Baseball elbow

Japanese: 野球肘 - やきゅうひじ（英語表記）Baseball elbow

What kind of disability is it?

This is an elbow disorder that occurs when the elbow joint is forced into excessive valgus (bending outward) in a flexed position, mainly during the acceleration phase of the pitching motion, which causes repeated pulling stress on the inside, compressive stress on the outside, and collision and pulling stress on the rear. Epiphyseal line ( Kotsutansen ) During adolescence, before the bones close, baseball elbow occurs due to the underdeveloped bones, cartilage, and muscles, as well as the pitching motion that is unique to the growth period.

At first, the elbow is forced into valgus, causing Ligaments ( Constitution ) The ligament is pulled, causing damage to the epiphyseal line of the ligament itself and its attachment, and then the medial side becomes loose, which increases the compressive stress on the lateral side, causing the humeral head and Radial head ( Toukotto ) This causes damage to the cartilage and bones of the elbow. As this external pathology progresses, the bone cartilage fragments become loose bodies (articular cartilage), and eventually osteoarthritis of the elbow occurs.

Injuries caused by posterior stress are mainly typified by epiphyseal separation caused by repeated pulling on the olecranon by the contraction of the triceps. Bone spurs ( Knowledge ) formation (in bone thorn ( Thorn ) This can also be caused by a loose body from outside getting stuck in this area, which can result in a deformation like that of the bone.

complications

If the damage within the joint progresses, it can become osteoarthritis of the elbow, which can interfere with daily life, so early detection and treatment are important.

How symptoms manifest

The first symptom is pain in any part of the body. At first, there is localized pain only when pitching, and when resting, there is no pain or Fatigue ( Health test ) The pain is usually to a certain extent. Injuries to muscles, tendons, ligaments, and ligament attachments cause sharp pain, while disorders within the joints cause dull pain. As the condition progresses, movement of the elbow joint becomes restricted. Even in the early stages, range of motion may be restricted due to the onset of arthritis, but extension restriction caused by bone and cartilage disorders is an indicator of chronicity and requires attention.

Testing and diagnosis

X-rays are used to check for abnormalities in each part of the bone. On the inside, findings such as separation, segmentation, sclerosis, irregularity, and thickening of the epiphyseal nucleus (bones outside the growth line) may be seen. On the outside, findings such as a clear focus (a lesion that appears as a dark hole), separation, or loss of the capitellum of the humerus may be seen. On the posterior side, findings such as separation, sclerosis, and irregularity of the epiphyseal nucleus of the olecranon may be seen. Loose bodies and osteophytes may be seen on X-rays, but CT scans will show them in more detail. MRI can be used to detect osteochondral changes that are not yet apparent on X-rays or CT images, as well as changes in the bone and cartilage that may be present. Synovial membrane ( Congratulations ) It is a very useful examination because it can also show the condition of the joints, muscles, and ligaments. Furthermore, arthroscopy (endoscopy) allows direct visualization of the lesion, and allows transition to endoscopic surgery such as removal of loose bodies and treatment of osteochondral lesions, so it is also used as a treatment.

Treatment methods

Treatment plans vary depending on the location of the injury, its progression, as well as the patient's age and individual circumstances, but the general rule is early detection and early treatment. Most medial injuries can be cured early with conservative treatment such as cessation of pitching. However, if left untreated at this stage, the lateral injury will progress, so care must be taken.

For external injuries, if the injury is minor, it can be cured by ceasing pitching until the damage is repaired; however, if the osteochondral lesion becomes more severe or a loose body has formed, surgery will be necessary.

Surgical methods include drilling (making holes) in the area where separation or loss has occurred. Bone nail ( Master ) There are grafts, osteochondral grafts, and loose body removal. For posterior disorders, arthroplasty may be performed if there is a large separation of the epiphyseal line of the olecranon.

Prevention measures

Factors that cause baseball elbow during the growth period include underdevelopment of bones, cartilage, and muscles, and immature pitching technique. To prevent and recur, warming up and cooling down before and after pitching, stretching, strength training, and improving pitching form are recommended. In addition, since the main cause is thought to be excessive pitching, it is necessary to limit the number of pitches (50 pitches/day, 300 pitches/week).

Prince Kato

Baseball elbow
Baseball elbow
(Childhood illnesses)

What kind of disability is it?

Baseball elbow is an injury around the elbow joint caused by the repeated motion of throwing a ball. During the series of pitching movements, the inside of the elbow (little finger side) is pulled, the outside (thumb side) is compressed, and the back of the elbow is subjected to a force of impact when the ball is released. Such forces are repeatedly applied to the elbow, causing injury (Figure 31).

During the growth period, cartilage (articular cartilage: the soft tissue that outlines the surface of the joint, growth zone: the cartilage near the joint where the bone grows) is easily damaged, causing breakdowns in those areas. Humerus ( Jowankotsu ) Part or all of the medial growth zone Peeling ( Peeling ) And on the outside of the humerus Osteochondritis dissecans ( Red blood cell ) occurs, and in the rear Olecranon ( Middle school ) Fatigue fractures occur.

How symptoms manifest

The most common symptom is elbow pain when throwing a ball. It rarely causes problems in daily life, but if joint mucus (loose bodies in the joint) develops, it can make it difficult to move the elbow and cause severe pain.

Testing and diagnosis

Diagnosis is possible based on the location of the characteristic pain and X-ray examination. MRI and CT scans may be performed if necessary.

Treatment methods

There are surgical and non-surgical methods, but surgery seems to be rare. Since the injury is caused by throwing too many balls, players should stop throwing until it has healed sufficiently and strengthen the muscles around the elbow and wrist. In cases of osteochondritis dissecans and olecranon stress fractures, surgical treatment may be chosen to speed up recovery. Even if the injury heals, it is extremely important to keep in mind that it is an "elbow injury caused by throwing too much," and to take preventative measures such as limiting the number of pitches and improving form.

What to do if you notice a problem

There are many different conditions that can be classified as "baseball elbow." Do not self-diagnose easily, but be sure to see an orthopedic specialist and have an accurate diagnosis made through X-rays and other tests, and have a treatment plan drawn up. If diagnosis and treatment are not made sooner, the elbow movement may worsen, and you may be left with a lifelong disability, so please be careful.

Shuji Horibe

Figure 31 Mechanism of baseball elbow development
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Figure 31 Mechanism of baseball elbow development

Source: Houken “Sixth Edition Family Medicine Encyclopedia” Information about the Sixth Edition Family Medicine Encyclopedia

Japanese:

どんな障害か

　投球動作の主にアクセレーション期（加速期）に、肘関節が屈曲位で過度の外反（外側に反る）を強制されることにより、内側には引っ張りストレス、外側には圧迫ストレス、後方には衝突や引っ張りストレスが繰り返し加わることによって発生する肘の障害です。とくに、肘の骨端線(こつたんせん)が閉鎖する前の少年期では、骨、軟骨、筋肉が未発達なことと成長期特有の投球動作の関係で野球肘が起こります。

　はじめは、肘の外反が強制されることにより内側の靭帯(じんたい)が引っ張られて、靭帯自体や付着部の骨端線に障害が起こり、次いで内側に緩みが生じたことで外側への圧迫ストレスが強くなり、上腕骨小頭と橈骨頭(とうこっとう)の軟骨、骨の損傷が起こります。この外側の病態が進行すると、骨軟骨片がはがれて遊離体（関節ねずみ）となり、ついには変形性肘関節症(ちゅうかんせつしょう)を併発してしまいます。

　後方にストレスが加わることによって起こる障害は、主に上腕三頭筋の収縮が肘頭を繰り返し引っ張ることによって起こる骨端線の離開に代表されます。その他、骨棘(こつきょく)の形成（骨に刺(とげ)状の変形ができる）や外側からの遊離体がこの部位にはさまることなどによることもあります。

合併症

　関節内の障害は進行すると変形性肘関節症となり、日常生活に支障を来すことになるので、早期発見・早期治療が重要になります。

症状の現れ方

　自覚症状はどの部位の障害も疼痛で始まります。はじめは投球時にのみ局所に疼痛があり、安静時には無痛か倦怠感(けんたいかん)がある程度です。筋肉、腱、靭帯、靭帯付着部の障害では鋭い疼痛、関節内の障害では鈍痛を訴えます。病態が進むと肘関節の運動制限が現れてきます。初期でも関節炎の併発により可動域が制限されることがありますが、骨、軟骨性障害によって現れる伸展制限は慢性化の指標で、注意を要します。

検査と診断

　X線撮影で各部位の骨の異常を調べます。内側は骨端核（成長線の外にある骨）の離開、分節化、硬化、不整、肥厚など、外側は上腕骨小頭の透明巣（黒く抜けて見える病巣）、分離、欠損など、後方は肘頭の骨端核の離開、硬化、不整などの所見が認められることがあります。遊離体や骨棘はX線像でもわかる場合もありますが、CT撮影でより詳細に描き出されます。MRIはX線、CT像でまだ現れていない骨軟骨変化や、滑膜(かつまく)、筋肉、靭帯の状態なども描き出せるので、非常に有用な検査です。さらに、関節鏡検査（内視鏡）は病巣部を直視でき、遊離体摘出術や骨軟骨病変の処置などの鏡視下手術に移行できることから、治療を兼ねて行われています。

治療の方法

　障害部位とその進行程度、さらには年齢や個人の事情によって治療方針は異なりますが、原則は早期発見・早期治療です。内側の障害は、早期であればほとんどが投球中止などの保存療法で治ります。しかし、この段階で放置すると外側の障害が進行することになるので注意を要します。

　外側の障害についても、程度が軽ければ損傷が修復するまで投球を中止することによりよくなりますが、骨軟骨病変の分離が進んだり、遊離体ができてしまった場合などには手術が必要になります。

　手術方法としては分離や欠損を起こしている部位へのドリリング（穴をあける）や骨釘(こつてい)移植、骨軟骨移植、遊離体摘出などがあります。後方の障害については、肘頭の骨端線の離開が大きい場合に接合術の手術を行うことがあります。

予防対策

　成長期の野球肘の発生要因としては、骨、軟骨、筋肉の未発達、投球技術の未熟などがあげられます。予防・再発予防として、投球前後のウォーミングアップとクールダウン、ストレッチング、筋力トレーニング、投球フォームの改善などを行います。また、最大の要因は投球過多と考えられるので、投球数の制限（50球／日、300球／週以内）を行う必要があります。

加藤　公

野球肘
やきゅうひじ
Baseball elbow
(子どもの病気)

どんな障害か

　野球肘とは、ボールを投げる動作が繰り返されることにより生じる肘関節周囲の故障です。一連の投球動作において、肘の内側（小指側）は引っ張られ、外側（親指側）は圧迫が加わり、肘の後ろにはボールリリースの際にぶつかる力が加わります。そのような力が繰り返し肘に加わり、故障が発生します（図31）。

　成長期では、軟骨（関節軟骨：関節部の表面の輪郭をなす軟らかい組織、成長軟骨帯：関節近くにある軟骨で骨が伸びる部位）が傷みやすいため、その部位に故障を生じます。内側では、上腕骨(じょうわんこつ)内側の成長軟骨帯の一部または全部が剥離(はくり)し、上腕骨外側には離断性骨軟骨炎(りだんせいこつなんこつえん)が生じ、後方では肘頭(ちゅうとう)に疲労骨折が生じます。

症状の現れ方

　ボールを投げる際の肘の痛みが特徴的です。普通の生活には困ることはほとんどないのですが、関節ねずみ（関節内遊離体）ができると、肘が動きにくくなったり、激痛が走ったりすることがあります。

検査と診断

　特徴的な痛みの部位やX線検査で診断は可能です。必要に応じて、MRI検査やCT検査を行うこともあります。

治療の方法

　手術による方法と手術によらない方法がありますが、手術が必要なものは少ないようです。ボールの投げすぎによる故障ですので、十分に治るまで投げることをやめ、肘や手関節周囲の筋力アップを行います。離断性骨軟骨炎や肘頭疲労骨折では、早期復帰目的で外科的治療を選択する場合もあります。治っても、“投げすぎにより生じた肘の故障”ということを念頭におき、投球数の制限やフォームの改良などの予防対策も極めて重要です。