The peroneus brevis tendon is an important structure located in the ankle and foot. Injuries to this tendon can be a significant source of ankle discomfort and functional limitation. A longitudinal split tear of the peroneus brevis tendon is a condition that can lead to persistent pain. Understanding this injury is helpful for individuals experiencing outer ankle pain.
Understanding the Peroneus Brevis Tendon
The peroneus brevis tendon is one of two peroneal tendons situated on the outer side of the lower leg, behind the fibula. This tendon originates from the lower portion of the fibula and extends downwards, wrapping around the lateral malleolus, a bony prominence. It then inserts into the base of the fifth metatarsal bone on the outer side of the midfoot.
The primary function of the peroneus brevis tendon involves assisting with two key movements of the foot: eversion and plantarflexion. Eversion refers to turning the sole of the foot outwards. Plantarflexion is the movement of pointing the foot downwards. This tendon works in coordination with the peroneus longus tendon to stabilize the ankle and foot during activity.
The peroneus brevis tendon passes through a groove behind the lateral malleolus, sharing a common sheath with the peroneus longus tendon. This anatomical arrangement positions the brevis tendon closer to the bone. This close proximity and confined space can make it susceptible to friction and compression, especially during repetitive ankle movements.
What a Longitudinal Split Tear Is
A longitudinal split tear of the peroneus brevis tendon is an injury where the tendon fibers separate along their length. Unlike a complete rupture, where the tendon breaks entirely, a longitudinal tear involves a split or fraying that runs parallel to the tendon fibers, splitting into two or more strands.
These tears can vary in extent and depth, ranging from partial-thickness (only some fibers affected) to full-thickness (split extends through the entire tendon). This type of tear often occurs due to repetitive stress or degenerative changes within the tendon.
The unique anatomy of the peroneus brevis tendon, particularly its position within the peroneal groove, makes it prone to this injury. As the tendon moves within this confined space, it can rub against the bone or the adjacent peroneus longus tendon. This constant friction, especially if the groove is shallow or if there is excessive ankle motion, can contribute to the gradual development of longitudinal tears.
Common Causes and Symptoms
Longitudinal split tears often result from repetitive stress and acute incidents. Recurrent ankle inversion, where the ankle twists inwards, is common in activities requiring sudden changes in direction. Chronic ankle instability from previous sprains can also predispose individuals to these tears. Overuse from activities involving repetitive ankle motion, such as long-distance running, can contribute to gradual development. Direct trauma, like a severe ankle sprain, can also cause an immediate split tear.
Individuals with a longitudinal split tear typically report specific symptoms. Pain along the outside of the ankle is a primary complaint, often worsened by physical activity, especially movements involving eversion or pointing the foot downwards. This pain may feel sharp or aching and worsen with activity. Swelling and tenderness are common along the tendon’s path, particularly behind the lateral malleolus. Some individuals may also describe ankle instability or weakness when moving the foot outwards.
Diagnosis and Treatment Options
Diagnosing a longitudinal split tear typically involves a physical examination and imaging studies. During examination, a healthcare provider will palpate the outer ankle, looking for tenderness, particularly behind the lateral malleolus. They will assess the ankle’s range of motion and stability, and may perform tests like resisted eversion to evaluate peroneal tendon integrity. X-rays can rule out fractures but do not visualize soft tissues like tendons.
Magnetic Resonance Imaging (MRI) is the most effective imaging for confirming a longitudinal split tear. MRI scans provide detailed images of soft tissues, assessing the tear’s location, length, and depth. Ultrasound imaging can also visualize the tendon as the ankle moves for real-time assessment.
Treatment for longitudinal split tears varies based on severity and patient activity, often beginning with non-surgical approaches. Initial conservative management includes rest, ice, compression, and elevation (RICE protocol). Immobilization using a walking boot or ankle brace may be prescribed to protect the tendon and allow healing.
Physical therapy plays a role, focusing on exercises to reduce swelling, restore range of motion, strengthen the peroneal muscles, and improve ankle stability. Nonsteroidal anti-inflammatory drugs (NSAIDs) may manage pain and inflammation. If conservative treatments do not resolve symptoms, surgical intervention may be considered. Surgical options involve debridement (removing damaged tissue) or repair of the split tendon.
Recovery Expectations
The recovery process for a longitudinal split tear varies. For non-surgical treatment, initial healing may take several weeks, with a gradual return to activities over 6 to 12 weeks. The primary focus is on reducing pain and inflammation, followed by restoring strength and flexibility through a physical therapy program.
Following surgical repair, the recovery timeline is generally longer, involving an initial period of immobilization (4 to 6 weeks) to allow the tendon to heal. A progressive rehabilitation program then focuses on regaining range of motion, strengthening the ankle muscles, and improving balance and proprioception. Full recovery and return to athletic activities can take 4 to 6 months or longer, depending on individual progress.
Adherence to the prescribed physical therapy protocol is important for a successful outcome, preventing re-injury and optimizing functional recovery. While many individuals achieve good results, some may experience persistent pain or ankle instability. Commitment to rehabilitation is a factor in achieving the best long-term results.