Peroneal Tendon Injury

Peroneal Tendon Tears

Complete Foot Care Course
Las Vegas, NV
September 13-15th, 2007

Troy S. Watson, MD
Director, Foot and Ankle Institute
Desert Orthopaedic Center
Las Vegas, Nevada

 

ANATOMY
Injuries to the peroneal tendons are common but not always clinically significant.
They are often times misdiagnosed as a lateral ankle sprain because an isolated injury to
the peroneal tendons are rare. Injury can occur to either the peroneus longus or
brevis tendons and is typically classified as acute or chronic. The peroneal muscle splits
into two separate muscles, the peroneus longus and peroneus brevis.
The peroneus longus muscle originates on the lateral condyle of the tibia and the head and midlateral aspect of the fibula. The tendon runs along the plantar surface of the foot to insert on the plantar aspect of the base of the 1st metatarsal and the medial cuneiform. The peroneus brevis muscle originates on the mid and distal lateral fibula and inserts on the base of the 5th metatarsal (Figure 1). They may be separated by the peroneal tubercle, with the brevis superior to the tubercle and the peroneus longus inferior to the tubercle. The superior peroneal retinaculum (SPR) is the primary restraint to subluxation for both peroneal tendons. The longus tendon crosses on the plantar aspect of the brevis before insertion. The role of the peroneus brevis is primarily abduction and eversion of the foot and ankle while the peroneus longus is primarily plantarflexion of the first ray and eversion. These tendons also help to stabilize the subtalar motion in the ankle. In balancing the foot, these tendons play off the posterior tibialis muscle on the opposite side of the tibia. Maximal exertion occurs with side-to-side movement and jumping.
Peroneal longus and brevis injuries can be differentiated by their location. Peroneus longus injuries often are more distal and localize to the os peroneum region with peroneus brevis injuries occurring most often at the level of the distal fibula or around the peroneal tubercle.

 

 

ETIOLOGY
Although any tendon tear or disruption can cause problems, a complete rupture of the peroneal tendons may sometimes go undiagnosed. Acute injuries of the peroneal
tendons include tendonitis, a longitudinal tear or rupture, laceration, and dislocation or subluxation. Acute injuries typically have one of two mechanisms as the cause; either an inversion ankle injury, which is often seen associated with anterior talofibular ligaments (ATFL) and/or calcaneofibular ligament (CFL) tears, or secondly, a powerful contraction of the peroneal muscles with a forcefully dorsiflexed foot.
The importance of the peroneus muscles is most obvious after lateral ankle sprains. Trauma to the lateral ankle distorts the proprioceptive sense and stretches the connective tissues. The peroneus muscles are often stretched and injured from traction when the foot inverts. Ankle instability begins and continues until the lateral retinaculum heals, the peroneal muscles recover, and proprioception returns. If the retinaculum does not heal properly and cannot retain its tension to stabilize the peroneal tendons, symptoms of instability may not resolve without further intervention, usually requiring surgery.

 

Chronic injuries may be associated with ankle or subtalar instability, and most commonly are seen in the middle-aged patient. More commonly, patients will not recall an inciting traumatic event. It is believed that most peroneal split tears in this subgroup of patients stems from mechanical irritation or attrition within the fibular groove. The peroneus brevis tendon becomes injured due to its repetitive mechanical trauma at the tip of the fibula (Figure 2). It is rare to see associated problems with the peroneus longus in this region. Brodsky and Krause found that in 24 patients with longitudinal split tears of the peroneus brevis tendon all had a stretched out superior peroneal retinaculum. This can lead to subluxation, which is when the tendons slip out of their normal position in the fibular groove, leading to lateral ankle instability and painful snapping across the ankle. Continuous subluxation of the tendons will usually result in a tear or rupture; therefore, it is critical to treat this problem as early as possible. In the early stages, a patient may be noted by MRI to have peroneal tendinosis rather than a tear. In tendinosis, there is notable degeneration within the tendon, which weakens this structure. Eventually, longitudinal split tears are seen. Chronic injury results in the subtle, insidious onset of pain posterior to lateral malleolus that progressively worsens in terms of both function and the level of pain. Split tears are then graded on their severity and size (Figure 3).

 

 

HISTORY AND PHYSICAL EXAM
Because peroneal tendon injuries are sometimes misdiagnosed and may worsen without proper treatment, prompt evaluation by a foot and ankle surgeon is highly recommended. To diagnose a peroneal tendon injury, the surgeon will examine the foot
and look for pain, instability, swelling, and weakness on the outer side of the ankle. During initial inspection of the ankle, the amount and location of swelling is noted. Signs of bruising and any ankle or foot deformity may also be present. The hindfoot is often noted to be in varus (bottom of shoe is worn out on the outside or lateral aspect) in patients with peroneal tendon pathology. The position of the peroneal tendons, which may be visibly subluxed or dislocated, without manipulative testing, is also of value. Observation of the patient's gait for abnormal rotation, heel strike, or weight transfer should also be made. The test for peroneal tendon injury or instability is simple. The physician holds the patient’s foot with one hand, while the opposite hand gently palpates the peroneal tendons just posterior to the lateral malleolus. The physician then moves the foot into end-range inversion, and then asks the patient to evert against resistance. The other hand is monitoring the peroneal tendons, feeling for a palpable snap or translation.

 

While x-ray is always a first-line study for imaging and is useful for ruling out any bone fractures or avulsions, an MRI is needed to fully evaluate the extent of the soft tissue injury. There is a high correlation between peroneal tendon split tears seen on MRI and intraoperative confirmation of a tear.

 

As stated earlier, peroneal tendon injuries are most commonly a result of inversion ankle sprains. It is important to note, however, that other commonly seen problems associated with or without peroneal tendon injuries include calcaneofibular ligament injury, anterior talofibular ligament injury, ankle fracture, Achilles tendonitis, ankle impingement syndrome, subtalar joint instability, tarsal coalition and lumbosacral radiculopathy.

 

 

TREATMENT
Conservative Treatment
There are different treatment options to be considered with peroneal tendon injuries. Conservative treatment usually begins with an anti-inflammatory, modification in activity, ice message, custom orthotics (with the possible addition of a lateral heel wedge) and rest to help relieve pain and swelling and provide some short-term comfort. Immobilization with a cast or CAM walker boot can also play a role in decreasing the inflammatory process. Use of an ankle brace can also help to decrease symptoms by limiting inversion and eversion. If there is not a complete rupture of the peroneal tendons, then physical therapy can provide exercises to strengthen the muscles and improve range of motion and balance. Modalities including ultrasound therapy enhance tissue healing by increasing local circulation. While these measures are conservative and usually reserved for strains and sprains of the peroneal tendons, a more aggressive approach is commonly used when dealing with confirmed tears. Symptoms do not typically improve with conservative treatment for those patients presenting with peroneal tears. Brodsky and Krause noted that conservative treatment failed in 20 of 24 patients (83%) with an average of 8 months of conservative care. This has been confirmed in my experience as well.

 

 

Surgical Treatment
Surgical management is usually necessary for those patients with pathology that does not respond to the above noted conservative measures or in those who are noted by MRI with a peroneal tendon tear.

 

 

Tenosynovitis and Tendinosis
Tenosynovitis is an inflammatory process of the lining of the tendons. Each tendon has an associated sheath surrounding the tendon distal to the tip of the fibula. To treat this condition surgically, the surgeon opens the sheath and explores each tendon. A tenosynovectomy or debridement of the surrounding soft tissue inflammation is then undertaken. Any degenerative portion of the tendon(s) (tendinosis) is removed. The peroneus quartus (an accessory muscle belly sometimes seen in this area) can be excised. If a prominent peroneal tubercle is seen and felt to be contributing to the inflammatory process, it is removed. The tendon sheath is not repaired. If hindfoot varus is noted, a Dwyer calcaneal osteotomy is added to the procedure to correct the position of the foot and decrease the load on the lateral ankle structures. The patient is placed into a splint and returns at two weeks for a wound check. A weightbearing cast is applied for an additional three weeks and the patient is then transitioned into a CAM walker boot and begins therapy. Usually by 8-10 weeks, the patient is back in a regular tennis shoe with an ankle brace. Swelling may continue for several months following the operative procedure.

 

 

Os Peroneum Syndrome
The os peroneum sits within the contents of the peroneal longus tendon as it curves under the cuboid and heads towards the plantar aspect of the foot (Figure 4). This accessory bone of the foot can lead to degeneration of the peroneal longus tendon and chronic pain in this area. Approach to this problem surgically is through a lateral incision with splitting of the peroneal tendon sheath. The os peroneum is then carefully excised from the tendon with direct repair of the tendon. The postoperative regimen is the same as that discussed above for tenosynovectomy.

 

 

Peroneal Brevis Tendon Split Tears
Repair of peroneal tendon tears is usually necessary to alleviate the symptoms associated with these injuries. A repair of any involved ligaments is essential in reestablishing ankle stability, commonly the ATFL and CFL. Additionally, suturing the ruptured tendon back together and maintaining its tubular structure is important in retaining its original shape. The approach is the same as that described above with takedown of the superior peroneal retinaculum to allow exposure of the peroneal tendons over their full course. If a single longitudinal split is identified, it is repaired with a running nonabsorbable suture, usually Ethibond, Fiberwire or Nylon. If the tendon has several longitudinal splits, an attempt is made to debride the tendon and tubularize the remaining tendon (Figure 5). If greater than 50% of the tendon is involved with tendinosis and split tearing, the diseased portion of the tendon is excised with tenodesis (repair of the remaining tendon) of the proximal and distal segments to the peroneal longus tendon (Figure 6A, 6B). The superior peroneal retinaculum is then repaired with suture anchors. The postoperative course is similar to that described above with return to shoe and brace at 10-12 weeks.

 

 

Peroneal Tendon Subluxation
Often associated with peroneal tendinosis and tears is peroneal subluxation and/or dislocation (Figure 7). The tendon pathology is approached as discussed above. If it is felt preoperatively that peroneal subluxation may be present, it may be necessary to address this with a retinacular repair with or without a groove deepening procedure. The simple retinacular repair was discussed above. Groove deepening adds depth to the posterior fibular groove to prevent further subluxation. This is typically done by elevating a periosteal flap and removing some underlying bone with a burr and then reattaching this structure with repair of the soft tissues as described (Figure 8). This procedure creates a trough for the peroneal tendons and is secured by repair and tightening of the superior peroneal retinaculum. Postoperative protocols are the same as those discussed under the tenosynovitis and tendinosis section.

REFERENCES

  • Calliet, Rene, MD. Foot and Ankle Pain. Philadelphia: F. A. Davis Company, 1995.
  • Coughlin, MJ, Schon, L: Disorders of Tendons, In Surgery of the Foot and Ankle, pp. 1149-1277, Edited by Coughlin, M, Mann, R and Saltzman, C, C.V. Mosby, 8th Ed., 2007.
  • Hort, K, DeOrio, J: Peroneal Tendon Pathology, eMedicine, (March 2005)
  • Karageanes, S: "Peroneal Tendon Syndromes." eMedicine (Feb. 2006). 11 Oct. 2006. http://www.emedicine.com/SPORTS/topic98.htm
  • Krause, JO, Brodsky, JW: Peroneus brevis tendon tears: pathophysiology, surgical reconstruction and clinical results, Foot Ankle Int 1998, May; 19(5): 271-9.
  • Sammarco, GJ: Peroneus longus tendon tears: acute and chronic, Foot and Ankle Int, 1995, May; 16(5): 245-53.