Direct Anterior Approach for Total Hip Arthroplasty

Indications

The technical essentials of total hip arthroplasty include the restoration of anatomic relationships including the center of rotation, leg length, and offset.  The goal is at the same time to preserve musculature, avoid complications, and for the surgeon to be able to reproducibly implant the components.

The direct anterior approach utilizing the orthopedic bed with fluoroscopic assistance has been designed to have predictable component alignment and  minimized muscle damage, thus decreasing instability.

The direct anterior approach has been around for over 60 years, and has been popularized in the US by  Keggi and Matta.

Most recently, Hozack has reported a prospective randomized study that found direct anterior approach has a significant improvement in the SF-36 and WOMAC scores at 6 weeks, 6 months, and even at one year when compared with anterolateral approach.

But is it safe? Is the complication rate higher? Masonis from Orthocarolina, reported on his first 300 cases.  One dislocation in 300, which aligns with Matta’s published rate of 0.6%. Component implantation was reliable, and there were 3 calcar cracks. Three patients with BMIs greater than 40 had superficial I&Ds. Revisions included one at 4 months for deep infection, one fibrous stem, one squeaker, and one for ill defined thigh pain with well fixed components.

These favorable results are tempered by Woolson’s paper of 247 THAs with a 9% complication rate, high blood loss, and long operative times.  On deeper inspection we do note that these surgeons were doing the procedure relatively infrequently (2 a month on average) with only one day of observational formalized training.

I would agree that there is a definite learning curve for the approach, but it can be effectively mitigated by good, formalized training, such as a fellowship, or more extended courses with cadaveric training.  Certain patients, such as those who practice yoga, or require a greater stable range of motion may particularly benefit from the approach. To additionally control the learning curve, patient selection can play a big role. Using preoperative films, surgeons can identify patients that will be more challenging through the direct anterior approach.  With this knowledge, patients can be selected more carefully during the learning curve. A wide ilium with a narrow inner ischial distance, and  coxa breva is going to be an example of a harder case.

Preoperative Planning

Anatomic Conisderations in preoperative  planning

• Femoral Neck Length
• Neck Shaft Angle
• Protrusio Acetabuli
• Ilium Morphology
• Inner Ischial distance

Positioning

Supine

Approach

An oblique incision is made over the anterior margin of the tensor muscle at a point approximately 3 centimeters lateral from the anterior superior iliac spine and extending 10 to 14 centimeters to the anterior 1/3 of the greater trochanter (should follow the fibers of the TFL).

Internervous plane
A True Internervous Plane

• Lateral: Superior and inferior gluteal nerves
• Medial: Femoral nerve

The muscular interval for the Heuter approach is between the TFL and the Sartorius and rectus.

Techniques

Video: Direct Anterior Total Hip Arthroplasty

Management of the patient for direct anterior approach includes placement of the patient on a special table which allows hyperextension and adduction of the operative extremity while the pelvis is stabilized through counter traction on the contralateral extremity. An OSI ProFx® table and an OSI Hana® table are used. The variation in table usage is based on hospital, and has no impact on the procedure.

An oblique incision is made over the anterior margin of the tensor muscle at a point approximately 3 centimeters lateral from the anterior superior iliac spine and extending 10 to 14 centimeters to the anterior 1/3 of the greater trochanter (should follow the fibers of the TFL). The fascia of the tensor muscle is identified and incised. The edge of the fascia is elevated with a Allis clamp. A Cobb retractor is used to elevate the fascia from the TFL (start inferiorly and sweep up). The muscle is swept digitally laterally with a finger. Use finger to drop over to the superior neck, and place Cobra retractor over the superior aspect of the femoral neck. Use hip retractor inferiorly . Use tonsil and cautery to identify and cauterize the ascending branch of the lateral femoral circumflex artery. Inferior Cobb retractor is then placed beneath the inferior femoral neck. Remove the overlying fat. Use a lap sponge to clean up. Use a #1 to lift the rectus. Identify the reflected head, and release in line with the planned capsulotomy. The hip capsule is then incised with a 135 degree L shaped incision, in line with the superior femoral neck, and the intertrochanteric line. A suture is placed in the capsule at the angle. The inferior cobra is placed inside the capsule. The superior capsule is released in line with the lateral limb of the previous capsulotomy. The capsule is tagged, and the superior Cobra retractor is placed inside of the capsule. The capsule is retracted.

Externally rotate to 40 degrees. Release the inferior capsule off of the femoral neck. Internally rotate back to 0. Place the #1 over the labrum anteriorly. Use the Beaver blade to remove a portion of the capsule. Place gross traction. A measured resection of the femoral neck is performed with the assistance of fluoroscopy and pre-operative templates. Use the cautery to mark the planned resection. Bring in the fluoroscopy to verify – use cautery tip to identify- remove Cobras for Xray. Replace the Cobras. Make the osteotomy with a precision saw. Make sure to get across the Calcar. Use a Cobb retractor to flex the osteotomized femoral head. Insert the femoral head Christmas tree. Remove femoral head manually. The traction is released and the leg is left in a slightly externally rotated position (40 degrees) and retractors are placed to expose the acetabulum. A #1 retractor is placed on the anterior rim, angled toward the head. Locate the superior-posterior capsule at the previous split – split capsule and release from posterior wall a limited amount. See the posterior acetabular rim all around. Allows freedom for femur to fall back. Release the inferior capsule. Protect the psoas and retract – release TAL anteriorly. Then with the Beaver blade, excise the anterior then the posterior labrum. Place the #2 retractor posteriorly.

Ream with offset reamer with the #1 anteriorly and the #2 posteriorly. Acetabular reaming is performed with the fluoroscopic assistance and direct visualization. Sometimes some traction is needed to keep the calcar out of the way – also may lift the leg or release a bit more. To evaluate the correct reaming position may need to adjust the C-arm Inlet/outlet, over/back. Then center over the socket look for appropriate medialization, coverage, anteversion, size. Place cup with the plastic cover, and remove cover with Grasper. Turn the cup clockwise for correct screw placement position. Impact partially, and check Xray, impact fully. Place screws. Make sure to get even with cup edge. Number depends on age, bone quality, fixation. After placement of the acetabular component and confirmation of the position fluoroscopically, attention is directed to the femur.

A retractor hook is placed beneath the femur in the recess of the vastus lateralis ridge. LEFT hip – Counter clockwise, RIGHT hip - Clockwise. This hook is contoured to avoid soft tissue injury. The hook is raised just enough to keep in position. Attention to the inferior femoral neck to further release capsule. Place inferior neck Mueller. The operative extremity is externally rotated to 120 degrees, then extend and adduct (down and across) (NO TRACTION) allowing axial access to the proximal femur. Release the superior capsule. Place the Sharp Hohman posterior-superior neck. Up with the hook. Piriformis is now on tension. Place the superior Mueller. Use cautery to release the piriformis straight off the ledge parallel to the posterior margin of the femur. Releases typically include superior capsular release, inferior capsular release, and often piriformis release in the piriformis fossa. The posterior muscular structures remain intact. Femur should be ready for preparation, if not, repeat steps. Start the box osteotome, then drop hand (get lateral – but don’t go too lateral in troch). Tendency is to broach in to much anteversion. Feel the epicondylar axis to assess for anteversion. Place final broach. Down with the hook and out – up and across, IR to 0. Check position with Xray. Then place hook ER to 120 degrees, down and across, up with hook. Replace the Mueller. Calcar ream. Broach stays about 1 mm below where you calcar ream to. Place the real stem. Place trial head Hook down, leg up and across. IR to 80 degrees, gross traction, 2 turns fine traction, IR to 0 degrees, release traction. Check position. Reverse to dislocate. The surgical implantation of the femoral implant trial is followed by a trial reduction. After appropriate sizing, the final femoral implant is placed. Trial head sizes are performed. After placement of the final arthroplasty head, closure is quite simple with reapproximation of the anterior capsule and interrupted Vicryl suture closure of the tensor fascia. Subcutaneous closure and skin closure are per routine.

Pearls and Pitfalls

Tips and problems to avoid

Postoperative Care

• WBAT
• No Dislocation Precautions
• Walker at d/c

Outcome

Most recently, Hozack has reported a prospective randomized study that found direct anterior approach has a significant improvement in the SF-36 and WOMAC scores at 6 weeks, 6 months, and even at one year when compared with anterolateral approach.

But is it safe? Is the complication rate higher?  Dr. Masonis from Orthocarolina, where I did my fellowship, reported on his first 300 cases.  One dislocation in 300, which aligns with Joel Matta’s published rate of 0.6%. Component implantation was reliable, and there were 3 calcar cracks. Three patients with BMIs greater than 40 had superficial I&Ds.   Revisions included one at 4 months for deep infection, one fibrous stem, one squeaker, and one for ill defined thigh pain with well fixed components.

These favorable results are tempered by Woolson’s paper of 247 THAs with a 9% complication rate, high blood loss, and long operative times.  On deeper inspection we do note that these surgeons were doing the procedure relatively infrequently (2 a month on average) with only one day of observational formalized training.  

Complications

Approach Related

• LCFN
• Circumflex Vessels
• Muscle Damage
• Femoral Neurovascular Bundle

Access Related Complications

• Reaming and Cup Positioning
• Femoral Perforation
• Stem Positioning

Postoperative Complications

• Wound Hematoma
• Dislocation
  • Siguier 0.96% in 1037
  • Matta 0.61% in 437
  • Kennon 1.3% in 2132
  • Sariali 1.5% in 1374

References

Include limited reference list