Special Imaging

Fig. 7.1

Radiographs in a-p (a) and lateral (b) view of a 74 year old patient who fell onto his left shoulder showing a multi-part fracture of the proximal humerus

Fig. 7.2

Although the radiographs (Fig. 7.1) showed the presence of multi-part fracture of the proximal humerus of the left side a MDCT exam of the patient’s left shoulder was performed to get information on the exact number of fragments, the fracture lines as well as whether the humeral head calotte is affected or not. (a–c) show CT-images in axial orientation with (d) and (e) presenting coronal reformats exactly presenting a four-part fracture of the proximal humerus without affecting the humeral head calotte

In general CT is a commonly used imaging modality when it comes to the assessment of traumatic injuries of the shoulder. In comparison to conventional radiography already axial CT images help to increase the accuracy of classifying the fracture adequately as well as help to correctly plan the surgical procedure and to decide for the optimal therapy regimen.

It is known that especially displaced three- or even four-part fractures of the proximal humerus are associated with a high incidence of humeral head avascular necrosis. Thus, these fractures have to be treated adequately depending on the number and dislocation of the fragments [4, 5] so that the extent of the fracture itself as well as number and localisation of the fragments need to be correctly identified. Although the diagnostic cascade after proximal humerus fracture starts with conventional radiography of the affected extremity it is sometimes quite difficult for several reasons (see Chap. 6) to adequately assess fracture fragments and their exact location especially if the lesser tuberosity is affected on plain radiography. Not only in exactly describing the fracture and its extent itself but also in detecting concomitant bony lesions such as fractures of the coracoid process x-rays provide only poor sensitivity. However, for the identification of bony Bankart lesions on conventional x-rays Haapamaki et al. reported a rather good sensitivity [6] which is of great importance since fractures of the glenoid with large fragments might cause an anterior instability of the shoulder joint [7]. Also in this context CT provides superior image quality compared to conventional radiography [8] as described by Haapamaki et al. [6] as well (Figs. 7.3 and 7.4).

Fig. 7.3

The radiographs in a-p (a) and lateral (b) view under suboptimal conditions show an anterior-inferior dislocation of the left shoulder of a 65 year old patient after a fall. The greater tuberosity seems fractured and slightly displaced with a non-axial alignment within the gleno-humeral joint

Fig. 7.4

These radiographs (a) a-p view, (b) lateral view show the status after closed reduction of the left shoulder of a 65 year old patient. A good axial alignment is reached. However the fracture of the greater tuberosity is still visible but seems not as much displaced as in the previous radiographs (Fig. 7.3)

To summarize it is recommended to perform CT of the shoulder including multiplanar reformats and a 3D reconstruction on a routine basis in case of especially complex proximal humerus fractures to be able to adequately evaluate fracture morphology and to assess prognostic factors. So that in general on the basis of the CT images it should be evaluated whether there is valgus or varus position of the calvarium along with a flexion/extension position and/or rotational malposition, if there is an impaction or distraction present, determine the number of fragments as well as the length of the postero-medial calcar and the dislocation at the medial hinge to be able to choose for the optimal treatment.

Magnetic Resonance Imaging (MRI)

In general MRI is known for its superb soft tissue contrast and missing radiation exposure as compared to x-rays and CT so that MR-examinations own a high significance when it comes to musculoskeletal imaging especially as imaging modality for evaluating joints and traumatic joint injuries [9].

The typical disadvantages of MRI especially compared to CT are known as follows: first of all its availability, its cost and the compared to CT significantly prolonged examination times which makes MRI rather useless for acute trauma care.

Performing MRI it is possible to show that a proximal humerus fracture is not just an injury to the bone but is usually associated with injuries to the surrounding tissues such as the rotator cuff (RC) and others.

In the current literature a positive correlation between the severity of proximal humerus fractures and RC lesions had been described by several authors [10, 11]. However, the definite role of the RC injury to the functional outcome after proximal humerus fractures is yet not completely understood, however recent studies in the literature state that RC injuries along with a proximal humerus fracture do not result in significantly worsened functional outcome of the shoulder joint [10, 12].

The domain of CT is the depiction of the osseous changes whereas MRI’s domain lays within the demonstration of soft tissue and its pathological changes. Since due to the increasing patients’ age and activity more and more older people do suffer from proximal humerus fractures possibly presenting with degenerative changes of the RC. Concludingly, in singular cases depending on the clinical evaluation a preoperative MRI might be useful to rule out pathologies e.g. of the RC or to define the extent of soft tissue injury for the exact planning of the surgical intervention [13]. However, 50 % of the patients older than 60 years show signal abnormalities in the RC being consistent with signs of tears [14]. Therefore regarding a screening tool for patients suffering from proximal humerus fractures MRI has not been proven to be a cost-effective economic tool and neither has arthroscopy.

In this context the work of Wilmanns et al. [11] should be mentioned describing a correlation between RC injuries and the proximal humerus fracture type according to the AO classification. Their findings are supported by the results of Fjalestad et al. [15] suggesting that additional RC tears are not caused by degeneration but are rather part of the injury leading primarily to the proximal humerus fracture.

However, reading an MR-exam after proximal humerus fractures with injured soft tissues and of course an abnormal anatomy, does raise some difficulties especially regarding the exact detection of partial and full thickness tears respectively of the RC tendons. In this context Potter et al. [16] described in their study a high detection rate of 98 % for full thickness tears whereas for partial thickness tears only 70 % of the cases were recognized which is equal to results known from ultrasound [13].

Another factor deteriorating MR images is blood in the articular cavity of the shoulder joint especially when it is located in the subacromial-subdeltoid bursa since it may derive from a full thickness tear of the RC, but may also be of secondary character due to posttraumatic bursitis.

In addition in case of proximal humerus fractures MRI should be performed to be able to clarify whether the quality of the RC allows for the implantation of a fracture prosthesis which is considered due to severe soft tissue – as well as bony injuries.

If in the posttraumatic or even post-operative phase when an avascular necrosis (AVN) of the humeral head is clinically or radiographically suspected MRI presents the imaging method of choice to confirm or exclude the diagnosis of an AVN. On MR-images it is possible to assess vitality of the humeral head and the exact extent of the AVN. In case of diagnosis of an AVN also MRI-follow-up exams should be considered to evaluate progressive or stable conditions of the humeral head to be able to adequately react in every case with the optimal treatment (Fig. 7.5).

Fig. 7.5

Since the radiographs pointed out that the greater tuberosity was fractured a lesion to the rotator cuff was suspected so that the decision was made to perform a MR-examination of the shoulder. The upper row of images presents T2-weighted STIR images in coronal orientation with corresponding T1-weighted coronal images in the lower row. On the STIR-sequence a bone marrow edema of the fractured but not displaced greater tuberosity is visible along with effusion in the bursa subdeltoidea and subacromialis as well as a slight hyperintensity of the insertion of the supraspinatus tendon with corresponding hypointensity on T1-w images suspicious for traumatic lesion of the rotator cuff

If posttraumatically a lesion of the plexus brachialis is suspected MR-images are definitely helpful to demonstrate first of all the continuity of the plexus which is of great prognostic value, but also to rule out significant injury to soft tissue of the shoulder joint such as hematomas especially along the anatomic course of the plexus brachialis. In this context it should be mentioned that plexus brachialis lesions are of rather rare incidence in “normal” proximal humerus fractures but might occur in cases of motor cycle accidents (Fig. 7.6).

Fig. 7.6

The upper 2 MR-images show a proton density fat saturated axial view onto the left shoulder (see Figs. 7.3, 7.4 and 7.5). On these axial MR-images effusion is recognizable but here in the posterior part of the shoulder joint along the capsule as well as in the bursa subcoracoidea. As far as possibly evaluated no greater lesion of the glenoid is visible. The lower row presents T2-weighted sagittal images of the shoulder showing the fractured slightly displaced greater tuberosity along with the slight distraction of the supraspinatus tendon and surrounding fluid

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