MDR - M/L Taper With Kinectiv Technology Stems and Necks

Inclusion Criteria: * Patient must be 18 years of age or older * Rheumatoid arthritis * Osteoarthritis * Traumatic arthritis * Polyarthritis * Collagen disorders * Avascular necrosis of the femoral head * Nonunion of previous fractures of the femur * Acute femoral neck fractures * Congenital hip dysplasia * Protrusio acetabuli * Previously failed endoprostheses * Patient must be willing and able to sign IRB/EC approved informed consent. Exclusion Criteria: * Skeletal immaturity * Loss of abductor musculature in the affected limb * Poor bone stock (e.g., steroid-induced metabolic bone disease) * Poor skin coverage around the hip joint * Neuromuscular disease (e.g., Charcot's joint) in the affected limb * Local and/or overt systemic infection * Patient with a stove-pipe femur * Stem implanted using cement fixation. * Off-label use * Uncooperative patient or patient with neurologic disorders who are incapable of following directions * Patient is known to be pregnant or nursing * Patient is a prisoner * Patient is a known alcohol or drug abuser * Patient has a psychiatric illness or cognitive deficit that will not allow for proper informed consent Patient is unwilling to sign the informed consent