The rough treatment and confinement caused Needhams left arm to develop compartment syndrome, a medical condition in which muscle tissue is injured and swells, cutting off circulation to a compartment of the muscle.
Deprived of oxygen and nutrients, the muscle tissue in the blocked compartment dies and becomes necrotic. The damage then spreads to other tissues. Left unchecked, compartment syndrome can cost limbs and lives.
The only treatment is a surgical intervention in which the muscles hard coating, the fascia, is cut open to relieve the pressure and swelling. In Needhams case, an infection invaded the necrotic tissue, which then spread throughout the arm.
http://www.rawstory.com/rs/2013/12/31/pittsburgh-woman-loses-arm-after-alleged-police-brutality-and-jail-neglect/
all well and good but if bothered to read the treatment (even IF her being handcuffed caused said injury which has NOT been proven) AMPUTATION is NOT the corrective surgery.