Published Article: Retrocalcaneal Pain, Lower Extremity Review, March 1996

Dr. Amol Saxena, DPM
Palo Alto Foundation
Medical Group
Dept. of Sports Medicine
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Dr. Amol Saxena, DPM

Articles

Retrocalcaneal Pain. March 1996 The Lower Extremity, Churchill Livingstone.

Amol Saxena, D.P.M., F.A.C, F.A.S.

Julie Lee, D.P.M.
Resident, California College
of Podiatric Medicine

Walter Pyka, M.D.

INTRODUCTION

Heel pain is one of the most commonly treated lower extremity pathologies. Pain in the retrocalcaneal region could be due to many reasons; successful treatment depends on localizing pathology. Retrocalcaneal pain can be referred from four anatomical areas: the myotendinous junction of the gastrocnemius-soleus complex, the watershed area of the Achilles tendon, the posterior triangle of the ankle, and the Achilles insertion. Nerve entrapment and radicular symptoms can also refer pain to this region. The purpose of this paper is to produce an algorithm for evaluation and treatment of retrocalcaneal pain.

Pain in the retrocalcaneal region can be referred from the gastocnemius-soleus junction. The differential diagnosis for pain of the myotendinous junction includes posterior compartment syndrome, plantaris rupture, tear of the medial head of the gastrocnemius muscle (tennis leg), and myositis ossificans/calcinosis. Acute compartment syndrome may be caused by trauma such as a crush injury resulting in an increased pressure within a myofascial compartment which leads to ischemia and subsequent necrosis of neuromuscular tissues. Chronic compartment syndrome is described as a transient increase in compartment pressure that is induced by exercise and relieved by rest. Compartment pressures greater than 30 mmHg during activity or greater than 10 mmHg after five minutes of rest are considered abnormal and are an indication for surgical fasciotomy.

The differential diagnosis for pathology in the watershed area includes Achilles tendon rupture (complete or partial), tendinosis, peritendinosis, and soft tissue tumor. Peritendinosis and tendinosis may co-exist. In reviewing the literature, the terms tenosynovitis, peritendinitis, peritendinosis, paratendinosis and paratendinitis are used synonymously to describe inflammation of the peritenon.

The tendo Achilles possesses no synovial sheath. Instead it has a peritenon which serves the same function. The peritenon consists of three layers: parietal, visceral and the mesotenon. The mesotenon connects the outer parietal with the inner visceral layer. The tendo Achilles like any other tendon consists of many bundles surrounded by an epitinon with each collagen bundle surrounded by endotinon. The vascular supply to the tendo Achilles is provided from the musculotendinous junction proximally, the periosteum distally, and the peritenon itself. There is a zone of relative avascularity located two to six centimeters proximal to its insertion. This zone is also referred to as the watershed area of the tendo Achilles. Due to its lack of vascularity, this area is prone to tendinosis and rupture. The watershed area's blood supply is mainly from the peritenon, specifically vessels in the mesotenon anteriorly.

The anatomy of the Achilles tendon makes it vulnerable to having different pathologies. The tendo Achilles is the strongest tendon in the body. Its function is to transmit load from the triceps surae to the calcaneus. It is able to withstand forces eight times the body weight as produced while running. Overuse injuries of the Achilles tendon are common in running and other sports that involve jumping and sprinting movements. The tendo Achilles is the largest tendon in the body. It originates approximately 15 cm above the calcaneus and is approximately 6 cm in length. It consists of fibers from the gastrocnemius and soleus muscles. The fibers rotate approximately 90° as it heads towards the insertion of the middle third of the posterior calcaneus. This rotation causes the fibers that lie mediosuperiorly to come to lie superficially superodistally, and the fibers that lie lateroproximally come to lie deep distally.

Signs and symptoms of peritendinosis are pain, diffuse swelling, warmth, thickening of the tendon, and crepitation of the tendon with ankle joint range of motion. The pain of peritendinosis characterizes moving in an arc when the ankle joints dorsiflex and plantarflex. Peritendinosis may not respond to or be exacerbated by immobilization, heel lifts, and cold therapy. Massage of the myotendinous junction alleviates symptoms whereas direct massage of the painful site may increase symptoms. Magnetic resonance imaging demonstrates fluids surrounding the tendon as an intermediate signal intensity on T1 weighted images and a high signal intensity (white) on T2 weighted images. The peritenon can be visualized as a low signal intensity (black) rim around the fluid. (Fig) Initial conservative treatment consists of rest and anti-inflammatory modalities, such as nonsteroidal anti-inflammatories, ultrasound, and phonophoresis. Orthoses may be beneficial in reducing the torque of the Achilles. If the patient does not respond to these modalities, then a peritenon "brisement" injection may be given. Local anesthetic is injected into the peritenon sheath to break up any adhesions that may be present. The volume adhesiotomy effect of the injection may be minimal (and therefore unsuccessful) when moderate fibrosis is noted clinically and on MRI. If conservative treatment fails, generally after three to six months, then surgical treatment is indicated. The procedure consists of tenolysis of peritenon taking care not to disrupt the vascular supply of the tendon. Tendinosis is chronic tendinitis characterized by tendinous degeneration. It is associated with aging, repetitive microtrauma or partial tears, and vascular compromise. Tendinosis may present as an asymptomatic, palpable tendon nodule. The patient may report a history of previous Achilles tendinitis or injury. Histologically, there is mucoid degeneration of the tendon, which is well visualized on MRI. Magnetic resonance imaging will demonstrate an intact tendon disrupted by intratendinous areas of high signal intensity on T1 and T2 weighted images. The findings are similar to those found in partial ruptures of tendo Achilles. Tendinosis and partial ruptures of the Achilles tendon are functionally the same in that they are both partial disruptions of tendon fibers. (Fig) Peritendinosis and tendinosis can occur simultaneously. This presents as activity related pain, crepitation of the tendon with motion, morning stiffness and thickening of the tendon and/or a nodule in the tendon. Conservative treatment consists of heel lifts and orthotics to decrease the tension in the Achilles tendon. Physical therapy modalities such as those mentioned with peritendinosis along with deep friction massage are helpful. Surgical intervention is indicated if there is a suspicion of probable rupture of the tendon or if there is associated peritendinosis and the patient is asymptomatic. Surgical procedure involves excision and curettment of all degenerated areas. Small defects are repaired with #2-0 absorbable suture. The watershed area is augmented with #2 nonabsorbable suture after the tear is completely debrided. If the insertion of the tendo Achilles is involved, then it can be re-attached to the calcaneus with Mitek suture.

Achilles tendon ruptures are common in males 18 to 35 and usually occur during recreational activity. The patient reports a history of a sudden, sharp pain in the back of the leg. The patient will usually recall an audible pop with a complete rupture of the tendon. Both partial and complete ruptures present with localized tenderness and nodular swelling of the Achilles tendon. Complete rupture is distinguishable from a partial rupture on physical examination. There are two signs that indicate a complete rupture of the tendo Achilles: a palpable depression in the tendon, and a positive Thompson's test. The Thompson's test is positive when squeezing the calf does not produce plantar flexion of the foot. There may be proximal calf atrophy and increased passive dorsiflexion of the ankle with a complete rupture. The patient is also unable to perform a single heel raise on the effected side. Plain films demonstrate a blunting of Kager's triangle caused by increased soft tissue density due to edema and hemorrhage. Magnetic resonance imaging of a complete rupture will demonstrate disruption of tendon fibers with associated hemorrhage and edema in the pre-Achilles fat pad. There will be an intermediate signal intensity on T1 weighted images and a high signal intensity on T2 weighted images between the disrupted ends. (Fig)

Partial ruptures of the Achilles tendon are often associated with tendinosis or peritendinosis. As stated earlier, tendinosis is basically a rupture of the tendon fibers but on a smaller scale. Therefore, tendinosis predisposes the tendon to rupture, partial or complete. In the case of partial rupture of the Achilles tendon, the patient may report hearing an audible snap. There is weakness, swelling, tenderness, and the patient is unable to walk on the effected leg. There may be a palpable defect depending on the amount of tendon torn. There is decreased dorsiflexion of the ankle joint (due to pain and spasm) and the Thompson's test is negative. The patient may not be able to perform a single heel raise. On magnetic resonance imaging the tendon is partially intact, but there is increased intratendinous signal on T1 an T2 weighted images. The extent of the rupture determines the treatment. (Fig) If less than 50% of the tendon is involved, nonoperative treatment is indicated. (In athletic patients, surgical repair is an option.) Conservative treatment consists of below-the-knee, weight-bearing cast for two to four weeks followed by four to six weeks in a weight-bearing removable cast and aggressive physical therapy. If greater than 50% of the tendon fibers are ruptured or if conservative treatment did produce satisfactory results, then surgical treatment is indicated. Surgical treatment consists of debridement of the tendon and repair of the ruptured tendon.

The treatment of a complete Achilles rupture has long been debated whether conservative versus surgical treatment produces a significantly better result. Most studies show that surgical treatment provides a better result than conservative treatment, but the conservative treatment can produce a satisfactory result. Conservative treatment has a high rerupture rate and a decreased performance rate. Therefore, the determining factor when choosing a treatment option is the patient's health status, age, desired activity level and compliancy. The accepted conservative treatment is a below-the knee, nonweight-bearing cast in equinus for three to six weeks. The cast is changed every two weeks in order that progressive reduction of the equinus may be achieved. This is followed by two to six weeks in a weight-bearing cast with the ankle in neutral position. Twelve weeks of cast immobilization is followed by aggressive physical therapy to restore strength and flexibility to the effected leg. Surgical treatment consists of trying to repair the ruptured Achilles tendon. The frayed ends of the ruptured tendon are resected and reapproximated with

#2 nonabsorbable suture in a Bunnell-type fashion. Postoperative care is generally the same for any repair of the Achilles tendon. This regimen consists of a nonweight-bearing, below-the-knee cast for three to four weeks with the foot in equinus. Gradual progression to full weight-bearing occurs over the next four weeks in a removable cast. An aggressive rehabilitation is begun at eight to ten weeks postoperatively. The patient may return to running sports at twelve to sixteen weeks postoperatively.

Clear-cell sarcomas, xanthomas, and accessory soleus muscle are all soft-tissue tumors that may occur in the retrocalcaneal area in association with the Achilles tendon. Clear-cell sarcoma was first described by Enzinger and is a rare malignant soft-tissue tumor associated with tendon sheaths and aponeuroses. It primarily occurs in the extremities and effects patients between the ages of 20 to 40 years old. It presents as a slowly enlarging mass causing tenderness and pain. Plain films demonstrate a soft tissue mass with no calcification and no changes to the underlying bone. Hyperlipoproteinemia

Types II, III, IV are associated with tendinous xanthomas. Type II hyperlipoproteinemia is also associated with Achilles tendinitis. Accessory soleus muscle may also cause pain and swelling of the ankle. The incidence is up to 6%. Magnetic resonance imaging has been shown to demonstrate the presence of an accessory muscle.

The differential diagnosis for pain in the insertion of the Achilles tendon includes tendocalcinosis, tendinosis, retrocalcaneal bursitis, exostosis, bone tumor, stress fracture, apophysitis and tendofasciitis. Tendinosis has previously been discussed. Bone tumors may be ruled out by plain films. Care must be taken to differentiate between tendofasciitis and plantarfasciitis.

Similar in symptoms to plantar fasciitis, tendofasciitis is painful in the morning and after periods of rest. The location of the pain, however, is at the distal-most Achilles insertion and extends to the inferoplantar heel where the Achilles fibers communicate with the plantar fascia. This entity responds well to heel lifts and physical therapy.

Tendocalcinosis can be characterized by retrocalcaneal mass, dull achy pain with localized tenderness at the insertion. The pain is worse with active and passive ankle joint range of motion with physical activity. The calcification may crack and fragment. This can be visualized on an x-ray. There may be a history of Achilles tendinitis and patients may also have a functional equinus. On plain radiographs there is calcification within the Achilles tendon and/or a posteriorcalcaneal exostosis.(Fig) Conservative treatment consists of stretching, ice massage, modification of activities, heel lifts, orthoses, etc. If conservative treatment does not produce adequate results, then surgical excision of the tendinocalcinosis is indicated.

Retrocalcaneal bursitis has many systemic etiologies. These include rheumatoid arthritis, gout, Reiter's syndrome, ankylosing spondylolysis, psoriatic arthritis, and connective tissue diseases. It may also be caused by mechanical etiologies such as shoe pressure, retrocalcaneal exostosis or Haglund's deformity.

There are two bursae associated with the tendo Achilles: the deep retrocalcaneal bursa and the superficial retrocalcaneal bursa. The superficial retrocalcaneal bursa lies between the tendo Achilles and the overlying skin. The deep retrocalcaneal bursa lies between the calcaneus and the tendo Achilles. It is these two structures that are inflamed with retrocalcaneal bursitis or Haglund's syndrome.

Shoe pressure can cause a superficial retrocalcaneal bursitis. A retrocalcaneal exostosis is a bony proliferation of the posterior aspect of the calcaneus above or at the insertion of the tendo Achilles. The exostosis can be associated with calcification of the tendo Achilles. Haglund's deformity is a prominent posterosuperior lateral aspect of the calcaneus. It presents as a dull achy soreness in the posterosuperior heel. The pain is exacerbated by activity and shoes. On physical examination an erythematous, edematous, posterosuperior,lateral prominence near the insertion of the Achilles tendon is noted. On plain films a Phillips-Fowler angle of greater than 75° , and a total angle greater than 90° is indicative of Haglund's deformity. Conservative treatment consists of gastrocsoleus stretching, ice massage, modification of activities, heel lifts, and nonsteroidal anti-inflammatories. Surgery may consist of a retrocalcaneal exostectomy, or an osteotomy, as described by Keck and Kelly, depending on the degree of deformity present. One should note injection of retrocalcaneal bursitis is associated with Achilles tendon rupture, particularly in the athletic individual.(Fig)

Calcaneal stress fracture may be evident on x-ray, but bone scan and MRI may be more helpful for quick diagnosis.(Fig) Edema and pain with manual pressure on the sides of the calcaneus are hallmarks. Treatment involves below-the-knee cast, immobilization for six to eight weeks with the initial three weeks nonweight bearing.

Calcaneal apophysitis (Sever's disease) manifests between ages 10 to 14 years as pain at the Achilles insertion and the sides of the calcaneus. It is generally self limiting; however, treatment may include rest, anti-inflammatories, heel lifts/cups, and ice. Symptoms generally resolve in three to six months.

Avulsion fractures of the calcaneus in the retrocalcaneal region are classified in the Rowe system. Rowe IIA is a fracture which involves the posterior calcaneal tuberosity superior to the Achilles insertion. Rowe IIB is a fracture involving the Achilles insertion itself. These fractures are often treated surgically with open reduction. Immobilization ranges up to 12 weeks with the Rowe IIB fractures.

Often posterior triangle pain will be described as retrocalcaneal or Achilles pain. Therefore, the differential diagnoses for retrocalcaneal pain should include posterior impingement syndrome, os/trigonum fracture, tenosynovitis or tendinitis of the flexor halucis longus tendon and other posterior muscle tendons. Posterior impingement syndrome is inflammation of the posterior capsule of the ankle joint deep to the Achilles tendon. Pain can be reproduced via maximum plantar flexion of the ankle joint and/or when the patient stands on their toes. For this reason, this type of pathology is common with dancers. An os/trigonum fracture, or posterior process fracture can be evaluated by plain films. Bone scans can help confirm the diagnosis. Tenosynovitis of the tendons that course along the posteromedial aspect of the tendon can be evaluated by reproducible pain with exertion of the particular tendon and palpable crepitus. Treatment for posterior impingement syndrome and os/trigonum injury may include immobilization up to six weeks in a below-the-knee cast. A nonunited os/trigonum or posterior process fracture (Shepherd's fracture) may be treated with excision of the fragment. Steroid injection with phosphate solution may be used to decrease posterior ankle capsule and inflammation taking care to avoid the flexor tendons and neurovascular bundle. Tenosynovitis is often treated with anti-inflammatory and physical therapy modalities mentioned above; Recalcitrant cases may respond to tenosynovectomy of the involved posteromedial ankle tendon.

Amol Saxena, D.P.M., F.A.C,
Julie Lee, D.P.M.

CONCLUSION

There are numerous causes for pain in the retrocalcaneal region. Several differential diagnoses have been presented with attention given to the disorders of the tendo Achilles. An accurate diagnosis is essential to determine proper treatment and to best serve the patient.

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