Failed Femoral Neck ORIF (5-15% nonunion, 5-15% AVN) is often the easiest to convert to THA, as the standard treatment of 3 cannulated screws can be removed through the posterolateral incision for THA. Furthermore the femoral neck nonunion is excised with femoral preparation for the stem implant [40]. Outcomes suggest conversion failed femoral neck ORIF to THA is comparable to standard THA with 93% survivorship at 10 years (although possibly higher dislocation risk) [41].
Failed Intertrochanteric Fracture ORIF (nonunion risk only 5%) is more complicated to revise [40]. An intramedullary nail (hip IMN) is inserted through the abductor musculature and removal often causes further injury to the abductor complex, leading to postoperative limp and possible long term abductor deficiency and subsequent risk for instability. A screw and side plate is the preferred construct for the arthroplasty surgeon because removal can often be performed through the posterolateral approach used for the THA, and also because it preserves the abductor musculature. The additional challenge of converting a failed Intertroch ORIF is an intertroch nonunion often requires a calcar replacing stem (about 65% of cases), and the stem must be long enough to bypass screw holes from the removed hardware which would otherwise act as stress risers. Additionally, the fracture itself may have altered the anatomy of the proximal femur and thus increases the complexity of preparing the femur. Outcome studies indicate that conversion of Intertroch to THA is a less successful procedure, with higher rates of instability and greater troch pain, overall 88% survivorship at 10 years [42].
REFERENCES
40. Mehlhoff, T., G.C. Landon, and H.S. Tullos, Total hip arthroplasty following failed internal fixation of hip fractures. Clin Orthop Relat Res, 1991(269): p. 32-7.
41. Mabry, T.M., et al., Long-term results of total hip arthroplasty for femoral neck fracture nonunion. J Bone Joint Surg Am, 2004. 86-A(10): p. 2263-7.
42. Haidukewych, G.J. and D.J. Berry, Hip arthroplasty for salvage of failed treatment of intertrochanteric hip fractures. J Bone Joint Surg Am, 2003. 85-A(5): p. 899-904.