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Acute Traumatic Posterior Shoulder Dislocation

·Journal of the American Academy of Orthopaedic Surgeons·2014·98 citations·Shoulder & Elbow
DOI·PubMed
SummaryAbstract on PubMed →

This review covers the diagnosis and management of acute traumatic posterior shoulder dislocation. It addresses why the injury is so often missed and how reverse Hill-Sachs lesion size guides treatment. It also details the associated injuries and the surgical algorithm from closed reduction to arthroplasty.

Key Findings

  • Posterior dislocation is missed or delayed in up to 79% of patients. The triad to remember is seizure, electrocution, and high-energy trauma. In the post-seizure patient, reduced nociceptive sensitivity masks the injury, so maintain a high index of suspicion.
  • A systematic review found posterior dislocations occur after trauma in 67%, seizure in 31%, and electrocution in 2% of cases. The seizure mechanism is unbalanced muscle pull. Strong internal rotators overpower the weak external rotators, driving the head posteriorly.
  • Associated injuries are far more common than historically thought, reaching up to 65% of dislocations. Fractures occur in 34%, most often the surgical neck (55%), then lesser (42%) and greater (23%) tuberosities. A lesser tuberosity fracture matters because you enter the joint through the fracture rather than doing a subscapularis tenotomy.
  • Reverse Hill-Sachs lesions appear in up to 86% of patients and are significant in 29%. This anteromedial impaction size is the single number that drives the surgical algorithm.
  • Rotator cuff tears are found in 13% on MRI, but the odds are 4.6 times higher when there is no associated fracture or Hill-Sachs lesion. So if the CT shows no fracture, get an MRI and examine the cuff carefully.
  • Recurrent instability affects roughly 18% in the first year. Risk factors are age under 40, seizure, and a large reverse Hill-Sachs lesion (>1.5 cm3). Functional impairment can persist at 2 years even without recurrence.
  • Closed reduction succeeded in only 33% of 112 shoulders using gentle in-line traction. Always image before reduction, because forceful manipulation can fracture the humeral head and cause osteonecrosis.
Board PearlPosterior shoulder dislocation is missed in up to 79% of patients; suspect it after seizure, electrocution, or trauma and get an axillary view.

Clinical Relevance

When you see a shoulder that will not externally rotate after a seizure, electrocution, or high-energy fall, think posterior dislocation until proven otherwise. The injury is missed in up to 79% of patients because the AP film can look nearly normal. The single most useful step is ordering an axillary or Velpeau view, and looking for the lightbulb sign, trough line, and loss of the half-moon sign.

Once reduced, the reverse Hill-Sachs lesion size becomes your decision engine. Under 20% may tolerate closed or open reduction. From 20% to 40% consider a McLaughlin or modified McLaughlin transfer or bone grafting. Over 40% in a younger patient often needs hemiarthroplasty.

Always image before any reduction maneuver, because reducing an unrecognized neck fracture or forcing an engaged lesion can fracture the head and precipitate osteonecrosis. Finally, if CT shows no fracture, the odds of a rotator cuff tear jump 4.6-fold, so get an MRI.

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Acute Traumatic Posterior Shoulder Dislocation

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Roos, Beynnon, et al.·J Orthop Sports Phys Ther·1998·3,837 citations·Sports Medicine
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Acute Traumatic Posterior Shoulder Dislocation

·Journal of the American Academy of Orthopaedic Surgeons·2014·98 citations·Shoulder & Elbow
DOI·PubMed
SummaryAbstract on PubMed →

This review covers the diagnosis and management of acute traumatic posterior shoulder dislocation. It addresses why the injury is so often missed and how reverse Hill-Sachs lesion size guides treatment. It also details the associated injuries and the surgical algorithm from closed reduction to arthroplasty.

Key Findings

  • Posterior dislocation is missed or delayed in up to 79% of patients. The triad to remember is seizure, electrocution, and high-energy trauma. In the post-seizure patient, reduced nociceptive sensitivity masks the injury, so maintain a high index of suspicion.
  • A systematic review found posterior dislocations occur after trauma in 67%, seizure in 31%, and electrocution in 2% of cases. The seizure mechanism is unbalanced muscle pull. Strong internal rotators overpower the weak external rotators, driving the head posteriorly.
  • Associated injuries are far more common than historically thought, reaching up to 65% of dislocations. Fractures occur in 34%, most often the surgical neck (55%), then lesser (42%) and greater (23%) tuberosities. A lesser tuberosity fracture matters because you enter the joint through the fracture rather than doing a subscapularis tenotomy.
  • Reverse Hill-Sachs lesions appear in up to 86% of patients and are significant in 29%. This anteromedial impaction size is the single number that drives the surgical algorithm.
  • Rotator cuff tears are found in 13% on MRI, but the odds are 4.6 times higher when there is no associated fracture or Hill-Sachs lesion. So if the CT shows no fracture, get an MRI and examine the cuff carefully.
  • Recurrent instability affects roughly 18% in the first year. Risk factors are age under 40, seizure, and a large reverse Hill-Sachs lesion (>1.5 cm3). Functional impairment can persist at 2 years even without recurrence.
  • Closed reduction succeeded in only 33% of 112 shoulders using gentle in-line traction. Always image before reduction, because forceful manipulation can fracture the humeral head and cause osteonecrosis.
Board PearlPosterior shoulder dislocation is missed in up to 79% of patients; suspect it after seizure, electrocution, or trauma and get an axillary view.

Clinical Relevance

When you see a shoulder that will not externally rotate after a seizure, electrocution, or high-energy fall, think posterior dislocation until proven otherwise. The injury is missed in up to 79% of patients because the AP film can look nearly normal. The single most useful step is ordering an axillary or Velpeau view, and looking for the lightbulb sign, trough line, and loss of the half-moon sign.

Once reduced, the reverse Hill-Sachs lesion size becomes your decision engine. Under 20% may tolerate closed or open reduction. From 20% to 40% consider a McLaughlin or modified McLaughlin transfer or bone grafting. Over 40% in a younger patient often needs hemiarthroplasty.

Always image before any reduction maneuver, because reducing an unrecognized neck fracture or forcing an engaged lesion can fracture the head and precipitate osteonecrosis. Finally, if CT shows no fracture, the odds of a rotator cuff tear jump 4.6-fold, so get an MRI.

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