Understanding Anterior Hip Replacement and its Benefits over Traditional Approaches

Hip replacement is one of the most successful procedures in modern medicine. Nearly 400,000 hip replacements are performed each year in the United States. The traditional successes of total hip replacement (THR) are based on a foundation of extensive clinical research and long-term patient outcomes. Conventional teaching and thought processes in THR are therefore inherently resistant to change and instead are focused more on improving upon these prior successes. Only in recent decades has the joint replacement surgeon community begun to embrace new techniques and thought processes to achieve faster recovery, better pain management, and improved patient outcomes. What was previously thought not possible has recently become nearly universal in modern joint replacement surgery. Patients now walk and can go home just hours after hip and knee replacement, pain is significantly less after surgery, and patient recovery is much faster. These changes have not come easily, but the benefits of transitioning to these new procedures will fuel future enthusiasm to challenge prior standards and to adopt novel techniques.   

Over the years, there has been a long-standing debate over which surgical approach is most effective for total hip replacement. Various techniques have been used, each with their own set of advantages and disadvantages. In prior decades, posterior and lateral approaches have been most commonly used based on national registry reporting, domestic and abroad. The posterior approach enters the hip near the buttock area and has the benefit of not interfering with the abductor mechanism (side of the hip muscle group), is familiar to surgeons, is relatively straightforward as a technique, and subsequently, it is traditionally the most common approach taught in teaching institutions.  In a medical field typically based on convention, this approach has subsequently had the broadest adoption with respect to both time and scope.

Risks are quite rare, however, injury to the sciatic nerve during dissection or retractor placement with the posterior approach can occur. The inferior gluteal artery may be damaged as it leaves the pelvis beneath the piriformis to supply the gluteus maximus muscle. Most significantly, the principal disadvantage of this approach is a dislocation rate of about 3%, as per a meta-analysis of >13,000 THAs.[i] Regardless of capsule repair or external rotator repair or preservation, the modified versions of the posterior approach all remain limited by the persistent risk of early and late hip instability.[ii]

The direct lateral approach enters the hip at the side of the joint and asserts better hip stability by avoiding violation of the external rotators and posterior capsule.  However, the risks associated with the lateral approaches include injury to the superior gluteal nerve, postoperative limp, and heterotopic ossification. Other variations of less invasive surgical techniques such as minimally invasive posterior, superior posterior approach, modified anterolateral approaches, two-incision, and others have been adopted and popularized by some small groups of users in recent years. However, none of these approaches have gained widespread popularity, nor sustained increased growth, to surpass the usage of the posterior or lateral approaches.

In recent years, there has been increasing interest in the benefits of the direct anterior hip approach. This surgical technique exposes the hip from the front and goes between natural muscle planes, to avoid cutting muscle or requiring extended recovery times. Developed from techniques also used to treat hip and pelvic fractures, this approach has been shown to have a faster recovery and fewer complications and limitations than with traditional approaches. Literature has supported that the anterior approach is associated with a reduced risk of dislocation, faster recovery, less pain, and fewer surgical complications.[iii] It has proven to have rapid adoption and continued growth because of its potential advantages over traditional approaches. In the annual hip and knee specialty meeting poll in 2018, the anterior approach was the preferred technique for 40% of attendees, rapidly increasing from 12% in 2009.[iv] In a subsequent survey of nearly 1000 hip and knee surgeon specialists, anterior approach surpassed other approaches and was performed by the majority of surgeons at 56.2%.[v] Recent history has shown that the early reported clinical benefits and the opportunity to address the limitations of traditional approaches by using the anterior approach have driven this rapid increase in popularity.

While other less invasive surgical approaches have paradoxically shown increased muscle damage compared to traditional approaches, there remains enthusiasm for performing hip replacement with the least invasion possible. Some studies have shown that an alternative approach like the direct anterior technique may have muscle-sparing advantages. A retrospective magnetic resonance imaging (MRI) study at 1-year postoperatively revealed significantly less frequent detachment of the abductor insertion, partial tears or tendonitis of gluteus medius and minimus, lower presence of peritrochanteric bursal fluid, or fatty atrophy of the gluteus medius and minimus with the anterior approach.[vi] Furthermore, inflammation and muscle damage markers were lower in anterior versus posterior approach groups, suggesting significantly less muscle damage with the anterior approach.[vii] When comparing trochanteric and groin pain, the anterior approach has a decreased incidence compared to the posterolateral approach.[viii]

Another deviation from conventional techniques is the movement towards using fluoroscopy or real-time guidance during hip component placement. Unlike spine or orthopedic trauma surgery, hip replacement has traditionally been taught to be performed without the use of image guidance. And yet, it makes sense that using imaging during hip surgery would potentially address improper component positioning, which is a leading cause of hip replacement failure. In contrast to other hip approaches where patients are positioned on their side, the anterior approach is performed with the patient lying on their back, which allows ease of using x-ray during the surgical procedure. In fact, studies have shown the benefits of intraoperative fluoroscopy during anterior hip replacement to confirm implant fit and position, leg length, and offset. This higher degree of accuracy of component position is evident with the anterior approach compared to the other traditional experienced techniques.[ix] Furthermore, performing anterior hip replacement in this position allows the advantage of accurately measuring leg lengths either manually or with an x-ray.

The anterior approach provides significant benefits for patients in the early postoperative period based on pain scores and functional recovery compared to the posterior approach and carried through 6 weeks after surgery.[x] Other hip scores show continued benefit favoring the anterior approach to 3 months. In regards to complications, a recent meta-analysis of only randomized controlled studies comparing direct anterior to posterior approach found no difference in complications.[xi] When comparing the anterior approach to posterior approach surgeries by high-volume surgeons, the anterior approach still shows a shorter length of stay, shorter procedure time, lower transfusion rate, increased discharge to home, lower minor systemic complication rates, and lower revision rates.[xii] The anterior approach may be associated with reduced risk of dislocation, faster recovery, reduced pain, and fewer complications.  

Improvements in instrumentation, surgical tables, and retractor devices have possibly made the approach more accessible to more surgeons.[xiii] In 2013, it is estimated that the anterior approach accounted for about 10% of all surgical procedures worldwide.[xiv] Recent surveys have revealed that over 50% of US surgeons are performing the technique. With more experience, the surgeon can relate to the growing body of literature reporting the advantages of anterior approach over traditional techniques. Growing mid-term outcomes show that the revision rate is significantly less for anterior versus posterior hip approaches. An analysis of the Norwegian Arthroplasty Register found the posterior approach was associated with more than twice the risks of revision for dislocation than anterior and other approaches.[xv]

Anterior hip replacement has many potential benefits in the recovery of total hip replacement. Patients are recovering faster, with fewer restrictions, and often are able to go home the same day as surgery. Like any surgical procedure, outcomes are generally better when performed by high-volume surgeons, at high-volume joint programs.  Patient education is also important to optimize patient outcomes, and discussions with the surgeon will determine which procedure is best for them. Total hip replacement outcomes and recovery continue to improve with modern techniques, all for the benefit of the patient experience.

[i]Masonis JL, Bourne RB. Surgical approach, abductor function, and total hip arthroplasty dislocation. CORR 2002;405:46-53.

[ii]von Knoch M, Berry DJ, Harmsen WS, Morrey BF. Late dislocation after total hip arthroplasty. J Bone Joint Surg Am2002;84-A:1949–1953

[iii]Barrett WP, Turner SE, Leopold JP. Prospective randomized study of direct anterior versus posterolateral approach for total hip arthroplasty. J Arthroplasty 2013;28:1634-8.

[iv]Abdel M, Berry DJ. Current Practice Trends in Primary Hip and Knee Arthroplasties Among Members of the American Association of Hip and Knee Surgeons: A Long-Term Update, 2018 AAHKS Annual Meeting Symposium| Volume 34, ISSUE 7, SUPPLEMENT , S24-S27, July 01, 2010

[v]Patel NN, Shah JA, Erens GA. Current Trends in Clinical Practice for the Direct Anterior Approach Total Hip Arthroplasty, Volume 34, ISSUE 9, P1987-1993.e3, September 01, 2019

[vi]Bremer AK, Kalberer F, Pfirrmann CW, Dora C. Soft-tissue changes in hip abductor muscles and tendons after total hip replacement: comparison between the direct anterior and the transgluteal approaches. JBJS Br 2011;93:886-9.

[vii]Bergin PF, Doppelt JD, Kephart CJ, Benke MT, Graeter JH, Holmes AS, Haleem-Smith H, Tuan RS, Unger AS. Comparison of minimally invasive direct anterior versus posterior total hip arthroplasty based on inflammation and muscle damage markers. JBJS 2011;93:1392-8.

[viii]Nam D, Nunley RM, Clohisy JC, Lombardi AV, Berend KR, Barrack RL. Does patient-reported perception of pain differ based on surgical approach in total hip arthroplasty? JBJS Br 2019;101:31-6.

[ix]Kobayashi H, Homma Y, Baba T, Ochi H, Matsumuto M, Yuasa T, Kaneko K. Surgeons changing the approach for total hip arthroplasty from posterior to direct anterior with fluoroscopy should consider potential excessive cup anteversion and flexion implantation of the stem in their early experience. Int Orthop 2016;40:1813-9.

[x]Zawadsky MW, Paulus MC, Murray PJ, Johansen MA. Early outcome comparison between the direct anterior approach and the mini-incision posterior approach for primary total hip arthroplasty: 150 consecutive cases. J Arthroplasty 2014;29:1256-60.

[xi]Wang, Z, Hou J, Hu C, Zhou Y, Gu X, Wang H, Feng W, Cheng Y, Sheng Z, Bao H. A systematic review and meta-analysis of direct anterior approach versus posterior approach in total hip arthroplasty. J Orthop Surg and Res 2018;13:229-40.

[xii]Ponzio DY, Poulsides LA, Salvatore A, Lee Y, Memtsoudis SG, Alexiades MM. In-hospital morbidity and postoperative revisions after direct anterior versus posterior total hip arthroplasty. J Arthroplasty. 2018;33:1421-5.

[xiii]Post ZD, Orozco F, Diaz-Ledezma C, Hozack WJ, Ong A. Direct anterior approach for total hip arthroplasty: indications, technique, and results. JAAOS 2014;22:595-603.

[xiv]Chechik O, Khashan M, Lador R, Salai M, Ama E. Surgical approach and prosthesis fixation in hip arthroplasty worldwide. Arch Orthop Trauma Surg 2013;133:1595-60.

[xv]Mjaaland KE, Svenningsen S, Fensta AM, Havelin, LI, Furnes O Norsletten L. Implant survival after minimally invasive anterior or anterolateral vs conventional posterior or direct lateral approach: an analysis of 21,860 total hip arthroplasties from the Norwegian Arthroplasty Register (2008 to 2013). JBJS 2017;99:840-7.