Optimal Treatment of Femoral Neck Fractures According to Patient’s Physiologic Age: An Evidence-Based Review




For decades, the basic tenets of managing displaced femoral neck fractures have not changed, but the optimal treatment choice continues to be highly debated. The contemporary controversies associated with the treatment principles of displaced femoral neck fractures are distinct between young and old patients and are considered individually in this article about the current evidence. Although fixation constructs all seem to have similar complication rates, there is increasing evidence suggesting that total hip replacement improves patient functional outcomes for healthy, independent, elderly patients compared with hemiarthroplasty and should be considered as the treatment of choice for these patients.


For decades, the basic tenets of managing displaced femoral neck fractures have not changed, but the optimal treatment choice continues to be highly debated. The first step in management includes an assessment of the patient’s physiologic age. Chronologic age becomes less important in patients who are active with high functional demands, good bone quality, and few medical comorbidities. These patients are considered “young,” whereas patients with poor bone quality and significant medical comorbidities are often considered “old” despite chronologic age. The contemporary controversies associated with the treatment principles of displaced femoral neck fractures are distinct between these 2 age groups and will be considered individually in this review of the current evidence.


Femoral neck fractures in young patients


Femoral neck fractures in physiologically young patients are managed differently than those in the elderly. These patients have fewer medical problems, sustain different fracture patterns, and have good bone quality. These patients typically have high functional demands and are not considered good candidates for hip replacement. Surgical timing, the role of capsulotomy, and the choice of internal fixation remain controversial.


Does Surgical Timing Matter?


Avascular necrosis


The most common justification for emergent care of femoral neck fractures in “young” patients has been to rapidly reestablish the blood supply to the femoral head and thus minimize the risk of avascular necrosis (AVN). Swiontkowski and colleagues reported low rates of AVN (20%) in 27 patients aged 15 to 50 years and attributed this success to the application of an institutional protocol of “immediate reduction” (within 8 hours of diagnosis) and internal fixation with compression. This pivotal publication labeled these injuries “surgical emergencies” in young patients.


More recent evidence from cohort studies, however, does not conclusively support the association between time to reduction (<24 hours) and AVN. On one hand, Jain and colleagues supported Swiontkowski’s findings when they reported an increased rate of AVN (16%) in 38 patients (aged <60 years) treated more than 12 hours after injury and 0% AVN in patients treated within 12 hours of injury. On the other hand, Haidukewych and colleagues retrospectively reviewed a series of 73 patients (aged 15–50 years) and found no significant difference in AVN in those treated within 24 hours of injury (23%) and those treated more than 24 hours after injury (20%). Three cases series reported that patients treated after inadvertent delays of 6 days to 2 years had rates of AVN similar to those series in which patients were treated emergently (0%–25%).


To further support the lack of association between surgical timing and AVN, a meta-analysis was performed reviewing 18 retrospective cohort studies of femoral neck fractures in patients aged 15 to 50 years (547 fractures). The overall rate of AVN for displaced fractures was 22.5%. Seven of these studies reported data on the association between surgical timing and AVN rates and demonstrated no difference between patients treated within 12 hours of injury (13.6%) and those treated after 12 hours of injury (15%). The only prospective data to date included 92 patients and demonstrated an overall AVN rate of 16%, with no difference in those patients treated before or after 48 hours at 2-year follow-up.


Nonunion


Swiontkowski and colleagues reported no nonunions in 27 patients and attributed this success to emergent surgical intervention, anatomic reduction, and compressive fixation. Jain and colleagues reported no nonunions regardless of surgical delays of more than 12 hours. Haidukewych and colleagues showed no difference in nonunion (overall rate 8%) seen in patients treated before or after 24 hours. Upadhyay and colleagues found an overall nonunion rate of 17.4%, with no difference between those treated before or after 48 hours. The above-mentioned meta-analysis reported a 6% overall nonunion rate and found no significant difference between fractures treated within 12 hours (11.8%) or after 12 hours (5%) of injury.




Should the intracapsular pressure/hematoma be decompressed?


Although experimental data demonstrate an increase in the intracapsular hip pressure associated with femoral neck fractures, there have not been any significant clinical benefits associated with capsulotomy. Maruenda and colleagues prospectively measured preoperative intracapsular pressures in 34 patients with femoral neck fractures and observed the patients for an average of 7 years postoperatively. Five of the six patients in whom AVN developed had preoperative intracapsular pressures less than the diastolic blood pressure that led the investigators to conclude that the rate of AVN was not secondary to high intracapsular pressures. Upadhyay and colleagues prospectively randomized patients to either closed reduction and percutaneous pinning or open capsulotomy, reduction, and pinning and found no difference in the rates of AVN and nonunion between treatment groups.




Should the intracapsular pressure/hematoma be decompressed?


Although experimental data demonstrate an increase in the intracapsular hip pressure associated with femoral neck fractures, there have not been any significant clinical benefits associated with capsulotomy. Maruenda and colleagues prospectively measured preoperative intracapsular pressures in 34 patients with femoral neck fractures and observed the patients for an average of 7 years postoperatively. Five of the six patients in whom AVN developed had preoperative intracapsular pressures less than the diastolic blood pressure that led the investigators to conclude that the rate of AVN was not secondary to high intracapsular pressures. Upadhyay and colleagues prospectively randomized patients to either closed reduction and percutaneous pinning or open capsulotomy, reduction, and pinning and found no difference in the rates of AVN and nonunion between treatment groups.




Which implant is best for femoral neck fractures in young patients?


Femoral neck fracture fixation ideally allows interfragmentary compression, resists displacement, and ensures rotational stability during the healing process. Options for the fixation of femoral neck fractures include multiple compression screws (CSs), dynamic fixed-angle devices such as sliding hip screw (SHS) and side plate, static fixed-angle devices such as blade plate, dynamic condylar screw (DCS), and more recently, locked plates contoured to the proximal femur. The CS and the SHS constructs may allow fracture fragments to slide along the implants with axial loading during weight bearing and add the benefit of controlled dynamic compression during healing. Static fixed-angle devices aim to maintain the surgically obtained reduction rigidly during the healing period.


Although multiple clinical trials have directly compared implant choice with patient outcomes, these studies have all been performed in the osteoporotic patient population. Close evaluation of the small cohort studies of patients younger than 50 years of age demonstrate that most surgeons treat patients in this age group with various CS configurations; none of these studies specifically evaluate the association between nonunion and AVN with the fixation device. Moreover, complications of uncontrolled sliding with multiple screws and resultant shortening of the femoral neck are well reported in older patients but have not been critically evaluated in younger populations with good bone quality.


The biomechanical principles of fixation devices apply regardless of patient age. When using CSs, it is important to place them parallel to achieve compression and close to the cortex to minimize the risk of nonunion and to prevent postoperative varus angulation and posteroinferior displacement of the femoral head. Eighty-nine percent of fractures fixed with 2 screws placed within 3 mm of the inferior neck cortex and the posterior calcar region achieved union, but there was a 100% nonunion rate if both screws were more than 3 mm away from the cortices.


The Pauwel classification is most commonly used for the evaluation of the young patient and is based on the biomechanical properties associated with the angle of the primary fracture line relative to the horizontal. In Pauwel type I fractures (<30 ° ), compressive forces predominate, and screw position perpendicular to the fracture is often achievable. As the fracture becomes more vertical, shear forces predominate and it becomes more difficult to apply fixation perpendicular to the fracture line. A recent evaluation by Liporace and colleagues retrospectively evaluated 62 young patients (19–64 years, mean age 42 years) with Pauwel type III fractures (>70 ° ). Thirty-seven patients were treated with CS fixation and had a nonunion rate of 19%. The remaining 25 patients were treated with a fixed-angle implant (DCS, SHS, or cephalomedullary nail) and had an 8% rate of nonunion. Although sample size was small and there was no statistically significant difference because of insufficient power, this retrospective cohort study demonstrates the challenge of treating these high-shear fracture patterns in young patients and emphasizes the potential advantage of fixed-angle implants.


Poor reduction, typically varus malreduction, and posteroinferior displacement of the femoral head have been shown to increase the rate of nonunion irrespective of implant choice and patient age. Haidukewych and colleagues reported an 80% nonunion rate in patients with a poor reduction versus 4% in those in whom a good to excellent reduction was achieved. Similarly, Liporace and colleagues demonstrated a 14% nonunion rate in fractures with good to excellent reductions versus 2 of the 3 with poor reductions. Upadhyay and colleagues prospectively associated nonunion with poor reduction, posterior neck comminution, and poor screw position. The presence of posterior neck comminution may compromise the surgeon’s ability to obtain and maintain an anatomic reduction and has been associated with a lower resistance to displacement and fixation failure.




Summary of the evidence: physiologically young patients


The goal of treatment in young patients is anatomic reduction and stable fixation of the femoral neck to minimize the risk of nonunion and osteonecrosis. Current best evidence suggests a lack of association between time to reduction (<24 hours) and AVN or nonunions. Similarly, although increased intracapsular pressure is associated with femoral neck fracture, no clinical benefit has been seen when capsular decompression is performed. The evidence, comprised of underpowered observational cohorts (level III–IV), is far from conclusive, and statistically sound inferences regarding surgical timing and capsular decompression cannot be made.


Regarding implant choice, the relative importance of dynamic compression during weight bearing at the cost of stability in unstable fracture patterns has not been evaluated. Although the theoretical benefit of fixed-angle implants should be considered in high-shear fractures (Pauwel III), an advantage over multiple screw fixation has not been clearly demonstrated in population-based studies. Although multiple screw fixation remains the current standard, trends favoring fixed-angle implants in the younger population demonstrate the need for ongoing comparative studies to ensure best practice. Quality of fracture reduction and presence of posterior comminution have been consistently associated with poor outcomes in young patients.




Expert opinion


Femoral neck fracture reduction and fixation is indicated in patients with no evidence of osteopenia and who are poor candidates for hip replacement based on activity level. That said, indications for the fixation of femoral neck fractures have been affected by the improvements made in total hip replacement, which continues to grow as a treatment option for this injury with excellent results even in patients as young as 50 years old. Based on the evidence, the authors think strongly that if fixation is the goal, an anatomic reduction and rigid fixation are critical. All efforts should be put toward improving the likelihood of an anatomic reduction, and in our hands, an open reduction often improves the likelihood that this goal is achieved. Thus, an incision is preformed in the situation in which an anatomic reduction cannot be obtained closed, not necessarily as a method to decrease the risk of AVN. Notably, in the investigators’ hands, an incision is often required to enhance reduction quality. The authors do not yet understand the importance of dynamic compression (afforded by CS or SHS fixation) on healing and think there may be some relevance to the consideration of fixed-angle implants in length-unstable fracture patterns, which fractures with comminution often are. However, the authors remain concerned that the locked implants, which create a bridge construct through the comminuted neck region, may lead to increased rates of nonunion because of the lack of compression and the rigidity created by these implants. The authors eagerly await further data on this topic. Finally, their interpretation of the available data indicates a lack of association between time to reduction and AVN or nonunions. Because these data are not definitive and low-level evidence, the current opinion remains that early reduction is the standard of care. The authors’ practices include an assumption that quality of reduction is the most important factor on outcome, and if a surgical delay of 12 hours from injury enhances the likelihood of an anatomic reduction based on institutional factors, they would wait to perform the operation.




Femoral neck fractures in old patients


Femoral neck fractures are significantly more common in the elderly than in physiologically young patients. Current projections suggest that 77 million Americans and 25% of Canadians will be older than 65 years by the year 2041. It is predicted that Canadian and American health care systems will face the fiscal and social dilemma of 88,000 and 500,000 hip fractures a year, respectively. Older patients are more likely to present with medical comorbidities; thus controversies regarding surgical timing are related to perioperative medical problems and mortality. Surgical controversies in this patient demographic include the benefit of fixation versus arthroplasty, implant options for internal fixation, and choices between partial and total hip arthroplasty.




Is there a role for nonoperative management in the elderly with femoral neck fractures?


Reported nonoperative protocols for hip fractures include a 1- to 3-week period of bed rest, followed by early bed-to-chair transfers and ambulation. This treatment protocol has been associated with a 14% to 62% incidence of secondary displacement versus 4.3% for similar fractures treated surgically. Furthermore, the initial period of immobilization is associated with medical complications, including urinary tract infections, thromboembolic events, decubitus ulcers, and pneumonia. Patients with cognitive dysfunction are at increased risk for complications associated with nonoperative treatment (50% mortality and 63% complication). Thus, although conservative management may be considered in high-risk surgical patients, it should be recognized that this option is associated with high rates of subsequent displacement, morbidity, and mortality.


Does Time to Surgery Matter?


Hip fractures in the elderly patient population are associated with an overall mortality rate averaging 30%. Although several studies have demonstrated a direct correlation between surgical timing and patient mortality, it is clear that patient comorbidities must be considered. Bottle and Aylin recently reviewed patients older than 65 years (n = 129,522) and found that a delay in surgery of more than 24 hours was associated with increased inhospital death odds ratio of 1.39 (95% confidence interval [CI], 1.34–1.44). When comorbidities were controlled, the odds ratio fell to 1.27 (95% CI, 1.23–1.32). The investigators concluded that the presence of comorbidities does affect patient treatment, including time to surgery, but delay of surgery increases mortality and therefore should only be delayed secondary to optimization of comorbidities for surgery.


Radcliff and colleagues prospectively analyzed patient outcomes in 5683 American veterans (aged >65 years) with femoral neck fractures and found that preinjury factors included older age, disseminated cancer, cognitive impairment, congestive heart failure, greater functional dependence, and higher ASA (III and IV). When these covariates were controlled, surgical delay more than 4 days was associated with increased 1-month mortality (odds ratio, 1.29; 95% CI, 1.02–1.61) as was the use of general anesthesia (odds ratio, 1.27; 95% CI, 1.15–1.53). They concluded that surgical delay of more than 4 days increased 1-month mortality.


Because surgical timing does seem to affect mortality, recent investigations have attempted to elucidate the optimal timing of surgical intervention in those patients presenting with medical conditions that may benefit from medical intervention before operation. Moran and colleagues prospectively compared mortality rates at 1 month, 3 months, and 1 year among patients who were either fit for surgery or who required preoperative management of medical disease (n = 2660). Patients who were fit for surgery at the time of presentation but experienced surgical delay more than 4 days had increased 90-day (hazard ratio of 2.25; 95% CI, 1.2–4.3) and 1-year (hazard ratio of 2.4; 95% CI, 1.45–3.99) mortality rates. Patients with medical comorbidities requiring treatment had mortality rates 2.5 times higher than the fit cohort. Surgical delay did not influence the nonfit cohort’s mortality rate. These data suggest that patients with treatable medical comorbidities have a significantly higher risk of overall mortality regardless of surgical timing and that priority should be given to optimizing medical management at the cost of surgical delay.


A meta-analysis of 16 prospective and retrospective observational studies demonstrated that surgical delay of more than 48 hours increased the 30-day and 1-year mortality rates by 41% and 32%, respectively. The investigators concluded that for every 1000 patients undergoing delayed surgery versus early surgery, there would be 25 more deaths at 1 month and 49 at 1 year. Although all studies were observational, the sample sizes were high, and their findings were consistent with most large, population-based evaluations that suggest a strong relationship among time to surgery, presence of medical comorbidities, and mortality ( Table 1 ).


Feb 23, 2017 | Posted by in ORTHOPEDIC | Comments Off on Optimal Treatment of Femoral Neck Fractures According to Patient’s Physiologic Age: An Evidence-Based Review
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