Hip Resurfacing Arthroplasty

P ITFALLS

• Renal dysfunction: the lack of metal ion clearance by the impaired kidney may predispose these patients to the possible carcinogenic effects of increased serum metal ion concentrations.

   

• Severe hip dysplasia (Crowe classes III and IV): bony acetabular deficiency combined with the inability to insert screws into the acetabular cup makes the initial implant stability problematic.

   

• Significant leg length discrepancy (2 cm) or valgus femoral neck may be better addressed with a stemmed THR.

• Severe osteoporosis.

• Active infection.

• Relative contraindications:

  • Multiple cysts greater than 1 cm or osteonecrotic lesions

    with Kerboull angle of greater than 200°

  • Metal hypersensitivity

 

Hip Resurfacing Arthroplasty

 

Indications

• Advanced osteoarthritis (OA) in the young adult (age 60 years) in whom a conventional total hip replacement (THR) may not last a lifetime, therefore requiring a revision procedure.

• Primary or secondary OA: osteonecrosis, trauma, Legg-Calvé-Perthes disease, developmental dysplasia of the hip (Crowe class I and II), or slipped capital femoral epiphysis.

• Posttraumatic hip in which a conventional hip replacement would be difficult secondary to abnormal anatomy.

• The ideal patient has a Surface Arthroplasty Risk Index (SARI) 3:

  • Femoral head cyst: 1 cm  2 points

  • Weight: less than 80 kg  2 points

  • Previous hip surgery: 1 point

  • University of California at Los Angeles activity score: greater than 6  1 point

    • A SARI score greater than 3 is associated with a 12-fold risk of early failure or adverse radiologic changes (Beaulé, Dorey, et al., 2004).

      Examination/Imaging

      Physical Examination

• Complete hip examination with emphasis on:

  • Range of motion (ROM)

  • Abductors strength

    Controversies

    • Women of childbearing age

    • Patients older than 65 years

     

  • Impingement sign: pain on passive hip flexion to 90°, internal rotation, and adduction

  • Leg length discrepancy

  • Vascular examination

    Radiographs

• Anteroposterior (AP) pelvis radiograph, including both hips.

• Cross-table lateral radiograph of the affected hip.

• Reduced anterior femoral head-neck offset or a pistol grip deformity. Offset of Eijer less than 0.15 is abnormal (Beaulé et al., 2007).

  Templating

• We use the Conserve Plus hip resurfacing prosthesis (Wright Medical Technology, Arlington, TN)

• Templating is the most important preoperative step for a successful outcome.

 

 

 

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A B

FIGURE 1

 

• The template, which is magnified by 15%, is placed over the AP (Fig. 1A and 1B) and lateral views:

• Anteroposterior view

  • The femoral head is sized first. The dotted lines in Figure 1A indicate the level of reaming by the cylindrical reamer. Femoral neck notching should be avoided.

  • The acetabulum is subsequently sized, keeping in mind that the Conserve Plus shell thickness is available in two sizes, 3 and 5 mm, allowing us to deal with femoral head–to-acetabulum mismatch. For example, a femoral head that is sized to 50 mm can be matched to a 56-mm acetabular normal-thickness cup in a normal acetabulum, or a 60-mm increased-thickness cup in a shallow and widened acetabulum.

     

     

     

    Hip Resurfacing Arthroplasty

     

    A B

    FIGURE 2

     

    192

     

    • Lateral view

      • The orientation of the femoral component is gauged on the lateral view to re-establish the anterior femoral head-to-neck offset ratio (Fig. 2A and 2B). Anterior translation may be needed to re-establish anterior offset.

    Treatment Options

    • Nonoperative treatment.

    • Hemiresurfacing can be used as a time-buying option for patients less than 30 years of age with a large osteonecrotic lesion either at the pre- or postcollapse stage with minimal acetabular cartilage involvement.

    • Total hip replacement.

     

    Computed Tomography

    • Assesses bony architecture (osteophytes, fracture fragments)

      Surgical Anatomy

    • The most common surgical approach for resurfacing remains the posterior approach. The approach described in this procedure is one that uses the surgical hip dislocation approach as described by Ganz et al. (2001). The advantages of this approach over the posterior approach are less soft tissue dissection as well as preservation of the extraosseous femoral head blood supply, which may play a role in preventing femoral component loosening and femoral neck fracture.

    • The femoral head blood supply is mainly derived from the medial femoral circumflex artery (MFCA), with a lesser contribution from the lateral circumflex (Fig. 3).

       

       

      Head of femur

       

                       

       

       

      Gluteus medius

       

      Terminal synovial branches of the medial femoral circumflex artery

      Deep branch of the medial femoral circumflex artery

      Lesser trochanter

      with nutrient

      vessels

       

      Insertion of tendon

      of piriformis

       

      Insertion and tendon of gluteus medius

       

      Hip Resurfacing Arthroplasty

       

      FIGURE 3

       

      193

       

• The anatomy of the MCFA is well described by Gautier et al. (2000).

• The MFCA is almost always derived from the deep femoral artery. One of its five branches, the deep branch, courses toward the intertrochanteric crest between the pectineus and the obturator externus. Posteriorly, it can found between the inferior gemellus and the quadratus femoris. It remains posterior to the tendon of the obturator externus and anterior to the tendons of the superior gemellus, obturator internus, and inferior gemellus.

• At the level of the hip capsule, it penetrates the joint just cranial to the insertion of the superior gemellus tendon and distal to the piriformis tendon. It subsequently gives off two to four retinacular branches that course beneath the synovial sheath and perforate 2–4 mm lateral to the bone-cartilage junction of the femoral head via the nutritive femoral foramina.

 

P EARLS

• Place the patient forward on the operating table to ease placement of the leg over the side while preparing the femur.

 

Positioning

• Spinal anesthetic is used for most of our hip resurfacing.

• The patient is placed in the lateral decubitus position, with the pelvis and thorax stabilized with padded bolsters.

• The entire leg is prepped and free draped. A leg cover is used up to the midthigh level.

   

   

  P EARLS

  • Extending the hip facilitates the mobilization of the iliotibial band.

     

  • Leaving part of the gluteus medius tendon attached to the main trochanteric fragment ensures that the osteotomy remains extracapsular.

     

  • Irrigate the saw blade thoroughly to avoid overheating.

     

    P ITFALLS

  • GT osteotomy site marking is critical in keeping the wafer viable and avoiding penetrating into the femoral neck as well as the branch of the MFCA supplying the retinacular vessels.

     

  • Often the arthritic hip is fixed in external rotation, thus it may not be possible to sufficiently internally rotate the leg in order to obtain the proper plane for the osteotomy. In this situation, the surgeon must compensate for the deformity by aiming the saw blade laterally to avoid penetrating into the femoral neck.

   

  Hip Resurfacing Arthroplasty

   

  Portals/Exposures

• A slightly posteriorly concave incision is made centered over the greater trochanter (GT) and measuring approximately 12–14 cm (Fig. 4).

• The iliotibial band is divided from distal to proximal between the tensor and gluteus maximus. Further subcutaneous release can be performed as needed. In large men, it may be easier to split the gluteus maximus muscle.

• The trochanteric bursa is then incised.

• The gluteus maximus is retracted with a right-angle retractor to identify the posterior border of the gluteus medius as well as the junction between the gluteus minimus and the piriformis.

• With the leg in 15° of internal rotation and resting on a padded Mayo stand, the GT osteotomy is marked using cautery, leaving a 2-mm cuff of gluteus medius tendon attached to the main trochanteric fragment (Fig. 5A and 5B). The osteotomy exits proximally just lateral to the medial portion of the gluteus medius and distally past the vastus lateralis tubercule.

• The vastus lateralis is then elevated from its tubercle distally to the midlevel of the gluteus maximus insertion. Careful attention is paid so as not to compromise the vastus lateralis origin on the GT.

 

194

 

Tensor fascia lata

 

 

A B

FIGURE 4

 

Gluteus maximus

 

 

 

 

195

 

Anterior Posterior

 

A

 

 

 

 

Gluteus Fascia lata minimus

 

Gluteus medius

 

Vastus Piriformis lateralis

10-15°

Hip Resurfacing Arthroplasty

 

internal rotation

 

 

Gluteus maximus

Gamelli and obturator internus

Quadratus

 

 

 

B

FIGURE 5

 

196

 

Instrumentation

• Blunt Hohmann retractor

 

Hip Resurfacing Arthroplasty

 

• Using a 3.2-mm drill bit, the GT osteotomy wafer is predrilled in its proximal third, aiming inferomedially toward the lesser trochanter. The latter facilitates the reduction of the GT osteotomy at the end of the procedure.

• A thin saw blade (0.09 mm) is used to perform the osteotomy.

  Controversies

  • Risk of trochanteric nonunion is 1–2% (Beaulé et al., 2007).

   

• A Hohmann retractor is then used to elevate the GT wafer (Fig. 6). The vastus lateralis is further elevated distally, and the remainder of the gluteus medius is released from the femur. This can be done by following the proximal edge of the piriformis tendon and retracting the gluteus minimus superoanteriorly.

• The dissection off the anterior capsule requires a sharp dissection since the plane between the iliofemoral ligament/capsule and the gluteus minimus can be difficult to develop.

• The leg is then placed in flexion and external rotation to allow the elevation of the vastus lateralis and intermedius from the lateral and anterior aspect of the proximal femur (Fig. 7).

• With further flexion and elevation and the use of a right-angle retractor for the gluteus medius and minimus, the capsule is exposed. It is then incised using a Z-shaped incision along the axis of the femoral neck inferiorly and the acetabular rim posteriorly (Fig. 8). Careful attention is paid to the retinacular vessels traveling along the superior edge of the femoral neck.

• The capsule is then elevated from the acetabular rim while avoiding the area posterior to the lesser trochanter in order to protect the main branch of the MFCA.

• The hip is then dislocated with flexion, external rotation, and adduction of the leg using a bone hook under the femoral neck.

• With the hip dislocated, the trochanteric wafer is folded in anteriorly and the leg is kept in flexion and external rotation in a sterile cover hanging over the edge of the operating table.

   

   

   

   

   

  Hip Resurfacing Arthroplasty

   

   

   

   

   

  197

   

  FIGURE 6

   

  FIGURE 7

   

  FIGURE 8

   

   

  198

   

   

  P EARLS

  • If the true head-neck junction is not properly visualized due to osteophytes, the latter can be removed with a ¾-inch curved osteotome with careful attention so as to not damage the retinacular vessels. The use of the see-through gauge facilitates proper bony removal.

     

    P ITFALLS

  • Varus position of the femoral component is associated with a higher risk of premature failure due to loosening (Beaulé, Lee, et al., 2004).

     

  • Excessive valgus position may lead to femoral neck notching and damage to the retinacular vessels, impairing femoral head blood flow, which can be associated with early femoral neck fracture (Beaulé et al., 2006).

   

  Hip Resurfacing Arthroplasty

   

  Procedure

  Step 1

• A femoral head-neck elevator is used to facilitate preparation (Fig. 9).

• The femoral head is sized using a see-through gauge (Fig. 10). In the presence of osteophytes along the head-neck junction or in case of lack of anterior offset, the normal femoral neck axis needs to be re-established for proper drill guide pin placement using a high-speed burr and/or osteotomes (Fig. 11A and 11B). Careful attention must be paid to the retinacular vessels along the superior aspect of the neck (Fig. 12).

• Using the final-size cylindrical reamer (Fig. 13) or a

pin-centering guide, the cylindrical reamer drill guide pin is then placed onto the femoral head with a 5–10° valgus orientation from the anatomic neck of the femur to give an angle between 135° and 145°.

 

 

 

FIGURE 9

 

 

 

FIGURE 10

 

 

 

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Hip Resurfacing Arthroplasty

 

A B

FIGURE 11

 

 

 

FIGURE 12

 

 

 

FIGURE 13

 

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Hip Resurfacing Arthroplasty

 

• In the sagittal plane, the guide pin is placed slightly superior and anterior to re-establish anterior head-neck offset and avoid reaming through the retinacular vessels.

  Instrumentation/ Implantation

  • Femoral head-neck elevator

   

• The position of the guide pin is then checked for angulation with a goniometer with the leg in neutral rotation (Fig. 14). The appropriate cylindrical reamer gauge for the measured femoral head size should also be able to rotate freely around the guide to assure that the cylindrical reamer will not cause any neck notching (Fig. 15). The guide pin is repositioned as needed.

  Controversies

  • How close one should be to the femoral neck in terms of getting the smallest femoral component in order to preserve acetabular bone stock is uncertain.

   

• Cylindrical reaming is started with an oversized reamer that is two sizes bigger than the measured head. The reamer is advanced in longitudinal pulsatile fashion along the axis of the pin to avoid bending it.

• Reaming is stopped 2–3 cm from the neck and a ¾-inch curved osteotome is used to remove any osteophytes (Fig. 16). The high-speed burr can be used to complete the preparation of the femoral head-neck junction, carefully avoid the retinacular vessels (Fig. 17).

• Prior to proceeding, the direction of the cylindrical reamer compared to the anatomical neck should be re-evaluated and the guide pin adjusted as necessary.

• The cylindrical reaming is then completed with the smaller reamers.

   

   

   

   

  FIGURE 14

   

   

  201

   

   

   

   

   

  Hip Resurfacing Arthroplasty

   

  FIGURE 15

   

   

   

  FIGURE 16

   

  FIGURE 17

   

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  Hip Resurfacing Arthroplasty

   

• A saw cutoff guide is placed over the reamed bone and is secured with two short pins through the guide holes, making sure that all of the reamed bone is covered.

• An oscillating saw is then used to resect the femoral head dome (Fig. 18).

• The tower alignment guide is then placed flush onto the cut bone and a final check of the orientation is carried out using a goniometer (Fig. 19).

• The stem hole is drilled (over-reaming by 2 mm is necessary for cemented stems to provide a cement mantle).

• The chamfer guide is subsequently placed into the drilled hole and the chamfer reamer is used to complete the femoral head preparation (Fig. 20).

• A trial prosthesis is used to confirm full seating (Fig. 21). It should rotate freely; any areas of asymmetric reaming are addressed with the final-size cylindrical reamer using the chamfer guide.

• Any cystic areas are removed using a curette.

   

   

   

  FIGURE 18

   

   

  203

   

   

   

   

   

  Hip Resurfacing Arthroplasty

   

  FIGURE 19

   

   

   

  FIGURE 20

   

  FIGURE 21

   

  204

   

   

  P EARLS

  • In order to ensure full seating of the acetabular shell, the amount of coverage for the see-through gauge should match that of the component once inserted.

     

    P ITFALLS

  • Placing the acetabulum in too much anteversion may create a situation of bony impingement and anterior instability.

     

  • Incomplete seating of the acetabular component.

   

  Hip Resurfacing Arthroplasty

   

  Step 2

• With the femoral head preparation completed, the hip is placed in flexion and external rotation with the knee fully extended and resting onto a padded Mayo stand (Fig. 22).

• A Cobra retractor is then placed onto the posterior wall of the acetabulum to retract the proximal femur, and a Hohmann retractor is placed on the anterior wall of the acetabulum to improve the exposure.

• The anterior and posterior walls are assessed for any bony deficiency, and the labrum is excised with sharp dissection.

• The inferomedial capsule is then released in a “pie crust” fashion using cautery to allow further mobilization of the femur.

  Instrumentation/ Implantation

  • Padded Mayo stand

  • Cobra retractor

   

• The acetabulum is prepared in the usual fashion for a THR, starting with a reamer that is 8 mm smaller than the final size of the acetabular implant and ending with the last two reamers increasing in 1-mm increments. The Conserve Plus system has a 1-mm press-fit built into the component, allowing reaming up to the templated cup size.

  Controversies

  • If final acetabular preparation would entail going one size larger than one would usually do for a primary THR, is it better to downsize the femur or increase the socket size?

   

• Cysts are curettaged and grafted when encountered.

• Acetabular preparation can be verified using a see-through gauge and metallic acetabular rings prior to implantation (Fig. 23).

• The reamed acetabulum is then irrigated prior to inserting the component in 20° of anteversion and 45° of abduction. It is important to have the operative assistant help the surgeon in maintaining

   

   

   

  FIGURE 22

   

  205

   

  Hip Resurfacing Arthroplasty

   

  this alignment as the surgeon impacts the cup with a 10-lb hammer (Fig. 24). The cup is further impacted with the central ball impactor.

  • The stability of the cup is then checked by pushing along its edges.

  • Peripheral osteophytes are removed with an osteotome to prevent impingement.

     

     

     

    FIGURE 23

     

     

     

    FIGURE 24

     

    206

     

     

    P EARLS

    • We recommend cementing the stem in patients with cystic defects greater than 1 cm or with a small femoral head (46 mm) in order to increase the fixation area.

       

    • Cover the femoral component with wet gauze as the cement is curing to prevent a large increase in temperature associated with thermal osteonecrosis.

       

    • Avoid overfilling of the femoral component with cement.

       

      P ITFALLS

    • Completely cleaning and drying the prepared femoral head prior to cementing is important in obtaining a good bone-cement interface and therefore solid fixation.

       

    • Delaying implantation of the femoral component after cement mixing may compromise full seating of the component due to the high viscosity of the cement.

     

    Hip Resurfacing Arthroplasty

     

    Step 3

• With the hip in flexion and external rotation into a sterile cover, the femoral head is irrigated with pulsed lavage and dried using a tapered suction tip placed in the central drill guide hole (Fig. 25).

• Any area of hard cortical bone is cancellized using a

  1/8-inch drill bit.

• The cement is poured in its liquid form to fill one quarter of the femoral component (Fig. 26).

• The prepared femoral head is further covered with cement without allowing cement to penetrate into the central drill guide hole, which is continuously being suctioned (Fig. 27).

• The femoral component is then cemented with continuous manual pressure as well as light impaction with a hammer (Fig. 28).

• Any excess cement is carefully removed using curettes (Fig. 29).

• Pressure is applied until the cement is fully cured.

   

  Controversies

  • Cementation of the short femoral stem

  • Grafting or not grafting femoral head cysts

   

   

   

   

  FIGURE 25

   

  FIGURE 26

   

   

  207

   

   

   

   

   

  Hip Resurfacing Arthroplasty

   

  FIGURE 27

   

   

   

  FIGURE 28

   

  FIGURE 29

   

  208

   

  Hip Resurfacing Arthroplasty

   

  Step 4

• The hip is then reduced and taken through a ROM check to look for any bony impingement, which can be addressed with an osteotome.

• The capsule is closed using #1 interrupted Vicryl sutures and reattached to the acetabular rim posteriorly. Avoid watertight closure, which may lead to a hematoma buildup that can constrict the retinacular vessels at the head-neck junction.

• The GT osteotomy is subsequently properly reduced by placing a drill bit in the osteotomy site predrilled at the beginning of the procedure (Fig. 30). The reduction is further maintained with a large, sharp reduction forceps while a second hole is drilled and a 4.5-mm screw is placed to secure the reduction. A second screw is inserted for additional fixation. In cases of bilateral hip surgery, three screws are inserted in each hip.

• An intraoperative radiograph is taken to ensure

  proper screw and implant placement (Fig. 31).

• The incision is then closed in layered fashion without the use of drains.

   

   

   

  FIGURE 30

   

   

   

  209

   

  Hip Resurfacing Arthroplasty

   

  FIGURE 31

   

   

  P ITFALLS

  • Patient noncompliance with restricted weight bearing.

   

  Postoperative Care and Expected Outcomes

  • All patients are given antibiotic prophylaxis for 24 hours postoperatively as well as low-molecular-weight heparin for a period of 14 days.

    Controversies

    • How active can patients be after hip resurfacing?

     

  • Patients are restricted to weight bearing of no more than 30 lbs with no active straight leg raise for 6 weeks.

  • Patients are assessed by the hospital’s physical therapist postoperatively and are given gait training and gentle ROM exercises to perform following discharge. At their first postoperative visit (6 weeks), the patients are started on formal physical therapy consisting of muscle-strengthening exercises.

  • They are allowed to return to sports at the 3-month mark.

 

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Hip Resurfacing Arthroplasty

 

Evidence

Beaulé PE, Campbell PA, Hoke R, Dorey F. Notching of the femoral neck during resurfacing arthroplasty of the hip: a vascular study. J Bone Joint Surg Br.

2006;88:35–9.

 

Using laser Doppler flowmetry, femoral head blood flow was measured in 14 osteoarthritic femoral heads during routine total hip replacement surgery, before and after notching of the femoral neck. In ten hips there was a reduction in blood flow of more than 50% from the baseline value after simulated notching of the femoral neck. These results suggest that femoral head vascularity in the osteoarthritic state is similar to the non-arthritic state, where damage to the extraosseous vessels can predispose to avascular necrosis. Surgeons who perform resurfacing arthroplasty of the hip should pay careful attention to these vessels by avoiding excessive dissection around the femoral neck and/or notching. (Level I evidence)

 

Beaulé PE, Dorey FJ, LeDuff M, Gruen T, Amstutz HC. Risk factors affecting outcome of metal-on-metal surface arthroplasty of the hip. Clin Orthop Relat Res.

2004;(418):87–93.

 

Ninety-four hips in 83 patients with a mean age of 34.2 years (range, 15–40 years) were reviewed after undergoing metal-on-metal hip resurfacing. Seventy-one percent of the patients were males and 29% of the patients were females; 14% had previous surgery. The Chandler index and surface arthroplasty risk index were calculated. The mean follow-up at 3 years (range, 2–5 years) showed that three hips were converted to a total hip replacement at a mean of 27 months (range, 2–50 months) after the original surgery, and 10 hips had significant radiologic changes. The mean surface arthroplasty risk index for these 13 problematic hips versus the remaining hips was significantly higher, 4.7 and 2.6, respectively. With a surface arthroplasty risk index score greater than 3, the relative risk of early problems is 12 times greater than if surface arthroplasty risk index is less than or equal to 3. (Level III evidence)

 

Beaulé PE, Harvey N, Zaragoza E, Le Duff MJ, Dorey FJ. The femoral head/neck offset and hip resurfacing. J Bone Joint Surg Br. 2007;89B:9–15.

 

The femoral head/neck offset was measured in 63 hips undergoing metal-on-metal hip resurfacing and in 56 hips presenting with non-arthritic pain secondary to femoroacetabular impingement. Most hips undergoing resurfacing (57%; 36) had an offset ratio 0.15 preoperatively and required greater correction of offset at operation than the rest of the group. In the nonarthritic hips the mean offset ratio was 0.137 (0.04 to 0.23), with the offset ratio correlating negatively to an increasing alpha angle. An offset ratio 0.15 had a 9.5-fold increased relative risk of having an alpha angle 50.5°. Most hips undergoing resurfacing have an abnormal femoral head/neck offset, which is best assessed in the sagittal plane. (Level IV evidence)

 

Beaulé PE, Lee JL, Le Duff MJ, Amstutz HC, Ebramzadeh E. Orientation of the femoral component in surface arthroplasty of the hip. A biomechanical and clinical analysis. J Bone Joint Surg 2004;86A:2015–21.

 

The correlation between the orientation of the femoral component and the outcome of metal-on-metal hip resurfacing was evaluated, as were stresses within the resurfaced femoral head as a function of the orientation of the femoral component. Hips with a stem shaft angle of 130° had an increase in the relative risk of an adverse outcome by a factor of 6.1 (p  0.004). In the entire cohort, stresses in the superior aspect of the resurfaced femoral head were substantially lower during slow walking than they were during fast walking (7.1 N/mm2 compared with 14.2 N/mm2). Optimizing the femoral stem-shaft angle toward a valgus orientation during the preparation of the femoral head is important when a hip is being reconstructed with a surface arthroplasty because the resurfaced hip transmits the load through a narrow critical zone in the femoral head-neck region and the valgus angulation may reduce these stresses. (Level IV evidence)

 

Ganz R, Gill TJ, Gautier E, Ganz K, Krugel N, Berlemann U. Surgical dislocation of the adult hip a technique with full access to the femoral head and acetabulum without the risk of avascular necrosis. J Bone Joint Surg Br. 2001;83:1119–24.

 

A technique for operative dislocation of the hip, based on detailed anatomical studies of the blood supply is described. This surgical technique combines aspects of approaches which have been reported previously and consists of an anterior dislocation