Posttraumatic Reconstruction of the Hip Joint

Hemiarthroplasty

Hemiarthroplasty is a reliable procedure for low-demand patients, that is, those who are minimal ambulators, have multiple medical comorbidities, or have a short life expectancy. These implants have low rates of major complications, including infections and dislocations. Hemiarthroplasty also entirely avoids the potential complications of nonunion or malunion inherent in attempting internal fixation in this population. These implants are associated with activity-dependent acetabular cartilage erosion (also known as prosthetic arthritis ). In one study, native cartilage wear was observed in two-thirds of hemiarthroplasties. However, only 20% of these patients were symptomatic to the point that they required conversion to THA.

Total Hip Arthroplasty

Primary THA as a treatment for a displaced femoral neck fracture was generally limited to active patients with preexisting degenerative joint disease from osteoarthritis (OA), inflammatory arthritis, and so forth. Patient selection is key; the treating surgeon must balance a higher risk of dislocation with THA in an elderly population, especially in the setting of dementia and/or neuromuscular disorders, with improved functional parameters and the avoidance of progressive coxarthrosis. Patients undergoing THA for an acute femoral neck fracture should be considered as having a higher risk of complications and an increased cost of care when compared with patients undergoing elective THA in the setting of OA. Multiple published studies indicate longer hospital stays; higher perioperative mortality; higher rates of discharge to inpatient care facilities; unplanned readmissions; and complications such as pulmonary emboli, hematomas, and infections in the posttraumatic THA patient population when compared with patients undergoing elective THA.

Other studies, however, have shown the long-term efficacy of primary THA for femoral neck fracture in terms of residual pain and need for revision. One study found no difference in terms of morbidity, functional outcomes, and implant survival at 36 months between patients undergoing THA for either femoral neck fracture or end-stage OA. Two randomized trials showed significantly improved functional status and lower reoperation rates in elderly patients receiving THA compared with those receiving internal fixation using parallel screws.

Decision Making: Hemiarthroplasty Versus Total Hip Arthroplasty

Hemiarthroplasty has been touted as having shorter operative times, decreased blood loss, and improved stability when compared with THA ( Fig. 56.1 ). Despite these benefits, in patients without cognitive deficits, neuromuscular disorders, or inflammatory arthritis, who demonstrate community ambulation, the authors prefer to perform THA ( Fig. 56.2 ). THA has also been shown to have a decreased need for revision and better patient outcomes than hemiarthroplasty in the setting of displaced femoral neck fractures at midterm follow-up, with a slightly increased risk of dislocation. However, more recently, Khurana et al. showed that when compared with primary THA for OA, THA has longer operative times, more acute blood loss and the need for subsequent transfusion, and a revision rate of 12.5% within a mean follow-up time of 4.4 years. THA in the setting of femoral neck fractures does not impart a significantly higher risk of acute postoperative dislocation. Additional studies using national joint registries have shown improving rates of perioperative mortality, pulmonary embolism, and infection. Furthermore, dual-mobility implants, which have recently become more commonly used in the United States, may help mitigate differences in dislocation rates between these two types of implants as well. Finally, surgeon comfort with acetabular component placement should also be considered in the decision-making process; if the treating surgeon does not feel confident reliably placing an acetabular component in an appropriate position with the correct orientation and does not have access to another surgeon who does, a hemiarthroplasty is the best treatment option in their hands regardless of these patient factors.

Technical Considerations for Primary Arthroplasty in the Setting of Acute Femoral Neck Fracture

The surgical approach should be foremost based on the treating surgeon's experience and comfort level in addition to balancing risks of potential complications. The literature with regard to the approach in hemiarthroplasty has shown no difference in objective and patient-reported outcomes except for two studies showing slightly higher rates of dislocations when a posterior approach was used, even in conjunction with a capsular repair, when compared with either a lateral or an anterior approach. The surgical approach in THA for femoral neck fractures has demonstrated a similar effect on dislocations rates. In one study of 713 THAs, patients who had an anterolateral approach had a much lower dislocation rate (2%) compared with those who had a posterolateral approach with or without capsule repair (12% and 14%, respectively). It is important to consider, however, that the femoral heads used in these studies are smaller compared with contemporary implants. The larger femoral heads, in addition to dual-mobility implants, afford the surgeon more options for hip stability. Further study is warranted to determine if the approach in this patient population still has similar dislocation rates as in the studies cited previously.

The component-selection operative technique should be optimized to maximize bony ingrowth and avoid iatrogenic fracture because these patients generally have impaired bone stock. Bony preparation should proceed cautiously to reduce the risk of fracture. The authors typically use cement fixation for femoral component placement because the bone has already failed a structural integrity litmus test. This allows for a significant decrease in iatrogenic fracture risk and adds confidence for immediate weight bearing because the periprosthetic fracture risk has been shown to be 20% higher in uncemented prostheses. In younger patients who have fractured through higher-energy trauma rather than a ground-level fall, press-fit stems are considered but often with a prophylactic cable placed around the calcar before femoral preparation. In THA, the authors also routinely use acetabular components with porous ingrowth surfaces and screw augmentation after press-fit is achieved to promote osseous ingrowth and stable fixation. Having multiple liner options available, including dual-mobility bearing couples, is advised to augment stability if necessary.

The treating surgeon must weigh the risks of periprosthetic fracture in an uncemented stem with the risk of potentially fatal emboli from bone cement implementation syndrome, a fortunately exceedingly rare event. One way to potentially mitigate this risk is to use thumb or manual pressurization of cement, rather than foam restrictors placed at the calcar during cement filling of the intramedullary canal.