Pain in the knee is one of the commonest clinical presentations in pain clinics worldwide. Sri Lanka is no exception. Knee pain can be due to
1. Arthritis of the knee
2. Trauma
3. Infections
In this column I will discuss mainly about arthritis of the knee.
Anatomy of the knee
Diagram of the knee joint
The lower end of the long bone Femur and the upper ends of the Tibia and Fibula are the three long bones involved in the formation of the knee joint. These bony ends are separated from each other by cartilages, lateral and medial meniscus. Cartilages prevent the bony ends touching each other and avoids friction. To keep the joint in place and maintain the stability there are ligaments in and around the joint. They are anterior and posterior cruciate ligaments, lateral and medial co lateral ligaments.
Arthritis of the knee
There are many types of arthritis in the knee. The commonest type of arthritis is osteoarthritis.
Normal knee (L) Arthritic knee (R)
It is associated with pain, swelling and stiffness. Day to day activities become difficult, especially, walking, standing and climbing stairs. Pain is reduced while seated.
Osteoarthritis occurs mostly in the weight bearing joints, mainly the knee as it has to hold the full weight of the body. Other joints too can be affected. There is wear and tear in the knee, and this leads to degeneration with the growth of bony spurs. In some people with increasing age the cartilages get worn out and the Femur touches the Tibia (bone on bone). The knee becomes very painful due to this. In some, bony spurs are formed. All these factors lead to inflammation with swelling of the knee. Osteoarthritis is more common among Sri Lankans compared to the Caucasians. It is more common in females, overweight individuals and those advancing in age. We have a predisposition to the disease due to genetic makeup. Squatting position does not help the knee. A large percentage of Sri Lankans use the squatting pan in toilets, and strangely the hip favours the squatting position. Hip issues are less common in Sri Lankans compared to the Caucasians.
Diagnosis
Clinical presentation, X ray of the knee, MRI scans - rarely needed
Treatment
1. Reducing weight
2. Simple analgesics
3. Strong analgesics - Fentayl patch (this is opioid patch)
4. Physiotherapy
5. Injections to the knee. Steroid and Hyalase, Platelet rich plasma, Stem cells (not enough evidence yet)
6. Referral to an orthopaedic surgeon as a last resort for a total knee replacement or a compartmental knee replacement. However, knee replacements will not satisfy all patients. Around 20 percent may not be satisfied with the replacement.
7. Nerve blocks for inoperable knees due to many factors and failed knee replacements. A genicular nerve block involving three branches can be blocked and cauterised. In UK patients were referred to me by orthopaedic surgeons for this procedure for failed knee replacements and inoperable knees.
Radio frequency ablation of the Genicular nerve
Readers note there is no permanent cure for osteoarthritis of the knee other than a total knee replacement of the knee. Then again total knee replacements will only last around 10-12 years. Therefore, do not visit doctors hoping that they will cure the knee problem. As pain consultants we can help patients to alleviate the pain and manage the problem. But the underlying issue of arthritis cannot be reversed. I have noticed Sri Lankan patients visiting Consultants for help with their knee issues hoping the knee will he reversed to normal. This is like any other mechanical joint. Once it’s worn out the time is up.
Trauma to the knee
It is mainly an injury common in sportsmen. The most common is injury of the anterior cruciate ligament (AC tear). Rupture to the tendon can occur. Treatment is mainly surgical. Pain relief is by methods as described above. Injecting of Platelet rich plasma (PRP) into the joint can help the healing process.
Infection of the knee
A germ such as a bacteria getting into the knee can cause septic arthritis with severe knee pain. Treating the primary foci will help decrease the pain.
(To be continued next week)
Dr Namal Senasinghe MBBS, Dip in Pain Med, FFARCS, FFPMCA, CCST(U.K) is a Consultant in pain medicine at the London Pain Management Centre, No 31, Horton Place, Colombo 7, Sri Lanka (hot line 0767155716)