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Problems in plating periprosthetic femur fractures
S49 Injury, Int. J. Care Injured 49S1 (2018) S49–S50 Volume 49 Supplement 1 June 2018 ISSN 0020-1383
Contents lists available at ScienceDirect
Injury Plating of Fractures: current treatments and complications Guest Editors: Peter Augat and Sune Larsson
j o u r n a l h o m e p a g e : w w w. e l s e v i e r . c o m / l o c a t e / i n j u r y
Problems in plating periprosthetic femur fractures Andrew H. Schmidta,* a
Department of Orthopaedic Surgery, Hennepin County Medical Center, Minneapolis, Minnesota, USA
K E Y W O R D S
A B S T R A C T
Periprosthetic fracture Femur Tibia Arthroplasty Fragility fracture Osteoporosis
Periprosthetic fractures are typically defined as fractures occurring adjacent to a total joint arthroplasty. However, fractures may occur adjacent to a previous internal fixation device used to treat a prior fracture in the same patient, or between implants (the interprosthetic fracture). All of these injuries tend to occur in frail patients with severe osteopenia, and therefore are very challenging to treat. This article provides a brief but thorough review of the current state of the art regarding the treatment of these challenging problems. © 2018 Elsevier Ltd. All rights reserved.
Scope of the problem Periprosthetic fractures represent a heterogeneous set of injuries and circumstances, and are one of the most challenging problems for the orthopedist to manage. Their optimum care requires a multidisciplinary team that can attend to all of the medical and rehabilitation needs of the patient with such an injury, as these fractures typically occur in very frail patients with complex comorbidities and social problems. One has to address not only the fracture, but consider how to deal with the associated arthroplasty, the patient’s (and the family’s) expectations for return-to-function, and do so in a way that minimizes the risk of complications. Obtaining appropriate fixation Periprosthetic fractures, by definition, occur adjacent to an arthroplasty that in many cases limits options for fixation. For femoral fractures about a total hip arthroplasty (THA) stem, the greatest challenge is in getting stable diaphyseal fixation about the intramedullary femoral stem. The femoral component of a THA fills the medullary canal and makes intramedullary nailing of the femur impossible as a form of fixation, and makes plate fixation a challenge. THA stems may be cemented or uncemented, and each presents different challenges for fixation. For distal femoral fracture near a total knee arthroplasty (TKA), the femoral component of the TKA may have a stem, lugs, and/or a “box” (if posterior stabilized) that fill some of the metaphyseal bone, reducing the volume of bone available for fixation and limiting screw trajectories. Finally, periarticular stress-shielding reduces local bone mineral density and contributes to greater fracture comminution, which also increases the difficulty of fracture fixation.
* Corresponding author at: Hennepin County Medical Center, Department of Orthopaedic Surgery, Mailcode G2, 701 Park Ave. South, Minneapolis, MN 55415, USA E-mail address: [email protected] (A.H. Schmidt). 0020-1383/© 2018 Elsevier Ltd. All rights reserved.
Several methods of fracture fixation can be used for periprosthetic fractures, including non-locking plates, locking plates, hybrid plates that accommodate both locked and non-locking screws, so-called cable-plates that facilitate the use of cerclage cables, and strut grafts, which may be used alone or in addition to a plate. Fractures about THA stems The optimal method of periprosthetic fracture fixation remains undefined. Dennis et al. used a biomechanical model to evaluate the fixation stability of five methods of fracture fixation [1]. Simulated periprosthetic fractures were created in 30 synthetic femurs and were fixed with various combinations of cables, unicortical screws, bicortical screws, or cortical allograft strut grafts with cables. When tested, the constructs with proximal unicortical screws (with or without cables) and distal bicortical screws were significantly more stable in axial compression, lateral bending, and torsional loading than the other fixation constructs studied [1]. Similarly, Zdero et al. studied four combinations of fixation in a synthetic femur with a cemented stem: a locking plate with proximal unicortical and distal bicortical screws; a locking plate with two cables and two locked unicortical screws proximal and locked bicortical screws distally; a nonlocking plate with two cables and two unicortical screws proximal and bicortical screws distally; and lastly the same construct with an anterior cortical strut graft [2]. The last construct (nonlocking plate with a combination of cables and unicortical screws proximally, bicortical screws distally, and an anterior cortical strut graft had the greatest stiffness in axial compression, lateral bending, and torsion [2]. The two locking plate constructs were the weakest in all testing modes, and performed the worst in resisting lateral bending [2]. Moazen and colleagues summarize the results of biomechanical testing of fixation methods of fixation for periprosthetic fractures, noting that increased rigidity improves fracture stability whether measured by stiffness or fracture motion [3]. In general, one may increase rigidity by increasing the number of plates and/or struts, that screws are more rigid than cables, which
S50
A.H. Schmidt / Injury, Int. J. Care Injured 49S1 (2018) S49–S50
in turn are more rigid than wires [3]. Finally, Moazen et al. point out that it is difficult to draw general conclusions because the available literature suffers from lack of standardization in testing procedures and measurements [3]. Areas needing more research include the role of strut grafts and what parameters are most important (such as length vs, fit), the ideal location for strut grafts, and the relative benefits of locking compared to non-locking plates [3]. New plate designs exist that are designed specifically for use in periprosthetic fractures and which facilitate off-axis screw placement. Tangential, or off-axis screws, not only allow one to “miss” an implant in the center of the medullary canal, but engage a greater thickness of cortical bone than a unicortical screw aimed at the medullary canal, and therefore may be more rigid. The biomechanical performance of two such constructs was studied by Lewis et al, who compared five methods of fixation in a series of 30 synthetic composite femurs with cemented femoral stems [4]. Specimens were loaded to failure in either axial compression or torsion. The cable construct was the weakest in both loading modes, followed by the locked unicortical screws. The addition of cables to the locked unicortical screw construct was not significantly stronger [4]. The two constructs with tangential, off-axis screws were strongest [4]. Ruchholtz et al. reported a clinical series of 41 patients treated using one such construct [5]. The patients included had 17 fractures about a THA, 10 around a TKA, 3 were interprosthetic, and 11 were about an intramedullary nail [5]. Overall, 88% of the plates were longer than 24 cm, and an average of 5.3 screws were inserted around the implant [5]. There were two nonunions resulting in plate breakage 6 months after surgery. The authors concluded that these plates facilitate less-invasive surgery, and when long plates are used, complications are few. Distal femur fractures above a TKA and interprosthetic fractures The clinical outcome of locking plates in distal femoral fractures as reported in the literature appears to be mixed. Some series report high complications rates [6]. Ebraheim et al. reported a 37% complication rate in 27 patients with fractures about a TKA.6 In contrast, Streubel et al. reported a 15% complication rate overall, but the “extreme” distal fractures treated with a lateral locked plate only had a 9% failure rate [7]. However, there are data suggesting that locking pre-contoured lateral femoral plates are too stiff, and that their use is associated with decreased callus formation and increased rate of nonunion. Henderson et al. retrospectively reviewed 86 distal femur fractures and examined various patient and treatment variables that affected healing [8]. Overall, 40% of the patients experienced complications, including 20% who’s fractures failed to unite. The constructs used in the healed fractures were more flexible, with more empty screws holes in the fractures that healed, and patients treated with titanium plates were more likely to heal than those with stainless steel plates [8]. In another paper from the same center, the volume of callus was compared in a matched series of 24 patients: 12 treated with locking plates and 12 were treated with retrograde nails [9]. Periosteal callus was measured using special image-processing software on anteroposterior and lateral radiographs at 12 weeks. The retrograde nail group had 2.4 times more callus area per location (231±304 mm2) than the locking plate group (95±109 mm2, P=0.028). These investigators concluded that significantly less periosteal callus forms in fractures stabilized with locking plates compared to retrograde intramedullary nails, and that construct stiffness is likely the important difference [9]. With the recognition of construct stiffness being important in callus formation and fracture healing, a number of methods are being proposed that increase the flexibility of fixation. These include using longer plates with fewer screws, titanium rather than stainless steel,
and methods such as far-cortical locking [10]. The clinical utility of these various methods is a focus of current research. Other problems and future research directions As in other areas of surgery, there may be benefits to stabilizing periprosthetic fractures using minimally-invasive techniques. In order to facilitate that, methods and tools that facilitate minimallyinvasive fracture reduction must be developed. Secondly, these patients are at risk for further fracture, and one must always consider how to prevent the next fracture. For this reason, extramedullary constructs that span and will protect the entire femur are needed for these patients. Finally, given how medically frail these patients are, methods to “boost” the biologic response to a fracture in these patients would be of obvious benefit. Other questions that remain include: • •
•
What is the current role for cerclage fixation? Is cerclage helpful for fracture reduction? For fixation? What is current role for allograft struts? Do such struts improve stability or fracture healing with current fixation devices? Do the biomechanical advantages of strut grafts demonstrated in the lab confer real clinical benefits, and do these benefits outweigh the costs (real and biologic)? What is the optimum fixation construct for different clinical situations?
Disclosure AHS discloses the following relationships. He reports serving as a consultant to Acumed, Conventus Orthopaedics and Alexion; stock ownership in Epix Orthopaedics, Conventus Orthopaedics and ActivOrtho; patent applications/registrations with Acumed and having received royalties from Smith & Nephew. Acknowledgment The authors of this manuscript express their thanks to the Osteosynthesis and Trauma Care Foundation for the sponsorship of the publication of this Supplement in Injury. References [1] Dennis MG, Simon JA, Kummer FJ, Koval KJ, DiCesare PE. Fixation of periprosthetic femoral shaft fractures occurring at the tip of the stem. a biomechanical study of 5 techniques. J Arthroplasty 2000;15(4):523–8. [2] Zdero R, Walker R, Waddell JP, Schemitsch EH. Biomechanical evaluation of periprosthetic femoral fracture fixation. J Bone Joint Surg Am 2008;90-A:1068–1077. [3] Moazen M, Jones AC, Jin J, Wilcox RK, Tsiridis E. Periprosthetic fracture fixation of the femur following total hip arthroplasty: A review of biomechanical testing. Clin Biomech 2011;26:13–22. [4] Lewis GS, Caroom CT, Wee H, et al. Tangential bicortical locked fixation improves stability in vancouver b1 periprosthetic femur fractures: A biomechanical study. J Orthop Trauma 2015;29:e364–e370. [5] Ruchholtz S, El-Zayat B, Kreslo D, et al. Less invasive polyaxial locking plate fixation in periprosthetic and peri-implant fractures of the femur: a prospective study of 41 patients. Injury 2013;44:239–248. [6] Ebraheim NA, Liu J, Hashmi SZ, et al. High complication rate in locking plate fixation of lower periprosthetic distal femur fractures in patients with total knee arthroplasties. J Arthroplasty 2012;27:809–813. [7] Streubel PN, Gardner MJ, Morshed S, Collinge CA, Gallagher B, Ricci WM. Are extreme distal periprosthetic supracondylar fractures of the femur too distal to fix using a lateral locked plate? J Bone Joint Surg Br 2010;92-B:527–534. [8] Henderson CE, Lujan TJ, Kuhl LL, Bottlang M, Fitzpatrick DC, Marsh JL. Healing complications are common after locked plating for distal femur fractures. Clin Orthop Rel Res 2011;469:1757–1765. [9] Henderson CE, Lujan T, Bottlang M, Fitzpatrick DC, Madey SM, Marsh JL. Stabilization of distal femur fractures with intramedullary nails and locking plates: differences in callus formation. Iowa Orthop J 2010:30:61–68. [10] Beltran MJ, Collinge CA, Gardner MJ. Stress modulation of fracture fixation implants. J Am Acad Orthop Surg 2016;24:711–719.
Contents lists available at ScienceDirect
Injury Plating of Fractures: current treatments and complications Guest Editors: Peter Augat and Sune Larsson
j o u r n a l h o m e p a g e : w w w. e l s e v i e r . c o m / l o c a t e / i n j u r y
Problems in plating periprosthetic femur fractures Andrew H. Schmidta,* a
Department of Orthopaedic Surgery, Hennepin County Medical Center, Minneapolis, Minnesota, USA
K E Y W O R D S
A B S T R A C T
Periprosthetic fracture Femur Tibia Arthroplasty Fragility fracture Osteoporosis
Periprosthetic fractures are typically defined as fractures occurring adjacent to a total joint arthroplasty. However, fractures may occur adjacent to a previous internal fixation device used to treat a prior fracture in the same patient, or between implants (the interprosthetic fracture). All of these injuries tend to occur in frail patients with severe osteopenia, and therefore are very challenging to treat. This article provides a brief but thorough review of the current state of the art regarding the treatment of these challenging problems. © 2018 Elsevier Ltd. All rights reserved.
Scope of the problem Periprosthetic fractures represent a heterogeneous set of injuries and circumstances, and are one of the most challenging problems for the orthopedist to manage. Their optimum care requires a multidisciplinary team that can attend to all of the medical and rehabilitation needs of the patient with such an injury, as these fractures typically occur in very frail patients with complex comorbidities and social problems. One has to address not only the fracture, but consider how to deal with the associated arthroplasty, the patient’s (and the family’s) expectations for return-to-function, and do so in a way that minimizes the risk of complications. Obtaining appropriate fixation Periprosthetic fractures, by definition, occur adjacent to an arthroplasty that in many cases limits options for fixation. For femoral fractures about a total hip arthroplasty (THA) stem, the greatest challenge is in getting stable diaphyseal fixation about the intramedullary femoral stem. The femoral component of a THA fills the medullary canal and makes intramedullary nailing of the femur impossible as a form of fixation, and makes plate fixation a challenge. THA stems may be cemented or uncemented, and each presents different challenges for fixation. For distal femoral fracture near a total knee arthroplasty (TKA), the femoral component of the TKA may have a stem, lugs, and/or a “box” (if posterior stabilized) that fill some of the metaphyseal bone, reducing the volume of bone available for fixation and limiting screw trajectories. Finally, periarticular stress-shielding reduces local bone mineral density and contributes to greater fracture comminution, which also increases the difficulty of fracture fixation.
* Corresponding author at: Hennepin County Medical Center, Department of Orthopaedic Surgery, Mailcode G2, 701 Park Ave. South, Minneapolis, MN 55415, USA E-mail address: [email protected] (A.H. Schmidt). 0020-1383/© 2018 Elsevier Ltd. All rights reserved.
Several methods of fracture fixation can be used for periprosthetic fractures, including non-locking plates, locking plates, hybrid plates that accommodate both locked and non-locking screws, so-called cable-plates that facilitate the use of cerclage cables, and strut grafts, which may be used alone or in addition to a plate. Fractures about THA stems The optimal method of periprosthetic fracture fixation remains undefined. Dennis et al. used a biomechanical model to evaluate the fixation stability of five methods of fracture fixation [1]. Simulated periprosthetic fractures were created in 30 synthetic femurs and were fixed with various combinations of cables, unicortical screws, bicortical screws, or cortical allograft strut grafts with cables. When tested, the constructs with proximal unicortical screws (with or without cables) and distal bicortical screws were significantly more stable in axial compression, lateral bending, and torsional loading than the other fixation constructs studied [1]. Similarly, Zdero et al. studied four combinations of fixation in a synthetic femur with a cemented stem: a locking plate with proximal unicortical and distal bicortical screws; a locking plate with two cables and two locked unicortical screws proximal and locked bicortical screws distally; a nonlocking plate with two cables and two unicortical screws proximal and bicortical screws distally; and lastly the same construct with an anterior cortical strut graft [2]. The last construct (nonlocking plate with a combination of cables and unicortical screws proximally, bicortical screws distally, and an anterior cortical strut graft had the greatest stiffness in axial compression, lateral bending, and torsion [2]. The two locking plate constructs were the weakest in all testing modes, and performed the worst in resisting lateral bending [2]. Moazen and colleagues summarize the results of biomechanical testing of fixation methods of fixation for periprosthetic fractures, noting that increased rigidity improves fracture stability whether measured by stiffness or fracture motion [3]. In general, one may increase rigidity by increasing the number of plates and/or struts, that screws are more rigid than cables, which
S50
A.H. Schmidt / Injury, Int. J. Care Injured 49S1 (2018) S49–S50
in turn are more rigid than wires [3]. Finally, Moazen et al. point out that it is difficult to draw general conclusions because the available literature suffers from lack of standardization in testing procedures and measurements [3]. Areas needing more research include the role of strut grafts and what parameters are most important (such as length vs, fit), the ideal location for strut grafts, and the relative benefits of locking compared to non-locking plates [3]. New plate designs exist that are designed specifically for use in periprosthetic fractures and which facilitate off-axis screw placement. Tangential, or off-axis screws, not only allow one to “miss” an implant in the center of the medullary canal, but engage a greater thickness of cortical bone than a unicortical screw aimed at the medullary canal, and therefore may be more rigid. The biomechanical performance of two such constructs was studied by Lewis et al, who compared five methods of fixation in a series of 30 synthetic composite femurs with cemented femoral stems [4]. Specimens were loaded to failure in either axial compression or torsion. The cable construct was the weakest in both loading modes, followed by the locked unicortical screws. The addition of cables to the locked unicortical screw construct was not significantly stronger [4]. The two constructs with tangential, off-axis screws were strongest [4]. Ruchholtz et al. reported a clinical series of 41 patients treated using one such construct [5]. The patients included had 17 fractures about a THA, 10 around a TKA, 3 were interprosthetic, and 11 were about an intramedullary nail [5]. Overall, 88% of the plates were longer than 24 cm, and an average of 5.3 screws were inserted around the implant [5]. There were two nonunions resulting in plate breakage 6 months after surgery. The authors concluded that these plates facilitate less-invasive surgery, and when long plates are used, complications are few. Distal femur fractures above a TKA and interprosthetic fractures The clinical outcome of locking plates in distal femoral fractures as reported in the literature appears to be mixed. Some series report high complications rates [6]. Ebraheim et al. reported a 37% complication rate in 27 patients with fractures about a TKA.6 In contrast, Streubel et al. reported a 15% complication rate overall, but the “extreme” distal fractures treated with a lateral locked plate only had a 9% failure rate [7]. However, there are data suggesting that locking pre-contoured lateral femoral plates are too stiff, and that their use is associated with decreased callus formation and increased rate of nonunion. Henderson et al. retrospectively reviewed 86 distal femur fractures and examined various patient and treatment variables that affected healing [8]. Overall, 40% of the patients experienced complications, including 20% who’s fractures failed to unite. The constructs used in the healed fractures were more flexible, with more empty screws holes in the fractures that healed, and patients treated with titanium plates were more likely to heal than those with stainless steel plates [8]. In another paper from the same center, the volume of callus was compared in a matched series of 24 patients: 12 treated with locking plates and 12 were treated with retrograde nails [9]. Periosteal callus was measured using special image-processing software on anteroposterior and lateral radiographs at 12 weeks. The retrograde nail group had 2.4 times more callus area per location (231±304 mm2) than the locking plate group (95±109 mm2, P=0.028). These investigators concluded that significantly less periosteal callus forms in fractures stabilized with locking plates compared to retrograde intramedullary nails, and that construct stiffness is likely the important difference [9]. With the recognition of construct stiffness being important in callus formation and fracture healing, a number of methods are being proposed that increase the flexibility of fixation. These include using longer plates with fewer screws, titanium rather than stainless steel,
and methods such as far-cortical locking [10]. The clinical utility of these various methods is a focus of current research. Other problems and future research directions As in other areas of surgery, there may be benefits to stabilizing periprosthetic fractures using minimally-invasive techniques. In order to facilitate that, methods and tools that facilitate minimallyinvasive fracture reduction must be developed. Secondly, these patients are at risk for further fracture, and one must always consider how to prevent the next fracture. For this reason, extramedullary constructs that span and will protect the entire femur are needed for these patients. Finally, given how medically frail these patients are, methods to “boost” the biologic response to a fracture in these patients would be of obvious benefit. Other questions that remain include: • •
•
What is the current role for cerclage fixation? Is cerclage helpful for fracture reduction? For fixation? What is current role for allograft struts? Do such struts improve stability or fracture healing with current fixation devices? Do the biomechanical advantages of strut grafts demonstrated in the lab confer real clinical benefits, and do these benefits outweigh the costs (real and biologic)? What is the optimum fixation construct for different clinical situations?
Disclosure AHS discloses the following relationships. He reports serving as a consultant to Acumed, Conventus Orthopaedics and Alexion; stock ownership in Epix Orthopaedics, Conventus Orthopaedics and ActivOrtho; patent applications/registrations with Acumed and having received royalties from Smith & Nephew. Acknowledgment The authors of this manuscript express their thanks to the Osteosynthesis and Trauma Care Foundation for the sponsorship of the publication of this Supplement in Injury. References [1] Dennis MG, Simon JA, Kummer FJ, Koval KJ, DiCesare PE. Fixation of periprosthetic femoral shaft fractures occurring at the tip of the stem. a biomechanical study of 5 techniques. J Arthroplasty 2000;15(4):523–8. [2] Zdero R, Walker R, Waddell JP, Schemitsch EH. Biomechanical evaluation of periprosthetic femoral fracture fixation. J Bone Joint Surg Am 2008;90-A:1068–1077. [3] Moazen M, Jones AC, Jin J, Wilcox RK, Tsiridis E. Periprosthetic fracture fixation of the femur following total hip arthroplasty: A review of biomechanical testing. Clin Biomech 2011;26:13–22. [4] Lewis GS, Caroom CT, Wee H, et al. Tangential bicortical locked fixation improves stability in vancouver b1 periprosthetic femur fractures: A biomechanical study. J Orthop Trauma 2015;29:e364–e370. [5] Ruchholtz S, El-Zayat B, Kreslo D, et al. Less invasive polyaxial locking plate fixation in periprosthetic and peri-implant fractures of the femur: a prospective study of 41 patients. Injury 2013;44:239–248. [6] Ebraheim NA, Liu J, Hashmi SZ, et al. High complication rate in locking plate fixation of lower periprosthetic distal femur fractures in patients with total knee arthroplasties. J Arthroplasty 2012;27:809–813. [7] Streubel PN, Gardner MJ, Morshed S, Collinge CA, Gallagher B, Ricci WM. Are extreme distal periprosthetic supracondylar fractures of the femur too distal to fix using a lateral locked plate? J Bone Joint Surg Br 2010;92-B:527–534. [8] Henderson CE, Lujan TJ, Kuhl LL, Bottlang M, Fitzpatrick DC, Marsh JL. Healing complications are common after locked plating for distal femur fractures. Clin Orthop Rel Res 2011;469:1757–1765. [9] Henderson CE, Lujan T, Bottlang M, Fitzpatrick DC, Madey SM, Marsh JL. Stabilization of distal femur fractures with intramedullary nails and locking plates: differences in callus formation. Iowa Orthop J 2010:30:61–68. [10] Beltran MJ, Collinge CA, Gardner MJ. Stress modulation of fracture fixation implants. J Am Acad Orthop Surg 2016;24:711–719.