Orthopedics and Orthopedics Surgery

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Achilles Tendon Dysfunction
Robert C. Greenberg, MD and Charles L. Saltzman, MD

The Achilles tendon is the largest and strongest tendon in the body. The tendon has no true synovial sheath but is encased in a paratenon of varying thickness. The vascular supply to the tendon comes distally from intraosseous vessels from the calcaneus and proximally from intramuscular branches. There is a relative area of avascularity 2 to 6 cm from the calcaneal insertion that is more vulnerable to degeneration and injury. Achilles tendon injuries are commonly associated with repetitive impact loading due to running and jumping. The primary factors resulting in damage of the Achilles tendon are training errors such as a sudden increase in activity, a sudden increase in training intensity (distance, frequency), resuming training after a long period of inactivity, and running on uneven or loose terrain. Achilles dysfunction can also be related to postural problems (e.g., pronation), poor footwear (generally poor hindfoot support), and a tight gastrocsoleus complex.

Diagnosis—Achilles Tendinitis
Pain is typically located in the area of the distal Achilles tendon approximately 2 to 6 cm from the calcaneal insertion. With initial morning activity, pain is noted that is described as sharp or burning pain. The pain is initially present only with vigorous activity and progresses to pain with activities of daily living. Pain is typically relieved with rest.

Examination
Examination is performed with the patient placed prone and the feet hanging off the edge of the table. Palpate the entire substance of the gastrocnemius-soleus myotendinous complex while the ankle is put through active and passive ROM. Evaluate for tenderness, warmth, swelling or fullness, nodularity, or substance defect. The Thompson test is performed to evaluate the continuity of the Achilles tendon (Fig. 5–39). A positive Thompson test (no plantar flexion of the foot with squeezing of the calf) indicates a complete rupture of the tendinoachilles. Note the resting position of the forefoot with the ankle and talonavicular joints held in the neutral position. Ankle and subtalar mobility may often be decreased. Calf atrophy is common in any Achilles tendon dysfunction.

While seated on the exam table, the patient’s foot shoud be passively dorsiflexed, first with the knee flexed and then with the knee fully extended. This will tell the examiner how tight the Achilles tendon is. Many females who have worn high heel shoes for years won’t be able to dorsiflex the foot to neutral with the knee in full extension.

Classification of Achilles Tendon Problems
Achilles tendon problems generally are classified as paratenonitis, tendinosis, or rupture.

Imaging
Most Achilles problems can be diagnosed with a thorough history and physical examination. Imaging helps confirm the diagnosis, assist with surgical planning, or rule out other diagnoses.

Routine radiographs are generally normal. Occasionally, calcification in the tendon or its insertion is noted. Inflammatory arthropathies (erosions), Haglund’s deformity (pump bump) can be ruled out on radiographs.

Ultrasound is inexpensive and fast and allows dynamic examination, but it requires substantial interpreter experience. It is the most reliable method for determining the thickness of the Achilles tendon and the size of a gap after a complete rupture.

MRI is not used for dynamic assessment, but it is superior in the detection of partial tears and the evaluation of various stages of chronic degenerative changes, such as peritendinous thickening and inflammation. MRI can be used to monitor tendon healing when recurrent partial rupture is suspected and is the best modality for surgical planning (location, size).

Achilles Paratenonitis
Background
Inflammation is limited to the paratenon without associated Achilles tendinosis. Fluid often accumulates next to the tendon, the paratenon is thickened and adherent to normal tendon tissue. Achilles paratenonitis most commonly occurs in mature athletes involved in running and jumping activities. It generally does not progress to degeneration. Histology of paratenonitis shows inflammatory cells, and capillary and fibroblastic proliferation in the paratenon or peritendinous areolar tissue.

Clinical Signs and Symptoms
Pain starts with initial morning activity. The discomfort is well-localized tenderness and sharp, burning pain with activity. The discomfort is present 2 to 6 cm proximal to the insertion of the Achilles tendon into the calcaneus. Pain is primarily aggravated by activity and relieved by rest. Pain is present with single-heel raise and absent on the Thompson test. Significant heel cord contracture will exacerbate symptoms.

Swelling, local tenderness, warmth, and tendon thickening are common. Calf atrophy and weakness and tendon nodularity can be present in chronic cases. Crepitation is rare.

Painful arc sign (Fig. 5–40) is negative in paratenonitis. It is important to localize the precise area of tenderness and fullness. In paratenonitis, the area of tenderness and fullness stays fixed with active ROM of ankle. The inflammation involves only the paratenon, which is a fixed structure, unlike pathology of the Achilles tendon itself, which migrates superiorly and inferiorly with ROM of the ankle.

In the acute setting, symptoms are typically transient, present only with activity, and last less than 2 weeks. Later, symptoms start at the beginning of exercising or at rest, and tenderness increases. The area of tenderness is well localized and reproducible by side-to-side squeezing of the involved region.

Partial rupture may be superimposed on chronic paratenonitis and can present as an acute episode of pain and swelling.

Operative Treatment for Paratenonitis
Operative treatment generally is indicated if 4 to 6 months of conservative treatment fails to relieve symptoms. Preoperative MRI usually is obtained primarily to evaluate for associated tendinosis and confirm diagnosis.

Technique
The patient is positioned prone and a thigh tourniquet is applied. A longitudinal incision is made postero-medially along the Achilles tendon. Full-thickness flaps are raised, with very gentle soft tissue handling. The thickened paratenon and adhesions are removed posteriorly, medially, and laterally as needed. Anterior dissection is avoided because the blood supply of the tendon is primarily within the anterior mesotenon and fat pad. The tendon is inspected for thickening and degeneration (tendinosis); if noted intraoperatively or on MRI, surgical treatment is as described for tendinosis.

Postoperative Protocol

Padded splint is applied in neutral position.

Non–weight-bearing motion is initiated immediately, both active ROM and gentle passive dorsiflexion with rubber tubing.

Crutch-assisted weight-bearing as tolerated after 7 to 10 days, when pain permits and swelling has decreased. If the wound is healing uneventfully at 2 to 3 weeks, ambulation is allowed as tolerated.

Exercises are begun on a stationary bike and stair climber when the patient can walk without pain. Swimming and aqua jogging are allowed, as tolerated by the patient and when the wound is healed.

Running can be resumed 6 to 10 weeks postoperative.

Return to competition is allowed after 3 to 6 months; calf strength must be at least 80% of the normal side.

Achilles Tendinosis
Background
Achilles tendinosis is characterized by intratendi-nous or mucoid degeneration of the Achilles tendon without evidence of paratenonitis (inflammation). The process starts with interstitial microscopic failure, which leads to central tissue necrosis with subsequent mucoid degeneration Achilles tendinosis most commonly occurs in mature athletes as the result of accumulated repetitive microtrauma from training errors. It is associated with an increased risk of Achilles tendon rupture.

The histology generally is noninflammatory, showing decreased cellularity and fibrillation of collagen fibers within the tendon. Along with the collagen fiber disorganization, there is scattered vascular ingrowth and occasional areas of necrosis and rare calcification.

Initially, the paratenon sheath may become inflamed, and with overuse, the tendon itself becomes inflamed or hypovascular because of the restriction of blood flow through the scarred paratenon.

Clinical Signs and Symptoms
Achilles tendinosis is often asymptomatic and remains subclinical until it presents as a rupture. It may elicit low-grade discomfort related to activities, and a palpable painless mass or nodule may be present 2 to 6 cm proximal to the insertion of the tendon. This can progress to gradual thickening of the entire tendon substance.

The painful arc sign is positive in patients with Achilles tendinosis. The thickened portion of tendon moves with active plantar flexion and dorsiflexion of the ankle (in contrast to paratenonitis, in which the area of tenderness remains in one position despite dorsiflexion and plantar flexion of the foot).

Paratenonitis and tendinosis can coexist when inflammation involves both the paratenon and intra-tendinous focal degeneration. This gives the clinical appearance of paratenonitis because the symptoms associated with tendinosis are absent or very subtle. Most patients seek treatment for symptoms related to the paratenonitis, and usually, the tendinosis is unrecognized until both processes are noted on MRI or at surgery (most commonly after a rupture). Conservative treatment is the same as for paratenonitis. MRI is very useful in preoperative planning, which must consider both entities.

Treatment
The initial treatment of Achilles tendinosis is always conservative and progresses as described for paratenonitis. If symptoms are severe, initial treatment may include 1 to 2 weeks of immobilization and crutch ambulation, in addition to NSAIDs, ice, and heel cord stretching. Foot and leg alignment should be carefully evaluated, with orthotic correction if necessary. Conservative treatment is continued for 4 to 6 months; surgery is indicated if this fails to relieve symptoms.

Operative Treatment
MRI is used to confirm the diagnosis and plan the operative procedure.

Technique
The patient is placed prone with a thigh tourniquet and the foot hanging off the end of the table. The incision is placed posteromedially just off the edge of the tendon (avoids the sural nerve). Full-thickness flaps are created with very careful soft tissue handling. The paratenon is inspected and any hypertrophic paratenon adherent to the tendon is excised. A longitudinal incision is made within the body of the tendon over the thickened, nodular parts to expose areas of central tendon necrosis. Degenerative areas are excised (should correspond with MRI). Débridement is followed by side-to-side closure to repair any defect. If the defect is too large to be closed primarily or lacks adequate substance after débridement, the Achilles tendon is reconstructed using the plantaris tendon, flexor digitorum longus, or a turndown flap.

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