Anterior Approach Total Hip Arthroplasty

J. Bohannon Mason

Michael Taunton

INDICATIONS/CONTRAINDICATIONS

There has been an increased interest in the anterior approach for total hip arthroplasty (THA) in the United States over the last 5 to 10 years (1). This increased attention has grown from surgeon and patient desires’ for rapid recovery, reduced dislocation risk, and increased component accuracy, which have been advocated as benefits of this approach, as well as a multiplicity of economic and marketing pressures, which have influenced surgeons to examine their surgical approach to the hip.

The anterior approach was first described by Smith-Peterson in 1917 (2,3) and used for mold arthroplasties. Heuter modified the classic Smith-Peterson approach, utilizing the inferior limb of the incision, dissecting between the sartorius muscle medially and the tensor muscle laterally and the tensor and rectus muscles deep onto the hip capsule. Judet (4) utilized an anterior approach in conjunction with a traction table for hip procedures including early arthroplasty. Following positive personal experience with the anterior approach for total hip arthroplasty, Joel Matta popularized this approach in the United States, touting the intermuscular, internervous plain to the hip joint as an approach that did not disrupt the abductor or “deltoid muscles” of the hip (5).

While several well-described approaches can be considered for routine total hip arthroplasty, the anterior approach has long been utilized for nonarthroplasty interventions requiring arthrotomy of the hip joint including removing of loose bodies, drainage of sepsis, and fractures of the femoral head. Recently, it has been advocated for patients seeking a more rapid recovery from the surgical trauma of hip arthroplasty. Although this last point remains controversial, strict indications for anterior total hip arthroplasty do not exist. Relative indications for utilizing an anterior approach
include patients who are at higher risk for postoperative dislocation. This includes patients suffering neurologic conditions such as multiple sclerosis, prior stroke, or patient factors such as cognitive impairment, substance abuse, or parkinsonism that may additionally be considered. Patients suffering from collagen vascular disorders such as Ehlers-Danlos or patients with prior hip fusion, particularly those with anteriorly placed hardware, are relative indications for an anterior approach.

Contraindications to the use of anterior approach vary according to the surgeon’s experience with extensile techniques employed via this approach and consequently are relative. That said, anterior approach is not generally selected for patients requiring trochanteric osteotomy for exposure or in patients with high-riding developmental dysplasia in which subtrochanteric osteotomy is required. Additionally for some surgeons, arthroplasty situations requiring the use of a straight stems may prove problematic and are a relative contraindication. Revision arthroplasty, when more extensile femoral exposure is required, is a relative contraindication for an anterior approach arthroplasty. Additionally, patients with personal hygiene issues, very large abdominal pannus, or with obvious skin irritation and/or fungal infection in the hip flexion crease are at risk for periprosthetic infection if explored via an anterior approach.

A number of recent studies have reported outcomes comparing direct anterior approach (DAA) THA to other approaches. Nakata et al. (6) reported faster recovery of hip function and gait mechanics with DAA compared to posterior approach THA. A retrospective MRI study comparing DAA to transgluteal approach found better soft tissue response, and another study found decreased creatine kinase, a marker for muscle tissue damage, in patients undergoing DAA compared to posterior approach THA (7,8). In a prospective randomized comparison of DAA to posterior approach, Barrett et al. (9) found improvements in early functional recovery and VAS scores for the DAA group that persisted to 3 months. We conducted a similar prospective randomized trial comparing DAA to miniposterior approach and found earlier cessation of walking aids with the anterior cohort (10). Additionally, Rodriguez et al. (11) found faster functional recovery and comparable safety with DAA compared to posterior approach, yet the functional gains did not persist beyond 2 weeks. The early functional recovery gains were reflected in another case series where hospital length of stay was significantly shorter for the DAA group compared to posterior approach (12). In another prospective series, the outcome variance between anterior and posterior patients undergoing advanced rehabilitation protocols was minimal (13).

Gait analysis has documented minimal difference in gait parameters between anterior and posterior approach patients, but greater postoperative stiffness in patients undergoing posterior approach (14,15). A prospective randomized trial comparing DAA with anterolateral approach found significantly better SF-36, WOMAC, and linear analogue scale assessment scores for the DAA patients, which persisted beyond 6 months (16). Several authors have shown improvement in acetabular component accuracy with the combined use of fluoroscopy and DAA, but without defined clinical benefit (17,18). Improvements in capsular closure and the use of larger heads have reduced the likelihood of instability following posterior approach THA to 1% to 2% some series (19). Many authors have shown equally low rates of dislocation with DAA, yet rates of revision for instability following DAA are 0.1%, superior to posterior THA (20). In contrast to the equivalent safety profiles reported in each of the aforementioned studies, some studies have highlighted technical concerns with DAA, documenting higher intraoperative fracture risk, higher complication risk, and higher blood loss in the early learning series (21,22).

PREOPERATIVE PLANNING AND PATIENT SELECTION

In patients with hip disease requiring THA, an anteroposterior standing pelvic x-ray and a Lowenstein lateral radiograph of the hip are obtained. We typically employ digital templating with a standardized magnification marker. Care is taken in the templating process to ascertain ideal component position, beginning first with the acetabular component. The depth and sizing of the acetabular component is patient specific, but generally, we attempt to reproduce the native hip center for each patient. Leg lengths are carefully evaluated, and the effect of stem position, neck resection level, and prosthetic head length are all ascertained and recorded in the preoperative templated plan. With regard to the acetabular component position, templated acetabular component position is noted relative to the patient’s radiographic teardrop. This landmark can be easily evaluated intraoperatively with the assistance of fluoroscopy and consequentially reproduced according to the templated plan. Limb length differences (LLDs) are measured on the templated x-ray, referencing a horizontally line at the base of the teardrop of the pelvis on both sides and compared to a line drawn between two fixed femoral references, typically the top of the lesser trochanters. The measured LLD should
be interpreted clinically with attention paid to fixed pelvic obliquity or discrepancies in extremity lengths, which occur below the level of the hip joint. In such instances, clinical measurement of limb inequality with blocks can be helpful. Stem selection, shape, and fill are all contingent upon variances in endosteal anatomy of the patient. Anatomic femoral offset also figures prominently into stem selection. With careful attention to templating, the patient’s limb length and femoral offset can be optimized, assisting with abductor mechanics and soft tissue tension.

Patient

Positioning

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