Tendonitis is inflammation or irritation of a tendon, the thick cord that attaches muscle to bone. It typically results from repetitive stress or overuse, leading to pain, tenderness, and swelling near the affected tendon. Common sites include the Achilles tendon (Achilles tendonitis) and the tendons around the shoulder (rotator cuff tendinitis).

Stress fractures are small, hairline cracks in a bone caused by repetitive force or overuse, often seen in weight-bearing bones such as the tibia or metatarsals. Symptoms include localised pain, swelling, and tenderness, which usually worsen with activity and improve with rest.

Ligament tears occur when one or more of the ligaments—strong bands of connective tissue that stabilise joints—are stretched or torn. This type of injury can result from trauma, such as a sudden twist or impact. Symptoms include pain, swelling, bruising, and instability in the affected joint. Common examples include ACL tears in the knee and ankle sprains.

Muscle strains involve the overstretching or tearing of muscle fibres, often due to sudden movements or overuse. Symptoms include pain, muscle spasms, swelling, and difficulty moving the affected muscle. Muscle tears are more severe and involve a complete rupture of muscle fibres, leading to significant pain, loss of function, and sometimes visible bruising or a noticeable gap in the muscle. Strains and tears are common in muscles such as the hamstrings or quadriceps.

Runner’s knee, or patellofemoral pain syndrome, is a condition characterised by pain around or behind the kneecap (patella). It often results from overuse, misalignment, or poor tracking of the patella as it moves over the femur. Symptoms include aching or sharp pain in the front of the knee, which can be aggravated by activities like running, climbing stairs, or sitting for long periods.

Hamstring injuries involve strains or tears in the hamstring muscles, which are located at the back of the thigh. These injuries often occur during activities involving sprinting, jumping, or sudden acceleration. Symptoms include pain, swelling, and bruising in the back of the thigh, along with difficulty walking or bending the knee. Severity can range from mild strains to complete tears of the muscle or its tendinous attachments.