Sprains, strains and bruises: what the words mean

"Sprain" and "strain" are used almost interchangeably in everyday speech, but they describe injuries to different tissues. This page explains the difference, along with the related words people hear after a knock or a twist: bruise, tendinitis and bursitis.

Sprains: ligament injuries

MedlinePlus, in its overview of sprains and strains, defines a sprain as a stretched or torn ligament, and ligaments as the tissues that connect bones at a joint. Falling, twisting or getting hit can all cause a sprain. The American Academy of Orthopaedic Surgeons, in its OrthoInfo page on sprains, strains and other soft-tissue injuries, names the ankles, knees and wrists as the areas most vulnerable to sprains, and gives typical examples: the foot rolling inward and stretching the ligaments on the outside of the ankle, a sudden twist of the knee, or a fall onto an outstretched hand.

MedlinePlus lists pain, swelling, bruising and difficulty moving the joint as common symptoms, and notes that some people feel a pop or tear when the injury happens. OrthoInfo explains that sprains are graded by severity, from slight stretching of the ligament fibres, through partial tearing that leaves the joint abnormally loose, to a complete tear that can make the joint unstable.

Strains: muscle and tendon injuries

A strain, in MedlinePlus's words, is a stretched or torn muscle or tendon, tendons being the tissues that connect muscle to bone. Twisting or pulling these tissues can cause a strain, and strains can happen suddenly or develop over time. MedlinePlus notes that back and hamstring strains are common, and that many people get strains playing sports. Symptoms it lists include pain, muscle spasms, swelling and trouble moving the muscle. OrthoInfo adds that strains often occur in the back, the neck or the leg, and that like sprains they range from a simple stretch to a partial or complete tear.

A strained lower back after lifting, a pulled hamstring when sprinting, and a sore calf after a first run of the season are all strains in this sense.

A quick way to remember the difference

A sprain affects a ligament, which joins bone to bone across a joint; a strain affects a muscle or tendon, which moves the joint. One way to keep them apart is that the "t" in strain can stand for tendon. In practice the two often happen together, and the first care described for both is much the same.

Bruises, tendinitis and bursitis

• Contusion is the medical word for a bruise. OrthoInfo describes it as an injury from a direct blow, or repeated blows, that crushes the underlying muscle fibres and connective tissue without breaking the skin; the discoloration comes from blood pooling around the injury.
• Tendinitis is inflammation or irritation of a tendon. OrthoInfo explains that it is caused by a series of small stresses that repeatedly aggravate the tendon, which makes it an overuse injury rather than a sudden one.
• Bursitis is inflammation of a bursa, a small fluid-filled sac that cushions moving parts near a joint. OrthoInfo notes that repeated small stresses and overuse can cause a bursa to swell, and that bursitis often occurs alongside tendinitis.

How first care is usually described

MedlinePlus explains that, at first, care for both sprains and strains usually involves resting the injured area, icing it, wearing a bandage or device that compresses it, and medicines, and that later care might include exercise and physical therapy. OrthoInfo describes the same first steps under the name RICE: rest from the activity that caused the injury, ice applied in short spells rather than continuously and never directly on the skin, an elastic compression bandage, and raising the injured part while resting. Which medicines, if any, are suitable is a question for a pharmacist or health care provider.

These are descriptions of what is commonly done, not a treatment plan. The right care depends on which tissue is injured, how badly, and where, and some injuries that feel like a sprain turn out to be fractures.

Signs that it may be more than a sprain

An injury is worth having checked if you cannot put weight on the leg or use the arm, if the joint looks misshapen, feels unstable or gives way, if there is numbness, or if the pain and swelling are severe or are not settling. OrthoInfo notes that the most severe sprains may need surgery to repair a torn ligament, so an early assessment matters when an injury seems significant.

For how these tissues repair themselves over time, see how muscles, tendons and ligaments recover after an injury.