Young Patients with Old Knees

Osteoarthritis (OA) is one of the top ten global diseases listed by the WHO and the knee is the most commonly affected joint. The incidence of OA in patients above 65 years is 11-15% and for patients aged 30-50 is 5%. OA is a chronic joint disorder in which there is progressive softening and disintegration of articular cartilage, accompanied by the new growth of cartilage and bone at the joint margins (osteophytes) and capsular fibrosis. It was previously thought that OA seen in old age is inevitable as a result of normal wear and tear. But in young and middle-aged adults, current evidence shows that the cause could be due to metabolic changes in cartilage following a knee injury.

Total knee replacement (TKR) is the ideal choice of treatment for an elderly patient after the failure of conservative treatment for osteoarthritis. Evidence from current literature shows prosthesis survival above 90%, for total knee arthroplasty in the elderly population at 15 years.

Could we consider the same treatment for the ‘younger’ patients with arthritis, who have failed conservative treatment?

Many studies demonstrate that total knee prostheses in young patients fail more often than that in older patients, but the results of different studies may be difficult to compare. The failure rates observed during the first ten years after a total knee replacement from the Swedish arthroplasty register is 12% for patients above 65 years and 4% for patients above 75. Young patients wear off their joint surfaces more than older patients. Wear of bearing surfaces in artificial joints is dependent on the amount of movement in the joint. The more you walk on your replaced total hip/knee joint, the more you wear away the joint surfaces. (It is about the same phenomenon as wearing off of the tyres – the more you drive your car, the more you wear the tyres). In the polyethylene-on-metal joint, it is the softer polyethylene that wears away.

The most common causes of preventable knee injury are those involving the meniscus and anterior cruciate ligament. Incidence of developing OA in a knee with absent meniscus and ACL is 100%. Do we have any other options for these young patients and why is it important?

For prevention and treatment of OA in young adults:

Joint Preserving Surgery:

Meniscal Preservation Surgery
Cartilage Preserving and Regenerating Surgery
Osteotomy

Meniscal Preservation:

Meniscal Repair: The aim of repairing the meniscus is to try and protect the joint surfaces from possible later wear and tear arthritis. The operation involves passing sutures or special fixation devices to repair the torn meniscus. Most repairs can be performed arthroscopically (key hole), but for large tears and tears in particular places, it may be necessary to make a small incision on the side of the knee in order to tie the sutures. Post-operative rehabilitation is slower than after a standard knee arthroscopy as the meniscal repair needs to be protected from excessive forces whilst it heals. Repair of a torn meniscus will lead to it healing in approximately 70% of cases. Unfortunately, 30% of repairs will not heal and for these patients, if they have persistent symptoms, a further arthroscopy is required to remove the torn portion of the mensicus.

Meniscal Replacement: Patients who lose mensicus volume at a young age will inevitably develop wear and tear osteoarthritis and if they have persistent symptoms meniscal replacement techniques offer a way of reducing and delaying this risk. A small percentage of patients who lose all or part of their meniscus will be suitable for a meniscal replacement technique. Patients who lose only part of their meniscus might be suitable for implantation of an artificial device, the menaflex or collagen meniscal implant. Patients who lose the meniscus totally will not be suitable for this device but might be suitable for a mensical transplant. Both these procedures are safe. These operations involve a longer rehabilitation period and there is good evidence that they do improve symptoms. However, the patients are unlikely to return to high-impact sports.

Cartilage Preserving and Regenerating Surgery

There is a lot of ongoing research in cartilage (gristle) preservation and regeneration. The presence or absence of cartilage (gristle) is the difference between normal and arthritic joints. There is not one technique or procedure that satisfactorily addresses this issue. The basic principle is to have a joint that is well aligned (straight) with the patient’s anatomy and has normal movement for the cartilage regeneration procedure to be successful. The flaps of relatively healthy cartilage can be attached back using biological glue or bio-absorbable pins. This may be combined with micro-fracture or retrograde drilling to enable the stem cells to come in contact with the healing area. In scenarios where cartilage is deficient in focal areas, various cartilage regeneration techniques are employed. These include;

Micro-fracture where specific instruments make holes perpendicular to articular cartilage defect to allow stem cells to differentiate into chondrocytes.
Autologous Chondrocyte Implantation (ACI) involve harvesting cartilage cells arthroscopically, which are then cultured in lab to increase their number and implanted back in the defect covering it with lining membrane of the bone. The second part of the operation usually involves open surgery.
Matrix-Induced Cartilage Implantation/Transplantation (MACI/ MACT) is similar to ACI, however, the cartilage cells are embedded into a membrane that is implanted in the defect.
Mosaicplasty is another procedure where plugs of cartilage and underlying bone are taken from a non-weight-bearing part of the joint and arranged into the damaged area.
OATS (Osteochondral Autograft Transfer System) or mega OATS are similar to mosaicplasty, however, the plugs of cartilage and bone tend to be much larger and hence the defect is filled with one or two plugs usually.
Osteochondral Allograft is used for large defects of cartilage and underlying bone. These grafts are taken from a donor from the tissue bank and are shape matched to the patient’s joint. This involves open surgery to fix them in place. The size can be variable depending on the defect that is being addressed.

Osteotomy:

Osteotomy around the knee is an operation to alter the alignment of the leg. It is mainly used in the treatment of arthritis in young patients to avoid knee replacement but also has a role in the treatment of complex knee instability. This operation is aimed at realigning the leg so as to reduce the forces of body weight that go through the inner aspect (medial) of the knee and transfer them more to the undamaged normal outside (lateral) compartment of the knee. The operation is particularly suited for young and very active patients who wish to avoid artificial joint replacement and who have a normal lateral compartment of their knee without any significant wear and tear arthritis. Most patients get good pain relief from an osteotomy. Although the pain is often relieved than abolished, it allows a much higher level of functioning. Activities of daily living are usually comfortable. However, as knee arthritis still exists, it can still hurt, particularly if overloaded with high-impact activities or sports. One role of osteotomy is to avoid/delay the need for a total knee replacement and hopefully avoid a situation where a second TKR is required. The major advantage of an osteotomy over joint replacement is that you still have a natural knee with no bridges burnt. You have fewer restrictions than after a knee replacement. If the knee deteriorates and the wear and osteoarthritis progress, it will require a knee replacement.

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