Humerus Fracture

A humerus fracture is the medical term for a break in the bone of the upper arm. The humerus is the long bone that sits between the shoulder and the elbow. 

Humeral fractures can be classified into three types, depending on which part of the bone is broken. A proximal humerus fracture is when the bone is broken at or near the top, by the shoulder. Mid-shaft humeral fractures, aka humeral shaft fracture or diaphyseal humerus fractures, are a break somewhere in the middle section of the bone. Distal humerus fractures are where the bone is broken near the elbow.

Here we will focus on fractures in the long, middle section of the upper arm – humeral shaft fractures. Injuries at the top of the shoulder are covered in the proximal humerus fracture section.

Approximately 3-5% of all broken bones are midshaft humeral fractures. They tend to affect young males (20-30’s) who have experienced a high-energy injury and elderly females (60-70’s) with low-energy injuries.

Here we will look at the common causes of midshaft humerus fractures, the different types and how they are classified, classic symptoms, how they are diagnosed, the different treatment options both surgical and non-surgical, the recovery process and possible complications.

The mid-shaft region of the humerus is the long, thin part of the bone. The top part is cylindrical in shape and as it runs down towards the elbow it becomes narrower and more prism shaped. The back surface of the shaft of humerus is larger than the front.

The shaft of humerus can be divided into thirds, the proximal (upper third), middle (mid third) and distal (lower third).

Midshaft humerus fractures are usually the result of:

1) A Fall: the most common cause of a midshaft humeral fracture, particularly in the elderly, is a simple fall. Occasionally it may be caused by falling onto an outstretched hand when the arm is abducted – out to the side

2) A Direct Blow: high energy force to the upper arm often causes a transverse fracture

3) Torsion: Forceful twisting of the upper arm can lead to a spiral fracture. Long, spiral humeral fractures in children should be carefully examined as they may indicate abuse

4) Bone Disease: Metastatic breast cancer can cause spontaneous fractures here

Midshaft humeral fractures can be classified into different types depending on the location and direction of the break and the associated damage:

1. Location

Proximal Third: 30% of humeral fractures occur in the top third region

Middle Third: 60% of mid shaft humerus fractures occur in the middle portion

Distal Third: 10% of humeral shaft fracture occur in the lower third

2. Fracture Pattern

Transverse Fracture: Where the line of the fracture runs perpendicular to the bone shaft i.e. horizontally in the humerus

Oblique Fracture: where the fracture line is angled

Spiral Fracture: where there is a spiral-shaped fracture line usually due to twisting of the bone

Comminuted Fracture: where the bone breaks into several pieces

Segmental Fracture: Where there are at least two fracture lines that together isolate a section of bone

3. Degree of Displacement

A displaced humerus fracture is where the bone fragments of the shaft do not line up normally. A non-displaced fracture is where normal alignment is maintained despite the fracture line.

4. Soft Tissue Damage

Open Fractures: This is where the skin over the fracture has been broken, typically by the broken bone puncturing through the skin from the inside, but it could also be from a blow to the shoulder cutting through the skin and muscle. Around 2-10% of humeral shaft fractures are open.

Closed Fractures: This is where the skin remains unbroken - the opposite of an open fracture.

5. Pathological Fracture

This type of fracture is where the bone has broken due to a disease that has weakened the bone such as metastases. With pathological fractures, there may not have been a specific incident that caused the injury, the midshaft humerus fracture may have occurred spontaneously.

Whichever part of the bone is broken, a midshaft humerus fracture will typically cause:

Pain: There is usually severe, ongoing pain associated with the fracture 

Restricted Arm Movement: Shoulder and arm movement tends to be extremely painful so people with a midshaft humerus fracture are often unwilling to move their arm. There is often weakness throughout the whole arm including the wrist and hand

Swelling & Bruising: There will be significant swelling and bruising in the upper arm which may extend all the way down to the hand. The swelling normally comes on fairly rapidly due to soft tissue damage and bleeding in the surrounding area

Crepitus: If the pieces of broken bone rub against each other when you move your arm you may notice a grating or grinding sensation

Deformity: If the fracture is displaced, there may be an obvious deformity of the upper arm e.g. the arm may appear shorter than normal if the bone at the fracture site has overlapped

Bleeding: If it is an open fracture where the bone has pierced through the skin, there will be bleeding. 

Altered Sensation: If there is nerve damage associated with the humerus fracture, then there will be altered sensation such as pins and needles or numbness below the fracture site. Normal movement at the wrist and hand may also be affected. Radial nerve damage is common with humeral shaft fractures

Diagnosing Humeral Shaft Fractures

If you doctor suspects a midshaft humerus fracture you will be sent for x-rays. X-rays will be taken in different directions, usually from front to back (AP) and from the side (lateral), and both the shoulder and elbow joints should be evaluated for any damage.

X-rays help the doctor to see where the fracture is, what type of fracture it is, any associated damage and the severity of the injury so that they can plan the best course of treatment.

Treatment for humerus fractures will vary slightly depending on the location and severity of the fracture, but in most cases, surgery is not required. Approximately 90% of humeral shaft fractures unite (heal) without the need for surgery. 

Non-Surgical Treatment

Non-surgical treatment for a midshaft humerus fracture usually consists of:

1) Immobilisation

For the first few weeks after a humerus fracture, a sling or splint is worn to hold the fracture still and to allow the swelling and pain to subside. The fracture needs to be immobilised to allow time for the bones to knit back together and heal. 

Humeral shaft fractures are normally treated with a coaptation splint that extends from the shoulder to the forearm, holding the elbow in 90 degrees flexion.

You may be given a collar and cuff sling to support the arm. It is really important to let the arm hang by your side without any support through the elbow as this allows gravity to help realign the fracture. If there is any pressure through the elbow it pushes the bones together resulting in them healing in the wrong position. 

After two to three weeks the coaptation is switched for a functional Sarmiento Brace, a cylindrical brace that fits around the upper arm holding the humerus in place. It leaves the shoulder and elbow free to move which helps prevent stiffness.

2) Medication

Medication to relieve pain and inflammation will be prescribed. If it was an open fracture you will also be given antibiotics to help reduce the risk of infection.

3) Exercises

A physical therapist will work through a rehabilitation programme with you following a midshaft humeral fracture. Exercises for the elbow, wrist and hand should be started as soon as possible to prevent stiffness and weakness from developing and it is usually fine to take your arm out of your sling to do these. 

Once the fracture has started to unite, you can start doing shoulder mobility exercises. These usually start with pendulum exercises where you use gravity to move the arm, and active assisted exercises where you use your good arm to support and move the broken arm. After a few weeks you will be able to start a progressive programme of strengthening exercises and more advanced range of motion exercises.

It is important to stick with the rehab programme and to do your exercises every day until you have regained full strength, flexibility and movement at the shoulder, elbow and hand. If you stop too soon, or only do your exercises sporadically you are likely to have ongoing limitations in the mobility, strength and function of your arm.

Surgical Treatment

Around 10% of humeral shaft fractures with require surgical treatment. 

If the bone fragments are displaced, then the fragments will need to be realigned and held in place. This process is known as an Open Reduction Internal Fixation (ORIF). Usually the fracture is secured with either:

1) Metal Plates: Humeral shaft fractures that require surgery are usually treated with a large metal plate held in place by screws.

Pros: Highest success rate for surgical treatment of humerus fractures 
Cons: Higher risk of nerve damage and non-union than non-surgical treatment

2) Rods: In some cases a humerus fracture will treated surgically with an intramedullary rod/nail. This is when a long metal rod is placed down the middle of the bone. IM nails can be used to stabilise a humerus fracture that is between 2cm below the surgical neck and 3 cm above the elbow. 

Pros: Less invasive and less chance of nerve damage.
Cons: Lower healing rate and higher rate of non-union

Metalware is designed to hold the bones together while they heal – full union should still be achieved. Metal implants are not meant to be a long term solution and if the bones fail to unite, then there is a high chance that the metalware will at some point fail and further surgery may be required 

The usual indications for treating a midshaft humerus fracture surgically are:

1) Fracture Can’t Be Reduced: In some cases, it may be difficult to realign the bones, or maintain the realigned position. This is usually due to associated soft tissue injuries, head injuries or patient obesity

2) Open Fractures: If the bone has shifted enough to puncture the skin it is unlikely that the bone will realign without surgery

3) Segmental Fractures: If the fracture has caused a fragment of bone to break off, it will often need to be secured surgically

4) Multiple Fractures: If the humerus has broken into 4 or more pieces, both the left and right upper arms are broken, or there is a break in one of the forearm bones on the same side then surgery is usually necessary

5) Vascular Damage: If there is significant vascular damage then surgery will be advised

6) Nerve Damage: If the brachial plexus has been damaged then surgery is usually necessary. If the radial nerve has been damaged, it does not usually require surgical intervention unless there are associated injuries – the radial nerve damage will most likely heal within 3-4 months without the need for surgery

7) Non-Union: If after a few weeks the humeral shaft fracture has failed to heal and the bones haven’t united then surgery may be necessary to stabilise the bone

8) Skin or Soft Tissue Damage: If the skin or soft tissues of the upper arm have been damaged to the extent that it is not possible to wear a splint, e.g. severe burns, then surgery may be required

Over 90% of humerus fractures treated non-operatively will unite and are usually fully healed (complete union) within 8-12 weeks. Older patients may not regain full shoulder movement, but they usually regain enough functional range for their day to day activities.

Complications are more common with complex fractures and those requiring surgery.

Mid-shaft fractures may heal with slight angulation i.e. not completely straight, but this doesn’t usually cause any functional issues as the shoulder and elbow accommodate.

At The Time Of Injury

1) Nerve Damage: There is often associated damage to the surrounding nerves with midshaft humerus fractures. The most commonly damaged nerve is the radial nerve, as the nerve wraps around the back of the humerus, with between 8-15% of midshaft fractures resulting in radial nerve damage. Injury to the radial nerve usually occurs at the time of injury, but can also occur when the fracture is reduced so great care should be taken when realigning the bones

2) Blood Vessel Damage: There may be damage to the brachial artery

During Recovery

1) Frozen Shoulder: This is when the capsule of the shoulder joint becomes inflamed and thickened typically due to lack of shoulder movement after a shoulder fracture

2) Myositis Ossificans: This is where calcification develops in the surrounding muscles. Myositis ossificans is usually caused by returning to activities too quickly after a midshaft humerus fracture

3) Fracture Angulation: Often the bone heals at a slight angle but it rarely has any function impact and is usually not visibly noticeable

4) Mal-Union or Non-Union: Mal-union is when the bone fragments unite significantly out of normal alignment. Non-union is where the bone fragments fail to unite back together – this is rare with a midshaft humerus fracture occurring in only 4% of cases and tends to occur with a proximal third midshaft fracture or spiral humerus fracture.

The best way to ensure you make a full recovery from a midshaft humeral fracture, whether it is treated surgically or not, is to follow your exercise rehab programme. Starting exercises as soon as you can tolerate them and continuing them regularly, at least twice a day, over the next few months is the best way to regain full strength, flexibility and mobility. It can get frustrating but do persevere. You will find a whole range of suitable exercises in the shoulder exercises section including progressive plans for mobility exercises and strengthening exercises.

You can find out more about the different types of shoulder fractures, how the present and how to treat them in the shoulder fractures overview. If you injury is at the top part of the upper arm, visit the proximal humerus fracture section.

Go to Shoulder Pain Guide

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