1. Lifeline multi-specialty hospital
Perungudi, Rajiv Gandhi road
Tamilnadu, India
T.+91 9176640002 (personal mobile)
27, 1st avenue, Besant nagar
Chennai 600090, India
Mobile: +91 9176640002 & +91 9282165002
The mobile joints of the limbs and spine are covered by a shining, smooth and elastic articular cartilage. Depreciation and degeneration of this tissue results in the well known condition, osteoarthritis which commonly affects the joints of the knee, spine, ankle, shoulder and less commonly the hips in the Indian population. Activity related pain and stiffness are the common symptoms. Joint replacements have offered lasting pain relief and improved the quality of life to the suffering elderly population of arthritics. While joint replacements are a solution for advanced joint destruction in the elderly, many a young person having joint pain has had no lasting remedy to his ills. The investigation and management of the young patient with arthritis is a challenge to many orthopedic surgeons. In this article, I will discuss the mechanisms of injury, recent advances in radiological imaging, surgical techniques, and future trends and technologies of managing cartilage damage.
Articular cartilage is the lining firm and elastic tissue at the ends of the long bones. It is rich in water, proteo-glycans, proteins, and collagen. It is avascular (lack of blood vessels) and aneural (lack of nerve endings). It derives its nutrition from the synovial fluid. Its constituents are hydrophilic and synovial fluid is driven in and trapped in its matrix on loading. This makes it turgid. This turgidity contributes to the shock absorber like function of articular cartilage.
It is a precious tissue like the nervous tissue of the brain, spinal cord and heart muscle. In normal life there is a balance between the synthesis and destruction of articular cartilage. The capacity to regenerate articular cartilage diminishes with aging (fourth decade). When articular cartilage is damaged, there is little chance for its repair. Damaged cartilage sets the ball rolling to a sequence of degenerative changes leading to osteoarthritis of the joint and the need for arthroplasty (a total joint replacement).
Mechanism of articular cartilage damage- Injuries to the articular cartilage of the knee can serve as the basis of this discussion as it is the largest joint and knee injuries are very common. The same principles will apply to the treatment of other joints like the hip, ankle, shoulder and elbow.
1) A high impact mechanical injury to the knee occurs in sports. The frequent mechanism in sports related articular cartilage injuries is an impact load seen in association with a ligament injury. Anterior cruciate ligament (ACL) injuries of the knee are the commonest ligament injuries. Bruising of the articular cartilage of the femur (thigh bone) is a common accompaniment seen on the MRI scans of these patients. Many patients undergo an ACL reconstruction in the hope that this will postpone the onset of arthritis, yet are at risk of developing arthritis due to the progression of articular cartilage damage.
In addition to the above sudden incident, repeated and excessive overloading of the joint can lead to articular cartilage damage. The conditions responsible are
a) Joint deformities like bow legs and knock knees which produce a mal-alignment and overload on one half of the joint.
b) Obesity. The implication here is that weight reduction can help to reduce further ongoing damage.
2) Thermal injury is another mechanism responsible for cartilage injury and is inadvertently applied in the conservative treatment of joint pain prescribed by many orthopedic surgeons and physiotherapists. (Short wave diathermy is the main offender). Lasers used in arthroscopic surgery also can cause cartilage damage.
3) Chemical injury occurs in infections like septic arthritis (pus) and inflammatory diseases like Rheumatoid arthritis.
The only known physiological ways of maintaining health of the articular cartilage is regular exercise. This not only tones the surrounding muscles, but by forcing the nutrient synovial fluid into cartilage maintains its health.
Evaluation of articular cartilage- This can be achieved surgically by arthroscopy or by imaging techniques. Arthroscopy allows a direct visual evaluation and mapping of focal loss.
Imaging of cartilage-Only advanced cartilage damage is discerned on plain x –rays by a diminution of the joint space. This is an indirect method to evaluate cartilage loss.
Special MRI scans can show areas of focal cartilage loss or micro-fracture.
Molecular imaging of articular cartilage is an exciting prospect of assessing diminution of the normal cartilage thickness. It is a more sensitive and specific MRI technique to evaluate articular cartilage abnormalities. In this technique, a substance that is taken up by the cartilage is injected. The uptake of the dye is dependent upon the molecular content of the matrix and collagen. Gadolinium, an intravenous contrast agent is used to obtain a MRI image of the actual molecular content of cartilage. This technique is called delayed gadolinium enhanced Magnetic Resonance Imaging of cartilage-dGEMRIC
A recent study reported that individuals who exercise regularly have a higher dGMERIC index (denoting higher cartilage content) than those who are sedentary. This is a fillip to those who keep fit by exercise.
Optical coherence tomography (OCT) is an optical imaging technique that allows for non destructive high resolution cross sectional imaging of articular cartilage. It is similar to the familiar ultrasound except that in this technique infra red light is shone on the joint and an echo graph is generated. It can obtain an optical biopsy of cartilage defects and the response to surgery. This modality can contribute to earlier diagnosis of articular cartilage injury.
Surgical techniques of regenerating or repairing cartilage-
Once a diagnosis of articular cartilage damage is made, most commonly by an arthroscopic examination, the orthopedic surgeon is confronted with two options “To do or not to do” (treat it or ignore it). Longer term studies may indicate that it may be better to treat larger sizes of these lesions in active individuals. The surgical options to treat focal cartilage loss fall under two headings, a) a reparative one and b) a restorative one. The restorative technique involves substitution of areas of focal articular cartilage loss by the same tissue. It can be obtained from a cadaveric source (allograft) or be harvested from the patient’s own body (autograft. In a cartilage transplant, a rice size piece of articular cartilage is harvested at an arthroscopic operation from the patient’s knee and sent to the laboratory for culture. After a gap of six weeks, the multiplied cartilage cells grown in the culture tube are re-implanted into the patient’s joint at an open operation. This procedure is called autologous chondrocyte implantation (ACI). This technique is available in India at an affordable cost. It is particularly suitable for young patients with cartilage lesions following a sports injury.
In a restorative technique a reparative tissue is generated by surgery. There are a number of techniques involved and some can be done through key hole incisions (arthroscopic surgery). Microfracture is one such procedure. They have been proved to confer lasting pain relief in younger patients and are a worthwhile low cost surgical option to consider. The patient must be willing to undergo an extended recovery process in both techniques.
In addition the background scenario responsible for articular cartilage damage must be set right. This means correction of mechanical mal-alignment by an osteotomy and ligaments reconstruction to restore stability.
Latest trends
Autologous chondrocyte implant- This is being done in India. Cartilage cells are harvested by a key hole surgery from a health part of the knee. These cells are cultivated in the lab for four to five weeks. These multiplied cartilage cells are then re implanted into the defect through an open procedure.
Future trends and technologies-
Gene therapy- Genes that can code for cartilage enhancing growth factors can be used to synthesize these growth factors. These growth factors can be delivered to target cells and tissues.
Functional tissue engineering is an approach to enhance tissue regeneration and provides the possibility of producing tissue that is bio-mechanically, bio-chemically and histologically similar to the native articular cartilage.
Stem cell manipulation involves the differentiation of fetal umbilical cord cells into different tissue types like cartilage, tendon or bone.
To summarize, articular cartilage defects are the precursors of osteo-arthritis. Early methods of detection should include an evaluative arthroscopy and special MRI scans. Currently available surgical techniques of repair or regeneration of cartilage can be adapted to the needs and interests of the patient. If undertaken the progression of cartilage loss to end stage arthritis can be halted. The patient can continue to use his own joint and the need for a total joint replacement (arthroplasty) averted.
ontde1Њ an approach to enhance tissue regeneration and provides the possibility of producing tissue that is bio-mechanically, bio-chemically and histologically similar to the native articular cartilage.
Stem cell manipulation involves the differentiation of fetal umbilical cord cells into different tissue types like cartilage, tendon or bone.
To summarize, articular cartilage defects are the precursors of osteo-arthritis. Early methods of detection should include an evaluative arthroscopy and special MRI scans. Currently available surgical techniques of repair or regeneration of cartilage can be adapted to the needs and interests of the patient. If undertaken the progression of cartilage loss to end stage arthritis can be halted. The patient can continue to use his own joint and the need for a total joint replacement (arthroplasty) averted.
