, damaged cartilage, lightly scraping the surface from the exposed bone, then creating holes in the exposed bone approximately 2-3 mm. apart. This creates a rough surface for the ensuing blood clot with undifferentiated mesenchymal cells (stem cells) from the marrow to adhere. In other words, a blood clot derived from the bone marrow, fills the defect in the articular surface. If all goes well, this clot will become a "fibrocartilage" patch which fills the defect in the joint surface. Most patients are significantly improved by this procedure.

   Pro: Relatively easy to perform. Response and recovery is quite predictable

   Con: It is important to protect the healing tissue. This means crutches with only "toe-touch" weight bearing for 6 weeks. It is also important to do passive range of motion several hours per day or apply 1500 unloaded cycles of range of motion per day.

   Applications: Used to treat relatively small full thickness cartilage injuries in the under 50 age group.

4. Osteochondral Grafts
   Some lesions are too large to respond favorably to microfracture procedure. In these situations the injured surface may be "replaced" by transporting cartilage "plugs" from one site (less important) in the knee to another (the site of the painful lesion). These "plugs" or in some cases larger pieces of bone and cartilage can be transported from the same knee (your knee). These are called Autografts. Or they may be obtained from an organ donor. These grafts are called Allografts.

   When a small graft or grafts will suffice, they are obtained from a less important part of the injured knee. When a very large defect must be treated, the graft must come from a "donor". Allografts are obtained from Tissue Banks.

   • Autografts:
     Pro: Can effectively heal relatively large full thickness cartilage lesions. Not associated with risk of rejection from donor material. Not exposed to risk of disease transmission from organ donor.

     Con: Size of treatable lesion is limited by need to harvest donor material from another part of the same knee. Thus amount of transportable graft material is limited.

     Application: Treatment of relatively large full thickness cartilage lesions.

   • Allografts:
     Pro: Can be used to treat large lesions. No limitations on size or amount of graft material.

     Con: Requires implanting biologic material from organ donor thus there is risk of disease transmission from donor, risk of infection from tissue bank processing and risk of rejection from immunologic reaction.

     Application: Treatment of very large full thickness cartilage and bone lesions.

   • Autologous Chondrocyte Implantation (ACI)

     This is a very special type of Autograft. Cartilage cells are harvested ( via arthroscope), sent to a special lab where the cells are cultured to increase their numbers, then the cells are implanted using a very special technique. This enables one to "regrow" cartilage tissue and fill the defect.