The most common site of fracture neck of femur that causes avascular necrosis is
A i.e. Subcapital Malunion is rarest complication of fracture neck femur (almost not seen) because intracapsular fracture neck femur almost never unite unless thay are anatomically reduced and stabliy fixed. Most common complications of intracapsular fracture neck femur are nonunioin & fixation failure (more common in most series of displaced fractures) and avascular necrosis (more common in most series of undisplaced fractures). Shoening is seen in almost all cases of nonunion & AVN. Chances of avascular necrosis (AVN) and nonunion increases as the fracture site becomes more proximal Q. The more proximal the fracture located the worse the prognosis. Chances of AVN & nonunion (or worseness of prognosis) in decreasing order is Subcapital Q > transcervical > basal > interochanteric Transphyseal > transcervical > cervicotrochanteric > interochanteric (in children) Complications of Hip Fractures Intracapsular Fracture Neck Femur Extracapsular Fracture Interochanteric Femur Most - Non union (in MalunionQ common displaced fracture) - Avascular (Osteo) necrosis (in undisplaced fracture) Least common MalunionQ NonunionQ Nonunion is second most common complication (after avascular necrosis) of undisplaced fracture neck femurQ. The probable causes of nonunion in fracture neck femur are - - Cambium layer of periosteum which produce callus is missing. There fore femoral neck must heal direct endosteal healing only. There is no contact with soft tissues which could promote callus formation. Precarious blood supply: by tearing the ascending cervical branches or retinacular vessels the injury deprives head of its main blood supplyQ. Synol fluid interfere with fracture healing as it prevents clotting of fracture hematoma and release angiogenic inhibiting factors. - Inadequate reduction and improper immobilization. * It is impoant to note that avascular necrosis and nonunion are independent events, because AVN is based on vascular supply of femoral head, whereas nonunion is based on the healing process. So AVN can occur even in united fractures. * Femoral neck fractures should unite by 6 months. If there is no evidence of healing or patient continued to have pain at 3 - 6 months after surgery then a delayed (3 months) or non union ( 6 months) should be contemplated. * AVN is a late complication and ischemic collapse usually occur with in 2 -years of fracture. According to anatomical location of fracture neck femur the chances of AVN & nonunion in decreasing order are: subcapital (transepiphyseal in children) > TranscervicalQ > Basicervical. - Temponade effect of intracapsular hematoma causing floating of both fracture ends and making reduction difficult.
Sub-capital
Interochanteric
Trans-cervical
Basal