Also named supracondylar fracture, a distal humerus fracture is a type of elbow fracture involving the lower (distal) part of the arm bone. At the elbow the humerus connects with the ulna and allows the rotation of the ulna when the hand is moved palm up or palm down. A distal humerus fracture can impair or block completely the movements of the elbow.
The fracture of the distal humerus comprises 2% of all adult fractures but is very common in children (up to 60%). It is found either as an isolated fracture or in conjunction with other fractures of the arm and elbow joint. It is generally defined as an extension or flexion fracture.
Injuries associated with a distal humerus fracture are:
Vascular damage (brachial artery tear or compression)
Compartment syndrome of the arm and necrosis of soft tissue due poor blood supply
Injuries to the radial nerve, causing temporary/permanent flexion of the wrist (drop hand)
In adults, the classification of distal humerus fractures refers to the mechanisms of injury:
Extension-type (98%): the distal fragment is displaced towards the back (posteriorly)
Flexion-type (uncommon): the distal fragment is displaced to the front (anteriorly)
In children, the Gartland classification for extension type of distal humerus fractures corresponds to the Arbeitsgemeinschaft Osteosynthese (AO) Müller classification for adults as mentioned below in the parentheses.
Type I (extra-articular fracture): undisplaced fractures with unaltered bone alignment
Type II (partial articular fracture): posterior displacement fracture retaining the integrity of the posterior segment of the bone
Type III (complete articular fracture): complete displacement of the distal fragment posteriorly.
According to the Habermeyer Classification the fractures to the proximal humerus are divided into:
Type 0 one fractured part without dislocation
Type A two-part fracture of the great tuberosity and lesser tuberosity avulsion
Type B involves the humerus “surgical” neck below the femoral head as two-part, three-part and four-part with one or both tuberosities
Type C involves the humerus anatomical neck (between the head and greater tuberosity) as two-part, three-part and four-part with one or both the greater and lesser tuberosities.
These are defined further as:
One-part fractures are non-displaced fractures or fractures with minimal displacement
Two-part fractures only involve a single segment
Three-part fractures involve two segments
Four-part fractures occur when all humeral segments are involved (see image in pathology section)
The injury severity is proportional to the increasing number of fractures.
Distal humerus fractures are caused by direct trauma to the arm or elbow and by axial loading transmitted through the elbow. Most common causes are:
Traumatic event (eg. motor vehicle, bicycle accidents)
Fall with the outstretched arm where the ulna pushes towards the humerus
Fall on the flexed elbow
Direct impact with a hard object (hockey/baseball bat, car parts during a collision)
Pathological fractures due to osteoporosis or cancerous metastatic growth
The most frequent risk factors leading to a distal humerus fracture include:
Tendency to fall in elderly individuals (poor vision, lack of physical exercise)
Medical conditions (diabetes, seizure)
Sports (bicycle, horse riding)
Contact sports (football, rugby)
Post-menopausal age in women
The most common symptoms of a distal humerus fracture are:
Severe acute pain at time of accident
Pain at touch
Obvious deformity of the distal arm
Inability to move the elbow
Bone exiting the skin in open fractures
The physical examination begins with the medical history including the causes leading to the distal humerus fracture. The examiner will look for the presence of bruises of the distal arm as a sign of possible humerus fracture. Additional evaluation includes:
Changes in the elbow contour
Restrictions in the range of movement of the elbow, fingers and wrist
Test for nerve damage (sensation at touch, muscle weakness, nerve palsy)
Monitoring of radial and ulnar artery pulses to assess vascular integrity
X-rays are the first approach to detect a distal humerus fractures and assess its classification. A CT scan may be performed if necessary to explore further the type of fracture.
Assessment of the radial nerve
The radial nerve innervates the dorsal extrinsic muscles in the forearm. Injury of this nerve may ca0use hand drop. Functional tests of the radial nerve:
Extension of the wrist and metacarpo-phalangeal (MCP) joints with abduction and extension of the thumb
On examination, the fingers are in flexion at the MCP joints and the thumb are adducted
Dysesthesia or anaesthesia on the dorsum of the thumb
Rarely, the median or ulnar nerves are affected in parallel to injuries to the radial nerve.
In case of undisplaced or minimally displaced distal humeral fractures conservative treatment forms a standard management. A splint or sling is applied and frequent X-rays taken to monitor the progress of fracture healing. During the initial period after injury the elbow is immobilised, after which a gentle physiotherapy can begin.
Additional treatments include:
Administration of NSAIDs
Surgery is required in displaced fractures and open distal humerus fractures. Metal implants are used to repair bone fragments and gain structural alignment.
An external fixator is used when severe, open fractures produce multiple fragments or in patients who cannot be operated, due to medical conditions or the occurrence of multiple injuries. External fixators are connected to the bone with screws inserted through the skin to reduce the fractured humerus and allow for repair in a correct position. Once the patient’s health has improved the surgical internal fixation can be performed. In some rare cases the external fixator is kept until the fracture has healed completely.
Open surgery begins with an incision on the back of the elbow. An osteotomy (bone removal) of the olecranon is performed to allow a better access to the distal humerus. The olecranon is then repaired at the end of the operation. A number of metal implants are used to fix the fracture: pins, wires, plates, and screws. In severe cases the loss of bone caused by the fracture is replaced with homologous bone graft taken from the iliac crest of the hip, cadaver bone or artificial calcium rich material. If it is not possible to repair the fracture of the distal humerus due to abundant comminution and bone loss, the elbow joint may be replaced with a metal prosthesis.
With either conservative or surgical treatment, complications after distal humerus fracture can occur:
Non-union of the fracture (when the gap between the bone extremities is not closed)
Mal-union when the fracture heals with abnormal bone alignment
Temporary damage to the radial nerve
Joint stiffness of the shoulder and elbow
Ossification of soft tissues or heterotopic ossification in adjacent muscles, tendons
Second surgery in case of non union and removal of metal
Initially, after either conservative or surgical treatment a cast or splint is applied in most patients with distal humerus fracture. Physical therapy can commence as soon as the fracture is considered to be stable to prevent elbow stiffness, which may occur after prolonged immobilisation. NSAIDs and pain medications can aid the convalescence by reducing inflammation, swelling and pain. Recovery after distal humerus fracture can be a lengthy process (6 months) and the patient may never be able to lift weights or straighten the arm in full. Patients often display an extension deficit of up to 25 degree without any major functional impairment due to compensation of other joints of the affected arm, i.e. shoulder and wrist joint. Standard rehabilitative therapy also includes:
Activity modification advice
Return to sport/work plan
The main preventative measure aims at reducing the risk of falls in the elderly and protect the arm if collisions occur during sport or biking/motor biking in younger individuals.
Other preventive strategies are:
Elbow bracing when returning to sport
Use of devices to improve elderly stability and avoid falls
Modification of physical activities
Physical exercise to improve muscle strength, flexibility and posture