Drop Foot (Foot Drop)

Drop foot (foot drop) is difficulty lifting the front of the foot, so the toes drag or catch on the ground when walking. It is a sign of an underlying nerve or muscle problem, not a disease in its own right. It can be temporary or permanent, depending on the cause. Treatment ranges from a brace to surgery.

The muscles at the front of the shin lift the foot and toes with each step. They are controlled by the peroneal nerve, which wraps around the outer side of the knee just below the skin. Damage anywhere along this pathway can cause drop foot, from the brain and spine down to the nerve at the knee or the muscles themselves. The NHS notes that drop foot usually affects one foot and can sometimes get better on its own.

What are the symptoms?

• Difficulty lifting the toes or the front of the foot
• The foot dragging or catching on the ground when walking
• A high-stepping or swinging walk (steppage gait) to clear the toes
• The foot hanging limp when the leg is lifted
• Numbness or tingling in the shin, foot or toes
• Tripping or falling more often

What causes drop foot?

• Peroneal nerve compression or injury: the most common cause. This can follow a knee fracture or surgery, or prolonged pressure on the nerve, such as from habitual leg crossing, kneeling or squatting
• A trapped nerve in the lower back: from a slipped disc or spinal stenosis
• Neurological conditions: such as multiple sclerosis, stroke or muscular dystrophy
• Peripheral neuropathy: for example, from diabetes
• Complications after hip or knee replacement

The NHS lists rarer causes, including Charcot-Marie-Tooth disease, motor neurone disease, cerebral palsy and Parkinson's disease. Finding the cause is the most important step, because it determines whether the weakness is likely to recover.

Non-surgical treatment

• Ankle-foot orthosis (AFO): a lightweight brace that holds the foot at a right angle for a more natural walk
• Physiotherapy: exercises to strengthen the working muscles, keep the ankle supple and improve walking
• Functional electrical stimulation (FES): small electrical impulses stimulate the peroneal nerve at the right moment during walking, lifting the foot
• Treating the underlying cause: for example, spinal surgery for a trapped nerve or better diabetes control

NICE guidance supports FES for drop foot caused by conditions of the brain or spinal cord, such as stroke or multiple sclerosis. It finds the evidence on safety and on improving walking adequate. The NHS also advises simple steps to reduce the risk of falls, such as keeping floors clear and rooms well lit.

When is surgery recommended?

Surgery may be considered when drop foot does not improve with non-surgical treatment, or when there is a correctable anatomical cause. Mr Hester will discuss the specific surgical plan based on the cause and extent of the drop foot. The options include:

• Nerve decompression: releasing a nerve that is being squeezed
• Nerve repair: for a nerve that has been cut or badly damaged
• Tendon transfer: rerouting a working tendon to lift the foot

When the nerve is unlikely to recover, a tendon transfer is a common option. The usual technique moves the tibialis posterior tendon from the inner side of the foot, passes it through the membrane between the shin bones, and fixes it to the top of the foot so that it can lift it. If the ankle is also tight, the Achilles tendon may need lengthening. A systematic review of tendon transfer for foot drop (Stevoska and colleagues) supports this approach as an established surgical option.

A systematic review of 37 studies in Archives of Orthopaedic and Trauma Surgery (Stevoska and colleagues) found that tibialis posterior transfer through this membrane was the most frequently reported technique. Function scores improved and fewer people needed a brace afterwards. The exact surgical technique did not appear to affect the result. The NHS adds that fusing joints in the foot or ankle is an option in some cases where the loss is permanent.

What is recovery like?

The transferred muscle has to learn a new job, so physiotherapy and gait retraining are an essential part of recovery.

How Mr Hester can help

Mr Hester is a dual fellowship-trained foot and ankle surgeon (FRCS Tr&Orth), trained at Guy's and St Thomas' and in Toronto and Calgary, and a member of BOFAS and EFAS. He sees patients privately at The London Clinic, Cromwell Hospital, King Edward VII's Hospital and HCA The Shard. His NHS practice is at King's College Hospital.

Insured patients need a GP referral and an authorisation code from their insurer. Self-pay patients are welcome. To book, call 020 7046 8004.

Frequently Asked Questions

Sources

1. Foot drop. NHS. https://www.nhs.uk/conditions/foot-drop/
2. Functional electrical stimulation for drop foot of central neurological origin. NICE. https://www.nice.org.uk/guidance/htg178
3. Stevoska S, Pisecky L, Stadler C, Gahleitner M, Klasan A, Klotz MC. Tendon transfer in foot drop: a systematic review. Arch Orthop Trauma Surg. 2022;142(3):415–425. PMID: 34524486. https://pubmed.ncbi.nlm.nih.gov/34524486/