Bio-Medical Materials and Engineering 23 (2013) 485–493 DOI 10.3233/BME-130774 IOS Press
485
Enhancement of fracture healing by electrical stimulation in the comminuted intraarticular fracture of distal radius Kazuhiro Kohata a,b , Soichiro Itoh a,b,∗ , Shu Takeda c , Misa Kanai a , Taro Yoshioka a , Hiroyuki Suzuki a and Kimihiro Yamashita b a
Department of Orthopedic Surgery, Kawakita General Hospital, Tokyo, Japan Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan c Section of Nephrology, Endocrinology and Metabolism, Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan b
Received 25 March 2013 Accepted 25 April 2013 Abstract. Effectiveness of an alternating electric current (AC) stimulation in prevention of bone deformity for comminuted intraarticular fracture of distal radius were verified by comparing postoperative results treated with a wrist-bridging external fixator combined with or without an AC stimulator (EF and NEF, respectively), and a palmar locking plate (LP). This study evaluated 92 cases (mean age 67.9 ± 11.4 years) of type C2 and 60 cases (mean age 69.7 ± 9.5 years) of type C3 distal radius fractures, as classified by the Association for Osteosynthesis. In total, 55 and 24 cases were treated with EF and NEF, respectively; and 73 cases were treated with LP. Callus appeared 27.5 ± 4.6 days postoperatively and the external skeletal fixation period was significantly shorter in the EF group than in the NEF group. The decrease in radial length was significantly lower in the EF group when compared to the LP group. There were no significant differences among the groups for the other radiographic and functional parameters. AC stimulation combined to the external fixation may be a promising method to prevent postoperative deformity in the severely comminuted intraarticular fractures by accelerating callus maturation and facilitating new bone bridging across the gap of fracture site. Keywords: Alternating electric current (AC) stimulation, comminuted intraarticular fracture, distal radius fracture, wristbridging external fixator, palmar locking plate
1. Introduction Distal radius fractures are among the most frequent injuries that occur in the elderly population. In addition, because osteoporosis often precedes fracture in elderly people, the distal radius fracture can easily become comminuted. Since Orbay reported that most dorsally displaced distal radius fractures can be anatomically reduced and fixed using palmar locking plates [1], these types of plates have commonly used for managing unstable, dorsally displaced fractures of the distal radius. Palmar locked plating is * Address for correspondence: Soichiro Itoh and Kimihiro Yamashita, Department of Inorganic Materials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062, Japan. Tel.: +81 3 5280 8016; Fax: +81 3 5280 8125; E-mails: [email protected], [email protected].
0959-2989/13/$27.50 © 2013 – IOS Press and the authors. All rights reserved
486
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
Fig. 1. The AO type C fracture of distal radius. Depending on the relationship between the radius joint surface and the fracture, it is divided into 3 main groups: (A) Extraarticular fracture, (B) Partial articular fracture and (C) complete articular fracture. Each group is divided into 3 subgroups and classification of type (C) fracture is shown as a figure.
expected to facilitate an anatomical reduction and stabilization of the fracture and allow early mobilization. As a result, this method has been recently used even in the treatment of comminuted distal radius fractures. However, the selection of the best treatment option remains controversial in highly comminuted intraarticular fractures of the distal radius, type C2 and C3 fractures as classified by the Association for Osteosynthesis (AO) (Fig. 1) [2–4]. External skeletal fixation may be a gold standard to treat such an unstable distal radius fracture even now. Because it is hard to improve the range of wrist and finger motion for elderly patients with low motivation for social reintegration once joint contracture has developed, time periods of external fixation should be shorten to improve post-operative results. Electrical stimulation has been used as a technique to enhance fracture healing; the effectiveness of electrical stimulation in enhancing bone healing has been shown in fresh fractures [5], as well as in delayed union and nonunion of fractures [6], which improves the efficacy of bone grafts [7]. We also reported usefulness of an alternating electric current (AC) stimulation coupled with an external fixator to overcome its fault for distal radius fracture treatment [8]. Our goal for this study was to evaluate the effectiveness of AC stimulation in shortening of the external fixation period and prevention postoperative deformity in severely comminuted fracture. For this purpose, we analyzed and compared the radiological and functional outcomes of elderly people with severely comminuted intraarticular distal radius fractures (AO type C2 and C3 fractures) who were treated with either an external fixator with or without AC stimulation (designated as EF or NEF group, respectively), or with a palmar locking plate (designated as LP group). 2. Patients and methods From January 2005 to April 2012, 92 cases (83 female, 67.9 ± 11.4 years) of AO classification type C2 and 60 cases (47 female, 69.7± 9.5 years) of type C3 distal radius fractures were surgically treated in our related hospitals and enrolled in this study after providing informed written consent. The mechanism of injury was a falling. Patients with the open injuries or who had any other associated fractures of the hand, wrist or forearm or had a previous fracture of the same wrist were excluded. The surgeon selected a sole clever treatment method of fixation, with either an external fixator or with a palmar locking plate.
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
487
No surgeon switched his fixation device during the whole treatment period. When an external fixator was chosen, patients treated between January 2005 and June 2007 received a wrist bridging external skeletal fixator without AC stimulation (Tri Planar, Kisco, Co. Ltd., Kobe, Japan); patients treated between July 2007 and April 2012 received a wrist-bridging external skeletal fixator (BE-1100, Medical Engineering System, Co. Ltd., Tokyo, Japan) that was coupled to an AC stimulator (BS-1000, Medical Engineering System, Co. Ltd.). Patients treated with a palmar locking plate received a polyaxial locking plate, Aptus 2.5 (Medical Engineering System, Co. Ltd.) or VariAx (Stryker, Co. Ltd., Tokyo, Japan). 2.1. External skeletal fixation For wrist bridging fixation, two longitudinal parallel half pins measuring 3 mm in diameter were inserted into the second metacarpal base and into the radius proximal to the fracture. A closed fracture reduction was performed, and the instrument was locked using carbon rod coupling pins. Small fragments were fixed when needed with one or two percutaneous pins measuring 1.2 mm in diameter to obtain and maintain reduction. 2.2. External skeletal fixation combined with AC stimulation For electrical stimulation, major fragments, including the articular surface were fixed with another percutaneous radial pin that was 1.6 mm in diameter. This percutaneous radial pin and the most distal pin of the two pins inserted into the proximal radius were used for electrical stimulation (Fig. 2). An AC stimulator was attached to the external fixator with a dedicated adapter. The stimuli were applied after the operation with a 2 ± 0.4 Hz sinusoidal wave, 30 ± 0.6 µA of constant current output, and 0–60 kΩ of
Fig. 2. The external skeletal fixator coupled to the AC stimulator. The pin inserted to fix major fragments including the articular surface and the most distal pin of two pins inserted into the proximal radius are used for electrical stimulation (indicated by arrows). The stimuli are applied with a 2 ± 0.4 Hz sinusoidal wave, 30 ± 0.6 µA of constant current output, and 0–60 kΩ of loading resistance.
488
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
loading resistance. The electrical stimulation was given continuously with the AC electrical stimulator, which had a built-in constant current circuit. X-rays were obtained every 1 or 2 weeks. The additional pins that were used to fix the fragments were removed 3–4 weeks postoperatively. The external fixator and an electrical stimulation pin were removed after 5–6 weeks in the EF group when new bone bridging across the fracture site was completed, and the external fixator after 7–8 weeks in the NEF group when radiolucency decreased and new bone was formed homogeneously amongst the fragments. 2.3. Palmar locking plate fixation A Henry incision in the distal forearm was performed. Four distal holes were filled to support the central region of the subchondral bone, and three holes were filled in the second row to support the dorsal subchondral bone to provide double tiered subchondral support [9]. Artificial bone implantation was applied accordingly using hydroxyapatite (HA; Apaceram, HOYA Corporation, Tokyo, Japan) or β-tricalcium phosphate (β-TCP; Osferion, Olympus Co. Ltd., Tokyo, Japan) cubic blocks (1×1×1 cm). When needed, two temporary Kirschner wires were inserted from the radial styloid to maintain the fracture reduction and small fragments were fixed with 1–3 percutaneous pins measuring 1.2 mm in diameter to maintain the congruity of the articular surface. X-rays were obtained every 1 or 2 weeks, and depending on the stability, these pins were removed within 4 weeks postoperatively. 2.4. Post treatment Rehabilitation continued under the observation of occupational therapists until the bone healing had completed on the X-rays and the active range of motion (ROM) plateaued. 2.5. Postoperative evaluation The radial length (RL), radial inclination (RI), and palmar tilt (PT) of the fracture site [10] were measured using X-rays. These radiographic parameters were compared immediately after the operation and at the final consultation day to analyze the loss of reduced position. The active ROM, including wrist extension (Ext) and flexion (Flex), forearm pronation (Pro) and supination (Sup), and the grip power of the injured hand compared with the healthy opposite hand (Grip power %) were measured in the groups on the final consultation day. The Tukey–Kramer test was used for the statistical analysis of the patient age, observation period, radiographic and functional parameters in the groups. Furthermore, the difference in the external skeletal fixation period was compared between the EF and NEF groups using the Mann–Whitney U-test. In addition, the incidence rates of pain and complications in the groups were statistically compared using Chi-squared tests. The differences were considered as statistically significant when p < 0.05. This study was conducted according to the Declaration of Helsinki and was approved by the ethics committees of the authors’ institutions. 3. Results The number of cases that used supplementary pin fixation or artificial bone implantation in combination with the treatment for type C2 and C3 distal radius fractures is summarized in Table 1. The base
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
489
Table 1 The number of cases that used supplementary pin fixation or artificial bone implantation in combination with the treatment for type C2 and C3 distal radius fractures EF EF + pinning EF + HA EF + β-TCP
C2 23 4 0 0
C3 14 11 0 3
C2 + C3 37 15 0 3
Total N
27
28
55
NEF NEF + pinning EF + HA NEF + β-TCP
12 1 0 0
7 2 0 2
19 3 0 2
Total N
13
11
24
LP LP + pinning LP + HA LP + β-TCP LP + pinning + β-TCP
45 2 2 3 0
12 3 1 4 1
57 5 3 7 1
Total N
52
21
73
Table 2 The base line statics of patients enrolled in this study, including the total number of fractures, patient gender and age, observation period, and external fixator fixing time periods, and the radiological and functional outcomes Total number Female (%) Age (years) Observation period (weeks) EF fixing period (days) RL (mm) RI (◦ ) PT (◦ ) Ext (◦ ) Flex (◦ ) Pro (◦ ) Sup (◦ ) Grip power %
EF 55 46 69.9 ± 10.8 40.1 ± 11.3 37.0 ± 4.8∗∗ −0.4 ± 1.2∗∗ −0.3 ± 3.4 −0.5 ± 2.8 55.5 ± 14.0 49.6 ± 18.0 76.3 ± 13.3 83.9 ± 9.4 59.7 ± 17.4
NEF 24 23 66.6 ± 12.5 38.1 ± 11.3 50.5 ± 5.8∗∗ −1.3 ± 1.4 −1.6 ± 4.0 −2.5 ± 3.5 59.3 ± 9.4 50.0 ± 15.2 70.0 ± 13.5 80.0 ± 13.3 58.8 ± 15.3
LP 73 58 70.0 ± 9.1 39.6 ± 8.1 – −1.5 ± 1.0∗∗ −0.1 ± 3.7 −1.0 ± 3.6 59.0 ± 12.8 50.0 ± 13.9 82.2 ± 8.6 85.5 ± 8.0 69.2 ± 18.9
Notes: The data are shown as means ± SD. ∗∗ p < 0.01.
line statics of patients enrolled in this study, including the total number of fractures, patient gender and age, observation period, and external fixator fixing time periods, are summarized in Table 2. Furthermore, the radiological and functional outcomes are summarized in Table 2, as well. Callus formation bridging the fragments, termed an electrical callus, was observed in the radiographs from the EF group 27.5 ± 4.6 days postoperation (Fig. 3). This electrical callus on the dorsal-radial site of the fracture elongated from both side of gap and matured with time. Such prominent callus formation, however, was
490
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
Fig. 3. An X-ray of an 84 years old woman treated with a wrist bridging fixator coupled to an AC stimulator for an AO classification type C3 fracture: anterior-posterior (left image) and lateral (right image) views. (A) At the time of the injury. (B) Immediately after application of an external fixator. (C) Three weeks after the operation. The callus formation, termed electrical callus, is observed on the dorsal radial site of the distal radius (indicated by arrows), but not on the ulnar styloid base. (D) Ten weeks after the operation. After removal of the external fixator 6 weeks postoperatively, the electrical callus maturation has proceeded to form new bone bridging over the fracture site (indicated by arrows) and bone has united completely.
not observed in the NEF group. Therefore, the external skeletal fixation time period was significantly shorter in the EF group than in the NEF group. The bone bridging progressed after removing the external fixator to prevent radial shortening. In contrast, callus was scarcely formed in the LP group and radial shortening occurred in varying degrees. In 5 cases within the LP group it was suspected that radial shortening down to the level of prereduction occurred, causing protrusion of the distal screws into the wrist joint. As a result, the decrease in RL was significantly lower in the EF group compared with the LP groups. There were no significant differences between the groups for the other radiographic and functional parameters. The number of cases in which wrist or hand pain or other complications persisted in the groups is summarized in Table 3. There were no significant differences in the rates of incidence of pain or complications between the groups.
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
491
Table 3 The number of cases in which wrist or hand pain or other complications persisted in the groups Pain Wrist radial pain Wrist ulnar pain
N 4 3
Complication Finger stiffness Superficial infection Hypersensitivity in the radian nerve region Hypoesthesia in the median nerve region CRPS
N 5 2 2 1 1
NEF
Wrist radial pain Wrist ulnar pain Allodynia
1 1 1
Hypersensitivity in the radian nerve region Hypoesthesia in the median nerve region Finger stiffness CRPS
1 1 2 1
LP
Wrist radial pain Wrist ulnar pain Finger pain Allodynia Forearm pain
5 5 2 2 1
FPL tendon rupture Hypersensitivity in the median nerve region Finger stiffness Superficial infection
2 7 3 1
EF
4. Discussion Closed reduction and fixation with an external fixator is an established surgical procedure for comminute distal radius fractures. Major faults of this method are wrist and finger joint contracture after prolonged time period of external fixation and psychological adverse effects especially for elderly patients. Therefore, palmar locking plate fixation of dorsally angulated distal radius fractures has become a common treatment of choice in recent years. Nevertheless, the results for palmar locking plates compared with those for external fixators for treating unstable distal radius fractures are still controversial. Considering that, measurements in the C2 and C3 type distal radius fractures found that the decrease in RL was significantly lower in the EF group in this study, when compared with the LP groups, we can make the following conclusions. Postoperative radial shortening can be more effectively prevented with the use of an external fixation method, when combined with AC stimulation, than with the palmar locking plating methods. Although each screw is set to catch distal fragments in the double tiered subchondral support of the locking plates, the screws may not have sufficient mechanical strength to hold each major subchondral fragment firmly and prevent the progression of postoperative deformity when the distal radius is severely comminuted. While, early calluses bridging the fracture site were observed with AC stimulation. Additionally, although the external skeletal fixation period was significantly shorter in the EF group when compared with the NEF group, there were no significant differences between these groups in functional and radiographic parameters. These results suggest that after approximately 5–6 weeks postoperation such electric calluses can mature into newly formed bone that bridges fragments and has a mechanical strength that is sufficiently strong to prevent radius deformities after removal of the external fixator. These observations are supported by the report that indicates AC stimulation accelerates the callus maturation, although the callus volume does not increase, by promoting the differentiation of mesenchymal stem cells into osteogenic cells within the callus [11]. Another report showed that direct current (DC) stimulates osteogenesis by an electrochemical reaction at the cathode; O2 + 2H2 O + 4e− → 4OH. These hydroxyl ions at the cathode lower the oxygen concentration and increase pH, in which condition osteoblasts activities increase and osteoclasts activities decrease [12]. Furthermore, a second faradic
492
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
product, hydrogen peroxide (H2 O2 ) formed at the cathode enhances osteoclasts differentiation [13]. Bone resorption by osteoclasts triggers bone formation by osteoblasts through coupling mechanism. Hydrogen peroxide also stimulates vascular endothelial growth factor secretion by macrophages [14]. DC stimulation may increase bone morphogenetic protein (BMP)-2, 6, 7 [15] as well. Although such reports concern about positive effects of DC stimulation on bone healing, these mechanisms of DC stimulation on osteogenesis may work more effectively by AC stimulation in which direction of an electric current flow changes constantly. Early removal of the external fixator enables a faster rehabilitation of the wrist joint, and above all can relieve elderly patients of psychological adverse effects. Indeed, a report using two rating systems to evaluate treated patients’ satisfaction (the Patient Rated Wrist Evaluation (PRWE) and the Disability of the Arm, Shoulder, and Hand (DASH) scores) concluded that subjective assessment of postoperative results in palmar plating was better than that in external fixation [16]. Moreover, although it has been reported that losses in palmar angulation may continue in the long term with external fixation [17], the decrease in RL was significantly lower in the EF group when compared with the LP group approximately 40 weeks postoperatively in the present study. These findings indicate that the shortened time period of external fixation observed when combined with AC stimulation treatment is advantageous in easing patient apprehension safely.
5. Conclusion AC stimulation combined with external fixation may be a promising method to treat severely comminuted intraarticular fractures of distal radius by accelerating callus maturation and facilitating new bone bridging across the gap of the fracture site, enabling early external fixator removal, effective prevention of the postoperative deformity progression, and allaying patient anxiety.
Acknowledgements This study was conducted according to the Declaration of Helsinki and was approved by the ethics committees of the authors’ institutions. Declaration of conflicting interests: All named authors hereby declare that they have no conflicts of interest to disclose. Funding statement: This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Informed consent: Patients of distal radius fractures were surgically treated in our related hospitals and enrolled in this study after providing informed written consent.
References [1] J.L. Orbay and D.L. Fernandez, Volar fixation for dorsally displaced fractures of the distal radius: a preliminary report, J. Hand. Surg. (Am.) 27(2) (2002), 205. [2] J.L. Knirk and J.B. Jupiter, The AO/ASIF classification of long bone fractures, Injury 24(3) (1993), 163. [3] N. Schmelzer-Schmied, P. Wieloch, A.K. Martini and W. Daecke, Comparison of external fixation, locking and nonlocking palmar plating for unstable distal radius fractures in the elderly, Int. Orthop. 33(3) (2009), 773.
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
493
[4] J.L. Marsh, T.F. Slongo, J. Agel, J.S. Broderick, W. Creevey, T.A. DeCoster et al., Fracture and Dislocation classification compendium – 2007: Orthopaedic trauma association classification, database and outcomes committee, J. Orthop. Trauma 21(10 Suppl.) (2007), S1. [5] O. Wahlström, Stimulation of fracture healing with electromagnetic fields of extremely low frequency (EMF of ELF), Clin. Orthop. Relat. Res. 186 (1984), 293. [6] W.J. Sharrard, A double-blind trial of pulsed electromagnetic fields for delayed union of tibial fractures, J. Bone Joint. Surg. (Br.) 72 (1990), 347. [7] C.A. Bassett, S.N. Mitchell and M.M. Schink, Treatment of therapeutically resistant nonunions with bone grafts and pulsing electromagnetic fields, J. Bone Joint Surg. Am. 64(8) (1982), 1214. [8] S. Itoh, T. Ohta, Y. Sekino, Y. Yukawa and K. Shinomiya, Treatment of distal radius fractures with a wrist-bridging external fixation: The value of alternating electric current stimulation, J. Hand. Surg. (Eur.) 33(5) (2008), 605. [9] J.L. Orbay and A. Touhami, Current concepts in volar fixed-angle fixation of unstable distal radius fractures, Clin. Orthop. Relat. Res. 445 (2006), 58. [10] J.J. Gartland and C.W. Werley, Evaluation of healed Colles’ fractures, J. Bone Joint Surg. (Am.) 33(4) (1951), 895. [11] K. Kawamoto, W.C. Kim, Y. Tsuchida, Y. Tsuji, M. Fujioka, M. Horii, Y. Mikami, D. Tokunaga and T. Kubo, Effects of alternating current electrical stimulation on lengthening callus, J. Pediatr. Orthop. B 14(4) (2005), 299. [12] T. Bodamyali, J.M. Kanczler, B. Simon, D.R. Blake and C.R. Stevens, Effect of faradic products on direct currentstimulated calvarial organ culture calcium levels, Biochem. Biophys. Res. Commun. 264(3) (1999), 657. [13] M.J. Steinbeck, J.K. Kim, M.J. Trudeau, P.V. Hauschka and M.J. Karnovsky, Involvement of hydrogen peroxide in the differentiation of clonal HD-11EM cells into osteoclast-like cells, J. Cell. Physiol. 176(3) (1998), 574. [14] M. Cho, T.K. Hunt and M.Z. Hussain, Hydrogen peroxide stimulates macrophage vascular endothelial growth factor release, Am. J. Physiol. Heart Circ. Physiol. 280(5) (2001), 2357. [15] D.C. Fredericks, J. Smucker, E.B. Petersen, J.A. Bobst, J.C. Gan, B.J. Simon et al., Effects of direct current electrical stimulation on gene expression of osteopromotive factors in a posterolateral spinal fusion model, Spine 32(2) (2007), 174. [16] T.W. Wright, M. Horodyski and D.W. Smith, Functional outcome of unstable distal radius fractures: ORIF with a volar fixed-angle tine plate versus external fixation, J. Hand. Surg. (Am.) 30(2) (2005), 289. [17] P. Dicpinigaitis, P. Wolinsky, R. Hiebert, K. Egol, K. Koval and N. Tejwani, Can external fixation maintain reduction after distal radius fractures?, J. Trauma 57(4) (2004), 845.
Copyright of Bio-Medical Materials & Engineering is the property of IOS Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
485
Enhancement of fracture healing by electrical stimulation in the comminuted intraarticular fracture of distal radius Kazuhiro Kohata a,b , Soichiro Itoh a,b,∗ , Shu Takeda c , Misa Kanai a , Taro Yoshioka a , Hiroyuki Suzuki a and Kimihiro Yamashita b a
Department of Orthopedic Surgery, Kawakita General Hospital, Tokyo, Japan Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan c Section of Nephrology, Endocrinology and Metabolism, Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan b
Received 25 March 2013 Accepted 25 April 2013 Abstract. Effectiveness of an alternating electric current (AC) stimulation in prevention of bone deformity for comminuted intraarticular fracture of distal radius were verified by comparing postoperative results treated with a wrist-bridging external fixator combined with or without an AC stimulator (EF and NEF, respectively), and a palmar locking plate (LP). This study evaluated 92 cases (mean age 67.9 ± 11.4 years) of type C2 and 60 cases (mean age 69.7 ± 9.5 years) of type C3 distal radius fractures, as classified by the Association for Osteosynthesis. In total, 55 and 24 cases were treated with EF and NEF, respectively; and 73 cases were treated with LP. Callus appeared 27.5 ± 4.6 days postoperatively and the external skeletal fixation period was significantly shorter in the EF group than in the NEF group. The decrease in radial length was significantly lower in the EF group when compared to the LP group. There were no significant differences among the groups for the other radiographic and functional parameters. AC stimulation combined to the external fixation may be a promising method to prevent postoperative deformity in the severely comminuted intraarticular fractures by accelerating callus maturation and facilitating new bone bridging across the gap of fracture site. Keywords: Alternating electric current (AC) stimulation, comminuted intraarticular fracture, distal radius fracture, wristbridging external fixator, palmar locking plate
1. Introduction Distal radius fractures are among the most frequent injuries that occur in the elderly population. In addition, because osteoporosis often precedes fracture in elderly people, the distal radius fracture can easily become comminuted. Since Orbay reported that most dorsally displaced distal radius fractures can be anatomically reduced and fixed using palmar locking plates [1], these types of plates have commonly used for managing unstable, dorsally displaced fractures of the distal radius. Palmar locked plating is * Address for correspondence: Soichiro Itoh and Kimihiro Yamashita, Department of Inorganic Materials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062, Japan. Tel.: +81 3 5280 8016; Fax: +81 3 5280 8125; E-mails: [email protected], [email protected].
0959-2989/13/$27.50 © 2013 – IOS Press and the authors. All rights reserved
486
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
Fig. 1. The AO type C fracture of distal radius. Depending on the relationship between the radius joint surface and the fracture, it is divided into 3 main groups: (A) Extraarticular fracture, (B) Partial articular fracture and (C) complete articular fracture. Each group is divided into 3 subgroups and classification of type (C) fracture is shown as a figure.
expected to facilitate an anatomical reduction and stabilization of the fracture and allow early mobilization. As a result, this method has been recently used even in the treatment of comminuted distal radius fractures. However, the selection of the best treatment option remains controversial in highly comminuted intraarticular fractures of the distal radius, type C2 and C3 fractures as classified by the Association for Osteosynthesis (AO) (Fig. 1) [2–4]. External skeletal fixation may be a gold standard to treat such an unstable distal radius fracture even now. Because it is hard to improve the range of wrist and finger motion for elderly patients with low motivation for social reintegration once joint contracture has developed, time periods of external fixation should be shorten to improve post-operative results. Electrical stimulation has been used as a technique to enhance fracture healing; the effectiveness of electrical stimulation in enhancing bone healing has been shown in fresh fractures [5], as well as in delayed union and nonunion of fractures [6], which improves the efficacy of bone grafts [7]. We also reported usefulness of an alternating electric current (AC) stimulation coupled with an external fixator to overcome its fault for distal radius fracture treatment [8]. Our goal for this study was to evaluate the effectiveness of AC stimulation in shortening of the external fixation period and prevention postoperative deformity in severely comminuted fracture. For this purpose, we analyzed and compared the radiological and functional outcomes of elderly people with severely comminuted intraarticular distal radius fractures (AO type C2 and C3 fractures) who were treated with either an external fixator with or without AC stimulation (designated as EF or NEF group, respectively), or with a palmar locking plate (designated as LP group). 2. Patients and methods From January 2005 to April 2012, 92 cases (83 female, 67.9 ± 11.4 years) of AO classification type C2 and 60 cases (47 female, 69.7± 9.5 years) of type C3 distal radius fractures were surgically treated in our related hospitals and enrolled in this study after providing informed written consent. The mechanism of injury was a falling. Patients with the open injuries or who had any other associated fractures of the hand, wrist or forearm or had a previous fracture of the same wrist were excluded. The surgeon selected a sole clever treatment method of fixation, with either an external fixator or with a palmar locking plate.
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
487
No surgeon switched his fixation device during the whole treatment period. When an external fixator was chosen, patients treated between January 2005 and June 2007 received a wrist bridging external skeletal fixator without AC stimulation (Tri Planar, Kisco, Co. Ltd., Kobe, Japan); patients treated between July 2007 and April 2012 received a wrist-bridging external skeletal fixator (BE-1100, Medical Engineering System, Co. Ltd., Tokyo, Japan) that was coupled to an AC stimulator (BS-1000, Medical Engineering System, Co. Ltd.). Patients treated with a palmar locking plate received a polyaxial locking plate, Aptus 2.5 (Medical Engineering System, Co. Ltd.) or VariAx (Stryker, Co. Ltd., Tokyo, Japan). 2.1. External skeletal fixation For wrist bridging fixation, two longitudinal parallel half pins measuring 3 mm in diameter were inserted into the second metacarpal base and into the radius proximal to the fracture. A closed fracture reduction was performed, and the instrument was locked using carbon rod coupling pins. Small fragments were fixed when needed with one or two percutaneous pins measuring 1.2 mm in diameter to obtain and maintain reduction. 2.2. External skeletal fixation combined with AC stimulation For electrical stimulation, major fragments, including the articular surface were fixed with another percutaneous radial pin that was 1.6 mm in diameter. This percutaneous radial pin and the most distal pin of the two pins inserted into the proximal radius were used for electrical stimulation (Fig. 2). An AC stimulator was attached to the external fixator with a dedicated adapter. The stimuli were applied after the operation with a 2 ± 0.4 Hz sinusoidal wave, 30 ± 0.6 µA of constant current output, and 0–60 kΩ of
Fig. 2. The external skeletal fixator coupled to the AC stimulator. The pin inserted to fix major fragments including the articular surface and the most distal pin of two pins inserted into the proximal radius are used for electrical stimulation (indicated by arrows). The stimuli are applied with a 2 ± 0.4 Hz sinusoidal wave, 30 ± 0.6 µA of constant current output, and 0–60 kΩ of loading resistance.
488
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
loading resistance. The electrical stimulation was given continuously with the AC electrical stimulator, which had a built-in constant current circuit. X-rays were obtained every 1 or 2 weeks. The additional pins that were used to fix the fragments were removed 3–4 weeks postoperatively. The external fixator and an electrical stimulation pin were removed after 5–6 weeks in the EF group when new bone bridging across the fracture site was completed, and the external fixator after 7–8 weeks in the NEF group when radiolucency decreased and new bone was formed homogeneously amongst the fragments. 2.3. Palmar locking plate fixation A Henry incision in the distal forearm was performed. Four distal holes were filled to support the central region of the subchondral bone, and three holes were filled in the second row to support the dorsal subchondral bone to provide double tiered subchondral support [9]. Artificial bone implantation was applied accordingly using hydroxyapatite (HA; Apaceram, HOYA Corporation, Tokyo, Japan) or β-tricalcium phosphate (β-TCP; Osferion, Olympus Co. Ltd., Tokyo, Japan) cubic blocks (1×1×1 cm). When needed, two temporary Kirschner wires were inserted from the radial styloid to maintain the fracture reduction and small fragments were fixed with 1–3 percutaneous pins measuring 1.2 mm in diameter to maintain the congruity of the articular surface. X-rays were obtained every 1 or 2 weeks, and depending on the stability, these pins were removed within 4 weeks postoperatively. 2.4. Post treatment Rehabilitation continued under the observation of occupational therapists until the bone healing had completed on the X-rays and the active range of motion (ROM) plateaued. 2.5. Postoperative evaluation The radial length (RL), radial inclination (RI), and palmar tilt (PT) of the fracture site [10] were measured using X-rays. These radiographic parameters were compared immediately after the operation and at the final consultation day to analyze the loss of reduced position. The active ROM, including wrist extension (Ext) and flexion (Flex), forearm pronation (Pro) and supination (Sup), and the grip power of the injured hand compared with the healthy opposite hand (Grip power %) were measured in the groups on the final consultation day. The Tukey–Kramer test was used for the statistical analysis of the patient age, observation period, radiographic and functional parameters in the groups. Furthermore, the difference in the external skeletal fixation period was compared between the EF and NEF groups using the Mann–Whitney U-test. In addition, the incidence rates of pain and complications in the groups were statistically compared using Chi-squared tests. The differences were considered as statistically significant when p < 0.05. This study was conducted according to the Declaration of Helsinki and was approved by the ethics committees of the authors’ institutions. 3. Results The number of cases that used supplementary pin fixation or artificial bone implantation in combination with the treatment for type C2 and C3 distal radius fractures is summarized in Table 1. The base
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
489
Table 1 The number of cases that used supplementary pin fixation or artificial bone implantation in combination with the treatment for type C2 and C3 distal radius fractures EF EF + pinning EF + HA EF + β-TCP
C2 23 4 0 0
C3 14 11 0 3
C2 + C3 37 15 0 3
Total N
27
28
55
NEF NEF + pinning EF + HA NEF + β-TCP
12 1 0 0
7 2 0 2
19 3 0 2
Total N
13
11
24
LP LP + pinning LP + HA LP + β-TCP LP + pinning + β-TCP
45 2 2 3 0
12 3 1 4 1
57 5 3 7 1
Total N
52
21
73
Table 2 The base line statics of patients enrolled in this study, including the total number of fractures, patient gender and age, observation period, and external fixator fixing time periods, and the radiological and functional outcomes Total number Female (%) Age (years) Observation period (weeks) EF fixing period (days) RL (mm) RI (◦ ) PT (◦ ) Ext (◦ ) Flex (◦ ) Pro (◦ ) Sup (◦ ) Grip power %
EF 55 46 69.9 ± 10.8 40.1 ± 11.3 37.0 ± 4.8∗∗ −0.4 ± 1.2∗∗ −0.3 ± 3.4 −0.5 ± 2.8 55.5 ± 14.0 49.6 ± 18.0 76.3 ± 13.3 83.9 ± 9.4 59.7 ± 17.4
NEF 24 23 66.6 ± 12.5 38.1 ± 11.3 50.5 ± 5.8∗∗ −1.3 ± 1.4 −1.6 ± 4.0 −2.5 ± 3.5 59.3 ± 9.4 50.0 ± 15.2 70.0 ± 13.5 80.0 ± 13.3 58.8 ± 15.3
LP 73 58 70.0 ± 9.1 39.6 ± 8.1 – −1.5 ± 1.0∗∗ −0.1 ± 3.7 −1.0 ± 3.6 59.0 ± 12.8 50.0 ± 13.9 82.2 ± 8.6 85.5 ± 8.0 69.2 ± 18.9
Notes: The data are shown as means ± SD. ∗∗ p < 0.01.
line statics of patients enrolled in this study, including the total number of fractures, patient gender and age, observation period, and external fixator fixing time periods, are summarized in Table 2. Furthermore, the radiological and functional outcomes are summarized in Table 2, as well. Callus formation bridging the fragments, termed an electrical callus, was observed in the radiographs from the EF group 27.5 ± 4.6 days postoperation (Fig. 3). This electrical callus on the dorsal-radial site of the fracture elongated from both side of gap and matured with time. Such prominent callus formation, however, was
490
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
Fig. 3. An X-ray of an 84 years old woman treated with a wrist bridging fixator coupled to an AC stimulator for an AO classification type C3 fracture: anterior-posterior (left image) and lateral (right image) views. (A) At the time of the injury. (B) Immediately after application of an external fixator. (C) Three weeks after the operation. The callus formation, termed electrical callus, is observed on the dorsal radial site of the distal radius (indicated by arrows), but not on the ulnar styloid base. (D) Ten weeks after the operation. After removal of the external fixator 6 weeks postoperatively, the electrical callus maturation has proceeded to form new bone bridging over the fracture site (indicated by arrows) and bone has united completely.
not observed in the NEF group. Therefore, the external skeletal fixation time period was significantly shorter in the EF group than in the NEF group. The bone bridging progressed after removing the external fixator to prevent radial shortening. In contrast, callus was scarcely formed in the LP group and radial shortening occurred in varying degrees. In 5 cases within the LP group it was suspected that radial shortening down to the level of prereduction occurred, causing protrusion of the distal screws into the wrist joint. As a result, the decrease in RL was significantly lower in the EF group compared with the LP groups. There were no significant differences between the groups for the other radiographic and functional parameters. The number of cases in which wrist or hand pain or other complications persisted in the groups is summarized in Table 3. There were no significant differences in the rates of incidence of pain or complications between the groups.
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
491
Table 3 The number of cases in which wrist or hand pain or other complications persisted in the groups Pain Wrist radial pain Wrist ulnar pain
N 4 3
Complication Finger stiffness Superficial infection Hypersensitivity in the radian nerve region Hypoesthesia in the median nerve region CRPS
N 5 2 2 1 1
NEF
Wrist radial pain Wrist ulnar pain Allodynia
1 1 1
Hypersensitivity in the radian nerve region Hypoesthesia in the median nerve region Finger stiffness CRPS
1 1 2 1
LP
Wrist radial pain Wrist ulnar pain Finger pain Allodynia Forearm pain
5 5 2 2 1
FPL tendon rupture Hypersensitivity in the median nerve region Finger stiffness Superficial infection
2 7 3 1
EF
4. Discussion Closed reduction and fixation with an external fixator is an established surgical procedure for comminute distal radius fractures. Major faults of this method are wrist and finger joint contracture after prolonged time period of external fixation and psychological adverse effects especially for elderly patients. Therefore, palmar locking plate fixation of dorsally angulated distal radius fractures has become a common treatment of choice in recent years. Nevertheless, the results for palmar locking plates compared with those for external fixators for treating unstable distal radius fractures are still controversial. Considering that, measurements in the C2 and C3 type distal radius fractures found that the decrease in RL was significantly lower in the EF group in this study, when compared with the LP groups, we can make the following conclusions. Postoperative radial shortening can be more effectively prevented with the use of an external fixation method, when combined with AC stimulation, than with the palmar locking plating methods. Although each screw is set to catch distal fragments in the double tiered subchondral support of the locking plates, the screws may not have sufficient mechanical strength to hold each major subchondral fragment firmly and prevent the progression of postoperative deformity when the distal radius is severely comminuted. While, early calluses bridging the fracture site were observed with AC stimulation. Additionally, although the external skeletal fixation period was significantly shorter in the EF group when compared with the NEF group, there were no significant differences between these groups in functional and radiographic parameters. These results suggest that after approximately 5–6 weeks postoperation such electric calluses can mature into newly formed bone that bridges fragments and has a mechanical strength that is sufficiently strong to prevent radius deformities after removal of the external fixator. These observations are supported by the report that indicates AC stimulation accelerates the callus maturation, although the callus volume does not increase, by promoting the differentiation of mesenchymal stem cells into osteogenic cells within the callus [11]. Another report showed that direct current (DC) stimulates osteogenesis by an electrochemical reaction at the cathode; O2 + 2H2 O + 4e− → 4OH. These hydroxyl ions at the cathode lower the oxygen concentration and increase pH, in which condition osteoblasts activities increase and osteoclasts activities decrease [12]. Furthermore, a second faradic
492
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
product, hydrogen peroxide (H2 O2 ) formed at the cathode enhances osteoclasts differentiation [13]. Bone resorption by osteoclasts triggers bone formation by osteoblasts through coupling mechanism. Hydrogen peroxide also stimulates vascular endothelial growth factor secretion by macrophages [14]. DC stimulation may increase bone morphogenetic protein (BMP)-2, 6, 7 [15] as well. Although such reports concern about positive effects of DC stimulation on bone healing, these mechanisms of DC stimulation on osteogenesis may work more effectively by AC stimulation in which direction of an electric current flow changes constantly. Early removal of the external fixator enables a faster rehabilitation of the wrist joint, and above all can relieve elderly patients of psychological adverse effects. Indeed, a report using two rating systems to evaluate treated patients’ satisfaction (the Patient Rated Wrist Evaluation (PRWE) and the Disability of the Arm, Shoulder, and Hand (DASH) scores) concluded that subjective assessment of postoperative results in palmar plating was better than that in external fixation [16]. Moreover, although it has been reported that losses in palmar angulation may continue in the long term with external fixation [17], the decrease in RL was significantly lower in the EF group when compared with the LP group approximately 40 weeks postoperatively in the present study. These findings indicate that the shortened time period of external fixation observed when combined with AC stimulation treatment is advantageous in easing patient apprehension safely.
5. Conclusion AC stimulation combined with external fixation may be a promising method to treat severely comminuted intraarticular fractures of distal radius by accelerating callus maturation and facilitating new bone bridging across the gap of the fracture site, enabling early external fixator removal, effective prevention of the postoperative deformity progression, and allaying patient anxiety.
Acknowledgements This study was conducted according to the Declaration of Helsinki and was approved by the ethics committees of the authors’ institutions. Declaration of conflicting interests: All named authors hereby declare that they have no conflicts of interest to disclose. Funding statement: This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Informed consent: Patients of distal radius fractures were surgically treated in our related hospitals and enrolled in this study after providing informed written consent.
References [1] J.L. Orbay and D.L. Fernandez, Volar fixation for dorsally displaced fractures of the distal radius: a preliminary report, J. Hand. Surg. (Am.) 27(2) (2002), 205. [2] J.L. Knirk and J.B. Jupiter, The AO/ASIF classification of long bone fractures, Injury 24(3) (1993), 163. [3] N. Schmelzer-Schmied, P. Wieloch, A.K. Martini and W. Daecke, Comparison of external fixation, locking and nonlocking palmar plating for unstable distal radius fractures in the elderly, Int. Orthop. 33(3) (2009), 773.
K. Kohata et al. / Enhancement of fracture healing by electrical stimulation
493
[4] J.L. Marsh, T.F. Slongo, J. Agel, J.S. Broderick, W. Creevey, T.A. DeCoster et al., Fracture and Dislocation classification compendium – 2007: Orthopaedic trauma association classification, database and outcomes committee, J. Orthop. Trauma 21(10 Suppl.) (2007), S1. [5] O. Wahlström, Stimulation of fracture healing with electromagnetic fields of extremely low frequency (EMF of ELF), Clin. Orthop. Relat. Res. 186 (1984), 293. [6] W.J. Sharrard, A double-blind trial of pulsed electromagnetic fields for delayed union of tibial fractures, J. Bone Joint. Surg. (Br.) 72 (1990), 347. [7] C.A. Bassett, S.N. Mitchell and M.M. Schink, Treatment of therapeutically resistant nonunions with bone grafts and pulsing electromagnetic fields, J. Bone Joint Surg. Am. 64(8) (1982), 1214. [8] S. Itoh, T. Ohta, Y. Sekino, Y. Yukawa and K. Shinomiya, Treatment of distal radius fractures with a wrist-bridging external fixation: The value of alternating electric current stimulation, J. Hand. Surg. (Eur.) 33(5) (2008), 605. [9] J.L. Orbay and A. Touhami, Current concepts in volar fixed-angle fixation of unstable distal radius fractures, Clin. Orthop. Relat. Res. 445 (2006), 58. [10] J.J. Gartland and C.W. Werley, Evaluation of healed Colles’ fractures, J. Bone Joint Surg. (Am.) 33(4) (1951), 895. [11] K. Kawamoto, W.C. Kim, Y. Tsuchida, Y. Tsuji, M. Fujioka, M. Horii, Y. Mikami, D. Tokunaga and T. Kubo, Effects of alternating current electrical stimulation on lengthening callus, J. Pediatr. Orthop. B 14(4) (2005), 299. [12] T. Bodamyali, J.M. Kanczler, B. Simon, D.R. Blake and C.R. Stevens, Effect of faradic products on direct currentstimulated calvarial organ culture calcium levels, Biochem. Biophys. Res. Commun. 264(3) (1999), 657. [13] M.J. Steinbeck, J.K. Kim, M.J. Trudeau, P.V. Hauschka and M.J. Karnovsky, Involvement of hydrogen peroxide in the differentiation of clonal HD-11EM cells into osteoclast-like cells, J. Cell. Physiol. 176(3) (1998), 574. [14] M. Cho, T.K. Hunt and M.Z. Hussain, Hydrogen peroxide stimulates macrophage vascular endothelial growth factor release, Am. J. Physiol. Heart Circ. Physiol. 280(5) (2001), 2357. [15] D.C. Fredericks, J. Smucker, E.B. Petersen, J.A. Bobst, J.C. Gan, B.J. Simon et al., Effects of direct current electrical stimulation on gene expression of osteopromotive factors in a posterolateral spinal fusion model, Spine 32(2) (2007), 174. [16] T.W. Wright, M. Horodyski and D.W. Smith, Functional outcome of unstable distal radius fractures: ORIF with a volar fixed-angle tine plate versus external fixation, J. Hand. Surg. (Am.) 30(2) (2005), 289. [17] P. Dicpinigaitis, P. Wolinsky, R. Hiebert, K. Egol, K. Koval and N. Tejwani, Can external fixation maintain reduction after distal radius fractures?, J. Trauma 57(4) (2004), 845.
Copyright of Bio-Medical Materials & Engineering is the property of IOS Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
