This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pelvis & Injuries, Subject name: Orthopaedics
A patient with hip dislocation with limitation of Abduction at hip and flexion and internal rotation deformity at hip and shortening. Diagnosis is: 
Select and explain. 
A. Central dislocation, B. Anterior dislocation, C. Posterior dislocation, D. Fracture dislocation
C: Posterior dislocation
Answer: C: Posterior dislocation 
Explanation: (c) Posterior dislocationExplanationSince the question mentions limitation of abduction, hence there is adduction deformity along with flexion and internal rotation deformity. Thus this is a case of Posterior dislocation of hip.Position of hipPattern of InjuryFlexion, adduction, internal rotationPure posterior dislocationLess flexion, less adduction (neutral or slight abduction), internal rotationPosterior fracture dislocation > central dislocationHyper abduction + Flexion + External rotationAnterior dislocationSome students remember an alternate format of the question 6b