This article is more than 5 years old. Information may no longer be current.
Avoid pitfalls in the direct anterior hip approach for primary and revision total hips
Click Here to Manage Email Alerts
The direct anterior, or the anterior supine intermuscular, approach for total hip arthroplasty continues to gain acceptance with surgeons as patient demand for the procedure remains high. Many studies have demonstrated advantages with the approach, including improved gait symmetry at 6 weeks postoperatively, decreased dislocation rate, decreased muscle damage, decreased pain and more accurate leg-length restoration when compared with the posterior approach. The reduced hospital stay and earlier return to activities, such as driving, work, and recreation, afforded by the approach is appealing to both middle-age and elderly patients. In experienced hands, the anterior approach total hip arthroplasty is a safe and effective procedure. However, the approach does carry a lengthy learning curve and may result in an increased complication rate during the learning period.
A recent series from a community hospital early in the learning curve demonstrated a high complication rate (16.4%) and reoperation incidence (6.5%). While early return to unrestricted physical activity without hip precautions is attractive, direct anterior approach (DAA) benefits may be counterbalanced by these potential early risks. Siguier and colleagues reported the results of 1037 total hip arthroplasties (THAs) using the anterior supine intermuscular approach on an orthopedic table. Their dislocation rate was 0.96%. Additional complications included two femoral nerve palsies, five deep infections, and one ankle fracture. Matta and colleagues. reported a series of 494 primary THAs performed through an anterior approach on an orthopedic table. Seventeen (3.89%) complications occurred, including one deep infection, three wound infections, one transient femoral nerve palsy, three greater trochanteric fractures, two femoral shaft fractures, four calcar fractures and three ankle fractures. Injury to branches of the lateral femoral cutaneous nerve is a recognized complication after anterior approach THA. The distal branches of the lateral femoral cutaneous nerve (LCFN) are at risk with distal extension of the incision. Goulding and colleagues. reported LCFN neurapraxia in 107 (81%) of 132 patients after anterior approach THA. They concluded that the incidence of LCFN neuropraxia is underreported, but the condition does not lead to functional limitations. Increased blood loss has also been demonstrated with the DAA when compared to the posterior approach. Jewett and Collis reported a 4.6% rate of serious wound-healing complications in their series, with a 1.6% reoperation rate for superficial wound infections and wound necrosis. Though these complications can be problematic and worrisome, they are not exclusive to the anterior approach, and their risk can be significantly mitigated by recognizing their potential and taking the appropriate steps.
Avoiding injury, complications
The LFCN travels adjacent the incision and lays over the sartorius, within the sartorial sheath before penetrating the fascia approximately 10 cm distal to the anterior superior iliac spine (ASIS) to supply the skin of the anterior and lateral thigh through its anterior and posterior branches. To avoid injury, the incision is moved slightly lateral, usually starting two fingerbreadths lateral to the ASIS and extending slightly obliquely in the direction of the lateral knee. This trajectory helps avoid direct exposure and injury to the LFCN branches. Identifying this appropriate position is especially important in obese patients, in which the planes of dissection may be obscured by subcutaneous fat. During the approach, incising the fascia over the tensor fascia lata (TFL) muscle and staying within the TFL sheath (outside of the sartorial sheath) offers the best protection of the LFCN during the approach and throughout the case. Also, the branches of the LFCN may be exposed and protected. LFCN neuropathy resolves the vast majority of the time, and a temporary course of gabapentin may assist with pain control.
Wound problems
We avoid development of superficial skin flaps during the dissection, which can predispose to seroma formation, wound healing problems, and even skin necrosis. Care with retractor placement and limiting the length of time with retractors compressing skin edges decreases superficial soft tissue compromise. Minimizing the number of assistants, C-arm technicians and OR personnel, as well as limiting the time when the fluoroscope is placed directly over the incision, may reduce potential contamination in the surgical field. In obese patients, a longer incision is often used to avoid undue stretch and maceration of the wound edges (Figure 1).
A proximal thigh in a morbidly obese female patient with a large soft tissue abscess adjacent to the incision is shown. The patient was referred for management of the infection 4-weeks postoperatively.
Femoral head extraction with protective protractor in place is shown. The sharp edges of the cut femoral neck may injure the TFL. The protractor protects the muscle and adjacent LFCN.
Images: Siegel HJ
The incision should avoid the flexion skin fold when possible and is placed lateral to an existing pannus. The use of a disposable protractor (Alexis Retractor, Applied Medical; Rancho Santa Margarita, CA) can also be used to protect skin edges (Figure 2), and is placed underneath the TFL. Meticulous fascial closure over the TFL, and a fat closure layer or subcutaneous drain may be used to reduce dead space. An incisional sealant over the incision in addition to an occlusive antimicrobial dressing may remain in place for 4 days to 10 days.
Blood loss
Adequate identification and ligation of the lateral femoral circumflex vessels is essential. A suture ligation is recommended as opposed to electrocautery; alternatively a bipolar hemosealant device may also be used.
The hip capsule adjacent to the posterior femoral neck and the posterior acetabulum may be a source of bleeding, and should be identified during releases and pre-treated with electrocautery. Removal of the pulvinar may incite bleeding from a branch of the obturator vessel. The use of 1 gram of intravenous tranexemic acid 30 minutes prior to incision and another 1 gram at the time of closure may significantly reduce perioperative blood loss.
Proximal femoral fractures
Fractures of the proximal femur may occur intraoperatively and/or in the early postoperative period. Greater trochanteric fractures result from inadequate soft tissue release coupled with excessive femoral elevation force, either with retractors or femoral hook devices. Short, transverse femoral neck cuts also increase trochanteric fracture risk by increasing levering moment on the trochanter. Peritrochanteric spiral fractures occur from torsional moments, usually during external rotation for femoral exposure or during trial reduction and dislocation. Inadequate femoral elevation and exposure may predispose to an improper femoral stem insertion angle and may result in femoral perforation longitudinal splitting of the femoral cortex.
Greater trochanteric fractures can be managed without any fixation, as long as the stem remains well fixed. Fractures distal to the lesser trochanter often require fixation, usually in the form of tensioned cerclage cables and a stem that bypasses the fracture by at least two cortical diameters. The incision can be extended distally and laterally, and a subvastus approach can be used to expose the proximal femur for reduction and cable placement.
Acetabular component implantation
Fluoroscopy can assist with acetabular cup position, but can also be misleading. Obtaining a true AP of the pelvis is very important, eliminating any potential pelvic tilt or rotation. An inlet view of the pelvis will make the cup look more horizontal than it is, predisposing to vertical cup placement.
This intraoperative image shows acetabular cup placement in a morbidly obese patient using a double offset cup inserter.
Preoperative AP of the patient’s proximal femur is seen. A short-stem implant was used to avoid the occlude intramedullary canal and femoral deformity.
Rotation of the pelvis will affect the apparent version and abduction of the cup. During reaming, the anterior force of the thigh musculature, especially in obese and muscular patients, can predispose to over reaming the anterior acetabular wall. Offset acetabular instrumentation may assist with component positioning and reduce soft tissue injury (Figure 3).
Femoral stem implantation
Appropriate exposure of the lateral femoral neck and lateralization of the proximal femoral canal prevents potential varus stem placement. Appropriate external rotation, adduction, and extension of the femur (with or without a traction table) will assist with femoral exposure. Release of the conjoined tendon can improve femoral elevation if necessary. Keeping the knee extended will decrease anterior hip soft tissue tension and improve exposure.
Short stems are often used with DAA and they do allow for easier insertion and decreased femoral release; however, they do not forgive for inappropriate lateralization or misdirection down the canal, which will cause problems if not addressed. Judicious use of intraoperative fluoroscopy in the AP and lateral planes can help guide and confirm appropriate stem placement (Figure 4). Tapered stems are often used successfully in the DAA; however, a fit and fill stem may have the added advantage of rotational control, particularly in obese and osteoporotic patients (Figure 5). In accordance with manufacturer recommendations for press fit stems with any approach, limiting weight bearing for 4 weeks to 8 weeks may be helpful, especially in these obese and osteoporotic patients.
A new, short fit and fill femoral stem (Micromax short stem; DJO.) is shown.
The trial implants are in place. The illuminated suction tip is seen and is helpful to assist with exposure and component position.
Intraoperative fluoroscopy can help with optimization of limb length equality as well as offset. During trialing, imaging of the contralateral side can be compared (usually identifying the relation of the lesser trochanter to the ischium) or a comparative image may be taken, printed and then superimposed on an image of the contralateral hip. If the patient is not on a fracture table, both lower extremities are prepped in the surgical field, and direct comparison of the medial malleoli and/or knees (Galeazzi sign) may be performed. The feel of hip tension and stability during and after trial reduction may also be used, but this technique does require increased DAA experience.
Dislocation, deep neurologic injury
Despite the inherent stability afforded by the anterior approach, dislocation is still possible, and can occur posteriorly. Excessive release of posterior capsule and dynamic stabilizers can increase this risk, and posterolateral releases should be performed only to the extent required to deliver the femur for appropriate implantation. Inadequate anteversion of the cup can also predispose to posterior dislocation, and excessive anteversion of the femoral component (caused by inadequate femoral external rotation during exposure) can predispose to anterior instability. Some surgeons prefer to preserve and repair the anterior joint capsule, which may serve as a potential early restraint to dislocation; however this point remains controversial.
Injury to the femoral nerve may occur from excessive traction on the lower extremity during the extension, external rotation, and adduction maneuver, especially using the traction table technique. Traction must be released before proceeding to this position. Aberrant retractor placement over the anterior wall of the acetabulum may also cause injury to the femoral nerve and inappropriate posterior wall retractor position may injure the sciatic nerve; great care must be taken with the anterior and posterior wall retractors to place them as close to the bone as possible and to avoid excessive retraction.
Options, limitations of revision
Extensile exposures allow for exposure from the iliac wing to the knee. The approach may be extended proximally by release of part or all of the TFL origin. The DAA offers little access to the posterior column of the acetabulum or the greater trochanter, though the posterior column can still be reconstructed through this approach if the Harrington method (screws directed from the iliac crest to the posterior column) on intra-acetabular plate techniques are used. A periacetabular cage can be placed from the anterior approach, though this reconstruction requires extensive DAA experience and great care must be taken with ischial flange fixation.
If fixation of a displaced greater trochanter fracture is required, a separate more posterior incision may be used, though this fixation is often not necessary. An extended trochanteric osteotomy may be performed through either an approach that extends towards to lateral knee distally or through a separate direct lateral approach, with both using a subvastus technique. Straight reaming of the femoral canal can be performed through the DAA, but requires appropriate femoral release and exposure. Fluoroscopy is helpful to assist with location of osteotomy and direction of reaming in these cases.
The fracture table is commonly used with the DAA because it often provides assistance with limb positioning and exposure. In these cases, the surgeon should always maintain control of the leg; and while assistants will need to operate the table, hip rotation and extension needs to be guided by the surgeon with his hand on the proximal femur and / or knee. OR staff must be trained with regards to the optimal extremity positions, traction control, limb positioning and securing the patient. The femoral elevator attachment is also useful to assist with exposure and to stabilize the proximal femur, though excessive elevation can lead to levering forces on the greater trochanter and subsequent fracture. The standard radiolucent operating table has the advantage of complete surgeon control and feel of the entire operative extremity and easy comparison to the contralateral side. A break in the table is often helpful with exposure, which allows the hip to extend up to 60°, and facilitates femoral positioning and broaching. Use of the standard table may decrease some of the complications seen with the fracture table, such as femoral fracture, knee ligamentous injury, ankle fracture, and transient femoral nerve palsies, however may require additional assistants. Table attachments with femoral elevators (TeDan Surgical Innovations; Houston) and lighted retractors and/or suction tips (Eigr Saber Waveguide; Invuity, San Francisco, CA) are routinely used to assist with exposure and implant positioning (Figure 6).
The increasing demand from both patients and surgeons to perform the DAA has led to a demand for education, advancements in instrumentation and novel femoral stems. It has become a widely recognized, safe, and effective means by which to perform total hip arthroplasty, and may have several advantages including: decreased pain, decreased hospital length of stay, quicker early recovery, decreased dislocation risk, and decreased muscle damage, though at the expense of increased technical demands and potential complications, especially early during the surgeon’s learning of the approach. Following the key steps and avoiding common pitfalls will shorten the learning curve and improve early outcomes.
References:
Barrett WP, et al. J Arthroplasty. 2013;doi: 10.1016/j.arth.2013.01.034.
Bhandari M, et al. Orthop Clin North Am. 2009;doi: 10.1016/j.ocl.2009.03.001.
Benoit B, et al. Orthop Clin North Am. 2009;doi: 10.1016/j.ocl.2009.02.002.
Berend KR, et al. J Bone Joint Surg Am. 2009;doi: 10.2106/JBJS.I.00525.
Bergin PF, et al. J Bone Joint Surg Am. 2011;doi: 10.2106/JBJS.J.00557.
Goulding K, et al. Clin Orthop Relat Res. 2010;doi: 10.1007/s11999-010-1406-5.
Jewett BA, et al. Clin Orthop Relat Res. 2011;doi: 10.1007/s11999-010-1568-1.
Martin CT, et al. J Arthroplasty. 2013;doi: 10.1016/j.arth.2012.10.029.
Matta JM, et al. Clin Orthop Relat Res. 2005;441:115-124.
Mayr E, et al. Clin Biomech (Bristol, Avon). 2009;24(10):812-818.
Masonis J, et al. Orthopedics. 2008;31(12 Suppl 2).
Nakata K, et al. J Arthroplasty. 2009;doi: 10.1016/j.arth.2008.04.012.
Sariali E, et al. J Arthroplasty. 2008;doi: 10.1016/j.arth.2007.04.003.
Seng BE, et al. Orthop Clin North Am. 2009; doi: 10.1016/j.ocl.2009.01.002.
Sendtner E, et al. Arch Orthop Trauma Surg. 2011;doi: 10.1007/s00402-010-1174-4.
Siguier T, et al. Clin Orthop Relat Res. 2004;(426):164-173.
Woolson ST, et al. J Arthroplasty. 2009;doi: 10.1016/j.arth.2009.04.001.
Yi C, et al. Orthopedics. 2013;doi: 10.3928/01477447-20130222-14.
Zawadsky MW, et al. J Arthroplasty. 2014;doi: 10.1016/j.arth.2013.11.013.
For more information:
Herrick J. Siegel, MD, can be reached at University of Alabama at Birmingham, Division of Orthopaedic Surgery, 1313 13th St. S., Birmingham, AL, 35205; email: hsiegel@uabmc.edu.
Daniel C. Allison, MD, can be reached at Cedars-Sinai Medical Center, 444 S. San Vincente, Suite 603, Los Angeles, CA; email: dallison12@hotmail.com.
Disclosures: Siegel has consultant agreements with DJO, Corin, Stanmore, Invuity, Biomet and Aesculap. Allison has consultant agreements with Exactech, Ortho Development, TeDan Surgical Innovations, Carbo-Fix LTD and Convatec Inc; receives royalties for a minimally invasive femoral stem from Ortho Development Corporation; and receives royalties from TeDan Surgical Innovations for an anterior hip retractor system.