Orthopaedic Conditons & Treatments

Forearm Fracture, Causes and Symptoms

It may not seem like it, but your forearm – the length of arm between your wrist and elbow – is made up of two bones, called the radius and the ulna. If your arms are hanging at your sides with your palms facing back, the radius is the bone facing toward your body, and the ulna is the bone facing away from it. Most instances of forearm fracture involve the breaking of both of these bones, but if you break either of them, you are considered to have fractured your forearm. If the radius and the ulna are not functioning properly, your wrist and elbow cannot move correctly.

If you think you may have fractured your forearm, it is imperative that you seek medical attention. Forearm fractures can lead to complications that have the potential to cause lifelong disability. Forearm fractures are notoriously unstable – even when they are put into a splint or a cast and made immobile. The bone must be stabilized in order for it to mend correctly. And the bone must mend correctly in order for you to regain your full range of motion in your elbow and wrist. The forearm is necessary in order for you to be able to twist objects – such as a light bulb, bottle cap or screwdriver. The radius rotating around the ulna makes your wrist’s twisting motion. Forearm health is also necessary for extending and bending the wrist and the elbow.

Anatomy of the Forearm
The two bones of the forearm have reverse shapes. The ulna starts large where it meets the elbow (it is the bone that makes up the elbow’s pointy end) and tapers small by the time it reaches the wrist. The radius starts large at the wrist and tapers down in size toward the elbow. The forearm consists of the following:

  • The radius (the forearm bone on the side of the thumb)
  • The ulna (the forearm bone on the side away from the thumb)
  • The wrist joint (at the wrist joint, the distal ends of the radius and ulna articulate with the carpal bones of the hand)
  • The elbow joint (the radius and ulna articulate with the upper arm bone – known as the humerus – at the elbow joint)

Types of Forearm Fractures
Forearm Fractures can be divided into five main types:

  • Radial shaft fracture – If only the radius is fractured at the shaft, not at the wrist or the elbow, then you have a radial shaft fracture. This type of forearm fracture is rare. In most cases, if you have a radius shaft fracture, your ulnar shaft is also fractured. If it is only the radius that is fractured, there is a high likelihood that the fracture is near or at the wrist.
  • Ulnar shaft fracture – The ulnar shaft fracture has been nicknamed the “nightstick fracture,” because this injury is most frequently sustained when an object has hit the forearm or the forearm has hit an object. Because the ulna is on the outside of your forearm, it is the bone that you naturally protect yourself with.
  • Fracture of both bones – If both of your forearm bones are broken, you are very likely going to need surgery. The bones do not stabilize well on their own – even if put in a cast.
  • Distal radius fracture – This is a fracture of the radius at the wrist – the most common break when it is only the radius that fractures. This is a common injury in general. The radius is the arm bone that is broken most.
  • Elbow (olecranon fracture) – The olecranon is the elbow point, which is formed by the ulna. The ulna does not have much protection at this point – just skin. If you are hit on your bent elbow or fall on it, it can be fractured.

Causes of Forearm Fractures
A forearm fracture is generally the result of a fall or a blow to the arm. The following are the causes of forearm fractures:

  • Fall on outstretched hand – When you catch yourself with one hand after a fall, you have put a lot of pressure on your forearm. If the fall is significant, or if your bones are weakened, you are vulnerable to forearm fracture. Distal radius fractures are commonly caused this way. You can also fracture both forearm bones this way.
  • Blow to the arm – If you receive a blow to your forearm, you may sustain an ulnar shaft fracture. And if you receive a blow to your elbow, you may sustain an olecranon fracture. You can also fracture both the ulna and the radius this way.    

Symptoms of Forearm Fractures
Different types of forearm fracture have different symptoms, as they occur in different locations. The symptoms of forearm bone shaft fractures are generalizable, though: You will feel extreme pain immediately. You arm may look shorter than your uninjured arm, and crooked – especially if both the radius and the ulna have been fractured. Your arm will not have the strength to support itself; you will have to do so with the hand of your uninjured arm. The arm will swell and bruise. You will be unable to rotate it. Additionally, the wrist and the fingers may become weak and numb (though this is not likely). If you fracture your distal radius, your wrist will be in severe pain. It will be tender and it will bruise and swell. The wrist may hang limply. If your fracture your elbow, you will feel pain. You will be unable to extend your arm. Your elbow will swell and bruise. Some of your fingers will likely feel numb and moving the elbow will be painful.  

The following are common forearm fracture symptoms:

  • Pain
  • Tenderness
  • Swelling
  • Bruising
  • Numbness

The symptoms of forearm fracture may be mistaken for the symptoms of other medical conditions (tennis elbow, tendonitis, etc.). Make sure you consult a doctor in order to determine if you have a forearm fracture and get the appropriate treatment. 

The multidisciplinary team of orthopaedic experts at North Shore-LIJ Orthopaedic Institute's Trauma Services in New York treats Forearm Fractures as well as a broad range of conditions that affect the bones within the body.

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