A humerus fracture is a break in the upper arm bone, the single long bone that runs from your shoulder to your elbow. It’s one of the more common fractures in adults, occurring most often in people over 40 and roughly 1.6 times more frequently in women than men. Depending on where the bone breaks, a humerus fracture can range from a minor crack that heals in a sling to a complex injury requiring surgery.
Where the Humerus Breaks
The humerus has three distinct regions, and a fracture in each one behaves differently and carries its own set of risks.
The proximal humerus is the top of the bone, near the shoulder joint. This is the most common fracture site, especially in older adults with weaker bone density. The proximal humerus has several important structures packed close together: two bony bumps called tuberosities where rotator cuff muscles attach, the rounded head that fits into the shoulder socket, and the shaft just below. A fracture here can involve one or more of these segments.
The humeral shaft is the long middle section of the bone. It’s cylindrical near the top and gradually flattens into a more triangular shape as it approaches the elbow. The radial nerve, which controls your ability to extend your wrist and fingers, wraps closely around this part of the bone, making it vulnerable during a break.
The distal humerus is the lower end near the elbow. Fractures here are especially common in children. Supracondylar fractures, which occur just above the elbow joint, account for about 60% of all pediatric elbow fractures.
How These Fractures Happen
The cause depends heavily on age. In younger adults and children, humerus fractures typically result from high-energy injuries like car accidents, sports collisions, or falls from height. Extension-type fractures near the elbow, the most common pattern in kids, happen from falling onto an outstretched hand.
In older adults, particularly women over 65, a simple fall from standing height is often enough to break the proximal humerus. Weakened bone density turns an otherwise minor fall into a fracture. The 65-to-90 age group accounts for nearly half of all humeral shaft fractures recorded in the U.S. between 2017 and 2022.
Symptoms and Complications to Watch For
The immediate signs are what you’d expect from any broken bone: sharp pain, swelling, bruising, and difficulty moving the arm. With proximal fractures, the bruising often spreads down the arm and into the chest wall over the first few days, which can look alarming but is normal.
The more important concern is nerve damage. Between 7% and 17% of humeral shaft fractures injure the radial nerve, which can cause a condition called wrist drop, where you can’t lift your hand at the wrist or straighten your fingers. Fractures in the middle and lower third of the shaft, particularly spiral and transverse patterns, carry the highest risk. Most of these nerve injuries recover on their own over weeks to months, but they need to be identified early.
For complex proximal fractures, especially those involving a dislocation, there’s a risk that the blood supply to the top of the bone gets cut off. When that happens, the bone tissue can die, a complication called avascular necrosis. In one study of fracture-dislocations, 33% of patients developed this problem. Delayed surgery dramatically increased the risk: every patient who had late surgery developed avascular necrosis, compared to 20% of those treated early. Poor-quality fracture reduction also played a major role, with 45% of patients who had suboptimal realignment developing the condition versus 10% of those with anatomical restoration.
How Fractures Are Classified
For proximal humerus fractures, doctors use a system that counts how many bone segments have shifted out of place. A segment is considered displaced if it has moved more than 1 centimeter or tilted more than 45 degrees. The four possible segments are the greater tuberosity, lesser tuberosity, the articular surface (the ball of the shoulder joint), and the shaft.
A one-part fracture means the bone is cracked but nothing has shifted significantly. These are the most common and the easiest to treat. A two-part fracture has one displaced segment. A three-part fracture has two displaced segments, which creates a rotational deformity that makes the shoulder unstable. A four-part fracture means all segments have shifted apart. This is the most severe pattern and carries the highest risk of losing blood supply to the humeral head.
When Surgery Is Needed
Most proximal humerus fractures can be treated without surgery. The general thresholds for nonsurgical care are: the tuberosities haven’t shifted more than 5 millimeters, and the main bone segments haven’t displaced more than 1 centimeter or angled beyond 45 degrees. If these criteria are met, a sling and gradual rehabilitation are usually sufficient.
Surgery becomes necessary when bone fragments are significantly displaced, when the fracture pattern is unstable, or when there’s an associated injury to blood vessels. Specific red flags include tuberosity displacement greater than 5 millimeters (which can block shoulder movement), complete displacement of the surgical neck, and large deformities in the bone’s alignment.
The type of surgery depends on whether the fracture can be pieced back together. If the fragments can be reassembled and the blood supply is intact, surgeons use plates and screws to hold everything in position while it heals. If the fracture involves a significant split through the joint surface or multiple fragments that can’t be reconstructed, particularly if the blood supply is gone, a partial or total shoulder replacement may be recommended instead. Factors like age, bone quality, overall health, and whether you can participate in the rehabilitation process all influence the decision.
Recovery and Rehabilitation Timeline
Full recovery from a humerus fracture takes several weeks to several months, depending on the location, severity, and whether surgery was involved. The rehabilitation process follows a predictable sequence designed to protect the healing bone while gradually restoring movement and strength.
Weeks 1 Through 4
Your arm stays in a sling for at least three weeks. During this phase, the focus is on gentle passive motion, meaning a therapist or your other hand moves the injured arm rather than the muscles around the fracture doing the work. Pendulum exercises, where you lean forward and let the arm swing gently, help prevent the shoulder from stiffening without putting stress on the healing bone. You’ll remove the sling several times a day for exercises and basic activities like eating and dressing.
Weeks 4 Through 8
The goal shifts to restoring full passive range of motion and introducing assisted active movement. You’ll start using the muscles around the shoulder with some support, progressing to unassisted active motion around the six-week mark. This is a critical transition period where pushing too hard can compromise healing, but not moving enough leads to lasting stiffness.
Weeks 8 Through 12 and Beyond
Once the bone has healed enough to tolerate load, strengthening exercises begin. This phase focuses on rebuilding the rotator cuff and shoulder blade muscles that have weakened during immobilization. Full shoulder range of motion is the goal before starting resistance work. For many people, returning to full activity takes three to four months, though complex fractures or those requiring shoulder replacement may take longer.
What Affects Your Outcome
Several factors influence how well a humerus fracture heals. Fractures that stay well-aligned, whether through bracing or surgical fixation, have significantly better outcomes. Age and bone quality matter, but they don’t determine the result on their own. In one study, factors like gender, age over 65, and multiple health conditions did not independently increase the risk of complications or the need for additional surgery.
The timing of treatment matters most for complex injuries. For fracture-dislocations of the proximal humerus, early surgery is strongly associated with better results. Patients treated early had a fivefold lower risk of losing blood supply to the bone compared to those whose surgery was delayed. The quality of the repair also played a significant role, with anatomical reduction cutting the rate of bone death from 45% down to 10%.
For nerve injuries associated with shaft fractures, most radial nerve palsies recover spontaneously. Your doctor will typically monitor recovery for several months before considering surgical exploration of the nerve.