Foot drop is not
always permanent —
if the nerve is decompressed in time.

The distinction is critical and is made through a combination of clinical examination, imaging, and electrodiagnostic testing (EMG/NCS). Foot drop from L4-L5 disc herniation or lumbar spinal stenosis involves the L5 nerve root — the weakness pattern, sensory distribution, and reflexes differ from peroneal neuropathy. Nerve conduction studies of the peroneal nerve and needle EMG of the muscles it innervates (tibialis anterior, extensor hallucis longus, peroneus longus) will show abnormal conduction and denervation changes localized to the fibular head if the problem is peroneal rather than spinal. Many patients with foot drop have already had lumbar spine imaging and been told the spine is the cause — in a meaningful number of cases, the actual source is peroneal entrapment at the knee, and decompression at the right level produces recovery that spine surgery would not.

Duration is one of the most important factors in predicting surgical outcome. Foot drop from peroneal compression that has been present for less than 6 months with incomplete weakness has an excellent prognosis after decompression — most patients recover meaningful dorsiflexion. At 6 to 18 months with complete foot drop, recovery is possible but less predictable and typically slower. Beyond 18–24 months of complete foot drop with EMG evidence of severe denervation and loss of motor units, the window for meaningful motor recovery is substantially narrowed. This is not a rule with sharp edges — individual factors matter — but it is the reason that early evaluation and surgical decision-making is strongly preferable to prolonged bracing and observation when peroneal compression is the cause.

Most patients go home the same day. The incision is small — 2 to 3 cm at the lateral knee — and wound recovery is straightforward. Walking is possible immediately. The more meaningful recovery question is when the nerve function returns. In patients with mild to moderate compression and intact axons, early signs of returning dorsiflexion may appear within days to weeks. In patients with significant axonal injury requiring nerve regeneration, recovery is measured in months — peripheral axons regenerate at approximately 1 mm per day from the injury site toward the muscle. Physical therapy is often valuable during recovery to maintain ankle mobility and retrain the recovering musculature as nerve function returns.

Post-TKA peroneal palsy is a recognized indication for peroneal nerve decompression when it does not spontaneously resolve. After total knee replacement, the peroneal nerve may be injured by stretch from deformity correction, direct compression from the cast or brace, or positional pressure during surgery. If foot drop persists beyond 6–8 weeks without meaningful improvement, EMG/NCS should be performed to assess nerve continuity and the degree of axonal injury. When the nerve is anatomically intact but compressed or in continuity (nerve-in-continuity injury), decompression at the fibular head can free the nerve from any residual entrapment and provides the best environment for recovery. Earlier intervention tends to produce better outcomes in this group.

Bilateral peroneal neuropathy occurs less commonly than unilateral but does happen — typically in the setting of significant weight loss, prolonged bilateral positional compression, or systemic neuropathy affecting vulnerable nerve segments. Each side is evaluated independently with EMG/NCS to confirm peroneal entrapment bilaterally and to assess the degree of injury on each side. Both sides can be decompressed, though typically staged to allow normal gait with one leg during recovery of the other. The more symptomatic or more recently injured side is usually addressed first.

In the early post-operative period, yes — the brace provides safety while the nerve recovers and dorsiflexion strength returns. As motor function improves, the brace is progressively weaned under physical therapy guidance. In patients with full recovery of dorsiflexion, the brace is ultimately discarded. In patients with partial recovery, the brace may continue to be needed for demanding activities or uneven terrain even after meaningful improvement. The goal of surgery is not simply to justify stopping the brace — it is to restore as much native function as the nerve can regenerate. For many patients, especially those treated early, that means no brace at all.