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High Incidence of Intraoperative Fractures With a Specific Cemented Stem Following Intracapsular Displaced Hip Fracture
The Journal of Arthroplasty xxx (2019) 1e5
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The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
High Incidence of Intraoperative Fractures With a Specific Cemented Stem Following Intracapsular Displaced Hip Fracture le Angers, MD a, Jessica Vachon, MD b, Melissa Laflamme, MD, MSc a, *, Miche Veronica Pomerleau, MD c, Annie Arteau, MD d Department of Orthopaedic Surgery, CHU de Qu ebec e Centre Hospitalier de l’Universit e Laval (CHUL), Qu ebec City, Qu ebec, Canada ^tel-Dieu-de-L Department of Orthopaedic Surgery, Ho evis, L evis, Qu ebec, Canada c Department of Surgery, Facult e de M edecine, Universit e Laval, Qu ebec City, Qu ebec, Canada d ^tel-Dieu-de-Qu Department of Orthopaedic Surgery, CHU de Qu ebec e Ho ebec, Qu ebec, Qu ebec, Canada a
b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 17 July 2019 Received in revised form 6 September 2019 Accepted 11 September 2019 Available online xxx
Background: To reduce costs of orthopedic implants, the government decided to standardize implants used across different specialties in a group of hospitals located in the same geographic area. The usual cemented stem used in the context of intracapsular displaced geriatric hip fractures was replaced by another stem. Abnormal intraoperative calcar and trochanteric fractures were noted. The purpose of this study is to determine the incidence of intraoperative periprosthetic fractures following an intracapsular displaced hip fracture treated with this specific cemented stem compared to the previous implant. Methods: This is a retrospective cohort study comparing an historic cohort of hip fractures treated with the OmniFit EON (Stryker, Kalamazoo, MI) cemented stem with a new cohort of patients who received the Corail (DePuy Synthes, Warsaw, IN) cemented stem. Four orthopedic surgeons reviewed operative reports and postoperative radiographs. Results: The treatment group included 348 patients who received the Corail stem. The control group included 77 patients. The 2 groups had similar baseline characteristics (P > .05) except for the presence of dementia. Incidence of intraoperative calcar or greater trochanteric fracture was 15.5% for the Corail group and 2.7% for the control group (P < .05). No patient-related factors or surgeon-related factors were related to a higher number of fractures in the treatment group (P > .05). Conclusion: The Corail cemented stem presents an abnormal number of iatrogenic intraoperative fractures following displaced femoral neck fracture in our geriatric population. No external factor seems to explain this high number of fractures. Implant design should be questioned. Level of Evidence: III. © 2019 Elsevier Inc. All rights reserved.
Keywords: femoral neck fracture hip fracture hemiarthroplasty cemented stem calcar fracture
Hip fracture in the elderly is a growing problem. In fact, a report from the 2014 to 2015 Canadian registry demonstrates an increase of 20% in the number of hip fracture surgeries performed compared to
Source of Funding: There was no external source of funding for this study. One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to https://doi.org/10.1016/j.arth.2019.09.017. * Reprint requests: Melissa Laflamme, MD, MSc, Department of Orthopaedic bec, Pavillon CHUL, 2705 Boulevard Laurier, Bureau D-1211, Surgery, CHU de Que bec City, Que bec G1V 4G2, Canada. Que https://doi.org/10.1016/j.arth.2019.09.017 0883-5403/© 2019 Elsevier Inc. All rights reserved.
the previous 5 years [1]. The provincial government decided to standardize the implant that was used in a group of hospitals in the same geographic area to reduce costs. Following this process, surgeons across various specialties were asked to standardize implants for several different procedures. The usual cemented stem used in the context of intracapsular displaced geriatric hip fractures was replaced by another cemented stem in 3 teaching hospitals. Abnormal intraoperative calcar and trochanteric fractures were noted by surgeons in this group. The purpose of this retrospective cohort study is to determine the incidence of intraoperative iatrogenic periprosthetic hip fractures following an intracapsular displaced hip fracture treated with this newly implanted cemented stem compared to the previous implant. Possible implant-related, surgery-related, and patientrelated risk factors were also investigated.
2
M. Laflamme et al. / The Journal of Arthroplasty xxx (2019) 1e5
Materials and Methods
could be included twice in the data if they had 2 femoral neck fractures requiring a cemented hemiarthroplasty on each side.
Study Design A retrospective cohort study was conducted at 3 teaching hospitals of the same geographic area to compare the number of intraoperative iatrogenic periprosthetic femoral fractures following a displaced femoral neck fracture treated with a Corail (DePuy Synthes, IN) cemented stem to the number of this specific type of fracture with the previous implant used in the same hospitals, the OmniFit EON (Stryker, NJ). Demographic data were collected from the charts. Operative reports were reviewed for implant sizes and evidence of intraoperative fracture. Finally, postoperative radiographs were evaluated for postoperative complications. The hypothesis was that the newly implanted stem led to more intraoperative periprosthetic fractures than the previous implant. Patient Selection The implantation of the Corail began on June 1, 2016. Therefore, all patients who received a Corail cemented stem after a displaced femoral neck fracture from June 1, 2016 to March 31, 2018, in 3 teaching hospitals, by 35 different surgeons, were included in the present study. Patients from those 3 institutions were grouped together to form the Corail treatment group. An historic cohort of patients who received the previous cemented stem in 2013-2014 during a period of 12 months in one of the 3 institutions was used as the control group. The data from those patients were already collected from a previous local study.
Radiographic Evaluation Standard anteroposterior of the pelvis and lateral radiographs of the involved hip were routinely performed in the first 6 weeks postoperatively. Every radiograph was analyzed by one of the senior investigator for calcar or trochanteric fracture, implant displacement, dislocation, or cement fracture. Leg lengths were also measured postoperatively from a line drawn through the most inferior points of the ischial tuberosities to the most medial point of the lesser trochanter. The contralateral nondiseased side was used to determine the patient’s normal anatomy, against which postoperative values were compared. Statistical Analysis All continuous variables are presented as means ± standard deviations. Categorical variables are presented as percentage. Continuous comparisons between groups were performed using independent-samples t-test. Cochran approximation was used when appropriate. For categorical comparisons, according to group size, chi-squared or Fisher’s test was performed. As there was a significant difference in dementia status between the treatment and the control groups, the comparison in the proportion of fractures was tested using logistic regression adjusted for this factor. All analyses were performed with the SAS Statistical Package version 9.2 (SAS Institute, Cary, NC) and a P value <.05 was considered significant.
Study Procedure The study was approved by the Institutional Ethics Review Board and was conducted in accordance with guidelines for the conduct of research on human subjects. Four orthopedic surgeons participated in data collection from the patient's charts and postoperative radiographs. Data between patients with and without a periprosthetic fracture were then compared to identify risk factors of intraoperative periprosthetic fracture. Those risk factors were divided into 3 categories: patient-related factors; surgically related factors such as presence of a surgical assistant, surgery performed during the first 6 months after the introduction of the stem, hip reconstruction surgeon, or non-hip reconstruction surgeon; and implant-related factors such as stem size, neck length, and head size. The surgeons performing elective hip replacement regularly including those with a hip reconstruction fellowship were defined as the hip reconstruction surgeons. To evaluate the learning curve effect, we divided the complete study period into 6-month periods to evaluate if most of the fracture happened in the first 6 months. Data Collection Patient’s medical charts were reviewed by one of the investigators. Demographic data as well as past medical history, comorbidities, presence of dementia, as well as American Society of Anesthesiologists category were recorded from patient’s charts. Operative report and implant stickers were all reviewed to collect information on the side of surgery, date of surgery, surgeon in charge, presence of a surgical assistant, as well as stem size, neck length, and head size. The presence of an intraoperative calcar fracture, trochanteric fracture, or both was noted and the procedure performed to address the complication was recorded. Patients
Results The Corail treatment group included 348 patients. The control group included 77 patients. The demographic data were similar between the 2 groups, except for a statistically significant difference for the presence of dementia (Table 1). All further statistical analyses were therefore adjusted for dementia. Two patients had bilateral femoral neck fractures during the study period and were therefore included twice. Fifty-four patients (15.5%) experienced a periprosthetic fracture in the Corail treatment group (Fig. 1). In 43 patients (12.6%), fractures were recognized during surgery. Only 2 patients (2.7%) had a fracture in the control group (P < .05), both recognized during surgery. Within the Corail treatment group, 6 patients sustained both a calcar and a greater trochanteric fracture. Thirty-eight of the 39 calcar fractures were recognized during surgery and treated with a cerclage wire. The other calcar fracture presented at 6 weeks of follow-up with a displaced fracture and pain since surgery. The fracture was not displaced and therefore missed on the initial
Table 1 Demographic Data. Variables
Control Group
Corail Group
Number of patients Gender (%) Male Female Age (y) No. of comorbidities ASA 3 and 4 (%) Dementia (%)
74
348
25.7 74.3 83 ± 8 2±1 54 24
23.9 76.1 82 ± 9 2±1 58 37
ASA, American Society of Anesthesiologists score; NS, not significant.
P-Value
NS NS NS NS NS .04
M. Laflamme et al. / The Journal of Arthroplasty xxx (2019) 1e5
3
Fig. 1. Comparison between the control group and the Corail group regarding periprosthetic fractures.
postoperative radiographs. In this case, decision was made to proceed with a prosthesis revision. Six of the 22 trochanteric fractures were recognized during surgery and treated with cerclage wire. Sixteen fractures of the greater trochanter were only recognized on routine postoperative imaging. Those fracture were treated conservatively. The fractures happened equally between institutions. Fractures around the calcar and/or trochanteric area recognized during surgery were fixed using the 1.7-mm cable system (DePuy Synthes). Fifty-nine cables were therefore required to fix the 43 recognized fractures intraoperatively in the treatment group compared to only 3 cables used to fix the 2 fractures in the control group. Analysis comparing patients in the treatment group who sustained a periprosthetic fracture (n ¼ 54) to patients without fracture (n ¼ 294) treated with the same prosthesis were performed to identify risk factors. No patient-related factor could be identified to explain the high number of fractures in the Corail treatment group (Table 2). Moreover, surgically related factors were also similar between groups (Table 3). Finally, the data regarding implantrelated factors could not identify a difference between the 2 groups (Table 4). Looking at the first 6 months after the implantation of the Corail stem, 10 fractures were recorded. This was in fact the lowest number of fractures in a 6-month period. The other 6month period in the chronological order recorded 13, 19, and 12 patients sustaining a periprosthetic fracture, respectively. Therefore, no learning curve effect could be demonstrated. We looked at leg lengths of the 54 patients in the Corail group who sustained a periprosthetic fracture. After surgery, 26 patients were shorter than their noninjured side or had the same leg length and 28 patients had their operated side longer than the noninjured leg. Of those 28 patients, 22 patients had a lengthening of 10 mm or less.
Table 2 Patient-Related Factors to Sustain a Periprosthetic Fracture Within the Corail Group.
Discussion There are many studies in the literature on the Corail stem, but all of them report on the cementless stem. This stem is widely used in primary and revision arthroplasty. According to the Norwegian arthroplasty registry [2], the uncemented primary Corail stem has a 10-year and 15-year survival rate of 98% and 97%, respectively. Many other studies confirm the good long-terms results of this stem [3e5]. Vidalain [3] explains their 10.9% intraoperative complications in 347 cases, including 33 calcar cracks, 3 fractures, and 2 perforations, to the learning curve and to the goal of achieving a closer cortical contact when broaching the femoral canal for a noncemented stem. In our cohort, patients were not classified according to their bone stock as this was a geriatric population with low energy trauma femoral neck fractures. Therefore, a cemented stem design was chosen to address the poor bone stock, as the broaching technique is usually less aggressive than in cementless stem design where cortical contact is mandatory. When using a cemented stem like in our series, the number of calcar fractures was expected to be lower. Wood et al [6] implanted the cementless Corail stem in 10 revision total hip replacement cases without any complication. Reikerås [7] also used this stem for revision. They reported 8 proximal femoral fractures intraoperatively requiring wire fixation in their 66 cases. The only study reporting the use of the Corail stem with bipolar head in displaced femoral neck fractures was published by Cawley et al [8] and used the cementless design. They report good results at 4.3 years of follow-up on their 68 patients with 1 patient requiring revision for subsidence of an undersized implant. No fracture occurred while seating the implant in this series.
Table 3 Surgically Related Factors to Sustain a Periprosthetic Fracture Within the Corail Group.
Risk Factors
Patient With Fracture (n ¼ 54)
Patient Without Fracture (n ¼ 294)
P-Value
Risk Factors
82 ± 9 17 57 33
82 ± 9 25 61 38
.58 .17 .64 .56
Patient Without Fracture (n ¼ 294)
P-Value
Age (y) Male (%) ASA 3 and 4 (%) Dementia (%)
Patient With Fracture (n ¼ 54)
Presence of surgical assistant (%) THA surgeon (%)
83
84
NS
46
38
NS
ASA, American Society of Anesthesiologists score.
THA, total hip arthroplasty; NS, not significant.
4
M. Laflamme et al. / The Journal of Arthroplasty xxx (2019) 1e5
Table 4 Implant-Related Factors to Sustain a Periprosthetic Fracture Within the Corail Group. Risk Factors
With Fracture (n ¼ 54)
Without Fracture (n ¼ 294)
P-Value
Stem size Neck length Short (%) Standard (%) Long (%) Head size
11 ± 2
11 ± 2
NS NS
46 44 9 46 ± 4
48 48 4 47 ± 4
NS
NS, not significant.
According to Louboutin et al [9], perioperative hip fracture rate is 4%. Our study demonstrated a high rate of intraoperative fractures compared to our control group and also compared to the literature. We tried to identify risk factors that could explain this phenomenon. Since this prosthesis design was newly implanted in our institutions, we looked at the learning curve since studies show a decreased complication rate as the number of prosthesis performed by the surgeon increases [10,11]. According to Nunley et al [12], the complication rate is higher in the first 25 prosthesis implanted. In our study, the learning curve effect could not be demonstrated since the lowest number of fractures was in the first 6-month period after the implantation of the Corail stem. We also looked at leg lengths, since significant lengthening of the operated limb could be an explanation for periprosthetic fracture. Since only half of our cohort had the operated side longer than the contralateral, this does not seem to be the main factor. We have 2 theories that could explain, at least partially, the high rate of intraoperative periprosthetic fractures in our cohort of cemented Corail stems coupled with a bipolar head. First, the offset difference between the smallest and the largest stem is small. According to the company’s brochure, the neck length is 39 mm, which is the same for all the stem sizes. The smallest stem has an offset of 38.3 mm. Those dimensions make it difficult to reduce the implant in the acetabulum due to the high offset and long neck even for small stems. When questioned, some surgeons tried to reduce the neck length by using a shorter neck length on the bipolar head, but this strategy failed to decrease the fracture number as shown in Table 4. This offset issue might also explain the high number of calcar cracks described in Vidalain’s study [3]. Moreover, if we compare the neck length and offset of another stem from the same company of the Corail, the C-stem (DePuy Synthes), the smallest stem has a neck length and offset of 30.5 and 35.5 mm, respectively. The neck length is 8.5 mm less and the offset is 2.8 mm less if we compare the smallest stem of both systems. Moreover, the largest C-stem stem as a neck length of 38 mm, which is 1 mm less than the entire Corail neck lengths. In fact, the smallest Corail neck length is 39 mm. Furthermore, if we compare the neck length and offset of the OmniFit EON 132 used in the control group, the smallest stem has a neck length and offset of 25 and 29 mm, respectively, and the largest stem has a neck length and offset of 40 and 48 mm, respectively. These significant differences might explain, at least partially, the difference in the number of calcar fractures between the 2 groups. As discussed by Parvizi [13], there is a wide variation in the morphology of native femurs and the Corail stem design with a large femoral offset may not be adequate for this population. Second, the bipolar head is fairly large, therefore the lever of arm to reduce the implant in the acetabular cavity is larger than in total hip replacement where the head is much smaller. The larger head led to a larger jumping distance to reduce or dislocate the implant and a larger moment of strength. This could explain the fractures when taking into consideration the exaggerated neck length and
offset compared to patient's anatomy since intraoperative calcar fracture was the most common fracture found in our cohort and usually occurred during prosthesis trial reduction when the leg was rotated to reduce the hip joint. Finally, greater trochanteric fractures can be explained, at least in part, by surgical approach. Most of the surgeons in our centers address femoral neck fractures using the Hardinge anterolateral hip approach. Gluteus medius reinsertion with transosseous tunnels at closure can fragilize the tip of the greater trochanter. Also, design of the implant might play a role. The fairly large offset of the implant can put too much tension on the muscular insertions on the greater trochanter and create a fracture. The corners of the trapezoidal proximal cross section of the Corail did not seem too sharp and could not explain the high number of greater trochanter fractures, but some surgeons felt that the Corail broaches for medullary canal preparation were aggressive. In fact, according to the company, the same broach instrumentation is used for cemented and cementless design. This instrumentation might be too aggressive for poor density bone as in this geriatric population and create greater trochanteric fracture while the surgeon tried to avoid varus positioning of the implant. Luckily, greater trochanteric fractures do not impact the stem’s stability and can be managed conservatively [14], but calcar fractures found during surgery were managed as recommended using cerclage wires to prevent stem subsidence [15]. Overall, intraoperative calcar and greater trochanteric fractures can certainly have detrimental effects on the postoperative care. Using cerclage wires increases surgical time and blood loss leading to an increased risk of infection. Patients can describe more pain after surgery and develop complications related to their decreased mobility secondary to their pain. This could definitely be part of another study. We have noted some limitations in the current study, mainly due to the retrospective nature of the study and the fact that the control group is fairly small compared to the study group. Using operative protocols and postoperative radiographs to look for the presence of a periprosthetic fracture might have induced a bias, since no patient underwent a computed tomography scan to confirm the fracture. Also, the learning curve effect is a difficult concept to evaluate. We decided to look at this as a group and not for every surgeon considering that the numbers were too small to evaluate individually. Finally, since we were looking at the perioperative fractures, no patients were lost to follow-up.
Conclusion The Corail cemented stem presents an abnormal number of iatrogenic intraoperative periprosthetic fractures following displaced femoral neck fractures in the geriatric population. Our number of fractures is above the expected percentage during an elective noncemented total hip arthroplasty and above the control group operated by the same group of surgeons. No external factor seems to explain this abnormal number of fractures. Implant design might be an important aspect to be evaluated in more details. Surgeons should be aware of this unexpected complication with this cemented stem used in this specific patient population.
Acknowledgments We would like to thank Guillaume Ruel for his contribution to the statistical analysis.
M. Laflamme et al. / The Journal of Arthroplasty xxx (2019) 1e5
References /Canadian Institute for Health In[1] Institut canadien d'information sur la sante formation. Arthroplasties de la hanche et du genou au Canada: rapport annuel de 2014-2015. Registre canadien des remplacements articulaires 2017:1e35. [2] Hallan G, Lie SA, Furnes O, Engesaeter LB, Vollset SE, Havelin LI. Medium- and long-term performance of 11,516 uncemented primary femoral stems from the Norwegian arthroplasty register. J Bone Joint Surg Br 2007;89:1574e80. https://doi.org/10.1302/0301-620X.89B12.18969. [3] Vidalain JP. Twenty-year results of the cementless Corail stem. Int Orthop 2011;35:189e94. https://doi.org/10.1007/s00264-010-1117-2. ski M. Results of total cementless [4] Drobniewski M, Borowski A, Synder M, Sibin hip joint arthroplasty with Corail stem. Ortop Traumatol Rehabil 2013;15: 61e8. https://doi.org/10.5604/15093492.1032797. [5] Xu J, Xie Z, Zhao J, Gao Y, Zhao H, Peng L, et al. Results of a hydroxyapatitecoated femoral stem (Corail) in Chinese: a minimum 10-year follow-up. Springerplus 2016;5:1983. https://doi.org/10.1186/s40064-016-3656-5. [6] Wood TJ, Alzahrani M, Marsh JD, Somerville LE, Vasarhelyi EM, Lanting BA. Use of the Corail stem for revision total hip arthroplasty: evaluation of clinical outcomes and cost. Can J Surg 2019;62:78e82. https://doi.org/10.1503/ cjs.002318. [7] Reikerås O. Femoral revision surgery using a fully hydroxyapatite-coated stem: a cohort study of twenty two to twenty seven years. Int Orthop 2017;41:271e5. https://doi.org/10.1007/s00264-016-3204-5.
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[8] Cawley DT, Curtin PD, Lohan D, O'Sullivan M, Curtin W. The Corail® stem for the treatment of displaced femoral neck fractures d a viable alternative. Hip Int 2011;21:243e50. https://doi.org/10.5301/HIP.2011.7417. [9] Louboutin L, Viste A, Desmarchelier R, Fessy MH. Long-term survivorship of the Corail™ standard stem. Orthop Traumatol Surg Res 2017;103:987e92. https://doi.org/10.1016/j.otsr.2017.06.010. [10] York PJ, Logterman SL, Hak DJ, Mavrogenis A, Mauffrey C. Orthopaedic trauma surgeons and direct anterior total hip arthroplasty: evaluation of learning curve at a level I academic institution. Eur J Orthop Surg Traumatol 2017;27: 421e4. https://doi.org/10.1007/s00590-017-1937-5. [11] Hartford JM, Bellino MJ. The learning curve for the direct anterior approach for total hip arthroplasty: a single surgeon's first 500 cases. Hip Int 2018;27: 483e8. https://doi.org/10.5301/hipint.5000488. [12] Nunley RM, Zhu J, Brooks PJ, Engh Jr CA, Raterman SJ, Rogerson JS, et al. The learning curve for adopting hip resurfacing among hip specialists. Clin Orthop Relat Res 2009;468:382e91. https://doi.org/10.1007/s11999-009-1106-1. [13] Parvizi J. CORR Insights(®): increased risk of periprosthetic femur fractures associated with a unique cementless stem design. Clin Orthop Relat Res 2015;473:2054e5. https://doi.org/10.1007/s11999-014-4119-3. [14] Marsland D, Mears SC. A review of periprosthetic femoral fractures associated with total hip arthroplasty. Geriatr Orthop Surg Rehabil 2012;3:107e20. https://doi.org/10.1177/2151458512462870. [15] Duwelius PJ, Schmidt AH, Kyle RF, Talbott V, Ellis TJ, Butler JB. A prospective, modernized treatment protocol for periprosthetic femur fractures. Orthop Clin North Am 2004;35:485e92. https://doi.org/10.1016/j.ocl.2004.05.001.
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
High Incidence of Intraoperative Fractures With a Specific Cemented Stem Following Intracapsular Displaced Hip Fracture le Angers, MD a, Jessica Vachon, MD b, Melissa Laflamme, MD, MSc a, *, Miche Veronica Pomerleau, MD c, Annie Arteau, MD d Department of Orthopaedic Surgery, CHU de Qu ebec e Centre Hospitalier de l’Universit e Laval (CHUL), Qu ebec City, Qu ebec, Canada ^tel-Dieu-de-L Department of Orthopaedic Surgery, Ho evis, L evis, Qu ebec, Canada c Department of Surgery, Facult e de M edecine, Universit e Laval, Qu ebec City, Qu ebec, Canada d ^tel-Dieu-de-Qu Department of Orthopaedic Surgery, CHU de Qu ebec e Ho ebec, Qu ebec, Qu ebec, Canada a
b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 17 July 2019 Received in revised form 6 September 2019 Accepted 11 September 2019 Available online xxx
Background: To reduce costs of orthopedic implants, the government decided to standardize implants used across different specialties in a group of hospitals located in the same geographic area. The usual cemented stem used in the context of intracapsular displaced geriatric hip fractures was replaced by another stem. Abnormal intraoperative calcar and trochanteric fractures were noted. The purpose of this study is to determine the incidence of intraoperative periprosthetic fractures following an intracapsular displaced hip fracture treated with this specific cemented stem compared to the previous implant. Methods: This is a retrospective cohort study comparing an historic cohort of hip fractures treated with the OmniFit EON (Stryker, Kalamazoo, MI) cemented stem with a new cohort of patients who received the Corail (DePuy Synthes, Warsaw, IN) cemented stem. Four orthopedic surgeons reviewed operative reports and postoperative radiographs. Results: The treatment group included 348 patients who received the Corail stem. The control group included 77 patients. The 2 groups had similar baseline characteristics (P > .05) except for the presence of dementia. Incidence of intraoperative calcar or greater trochanteric fracture was 15.5% for the Corail group and 2.7% for the control group (P < .05). No patient-related factors or surgeon-related factors were related to a higher number of fractures in the treatment group (P > .05). Conclusion: The Corail cemented stem presents an abnormal number of iatrogenic intraoperative fractures following displaced femoral neck fracture in our geriatric population. No external factor seems to explain this high number of fractures. Implant design should be questioned. Level of Evidence: III. © 2019 Elsevier Inc. All rights reserved.
Keywords: femoral neck fracture hip fracture hemiarthroplasty cemented stem calcar fracture
Hip fracture in the elderly is a growing problem. In fact, a report from the 2014 to 2015 Canadian registry demonstrates an increase of 20% in the number of hip fracture surgeries performed compared to
Source of Funding: There was no external source of funding for this study. One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to https://doi.org/10.1016/j.arth.2019.09.017. * Reprint requests: Melissa Laflamme, MD, MSc, Department of Orthopaedic bec, Pavillon CHUL, 2705 Boulevard Laurier, Bureau D-1211, Surgery, CHU de Que bec City, Que bec G1V 4G2, Canada. Que https://doi.org/10.1016/j.arth.2019.09.017 0883-5403/© 2019 Elsevier Inc. All rights reserved.
the previous 5 years [1]. The provincial government decided to standardize the implant that was used in a group of hospitals in the same geographic area to reduce costs. Following this process, surgeons across various specialties were asked to standardize implants for several different procedures. The usual cemented stem used in the context of intracapsular displaced geriatric hip fractures was replaced by another cemented stem in 3 teaching hospitals. Abnormal intraoperative calcar and trochanteric fractures were noted by surgeons in this group. The purpose of this retrospective cohort study is to determine the incidence of intraoperative iatrogenic periprosthetic hip fractures following an intracapsular displaced hip fracture treated with this newly implanted cemented stem compared to the previous implant. Possible implant-related, surgery-related, and patientrelated risk factors were also investigated.
2
M. Laflamme et al. / The Journal of Arthroplasty xxx (2019) 1e5
Materials and Methods
could be included twice in the data if they had 2 femoral neck fractures requiring a cemented hemiarthroplasty on each side.
Study Design A retrospective cohort study was conducted at 3 teaching hospitals of the same geographic area to compare the number of intraoperative iatrogenic periprosthetic femoral fractures following a displaced femoral neck fracture treated with a Corail (DePuy Synthes, IN) cemented stem to the number of this specific type of fracture with the previous implant used in the same hospitals, the OmniFit EON (Stryker, NJ). Demographic data were collected from the charts. Operative reports were reviewed for implant sizes and evidence of intraoperative fracture. Finally, postoperative radiographs were evaluated for postoperative complications. The hypothesis was that the newly implanted stem led to more intraoperative periprosthetic fractures than the previous implant. Patient Selection The implantation of the Corail began on June 1, 2016. Therefore, all patients who received a Corail cemented stem after a displaced femoral neck fracture from June 1, 2016 to March 31, 2018, in 3 teaching hospitals, by 35 different surgeons, were included in the present study. Patients from those 3 institutions were grouped together to form the Corail treatment group. An historic cohort of patients who received the previous cemented stem in 2013-2014 during a period of 12 months in one of the 3 institutions was used as the control group. The data from those patients were already collected from a previous local study.
Radiographic Evaluation Standard anteroposterior of the pelvis and lateral radiographs of the involved hip were routinely performed in the first 6 weeks postoperatively. Every radiograph was analyzed by one of the senior investigator for calcar or trochanteric fracture, implant displacement, dislocation, or cement fracture. Leg lengths were also measured postoperatively from a line drawn through the most inferior points of the ischial tuberosities to the most medial point of the lesser trochanter. The contralateral nondiseased side was used to determine the patient’s normal anatomy, against which postoperative values were compared. Statistical Analysis All continuous variables are presented as means ± standard deviations. Categorical variables are presented as percentage. Continuous comparisons between groups were performed using independent-samples t-test. Cochran approximation was used when appropriate. For categorical comparisons, according to group size, chi-squared or Fisher’s test was performed. As there was a significant difference in dementia status between the treatment and the control groups, the comparison in the proportion of fractures was tested using logistic regression adjusted for this factor. All analyses were performed with the SAS Statistical Package version 9.2 (SAS Institute, Cary, NC) and a P value <.05 was considered significant.
Study Procedure The study was approved by the Institutional Ethics Review Board and was conducted in accordance with guidelines for the conduct of research on human subjects. Four orthopedic surgeons participated in data collection from the patient's charts and postoperative radiographs. Data between patients with and without a periprosthetic fracture were then compared to identify risk factors of intraoperative periprosthetic fracture. Those risk factors were divided into 3 categories: patient-related factors; surgically related factors such as presence of a surgical assistant, surgery performed during the first 6 months after the introduction of the stem, hip reconstruction surgeon, or non-hip reconstruction surgeon; and implant-related factors such as stem size, neck length, and head size. The surgeons performing elective hip replacement regularly including those with a hip reconstruction fellowship were defined as the hip reconstruction surgeons. To evaluate the learning curve effect, we divided the complete study period into 6-month periods to evaluate if most of the fracture happened in the first 6 months. Data Collection Patient’s medical charts were reviewed by one of the investigators. Demographic data as well as past medical history, comorbidities, presence of dementia, as well as American Society of Anesthesiologists category were recorded from patient’s charts. Operative report and implant stickers were all reviewed to collect information on the side of surgery, date of surgery, surgeon in charge, presence of a surgical assistant, as well as stem size, neck length, and head size. The presence of an intraoperative calcar fracture, trochanteric fracture, or both was noted and the procedure performed to address the complication was recorded. Patients
Results The Corail treatment group included 348 patients. The control group included 77 patients. The demographic data were similar between the 2 groups, except for a statistically significant difference for the presence of dementia (Table 1). All further statistical analyses were therefore adjusted for dementia. Two patients had bilateral femoral neck fractures during the study period and were therefore included twice. Fifty-four patients (15.5%) experienced a periprosthetic fracture in the Corail treatment group (Fig. 1). In 43 patients (12.6%), fractures were recognized during surgery. Only 2 patients (2.7%) had a fracture in the control group (P < .05), both recognized during surgery. Within the Corail treatment group, 6 patients sustained both a calcar and a greater trochanteric fracture. Thirty-eight of the 39 calcar fractures were recognized during surgery and treated with a cerclage wire. The other calcar fracture presented at 6 weeks of follow-up with a displaced fracture and pain since surgery. The fracture was not displaced and therefore missed on the initial
Table 1 Demographic Data. Variables
Control Group
Corail Group
Number of patients Gender (%) Male Female Age (y) No. of comorbidities ASA 3 and 4 (%) Dementia (%)
74
348
25.7 74.3 83 ± 8 2±1 54 24
23.9 76.1 82 ± 9 2±1 58 37
ASA, American Society of Anesthesiologists score; NS, not significant.
P-Value
NS NS NS NS NS .04
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Fig. 1. Comparison between the control group and the Corail group regarding periprosthetic fractures.
postoperative radiographs. In this case, decision was made to proceed with a prosthesis revision. Six of the 22 trochanteric fractures were recognized during surgery and treated with cerclage wire. Sixteen fractures of the greater trochanter were only recognized on routine postoperative imaging. Those fracture were treated conservatively. The fractures happened equally between institutions. Fractures around the calcar and/or trochanteric area recognized during surgery were fixed using the 1.7-mm cable system (DePuy Synthes). Fifty-nine cables were therefore required to fix the 43 recognized fractures intraoperatively in the treatment group compared to only 3 cables used to fix the 2 fractures in the control group. Analysis comparing patients in the treatment group who sustained a periprosthetic fracture (n ¼ 54) to patients without fracture (n ¼ 294) treated with the same prosthesis were performed to identify risk factors. No patient-related factor could be identified to explain the high number of fractures in the Corail treatment group (Table 2). Moreover, surgically related factors were also similar between groups (Table 3). Finally, the data regarding implantrelated factors could not identify a difference between the 2 groups (Table 4). Looking at the first 6 months after the implantation of the Corail stem, 10 fractures were recorded. This was in fact the lowest number of fractures in a 6-month period. The other 6month period in the chronological order recorded 13, 19, and 12 patients sustaining a periprosthetic fracture, respectively. Therefore, no learning curve effect could be demonstrated. We looked at leg lengths of the 54 patients in the Corail group who sustained a periprosthetic fracture. After surgery, 26 patients were shorter than their noninjured side or had the same leg length and 28 patients had their operated side longer than the noninjured leg. Of those 28 patients, 22 patients had a lengthening of 10 mm or less.
Table 2 Patient-Related Factors to Sustain a Periprosthetic Fracture Within the Corail Group.
Discussion There are many studies in the literature on the Corail stem, but all of them report on the cementless stem. This stem is widely used in primary and revision arthroplasty. According to the Norwegian arthroplasty registry [2], the uncemented primary Corail stem has a 10-year and 15-year survival rate of 98% and 97%, respectively. Many other studies confirm the good long-terms results of this stem [3e5]. Vidalain [3] explains their 10.9% intraoperative complications in 347 cases, including 33 calcar cracks, 3 fractures, and 2 perforations, to the learning curve and to the goal of achieving a closer cortical contact when broaching the femoral canal for a noncemented stem. In our cohort, patients were not classified according to their bone stock as this was a geriatric population with low energy trauma femoral neck fractures. Therefore, a cemented stem design was chosen to address the poor bone stock, as the broaching technique is usually less aggressive than in cementless stem design where cortical contact is mandatory. When using a cemented stem like in our series, the number of calcar fractures was expected to be lower. Wood et al [6] implanted the cementless Corail stem in 10 revision total hip replacement cases without any complication. Reikerås [7] also used this stem for revision. They reported 8 proximal femoral fractures intraoperatively requiring wire fixation in their 66 cases. The only study reporting the use of the Corail stem with bipolar head in displaced femoral neck fractures was published by Cawley et al [8] and used the cementless design. They report good results at 4.3 years of follow-up on their 68 patients with 1 patient requiring revision for subsidence of an undersized implant. No fracture occurred while seating the implant in this series.
Table 3 Surgically Related Factors to Sustain a Periprosthetic Fracture Within the Corail Group.
Risk Factors
Patient With Fracture (n ¼ 54)
Patient Without Fracture (n ¼ 294)
P-Value
Risk Factors
82 ± 9 17 57 33
82 ± 9 25 61 38
.58 .17 .64 .56
Patient Without Fracture (n ¼ 294)
P-Value
Age (y) Male (%) ASA 3 and 4 (%) Dementia (%)
Patient With Fracture (n ¼ 54)
Presence of surgical assistant (%) THA surgeon (%)
83
84
NS
46
38
NS
ASA, American Society of Anesthesiologists score.
THA, total hip arthroplasty; NS, not significant.
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Table 4 Implant-Related Factors to Sustain a Periprosthetic Fracture Within the Corail Group. Risk Factors
With Fracture (n ¼ 54)
Without Fracture (n ¼ 294)
P-Value
Stem size Neck length Short (%) Standard (%) Long (%) Head size
11 ± 2
11 ± 2
NS NS
46 44 9 46 ± 4
48 48 4 47 ± 4
NS
NS, not significant.
According to Louboutin et al [9], perioperative hip fracture rate is 4%. Our study demonstrated a high rate of intraoperative fractures compared to our control group and also compared to the literature. We tried to identify risk factors that could explain this phenomenon. Since this prosthesis design was newly implanted in our institutions, we looked at the learning curve since studies show a decreased complication rate as the number of prosthesis performed by the surgeon increases [10,11]. According to Nunley et al [12], the complication rate is higher in the first 25 prosthesis implanted. In our study, the learning curve effect could not be demonstrated since the lowest number of fractures was in the first 6-month period after the implantation of the Corail stem. We also looked at leg lengths, since significant lengthening of the operated limb could be an explanation for periprosthetic fracture. Since only half of our cohort had the operated side longer than the contralateral, this does not seem to be the main factor. We have 2 theories that could explain, at least partially, the high rate of intraoperative periprosthetic fractures in our cohort of cemented Corail stems coupled with a bipolar head. First, the offset difference between the smallest and the largest stem is small. According to the company’s brochure, the neck length is 39 mm, which is the same for all the stem sizes. The smallest stem has an offset of 38.3 mm. Those dimensions make it difficult to reduce the implant in the acetabulum due to the high offset and long neck even for small stems. When questioned, some surgeons tried to reduce the neck length by using a shorter neck length on the bipolar head, but this strategy failed to decrease the fracture number as shown in Table 4. This offset issue might also explain the high number of calcar cracks described in Vidalain’s study [3]. Moreover, if we compare the neck length and offset of another stem from the same company of the Corail, the C-stem (DePuy Synthes), the smallest stem has a neck length and offset of 30.5 and 35.5 mm, respectively. The neck length is 8.5 mm less and the offset is 2.8 mm less if we compare the smallest stem of both systems. Moreover, the largest C-stem stem as a neck length of 38 mm, which is 1 mm less than the entire Corail neck lengths. In fact, the smallest Corail neck length is 39 mm. Furthermore, if we compare the neck length and offset of the OmniFit EON 132 used in the control group, the smallest stem has a neck length and offset of 25 and 29 mm, respectively, and the largest stem has a neck length and offset of 40 and 48 mm, respectively. These significant differences might explain, at least partially, the difference in the number of calcar fractures between the 2 groups. As discussed by Parvizi [13], there is a wide variation in the morphology of native femurs and the Corail stem design with a large femoral offset may not be adequate for this population. Second, the bipolar head is fairly large, therefore the lever of arm to reduce the implant in the acetabular cavity is larger than in total hip replacement where the head is much smaller. The larger head led to a larger jumping distance to reduce or dislocate the implant and a larger moment of strength. This could explain the fractures when taking into consideration the exaggerated neck length and
offset compared to patient's anatomy since intraoperative calcar fracture was the most common fracture found in our cohort and usually occurred during prosthesis trial reduction when the leg was rotated to reduce the hip joint. Finally, greater trochanteric fractures can be explained, at least in part, by surgical approach. Most of the surgeons in our centers address femoral neck fractures using the Hardinge anterolateral hip approach. Gluteus medius reinsertion with transosseous tunnels at closure can fragilize the tip of the greater trochanter. Also, design of the implant might play a role. The fairly large offset of the implant can put too much tension on the muscular insertions on the greater trochanter and create a fracture. The corners of the trapezoidal proximal cross section of the Corail did not seem too sharp and could not explain the high number of greater trochanter fractures, but some surgeons felt that the Corail broaches for medullary canal preparation were aggressive. In fact, according to the company, the same broach instrumentation is used for cemented and cementless design. This instrumentation might be too aggressive for poor density bone as in this geriatric population and create greater trochanteric fracture while the surgeon tried to avoid varus positioning of the implant. Luckily, greater trochanteric fractures do not impact the stem’s stability and can be managed conservatively [14], but calcar fractures found during surgery were managed as recommended using cerclage wires to prevent stem subsidence [15]. Overall, intraoperative calcar and greater trochanteric fractures can certainly have detrimental effects on the postoperative care. Using cerclage wires increases surgical time and blood loss leading to an increased risk of infection. Patients can describe more pain after surgery and develop complications related to their decreased mobility secondary to their pain. This could definitely be part of another study. We have noted some limitations in the current study, mainly due to the retrospective nature of the study and the fact that the control group is fairly small compared to the study group. Using operative protocols and postoperative radiographs to look for the presence of a periprosthetic fracture might have induced a bias, since no patient underwent a computed tomography scan to confirm the fracture. Also, the learning curve effect is a difficult concept to evaluate. We decided to look at this as a group and not for every surgeon considering that the numbers were too small to evaluate individually. Finally, since we were looking at the perioperative fractures, no patients were lost to follow-up.
Conclusion The Corail cemented stem presents an abnormal number of iatrogenic intraoperative periprosthetic fractures following displaced femoral neck fractures in the geriatric population. Our number of fractures is above the expected percentage during an elective noncemented total hip arthroplasty and above the control group operated by the same group of surgeons. No external factor seems to explain this abnormal number of fractures. Implant design might be an important aspect to be evaluated in more details. Surgeons should be aware of this unexpected complication with this cemented stem used in this specific patient population.
Acknowledgments We would like to thank Guillaume Ruel for his contribution to the statistical analysis.
M. Laflamme et al. / The Journal of Arthroplasty xxx (2019) 1e5
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