Believe it or not, knee problems are the second most common musculoskeletal complaint for which people consult their doctor.
In the past we were led to believe the ‘cartilages’ were the main perpetrators of knee problems and this led to much indiscriminate surgery for their removal (menisectomy). Now we know differently; the kneecap (patella) is the more common source of reversible knee trouble.
The opening and closing knee is a beautiful structure. It allows us to
swing the legs past one another during walking, while it also
shortens and lengthens the leg
The knee gets into difficulty because it's a very tight joint. It is also quite a complicated joint. On the surface, it looks to be a fairly straightforward backwards and forwards hinge, but under the skin it is indeed a little more complex.
The main intricacy of the knee is a sophisticated locking mechanism that allows you to brace the leg back, so it doesn’t buckle and give way under you as you bear weight. A locking mechanism not working properly will cause the beginnings of knee trouble. It causes more lateral instability of the knee and it also reduces the hydraulic cushioning effect of the fluid held within the joint capsule.
The 'knee cartilages' are a juicy fibro-elastic buffer sandwiched between the femur and tibia and forming the knee-lock mechanism
The major joint of the knee is formed by two large round knobs (femoral condyles) at the bottom of the thigh bone (femur) articulating the top of the shin bone (tibia). As you bend your knee the tibia slides around to the back of the condyles. They are kept in place, and on track, by two wedge-shaped cartilages (the menisci) that pack out the triangular spaces at the margins of the joint. These are the aforementioned knee 'cartilages'. Wear and tear of the knee cartilages is greatly influenced by ankle stability and the inner the arches of the feet.
Knee bending and straightening is caused by the shin bone (tibia) sliding backwards and forwards under the femoral condyles
Knee movement during bending and straightening is kept on track by the wedge-shaped knee 'cartilages' or mensci
The quadriceps muscle at the front of the thigh is the knee-straightening muscle. The important vastus medialis muscle on the inner side of the thigh does the final 15 degrees of straightening to bring the leg into a locked position at the knee. It is critically important for bracing the knee through its action of compressing the knee cap against the hydraulic sack of the knee joint capsule. This pressurises of the fluid inside the knee and helps to keep the opposing cartilage surfaces from grinding on one another too much as you take weight through the leg.
The kneecap is a shield-shaped sesamoid bone at the front of the knee, covered by a glistening plastic buffer of joint cartilage. It exists in the quadriceps tendon as a friction defraying mechanism to prevent the tendon from chafing as it pulls down across the front of the bending and straightening knee.
The right amount of fluid held within the knee capsule is critical for hydraulic cushioning and helping to spring the femur and tibia apart on weight-bearing
This glancing contact at the front of the knee is known as the patello-femoral joint. Friction between these two cartilage-covered surfaces is the most common cause of knee pain. In the condition known as acute chondromalacia patellae, the knees may be swollen, hot to the touch and painfully uncomfortable, particularly on going down stairs.
The kneecap (patella) prevents the quadriceps tendon wearing through, like rope fraying around a pulley
For the locking mechanism of the knee to work well, the opposing joint surfaces have to be level, on the horizontal. Any kind of inward or outward angulation at the knee causes wear of the protective cartilage buffer between the upper and lower legs, either in the medial (inner) or lateral (outside) compartment of the knee joint.
Deficiency in full knee straightening, or knee alignment, can cause knee pain - and eventually osteoarthritis
At the same time, the knee joint must be able to fully straighten. Even the slightest deficiency in full extension of the knee will mean the joint imperceptibly wobbles, introducing crushing micro-trauma to the wedge-shaped menisci, or joint 'cartilages'.
Knee alignment is critically important to the prevention of knee problems, the most serious of which is osteoarthritis of the knees. The most common cause of defective joint alignment is congenital or acquired bow legs or knock knees, even though the angulation may be barely visible. Another common cause of knee mis-alignment is progressive falling of the foot arches, for which you may need orthotic correction.
Sarah Key Physiotherapy heel inserts for correction of faulty knee alignment
Click here for more information and to buy
Knee alignment difficulty causes knee problems at both the patello-femoral and tibio-femoral joint. With bow legs the medial compartment of the knee suffers excessive wear, whereas the lateral compartment suffers more with knock-knees, as the cartilage bed on the tibial plateau is eroded down and worn away.
Faulty knee alignment also causes tracking problems of the patella as the knee bends and straightens. The patella drags laterally with knock knees and medially with bow legs. In effect, the kneecap has to track around a corner (called the 'Q angle') which leads to added patello-femoral friction, swelling, inflammation and knee pain.
For Inward & Outward Knee Angulation Correction
One of the most simple-is-genius effective ways to deal with inward or outward angulation of the leg at the knee joint is a simple heel wedge. We like to use a cork and pig skin covered wedges custom made in London.
In the past, the highly invasive and complex wedge osteotomy orthopaedic procedures were performed by surgeons, involving cutting a wedge-shaped divot of bone out of the tibial (shin) shaft to realign the legs. Bloody and highly disruptive (weeks in plaster of Paris cast) as these procedures were, they were highly effective in giving years more in pain-free life to knees. A simple cork in-sole wedge is just as effective, and miles simpler in manifold ways.
This wedge would ease a knock-kneed deformity of
the right leg, or a bow-legged deformity of the left.
Wedge heights vary from 2mm-4mm.
Knee problems can also be caused by the presence of a longer leg. To keep the body in balance there's an automatic and subconscious tendency to shorten the longer leg by keeping that knee slightly bent. Over time, this causes subtle, ongoing friction behind the kneecap, otherwise known as patello-femoral rub or chondomalacia patellae.
A slightly longer leg is a common cause of knee trouble through friction begind the kneecap
Chondromalacia patella irritation behind the kneecap (patella). It is usually caused by faulty tracking of the kneecap in the grove at the front of the lower end of the femur. It will be dragged sideways if the leg is knock-kneed or bow-legged and this scours or scratches the underside of the kneecap. If the leg has a flexion contracture of the knee, usually caused by the leg being longer, the back of the kneecap will also be abraded, causing patello-femoral rub or chondomalacia patellae.
The furry outgrowths in the cartilaginous underside of the kneecap causes friction, inflammation and pain
Leg length difference also has a profound effect on the lower back, with the spine tending to slide imperceptibly towards the side of the shorter leg, as well as forwards on the sacral table on that side. The static twisting strains induced by a shorter leg have long been associated with lower back pain.
Very modest efforts to minimise leg length discrepancy have an immediate effect on the knees - and the back. The most definitive measurement of leg length difference is through CT Leg Length scanning, although the radiation levels to the body are high. A CT scan is also not entirely necessary as the correction is only ever approximate, to minimise the inflammatory reaction from the body's bony architecture.
For Shorter Leg Correction
It's important to commit to a heel raise entirely or not do it al all, since going on and off the raise is vexatious to the soft-tissues of the skeleton as they attempt to adjust (and the knee may become more swollen and painful). When first adopting a heel it's best to wear it 24/7, or at least for as much of the daylight hours as possible. Going bare-footed is best avoided for the first 3 months. Sarah Key Physiotherapy uses heel raises custom made in London
A cork heel raise is very effective for minimising leg length discrepancy.
Key Physiotherapy heel raises vary between 2mm and 4mm
Return to Knee Physiotherapy
Return to Home page
Australian and New Zealand buyers can buy the books from Booktopia