Simple bone cysts of the proximal humerus presented with limb length discrepancy: A case report

Figure 6 Two hypotheses for the etiology of our patient with simple bone cyst who presented with a pathological fracture, angular deformity, and limb length discrepancy. The red area represents the location of simple bone cyst (SBC); the blue dotted line represents the epiphysis; and the yellow line indicates the affected epiphysis. A–D: The first hypothesis. A: The proximal humeral simple bone cyst extends through the physis on the medial side; B: The SBC subsequently caused growth arrest and varus deformity of the humerus; C: Due to a proximal humerus fracture, additional varus angulation of the humeral head occurs; D: SBC presenting with a pathological fracture, complicated with malunion of the displaced fracture, varus deformity and limb length discrepancy. E–H: The second hypothesis. E: A proximal humeral simple bone cyst develops; F: Repetitive pathological fractures due to SBC damaged the medial epiphysis of the proximal humerus and varus humeral head angulation was established as a consequence; G: The humerus develops varus deformity and a length discrepancy due to a damaged epiphysis; H: SBC presenting with a pathological fracture, complicated with malunion of the displaced fracture, varus deformity and limb length discrepancy.