DEFINITION

Proximal humerus fractures are defined as those of the proximal portion of the humerus involving the shoulder joint.

Fracture lines divide the proximal humerus into parts defined by anatomic structures that arise from early centers of ossification.

These “parts” first were described by Codman and led to development of the Neer classification,7 which is commonly used today.

The parts refer to the head of the humerus, the greater tuberosity, the lesser tuberosity, and the shaft (FIG 1).

Proximal humerus fractures are classified as two-, three-, or four-part fractures according to the Neer classfication.7

Displacement of a “part” is classically defined as 1 cm of displacement or 45 degrees of angulation. Importantly, displacement is not necessarily an indication for surgery but only a criterion for classification.

The type of fracture, degree of displacement, and the likelihood of osteonecrosis, as well as patient considerations, all factor into surgical decision making.

 

ANATOMY

 

The proximal humerus arises from four distinct centers of ossification: the humeral head, the greater tuberosity, the lesser tuberosity, and the shaft.

 

 

The greater tuberosity has three distinct facets for the insertion of the supraspinatus, the infraspinatus, and the teres minor muscles of the rotator cuff.

 

 

 

FIG 1 • Fractures of the proximal humerus are classified as two-, three-, or four-part fractures based on fracture and degree of displacement of the greater tuberosity, the lesser tuberosity, the humeral head, and the humeral shaft.

 

 

The lesser tuberosity is the insertion site for the subscapularis muscle.

 

The rotator interval lies between the upper subscapularis and the anterior border of the supraspinatus.

 

 

The long head of the biceps tendon lies in a shallow groove on the anterior proximal humerus and enters the glenohumeral joint at the rotator interval.

 

The proximal 3 cm of the long head of the biceps tendon lies deep to the interval tissue intra-articularly.

 

The anterior humeral circumflex artery (FIG 2) courses laterally along the inferior subscapularis.

 

 

The anterolateral branch of the anterior humeral circumflex artery travels superiorly along the lateral aspect of the biceps groove and enters the humeral head at the proximal-most aspect of the groove, providing

about 85% of the blood supply to the humeral head.1

 

The posterior humeral circumflex artery gives off several small branches that run adjacent to the inferior capsule of the shoulder, providing most of the remaining blood supply.

 

The pectoralis major muscle inserts on the proximal shaft of the humerus lateral to the long head of the biceps tendon. The latissimus dorsi muscle inserts onto the proximal shaft medial to the biceps groove.

 

 

 

FIG 2 • The rotator interval lies between the upper border of the subscapularis and the anterior border of the supraspinatus. The biceps tendon runs deep to the rotator interval tissue. Importantly, the fracture line between the greater and lesser tuberosities lies just posterior to the biceps groove. The ascending branch of the anterior humeral circumflex artery provides 85% of the blood supply to the humeral head.

 

 

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PATHOGENESIS

 

Proximal humerus fractures occur in a bimodal distribution.

 

 

Most proximal humerus fractures are “fractures of senescence” in older individuals with age-related osteopenia. They commonly result from low-energy injures such as tripping and falling.

 

They also occur in younger individuals as the result of highenergy injuries such as motorcycle or automobile accidents.

 

Associated nerve injuries can occur and usually resolve spontaneously. Axillary nerve neurapraxia is the most common.

NATURAL HISTORY

 

Eighty-five percent of proximal humerus fractures can be treated nonoperatively.7

 

Displacement at the surgical neck is better tolerated than displacement at the greater tuberosity.

 

 

Because of the vast range of motion (ROM) of the shoulder in multiple planes, the arm can compensate for translational displacement or angulation at the surgical neck.

 

Displacement of the tuberosities, however, affects the mechanics of the rotator cuff and is very poorly tolerated.

 

Four-part fractures have an extremely high incidence of avascular necrosis—45% in Neer's classic series— with the exception of valgus impacted four-part fractures in which the incidence is only 11%.8

 

In most four-part fractures, the blood supply from the anterior humeral circumflex artery is disrupted, contributing to the high incidence of avascular necrosis.

 

The posterior humeral circumflex artery also contributes to humeral head vascularization, and the incidence of avascular necrosis increases with lateral displacement of the humeral head in four-part fractures.

 

The blood supply is maintained in most valgus impacted fractures by the branches from the posterior humeral circumflex artery along the intact medial periosteal hinge (FIG 3), making this particular fracture configuration very amenable to fixation.

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

A complete history of injury is important to determine the mechanism of injury. It is helpful to differentiate low-energy from high-energy injuries.

 

 

Elderly individuals often sustain proximal humerus fractures as the result of low-energy injuries such as slipping and falling. These injuries often are very amenable to minimally invasive fixation techniques because the displacement is manageable and the periosteal sleeve between fracture fragments often is intact. The rotator cuff often is intact as a sleeve. All these qualities facilitate minimally invasive reduction and fixation techniques.

 

 

 

FIG 3 • Valgus impacted fractures maintain blood supply to the articular surface via ascending branches off the posterior humeral circumflex artery along the intact medial periosteal hinge.

 

 

In younger individuals, proximal humerus fractures often result from higher energy injuries. These fractures commonly have greater fracture fragment displacement, rotator cuff tears between the tuberosities, and disruption of the periosteal sleeve. These factors do not necessarily preclude percutaneous pinning but make it more challenging and should be considered in preoperative planning.

 

Other important aspects of the history include the following:

 

 

 

Previous history of injury to the affected shoulder Previous shoulder function

 

History of numbness or tingling in the affected extremity

 

Rule out elbow and wrist fractures, especially in osteoporotic patients with injuries resulting from a fall on an outstretched arm.

 

Patients often hold the shoulder inferior on the affected side.

 

Examination should include skin integrity, presence of ecchymosis, downward carriage of shoulder girdle, and deformity consistent with shoulder dislocation or acromioclavicular joint separation.

 

Examine for possible associated nerve injury (usually neurapraxia) by testing sensation to light touch in individual nerve distribution, two-point discrimination, and muscle strength (testing is limited to isometric at shoulder because of limited ROM and pain).

 

Pay particular attention to axillary nerve function as injuries are common.

 

Possible associated vascular injury can be determined by testing radial pulse and capillary refill.

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

A trauma series of radiographs of the shoulder should be obtained (FIG 4).

 

 

The series includes an anteroposterior (AP) view of the shoulder, a scapular AP view, a scapular Y view, and an axillary view.

 

A complete series with these views allows the fracture configuration to be determined in sufficient detail.

 

A computed tomography (CT) scan is helpful in many cases and should be obtained if there is any question regarding the

 

P.3724

extent of fracture involvement or the level of displacement of the fragments. It also is helpful if there is any question of joint dislocation or glenoid fracture.

 

 

 

FIG 4 • A normal trauma series includes a scapular AP radiograph, an AP radiograph of the shoulder, an axillary view, and a Y lateral view. A. The scapular AP view is taken, by convention, with the arm in neutral rotation. B. The AP view of the shoulder is taken with the arm in internal rotation. C. The axillary lateral view is taken with the arm abducted and in neutral rotation. D. The Y lateral view often allows the examiner to detect any posterior displacement of subtle greater tuberosity fractures.

 

 

Radiographs are used to determine whether the fracture is a two-, three-, or four-part fracture and to assess the degree of displacement.

 

Three-dimensional reconstructions of the CT scan can be helpful in fracture evaluation but are not routinely required.

 

DIFFERENTIAL DIAGNOSIS

Acromioclavicular joint separation Glenohumeral joint dislocation Humeral shaft fracture Scapulothoracic dissociation

Elbow and wrist fractures (may coexist)

 

 

NONOPERATIVE MANAGEMENT

 

 

Minimally displaced fractures can be treated nonoperatively. Displacement at the surgical neck is well tolerated.

 

An AP view of the shoulder can be misleading in the case of a surgical neck fracture.

 

 

The pectoralis major muscle exerts an anterior force on the shaft, resulting in anterior displacement of the shaft relative to the humeral head.

 

A scapular Y or axillary view can exhibit this angular deformity.

 

Displacement of the greater tuberosity is less well tolerated.

 

Historically, 1 cm of displacement has been used as the criterion for clinically significant tuberosity displacement.

 

Recently, however, even 5 mm of displacement has been considered an operative indication.

 

Patients wear a sling for 2 to 3 weeks or until the proximal humerus feels stable with gentle internal or external rotation of the arm.

 

 

Patients should be instructed to remove the sling for elbow, wrist, and hand ROM to avoid stiffness of these joints.

 

Early signs of healing (eg, callus formation) also are helpful indicators of when it is safe to commence ROM exercises.

 

In borderline instances, it is better to err toward a longer period of immobilization to ensure healing because shoulder stiffness is easier to address than a nonunion.

 

Therapy begins with passive stretching until 6 weeks when active ROM and strengthening can be started, progressing as tolerated.

 

SURGICAL MANAGEMENT

Preoperative Planning

 

All imaging studies should be reviewed carefully to determine the type of fracture, the degree of displacement, fracture configuration, and bone quality.

 

Certain radiographic findings that can suggest that minimally invasive fracture fixation is not appropriate for a given fracture are as follows:

 

Poor bone quality. The bone may not hold the pins and screws well and may be better treated with a more stable construct.

 

Comminution of the greater tuberosity. A comminuted bone fragment is not amenable to fixation with screws. Fractures with a comminuted greater tuberosity require suture fixation through the tendon-bone junction (requires an open approach).

 

Comminution of the medial calcar region leads to unstable reduction of the head onto the shaft.

 

Fractures amenable to minimally invasive fixation are twopart, three-part, and valgus impacted four-part fractures with the following:

 

 

Good bone quality

 

 

Substantial fracture fragments with minimal comminution of the tuberosities Minimal or no comminution at the medial calcar region

 

Minimally invasive fixation is not appropriate for noncompliant or unreliable patients. This procedure should be

 

P.3725

performed only in patients committed to consistent followup in the postoperative period.

 

 

 

FIG 5 • The patient is placed in the supine or gently upright position. The C-arm is brought in parallel to the patient, leaving the lateral aspect of the arm free for instrumentation. The patient should be positioned laterally on the table such that an adequate fluoroscopic view can be obtained.

 

 

The pins require close surveillance in the early postoperative period.

 

Pin migration is possible and must be caught early in order to avoid potential injury to thoracic structures.

 

Positioning

 

Percutaneous pinning is performed with the patient in the 45-degree beach-chair position (FIG 5).

 

 

This allows easy intraoperative evaluation with C-arm fluoroscopy.

 

The C-arm fluoroscope is placed parallel to the patient, extending over the shoulder from the cephalad direction.

 

 

This position leaves the lateral shoulder completely accessible for instrumentation and pin fixation.

 

 

 

FIG 6 • A. The reduction portal is established off the anterolateral corner of the acromion. Instruments can be introduced through this portal to help reduce the fracture. B. The reduction portal is located at the level of the surgical neck fracture approximately 0.5 to 1 cm posterior to the biceps groove. The reduction portal is definitively localized using C-arm imagery. (continued)

 

 

The patient must be positioned far lateral on the table or on a specialized shoulder surgery positioning device such that the shoulder can be imaged in the AP plane without the table obstructing the view.

 

 

This image should be checked before prepping and draping to confirm adequate visualization.

 

The entire upper extremity is draped free.

 

Approach

 

Closed fracture reductions are performed with the aid of a “reduction portal” (FIG 6).3

 

 

The reduction portal is a portal (analogous to that of an arthroscopic portal) or small incision used to access the fracture fragments.

 

Instruments can be introduced through this portal to lever fracture fragments or pull fragments into reduced position.

 

The surgeon also can insert a finger through this portal to palpate fragments.

 

 

Medially, the biceps tendon can be palpated.

 

The surgical neck fracture is located just deep to the portal.

 

By sweeping posteriorly and superiorly, the greater tuberosity and its extent of displacement can be palpated.

 

 

The location of the reduction portal is critical (FIG 6B).

 

 

In three- and four-part fractures, the fracture line of the greater tuberosity is reliably 0.5 to 1 cm posterior and lateral to the biceps groove.

 

Therefore, the reduction portal is located at the level of the surgical neck and 1 cm posterior to the biceps groove.

 

The arm is held in neutral rotation.

 

The level of the surgical neck is located using fluoroscopic imagery (FIG 6C,D).

 

The location of the biceps tendon is estimated based on surface anatomic landmarks.

 

A 2-cm incision is made in the skin (FIG 6E).

 

 

Subcutaneous tissues and the deltoid muscle are spread bluntly using a straight hemostat to avoid injury to the axillary nerve on the deep surface of the deltoid. Subdeltoid adhesions are gently released by sweeping finger if necessary.

 

 

P.3726

 

 

 

FIG 6 • (continued) A hemostat is applied to the skin (C) and then imaged (D) to confirm that this portal will be directly at the level of the surgical neck fracture. E. A small incision is made in the skin, and the deltoid is spread bluntly to avoid injury to the underlying axillary nerve.

 

 

TECHNIQUES

• Surgical Neck Fracture

  Reduction

  The pectoralis major muscle provides the major deforming force resulting in displacement of surgical neck fractures. The shaft usually is displaced anteriorly and medially with respect to the head.

  An axillary or scapular Y radiograph is necessary to evaluate the extent of this displacement.

  The reduction maneuver involves flexion, adduction, and possibly some slight internal rotation to relax the pull of the pectoralis major muscle4 (TECH FIG 1).

  Longitudinal traction is applied to the arm, and a posteriorly directed force is applied to the proximal shaft of the humerus.

  A blunt instrument can be inserted into the fracture at the surgical neck to lever the head back onto the shaft. This maneuver can be a powerful reduction tool, but care should be used to avoid further damage or fracture to the humeral head during this maneuver, especially on osteopenic patients.

  The long head of the biceps tendon can become interposed between the fracture fragments, precluding reduction.

  Therefore, if reduction is not achieved, check the biceps tendon through the reduction portal (or consider open reduction).

   

   

   

  TECH FIG 1 • The reduction maneuver for surgical neck fractures involves flexion and internal rotation of the arm to negate the effect of the pectoralis major fragment on the proximal aspect of the shaft. Often, a posterior vector must be applied to the shaft or an instrument can be introduced through the reduction portal to lever the head back onto the shaft.

  Fixation

   

  Two or three retrograde pins are placed from the shaft into the humeral head (TECH FIG 2).

   

  The starting point for the pins is approximately 5 to 6 cm distal to the surgical neck fracture line.

   

  The pins must angle steeply to enter the head fragment and not cut out posteriorly (TECH FIG 2B,C).

   

  Pins should be smooth to avoid injury to soft tissue upon insertion and terminally threaded to avoid backing out.

   

  A 2.5- or 2.7-mm smooth, terminally threaded pins commonly are found in external fixation or 7.3-mm cannulated screw sets of instruments.

   

  The pins should enter at different directions to enhance stability of fixation construct.

   

   

  One pin should enter lateral to the biceps in a primarily anterior to posterior direction. Another pin should enter further laterally in a primarily lateral to medial direction.

   

  Stability should be checked under fluoroscopic imaging with live, gentle internal and external rotation.

   

  Any suggestion of instability or motion at the fracture is an indication for open reduction and plate fixation at that point.

   

   

  Pins are cut below the skin to prevent pin site infection (TECH FIG 2D). The reduction portal is closed with interrupted absorbable sutures.

   

  A soft dressing and sling are applied.

   

   

  P.3727

   

   

   

  TECH FIG 2 • A. Retrograde pins are introduced several centimeters below the level of the surgical neck fracture into the head. The pins should be placed in different directions to provide stability to the construct.

  B. Placement of two pins. C. Fluoroscopic view of two retrograde pins in place. D. The pins should be cut below the skin after insertion to prevent pin site infection. They are easily removed a couple of weeks later with a small procedure in the office or operating room.

• Three-Part Greater Tuberosity Fractures

  Reduction

   

  Deforming forces influencing displacement of three-part fractures include the pectoralis major, as described earlier, and the rotator cuff muscles. The rotator cuff pulls the tuberosity medially (to a certain extent) and posteriorly. Posterior displacement and rotation often are underappreciated and must be considered.

   

  The surgical neck component is addressed first. (See Surgical Neck Fracture earlier in this section.)

   

  The greater tuberosity fracture is reduced using the “reduction portal.” A dental pick or small hooked instrument is inserted through the portal to engage the tuberosity and pull it inferiorly and anteriorly into a reduced position.

  Fixation

   

  4.5-mm cannulated screws are used to fix the tuberosity fragment.

   

  The screw is placed through the tuberosity fragment distal to the cuff insertion through bone on the

  lateral cortex (TECH FIG 3A).

   

  The proper location is confirmed with fluoroscopic imaging.

   

  The guidewire is first passed through a small incision in the skin just large enough to pass the drill guide and screw through the deltoid (TECH FIG 3B,C).

   

  The guidewire is passed through the tuberosity, across the surgical neck fracture, and engages the medial cortex of the proximal humeral shaft.

   

  After the guidewire is overdrilled, the screw is passed over the guidewire. We use a partially threaded screw with a washer (TECH FIG 3D-F).

   

  If the greater tuberosity fragment is large enough, a second cancellous screw is directed through the tuberosity fragment, engaging cancellous bone of the humeral head.

   

  Pins are cut beneath the skin.

   

   

  Incisions are closed with nylon interrupted sutures. A dressing and sling are applied.

   

  P.3728

   

   

   

  TECH FIG 3 • A. The greater tuberosity is localized under fluoroscopy using a hemostat. B. A small incision is made over the greater tuberosity, and a cannulated screw is used for fixation. This photograph demonstrates the drill guide used for soft tissue protection. C. The guidewire is aimed to engage the greater tuberosity fragment as well as the medial cortex to provide compression. D. This fluoroscopic view demonstrates the screw being inserted over the guidewire. E. A washer is used to provide some compression. Overtightening should be avoided to prevent fracture of the greater tuberosity fragment. F. Screw and washer insertion.

• Valgus Impacted Four-Part Proximal Humerus Fractures

   

  Valgus impacted fractures are recognized by the 90-degree angle between the long axis of the humeral

  shaft and the articular surface of the humeral head with loss of the normal neck shaft angle.5 The tuberosities are displaced laterally from the head of the humerus and slightly proximally.

   

  This fracture configuration results in a low incidence of avascular necrosis compared to that of other four-part fractures because the medial periosteal hinge of soft tissues is intact along the medial and posterior anatomic neck, preserving the blood supply provided by the posterior humeral circumflex

  artery and its ascending vessels.

   

  The reduction maneuver for this fracture requires raising the humeral head back into its anatomic position.

   

  The reduction portal described previously is created, and an instrument such as a blunt elevator or small bone tamp is inserted beneath the humeral head (TECH FIG 4A,B).

   

  The instrument passes through the surgical neck fracture and through the fracture line between the tuberosities, which reliably exists 0.5 to 1 cm posterior and lateral to the biceps groove.

   

  The instrument is tapped with a mallet in a distal to proximal direction, lifting the head fragment into anatomic position (TECH FIG 4C).

   

  The surgical neck fractures and tuberosity fractures are then fixed using the techniques described earlier.

   

   

  P.3729

   

   

   

  TECH FIG 4 • A. Valgus impacted proximal humerus fractures are reduced using a small bone tamp or other blunttipped instrument. B. The instrument is inserted through the fracture line between the greater tuberosity and the lesser tuberosity, which lies posterior to the biceps groove. Position is confirmed with fluoroscopic imaging. C. The bone tamp is impacted in a superior direction, bringing the humeral head into a reduced position. The greater and lesser tuberosities fall naturally into a reduced position after this reduction maneuver.

   

   

  In some cases, there may be significant medial displacement of the lesser tuberosity. In these cases, the lesser tuberosity is reduced using the hook through the reduction portal and fixed with a screw placed in the anterior to posterior direction through the tuberosity into the head.

   

  In most cases, minimal medial displacement of the lesser tuberosity is well tolerated and no fixation is required.

   

   

   

  Pins are cut beneath the skin. Incisions are closed with nylon sutures. A dressing and sling are applied.

   

  PEARLS AND PITFALLS
  	Indications ▪ Successful percutaneous pinning depends on appropriate patient selection. Criteria include good bone stock, minimal to no comminution at the greater

   

  tuberosity fragment, minimal to no comminution at the medial calcar and proximal shaft, and patient compliance.

  • Contraindications include poor bone stock that will not hold pins, comminution of greater tuberosity or proximal shaft fragments, and a noncompliant patient with poor follow-up potential.

 

Positioning ▪ The patient must be lateral enough on the table to obtain unencumbered access to the shoulder and clear fluoroscopic images.

 

Reduction technique

• The location of the reduction portal is critical for maximizing its usefulness during the procedure.

• The surgeon must have a thorough understanding of three-dimensional anatomy as well as interpretation and application of two-dimensional fluoroscopic images.

   

  Pin placement

• Pins should engage the humerus distal to the axillary nerve but proximal to the deltoid insertion to avoid nerve injury.

• The angle of insertion is steep to enter the humeral head and avoid cutting out posteriorly.

• At least two fluoroscopic images in different planes are necessary to confirm successful pin placement.

• A drill guide can be used to protect the soft tissues during pin insertion.

   

  Screw placement

• The deltoid should be spread bluntly and a drill guide used to prevent injury to the axillary nerve in this location. In most cases, insertion will be proximal to the nerve, but precautionary measures should be taken.

• Overtightening the screw with a washer may result in fracture of the greater tuberosity.

• Engaging medial cortex of the proximal shaft gives stability to the screw construct.

 

Intraoperative assessment of stability

• The arm should be internally and externally rotated gently under continuous fluoroscopic imagery after completion of hardware placement. Any motion or suggestion of instability is an indication for open reduction and fixation.

 

 

 

POSTOPERATIVE CARE

 

The operative arm is immobilized in a sling.

 

 

The patient is instructed to begin active elbow, wrist, and hand ROM exercises. Radiographs are checked weekly to monitor for pin migration or loss of fixation.

P.3730

 

Pins are removed as a short procedure in the office or operating room about 3 to 4 weeks postoperatively or when early signs of healing are evident radiographically.

 

Pendulum exercises are initiated 2 to 3 weeks postoperatively, and passive stretching (forward elevation in scapular plane), external rotation, and internal rotation (all in supine position) is initiated when pins are

removed.

 

 

Ideally, pins should be out and motion started no later than 4 weeks postoperatively.

 

Active ROM progressing as tolerated to resistance exercises commences at 6 weeks postoperatively.

 

 

OUTCOMES

Jaberg et al4 reported good to excellent results in 38 of 48 fractures. There were 29 surgical neck, 3 anatomic neck, 8 three-part, and 5 four-part fractures.

Resch et al9 reported results of 9 three-part fractures and 18 four-part fractures. In the four-part fractures, the incidence of avascular necrosis was 11%. Good results correlated with anatomic reconstruction.

Keener et al6 reported a multicenter study of 35 patients—7 two-part, 8 three-part, and 12 valgus impacted fractures. Average duration of follow-up was 35 months. All fractures healed. American Shoulder and Elbow Surgeons (ASES) and Constant scores were 83.4 and 73.9, respectively. Four patients had some residual malunion, and four developed posttraumatic arthritis. Neither of these affected outcome at this early follow-up period, however.

This same group of patients was subsequently followed for an average of 50 months2 (range, 11 to 101 months). Osteonecrosis was present in 10 (37%) of the patients. Only two were symptomatic enough to warrant revision to an arthroplasty. Average ASES score was 82 at this intermediate-term follow-up.

Most studies report very satisfactory results with this procedure.

Patient selection is critical. In published studies, patients are not randomized to percutaneous pinning, but rather, careful patient selection is left to the treating surgeon. Therefore, it can be concluded that this is an appropriate technique in certain patients who meet the outlined criteria.

 

COMPLICATIONS

Nerve injury10 Pin migration Loss of fixation Malunion Nonunion Infection

Glenohumeral joint stiffness

 

 

REFERENCES

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

    

    

2. Harrison AK, Gruson KI, Zmistowski B, et al. Intermediate outcomes following percutaneous fixation of proximal humeral fractures. J Bone Joint Surg Am 2012;94(13):1223-1228.

    

    

3. Hsu J, Galatz LM. Mini-incision fixation of proximal humeral fourpart fractures. In: Scuderi GR, Tria A, Berger RA, eds. MIS Techniques in Orthopedics. New York: Springer, 2006:32-44.

    

    

4. Jaberg H, Warner JJ, Jakob RP. Percutaneous stabilization of unstable fractures of the humerus. J Bone Joint Surg Am 1992;74A:508-515.

    

    

5. Jakob RP, Miniaci A, Anson PS, et al. Four-part valgus impacted fractures of the proximal humerus. J Bone Joint Surg Br 1991;73B: 295-298.

    

    

6. Keener J, Parsons BO, Flatow EL, et al. Outcomes after percutaneous reduction and fixation of proximal humeral fractures. J Shoulder Elbow Surg 2007;16:330-338.

    

    

7. Neer CS II. Displaced proximal humerus fractures. I. Classification and evaluation. J Bone Joint Surg Am 1970;52A:1077-1089.

    

    

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

    

    

9. Resch H, Povacz P, Fröhlich R, et al. Percutaneous fixation of threeand four-part fractures of the proximal humerus. J Bone Joint Surg Br 1997;79B:295-300.

    

    

10. Rowles DJ, McGrory JE. Percutaneous pinning of the proximal humerus: an anatomic study. J Bone Joint Surg Am 2001;83A: 1695-1699.