Introduction                       

Metal on metal hip resurfacing (MOMHR) has regained popularity in the last decade as an alternative to total hip arthroplasty (THA) especially for younger active patients. The primary advantage of MOMHR is that it preserves proximal femoral bone stock. MOMHR offers excellent implant stability with good range of motion because of the large femoral head.1,2 Also, if required, it can often easily be converted to THA with minimal morbidity. The results of revision THA, on average, are not as good. Revision THA is often accompanied by a greater degree of periprosthetic bone loss due to osteolysis.3

The results of THA in young active patients have a higher failure rate compared to the results in the older patients.4 These young active patients might need multiple future revisions in their lifetime and therefore the importance of bone conservation should be paramount.4 Patient selection and proper surgical technique for MOMHR, which has been modified from its use in THA5 are the key factors in obtaining a successful outcome.6 We describe here a novel surgical technique for MOMHR which has yielded excellent reproducible outcomes for our patients.

 

Patient                     Selection                     

Patient selection is the first key step on the journey towards a successful MOMHR outcome. The ideal patient is a young (typically under 55 years of age) active male. He should have good bone quality despite end stage osteoarthritis and femoral head and neck morphology appropriate for resurfacing.7-10 Specifically, the more spherical the head (relatively devoid of cysts or “geodes”), the more appropriate it is for MOMHR. Coxa plana, coxa vara and osteonecrotic femoral heads make for suboptimal MOMHR. Femoral neck morphology is important as well. Short or wide necks make MOMHR a poor choice compared to THA. Acetabuli which are shallow or devoid of bone in any way (dysplasia or post-traumatic OA) are less than ideal for proper MOMHR.

Apart from the general contraindications to THA, such as suspected or known sepsis, those specific to MOMHR are:

1. Patients with end stage renal disease or the potential for compromised renal function (such as diabetes mellitus) because metal ions generated at the articulation can accummulate in the blood and tissues.

2. Women capable of child bearing may want to avoid MOMHR because metal ions do pass through the placenta.11,12

3. Females with risk of osteoporosis have a higher relative risk of revision.13,14

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4. Patients with poor bone quality should be avoided. Beaule’s SARI index8 is a useful way for identifying patients for MOMHR.

5. Patients with severe leg length discrepancy.

   Total Hip Arthroplasty

    

6. Known or suspected metal hypersensitivity like from nickel in jewellery.

 

Templating                       

As with THA, preoperative planning is essential. This is true especially for a technically demanding procedure like MOMHR since even experienced surgeons may have to “bail-out” to THA. All MOMHR patients should be template also for THA with consideration given to head size and articulation couple. Inadequate preoperative planning or poor surgical technique can lead to early implant failure due to various factors such as inadequate preparation of the acetabulum, inaccurate component placement, femoral neck notching or oversizing of the femoral component.15-17 Templating can be performed either on conventional or digital radiographs.18 Attention should always be paid to the proper magnification for the radiographs being templated.

The femoral template (Fig. 13.1) is placed at the medial head neck junction to begin with. After determining the appropriate size, the implant is placed in a slight valgus position to the normal neck shaft angle. The femoral component should adequately cover the superior cortical femoral neck without leaving any exposed cancellous bone. Also too much valgus orientation can lead to lateral femoral notching predisposing to femoral neck fracture. The point on the lateral cortex of the femur that is transected by the implant axis is the entry point for the guide pin and its distance from the tip of the greater trochanter is measured (Fig. 13.2).

The acetabular component is templated like any cementless THA. The cup placement is medialized all the way to the lateral border of the anatomical teardrop and appropriate size estimated. It is desirable to have an inclination angle of approximately 40 degrees and avoid excess vertical positioning of the cup which can lead to increased contact stresses and rapid wear of metal on metal couple.19 Almost all MOMHR designs are unforgiving when it comes to an acetabular inclination (abduction) angle of 50 degrees or more. The proposed center of rotation is marked once the socket location is estimated.

There is a limitation to the femoral sizes available for any specific outer diameter of acetabular component in MOMHR. If there is a gross mismatch in the sizing of the acetabular and available femoral components, THA should be favored. THA should always be available

 

 

 

 

Figure 13.1: Preoperative templating of X-ray Figure 13.2: Point of entry marked on the lateral cortex

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Metal on Metal Hip Resurfacing Arthroplasty Via Modified Enhanced Posterior Soft Tissue Repair

 

as a back-up and the possibility of “bailing-out”20 intraoperatively to THA, regardless of the unlikelihood, should be discussed (and consented to) with the patient before surgery. Also an intraoperative finding such as extensive femoral head damage, cystic changes, femoral notching or fracture will necessitate “bailing-out” to THA.21

 

Patient     Positioning     and     Exposure              

The patient is usually given regional (epidural and/or spinal) anesthesia. Any one of several approaches can be used depending on the surgeon preference and experience. The exposure is different and more difficult than with conventional THA because the femoral head and neck are not resected, must be worked around and also the head vascularity must be maintained during the procedure. We prefer the use of a modified enhanced posterior soft tissue repair for the MOMHR procedure.5,22

 

 

The patient is positioned in lateral decubitus with the help of pelvic supports secured in a neutral position on a custom designed hip table (Fig. 13.3). Care is taken to pad all the bony prominences. The positioning must allow more than 90 degrees of flexion of the hip. The extremity is prepared and draped in a sterile fashion as per standard protocols. We prefer chlorhexidine and iodinated plastic skin wrap. The bony prominences such as the trochanter of the femur are marked with a surgical marking pen. A curvilinear incision is made over the posterolateral aspect of the hip along the posterior border of the trochanter. The incision is generally more posterior and longer than that of a usual total hip replacement. The incision is deepened through the fat with a scalpel till the fibrous layer of gluteal and tensor fascia. After incising the tensor fascia lata centrally with a scalpel, the fascia is further divided distally and proximally with the help of curved Mayo scissors (taking care to preserve the vastus lateralis and the gluteus maximus muscles). The gluteus maximus is divided along the line of its fibers thereby minimizing trauma. The trochanteric bursa is divided to expose the posterior aspect of the trochanter. The tendinous insertion of gluteus maximus tendon is divided with the help of electrocautery to avoid damage to the first perforating artery below. Depending on the patient size and muscularity, only 50 to 90 % of the proximal gluteal sling is divided. It also relaxes tension on the sciatic nerve.23 The fat overlying the short external rotators is then removed to visualize the tendons below (Fig. 13.4). The interval between the piriformis tendon and the gluteus medius muscle is then developed and a thin bent Hohmann retractor placed over the underlying gluteus minimus muscle. Next an Aufranc retractor is used to sweep the inferior gemellus inferiorly to visualize the posteroinferior hip capsule. The pyriformis and conjoined tendons are detached from the back of the trochanter and

 

Figure 13.3: Patient positioned on custom hip table

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Figure 13.4: External rotators identified during exposure

 

Figure 13.5: Pyriformis and conjoint tendons being released from trochanter

 

 

separated from the capsule underneath (Fig. 13.5). They are then tagged with separate no. 2 braided nonabsorbable sutures using a Mason Allen type stitch. The gluteus minimus is then separated from the capsule with the use of a Cobb elevator and the thin bent Hohmann retractor replaced beneath the minimus for anterior retraction of that muscle.

Next the quadratus femoris muscle is released using elecrocautery. A trapezoidal flap with a wider base posteriorly than anteriorly (about 3 times) is raised by taking capsule off the intertrochanteric crest starting from its posterosuperior edge (Figs 13.6 and 13.7 ). The trapezoidal capsular flap is also tagged superiorly and inferiorly with no. 2 nonabsorbable braided suture using the Mason-Allen stitch. These tag sutures are cut long to distinguish them from the previous ones placed in the short external rotators. The superior tendon and capsule tag sutures are bunched together and a clamp applied. The same is done for the inferior tagging sutures. A Kocher clamp is placed, prior to hip dislocation, on the anterosuperior capsule at the acetabular margin to later facilitate the anterosuperior capsulotomy.

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Metal on Metal Hip Resurfacing Arthroplasty Via Modified Enhanced Posterior Soft Tissue Repair

 

Figure 13.6: EPSTR Opening: The piriformis tendon and the conjoined tendons have been detached as a tendinous sleeve from their insertions, tagged superiorly and inferiorly using nonabsorbable sutures, and then reflected posteriorly. Arthrotomy of the posterior capsule has created a posteriorly based trapezoidal-shaped capsular sleeve that is likewise tagged twice with sutures and reflected posteriorly. (Drawings by Nicholas D Colacchio and reproduced with permission from Macaulay W, Colacchio ND, Fink LA. Modified enhanced posterior soft tissue repair results in a negligible dislocation rate after hip resurfacing. Operative Techniques in Orthopaedics 2009;19(3):163-8.)

 

Figure 13.7: Capsular and tendinous flap retracted

 

It is important to leave soft tissue attached to the femoral side and not take the dissection very close to the bone. Also the arthrotomy is kept superficial preserving the soft tissue on the outer surface of the femoral neck to preserve femoral head vascularity. Retinacular vessels on the surface of femoral head which are important for maintaining femoral head vascularity can be damaged if deep or careless arthrotomy is performed. McMahon et al demonstrated that intraosseous femoral head blood supply in inflammatory arthritis is enough to maintain femoral head vascularity despite compromise of extraosseous blood supply through the medial circumflex femoral artery.24

The hip is now dislocated and the neck sizing guides (Fig. 13.8) used to determine the possible size range of femoral components which can later be placed. The Kocher clamp (which had been applied to the superior hip capsule at the acetabular margin) is then better visualized by positioning the leg in 90 degrees of flexion, 90 degrees of internal rotation and in maximal adduction to allow visualization of the anterosuperior hip capsule which can

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Figure 13.8: Femoral sizing guide used to estimate component size

 

now be incised using the Muller scissors to meet up with the anteroinferior capsulotomy. Complete anterior capsulotomy is usually required to mobilize the femoral head enough to prepare the socket. Next the leg is positioned in full extension, maximal internal rotation and neutral adduction, to allow the surgeon to visualize the anteroinferior hip capsule. A large capsulotomy scissor (of Muller) is used to divide the anteroinferior (meeting up with the anterosuperior slit) capsule near the psoas tendon. The anterior hip capsule can be palpated to be sure there are no remaining anterior tight capsular fibers. After the circum-ferential capsulotomy, the femoral head is cleared of osteophytes especially the anterosuperior region taking care not to strip any soft tissue. The head is then prolapsed beneath the gluteus medius by placing a straight Hohmann retractor under the neck of the femur and impacting the tip forcefully into the anterior column of the pelvis at a level equal to the superior aspect of the acetabulum. Neutral rotation of the femur in slight flexion and adduction will allow full exposure of the acetabulum for preparation.

 

Acetabular                  Preparation                  

The acetabular preparation is nearly similar to that of any pressfit cementless acetabular component (without screw holes) placement. A bent wide Hohmann retractor is impacted into the ischium posteriorly between the labrum and posterior capsule to retract the posterior tissues. A cobra retractor is placed inferiorly beneath the transverse ligament. This gives a wide and full exposure for acetabular preparation.

The acetabular labrum, transverse acetabular ligament and the ligament teres are excised and the acetabular fossa exposed. A small reamer is then used to ream medially to reach to the quadrilateral plate (Fig. 13.9). The reaming is then begun at 40 degrees abduction and 20 degrees anteversion inferiorly within the socket. Hemispherical reamers are upsized in 2 mm increments (and then 1 mm as the final reaming size is approached) until the socket is prepared circumferentially with minimal removal of cortical bone at the periphery. The acetabulum is underreamed by 1 mm for the BHR acetabular component to be inserted. The acetabular component (Figs 13.10 and 13.11) has 2 inferior antirotation flanges which should be placed in the pubis and the ischium respectively. The acetabular component is impacted forcefully into the position of 40 degrees of abduction and 20 degrees of anteversion (Fig. 13.12). The implant should be completely seated as judged by the change of sound and nonprogression of implant with subsequent blows. The impactor handle is removed and the polyethylene impactor is retracted to confirm the cup positioning (Fig. 13.13). If any changes

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Metal on Metal Hip Resurfacing Arthroplasty Via Modified Enhanced Posterior Soft Tissue Repair

 

Figure 13.9: Reaming of the acetabulum with femoral head prolapsed beneath the gluteus medius

 

 

 

 

Figures 13.10A and B: Acetabular component with antirotation flanges

 

 

 

 

Figure 13.11: Final acetabular component being implanted

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Figure 13.12: Final acetabular component in place in 20 degrees of anteversion and 40 degrees of abduction

 

Figure 13.13: Polyethlene liner retracted to check the final implant positioning

 

 

are contemplated the introducer can be reapplied and position corrected. Once the cup is satisfactorily placed, the holding cables are cut in 2 places and the polyethylene impactor removed with 2 pieces of cable. Acetabular osteophytes can now be removed with a osteotome and ronguer to prevent any impingement. It is desirable to have the anterior aspect of the acetabular component buried 2 mm from the edge of the native socket (Fig. 13.14). The internal diameter of the chosen socket then dictates the size of the femoral head component which will be required.

 

Femoral Preparation

 

The femoral head is now brought in view by flexion, adduction and internal rotation of the limb (Fig. 13.15). The first and the most important step is the femoral guide wire insertion.

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Metal on Metal Hip Resurfacing Arthroplasty Via Modified Enhanced Posterior Soft Tissue Repair

 

Figure 13.14: Acetabular component in place

 

 

Figure 13.15: Femoral exposure

 

 

 

The senior author now uses a freehand technique generally choosing a starting point (Fig. 13.16) about 1 cm above the upper edge of the native fovea (slightly anterior to the center of the head front-to-back). The pin is then advanced (just deep enough to barely engage the lateral cortex of the subtrochanteric femur) roughly parallel to the posterior and inferior femoral neck through a metal cannula to keep the pin from bending and the direction from changing during insertion through sclerotic bone. For any beginning MOMHR surgeon, an alignment guide should be used. The position of the alignment pin is determined from the preoperative templating as discussed earlier. The targeting point on the lateral cortex of the femur is measured from the tip of the greater trochanter. The alignment pin is directed towards the center of the femoral head, engaging the lateral subtrochanteric femur at the targeting point and left protruding from the vastus lateralis. The alignment guide is then anchored on the pin and the leg rotated to deliver the femoral head into the wound. With the

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Total Hip Arthroplasty

 

Figure 13.16: Free hand guidewire insertion

 

Figure 13.17: Femoral alignment guide with stylus

 

central cannulated rod fixed on the femoral head (starting point chosen similarly to that described above for the freehand technique), the position of the guide is checked with a stylus. The stylus tip should pass circumferentially around the femoral neck and not notch the femur at any point (Fig. 13.17). At the same time it should touch the periphery of femoral head to avoid oversizing the femoral component. Once the surgeon is satisfied with the alignment the guide wire is inserted. The position of the guide wire is rechecked with a stylus and if required it can be repositioned with the jig or wire positioning device.

The guidewire is then overdrilled to the length of the implant (Fig. 13.18) and a guide bar is substituted for the wire (Fig. 13.19). The periarticular soft tissues around the femoral neck are covered with wet sponges or towels. This protects soft tissues from bony debris generated during femoral preparation. Care is taken to place the towels in such a way that they don’t get caught in the femoral preparation instruments. A head neck template can be

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Figure 13.18: Overdrilling of the guidewire

 

 

 

 

Metal on Metal Hip Resurfacing Arthroplasty Via Modified Enhanced Posterior Soft Tissue Repair

 

Figure 13.19: Guide bar substitutes the guide-wire

 

used to protect the femoral neck and thus avoid plunging or notching (Fig. 13.20). The peripheral femoral head cutter is then advanced slowly on the alignment rod (Fig. 13.21). It is advantageous to start all reamers before reaching the bone and to advance slowly to lessen the torque and stress generated. After the peripheral cut is completed, the peripheral rim should be removed from the adhering soft tissue on the neck sharply to preserve vascularity. Avulsing this with a ronguer can damage the femoral neck retinacular vessels. The medial head neck junction is then identified and the peripheral femoral cutter on a T handle is advanced to that point. A line is marked on the femoral neck at the point to where the apical head bone needs to be removed. The head planer is then advanced till the marked resection line. The chamfer cutter is used next and advanced till it is fully seated over the

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Total Hip Arthroplasty

 

Figure 13.20: Head neck template used to protect neck during femoral preparation

 

Figure 13.21: Peripheral femoral head cutter

 

femoral head (Fig. 13.22). The bone resection is now checked with the head neck template again and any peripheral irregularities can also be removed with it (Fig. 13.23). The guide bar is removed and the central hole enlarged using a taper drill. Keyholes are drilled on the prepared femoral head on the chamfer and summit with the Wroblewski drill (Fig. 13.24) to enhance interdigitation of the cement. A suction cannula is placed in the femoral canal after drilling through the lesser trochanter (and calcar femorale) to keep the femoral head dry while cementing (Fig. 13.25). All the loose bone is removed and any small cysts curetted.

The femoral neck has previously been marked to determine the point to which the femoral component should be advanced. Pulsatile lavage is used to remove any blood clots and debris from the prepared femoral head and expose the cancellous bone. The prepared head is dried with a dry sponge. Some may prefer an air (particle filtered) jet femoral head bone drying device. The suction cannula in the lesser trochanter also helps in keeping it dry till

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Metal on Metal Hip Resurfacing Arthroplasty Via Modified Enhanced Posterior Soft Tissue Repair

 

Figure 13.22: The chamfer cutter Figure 13.23: Bony resection checked with the head neck template

 

 

 

Figure 13.24: Wroblewski drill Figure 13.25: Suction cannula placed in the femoral canal after drilling through the lesser trochanter

 

cementation of the prosthesis (Fig. 13.26). A low viscosity cement (Simplex Stryker corporation, Kalamazoo, MI, USA) is mixed by hand (spatula, without vacuum) for 30 seconds and poured to approximately one-third height into the femoral component as soon as it is liquid. The femoral component is tilted to spread the cement onto all the femoral component fixation surface. The femoral component is implanted within 1 minute and 15 seconds of mixing the cement (Figs 13.27 and 13.28). The higher viscosity of the cement can lead to incomplete and improper seating of the femoral component. The cement extruded is collected anteriorly on a gauze and any extra cement is curetted out. The sponges covering the periarticular tissues are removed carefully (with all the extra cement and bone debris) as is the trochanteric cannula. The acetabulum is filled with lavage fluid and the femoral head

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Total Hip Arthroplasty

 

Figure 13.26: Prepared femoral head ready for cementing

 

 

 

Figure 13.27: Impaction of the femoral component

 

 

 

 

 

 

Figure 13.28: Final femoral component implanted

 

reduced. Immediate reduction of the head into the acetabulum also helps to dissipate the heat generated from the exothermic cement reaction and decrease any damage to the vascularity of the prepared femoral head. The alignment pin is removed from the femur (if applicable). The hip joint is tested for stability, range of motion and impingement. Two 2.7 mm holes are drilled on the posterior aspect of the trochanter exiting medially near the piriformis fossa. The 4 strands of the proximal and distal suture bundle are passed through the respective trochanteric holes with the help of a suture passer. The leg is then repositioned into neutral or external rotation to help approximate the tendons and capsule to the posterior part of the trochanter. The long capsular sutures are tied first followed by the tendinous sutures to restore the posterior soft tissue envelope. The wound is irrigated with antibiotic solution and a three layer closure completed (Fig. 13.29).

A sterile dressing (Fig. 13.30) and a loosely wrapped elastic bandage are applied to the operated limb (toe to waist). Aspirin and intermittent calf pumps are often used for venous

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Metal on Metal Hip Resurfacing Arthroplasty Via Modified Enhanced Posterior Soft Tissue Repair

 

Figure 13.29: EPSTR Closing: The posterior capsular flap and short external rotators have been approximated to the posterior aspect of the greater trochanter. The superior and inferior capsular sutures (cut to 9 inches, and labeled as X) are tied together first, and then the short external rotator sutures (cut to 6 inches, and labeled as O) are tied together to restore the posterior soft tissue envelope. (Drawings by Nicholas D Colacchio and reproduced with permission from Macaulay W, Colacchio ND, Fink LA. Modified enhanced posterior soft tissue repair results in a negligible dislocation rate after hip resurfacing. Operative Techniques in Orthopaedics 2009;19(3):163-8.)

 

 

 

Figure 13.30: Final sterile dressing

 

Figure 13.31: Bilateral hip resurfacing

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thromboprophylaxis. The patients start weight bearing and physical therapy the next day after surgery and are generally discharged in 2 to 3 days. The patients are followed up regularly at 1 month, 3 months and then yearly thereafter.

Total Hip Arthroplasty

 

Proper preoperative selection of patients, meticulous surgical execution and attention to detail makes the operation reproducible and is necessary for a successful clinical outcome (Fig. 13.31).

 

Acknowledgment                     

Dr Jeffrey A Geller MD for his help with the clinical photographs and Nicholas D Colacchio MD

for the EPSTR figure drawings.

 

Illustrative   Case   (Figs   13.32A   to   F)              

 

 

 

 

 

 

 

Figures 13.32A to C

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Figure 13.32D

 

 

Figure 13.32E

 

 

Metal on Metal Hip Resurfacing Arthroplasty Via Modified Enhanced Posterior Soft Tissue Repair

 

References                       

1. dela Rosa MA, Silva M, Heisel C, Reich M, Schmalzried TP. Range of motion after total hip resurfacing. Orthopedics 2007;30(5):352-7.

2. Kishida Y, Sugano N, Nishii T, Miki H, Yamaguchi K, Yoshikawa H. Preservation of the bone mineral density of the femur after surface replacement of the hip. J Bone Joint Surg Br 2004;86(2):185-9.

3. Robinson AH, Palmer CR, Villar RN. Is revision as good as primary hip replacement? A comparison of quality of life. J Bone Joint Surg Br 1999;81(1):42-5.

4. Joshi AB, Porter ML, Trail IA, Hunt LP, Murphy JC, Hardinge K. Long-term results of Charnley low-friction arthroplasty in young patients. J Bone Joint Surg Br 1993;75(4):616-23.

5. Macaulay W, Colacchio ND, Fink LA. Modified enhanced posterior soft tissue repair results in a negligible dislocation rate after hip resurfacing. Operative Techniques in Orthopaedics 2009;19(3):163-8.

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6. Morlock MM, Bishop N, Zustin J, Hahn M, Ruther W, Amling M. Modes of implant failure after hip resurfacing: morphological and wear analysis of 267 retrieval specimens. J Bone Joint Surg Am 2008;90(Suppl 3):89-95.

7. Amstutz H, Beaule PE, Leduff M. Hybrid metal on metal surface arthroplasty of the hip. Operative Techniques in Orthopaedics 2001;11(No. 4):253-62.

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8. Beaule 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.

9. Maguire CM, Seyler TM, Boyd HS, Lai LP, Delanois RE, Jinnah RH. Hip resurfacing-keys to success. Bull NYU Hosp Jt Dis 2009;67(2):142-5.

10. Daniel J, Pradhan C, Ziaee H. Patient selection and timing of operation. In: McMinn D, editor. Modern hip resurfacing: Springer-Verlag London limited; 2009.

11. Jacobs JJ, Skipor AK, Doorn PF, Campbell P, Schmalzried TP, Black J, et al. Cobalt and chromium concentrations in patients with metal on metal total hip replacements. Clin Orthop Relat Res 1996;329(Suppl):S256-63.

12. Ziaee H, Daniel J, Datta AK, Blunt S, McMinn DJ. Transplacental transfer of cobalt and chromium in patients with metal-on-metal hip arthroplasty: a controlled study. J Bone Joint Surg Br 2007;89(3):301-5.

13. McBryde CW, Theivendran K, Thomas AM, Treacy RB, Pynsent PB. The influence of head size and sex on the outcome of Birmingham hip resurfacing. J Bone Joint Surg Am 2010;92(1): 105-12.

14. Shimmin AJ, Back D. Femoral neck fractures following Birmingham hip resurfacing: a national review of 50 cases. J Bone Joint Surg Br 2005;87(4):463-4.

15. Anglin C, Masri BA, Tonetti J, Hodgson AJ, Greidanus NV. Hip resurfacing femoral neck fracture influenced by valgus placement. Clin Orthop Relat Res 2007;465:71-9.

16. Buergi ML, Walter WL. Hip resurfacing arthroplasty: the Australian experience. J Arthroplasty 2007;22(7 Suppl 3):61-5.

17. Olsen M, Gamble P, Chiu M, Tumia N, Boyle RA, Schemitsch EH. Assessment of accuracy and reliability in preoperative templating for hip resurfacing arthroplasty. J Arthroplasty 2010;25(3):445-9.

18. Choi JK, Geller JA, Wang W, Nyce JD, Macaulay W. The accuracy and reliability of preoperative templating for metal-on-metal hip resurfacing. J Arthroplasty 2010.

19. McMinn D. Templating for the Birmingham hip resurfacing from conventional X-rays. In: McMinn D, editor. Modern hip resurfacing: Springer-Verlag London limited; 2009.

20. Geller JA, Kukkar N, Fink LA, Macaulay W. Avoiding early complications after metal-on-metal hip resurfacing: The technical and conceptual aspects of “Bailing-Out” to total hip arthroplasty. Operative Techniques in Orthopaedics 19(3):169-75.

21. Slover J, Wetter E, Malchau H. Computer templating of hip resurfacing arthroplasty. In: McMinn D, editor. Modern hip resurfacing: Springer-Verlag London limited; 2009.

22. Pellicci PM, Bostrom M, Poss R. Posterior approach to total hip replacement using enhanced posterior soft tissue repair. Clin Orthop Relat Res 1998;355:224-8.

23. Hurd JL, Potter HG, Dua V, Ranawat CS. Sciatic nerve palsy after primary total hip arthroplasty: a new perspective. J Arthroplasty 2006;21(6):796-802.

24. McMahon SJ, Young D, Ballok Z, Badaruddin BS, Larbpaiboonpong V, Hawdon G. Vascularity of the femoral head after Birmingham hip resurfacing. A technetium Tc 99m bone scan/single photon emission computed tomography study. J Arthroplasty 2006;21(4):514-2