The forearm is made up of 2 bones – the Radius and the Ulna. Both bones participate in movement at both the elbow and wrist, and are largely covered in the bulky muscles of the forearm. The two bones are joined along their length by a tough fibrous sheet, called the interosseous membrane, which allows the 2 bones to rotate around each other whilst keeping them bound together. In addition, there are small joints between the 2 bones at each end – the radio-ulnar joints.

Injuries to the forearm may affect either bone individually, or both bones together; the wrist or elbow joints can also be affected, as well as the small joints between the radius and ulna, most commonly at the wrist end (the DRUJ – distal radio-ulna joint).

Due to these complexities this injury is often not simple, and most commonly surgery is required to restore the complex function of the forearm.

Causes

A broken forearm is a fairly common injury, and usually results from a fall. It is frequently seen after falls playing sport, and typically involves varying amounts of compression force (ie falling with the hand outstretched) combined with bending or twisting. Sometimes a heavy direct blow will break the forearm – the most common example of this is the so-called “nightstick” injury – where the ulna is struck by something heavy (a nightstick is a type of police baton). Forearm injuries are also seen after high energy injuries such as motor vehicle accidents, often part of more extensive injuries.

Symptoms

A broken forearm causes pain, swelling and bruising over the forearm. With a simple ulna fracture, function of the upper limb may be painful but possible. In most both bone fractures however, all movement of the hand and forearm is extremely painful, and patients typically hold the arm still using the opposite hand. In more severe cases the deformity is obvious, and open fractures are sometimes seen, where the broken bone ends have penetrated the skin. In these severe cases, nerve injuries can occur leading to numbness in the hand, and weakness of some hand function.

Diagnosis

To diagnose a broken forearm, your doctor will ask you questions about how you injured the area, and will examine your upper limb carefully, including examination of the hand. Simple x-rays will almost always show this fracture, but at times a CT scan may help as well.

Treatment

The majority of forearm fractures that occur require surgery to achieve the best outcome. This restores the bony anatomy, allowing restoration of joint function at both ends of the bones, and provided stability is achieved through fixation rehabilitation can commence early.  Occasionally, single bone fractures can be treated without surgery, but this is uncommon.

Surgery

The aim of surgery is to replace the bone ends back to their original position, and hold them there with plates and screws. This is critical to allow proper function of the joints at both ends of the bones, and thus restore elbow and wrist function. Surgery is done under a general anaesthetic, usually with a separate incision for each bone.

One advantage of surgery is that mobility of the shoulder, elbow and hand can usually be started almost immediately after surgery, and so return to function is typically quicker than non-operative treatment. The plates and screws are generally left in permanently, unless they cause irritation which is uncommon.

Rehabilitation / return to function

This injury typically has a very good outlook, provided the fracture ends are returned to a near anatomic position. Most people are back to normal daily activities by 6 weeks, but fracture healing may take 12 weeks meaning that heavy loading of the arm cannot occur until at least that point. Sports activities are therefore typically ill advised for at least 3-4 months after injury. Complications are uncommon and rarely serious, but nerve injury can occur either at the time of injury, or rarely during surgery. The majority of nerve injuries recover well, but result in numbness or some muscle weakness for weeks or months. Perhaps the most common problem after forearm fractures is joint stiffness, and particularly rotation of the forearm. This can usually be overcome with exercises and physiotherapy once pain allows.

Forearm fracture X-ray

Forearm fracture – plate and screws