Suspensory Complex
Michael J. Gardner, Bryan T. Kelly, and Dean G. Lorich
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capsular avulsions seen in pure shoulder dislocations and typically involve a larger fragment due to humeral head impaction rather than a capsular avulsion. In type II frac- tures, the fracture line is transverse or slightly oblique at the articular surface, and exits the lateral border of the scapula inferiorly. When a significant portion of the articu- lar surface is involved, inferior subluxation of the humeral head may be present. The inferior fragment may be pulled and angled distally by the long head of the triceps tendon.
Type III fractures occur following a medially directed force
with a cephalad component, and the superior one third of the glenoid fossa is affected. The fracture line courses superiorly and usually exits medial to the coracoid at the superior scapular border, and may follow the epiphyseal scar. The direction of the force vector in these injuries often disrupts the superior elements of the shoulder girdle, and may lead to fracture of the clavicle or acromion, or acromioclavicular (AC) separation. Type IV fractures result from a direct medial force. The glenoid is fractured cen- trally, and the fracture line extends medially to the medial
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Solutions for Complex Upper Extremity TraumaFigure 3–1 The classification system of Ideberg and Goss for fractures of the glenoid.
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border of the scapula. Type V fractures involve a type IV transverse fracture component with associated superior or inferior fragments as seen in types II and III fractures. Type VI patterns, added by Goss, are comminuted fractures of the glenoid fossa.
We have found this fracture classification useful for descriptive purposes only. The surgical approach follows common sense and logical biomechanical principles, and each fracture must be evaluated individually as no single approach applies for all fractures in a given class.
Prognosis based on fracture type has also not been fully correlated, and most available data are anecdotal or small single-surgeon series.
Glenoid Neck Fractures
Fractures of the glenoid neck frequently occur following direct lateral impact on the humeral head, and may occur in concert with other bony or soft tissue disruptions around the shoulder girdle. When double disruptions of the superior shoulder suspensory complex (SSSC) occur, unique biomechanical issues must be considered. The first consideration when evaluating glenoid neck frac- tures is the inherent stability or lack thereof, for which associated lesions must be considered. These combina- tion injuries are complex and will be discussed further in a later section. Additional specific factors relative to the glenoid neck have significant implications on treatment approaches, however, regardless of associated injuries. In particular, whether or not the fracture is deemed to be stable, malalignment of the glenoid neck may lead to per- manent malunion and can have a detrimental effect on shoulder function. The force vector created by the deltoid during initial abduction is a shear force across the glenoid, which is stabilized by the compressive forces of the rotator cuff across an anatomically positioned glenoid. Alteration of this axis results in conversion of the rotator cuff force to shear in the case of inferior angulation, or in a short- ened lever arm in the case of a medially displaced glenoid neck fracture.13For this reason, operative reduction and stabilization of glenoid fractures with evidence of inferior angulation or medial displacement is recommended.13–17 Measurements of angulation must be derived in relation to the scapular body. Some surgeons have advocated the threshold of 40 degrees of angulation or 10 mm of transla- tional displacement as a surgical indication.3,13,18,19Despite these empiric recommendations, the clinical evidence sup- porting these indications is sparse. We have found the glenopolar angle (GPA) a useful tool for this purpose. In ad- dition, several authors have correlated the GPA to outcomes after either conservative or operative treatment.15,17,20,21To obtain the GPA, an anteroposterior (AP) x-ray of the scapula is obtained. Two lines are drawn: the first between the su- perior and inferior margins of the glenoid, and the second
between the superior glenoid and the most inferior point of the scapular body (Fig. 3–2). The GPA is normally between 30 and 45 degrees, and as the glenoid becomes more mis- aligned inferiorly by the pull of muscular attachments and the weight of the extremity, the angle decreases. When the angle is 20 degrees or less, clinically significant angulation exists and we recommend operative intervention based on this angulation alone.
Treatment
Truly nondisplaced glenoid fractures, which have been adequately evaluated radiographically, may be successfully treated nonoperatively. In these cases, we recommend the use of a sling for comfort, and early dependent passive shoulder mobilization, such as pendulum exercises, to minimize posttraumatic shoulder stiffness. Frequent radi- ographic follow-up is required to ensure the fracture does not displace.
The goal of operative reduction and fixation is to cor- rect bony deformity, to prevent chronic glenohumeral instability, and to restore articular congruity to mini- mize the risk of degenerative joint disease. Due to the relative paucity of long-term clinical outcome data, strict guidelines for operative indications do not exist.
3 Treatment of Glenoid Fractures and Injuries to the Superior Shoulder Suspensory Complex
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Figure 3–2 The glenopolar angle for assessing glenoid neck fractures accounts for the relative inferior tilt of the articular surface. Normal ranges from 30 to 45 degrees. Less than 20 degrees may be a good indicator for operative intervention.
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Previous authors have advocated surgical treatment when at least 5 mm of articular displacement was pres- ent, or with persistent subluxation of the humeral head,1,4,12,22,23although these parameters are based on very little scientific data. Instability can be anticipated if at least one quarter of the anterior fossa or one third of the posterior fossa is displaced.
Authors’ Recommended Treatment
The surgeon should not rely solely on the fracture clas- sification to dictate surgical approach and fixation techniques. Each fracture should be evaluated for the optimal fixation construct based on ideal biomechan- ics, and the surgical approach tailored accordingly.
However, the fracture type and location of the major fragments does allow for a general approach to the in- jury. Type Ia fractures are best visualized anteriorly through a deltopectoral approach, which gives adequate access to the anterior glenoid rim. In type Ib fractures, a limited posterior approach to the glenohumeral joint allows for reduction and fixation of the posterior glenoid fossa with small fragment screws.
The remainder of the fracture types (types II–VI) in- volve medial extension of the fracture into the scapular body, and require wider exposure for anatomic reduction and fixation individualized to the fracture. As a general rule, fractures that exit superiorly may be treated with an anterior approach, and inferior fractures are best treated with a posterior approach. For fractures with superome- dial extension, a deltopectoral approach may be adequate to control and stabilize the fragment depending on its size. Due to the posterior position of the posterior border of the acromion, visualization of the superior fragment is usually better through an anterior approach. The deform- ing forces of the long head of the biceps and the conjoint must be counteracted during reduction. Interfragmentary 2.7- or 3.5-mm screws are used for final fracture stabiliza- tion. If plates are necessary for fixation, an anterior ap- proach is suboptimal due to limited options of good bone stock for screw purchase posteriorly.
When the fracture line extends far medially, we pre- fer a posterior approach, often supplemented with an accessory superior approach. This technique involves placing a 4.0-mm Schanz pin in the coracoid as a joystick to facilitate reduction. Screws may then be placed from superior to inferior from the coracoid into the scapular spine (posteriorly) or distally into the stout glenoid neck and lateral body depending of the fracture pattern. The posterior approach for superior or medial fracture exten- sion should involve reflecting the posterior head of the deltoid inferiorly and exposing the supraspinous fossa to directly address the fracture. Care must be taken to expose and protect the suprascapular nerve when
performing this exposure, and mobilization of the nerve may be the limiting factor in the extent of exposure.
Most fractures with medial or inferior extension require a posterior approach to the scapula to visualize, reduce, and stabilize the inferior fragments through the scapular body. Position the patient in a lateral decubitus position with the affected extremity upward. Make a slightly oblique vertical incision, starting from the lateral one third of the scapular spine, angling slightly medially, and ex- tending distally for 15 cm. The posterior head of the deltoid is then reflected from the scapula, and the interval between the infraspinatus and teres minor is identified lat- erally. The infraspinatus may be mobilized subperiosteally from the inferior scapular fossa as necessary, taking care to protect the suprascapular nerve on its undersurface. The infraspinatus insertion may be partially released from its tendinous insertion, and later repaired, to increase expo- sure. A T-shaped capsular incision is then made to expose the articular surface (Fig. 3–3). If visualization and ade- quate control of all the fracture fragments are not possible through this interval, dissection superior to the spine may allow for complete exposure.
Reconstruction of the articular surface is performed un- der direct visualization, using Kirschner wires (K-wires) for provisional fixation followed by interfragmentary screws (Fig. 3–4). A Schanz pin or threaded K-wire may be inserted into the dense lateral neck or subchondral bone to assist in reduction of the fracture if a large enough frag- ment is present. A 2.7-mm reconstruction plate placed along the solid bone stock of the lateral scapular is useful to maintain the reduction, and an additional 3.5-mm reconstruction plate may be contoured and placed on the posterior border of the lateral scapula to allow a 90–90 construct (Fig. 3–5). It is important to recognize the optimal anatomic locations that allow for good screw purchase (Fig. 3–6). Following internal fixation, the deltoid fascia should be repaired securely to its anatomic position using drill holes through the scapular spine.
When the fracture extends more directly inferiorly, we prefer a more limited posterior approach to the glenoid as described by Brodsky.24,25Abduction of the arm elevates the posterior head of the deltoid and may eliminate the need for extensive deltoid release. The interval between the infraspinatus and teres minor is developed, and release of the infraspinatus is limited to minimize the risk of denervation. The posterior glenoid is exposed and reduction and fixation proceeds as previously described.
It is critical when using this limited approach to avoid injury to the axillary nerve, which migrates superiorly with humerus abduction.26
Glenoid neck fractures often occur in combination with injuries to other superior structures of the shoulder girdle, and the fracture infrequently extends more medi- ally. Thus, a limited posterior approach usually affords
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Figure 3–3 (A–D)The preferred approach for most fractures of the glenoid is posteriorly through the infraspinatus-teres minor interval.
(From Kavanagh BF, Bradway JK, Cofield RH. Open reduction and internal
fixation of displaced intra-articular fractures of the glenoid fossa. J Bone Joint Surg Am 1993;75:479–484. Reprinted by permission.)
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adequate exposure without medial dissection or extensive release of the deltoid or infraspinatus. With the fracture exposed, the neck can be disimpacted using a small eleva- tor or bone tamp. A contoured 3.5-mm reconstruction
plate may be placed on the posterior surface of the neck and distally along the lateral border of the scapula. If a significant defect remains after disimpaction, bone graft may be placed medially to the neck, and locking screws should be considered to buttress the reduced glenoid fragment.
Results
Scapular fractures are relatively rare injuries, and the vari- ety of concomitant injury patterns about the shoulder girdle has led to a multitude of small heterogeneous case series in the literature.1,3,4,7,12,27–29Very few comparative trials exist, and it is still not completely clear which injuries are best treated by which method. It does appear that the majority of glenoid fractures, and particularly gle- noid neck fractures, may be treated nonoperatively with the expectation of return of good shoulder function.12,30–33 When significant displacement of the articular surface is present, nonoperative treatment generally leads to poor results,13,22,33,34and surgical reconstruction is rec- ommended. Leung et al7reported on 14 patients treated operatively using a deltopectoral or a limited posterior approach. All patients had good or excellent outcomes, both subjectively and objectively using the Rowe shoulder scoring system. In one of the largest series, Mayo et al4 evaluated the functional outcomes after surgical treat- ment of 27 displaced glenoid fractures, and found 22 of 27 patients (81%) had good or excellent results. Eighteen
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Solutions for Complex Upper Extremity TraumaFigure 3–4 Case example showing articular reconstruction using a small fragment lag screw posteroinferiorly into the dense bone of the coracoid.
Figure 3–5 (A)Following a posterior approach, reduction and fixation may be performed with the use of a K-wire, a reduction clamp, and a re- construction plate. (B)In this case, the fracture extended inferiorly and
was stabilized with plate fixation along the lateral border and posteriorly with fixation into the spine and coracoid.
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patients (67%) had no pain, but only 6 (22%) regained full shoulder motion, and the most common deficit was in external rotation. Schandelmaier et al23 evaluated 22 fractures treated operatively which were displaced at least 5 mm at an average follow-up of 10 years, and reported good overall results. Other series have generally found similarly good results following surgical treatment of displaced glenoid fractures.1,3,28Unfortunately, many studies of both conservative and surgical treatment do not, however, accurately quantify fracture displacement or stratify patients accordingly, and it is difficult to draw strong conclusions on treatment recommendations from the available literature.
Glenoid neck fractures often settle in an impacted and stable position. However, inferior angulation may lead to malunion and impair proper shoulder function. Romero et al17found significant differences in outcomes using an angulation threshold of a GPA of 20 degrees. Most patients who complained of moderate or severe pain had a GPA of less than 20 degrees, several of whom had severely limited range of motion. On the contrary, the majority of patients who had mild or no pain had a GPA of 20 degrees. Inter- estingly, half of the patients with malalignment (GPA 20 degrees) had no associated clavicle or AC joint injury, implying that fracture alignment or instability can occur and lead to a poor result without an associated clavicle injury.17Other authors have confirmed high correlations between the GPA and functional shoulder outcomes.14,15