Knee & Lower Leg

An ACL injury involves a tear of the anterior cruciate ligament—a key stabiliser running between the femur and the tibia—typically sustained during sudden deceleration, pivoting or direct impact in sport. The ligament’s disruption compromises anterior–posterior stability of the lower leg.

You may hear or feel a “pop” at the time of injury, followed by rapid swelling within hours and a sensation that the knee “gives way” under weight. Difficulty bearing weight, marked joint effusion and a positive Lachman or anterior drawer test help confirm the diagnosis.

The PCL, which prevents the tibia sliding backwards under the femur, is injured most often by a direct blow to a flexed knee (for example in a fall onto the shin). PCL tears range from partial stretches to complete ruptures, affecting the knee’s posterior stability.

You’ll often experience pain at the back of the knee, swelling that may be slower to develop than with an ACL tear, and a feeling of instability when descending steps. On examination, the tibia may sag backwards on the femur (posterior sag sign), and a posterior drawer test reproduces the instability.

Collateral ligament sprains affect the medial (MCL) or lateral (LCL) ligaments on either side of the knee, usually from a direct blow that forces the joint sideways in sport or a fall. They provide important resistance to valgus/inwards (MCL) and varus/outwards (LCL) stresses

Signs include focal pain and tenderness along the inner or outer knee margin, swelling local to the injured ligament and a sense of looseness when applying a valgus or varus stress at 30° of flexion. Mild sprains may permit weight-bearing, whereas more severe tears cause marked instability.

A meniscal tear involves damage to the crescent-shaped cartilage between femur and tibia, often from twisting on a planted foot or degenerative wear. Medial and lateral menisci cushion and stabilise the joint, but once torn they can catch or block movement.

You’ll feel an immediate or gradual onset of deep knee pain, often localised to the joint line. Swelling may develop over 24 hours, and locking, catching or giving way are common. Pain is reproduced by twisting the knee in weight-bearing, and joint-line tenderness on palpation aids the diagnosis.

Patellofemoral maltracking occurs when the kneecap fails to glide smoothly in the femoral groove, sometimes leading to cartilage softening (chondromalacia) beneath the patella. Muscle imbalance, overuse or anatomical variations are normally the cause of the abnormal tracking.

Presentation includes anterior knee pain—particularly when squatting, kneeling, rising from a seat or descending stairs—often accompanied by grinding, clicking or a feeling of instability under the patella. Tenderness on pressing the kneecap and a positive patellar grind test are key findings.

Jumper’s knee is inflammation of the patella tendon at its insertion on the tibial tuberosity, caused by repetitive impact activities such as jumping or sprinting. The tendon fibres develop microtears and thickening, leading to pain with load.

You’ll feel a sharp or aching pain at the base of the kneecap during activities that load the tendon—jumping, running or deep squats—and tenderness when pressing directly over the tendon insertion. Pain may flare when rising from sitting or climbing stairs.

Injury to the superior tibiofibular joint—where the fibula meets the tibia just below and to the outside aspect of the knee—can result from twisting movements or direct blows, occasionally affecting the nearby common peroneal nerve. This joint assists in load transfer and ankle stability.

You’ll notice pain and tenderness to the outer side of the knee, especially on weight-bearing, walking or ankle movement. In severe cases, tingling, numbness or weakness in the lower leg and foot suggests and associated peroneal nerve involvement.

Osgood-Schlatter’s is inflammation of the growing tibial tuberosity in adolescents, where the patella tendon attaches. Repetitive running and jumping overload the soft, developing bone, leading to micro-avulsions and pain.

This is normally seen in sporty teenagers who report localised swelling and tenderness over the shin just below the knee, aggravated by kneeling, squatting and straightening the leg against resistance. The bony prominence may become enlarged and sore on palpation.

Compartment syndrome arises when pressure from muscle inflammation within one of the leg’s three muscular compartments (anterior, lateral or posterior) builds during prolonged exercise, impeding blood flow and nerve function. Without relief, it can cause muscle and nerve damage.

In chronic exertional compartment syndrome, you might experience tightness, cramping pain and sometimes numbness in the shin during activity—typically running—that eases on rest. Acute compartment syndrome, by contrast, presents with severe pain disproportionate to injury, tense swelling and may require emergency treatment.

Peripheral neuropathy of the lower leg results from damage to the peripheral nerves—commonly due to diabetes, vitamin deficiencies or toxins—and leads to sensory changes and discomfort. It affects the nerves serving the foot and lower leg compartments.

You’ll notice burning, tingling, numbness or sharp shooting pains in a stocking-and-glove distribution starting in the feet and lower calves. Symptoms often worsen at night and may be accompanied by muscle weakness or loss of reflexes, signalling the need for medical evaluation.