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Anterior approach to THA enables the procedure to be performed in ASCs
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The anterior approach to total hip arthroplasty is creating a clinical shift among practitioners. According to some reports, about 20% of orthopedic surgeons who perform THA now use this approach and more patients seek surgeons who offer the technique. Although the anterior THA approach is relatively new in the United States, its use is rapidly expanding due to advancements in technology and improved training opportunities available to U.S. surgeons.
In the past, patients undergoing THA expected to be hospitalized for several days. Newer protocols, including multimodal pain management, blood management, streamlined equipment, improved imaging and adoption of tissue-sparing surgical techniques, including the anterior approach, have contributed to the migration of THA to the outpatient environment.
In application, the anterior approach goes through the front of the hip, preserving the gluteal muscles and making recovery faster by preserving the muscular envelope around the hip. It also makes the patient’s postoperative course more predictable by reducing some of the complications seen in more standard techniques. Therefore, an early transition to the home environment after THA performed with the anterior approach may be more comfortable for the patient and practitioner alike.
Table aids imaging, positioning
The Hana table (Mizuho OSI) facilitates the use of fluoroscopy and standardization of patient positioning which makes imaging and implantation of the prosthesis more reliable. The ability to use fluoroscopy to guide implant placement makes the anterior approach a reliable way to achieve an ideal implant position. An excellent implant position translates into more appropriate soft tissue tension and leg length and, potentially, more reliable and durable function of the prosthesis. Improvements in exposure made possible by using the Hana table during surgery make the anterior surgical procedure more applicable to patients with a wider variety of body types and hip pathologies.
The most common concerns with the anterior approach are numbness of the lateral femoral cutaneous nerve (LFCN), and the steep learning curve. With attention to surgical technique and judicious use of medication, such as gamma-aminobutyric acid analogs like Lyrica (pregabalin, Pfizer) or gabapentin, we have found LFCN causalgia to be manageable. We are finding that as there has been more exposure to the procedure in residencies, fellowships and industry-sponsored learning environments, the learning curve has similarly been shortened for the surgeon.
In our experience at the Hip and Pelvis Institute of San Francisco, the anterior approach, as described by Joel M. Matta, MD, has been well suited to the outpatient environment. Most patients begin walking immediately postoperatively and can quickly manage the home environment, which allows for early discharge. Table adapters, such as the Hana SSXT, have a smaller footprint and are therefore well-suited to the ASC setting. As there continue to be more ASCs in operation in the United States and more insurers recognize the cost-savings associated with the outpatient environment, more THA patients are expected to be treated in this setting vs. hospitals and hospital outpatient departments.
Proper positioning on the table
The surgical technique used at our center generally relies on the use of the orthopedic table in the OR. A few table options exist for THA, but we find the Hana orthopedic table with its femoral lift to be particularly well suited to this technique. The femoral lift aids femoral exposure without requiring an additional set of hands. In the ASC, physical space is usually at a premium, so one less person in the OR translates into benefits in terms of cost and space.
Draping of the patient is facilitated by the orthopedic table because commonly only the surgical field is draped using an adhesive drape via a “shower curtain” or similar draping technique. This saves time and is easily performed by the OR support staff (Figure 1).
Source: Nicholas H. Mast, MD
Surgical approach
The approach starts with an incision 2 cm to 3 cm posterior and 1 cm to 2 cm distal to the anterior superior iliac spine. A vinyl circumferential skin retractor is placed so that it slightly undermines the fat layer off the underlying fascia and the fascial incision is continued slightly distal and proximal beyond the ends of the skin incision. During the subcutaneous dissection, the branches of the LFCN will commonly be encountered and should be protected when possible (Figure 2).
A cobra retractor is placed along the lateral hip capsule to retract the tensor and gluteus minimus laterally and a Hibbs retractor is used to retract the sartorius and rectus femoris muscles medially. A small periosteal elevator is placed just distal to the reflected head and directed medial and distal, which opens the path for a second cobra retractor to be placed on the medial hip capsule. If necessary, progress with the THA can be checked with imaging (Figure 3).
The lateral femoral circumflex vessels are then clamped, cauterized and transected. The distal anterior capsule is detached from the femur at the anterior intertrochanteric line and suture tags are placed on the anterior and lateral capsule at the distal portion of the incision that separates them. The cobra retractors are placed intracapsular both medial and lateral to the neck. Base of the neck exposure is facilitated by a Hibbs retractor, which retracts the vastus and distal tensor.
Extremity dislocation
A femoral head skid is placed into the gap between the femoral head and the roof of the acetabulum and then moved to a more medial position. The patient’s hip should be externally rotated about 20°, after which a femoral head cork screw should be inserted into the femoral head in a vertical direction. As the extremity and hip are externally rotated and leverage is applied to the skid and cork screw, the hip becomes dislocated anteriorly and the femur is externally rotated 90°.
The capsule should now be detached from the medial neck and the lesser trochanter and the medial posterior neck should be exposed. Internally rotate and reduce the hip. Replace the cobra retractors around the medial and lateral neck and retract the vastus origin and distal tensor using a Hibbs retractor. Cut the femoral neck with a reciprocating saw at the desired level and angle according to the preoperative surgical plan. Extract the head with the corkscrew. Use light traction, if needed, to help distract the neck osteotomy.
Anterior THA is begun by cutting the neck in situ and extracting the femoral head. Throughout the procedure, the surgeon will find the tensor fascia lata muscle is potentially vulnerable to injury, so care should be taken during the retraction portion of the case.
Reaming, cup implantation
Place a cobra retractor with the tip on the mid-posterior rim and excise the labrum circumferentially. Reaming is begun under direct vision and later checked with the image intensifier to confirm depth of reaming and adequacy of its circumference. The indicators of torque and acetabular appearance are also used. The acetabular prosthesis is inserted with a curved handle inserter. Whether the pelvis is level can be confirmed by the symmetry of the obturator foramina or centering of the coccyx to the symphysis. The liner is inserted, which is facilitated by prior excision of the labrum and release of the inferior capsule.
After acetabular component insertion, gross traction control on the leg spar is released and the femur is internally rotated to neutral. For proximal femoral exposure, a long-handled cobra is used with the tip on the posterior femoral neck and the tip of a trochanteric retractor is placed over the tip of the trochanter. The proximal femur is now raised by the femoral hook until the tissues come under moderate tension. The lateral capsular flap is detached from the base of the neck in an anterior-to-posterior direction, which facilitates visualization of the medial greater trochanter and enhances femoral mobility. A rongeur is used to excise the remnant of the lateral neck.
Retract muscles, tendons
After release of the lateral capsule, the tip of the trochanteric retractor is placed closer to the upper border of the trochanter to retract the gluteus minimus muscle and piriformis and obturator internus tendons. The femoral rotation and broach anteversion should be assessed and the patella palpated to determine femoral rotation.
Once broaching is complete, a trial reduction is made. Neck length is estimated from the preoperative template. The hip is flexed to the neutral position, traction is applied, the hip is reduced with internal rotation and, if necessary, with a push on the femoral head. When comparing image views of both hips, it is suggested that both hips be placed in comparable positions in terms of flexion, abduction/adduction and rotation.
After the femoral prosthesis is selected, the femoral hook is replaced behind the proximal femur, traction is applied to distract the head and the hip is dislocated with external rotation. A bone hook also may be placed around the femoral neck to aid distraction. The femur is then placed in the preparation position and the femoral prosthesis is inserted as usual. A permanent head with the appropriate length can now be placed. The anterior and lateral capsular tag sutures are tied together and, if desired, any further capsular closure can be performed. The fascia lata is closed using a running suture followed by subcutaneous skin-closure. Radiographs obtained prior to discharge will confirm appropriate implant placement and reconstruction (Figure 4).
Postoperatively, the patient does not need to follow anti-dislocation precautions. He or she is encouraged to weight-bear immediately and use his or her hip. Patients may discontinue the use of any external support devices as their symptoms allow.
- References:
- Barton C, et al. Orthop Clin North Am. 2009;doi:10.1016/j.ocl.2009.04.004.
- Kamath AF, et al. J Med Econ. 2018;doi:10.1080/13696998.2017.1393428.
- Matta JM, et al. J Bone Joint Surg Am. 2011;doi:10.2106/JBJS.J.01736.
- Mast, NH, et al. Orthop Clin North Am. 2009;doi:10.1016/j.ocl.2009.04.002.
- Mast NH, et al. J Bone Joint Surg Am. 2011;doi: 10.2106/JBJS.J.01736.
- Toy PC, et al. J Arthroplasty. 2018;doi:10.1016/j.arth.2017.08.026.
- For more information:
- Nicholas H. Mast, MD, can be reached at Hip and Pelvis Institute of San Francisco, 2299 Post St., #107, San Francisco, CA 94115; email: doctormast@yahoo.com.
Disclosure: Mast reports he is a paid consultant and paid presenter or speaker for DePuy Synthes, A Johnson & Johnson Company, and he receives stock or stock options from Radlink.