Supracondylar fractures of the humerus are most common in children, accounting for 30% to 40% of elbow fractures in children, with the preferred age being 5 to 12 years. Ischemic contracture is likely to occur in the early stage of treatment, and deformities such as inversion of the elbow may occur in the late stage.
Etiology and pathology
According to the source and direction of violence, there are three types of fractures: extension, flexion and crush.
1.Extension type
The most common type, accounting for more than 90% of cases. When the elbow joint is in semi-flexion or extension during a fall, the palm of the hand lands on the ground and the violence is transmitted along the forearm to the lower end of the humerus, pushing the humeral condyle posteriorly, while gravity pushes the humeral stem anteriorly, causing a supracondylar fracture of the humerus. The fracture line slopes from anterior to posterior and superior, with the distal end of the fracture displaced posteriorly and the proximal end displaced anteriorly and inferiorly, which can damage the median nerve and brachial artery in severe cases. According to the lateral displacement of the fracture, it can be divided into ulnar deviation type and radial deviation type. The incidence of ulnar deviation fracture elbow inversion can be as high as 74%.
2. Flexion type
It is less common, accounting for about 5%. When the elbow falls in the flexion position, the violence strikes the ulnar hawkbone anteriorly and superiorly from posterior inferiorly, the distal end of the supracondylar fracture is displaced forward and the fracture line is oblique from posterior inferiorly to superiorly.
3.Comminuted type
Mostly seen in adults. Most of the fractures are intercondylar fractures of the humerus, which can be divided into T- and Y-type or comminuted fractures according to the shape of the fracture line.
It can be divided into ulnar deviation and radial deviation according to the displacement.
1.Ulnar deviation type
The fracture violence comes from the anterolateral aspect of the humeral condyle, and the humeral condyle is pushed to the posterior medial aspect during the fracture. The medial bone cortex is compressed and collapses to a certain extent. The anterolateral periosteum is ruptured and the medial periosteum is intact. The distal end of the fracture is displaced to the ulnar side. The distal end is therefore prone to re-displacement to the ulnar side after repositioning. Even if anatomic repositioning is achieved, the medial cortical compression defect is thus deflected inward. The incidence of inversion of the elbow is highest after ulnar deviation fracture.
2. Radial deviation type
This is the opposite of the ulnar deviation type. The radial cortex of the fracture is collapsed due to compression. The lateral periosteum remains continuous. The ulnar periosteum is broken and the distal end of the fracture is displaced to the radial side. This type of fracture does not produce severe elbow valgus even if it is not completely repositioned, but it can also produce elbow valgus deformity if anatomically repositioned or overcorrected.
Clinical presentation
The clinical diagnosis is easy and most patients are children. Post-traumatic swelling, pain, dysfunction and deformity. The diagnosis of supracondylar fracture of the humerus should be accompanied by attention to hand temperature, pulse, movement and sensation to clarify the presence of vascular and nerve injury.
Diagnosis
A history of obvious trauma, pain in the affected limb, and limited movement. x-rays can determine the diagnosis and the fracture category of shortened upper arm, normal forearm, normal upper arm, and shortened forearm type. Supracondylar fracture of humerus needs to be differentiated from elbow dislocation.
Complications and sequelae
1, vascular nerve injury: a serious complication of supracondylar humerus fracture is vascular injury. It is rare for the fracture end to pierce the blood vessels, but mostly due to spasm or mechanical compression of the blood vessels by stimulation, resulting in impaired blood supply to the distal limb. Clinical attention should be paid to check the pulsation of the radial artery of the affected limb. Once it occurs, it can cause limb necrosis.
2, ischemic muscle contracture: when the brachial artery is spasmed or compressed, the distal blood supply of the limb is severely impaired. The muscle is edematous due to ischemia. It is generally said that ischemia lasts more than 6 to 8 hours, and muscle necrosis can occur. In mild cases, only the fingers cannot be straightened, in severe cases, the fingers and wrist joints are flexed and stiffened, the set of sensory paralysis, claw-like hand deformity, etc. is called ischemic muscle contracture, also known as Volkmann’s contracture.
The earliest symptom of ischemic myoclonus is severe pain, which is more pronounced when the fingers are passively straightened early. The radial artery pulsation is weakened or absent, and the fingers are cyanotic, cold, and numb. Once the main cause is identified, surgical exploration or release of external fixation is targeted for further observation. In some cases, the radial artery pulsation disappears, but the finger can still be moved and the pain is not serious, so the radial artery pulsation can be restored by manual repositioning or traction repositioning, because the fracture misalignment is reverted to correction and the compression of the blood vessels is released.
After the formation of ischemic muscle contracture, treatment is difficult. The key is early diagnosis and prevention.
3. Treatment of elbow inversion deformity: ulnar deviated supracondylar humerus fractures are mostly followed by elbow inversion, while radial deviated type is rarely followed by elbow inversion. When dealing with supracondylar humerus fractures, special attention should be paid to prevent elbow inversion from occurring. Once it occurs, it should be corrected by surgical osteotomy.
Treatment
1. Green branch fracture or non-displaced or mildly displaced fracture
If the fracture end is not displaced and the anteversion angle disappears, no repositioning is required; if the anteversion angle increases, gentle repositioning is performed under brachial plexus anesthesia or general anesthesia, and the long-arm cast is fixed in a functional position for 3 to 4 weeks.
2. Displaced fracture
Under brachial plexus or general anesthesia, the fracture is repositioned manually and the long-arm cast is fixed for 4-6 weeks. The main points of manual repositioning are: longitudinal traction to correct the overlapping displacement, then lateral compression to correct the lateral displacement, and finally the anterior-posterior displacement. The radial lateral displacement need not be completely corrected, and the ulnar lateral displacement should be overcorrected to avoid the occurrence of elbow inversion deformity. For flexion fractures, fix the fracture in a semi-extension position after resetting; for extension fractures, fix the fracture in a less than 900 flexion position after resetting, so that the fracture is stable and does not affect the circulation of the hand. If the flexion position affects the circulation and the fracture is unstable after a little straightening, it can be fixed by percutaneous clinically crossed pins under the fluoroscopic view of TV Х-ray machine and external fixation in the appropriate flexion position with a plaster rest; it can also be treated by traction and fixed by plaster after the swelling is reduced.
3.Traction treatment
Applicable to fracture more than 24-48 hours, soft tissue swelling, blister formation, can not be repositioned manually, or the fracture is unstable after repositioning.
4.Open reduction
It is suitable for those who have failed to be repositioned manually, open fracture, fracture combined with vascular injury, bone discontinuity, fracture deformity connection or serious deformity of elbow inversion or valgus, and osteotomy is feasible for correction.
5.Fracture combined with nerve injury
First reset and fix the fracture, observe for 1~3 months, if there is no recovery, then perform nerve exploration and release or repair.
6.Ischemic contracture
The key is early diagnosis and prevention. For those who have 5 “P” signs, first reset the fracture and release the compression factors. If there is no improvement, early exploration and vascular repair should be performed, and if necessary, interfascial compartment dissection and decompression should be performed.