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Cementless Bipolar Hemiarthroplasty Using a Micro-Arc Oxidation Coated Stem in Patients with Displaced Femoral Neck Fractures
The Journal of Arthroplasty xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Cementless Bipolar Hemiarthroplasty Using a Micro-Arc Oxidation Coated Stem in Patients with Displaced Femoral Neck Fractures Young-Kyun Lee, M.D. a, Ho-Yun Joung, M.D. a, Sang-Hwan Kim, M.D. a, Yong-Chan Ha, M.D. b, Kyung-Hoi Koo, M.D. c a
Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, 82 Gumi-ro, 173 Beon-gil, Bundang-gu, Seongnam 463-707, South Korea Department of Orthopaedic Surgery, Chung-Ang University College of Medicine, 224-1 Heukseok-dong, Dongjak-gu, Seoul 156-755, South Korea Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 82 Gumi-ro, 173 Beon-gil, Bundang-gu, Seongnam 463-707, South Korea
b c
a r t i c l e
i n f o
Article history: Received 6 January 2014 Accepted 16 April 2014 Available online xxxx Keywords: femoral neck fracture cementless stem surface treatment micro-arc oxidation hemiarthroplasty
a b s t r a c t Femoral stem fixation for displaced femoral neck fractures in osteoporotic patients is an ongoing debate. We evaluated the outcome of 136 cementless bipolar hemiarthroplasty using a Micro-arc oxidation (MAO) coated stem. All patients survived the procedure and were discharged from the hospital. Thirty- and 90-day mortality rates were 0.7% and 2.2%, respectively. Ninety-eight hips were followed for a minimum of 2 years (mean, 44 months) postoperatively. Three stems were revised because of a periprosthetic fracture. Although cortical stress shielding around the stem was observed in 3 hips, there was no loosening or osteolysis. Cementless bipolar hemiarthroplasty using a MAO-coated stem is a useful and safe option to treat displaced femoral neck fractures. © 2014 Elsevier Inc. All rights reserved.
Hemiarthroplasty is a useful treatment for displaced femoral neck fractures in osteoporotic patients [1,2]. Traditionally, cemented stems have been preferred than cementless stems in these fractures [3,4], because cementless fixation might lack the initial stability, which could lead to a failure of fixation [5,6]. However, cemented stems may cause an intraoperative embolism and subsequent cardiopulmonary complications [7], although these complications might be reduced with modern cementing techniques and close intraoperative monitoring [8]. Thus, the fixation method of stem has been debated in osteoporotic femurs [1,9,10]. Cementless stem designs have been improved [11], and several surface treatments have been introduced to enhance biologic fixation [12–17]. Satisfactory results were reported after the use of contemporary cementless stems in senile patients with osteoporosis [18–21]. Micro-arc oxidation (MAO) is an electrochemical oxidation with a high voltage spark treatment in an alkaline electrolyte, forming nanoporous pits and thick oxide layers on the metal surface [12,13,22,23]. This process is available for surfaces of aluminum, titanium, zirconium, and their alloys. It enhances wear and corrosion resistance as well as prolonging component lifetime. It also incorporates calcium and phosphorus into the coating layer, resulting in an
The Conflict of Interest statement associated with this article can be found at http:// dx.doi.org/10.1016/j.arth.2014.04.020. Reprint requests: Yong-Chan Ha, Department of Orthopaedic Surgery, Chung-Ang University College of Medicine, 224-1 Heukseok-dong, Dongjak-gu, Seoul 156-755, South Korea.
enhanced bone on-growth of cementless implants [12,13,22,23]. However, there is no clinical study to support the effectiveness of MAO-coated stem. The purpose of this study was to evaluate clinical and radiological results of cementless bipolar hemiarthroplasty using an MAO-coated stem in senile patients with displaced femoral neck fracture. Materials and Methods From March 2007 to July 2010, 134 patients (136 hips) aged 65 years or older, who were diagnosed as having a displaced femoral neck fracture, were treated with bipolar hemiarthroplasty using a MAO-coated stem at two hospitals (Seoul National University Bundang Hospital and Chung-Ang University Hospital). There were 28 men and 106 women, and their mean age at the time of surgery was 78.4 years (range, 65–108 years). The mean body mass index was 21.2 kg/m 2 (range, 12.9–29.8 kg/m 2) and the mean American Society of Anesthesiologists score was 2.4 (range 1–4). A cementless stem design (Bencox stem; CORENTEC, Cheonan, Korea) was used. This is a double-tapered, rectangular-shaped titanium stem. The stem is composed of a titanium alloy and the surface is extensively treated with MAO, maintaining average 5.5 micron of surface roughness. The acetabular component is a cobalt-chromium cup (IC Bipolar Head, Implantcast GmbH, Buxtehude, Germany), which has a UHMWPE liner inside. (Fig. 1) The operation was performed under regional anesthesia in 117 and general anesthesia in 19 hips. All operations were carried out
http://dx.doi.org/10.1016/j.arth.2014.04.020 0883-5403/© 2014 Elsevier Inc. All rights reserved.
Please cite this article as: Lee Y-K, et al, Cementless Bipolar Hemiarthroplasty Using a Micro-Arc Oxidation Coated Stem in Patients with Displaced Femoral Neck Fractures, J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.04.020
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Y-K. Lee et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx
of the femoral stem, the acetabular erosion and cortical porosis around femoral stem [26], leg length discrepancy and heterotopic ossification. The stability of the femoral stem was classified with use of the method of Engh et al. [27]. The osteolytic lesions were defined according the criteria of Engh et al. [28]. The lesions were recorded according to the seven zones described by Gruen et al. [29]. Evidence of spot welding and reactive lines was documented in each of the Gruen zones [29]. Spot welds were defined as bone densification and trabecular streaming between the cortex and the implant [30]. Subsidence of the femoral stem was defined as the change in the distance from the superolateral edge at the shoulder of the prosthesis to the tip of the greater trochanter on the anteroposterior radiograph of the hip [31]. Cortical porosis was defined as a loss of endosteal bone and a decrease in bone mineralization resulting in a homogeneous but somewhat sparse (washed-out) appearance of the remaining cortex [24,26]. For the evaluation of leg-length, we measured the distance between the inter-teardrop line and the lower margin of the lesser trochanter. The distances of the operated limb and the contralateral limb were compared and the difference N 2 cm was defined as the failure of leg length equalization [32]. Heterotopic ossification was evaluated according to the system of Brooker et al. [33], if present. The design and protocol of this retrospective study were approved by the institutional review board in each hospital, and all informed consent was waived due to the retrospective nature of the study.
Fig. 1. The Bencox stem is a double-tapered, rectangular titanium stem without collar and extensive MAO-coating on the surface.
through the posterolateral approach. After rasping the endosteal cavity in the proximal femur, a stem trial was inserted to check the size of stem, stability and leg length as described previously [24]. Once an optimal stem size was determined, a real stem was press-fitted into the femoral canal. Proximal femoral cracks occurred in 2 hips during the insertion of stem, which were treated with cerclage wires. There were no anesthesia-related complications. The mean operating time was 81.4 minutes (range, 30–120 minutes) and the mean estimated blood loss was 321.5 mL (range, 100–500 mL). Patients were instructed to stand and walk using an assistive device (walker, crutches, or cane) with tolerable weight-bearing on the third postoperative day. As the walking ability improved, the assistive device was changed by physical therapist. To prevent thromboembolism, thigh-length antiembolic stockings were applied and ankle pump was encouraged in bed during the hospitalization. The mean hospital stay was 17.1 days (range, 6 to 85 days) and no patients died during the hospitalization. Patients who necessitated further physical therapy and/or nursing care were transferred to rehabilitation department or other institutions. Follow-up evaluations were performed at six weeks; at three, six, nine, and twelve months, and every year thereafter. Two nurses and one private locator visited patients who were unable to return for the follow-up evaluations. Some patients were contacted by telephone interview and they were asked to send recent follow-up radiographs. The walking ability was evaluated by using the Koval’s categories [25]. The radiographs were evaluated by two independent observers who did not participate in the operation. The six-week anteroposterior and cross-table lateral radiographs were considered to be the baseline studies for comparison. The serial radiographic evaluation included an assessment of the stability, osteolysis around femoral stem, subsidence
Fig. 2. (A) A 73 year-old women, who had undergone a hemiarthroplasty for femoral neck fracture using MAO-coated cementless stem, sustained a periprosthetic fracture at postoperative 3 years and 3 months. (B) On radiograph obtained 2 years 6 months after the revision of stem, the revised stem is well fixed.
Please cite this article as: Lee Y-K, et al, Cementless Bipolar Hemiarthroplasty Using a Micro-Arc Oxidation Coated Stem in Patients with Displaced Femoral Neck Fractures, J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.04.020
Y-K. Lee et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx
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Results At the time of discharge, 62 (64.6 %) patients could independently ambulate with or without an assistive device. Twelve patients (12 hips) were lost to follow-up, and 26 patients (26 hips) died before a minimum follow-up of 2 years; 1 patient died within 30 days, 3 patients died within 90 days, 16 patients died between 90 days and 1 year, and 6 patients between 1 year and 2 years postoperatively. The remaining 96 patients (98 hips) were followed for more than 2 years postoperatively (mean, 44 months; range, 24–72 months). Among them, radiographic analysis was available in 70 hips. There was no readmission within 30 days. There was no dislocation or periprosthetic joint infection during the follow-up period. Periprosthetic femoral fractures occurred in 3 patients at 2.9–3.3 years postoperatively. One fracture was stabilized with cerclage wires and the remaining two fractures were treated with a stem revision (Fig. 2). Three patients had activity-related thigh pain, but did not require any medication. Comparing the ambulatory abilities before the fracture and at the final follow-up based on the Koval Categories [25], the ability dropped by 1 level in 14 patients (14.6 %), by 2 levels in 5 (5.2 %), by 3 levels in 8 (8.3 %), and by 4 or more levels in 14 (14.6 %). Nineteen patients (19.8 %); 9 community ambulatories and 10 household ambulatories before fracture became nonfunctional ambulatories due to medical co-morbidities at the final follow-up, although they did not have any discomforts in the hips. (Fig. 3). In 1 patient, a subsidence of the femoral stem was observed by 7 mm at 6 weeks radiograph postoperatively, which was not progressive on later radiographs. There was no failure of leg length equalization. At the latest radiographs, no hip had any sign of loosening or osteolysis (Fig. 4). Cortical porosis was seen around the stem in 3 hips (Fig. 5). These 3 hips had spot weld in Gruen zone 2, 3, 5, and 6, and thought to have a bone-ingrown stability. Two hips had a reactive line at Gruen zone 1 and 7, which was not progressive. Two hips had an acetabular erosion by less than 2 mm. Brooker grade I heterotopic ossification was seen in 1 hip (1.0 %). Discussion In our study, a cementless bipolar hemiarthroplasty with use of an MAO-coated tapered stem provided satisfactory clinical and radiological results, and was associated with few complications in displaced neck fractures of osteoporotic femur. The result is compatible with previously reported outcomes of hemiarthroplasty using cemented stems [3,34,35]. Thirty- and 90-day mortality rates (0.7% and 2.2%) in our study were lower than those (4 to 7 %, and 5 to 24 %) of previous studies
Fig. 3. Ambulatory change between preinjury and final follow-up.
Fig. 4. (A) A 71-year-old woman with a displaced femoral neck fracture underwent a hemiarthroplasty using MAO-coated cementless stem. (B) On anteroposterior radiographs obtained 5 years postoperatively, the stem is well fixed with a stable bone ingrowth.
[36–40], although we could not directly compare with the results of other studies, because we could not adjust comorbidities. Our findings, about 20% nonfunctional ambulatories of the patients at the last follow-up, was compatible with those (6–40%) of previous studies [25,38,41]. Some studies reported that the cementless arthroplasty is associated with an increased risk of periprosthetic fracture [10,42]. In our study, there were 3 periprosthetic fractures during the follow-up. However, we could not determine whether these fractures were related with the fixation method due to lack of the control group. Because osteosynthesis of displaced femoral neck fractures in osteoporotic patients requires a prolonged protection from weight bearing, and has concerns such as loss of initial stability, some authors have recommended cemented hemiarthroplasty to avoid these problems and to return patients to their prefracture level of activity quickly [3,34,35]. However, the cementation increases the risk of cardiopulmonary complications, particularly in elderly patients with osteoporosis [7,43]. The stem in this study was a tapered rectangular stem with an extensive MAO-coating. It fits into the meta-diaphyseal junction, which enables an initial stability and long-term biologic fixation even in osteoporotic proximal femur [12,13,22,23,44–47], and actually avoids the cement-related cardiopulmonary complications [48]. In our study, 3 patients (3.1 %) showed cortical porosis around the femoral stem. There might be some explanations for the porosis. It
Please cite this article as: Lee Y-K, et al, Cementless Bipolar Hemiarthroplasty Using a Micro-Arc Oxidation Coated Stem in Patients with Displaced Femoral Neck Fractures, J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.04.020
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Y-K. Lee et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx
Fig. 5. (A) A 91-year-old woman with a displaced femoral neck fracture underwent a hemiarthroplasty using MAO-coated cementless stem. (B) An anteroposterior radiograph obtained 2 years postoperatively shows cortical porosis around the stem. However, there is no loosening sign around the femoral stem.
could be a stress shielding after the use of a cementless stem, and/or a cortical thinning due to an aging phenomenon [24,49,50]. The cortical porosis did not threaten the stability of the stems for 2–6 years postoperatively. We should address several limitations of our study. Our study was a retrospective with a short follow-up period. However, a long-term follow-up study is barely possible, because senile patients have a short life expectancy. We did not use cemented stem during the study period because we were concerned about the cement-related adverse effects. Accordingly, there was no comparison with cemented hemiarthroplasty. Despite these limitations, this is the first study which showed the results of an extensively MAO-coated cementless stem. Hemiarthroplasty using this type of stem design is a safe and satisfactory option to treat displaced femoral neck fractures in osteoporotic patients. References 1. Figved W, Opland V, Frihagen F, et al. Cemented versus uncemented hemiarthroplasty for displaced femoral neck fractures. Clin Orthop Relat Res 2009;9:2426. 2. Zi-Sheng A, You-Shui G, Zhi-Zhen J, et al. Hemiarthroplasty vs primary total Hip arthroplasty for displaced fractures of the femoral neck in the elderly: a metaanalysis. J Arthroplasty 2012;4:583. 3. Haidukewych GJ, Israel TA, Berry DJ. Long-term survivorship of cemented bipolar hemiarthroplasty for fracture of the femoral neck. Clin Orthop Relat Res 2002;403:118. 4. Ahn J, Man LX, Park S, et al. Systematic review of cemented and uncemented hemiarthroplasty outcomes for femoral neck fractures. Clin Orthop Relat Res 2008;10:2513.
5. Bottner F, Zawadsky M, Su EP, et al. Implant migration after early weightbearing in cementless hip replacement. Clin Orthop Relat Res 2005;436:132. 6. Rao RR, Sharkey PF, Hozack WJ, et al. Immediate weightbearing after uncemented total hip arthroplasty. Clin Orthop Relat Res 1998;349:156. 7. Parvizi J, Ereth MH, Lewallen DG. Thirty-day mortality following hip arthroplasty for acute fracture. J Bone Joint Surg Am 2004;9:1983. 8. Randall RL, Aoki SK, Olson PR, et al. Complications of cemented long-stem hip arthroplasties in metastatic bone disease. Clin Orthop Relat Res 2006:287. 9. Parker MI, Pryor G, Gurusamy K. Cemented versus uncemented hemiarthroplasty for intracapsular hip fractures: A randomised controlled trial in 400 patients. J Bone Joint Surg (Br) 2010;1:116. 10. Gjertsen JE, Lie SA, Vinje T, et al. 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Clin Orthop Relat Res 2004;421:143. 32. Woolson ST, Hartford JM, Sawyer A. Results of a method of leg-length equalization for patients undergoing primary total hip replacement. J Arthroplasty 1999;2:159. 33. Brooker AF, Bowerman JW, Robinson RA, et al. Ectopic ossification following total hip replacement. Incidence and a method of classification. J Bone Joint Surg Am 1973;8:1629. 34. Chandran P, Azzabi M, Burton DJ, et al. Mid term results of Furlong LOL uncemented hip hemiarthroplasty for fractures of the femoral neck. Acta Orthop Belg 2006;4:428. 35. Eiskjaer S, Gelineck J, Soballe K. Fractures of the femoral neck treated with cemented bipolar hemiarthroplasty. Orthopedics 1989;12:1545. 36. Dobbs RE, Parvizi J, Lewallen DG. Perioperative morbidity and 30-day mortality after intertrochanteric hip fractures treated by internal fixation or arthroplasty. J Arthroplasty 2005;8:963. 37. Todd CJ, Freeman CJ, Camilleri-Ferrante C, et al. Differences in mortality after fracture of hip: the east Anglian audit. BMJ 1995;6984:904. 38. Nather A, Seow CS, Iau P, et al. Morbidity and mortality for elderly patients with fractured neck of femur treated by hemiarthroplasty. Injury 1995;3:187. 39. Thomas CJ, Smith RP, Uzoigwe CE, et al. The weekend effect: short-term mortality following admission with a hip fracture. Bone Joint J 2014;3:373.
Please cite this article as: Lee Y-K, et al, Cementless Bipolar Hemiarthroplasty Using a Micro-Arc Oxidation Coated Stem in Patients with Displaced Femoral Neck Fractures, J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.04.020
Y-K. Lee et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx 40. Kang BJ, Lee Y-K, Lee KW, et al. Mortality after Hip Fractures in Nonagenarians. J Bone Metab 2012;2:83. 41. Cooper C. The crippling consequences of fractures and their impact on quality of life. Am J Med 1997;2A:12S. 42. Streit MR, Merle C, Clarius M, et al. Late peri-prosthetic femoral fracture as a major mode of failure in uncemented primary hip replacement. J Bone Joint Surg (Br) 2011;2:178. 43. Parvizi J, Johnson BG, Rowland C, et al. Thirty-day mortality after elective total hip arthroplasty. J Bone Joint Surg Am 2001;10:1524. 44. Keisu KS, Orozco F, Sharkey PF, et al. Primary cementless total hip arthroplasty in octogenarians. Two to eleven-year follow-up. J Bone Joint Surg Am 2001;3:359. 45. Parvizi J, Keisu KS, Hozack WJ, et al. Primary total hip arthroplasty with an uncemented femoral component: a long-term study of the Taperloc stem. J Arthroplasty 2004;2:151.
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46. Berend KR, Lombardi AV, Mallory TH, et al. Cementless double-tapered total hip arthroplasty in patients 75 years of age and older. J Arthroplasty 2004;3:288. 47. Reitman RD, Emerson R, Higgins L, et al. Thirteen year results of total hip arthroplasty using a tapered titanium femoral component inserted without cement in patients with type C bone. J Arthroplasty 2003;7(Suppl 1):116. 48. Rothman RH, Cohn JC. Cemented versus cementless total hip arthroplasty. A critical review. Clin Orthop Relat Res 1990;254:153. 49. McCalden RW, McGeough JA, Barker MB, et al. Age-related changes in the tensile properties of cortical bone. The relative importance of changes in porosity, mineralization, and microstructure. J Bone Joint Surg Am 1993;8:1193. 50. Noble PC, Box GG, Kamaric E, et al. The effect of aging on the shape of the proximal femur. Clin Orthop Relat Res 1995;316:31.
Please cite this article as: Lee Y-K, et al, Cementless Bipolar Hemiarthroplasty Using a Micro-Arc Oxidation Coated Stem in Patients with Displaced Femoral Neck Fractures, J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.04.020
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Cementless Bipolar Hemiarthroplasty Using a Micro-Arc Oxidation Coated Stem in Patients with Displaced Femoral Neck Fractures Young-Kyun Lee, M.D. a, Ho-Yun Joung, M.D. a, Sang-Hwan Kim, M.D. a, Yong-Chan Ha, M.D. b, Kyung-Hoi Koo, M.D. c a
Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, 82 Gumi-ro, 173 Beon-gil, Bundang-gu, Seongnam 463-707, South Korea Department of Orthopaedic Surgery, Chung-Ang University College of Medicine, 224-1 Heukseok-dong, Dongjak-gu, Seoul 156-755, South Korea Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 82 Gumi-ro, 173 Beon-gil, Bundang-gu, Seongnam 463-707, South Korea
b c
a r t i c l e
i n f o
Article history: Received 6 January 2014 Accepted 16 April 2014 Available online xxxx Keywords: femoral neck fracture cementless stem surface treatment micro-arc oxidation hemiarthroplasty
a b s t r a c t Femoral stem fixation for displaced femoral neck fractures in osteoporotic patients is an ongoing debate. We evaluated the outcome of 136 cementless bipolar hemiarthroplasty using a Micro-arc oxidation (MAO) coated stem. All patients survived the procedure and were discharged from the hospital. Thirty- and 90-day mortality rates were 0.7% and 2.2%, respectively. Ninety-eight hips were followed for a minimum of 2 years (mean, 44 months) postoperatively. Three stems were revised because of a periprosthetic fracture. Although cortical stress shielding around the stem was observed in 3 hips, there was no loosening or osteolysis. Cementless bipolar hemiarthroplasty using a MAO-coated stem is a useful and safe option to treat displaced femoral neck fractures. © 2014 Elsevier Inc. All rights reserved.
Hemiarthroplasty is a useful treatment for displaced femoral neck fractures in osteoporotic patients [1,2]. Traditionally, cemented stems have been preferred than cementless stems in these fractures [3,4], because cementless fixation might lack the initial stability, which could lead to a failure of fixation [5,6]. However, cemented stems may cause an intraoperative embolism and subsequent cardiopulmonary complications [7], although these complications might be reduced with modern cementing techniques and close intraoperative monitoring [8]. Thus, the fixation method of stem has been debated in osteoporotic femurs [1,9,10]. Cementless stem designs have been improved [11], and several surface treatments have been introduced to enhance biologic fixation [12–17]. Satisfactory results were reported after the use of contemporary cementless stems in senile patients with osteoporosis [18–21]. Micro-arc oxidation (MAO) is an electrochemical oxidation with a high voltage spark treatment in an alkaline electrolyte, forming nanoporous pits and thick oxide layers on the metal surface [12,13,22,23]. This process is available for surfaces of aluminum, titanium, zirconium, and their alloys. It enhances wear and corrosion resistance as well as prolonging component lifetime. It also incorporates calcium and phosphorus into the coating layer, resulting in an
The Conflict of Interest statement associated with this article can be found at http:// dx.doi.org/10.1016/j.arth.2014.04.020. Reprint requests: Yong-Chan Ha, Department of Orthopaedic Surgery, Chung-Ang University College of Medicine, 224-1 Heukseok-dong, Dongjak-gu, Seoul 156-755, South Korea.
enhanced bone on-growth of cementless implants [12,13,22,23]. However, there is no clinical study to support the effectiveness of MAO-coated stem. The purpose of this study was to evaluate clinical and radiological results of cementless bipolar hemiarthroplasty using an MAO-coated stem in senile patients with displaced femoral neck fracture. Materials and Methods From March 2007 to July 2010, 134 patients (136 hips) aged 65 years or older, who were diagnosed as having a displaced femoral neck fracture, were treated with bipolar hemiarthroplasty using a MAO-coated stem at two hospitals (Seoul National University Bundang Hospital and Chung-Ang University Hospital). There were 28 men and 106 women, and their mean age at the time of surgery was 78.4 years (range, 65–108 years). The mean body mass index was 21.2 kg/m 2 (range, 12.9–29.8 kg/m 2) and the mean American Society of Anesthesiologists score was 2.4 (range 1–4). A cementless stem design (Bencox stem; CORENTEC, Cheonan, Korea) was used. This is a double-tapered, rectangular-shaped titanium stem. The stem is composed of a titanium alloy and the surface is extensively treated with MAO, maintaining average 5.5 micron of surface roughness. The acetabular component is a cobalt-chromium cup (IC Bipolar Head, Implantcast GmbH, Buxtehude, Germany), which has a UHMWPE liner inside. (Fig. 1) The operation was performed under regional anesthesia in 117 and general anesthesia in 19 hips. All operations were carried out
http://dx.doi.org/10.1016/j.arth.2014.04.020 0883-5403/© 2014 Elsevier Inc. All rights reserved.
Please cite this article as: Lee Y-K, et al, Cementless Bipolar Hemiarthroplasty Using a Micro-Arc Oxidation Coated Stem in Patients with Displaced Femoral Neck Fractures, J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.04.020
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Y-K. Lee et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx
of the femoral stem, the acetabular erosion and cortical porosis around femoral stem [26], leg length discrepancy and heterotopic ossification. The stability of the femoral stem was classified with use of the method of Engh et al. [27]. The osteolytic lesions were defined according the criteria of Engh et al. [28]. The lesions were recorded according to the seven zones described by Gruen et al. [29]. Evidence of spot welding and reactive lines was documented in each of the Gruen zones [29]. Spot welds were defined as bone densification and trabecular streaming between the cortex and the implant [30]. Subsidence of the femoral stem was defined as the change in the distance from the superolateral edge at the shoulder of the prosthesis to the tip of the greater trochanter on the anteroposterior radiograph of the hip [31]. Cortical porosis was defined as a loss of endosteal bone and a decrease in bone mineralization resulting in a homogeneous but somewhat sparse (washed-out) appearance of the remaining cortex [24,26]. For the evaluation of leg-length, we measured the distance between the inter-teardrop line and the lower margin of the lesser trochanter. The distances of the operated limb and the contralateral limb were compared and the difference N 2 cm was defined as the failure of leg length equalization [32]. Heterotopic ossification was evaluated according to the system of Brooker et al. [33], if present. The design and protocol of this retrospective study were approved by the institutional review board in each hospital, and all informed consent was waived due to the retrospective nature of the study.
Fig. 1. The Bencox stem is a double-tapered, rectangular titanium stem without collar and extensive MAO-coating on the surface.
through the posterolateral approach. After rasping the endosteal cavity in the proximal femur, a stem trial was inserted to check the size of stem, stability and leg length as described previously [24]. Once an optimal stem size was determined, a real stem was press-fitted into the femoral canal. Proximal femoral cracks occurred in 2 hips during the insertion of stem, which were treated with cerclage wires. There were no anesthesia-related complications. The mean operating time was 81.4 minutes (range, 30–120 minutes) and the mean estimated blood loss was 321.5 mL (range, 100–500 mL). Patients were instructed to stand and walk using an assistive device (walker, crutches, or cane) with tolerable weight-bearing on the third postoperative day. As the walking ability improved, the assistive device was changed by physical therapist. To prevent thromboembolism, thigh-length antiembolic stockings were applied and ankle pump was encouraged in bed during the hospitalization. The mean hospital stay was 17.1 days (range, 6 to 85 days) and no patients died during the hospitalization. Patients who necessitated further physical therapy and/or nursing care were transferred to rehabilitation department or other institutions. Follow-up evaluations were performed at six weeks; at three, six, nine, and twelve months, and every year thereafter. Two nurses and one private locator visited patients who were unable to return for the follow-up evaluations. Some patients were contacted by telephone interview and they were asked to send recent follow-up radiographs. The walking ability was evaluated by using the Koval’s categories [25]. The radiographs were evaluated by two independent observers who did not participate in the operation. The six-week anteroposterior and cross-table lateral radiographs were considered to be the baseline studies for comparison. The serial radiographic evaluation included an assessment of the stability, osteolysis around femoral stem, subsidence
Fig. 2. (A) A 73 year-old women, who had undergone a hemiarthroplasty for femoral neck fracture using MAO-coated cementless stem, sustained a periprosthetic fracture at postoperative 3 years and 3 months. (B) On radiograph obtained 2 years 6 months after the revision of stem, the revised stem is well fixed.
Please cite this article as: Lee Y-K, et al, Cementless Bipolar Hemiarthroplasty Using a Micro-Arc Oxidation Coated Stem in Patients with Displaced Femoral Neck Fractures, J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.04.020
Y-K. Lee et al. / The Journal of Arthroplasty xxx (2014) xxx–xxx
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Results At the time of discharge, 62 (64.6 %) patients could independently ambulate with or without an assistive device. Twelve patients (12 hips) were lost to follow-up, and 26 patients (26 hips) died before a minimum follow-up of 2 years; 1 patient died within 30 days, 3 patients died within 90 days, 16 patients died between 90 days and 1 year, and 6 patients between 1 year and 2 years postoperatively. The remaining 96 patients (98 hips) were followed for more than 2 years postoperatively (mean, 44 months; range, 24–72 months). Among them, radiographic analysis was available in 70 hips. There was no readmission within 30 days. There was no dislocation or periprosthetic joint infection during the follow-up period. Periprosthetic femoral fractures occurred in 3 patients at 2.9–3.3 years postoperatively. One fracture was stabilized with cerclage wires and the remaining two fractures were treated with a stem revision (Fig. 2). Three patients had activity-related thigh pain, but did not require any medication. Comparing the ambulatory abilities before the fracture and at the final follow-up based on the Koval Categories [25], the ability dropped by 1 level in 14 patients (14.6 %), by 2 levels in 5 (5.2 %), by 3 levels in 8 (8.3 %), and by 4 or more levels in 14 (14.6 %). Nineteen patients (19.8 %); 9 community ambulatories and 10 household ambulatories before fracture became nonfunctional ambulatories due to medical co-morbidities at the final follow-up, although they did not have any discomforts in the hips. (Fig. 3). In 1 patient, a subsidence of the femoral stem was observed by 7 mm at 6 weeks radiograph postoperatively, which was not progressive on later radiographs. There was no failure of leg length equalization. At the latest radiographs, no hip had any sign of loosening or osteolysis (Fig. 4). Cortical porosis was seen around the stem in 3 hips (Fig. 5). These 3 hips had spot weld in Gruen zone 2, 3, 5, and 6, and thought to have a bone-ingrown stability. Two hips had a reactive line at Gruen zone 1 and 7, which was not progressive. Two hips had an acetabular erosion by less than 2 mm. Brooker grade I heterotopic ossification was seen in 1 hip (1.0 %). Discussion In our study, a cementless bipolar hemiarthroplasty with use of an MAO-coated tapered stem provided satisfactory clinical and radiological results, and was associated with few complications in displaced neck fractures of osteoporotic femur. The result is compatible with previously reported outcomes of hemiarthroplasty using cemented stems [3,34,35]. Thirty- and 90-day mortality rates (0.7% and 2.2%) in our study were lower than those (4 to 7 %, and 5 to 24 %) of previous studies
Fig. 3. Ambulatory change between preinjury and final follow-up.
Fig. 4. (A) A 71-year-old woman with a displaced femoral neck fracture underwent a hemiarthroplasty using MAO-coated cementless stem. (B) On anteroposterior radiographs obtained 5 years postoperatively, the stem is well fixed with a stable bone ingrowth.
[36–40], although we could not directly compare with the results of other studies, because we could not adjust comorbidities. Our findings, about 20% nonfunctional ambulatories of the patients at the last follow-up, was compatible with those (6–40%) of previous studies [25,38,41]. Some studies reported that the cementless arthroplasty is associated with an increased risk of periprosthetic fracture [10,42]. In our study, there were 3 periprosthetic fractures during the follow-up. However, we could not determine whether these fractures were related with the fixation method due to lack of the control group. Because osteosynthesis of displaced femoral neck fractures in osteoporotic patients requires a prolonged protection from weight bearing, and has concerns such as loss of initial stability, some authors have recommended cemented hemiarthroplasty to avoid these problems and to return patients to their prefracture level of activity quickly [3,34,35]. However, the cementation increases the risk of cardiopulmonary complications, particularly in elderly patients with osteoporosis [7,43]. The stem in this study was a tapered rectangular stem with an extensive MAO-coating. It fits into the meta-diaphyseal junction, which enables an initial stability and long-term biologic fixation even in osteoporotic proximal femur [12,13,22,23,44–47], and actually avoids the cement-related cardiopulmonary complications [48]. In our study, 3 patients (3.1 %) showed cortical porosis around the femoral stem. There might be some explanations for the porosis. It
Please cite this article as: Lee Y-K, et al, Cementless Bipolar Hemiarthroplasty Using a Micro-Arc Oxidation Coated Stem in Patients with Displaced Femoral Neck Fractures, J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.04.020
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Fig. 5. (A) A 91-year-old woman with a displaced femoral neck fracture underwent a hemiarthroplasty using MAO-coated cementless stem. (B) An anteroposterior radiograph obtained 2 years postoperatively shows cortical porosis around the stem. However, there is no loosening sign around the femoral stem.
could be a stress shielding after the use of a cementless stem, and/or a cortical thinning due to an aging phenomenon [24,49,50]. The cortical porosis did not threaten the stability of the stems for 2–6 years postoperatively. We should address several limitations of our study. Our study was a retrospective with a short follow-up period. However, a long-term follow-up study is barely possible, because senile patients have a short life expectancy. We did not use cemented stem during the study period because we were concerned about the cement-related adverse effects. Accordingly, there was no comparison with cemented hemiarthroplasty. Despite these limitations, this is the first study which showed the results of an extensively MAO-coated cementless stem. Hemiarthroplasty using this type of stem design is a safe and satisfactory option to treat displaced femoral neck fractures in osteoporotic patients. References 1. Figved W, Opland V, Frihagen F, et al. Cemented versus uncemented hemiarthroplasty for displaced femoral neck fractures. Clin Orthop Relat Res 2009;9:2426. 2. Zi-Sheng A, You-Shui G, Zhi-Zhen J, et al. Hemiarthroplasty vs primary total Hip arthroplasty for displaced fractures of the femoral neck in the elderly: a metaanalysis. J Arthroplasty 2012;4:583. 3. Haidukewych GJ, Israel TA, Berry DJ. Long-term survivorship of cemented bipolar hemiarthroplasty for fracture of the femoral neck. Clin Orthop Relat Res 2002;403:118. 4. Ahn J, Man LX, Park S, et al. Systematic review of cemented and uncemented hemiarthroplasty outcomes for femoral neck fractures. Clin Orthop Relat Res 2008;10:2513.
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Please cite this article as: Lee Y-K, et al, Cementless Bipolar Hemiarthroplasty Using a Micro-Arc Oxidation Coated Stem in Patients with Displaced Femoral Neck Fractures, J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.04.020