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Osteoarthritis/Chondral Injuries Print

Articular Cartilage

The primary functions of articular cartilage (covering of the bone) are to distribute forces to the bone and provide a low friction surface for the joint. These properties protect the bones from a lifetime of walking, running, jumping, and sudden, severe shocks. Normal hyaline cartilage is thick, with a smooth glassy shine. The cartilage is firmly anchored to the underlying bone by collagen fibers which protect the joint from shearing injuries. Cartilage injuries or wear from osteoarthritis can lead to progressive destruction of the joint surface. Fig. 2 demonstrates the cross sectional normal articular cartilage.  

Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 1A Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 1B
Figure 1A Figure 1B

 

Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 1C Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 1D
Figure 1C Figure 1D

 

Articular cartilage consists of cartilage, cells(chondrocytes), collagen fibers and proteoglycans (Fig. 3).

The chondrocytes are the cells that are responsible for making articular cartilage. These cells are active in the development and maintenance of healthy cartilage, as well as the degradation of diseased cartilage. They orchestrate the balance between synthesis and breakdown of the cartilage components.

The reason cartilage is such a good shock absorber is that 60-80% of its weight is composed of water. Because of this, articular cartilage is known as a hyperhydrated tissue. The remaining 20-40% is made of the collagen fibers and proteoglycans (Fig. 4). Type II collagen fibers (Fig. 5) provide the basic architectural structure of articular cartilage. These fibers are extremely strong and have the capacity to resist stress and provide strength to the articular cartilage.

 

Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 4

Figure 4

 

Figure 5

Proteoglycans consist of a central protein core, to which numerous sulfated glycosamioglycans chains are attached. A proteoglycon aggregate is composed of many molecules attached to a long, hyuronic acid chain. The glycosaminoglycan chains are negatively charged compounds that bind water molecules, making the proteoglycan chain, and therefore the articular cartilage, resistant to compression (Fig. 6).

 

Image for Figure 6A Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 6B
Figure 6A Figure 6B

 

Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 6C Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 6D
Figure 6C Figure 6D

 

Articular cartilage does not have blood or nerve supply. It receives nutrition from the fluid within the joint or from the underlying subchondral bone. The structure and function of articular cartilage is very closely linked. The failure of chondrocytes to maintain a balance between the matrix components (the tissue around the cells) can lead to serious consequences. When cartilage is damaged, the proteoglycans are lost from the artilage. As a result, the chondrocytes are more exposed to compression forces. When chondrocytes are subjected to increased mechanical wear, they release enzymes that can destroy the cartilage.

Hyaline cartilage has distinctive zones. The superficial layer, known as the gliding zone, is characterized by densely packed elongated cells which run parallel to the surface. Just below the superficial layer is a transitional zone, consisting of rounded chondrocyte cells that are randomly oriented. Following the transitional zone is the radial zone. It is noted for vertical columns of cells that travel to and anchor the articular cartilage to the subchondral bone. Just below the radial zone is a wavy bluish line called the tide mark. The tide mark separates the radial zone from the deepest zone. This zone is known as the calcified zone, and consists of different types of salts and cells that are larger. The point to emphasize is that the structure, composition and mechanics of cartilage are inseparably linked. Any changes to the architecture of the normal hyaline cartilage will have profound effect on its biomechanical properties.

Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 7A Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 7B
Figure 7A Figure 7B

 

The common end point of osteoarthritis is breakdown of the articular cartilage. The degree of cartilage degree deterioration may be graded. Grade I is softening of the cartilage with fibrillation, grade II changes have linear fissures that extend into the articular cartilage but not down to the underlying bone, grade III lesions have defects that extend down to the tide mark region of the cartilage, but not down to the subchondrol bone and grade IV defects extends to the subchondral bone with complete destruction of the cartilage.

 

Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 8A1 Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 8A2
Figure 8A1 Figure 8A2

 

Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 8A3 Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 8B1
Figure 8A3 Figure 8B1

 

 

Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 8B2 Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 8B3
Figure 8B2 Figure 8B3

 

 

 

image Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 9D
Figure 9C Figure 9D

 

Treatment

The treatment of osteoarthritis varies depending on the severity of the condition, the amount of deformity, degree of pain and the goals of the patient. In general, activities that load the joint excessively should be minimized. Losing weight and using an assistive device, such as a cane, are often beneficial.

Exercises which minimize joint loading such as swimming are usually more beneficial than exercises such as walking or running. Physical therapy that emphasizes maintenance of motion and muscular strength are beneficial, but excessive exercises should be avoided. Although osteoarthritis is predominantly a degenerative condition, there is often a significant component of inflammation. In a study of 100 patients who had osteoarthritis, seventy-three per cent of involved knee joints had effusions (fluid on the joint), 26 had increased warmth of the joint and 40% had cysts. These patients complained of rest pain and joint stiffness, suggesting the presence of inflammation.

Nonsteroidal Anti-Inflammatories and Osteoarthritis

Nonsteroidal anti-inflammatories are the first line drugs used in the treatment of osteoarthritis. These drugs help to increase joint motion and decrease joint warmth. These drugs, including aspirin, ibuprofen, Naprosyn and others may be effective in decreasing pain, but there is no indication that they decrease the progression of joint breakdown in osteoarthritis. Moreover, nonsteroidal anti-inflammatories may be associated with side effects, such as stomach pain and gastrointestinal bleeding. They should be used with caution in elderly patients. 

Glucosamine & Chondroitin Sulfate

Glucosamine and chondroitin sulfate, administered orally, has been demonstrated to stimulate proteoglycan synthesis by the chondrocytes and has mild anti-inflammatory properties. Several scientific studies have demonstrated that Glucosamine and chondroitin sulfate are just as effective as some of the anti-inflammatories. Unlike nonsteroidal anti-inflammatories, which inhibit the prostaglandin and synthesis, Glucosamine and chondroitin sulfate appears to exert its therapeutic effects through a prostaglandin independent mechanism. There are few side effects with Glucosamine and chondroitin sulfate and medication should be taken at least six weeks to determine if it is effective.

Synvisc, Hyalgan, Supartz, Orthovisc

Intraarticular administration of hyaluronic acid (trade names Synvisc, Hyalgan, Supartz, Orthovisc) has become widely used for treatment of osteoarthritis. Normal joint fluid contains hyaluronic acid which acts as a lubricant. In osteoarthritis, this lubricant is depleted. The injection of SYNVISC or HYALGAN, a thickened version of the joint fluid, lubricates the joint and also stimulates cells in the joint to produce additional hyaluronic acid. Hyaluronic acid also affects the white blood cells which cause inflammation in the joint. Intraarticular injection of hyaluronic acids seems to be as effective as commonly used anti-inflammatories in relieving pain and improving function in patients with osteoarthritis of the knee.

Side effects of hyaluronic acid injection are minimal. Intraarticular hyaluronic acid may be particularly useful in symptomatic treatment of osteoarthritis of the knee in elderly patients with a prior history of anti-inflammatory complications, or in patients with contraindications to use of anti-inflammatories such as renal disease.

Typically, a series of three to five hyaluronic acid injections, administered weekly, is recommended. Although the effects of hyaluronic acid injections may last as long as six months, the long-term effectiveness and the need for repeated injections is uncertain.

Corticosteroids and Osteoarthritis

The injection of intraarticular corticosteroids (cortisone) in osteoarthritic knee joints is a common practice. Judicious use of these drugs in osteoarthritis does not seem to carry a high risk of significant adverse effects. Injections should not be performed more frequently than every three to four months.

Once damaged, the articular cartilage has only limited ability to repair itself. The articular cartilage damage may result from an injury (such as a fall), a defect in the cartilage and bone known as osteochondritis dissecans, or from a series of seemingly minor traumatic events. If the arthritis is progressive and severe, replacement with an artificial joint may eventually be required. This surgical procedure is extensive and can have serious complications. Preservation of the joint is preferable to a joint replacement.

Several surgical techniques are currently used to try to relieve symptoms and stimulate some form of repair to injured cartilage.

Shaving of Fibrillated Cartilage

Clinical experience indicates that arthroscopic shaving of fibrillated and irregular cartilage, particularly patella cartilage, may relieve symptoms. Although this procedure is performed frequently, its efficacy has not been documented. It does not restore a normal congruent articular surface or stimulate significant cartilage repair.

Grade II Articular Cartilage Changes of the Patella

Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 10A Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 10B
Figure 10A Figure 10B

 

Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 10C Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 10D
Figure 10C Figure 10D

 

After arthroscopic debridement

Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 11A Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 11B
Figure 11A Figure 11B

 

Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 11C
Figure 11C

 

Perforation or Abrasion Chondroplasty

Perforation of the subchondral bone stimulates bleeding and the formation of fibrocartilage to fill the defect, but fibrocartilage is inferior to normal articular cartilage (Figure 12). Clinical experience shows that the repaired tissue produced by this method may function well as the joint surface for a relatively long period of time. Fibrocartilage does not stand up to the demands of an active joint and wears poorly, with recurring symptoms, ultimately requiring further surgical intervention. The most frequently performed marrow stimulation technique are microfracture is indicated for isolated lesions that have normal surrounding cartilage. This procedure does not work for patients with osteoarthritis.

Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 9A 	Osteochondral Dissecans, Injuries of the Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Surgery, Sports Medicine, Figure 12a before osteoarthritischondral injuries of the knee, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 12b after
Figure 11a Before Microfracture Figure 11b After Chondroplasty

 

 

Cartilage Regeneration

A group of Swedish researchers developed an innovative surgical technique for regenerating damaged articular cartilage. The procedure, performed in Sweden since 1987, is designed to treat cartilage defects through regeneration of long wearing hyaline cartilage. This technique, autologous cartilage implantation, involves removal and reimplantation of the patient's own cartilage cells to fill a cartilage defect. The Swedish study, published in the New England Journal of Medicine (October 1994), reported the technique to be very effective for treatment of cartilage defects involving the end of the femur (thigh bone). More than 10,000 of these procedures have been performed world-wide.

The term "autologous" means the tissue implant originates from the patient's own cells. There are no cells from another individual involved, so concerns of tissue rejection or cross infection through donated tissues are avoided. The treatment consists of two surgical procedures, as detailed.

Step 1: Arthroscopic biopsy procedure

The initial surgical procedure is an arthroscopy. This is a minimally invasive technique usually performed in an outpatient setting. The arthroscope is inserted into the knee to allow the surgeon to visualize the inside of the joint and perform certain surgical procedures. If an articular cartilage defect is present which is amenable to this procedure a sample of healthy cartilage is removed.

Step 2.: Biopsy, processing, and cell culturing

The biopsy tissue is then sent to the specialized processing facility at Genzyme Tissue Repair. Under strict aseptic conditions, the cartilage cells from the biopsy are nourished and grown in culture. Rigorous quality control measures are implemented to insure safety in processing. Cell culturing usually requires several weeks, during which time the cells grown many times their original number. Following culture, the cells will be returned to the physician for surgical implantation.

Step 3: Surgical Implantation

At this time a second surgical procedure is performed by a physician who is especially trained in this procedure. (See series of images below)

osteoarthritischondral injuries of the knee, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 13

osteoarthritischondral injuries of the knee, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 14

Figure 12

Figure 13

 

 

 

 

 

 

 

 

 

 

 

An incision is made and the joint is opened (Fig. 13). Damaged cartilage tissue is removed, and the defect is prepared to receive the cultured cells (Fig. 15) Another incision is then made over the tibia (shin bone) to remove a piece of the periosteum, the thin tissue which covers the bone. The periosteum is sutured over the cartilage defect to serve as a protective cover for the cells which are implanted beneath it (Fig. 13) . The cells adhere to the lining of the defect and gradually regenerate new cartilage which eventually grows to appear like the original tissue.

 

Fig 15 - The lesion is debrided back to expose healthy cartilage, leaving the subchondral bone plate intact

Fig 16 - The prepared defect is covered with a periosteal patch taken from the proximal medial tibia.

The periosteum is sutured to the rim of the healthy cartilage, creating a protective cover over the lesio

osteoarthritischondral injuries of the knee, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 15 osteoarthritischondral injuries of the knee, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 16
Figure 14 Figure 15

 

Fig 16 - Autologous fibrin glue may be applied to supplement the seal

Fig 17 - The cultured cells are then implanted under the patch into the defect. The joint is then closed in routine fashion.

osteoarthritischondral injuries of the knee, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 17 osteoarthritischondral injuries of the knee, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 18
Figure 16 Figure 17

 

Osteochondral Autograft Transplantation

Osteochondral autograft transfer is a technique that has been used to replace damaged articular cartilage. A series of thin walled cutting tubs are used to harvest plugs of bone capped with healthy hyaline cartilage from relatively unused part of the knee which is subsequently transferred to the damaged area. The following picture demonstrates the damaged area on the medial femoral condyle and the articular cartilage bone cores which have been inserted in the damaged area.

 

Anatomy of the Knee, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, Figure 19A Anatomy of the Knee, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, Figure 19B
Figure 18A Figure 18B

 

Anatomy of the Knee, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, Figure 20A
Figure 19A Figure 19B

 

Figure 19A and 19B demonstrate an OATS  for a small lesion and 19A and 19B show repair of a larger lesion with two plugs.

 
© Allen F. Anderson, M.D. 2017