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The fake unlocked femoral nail: A configuration to avoid in stable pertrochanteric femur fractures
Injury, Int. J. Care Injured 49S3 (2018) S32–S36
Contents lists available at ScienceDirect
Injury journal homepage: www.elsevier.com/locate/injury
The fake unlocked femoral nail: A configuration to avoid in stable pertrochanteric femur fractures Claudio Maria Mori, Giovanni Vicenti, Massimiliano Carrozzo* , Girolamo Picca, Davide Bizzoca, Andrea Leone, Arcangelo Morizio, Giuseppe Solarino, Biagio Moretti School of Medicine, University of Bari “Aldo Moro”, AOU Policlinico Consorziale, Department of Basic Medical Sciences, Neuroscience and Sense Organs, Orthopaedic & Trauma Unit, Bari, Italy
A R T I C L E I N F O
Keywords: Complications Distal locking Intramedullary nail Pertrochanteric fractures Nonunion Cut-out
A B S T R A C T
Background: Intramedullary unlocked nailing is a safe and used treatment for stable pertrocantheric fractures. Due to the femoral anterior bow of the shaft or a wrong entry point, the distal tip of the nail can be impinging the anterior cortex. This type of situation can compromise the function of the nail, leading to nonunion of the fracture, and cut-out. The aim of this study was to assess the relationship between nail impingement of the anterior cortex of the femur and cut-out and nonunion incidence in patients with pertrochanteric stable fracture treated with an IM nail in an unlocked configuration. Material and methods: A retrospective study based on medical records and imaging from the archives of our Level I academic medical center was conducted. The study included patients with proximal femoral fractures treated with short cephalomedullary nails between January 2012 and May 2015. The data collected were analyzed to a possible correlation with the healing time and occurrence of nonunion and cut-out. Results: The study population counted 429 cases. Applying the inclusion criteria the final series was composed of 169 patients: 112 females (66.73%) and 57 males (33.27%), with a mean age of 81.23 years (range: 67–93 years). Distal tip impingement was observed in 22 cases (13.02%). In total 16 (9.47%) postoperative complications were recorded: 8 non-union and 7 cut-outs. Consolidation was registered in 153 cases and the fracture healing time averaged 14.4 3.8 weeks (range, 11–24 weeks). The cortical impingement was correlated with nonunion and cut-out (p < 0.001) Logistic regression analysis revealed jamming sign significantly affected the fracture healing time (p < 0.001). Conclusion: The occurrence of cut-out and nonunion after cephalomedullary nailing of stable pertrochanteric fractures appear to be correlated to the presence of the cortical impingement. For this reason, the fake unlocked femoral nail with the cortical impingement is a configuration to avoid in stable pertrochanteric femur fractures. © 2018 Elsevier Ltd. All rights reserved.
Introduction The number of hip fractures worldwide will drastically increase in the next few decades and is estimated to surpass 6.3 million by 2050 [1,2]. The current standard of care of stable intertrochanteric hip fractures includes extramedullary fixation (hip screws) or intramedullary fixation (intramedullary nail). There is still insufficient evidence about the utility of the
* Corresponding author at: Department of Basic Medical Sciences, Neuroscience and Sense Organs, Orthopaedic Clinic, School of Medicine, University of Bari “Aldo Moro”, AOU Consorziale Policlinico, Piazza Giulio Cesare 11, 70100, Bari, Italy. E-mail address: [email protected] (M. Carrozzo). https://doi.org/10.1016/j.injury.2018.09.057 0020-1383/© 2018 Elsevier Ltd. All rights reserved.
distal locking in proximal femur intramedullary nailing. Some authors have stated that distal locking is not necessary for stable intertrochanteric fracture (AO/OTA 31-A1 and A2.1) [3–6]. Even though fixation failure occurs in up to 10 percent with some fracture patterns, some of the most commonly reported complications in the intramedullary fixation are the cut-out defined as “the collapse of the neck-shaft angle into varus, leading to extrusion of the screw from the femoral head” [7] and the nonunions [8]. Another intraoperative complication is the cortical impingement of the anterior cortex of the femur, also called the jamming effect, caused by the contact between the nail tip of the nail and the anterior femoral cortex [9–12].
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This complication seems to depend on the length of the nail and the mismatch between the curvature of the femur (especially in Hispanic and Asian population) and the radius of curvature (ROC) of the intramedullary nails available in the market [10,13,14]. Previous studies analyze clinical implications of cortical impingement, especially a possible correlation with thigh pain and femoral peri-implant fractures without focusing on the cutout and nonunion rates [10–12]. Our study aimed to assess the relationship between nail impingement of the anterior cortex of the femur and cut-out and nonunion incidence in patients with pertrochanteric stable fracture treated with an IM nail in an unlocked configuration We hypothesize that the patients with nail impingement present greater nonunion and cut-out rate than those without impingement after cephalomedullary nailing. It is hoped that these findings may better guide the surgeon in the prevention of these complications.
senior surgeons using the immediate postoperative standard anteroposterior (AP) and lateral (Lat) radiographs of the hip. Only the reductions that met the displacement criteria (less than 4 mm of displacement on either the AP or Lat X-ray) and the angulation criteria (neck shaft angulation normal or slightly valgus 135 and less than 20 of angulation in the Lat X-ray) were categorized good and included in the study. Also, the presence of distal tip impingement with the anterior cortex was registered (Fig. 1). Patients were followed clinically and radiographically at one month, three months, six months and 1-year postoperatively. Fracture union was defined as full weight-bearing without pain in a patient along with radiographic evidence of a bridging callus. Nonunion is defined as lack of bony consolidation after six months interval. The study population’s data were analyzed to find an eventual correlation with the occurrence of non-union or cut-out.
Materials and methods
Statistical analysis
A retrospective study based on medical records and imaging from the archives of our Level I academic medical center was conducted. The study included patients with proximal femoral fractures treated with short cephalomedullary nails between January 2012 and May 2015. The inclusion criteria were the presence of an acute (treatment within 15 days from trauma) pertrochanteric stable fracture (AO/ OTA 31-A1/31-A2.1) in patients aged over 65 years treated with an IM nail in an unlocked configuration (without the distal locking screw). Exclusion criteria were medical contraindications, medical illness or cognitive disorders, open fracture, bilateral fractures, open reduction, poor or non-acceptable reduction of the fracture, pathological fracture and previous ipsilateral hip or femur surgery, smoking and metabolic bone disease. Four different type of short intramedullary nail were used: Endovis BA and Endovis BA-2 (Citieffe, Bologna, Italy), PFNA (DePuy Synthes, Oberdorf, Switzerland) and Affixus (ZimmerBiomet, Warsaw, Indiana, USA). Table 1 summarize implants characteristics. Intramedullary nailing was performed under fluoroscopic control using an orthopedic traction table for reduction within 48 h from admission following the manufacturer’s instructions. Standard antibiotic prophylaxis with 2 g of cefazolin (Fosfomycin in allergic patients) and thromboembolic prophylaxis with enoxaparin was used. After introducing the patient to rehabilitative program on the first-day post-op, ambulation was allowed with crutches approximately 48–72 h after surgery. Evaluation of the quality of reduction according to Baumgaertner method [15,16], was carried out by two independent
Statistical analysis was performed using STATA/MP 14 for Windows (Stata Corp LP, College Station, USA). The Chi-square test was performed to compare the percentage of Jamming sign between groups. Statistical significance was set at p < 0.05. The logistic regression analysis was used to compare the independent variable (fracture healing time) and the dichotomic variable (Jamming sign). Results The population of patients treated with a cephalomedullary nail at our institution in the study period counted 429 cases. 216 patients out of 429 meet the inclusion and exclusion criteria; at 1year follow-up, however, 28 patients (16.57%) had died, and 19 were lost or had not attended the last examination. Thus, the final series was composed of 169 patients: 112 females (66.73%) and 57 males (33.27%), with a mean age of 81.23 years (range: 67–93 years). The primary data of the study are summarized in Table 2. There were 98 fractures (57.99%) of the right femur and 71 fractures (42.01%) of the left one. Based on the AO/OTA classification there were 118 31-A1-type fractures (65 A1.1; 43 A1.2; 30 A1.3) and 31 A2.1-type fractures. At 1-year follow-up, a distal tip impingement was observed in 22 cases (13.02%), 15 females and 7 males. We encountered in total 16 (9.47%) postoperative complications: 8 non-union and 7 cutouts (Fig. 2). 13 (81.25%) of these occurred in cases with concomitant distal tip impingement. Consolidation was registered in 153 cases and the fracture healing time averaged 14.4 3.8 weeks (range, 11–24 weeks). Table 3 shows the prevalence of jamming sign in fracture without nail cut-out compared with fracture with nail cut-out. A
Table 1 Endomedullary nails features used in the study. Nail type
PFNA EBA EBA 2 Affixus
Characteristics Length
Proximal diameter
Main diameter
Cephalic
CD angle
200 mm 195 mm 180 mm 180 mm
16.5 mm 13 mm 13 mm 15.6 mm
9 mm 10 mm 10 mm 9 mm
PFNA Blade 2 screws 2 screws 1 Lag screw 1 AR screw optional
125 or 130 130 130 125 or 130
CD: cervicodiaphyseal AR: Antirotation screw.
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Fig. 1. Schematic example of cortical impingment with a short nail.
Table 2 Main data of the study. Data # of patients Age Mean SD Range Gender Male. n (%) Female. n (%) BMI (Kg/m2) Mean SD Side Left. n (%) Right. n (%) AO Classification 31-A1.1 n (%) 31-A1.2 n (%) 31-A1.3 n (%) 31-A2.1 n (%) Union time (weeks)
169 81.236 11.8 67–93 57 (33.27%) 112 (66.73%) 27.6 5.1 71 (42.01%) 98 (57.99%) 65 43 30 31
(38.46%) (25.44%) (17.75%) (18.34%)
14 3.8 11–24
Range
Table 3 Jamming sign in fractures without cut-out versus fractures with cut-out, at 1-year follow-up: Chi-square test. Variable
Without cut-outa n (%)
Cut-outb n (%)
χ2
p-value
Jamming Sign
14 (8.75%)
8 (88.9%)
11.237
<0.001*
a b *
No complications (n = 160). Cut-out (n = 9). Significant p-value.
Table 4 Jamming sign in healed fractures versus non-union group, at 1-year follow-up: Chisquare test. Variables
Healed Fracturesa n (%)
Non-unionb n (%)
χ2
p-value
Jamming Sign
8 (5.23%)
6 (85.71%)
12.455
<0.001*
a b *
Healed fractures (n = 153). Non-union (n = 7). Significant p-value.
Table 5 Logistic Regression Analysis: Independent variable (Fracture Healing Time) Dependent variable (Jamming Sign). Variables
χ
2
p-value
OR
95% CI
Jamming Sign
11.95
<0.001*
2.98
1.85–4.92
*
Significant p-value.
significant difference between the two groups (p < 0.001) was found. In Table 4 the prevalence of jamming sign in healed groups compared with the non-union group is shown; a significant difference (p < 0.001) between the two groups was depicted. Logistic regression analysis (Table 5) revealed jamming sign significantly affected the fracture healing time (p < 0.001) and the 95% CI for the OR does not include one. Discussion Nowadays, intramedullary nailing represents the treatment of choice for stabilization of the majority of proximal femoral fractures [2,8,17]. Different authors confirm that pertrochanteric stable fractures can be treated successfully with intramedullary nails without distal locking, Rosenblum et al. describe in their biomechanical study that the insertion of the distal interlocking screw was not associated with change of the proximal femoral strain pattern. This demonstrates that a distal locking screw might not be necessary for stable pertrochanteric fractures [4]. Also, Vopat et al. stated that distal locking was not necessary when stable intertrochanteric fractures were treated with long nails [18]. Comparing outcomes and complications between two groups of patients treated with intramedullary nails for stable pertrochanteric fracture with or without distal locking screws Li et al. concluded that unlocked nail may be an acceptable and reliable option for these fracture pattern [3]. In a recent prospective, multicenter, randomized study [6] we also compared the use of short locked and short unlocked cephalomedullary nails in the treatment of pertrochanteric stable femur fractures in an elderly population. We detect no significant differences between the two groups. Moreover, we reported no differences concerning outcomes in each group and the few significant complications that occurred were equally distributed in the two groups. The study hypothesis proposed that patients with cortical impingement of the femur present greater nonunion and cut-out rate than those without impingement after cephalomedullary nailing. Our hypothesis was confirmed by the results of this study in which cortical impingement show a direct relationship with the incidence of cut-out and nonunion complications. Recently Murena et al. e. confirm the significant association of inadequate Tip Apex Distance and Parker’s AP ratio with cut-out. Moreover, they also confirm a significant association with quality of reduction, but they did not analyze the presence and association with cortical impingement [19]. Previous studies analyze clinical implications of cortical impingement, especially a possible correlation with thigh pain and femoral peri-implant fractures without focusing on the cutout and nonunion rates [10–12]. Peña et al. underline the importance of being vigilant of the tip impingement and cortical penetration when using currently
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Fig. 2. A-B-C-D-E: Case of an 83 years old lady with AO/OTA 32 A.1 fracture. B Immediate Post op X Ray shows a correct reduction of the fracture and the presence of the cortical impingmement. C 6 weeks post op no sign of union. D 2 months post op. Cut-out of cephalic screws. E X-ray post op pf the conversion to total hip arthroplasty after failed proximal femoral nail.
available nail systems, particularly for patients with a strong anterior bow [10]. They also affirm in a parallel study that cortical impingement of the anterior cortex of the femur was not associated with the presence of pain but that femoral fractures, and delayed union or nonunion of the fracture may occur theoretically in patients with cortical impingement [11]. Maniscalco et al. reported a case that the distal tip impingement to the anterior cortex can lead to a nonunion of the fracture, which is based on the principle that cortical impingement prevents the distal sliding of the nail within the diaphyseal canal, and so it interferes with the compression during the healing process under fracture loading [12]. In our opinion, the interference with the distal sliding of the nail determined by the cortical impingement does not influence the compression directly at the fracture level. If this is the case, we should register more complications in locked nails than unlocked nails in contrast with the literature [5,6,20,21]. We suggest that the cortical impingement determines mechanical stress at the level of the fracture and of at the level of cephalic screws. The bending moment results in torsional stress that leads to possible delay of healing time, nonunion or cut-out. Our study has some limitations. First, it was a retrospective analysis with a short duration of follow-up. Secondly, we did not analyze the different design of the nails like the presence of one
screw, two screws or blade or the different diameters and lengths. This can be a be a bias to keep in consideration Therefore, strengths should be addressed. To our knowledge, this is the first research that demonstrates a correlation between the cortical impingement after cephalomedullary nailing and nonunion and cut-out complications. Moreover, studies with longer follow-up and further biomechanical studies are required to confirm our conclusions. Conclusions The occurrence of cut-out and nonunion after cephalomedullary nailing of stable pertrochanteric fractures appear to be correlated to the presence of the cortical impingement. For this reason, the fake unlocked femoral nail with the cortical impingement is a configuration to avoid in stable pertrochanteric femur fractures. Nonetheless, in consideration of the limitations of the present work, further studies with biomechanical experiment may be necessary to confirm our conclusions. Conflict of interest statement There are no conflicts of interest do declare.
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Compliance with ethical standard This study was conducted in accordance with the declaration of Helsinki. informed consent was obtained from all participants. Funding No funding was provided for this study. References [1] Dhanwal D.K., Dennison EM, Harvey NC, Cooper C. Epidemiology of hip fracture: worldwide geographic variation. Indian J Orthop 2011;45:15–22, doi: http://dx.doi.org/10.4103/0019-5413.73656. [2] Rapp K, Büchele G, Dreinhöfer K, Bücking B, Becker C, Benzinger P. Epidemiology of hip fractures. Z Gerontol Geriatr 2018, doi:http://dx.doi. org/10.1007/s00391-018-1382-z. [3] Li X, Zhang L, Hou Z, Meng Z, Chen W, Wang P, et al. Distal locked and unlocked nailing for perthrochanteric fractures—a prospective comparative randomized study. Int Orthop 2015;39:1645–52, doi:http://dx.doi.org/10.1007/s00264015-2771-1. [4] Skála-Rosenbaum J, Džupa V, Bartoška R, Douša P, Waldauf P, Krbec M. Distal locking in short hip nails: cause or prevention of peri-implant fractures? Injury 2016, doi:http://dx.doi.org/10.1016/j.injury.2016.02.009. [5] Vopat BG, Kane PM, Truntzer J, McClure P, Paller D, Abbood E, et al. Is distal locking of long nails for intertrochanteric fractures necessary? A clinical study. J Clin Orthop Trauma 2014;5:233–9, doi:http://dx.doi.org/10.1016/j. jcot.2014.06.001. [6] Caiaffa V, Vicenti G, Mori C, Panella A, Conserva V, Corina G, et al. Is distal locking with short intramedullary nails necessary in stable pertrochanteric fractures? A prospective, multicentre, randomised study. Injury 2016;47 (Suppl. 4):S98–106, doi:http://dx.doi.org/10.1016/j.injury.2016.07.038. [7] Bojan AJ, Beimel C, Taglang G, Collin D, Ekholm C, Jönsson A. Critical factors in cut-out complication after Gamma Nail treatment of proximal femoral fractures. BMC Musculoskelet Disord 2013;14:1, doi:http://dx.doi.org/10.1186/ 1471-2474-14-1. [8] Tosounidis TH, Castillo R, Kanakaris NK, Giannoudis PV. Common complications in hip fracture surgery: tips/tricks and solutions to avoid them. Injury 2015;46: S3–11, doi:http://dx.doi.org/10.1016/j.injury.2015.08.006. [9] Robinson CM, Houshian S, Khan LAK. Trochanteric-entry long cephalomedullary nailing of subtrochanteric fractures caused by low-
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energy trauma. J Bone Jt Surg 2005;87:2217, doi:http://dx.doi.org/10.2106/ JBJS.D.02898. Peña OR, Gómez Gélvez A, Espinosa KA, Cardona JR. Cephalomedullary nails: factors associated with impingement of the anterior cortex of the femur in a Hispanic population. Arch Orthop Trauma Surg 2015;135:1533–40, doi:http:// dx.doi.org/10.1007/s00402-015-2313-8. Peña OR, Gómez Gélvez A, Espinosa KA. Clinical implications of impingement of the anterior femoral cortex after cephalomedullary nailing. Injury 2016;47:2300–6, doi:http://dx.doi.org/10.1016/j.injury.2016.06.025. Maniscalco P, Rivera F, D’Ascola J, Del Vecchio EO, Ascola JD, Olivier E, et al. Failure of intertrochanteric nailing due to distal nail jamming. J Orthop Traumatol 2013;14:71–4, doi:http://dx.doi.org/10.1007/s10195-012-0183-1. Chang S-M, Song D-L, Ma Z, Tao Y-L, Chen W-L, Zhang L-Z, et al. Mismatch of the short straight cephalomedullary nail (PFNA-II) with the anterior bow of the femur in an asian population. J Orthop Trauma 2014;28:17–22, doi:http://dx. doi.org/10.1097/BOT.0000000000000022. Zhang S, Zhang K, Wang Y, Feng W, Wang B, Yu B. Using three-dimensional computational modeling to compare the geometrical fitness of two kinds of proximal femoral intramedullary nail for Chinese femur. Sci World J 2013;2013:1–6, doi:http://dx.doi.org/10.1155/2013/978485. Baumgaertner MR, Solberg BD. Awareness of tip-apex distance reduces failure of fixation of trochanteric fractures of the hip. J Bone Joint Surg Br 1997;79:969–71. Baumgaertner MR, Curtin SL, Lindskog DM, Keggi JM. The value of the tip-apex distance in predicting failure of fixation of peritrochanteric fractures of the hip. J Bone Joint Surg Am 1995;77:1058–64. Studer P, Suhm N, Wang Q, Rosenthal R, HA-F Saleh, Jakob M. Displaced trochanteric fragments lead to poor functional outcome in pertrochanteric fractures treated by cephalomedullary nails. Injury 2015;46:2384–8, doi: http://dx.doi.org/10.1016/j.injury.2015.06.040. Vopat B, Kane P, Paller DJ, Hsu R, Koruprolu S, Abbood E, et al. Dynamic versus static distal interlocks of long cephomedullary nails for unstable intertrochanteric fracture ORS 2014. Annual Meeting. . Murena L, Moretti A, Meo F, Saggioro E, Barbati G, Ratti C, et al. Predictors of cut-out after cephalomedullary nail fixation of pertrochanteric fractures: a retrospective study of 813 patients. Arch Orthop Trauma Surg 2018;138:351–9, doi:http://dx.doi.org/10.1007/s00402-017-2863-z. Yun HH, Yoon JR, Seo HS, Yu JJ. Is Distal Locking Constantly Necessary When Intertrochanteric Femur Fracture Is Stably Fixed in the Distal Area with Intramedullary Hip Nail? J Korean Orthop Assoc 2015;50:8–17. Skála-Rosenbaum J, Bartoní9 cek J, Bartoška R. Is distal locking with IMHN necessary in every pertrochanteric fracture? Int Orthop 2010;34:1041–7, doi: http://dx.doi.org/10.1007/s00264-009-0874-2.
Contents lists available at ScienceDirect
Injury journal homepage: www.elsevier.com/locate/injury
The fake unlocked femoral nail: A configuration to avoid in stable pertrochanteric femur fractures Claudio Maria Mori, Giovanni Vicenti, Massimiliano Carrozzo* , Girolamo Picca, Davide Bizzoca, Andrea Leone, Arcangelo Morizio, Giuseppe Solarino, Biagio Moretti School of Medicine, University of Bari “Aldo Moro”, AOU Policlinico Consorziale, Department of Basic Medical Sciences, Neuroscience and Sense Organs, Orthopaedic & Trauma Unit, Bari, Italy
A R T I C L E I N F O
Keywords: Complications Distal locking Intramedullary nail Pertrochanteric fractures Nonunion Cut-out
A B S T R A C T
Background: Intramedullary unlocked nailing is a safe and used treatment for stable pertrocantheric fractures. Due to the femoral anterior bow of the shaft or a wrong entry point, the distal tip of the nail can be impinging the anterior cortex. This type of situation can compromise the function of the nail, leading to nonunion of the fracture, and cut-out. The aim of this study was to assess the relationship between nail impingement of the anterior cortex of the femur and cut-out and nonunion incidence in patients with pertrochanteric stable fracture treated with an IM nail in an unlocked configuration. Material and methods: A retrospective study based on medical records and imaging from the archives of our Level I academic medical center was conducted. The study included patients with proximal femoral fractures treated with short cephalomedullary nails between January 2012 and May 2015. The data collected were analyzed to a possible correlation with the healing time and occurrence of nonunion and cut-out. Results: The study population counted 429 cases. Applying the inclusion criteria the final series was composed of 169 patients: 112 females (66.73%) and 57 males (33.27%), with a mean age of 81.23 years (range: 67–93 years). Distal tip impingement was observed in 22 cases (13.02%). In total 16 (9.47%) postoperative complications were recorded: 8 non-union and 7 cut-outs. Consolidation was registered in 153 cases and the fracture healing time averaged 14.4 3.8 weeks (range, 11–24 weeks). The cortical impingement was correlated with nonunion and cut-out (p < 0.001) Logistic regression analysis revealed jamming sign significantly affected the fracture healing time (p < 0.001). Conclusion: The occurrence of cut-out and nonunion after cephalomedullary nailing of stable pertrochanteric fractures appear to be correlated to the presence of the cortical impingement. For this reason, the fake unlocked femoral nail with the cortical impingement is a configuration to avoid in stable pertrochanteric femur fractures. © 2018 Elsevier Ltd. All rights reserved.
Introduction The number of hip fractures worldwide will drastically increase in the next few decades and is estimated to surpass 6.3 million by 2050 [1,2]. The current standard of care of stable intertrochanteric hip fractures includes extramedullary fixation (hip screws) or intramedullary fixation (intramedullary nail). There is still insufficient evidence about the utility of the
* Corresponding author at: Department of Basic Medical Sciences, Neuroscience and Sense Organs, Orthopaedic Clinic, School of Medicine, University of Bari “Aldo Moro”, AOU Consorziale Policlinico, Piazza Giulio Cesare 11, 70100, Bari, Italy. E-mail address: [email protected] (M. Carrozzo). https://doi.org/10.1016/j.injury.2018.09.057 0020-1383/© 2018 Elsevier Ltd. All rights reserved.
distal locking in proximal femur intramedullary nailing. Some authors have stated that distal locking is not necessary for stable intertrochanteric fracture (AO/OTA 31-A1 and A2.1) [3–6]. Even though fixation failure occurs in up to 10 percent with some fracture patterns, some of the most commonly reported complications in the intramedullary fixation are the cut-out defined as “the collapse of the neck-shaft angle into varus, leading to extrusion of the screw from the femoral head” [7] and the nonunions [8]. Another intraoperative complication is the cortical impingement of the anterior cortex of the femur, also called the jamming effect, caused by the contact between the nail tip of the nail and the anterior femoral cortex [9–12].
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This complication seems to depend on the length of the nail and the mismatch between the curvature of the femur (especially in Hispanic and Asian population) and the radius of curvature (ROC) of the intramedullary nails available in the market [10,13,14]. Previous studies analyze clinical implications of cortical impingement, especially a possible correlation with thigh pain and femoral peri-implant fractures without focusing on the cutout and nonunion rates [10–12]. Our study aimed to assess the relationship between nail impingement of the anterior cortex of the femur and cut-out and nonunion incidence in patients with pertrochanteric stable fracture treated with an IM nail in an unlocked configuration We hypothesize that the patients with nail impingement present greater nonunion and cut-out rate than those without impingement after cephalomedullary nailing. It is hoped that these findings may better guide the surgeon in the prevention of these complications.
senior surgeons using the immediate postoperative standard anteroposterior (AP) and lateral (Lat) radiographs of the hip. Only the reductions that met the displacement criteria (less than 4 mm of displacement on either the AP or Lat X-ray) and the angulation criteria (neck shaft angulation normal or slightly valgus 135 and less than 20 of angulation in the Lat X-ray) were categorized good and included in the study. Also, the presence of distal tip impingement with the anterior cortex was registered (Fig. 1). Patients were followed clinically and radiographically at one month, three months, six months and 1-year postoperatively. Fracture union was defined as full weight-bearing without pain in a patient along with radiographic evidence of a bridging callus. Nonunion is defined as lack of bony consolidation after six months interval. The study population’s data were analyzed to find an eventual correlation with the occurrence of non-union or cut-out.
Materials and methods
Statistical analysis
A retrospective study based on medical records and imaging from the archives of our Level I academic medical center was conducted. The study included patients with proximal femoral fractures treated with short cephalomedullary nails between January 2012 and May 2015. The inclusion criteria were the presence of an acute (treatment within 15 days from trauma) pertrochanteric stable fracture (AO/ OTA 31-A1/31-A2.1) in patients aged over 65 years treated with an IM nail in an unlocked configuration (without the distal locking screw). Exclusion criteria were medical contraindications, medical illness or cognitive disorders, open fracture, bilateral fractures, open reduction, poor or non-acceptable reduction of the fracture, pathological fracture and previous ipsilateral hip or femur surgery, smoking and metabolic bone disease. Four different type of short intramedullary nail were used: Endovis BA and Endovis BA-2 (Citieffe, Bologna, Italy), PFNA (DePuy Synthes, Oberdorf, Switzerland) and Affixus (ZimmerBiomet, Warsaw, Indiana, USA). Table 1 summarize implants characteristics. Intramedullary nailing was performed under fluoroscopic control using an orthopedic traction table for reduction within 48 h from admission following the manufacturer’s instructions. Standard antibiotic prophylaxis with 2 g of cefazolin (Fosfomycin in allergic patients) and thromboembolic prophylaxis with enoxaparin was used. After introducing the patient to rehabilitative program on the first-day post-op, ambulation was allowed with crutches approximately 48–72 h after surgery. Evaluation of the quality of reduction according to Baumgaertner method [15,16], was carried out by two independent
Statistical analysis was performed using STATA/MP 14 for Windows (Stata Corp LP, College Station, USA). The Chi-square test was performed to compare the percentage of Jamming sign between groups. Statistical significance was set at p < 0.05. The logistic regression analysis was used to compare the independent variable (fracture healing time) and the dichotomic variable (Jamming sign). Results The population of patients treated with a cephalomedullary nail at our institution in the study period counted 429 cases. 216 patients out of 429 meet the inclusion and exclusion criteria; at 1year follow-up, however, 28 patients (16.57%) had died, and 19 were lost or had not attended the last examination. Thus, the final series was composed of 169 patients: 112 females (66.73%) and 57 males (33.27%), with a mean age of 81.23 years (range: 67–93 years). The primary data of the study are summarized in Table 2. There were 98 fractures (57.99%) of the right femur and 71 fractures (42.01%) of the left one. Based on the AO/OTA classification there were 118 31-A1-type fractures (65 A1.1; 43 A1.2; 30 A1.3) and 31 A2.1-type fractures. At 1-year follow-up, a distal tip impingement was observed in 22 cases (13.02%), 15 females and 7 males. We encountered in total 16 (9.47%) postoperative complications: 8 non-union and 7 cutouts (Fig. 2). 13 (81.25%) of these occurred in cases with concomitant distal tip impingement. Consolidation was registered in 153 cases and the fracture healing time averaged 14.4 3.8 weeks (range, 11–24 weeks). Table 3 shows the prevalence of jamming sign in fracture without nail cut-out compared with fracture with nail cut-out. A
Table 1 Endomedullary nails features used in the study. Nail type
PFNA EBA EBA 2 Affixus
Characteristics Length
Proximal diameter
Main diameter
Cephalic
CD angle
200 mm 195 mm 180 mm 180 mm
16.5 mm 13 mm 13 mm 15.6 mm
9 mm 10 mm 10 mm 9 mm
PFNA Blade 2 screws 2 screws 1 Lag screw 1 AR screw optional
125 or 130 130 130 125 or 130
CD: cervicodiaphyseal AR: Antirotation screw.
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Fig. 1. Schematic example of cortical impingment with a short nail.
Table 2 Main data of the study. Data # of patients Age Mean SD Range Gender Male. n (%) Female. n (%) BMI (Kg/m2) Mean SD Side Left. n (%) Right. n (%) AO Classification 31-A1.1 n (%) 31-A1.2 n (%) 31-A1.3 n (%) 31-A2.1 n (%) Union time (weeks)
169 81.236 11.8 67–93 57 (33.27%) 112 (66.73%) 27.6 5.1 71 (42.01%) 98 (57.99%) 65 43 30 31
(38.46%) (25.44%) (17.75%) (18.34%)
14 3.8 11–24
Range
Table 3 Jamming sign in fractures without cut-out versus fractures with cut-out, at 1-year follow-up: Chi-square test. Variable
Without cut-outa n (%)
Cut-outb n (%)
χ2
p-value
Jamming Sign
14 (8.75%)
8 (88.9%)
11.237
<0.001*
a b *
No complications (n = 160). Cut-out (n = 9). Significant p-value.
Table 4 Jamming sign in healed fractures versus non-union group, at 1-year follow-up: Chisquare test. Variables
Healed Fracturesa n (%)
Non-unionb n (%)
χ2
p-value
Jamming Sign
8 (5.23%)
6 (85.71%)
12.455
<0.001*
a b *
Healed fractures (n = 153). Non-union (n = 7). Significant p-value.
Table 5 Logistic Regression Analysis: Independent variable (Fracture Healing Time) Dependent variable (Jamming Sign). Variables
χ
2
p-value
OR
95% CI
Jamming Sign
11.95
<0.001*
2.98
1.85–4.92
*
Significant p-value.
significant difference between the two groups (p < 0.001) was found. In Table 4 the prevalence of jamming sign in healed groups compared with the non-union group is shown; a significant difference (p < 0.001) between the two groups was depicted. Logistic regression analysis (Table 5) revealed jamming sign significantly affected the fracture healing time (p < 0.001) and the 95% CI for the OR does not include one. Discussion Nowadays, intramedullary nailing represents the treatment of choice for stabilization of the majority of proximal femoral fractures [2,8,17]. Different authors confirm that pertrochanteric stable fractures can be treated successfully with intramedullary nails without distal locking, Rosenblum et al. describe in their biomechanical study that the insertion of the distal interlocking screw was not associated with change of the proximal femoral strain pattern. This demonstrates that a distal locking screw might not be necessary for stable pertrochanteric fractures [4]. Also, Vopat et al. stated that distal locking was not necessary when stable intertrochanteric fractures were treated with long nails [18]. Comparing outcomes and complications between two groups of patients treated with intramedullary nails for stable pertrochanteric fracture with or without distal locking screws Li et al. concluded that unlocked nail may be an acceptable and reliable option for these fracture pattern [3]. In a recent prospective, multicenter, randomized study [6] we also compared the use of short locked and short unlocked cephalomedullary nails in the treatment of pertrochanteric stable femur fractures in an elderly population. We detect no significant differences between the two groups. Moreover, we reported no differences concerning outcomes in each group and the few significant complications that occurred were equally distributed in the two groups. The study hypothesis proposed that patients with cortical impingement of the femur present greater nonunion and cut-out rate than those without impingement after cephalomedullary nailing. Our hypothesis was confirmed by the results of this study in which cortical impingement show a direct relationship with the incidence of cut-out and nonunion complications. Recently Murena et al. e. confirm the significant association of inadequate Tip Apex Distance and Parker’s AP ratio with cut-out. Moreover, they also confirm a significant association with quality of reduction, but they did not analyze the presence and association with cortical impingement [19]. Previous studies analyze clinical implications of cortical impingement, especially a possible correlation with thigh pain and femoral peri-implant fractures without focusing on the cutout and nonunion rates [10–12]. Peña et al. underline the importance of being vigilant of the tip impingement and cortical penetration when using currently
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Fig. 2. A-B-C-D-E: Case of an 83 years old lady with AO/OTA 32 A.1 fracture. B Immediate Post op X Ray shows a correct reduction of the fracture and the presence of the cortical impingmement. C 6 weeks post op no sign of union. D 2 months post op. Cut-out of cephalic screws. E X-ray post op pf the conversion to total hip arthroplasty after failed proximal femoral nail.
available nail systems, particularly for patients with a strong anterior bow [10]. They also affirm in a parallel study that cortical impingement of the anterior cortex of the femur was not associated with the presence of pain but that femoral fractures, and delayed union or nonunion of the fracture may occur theoretically in patients with cortical impingement [11]. Maniscalco et al. reported a case that the distal tip impingement to the anterior cortex can lead to a nonunion of the fracture, which is based on the principle that cortical impingement prevents the distal sliding of the nail within the diaphyseal canal, and so it interferes with the compression during the healing process under fracture loading [12]. In our opinion, the interference with the distal sliding of the nail determined by the cortical impingement does not influence the compression directly at the fracture level. If this is the case, we should register more complications in locked nails than unlocked nails in contrast with the literature [5,6,20,21]. We suggest that the cortical impingement determines mechanical stress at the level of the fracture and of at the level of cephalic screws. The bending moment results in torsional stress that leads to possible delay of healing time, nonunion or cut-out. Our study has some limitations. First, it was a retrospective analysis with a short duration of follow-up. Secondly, we did not analyze the different design of the nails like the presence of one
screw, two screws or blade or the different diameters and lengths. This can be a be a bias to keep in consideration Therefore, strengths should be addressed. To our knowledge, this is the first research that demonstrates a correlation between the cortical impingement after cephalomedullary nailing and nonunion and cut-out complications. Moreover, studies with longer follow-up and further biomechanical studies are required to confirm our conclusions. Conclusions The occurrence of cut-out and nonunion after cephalomedullary nailing of stable pertrochanteric fractures appear to be correlated to the presence of the cortical impingement. For this reason, the fake unlocked femoral nail with the cortical impingement is a configuration to avoid in stable pertrochanteric femur fractures. Nonetheless, in consideration of the limitations of the present work, further studies with biomechanical experiment may be necessary to confirm our conclusions. Conflict of interest statement There are no conflicts of interest do declare.
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