In the young patient, and historically in all patients, osteosynthesis was considered the gold standard for hip fractures regardless of fracture pattern. Common complications prevalent in femoral neck fractures include nonunion, malunion, and osteonecrosis. As surgeons became more familiar with endoprosthetic designs, their use in treating displaced femoral neck fractures has grown substantially. A long-term randomized control trial (3) and a meta-analysis of RCT’s with nearly 1,200 patients (4) both found favorable outcomes in femoral neck fractures treated with arthroplasty in older patients. Still, the precise indications for arthroplasty in the acute fracture setting are not agreed upon.

Arthroplasty options first appeared in the 1960s with the earliest endoprosthetic designs being uncemented monopolar femoral stems. A major issue with these early designs was acetabular wear and erosion. To diminish forces across the acetabulum, bipolar hemiarthroplasties were introduced in the mid-1970s. Persistent issues continued in more active patients with decreased joint motion, persistent acetabular erosion, and diminished hip function leading some surgeons to recommend the use of total hip arthroplasty (THA) for the treatment of displaced neck of femur fractures.

Nondisplaced femoral neck fractures in most patients, regardless of age should be treated with internal fixation. Subcapital and intertrochanteric fractures may also be treated with osteosynthesis in certain settings and patient populations (Fig. 77.1). Similarly, in displaced femoral neck fractures in the young patient, most surgeons still favor internal fixation over arthroplasty. However, in the older patient with a displaced fracture of the femoral neck primary arthroplasty should be considered. Patient factors such as general health, premorbid activity level, cognitive function, and bone stock must be assessed by the operating surgeon to determine if THA or hemiarthroplasty is most appropriate. Generally, if there is preexisting hip pain, significant osteoarthritis, and pathologic bone disease (i.e., metabolic/oncologic), THA should be considered as a primary treatment.

Femoral neck fractures occur in a bimodal distribution with regards to age and mechanism. Younger patients typically sustain femoral neck fracture as the result of high energy trauma and often occur in conjunction with other injuries. Older patients with femoral neck fracture usually sustain the injury as a result of lower energy mechanism such as fall from standing height. In both populations however, treatment algorithms begin with the amount of fracture displacement. Nondisplaced or valgus-impacted patterns in both patient populations should be treated with in situ pinning. Given the majority of blood supply to the femoral head is derived from an extracapsular source via the retinacular vessels these fractures should heal uneventfully. Increased fracture displacement however, increases vessel injury and a tamponade effect within the capsule can further diminish blood supply and predispose to development of avascular necrosis.

Proponents of osteosynthesis suggest that internal fixation after anatomic reduction provides more natural hip mechanics, a lower risk of dislocation, and decreased OR time with lower mortality risk (2). Anatomic reduction however is paramount and technical errors in the placement of hardware can lead to early failure, nonunion, or clinical dissatisfaction. A meta-analysis of nine randomized trials (1,162 patients) has shown an increased rate of revision in patients undergoing internal fixation versus arthroplasty for femoral neck fracture (4). Further analysis demonstrated that 17 conversion procedures can be prevented for every 100 patients treated with arthroplasty (4). Two large randomized control trials from Sweden echo the positive results of arthroplasty in hip fracture treatment. The first examined the short-term outcomes at the 2-year follow-up, finding patients that received primary arthroplasty treatment (hemi- or THA) had improved pain, functionality, and mobility. In additionally, these patients had a revision rate of 4% compared to 43% in the internal fixation group (5). When longer-term trends are examined, arthroplasty treatment once again offers improved clinical function and lower revision rates. At the 17-year follow-up, Chammout et al. (3) demonstrated decreased major revision surgery in the THA group and observed that the majority of failures in the internal fixation group occurred early (<2 years), while those in the arthroplasty group occurred later (>48 months). None of the patients in this long-term randomized trial had preexisting hip pain and all were over the age of 65. Furthermore, active older patients without significant medical co-morbidity do better with hemiarthroplasty/THA versus reduction and fixation (6).

There has been some belief that internal fixation is associated with lower cost when compared to arthroplasty options. Iorio et al. (7) however found that internal fixation was in fact the most expensive option. They performed a cost analysis for 2 years postoperative comparing internal fixation, unipolar, bipolar hemiarthroplasty and THA. Hospital admission, rehabilitation, and adjusted revision costs
were considered and demonstrated that cemented THA was the most cost-effective option ($20,670). Internal fixation meanwhile was found to be the least cost-effective of the cohorts examined ($24,606). Therefore due to positive long-term results and cost neutrality the use of arthroplasty (hemiarthroplasty or THA) should be strongly considered in older patients with femoral neck fracture.

The remainder of this chapter will focus on the indications, techniques, and literature pertaining to the use of arthroplasty for the treatment of femoral neck fractures. We will discuss hemiarthroplasty and THA for acute fracture treatment as well as explore the details surrounding conversion arthroplasty in revision settings.

The current literature clearly supports that elderly patients benefit from arthroplasty for the treatment of acute femoral neck fracture (3,4,5,6,7). The next decision the treating surgeon must make is whether a hemiarthroplasty (bipolar or monopolar) or THA would be most appropriate. Furthermore, one must determine the approach to be utilized; the type of fixation (cemented vs. uncemented); and the implant specifics such as head size, modularity, and bearing material to be used. Specific patient and fracture characteristics to consider have been presented by Zuckerman (8). Some general questions surgeons should consider when deciding on the treatment of acute femoral neck fracture must include the following: