Updated: Dec 26, 2020
What causes knee pain in hikers?
Movement in the hiking activities stresses the knees a lot. Walking uphill and downhill, stepping on uneven ground, carrying a heavy backpack, and jumping down from ledges excessively load the knee joints.
Anatomy of patellofemoral joint - the kneecap and the thigh bone
The patellofemoral joint is where our kneecap (patella) meets our thigh bone (femur) at the front (anterior) of our knee.
The patella bone is a roughly inverse triangular bone with its apex at the bottom. Its back surface facing the femur can be subdivided into two bodies with a vertical ledge around the center. The patella's underside is coated with thick cartilage (4-5mm), which is the thickest in the body. This is due to the tremendous pressures applied to the patella.
Our thigh bone, the femur, has two convex femoral condyles similar to the two lips of the pulley, with a central groove for the patella ledge to slide on during bending and straightening. The femur and the patella work together like a pulley system during our daily movement.
Function of patella
The pulley system is controlled by the quadriceps with the patella's help to increase its lever arm and hence the quadriceps strength by 33-50%. The patella changes its contact area to adjust the length, position, and force angle of the quadriceps and patella tendon to act as a balance beam to provide mechanical advantage to the muscles. The patella also protects the tendon and femur bone by working as a "separator" to reduce friction and stress to the underlying bone.
Front (anterior) knee pain:
One of the reasons for hikers complaining of front knee pain is the pathological changes affecting the patella's undersurface. The changes range from mild irritation and inflammation to visible macroscopically change due to excessive and abnormal contact between the patella and the femur. This condition is also known as patellofemoral tracking disorder. It is frequently due to an abnormality in the tracking of the patella.
Why does pain/patellofemoral syndrome happen?
Activities such as downhill running, walking downstairs, distance running, or squatting increase the patella's loading may cause pain. Our body factors such as muscle weakness, tightness, post knee injury, or foot anomalies (e.g., hallux valgus) worsen the situation. Always remember that not only muscle strength imbalance will affect the patella tracking, but improper timing and coordination also play a crucial role in adversely affecting the health of the kneecap.
The illustration below shows the weak and tight muscles that may contribute to front knee pain.
The diagram below shows how the patellofemoral joint syndrome/pain developed.
Where is the source of pain?
Any structures with a rich nerve ending in the anterior knee can be the source of pain. They can be the medial and lateral retinaculum, patella fat pad, synovial lining, or subchondral bone.
Some misunderstanding about the cause of front knee pain:
1.It is commonly said that people with front knee pain due to a delay of the firing of inner thigh muscle (vastus medialis obliquus) relative to the outer thigh muscles (vastus lateralis):
It is not absolutely the case; some people who suffer front knee pain demonstrate such dysfunction but not all.
2. Only quadriceps weakness or in-coordination leads to pain:
Proper functioning of the quadriceps is crucial to the health of the kneecap. However, it is also essential to pay attention to the hip, pelvic, and low back muscles. They are important muscles to stabilize the knee.
3. I was diagnosed with structural abnormalities/patella malalignment/ patellofemoral *chondral lesions; therefore, I must have knee pain:
NO, that is not the end of the world. Researchers found that the structural abnormalities/patella malalignment are not strongly related to front knee pain, and chondral lesions can be left alone. "In fact, the worst anterior knee pain patients are those secondary to a surgical procedure that aimed at correcting structural anomalies that, possibly, were not the cause of the pain and disability the patient suffered." by Vicente Sanchis-Alfonso
*Chondral lesions can be a tear, crushed, fracture, or a cyst on the cartilage covering a joint's bone.
Loading fact for the knee:
The compression force in the joint between the kneecap & thigh bone (patellofemoral joint) during different activities:
Level walking: 0.5 times body weight
Upstairs walking: 3-4 times body weight
squatting: 7-8 times body weight
The signs and symptoms of kneecap (patellofemoral) syndrome:
It occurs during running (particularly downhill), stepping downhills, repeated knee movement such as distance running/trekking. The pain can be vague and nonspecific around the kneecap. There may be minor swelling around the patella, occasional clicking, giving way of quadriceps. Unless in severe conditions, the range of motion in the knee is usually normal. The patella's gliding may be limited, or a decrease in muscle bulk's size in the inner thigh may present.
What should we do if knee pain develops?
Getting a proper assessment to find out the underlying reason for the pain is essential. Consult the healthcare professional if you have any doubt. Another priority of treatment is to reduce acute pain and swelling if present. Rest and ice (15 minutes, 3 times/day) to the affected part could help.
There are two common mistakes we should avoid if we develop knee pain.
1. I really love hiking. Therefore, I can't stop even if I developed pain. So I take painkillers and continue the activities I like.
It is not wrong taking NSAIDS or painkillers under prescription. However, do consider that there may be other underlying problems such as muscle weakness required to be correct. Giving attention to the condition as early as possible is beneficial to our health, allowing us to prolong our hiking lifespan.
2. I should quit hiking and live a sedentary life.
Don't jump to a conclusion too early. Again consider the underlying cause of the pain and tackle it, ask for proper and professional help. You can change your hobbies if needed. However, keeping your knees in good condition is crucial for a healthy lifestyle; we need to walk around and exercise even if we are not active hikers.
Prevention and adaptation for kneecap pain:
Prevention is always the best cure. Before problems happen, tune-up your low back, hip, and thigh muscles, including strength, coordination, and agility, for future hiking activities and make certain adjustments to the hiking routine:
Taking a stretching break
Going downhill in a zigzag pattern
Taking your time to increase the intensity of hiking
Choosing suitable hiking boots
Reducing the load of your backpack
Assisting with hiking poles
This article is not intended to replace medical advice. Seek professional help if you encounter any medical problems.
Brukner P, Khan Karim. Clinical Sports Medicine. McGraw Hill Book Company Australia. 1995 p373-378.
Kapandji. The Physiology of the Joints. Churchill Livingstone 1985. P98-101
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