出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2014/03/31 20:06:29」(JST)
The Achilles tendon is the strongest and thickest tendon in the body, connecting the gastrocnemius, soleus and plantaris to the calcaneus. It is approximately 15 centimeters (5.9 inches) long and begins near the middle portion of the calf. Contraction of the gastrosoleus plantar flexes the foot, enabling such activities as walking, jumping, and running. The Achilles tendon receives its blood supply from its musculotendinous junction with the triceps surae and its innervation from the sural nerve and to a lesser degree from the tibial nerve.
The Achilles tendon is most commonly injured by sudden plantarflexion or dorsiflexion of the ankle, or by forced dorsiflexion of the ankle outside its normal range of motion.
Other mechanisms by which the Achilles can be torn involve sudden direct trauma to the tendon, or sudden activation of the Achilles after atrophy from prolonged periods of inactivity. Some other common tears can occur from overuse while participating in intense sports. Twisting or jerking motions can also contribute to injury.
Fluoroquinolone antibiotics, famously ciprofloxacin, are known to increase the risk of tendon rupture, particularly achilles.
People who commonly fall victim to Achilles rupture or tear include recreational athletes, people of old age, individuals with previous Achilles tendon tears or ruptures, previous tendon injections or quinolone use, extreme changes in training intensity or activity level, and participation in a new activity.
Most cases of Achilles tendon rupture are traumatic sports injuries. The average age of patients is 29–40 years with a male-to-female ratio of nearly 20:1. Fluoroquinolone antibiotics, such as ciprofloxacin, and glucocorticoids have been linked with an increased risk of Achilles tendon rupture. Direct steroid injections into the tendon have also been linked to rupture.
Quinolone has been associated with Achilles tendinitis and Achilles tendon ruptures for quite some time now. Quinolones are antibacterial agents that act at the level of DNA by inhibiting DNA Gyrase. DNA Gyrase is an enzyme used to unwind double stranded DNA which is essential to DNA Replication. Quinolone is specialized in the fact that it can attack bacterial DNA and prevent them from replicating by this process, and are frequently prescribed to elderly. Approximately 2% to 6% of all elderly people over the age of 60 that have had Achilles ruptures can be attributed to the use of quinolones.[1]
Diagnosis is made by clinical history; typically people say it feels like being kicked or shot behind the ankle. Upon examination a gap may be felt just above the heel unless swelling has filled the gap and the Simmonds' test (aka Thompson test) will be positive; squeezing the calf muscles of the affected side while the patient lies prone, face down, with his feet hanging loose results in no movement (no passive plantarflexion) of the foot, while movement is expected with an intact Achilles tendon and should be observable upon manipulation of the uninvolved calf. Walking will usually be severely impaired, as the patient will be unable to step off the ground using the injured leg. The patient will also be unable to stand up on the toes of that leg, and pointing the foot downward (plantarflexion) will be impaired. Pain may be severe, and swelling is common.
An O'Brien test can also be performed which entails placing a sterile needle through the skin and into the tendon. If the needle hub moves in the opposite direction of the tendon and the same direction as the toes when the foot is moved up and down then the tendon is at least partially intact.
Sometimes an ultrasound scan may be required to clarify or confirm the diagnosis. MRI can also be used to confirm the diagnosis.
Musculoskeletal ultrasonography can be used to determine the tendon thickness, character, and presence of a tear. It works by sending extremely high frequencies of sound through your body. Some of these sounds are reflected back off the spaces between interstitial fluid and soft tissue or bone. These reflected images can be analyzed and computed into an image. These images are captured in real time and can be very helpful in detecting movement of the tendon and visualising possible injuries or tears. This device makes it very easy to spot structural damages to soft tissues, and consistent method of detecting this type of injury. This imaging modality is inexpensive, involves no ionizing radiation and, in the hands of skilled ultrasonographers, may be very reliable.
Magnetic resonance imaging (MRI) can be used to discern incomplete ruptures from degeneration of the Achilles tendon, and MRI can also distinguish between paratenonitis, tendinosis, and bursitis. This technique uses a strong uniform magnetic field to align millions of protons running through the body. these protons are then bombarded with radio waves that knock some of them out of alignment. When these protons return they emit their own unique radio waves that can be analysed by a computer in 3D to create sharp cross sectional image of the area of interest. MRI can provide unparalleled contrast in soft tissue for an extremely high quality photograph making it easy for technicians to spot tears and other injuries.
Radiography can also be used to indirectly identify achilles tears. Radiography uses X-rays to analyse the point of injury. This is not very effective at identifying injuries to soft tissue. X-rays are created when high energy electrons hit a metal source. X-ray images are acquired by utilising the different attenuation characteristics of dense (e.g. calcium in bone) and less dense (e.g. muscle) tissues when these rays pass through tissue and are captured on film. X-rays are generally exposed to optimise visualisation of dense objects such as bone while soft tissue remains relatively undifferentiated in the background. Radiography has little role in assessment of Achilles' tendon injury and is more useful for ruling out other injuries such as calcaneal fractures.[2]
Treatment options for an Achilles tendon rupture include surgical and non-surgical approaches. Among the medical profession opinions are divided what is to be preferred.
Non-surgical management traditionally was selected for minor ruptures, less active patients, and those with medical conditions that prevent them from undergoing surgery. It traditionally consisted of restriction in a plaster cast for six to eight weeks with the foot pointed downwards (to oppose the ends of the ruptured tendon). But recent studies have produced superior results with much more rapid rehabilitation in fixed or hinged boots.
Some surgeons feel an early surgical repair of the tendon is beneficial. The surgical option was long thought to offer a significantly smaller risk of re-rupture compared to traditional non-operative management (5% vs 15%).[3] Of course, surgery imposes higher relative risks of perioperative mortality and morbidity e.g. infection including MRSA, bleeding, deep vein thrombosis, lingering anesthesia effects, etc.
However, four recent studies have scientifically tested the benefits of surgery, using randomized streaming of patients into surgical and non-surgical protocols, and applying virtually identical (and aggressive) rehabilitation protocols to both types of patients. All four such studies completed to date have found only small, but statistically significant benefits from the surgery, separated from the other confounding variables. They have all produced reasonably comparable results in re-rupture rates (with each study adding a cautious note about small sample size, one study showing 12% re-rupture in non-surgical treatment versus 4% re-rupture in surgical treatment, which is statistically insignificant), strength, and range of motion, while most have reaffirmed the greater complication rate from surgery.[4][5][6][7] Two studies showed small, but statistically significant differences in plantarflexion strength. The surgical group had significantly better results in the heel-rise work, heel-rise height, concentric power, and hopping tests at the 6-month evaluation than did the nonsurgical group. However, at the 12-month evaluation, there was a significant between-groups difference only in the heel-rise work test.[8][9]
The relative benefits of surgical and nonsurgical treatments remains a subject of debate; authors of studies are cautious about the preferred treatment.[10] It should be noted that in centers that do not have early range of motion rehabilitation available, surgical repair is preferred to decrease re-rupture rates.[11]
There are two different types of surgeries; open surgery and percutaneous surgery.
During an open surgery an incision is made in the back of the leg and the Achilles tendon is stitched together. In a complete or serious rupture the tendon of plantaris or another vestigial muscle is harvested and wrapped around the Achilles tendon, increasing the strength of the repaired tendon.[12] If the tissue quality is poor, e.g. the injury has been neglected, the surgeon might use a reinforcement mesh (collagen, Artelon or other degradable material).
In percutaneous surgery, the surgeon makes several small incisions, rather than one large incision, and sews the tendon back together through the incision(s). Surgery may be delayed for about a week after the rupture to let the swelling go down.[13] For sedentary patients and those who have vasculopathy or risks for poor healing, percutaneous surgical repair may be a better treatment choice than open surgical repair.[14]
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リンク元 | 「アキレス腱断裂」 |
関連記事 | 「rupture」「tend」「Achilles tendon」 |
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