Proximal humerus - Overview

Below is an overview of proximal humeral fractures for details on  2 part, and 3&4 part fractures follow links on left.

 

Proximal humerus fractures are common injuries, particularly in the elderly population. They represent approximately 4% to 5% of all fractures.

80- 85% of these fractures are minimally displaced or nondisplaced.
 

Anatomy

The proximal humerus consists of four bony parts:

  • Humeral head (articular surface)

  • Greater tuberosity

  • Lesser tuberosity

  • Humeral shaft

The neck shaft angle of the proximal humerus averages 145° and is retroverted approximately 30°.

The proximal humerus forms from multiple ossification centres, which are visible on plain radiographs by age 6 months.

The greater tuberosity ossifies by age 3 years and the lesser tuberosity by age 5 years.

The tuberosities unite during the fifth year of life and subsequently fuse with the shaft by age 19 years.

 

Vascularity of humeral head

Predominantly from the anterior humeral circumflex artery, a branch of the axillary artery.

As it traverses across the anterior aspect of the humerus, it gives off an anterolateral ascending branch (Arcuate artery), which travels along the lateral aspect of the long head of the biceps and enters the head at the proximal margin where the bicipital groove borders the greater tuberosity.

The posterior humeral circumflex artery contributes to the vascularity of a small portion of the inferior part of the humeral head and part of the greater tuberosity. Gerber et al (1990)


Brooks et al (1993) showed in contrast to the conclusions of Gerber et al (1990), that the humeral head can be completely perfused after ligation of the anterior humeral artery at its site of entry into the humeral head.
They showed a large metaphyseal, epiphyseal anastomosis in six of the eight normal and control specimens.
In long bones with an open growth plate, the epiphyseal and metaphyseal circulations have been described as essentially independent.
Small arteriolar communications are known to develop at the time of fusion of the growth plate.
Brooks et al showed the presence of a large metaphyseal artery which passes through the central area of the fused growth plate to anastomose with the epiphyseal arcuate artery.
This suggests that in the upper humerus at least, the circulations of the epiphysis and metaphysis are not independent.
As regards the management of four-part fractures, these perfusion studies highlight the importance of the posteromedial arteries in maintaining the vascularity of the humeral head.
These vessels pass beneath the humeral capsular attachment, which at this site extends for 1 cm on to the surgical neck, and run towards the humeral head before entering the bone just below the articular margin. After a four-part fracture, when the blood supply from the anterior humeral circumflex artery, the greater tuberosity, the lesser tuberosity and any metaphyseal arterial anastomoses have all been lost, perfusion of the humeral head via the arcuate artery may continue if the head fragment includes part of the medial aspect of the upper part of the neck.
This would explain the findings of Jakob et al (1991) who reported a low incidence of avascular necrosis of the humeral head in four-part fractures in which the humeral head was impacted and in valgus. In this type of fracture the medial aspect of the humeral head is little displaced, and may thus retain its vascularity from the posteromedial vessels.
When the medial fracture line is at the junction between the articular surface and the neck this anastomosis will be lost and the head will be avascular.
A clear appreciation of the plane and level of all fracture lines is essential in assessing the remaining blood
supply to the humeral head. CT scanning of the upper humerus with 3-D reconstruction has been shown to
improve this evaluation in most cases.

 

The posterior humeral circumflex artery

Arises from the axillary artery at the lower border of the Subscapularis, and runs backward with the axillary nerve through the quadrangular space bounded by the Subscapularis and Teres minor above, the Teres major below, the long head of the Triceps brachii medially, and the surgical neck of the humerus laterally. It winds around the neck of the humerus and is distributed to the Deltoideus and shoulder-joint, anastomosing with the anterior humeral circumflex and profunda brachii.

 

The anterior humeral circumflex artery

Is considerably smaller than the posterior, arises nearly opposite it, from the lateral side of the axillary artery. It runs horizontally, beneath the Coracobrachialis and short head of the Biceps brachii, in front of the neck of the humerus. On reaching the intertubercular sulcus, it gives off a branch which ascends in the sulcus to supply the head of the humerus and the shoulder-joint. The trunk of the vessel is then continued onward beneath the long head of the Biceps brachii and the Deltoideus, and anastomoses with the posterior humeral circumflex artery.

 

Muscular attachments

The muscle attachments are typically balanced; however, when a fracture occurs, they produce deforming forces.

  • Pectoralis major inserts on the lateral margin of the bicipital groove and acts to displace the shaft medially and anteriorly.

  • Supraspinatus, infraspinatus, and teres minor insert on the greater tuberosity and exert an abduction and external rotation force.

  • Subscapularis inserts on the lesser tuberosity and exerts an internal rotation force.

Therefore, if the greater tuberosity is fractured, it will be displaced superiorly and posteriorly (depending on which portion or portions of the tuberosity are involved), and the head will rotate internally. If the lesser tuberosity is fractured, it will be displaced medially, and the humeral head will rotate externally.

 

Clinical evaluation

Gross deformity is not often appreciated because of the soft tissues surrounding the proximal humerus.

Swelling and tenderness to palpation are typically present.

Bruising extending along the arm distally and along the chest wall is often present a few days following injury.

Assessment of fracture stability is an important part of the examination.

With one hand palpating the humeral head, the humeral shaft should be gently internally and externally rotated. If the proximal and distal fragments move as a unit, the fracture is considered stable.

A thorough neurovascular examination is crucial due to the close proximity of the brachial plexus and the axillary artery.

The incidence of neurovascular injury is increased in fracture-dislocations.

The axillary nerve is most commonly injured.

 

Radiographs

Three standard radiographs.

AP view

Perpendicular to the plane of the scapula. Be aware of the possibility of pseudosubluxation of the shoulder as a result of weakening of the surrounding musculature and its inability to support the weight of the arm. Fairbank reported a 10% occurrence of pseudosubluxation following proximal humerus fractures.

Lateral scapula (Y view)

This view is helpful in evaluating the position of the humeral head in relation to the glenoid and for assessing anteriorly or posteriorly displaced fragments.

Axillary view

Very helpful in evaluating the position of the humeral head in relation to the glenoid, glenoid rim pathology, and humeral head articular injuries.

 

If the degree of displacement of the humeral head or tuberosity fragments is uncertain, obtain an axial CT with 2-mm sections.

Magnetic resonance imaging is rarely needed.

MRI is indicated when the patient has symptoms suggestive of a preinjury shoulder disorder such as a rotator cuff tear.

It can also be useful in the evaluation of the rotator cuff when the patient has persistent pain after the fracture has healed.

 

Classification

 

 

Kocher 1896

Divided the proximal humerus into 3 regions

  • Anatomical neck

  • Epiphyseal region

  • Surgical neck

Codman 1934

Divided the proximal humerus into four fragments, along lines of physeal union:

  • Anatomical head

  • Greater tuberosity

  • Lesser tuberosity

  • Shaft

Neer 1970

Neer, utilizing Codman's earlier descriptions, classified proximal humerus fractures based on the position of four possible fracture fragments.

This classification has become the most widely used in practice today.

The type of proximal humerus fracture depends on the displacement of one or more of the four segments.

For a segment to be considered a part (i.e., displaced), it must be displaced greater than 1 cm or angulated more than 45° from its anatomic position.

The number of fracture lines is only important if the displacement criteria are fulfilled. The most common fracture type is a one-part fracture (i.e., absence of displacement of any of the four parts).

These fractures comprise 80% to 85% of proximal humerus fractures.

 

Some authors suggest that in greater tuberosity fractures displacement of 0.5cm should be used to define a part.

 

Two-part fracture

There are four possible types of 2 part fractures:

Three-part fracture

These can either involve a fracture of the greater tuberosity or the lesser tuberosity in conjunction with a fracture of the surgical neck.

 

Four-part fracture

These are characterized by displacement of all four segments.

 

Articular surface

Fractures of the articular surface are also included in this classification.

This group includes head-splitting fractures and impression fractures, which may occur with a dislocation.

Impression fractures of the articular surface are graded according to % articular surface involved:

  • Less than 20%

  • 20% to 45%

  • Greater than 45%

Fractures in which the articular surface is shattered into several fragments are termed head-splitting fractures.

This term is not applicable to fractures in which a small portion of articular surface (<10% or 15%) is attached to a displaced greater tuberosity

 

Fracture dislocation

Neer also classified fracture-dislocations as either an anterior or posterior dislocation of the articular segment.

Consequently, all two-, three-, and four-part fractures can occur as fracture-dislocations.

Although the Neer classification is often used in the treatment decision-making process for proximal humerus fractures, reports in the orthopaedic literature demonstrate suboptimal interobserver and intraobserver reliability

 

AO classification

In the AO universal classification greater emphasis is placed on the vascular supply as an indication of the severity of the injury and the risk of osteonecrosis.

  • Type A - extraarticular and involve one of the tuberosities.

    • A1- extraarticular unifocal tuberosity

    • A2 have an impacted metaphyseal fracture

    • A3 have a nonimpacted metaphyseal fracture.

    • Osteonecrosis is not likely because the vascular supply to the articular surface is not violated.

  • Type B - Extraarticular and involve both tuberosities

    • B1 - Impacted metaphyseal fracture

    • B2 - Nonimpacted metaphyseal fracture

    • B3 - Glenohumeral dislocation

    • The risk of osteonecrosis is low

  • Type C - Articular

    • C1 - Slight displacement

    • C2 - Marked displacement

    • C3 - Associated dislocation

    •  The risk of osteonecrosis is high because the articular surface is separated from its vascular supply.

The complexity of this universal classification has limited its use compared with the Neer classification.

Siebenrock and Gerber in 1993 reported that the interobserver reliability of the AO classification was as limited as the Neer classification.

 

Treatment Selection

Although absolute indications for the treatment of proximal humerus fractures remain controversial, treatment is primarily determined by examining the radiographs and computed tomographic (CT) scans of the proximal humerus and then classifying the injury according to the Neer classification.


The indications for open or closed reduction and internal fixation are related to:

  • The fracture pattern

  • The quality of the bone

  • The status of the rotator cuff

  • The age and activity level of the patient

  • The goal of reduction and fixation of a proximal humeral fracture is to obtain nearly anatomic reduction and stable fixation to allow an early range of motion.

Recently, there has been an emphasis on the use of less invasive open procedures for reduction and fixation, thereby minimizing periarticular scarring and decreasing the risk of vascular insult to the articular humeral head segment from the surgical exposure.

Most truly undisplaced fractures are treated non operatively.
Remember in greater tuberosity fractures use 0.5 cm, not 1cm as a cut off for displacement.

 

For details of injury and treatment follow links on left or below

Undisplaced/ minimally displaced fractures

Minimally displaced fractures or one-part fractures are typically managed with a short period of sling immobilization for comfort.

If the humeral head and shaft move as a unit on physical examination, early Passive Range Of Movement (PROM) exercises may be instituted.

Minimally displaced fractures occur through metaphyseal bone and usually unite in 6 weeks.

 

Patients are generally reviewed at  to 2 weeks with a radiograph to exclude any displacement.

Reviewed again at 3 to 4 weeks where if clinically and radiographically the fracture is uniting, a strengthening program is usually begun when AROM has progressed.

 

Hodgson et al showed that in minimally displaced 2 part fractures, patients who begin immediate physiotherapy, experience less pain initially and improved shoulder function persists at 52 weeks.

During the first two weeks patients are educated about their injury, taught pendular exercises, and shown how to flex their arm passively, within their pain tolerance, as part of a home exercise programme.

Between weeks two and four, the patients progress to full passive flexion and light functional exercises, with progressive functional exercises starting at week four.

 

From the date of injury, encourage patients to perform active ROM (AROM) of the elbow, wrist, and hand in an effort to prevent distal extremity stiffness and oedema.

 

Complications

Complications following treatment of minimally displaced proximal humerus fractures primarily include stiffness.

Malunion should not occur if the fracture is diagnosed properly and followed closely.

Stiffness is best avoided by early ROM.

 

2 part fractures

Follow links on left or click on heading above

 

3 and 4 part fractures

Follow links on left or click on heading above
 

References

 

CH Brooks, WJ Revell, and FW Heatley; Vascularity of the humeral head after proximal humeral fractures. An anatomical cadaver study J Bone Joint Surg Br, Jan 1993; 75-B: 132 - 136

 

C Gerber, AG Schneeberger, and TS Vinh
The arterial vascularization of the humeral head. An anatomical study
J. Bone Joint Surg. Am., Dec 1990; 72: 1486 - 1494

 

Laing PG: The arterial supply of the adult humerus. J Bone Joint Surg Am 1956;38:1105–1116

 

IANNOTTI, JOSEPH P. MD, PHD; RAMSEY, MATTHEW L. MD; WILLIAMS, GERALD R. MD; WARNER, JON J.P. MD NONPROSTHETIC MANAGEMENT OF PROXIMAL HUMERAL FRACTURES. Journal of Bone & Joint Surgery - American Volume. 85-A(8):1578-1593, August 2003.

Joseph, David MD; Levine, William N. MD Proximal humerus fractures. Current Opinion in Orthopedics. 10(4):305-309, August 1999.

 

ELKOWITZ, STUART J. M.D.; KOVAL, KENNETH J. M.D.; ZUCKERMAN, JOSEPH D. M.D. Decision Making for the Treatment of Proximal Humerus Fractures. Techniques in Shoulder & Elbow Surgery. 3(4):234-250, December 2002.

 

R. John Naranja, Jr and Joseph P. Iannotti
Displaced Three- and Four-Part Proximal Humerus Fractures: Evaluation and Management


J. Am. Acad. Ortho. Surg., November/December 2000; 8: 373 - 382.

Resch H, Beck E, Bayley I: Reconstruction of the valgus-impacted humeral head fracture. J Shoulder Elbow Surg 1995;4:73–80

 

S. A. Hodgson, S. J. Mawson, and D. Stanley; Rehabilitation after two-part fractures of the neck of the humerus
J Bone Joint Surg Br, Apr 2003; 85-B: 419 - 422.
 

Page created by: Lee Van Rensburg
Last updated 11/09/15