RECONSTRUCTION 2023, Jan, 08 | 12:00 am

Direct Lateral Exposure

Introduction

  • Adequate exposure is considered an essential part of a revision total hip replacement, equal in importance to other steps such as implant extraction dealing with bone defects, implant selection, and postoperative rehabilitation. Many exposures have been described for revision total hip replacement, including transtrochanteric, trochanteric slide, anterolateral, direct lateral, posterior, extended trochanteric, and Wagner approaches. Each surgical approach has its merits, and an experienced revision total hip replacement surgeon often switches from one surgical approach to another depending on the revision problem presented.

  • The extensile direct lateral surgical approach for revision total hip arthroplasty has been and remains the workhorse surgical exposure for most of the revision procedures at the University of Western Ontario. The main advantages of the direct lateral approach are wide exposure about the acetabulum and femur, easy conversion to a more extensile approach with or without an extended trochanteric osteotomy or control perforation technique, and a very low prevalence of postoperative dislocations. The main disadvantages of the direct lateral approach are the necessity to split the abductor muscles and the risk of damaging the terminal branch of the superior gluteal nerve.

  • Mallory and Head deserve credit for popularizing the use of the extensile direct lateral approach during revision total hip arthroplasties (Head et al., 1987). They also describe the control perforation technique, which enables retained cement to be safely removed from the top of the femur.

  • Use of an extended trochanteric osteotomy in association with the extensile direct lateral approach has been popularized by the University of Western Ontario. Like an extended trochanteric osteotomy described through the posterior approach, the lateral bony fragment, which includes the greater trochanter, incorporates approximately one third of the femoral tube and can be extended distally as far as the surgeon needs (usually 10–12 cm).

  • The extended trochanteric osteotomy performed through the direct lateral approach is usually hinged on the intermuscular septum. The advantage is that a healthy blood supply is maintained to the bony

     

    247

     

    Direct Lateral Exposure

     

    fragment, but the disadvantage is that the lateral bony fragment and greater trochanter cannot be reflected superiorly.

    • When an extended trochanteric osteotomy is used with the direct lateral approach, the surgeon is usually forced to depend on diaphyseal fixation, and most often an extensively coated cylindrical revision stem is used. At the end of the procedure, two to three cables are used to fix the trochanteric osteotomy fragment to the proximal femur. The surgeon may or may not elect to use one or two strut allografts at this time.

       

      P ITFALLS

      • Injury to the terminal branch of the superior gluteal nerve, particularly when a major acetabular revision procedure is being performed

       

      Indications

    • Extensile exposure for revision total hip replacement in patients in whom postoperative dislocation is a risk factor

      Examination/Imaging

      Controversies

      • Risk of injury to the terminal branch of the superior gluteal nerve

      • Increased risk of postoperative limp and the need for walking aids

       

    • Radiographs should include an anteroposterior view of the pelvis and lateral view of the affected hip, and anteroposterior and lateral views of the affected

      femur.

       

    • Judet views are helpful in determining the extent of acetabular osteolysis and whether a pelvic dissociation is present.

    • Computed tomography scans are helpful in assessing the extent of acetabular osteolysis and remaining bone stock.

      Treatment Options

      • Anterolateral (Watson-Jones) surgical approach (difficult)

      • Posterior surgical approach (associated with high dislocation rates)

      • Transtrochanteric surgical approach (risk of trochanteric nonunion/discomfort)

      • Extended trochanteric osteotomy through posterior or direct lateral approaches (extensile)

      • Extensile direct lateral surgical approach with or without controlled anterior femoral perforations or extended trochanteric osteotomy (extensile)

       

    • Hip aspiration and the use of a cell count and aerobic and anaerobic cultures are helpful, particularly if the sedimentation rate and C-reactive protein levels are elevated.

       

      248

       

      Direct Lateral Exposure

       

      Surgical Anatomy

  • The terminal branch of the superior gluteal nerve courses from posterior to anterior in the interval between the gluteus medius and minimus muscles. The nerve is found 9 cm posteriorly and 5 cm anteriorly from the tip of the greater trochanter (Fig. 1).

  • In revision total hip replacement, a posterior longitudinal split in the muscle fibers of the gluteus medius muscle is recommended to avoid the terminal branch of the superior gluteal nerve (Fig. 2). The superior gluteal nerve can be protected by gently retracting the nerve superiorly within the fat layer that exists between the gluteus medius and minimus muscles.

  • The anterior portion of the extensor mechanism, including the conjoint tendon of the gluteus medius and gluteus minimus and hip capsule, is then reflected from the anterior aspect of the greater trochanter, maintaining a 5-mm cuff of soft tissue on the anterior aspect of the greater trochanter (Fig. 3). The continuity of the gluteus medius and vastus lateralis muscles is preserved.

  • The dissection is then continued distally and posteriorly through the vastus lateralis muscle, thereby avoiding denervating the vastus lateralis and bleeding associated with cutting perforating vessels, which might retract through the intermuscular septum.

     

     

     

    B

     

    E

     

     

    D

     

    C

     

     

    A

     

    Posterior Anterior

     

    FIGURE 1

     

     

    249

     

     

     

    Direct Lateral Exposure

     

    Gluteus medius

    muscle

     

    Femur

     

     

    Fascia lata

    Vastus lateralis muscle

     

    FIGURE 2

     

    Gluteus minimus

    muscle

    Capsule

    Gluteus medius

    muscle

    Greater trochanter

     

     

    FIGURE 3

     

     

     

     

    P EARLS

    • Rigid positioning of the patient in the lateral position is important to assure accurate acetabular component placement.

       

    • Since the ipsilateral limb will be placed in a sterile pouch on the anterior aspect of the patient, any obstructions to movement of the leg into this pouch should be avoided (Fig. 4).

       

      P ITFALLS

    • Insecure patient positioning allowing the body to fall anteriorly and placement of the acetabular component in retroversion

     

    Direct Lateral Exposure

     

    FIGURE 4

     

    250

     

    Positioning

  • The patient is positioned in the lateral position on a well-padded operating room table and secured with bolsters.

  • The contralateral limb is placed in a slightly flexed position with extra padding placed to protect the common peroneal nerve.

    Equipment

    • Padded operating room table

    • Sacral and symphysis bolsters

    • Optional anterior and posterior chest bolsters

     

  • Padding is placed on the thigh and lower leg, but it is important to keep the contralateral foot and knee palpable through the drapes such that leg-to-leg assessments can be made for final leg length restoration.

    Portals/Exposures

  • Preexisting hip incisions are usually incorporated into a longitudinal incision in line with the longitudinal axis of the femur and extending one hand breadth proximal to the tip of the greater trochanter and distally as far as is needed for the revision procedure.

  • The extensile direct lateral approach is applicable to over 90% of revision hip operations. With extensive acetabular reconstructions (i.e., allografts or use of reconstruction cages). Other surgical approaches (i.e., trochanteric slide or extended trochanteric osteotomy) might be considered to protect the terminal branch of the superior gluteal nerve.

     

     

     

    251

     

     

    P EARLS

    • The extensile direct lateral surgical approach in revision hip arthroplasties is very versatile. The surgeon may use the control perforation technique to safely remove retained cement from the top of the femur (Fig. 5).

       

    • The direct lateral surgical approach might also be transformed to an extended trochanteric osteotomy hinged posteriorly on the intermuscular septum if needed (Fig. 6).

       

      P ITFALLS

    • Care must be taken to protect the terminal branch of the superior gluteal nerve when utilizing the direct lateral approach.

     

    Instrumentation

    • The operative procedure is facilitated by the use of self-retaining and Charnley retractors (see Fig. 4).

     

    Direct Lateral Exposure

     

    FIGURE 5

     

     

     

    Controversies

    • The advantage of the direct lateral surgical approach for revision total hip arthroplasties is the postoperative stability afforded to these difficult procedures (0.5% dislocation rates). This must be balanced with the risk of damaging the superior gluteal nerve and subsequent development of limp and need for walking aids.

     

    FIGURE 6

     

    252

     

     

    P EARLS

    • It is advisable to start the split in the iliotibial band distally, then place a finger between the iliotibial band and greater trochanter to identify the interval between the tensor and gluteus maximus muscles.

       

      P ITFALLS

    • Failure to mobilize the anterior and posterior flaps of the iliotibial band will make the procedure more difficult.

     

    Direct Lateral Exposure

     

    Procedure

    Step 1

  • The incision is carried down through the subcutaneous tissue to the iliotibial band, which is then split longitudinally over the femur and carried proximally in the interval between the tensor and gluteus maximus muscles.

  • The iliotibial band is mobilized anteriorly and posteriorly, releasing scarring to underlying

    structures.

     

    Step 2

    Instrumentation/ Implantation

    • The mobilized iliotibial band can then be reflected using a Charnley retractor.

     

  • Many variances of the direct lateral approach have been described, but for revision total hip replacements, longitudinally splitting the gluteus medius muscle at the junction of the anterior two thirds and posterior one third as described by Hardinge (1982) is preferred to maximize the safe zone in terms of protecting the terminal branch of the superior gluteal nerve (see Fig. 2).

     

    P EARLS

    • The steps outlined are important to preserve the integrity of the terminal branch of the superior gluteal nerve.

       

    • Leaving a 5-mm cuff of soft tissue attached to the anterior aspect of the greater trochanter helps assure an excellent wound closure.

       

      P ITFALLS

    • Making the vertical split in the abductor muscles too anterior can hinder exposure of the proximal femur and result in excessive abductor muscle damage.

     

  • The incision is then carried along the anterior aspect of the greater trochanter, leaving a 5-mm cuff of the conjoint tendon for subsequent reattachment to the greater trochanter (see Fig. 3).

  • The incision is then carried distal to the greater trochanter and courses posteriorly to preserve the innervation of the vastus lateralis muscle for whatever distance the surgeon requires.

  • Once the exposure is outlined, retractors are used to open the vertical split in the gluteus medius muscle and a Cobb elevator used to gently tease fat and the terminal branch of the superior gluteal nerve vascular bundle superiorly off the tendon of the gluteus minimus.

  • The visualized gluteus minimus tendon is then split in line with its fibers in the direction of the original incision.

  • The conjoint tendinous insertion of the gluteus medius, gluteus minimus, and hip capsule are then reflected anteriorly off the anterior aspect of the greater trochanter, and this exposure is extended distally, elevating the vastus lateralis off the anterolateral femur (Fig. 7).

  • Scar and granuloma tissue are then excised, exposing the acetabular and femoral components.

  • The goal is to obtain circumferential exposure of the acetabular component and complete exposure of the proximal femur except where the abductor muscles attach to the greater trochanter.

     

    Instrumentation/ Implantation

    • Once the anterior flap, consisting of the gluteus medius, gluteus minimus, and hip capsule, is developed, it is helpful to readjust the Charnley retractor, placing a deep blade deep to the anterior abductor cuff of tissue.

     

     

    253

     

    Controversies

    • Revision total hip replacement requires wider exposure, placing the terminal branch of the superior gluteal nerve at risk. While this complication is largely avoidable, the surgeon might want to consider other options when extensive acetabular revision procedures are needed (i.e., use of allografts or use of a reconstruction cage).

     

    Direct Lateral Exposure

     

    FIGURE 7

     

    Step 3

    • When revising a cemented femoral component from the top, it is advisable to remove the femoral component, then use cement-removing instruments to break the cement away from the underlying bone.

       

      P EARLS

      • Removing cement from the top or using the control perforation technique is ideal if the surgeon wishes to use a cemented or impaction grafting technique for the revision of the femoral component.

         

      • Use of an extended trochanteric osteotomy is usually associated with the use of a distal fixation, cementless stem.

       

      • It is important to visualize the anterior cortex of the femur to help direct the use of the cement-removing instruments. If visualization becomes difficult, a controlled perforation technique is helpful. A high-speed burr can be used to make 5- to 10-mm circular perforations in the anterior cortex, allowing illumination of the femoral canal and direct visualization of the cement-bone

        interface. Often, two to three anterior perforations are necessary.

      • When this technique is used, the final femoral stem should be at least two femoral diameters distal to the last perforation to minimize the stress riser effect.

         

         

         

        P ITFALLS

        • When removing cement from the top, the risk of femoral perforation is increased.

           

        • Both the control perforation and extended trochanteric osteotomy techniques necessitate the use of implants that bypass iatrogenic bone defects. Usually these bone defects should be bypassed by at least two cortical diameters or approximately 5 cm.

         

         

        Instrumentation/ Implantation

        • Specially designed cement removal instruments.

         

        Direct Lateral Exposure

         

  • An alternate measure to improve access to the femoral canal is to develop an extended trochanteric osteotomy through the direct lateral approach.

    Controversies

    • Extended trochanteric osteotomy was first advocated from a posterior surgical approach. Using an extended trochanteric osteotomy from the direct lateral approach is novel. It is important to preserve the vascularity of the trochanteric fragment via attachment of the abductor muscles and the blood supply in the region of the intermuscular septum.

     

    • The technique involves making an osteotomy of the posterolateral third of the proximal femur 10 to 15 cm from the tip of the greater trochanter such that the intermuscular septum remains attached to the osteotomy fragment. It is helpful to use a high-speed burr to complete the transverse portion of the osteotomy distally.

    • Use of a ¼-inch osteotome to complete the posterior osteotomy is helpful. The osteotomy is then pried open with the help of a broad osteotome.

    • Wide exposure is obtained using this technique (Fig. 8).

     

    254

     

     

     

    FIGURE 8

     

    Step 4

  • Once the revision procedure has been completed and the surgeon is happy with the stability of the joint and restoration of leg length and offset, closure is begun.

  • I prefer to close the vertical incision made in the gluteus minimus tendon with a running 0 PDS (polydioxone) suture.

  • The conjoint insertion of the gluteus medius and gluteus minimus and hip capsule are then reapproximated to the cuff of tissue left attached to the anterior aspect of the greater trochanter with interrupted #1 PDS suture. Interrupted sutures are used to close the vertical rent in the gluteus medius muscle belly (Fig. 9). A running #1 PDS suture is used to close the fascia overlying the vastus lateralis muscle.

  • The iliotibial band, subcutaneous tissue, and skin are then closed in the usual fashion.

     

     

     

    255

     

     

    P ITFALLS

    • The suture material used for closure is important. Most braided absorbable sutures have a half-life of only 2 weeks. The monofilament absorbable sutures have a half-life of 6 weeks and are preferred. Another option is to use nonabsorbable sutures.

     

    Direct Lateral Exposure

     

    FIGURE 9

     

    Postoperative Care and Expected Outcomes

    Controversies

    • Limp is more common after all revision hip arthroplasties related to leg length inequality, abductor muscle weakness, and suboptimal restoration of hip biomechanics. Controversy exists as to whether the extensile direct lateral approach is associated with increased limp as compared to other surgical approaches.

    • Controversy also exists as to whether the extensile direct lateral approach is associated with more patients who need walking aids following its use. No proper randomized clinical trial has been performed on this topic.

    • It seems evident that the risk of dislocation is at least 10-fold less with the use of the direct lateral approach as compared to posterior surgical approaches during revision, but again, the data are less than ideal in this regard.

     

    • A benefit of the extensile direct lateral approach for revision arthroplasty is the very low risk of postoperative dislocation (0.5%). Therefore,

      postoperative precautions to prevent dislocation are minimal (i.e., avoiding flexion over 90° and forced internal rotation for the first 6 weeks).

    • Most revision patients are allowed weight bearing as tolerated depending on stability of the revision reconstruction.

    • Patients are discouraged from performing resisted hip abductor exercises for the first 6 weeks.

    • Most patients prefer to use crutches, and occasionally a walker, if unstable in their gait for the first 3–4 weeks following this type of revision procedure.