The pain felt on the outside of the ankle and lower leg often relates to the peroneus brevis muscle or its tendon. This muscle is a common source of discomfort, especially for those who are physically active or have recently strained their ankle. The peroneus brevis is a significant stabilizer of the ankle, making it vulnerable to injury from repetitive stress or sudden, forceful movements.
Locating the Peroneus Brevis Muscle
The peroneus brevis is one of two muscles situated in the lateral compartment of the lower leg, lying underneath the larger peroneus longus muscle. It originates from the lower two-thirds of the outer surface of the fibula. The muscle then transitions into a tendon that travels down toward the ankle.
This tendon passes behind the bony prominence on the outside of your ankle, known as the lateral malleolus. It then continues along the side of the foot to insert at the tuberosity, a small bump found on the base of the fifth metatarsal bone. This insertion point is located on the outer edge of your foot, close to the pinky toe.
The primary function of the peroneus brevis is to evert the foot, which means turning the sole of the foot outward. It also assists in plantarflexion, the motion of pointing your foot downward. These actions are fundamental for balance and stability, especially when walking or running on uneven ground, as the muscle actively works to protect the ankle from rolling inward.
Common Conditions Causing Pain
Pain originating from this muscle is most often due to issues with its tendon, categorized as chronic overuse, acute trauma, or mechanical instability. The most frequent cause is peroneal tendinopathy, often called tendinitis. This overuse injury occurs when repetitive stress, common in runners, causes micro-trauma faster than the body can repair it. Tendinopathy pain usually has a gradual onset, worsens with activity, and eases with rest.
A more severe, acute cause of pain is a tear in the peroneus brevis tendon, which can be partial or complete. Tears often occur suddenly, frequently following a traumatic ankle sprain where the foot rolls inward forcefully. Symptoms include sharp, immediate pain, swelling, and a feeling of instability or weakness. In chronic cases, the tendon may fray or degenerate over time due to long-term overuse, sometimes called tendonosis.
Peroneal subluxation is a third distinct issue, occurring when the tendon slips out of its normal groove behind the lateral malleolus. This condition usually results from a forceful twisting injury that damages the superior peroneal retinaculum, the fibrous band holding the tendons in place. Patients often report a distinct snapping, clicking, or popping sensation and may feel the tendon visibly moving over the bone. Subluxation causes sharp pain and instability, and if left untreated, the friction can lead to a longitudinal tear in the tendon.
Managing Pain and Knowing When to Seek Help
For mild pain, initial self-care focuses on reducing inflammation and preventing further irritation. The modified R.I.C.E. protocol is a common starting point, involving resting the foot by avoiding painful activities. Applying ice to the outer ankle for 15 to 20 minutes helps reduce swelling and pain.
Compression using a bandage or elastic wrap, along with elevating the foot above the level of the heart, can further assist in managing swelling. Over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, may also be used to alleviate pain and reduce localized inflammation. Once acute pain subsides, gentle, pain-free stretching and strengthening exercises, often guided by a professional, can help restore function and prevent recurrence.
It is important to know when to consult a healthcare provider for a professional diagnosis and treatment plan. Seek medical attention if the pain is severe enough to prevent weight-bearing or if it is accompanied by severe swelling. Hearing a sudden popping or snapping sound at the time of injury is also a red flag, as this may indicate an acute tendon tear or subluxation.
If symptoms persist or worsen after five to seven days of consistent rest and home treatment, a medical evaluation is warranted. A professional may recommend physical therapy to strengthen the muscles and improve ankle stability, or prescribe immobilization with a brace or boot. For severe tears or chronic subluxation that do not respond to conservative methods, surgical intervention may be necessary to repair the tendon or stabilize its position.