our website is for educational purposes only.  the information provided is not a substitution for seeing a medical doctor.  for the treatment of a medical condition, see your doctor.  we update the site frequently but medicine also changes frequently.  thus the information on this site may not be current or accurate. 

related talks: broken shoulder (proximal humerus fracture); shoulder separation (AC joint); shoulder dislocationbroken collar bone (clavicle fracture); shoulder instability (torn labrum); broken elbow

What is a Broken Arm ("Midshaft Humerus Fracture")?

A Broken Arm is also called a Midshaft Humerus Fracture (the arm bone is called the humerus and the break occurs in the middle portion of the bone).

This type of fracture occurs in people of all ages and can occur after a traumatic event, like a high speed motor vehicle accident, or after a simple slip and fall.  

mid-shaft humerus fracture broken arm banana fall

There is an important nerve, called the Radial Nerve, that travels along the arm bone.  This nerve provides sensation to the back of your arm, and it also gives strength to your triceps muscle and a the muscles that extend your fingers and wrist.  This nerve can get injured (about 20% of the time) when the arm breaks because its in such close contact with the bone.  Although the vast majority of these nerve injuries will completely recover, it is important for your doctor to identify when this injury occurs and to watch carefully for nerve recovery.  

radial nerve palsy after midshaft humerus fracture

How is a Broken Arm ("Midshaft Humerus Fracture") diagnosed?

People with a broken arm come in after a traumatic event complaining of significant pain and swelling in the affected arm.  Sometimes you know the arm is broken just by looking at it because theres an abnormal bend.

A doctor that is suspicious for this injury will order x-rays to confirmed the diagnosis.  Its important to get x-rays of the shoulder and elbow joint to make sure there arent other injuries in addition to the broken arm bone.  

midshaft humerus fracture xray broken arm x-ray

Remember that about 20% of people with this injury also experience numbness on the back of their hand and possibly weakness in the arm as well.  A doctor will test for sensation and muscle strength (like the triceps, and wrist extensor muscles by asking someone to straighten their arm and extend their wrist and fingers).

How is a Broken Arm ("Midshaft Humerus Fracture") treated?

Treatment is based on the severity of injury.

The majority of these injuries will heal well without surgery (even ones that look pretty bad on x-ray).  

Non-surgical treatment consists of protecting the arm with a special splint (called a "Coaptation splint") for about 7-10 days.  This splint is molded to realign the broken bone, so that it heals in the correct position.  

After 7-10 days, the bone has begun its early stages of healing and its a little more stable.  The arm is placed into a brace called a "Sarmiento Brace" which wraps tightly around the arm, holding everything into place, while allowing someone to gradually start moving the arm.  

There are of course some indications to fix these injuries with surgery.  If the brace fails to hold the broken arm in good alignment (the arm bone bends more than 10 degrees), or if the bone fails to heal within the brace (doctors typically give the bone about 3 months to show signs of healing before they recommend surgery). In these cases, where nonsurgical treatment fails, surgery is needed to provide better stability to allow healing.  

A polytrauma patient (someone with multiple broken bones) usually has this fixed to allow for a faster rehab. 

Also a fracture at the very top of the humerus (a proximal 1/3 humerus fracture) sometimes needs to be fixed with surgery because its so close to the shoulder that the normal brace cannot reach up that high to hold the bone stable. 

If surgery is performed, there are multiple ways to do it.  This includes using an intramedullary nail (goes down the center of the humerus), or a plate with screws.  A plate has been shown in many studies to have less risk for future shoulder impingement, reoperation, and nonunion (failure to heal).   

What is the outcome?

The arm bone will usually heal with bracing alone (95% healing rate).  Most bones actually heal with a slight bend, but 80% of these bends are less than 10 degrees (which rarely affects arm function).  However, about 10% of people report some lost motion, but even if motion is lost its typically minimal.   

Sometimes it takes a few months to regain the strength to return to normal activities, even if everything goes perfectly as planned.  Overall most function is regained, however some reports say that people report mild but persistent activity limitations.

An injury to your nerves (specifically the brachial plexus) or a radial nerve palsy alone isn’t an indication to get surgery because most will heal with time.  Radial nerve injuries are often seen with a broken arm because the radial nerve runs closely along the bone especially between 14-21 cm from the elbow.  Injury to the nerve occurs in about 20% of these fractures.  Injury to the nerve usually occurs from traction (pulling) on the nerve.  Overall 90% will resolve by 3-4 months although we like to get a EMG (this test the muscles to see if they are receiving signals from the nerve) at 6 weeks if there haven’t been signs of improvement.   


1) Heineman DJ et al. Plate fixation or intramedullary fixation of humeral shaft fractures. Acta Orthop. 2010; 81: 216-23. full article

2) Sarmiento A et al. Functional bracing for the treatment of fractures of the humeral diaphysis. JBJS 2000; 82: 478-86. full article.

3) Tingstad EM et al. Effect of immediate weight bearing on plated fractures of the humeral shaft. J Trauma. 2000; 49: 278-80. full article

4) Carroll EA et al. Management of humeral shaft fractures. JAAOS 2012; 20: 423-33. full article. treatment review.

5) Ekholm R et al. Outcome after closed functional treatment of humeral shaft fractures. JOT 2006; 20: 591-595. full article. concerns about nonop function.

6) Klenerman L. Fractures of the shaft of the humerus. JBJS 1966; 48: 105-11. full article.  reduction criteria.