Dados do Trabalho

Título

Humeral Shaft Fracture Secondary to Muscular Violence

Introdução e Objetivo

Humeral shaft fractures occur mainly due to direct trauma or stress lesion. Occasionally, these fractures are attributed to muscular violence, a rare phenomenon well described in the literature. This injury has been associated with intense arm movement such as throwing objects, javelins, hand grenades, softballs, and baseballs, especially in adolescents. The biomechanics of pitching leads to a great torsional force into the humerus caused by the external and internal rotation of the elbow and shoulder. This force, once exacerbated in a full-power pitch, can cause a humeral fracture, especially when a wrong technique is applied during the pitching movement. We present a case of an amateur baseball player who had a displaced spiral fracture of the distal third of the right humerus secondary to muscular violence.

Casuística e Método

A 19-year-old recreational baseball male athlete sustained a spontaneous injury to his throwing arm while pitching with full power in a baseball game. The patient denied a history of previous pain and trauma to the affected arm. Radiographs demonstrated a displaced spiral fracture of the distal third of the right humerus diaphysis.

Resultados

The patient underwent an open reduction with plate placement and screw fixation with no surgical complications. At the time of 4 months of follow-up, the patient had returned to his routine of practice still under physiotherapy care, working on arm strength and motion for future prevention of lesions.

Discussão

To throw an object, the arm executes a violent forward and upward sequential movements going from external rotation position to internal. The humeral axial torque peaks when the shoulder and elbow are brought forward and whipped from extreme external to internal rotation, which is when electromyographic studies demonstrate the time fractures may occur. The humerus is not at risk of fracture in a normal throw, but it’s hypothesized that in a faulty throwing style associated with muscular imbalance can lead to fracture. Throwing fractures are mainly spiral external rotation fractures in the mid distal humerus. Fractures of the proximal half of the humerus are much less common and typically occur in early adolescence.
Common causes of humeral fracture include violent muscle action, faulty throwing style, fatigue, excessive torque, or even a combination of these factors. Branch case series showed that pitchers described arm pain at point of fracture 75% of the time before the fracture, suggesting that fractures in the humerus can be a consequence of stress and not only of an acute cause. For this reason, we could argue that individuals prone to humeral fracture can be organized into two groups: 1. young patients with no arm pain that makes an exceptionally hard throw, caused by muscular violence; 2. Patients with a pain prodrome before the event, which has a stress factor.
Recreational throwers are at higher risk than professional pitchers. These pro players experience bone remodeling to repetitive stresses producing physiological adaptation (cortical hypertrophy) increasing bone sheer value. To avoid humeral fractures in casual athletes a preparation program for at least 3 months prior to the season is advised.

Conclusão

Therefore, the importance of this paper is to shed light to muscular violence as being a possible cause of distal humeral shaft fractures. In this way, physicians can be more prepared when dealing with similar throwing situations, which allows them to better prevent and treat these injuries, so patients can be well cared for and return to their throwing routine.