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Ankle Sprain 

​足関節捻挫  足首の捻挫

1 病名・病態  Diagnosis and Condition

n ankle sprain occurs when the strong ligaments that support the ankle stretch beyond their limits and tear. Ankle sprains are common injuries that occur among people of all ages. They range from mild to severe, depending upon how much damage there is to the ligaments.

Most sprains are minor injuries that heal with home treatments like rest and applying ice. However, if your ankle is very swollen and painful to walk on — or if you are having trouble putting weight on your ankle at all, be sure to see your doctor.

Without proper treatment and rehabilitation, a more severe sprain can weaken your ankle—making it more likely that you will injure it again. Repeated ankle sprains can lead to long-term problems, including chronic ankle pain, arthritis, and ongoing instability.







2 Description

Ligaments are strong, fibrous tissues that connect bones to other bones. The ligaments in the ankle help to keep the bones in proper position and stabilize the joint.

Most sprained ankles occur in the lateral ligaments on the outside of the ankle. Sprains can range from tiny tears in the fibers that make up the ligament to complete tears through the tissue.

If there is a complete tear of the ligaments, the ankle may become unstable after the initial injury phase passes. Over time, this instability can result in damage to the bones and cartilage of the ankle joint.



Cause 原因

Your foot can twist unexpectedly during many different activities, such as:

  • Walking or exercising on an uneven surface

  • Falling down

  • Participating in sports that require cutting actions or rolling and twisting of the foot—such as trail running, basketball, tennis, football, and soccer

  • During sports activities, someone else may step on your foot while you are running, causing your foot to twist or roll to the side.



  • 凹凸のある場所での歩行や運動

  • 落下

  • トレイルラン、バスケットボール、テニス、アメリカンフットボール、サッカーなど、足を斬り込む動作、転がす動作、捻る動作を必要とするスポーツ

  • スポーツ中、走っているときに足を踏まれ、足を捻ったり、横に転がったりした際

Symptoms 症状

A sprained ankle is painful. Other symptoms may include:

  • Swelling

  • Bruising

  • Tenderness to touch

  • Instability of the ankle—this may occur when there has been complete tearing of the ligament or a complete dislocation of the ankle joint.



  • 腫脹

  • 皮下出血

  • 圧痛



If there is severe tearing of the ligaments, you might also hear or feel a "pop" when the sprain occurs. Symptoms of a severe sprain are similar to those of a broken bone and require prompt medical evaluation.



Doctor Examination 医師の診察

Physical Examination 身体の診察

Your doctor will diagnose your ankle sprain by performing a careful examination of your foot and ankle. This physical exam may be painful.

  • Palpate. Your doctor will gently press around the ankle to determine which ligaments are injured.

  • Range of motion. He or she may also move your ankle in different directions; however, a stiff, swollen ankle usually will not move much.

If there is no broken bone, your doctor may be able to tell the severity of your ankle sprain based upon the amount of swelling, pain, and bruising.



  • 触診  どの靭帯が損傷しているかを判断するために、足首の周りを優しく押します。

  • 可動域  足首を様々な方向に動かします; 硬く腫れている足首は、通常はあまり動かないでしょう。


Imaging Tests 画像診断

X-rays.  X-rays provide images of dense structures, such as bone. Your doctor may order x-rays to rule out a broken bone in your ankle or foot. A broken bone can cause similar symptoms of pain and swelling.

Stress x-rays. I n addition to plain x-rays, your doctor may also order stress x-rays. These scans are taken while the ankle is being pushed in different directions. Stress x-rays help to show whether the ankle is moving abnormally because of injured ligaments.

Magnetic resonance imaging (MRI) scan.  Your doctor may order an MRI if he or she suspects a very severe injury to the ligaments, damage to the cartilage or bone of the joint surface, a small bone chip, or another problem. The MRI may not be ordered until after the period of swelling and bruising resolves.

Ultrasound.  This imaging scan allows your doctor to observe the ligament directly while he or she moves your ankle. This helps your doctor to determine how much stability the ligament provides.


X線. 骨などの密な構造物をうつします。骨折を除外するためにレントゲンを撮像します。骨折は、痛みや腫れを呈します。

ストレスX線. 単純X線撮影に加えて、ストレスX線撮影をします。足関節を様々な方向に押しながら撮影します。ストレスX線は、靭帯損傷によって足関節が異常に動くかどうかを確認します。

MRI. 靭帯の重度の損傷、関節表面の軟骨や骨の損傷、小さな骨片、または別の問題が疑われる場合には、MRIを撮像することがあります。腫れや皮下出血が治まってからでないと、MRIを撮像しないこともあります。

超音波. 足関節を動かしながら靭帯を直接観察することができます。靭帯がどの程度安定しているかを判断するのに役立ちます。

Grades of Ankle Sprains 足首の捻挫の重症度

After the examination, your doctor will determine the grade of your sprain to help develop a treatment plan. Sprains are graded based on how much damage has occurred to the ligaments.

Grade 1 Sprain (Mild)

  • Slight stretching and microscopic tearing of the ligament fibers

  • Mild tenderness and swelling around the ankle

Grade 2 Sprain (Moderate)

  • Partial tearing of the ligament

  • Moderate tenderness and swelling around the ankle

  • If the doctor moves the ankle in certain ways, there is an abnormal looseness of the ankle joint

Grade 3 Sprain (Severe)

  • Complete tear of the ligament

  • Significant tenderness and swelling around the ankle

  • If the doctor pulls or pushes on the ankle joint in certain movements, substantial instability occurs



Grade 1 (軽症)

  • 靭帯の微小な伸展と微小な断裂

  • 足関節周囲の軽度圧痛と腫脹

Grade 2 (中等症)

  • 靭帯の部分断裂

  • 足関節周囲の中等度圧痛と腫脹

  • 特定の方向に足関節を他動させた際の足関節の異常な緩み

Grade 3 (重症)

  • 靭帯の完全断裂

  • 足関節周囲の顕著な圧痛と腫脹



Almost all ankle sprains can be treated without surgery. Even a complete ligament tear can heal without surgical repair if it is immobilized appropriately.

A three-phase program guides treatment for all ankle sprains—from mild to severe:

  • Phase 1 includes resting, protecting the ankle and reducing the swelling.

  • Phase 2 includes restoring range of motion, strength and flexibility.

  • Phase 3 includes maintenance exercises and the gradual return to activities that do not require turning or twisting the ankle. This will be followed later by being able to do activities that require sharp, sudden turns (cutting activities)—such as tennis, basketball, or football.

This three-phase treatment program may take just 2 weeks to complete for minor sprains, or up to 6 to 12 weeks for more severe injuries.




  • 第1段階では、安静にして足関節を保護し、腫脹を軽減させます。

  • 第2段階では、可動域、強度、柔軟性の回復を行います。

  • 第3段階では、維持運動を行い、足関節を回したり捻ったりする必要のない動作に徐々に戻していきます。続けて、テニス、バスケットボール、サッカーなど、鋭く急な旋回動作を必要とする活動ができるようになります。




Home Treatments 自宅療法

For milder sprains, your doctor may recommend simple home treatment.

The RICE protocol. Follow the RICE protocol as soon as possible after your injury:

  • Rest your ankle by not walking on it.

  • Ice should be immediately applied to keep the swelling down. It can be used for 20 to 30 minutes, three or four times daily. Do not apply ice directly to your skin.

  • Compression dressings, bandages or ace-wraps will immobilize and support your injured ankle.

  • Elevate your ankle above the level of your heart as often as possible during the first 48 hours.

Medication. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen can help control pain and swelling. Because they improve function by both reducing swelling and controlling pain, they are a better option for mild sprains than narcotic pain medicines.



RICE処置  受傷後はできるだけ早くRICE処置に従ってください。

  • (R)歩かないで安静にする。

  • (I)腫脹を抑えるために、すぐにアイシングする必要がある。1日3~4回、20~30分程度行う。ただし、氷を直接肌に当てないように気を付ける。

  • (C)圧迫して覆う。足首を固定し、受傷した足首をサポートする。

  • (E)最初の48時間はできるだけ足首を心臓の高さより上に上げる。

服薬   イブプロフェンやナプロキセンなどの非ステロイド性抗炎症薬(NSAIDs)は、疼痛や腫脹を抑えるのに役立ちます。腫脹を抑えて疼痛をコントロールすることによって機能を改善するため、麻薬性鎮痛剤よりも軽度の捻挫には適しています。



Nonsurgical treatment 非手術治療

Some sprains will require treatment in addition to the RICE protocol and medications.

Crutches. In most cases, swelling and pain will last from 2 to 3 days. Walking may be difficult during this time and your doctor may recommend that you use crutches as needed.

Immobilization. During the early phase of healing, it is important to support your ankle and protect it from sudden movements. For a Grade 2 sprain, a removable plastic device such as a cast-boot or air stirrup-type brace can provide support. Grade 3 sprains may require a short leg cast or cast-brace for 2 to 3 weeks.


松葉杖   ほとんどの場合、腫脹や疼痛は2~3日続きます。この間は歩行困難な場合があり、必要に応じて松葉杖の使用を推奨する場合があります。


固定   治癒の初期段階では、足首をサポートし、急激な動きから保護することが重要です。グレード2の捻挫の場合は、ギプスブーツや取り外し可能なプラスチック製の装具でサポートできます。グレード3の捻挫では、2~3週間のギプスが必要になることがあります。


Your doctor may encourage you to put some weight on your ankle while it is protected. This can help with healing.

Physical therapy. Rehabilitation exercises are used to prevent stiffness, increase ankle strength, and prevent chronic ankle problems.

  • Early motion.  To prevent stiffness, your doctor or physical therapist will provide you with exercises that involve range-of-motion or controlled movements of your ankle without resistance.

  • Strengthening exercises.  Once you can bear weight without increased pain or swelling, exercises to strengthen the muscles and tendons in the front and back of your leg and foot will be added to your treatment plan. Water exercises may be used if land-based strengthening exercises, such as toe-raising, are too painful. Exercises with resistance are added as tolerated.

  • Proprioception (balance) training.  Poor balance often leads to repeat sprains and ankle instability. A good example of a balance exercise is standing on the affected foot with the opposite foot raised and eyes closed. Balance boards are often used in this stage of rehabilitation.

  • Endurance and agility exercises.  Once you are pain-free, other exercises may be added, such as agility drills. Running in progressively smaller figures-of-8 is excellent for agility and calf and ankle strength. The goal is to increase strength and range of motion as balance improves over time.



理学療法   リハビリ体操は、拘縮予防、足関節の筋力アップ、慢性的な足関節トラブルを予防するために行います。

  • アーリーモーション   拘縮を防ぐために、医師や理学療法士が、足関節が抵抗なくコントロールできる動作や可動域を伴う運動を行います。

  • 強化エクササイズ   疼痛や腫脹の増悪なく、荷重に耐えられるようになったら、足の前後の筋肉や腱を強化する運動を行っていきます。つま先立ちのような陸での強化運動で疼痛を伴う場合は、水中での運動を行うこともあります。抵抗のある運動は、許容範囲内で追加されます。

  • 固有感覚トレーニング   バランスが悪いと、捻挫を繰り返したり、足関節が不安定になることがよくあります。バランス運動の良い例は、患足で目を閉じて片足立ちすることです。リハビリテーションのこの段階では、バランスボードがよく使用されます。

持久力と敏捷性のエクササイズ   痛みがなくなったら、アジリティ・ドリルなどの他のエクササイズを追加することもできます。8の字を徐々に小さくして走ることは、敏捷性とふくらはぎと足関節の筋力を高めるのに優れています。目標は、時間の経過とともにバランスが改善され、強度と可動域が向上することです。


Surgical treatment 手術療法

Surgical treatment for ankle sprains is rare. Surgery is reserved for injuries that fail to respond to nonsurgical treatment, and for patients who experience persistent ankle instability after months of rehabilitation and nonsurgical treatment.




Surgical options may include:

  • Arthroscopy. During arthroscopy, your doctor uses a small camera, called an arthroscope, to look inside your ankle joint. Miniature instruments are used to remove any loose fragments of bone or cartilage, or parts of the ligament that may be caught in the joint.

  • Reconstruction. Your doctor may be able to repair the torn ligament with stitches or sutures. In some cases, he or she will reconstruct the damaged ligament by replacing it with a tissue graft obtained from other ligaments and/or tendons found in the foot and around the ankle.


  • 関節鏡  関節鏡と呼ばれる小さなカメラを使用して、足関節の中を見ます。骨や軟骨、または関節に巻き込まれる可能性のある靭帯の緩んだ断片を除去するために使用します。

  • 再建  断裂した靭帯を縫合して修復します。場合によっては、足関節や周囲にある他の靭帯や腱を採取し、移植して、損傷した靭帯を再建することもあります。



Immobilization. There is typically a period of immobilization following surgery for an ankle sprain. Your doctor may apply a cast or protective boot to protect the repaired or reconstructed ligament. Be sure to follow your doctor's instructions about how long to wear the protective device; if you remove it too soon, a simple misstep can re-tear the fixed ligament.

Rehabilitation. Rehabilitation after surgery involves time and attention to restore strength and range of motion so you can return to pre-injury function. The length of time you can expect to spend recovering depends upon the extent of injury and the amount of surgery that was done. Rehabilitation may take from weeks to months.

固定   足関節捻挫の手術後は、通常、固定する期間があります。修復または再建した靭帯を保護するためにギプスなどを装着します。どのくらいの期間装着するかは、医師の指示に従ってください。

リハビリテーション   手術後のリハビリは、受傷前の機能に戻れるよう、筋力や可動域を回復させるための時間と注意が必要です。回復に要する時間は、損傷程度や手術内容によって異なります。リハビリテーションには数週間から数ヶ月かかることもあります。


Outcomes 治療成績

Outcomes for ankle sprains are generally quite good. With proper treatment, most patients are able to resume their day-to-day activities after a period of time.


Most importantly, successful outcomes are dependent upon patient commitment to rehabilitation exercises. Incomplete rehabilitation is the most common cause of chronic ankle instability after a sprain. If a patient stops doing the strengthening exercises, the injured ligament(s) will weaken and put the patient at risk for continued ankle sprains.




Chronic Ankle Sprains

Once you have sprained your ankle, you may continue to sprain it if the ligaments do not have time to completely heal. It can be hard for patients to tell if a sprain has healed because even an ankle with a chronic tear can be highly functional because overlying tendons help with stability and motion.


If pain continues for more than 4 to 6 weeks, you may have a chronic ankle sprain. Activities that tend to make an already sprained ankle worse include stepping on uneven surfaces and participating in sports that require cutting actions or rolling and twisting of the foot.


Abnormal proprioception—a common complication of ankle sprains—can also lead to repeat sprains. There may be imbalance and muscle weakness that causes a reinjury. If you sprain your ankle over and over again, a chronic situation may persist with instability, a sense of the ankle giving way, and chronic pain. This can also happen if you return to work, sports, or other activities before your ankle heals and is rehabilitated.



The best way to prevent ankle sprains is to maintain good muscle strength, balance, and flexibility. The following precautions will help prevent sprains:

  • Warm up thoroughly before exercise and physical activity

  • Pay careful attention when walking, running, or working on an uneven surface

  • Wear shoes that are made for your activity

  • Slow down or stop activities when you feel pain or fatigue




  • 運動・運動前のウォーミングアップを徹底する

  • 歩いたり、走ったり、凹凸のある場所で作業をする際には注意する

  • アクティビティに合わせた靴を履く

  • 痛みや疲労を感じたときは、活動のペースを落としたり、中止したりする

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