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Standard trochanteric osteotomy
Standard Trochanteric Osteotomy William P. Barrett, MD Osteotomy of the greater trochanter allows wide exposure of the hip joint for primary and revision total hip arthroplasty. The indications for use of a standard trochanteric osteotomy have decreased significantly over the last two decades. The procedure can be performed with a single plane or biplane Chevron type osteotomy. Reattachment of the trochanteric fragment can be accomplished with monofilament multiwire techniques or with a multifilament wire and grip device. Nonunion rates range from 1 to 25% with most large series reporting a 2 to 5% nonunion rate. Complications of trochanteric osteotomy include nonunion, malunion, painful hardware, and persistent limp. Semin Arthro 15:108-112 © 2004 Elsevier Inc. All rights reserved.
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steotomy of the greater trochanter allows wide exposure of the hip joint for primary and revision total hip arthroplasty. The transtrochanteric approach to the hip was initially regarded as the gold standard of surgical exposures. By allowing wide access to the acetabulum and femur, it has been useful in both primary and revision situations. However, with the evolution and refinement of surgical techniques, use of less invasive exposures, and attention to soft tissue handling, use of the trochanteric osteotomy has diminished substantially. In this article, we will review the indications for trochanteric osteotomy, contraindications, surgical technique, reattachment techniques, results of various series, and complications associated with use of the trochanteric osteotomy.
Indications and Contraindications Rarely is the transtrochanteric approach to the hip indicated in routine total hip arthroplasty performed in the 21st century. However, in cases of difficult primary total hips, such as those associated with developmental dysplasia, severe protrusio, previous peritrochanteric fracture with associated deformity and/or malunion, take-down of a previous hip fusion, severe heterotopic ossification associated with prior hip surgery, specifically previous ORIF of acetabular fractures, and in cases of significant congenital varus deformity to adjust soft tissue tension, trochanteric osteotomy can be extremely useful. In revision total hip arthroplasty, a variety of osteotomy techniques have been utilized for exposure of the
Private Practice, Renton, WA, USA. Address reprint requests to William P. Barrett, MD, 4011 Talbot Rd S, Suite 300, Renton, WA 98055.
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1045-4527/04/$-see front matter © 2004 Elsevier Inc. All rights reserved. doi:10.1053/j.sart.2004.08.010
femur and acetabulum. These have been discussed in previous chapters. The standard trochanteric osteotomy can be used in cases in which there is an overhanging greater trochanter blocking implant and/or proximal cement removal. In cases of difficult acetabular revision, where extensive structural allografting is required and/or a pelvic cage will be placed, trochanteric osteotomy allows better exposure of the ilium for fixation of the proximal screws. Intrapelvic migration of a loose acetabular component often necessitates a combined approach, both retroperineal and transtrochanteric for exposure, grafting, and fixation of the associated implants. Recurrent dislocation with increased soft tissue laxity can be dealt with by trochanteric osteotomy and tightening of the abductor mechanism, if implant position is acceptable.1 In any case in which there is difficulty exposing the hip joint, it is prudent to perform an osteotomy to protect the abductor musculature and prevent fracture of the greater trochanter and/or femoral shaft. Contraindications to standard trochanteric osteotomy include severe osteolysis associated with wear and an inadequate bony bed for reattachment of the trochanteric fragment. In cases in which advancement of the trochanter more than 1 cm is anticipated, it should be realized that the risk of nonunion increases once the trochanter is displaced more than 1 cm distal to its original bed.2
Surgical Technique The patient is placed in the lateral decubitus position and securely fixed to the operating room table. A lateral approach to the hip is performed, centered over the greater trochanter. The skin and subcutaneous tissue are divided. The facia lata is split in line with the incision, and a Charnley retractor is placed to retract the anterior and posterior
Standard trochanteric osteotomy soft tissue sleeve. The greater trochanter and the vastus lateralis ridge are identified. The vastus lateralis tendon is divided transversely 1 cm distal to its origin on the vastus ridge of the proximal femur. The muscle is retracted distally by subperiosteal elevation exposing the lateral flare of the vastus ridge from posterior to anterior. The posterior margin of the gluteus medius muscle is identified posteriorly. This is relatively simple, retracting it from a posterior-to-anterior direction, separating it from the underlying piriformis tendon and hip capsule. Anteriorly, it is separated from the tensor fascia lata, again by gentle blunt dissection. Once the gluteus medius and underlying minimus have been bluntly elevated off the capsule, the surgeon’s finger can be passed from posterior to anterior, or a small clamp can likewise be passed, to determine the exit level of the osteotomy just medial to the attachment of the gluteus medius and minimus tendon. Distally the osteotomy will exit at the vastus ridge, just distal to the origin of the vastus lateralis. The osteotomy fragment should be approximately 3-4 cm in length and angled 30 to 50 degrees off the horizontal. The osteotomy can be performed using a number of instruments including an oscillating saw from posterior to anterior or from distal to proximal. An osteotome likewise from posterior to anterior or from distal to proximal, or a Gigli saw that is passed superiorly over the greater trochanteric fragment just deep to the gluteus minimus and medius tendon and exiting distally at the vastus lateralis ridge. The type of osteotomy performed is based on the surgeon’s preference. These can include a single plane straight osteotomy angled 30 to 50° to the horizontal versus a biplane or “Chevron” osteotomy with an anterior and posterior vertical segment (Fig.1). The biplane or Chevron osteotomy has the benefit of rotational resistance and more accurate apposition of the fragments at the conclusion of the procedure. The biplane osteotomy has been associated with a lower nonunion rate.3,4 It can be performed either with an oscillating saw or wide osteotomes. With either type of osteotomy, it is important to maintain adequate thickness of the trochanteric fragment, so it can accept appropriate fixation devices. With the Chevron osteotomy, care must be taken not to make the apex of the cut too lateral and run the risk of a stress riser causing a vertical split of the trochanteric fragment. Once the osteotomy has been performed, the trochanteric fragment along with its abductor musculature can be reflected proximally, elevating the gluteus medius and minimus off the capsule, which is quite easy in a primary situation, more difficult in the case of a revision with scarring of the underlying soft tissue to the deep surface of the abductors. In either case, the anterior and posterior margins of the abductors are identified and elevated proximally. Care is taken not to put undue stretch on the superior gluteal nerve. The abductor musculature can be retracted proximally with right angle retractors, held in place either with a trochanteric clamp or smooth Steinmann pins fixed into the ilium. The gluteus medius and minimus are innervated by the superior gluteal nerve, which receives branches from L5 and S1. The neurovascular bundle enters the posterior hip region through the sciatic notch proximal to the
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Figure 1 (A) Chevron osteotomy, performed with osteotome. (B) The biplane osteotomy provides rotational stability with reapposition of the osteotomy fragment. Reprinted with permission from Callaghan JJ, Rosenberg AG, Rubash HE (eds.): The Adult Hip. © 1998 by Lippincott Williams & Wilkins.
piriformis muscle. Reflecting the abductors proximally with trochanteric osteotomy does not put these neurovascular structures at risk, unless undue retraction posteriorly near the sciatic notch is performed.5,6
Fixation Techniques There are multiple options for fixation of the greater trochanteric fragment to the proximal femur. These include smooth wire, braided cables, cables associated with some type of grip or clamp, and plates plus wires. All methods of fixation attempt to counter the forces that act across the trochanteric fragment. These include the pull of the gluteus medius and minimus with the leg in extension, which tends to displace the fragment proximally in the vertical plane. However, when the hip and knee are flexed, the pull of these muscles is more prominent in the anterior–posterior plane, creating a rotational force on the trochanteric fragment.7,8 It is important for any fixation system to resist these vertical and anterior–posterior forces while maintaining compression across the osteotomy fragment to promote healing. Trochanteric union will be influenced by the surface area of the osteotomized fragments, the vascular supply, which is derived from the soft tissue attachments to the fragment, and lastly the bone quality. For timely healing to occur, the bone fragments
W.P. Barrett
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Figure 2 (A-D) The four-wire technique using two vertical wires to resist proximal displacement and two horizontal wires to resist anterior–posterior displacement. The transverse wires can be placed through and below the lesser trochanter. Reprinted with permission from Callaghan JJ, Rosenberg AG, Rubash HE (eds.): The Adult Hip. © 1998 by Lippincott Williams & Wilkins.
wire and the metal of the implant. Transverse wire (or wires) can be passed through the lateral cortical bone in a primary osteotomy. In a revision setting, more likely than not, the transverse wires will be placed either inferior to or through the lesser trochanter and then tied over the top of the trochanteric fragment. The vertical wires can be tightened initially to secure the proximal– distal location of the fragment. The transverse wires can then be tightened, locking the vertical wires in place. A variety of techniques incorporating the transverse and vertical wires with square knots have been described by many authors.9,10 The operative leg can be placed on a sterile Mayo stand to adjust abduction and rotation to ease reattachment of the fragment. Once fixation has been achieved, the hip should be placed through a range of motion to check the stability of the fixation. Multifilament cable systems have mechanical properties that are far superior to monofilament wire. Cobalt chrome cables have better resistance to fatigue and a higher yield and breaking strength than monofilament wire.12-14 These are combined with a trochanteric grip or a cable sleeve. The transverse wires are placed through the trochanteric grip. Tension is applied via tensioning devices, and the grip can be crimped onto the wire, maintaining tension. The amount of compression across the osteotomy fragment can be adjusted via the tensioning devices. Despite the fact that multifilament cable systems are stronger than monofilament wire, breakage does occur and is often associated with third-body generation from the frayed wire pieces.15,16 A variety of cable/grip systems is available from orthopedic implant companies. Other devices available for fixation include a bolt assembly, which can attach through the femoral component of revision total hip stems, and plates used in combination with screws and/or wires.
Results need to be in continuity and compressed. That is the goal of any fixation technique. As previously mentioned, the Chevron osteotomy provides rotational stability by nature of its geometry. The most commonly used fixation device is monofilament wire (16-18 gauge). The wire can be stainless steel or cobalt chrome. While the cobalt chrome wire has increased yield strength, it is less ductile and is more prone to breakage with tightening versus stainless steel wire. There are a variety of techniques for reattachment of the trochanter, using monofilament wire.9-11 These include two-wire technique, threewire technique, and four-wire technique (Fig. 2). The most commonly used and reliable techniques involve two vertical and one or two transverse wires. The vertical wires resist proximal migration, while the transverse wire(s) resists AP and rotational forces. Nonunion rates can range from 1 to 25%. Monofilmanent wire can be attached using either a square knot or a twist technique. The vertical wires are placed through either one or two drill holes 1 cm apart, 5-10 mm distal to the cut surface of the lateral femur, depending on how much advancement of the trochanter is desired (Fig. 2). These are brought out through the medullary canal in revision cases. In primary cases, they may exit through the anterior and posterior cortical bone to avoid contact between the
Evaluating the results for fixation of trochanteric osteotomies is difficult secondary to the numerous variables involved in the use of this procedure. These include a varied patient population, comparison of primary and revision procedures, varied postop protocols, and whether significant functional limitation was recorded. The most obvious endpoint for a satisfactory outcome is bony union of the trochanter. As mentioned previously, this ranges from 1 to 25%.9,10 In vitro testing of various monofilament wire configurations has consistently revealed three-wire and four-wire techniques to displace the least when subjected to repeated loading.8 The type of osteotomy, flat versus Chevron, also influences the outcome of union. Weber4 reported on a comparative group of 138 patients; 69 had a conventional flat osteotomy and 69 had a biplane osteotomy. The pseudoarthrosis rate was 11% in the conventional flat osteotomy group and 1.5% in the biplane osteotomy group. Berry and Müller3 reported on 53 primary total hip arthroplasties and 74 revisions utilizing a Chevron technique with trochanteric union rates of 98 and 97%, respectively. Wroblewski and Shelley11 reported a 98% union rate in 222 arthroplasties using the Chevron osteotomy technique. Jensen and Harris10 reported on 804 patients, the majority of which were primary total hip arthro-
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plasties using a three-wire technique. The ultimate union rate was 99%, though 28% of their patients had wire breakage. Dall and Miles12 reported on a group of 130 patients using 2.0 mm cable with the cable-grip system and noted a union rate of 98% and incidence of cable breakage of 3%. However, other authors have reported significantly higher failure rates using the cable-grip system. Ritter et al.17 noted a nonunion rate of 38% and cable breakage rate of 33% using the cablegrip system. Kelley and Johnston16 reported a review of 322 trochanteric osteotomies: 162 were repaired with stainless stell monofilament wire and 160 with 1.5 mm cobalt-chrome cables. Trochanteric nonunion was 25% in the wire group and 21% in the cable group.
Complications Primary complications of trochanteric osteotomy and subsequent reattachment include irritation secondary to the fixation hardware, nonunion of the fragment, malunion of the fragments, and persistent functional limitations including limp and postoperative hip instability.18 The most worrisome complication following trochanteric osteotomy is nonunion. This can result in persistent pain, limp, and dislocation. Woo and Morrey19 in a review of 10,500 total hip arthroplasties noted a nonunion rate of 1.85%, but dislocations occurred only in those patients whose trochanter migrated proximally more than 2 cm. They concluded that migration of the trochanter further than 2 cm associated with trochanteric nonunion increased the rate of dislocation following total hip arthroplasty. It is difficult to accurately measure the degree of functional loss with trochanteric nonunion, but most series report little impairment if the trochanter is stable and has migrated less than 1 cm.19 An unstable greater trochanter and/or migration greater than 2 cm does produce functional loss with abductor weakness and associated limp. Correction of a trochanteric nonunion requires analysis of the reasons for nonunion. If it were due to inadequate fixation initially, this can be dealt with by improved fixation techniques. If excess distal transfer with associated increased soft tissue tension results in nonunion, reattaching the trochanter to a slightly more proximal location is appropriate. If an inadequate bony bed were present, autogenous bone grafting to the area with adequate fixation can increase in the rate of union. If abduction of the leg were required for appropriate apposition of the fragment, then placement in an abduction orthosis versus single-leg spica cast would be helpful to enhance the rate of union following a revision procedure. Pain associated with prominent hardware can often be dealt with by removing the hardware. Preoperatively diagnostic injections with an anesthetic agent can be useful to determine whether the hardware were, in fact, the etiology of the pain versus a painful prosthesis. Once it is determined that the prominent hardware is causing the lateral hip discomfort, removal of the hardware is appropriate. Migration of broken hardware has been reported and seen with a much higher frequency with multifilament cables.15,17 In the cable-grip system, motion of the trochanteric fragment can lead to a sawing affect of the cable on the grip, leading to
Figure 3 X-ray of trochanteric nonunion with breakage of multifilament cable and migration of wire fragments.
fraying and migration of the broken hardware (Fig. 3). Abrasive third-body wear can lead to premature failure of the bearing surface from third-body wear.
Conclusion Though the need for trochanteric osteotomy has decreased significantly over the last two decades, there are situations described in this paper in which osteotomy of the trochanter is necessary. The type of osteotomy required and the amount of exposure necessary are based on surgeon preference and the unique circumstances presented by each case. Once the decision has been made and the osteotomy performed, the procedure is completed. Stable reattachment and union of the osteotomy then become of paramount importance. As noted in this chapter, stable fixation with compression across the osteotomy site can be accomplished with monofilament wire using either a three- or four-wire technique, as described. Satisfactory results with a cable-grip system have also been obtained. The surgeon must weigh the better mechanical properties offered by the cable-grip system with the potential for third-body wear in the event of fraying and breakage of these cables. Being familiar with both types of fixation will allow the surgeon to choose the appropriate technique based on the unique factors in each case.
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References 1. Kaplan SJ, Thomas WH, Poss R: Trochanteric advancement for recurrent dislocation after total hip arthroplasty. J Arthroplasty 2:119-124, 1987 2. Gottschalk FA, Morein G., Weber F: Effect of the position of the greater trochanter on the rate of union after trochanteric osteotomy for total hip arthroplasty. J Arthroplasty 3:235-240, 1988 3. Berry DJ, Müller ME: Chevron osteotomy and single wire reattachment of the greater trochanter in primary and revision total hip arthroplasty. Clin Orthop 294:155-161, 1993 4. Weber BG: Osteotomy of the greater trochanter total hip replacement. Conventional versus dihedral technique. Orthopäde 18:540-544, 1989 5. Jacobs LGH, Buxton RA: The course of the superior gluteal nerve in the lateral approach to the hip. J Bone Joint Surg 71A:1235, 1989 6. Fulkerson JP, Crelin ES, Keggi KJ: Anatomy and osteotomy of the greater trochanter. Arch Surg 114:19-21, 1979 7. Charnley J: The long-term results of low-friction arthroplasty of the hip performed as a primary intervention. J Bone Joint Surg 54B:61-76, 1972 8. Markoff KL, Hirschowitz DL, Amstutz HC: Mechanical instability of the greater trochanter following osteotomy and reattachment by wiring. Clin Orthop 141:111-121, 1979 9. Amstutz HC, Mai LL: Results of interlocking wire trochanteric reattachment and technique refinements to prevent complications following total hip arthroplasty. Clin Orthop 183:82, 1983
W.P. Barrett 10. Jensen NF, Harris WH: A system for trochanteric osteotomy and reattachment for total hip arthroplasty with a ninety-nine percent union rate. Clin Orthop 208:174-181, 1986 11. Wroblewski BM, Shelley P: Reattachment of the greater trochanter after hip replacement. J Bone Joint Surg 67B:736-740, 1985 12. Dall DM, Miles AW: Re-attachment of the greater trochanter: The use of the trochanter cable-grip system. J Bone Joint Surg 65B:55-59, 1983 13. Hersh CK, Williams RP, Trick LW, et al: Comparison of the mechanical performance of trochanteric fixation devices. Clin Orthop 329:317325, 1996 14. Turner RH, McCarthy JC, Kremchek T, et al: Reattachment of the greater trochanter after total hip replacement: Using the Dall-Miles cable-grip system. Presented at the Ninth Combined Meeting of the Orthopaedic Associations of the English Speaking World, Toronto, Canada, June 1992. 15. Bauer TW, Ming J, D’Antonio JA, et al: Abrasive three-body wear of polyethylene caused by broken multifilament cables of a total hip prosthesis: A report of three cases. J Bone Joint Surg 78A:1244-1247, 1996 16. Kelley S, Johnston RC: Debris from cobalt-chrome cable may cause acetabular loosening. Clin Orthop 285:140-146, 1992. 17. Ritter MA, Eizember LE, Keating EM, et al: Trochanteric fixation by cable grip in hip replacement. J Bone Joint Surg 73B:580-581, 1991 18. Glassman AH: Complications of trochanteric osteotomy. Orthop Clin North Am 23:321-333, 1992 19. Woo RYG, Morrey BF: Dislocation of THA. J Bone Joint Surg 64A:12951306, 1992
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steotomy of the greater trochanter allows wide exposure of the hip joint for primary and revision total hip arthroplasty. The transtrochanteric approach to the hip was initially regarded as the gold standard of surgical exposures. By allowing wide access to the acetabulum and femur, it has been useful in both primary and revision situations. However, with the evolution and refinement of surgical techniques, use of less invasive exposures, and attention to soft tissue handling, use of the trochanteric osteotomy has diminished substantially. In this article, we will review the indications for trochanteric osteotomy, contraindications, surgical technique, reattachment techniques, results of various series, and complications associated with use of the trochanteric osteotomy.
Indications and Contraindications Rarely is the transtrochanteric approach to the hip indicated in routine total hip arthroplasty performed in the 21st century. However, in cases of difficult primary total hips, such as those associated with developmental dysplasia, severe protrusio, previous peritrochanteric fracture with associated deformity and/or malunion, take-down of a previous hip fusion, severe heterotopic ossification associated with prior hip surgery, specifically previous ORIF of acetabular fractures, and in cases of significant congenital varus deformity to adjust soft tissue tension, trochanteric osteotomy can be extremely useful. In revision total hip arthroplasty, a variety of osteotomy techniques have been utilized for exposure of the
Private Practice, Renton, WA, USA. Address reprint requests to William P. Barrett, MD, 4011 Talbot Rd S, Suite 300, Renton, WA 98055.
108
1045-4527/04/$-see front matter © 2004 Elsevier Inc. All rights reserved. doi:10.1053/j.sart.2004.08.010
femur and acetabulum. These have been discussed in previous chapters. The standard trochanteric osteotomy can be used in cases in which there is an overhanging greater trochanter blocking implant and/or proximal cement removal. In cases of difficult acetabular revision, where extensive structural allografting is required and/or a pelvic cage will be placed, trochanteric osteotomy allows better exposure of the ilium for fixation of the proximal screws. Intrapelvic migration of a loose acetabular component often necessitates a combined approach, both retroperineal and transtrochanteric for exposure, grafting, and fixation of the associated implants. Recurrent dislocation with increased soft tissue laxity can be dealt with by trochanteric osteotomy and tightening of the abductor mechanism, if implant position is acceptable.1 In any case in which there is difficulty exposing the hip joint, it is prudent to perform an osteotomy to protect the abductor musculature and prevent fracture of the greater trochanter and/or femoral shaft. Contraindications to standard trochanteric osteotomy include severe osteolysis associated with wear and an inadequate bony bed for reattachment of the trochanteric fragment. In cases in which advancement of the trochanter more than 1 cm is anticipated, it should be realized that the risk of nonunion increases once the trochanter is displaced more than 1 cm distal to its original bed.2
Surgical Technique The patient is placed in the lateral decubitus position and securely fixed to the operating room table. A lateral approach to the hip is performed, centered over the greater trochanter. The skin and subcutaneous tissue are divided. The facia lata is split in line with the incision, and a Charnley retractor is placed to retract the anterior and posterior
Standard trochanteric osteotomy soft tissue sleeve. The greater trochanter and the vastus lateralis ridge are identified. The vastus lateralis tendon is divided transversely 1 cm distal to its origin on the vastus ridge of the proximal femur. The muscle is retracted distally by subperiosteal elevation exposing the lateral flare of the vastus ridge from posterior to anterior. The posterior margin of the gluteus medius muscle is identified posteriorly. This is relatively simple, retracting it from a posterior-to-anterior direction, separating it from the underlying piriformis tendon and hip capsule. Anteriorly, it is separated from the tensor fascia lata, again by gentle blunt dissection. Once the gluteus medius and underlying minimus have been bluntly elevated off the capsule, the surgeon’s finger can be passed from posterior to anterior, or a small clamp can likewise be passed, to determine the exit level of the osteotomy just medial to the attachment of the gluteus medius and minimus tendon. Distally the osteotomy will exit at the vastus ridge, just distal to the origin of the vastus lateralis. The osteotomy fragment should be approximately 3-4 cm in length and angled 30 to 50 degrees off the horizontal. The osteotomy can be performed using a number of instruments including an oscillating saw from posterior to anterior or from distal to proximal. An osteotome likewise from posterior to anterior or from distal to proximal, or a Gigli saw that is passed superiorly over the greater trochanteric fragment just deep to the gluteus minimus and medius tendon and exiting distally at the vastus lateralis ridge. The type of osteotomy performed is based on the surgeon’s preference. These can include a single plane straight osteotomy angled 30 to 50° to the horizontal versus a biplane or “Chevron” osteotomy with an anterior and posterior vertical segment (Fig.1). The biplane or Chevron osteotomy has the benefit of rotational resistance and more accurate apposition of the fragments at the conclusion of the procedure. The biplane osteotomy has been associated with a lower nonunion rate.3,4 It can be performed either with an oscillating saw or wide osteotomes. With either type of osteotomy, it is important to maintain adequate thickness of the trochanteric fragment, so it can accept appropriate fixation devices. With the Chevron osteotomy, care must be taken not to make the apex of the cut too lateral and run the risk of a stress riser causing a vertical split of the trochanteric fragment. Once the osteotomy has been performed, the trochanteric fragment along with its abductor musculature can be reflected proximally, elevating the gluteus medius and minimus off the capsule, which is quite easy in a primary situation, more difficult in the case of a revision with scarring of the underlying soft tissue to the deep surface of the abductors. In either case, the anterior and posterior margins of the abductors are identified and elevated proximally. Care is taken not to put undue stretch on the superior gluteal nerve. The abductor musculature can be retracted proximally with right angle retractors, held in place either with a trochanteric clamp or smooth Steinmann pins fixed into the ilium. The gluteus medius and minimus are innervated by the superior gluteal nerve, which receives branches from L5 and S1. The neurovascular bundle enters the posterior hip region through the sciatic notch proximal to the
109
Figure 1 (A) Chevron osteotomy, performed with osteotome. (B) The biplane osteotomy provides rotational stability with reapposition of the osteotomy fragment. Reprinted with permission from Callaghan JJ, Rosenberg AG, Rubash HE (eds.): The Adult Hip. © 1998 by Lippincott Williams & Wilkins.
piriformis muscle. Reflecting the abductors proximally with trochanteric osteotomy does not put these neurovascular structures at risk, unless undue retraction posteriorly near the sciatic notch is performed.5,6
Fixation Techniques There are multiple options for fixation of the greater trochanteric fragment to the proximal femur. These include smooth wire, braided cables, cables associated with some type of grip or clamp, and plates plus wires. All methods of fixation attempt to counter the forces that act across the trochanteric fragment. These include the pull of the gluteus medius and minimus with the leg in extension, which tends to displace the fragment proximally in the vertical plane. However, when the hip and knee are flexed, the pull of these muscles is more prominent in the anterior–posterior plane, creating a rotational force on the trochanteric fragment.7,8 It is important for any fixation system to resist these vertical and anterior–posterior forces while maintaining compression across the osteotomy fragment to promote healing. Trochanteric union will be influenced by the surface area of the osteotomized fragments, the vascular supply, which is derived from the soft tissue attachments to the fragment, and lastly the bone quality. For timely healing to occur, the bone fragments
W.P. Barrett
110
Figure 2 (A-D) The four-wire technique using two vertical wires to resist proximal displacement and two horizontal wires to resist anterior–posterior displacement. The transverse wires can be placed through and below the lesser trochanter. Reprinted with permission from Callaghan JJ, Rosenberg AG, Rubash HE (eds.): The Adult Hip. © 1998 by Lippincott Williams & Wilkins.
wire and the metal of the implant. Transverse wire (or wires) can be passed through the lateral cortical bone in a primary osteotomy. In a revision setting, more likely than not, the transverse wires will be placed either inferior to or through the lesser trochanter and then tied over the top of the trochanteric fragment. The vertical wires can be tightened initially to secure the proximal– distal location of the fragment. The transverse wires can then be tightened, locking the vertical wires in place. A variety of techniques incorporating the transverse and vertical wires with square knots have been described by many authors.9,10 The operative leg can be placed on a sterile Mayo stand to adjust abduction and rotation to ease reattachment of the fragment. Once fixation has been achieved, the hip should be placed through a range of motion to check the stability of the fixation. Multifilament cable systems have mechanical properties that are far superior to monofilament wire. Cobalt chrome cables have better resistance to fatigue and a higher yield and breaking strength than monofilament wire.12-14 These are combined with a trochanteric grip or a cable sleeve. The transverse wires are placed through the trochanteric grip. Tension is applied via tensioning devices, and the grip can be crimped onto the wire, maintaining tension. The amount of compression across the osteotomy fragment can be adjusted via the tensioning devices. Despite the fact that multifilament cable systems are stronger than monofilament wire, breakage does occur and is often associated with third-body generation from the frayed wire pieces.15,16 A variety of cable/grip systems is available from orthopedic implant companies. Other devices available for fixation include a bolt assembly, which can attach through the femoral component of revision total hip stems, and plates used in combination with screws and/or wires.
Results need to be in continuity and compressed. That is the goal of any fixation technique. As previously mentioned, the Chevron osteotomy provides rotational stability by nature of its geometry. The most commonly used fixation device is monofilament wire (16-18 gauge). The wire can be stainless steel or cobalt chrome. While the cobalt chrome wire has increased yield strength, it is less ductile and is more prone to breakage with tightening versus stainless steel wire. There are a variety of techniques for reattachment of the trochanter, using monofilament wire.9-11 These include two-wire technique, threewire technique, and four-wire technique (Fig. 2). The most commonly used and reliable techniques involve two vertical and one or two transverse wires. The vertical wires resist proximal migration, while the transverse wire(s) resists AP and rotational forces. Nonunion rates can range from 1 to 25%. Monofilmanent wire can be attached using either a square knot or a twist technique. The vertical wires are placed through either one or two drill holes 1 cm apart, 5-10 mm distal to the cut surface of the lateral femur, depending on how much advancement of the trochanter is desired (Fig. 2). These are brought out through the medullary canal in revision cases. In primary cases, they may exit through the anterior and posterior cortical bone to avoid contact between the
Evaluating the results for fixation of trochanteric osteotomies is difficult secondary to the numerous variables involved in the use of this procedure. These include a varied patient population, comparison of primary and revision procedures, varied postop protocols, and whether significant functional limitation was recorded. The most obvious endpoint for a satisfactory outcome is bony union of the trochanter. As mentioned previously, this ranges from 1 to 25%.9,10 In vitro testing of various monofilament wire configurations has consistently revealed three-wire and four-wire techniques to displace the least when subjected to repeated loading.8 The type of osteotomy, flat versus Chevron, also influences the outcome of union. Weber4 reported on a comparative group of 138 patients; 69 had a conventional flat osteotomy and 69 had a biplane osteotomy. The pseudoarthrosis rate was 11% in the conventional flat osteotomy group and 1.5% in the biplane osteotomy group. Berry and Müller3 reported on 53 primary total hip arthroplasties and 74 revisions utilizing a Chevron technique with trochanteric union rates of 98 and 97%, respectively. Wroblewski and Shelley11 reported a 98% union rate in 222 arthroplasties using the Chevron osteotomy technique. Jensen and Harris10 reported on 804 patients, the majority of which were primary total hip arthro-
Standard trochanteric osteotomy
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plasties using a three-wire technique. The ultimate union rate was 99%, though 28% of their patients had wire breakage. Dall and Miles12 reported on a group of 130 patients using 2.0 mm cable with the cable-grip system and noted a union rate of 98% and incidence of cable breakage of 3%. However, other authors have reported significantly higher failure rates using the cable-grip system. Ritter et al.17 noted a nonunion rate of 38% and cable breakage rate of 33% using the cablegrip system. Kelley and Johnston16 reported a review of 322 trochanteric osteotomies: 162 were repaired with stainless stell monofilament wire and 160 with 1.5 mm cobalt-chrome cables. Trochanteric nonunion was 25% in the wire group and 21% in the cable group.
Complications Primary complications of trochanteric osteotomy and subsequent reattachment include irritation secondary to the fixation hardware, nonunion of the fragment, malunion of the fragments, and persistent functional limitations including limp and postoperative hip instability.18 The most worrisome complication following trochanteric osteotomy is nonunion. This can result in persistent pain, limp, and dislocation. Woo and Morrey19 in a review of 10,500 total hip arthroplasties noted a nonunion rate of 1.85%, but dislocations occurred only in those patients whose trochanter migrated proximally more than 2 cm. They concluded that migration of the trochanter further than 2 cm associated with trochanteric nonunion increased the rate of dislocation following total hip arthroplasty. It is difficult to accurately measure the degree of functional loss with trochanteric nonunion, but most series report little impairment if the trochanter is stable and has migrated less than 1 cm.19 An unstable greater trochanter and/or migration greater than 2 cm does produce functional loss with abductor weakness and associated limp. Correction of a trochanteric nonunion requires analysis of the reasons for nonunion. If it were due to inadequate fixation initially, this can be dealt with by improved fixation techniques. If excess distal transfer with associated increased soft tissue tension results in nonunion, reattaching the trochanter to a slightly more proximal location is appropriate. If an inadequate bony bed were present, autogenous bone grafting to the area with adequate fixation can increase in the rate of union. If abduction of the leg were required for appropriate apposition of the fragment, then placement in an abduction orthosis versus single-leg spica cast would be helpful to enhance the rate of union following a revision procedure. Pain associated with prominent hardware can often be dealt with by removing the hardware. Preoperatively diagnostic injections with an anesthetic agent can be useful to determine whether the hardware were, in fact, the etiology of the pain versus a painful prosthesis. Once it is determined that the prominent hardware is causing the lateral hip discomfort, removal of the hardware is appropriate. Migration of broken hardware has been reported and seen with a much higher frequency with multifilament cables.15,17 In the cable-grip system, motion of the trochanteric fragment can lead to a sawing affect of the cable on the grip, leading to
Figure 3 X-ray of trochanteric nonunion with breakage of multifilament cable and migration of wire fragments.
fraying and migration of the broken hardware (Fig. 3). Abrasive third-body wear can lead to premature failure of the bearing surface from third-body wear.
Conclusion Though the need for trochanteric osteotomy has decreased significantly over the last two decades, there are situations described in this paper in which osteotomy of the trochanter is necessary. The type of osteotomy required and the amount of exposure necessary are based on surgeon preference and the unique circumstances presented by each case. Once the decision has been made and the osteotomy performed, the procedure is completed. Stable reattachment and union of the osteotomy then become of paramount importance. As noted in this chapter, stable fixation with compression across the osteotomy site can be accomplished with monofilament wire using either a three- or four-wire technique, as described. Satisfactory results with a cable-grip system have also been obtained. The surgeon must weigh the better mechanical properties offered by the cable-grip system with the potential for third-body wear in the event of fraying and breakage of these cables. Being familiar with both types of fixation will allow the surgeon to choose the appropriate technique based on the unique factors in each case.
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References 1. Kaplan SJ, Thomas WH, Poss R: Trochanteric advancement for recurrent dislocation after total hip arthroplasty. J Arthroplasty 2:119-124, 1987 2. Gottschalk FA, Morein G., Weber F: Effect of the position of the greater trochanter on the rate of union after trochanteric osteotomy for total hip arthroplasty. J Arthroplasty 3:235-240, 1988 3. Berry DJ, Müller ME: Chevron osteotomy and single wire reattachment of the greater trochanter in primary and revision total hip arthroplasty. Clin Orthop 294:155-161, 1993 4. Weber BG: Osteotomy of the greater trochanter total hip replacement. Conventional versus dihedral technique. Orthopäde 18:540-544, 1989 5. Jacobs LGH, Buxton RA: The course of the superior gluteal nerve in the lateral approach to the hip. J Bone Joint Surg 71A:1235, 1989 6. Fulkerson JP, Crelin ES, Keggi KJ: Anatomy and osteotomy of the greater trochanter. Arch Surg 114:19-21, 1979 7. Charnley J: The long-term results of low-friction arthroplasty of the hip performed as a primary intervention. J Bone Joint Surg 54B:61-76, 1972 8. Markoff KL, Hirschowitz DL, Amstutz HC: Mechanical instability of the greater trochanter following osteotomy and reattachment by wiring. Clin Orthop 141:111-121, 1979 9. Amstutz HC, Mai LL: Results of interlocking wire trochanteric reattachment and technique refinements to prevent complications following total hip arthroplasty. Clin Orthop 183:82, 1983
W.P. Barrett 10. Jensen NF, Harris WH: A system for trochanteric osteotomy and reattachment for total hip arthroplasty with a ninety-nine percent union rate. Clin Orthop 208:174-181, 1986 11. Wroblewski BM, Shelley P: Reattachment of the greater trochanter after hip replacement. J Bone Joint Surg 67B:736-740, 1985 12. Dall DM, Miles AW: Re-attachment of the greater trochanter: The use of the trochanter cable-grip system. J Bone Joint Surg 65B:55-59, 1983 13. Hersh CK, Williams RP, Trick LW, et al: Comparison of the mechanical performance of trochanteric fixation devices. Clin Orthop 329:317325, 1996 14. Turner RH, McCarthy JC, Kremchek T, et al: Reattachment of the greater trochanter after total hip replacement: Using the Dall-Miles cable-grip system. Presented at the Ninth Combined Meeting of the Orthopaedic Associations of the English Speaking World, Toronto, Canada, June 1992. 15. Bauer TW, Ming J, D’Antonio JA, et al: Abrasive three-body wear of polyethylene caused by broken multifilament cables of a total hip prosthesis: A report of three cases. J Bone Joint Surg 78A:1244-1247, 1996 16. Kelley S, Johnston RC: Debris from cobalt-chrome cable may cause acetabular loosening. Clin Orthop 285:140-146, 1992. 17. Ritter MA, Eizember LE, Keating EM, et al: Trochanteric fixation by cable grip in hip replacement. J Bone Joint Surg 73B:580-581, 1991 18. Glassman AH: Complications of trochanteric osteotomy. Orthop Clin North Am 23:321-333, 1992 19. Woo RYG, Morrey BF: Dislocation of THA. J Bone Joint Surg 64A:12951306, 1992