[Undetected traumatic posterior glenohumeral dislocation]

Glenohumeral dislocation (GHD) is frequent, but traumatic posterior glenohumeral dislocation (TPGHD) is rare, with an incidence of 1-4% of all GHD. The diagnosis is a challenge: sometimes, it can be omitted due to incorrect diagnosis, absence of consideration in the differential diagnosis, suboptimal radiographic evaluation and an absence of characteristic signs and symptoms; missed diagnosis reaches 60-79% and the diagnosis can delay from 24 hours to a year.

To transmit previous experiences to provide support for better diagnosing TPGHD, favoring appropriate attention.

Case 1. 34-year-old male. Delayed diagnosis of left TPGHD in the 4th week. Reverse Hill-Sachs < 25%. Closed reduction, immobilization for four weeks. Follow-up at week 20, good functional recovery (UCLA = 32). Case 2. 32-year-old male. Eight months with undiagnosed left TPGHD. Reverse Hill-Sachs 25%. Open reduction, immobilization for four weeks. Eight-month post-surgical follow-up. Good functional recovery (UCLA = 29).

The diagnosis of TPGHD is difficult because of its lack of frequency. Even with delayed diagnosis-treatment, evolution can be favorable provided that the reverse Hill-Sachs injury is 25% or minor. To avoid a delayed diagnosis and inadequate attention, we must always consider the injury mechanism, physical examination with the arm fixed in internal rotation, clinical suspicion in functional deficit for external rotation, flexion and abduction, radiographic studies including true AP and scapula lateral (Y view).