7 Femoral Neck Fractures

Arthroplasty

The use of arthroplasty for the management of displaced fractures of the femoral neck is generating increasing interest.¹ Because of the uncertainty of outcome following reduction and fixation of displaced femoral neck fractures, surgeons are increasingly turning to arthroplasty as a more certain procedure in terms of patient satisfaction and lower revision rate.² Arthroplasty for femoral neck fractures is generally a more complicated surgical procedure than reduction and fixation, however, and meticulous attention to detail is necessary to ensure the success of the procedure.³

Indications

Arthroplasty is indicated for displaced intracapsular fractures of the femoral neck. In elderly patients with significant osteoporosis, arthroplasty is the operation of choice.⁴ The decision between unipolar or bipolar arthroplasty and total hip replacement should be made on the basis of the patient’s preoperative activity level or the presence of antecedent symptomatic hip arthritis. As a general rule, younger, more active patients have better outcomes with total hip replacement, thus making the slightly increased risk of complications with that procedure acceptable.⁵

Secondary indications, which are not within the scope of this chapter, are failed internal fixation with malunion or nonunion or avascular necrosis occurring sometime after fracture healing.

Elsewhere in this text, the technique of internal fixation and its indications and complications are explored. Arthroplasty is a viable alternative to internal fixation for patients with completely displaced fractures, particularly in the presence of significant comminution or significant osteoporosis. The role of monopolar, bipolar, and total hip arthroplasty should be made on the basis of the surgeon’s experience, the availability of the implant, and the patient’s activity level rather than on patient age alone.^6,⁷ Implant costs may also play a role in selection of treatment.

Bipolar and unipolar arthroplasty procedures have a significant advantage of increased stability as compared with total hip replacement.⁸ However, the introduction of highly cross-linked polyethylene has allowed for the use of thinner polyethylene inserts and therefore larger-diameter femoral heads in total hip arthroplasty. These improvements have increased the stability of that operation and decreased the risk of dislocation. The choice between cemented and cementless components largely depends on the surgeon’s preference, although in patients with extreme osteopenia with a large medullary canal, a cemented stem offers more secure fixation and the possibility of immediate weight bearing without concerns about prosthetic subsidence.⁹ However, cemented stems are recognized to pose a slight but definite increase in the risk of systemic fat embolization; they also prolong the operative procedure by approximately 10 minutes as compared with cementless stems.

There is little indication for the use of alternative bearing surfaces in this patient group. Not only are the implants more expensive, but also investigations suggest that the large femoral head seen in the hard bearing surface constructs does not effectively reduce the rate of dislocation. Furthermore, metal-on-metal bearing surfaces may be associated with an increased risk of infection, and because they confer no benefit to this patient population and are more expensive, their use is discouraged.

Surgical approach is again dependent on the surgeon’s preference.¹⁰ The technique illustrated in this chapter is the posterior approach, but the direct lateral approach is also frequently used. The advantage of the direct lateral approach is the decreased rate of dislocation, particularly in patients who have preoperative or postoperative confusion or delirium. The disadvantage is the increased weakness of the abductors as a consequence of the approach that may increase or prolong a postoperative limp.