A proximal humerus fracture is a break in the upper part of your arm bone, right near the shoulder joint. It’s the third most common fracture in women over 50 and accounts for 5 to 6 percent of all adult fractures. Most happen when an older person falls and catches themselves on an outstretched hand, though younger people can get them too from higher-force injuries like car accidents.
Where Exactly the Break Happens
The “proximal” part of the humerus is the top end, the part that forms the ball in your shoulder’s ball-and-socket joint. This region has four distinct segments that matter when doctors assess the fracture: the rounded head (the “ball”), the greater tuberosity (a bony bump on the outer side where rotator cuff muscles attach), the lesser tuberosity (a smaller bump on the front), and the shaft just below these structures. The junction between the tuberosities and the shaft is called the surgical neck, named specifically because it breaks so often.
Understanding these four segments matters because the number of segments involved, and how far they’ve shifted out of place, determines how serious the fracture is and what treatment looks like.
How These Fractures Are Classified
Doctors use a system developed by orthopedic surgeon Charles Neer to categorize proximal humerus fractures by severity. A segment counts as “displaced” if it has shifted more than 1 centimeter or tilted more than 45 degrees from its normal position.
- One-part fracture: The bone is cracked, but no segment has shifted significantly. This is the most common type and the easiest to treat.
- Two-part fracture: One segment has displaced. It could be either tuberosity, or the break could run through the surgical neck or anatomical neck.
- Three-part fracture: One tuberosity is displaced along with a surgical neck fracture, pulling the remaining attached tuberosity into a rotational deformity.
- Four-part fracture: All four segments have displaced. The humeral head typically shifts sideways and loses contact with the shoulder socket entirely.
The higher the number, the more complex the injury and the more likely surgery becomes necessary.
Who Gets Them and Why
These fractures follow a bimodal pattern, meaning they cluster in two very different groups. The largest group is adults over 65 with weakened bones from osteoporosis or osteopenia. For them, a simple fall from standing height is enough to cause a break. When a fracture results from this kind of low-energy impact in someone with bone loss, it’s classified as a fragility fracture.
The second group is younger adults who experience high-energy trauma: car crashes, motorcycle accidents, or serious sports injuries. These tend to produce more severe, multi-fragment fracture patterns. Less common causes include violent muscle contractions during seizures, electrical shock, or a direct blow to the shoulder.
Interestingly, compared to hip fractures (which mostly happen indoors in people over 80), about 41 percent of proximal humerus fractures occur outdoors and at somewhat younger ages, suggesting a more physically active population.
Symptoms After the Injury
The most obvious sign is immediate, intense pain in the upper arm and shoulder after a fall or impact. You’ll likely notice significant swelling around the shoulder, and bruising that can spread dramatically over the following days, sometimes tracking down the arm, across the chest, or along the side of the body. Moving the arm becomes extremely painful, and you may instinctively hold it close to your body for protection.
In the emergency department, doctors will check nerve and blood vessel function around the injury, paying particular attention to the axillary nerve, which runs close to the surgical neck and is vulnerable during these fractures. They’ll test for sensation on the outer part of your shoulder and your ability to contract the deltoid muscle.
How Doctors Confirm the Diagnosis
Standard X-rays are the first step. A full series typically includes views from the front (with the arm rotated internally and externally), a scapular Y view (taken from the side), and an axillary view (taken from below the armpit looking up). Together, these angles reveal the fracture pattern and whether any segments have shifted. If there’s concern about a shoulder dislocation accompanying the fracture, the scapular Y and axillary views become especially important.
For more complex fractures, particularly when surgery is being considered, a CT scan provides a detailed three-dimensional picture. This helps surgeons understand exactly how many fragments exist, how far they’ve displaced, and what approach will work best for repair.
Non-Surgical Treatment
The good news is that 65 to 85 percent of proximal humerus fractures are treated without surgery. Most one-part fractures and many minimally displaced two-part fractures heal well on their own because the bone fragments haven’t shifted far enough to cause problems.
The standard approach is a sling to immobilize the arm, followed by early and progressive physical therapy. “Early” is the key word here. Keeping the shoulder completely still for more than two weeks increases the risk of lasting stiffness. Research on patients with valgus impacted fractures (a specific pattern where the bone compresses inward) found that about 81 percent achieved good or excellent outcomes with non-surgical management alone.
When Surgery Is Needed
Surgery becomes the better option for fractures with significant displacement, multiple fragments, or disruption of the joint surface. The choice of procedure depends on the fracture pattern, bone quality, the condition of the rotator cuff, and how active you are.
For younger patients with good bone density, internal fixation using plates and screws is often the approach. The surgeon repositions the bone fragments and holds them together with hardware while they heal. More severe fractures in younger patients, including four-part fractures, head-splitting fractures, or those with significant damage to the joint surface, may require a partial shoulder replacement, where the ball of the joint is replaced with a metal implant.
For older patients, especially those with poor bone quality or existing rotator cuff damage, a reverse total shoulder replacement has become an increasingly valuable option. This device reverses the normal anatomy of the shoulder, placing the ball on the socket side and the socket on the arm side, which allows the deltoid muscle to compensate for a weak or damaged rotator cuff. When the greater tuberosity is too shattered to reconstruct and the cuff muscles have already thinned, this approach often produces better functional results than trying to piece the bone back together.
Recovery and Rehabilitation
Whether you’re treated with or without surgery, rehabilitation follows a gradual progression designed to restore movement without stressing the healing bone.
During the first four weeks after surgery, the focus is entirely on gentle, passive range of motion. A therapist moves your arm for you while your muscles stay relaxed. This prevents the shoulder capsule from scarring down while the fracture begins to knit together. Starting around weeks four through eight, you begin assisting the movement yourself and eventually progress to moving the arm on your own. Light isometric exercises (contracting muscles without moving the joint) start during this phase.
True strengthening begins at roughly eight to twelve weeks, once the bone has healed enough to tolerate resistance. Full recovery takes several months, and most people notice gradual improvement in strength and range of motion continuing well past the three-month mark. Non-surgical patients often start rehabilitation sooner, but the overall arc of recovery is similar.
Potential Complications
Stiffness is the most common issue, particularly if rehabilitation starts too late or progresses too slowly. The shoulder joint is prone to developing adhesions (internal scar tissue) when immobilized for extended periods.
Avascular necrosis, where the blood supply to the humeral head is disrupted and the bone tissue dies, is a more serious concern with complex fractures. The risk climbs with severity: roughly 11 percent of three-part fractures and 17 percent of four-part fractures develop this complication after surgery. When the fracture also involves a dislocation, the rate jumps sharply, reaching 60 percent for three-part fracture-dislocations. Head-splitting fractures carry the highest risk. Avascular necrosis can lead to collapse of the humeral head over time, potentially requiring a later shoulder replacement.
Nerve injury, hardware failure, infection, and nonunion (the bone failing to heal) are less common but possible, particularly with surgical treatment. Older patients with osteoporosis face an additional challenge: the weakened bone may not hold screws well, which can lead to hardware loosening.