Femoral neck fractures are a devastating injury for patients and a substantial burden for the health care system.1–7 Every year, approximately 250,000 individuals in the United States seek treatment for femoral neck fractures, with reported annual costs exceeding $4.4 billion.8,9 Most of these cases involve the elderly. Ambulation is critical for successful rehabilitation of this population following surgical treatment of femoral neck fracture.10,11 Hemiarthroplasty, which promotes early postoperative ambulation, is an attractive intervention for patients with femoral neck fractures.12 The increased medical comorbidities associated with delayed mobilization of these patients provide further incentive.
Multiple hip approaches are used for hemiarthroplasty. The direct anterior approach, which uses the intermuscular plane of Hueter, is believed to accelerate functional recovery by limiting iatrogenic muscle damage in total hip arthroplasty (THA).13 Specifically, multiple studies have reported decreased postoperative pain scores,14–16 improved discharge home,17–19 and accelerated return to preoperative functional status.20–22 In contrast to the THA population, patients with femoral neck fractures tend to be older and develop pathology during an acute traumatic event. As such, it is not known if the purported benefits of the direct anterior approach transfer to this population.
The direct lateral approach splits the gluteus medius and vastus lateralis to gain access to the hip.23 The muscle damage inherent in this approach is presumed to increase postoperative pain, decrease hip muscle strength perioperatively, and potentially prolong rehabilitation relative to muscle-sparing techniques.24 Compared with patients treated with the direct lateral approach, patients treated with the direct anterior approach should show accelerated functional recovery. Despite growing popularity, data from direct comparison of functional recovery and other surgical outcomes following femoral neck fracture are limited.
The primary aim of this study was to compare functional recovery following surgical repair of femoral neck fractures using the direct anterior approach and the direct lateral approach. The hypothesis was that patients treated with the direct anterior approach would show decreased rates of discharge to secondary rehabilitation facilities and accelerated return to preoperative ambulatory status. To further investigate postoperative recovery, the secondary aim of this study was to compare other surgical outcomes for the direct anterior approach and the direct lateral approach cohorts.
Materials and Methods
This study received institutional review board approval. Consecutive patient records between September 2006 and January 2016 were retrospectively reviewed at a single institution certified by the Accreditation Council for Graduate Medical Education. All adult reconstructive surgical cases were screened using International Classification of Diseases, Ninth Revision, codes for the following inclusion criteria: acute, intracapsular femoral neck fracture (Garden III–IV)25; exposure of fracture site via the direct anterior approach or the direct lateral approach; and use of bipolar or monopolar hemiarthroplasty repair. Exclusion criteria included age younger than 18 years, ongoing systemic infection, open or pathologic fractures, and prior fracture of the femoral neck, ipsilateral acetabulum, or proximal femur. A total of 160 patients met inclusion criteria.
Surgical Techniques
After medical optimization, all procedures were performed by 1 of 2 board-certified, fellowship-trained orthopedic surgeons (A.C.O., Z.D.P.) who specialize in joint replacement surgery. In line with recent THA trends, the hemiarthoplasty practices at the authors' institution have shifted from the direct lateral approach to the direct anterior approach over time. Ultimately, the choice of surgical approach was determined by each joint specialist at the time of surgery. The physicians generally preferred a hemiarthroplasty over THA for patients who were at increased surgical risk because of comorbidities or advanced age.
The plane of Hueter was used for femoral neck fracture exposure in the direct anterior approach cohort as described by Rachbauer and Krismer.19 A modified version of the lateral approach described by Hardinge23 was used for femoral neck fracture repair in the direct lateral approach cohort.
Following surgery, all patients received standard, inpatient postoperative care. This included mechanical prophylaxis for deep venous thrombosis in addition to chemical prophylaxis. Ambulation and physical therapy were encouraged for all patients beginning less than 24 hours after surgery. If a patient could not ambulate or participate in physical therapy, he or she was encouraged to do so as soon as possible. The same postoperative rehabilitation protocol was used in each cohort. Disposition (ie, to home or to a secondary rehabilitation facility) was determined by mutual agreement among the patient, the family, the medical team, and the surgeon.
Although the authors' institution's primary THA practices have changed with time, the hip fracture protocols had remained consistent during the 10 years that these data were collected. The authors' anesthesia and perioperative factors, including transfusion triggers and anticoagulation, had not changed. Similarly, their postoperative weight-bearing protocols and rehabilitation instructions had remained the same.
Data Collection
Data were retrospectively reviewed to compare patient characteristics (Table 1), perioperative outcomes (Table 2), discharge location stratified by age and American Society of Anesthesiologists classification (Table 3), and ambulation (Table 4) between the direct anterior approach and the direct lateral approach cohorts. For the comparison of perioperative outcomes, the perioperative interval was defined as surgery to the initial follow-up visit at 4 to 6 weeks. The change in hemoglobin (Hb) was calculated by subtracting the preoperative Hb from the lowest postoperative Hb observed during each patient's hospital stay. Medical and surgical complications were categorized into major and minor subgroups. Deep venous thrombosis was considered a major complication if it required intervention such as placement of an inferior vena cava filter. Of note, comparisons of complications and reoperation rates were extended beyond the perioperative interval to include 4- to 6-month follow-up data. For comparisons of ambulation, the maximum number of steps ambulated on postoperative day 2 was determined. Eleven patients who were nonambulatory at baseline or unable to participate because of other medical conditions were excluded from this comparison. The prevalence of pre- to postoperative ambulatory decline was compared between the cohorts at the 4- to 6-week and the 4- to 6-month follow-up visits. Ambulatory decline was defined as any stepwise decrease from unassisted walking to dependence on an assistive device (cane, walker, and then wheelchair) relative to each patient's preoperative baseline.
Statistical Analysis
Normality was assessed for all variables using the Kolmogorov–Smirnov test. For normally distributed variables (age, body mass index), a Student's t test was used to compare the cohorts. For non-normally distributed variables (operative time, change in Hb, length of hospital stay, number of feet ambulated on postoperative day 2, and intervals to follow-up visits), the Mann– Whitney U test was used. Where appropriate, a chi-square or Fisher's exact test was used to compare the categorical variables between the cohorts. Missing data were excluded from statistical analysis.
Results
A total of 160 patients met criteria for this study. The direct anterior approach and the direct lateral approach cohorts had 85 and 75 patients, respectively. No significant demographic or preoperative differences existed between the cohorts (Table 1). No significant difference was observed between the cohorts regarding mean±SD times for the 4- to 6-week (direct anterior approach, 6.2±1.8 weeks; direct lateral approach, 6.0±1.5 weeks) (P=.29) and the 4- to 6-month (direct anterior approach, 5.7±1.2 months; direct lateral approach, 5.7±1.2 months) (P=.57) follow-up intervals.
Compared with the direct lateral approach cohort, the direct anterior approach cohort had a significantly shorter mean operative time, a shorter mean length of hospital stay, and a smaller mean decrease in Hb (Table 2). No significant differences were observed for perioperative outcomes, complications, or reoperation rates. No significant difference in disposition was observed between the cohorts (Table 3), and this was the case even when stratifying for age and American Society of Anesthesiologists classification status. No significant difference was found for feet ambulated on postoperative day 2 or the prevalence of ambulatory decline at the 4- to 6-week or 4- to 6-month follow-up visits (Table 4).
Discussion
To the best of the authors' knowledge, this is the first study to directly compare outcomes following hemiarthroplasty of femoral neck fractures via the direct anterior approach and the direct lateral approach. On the basis of the results of this study, the direct anterior approach may benefit patients by decreasing the length of hospital stay by 2 to 3 days, which could have a substantial impact on inhospital exposures and health care costs. However, because of the devastating pathologic insult experienced by patients with femoral neck fractures, disposition appears to be independent of approach for this population. Even among subgroups composed of younger patients or those with higher preoperative health status, the authors found no improvement in disposition for patients receiving the direct anterior approach. Further, maximum ambulatory capacity shortly after surgery and the prevalence of ambulatory decline at later follow-up visits appeared to be indistinguishable between these cohorts. Given the large standard deviation observed for the number of feet ambulated on postoperative day 2 for both cohorts, the health and motivation of each individual patient may have a more substantial effect than the approach used for the repair.
A recent study by Trinh et al26 reported comparisons similar to those of the current analysis. Trinh et al26 compared perioperative outcomes for patients undergoing surgery via the direct anterior approach with those for a mixed cohort of posterior, anterolateral, and direct lateral cases. Similar to the current study's findings, Trinh et al26 reported no significant difference in discharge location or postoperative ambulation. They also found that the direct anterior approach cohort was more likely to be discharged on or before the third postoperative day. Although these results support the findings of the current study, in the study by Trinh et al,26 the direct anterior approach and the direct lateral approach cohorts consisted of 30 and 11 patients, respectively. This limited the generalizability of the results for these commonly used approaches. It also increased the risk of a type II error for conclusions regarding postoperative function, thus providing justification for the current analysis.
The recent study by Unger et al27 also reported comparisons similar to those of the current analysis. Unger et al27 reported surgical outcomes for elderly patients undergoing hemiarthroplasty for femoral neck fracture repair using the direct anterior approach. In contrast to the current study, most (159 of 180) of the patients were discharged home. However, the average length of hospital stay (16 days) notably exceeded that of the current study and likely offset the improved disposition. These differences likely reflect cultural trends in surgical practice, as the Unger et al27 study was performed in Germany and the current study was conducted in the United States. In addition, it is likely that length of stay is heavily influenced by medical comorbidities in this population.
Two other studies have compared functional recovery following femoral neck fracture repair via the direct anterior approach with that following posterior approaches. Langlois et al28 observed that a direct anterior approach cohort performed better than a posterolateral approach cohort on a timed up-and-go test at 6 weeks postoperatively; however, the difference was not significant. Baba et al29 found that a higher proportion of patients receiving the direct anterior approach ambulated without assistance at 2 weeks postoperatively compared with patients receiving the posterior approach. However, this study reported no significant difference in mean length of hospital stay (direct anterior approach, 29.3 days; posterior approach, 29.9 days), and discharge locations were not compared statistically.29 Thus, the direct anterior approach may accelerate functional recovery relative to posterior approaches. However, this conclusion requires future investigation.
Surgeon experience, peri- and postoperative outcomes, the unique needs of the patient, and the burden on the health care system must be balanced when determining optimal surgical technique. Among the various factors to consider, hospital stay is an important outcome for elderly patients because of their predilection to iatrogenic complications,30,31 including the development of deep venous thrombosis with prolonged inpatient medical care.32,33 The burden on the health care system must also be considered. A recent study found that hospital stay accounts for 44% of the direct cost of hip fractures.34 Findings from the current study suggest that the direct anterior approach may benefit patients and health care systems by promoting earlier discharge.
Because of equal expertise in operative techniques and the potential for earlier discharge, the authors' institution continues to use the direct anterior approach for femoral neck fractures. The authors also recognize that the earlier discharge observed in this study may indirectly reflect enhanced functional recovery, which provides additional incentive. Prospective studies with larger samples are needed and may identify differences in disposition and postoperative functional recovery undiscoverable in the current study because of limitations in cohort sizes.
A limitation of this study was the absence of follow-up data for multiple patients. Because the authors' practice is located near a popular vacation destination, tourists comprised a substantial percentage of the patients in each cohort. These patients returned home after receiving acute care for femoral neck fractures and were unavailable for outpatient data collection. It is also possible that differences existed between the cohorts regarding preoperative American Society of Anesthesiologists classification and ambulatory status but were not identified because of the population sizes. Another limitation was the short follow-up interval. More meaningful comparison of dislocation and reoperation rates could be obtained by extending data collection over several years. Further, this study was unable to account for the recent emphasis on early ambulation in the rehabilitation protocols for THA, which may have transferred to the femoral neck fracture population. As a result, it is possible that patients receiving the direct anterior approach were encouraged to ambulate earlier than patients receiving the direct lateral approach because of the trend toward the increased direct anterior approach during the course of this study. However, this effect would have biased for improved functional recovery in patients receiving the direct anterior approach—a result that was not found. Finally, although the differences in Hb and operative time showed statistical significance, the clinical significance of these findings is less consequential.
Conclusion
The direct anterior approach benefits patients undergoing hemiarthroplasty repair of femoral neck fractures by decreasing the length of hospital stay. However, the direct anterior approach does not appear to increase the likelihood of return to preoperative functional status after femoral neck fracture. Thus, the purported benefits of the direct anterior approach for patients undergoing THA do not appear to transfer to patients with femoral neck fractures undergoing hemiarthroplasty. It is likely that femoral neck fracture represents a devastating change in physiologic status that is unaffected by the surgical approach chosen to treat the patient. As presumed acceleration of functional recovery likely represents the primary motivation for conversion to use of the direct anterior approach, surgeons are encouraged to select the surgical approach (the direct anterior approach or the direct lateral approach) that they are most experienced in using for femoral neck fracture repair.
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Patient Characteristicsa
| Characteristic | Cohort | Pa | z Score |
|---|
|
|---|
| Direct Anterior Approach | Direct Lateral Approach |
|---|
| Patients, No. | 85 | 75 | - | NA |
| Male:female ratio, No. | 1:1.5 | 1:1.6 | .45 | NA |
| Age at surgery, mean (SD), y | 82.7 (9.4) | 82.9 (9.1) | .91 | NA |
| Age range, y | 53.3–102.2 | 58.7–104.3 | - | NA |
| Body mass index, mean (SD), kg/m2 | 23.3 (4.9) | 24.7 (4.5) | .07 | NA |
| Preoperative disposition, No. | | | .92 | NA |
| Home | 67 | 60 | | |
| Assisted living | 18 | 15 | | |
| Preoperative ambulatory status, No. | | | .32 | NA |
| Unassisted | 61 | 60 | | |
| Cane | 3 | 4 | | |
| Walker | 15 | 6 | | |
| Wheelchair | 6 | 5 | | |
| Interval from admission to surgery, mean (SD), d | 1.4 (1.1) | 1.7 (1.2) | .31 | −1.0 |
| American Society of Anesthesiologists classification, No. | | | .09 | NA |
| I | 0 | 1 | | |
| II | 3 | 6 | | |
| III | 65 | 45 | | |
| IV | 12 | 11 | | |
| Not reported | 5 | 12 | | |
Perioperative Outcomes
| Perioperative Outcome | Cohort | P | z Score |
|---|
|
|---|
| Direct Anterior Approach (N=85) | Direct Lateral Approach (N=75) |
|---|
| Length of surgery, mean (SD), min | 42.9 (13.9) | 45.3 (8.8) | <.01 | −2.61 |
| Difference between pre- and postoperative hemoglobin, mean (SD), g/dL | 2.3 (1.1) | 3.0 (1.3) | <.01 | −3.63 |
| Requirement for transfusion, No. | 15 | 18 | .30 | NA |
| Length of stay, mean (SD), d | 6.2 (3.1) | 8.9 (7.0) | <.01 | −3.14 |
| Major complications, No. | 9 (10.6%) | 14 (18.7%) | .14 | NA |
| Periprosthetic fracture | 3 | 3 | | |
| Periprosthetic infection | 1 | 2 | | |
| Dislocation | 2 | 0 | | |
| Pulmonary embolism | 2 | 1 | | |
| Deep venous thrombosis | 0 | 2 | | |
| Acute myocardial infarction | 1 | 2 | | |
| Ischemic stroke | 0 | 1 | | |
| Death | 0 | 3 | | |
| Minor complications, No. | 8 (9.4%) | 6 (8.0%) | .77 | NA |
| Trochanteric bursitis | 2 | 2 | | |
| Sacral decubitus ulcer | 1 | 3 | | |
| Pneumonia | 4 | 1 | | |
| Meralgia paresthetica | 1 | 0 | | |
| Reoperations, No. | 4 (4.7%) | 5 (6.7%) | .57 | NA |
| Revision | 1 | 1 | | |
| Open reduction and internal fixation | 2 | 3 | | |
| Removal of hardware | 0 | 1 | | |
| Total hip arthroplasty | 1 | 0 | | |
Total and Stratified Patient Disposition
| Disposition | Cohort | P |
|---|
|
|---|
| Direct Anterior Approach | Direct Lateral Approach |
|---|
| Patients, No. | 85 | 75 | .84 |
| Home | 13 | 14 | |
| Secondary care facility | 72 | 61 | |
| Patients <75 years old, No. | 20 | 14 | .62 |
| Home | 4 | 3 | |
| Secondary care facility | 16 | 11 | |
| Patients 75–80 years old, No. | 11 | 14 | .59 |
| Home | 1 | 2 | |
| Secondary care facility | 10 | 12 | |
| Patients >80 years old, No. | 19 | 13 | .41 |
| Home | 4 | 4 | |
| Secondary care facility | 15 | 9 | |
| Patients with ASA <4 including emergencies (ASA classification E), No. | 58 | 39 | .94 |
| Home | 10 | 6 | |
| Secondary care facility | 48 | 33 | |
| Patients with ASA <4 excluding emergencies (ASA classification E), No. | 54 | 34 | .81 |
| Home | 9 | 6 | |
| Secondary care facility | 45 | 28 | |
Ambulatory Outcomes
| Parameter | Cohort | P | z Score |
|---|
|
|---|
| Direct Anterior Approach | Direct Lateral Approach |
|---|
| Feet ambulated on postoperative day 2, mean (SD), No.a | 29.0 (34.8) | 24.7 (39.5) | .84 | −1.60 |
| Prevalence of ambulatory decline at the 4- to 6-week follow-up visit, No./Total No.b | 25/52 (48.1%) | 20/35 (57.1%) | .41 | NA |
| Prevalence of ambulatory decline at the 4- to 6-month follow-up visit, No./Total No.c | 13/50 (26.0%) | 12/34 (35.3%) | .70 | NA |