Peroneus Longus

Clinical Notes

• Peroneal tendinopathy presents as pain posterior or inferior to the lateral malleolus, worsened by eversion against resistance and walking on uneven surfaces. Often develops after recurrent lateral ankle sprains because the peroneals compensate for deficient lateral ligament stability.
• Peroneal tendon subluxation — the superior peroneal retinaculum tears (usually from an ankle inversion injury), allowing the tendons to snap over the lateral malleolus. The client describes a "clicking" or "snapping" behind the lateral ankle during eversion.
• Relevant to foot arch disorders — peroneus longus supports the transverse arch via its plantar crossing. Weakness allows the first ray to dorsiflex and the transverse arch to collapse, altering forefoot mechanics.
• The common peroneal nerve wraps around the fibular head at the origin of peroneus longus. Direct trauma to the fibular head or prolonged compression (leg crossing, tight cast, prolonged lateral knee pressure) produces common peroneal nerve palsy with foot drop and lateral leg sensory loss.

• In clients with recurrent ankle sprains, the peroneals are often hypertonic from chronic overwork — they compensate for ligamentous instability by providing dynamic lateral ankle stability. The lateral leg feels tight and tender along the full peroneal bulk.
• In runners on cambered roads (always running with one foot lower), the uphill peroneals are overloaded. Ask about running surface — this is a common missed cause of lateral leg pain.
• Peroneal tendon tenderness behind the lateral malleolus with crepitus suggests tendinopathy. Tenderness without crepitus may be TrP referral from the proximal belly.

• The muscle belly responds to longitudinal stripping along the lateral fibular surface. Work from the fibular head distally, using the bone as a backstop.
• Cross-fiber friction on the tendons behind the lateral malleolus is effective for peroneal tendinopathy. Position the foot in slight inversion to tension the tendons for optimal access.
• Proximal treatment must respect the common peroneal nerve at the fibular head — use sustained moderate compression rather than aggressive cross-fiber work directly over the nerve.

• The common peroneal nerve is the most frequently injured nerve in the lower extremity, largely because it is superficial at the fibular head. Avoid sustained heavy pressure directly over the fibular head. If the client reports tingling or numbness on the lateral leg or dorsal foot during treatment, you are compressing the nerve — immediately reduce pressure.
• The superficial peroneal nerve pierces the deep fascia in the distal lateral leg. Deep pressure in the distal third of the lateral compartment can compress this nerve, producing dorsal foot numbness.

• After a lateral ankle sprain, the peroneals must be rehabilitated as the primary dynamic stabilizers of the ankle. If a client has recurrent sprains, check peroneal strength (resisted eversion) — weakness indicates the muscle has not been rehabilitated and the ankle will keep spraining. Releasing the muscle alone without strengthening is counterproductive in this context.