Post-Traumatic Nerve Injuries after Ankle or Lower Leg Fractures

Injuries to the ankle or lower leg can affect not only bones, ligaments, and muscles – nerves can also be at risk.
If damaged, nerves may cause pain, numbness, or muscle weakness.
A targeted diagnosis is essential to clarify the cause and determine the most appropriate treatment.

Anatomical basics – which nerves can be affected?

Several important nerves run through the ankle and lower leg, controlling both movement and sensation in the foot and lower leg. Commonly affected nerves include:

Common peroneal nerve – runs around the fibular head and branches into the
Deep peroneal nerve (foot dorsiflexion muscles) and the superficial peroneal nerve.
Superficial peroneal nerve – runs down the front of the lower leg and supplies the dorsum of the foot and parts of the toes.
In some people,
- it branches into the dorsal cutaneous nerves already in the mid-lower leg, increasing injury risk with atypical courses.
Tibial nerve – runs behind the medial ankle bone and supplies the sole of the foot (tarsal tunnel area).
Saphenous nerve – branch of the femoral nerve, runs along the inner side of the lower leg to the foot.
Infrapatellar branch – branch of the saphenous nerve, supplies the area below the kneecap and can also be affected in proximal injuries or knee surgery.
Sural nerve – formed by the medial and lateral sural cutaneous nerves, runs down the back of the lower leg to the outer edge of the foot.

Possible symptoms of nerve injuries

Numbness or tingling in the foot or lower leg
Burning or stabbing pain
Muscle weakness, e.g., foot drop (foot falls downward while walking)
Unsteady gait or frequent tripping
Skin hypersensitivity to touch

Cartoon-style illustration of a post-traumatic nerve injuries at the ankle showing typical symptoms. — Depiction of a post-traumatic nerve injury at the ankle with typical symptoms affecting bones, ligaments, and nerves.

Causes – how nerve damage can occur

Direct nerve injury in fractures
Pressure from swelling, hematomas, or casts
Scar formation after surgery
Compression in anatomical narrow passages (e.g., tarsal tunnel)
Associated injuries in dislocations or complex fractures

Diagnosis

A thorough evaluation is essential to determine the cause and extent of the nerve injury.

1. Clinical examination

Assessment of strength, mobility, reflexes, and skin sensation in the affected areas.
This can often help identify which nerve is involved.

2. High-resolution nerve ultrasound

Real-time visualization of nerves
Detection of swelling, bleeding, scar tissue, or displacement
Very high spatial resolution, especially for cutaneous nerves
Sonopalpation: combining ultrasound imaging with gentle pressure using the probe to locate painful spots precisely

Illustration of a high-resolution ultrasound probe for visualizing peripheral nerves. — High-resolution probes can help visualize fine nerve structures in detail.

3. Muscle ultrasound

Evaluation of muscle structure for changes such as shrinkage (atrophy) or altered texture, as these can result from reduced nerve supply and may indicate nerve damage.

Muscle ultrasound: Ultrasound examination of muscles to diagnose scarring, fatty degeneration, atrophy, and muscle wasting. — Muscle ultrasound can help identify changes such as bleeding, scarring, atrophy, and fatty degeneration in muscles. It can also support follow-up examinations and assessment over time.

4. Magnetic resonance imaging (MRI)

Visualization of deeper nerve segments and surrounding structures such as muscles, vessels, or bone changes.

5. Neurophysiological studies (NCS/EMG)

Nerve conduction studies (NCS): measure the speed at which electrical signals travel along the nerve. Limitations exist for small cutaneous nerves due to their variable course, small size, and post-injury swelling.
Electromyography (EMG): measures the electrical activity of muscles.
Combined with muscle ultrasound, the most suitable muscle areas for needle testing can be selected.
The pattern of muscle changes can give indirect clues about the affected nerve segment and help optimize EMG planning.

llustration of the electrodes used for nerve conduction studies (neurography / NCS / ENG). — Nerve conduction studies (neurography) are performed using a stimulation electrode and adhesive skin electrodes.

Close-up of the tip of a concentric needle electrode with inner and outer recording surfaces. — The tip of the concentric needle electrode contains an inner and an outer electrode that record electrical activity of individual muscle fibers within a few millimeters.

Differential diagnoses – other possible causes

Lumbar disc herniation
Diabetic polyneuropathy
Peripheral arterial disease (PAD)
Nerve entrapment at other sites (e.g., fibular head, tarsal tunnel)
Scar tethering or adhesions from older injuries

Treatment

Management depends on the cause, severity of the injury, and individual circumstances – a specialist evaluation is essential.

Possible treatment approaches:

Reducing swelling or treating hematomas
Physiotherapy and occupational therapy
Bracing and orthotic support
Pain management
Ultrasound-guided nerve infiltrations – targeted injection of medication near the nerve or into surrounding tissue for temporary pain relief or diagnostic purposes
Surgical options in specialized centers (e.g., nerve decompression, reconstruction, or nerve grafting)
Regular follow-up examinations

Prognosis

Recovery can vary greatly and depends on the severity, cause, and timing of treatment.
Some patients experience significant improvement, while others may have lasting symptoms.
A reliable prognosis can only be made after specialist assessment and follow-up.

Disclaimer: The information provided on this page is for general informational purposes only and does not constitute medical advice. It is not a substitute for personal consultation, examination, or treatment by a physician or other qualified healthcare professional. No guarantees of healing or cure are made. While we strive for accuracy and completeness, we cannot guarantee that all content is up to date or free from errors, and we accept no liability for any inaccuracies.