Extended Trochanteric Osteotomy Followed by Cemented Impaction Allografting in Revision Hip Arthroplasty

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1 The Journal of Arthroplasty Vol. 28 No Extended Trochanteric Osteotomy Followed by Cemented Impaction Allografting in Revision Hip Arthroplasty John Charity, MD, MRCS,* Eleftherios Tsiridis, MD, MSc, PhD, FRCS,y David Gusmão, MD,* Adrian Bauze, MBBS, FRACS,z John Timperley, MB, ChB, FRCS (Ed), D Phil (Oxon),* and Graham Gie, MBBS, FRCS (Ed), FRCS Ed (Orth)* Abstract: The aim of this study is to present the medium- to long-term results of all cases of femoral impaction allografting revision at our institution that required an extended trochanteric osteotomy (ETO) at the time of surgery. Eighteen patients with a mean age of 60 years were evaluated. Indication for revision was aseptic loosening in all cases. The mean follow-up was 123 months (51-170). Charnley-D'Aubigné-Postel scores, stem length, ETO length, ETO healing, and complications were recorded. No patient was lost to follow-up. Signs of clinical healing were noted within the first 6 postoperative months. The difference between the preoperative and postoperative clinical scores was statistically significant. No nonunion of the ETO was observed in any case. These results give support to the combined use of these techniques. Keywords: extended trochanteric osteotomy, femoral impaction grafting, hip revision arthroplasty, cement, nonunion Elsevier Inc. All rights reserved. The number of patients who are predicted to require a revision total hip arthroplasty is increasing each year [1]. An extended trochanteric osteotomy (ETO) is a wellestablished surgical technique to facilitate the removal of both cemented and uncemented prostheses [2]. The technique, described by Younger et al [3], provides excellent exposure of the proximal femur by creating an enlarged window with reflection of the proximal lateral femur. Extended trochanteric osteotomy has been shown to be an efficient, safe, and reliable technique that brings the benefits of protecting and preserving bone stock, decreasing operative time and enhancing exposure of the acetabulum [4,5]. The osteotomy also From the *Hip Unit, Princess Elizabeth Orthopaedic Centre, Royal Devon and Exeter Hospital, Barrack Road, Exeter, EX2 5DW, United Kingdom; ydepartment of Surgery and Cancer, Imperial College London, Hammersmith Campus, Du Cane Road, London, W12 0HS, United Kingdom; and zuniversity of Adelaide Department of Orthopaedics and Trauma, Consultant Orthopaedic Surgeon, Sportsmed SA, 32 Payneham Rd, Stepney, 5069, South Australia, Australia. Submitted December 1, 2011; accepted July 1, The Conflict of Interest statement associated with this article can be found at Reprint requests: John Charity, MD, MRCS, Princess Elizabeth Orthopaedic Centre, Royal Devon and Exeter Hospital, Barrack Road, Exeter, EX2 5DW, United Kingdom Elsevier Inc. All rights reserved / $36.00/0 heals predictably when used with extensively porouscoated implants; decreased nonunion rates have been reported compared with previous trochanteric osteotomy techniques [2,3,6-8]. However, concerns have been raised when an ETO is used with cemented implants due to the risk of cement entering between the osteotomy fragments and preventing union. In addition, poor results have been reported by 1 author when an ETO was used in combination with femoral impaction grafting and a cemented implant [9]. We have used the technique of impaction grafting in our practice since its inception in 1987 and have not experienced problems with the combined use of ETO with impacted endosteal allograft. The aim of this study was to document the medium- to long-term results of all femoral revisions at our institution where ETO and impaction grafting were performed jointly. Patients and Methods Between 1996 and 2003, 18 consecutive patients had a revision hip arthroplasty at our institution where an ETO was performed in the presence of femoral bone loss necessitating femoral impaction grafting. There were 13 female and 5 male patients with a mean age of 60 years (range, years). The mean follow-up was 123 months (range, months). No patient was lost to follow-up. 154

2 ETO Followed by Cemented Impaction Allografting Charity et al 155 The indication for revision was aseptic loosening of one or both components in all cases. Seven patients in the series had been submitted to at least 2 previous ipsilateral hip arthroplasty operations. The Paprosky classification [10] was used to assess preoperative femoral bone loss, with 13 hips being graded as Paprosky type IIIB; 2 hips, as type IIIA; and 3 hips, as type IV. The ETO was carried out to facilitate removal of an uncemented stem in 8 hips, removal of a cemented stem in 6 hips, and removal of the cement mantle in 4 hips. The acetabular component was also revised in all cases except 1. The Exeter stem (Stryker Corporation, Mahwah, NJ) was used in every case with a length between 160 and 260 mm. No reinforcement with strut grafts or plates was required in any case. The ETO fragment was fixed with a minimum of 3 multifilament cables and/or cerclage wires. Dall-Miles cables (Stryker Corporation) were used as the preferred method of fixation due to ease of use and resistance to failure, except in the earlier cases before cables became available. The use of cables was also avoided for the most proximal fixation of the fragment that is in contact with the joint, due to the risk of fretting and potential release of metal debris into the joint and interfaces. Clinical outcome scores were recorded preoperatively and postoperatively using the Charnley modification of the Merle d'aubigné-postel classification including involvement of other joints, pain, function, and range of movement [11]. The time until evidence of clinical healing (in months) was also recorded. Complications recorded included any occurrence of nonunion of the ETO, fracture of the greater trochanter, infection, dislocation, and stem loosening. Radiologic analysis included recording the following measurements: length of the ETO measured in millimeters from the tip of the greater trochanter to its transverse distal cut, femoral diameter measured at the distal end of the ETO, length of metalwork bypassing the ETO distally and its ratio to the femoral diameter, stem subsidence within the cement mantle by measuring the height of the radiolucent line at the stem-cement interface in Gruen zone 1 [12] as described by Fowler et al [13], evidence of radiolucencies or graft resorption in all assessable zones of Gruen, and time until evidence of radiologic healing of the ETO in months. Morcellized fresh frozen cancellous allograft bone from our bone bank (femoral heads obtained from primary total hip arthroplasties) was used in every patient, and only in 1 operation a mix of allograft and heterologous bovine bone graft (Cancellous Unilab Surgibone LaSalle International Limited, Littleton, CO) was used. No irradiated or pasteurized bone was used in these cases. Impaction grafting was performed according to the technique previously described in detail [14-16] following fixation of the ETO. Statistical Analysis Because data were not normally distributed the preoperative and postoperative scores were compared using Wilcoxon signed rank test for nonparametric paired data. Level of significance was set at 5% that was adjusted for multiple testing using Bonferroni method. Scores are presented as means and ranges. The SPSS version 18.0 for Windows (SPSS, Inc, Chicago, Ill) was used in the analysis. Surgical Technique A posterior approach was used in every case. An attempt was made to remove the components using standard techniques. However, if this was unsuccessful or if further exposure was felt necessary, then an extended trochanteric osteotomy was performed as previously described [2,5,17]. The length of the osteotomy was planned to facilitate component and cement removal [4]. The muscular attachments to the osteotomy fragment were preserved in every case, thereby preserving the blood supply to the osteotomized bone. After removal of the implant (and cement when present), the canal was cleared of any remaining membrane and fibrous tissue. Mesh was applied to any cortical defects before impaction grafting to constrain the impacted bone chips. An Exeter X-Change (Stryker Corporation, Mahwah, NJ) proximal impactor of the chosen size and length was inserted into the proximal femur, ensuring that the ETO fragment could be reduced over it, which was possible in every case. The proximal impactor creates enough space to allow for the stem and a complete mantle of cement around the implant. A trial reduction was then performed to establish the correct position of the implant relative to the femur (leg length and version). If satisfactory, impaction grafting was then carried out using the standard technique described previously [14-16]. Results Clinical The preoperative and postoperative clinical scores are shown in the Table, and their differences are statistically significant. There was no postoperative infection or dislocation. There were 2 postoperative fractures of the greater trochanter. All patients were Trendelenburg positive preoperatively. Eleven patients were Trendelenburg negative at the most recent follow-up, whereas Table. Preoperative and Postoperative Clinical Scores According to the Charnley Modification of the Merle D'Aubigné-Postel System (Wilcoxon signed rank test) Preoperative Mean (range) Postoperative Mean (range) Pain 2.4 (1-4; SD, 0.9) 5.1 (2-6; SD, 1.1) P b.001 Function 1.8 (0-4; SD, 0.9) 3.2 (1-6; SD, 1.4) P =.003 Movement 3.6 (2-4; SD, 0.7) 4.8 (4-6; SD, 0.7) P b.001 P

3 156 The Journal of Arthroplasty Vol. 28 No. 1 January patients remained Trendelenburg positive, including 1 case where the greater trochanter was found to be fractured preoperatively, 1 case where severe abductor insufficiency was noted intraoperatively (case shown in Fig. 3), 2 cases that had more than 2 previous ipsilateral arthroplasty procedures and the 2 cases where a fracture of the greater trochanter were noted postoperatively. No patient required further femoral revision, with a survivorship of 100% for the combined use of these techniques in this series. Radiologic Signs of clinical and radiologic healing were first noted at a mean follow-up of 5.8 months (4-6 months). The ETO fragment healed in all cases, with no nonunion or proximal migration of the fragment observed in any case. The mean ETO length was 130 mm ( mm), and the mean number of cables and/or cerclage wires used to reduce and fix the ETO fragment was 4 (3-8). A minimum of 3 cables or wires was used in every case, being 1 proximally, 1 at the middle third, and 1 distally on the fragment. Additional cables or wires were used when stability of the fixation was not sound or for longer ETO fragments. The mean femoral diameter measured at the distal transverse cut of the ETO was 25 mm (18-30 mm). The revision stem bypassed the distal ETO line by a mean length of 58 mm ( mm), resulting in a mean ratio of the latter over the femoral diameter of 2.3. Stem subsidence within the cement mantle greater than 3 mm was observed in 1 hip. This stem subsided 5 mm in the first 2 years from implantation and then stabilized. At the most recent follow-up at 51 months, no further subsidence was noted. No sign of graft resorption was observed in any case. Evidence of cortical healing in areas of preexisting lysis was assessed on anteroposterior radiographs because the lateral view images in some radiographs in the series were either overpenetrated or underpenetrated, varying significantly in quality and, therefore, preventing a reliable serial comparison. For every preoperative radiograph, the proximal femur was divided according to the zones described by Gruen et al [12], and for each of them, the cortex was classified as deficient or not. Follow-up Fig. 1. Anteroposterior radiographs of the right hip preoperatively, showing a well-fixed Harris-Galante uncemented stem that required removal for rotational correction (A); immediately after operation, demonstrating the use of impaction grafting for fixation on the sclerotic endosteal surface left after implant removal that was not suitable for direct cementing (B). A proximal calcar mesh was not required, as there was no significant medial femoral neck deficiency. The ETO fragment was fixed with cerclage wiring only (before cables became available); after 5 years, demonstrating full healing at the osteotomy site and graft incorporation (C).

4 ETO Followed by Cemented Impaction Allografting Charity et al 157 radiographs were then analyzed in the same way for evidence of radiologic healing. From the entire group, a total of 73 zones were identified as deficient. Because of the presence of metalwork such as wires, cables, and metal mesh, only 53 of these zones were assessable both preoperatively and postoperatively to enable the investigators to objectively compare these appearances. Visible evidence of healing was seen on the latest follow-up radiographs in all of these 53 zones. Trabecular remodelling, as previously described by Halliday et al [18], was considered to have occurred in 37 zones. The preoperative and postoperative radiographs of three cases are shown in Figs. 1 to 3. Discussion The introduction of the ETO in hip revision arthroplasty expanded the options available to remove well-fixed femoral components or cement. A conventional trochanteric osteotomy fails to adequately expose the implant to be removed and brings an added risk of nonunion of the greater trochanter. An extended trochanteric osteotomy as described by Younger et al [3] provides an extensive segment of well-vascularized bone for reattachment to the host bone bed. The osteotomy length may vary but is generally between 10 and 13 cm [2]. Although most publications on the use of the ETO report favorable results, complications have also been reported Fig. 2. Anteroposterior radiographs of the left hip preoperatively, showing a Mittelmeir stem requiring removal and deficient proximal bone stock (A); immediately after operation, showing fixation with cables except for the most proximal section in close contact with the joint where a monofilament cerclage wire was used to avoid fretting and minimize production of metal particulate debris (B); after 8 years, showing evidence of restoration of proximal bone stock and healing of the osteotomy site (C).

5 158 The Journal of Arthroplasty Vol. 28 No. 1 January 2013 Fig. 3. Anteroposterior radiographs of the left hip preoperatively, showing a loose Charnley prosthesis with well-fixed cement distal to it requiring removal (A); immediately after operation, demonstrating an ETO of 190 mm in length fixed with multiple cables and wires, along with a small mesh to constrain the graft at a proximal anterior cortical deficiency (B). Severe abductor insufficiency ( bald greater trochanter) was noted intraoperatively requiring the use of a constrained liner; after 4 years and 8 months, anteroposterior view, demonstrating signs of healing (C); after 4 years and 8 months, lateral view (D). including nonunion (1%-3%), fracture (4%-20%), proximal migration of the ETO fragment (0%-1.2%), infection (1%-3%), and uncemented stem subsidence. The overall complication rate has been as high as 24% in some reports [2,5,8,19-22]. Adequate reduction and fixation of the ETO fragment along with the preservation of its vascular supply have been highlighted as being of great importance [7]. Bone reconstruction in case of deficient proximal bone stock carries additional risk of complications. The femoral impaction grafting technique, when adequately performed, has been shown to be a reliable method to reconstruct and ultimately augment damaged femoral bone [23,24]. Cemented femoral components provide better load distribution and prevent proximal stress shielding, allowing time for the periprosthetic impacted

6 ETO Followed by Cemented Impaction Allografting Charity et al 159 allograft to incorporate. In the presence of an ETO, impaction grafting can be expected to protect the osteotomy site from cement interposition and facilitate healing by providing osteoconductive material to promote bone union. Hellman et al [9] reported 2 cases of nonunion of the ETO after femoral impaction grafting in a series of 10 hips. The authors suggested the failure to union might have been either related to cement interposition at the osteotomy site or due to a variation of the impaction grafting technique used. Good results were reported in a limited number of patients (n = 4) from a series where an ETO was followed by cemented revision and impaction grafting using a collarless polished tapered stem [25]. A cadaveric study measuring micromotion and testing the stability of a cemented allograft impacted construct after an ETO vs an intact proximal femur found no difference in stability between the 2, suggesting that, from a biomechanical point of view, an ETO and impaction allografting could be used in a combined procedure [26]. Our results support the view that impaction grafting can be safely performed after an ETO has been carried out. All patients in this study were clinically healed at a mean of 6 months with a statistically significant improvement in their clinical scores along with evidence of radiologic healing in every case. A technical point to be made is that as long as one achieves sound impaction of good-quality cancellous allograft chips of 4 to 5 mm in size for the distal femur and of 8 to 10 mm proximally in the femur, no extrusion of cement should occur into the osteotomy site that could impair healing. It is important to highlight that firm packing of allograft chips in a retrograde fashion from distal to proximal decreases significantly the risk of residual voids in the graft layer that could potentially allow for a cement leak. Subsidence within the cement mantle (stem-cement interface) was assessed on serial films. This represents fixation by the taper-slip principle and is not regarded as failure in the absence of other adverse clinical or radiologic features. The results in this study of all but 1 stem subsiding less than 3 mm confirm the characteristic pattern previously reported for this implant and technique [18], suggesting that the presence of an ETO did not affect the mechanical stability of the reconstruction in these hips in any way. When assessing the length of the femoral component, length of the ETO, and the cortical diameter at that level, a minimum ratio of at least 2 cortical diameters of metalwork bypassing the transverse osteotomy line was aimed in every case. We feel this is important in avoiding periprosthetic fracture or implant failure. The results described give support to the use of ETO, when indicated, combined with impaction grafting at revision total hip arthroplasty with implantation of a cemented polished prosthesis. Acknowledgments The authors acknowledge with gratitude the work done in the Exeter Hip Unit at the Princess Elizabeth Orthopaedic Centre by R Sculpher, S Wraight, C Harris, and L Collett, which included keeping track of every patient, and would like to thank SL Whitehouse, PhD, Biostatistician, Institute of Health and Biomedical Innovation, Queensland University of Technology, The Prince Charles Hospital, Brisbane, for her assistance with this study. References 1. Huo MH, Cook SM. What's new in hip arthroplasty. J Bone J Surg Am 2001;83(10): Younger TI, Bradford MS, Paprosky WG. Removal of a well-fixed cementless femoral component with an extended proximal femoral osteotomy. 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