Musculoskeletal ultrasound provides real-time images of muscles, tendons, ligaments, joints, nerves, and other soft tissues.
It can be used to investigate pain and injuries affecting the feet, ankles, knees, and lower limbs. However, ultrasound is not suitable for every condition, and an X-ray, MRI, or CT scan may sometimes provide more useful information.
What Is Musculoskeletal Ultrasound Used For?
Ultrasound is particularly useful for examining soft tissues located relatively close to the surface of the body.
It also allows the clinician to view structures while they are moving. You may therefore be asked to bend your knee, move your ankle, or contract a muscle during the scan. This can help identify problems that may not be as obvious when the area is at rest.
Musculoskeletal ultrasound may be used to assess the following structures.
Tendons
Ultrasound can show tendon thickening, degeneration, inflammation, and partial or complete tears.
It may be used to investigate conditions affecting tendons around the feet, ankles, knees, and lower legs, including:
- Achilles tendinopathy
- Patellar tendon problems
- Quadriceps tendon injuries
- Tendon tears around the ankle
- Inflammation around a tendon
The ability to scan a tendon during movement can also help identify abnormal movement or irritation.
Ligaments
Ligaments connect bones and help stabilise joints. Ultrasound may identify sprains, thickening, tears, and other damage affecting accessible ligaments. It can be particularly helpful when investigating persistent pain or instability following an ankle or knee injury.
Some deeper ligaments within joints cannot be seen clearly and may require MRI imaging instead.
Muscles
Musculoskeletal ultrasound can help assess muscle strains, tears, bruising, scar tissue, and fluid collections. It may also help determine the location and extent of an injury, particularly when symptoms continue after the initial strain.
Bursae
Bursae are small, fluid-filled sacs that reduce friction between muscles, tendons, bones, and joints.
Ultrasound can show whether a bursa has become enlarged or inflamed. This can help identify bursitis around areas such as the knee, ankle, or heel.
Joints
Ultrasound can assess accessible structures within and around a joint. It may reveal:
- Excess fluid within the joint
- Swelling around the joint
- Inflammation of the joint lining
- Changes associated with inflammatory arthritis
- Some degenerative changes
- Cysts or fluid-filled swellings
For example, ultrasound may help identify fluid within the knee joint or a Baker’s cyst behind the knee. However, ultrasound cannot provide a complete view of every structure inside a joint.
Nerves
Superficial nerves can be examined for swelling, thickening, irritation, or compression. Ultrasound may be helpful when investigating nerve-related conditions such as Morton’s neuroma, which can cause burning pain, tingling, or numbness in the forefoot.
Plantar Fascia
The plantar fascia is the strong band of tissue running along the sole of the foot. Ultrasound can assess its thickness and structure, making it useful when investigating plantar fasciitis and persistent heel pain.
What Can’t a Musculoskeletal Ultrasound Show?
Ultrasound has limitations. Sound waves cannot travel through bone, so ultrasound cannot clearly show what is happening inside a bone. It cannot reliably identify:
- Stress fractures within the bone
- Bone marrow changes
- Early avascular necrosis
- Other conditions affecting the internal structure of a bone
Ultrasound may show changes to the surface of a bone or surrounding tissues, but an X-ray, MRI, or CT scan is usually required to investigate the bone itself.
It can also be difficult to assess structures that are located deep within the body or hidden behind bone. This includes some structures deep inside joints and areas such as the spinal canal.
Very deep tissues may also be harder to assess clearly because the ultrasound signal becomes weaker as it travels further beneath the skin.
Can Ultrasound Detect a Stress Fracture?
Ultrasound may sometimes show swelling or changes in the tissues surrounding a suspected stress fracture. However, it cannot provide a clear image inside the bone and cannot reliably confirm or rule out a stress fracture. An X-ray or MRI may therefore be more appropriate.
Does an Abnormal Scan Always Explain the Pain?
Changes such as tendon thickening, small tears, or age-related degeneration can sometimes appear on a scan without causing symptoms. Equally, someone may experience significant pain even when imaging shows only minor changes.
Ultrasound findings should therefore be considered alongside:
- The location and type of pain
- How and when the symptoms began
- Previous injuries or medical conditions
- The activities that make the symptoms worse
- Findings from a physical and musculoskeletal assessment
The aim is not simply to find an abnormality. It is to determine whether the scan findings match the symptoms and help explain the problem.
Book Musculoskeletal Ultrasound in Cambridge
At Cutting Edge Podiatry, diagnostic ultrasound scans are performed by Neil Liffen, an Extended Scope Physiotherapist and Diagnostic Musculoskeletal Sonographer.
Neil is available for diagnostic MSK ultrasounds and injection therapy at our Cambridge clinic every second Friday between 8:30am and 12 noon. Appointments can be booked online here, or you can call 01223 633 038. We recommend booking early as appointments are filling up fast.
