Direct anterior approach for femoral neck fractures: Why and how?

Abstract

Femoral neck fractures are among the most common orthopedic injuries, often managed using closed reduction internal fixation (CRIF), hemiarthroplasty, or total hip arthroplasty (THA). While several approaches have been utilized in the surgical management of femoral neck fractures, the direct anterior approach (DAA) has emerged as a popular approach for hip arthroplasty given its smaller incision, muscle sparing technique, and robust outcomes. Several studies and meta-analyses have demonstrated that the DAA has fewer complications, dislocations, and better early functional outcomes compared to other approaches when performing hip arthroplasty for femoral neck fractures. Furthermore, studies have demonstrated promising outcomes with the utilization of the DAA approach for femoral neck fracture visualization and anatomic reduction, which is particularly important when caring for younger high-energy trauma patients. Given the notable morbidity and mortality associated with geriatric femoral neck fractures in particular, the DAA may be yet another technique that can further reduce the incidence of adverse outcomes seen in this population as we anticipate a rising elderly patient population in the coming years.

1. Introduction: summarizing management of femoral neck fractures and the DAA

Femoral neck fractures are common orthopedic injuries with an incidence that is expected to double by the year 2050.¹ Most femoral neck fractures occur amongst the geriatric population through a low energy mechanism (i.e., ground level or mechanical fall)² with women being at a higher risk.³ These injuries occur less commonly among younger individuals as a result of high energy trauma. Radiographic evaluation of a femoral neck fracture should include an anterior-posterior (AP) view of the pelvis and hip as well as a lateral of the hip. A computed tomography (CT) scan can be used to detect occult nondisplaced femoral neck fractures when there is high suspicion.⁴ The Garden Classification is the most common system used to classify femoral neck fractures based on the degree of fracture displacement.⁵ Additionally, the Pauwel Classification classifies femoral neck fractures based on the angle of the fracture in concordance with fracture stability.⁶ Femoral neck fractures often require surgery, with nonoperative management reserved for either severely debilitated or high surgical risk patients. Non- or minimally displaced fractures are typically managed with closed reduction internal fixation (CRIF) utilizing multiple cancellous screws or a sliding hip screw (SHS). While CRIF can be achieved for some displaced fractures, significantly displaced fractures require open reduction internal fixation (ORIF), particularly among young adults, select active older adults, and those too ill to undergo hemiarthroplasty (HA) or total hip arthroplasty (THA).⁴

In circumstances where an open approach is indicated (i.e., ORIF or arthroplasty), several approaches have been implemented, including the Moore or Southern (posterior), Watson-Jones (anterolateral), and modified Smith-Petersen approach, which is now better known as the direct anterior approach (DAA).⁷ The DAA was originally introduced in 1881 by Heuter,⁸ with its first application for THA being described in 1940. In the 1980s, Light and Keggi publishing one of the first large series’ utilizing the a modified Smith-Peterson for hip arthroplasty.⁹ The DAA utilizes the interval between the tensor fascia lata and sartorius muscles to gain access to the hip joint, utilizing an incision around 3–4 inches long and a muscle sparing approach, whereas the posterior approach requires a 10 to 12-inch incision and splits the gluteus maximus muscle. With the growing popularity of the DAA, there have been several studies investigating its utilization for HA and THA,^7,10 particularly in the setting of femoral neck fractures. Fewer studies have addressed its utilization for ORIF of femoral neck fractures, femoral head fractures, or loose body removal. The goal of this review is to summarize the literature on the usage of the DAA for the various treatment modalities of femoral neck fractures.

2. Reviewing the history of DAA utilization for femoral neck fractures

The DAA has gained popularity due to its muscle-sparing nature allowing for earlier functional recovery and decreased risk of dislocation.11, 12, 13 Although use of the DAA for hip arthroplasty was reported as early as the 19th century, use of the approach for management of femoral neck fractures has lagged somewhat.11, 12, 13 Given that the geriatric hip fracture population carries a high morbidity and mortality, an approach that can reduce the risk of major complications has great potential in optimizing patient outcomes. Recent meta-analyses have found that the use of DAA for hip arthroplasty in management of femoral neck fractures is associated with fewer complications, fewer dislocations, and better early functional outcomes.^11,12 Therefore, it is not surprising the DAA is being adopted as a preferred approach for arthroplasty by many orthopaedic surgeons.¹³

Despite the inherent benefits of the DAA, it is important to acknowledge the technical considerations that can make utilizing this approach more challenging. A steep learning curve has been reported among surgeons adopting DAA but originally trained in the posterior approach, which raises concern for increased complication rates during the early stages of adoption.¹³ In addition, although the approach is versatile among a variety of body habitus types, there can be additional technical challenge using the DAA in patients with higher muscle mass, higher overall body mass index, or those with a sizable abdominal pannus.^13,14 In contrast to these difficulties, there are technical advantages of the for the treatment of femoral neck fractures. Supine positioning may increase ease of predictability, control of component positioning, and facilitate the use of intraoperative fluoroscopy.^13,15 Use of an anterior approach also minimizes the small but present risk of sciatic nerve injury which can occur through a posterior approach to the hip which, although rare, can have significant consequences.^13,16

3. Direct anterior arthrotomy for femoral neck fracture reduction, femoral head (pipkin) fractures, and foreign body removal

The DAA has promising applications for ORIF of complex femoral head and neck fractures, as well as removal of loose/foreign bodies. There are several surgical approaches that have traditionally been applied specifically in the setting of femoral neck fractures, including the modified Smith-Petersen (anterior), Watson-Jones (anterolateral), and Moore/Southern (posterior) approaches.¹⁷ ORIF is often indicated for young adult patients suffering a femoral neck fracture from a high-energy mechanism. The DAA may be advantageous in this patient population by allowing supine positioning in the setting of concomitant injuries, using a smaller incision, and ensuring less iatrogenic soft tissue damage. Furthermore, despite a small incision, the DAA has been shown to be equivalent to the Moore/Southern approach in achieving adequate visualization during fixation of femoral neck fractures.¹⁸ Another consideration is that high-energy femoral neck fractures in the young adult population are associated with higher rates of femoral head osteonecrosis and nonunion.¹⁹ Therefore, anatomic reduction is likely more important than the time to fixation.²⁰ In addition to direct visualization of the fracture, the DAA allows supine positioning which facilitates intraoperative fluoroscopy and confirmation of fracture reduction.¹³

Overall, there are limited studies assessing the implementation of the DAA for ORIF of femoral neck fractures. One study looked at the utility of DAA in a series of 16 patients <55 years with displaced (Garden III-IV) femoral neck fractures. All patients in this series underwent initial attempt at closed reduction on a fracture table followed by conversion to ORIF using direct visualization in addition to fluoroscopic guidance. All patients achieved anatomic reduction and fixation using a dynamic hip screw (DePuy Synthes™ Femoral Neck System (FNS)™). The authors report perfect anatomic reduction in all 16 cases, minimal blood loss, and less fluoroscopic time compared to CRIF. Overall, they support the usage of DAA and corroborate that it involves minimal soft tissue damage compared to traditional approaches and reduced risk of damage to the MFCA.²¹ Another small series (n = 28) assessed ORIF of vertically unstable Pauwels 3 femoral neck fractures fixed with a medial buttress plate utilizing a DAA. They achieved a union rate of 89 % with no cases of avascular necrosis (AVN) at a mean follow up of 13.6 months. This represents a notable reduction in the rate of avascular necrosis compared to a prior review of Pauwels 3 fractures that reported an AVN of 11 %.²² In their discussion, the authors comment that the DAA not only allows excellent visualization of the fracture reduction, but also reduces risk of damage to the MFCA, which is the predominant blood supply to the femoral head.^23,24 It is important to mention that the DAA often requires ligation of branches of the lateral femoral circumflex arteries (LFCA) during the approach; however, the LFCA contributes around 18 % of the blood supply to the femoral, head, so there is very little risk of AVN.²⁵ While further studies are warranted, especially comparing the DAA to posterior approaches, current literature demonstrates favorable outcomes for utilization of the DAA for ORIF of displaced femoral neck fractures with regard to maximizing anatomic reduction and mitigating risks for AVN.

Femoral head fractures are rare injuries that result from traumatic posterior hip dislocations. Fixation of displaced femoral head fractures is important to prevent the development of posttraumatic arthritis.²⁶ The DAA may be advantageous during the fixation of femoral head fractures as it allows adequate visualization of the femoral head, lower risk of damage to the MFCA and subsequent risk of AVN,^18,23,24 and minimal violation of the posterior capsule. One study compared outcomes between 12 Pipkin I/II femoral head fractures managed with a posterior approach and 12 managed with an anterior approach. With the anterior approach, they reported a significant reduction in operative time and blood loss and no cases of AVN; however, they reported a significantly higher rate of heterotopic ossification compared to a posterior approach.²⁷ A recent case report evaluated the utility of the DAA for fixation of 2 Pipkin II femoral head fractures. Both patients were doing well at 9 months follow up, although one had developed Brooker I heterotopic ossification (HO). The authors overall support the DAA as a simple, tissue sparing approach for operative femoral head fractures, and also advocate for its use for irreducible femoral neck fractures.²⁸ While the authors of both studies cite HO as a notable concern with the DAA, a recent large meta-analysis (n = 3427) investigating rates of HO found that the DAA is associated with a lower rate of HO compared to the anterolateral and posterior approaches to the hip in the setting of THA.²⁹ These findings support the DAA as an approach that minimizes operative time, risk, and postoperative complications in the setting of a femoral head fracture.

Loose or foreign body removal from the hip has historically been performed through a direct arthrotomy, dislocation of the hip, and removal of loose body (e.g., osteochondral fragment, metal debris, etc.). However, hip arthroscopy for loose/foreign body extraction has become popular as a low-risk, minimally invasive procedure with favorable outcomes.³⁰ In situations where you have femoral head fracture requiring fixation in addition to concomitant loose bodies requiring removal, the DAA may be the preferred option for fracture visualization as we have previously described. However, removal of loose/foreign bodies, particularly in the posterior recess, may be difficult when using this approach. One case series describes the use of a Satinsky vascular clamp, which has small, curved jaws to reach loose bodies in the posterior recess without requiring hip dislocation.³¹ To date, this is the only study describing a technique for removal of difficult loose bodies through an anterior approach.

3.1. DAA for hip hemiarthroplasty

While the indications for hemiarthroplasty for the treatment of femoral neck fractures is controversial, it remains an increasingly common modality for low-demand geriatric patients.¹¹ Regarding the surgical technique, the initial exposure is consistent with that of a primary DAA THA utilizing the inter-nervous plane between the tensor fascia lata and the sartorius muscles. After the capsule is incised and retractors are placed superior and inferior to the femoral neck, the remaining part of the femoral neck and head are removed, and the head is measured to determine the correct implant head size. Retractors are then placed at the greater trochanter and medially to support and expose the femur. A soft tissue release may be performed to enhance exposure and bring the femur forward. Standard femoral canal broaching and implant trialing is them performed to determine the appropriate final implants.³²

Several studies have demonstrated robust outcomes for utilization of the DAA for hemiarthroplasty in the setting of femoral neck fractures, particularly in comparison to other conventional approaches. In a prospective study by Krassnig et al. in Germany, 83 patients undergoing a hemiarthroplasty for a femoral neck fracture were randomized either to undergo a DAA or an anterolateral approach (ALA). The study found that postoperative pain levels were significantly lower in the anterior cohort compared to the anterolateral cohort. A significantly greater percentage of DAA patients were discharged home (40 %) as opposed to a rehabilitation facility when compared to the ALA group (16.3 %). In addition, the DAA group had lower rates of heterotopic ossification at 6 and 12 weeks postoperatively. 60 % of the DAA and 67.4 % of the ALA cases were cement augmented, based on the surgeon's assessment of each patient's bone quality. The authors had a slightly longer mean surgical time when using the DAA vs. the ALA (86.9 vs. 83.6 min); however, this was not statistically significant.³³ In a similar comparison of these two approaches in hemiarthroplasty for femoral neck fractures (51 DAA, 43 ALA), Bűcs et al. found that DAA patients demonstrated significantly less postoperative pain and shorter hospital stays. Furthermore, they found that patients who underwent DAA had a lesser degree of leg length discrepancy and fewer patients were seen limping at 12 weeks postoperatively. Furthermore, Harris Hip Scores were significantly better in DAA patients compared to ALA at 2 and 6 weeks after surgery (77 vs. 65 and 91 vs. 77, respectively). There were no significant differences in intraoperative complications, blood loss, or transfusion requirements between the two groups. While the operative preparation took more time for DAA cohort, there was no significant difference in time from surgical incision to closure. DAA patients had a significantly shorter mean hospital stay (1.41 vs. 3.09 days).³⁴ One explanation for lower pain scores and earlier hospital discharge in DAA patients may be that muscles are primarily retracted in DAA, while some muscles are incised in the ALA.

In multiple large systematic review studies investigating DAA in hemiarthroplasty for femoral neck fractures, DAA was found to be associated with reduced hospital stay, early functional recovery, lower dislocation rates, and lower early postoperative pain scores, and overall fewer total complications.^11,12,35 Overall, there is robust evidence in the literature to support the DAA for hemiarthroplasty in the setting of femoral neck fractures. Given the significant morbidity and mortality associated with femoral neck fractures in geriatric patients, the DAA may be another important factor in further improving outcomes for geriatric femoral neck fractures.

4. DAA for THA in the setting of femoral neck fractures

Total Hip Arthroplasty (THA) is a viable treatment option for physically active patients without cognitive impairment suffering from displaced femoral neck fractures. It particularly efficacious among patients with antecedent symptomatic hip arthritis. According to an analysis of 25 randomized controlled trials (RCTs) performed by Tang and coauthors, THA demonstrates superior mid-term functional outcomes, improved quality of life, and fewer instances of reoperations compared to hemiarthroplasty.³⁶

There are several challenges associated with THA, including an increased risk of dislocation, prolonged surgical duration, and an extended hospital stay. The DAA has been shown to mitigate some of these challenges, offering improved early postoperative mobility, lower pain scores, decreased opioid requirements, and lower dislocation rate.³⁷ Medium-term data from the Australian Orthopaedic Association National Joint Replacement Registry indicates a reduced risk of revision surgery for recurrent dislocations among those who underwent DAA THA compared to those undergoing a posterior-based approach.³⁸

Despite its benefits, the DAA has its own unique challenges, such as difficulty in femoral preparation leading to iatrogenic femur fracture or early postoperative stem loosening and potential wound healing problems, particularly in patients with elevated BMI. Careful surgical technique, including the utilization of the bikini approach, have been shown to reduce the risk of wound healing complications.³⁷ The sequential soft tissue release proposed by Chughati et al. allows safe mobilization of the proximal femur reducing the risk of periprosthetic fracture.³⁹ Proper exposure and visualization allow accurate implant sizing and fitting, reducing the risk of early postoperative loosening of the press-fit stem. When implementing a cemented stem, optimal femoral preparation is achievable through clear visualization of the proximal femur. The DAA is easily extendable, providing outstanding visualization of both the acetabulum and distal femur and enabling control of intraoperative leg length. The approach also allows the use of intraoperative fluoroscopy to verify the implant's position. The approach can also easily be used in conjunction with a separate lateral approach if a failed femoral neck fixation requires conversion to a THA (Fig. 1).

Fig. 1.

Direct anterior approach used in conjunction with lateral approach to femur for THA conversion. The above photo depicts the usage of the DAA for exposure of the femoral head/neck and acetabulum for THA, as well as a separate lateral incision for removal of the prior sliding hip screw construct. Both incisions were easily accessible with standard supine positioning and draping.

Historically, the direct anterior approach had a steep learning curve, with a reduction in complications linked to the surgeon's experience. Recent analysis by Wilson and colleagues suggests that the historically reported concerns about the learning curve are now likely much less significant, especially for surgeons with fellowship training in centers where the DAA is routine practice.⁴⁰

The surgical technique for DAA THA in femoral neck fracture does not differ from the technique used for elective hip arthroplasty. Using the modified Smith-Petersen interval, the exposure femoral head and neck exposed, removed, and sized. Following this, the acetabulum is exposed and prepared for cup implantation. After cup placement, the femoral canal is prepared, utilizing appropriate soft tissue releases to elevate and properly exposed, starting with a sequential release from supero-lateral capsular release, followed by conjoined tendon and piriformis tendon release if necessary. The preservation of the obturator externus tendon is advocated for its role in hip joint stability. In the case of most geriatric or osteoporotic patients with femoral neck fragility fractures, it is advisable to employ cemented stems to mitigate the risk of periprosthetic femur fractures in this specific patient population. After the final implants are positioned, the hip undergoes reduction, and its stability is evaluated. Employing the off-table technique endorsed by Keggi et al. facilitates a straightforward assessment of the implant position, stability, and the presence of impingement by testing the implants across the full range of motion.⁴¹ In contrast, the on-table technique, popularized by Matta et al. allows for the use of fluoroscopy to confirm the implant position.⁴² The surgical incision is closed in layers and sterile dressing is applied. No postoperative precautions are advised.

5. Conclusions

Overall, the literature supports the DAA as a safe and efficacious approach specifically for the management of femoral neck fractures. The DAA is versatile in allowing supine positioning and fluoroscopic verification of fracture reduction during ORIF of femoral neck fractures in young patients, mitigating risk of avascular necrosis and nonunion. Furthermore, emerging reports suggest that the DAA has been effective in the fixation of femoral head fractures, importantly preserving the posterior capsule and mitigating the risk of dislocation. There is robust evidence supporting usage of the DAA for hemiarthroplasty and total arthroplasty, with large meta-analyses suggesting that the DAA is, in fact, superior to other approaches with regard to overall complication rate, length of stay, postoperative pain, and early functional recovery. As more data emerges in support of the DAA compared to other surgical approaches to the hip, complications related to surgeon inexperience is a notable consideration; however, these risks tend to normalize after the first 100 cases. Looking toward the future with an aging population and projected rise in femoral neck fractures, we should anticipate a growing body of literature and data on the efficacy of the DAA, especially compared to other approaches to the hip, and seek to further elucidate the DAA as a surgical technique that may help us optimize the high morbidity and mortality associated with geriatric femoral neck fractures.

CRediT authorship contribution statement

Rajiv S. Vasudevan: Writing – original draft, Writing – review & editing, Conceptualization. Andrzej Brzezinski: Writing – original draft, Writing – review & editing. Stephanie Kaszuba: Writing – original draft, Writing – review & editing. Lidia Ani: Writing – original draft, Writing – review & editing. Maritza D. Essis: Writing – original draft, Writing – review & editing. Lee E. Rubin: Writing – original draft, Writing – review & editing, Conceptualization, Supervision.

Patient consent

Not applicable.

Ethical clearance

Not applicable.

Source of funding

None.

Declaration of competing interests

Rajiv S. Vasudevan, Andrzej Brzezinski, Stephanie Kaszuba, Lidia Ani, Diane EssisI have no competing interests to declare.

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