Operative Techniques in Orthopaedic Surgery (4 Volume Set) 1st Edition

372. Percutaneous Pinning for Proximal Humerus Fractures

Leesa M. Galatz

DEFINITION

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

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

images These “parts” first were described by Codman, and led to development of the Neer classification,6 which is commonly used today.

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

images Proximal humerus fractures are classified as two-, three-, or four-part fractures according to the Neer classfication.6

images 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.

images The type of fracture and degree of displacement, as well as patient considerations, all factor into surgical decisionmaking.

images

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.

ANATOMY

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

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

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

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

images 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.

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

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

images 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 proximalmost aspect of the groove, providing about 85% of the blood supply to the humeral head.1

images 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.

images 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.

images

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.

PATHOGENESIS

images Proximal humerus fractures occur in a bimodal distribution.

images 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.

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

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

NATURAL HISTORY

images Eighty-five percent of proximal humerus fractures can be treated nonoperatively.6

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

images 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.

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

images 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%.7

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

images 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

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

images 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.

images 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.

images Other important aspects of the history include.

images Previous history of injury to the affected shoulder

images Previous shoulder function

images History of numbness or tingling in the affected extremity

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

images Patients often hold the shoulder inferior on the affected side.

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

images 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).

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

IMAGING AND OTHER DIAGNOSTIC STUDIES

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

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

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

images A CT scan is helpful in many cases and should be obtained if there is any question regarding the 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.

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

images

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.

images

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.

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

DIFFERENTIAL DIAGNOSIS

images Acromioclavicular joint separation

images Glenohumeral joint dislocation

images Humeral shaft fracture

images Scapulothoracic dissociation

images Elbow and wrist fractures (may coexist)

NONOPERATIVE MANAGEMENT

images Minimally displaced fractures can be treated nonoperatively.

images Displacement at the surgical neck is well tolerated.

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

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

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

images Displacement of the greater tuberosity is less well tolerated.

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

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

images 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.

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

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

images 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.

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

SURGICAL MANAGEMENT

Preoperative Planning

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

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

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

images 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 (required open approach).

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

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

images Good bone quality

images Substantial fracture fragments with minimal comminution of the tuberosities

images Minimal or no comminution at the medial calcar region

images Minimally invasive fixation is not appropriate for noncompliant or unreliable patients. This procedure should be performed only in patients committed to consistent follow-up in the postoperative period.

images The pins require close surveillance in the early postoperative period.

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

Positioning

images Percutaneous pinning is performed with the patient in the straight supine or 10to 15-degree beach chair position (FIG 5).

images This allows easy intraoperative evaluation with C-arm fluoroscopy.

images

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.

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

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

images 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 anteroposterior plane without the table obstructing the view.

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

images The entire upper extremity is draped free.

Approach

images Closed fracture reductions are performed with the aid of a “reduction portal” (FIG 6).2

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

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

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

images Medially, the biceps tendon can be palpated.

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

images By sweeping posterior and superior, the greater tuberosity and its extent of displacement can be palpated.

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

images 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.

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

images

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 Carm imagery. 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.

images The arm is held in neutral rotation.

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

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

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

images 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.

TECHNIQUES

SURGICAL NECK FRACTURE

Reduction

images  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.

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

images  The reduction maneuver involves flexion, adduction, and possibly some slight internal rotation to relax the pull of the pectoralis major muscle3 (TECH FIG 1).

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

images  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.

images 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).

Fixation

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

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

images

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.

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

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

images 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.

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

images One pin should enter lateral to the biceps in a primarily anterior-to-posterior direction.

images Another pin should enter further laterally in a primarily lateral-to-medial direction.

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

images

images

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.

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

images Pins are cut below the skin to prevent pin site infection (TECH FIG 2D).

images The reduction portal is closed with interrupted nylon sutures.

images A soft dressing and sling are applied.

THREE-PART GREATER TUBEROSITY FRACTURES

Reduction

images  Deforming forces influencing displacement of threepart 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.

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

images  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 inferior and anterior into a reduced position.

Fixation

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

images The screw is placed through the tuberosity fragment distal to the cuff insertion through bone on the lateral cortex (TECH FIG 3A).

images The proper location is confirmed with fluoroscopic imaging.

images  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).

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

images

images

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. Over-tightening should be avoided to prevent fracture of the greater tuberosity fragment. F. Screw and washer insertion.

images 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).

images 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.

images  Pins are cut beneath the skin.

images  Incisions are closed with nylon interrupted sutures.

images  A dressing and sling are applied.

VALGUS IMPACTED FOUR-PART PROXIMAL HUMERUS FRACTURES

images  Valgus impacted fractures are recognized by the 90degree 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.4 The tuberosities are displaced laterally from the head of the humerus and slightly proximally.

images This fracture configuration results in a low incidence of avascular necrosis compared to that of other fourpart 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.

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

images 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).

images 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.

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

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

images

images

TECH FIG 4  A. Valgus impacted proximal humerus fractures are reduced using a small bone tamp or other blunt-tipped 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.

images  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.

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

images  Pins are cut beneath the skin.

images  Incisions are closed with nylon sutures.

images  A dressing and sling are applied.

PEARLS AND PITFALLS

images

POSTOPERATIVE CARE

images The operative arm is immobilized in a sling.

images The patient is instructed to begin active elbow, wrist, and hand ROM exercises.

images Radiographs are checked weekly to monitor for pin migration or loss of fixation.

images 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.

images 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.

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

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

OUTCOMES

images Jaberg et al3 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.

images Resch et al8 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.

images Keener et al5 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 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.

images 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

images Nerve injury9

images Pin migration

images Loss of fixation

images Malunion

images Nonunion

images Infection

images Glenohumeral joint stiffness

REFERENCES

· 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.

· 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.

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

· 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.

· 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. Epub 2007 Feb 22.

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

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

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

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



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