Hill Sachs Lesion

Original Editors - Lien Hennebel as part of the Vrije Universiteit Brussel's Evidence-based Practice project

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Description

A Hill-Sachs lesion is an osseous defect or "dent" of the postero-supero-lateral humeral head that occurs in association with anterior instability or dislocation of the glenohumeral joint. It is often associated with a Bankart lesion of the glenoid. This lesion is caused by an anterior shoulder dislocation which causes a humeral head impression fracture. The posterolateral aspect of the humeral head impacts on the anterior glenoid in the dislocated position, causing shoulder instability.

Watch this animated description of Hill-Sachs and Bankart Lesions that can occur with a shoulder dislocation and contribute to further shoulder instability (2 minutes)

Epidemiology

The incidence of Hill-Sachs lesions are approximately 40%-90% of all anterior shoulder instability cases, and even as high as 100% in patients with recurrent anterior instability. A study looking at this found Hill-Sachs lesions in 65% of acute dislocations and 93% in patients with recurrent instability.
A Hill-Sachs lesion occurs in about 50% of the first-time shoulder dislocations. For people with a shoulder dislocations history (i.e. shoulder instability) humeral head compression fractures are present in most cases.

Etiology

• Anterior shoulder instability:
  • Approximately 47% of the lesions are associated with the initial shoulder instability according to research studies
• Bankart lesion
  • 2.5 times more likely to for someone with either of those lesions to have the other as well

• Anterior glenoid bone loss (in cases of recurrent instability)

Classification

Classification systems are used to describe the amount of damage to the anterior capsule and the labrum, reflected by the depth of the lesion. Higher grade lesions are associated with increased risk of recurrent dislocation.

• Grade 1: Defect in the articular surface down to (but not including) the subchondral bone
• Grade 2: Lesion includes the subchondral bone
• Grade 3: Lesion causes large defect in the subchondral bone.

Further classification can be done by looking at the percentage of the defect of humeral head involvement in the compression fracture. The size of the lesion correlates in most cases to the number of previous dislocations.

• Minor: <20%
• Moderate: 20%-45%
• Severe: >45%

Another classification - ON track or OFF track

If the Hill-Sachs lesion engages, it is called an “off-track” Hill-Sachs lesion; if it does not engage, it is an “on-track” lesion.

Clinical Presentation

Shoulder dislocation rarely occur isolated. It causes damage to different tissues surrounding the glenohumeral joint, such as ligaments, rotator cuff tendons, joint capsule as well as the bone and cartilage of the humeral head. 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 - a Hill-Sachs lesion.This is always caused by dislocation, not only subluxation.

According to the page on shoulder dislocations, the following indicates an acute anterior glenohumeral dislocation:

• Arm held in abduction and external rotation
• Loss of normal contour of the deltoid and acromion prominent posteriorly and laterally
• Humeral head palpable anteriorly
• All movements limited and painful
• Coracoid process: Palpable fullness and positioned towards the axilla

Differential diagnosis

• Bankart lesion: Also as a result of shoulder dislocation, and often goes together
• Pseudo-Hill-Sachs lesion: It is normal that below the level of the coracoid, the humeral head normally flattens out, and should not be mistaken as a Hill-Sachs lesion

• Humeral avulsion fractures
• Mid capsular tears
• Floating anterior capsule
• Reverse Hill-Sachs lesion: Lesion on the anterior-superior aspect of the humeral head as the result of a posterior shoulder dislocation

Diagnostic Procedures

Physical examination

• Bony apprehension test:
  • Positive test: Pain/reflex muscle contraction (in case of sublaxation)

• Jobe relocation test:
  • Positive test: Apprehension
  • Crepitus and catching may be felt during active and passive abduction and external rotation
  • Possible lesion indicated by audible/palpable clunk in active/passive abduction and external rotation or an unstable feeling during mid-range

Special investigations

Bankart and Hill-Sachs lesions

X-ray:

• Grashey view (AP) in internal and external rotation; transcapular view (X-ray beam caudally from standard AP view); axillary views with exaggerated external rotation and West Pont views (if pain allows)
• Important first step at effectively evaluating the glenohumeral relationship as well as osseous pathology of the humerus and the glenoid
• Can detect bony lesions related to shoulder instability in the acute phase
• Difficult to see Hill-Sachs lesion

Ultrasound:

• Detect and localize a compression fracture
• Cost-effective, minimal exposure to excessive radiation, comfortable for patient
• Hill-Sachs lesions: Apparent triangular depression in the contour of the humerus

CT scan: Reliably assess the location and depth of the humeral lesion

MRI: Detect pathology of the soft tissue; determine the amount of humeral and glenoid bone loss

Outcome Measures

• Disabilities of the arm, shoulder and hand (DASH)
• Shoulder Pain and Disability Index (SPADI)
• Numeric Pain Rating Scale (NPRS)

Medical management

The bony defect usually does not require treatment, though the linked glenohumeral instability and possible anterior labral injuries often need surgical repair.

1. Minimum glenoid bone loss and without significant involvement of the humeral head (<20%), surgical management is not indicated. This instability can be managed conservatively in a master sling for immobilization for 2-6 weeks, before starting with rehabilitation.
2. Large Defects: Management of the bony defect (as in Hill-Sachs lesion) can be treated with bone grafting or placement of soft tissue within the defect.

Surgical management

The critical size of the glenoid bone loss has been clarified as 25% of the glenoid width both biomechanically and clinically. This is the determinant factor influencing the choice of the surgical technique: soft tissue procedure or bone block procedure.

Arthroscopic technique

• Remplissage procedure: Defect is filled with soft tissue, usually from the infraspinatus tendon

• Second arthroplasty method: Percutaneous humeroplasty
  • Lesion is filled by using a bone tamp brought into a drilled osseous window 180° from the lesion
  • Advantage: Rotational osteotomy of the humeral head is not needed and the humeral head can be restored without transpositioning the soft tissue
  • Limitations: Limited to moderate-sized defects; lack of management of osteochondral defects
• Other procedures: Techniques that use various small bone plugs

Latarjet-Procedure

Open technique

• Laterjet procedure: Most frequently done
  • Most commonly, bone from the coracoid process is used as an augment to the antero-inferior glenoid bone loss. By reforming the concavity and width of the glenoid, a Hill-Sachs lesion does not influence the anterior glenoid rim of unstable shoulders.
  • Successful in preventing instability over time
  • Negative consequences associated with the Laterjet are shoulder arthrosis and loss of function

• Autologous bone plugs
• Size-matched osteo-articular allografts
• Rotational humeral osteotomy:
  • Osteotomy of the surgical neck to rotate the humeral head for 25°
  • Currently not method of choice, given the related risks and the success rates of more recent procedures.
• The osseus humeral allograft bone plug technique:
  • A size-matched humeral bone plug of a donor is used
  • Approach: Delto-pectoral or deltoid-splitting
  • Advantages: Minimal exposure; humeral head remains in the capsule.
  • Disadvantage: Limited to small and moderate lesions; risks of using cadaveric tissue

Physiotherapy management

Aim: Prevent reoccurrence of dislocations

The non-operative rehabilitation of the unstable shoulder consists about seven key factors. It is important to consider this in the rehabilitation program of the shoulder after a Hill-Sachs lesion.

• The onset of pathology
• The degree of instability
• The frequency of dislocation
• The direction of instability
• Concomitant pathologies
• Neuromuscular control
• Activity level

Stiff sling

Physiotherapy interventions include:

• 2-6 weeks of immobilization in a mastersling:
  • Scapula stabilization exercises
  • Hand, wrist and elbow exercises
  • Teach patient on functional adaptions (e.g. personal hygiene, dressing and undressing)
  • No driving while still in sling
• When use of sling is discontinued (on recommendation of orthopaedic surgeon):
  • Pendulum exercises
  • Passive, active-assisted and active range of motion exercises (progressions)
  • Abduction and external rotation is restricted during the initial phase of the rehabilitation
    • Ligaments healing needs to take place to prevent dislocation
  • Strengthening of the deltoid, rotator cuff and periscapular (e.g. pectoralis major) muscles

Post-surgical rehabilitation should be guided by the orthopaedic surgeon, and depends on the procedure that was done.

Clinical bottom line

A Hill-Sachs lesion is an injury that occurs secondary to an anterior shoulder dislocation. The humeral head ‘collides’ with the anterior part of the glenoid, causing a lesion, bone loss, defect and deformity of the humeral head. This may cause a change loss of range of motion, feelings of instability and pain. A grading system is used based on the amount of bone loss or severity of the humeral head deformity. The incidence of Hill-Sachs lesion in patients with anterior shoulder instability can be as high as 100%. Another pathology secondary to an anterior shoulder dislocation is a Bankart lesion. This is an injury of the anterior glenoid labrum of the shoulder and often often accompanied by a Hill-Sachs lesion.

Conservative treatment is only recommended in cases of small bony defects (<20% Hill-Sachs lesion), in other cases (larger and more significant lesions), surgical treatment is needed. The conservative treatment should be based on strengthening the deltoid, the rotator cuff muscles and scapular stabilizers.