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What is Deforming force on proximal fragment in Benett's fracture ? and explain in detail?
Ans. is 'a' i.e., APL Benett's fracture Benett's fracture is an intra-aicular fracture dislocation of the palmar base of first metacarpal bone of the thumb with either subluxation or dislocation of first carpometacarpal joint, i.e. trapezometacarpal joint. The common mechanism of injury is an axial blow directed against the paially flexed metacarpal, in most cases during "Fist fights". Patient complains of pain, swelling and tenderness over the base of the thumb. Movements of thumb are restricted. Displacing force in Bennett's fractures Following are the deforming forces in Bennett's fracture :- i) At the distal fragment, it is the adductor pollicis. ii) At the proximal fragment, it is the abductor pollicis longus. Base of the thumb metacarpal is pulled dorsally and medially by the abductor pollicis longus, while the distal attachment of adductor pollicis fuher levers the base into abduction.