Minimally Invasive Total Hip Arthroplasty: Techniques and Results

RECONSTRUCTION 2023, Jan, 08 | 12:00 am

Minimally Invasive Total Hip Arthroplasty: Techniques and Results

Introduction

P ITFALLS

Some contraindications that can assist with patient selection generally include complicated primary THA, revision surgery, severe hip dysplasia (Crowe grade III or IV), body mass index considerably higher than 30 kg/ m2, very muscular patients, osteoporotic bone, and very stiff joints (Vail, 2005).

Total hip arthroplasty (THA) has developed into one of the most frequently performed and successful procedures in orthopedic surgery. Although there have been numerous variations in implant design and biomaterials over the years, surgical approaches to the hip have remained relatively unchanged. Recently, with the development of minimally invasive techniques within other areas of surgery, orthopedic surgeons have revealed increased interest in less invasive approaches for THA, which balances the desire for optimum visualization with less invasive surgery.
Two categories of minimally invasive THA have materialized: several modified single-incision approaches and a two-incision approach.

Controversies
- The definition of minimally invasive is controversial, but the “mini-incision” used for these techniques is typically a length of 10 cm or less, with some using up to 12 cm (Vail, 2005). As with any surgery, the incision length should not be standardized, as several factors can alter the exposure needed to correctly perform the THA. The length of the incision(s) depends on the skill of the surgeon, patient weight, local subcutaneous tissue, muscle mass, and the individual joint and anatomy.
- THA utilizing minimally invasive surgical technique is a topic that has created much debate and attention from surgeons and patients alike. It is important to realize that longterm outcomes are still unknown, and the short-term outcomes have failed to reveal consistent results regarding its intended benefits.
- The single-incision techniques are alterations to the standard posterior, anterolateral, and direct anterior approaches. These can be developed on a graduated basis with progressive reduction of incision length at a rate comfortable for the surgeon. Similarly, the mini single-incision approaches allow extension into a standard incision if needed to gain additional exposure.
- The two-incision technique represents a drastically different approach for THA and utilizes separate incisions to insert the acetabular and femoral components.
One key objective of any THA is to have well-positioned components without compromising soft tissues or neurovascular structures, allowing the patient to have a quick and functional recovery. To achieve this, it is crucial to gain sufficient access to both the acetabulum and proximal femur.

Indications
When considering minimally invasive THA, proper patient selection is important to avoid difficulties with exposure that ultimately may compromise the safety of the procedure.
Another important consideration is surgeon inexperience and/or lack of training. Each case needs to be looked at individually, with both the surgeon and the patient examining the risks and benefits to determine if minimally invasive techniques are worth pursuing.

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SINGLE-INCISION POSTERIOR APPROACH

Positioning

The patient is positioned in the lateral decubitus position.

P EARLS
- Regardless of how this flap is created, it may be beneﬁcial to tag it with sutures to help with anatomic repair at the end of the procedure.
Portals/Exposures
The incision is a short, oblique incision centered over the acetabulum, or utilizing the middle third of what would be the standard incision for the posterior approach over the posterior greater trochanter

(Fig. 1). The oblique nature of the incision can aid in acetabular reaming, as the incision is in that same direction.
The dissection proceeds to the thin investing fascia of the gluteus maximus muscle and the tensor fascia lata.
The gluteus maximus is split in line with its fibers, while trying to avoid cutting the iliotibial band.

Trochanter (outline)

Incision mini-posterior approach

FIGURE 1

Minimally Invasive THA
A Charnley retractor can be placed deep to the gluteus maximus to assist with exposure and identification of the trochanteric bursa, the posterior border of the gluteus medius (forceps in Fig. 2), the piriformis, and the short external rotators.

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A

Gluteus medius

Trochanter

Femur

Forceps

Piriformis and short external rotators

B

FIGURE 2

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- At this point, it is also crucial to palpate and protect the sciatic nerve as it leaves the greater sciatic notch and continues distally over the ischial tuberosity, although it is not necessary to expose the nerve.
- With a retractor pulling the gluteus medius anteriorly, the short external rotators, consisting of the piriformis and the conjoined tendon (superior gemellus, obturator internus, inferior gemellus, and quadratus femoris), should be incised from the femur and reflected posteriorly. A capsulotomy can now be performed exposing the femoral head and allowing posterior dislocation of the hip. Alternatively, the capsule and external rotators can be incised and reflected as a single layer.
  
  Instrumentation/ Implantation
  - Angled reamers can be utilized to help avoid impingement on soft tissues.
  Procedure
  
  Step 1
- The femoral neck is cut with an oscillating saw, the femoral head removed, and attention turned to preparation of the acetabulum.
- Ideally, an acetabular retractor with a sharp tip and a light to illuminate the acetabulum should be placed on the anterior rim.
- The inferior capsule may need to be divided, and the final step to gain maximum acetabular exposure is flexion and adduction of the femur.
- Before reaming, the labrum should be excised and any visible osteophytes removed. The acetabulum is then sequentially reamed under direct vision, making certain the femur does not force the reamer into the posterior column.
- Once reaming of the acetabulum is complete, the implant is inserted.
  
  Minimally Invasive THA
  
  Step 2
The femur is prepared under direct vision while protecting the posterior edge of the abductor muscles (A in Fig. 3) with a retractor. Positioning the femur in flexion in line with the skin incision and pushing the proximal femur up through the wound can aid greatly with proximal femur exposure (B in Fig. 3B).

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A

Trochanter

Femur

Abductor

muscles

Cut femoral neck

B

FIGURE 3

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Minimally Invasive THA
- With the final broach and a trial head and neck in place, a trial reduction is performed to assess limb length, stability, and signs of impingement. An intraoperative radiograph may be used to ensure proper implant position.
- The femoral components are inserted, and the wound is copiously irrigated before reattachment of the short external rotators and capsule to the femur.
- The wound is closed in layers as usual.
  
  Complications
  - Other potential disadvantages and complications documented in the literature include higher rates of wound and soft tissue complications as well as muscle damage and component problems (Mardones et al., 2005; Meneghini et al., 2006; Teet et al., 2006; Woolson et al. 2004).
  Postoperative Care and Expected Outcomes
- Results of mini-posterior THA are preliminary and certainly conflicting. Some series show improvement in function and decreased blood requirements (Chimento et al., 2005; Wenz et al., 2002), while others show no difference (Ogonda et al., 2005).
- Interestingly, no functional differences were found between patients who had both a mini-posterior THA and a two-incision THA on the contralateral hip (Pagnano et al., 2006).
  
  SINGLE-INCISION ANTEROLATERAL APPROACH
  
  Positioning
- The patient is positioned in either the lateral decubitus or supine position.
  
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  Minimally Invasive THA
  
  Portals/Exposures
The skin incision is centered on a point 2 cm distal to the tip of the greater trochanter, with the proximal half angled 30° posterior to the long axis of the femur and the distal half angled 30° anterior (Fig. 4). This incision should be centered to allow for extension in either direction for better acetabular or femoral exposure if needed.
Initial dissection is taken down to the fascia. The subcutaneous tissue is cleared from the fascia, creating a “mobile window” that can be shifted to facilitate ideal exposure of the acetabulum and proximal femur.
At this point, the anterior third of the gluteus medius, the entire gluteus minimus, and the anterior half of the capsule are elevated in one layer.
The remaining hip capsule is incised superiorly and inferiorly, which allows excellent exposure while maintaining the hip capsule integrity for increased stability postoperatively. The hip is dislocated, and the femoral neck cut is made using an oscillating saw.

Trochanter (outline)

Incision mini-anterolateral approach

FIGURE 4

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Minimally Invasive THA

Procedure

Step 1
- Four acetabular retractors can now be strategically placed around the anterior, superior, inferior, and posterior aspects of the acetabulum.
- The labrum should be excised to help visualize the periphery of the acetabulum, and osteophytes removed.
- Sequential reaming should be performed, ensuring proper placement of the retractors to protect the skin and soft tissue.
- The cementless implant is inserted under direct visualization.
  
  Step 2
- To assist with preparation of the femur, one retractor is placed posterior to the femur, and one is placed lateral to it. These retractors can again assist with protecting the skin and soft tissues during reaming and broaching.
- The femoral canal is prepared as usual, and with the final broach and a trial head and neck in place, a trial reduction is performed to assess limb length, stability, and signs of impingement.
- The final components are inserted, and the wound is closed in layers, focusing on repair of the gluteus medius tendon back to the femur.
  
  P EARLS
  - This approach obviates the need for special instrumentation,
    
    and many surgeons ﬁnd that acetabular component positioning is easier with this approach.
    
    P ITFALLS
  - The orthopedic literature is lacking with regard to results of this approach when compared to the mini-posterior approach.
  Postoperative Care and Expected Outcomes
- The proposed benefits of the mini-anterolateral THA are similar to those of other minimally invasive techniques, and include decreased pain, blood loss, rehabilitation time, operative time, length of hospital stay, and overall complications.
- However, just as with the other minimally invasive THA techniques, the results of the mini-anterolateral THA are short term, controversial, and inconsistent (Asayama et al., 2006; Ciminiello et al., 2006; O’Brien and Rorabeck, 2005).
- The general consensus has been that mini-anterolateral THA can be achieved with satisfactory results, but the reduced wound size does not seem to benefit the patient in any way when compared with a standard incision (Asayama et al., 2006; Ciminiello et al., 2006).
  
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  Minimally Invasive THA
  
  SINGLE-INCISION DIRECT ANTERIOR APPROACH
  
  Positioning
The authors who originally developed the technique describe orienting the operating room table at right angles to the walls to provide accurate references for anatomic orientation (Kennon et al., 2003).
The patient is positioned in the supine position, and the uninvolved lower limb should be abducted to allow for intraoperative adduction of the operative extremity.
A sandbag, bump, or bolster should be placed under the ipsilateral buttock to tilt the pelvis forward, placing the lower limb in slight extension.

P EARLS
- Traction on the limb may facilitate head removal.
Portals/Exposures
The incision is typically made along the medial border of the tensor fascia lata, and is parallel to a line that connects the anterior superior iliac spine (outlined proximal to the incision in Fig. 5) and the tip of the greater trochanter. The approximate location of the femoral neurovascular bundle should be kept in mind (outlined medial to the incision in Fig. 5). The remainder of the exposure should be done through a modified Smith-Peterson approach.

ASIS (outlined)

Femoral neurovascular bundle (outlined)

Incision direct anterior approach

FIGURE 5

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Minimally Invasive THA
- The initial dissection is through the internervous muscular plane between the sartorius and the tensor fascia lata (Fig. 6). The fascia is incised just lateral to that location to avoid injuring the lateral femoral cutaneous nerve.
  
  A
  
  Forceps
  
  Sartorius
  
  Tensor fascia lata
  
  B
  
  ASIS (outlined)
  
  Femoral neurovascular bundle (outlined)
  
  FIGURE 6
  
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  Minimally Invasive THA
Blunt dissection is used to establish the deep plane of dissection between the gluteus medius laterally and the rectus femoris medially, allowing the interval between the rectus and the hip capsule to be developed. The origin of the rectus femoris is not routinely detached.
A narrow Cobra retractor is placed superiorly to better expose the hip capsule. A second Cobra retractor is placed over the superolateral joint capsule, and a third is placed over the inferomedial joint capsule. The latter two retractors should be perpendicular to the femoral neck.
The anterior capsule is now excised, exposing the femoral neck, which needs to be osteotomized in situ to dislocate the hip. The neck cut is made and the head is removed using a corkscrew or threaded Steinmann pins. If it is difficult to deliver the entire head through the wound, an additional cut may need to be made at the head-neck junction.

Procedure

Step 1
Three narrow Cobra retractors placed around the rim of the acetabulum are used to gain complete visualization for acetabular preparation. Any remaining labrum and osteophytes should be excised.
At this point, the sandbag, bump, or bolster can be either removed or deflated from underneath the buttock so that reaming is done in the anatomic supine position.
The acetabulum is sequentially reamed, and the acetabular component is impacted into place.

Step 2
The femur is then exposed for preparation (A in Fig. 7; B indicates the abductor muscles). A bone hook can be placed posterior to the lesser trochanter to facilitate exposure. Elevation of the femur can be augmented by placing a rigid retractor posterior to the greater trochanter. If exposure still remains difficult, intentional release of the posterior capsule and external rotators can be performed.
Once the femur is appropriately exposed, reaming and broaching are performed as usual.
If the surgeon has any doubts regarding implant position, the supine positioning allows easy use of intraoperative fluoroscopy if needed. Trial reductions are performed to assess limb length, stability, and

Minimally Invasive THA

A

125

Femur (cut femoral neck)

Trochanter

B

FIGURE 7

Abductor muscles

signs of impingement. The definitive components are inserted.
- The wound is copiously irrigated, the fascia between the sartorius and the tensor fascia lata is repaired while avoiding entrapment of the lateral femoral cutaneous nerve, and the remainder of the wound is closed in layers as usual.
  
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  Minimally Invasive THA
  
  Postoperative Care and Expected Outcomes
  
  Complications
  - There are other potential complications that may argue against some of the original proposed advantages (Meneghini et al., 2006).
Advocates of the direct anterior minimally invasive THA describe many advantages to this approach (Kennon et al., 2003). These include absence of releasing or distorting the abductor mechanism, excellent anatomic visualization of the acetabulum and femur, reduced soft tissue dissection, reduced blood loss, and reduced operative time (Rachbauer, 2005).

TWO-INCISION APPROACH

Positioning
The patient is placed in the supine position on a radiolucent table to allow for intraoperative fluoroscopy.
Just as with the direct anterior approach, a sandbag, bump, or bolster should be placed under the ipsilateral buttock to tilt the pelvis forward and place the lower limb in extension.

Portals/Exposures

Acetabulum
The anterior incision and approach for exposure of the acetabulum is virtually identical to that in the direct anterior approach described above. The incision can be confirmed with fluoroscopy to be a line between the posterior acetabulum and the intertrochanteric line, in line with the femoral neck.
The remainder of the acetabular exposure should be done through a modified Smith-Peterson approach (see above).

Femur
The sandbag, bump, or bolster is reinserted or reinflated.
The location of the posterior incision is critical, and it should allow straight access to the femoral canal. There are two commonly used methods to ensure proper position of the posterior incision.
- First, the axes of the femoral shaft in the anteroposterior and lateral planes are palpated and drawn with the femur in adduction and external rotation. The point at which these two lines intersect proximally is the location of the posterior incision.
  
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  Minimally Invasive THA
- An alternative method utilizes a curved instrument (awl) passed through the anterior incision and through the superior capsular opening. This tents the skin posteriorly in line with the femoral shaft, where a small incision is made. After the incision is made, the subcutaneous tissues are spread using long, curved scissors, and a soft tissue passage to the hip joint is blindly developed by aiming the scissors toward the surgeon’s opposite finger, which is in the anterior incision within the superior hip capsule. Spreading the tissues using this technique creates a pathway to the femoral canal posterior to the abductors.
Procedure

Step 1
- When it comes time for preparation of the acetabulum, fluoroscopy can be used to verify alignment and appropriate medialization of the reamers.
- The cementless acetabular component is impacted into place using an offset inserter, again using fluoroscopy to ensure proper abduction and anteversion.
  
  Step 2
- With the two-incision technique, femoral instrumentation and implant insertion are done blindly, utilizing fluoroscopy and palpation through the anterior incision. It is important to keep the limb adducted with slight flexion to maintain the proper relationship between the soft tissue passage and the femoral canal.
- After the opening is lateralized into the canal, reaming and broaching are performed under fluoroscopic guidance. Broach stability can be assessed with visual confirmation through the anterior incision. If the broach should get caught up on the hip capsule, the capsule can be released as necessary.
- The femoral component is inserted under fluoroscopic guidance, and alignment and depth are confirmed visually through the anterior incision.
  
  Step 3
- The neck of the prosthesis is delivered into the anterior incision, which is achieved with an assistant applying traction and the surgeon manipulating the neck using a large bone hook with gentle flexion, abduction, and external rotation of the femur. Trial

FIGURE 8

reductions can now be performed, and limb length, stability, and signs of impingement are assessed as usual.

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Minimally Invasive THA

Once the appropriate neck length is determined, the trial head is removed, and the real component is impacted in place. The hip is reduced, and wounds are copiously irrigated.

Step 4
Anteriorly, repair of the anterior capsule should be attempted to assist with stability. The fascia between the sartorius and the tensor fascia lata is repaired, while avoiding entrapment of the lateral femoral cutaneous nerve. The remainder of the wound closed in layers as usual.

Complications
- Multiple authors have reported increased rates of complications when using this approach, including increased rates of reoperation, unpredictable implant position despite the use of intraoperative fluoroscopy, postoperative femur fracture, femoral nerve palsy, and injury to the lateral femoral cutaneous nerve causing lateral thigh numbness (Bal et al., 2006; Pagnano et al., 2005).
Posteriorly, repair of the fascia over the gluteus maximus is performed, followed by closure of the subcutaneous tissue and skin as usual.

Postoperative Care and Expected Outcomes
Outcomes of minimally invasive THA done through two incisions are varied, but satisfactory outcomes certainly can be realized (Berger and Duwelius, 2004). It has been proven difficult to reproduce the more rapid rehabilitation shown in previous reports.

P EARLS
- Elderly and obese females are at greatest risk of developing a complication with this approach.
The technical difficulty of this approach is reflected in longer operative times and a greater variability in operative times when compared with traditional THA (Pagnano et al., 2005). In addition, reoperation rates as high as 10% have been reported (Bal et al., 2006).
The potential benefit of less soft tissue dissection certainly may not be the case, as significant damage has been shown to occur to the gluteus medius and gluteus minimus muscles (Mardones et al., 2005). Figure 8 demonstrates gluteus medius muscle injury

(A) in a cadaveric specimen that occurred with the two-incision approach (B indicates the greater trochanter).
Most authors agree that the high complication rate is at least partly due to the so-called learning-curve effect (Pagnano et al., 2005). Slight modifications to the procedure may assist in bringing about more favorable outcomes. For example, one author has eliminated intraoperative fluoroscopy, stating that it may mislead the surgeon and provide a false sense of security (Bal et al., 2006). It is emphasized that implant position is dependent on adequate

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Minimally Invasive THA

visualization, anatomic landmarks, and instrument guides. The technique undoubtedly is technically challenging, and proper training, including cadaveric training, is necessary to minimize complications and ensure success (Berger and Duwelius, 2004).

Evidence

Asayama I, Kinsey TL, Mahoney OM. Two-year experience using a limited-incision direct lateral approach in total hip arthroplasty. J Arthroplasty. 2006;21:1083–91.

Retrospective early experience documenting satisfactory results with limited incision direct lateral approach.

Bal BS, Haltom D, Aleto T, Barrett M. Early complications of primary total hip replacement performed with a two-incision minimally invasive technique: surgical technique. J Bone Joint Surg [Am]. 2006;88(Suppl 1 Pt 2):221–33.

Retrospective case series review documenting substantial early complication rate with two-incision THA.

Berger RA, Duwelius PJ. The two-incision minimally invasive total hip arthroplasty: technique and results. Orthop Clin North Am. 2004;35:163–72.

This study showed rapid rehabilitation, quick return to activities of daily living, and a low prevalence of complications following minimally invasive THA done through two incisions.

Chimento GF, Pavone V, Sharrock N, Kahn B, Cahill J, Sculco TP. Minimally invasive total hip arthroplasty: a prospective randomized study. J Arthroplasty. 2005;20: 139–44.

A prospective, randomized study showed a mini-posterior THA group to have less intraoperative and total blood loss and less of a limp at 6 weeks when compared with standard THA, although there was no functional difference at 1 and 2 years’ follow-up.

Ciminiello M, Parvizi J, Sharkey PF, Eslampour A, Rothman RH. Total hip arthroplasty: is small incision better? J Arthroplasty. 2006;21:484–8.

Kennon RE, Keggi JM, Wetmore RS, Zatorski LE, Huo MH, Keggi KJ. Total hip arthroplasty through a minimally invasive anterior surgical approach. J Bone Joint Surg [Am]. 2003;85(Suppl 4):39–48.

Mardones R, Pagnano MW, Nemanich JP, Trousdale RT. The Frank Stinchfield Award: Muscle damage after total hip arthroplasty done with the two-incision and mini-posterior techniques. Clin Orthop Relat Res. 2005;(441):63–7.

Vail TP. Mini-incision THA: posterior approach. In Lieberman JR, Berry DJ (eds). Advanced Reconstruction Hip. Rosemont, IL: American Academy of Orthopaedic Surgeons, 2005:17–40.

In a cadaveric study, there was measurable damage to the abductors and gluteus minimus when a mini-posterior approach was performed, although the damage to the abductor mechanism was less when compared to the two-incision approach, in which mean abductor and gluteus minimus muscle damage exceeded 15% and 17%, respectively.

Meneghini RM, Pagnano MW, Trousdale RT, Hozack WJ. Muscle damage during MIS total hip arthroplasty: Smith-Petersen versus posterior approach. Clin Orthop Relat Res. 2006;(453):293–8.

In a cadaveric study, a mean of 8% of the gluteus minimus muscles and 31.2% of the tensor fasciae latae were damaged using the direct anterior approach, and in 50% of the cases the piriformis and/or conjoined tendon avulsed with mobilization of the femur. Muscle damage of some degree was found in all specimens. This study also showed that, in addition to the intentional detachment of the piriformis and conjoined tendon, there was also measurable damage to the abductors and gluteus minimus in each specimen in which a mini-posterior approach was performed.

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O’Brien DA, Rorabeck CH. The mini-incision direct lateral approach in primary total hip arthroplasty. Clin Orthop Relat Res. 2005;(441):99–103.

This series retrospectively compared mini-anterolateral THA to standard anterolateral THA and showed signiﬁcantly decreased operative time as well as length of hospital stay with the mini approach. The series showed no difference with regard to complications, need for blood transfusion, or component malposition.

Ogonda L, Wilson R, Archbold P, Lawlor M, Humphreys P, O’Brien S, Beverland D. A minimal-incision technique in total hip arthroplasty does not improve early postoperative outcomes: a prospective, randomized, controlled trial. J Bone Joint Surg [Am]. 2005;87:701–10.

A prospective, randomized, controlled trial showed no difference with respect to postoperative hematocrit, blood transfusion requirements, pain scores, early walking ability, length of hospital stay, femoral component cement mantle, functional outcome scores at 6 weeks, or component positioning.

Pagnano MW, Leone J, Lewallen DG, Hanssen AD. Two-incision THA had modest outcomes and some substantial complications. Clin Orthop Relat Res.

2005;(441):86–90.

In this series, most of the technical difﬁculties occurred on the femoral side, and placement of the acetabular component through the direct anterior approach was straightforward and presented few challenges. Fourteen percent of patients had a complication, with 5% requiring reoperation.

Pagnano MW, Trousdale RT, Meneghini RM, Hanssen AD. Patients preferred a mini-posterior THA to a contralateral two-incision THA. Clin Orthop Relat Res.

2006;(453):156–9.

This study reported on 26 patients who had both a mini-posterior THA and a two-incision THA on the contralateral hip. There were no differences with respect to ambulation, return to driving, stair climbing, return to work, or walking ½ mile. Sixteen of the 26 patients preferred their mini-posterior THA over their two-incision THA, and two had no preference.

Rachbauer F. [Minimally invasive total hip arthroplasty via direct anterior approach.] Orthopade. 2005;34:1103–4, 1106–8, 1110.

In a prospective study, it was shown that minimally invasive THA via the direct anterior approach allowed correct positioning of all components, little blood loss or postoperative pain, decreased hospital stays, and accelerated rehabilitation. Of the 100 patients in the series, there were six permanent lesions of the lateral femoral cutaneous nerve.

Teet JS, Skinner HB, Khoury L. The effect of the “mini” incision in total hip arthroplasty on component position. J Arthroplasty. 2006;21:503–7.

A series using the mini-posterior THA showed worrisome results regarding cemented femoral components, with a slight propensity toward varus malpositioning that could complicate long-term outcomes.

Wenz JF, Gurkan I, Jibodh SR. Mini-incision total hip arthroplasty: a comparative assessment of perioperative outcomes. Orthopedics. 2002;25:1031–43.

An early series showed that patients with mini-posterior THA had signiﬁcantly earlier ambulation with less transfer assistance needed, as well as less blood transfusion requirements.

Woolson ST, Mow CS, Syquia JF, Lannin JV, Schurman DJ. Comparison of primary total hip replacements performed with a standard incision or a mini-incision. J Bone Joint Surg [Am]. 2004;86:1353–8.

This series showed no difference with respect to variables such as blood loss and surgical time, but the mini-incision group was found to have a signiﬁcantly higher risk of wound complications, higher percentage of acetabular component malposition, and poor “ﬁt and ﬁll” of cementless femoral components.

Minimally Invasive Total Hip Arthroplasty: Techniques and Results