Posterior shoulder dislocation (posterior shoulder dislocation)

What is a Posterior Shoulder Dislocation?

Shoulder dislocation describes the complete dislocation of the head of the humerus from the socket (glenoid). In a posterior dislocation, the dislocation occurs backwards. It only accounts for a small proportion of all shoulder dislocations, but can require sophisticated diagnostics and therapy due to accompanying soft tissue and bone damage.

• Less common form of dislocation (significantly less common than anterior)
• Mechanism: Internal rotation, adduction and flexion promote wedging backwards
• Associated lesions: reverse Hill-Sachs impression defect on the anteromedial humeral head, lesion of the posterior labrum (reverse Bankart), capsular injuries

Anatomy: Why the shoulder can dislocate in the first place

The shoulder is the most mobile joint in the body. It is stabilized by an interplay of bony form (flat socket), labrum (fibrocartilage ring), joint capsule, ligaments and the rotator cuff as well as the shoulder blade muscles. This dynamic stabilization enables a large range of movement - but also makes the joint susceptible to injury.

• Glenoid: flat socket, stability primarily through soft tissue
• Labrum: increases the socket depth, protects against dislocation
• Capsular-ligamentous apparatus: limits end positions, particularly relevant posteriorly
• Rotator cuff and scapula control: active stabilization in everyday life and sports

Causes and risk factors

Posterior dislocation often occurs as a result of indirect force that forces the arm into internal rotation and adduction. Seizure events and electrical accidents can generate massive muscular pulling forces that push the head of the humerus backwards. Sports involving contact or overhead use can also play a role if technique is poor.

• Trauma: Fall on the arm that is held forward and internally rotated
• Seizures (e.g. epileptic), postictal dislocations
• Electrical accidents with generalized muscle contractions
• Repeated microtrauma in sports (e.g. throwing, rugby, weight training)
• Previous shoulder instability or hypermobility
• Bone anatomy: increased retroversional position of the glenoid in individual cases

Symptoms and warning signs

Patients report sudden shoulder pain and restricted movement. A close arm position with internal rotation is typical; active external rotation is often hardly possible. Often there is a feeling that the shoulder is “blocked” or “out of place”.

• Acute pain, especially when attempting external rotation
• Movement block, protective posture with internal rotation
• Pressure pain and possibly palpable misalignment at the back
• Sensory disturbances or reduced strength with accompanying nerve irritation (e.g. axillary nerve)
• In chronic, overlooked dislocation: diffuse pain, weakness, limited function

Diagnosis: clinical and imaging

Since the posterior dislocation is easily overlooked on the classic AP X-ray, targeted imaging is part of the standard diagnostic procedure. We clinically check blood circulation, motor skills and sensitivity. In the acute situation, the examination is carried out in a pain-adapted manner.

• X-ray: at least 2 levels, ideally AP, Y or axial view; Signs include the “lightbulb sign” (internally rotated humeral head) or a lack of joint space
• Sonography: Assessment of soft tissues and effusions, helpful if expertise is good
• CT: exact representation of bony defects (reverse Hill-Sachs, glenoid edge) for surgical planning
• MRI: evaluation of labrum, capsule and rotator cuff; important in cases of instability and athletes
• Neurological status: Examination of the axillary nerve and other nerves

First aid and emergency measures

A recent dislocation should be professionally reduced promptly as long as there are no contraindications. The reduction should be carried out by a doctor, often under analgesic sedation and with adequate muscle relaxation to avoid injuries.

• Maintain a protective posture, immobilize and use ice to relieve pain
• No independent attempts at reduction
• Seek medical attention quickly, especially if you experience numbness, coldness or discoloration of the hand
• After reduction: renewed clinical and imaging control (X-ray), brief immobilization

Conservative therapy: always first, if possible

After successful reduction and when conditions are stable, non-surgical treatment makes sense in many cases. The aim is pain-adapted mobilization, followed by targeted muscle and coordination training to restore the dynamic stability of the shoulder.

• Short-term immobilization (usually 1-3 weeks depending on age and tissue quality), preferably in neutral to slight external rotation
• Gradual physiotherapy with a focus on scapula setting, proprioception and rotator cuff
• Strengthening especially the external rotators and scapular stabilizers; dosed training of the anterior chain
• Avoid in the early phase: forced internal rotation, adduction and flexion over the middle of the body
• Pain and inflammation modulating measures (cooling, needs-adapted analgesics)
• Tape/orthosis in selected situations for proprioceptive support

Injections (e.g. with local anesthetics or cortisone) can be considered in individual cases in the event of severe irritation. Biological/regenerative procedures (PRP, etc.) can be considered for chronic irritation of the soft tissues, but the evidence is heterogeneous - an individual indication test is required.

Surgical therapy: indications and procedures

Surgery is considered if there are relevant structural injuries, persistent instability, major bony defects or recurrent dislocations - or if reduction is not possible safely and stably. The decision depends on age, activity level, tissue quality and associated injuries.

• Arthroscopic stabilization: refixation of the posterior labrum (reverse Bankart), capsular shift/plication
• Treatment of the reverse Hill-Sachs defect: depending on the size, conservative, “reverse remplissage” (tendon/soft tissue filling) or bony techniques
• Open procedures with relevant bone involvement: posterior bone block (e.g. iliac crest chip) for socket augmentation
• McLaughlin or modified techniques (transfer of the subscapularis muscle or lesser tubercle) for large anteromedial humeral head defects
• Fractures/ruptures: address according to common standards, for older patients possibly prosthesis options
• Chronic locked posterior dislocation: individually graded approach; In the case of massive defects and arthrosis, anatomical or inverted shoulder prosthesis may be required

The goal of every operation is to restore stable, pain-free joint function. The procedure is followed by a structured post-treatment protocol with phases of immobilization, mobilization and strength building. Return to contact sports takes place gradually, depending on the healing process.

Rehabilitation and aftercare

Good rehabilitation is crucial for the result - regardless of whether the treatment is conservative or surgical. It should be dosed individually, planned for everyday life and specific to the sport.

• Avoid combined internal rotation, adduction and flexion with weight-bearing in the first few weeks.
• Test criteria before returning to sport: pain-free full range of motion, lateral comparison strength, stable scapula guidance, functional tests passed.
• Time ranges vary: everyday stress after weeks, contact sports often after 3-6 months - depending on the findings and procedure.

Course and prognosis

Many patients achieve good function with careful reduction, consistent physiotherapy and adapted load control. The risk of recurrence of instability is lower than with anterior dislocations, but varies depending on age, sports exposure, and extent of structural damage.

• Younger, physically active sufferers and patients with larger bony defects have a higher risk of recurrence.
• Dislocations that go undetected or are treated too late can lead to chronic instability, cartilage damage and osteoarthritis.
• A structured, individual rehabilitation program sustainably improves strength, coordination and everyday function.

Possible complications

• Nerve involvement (e.g. axillary nerve), rarely vascular injuries
• Rotator cuff lesions, especially in older patients
• Impression and edge fractures (reverse Hill-Sachs, posterior glenoid edge)
• Rigidity and persistent pain with delayed mobilization
• Recurrent instability
• Post-traumatic osteoarthritis; with long dislocation times, risk of humeral head necrosis

Prevention: What you can do yourself

• Technique training and strength balance in overhead and contact sports
• Targeted training of scapular stability and external rotators
• Sufficient regeneration times, progressive increase in load
• Consistent treatment of seizure disorders; If there is an increased risk, be careful with extreme loads
• Early clarification if there is a recurring feeling of buckling or instability

Special situations and patient groups

The causes and tissue qualities differ depending on the patient group. The therapy concept is adjusted accordingly.

• Seizure/electrical accident: bilateral or simultaneous injuries are often possible; Thorough imaging is important.
• Older people affected: more frequent accompanying lesions of the rotator cuff, osteoporotic bone; Conservative approach with functional goals often makes sense, prosthetic options for massive defects.
• Competitive and contact sports: sport-specific rehabilitation, clear return-to-play criteria, if necessary early indication for surgery in the case of structural defects and a high exposure profile.
• Hypermobility: Focus on neuromuscular control and proprioceptive training; Surgery only if there is clear structural pathology and failure of conservative measures.

When should you seek medical attention?

• Acute pain and blockage of the shoulder after a fall or seizure
• Numbness, tingling, feeling cold or color changes in the arm/hand
• Repetitive dislocating sensations, especially with certain movements
• Persistent pain or weakness after a dislocation that has already been treated

A timely clarification usually improves treatment options and reduces subsequent risks.

Your orthopedic shoulder consultation in Hamburg

In our practice at Dorotheenstrasse 48, 22301 Hamburg, we clarify shoulder problems in a structured manner and transparently discuss the most sensible treatment options - preferably conservative, with clear indications for surgical measures if necessary. We coordinate diagnostics, physiotherapy and stress build-up closely with you and, if desired, with your training or rehabilitation team.