Dr David Su, Medical Director at The Orthopaedic Centre, shares the common causes of chronic knee pain and other knee problems like knee osteoarthritis and Anterior cruciate ligament (ACL) tears.
Chronic knee pain for people below 45 is commonly caused by overdoing and overuse from sports. As for those above 45, the common cause is age-related wear and tear leading to degenerative knee conditions. Three common knee pain problems are Patellofemoral Pain Syndrome (runner’s knee), knee osteoarthritis and knee ligament and cartilage injuries.
Runner’s knee happens when the kneecap is misaligned and rubs against the lower end of the femur. This is often caused by repetitive stress on the knees due to an excessive running or cycling routine. Dr David Su recommended that runners incorporate cross-training in their fitness routine to get a good mix of load on joints and muscles. Some supplements can help to stimulate the formation and repair of the cartilage or keep it from deteriorating.
Knee osteoarthritis, which is the wearing away of the knee cartilage, is the most common form of knee arthritis. There is no cure for this degenerative disease but there are ways to decelerate the cartilage erosion. Shedding 5kg of weight, especially for those who are overweight, can reduce knee pain by 50%. Knee joint injections like hyaluronic acid and platelet rich plasma (PRP) therapy are common temporary measures as well.
ACL tear is the most common ligament injury, especially for soccer players. Physical therapy is often used to restore the knee. However, orthopaedic specialists may advise for ACL reconstruction in the case of complete ACL tears.
Anterior knee pain amongst runners and athletes is very common. It is sometimes referred to as “runner’s knee”. It is a symptom that should not be taken lightly or neglected. Being a “weekend warrior”, it is even more important to pay attention to this symptom as your muscles, tendons and ligaments may not be as well conditioned as that of an active professional athlete.
There are several structures in the front of the knee, the most prominent of which is the patellar bone. This is also sometimes referred to as the kneecap. A tendon called the quadriceps tendon attaches above the patella & a tendon called the patellar tendon attaches below the patella. The patella glides in the front of the knee over the knee bone called the femur, making up the patella-femoral joint.
As we run the muscles contract and move the kneecap in the front of the femur. If our thigh muscles are weak, the pull on this quadriceps tendon is not strong and the kneecap is not able to glide well in the front of the femur. This abnormal gliding can give rise to mechanical knee pain as the patella knocks abnormally on the femur causing pain. Similarly the tendons above and below the knee cap could be inflamed from overuse causing pain. This is known as a tendinosis.
The structures within the knee like the menisci or the cruciate ligaments could also be injured to give the sharp pain. The most common structure to be injured within the knee is the meniscus. The meniscus is a type of cushion that protects the cartilage within the knee during impact. When we accidently twist the knee or land awkwardly while running, its possible for the meniscus to be injured. Sometimes the cartilage on the patella gets injured and the cartilage injury can cause severe pain, especially if there has been repetitive injury to the kneecap. The cartilage over the patella-femoral joint becomes thinned out and that condition is known as chondromalacia. However a cartilage injury of the patellar is uncommon.
It is best to seek an expert medical opinion with an orthopedic surgeon if the knee pain persists. Once a ligament or meniscal knee injury has been ruled out, physiotherapy can be started to strengthen the muscles. A structured physiotherapy program is useful to return a person to sports. Some patients do very well with knee taping and by changing their running pattern. Occasionally if there is structural damage to the knee and when physiotherapy has failed, surgery may be necessary. Knee surgery is usually done via arthroscopic (keyhole) surgery and there is minimal downtime following surgery.
Visual adapted from: https://www.123rf.com/stock-photo/14310222 , last assessed 20th Mar 2018
Seeking treatment early may prevent need for replacements
I always observe how patients with knee pain walk into my consultation room. From that, I can tell which leg is hurting, and how bad it is hurting .
After all, knee pain is one of the most common symptoms that I see in my practice.
Mr X hobbled into my clinic one day, complaining of pain in both knees. He could not play golf, and even walking around a shopping centre with his wife was painful.
He had tried medication (painkillers, supplements, traditional Chinese medicine), medicated plasters, gels, walking aids, physiotherapy, lubricant injections and even had special shoes designed to shift the stress away from the knees.
He had read up extensively about the surgical options available and he wanted my opinion.
After looking at his X-ray scans, which showed severe osteoarthritis, and considering his age of 69, I recommended the most reliable operation for someone in his situation: A total knee replacement.
He then asked a question that I had heard many times before.
Was there any way to preserve his knee and avoid replacing it with metal and plastic?
My answer was no, not in his case - his arthritis was too advanced.
But I have wondered if I could have preserved his knees had he come to see me years earlier.
VITAL PARTS OF THE KNEE
Knee preservation surgery is a broad concept that uses minimally invasive keyhole techniques (arthroscopy) to preserve the vital components of the knee.
Knee arthritis occurs when there is cartilage damage, which causes pain and stiffness. Vital components of the knee that contribute to its longevity are the meniscus, cartilage and ligaments.
The meniscus is a crescent-shaped structure made of cartilage. It absorbs shock and stabilises the knee. Forty years ago, surgeons routinely removed the entire meniscus when it was torn.
We now know that removing the whole meniscus is a bad idea. Without it, the knee will almost always develop arthritis .
There is now a big push to repair a meniscal tear and even if you cannot repair it, only the torn potion should be removed.
The cartilage is the white shiny layer covering the ends of the bones. It has lubricating and shock-absorbing qualities. Once you damage it, however, it has limited potential of healing itself.
But we know that cartilage damage in the knee should be treated early. By the time the damage is widespread, there is little doctors can do to regenerate the cartilage.
The patient may have no choice but to undergo a knee replacement with metal and plastic components.
Mr Y, 49, a university lecturer, was fortunate. He sought help early and managed to preserve his knees.
An avid basketball player, he started to experience pain in both knees after a game. It worsened to a point where he could not stand in front of his class for more than 15 minutes.
Magnetic resonance imaging scans showed cartilage damage, as well as "loose bodies" in his knees - little pieces of bone and cartilage that form during the degeneration process. These free-floating objects occasionally jam up the knee, causing a sudden locking sensation.
It is like having a pebble in your shoe when you are walking.
The loose bodies accelerate cartilage damage, grinding away the cartilage when the knee moves.
The advantage of keyhole surgery is that even if both knees are operated on at the same time, the patient can often walk out of the hospital the next day.
Mr Y eventually underwent keyhole cartilage regeneration and removal of loose bodies in both knees. He is now able to stand and teach for an hour.
More importantly, he started playing "old man basketball". He described it as more passing, less running and jumping, and playing with people his own age.
If he continues to take care of his knees and modify his activities to avoid further wear and tear, he might not require a knee replacement at all.