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Modular stem fracture at stem-sleeve junction after primary total hip arthroplasty
Journal of Orthopaedic Science xxx (2016) 1e4
Contents lists available at ScienceDirect
Journal of Orthopaedic Science journal homepage: http://www.elsevier.com/locate/jos
Case Report
Modular stem fracture at stem-sleeve junction after primary total hip arthroplasty Junya Yoshitani*, Takuya Nakamura, Yoshinobu Maruhashi, Takeshi Sasagawa, Kenichi Ueshima, Kiyonobu Funaki Department of Orthopedics Surgery, Toyama Prefectural Central Hospital, Japan
a r t i c l e i n f o Article history: Received 23 March 2016 Received in revised form 21 August 2016 Accepted 4 October 2016 Available online xxx
1. Introduction Modular stems have become an increasingly popular option due to the benefits provided by potential optimization of femoral anteversion, limb length, and femoral component offset. However, increased contact surfaces such as head-neck, neck-stem, and stem-sleeve, introduce potential for catastrophic failure due to corrosion, wear and fretting [1e6]. The S-ROM prosthesis first came to market in 1982 [7], and for Asian patients with smaller, narrower canals, the S-ROM-A femoral prosthesis was developed. The basic modular structure of the proximal sleeve component of the S-ROMA stem is the same as that of the S-ROM stem. Since their introduction, the S-ROM and S-ROM-A prostheses have shown stellar results in terms of clinical outcomes [8e10]. Only four cases of SROM failure at the stem-sleeve interface have been reported [1,5,6]. However, S-ROM-A stem failures at the stem-sleeve junction have not been reported. To our knowledge, this is the first report of an SROM-A stem failure at the stem-sleeve junction. The patient was informed that data concerning the case would be submitted for publication, and she consented. 2. Case report A 60-year-old physically active healthy woman, weight 49.6 kg, BMI 20.73, underwent primary THA of both hips for developmental
* Corresponding author. Department of Orthopedics Surgery, Toyama Prefectural Central Hospital, 2-2-78 Nishinagae, Toyama City, Toyama Prefecture, 930-8550, Japan. Fax: þ81 76 422 0667. E-mail address: [email protected] (J. Yoshitani).
dysplasia at age 50. The surgery on her left hip was conducted with S-ROM-A components and used a 13/7 mm femoral stem, 12B-small sleeve (both the stem and sleeve were made of Tie6Ale4V alloy), 28 3 mm cobalt-chromium head (DePuy, Warsaw, Indiana), highly cross linked polyethylene liner, and a 48 mm Trilogy cup (Zimmer, Warsaw, Indiana) (Fig. 1). The procedure was performed via a posterolateral approach, and no complications occurred intra and postoperatively. The stem and sleeve were strongly connected by a morse taper lock. Postoperatively, the patient was able to walk without restriction, and had no pain in her daily life. Ten years after implantation, when the patient was stretching with hip flexing, she complained of pain and heard an abnormal sound coming from her left hip. The patient had a normal erythrocyte sedimentation rate and c reactive protein. Serum metal ion levels showed a normal cobalt level of 0.5 ng/mL and a normal chromium level of less than 0.1 mg/dL. Plain radiography and computerized tomography demonstrated fracture of the stem in the sleeve (Fig. 2A and B). A revision using the previous surgical approach was conducted, and during this procedure, the proximal stem was easily removed from the sleeve due to a transverse stem fracture. The sleeve osseointegration was so tight that removal of the sleeve was difficult. The acetabular cup was well fixed, and the polyethylene liner was changed. There was no impingement scar on the polyethylene liner, no evidence of metal debris at the stem-sleeve junction, no osteolysis, and no pseudotumor noted in the operative field (Fig. 3). The appearance and surface morphology of the stem and sleeve were observed with a VHX-600 digital microscope (KEYENCE Company, Osaka, Japan) and an S-4800 scanning electron microscope (HITACHI Company, Tokyo, Japan). The stem was broken in the sleeve at approximately 115 mm from the stem end. Examination of the proximal stem surface showed extensive scratching and circumferential black debris. This was assumed to represent severe corrosion according to the subjective grading system developed by Goldberg et al. [11,12]. Fretting wear was observed at the trunnion surface, but there was no black debris (Fig. 4A and B). Macroscopic examination showed fatigue fracture, which occurred on the lateral side of the stem, due to cyclical loading. Analysis of electron microscopy of the fractured stem revealed fatigue striations that initiated laterally and progressed medially (Fig. 5A and B).
http://dx.doi.org/10.1016/j.jos.2016.10.003 0949-2658/© 2016 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.
Please cite this article in press as: Yoshitani J, et al., Modular stem fracture at stem-sleeve junction after primary total hip arthroplasty, Journal of Orthopaedic Science (2016), http://dx.doi.org/10.1016/j.jos.2016.10.003
2
J. Yoshitani et al. / Journal of Orthopaedic Science xxx (2016) 1e4
Fig. 3. (A) There is no evidence of metal debris and no pseudotumor in the operating field. (B) The retrieved stem shows a fracture several millimeters below the proximal end of the sleeve (✳ ¼ greater trochanter).
Fig. 1. Anteroposterior radiograph taken on the day of operation.
Fig. 4. (A) Proximal surface of the stem shows severe corrosion. (B) Fretting wear is observed at the trunnion surface.
Fig. 2. Radiography (A) and tomography (B) ten years after the primary arthroplasty identify the transverse fracture of the stem.
3. Discussion Modularity in THA has become an increasingly popular option for complex primary and revision cases due to the ability to adjust offset and limb length. However, there was an initial concern about the S-ROM stem because of possible fretting of the modular surfaces and possible failure of the stem at the modular junction [3,4].
Since its introduction in 1982, the S-ROM prosthesis has provided stellar clinical performance [8,9]. The femora of Asian developmental dysplasia of the hip patients have short anteverted necks associated with a small and narrow femoral canal. For those Asian patients, the S-ROM-A femoral prosthesis was developed and has been used since February 2004. The S-ROM-A femoral prosthesis has a shorter stem and more options for the shape of the stem neck with a smaller diameter compared with the S-ROM femoral prosthesis [10]. The size of the neck taper was also changed from 11/13 to 9/10 [13]. Both stem and sleeve are machined from forged Tie6Ale4V alloy, and the head ball is made from a cobaltchromium alloy or ceramic. A morse taper lock mechanism strongly connects the stem and sleeve, and manufacturer Depuy reported us that the stem and sleeve taper angles are the same. Charnley [14] have indicated that the incidence of stem fracture in the Charnley stem is 0.23%, making this a relatively rare complication. There are no reports of S-ROM-A stem fracture except three cases reported by the manufacturer Depuy. Nevertheless, all of these were distal to the stem. Four cases of S-ROM failure at the stem-sleeve interface have been reported in the literature [1,5,6]. Those reported were all relatively young men, from 50 to 61 years old, which suggests they were comparatively active patients. The latency periods until failure ranged from 5 months to 8.5 years from the primary operation. The stem diameters were the normal size e from 11 mm to 15 mm e however, the neck lengths were all high offset e 36 þ 6 mm or 36 þ 8 mm. In two cases, it was reported that
Please cite this article in press as: Yoshitani J, et al., Modular stem fracture at stem-sleeve junction after primary total hip arthroplasty, Journal of Orthopaedic Science (2016), http://dx.doi.org/10.1016/j.jos.2016.10.003
J. Yoshitani et al. / Journal of Orthopaedic Science xxx (2016) 1e4
3
Fig. 5. (A) Fatigue fracture, which has occurred on the lateral side of the stem (black arrow) and progresses medially. (B) Fractured stems show fatigue striations (black arrow shows the striation direction) that initiate laterally and progress medially.
macroscopic examination showed fretting and corrosion of the fractured surface. It is probable that constant cyclical loading on the modular interface forms microcracks at corrosive areas that lead to stem failure [1,5,6]. Mehran et al. [5] reported that fretting is the most common and unavoidable danger in modular stem failure. Previous fatigue tests of the S-ROM modular hip stem showed that all S-ROM stems which failed in the load test failed above 6BW, at the stem-sleeve junction, and the crack initiated on the lateral side (subject to tension) and progressed toward the medial side (subject to compression). For all specimens that failed within the sleeve, fretting damage was detected on the side where the fracture initiated [15]. Cook et al. [16] showed in a laboratory test for torsional resistance of the S-ROM that the stem-sleeve interface failed before the bone-sleeve interface. A significant decrease in the torsional resistance was found after contamination of the stemsleeve interface, as this increased the potential for disruption of the morse taper lock. According to these case reports and previous loading tests in vitro, it is presumable that the risk factors for fracture of the S-ROM stem at the stem-sleeve interface are: (1) decrease of torsional resistance due to contamination of the stemsleeve interface; (2) fretting corrosion; (3) high offset; and (4) high activity. In the present case, bone and sleeve osseointegration was extensive, and the distal stem from the fractured site was connected with the sleeve tightly, although the proximal stem was easily removed from the sleeve. This suggests that the stem and sleeve did not connect proximally at the morse taper lock, and there was a crevice in the stem-sleeve interface. Due to fluid accumulation in the crevice and morse taper lock disruption, it is possible that fretting occurred. In this case, serum cobalt and chromium ion level were normal, it is because there was no evidence of corrosion at the head-neck junction which were made of cobalt-chrome and titanium alloy. The galvanic effect also could occur with corrosion at the modular surface. Nevertheless, both the stem and the sleeve of the S-ROM-A were made of titanium alloy. Mehran et al. [5] reported that by using a single alloy throughout the prosthesis, one would expect to reduce this described corrosive force. This provides additional support for the notion that corrosion at the stem-sleeve interface in this case was due to fretting and not galvanic, and this is also supported by macroscopic examination that suggests fretting corrosion. At the stem-sleeve interface of the S-ROM-A prosthesis, the stem and the sleeve are connected by a morse taper lock. The surface roughness of the stem is satin, and the surface inside the sleeve is smooth. Nevertheless, laboratory tests of tribology between the stem and sleeve surface-roughness of the S-ROM-A have not been reported. A previous case report describes failure after 5 months of operation [1]. The reason for this failure might be a lack of intraoperative connection strength between the stem and sleeve.
It is important to lock the stem strongly to the sleeve of the S-ROM intraoperative. Regarding the failure process, analysis of the fractured stem by electron microscopy in the present case supports Kryger's loading test [15]. The crack initiated on the lateral side and progressed toward the medial side. Because the extension force in the lateral side and the compression force in the medial side increase with the length of the offset, high offset can introduce increased potential for stem fracture. The activity level of this patient was not quite at the level of playing sports, but she did exercise every day, and she had higher activity levels than a healthy person of the same age. This high activity level might also be a risk factor. Furthermore, the stem diameter was only 7 mm, characteristic of the S-ROM-A stem, although a 15 mm diameter stem failed in a previous case report [1]. It is possible that the 7 mm slim stem was also a risk factor for SROM-A stem fracture at the stem-sleeve interface. 4. Conclusion While the S-ROM prosthesis has the benefit of modularity, there is a danger that occurs fretting and corrosion due to the increased metal surface. Fretting, larger offsets, high activity and smaller stem diameter might be responsible for an increased risk of stem fracture. Stem fracture at the stem-sleeve interface of the S-ROM-A is a rare complication. However the S-ROM-A has the option of a small stem diameter, so we should be aware of the possibility of stem fracture when patients have some additional risk factors. Conflict of interest The authors declare that they have no conflict of interest. References [1] Patel A, Bliss J, Calfee RP, Froehlich J, Limbird R. Modular femoral stem-sleeve junction failure after primary total hip arthroplasty. J Arthroplasty 2009 Oct;24(7):1143.e1e5. [2] Huot Carlson JC, Van Citters DW, Currier JH, Bryant AM, Mayor MB, Collier JP. Femoral stem fracture and in vivo corrosion of retrieved modular femoral hips. J Arthroplasty 2012 Aug;27(7):1389e1396.e1. [3] Abdullah Kassim. In: Cakaj Shkelzen, editor. Study of factors affecting taper joint failures in modular hip implant using finite element modelling, modeling simulation and optimization e focus on applications. InTech; 2010, ISBN 978953-307-055-1. http://dx.doi.org/10.5772/8973. Available from: http://www. intechopen.com/books/modeling-simulation-and-optimization-focus-onapplications/study-of-factors-affecting-taper-joint-failures-in-modular-hipimplant-using-finite-element-modellin. [4] Collier JP, Surprenant VA, Jensen RE, Mayor MB, Surprenant HP. Corrosion between the components of modular femoral hip prostheses. J Bone Jt Surg Br 1992 Jul;74(4):511e7. [5] Mehran N, North T, Laker M. Failure of a modular hip implant at the stemsleeve interface. Orthopedics 2013 Jul;36(7):e978e81.
Please cite this article in press as: Yoshitani J, et al., Modular stem fracture at stem-sleeve junction after primary total hip arthroplasty, Journal of Orthopaedic Science (2016), http://dx.doi.org/10.1016/j.jos.2016.10.003
4
J. Yoshitani et al. / Journal of Orthopaedic Science xxx (2016) 1e4
[6] Parisi T, Burroughs B, Kwon YM. Modular hip implant fracture at the stemsleeve interface. Orthopedics 2015 Mar;38(3):e234e9. [7] Spitzer AI. The S-ROM cementless femoral stem: history and literature review. Orthopedics 2005 Sep;28(9 suppl):s1117e24. [8] Christie MJ, DeBoer DK, Trick LW, Brothers JC, Jones RE, Vise GT, Gruen TA. Primary total hip arthroplasty with use of the modular S-ROM prosthesis. Four to seven-year clinical and radiographic results. J Bone Jt Surg Am 1999 Dec;81(12):1707e16. [9] Drexler M, Dwyer T, Marmor M, Abolghasemian M, Chakravertty R, Chechik O, Cameron HU. Nineteen year results of THA using modular 9 mm S-ROM femoral component in patients with small femoral canals. J Arthroplasty 2013 Oct;28(9):1667e70. [10] Kido K, Fujioka M, Takahashi K, Ueshima K, Goto T, Kubo T. Short-term results of the S-ROM-A femoral prosthesis operative strategies for Asian patients with osteoarthritis. J Arthroplasty 2009 Dec;24(8):1193e9.
[11] Goldberg JR, Gilbert JL, Jacobs JJ, Bauer TW, Paprosky W, Leurgans S. A multicenter retrieval study of the taper interfaces of modular hip prostheses. Clin Orthop Relat Res 2002 Aug;(401):149e61. [12] Fraitzl CR, Moya LE, Castellani L, Wright TM, Buly RL. Corrosion at the stemsleeve interface of a modular titanium alloy femoral component as a reason for impaired disengagement. J Arthroplasty 2011 Jan;26(1):113e9. [13] Tamegai H, Otani T, Fujii H, Kawaguchi Y, Hayama T, Marumo K. A modified SROM stem in primary total hip arthroplasty for developmental dysplasia of the hip. J Arthroplasty 2013 Dec;28(10):1741e5. [14] Charnley J. Fracture of femoral prostheses in total hip replacement. A clinical study. Clin Orthop Relat Res 1975 Sep;(111):105e20. [15] Krygier JJ, Dujovne AR, Bobyn JD. Fatigue behavior of titanium femoral hip prosthesis with proximal sleeve stem modularity. J Appl Biomater 1994;5(3):195e201. [16] Cook SD, Manely MT, Kester MA, Dong NG. Torsional resistance modular sleeve-stem hip system. Clin Mater 1993;12(3):153e8.
Please cite this article in press as: Yoshitani J, et al., Modular stem fracture at stem-sleeve junction after primary total hip arthroplasty, Journal of Orthopaedic Science (2016), http://dx.doi.org/10.1016/j.jos.2016.10.003
Contents lists available at ScienceDirect
Journal of Orthopaedic Science journal homepage: http://www.elsevier.com/locate/jos
Case Report
Modular stem fracture at stem-sleeve junction after primary total hip arthroplasty Junya Yoshitani*, Takuya Nakamura, Yoshinobu Maruhashi, Takeshi Sasagawa, Kenichi Ueshima, Kiyonobu Funaki Department of Orthopedics Surgery, Toyama Prefectural Central Hospital, Japan
a r t i c l e i n f o Article history: Received 23 March 2016 Received in revised form 21 August 2016 Accepted 4 October 2016 Available online xxx
1. Introduction Modular stems have become an increasingly popular option due to the benefits provided by potential optimization of femoral anteversion, limb length, and femoral component offset. However, increased contact surfaces such as head-neck, neck-stem, and stem-sleeve, introduce potential for catastrophic failure due to corrosion, wear and fretting [1e6]. The S-ROM prosthesis first came to market in 1982 [7], and for Asian patients with smaller, narrower canals, the S-ROM-A femoral prosthesis was developed. The basic modular structure of the proximal sleeve component of the S-ROMA stem is the same as that of the S-ROM stem. Since their introduction, the S-ROM and S-ROM-A prostheses have shown stellar results in terms of clinical outcomes [8e10]. Only four cases of SROM failure at the stem-sleeve interface have been reported [1,5,6]. However, S-ROM-A stem failures at the stem-sleeve junction have not been reported. To our knowledge, this is the first report of an SROM-A stem failure at the stem-sleeve junction. The patient was informed that data concerning the case would be submitted for publication, and she consented. 2. Case report A 60-year-old physically active healthy woman, weight 49.6 kg, BMI 20.73, underwent primary THA of both hips for developmental
* Corresponding author. Department of Orthopedics Surgery, Toyama Prefectural Central Hospital, 2-2-78 Nishinagae, Toyama City, Toyama Prefecture, 930-8550, Japan. Fax: þ81 76 422 0667. E-mail address: [email protected] (J. Yoshitani).
dysplasia at age 50. The surgery on her left hip was conducted with S-ROM-A components and used a 13/7 mm femoral stem, 12B-small sleeve (both the stem and sleeve were made of Tie6Ale4V alloy), 28 3 mm cobalt-chromium head (DePuy, Warsaw, Indiana), highly cross linked polyethylene liner, and a 48 mm Trilogy cup (Zimmer, Warsaw, Indiana) (Fig. 1). The procedure was performed via a posterolateral approach, and no complications occurred intra and postoperatively. The stem and sleeve were strongly connected by a morse taper lock. Postoperatively, the patient was able to walk without restriction, and had no pain in her daily life. Ten years after implantation, when the patient was stretching with hip flexing, she complained of pain and heard an abnormal sound coming from her left hip. The patient had a normal erythrocyte sedimentation rate and c reactive protein. Serum metal ion levels showed a normal cobalt level of 0.5 ng/mL and a normal chromium level of less than 0.1 mg/dL. Plain radiography and computerized tomography demonstrated fracture of the stem in the sleeve (Fig. 2A and B). A revision using the previous surgical approach was conducted, and during this procedure, the proximal stem was easily removed from the sleeve due to a transverse stem fracture. The sleeve osseointegration was so tight that removal of the sleeve was difficult. The acetabular cup was well fixed, and the polyethylene liner was changed. There was no impingement scar on the polyethylene liner, no evidence of metal debris at the stem-sleeve junction, no osteolysis, and no pseudotumor noted in the operative field (Fig. 3). The appearance and surface morphology of the stem and sleeve were observed with a VHX-600 digital microscope (KEYENCE Company, Osaka, Japan) and an S-4800 scanning electron microscope (HITACHI Company, Tokyo, Japan). The stem was broken in the sleeve at approximately 115 mm from the stem end. Examination of the proximal stem surface showed extensive scratching and circumferential black debris. This was assumed to represent severe corrosion according to the subjective grading system developed by Goldberg et al. [11,12]. Fretting wear was observed at the trunnion surface, but there was no black debris (Fig. 4A and B). Macroscopic examination showed fatigue fracture, which occurred on the lateral side of the stem, due to cyclical loading. Analysis of electron microscopy of the fractured stem revealed fatigue striations that initiated laterally and progressed medially (Fig. 5A and B).
http://dx.doi.org/10.1016/j.jos.2016.10.003 0949-2658/© 2016 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.
Please cite this article in press as: Yoshitani J, et al., Modular stem fracture at stem-sleeve junction after primary total hip arthroplasty, Journal of Orthopaedic Science (2016), http://dx.doi.org/10.1016/j.jos.2016.10.003
2
J. Yoshitani et al. / Journal of Orthopaedic Science xxx (2016) 1e4
Fig. 3. (A) There is no evidence of metal debris and no pseudotumor in the operating field. (B) The retrieved stem shows a fracture several millimeters below the proximal end of the sleeve (✳ ¼ greater trochanter).
Fig. 1. Anteroposterior radiograph taken on the day of operation.
Fig. 4. (A) Proximal surface of the stem shows severe corrosion. (B) Fretting wear is observed at the trunnion surface.
Fig. 2. Radiography (A) and tomography (B) ten years after the primary arthroplasty identify the transverse fracture of the stem.
3. Discussion Modularity in THA has become an increasingly popular option for complex primary and revision cases due to the ability to adjust offset and limb length. However, there was an initial concern about the S-ROM stem because of possible fretting of the modular surfaces and possible failure of the stem at the modular junction [3,4].
Since its introduction in 1982, the S-ROM prosthesis has provided stellar clinical performance [8,9]. The femora of Asian developmental dysplasia of the hip patients have short anteverted necks associated with a small and narrow femoral canal. For those Asian patients, the S-ROM-A femoral prosthesis was developed and has been used since February 2004. The S-ROM-A femoral prosthesis has a shorter stem and more options for the shape of the stem neck with a smaller diameter compared with the S-ROM femoral prosthesis [10]. The size of the neck taper was also changed from 11/13 to 9/10 [13]. Both stem and sleeve are machined from forged Tie6Ale4V alloy, and the head ball is made from a cobaltchromium alloy or ceramic. A morse taper lock mechanism strongly connects the stem and sleeve, and manufacturer Depuy reported us that the stem and sleeve taper angles are the same. Charnley [14] have indicated that the incidence of stem fracture in the Charnley stem is 0.23%, making this a relatively rare complication. There are no reports of S-ROM-A stem fracture except three cases reported by the manufacturer Depuy. Nevertheless, all of these were distal to the stem. Four cases of S-ROM failure at the stem-sleeve interface have been reported in the literature [1,5,6]. Those reported were all relatively young men, from 50 to 61 years old, which suggests they were comparatively active patients. The latency periods until failure ranged from 5 months to 8.5 years from the primary operation. The stem diameters were the normal size e from 11 mm to 15 mm e however, the neck lengths were all high offset e 36 þ 6 mm or 36 þ 8 mm. In two cases, it was reported that
Please cite this article in press as: Yoshitani J, et al., Modular stem fracture at stem-sleeve junction after primary total hip arthroplasty, Journal of Orthopaedic Science (2016), http://dx.doi.org/10.1016/j.jos.2016.10.003
J. Yoshitani et al. / Journal of Orthopaedic Science xxx (2016) 1e4
3
Fig. 5. (A) Fatigue fracture, which has occurred on the lateral side of the stem (black arrow) and progresses medially. (B) Fractured stems show fatigue striations (black arrow shows the striation direction) that initiate laterally and progress medially.
macroscopic examination showed fretting and corrosion of the fractured surface. It is probable that constant cyclical loading on the modular interface forms microcracks at corrosive areas that lead to stem failure [1,5,6]. Mehran et al. [5] reported that fretting is the most common and unavoidable danger in modular stem failure. Previous fatigue tests of the S-ROM modular hip stem showed that all S-ROM stems which failed in the load test failed above 6BW, at the stem-sleeve junction, and the crack initiated on the lateral side (subject to tension) and progressed toward the medial side (subject to compression). For all specimens that failed within the sleeve, fretting damage was detected on the side where the fracture initiated [15]. Cook et al. [16] showed in a laboratory test for torsional resistance of the S-ROM that the stem-sleeve interface failed before the bone-sleeve interface. A significant decrease in the torsional resistance was found after contamination of the stemsleeve interface, as this increased the potential for disruption of the morse taper lock. According to these case reports and previous loading tests in vitro, it is presumable that the risk factors for fracture of the S-ROM stem at the stem-sleeve interface are: (1) decrease of torsional resistance due to contamination of the stemsleeve interface; (2) fretting corrosion; (3) high offset; and (4) high activity. In the present case, bone and sleeve osseointegration was extensive, and the distal stem from the fractured site was connected with the sleeve tightly, although the proximal stem was easily removed from the sleeve. This suggests that the stem and sleeve did not connect proximally at the morse taper lock, and there was a crevice in the stem-sleeve interface. Due to fluid accumulation in the crevice and morse taper lock disruption, it is possible that fretting occurred. In this case, serum cobalt and chromium ion level were normal, it is because there was no evidence of corrosion at the head-neck junction which were made of cobalt-chrome and titanium alloy. The galvanic effect also could occur with corrosion at the modular surface. Nevertheless, both the stem and the sleeve of the S-ROM-A were made of titanium alloy. Mehran et al. [5] reported that by using a single alloy throughout the prosthesis, one would expect to reduce this described corrosive force. This provides additional support for the notion that corrosion at the stem-sleeve interface in this case was due to fretting and not galvanic, and this is also supported by macroscopic examination that suggests fretting corrosion. At the stem-sleeve interface of the S-ROM-A prosthesis, the stem and the sleeve are connected by a morse taper lock. The surface roughness of the stem is satin, and the surface inside the sleeve is smooth. Nevertheless, laboratory tests of tribology between the stem and sleeve surface-roughness of the S-ROM-A have not been reported. A previous case report describes failure after 5 months of operation [1]. The reason for this failure might be a lack of intraoperative connection strength between the stem and sleeve.
It is important to lock the stem strongly to the sleeve of the S-ROM intraoperative. Regarding the failure process, analysis of the fractured stem by electron microscopy in the present case supports Kryger's loading test [15]. The crack initiated on the lateral side and progressed toward the medial side. Because the extension force in the lateral side and the compression force in the medial side increase with the length of the offset, high offset can introduce increased potential for stem fracture. The activity level of this patient was not quite at the level of playing sports, but she did exercise every day, and she had higher activity levels than a healthy person of the same age. This high activity level might also be a risk factor. Furthermore, the stem diameter was only 7 mm, characteristic of the S-ROM-A stem, although a 15 mm diameter stem failed in a previous case report [1]. It is possible that the 7 mm slim stem was also a risk factor for SROM-A stem fracture at the stem-sleeve interface. 4. Conclusion While the S-ROM prosthesis has the benefit of modularity, there is a danger that occurs fretting and corrosion due to the increased metal surface. Fretting, larger offsets, high activity and smaller stem diameter might be responsible for an increased risk of stem fracture. Stem fracture at the stem-sleeve interface of the S-ROM-A is a rare complication. However the S-ROM-A has the option of a small stem diameter, so we should be aware of the possibility of stem fracture when patients have some additional risk factors. Conflict of interest The authors declare that they have no conflict of interest. References [1] Patel A, Bliss J, Calfee RP, Froehlich J, Limbird R. Modular femoral stem-sleeve junction failure after primary total hip arthroplasty. J Arthroplasty 2009 Oct;24(7):1143.e1e5. [2] Huot Carlson JC, Van Citters DW, Currier JH, Bryant AM, Mayor MB, Collier JP. Femoral stem fracture and in vivo corrosion of retrieved modular femoral hips. J Arthroplasty 2012 Aug;27(7):1389e1396.e1. [3] Abdullah Kassim. In: Cakaj Shkelzen, editor. Study of factors affecting taper joint failures in modular hip implant using finite element modelling, modeling simulation and optimization e focus on applications. InTech; 2010, ISBN 978953-307-055-1. http://dx.doi.org/10.5772/8973. Available from: http://www. intechopen.com/books/modeling-simulation-and-optimization-focus-onapplications/study-of-factors-affecting-taper-joint-failures-in-modular-hipimplant-using-finite-element-modellin. [4] Collier JP, Surprenant VA, Jensen RE, Mayor MB, Surprenant HP. Corrosion between the components of modular femoral hip prostheses. J Bone Jt Surg Br 1992 Jul;74(4):511e7. [5] Mehran N, North T, Laker M. Failure of a modular hip implant at the stemsleeve interface. Orthopedics 2013 Jul;36(7):e978e81.
Please cite this article in press as: Yoshitani J, et al., Modular stem fracture at stem-sleeve junction after primary total hip arthroplasty, Journal of Orthopaedic Science (2016), http://dx.doi.org/10.1016/j.jos.2016.10.003
4
J. Yoshitani et al. / Journal of Orthopaedic Science xxx (2016) 1e4
[6] Parisi T, Burroughs B, Kwon YM. Modular hip implant fracture at the stemsleeve interface. Orthopedics 2015 Mar;38(3):e234e9. [7] Spitzer AI. The S-ROM cementless femoral stem: history and literature review. Orthopedics 2005 Sep;28(9 suppl):s1117e24. [8] Christie MJ, DeBoer DK, Trick LW, Brothers JC, Jones RE, Vise GT, Gruen TA. Primary total hip arthroplasty with use of the modular S-ROM prosthesis. Four to seven-year clinical and radiographic results. J Bone Jt Surg Am 1999 Dec;81(12):1707e16. [9] Drexler M, Dwyer T, Marmor M, Abolghasemian M, Chakravertty R, Chechik O, Cameron HU. Nineteen year results of THA using modular 9 mm S-ROM femoral component in patients with small femoral canals. J Arthroplasty 2013 Oct;28(9):1667e70. [10] Kido K, Fujioka M, Takahashi K, Ueshima K, Goto T, Kubo T. Short-term results of the S-ROM-A femoral prosthesis operative strategies for Asian patients with osteoarthritis. J Arthroplasty 2009 Dec;24(8):1193e9.
[11] Goldberg JR, Gilbert JL, Jacobs JJ, Bauer TW, Paprosky W, Leurgans S. A multicenter retrieval study of the taper interfaces of modular hip prostheses. Clin Orthop Relat Res 2002 Aug;(401):149e61. [12] Fraitzl CR, Moya LE, Castellani L, Wright TM, Buly RL. Corrosion at the stemsleeve interface of a modular titanium alloy femoral component as a reason for impaired disengagement. J Arthroplasty 2011 Jan;26(1):113e9. [13] Tamegai H, Otani T, Fujii H, Kawaguchi Y, Hayama T, Marumo K. A modified SROM stem in primary total hip arthroplasty for developmental dysplasia of the hip. J Arthroplasty 2013 Dec;28(10):1741e5. [14] Charnley J. Fracture of femoral prostheses in total hip replacement. A clinical study. Clin Orthop Relat Res 1975 Sep;(111):105e20. [15] Krygier JJ, Dujovne AR, Bobyn JD. Fatigue behavior of titanium femoral hip prosthesis with proximal sleeve stem modularity. J Appl Biomater 1994;5(3):195e201. [16] Cook SD, Manely MT, Kester MA, Dong NG. Torsional resistance modular sleeve-stem hip system. Clin Mater 1993;12(3):153e8.
Please cite this article in press as: Yoshitani J, et al., Modular stem fracture at stem-sleeve junction after primary total hip arthroplasty, Journal of Orthopaedic Science (2016), http://dx.doi.org/10.1016/j.jos.2016.10.003