الفهرس 
AnatomyOnly 14 pages are availabe for public view
 |  | from | 9 |  |  |
| | | from | 9 | | |
Abstract
The Achilles tendon is the strongest tendon in the body, serving both the gastrocnemius and soleus muscles. It begins near the mid-calf and inserts posteriorly at the calcaneus .In the region where the tendon joins the bone, there is an amalgam called the enthesis organ, in which the tissue is a composite of bone and tendon. Kager’s fat pad is located anterior to the Achilles tendon and posterior to the calcaneus, forms the superior border of this enthesis organ, and protects the blood vessels of the Achilles tendon. The fat pad may also provide a mechanical advantage by increasing the lever angle of the Achilles tendon during plantar flexion. Unlike other tendons, the Achilles does not have a true synovial sheath but has a paratenon, which is a sheath of flexible connective tissue that allows for a gliding action. The paratenon and Achilles tendon are innervated by nerves from attached muscles and small fasciculi from cutaneous nerves, especially the sural nerve. The paratenon is a highly vascular structure, and along with the surrounding muscle complex supplies blood to the Achilles tendon. The most common causes of Achilles disorders are midsubstance tendinopathy (55-65%), followed by insertional tendinopathy (20-25%). Achilles tendon disorders can affect anyone, but they most commonly affect active people, especially those who participate in running or jumping sports. Age, sex, and obesity have been cited as risk factors for Achilles tendon disorders, but a recent study of athletes over 40 years of age found no influence of any of these factors. Most Achilles disorders are diagnosed clinically. Imaging may be useful, however, when the diagnosis is unclear or when trying to differentiate between complete or partial tendon rupture. Ultrasound and MRI are useful when clinical examination does not yield a definitive diagnosis. MRI is useful in the diagnosis of tendon disorders because it can detect abnormalities in the entire locomotor unit, including the tendon, calcaneus, Achilles insertion, retrocalcaneal bursa, peritendinous tissues, and musculotendinous junction. MRI findings also correlate with findings at surgery and may be useful for surgical planning. Ultrasound, however, can provide a dynamic assessment of the tendon and can evaluate for tissue neovascularization. Perhaps more importantly, it can be used to guide percutaneous procedures and is therefore becoming a popular imaging tool. In a prospective blinded comparison study of ultrasound and MRI for identification of Achilles tendinopathy, both had similar specificity, but MRI had better sensitivity (95% v 80%.( However, MRI was less sensitive in the diagnosis of Achilles tendon rupture and may be useful only for operative planning. Ultrasound was used to measure neovascularization before and after eccentric exercises to help predict patient outcome, with a decrease in neovascularity corresponding to patient improvement. It has been suggested that, in trained hands, ultrasound is better for focused examinations or for guiding intervention, whereas MRI is better for global assessment of the tendon or for operative planning.Achilles tendon injuries have been divided into spontaneous ruptures and overuse injuries. Generally, Achilles tendon problems arise from two different origins: some symptoms are caused solely by the excessive loading-induced injury or degeneration of the Achilles tendon (without any predisposing systemic diseases); and sometimes a systemic disease, such as rheumatoid arthritis, manifests with Achilles tendon symptoms. Only a minority (~2%) of all Achilles tendon complaints and injuries are a result of a systemic, predisposing disease; most tendon problems in a population can be traced to sports and exercise-related overuse. Most of the Achilles tendon overuse injuries are successfully treated with nonoperative management. This usually consists of a brief period of rest, activity modification, and correction of malalignment with orthotics, and nonsteroidal anti inflammatory drugs. Other modalities that are helpful include ionophoresis, stretching, eccentric calf strengthening exercises, and a heel lift. Steroid injections are not indicated because this places the Achilles tendon at higher risk of rupture. A gradual, progressive rehabilitation program should be instituted. Nonoperative measures are 90% to 95% successful for acute treatment; however, up to 29% require surgical treatment for chronic problems that fail conservative management.