Knee Preservation

High Tibial osteotomy

High tibial osteotomy is a surgical procedure performed to relieve pressure on the damaged site of an arthritic knee joint. It is usually performed in arthritic conditions affecting only one side of your knee and the aim is to take pressure off the damaged area and shift it to the other side of your knee with healthy cartilage. During the surgery, your surgeon will remove or add a wedge of bone either below or above the knee joint depending on the site of arthritic damage.

High tibial osteotomy is commonly used for patients with osteoarthritis that is isolated to a single compartment (unicompartmental osteoarthritis). It is also performed for treating a variety of knee conditions such as gonarthrosis with varus or valgus malalignment, osteochondritis dissecans, osteonecrosis, posterolateral instability, and chondral resurfacing.

Procedure

The goal of the surgery is to release the involved joint compartment by correcting the malalignment of the tibia and to maintain the joint line perpendicular to the mechanical axis of the leg. There are two techniques that may be used: closing wedge osteotomy and opening wedge osteotomy. The surgeon determines the choice of the technique based on the requirement of the patient.

Closing wedge osteotomy

Closing wedge osteotomy is the most commonly used technique to perform high tibial osteotomy. In this procedure the surgeon makes an incision in front of the knee and removes a small wedge of bone from the upper part of the tibia or shin bone. This manipulation brings the bones together and fills the space left by the removed bone. The surgeon then uses plates and screws to bind the bones together while the osteotomy heals. This procedure unloads the pressure off the damaged joint area and helps to transfer some of the weight to the outer part of the knee, where the cartilage is still intact.

Opening wedge osteotomy

In this procedure the surgeon makes an incision in front of the knee, just below the knee cap and makes a wedge-shaped cut in the bone. Bone graft is used to fill the space of the wedge-shaped opening and if required plates and screws can be attached to further support the surgical site during the healing process. This realignment increases the angle of the knee to relieve the painful symptoms.

Complications following high tibial osteotomy may include infection, skin necrosis, non-union (failure of the bones to heal), nerve injury, blood vessel injury, failure to correct the varus deformity, compartment syndrome and deep vein thrombosis or blood clots.

Cartilage Repair and Transplantation

Articular Cartilage is the white tissue lining the end of bones where these bones connect to form joints. Cartilage acts as cushioning material and helps in smooth gliding of bones during movement. An injury to the joint may damage this cartilage which cannot repair on its own. Cartilage can be damaged with increasing age, normal wear and tear, or trauma. Damaged cartilage cannot cushion the joints during movement and the joints may rub over each other causing severe pain and inflammation.

Cartilage restoration is a surgical procedure where orthopaedic surgeons stimulate the growth of new cartilage that restores the normal function. Arthritis condition can be delayed or prevented through this procedure.

Several techniques are employed for cartilage restoration including dietary supplements, microfracture, drilling, abrasion arthroplasty, osteochondral autograft, and allograft transplantation.

Dietary supplements: Dietary supplements such as glucosamine and chondroitin are the non-surgical treatment options for cartilage restoration. Chrondroitin sulphate and glucosamine are naturally occurring substances in the body that prevent degradation of cartilage and promote formation of new cartilage. Chrondroitin sulphate and glucosamine obtained from animal sources are available as over the counter products and are recommended for cartilage restoration. Apart from these various other nutritional supplements are also recommended such as calcium with magnesium and vitamin D as a combination, S-Adenosyl-Methionine and Methylsulfonylmethane.

Microfracture: In this method numerous holes are created in the injured joint surface using a sharp tool. This procedure stimulates healing response by creating new blood supply. Blood supply results in growth of new cartilage.

Drilling: In this method a drilling instrument is used to create holes in the injured joint surface. Drilling holes creates blood supply and stimulate growth of new cartilage. Although the method is similar to microfracture, it is less precise and the heat produced during drilling may damage other tissues.

Abrasion Arthroplasty: High speed metal-like object is used to remove the damaged cartilage. This procedure is performed using an arthroscope.

Osteochondral Autograft Transplantation: Healthy cartilage tissue (graft) is taken from the bone that bears less weight and is transferred to the injured joint place. This method is used for smaller cartilage defects.

Osteochondral Allograft Transplantation: A cartilage tissue (graft) is taken from a donor and transplanted to the site of the injury. Allograft technique is recommended if larger part of cartilage is damaged.

Autologous Chondrocyte implantation: In this method a piece of healthy cartilage from other site is removed using arthroscopic technique and is cultured in laboratory. Cultured cells form a larger patch which is then implanted in the damaged part by open surgery.

Osteoarticular transfer system (OATS): Osteoarticular transfer system (OATS) is a surgical procedure to treat isolated cartilage defects which usually 10 to 20mm in size. The procedure involves transfer of cartilage plugs taken from the non-weight bearing areas of the joint and transferring into the damaged areas of the joint.

This procedure is not indicated for wide spread damage of cartilage as seen in osteoarthritis.

The procedure is usually performed using arthroscopy. During the procedure the plugs taken are usually larger and therefore only one or two plugs are needed to fill the area of cartilage damage. The area of damaged cartilage is prepared using a coring tool which makes a perfectly round hole in the bone in the area of damage. The hole is drilled to a size that fits the plug. Next the plug of normal cartilage is harvested from a non-weight bearing area of the knee, is then implanted into the hole that was created in the damaged area. The size of the plug used should be slightly larger than the hole so that it fits into the position. This procedure allows the newly implanted bone and cartilage to grow in the defected area.

Possible complications of OATS include donor site morbidity causing pain, avascular necrosis, and fracture. Other complications such as hemarthrosis, effusion and pain may also occur. Following OATS rehabilitation is recommended by use of crutches and limiting the range of motion.