Hill Sachs Lesion

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Original Editors - Lien Hennebel

Top Contributors - Jelle Van Hemelryck, Lien Hennebel, Leana Louw, Pauline Bouten, Simisola Ajeyalemi, Uchechukwu Chukwuemeka, Lucinda hampton, Shreya Pavaskar, Admin, Kim Jackson, Rachael Lowe, Fasuba Ayobami, Wanda van Niekerk, Nupur Smit Shah, 127.0.0.1 and Claire Knott  

Search Strategy

Databases used: Pubmed, Web of science, Google scholar, Pedro.
The following search terms were used to search the different databases: Hill Sachs lesion treatment, Hill Sachs deformity, (Conservative) treatment Hill Sachs lesion, Bone loss glenohumeral dislocation, Hill sachs defect.

Definition/Description

The glenohumeral joint is the most commonly dislocated joint in the human body and 90% of shoulder dislocations are anterior. The reason for this is that the scapula is oriented about 30 degrees anterior and this to the coronal (frontal) plane of the body. Because of this the glenohumeral joint with the humerus is orienting anterior to the glenoid.

CDR. Matthew, T. Provencher et al. Described a Hill-Sachs lesion as followed : The Hill-Sachs lesion is a compression fracture of the posterosuperolateral humeral head that occurs in association with anterior instability or dislocation of the glenohumeral joint.

When a trauma takes place, an anterior shoulder dislocation can cause a head impression fracture what we call a Hill sachs lesion. The posterolateral aspect of the humeral head impacts on the anterior glenoid in the dislocated position, what makes the glenohumeral joint unstable (Shoulder Instability).

About 90% of shoulder dislocations are anterior, so in some cases there could be a posterior dislocation what can cause a reverse Hill sachs lesion. This lesion may be present on the anterior aspect of the humeral head.

Several classifications and grading systems have been described for Hill-Sachs lesions, but there still is some controversy among which is most supported. Although the classifications and grading systems can be useful in clinical decision making, especially with larger lesions, they have not yet proved to be helpful in determining successful management strategies.(Level of evidence 2A) 

One way to grade a Hill-Sachs lesion is how J.J. Calandra et al. did it. They described the lesion arthroscopically in 3 grades (Level of evidence 2B):

• Grade 1: there is a defect in the articulair surface down to, but not including, the subchondral bone.
• Grade 2: the lesion includes the subchondral bone
• Grade 3: the lesion signifies means a large defect in the subchondral bone.

A, Illustration of an engaging Hill-Sachs lesion (dark gray area).
B, With the shoulder in a position of function or in abduction and external rotation, the lesion is oriented parallel with the anterior glenoid and thus engages it.
C, Illustration of a nonengaging lesion (dark gray area), which is created in a nonfunctional position.
D, When the shoulder is abducted and externally rotated, the lesion is not oriented parallel to the glenoid and thus does not engage.

Redrawn with permission from Burkhart SS, De Beer JF: Traumatic glenohumeral bone defects and their relationship to failure of arthroscopic Bankart repairs: Significance of the inverted-pear glenoid and the humeral engaging Hill-Sachs lesion. Arthroscopy 2000;16[7]:677-694.)

Clinically Relevant Anatomy

The term 'Hill-Sachs Lesion', refers to the glenohumeral joint , which is a synovial ball-and-socket diarthroidal joint. It is the articulation between the fossa glenoidalis of the scapula and the caput humeri. It’s common known that the shoulder joint has a real loose capsule and that therefore the risk for dislocation is severely high. 
* The bony part: the scapula with his glenoid and the humeral head from the humerus; The humerus is the “ball” of the ball-and-socket joint. This one is located in the “socket” (glenoid) which forms the shoulder joint. The scapula is a triangular shaped bone that forms the “socket” in the joint.
* The fibro cartilaginous structure surrounding the glenoid, namely the labrum; The labrum makes sure there is enough contact between the surface of the glenoid and the humeral head. There is a concavity compression mechanism which plays an important role in the stability of the shoulder. The less contact there is, the more chance there is for dislocations. 
* The capsule and ligamentous structures: Glenohumeral Ligaments (pars superior, media and inferior), which are meant for the strengthen of the capsule. Coracohumeral Ligament: is also meant for the strengthen of the capsule. Transversal humeral ligament: is meant for M. Biceps Brachii
* Muscles: Abductors: M. deltoideus and M. Supraspinatus Adductors: M. Pectoralis Major Flexors: M. Deltoid Rotator Cuff (very important for the stability of the art humeri): M. supraspinatus, M. infraspinatus, M. Teres Minor, M. Subscapularis Extensors: M. Deltoid, M. Triceps Brachii, M. Teres Major, M. Latissimus Dorsi Internal Rotators: M. Teres Major, M. latissimus dorsi, M. Subscapularis, M. Pectoralis Major External Rotators: M. Teres Minor and M. Infraspinatus. 
* Bursae: There are eight bursae in the shoulder complex. This is because of the high amount of muscles on the shoulder. They make sure there is a smooth contact between the muscle and the underlying structure. The biggest one in the body is the subacromial.

Epidemiology and etiology

Etiology

Anterior shoulder instability is considered as a risk factor for Hill sachs lesions. In their study, J.J. Calandra et al. found 47% of the lesions in their patients to be associated with the initial shoulder instability (Level of evidence 2B). They concluded that there research had the same results as the previous studies fromHovelius et al. and Simonet & Cofield et al.

In 2006 Widjaja et al. (Level of evidence 2B) stated that there is a strong correlation between the Bankart and the hill sachs lesion. They found that when someone has either of those lesions he is 2.5 times more likely to have the other as well. But the correlation found in this study couldn’t be considered significant due to small study numbers.

Later in 2013 Horst et al. (Level of evidence 2B) did a high quality MRI study in order to investigate the co-occurrence between Bankart and Hill Sachs lesions. After their study they stated that when someone has one or the other lesions, he or she is 11 times more likely to have suffered the associated injury. So having a Bankart lesion can be considered a risk factor for developing/having a Hill Sachs lesion.

There also is a very strong association between a combined engaged Hill-Sachs lesion and anterior glenoid bone loss in case of recurrent instability according to DS. Kim et al.(Level of evidence 3B)

Epidemiology

The true incidence of Hill-Sachs lesions is unknown. However, they are associated with approximately 40% to 90% of all anterior shoulder instability events. The incidence may be as high as 100% in patients with recurrent anterior instability, stated CDR. Matthew T. Provencher et al. (Level of evidence 2A)
K. Christos et al. investigated 127 patients with traumatic acute and chronic anterior shoulder instability prospectively. A Hill-Sachs lesion was found in 15 cases in the group with acute dislocations (65.21%) and in 97 cases in the chronic recurrent instability group (93.26%). So after their study, they stated that The incidence of shoulder lesions increases with time because the initial dislocation and secondary lesions are more common in patients with chronic instability. (Level of evidence 2B)

Mechanism of Injury / Pathological Process

The glenohumeral joint is the most commonly dislocated joint in the human body and 90% of shoulder dislocations are anterior. The reason for this is that the scapula is oriented about 30 degrees anterior and this to the coronal plane of the body. Because of this the glenohumeral joint with the humerus is orienting anterior to the glenoid.

When a trauma takes place, an anterior shoulder dislocation can cause a head impression fracture what we call a Hill sachs lesion. The posterolateral aspect of the humeral head impacts on the anterior glenoid in the dislocated position, what makes the glenohumeral joint unstable (Shoulder_Instability).

90% of shoulder dislocations are anterior, so in some cases there could be a posterior dislocation what can cause a reverse Hill sachs lesion. This lesion may be present on the anterior aspect of the humeral head.

Characteristics/Clinical Presentation

Shoulder dislocation don’t occur isolated. It causes damage to different tissues surrounding the glenohumeral joint like shoulder ligaments, rotator cuff tendons and the joint capsule. But the bone and cartilage of the humeral head can also be affected. This occurs when the round humeral head is forcibly impacted on the edge of the glenoid, which causes compression fractures in the humeral head. This forms a dimple structure on the articular surface of the humerus, and is called a Hill-Sachs lesion. It can be seen on MRI, CT-scan, but is difficult to see on an x-ray. 

 We can order this humeral head compression fractures according to the percentage of humeral head involvement
• minor defect: less than 20% of the humeral head is involved;
• moderate defect: between 20% and 45% of the head is involved;
• severe defect: more than 45% of the head is involved.
The size of the lesion is in most cases related to the amount of times a dislocation took place 

Figure 1 illustrates how the percentage of the humeral head, which is involved, is calculated. Next to this percentage, a Hill-Sachs lesion is also characterized by its depth ('d' on figure 1) and its size ('s' on figure 1).

 

Figure 1: preoperative double contrast CT arthrography of a 20 year old patient. 

When we diagnose a Hill-Sachs defect, we can be sure that there was a complete dislocation of the humeral head out of the socket, and that it was not just a subluxation. 
A Hill-Sachs lesion occurs in about 50 percent of the first-time shoulder dislocations. For people with a shoulders dislocations’ history (= shoulder instability) you can almost always see these humeral head compression fractures.  There is a link between bone loss on either the glenoid side or the humeral side and recurrent shoulder instability during activities. 

Differential Diagnosis

It is important to note that below the level of the coracoid the humeral head normally flattens out posterolaterally (also known as Pseudo-Hill-Sachs lesion), and this should not be misinterpreted as a Hill-Sachs lesion. [14]
Both a Hill-Sachs lesion (fig 1) as a Bankart lesion (fig 2) (link to: http://www.physio-pedia.com/Bankart_lesion) of the glenoid can be the result of a shoulder dislocation. They often occur together. It is important to inspect the anterior glenoid rim and labrum carefully, to see if there is a potential Bankart Lesion. [14][15]
Fig 1: Hill Sachs lesion Fig 2: Bankart lesion 
Savoie (2014) describes 3 other injuries that occur commonly with Hilll-Sachs lesion:
• Humeral avulsion (HAGL) and mid capsular tears
• Floating anterior capsule

Anterior glenohumeral ligamentous pathology and glenoid bone loss [16]
Anterior shoulder dislocation is more common, but sometimes a posterior shoulder dislocation takes place. If that’s the case and there is some damage to the cartilage and bone, we can speak of a Reverse Hill-Sachs lesion. This lesion can be seen on the anterior-superior aspect of the humeral head. [15][16][17]

  

Diagnostic Procedures

To diagnose pathologies of the humeral head, osseus glenoid and labrum, a number of imaging techniques have been described.
In the acute phase, plain radiography can detect bony lesions of the humeral head related to shoulder instability. Radiographic techniques most advandageous for initial evaluation of glenohumeral instability are the Grashey view (anteroposterior view of the shoulder) with internal and external views, the scapular 'Y' view (transcapular view of the shoulder) and the Garth view (x-ray beam caudally from a standard anteroposterior view). When the mobility of the patient allows, axillary, axillary with exaggerated external rotation and West Pont views can be added. In practice, for specific cases (when clinical examination is difficult), sometimes dynamic stress tells more about the instability of the shoulder. The combination of these views is an important first step at effectively evaluating both the glenohumeral relationship as well as osseous pathology on both the humerus and the glenoid. [2][18]
Also ultrasound can detect and localise a compression fracture in Hill Sachs lesions. The advantage of this method is its cost effectiveness and its minimal exposure to excessive radiation (see plain radiographies or CT scan). It also provides a comfortable position for the patient. [18],[19].
Firstly, with the arm in a neutral position, the convexity of the humerus in the posterior transversal plane is examined. Special attention should be payed to the layer of cartilage. Secondly, the patient has to flex the arm at a 90-degree angle, to facilitate the examination of the total posterosuperior convexity of the humerus. In Hill Sachs lesions, a triangular depression in the contour of the humerus will be apparent.[3].
A study of Pancione et al. (1997) compared the advantages of using ultrasound versus CT scans for the examination of shoulder dislocations. They showed that ultrasounds demonstrated a higher sensitivity (95,6%) and specificity (92,8%) for the detection of Hill Sachs lesions. [5] Recently, Pavic et al. (2013) found a statistically significant difference between ultrasound and MRI stating that MRI is more accurate than ultrasound. (level of evidence: 3) [20]
MRI is useful to detect a pathology of the soft tissue and to determine the amount of humeral and glenoid bone loss. A double-blind, prospective study by Denti et al.,15 patients underwent MRI with a sensitivity of 60%, specificity of 80% and accuracy of 87´%. [21]
CT scans make it possible to reliably asses the location and depth of the humeral lesion. Based on the latter, surgical decision is made. Overall, sagittal- and axial-plane measurements are more accurate for evaluation of these defects than the coronal plane. [19]

Outcome Measures

add links to outcome measures here (see Outcome Measures Database)

Examination

A major (passive) test to physically examine a clinically important Hill-sachs injury is the bony apprehension test. The therapist brings the arm in a 45 degrees abduction and a 45 degrees external rotation. Pressure is applied with the hand on the caput of the humerus to anterior. The test is positive if pain is felt, or if the muscle contracts by reflex in the case of a (sub)luxation. [1]

Apprehension test: http://www.physio-pedia.com/Apprehension_Test
jobes relocation test: http://www.physio-pedia.com/Jobes_Relocation_Test
In addition to a positive apprehension test, crepitus (palpalable and audible) and catching may be felt during active and passive abduction and external rotation. [2] Also, an audible or palpable clunk in these positions or an instable feeling during mid-ranges of these motions indicate a possible lesion.

Medical management

In the setting of humeral bone loss (Hill-Sachs) injury, treatment can be directed at the restoration of the glenohumeral articular arc with either glenoid-based solutions, humeral-based strategies, or a combination. These strategies include open as well as arthroscopic procedures, depending on the extent of the pathology. [2]
Most of the Hill-Sachs injuries are treated with glenoid-based bone augmentation techniques. Treating the glenoid defects is often the solution to the glenohumeral instability. Of these techniques, the (open) Latarjet procedure remains the most frequently applied procedure. This procedure includes a variety of methods. The technique whereby the bone from the processus coracoideus is used as an augment to the anteroinferior glenoid bone loss is the most common. By reforming the concavity and width of the glenoid, a Hill-Sachs lesion does not influence the anterior glenoid rim of unstable shoulders. This method is successful in preventing the overtime instability, proving at least two prospective cohort studies by Hovelius et al. (2004) and Schroder et al. (2006) (evidence based level: 1B). However, shoulder arthrosis and loss of function were negative consequences. [2][22][23]

The majority of Hill-Sachs defects can successfully be solved with glenoid-based strategies, however some of the Hill-Sachs injuries, especially when the glenoid is not touched, require a direct treatment of the injury. Generally taken, the Hill-Sachs deformity can be managed by two techniques: arthrosocopic and open techniques.[2]

Arthroscopic techniques include the ‘Remplissage procedure’, a method whereby the defect is filled with soft tissue, usually from the infraspinatus tendon. A second arthroplasty method is the percutaneous humeroplasty, a technique that fills the lesion by using a bone tamp brought into a drilled osseus window 180 degrees from the lesion. The advantage of this procedure is that no rotational osteotomy of the humeral head is needed and the humeral head can be resored without transpositioning the soft tissue. Limitations of this technique are moderate-sized defects and the lack of management of osteochondral defects. Other procedures where arthroscopy intervenes are techniques that use various small bone plugs. [2]

Open humeral bony techniques include autologous bone plugs, size-matched osteoarticular allografts and rotational humeral osteotomy. The latter, a procedure that includes an osteotomy of the surgical neck and rotates the humeral head for 25 degrees, is not the best chosen method nowadays, given the related risks and the success rates of more recent procedures. The osseus humeral allograft bone plug technique uses a size-matched humeral bone plug of a donor. It is an open procedure because it is performed trough a delto-pectoral approach or a deltoid-splitting approach. Advantages of this procedure are its minimal exposure and the fact that the head of the humerus remains in the capsule. A downside of this resurfacing technique is its limitation to small and moderate lesions and the risk of using cadaveric tissue. [2]

Physical therapy management

Several studies have shown that when the number of dislocations increases, the incidence and size of Hill sachs lesion also increases. It can be a cause of instability and in this case surgical treatment is considered. Frequently, authors consider that surgical treatment of recurrent shoulder dislocation is indicated when someone had more than five shoulder dislocations. [11][12]

But most of the time a Hill-Sachs lesion can be neglected, certainly if there is a minimum of glenoid bone loss and without significant involvement of the humeral head. There is no need for surgical treatment, but important is handling the instability.[11] 
The non-operative rehabilitation of the unstable shoulder consists about seven key factors: [17]
Onset of pathology (in this case: traumatic event)
Degree of instability (in this case: dislocation)
Frequency of dislocation (in this case acute)
Direction of instability (in this case: anterior)
concomitant pathologies (in this case: Hill sachs lesion)
Neuromuscular control
Activity level
In the non-operative rehabilitation program of the traumatic dislocation of the shoulder, it's important to consider all these seven factors and thus also with the concomitant 'Hill sachs lesion': rehabilitation program of the shoulder.( http://www.physio-pedia.com/Rehabilitation_program_of_the_shoulder) [17]

Differential Diagnosis

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Key Evidence

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Resources

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Case Studies

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References

Books
Management of the unstable shoulder: arth and open repair. H 18: Hill-Sachs Injuries of the Shoulder: When are these important and how should I manage them? Provencher, M, Rose, M., Peace, W. (2011). pp. 235-252.
Examination and diagnosis of musculoskeletal disorders. Castro, Jerosch & Grossman. (2001). Georg Thieme Verlag, Germany.

Sites
http://www.eorif.com/hill-sachs-lesion
http://orthodoc.aaos.org/
http://orthopedics.about.com/
www.wikiradiography.com