Knee Pain

The knee is a hinge joint which contains two joints:

- the tibiofemoral joint – between the tibia (lower leg bone) and femur (thigh bone)- the patellofemoral joint – between the patella (knee cap) and the femur.

The tibiofemoral joint is considered the “knee joint” but problems with the patellofemoral joint is an extremely common cause of knee pain.

The knee also contains ligaments which keep the knee stable as well as two cartilage menisci that help to cushion the joint.

The hamstring and calf muscle complex at the back, the hip flexor/quadriceps muscle groups in the front and gluteal muscles on the side help to stabilize and control movement of the knee.

Acute knee pain is commonly caused by the malfunction of or damage to one or more of these structures and/or a weakness of the surrounding muscles. There are other causes of knee pain which are less common in the general population.

Specific tests are performed to diagnose one of these causes if symptoms don’t match those of the more common injuries.

Some of the common causes of knee pain are:.

- patellofemoral pain/joint syndrome, - patellar tendinopathy, - iliotibial band friction syndrome, - fat pad impingement, - meniscus tear (medial or lateral), - medial collateral ligament sprain, - anterior cruciate ligament sprain/rupture, - posterior cruciate ligament sprain, - articular cartilage injury, - patellar dislocation

Patellofemoral Pain Syndrome:

This is the term used to describe pain under or around the kneecap (patella). The pain is usually of an achy quality and may be accompanied by swelling or a clicking sound. The pain is usually aggravated by going up/down stairs or hills, squatting, kneeling or sitting with the knees bent for prolonged periods of time. It is very common in runners. It can affect one or both knees. Patellofemoral Pain Syndrome results from abnormal movement or tracking of the patella on the femur during bending of the knee. This can lead to inflammation and damage to the surrounding tissues, particularly the cartilage on the underside of the patella.

The abnormal movement of the patella can be caused by:

1. Overuse/overload: the pressure between the patella and the femur increases when the knee is bent. Repetitive weight-bearing impact of the knee in sports such as running may predispose the athlete to patellofemoral joint syndrome. 2. Muscle imbalance: the quadriceps muscle group is responsible for the movement of the patella. If the outer fibres are stronger or tighter than the inner fibres, or if the iliotibial band (ITB) which runs down the outside of the thigh, is very tight, this can lead to patella tracking problems. 3. Other mechanical problems: mechanical problems such as pronating (flat) feet or increased Q-angle (knock-kneed appearance) affect the movement of the patella and may predispose to patellofemoral joint syndrome. Those with small, protruding patellae are also more prone to patellofemoral pain syndrome.

Role of physiotherapy

Recent research has shown that physiotherapy intervention for patellofemoral pain syndrome results in ‘significantly greater reduction in the scores for an average pain, worst pain and disability’ than no treatment (1).

Your physiotherapist will:

1. Identify the cause of the patella tracking problem 2. Improve the position of the patella using: • Mobilisations of the patellofemoral joint • Muscle releases and stretches, particularly of the structures on the outside of the knee and thigh, such as the ITB, gluteals and lateral retinaculum • Muscle strengthening of the hip abductor and external rotator muscles, as well as the quadriceps muscle. A particular focus is placed on the vastus medialis (part of the quadriceps muscle, on the inside of the knee) which controls patella movement. At Bay Active Physio we use EMG biofeedback which measures muscle activity to allow us to accurately measure and improve muscle activation • Taping of the patella 3. Electrotherapy modalities, such as ultrasound, to reduce swelling 4. Assessment and correction of other biomechanical causes of abnormal patella tracking 5. Advice regarding return to sports training and strategies to prevent re-occurence

Patellar tendinopathy

This term refers to pain which results from an overuse injury of the patellar tendon. Tendons transmit the force from muscle to bone. They are made up of parallel collagen fibres and are subject to great tensile stresses. Tendons are able to withstand large tensile forces, moderate shear forces but not much compressive force. When the stress/strain increases on the tendon past a certain point, the collagen fibers begin to deform and tear and eventually tendon failure occurs. Patellar tendinopathy is an umbrella term for tendinosis (chronic degeneration of the tendon without inflammation), paratenonitis/tenosynovitis (inflammation of the fluid filled area located between the tendon and the sheath that surrounds it i.e synovium), and tendinitis (inflammation of the tendon resulting from an acute injury). Patellar tendinopathy is often referred to as ‘jumper’s knee’ because it often occurs in jumping sports eg. basketball, volleyball, long/short/high jump. It is also seen in athletes who change direction frequently an can occur in sports where neither jumping nor direction change occurs. The most common site of the tendinopathy is the inferior pole on the patella. It will be painful with palpation either at the inferior pole of the patella or in the belly of the tendon. Predisposing factors for patella tendinopathy include hamstring and quadriceps tightness, increased neural tension and abnormal biomechanics of the pelvis, PFJ of lower leg. Calf weakness is also a common finding in these patients. Pain and disuse due to the patella tendinopathy may lead to VMO (medial quadriceps) weakness and incorrect biomechanics of the PFJ. Role of physiotherapy

Because this is a chronic condition (has developed over time and has been present for months) it will take a while to heal. The patient and physiotherapist needs to be patient through the rehabilitation programme.

Physiotherapy rehabilitation will include: • Relative load reduction : o activity modification o Correction of biomechanics • Cold therapy (ice) • Targeted muscle strengthening: o Including concentric, isometric and eccentric strengthening o graduated training for strength and strength endurance, power and speed endurance, combinations of the above as appropriate to the sport • Soft tissue treatment – of the quadriceps muscle, calf muscles and patellar tendon itself • Pharmacology – research has shown that corticosteroid(2) and sclerosing(3) injections have been found to reduce pain and improve function in patients with patellar tendinopathy

Iliotibial Band Friction Syndrome

It's a superficial thickening of tissue on the outside of the thigh, extending from the outside of the pelvis, over the hip and knee, and inserting just below the knee. The band is crucial to stabilizing the knee during running, moving from behind the femur to the front while walking. The continual rubbing of the band over the lateral femoral epicondyle, combined with the repeated flexion and extension of the knee during running may cause the area to become inflamed.

(2) Pellechia G, Hamel H, Behnke P. Treatment of infrapatellar tendinitis: a combination of modalities and transverse friction massage versus iontophoresis. J Sport Rehabil 1994 ; 3: 1315-45 (3)Hoksrud A, Ohberg L, Alfredson H, Bahr R. Ultrasound-guided sclerosis of neovessels in painful chronic patellar tendinopathy – a randomized controlled trial. Am J Sports Med 2006; in press