- Email: [email protected]
The Exeter Trauma Stem: A radiographic follow-up at minimum of five years post implantation
G Model JINJ 7415 No. of Pages 5
Injury, Int. J. Care Injured xxx (2017) xxx–xxx
Contents lists available at ScienceDirect
Injury journal homepage: www.elsevier.com/locate/injury
The Exeter Trauma Stem: A radiographic follow-up at minimum of five years post implantation A.M. Kassama , L. Tillotsona , S.L. Whitehouseb , J. Charitya,* a
Exeter Hip Unit, Princess Elizabeth Orthopaedic Centre, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW UK Orthopaedic Research Unit, Institute of Health and Biomedical Innovation, Queensland University of Technology, The Prince Charles Hospital, Chermside, Queensland, 4037 Australia b
A R T I C L E I N F O
Keywords: Hip fracture Hemiarthroplasty NICE Exeter Radiographic survival Loosening
A B S T R A C T
Introduction: The Exeter Trauma Stem (ETS) has been recommended by National Institute of Clinical Excellence (NICE) guidelines in the United Kingdom as a proven, cemented stem. A single laboratory study in the literature has raised possible concerns about the polished finish of the ETS and subsequent potential for accelerated loosening although there is little clinical evidence to support or refute this. Methods: The aim of this study was to assess clinical outcomes of the ETS at a minimum of five years post implantation. Primary outcomes were radiological loosening at a minimum of five years along with survivorship of the implant. Patient demographics were prospectively collected and followed up. Results: 218 ETS’s (in 214 patients) were implanted from June 2002 until August 2008 in a single centre by a wide variety of surgeons of differing grades. Of these, 16 underwent revision surgery for fracture (2), dislocation (3), infection (1) and acetabular erosion (10) but there were no revisions for aseptic loosening of the implant. There were 64.0% (137/214) patients that had died by the time of this study. Of the remaining patients, 90 had radiographs of their hips at a minimum of 5 years with 36 of these at a minimum of 7 years post implantation. None of these had evidence of loosening. Conclusion: The ETS is a robust and suitable stem for implantation in patients with hip fractures. There are no clinical suspicions or increased rates of loosening with the ETS in our study. The concerns about surface finish are not borne out in our clinical study which shows no evidence of loosening at a minimum of five years post operation. It confers many advantages including ease of revision and it should continue to be used as per NICE guidelines. © 2017 Elsevier Ltd. All rights reserved.
Introduction Recent United Kingdom NICE guidelines suggest the use of a proven hemiarthroplasty rather than the Austin Moore or Thompson design in the treatment of displaced intracapsular neck of femur fractures [1]. The Exeter Trauma Stem (ETS) is a double tapered polished stem (Stryker Orthopaedics, Mahwah, New Jersey) based on the design of an Exeter V40 stem. The ETS was first introduced on the market in 2002 and has been used in the authors’ institution since then. At the time, it was introduced circumspectly in conjunction with the Thompson hemiarthroplasty, which was used in the majority of cases. Since NICE guidelines in 2011, the ETS is the only non-modular hemiarthroplasty used in our institution [1]. Over 64000 hip
* Corresponding author at: 9 Stream Court, Haven Road, Exeter, EX2 8DL, UK. E-mail address: [email protected] (J. Charity).
fractures occur per year in the UK and this is a figure that is increasing year by year, placing an increasing burden on the National Health Service (NHS) [2]. Concerns have been raised about the surface finish of the ETS compared to the V40 but there is no evidence currently to suggest that this has any clinical significance [3]. There have been no early problems of the ETS reported, and several reports have shown no significant difference in mortality rates or post-operative pain [4– 8]. Parker has the longest follow up currently within the literature, which shows that there is a low complication rate associated with the ETS with a low revision risk of the implant. This study, however, only used radiological follow up of the ETS implant at 6 weeks post operation [9]. The aim of our study was to report on all consecutive ETS stems implanted at our institution with minimum radiological follow-up of five years and to report survivorship of the ETS in this elderly, frail population. The primary outcome was evidence of radiological loosening, with a secondary outcome of revision.
http://dx.doi.org/10.1016/j.injury.2017.09.014 0020-1383/© 2017 Elsevier Ltd. All rights reserved.
Please cite this article in press as: A.M. Kassam, et al., The Exeter Trauma Stem: A radiographic follow-up at minimum of five years post implantation, Injury (2017), http://dx.doi.org/10.1016/j.injury.2017.09.014
G Model JINJ 7415 No. of Pages 5
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A.M. Kassam et al. / Injury, Int. J. Care Injured xxx (2017) xxx–xxx
Patients and methods A retrospective review was performed of a consecutive series of the first 218 ETS’s (214 patients) performed at our institution. The operations were carried out between April 2002 (launch date of the ETS) and August 2008, to ensure a minimum five-year followup (Fig. 1). Data was collected prospectively using our institutional database and validated with the Hospital Episode Statistics (HES) and, from its launch in 2008, the National Hip Fracture Database (NHFD) to ensure completeness of records [2]. At the time of this study, 137 patients with 139 ETS implants (64.0%) had died. There were 18 patients (8.3%) that had died within 30 days of surgery (including 8 whilst still in hospital) and 39 (17.9%) died within 1 year of surgery. The mean patient age at the time of operation was 80.9 years (range 60–99 years). There were 175 (80.3%) ETS implants performed in females and 43 (19.7%) in males. The indication for surgery for all patients was a displaced intracapsular fractured neck of femur. The other prosthesis used in our department during this time period was the Thompson hemiarthroplasty (Stryker Orthopaedics, Mahwah, New Jersey). Patients who were felt to have independent mobility and who were cognitively unimpaired, had an ETS implanted rather than a Thompsons prosthesis. In the same study period 1602 cemented Thompson hemiarthroplasties were performed with comparison frequency graphs shown in Fig. 2. All ETS’ were performed via a lateral approach and cemented in place with Simplex cement (Stryker Orthopaedics, Mahwah, New Jersey) or Palacos cement (Heraeus, Hanau, Germany) depending on surgeon preference. ETS prostheses were implanted by a range of surgeons with varying expertise (Table 1) with 71 (32.6%) by, or under the supervision of, specialist hip surgeons and 147 (67.4%) by non-specialist hip surgeons. All consecutive patients undergoing ETS implantation were included in this review. Radiographs were requested for all surviving patients but were limited by patient comorbidities, cognitive disability and patients who had moved out of area and were radiologically assessed for presence of radiolucent lines at any interface and for evidence of loosening. Those patients without radiographs who were unable to attend for review had a telephone consultation to determine if they had any pain or lack of mobility with regards their operated hip and whether they had undergone any revision surgery. Revision of the implant for all patients was recorded including the reason for revision.
Radiographic analysis was performed by two of the authors (AK and JC) who assessed all radiographs independently. Femoral lucency was assessed, in seven zones as described by Gruen, on anteroposterior radiographs of the implant [10]. One patient had a CT scan performed within the required time frame which was assessed for loosening as no radiograph was available. A minimum five year follow-up was specified, although as some cases extended beyond seven years, this subgroup is also reported separately. Statistical analysis Data analysis was performed using SPSS for Windows (version 21, IBM Corp, Armonk, New York). Kaplan-Meier [11] survivorship curves were generated with the endpoints of revision for aseptic loosening and any cause revision (including infection) with a minimum 40 cases remaining at risk [12]. Construction of a worst case curve was not required as no patients were lost to follow-up [13] despite the transient nature of hip fracture patients. Results There were 218 hips in 214 patients implanted in the study period. Of the 218 hips, 16 ETS implants underwent revision at a rate of 7.3% (Table 2) at a mean of 37.4 months (range 0.6–87.9). The majority were for pain secondary to acetabular erosion (Table 1). There were no revisions performed for aseptic loosening. There were 137 patients (139 hips) (64.0%) that had died by the time of this review; 18 patients (8.3%) within 30 days of surgery (including 8 whilst still in hospital) and 39 (17.9%) within 1 year of surgery. The average time from surgery to death was 3.3 years (range 0– 11.5). There were 58 ETS prostheses implanted that had follow-up radiographs at a minimum of five years post-op (mean 7.6 years, range 5.2–10.9) with no radiographic evidence of lucency. Forty of these prostheses (69%) had a complete cement mantle in Gruen zones 1–7 and 18 patients had evidence, on immediate postoperative radiographs, of inadequate cement mantle in zone 1 only. None of these progressed on latest follow-up radiographs. No significant difference was found when comparing zone 1 lucencies between different grades of operating surgeon nor between specialist hip and non-hip surgeons (Table 3). Of the 36 ETS implants with minimum of 7-year follow-up radiographs, there was no radiographic evidence of progressive lucency compared to post-operative images.
Fig. 1. Flowchart showing ETS cohort and selection demographics.
Please cite this article in press as: A.M. Kassam, et al., The Exeter Trauma Stem: A radiographic follow-up at minimum of five years post implantation, Injury (2017), http://dx.doi.org/10.1016/j.injury.2017.09.014
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Fig. 2. Frequency of Thompson hemiarthoplasties compared to ETS0 performed per year during study period.
Table 1 Grade of lead surgeon performing surgery using the ETS. Grade of surgeon
Number (%) Specialist hip Non-specialist hip
Consultant Post FRCS Arthroplasty Fellow Specialist Registrar Senior House Officer
63 (28.9%) 32 (14.7%) 107 (49.1%) 16 (7.3%)
28 20 18 5
35 12 89 11
There were 16 surviving ETS implants without radiographs at a minimum of five years post-operation. These patients were contacted and reasons for inability to attend for radiographs were recorded (Table 4). All patients or family/carers were contacted. None had their implant revised at other institutions and none reported pain or lack of mobility related to their hip. Harris Hip Scores for these patients were noted as “none, or ignores it” (Harris score = 44) or “slight and occasional with no compromise in activities” (Harris score = 40) [14]. Survivorship
Table 2 Reasons for revision of ETS implants. Reason for revision
Number
Acetabular erosion/pain Infection Dislocation Periprosthetic fracture
10 1 3 2
The Kaplan-Meier survivorship was calculated with 40 cases remaining at 7.5 years (Fig. 3). Survivorship of the ETS with revision for any endpoint was 87.6% (95% confidence interval (CI) 81.13 to 94.07%). Survivorship of the ETS with revision for aseptic loosening was 100%. Discussion
Table 3 Grade of surgeon (a) and Hip vs Non hip surgeon (b) with inadequate cement in Gruen Zone 1. (a) 18 patients with inadequate cement in zone 1 Consultant Fellow/Specialist Registrar
4 14
(b) 18 patients with inadequate cement in zone 1 Specialist Hip Surgeon Non-hip Surgeon
5 13
Table 4 Reasons for inability to attend for radiographs. Reason of inability to attend
Number
Out of area Unable to attend due to dementia, poor mobility, ill health
4 12
This retrospective study shows that there is no evidence of radiological loosening of the ETS at a mean of 7.6 years postoperatively even after accounting for the death rate of patients with a hip fracture. Revision of the ETS stem is also low at 12.5 years (7.3%) and complications are comparable to other hemiarthroplasty implants [6,15,16]. There were 20% of the ETS implants with a minimum of 7 year follow up (7 out of 35), had inadequate cement in Zone 1 on their immediate post-operative radiograph. There was no correlation of this cement inadequacy between surgical grade nor between specialist hip and non-hip surgeons. This is likely secondary to insufficient clearance of corticocancellous bone from the proximal lateral canal and within the greater trochanter at the time of femoral preparation. This did not appear to confer any clinical problems in this limited group of patients as no progressive lucency at any interface was observed at later review. NICE guidelines recommend the use of a proven stem design for intracapsular hip fractures. The ETS is named in the guidelines, despite not having an ODEP rating, on the basis that its design is based on the Exeter V40 stem, which is a proven, ODEP 10A* rated
Please cite this article in press as: A.M. Kassam, et al., The Exeter Trauma Stem: A radiographic follow-up at minimum of five years post implantation, Injury (2017), http://dx.doi.org/10.1016/j.injury.2017.09.014
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Fig. 3. Kaplan-Meier survival curves for the ETS for revisions for aseptic loosening and all cause revision.
stem used for total hip replacements (THR). The ETS was introduced and has been in use in our department for almost 10 years prior to the NICE guidelines. Limited evidence regarding the ETS is available in the literature. No differences have been shown between the ETS and the Thompson hemiarthroplasty in terms of immediate complications including dislocation, infections and range of movement [4,6]. Parker reported no difference in length of hospital stay or operative time, and although a reduced leg length discrepancy was noted with the ETS implant, this was not found to be statistically significant [6]. At one year patients who had an ETS implanted had little or no pain [9]. The only reported long term outcomes are from the Australian registry which shows a revision rate for the ETS of 3.8% at 5 years. The same data shows that the 5 year mortality is 73% which suggests that revision is not the major concern in this frail, elderly cohort of patients [17]. The ETS is a double tapered design based on the Exeter V40 stem. The Exeter stem functions by a taper slip philosophy whereby load is transmitted through the stem in a compressive manner as hoop stresses in the cement mantle [18–21]. This contributes to the long term survival of the Exeter stem in the literature [22–27]. Petheram et al. have shown that the surface finish of the ETS is less polished than the Exeter V40 stem (surface roughness of 0.235 mm compared to 0.025 mm) [3]. This is still significantly lower than the surface roughness of the Exeter Matt stem (0.8–1.3 mm) which had a high revision rate and of which production was stopped in 1986 [28]. Electron microscopy and 3D interferometry studies have shown that surface roughness of between 0.389 and 2.59 mm increase the risk of abrasive wear [29]. Along with other studies, this would suggest that a stem with surface roughness greater than 0.4 mm will wear by an abrasive mechanism and that the critical roughness to avoid abrasive wear, and allow the stem to follow that taper slip philosophy, is between 0.1 and 0.3 mm [29,30]. The ETS lies within the critical roughness range and as such has a low risk of abrasive wear and should behave in a similar manner to an Exeter THR stem. Our study
supports this data with no cases of radiological loosening at a mean of 7.6 years post implantation. Raut and Parker retrospectively evaluated 604 implanted ETS’ and showed a revision rate of 2.6% at two to seven years. Whilst their study reported on consecutive ETS’s implanted in all patients presenting to their unit, patients who received ETS implants in our cohort (whose operations were performed before NICE guidelines into hip fractures) were generally fitter and higher demand patients, many of whom would have received a THR under current guidelines. Our cohort would have been fitter than the majority of intracapsular hip fractures attending our department who received Thompson hemiarthroplasties and so our cohort would have been more likely to require revision surgery for acetabular erosion. Another difference between Raut’s group and our study cohort is shown in the difference in death rates between the groups (one year mortality of 29.3% compared to 17.9%). Our cohort of patients were also younger (80.9 years vs 84 years). Comparison of death rates is difficult to interpret between groups as Raut’s groups had a large range of follow-up (2–7 years) compared to our group which had a mean of 7.6 year follow-up (death rates in both groups similar despite this 63.2% in Rauts cohort vs 62.8% in our cohort) [9]. Mortality after hip fracture remains high with a mortality rate of up to 30% at one year [31] and 80% after 8 years [32]. This is equivocal to our data and would suggest that the long term survival of a hemiarthroplasty implant is less critical when compared to that of the total hip replacement. NICE guidelines suggest that medically fit patients with a hip fracture, who are active and have no cognitive dysfunction, should be offered total hip replacement surgery rather than hemiarthroplasty [1]. This would undoubtedly filter out some of the patients who would survive beyond 8 years and potentially we may see that patients receiving a hemiarthroplasty would have a higher mortality rate than currently in the literature. Undoubtedly, with a high mortality rate, as in fractured hip patients, careful consideration needs to be made when considering
Please cite this article in press as: A.M. Kassam, et al., The Exeter Trauma Stem: A radiographic follow-up at minimum of five years post implantation, Injury (2017), http://dx.doi.org/10.1016/j.injury.2017.09.014
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what implant to utilise. The ETS is a cost-effective implant (that costs approximately one third of an Exeter V40 stem and head) that confers the advantage of allowing easier cement-in-cement revision if this is needed. The stem size is classed between the Size 0 and Size 1 standard Exeter V40 stems, allowing uncomplicated cement-in-cement revision using shorter and/or slimmer stems, with retention of the existing cement mantle. Limitations This is a retrospective study and the death rate in this cohort of patients, which is replicated in the rest of the literature, makes interpretation and definite conclusions difficult. We have minimised this by contacting all patients or family/carers who were still alive at the time of review. A proportion of patients (17 out of 65) were unable to attend for radiographs due to frailty, medical problems and dementia, but these were all contacted by telephone to assess the degree of discomfort from their ETS hip either from the patient directly of from family members or carers commenting on the patient’s mobility and pain in their hip. Clinical follow-up of hip fractures is not routinely undertaken in the UK. It is difficult to ensure frail and elderly patients, often with some element of cognitive impairment, return to clinical appointments for review and radiographs. For this reason, we had a proportion of patients who were unable to re-attend for radiographs and review and we did not feel it was ethically viable to enforce their attendance. This problem is well recognised in various research studies along with the high death rate of hip fracture patients making analysis of survivorship difficult. [33–35] Our study is the longest published literature with radiological outcomes of the ETS and show that it is a safe, low risk and low wear option in the treatment of intracapsular hip fractures requiring hemiarthroplasty. Acknowledgements The authors acknowledge the support of the Exeter Hip Research Team in organising patients’ appointments, searching for radiographs and providing outcome scores. The authors would like to thank the members of the Exeter Hip Unit for their tireless work following every patient; S. Wraight, S. Moore and L. Collett. References [1] NICE. The management of hip fracture in adults. National Clinical Guideline Centre; 2011. [2] Royal College of Physicians. The National Hip Fracture Database. 2015 [Available from: http://www.nhfd.co.uk/. [3] Petheram TG, Bone M, Joyce TJ, Serrano-Pedraza I, Reed MR. Partington P: surface finish of the Exeter Trauma Stem. Bone Joint J 2013;95-B(2):173–6. [4] Bidwa ASC, Willett K. Comparison of the Exeter Trauma Stem and the Thompson hemiarthroplasty for intracapsular hip fractures. Hip Int 2012;22 (6):655–60. [5] Cash D, Bayer J, Logan K, Wimhurst J. The Exeter trauma stem: early results of a new cemented hemiarthroplasty for femoral neck fracture. Br J Med Pract 2010;3(1):303–7. [6] Parker M. Cemented Thompson hemiarthroplasty versus cemented Exeter Trauma Stem (ETS) hemiarthroplasty for intracapsular hip fractures: a randomised trial of 200 patients. Injury 2012;43:807–10. [7] O'Neill G, Smyth J, Stark A, Ingram R. Early outcomes following Exeter Trauma Stem for intracapsular hip fractures. J Bone Joint Surg (Br) 2012;94-B (Suppl):32.
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[8] Sinclair MDJ, Pavlou P, Stuart S, Salter T, Harvey A. Exeter Trauma Stem: an early experience in a DGH. Injury Extra 2011;42:105–6. [9] Raut S, Parker MJ. Medium to long term follow up of a consecutive series of 604 Exeter Trauma Stem Hemiarthroplasties (ETS) for the treatment of displaced intracapsular femoral neck fractures. Injury 2016;47(3):721–4. [10] Gruen TA, McNeice GM, HC A. Modes of failure of cemented stem-type femoral components: radiographic study. Clin Orthop Relat Res 1979;141:17–27. [11] Kaplan EL, Meier P. Nonparametric estimation from incomplete observations. J Am Stat Assoc 1958;53(282):457–81. [12] Lettin AW, Ware HS, Morris RW. Survivorship analysis and confidence intervals: an assessment with reference to the Stanmore total knee replacement. J Bone Joint Surg Br 1991;73(5):729–31. [13] Murray DW, Carr AJ, Bulstrode C. Survival analysis of joint replacements. J Bone Joint Surg [Br] 1993;75(5):697–704. [14] Harris W. Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty. An end-result study using a new method of result evaluation. J Bone Joint Surg 1969;51(4):737–55. [15] Gjertsen SL JE, Vinje T, Engesaxter LB, Hallan G, Matre K, Furnes O. More reoperations after uncemented than cemented hemiarthroplasty used in the treatment of displaced fractures of the femoral neck. Bone Joint J 2012;94B:1113–9. [16] Azegami KG S, Parker MJ. Cemented versus uncemented hemiarthroplasty for hip fractures: a systematic review of randomised controlled trials. Hip Int 2011;21(5):509–17. [17] No authors listed. National Joint Replacement Registry: Hip and Knee Arthroplasty Annual Report. 2011. [18] Fowler GG JL, Lee AJC, Ling RSM. Experience with the Exeter total hip replacement since 1970. Orthop Clin North Am 1988;19:477–89. [19] Huiskes V R, Nivbrant B. Migration, Stem shape, and surface finish in cemented total hip arthroplasty. Clin Orthop Relat Res 1998;355:103–12. [20] Shen G. Femoral stem fixation: an engineering interpretation of the long term outcome of Charnley and Exeter stems. J Bone Jount Surg (Br) 1998;80-B:754– 6. [21] MIles SC AW, Bannister GC. The effect of the surface finish of the femoral component on load transmission in total hip replacement. J Bone Joint Surg (Br) 1990;72-B(Suppl):736. [22] Carrington NC, Sierra RJ, Gie GA, Hubble MJ, Timperley AJ, Howell JR. The Exeter Universal cemented femoral component at 15 to 17 years: an update on the first 325 hips. J Bone Joint Surg Br 2009;91(6):730–7. [23] Hook S, Moulder E, Yates PJ, Burston BJ, Whitley E, Bannister GC. The Exeter Universal stem: a minimum ten-year review from an independent centre. J Bone Joint Surg Br 2006;88(12):1584–90. [24] Williams HD, Browne G, Gie GA, Ling RS, Timperley AJ, Wendover NA. The Exeter universal cemented femoral component at 8 to 12 years: a study of the first 325 hips. J Bone Joint Surg Br 2002;84(3):324–34. [25] Young L, Duckett S, Dunn A. The use of the cemented Exeter Universal femoral stem in a District General Hospital: a minimum ten-year follow-up. J Bone Joint Surg Br 2009;91(2):170–5. [26] No authors listed. National Joint Registry: 12th Annual Report. 2015. [27] Petheram TG, Whitehouse SL, Kazi HA, Hubble MJ, Timperley AJ, Wilson MJ, et al. The Exeter Universal cemented femoral stem at 20 to 25 years: a report of 382 hips. Bone Joint J 2016;98-b(11):1441–9. [28] No authors listed. In: Ling R, editor. The Exeter Hip: 40 years of innovation in Total HIp Arthroplasty. Exeter Hip Publishing; 2010. [29] Howell LB JR, Doyle C, Hooper M, Lee AJC, Ling RSM. In vivo surface wear mechanisms of femoral components of cemented total hip arthroplasties. J Arthroplasty 2004;19(1):88–101. [30] Sheerlinck PC T. The design features of cemented femoral hip implants. Bone Joint J 2006;88-B:1409–18. [31] Bredahl C, Nyholm B, Hindsholm KB, Mortensen JS, Olesen AS. Mortality after hip fracture: results of operation within 12 h of admission. Injury 1992;23 (2):83–6. [32] Johnston AT, Barnsdale L, Smith R, Duncan K, Hutchison JD. Change in longterm mortality associated with fractures of the hip: evidence from the scottish hip fracture audit. J Bone Joint Surg Br 2010;92(7):989–93. [33] Norrish AR, Rao J, Parker MJ. Prosthesis survivorship and clinical outcome of the Austin Moore hemiarthroplasty: an 8-year mean follow-up of a consecutive series of 500 patients. Injury 2006;37(8):734–9. [34] Tanous T, Stephenson KW, Grecula MJ. Hip hemiarthroplasty after displaced femoral neck fracture: a survivorship analysis. Orthopedics 2010;33(6):385. [35] Chaplin VK, Matharu GS, Knebel RW. Complications following hemiarthroplasty for displaced intracapsular femoral neck fractures in the absence of routine follow-up. Ann R Coll Surg Engl 2013;95(4):271–4.
Please cite this article in press as: A.M. Kassam, et al., The Exeter Trauma Stem: A radiographic follow-up at minimum of five years post implantation, Injury (2017), http://dx.doi.org/10.1016/j.injury.2017.09.014
Injury, Int. J. Care Injured xxx (2017) xxx–xxx
Contents lists available at ScienceDirect
Injury journal homepage: www.elsevier.com/locate/injury
The Exeter Trauma Stem: A radiographic follow-up at minimum of five years post implantation A.M. Kassama , L. Tillotsona , S.L. Whitehouseb , J. Charitya,* a
Exeter Hip Unit, Princess Elizabeth Orthopaedic Centre, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW UK Orthopaedic Research Unit, Institute of Health and Biomedical Innovation, Queensland University of Technology, The Prince Charles Hospital, Chermside, Queensland, 4037 Australia b
A R T I C L E I N F O
Keywords: Hip fracture Hemiarthroplasty NICE Exeter Radiographic survival Loosening
A B S T R A C T
Introduction: The Exeter Trauma Stem (ETS) has been recommended by National Institute of Clinical Excellence (NICE) guidelines in the United Kingdom as a proven, cemented stem. A single laboratory study in the literature has raised possible concerns about the polished finish of the ETS and subsequent potential for accelerated loosening although there is little clinical evidence to support or refute this. Methods: The aim of this study was to assess clinical outcomes of the ETS at a minimum of five years post implantation. Primary outcomes were radiological loosening at a minimum of five years along with survivorship of the implant. Patient demographics were prospectively collected and followed up. Results: 218 ETS’s (in 214 patients) were implanted from June 2002 until August 2008 in a single centre by a wide variety of surgeons of differing grades. Of these, 16 underwent revision surgery for fracture (2), dislocation (3), infection (1) and acetabular erosion (10) but there were no revisions for aseptic loosening of the implant. There were 64.0% (137/214) patients that had died by the time of this study. Of the remaining patients, 90 had radiographs of their hips at a minimum of 5 years with 36 of these at a minimum of 7 years post implantation. None of these had evidence of loosening. Conclusion: The ETS is a robust and suitable stem for implantation in patients with hip fractures. There are no clinical suspicions or increased rates of loosening with the ETS in our study. The concerns about surface finish are not borne out in our clinical study which shows no evidence of loosening at a minimum of five years post operation. It confers many advantages including ease of revision and it should continue to be used as per NICE guidelines. © 2017 Elsevier Ltd. All rights reserved.
Introduction Recent United Kingdom NICE guidelines suggest the use of a proven hemiarthroplasty rather than the Austin Moore or Thompson design in the treatment of displaced intracapsular neck of femur fractures [1]. The Exeter Trauma Stem (ETS) is a double tapered polished stem (Stryker Orthopaedics, Mahwah, New Jersey) based on the design of an Exeter V40 stem. The ETS was first introduced on the market in 2002 and has been used in the authors’ institution since then. At the time, it was introduced circumspectly in conjunction with the Thompson hemiarthroplasty, which was used in the majority of cases. Since NICE guidelines in 2011, the ETS is the only non-modular hemiarthroplasty used in our institution [1]. Over 64000 hip
* Corresponding author at: 9 Stream Court, Haven Road, Exeter, EX2 8DL, UK. E-mail address: [email protected] (J. Charity).
fractures occur per year in the UK and this is a figure that is increasing year by year, placing an increasing burden on the National Health Service (NHS) [2]. Concerns have been raised about the surface finish of the ETS compared to the V40 but there is no evidence currently to suggest that this has any clinical significance [3]. There have been no early problems of the ETS reported, and several reports have shown no significant difference in mortality rates or post-operative pain [4– 8]. Parker has the longest follow up currently within the literature, which shows that there is a low complication rate associated with the ETS with a low revision risk of the implant. This study, however, only used radiological follow up of the ETS implant at 6 weeks post operation [9]. The aim of our study was to report on all consecutive ETS stems implanted at our institution with minimum radiological follow-up of five years and to report survivorship of the ETS in this elderly, frail population. The primary outcome was evidence of radiological loosening, with a secondary outcome of revision.
http://dx.doi.org/10.1016/j.injury.2017.09.014 0020-1383/© 2017 Elsevier Ltd. All rights reserved.
Please cite this article in press as: A.M. Kassam, et al., The Exeter Trauma Stem: A radiographic follow-up at minimum of five years post implantation, Injury (2017), http://dx.doi.org/10.1016/j.injury.2017.09.014
G Model JINJ 7415 No. of Pages 5
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Patients and methods A retrospective review was performed of a consecutive series of the first 218 ETS’s (214 patients) performed at our institution. The operations were carried out between April 2002 (launch date of the ETS) and August 2008, to ensure a minimum five-year followup (Fig. 1). Data was collected prospectively using our institutional database and validated with the Hospital Episode Statistics (HES) and, from its launch in 2008, the National Hip Fracture Database (NHFD) to ensure completeness of records [2]. At the time of this study, 137 patients with 139 ETS implants (64.0%) had died. There were 18 patients (8.3%) that had died within 30 days of surgery (including 8 whilst still in hospital) and 39 (17.9%) died within 1 year of surgery. The mean patient age at the time of operation was 80.9 years (range 60–99 years). There were 175 (80.3%) ETS implants performed in females and 43 (19.7%) in males. The indication for surgery for all patients was a displaced intracapsular fractured neck of femur. The other prosthesis used in our department during this time period was the Thompson hemiarthroplasty (Stryker Orthopaedics, Mahwah, New Jersey). Patients who were felt to have independent mobility and who were cognitively unimpaired, had an ETS implanted rather than a Thompsons prosthesis. In the same study period 1602 cemented Thompson hemiarthroplasties were performed with comparison frequency graphs shown in Fig. 2. All ETS’ were performed via a lateral approach and cemented in place with Simplex cement (Stryker Orthopaedics, Mahwah, New Jersey) or Palacos cement (Heraeus, Hanau, Germany) depending on surgeon preference. ETS prostheses were implanted by a range of surgeons with varying expertise (Table 1) with 71 (32.6%) by, or under the supervision of, specialist hip surgeons and 147 (67.4%) by non-specialist hip surgeons. All consecutive patients undergoing ETS implantation were included in this review. Radiographs were requested for all surviving patients but were limited by patient comorbidities, cognitive disability and patients who had moved out of area and were radiologically assessed for presence of radiolucent lines at any interface and for evidence of loosening. Those patients without radiographs who were unable to attend for review had a telephone consultation to determine if they had any pain or lack of mobility with regards their operated hip and whether they had undergone any revision surgery. Revision of the implant for all patients was recorded including the reason for revision.
Radiographic analysis was performed by two of the authors (AK and JC) who assessed all radiographs independently. Femoral lucency was assessed, in seven zones as described by Gruen, on anteroposterior radiographs of the implant [10]. One patient had a CT scan performed within the required time frame which was assessed for loosening as no radiograph was available. A minimum five year follow-up was specified, although as some cases extended beyond seven years, this subgroup is also reported separately. Statistical analysis Data analysis was performed using SPSS for Windows (version 21, IBM Corp, Armonk, New York). Kaplan-Meier [11] survivorship curves were generated with the endpoints of revision for aseptic loosening and any cause revision (including infection) with a minimum 40 cases remaining at risk [12]. Construction of a worst case curve was not required as no patients were lost to follow-up [13] despite the transient nature of hip fracture patients. Results There were 218 hips in 214 patients implanted in the study period. Of the 218 hips, 16 ETS implants underwent revision at a rate of 7.3% (Table 2) at a mean of 37.4 months (range 0.6–87.9). The majority were for pain secondary to acetabular erosion (Table 1). There were no revisions performed for aseptic loosening. There were 137 patients (139 hips) (64.0%) that had died by the time of this review; 18 patients (8.3%) within 30 days of surgery (including 8 whilst still in hospital) and 39 (17.9%) within 1 year of surgery. The average time from surgery to death was 3.3 years (range 0– 11.5). There were 58 ETS prostheses implanted that had follow-up radiographs at a minimum of five years post-op (mean 7.6 years, range 5.2–10.9) with no radiographic evidence of lucency. Forty of these prostheses (69%) had a complete cement mantle in Gruen zones 1–7 and 18 patients had evidence, on immediate postoperative radiographs, of inadequate cement mantle in zone 1 only. None of these progressed on latest follow-up radiographs. No significant difference was found when comparing zone 1 lucencies between different grades of operating surgeon nor between specialist hip and non-hip surgeons (Table 3). Of the 36 ETS implants with minimum of 7-year follow-up radiographs, there was no radiographic evidence of progressive lucency compared to post-operative images.
Fig. 1. Flowchart showing ETS cohort and selection demographics.
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Fig. 2. Frequency of Thompson hemiarthoplasties compared to ETS0 performed per year during study period.
Table 1 Grade of lead surgeon performing surgery using the ETS. Grade of surgeon
Number (%) Specialist hip Non-specialist hip
Consultant Post FRCS Arthroplasty Fellow Specialist Registrar Senior House Officer
63 (28.9%) 32 (14.7%) 107 (49.1%) 16 (7.3%)
28 20 18 5
35 12 89 11
There were 16 surviving ETS implants without radiographs at a minimum of five years post-operation. These patients were contacted and reasons for inability to attend for radiographs were recorded (Table 4). All patients or family/carers were contacted. None had their implant revised at other institutions and none reported pain or lack of mobility related to their hip. Harris Hip Scores for these patients were noted as “none, or ignores it” (Harris score = 44) or “slight and occasional with no compromise in activities” (Harris score = 40) [14]. Survivorship
Table 2 Reasons for revision of ETS implants. Reason for revision
Number
Acetabular erosion/pain Infection Dislocation Periprosthetic fracture
10 1 3 2
The Kaplan-Meier survivorship was calculated with 40 cases remaining at 7.5 years (Fig. 3). Survivorship of the ETS with revision for any endpoint was 87.6% (95% confidence interval (CI) 81.13 to 94.07%). Survivorship of the ETS with revision for aseptic loosening was 100%. Discussion
Table 3 Grade of surgeon (a) and Hip vs Non hip surgeon (b) with inadequate cement in Gruen Zone 1. (a) 18 patients with inadequate cement in zone 1 Consultant Fellow/Specialist Registrar
4 14
(b) 18 patients with inadequate cement in zone 1 Specialist Hip Surgeon Non-hip Surgeon
5 13
Table 4 Reasons for inability to attend for radiographs. Reason of inability to attend
Number
Out of area Unable to attend due to dementia, poor mobility, ill health
4 12
This retrospective study shows that there is no evidence of radiological loosening of the ETS at a mean of 7.6 years postoperatively even after accounting for the death rate of patients with a hip fracture. Revision of the ETS stem is also low at 12.5 years (7.3%) and complications are comparable to other hemiarthroplasty implants [6,15,16]. There were 20% of the ETS implants with a minimum of 7 year follow up (7 out of 35), had inadequate cement in Zone 1 on their immediate post-operative radiograph. There was no correlation of this cement inadequacy between surgical grade nor between specialist hip and non-hip surgeons. This is likely secondary to insufficient clearance of corticocancellous bone from the proximal lateral canal and within the greater trochanter at the time of femoral preparation. This did not appear to confer any clinical problems in this limited group of patients as no progressive lucency at any interface was observed at later review. NICE guidelines recommend the use of a proven stem design for intracapsular hip fractures. The ETS is named in the guidelines, despite not having an ODEP rating, on the basis that its design is based on the Exeter V40 stem, which is a proven, ODEP 10A* rated
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Fig. 3. Kaplan-Meier survival curves for the ETS for revisions for aseptic loosening and all cause revision.
stem used for total hip replacements (THR). The ETS was introduced and has been in use in our department for almost 10 years prior to the NICE guidelines. Limited evidence regarding the ETS is available in the literature. No differences have been shown between the ETS and the Thompson hemiarthroplasty in terms of immediate complications including dislocation, infections and range of movement [4,6]. Parker reported no difference in length of hospital stay or operative time, and although a reduced leg length discrepancy was noted with the ETS implant, this was not found to be statistically significant [6]. At one year patients who had an ETS implanted had little or no pain [9]. The only reported long term outcomes are from the Australian registry which shows a revision rate for the ETS of 3.8% at 5 years. The same data shows that the 5 year mortality is 73% which suggests that revision is not the major concern in this frail, elderly cohort of patients [17]. The ETS is a double tapered design based on the Exeter V40 stem. The Exeter stem functions by a taper slip philosophy whereby load is transmitted through the stem in a compressive manner as hoop stresses in the cement mantle [18–21]. This contributes to the long term survival of the Exeter stem in the literature [22–27]. Petheram et al. have shown that the surface finish of the ETS is less polished than the Exeter V40 stem (surface roughness of 0.235 mm compared to 0.025 mm) [3]. This is still significantly lower than the surface roughness of the Exeter Matt stem (0.8–1.3 mm) which had a high revision rate and of which production was stopped in 1986 [28]. Electron microscopy and 3D interferometry studies have shown that surface roughness of between 0.389 and 2.59 mm increase the risk of abrasive wear [29]. Along with other studies, this would suggest that a stem with surface roughness greater than 0.4 mm will wear by an abrasive mechanism and that the critical roughness to avoid abrasive wear, and allow the stem to follow that taper slip philosophy, is between 0.1 and 0.3 mm [29,30]. The ETS lies within the critical roughness range and as such has a low risk of abrasive wear and should behave in a similar manner to an Exeter THR stem. Our study
supports this data with no cases of radiological loosening at a mean of 7.6 years post implantation. Raut and Parker retrospectively evaluated 604 implanted ETS’ and showed a revision rate of 2.6% at two to seven years. Whilst their study reported on consecutive ETS’s implanted in all patients presenting to their unit, patients who received ETS implants in our cohort (whose operations were performed before NICE guidelines into hip fractures) were generally fitter and higher demand patients, many of whom would have received a THR under current guidelines. Our cohort would have been fitter than the majority of intracapsular hip fractures attending our department who received Thompson hemiarthroplasties and so our cohort would have been more likely to require revision surgery for acetabular erosion. Another difference between Raut’s group and our study cohort is shown in the difference in death rates between the groups (one year mortality of 29.3% compared to 17.9%). Our cohort of patients were also younger (80.9 years vs 84 years). Comparison of death rates is difficult to interpret between groups as Raut’s groups had a large range of follow-up (2–7 years) compared to our group which had a mean of 7.6 year follow-up (death rates in both groups similar despite this 63.2% in Rauts cohort vs 62.8% in our cohort) [9]. Mortality after hip fracture remains high with a mortality rate of up to 30% at one year [31] and 80% after 8 years [32]. This is equivocal to our data and would suggest that the long term survival of a hemiarthroplasty implant is less critical when compared to that of the total hip replacement. NICE guidelines suggest that medically fit patients with a hip fracture, who are active and have no cognitive dysfunction, should be offered total hip replacement surgery rather than hemiarthroplasty [1]. This would undoubtedly filter out some of the patients who would survive beyond 8 years and potentially we may see that patients receiving a hemiarthroplasty would have a higher mortality rate than currently in the literature. Undoubtedly, with a high mortality rate, as in fractured hip patients, careful consideration needs to be made when considering
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what implant to utilise. The ETS is a cost-effective implant (that costs approximately one third of an Exeter V40 stem and head) that confers the advantage of allowing easier cement-in-cement revision if this is needed. The stem size is classed between the Size 0 and Size 1 standard Exeter V40 stems, allowing uncomplicated cement-in-cement revision using shorter and/or slimmer stems, with retention of the existing cement mantle. Limitations This is a retrospective study and the death rate in this cohort of patients, which is replicated in the rest of the literature, makes interpretation and definite conclusions difficult. We have minimised this by contacting all patients or family/carers who were still alive at the time of review. A proportion of patients (17 out of 65) were unable to attend for radiographs due to frailty, medical problems and dementia, but these were all contacted by telephone to assess the degree of discomfort from their ETS hip either from the patient directly of from family members or carers commenting on the patient’s mobility and pain in their hip. Clinical follow-up of hip fractures is not routinely undertaken in the UK. It is difficult to ensure frail and elderly patients, often with some element of cognitive impairment, return to clinical appointments for review and radiographs. For this reason, we had a proportion of patients who were unable to re-attend for radiographs and review and we did not feel it was ethically viable to enforce their attendance. This problem is well recognised in various research studies along with the high death rate of hip fracture patients making analysis of survivorship difficult. [33–35] Our study is the longest published literature with radiological outcomes of the ETS and show that it is a safe, low risk and low wear option in the treatment of intracapsular hip fractures requiring hemiarthroplasty. Acknowledgements The authors acknowledge the support of the Exeter Hip Research Team in organising patients’ appointments, searching for radiographs and providing outcome scores. The authors would like to thank the members of the Exeter Hip Unit for their tireless work following every patient; S. Wraight, S. Moore and L. Collett. References [1] NICE. The management of hip fracture in adults. National Clinical Guideline Centre; 2011. [2] Royal College of Physicians. The National Hip Fracture Database. 2015 [Available from: http://www.nhfd.co.uk/. [3] Petheram TG, Bone M, Joyce TJ, Serrano-Pedraza I, Reed MR. Partington P: surface finish of the Exeter Trauma Stem. Bone Joint J 2013;95-B(2):173–6. [4] Bidwa ASC, Willett K. Comparison of the Exeter Trauma Stem and the Thompson hemiarthroplasty for intracapsular hip fractures. Hip Int 2012;22 (6):655–60. [5] Cash D, Bayer J, Logan K, Wimhurst J. The Exeter trauma stem: early results of a new cemented hemiarthroplasty for femoral neck fracture. Br J Med Pract 2010;3(1):303–7. [6] Parker M. Cemented Thompson hemiarthroplasty versus cemented Exeter Trauma Stem (ETS) hemiarthroplasty for intracapsular hip fractures: a randomised trial of 200 patients. Injury 2012;43:807–10. [7] O'Neill G, Smyth J, Stark A, Ingram R. Early outcomes following Exeter Trauma Stem for intracapsular hip fractures. J Bone Joint Surg (Br) 2012;94-B (Suppl):32.
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[8] Sinclair MDJ, Pavlou P, Stuart S, Salter T, Harvey A. Exeter Trauma Stem: an early experience in a DGH. Injury Extra 2011;42:105–6. [9] Raut S, Parker MJ. Medium to long term follow up of a consecutive series of 604 Exeter Trauma Stem Hemiarthroplasties (ETS) for the treatment of displaced intracapsular femoral neck fractures. Injury 2016;47(3):721–4. [10] Gruen TA, McNeice GM, HC A. Modes of failure of cemented stem-type femoral components: radiographic study. Clin Orthop Relat Res 1979;141:17–27. [11] Kaplan EL, Meier P. Nonparametric estimation from incomplete observations. J Am Stat Assoc 1958;53(282):457–81. [12] Lettin AW, Ware HS, Morris RW. Survivorship analysis and confidence intervals: an assessment with reference to the Stanmore total knee replacement. J Bone Joint Surg Br 1991;73(5):729–31. [13] Murray DW, Carr AJ, Bulstrode C. Survival analysis of joint replacements. J Bone Joint Surg [Br] 1993;75(5):697–704. [14] Harris W. Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty. An end-result study using a new method of result evaluation. J Bone Joint Surg 1969;51(4):737–55. [15] Gjertsen SL JE, Vinje T, Engesaxter LB, Hallan G, Matre K, Furnes O. More reoperations after uncemented than cemented hemiarthroplasty used in the treatment of displaced fractures of the femoral neck. Bone Joint J 2012;94B:1113–9. [16] Azegami KG S, Parker MJ. Cemented versus uncemented hemiarthroplasty for hip fractures: a systematic review of randomised controlled trials. Hip Int 2011;21(5):509–17. [17] No authors listed. National Joint Replacement Registry: Hip and Knee Arthroplasty Annual Report. 2011. [18] Fowler GG JL, Lee AJC, Ling RSM. Experience with the Exeter total hip replacement since 1970. Orthop Clin North Am 1988;19:477–89. [19] Huiskes V R, Nivbrant B. Migration, Stem shape, and surface finish in cemented total hip arthroplasty. Clin Orthop Relat Res 1998;355:103–12. [20] Shen G. Femoral stem fixation: an engineering interpretation of the long term outcome of Charnley and Exeter stems. J Bone Jount Surg (Br) 1998;80-B:754– 6. [21] MIles SC AW, Bannister GC. The effect of the surface finish of the femoral component on load transmission in total hip replacement. J Bone Joint Surg (Br) 1990;72-B(Suppl):736. [22] Carrington NC, Sierra RJ, Gie GA, Hubble MJ, Timperley AJ, Howell JR. The Exeter Universal cemented femoral component at 15 to 17 years: an update on the first 325 hips. J Bone Joint Surg Br 2009;91(6):730–7. [23] Hook S, Moulder E, Yates PJ, Burston BJ, Whitley E, Bannister GC. The Exeter Universal stem: a minimum ten-year review from an independent centre. J Bone Joint Surg Br 2006;88(12):1584–90. [24] Williams HD, Browne G, Gie GA, Ling RS, Timperley AJ, Wendover NA. The Exeter universal cemented femoral component at 8 to 12 years: a study of the first 325 hips. J Bone Joint Surg Br 2002;84(3):324–34. [25] Young L, Duckett S, Dunn A. The use of the cemented Exeter Universal femoral stem in a District General Hospital: a minimum ten-year follow-up. J Bone Joint Surg Br 2009;91(2):170–5. [26] No authors listed. National Joint Registry: 12th Annual Report. 2015. [27] Petheram TG, Whitehouse SL, Kazi HA, Hubble MJ, Timperley AJ, Wilson MJ, et al. The Exeter Universal cemented femoral stem at 20 to 25 years: a report of 382 hips. Bone Joint J 2016;98-b(11):1441–9. [28] No authors listed. In: Ling R, editor. The Exeter Hip: 40 years of innovation in Total HIp Arthroplasty. Exeter Hip Publishing; 2010. [29] Howell LB JR, Doyle C, Hooper M, Lee AJC, Ling RSM. In vivo surface wear mechanisms of femoral components of cemented total hip arthroplasties. J Arthroplasty 2004;19(1):88–101. [30] Sheerlinck PC T. The design features of cemented femoral hip implants. Bone Joint J 2006;88-B:1409–18. [31] Bredahl C, Nyholm B, Hindsholm KB, Mortensen JS, Olesen AS. Mortality after hip fracture: results of operation within 12 h of admission. Injury 1992;23 (2):83–6. [32] Johnston AT, Barnsdale L, Smith R, Duncan K, Hutchison JD. Change in longterm mortality associated with fractures of the hip: evidence from the scottish hip fracture audit. J Bone Joint Surg Br 2010;92(7):989–93. [33] Norrish AR, Rao J, Parker MJ. Prosthesis survivorship and clinical outcome of the Austin Moore hemiarthroplasty: an 8-year mean follow-up of a consecutive series of 500 patients. Injury 2006;37(8):734–9. [34] Tanous T, Stephenson KW, Grecula MJ. Hip hemiarthroplasty after displaced femoral neck fracture: a survivorship analysis. Orthopedics 2010;33(6):385. [35] Chaplin VK, Matharu GS, Knebel RW. Complications following hemiarthroplasty for displaced intracapsular femoral neck fractures in the absence of routine follow-up. Ann R Coll Surg Engl 2013;95(4):271–4.
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