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Management of displaced comminuted patellar fracture with titanium cable cerclage
The Knee 17 (2010) 283–286
Contents lists available at ScienceDirect
The Knee
Management of displaced comminuted patellar fracture with titanium cable cerclage Li Yang, Ouyang Yueping, Yuan Wen ⁎ Department of Orthopaedic Surgery, Changzheng Hospital Affiliated to Second Military Medical University, 450 Feng Yang Road, Shanghai 200003, PR China
a r t i c l e
i n f o
Article history: Received 6 September 2009 Received in revised form 25 January 2010 Accepted 10 February 2010 Keywords: Patellar fracture Displaced fracture Comminuted fracture Titanium cable Cerclage
a b s t r a c t Management of a displaced comminuted patellar fracture is challenging. Tension band wiring and lag screw fixation are not suitable for such a fracture pattern. Stainless steel wiring with various configurations has been the mainstay of treatment. However, issues of loss of fixation and breakage of wire have not been resolved yet. Partial or total patellectomy is the last resort with a detrimental effect on quadriceps power. Braided titanium cable is stronger in tensile strength and better in fatigue resistance than the stainless steel monofilament wire, and the tension of fixation could be controlled by a graded instrument in its application. We used titanium cable to treat 21 consecutive patients with displaced comminuted patellar fracture. Patients were followed up for a mean period of 24 months (12 to 32 months). The mean score at the final follow-up was 27 points (25 to 30) using the Böstman method. There was no complication except breakage of one cable at the sixth week after the operation and the fracture had united despite the breakage. This technique is simple and effective for these difficult fractures and avoided prolonged immobilisation of the knee. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Comminuted fractures of the patella which disrupt the extensor mechanism of the knee require operative treatment. The aim of the treatment is to preserve the bone of the patella, restore the joint surface and provide stable fixation for early mobilisation. Since partial or total patellectomy results in the loss of quadriceps muscle power, it should be avoided if possible [1]. Excision of the small fragments of the bone with the attachment of the patellar tendon by a transosseous pull-out suture is usually indicated [2–5]. Weakness of synthetic nonabsorbable sutures and partial patellectomy requires immobilisation of the knee after operation, which delays rehabilitation and may result in the weakness of the quadriceps muscle [2–4]. Some authors advocate patellotibial cerclage or the use of the figure-of-eight wiring to protect the pull-out suture in order to allow early rehabilitation, but these procedures make it difficult to adjust the length of the patellar tendon [2–5]. This may result in breakage of the wire requiring a second operation for its removal [3–5]. Fixation by using lag screw or conventional figure-of-eight tension band is advocated in patients with transverse fractures for the best results [6]. But such construct is not suitable for displaced comminuted fractures. Stainless steel wire has been associated with breakage and loss of fixation [7]. Braided cables have replaced the wire in upper cervical fusion, arthroplasty and periprosthetic fractures for their superior
⁎ Corresponding author. Tel.: + 86 21 81885632; fax: + 86 21 63720099. E-mail address: [email protected] (Y. Wen). 0968-0160/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.knee.2010.02.005
strength and fatigue resistance [8], furthermore, tension could be controlled through tensioning device. Therefore, we trialed the titanium cable cerclage in treatment of the displaced comminuted patellar fractures. Fractures with multiple fragments are defined as comminuted fractures [9]. Displaced fractures are those with an articular incongruity (step-off) of more than 2 mm or separation of the fragments of more than 3 mm [10]. During the study, patients with displaced patellar transverse fractures were treated with AO modified tension bands. Simple fractures involving a part of the articular surface and the inferior pole of the patella, which are disrupting the patellar ligament were treated with lag screw or ectomy. Fractures that didn't disturb the quadriceps mechanism were treated conservatively. Another aim of the titanium cable cerclage is to develop the advantage of stainless steel wire cerclage (fit for most of the comminuted patellar fractures and operate simply), and to overcome its disadvantage (loosening and breakage [11–13]). Cobalt–chrome cable fixation has been associated with fretting and metallic debris in total hip arthroplasty [14–17], and we wonder if this is a concern with titanium cerclage for the fracture fixation in the knee. Finally, we asked whether this simple procedure can fix comminuted patellar fractures firmly to allow early functional exercise, and get satisfactory results. 2. Patients and methods The inclusion criteria of the patients with titanium cable cerclage were as follows; the general physical condition of the patients could withstand the anesthesia and operation, fractures involved the
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patellar articular surface and without any deep infection, fractures with multiple fragments and with an articular incongruity (step-off) of more than 2 mm or a separation of the fragments of more than 3 mm, and fractures disrupted the quadriceps mechanism. The exclusion criteria were; the general physical condition of the patients could not withstand the anesthesia and operation, fractures didn't involve any articular surface, fractures with deep infection, fragments were less than three, fractures with an articular incongruity (step-off) of less than 2 mm and the separated distance was less than 3 mm, and fractures with quadriceps mechanism were not disturbed. We retrospectively reviewed 21 consecutive patients (12 males and nine females) with displaced comminuted patellar fractures (Fig. 1A) who were treated surgically due to the inability to straight leg raise, three of whom with three fragments, 16 with four fragments and two with five ones. Eighteen were closed, and three were open fractures (Gustilo II). No patient was found with any associated injuries. Two patients had type 2 diabetes, two had hypertension, the others were not found with background disease. All the patients were treated with titanium cable cerclage in our department between May 2005 and September 2008. Their mean age was 40 years (range, 25 to 65 years). There was no loss to follow-up, and the minimum followup was 12 months (mean, 24 months; range, 12 to 32 months). Anteroposterior radiographs (Fig. 1B) and lateral radiographs (Fig. 1C) were obtained at 2 days, 6 weeks, 8 weeks, and 12 weeks after surgery, and subsequently half-yearly follow-ups. And the roentgenographic results were independently assessed by radiologists who were not involved in the study. Cable breakage, fraying, fragmentation, and the presence of metallic debris and loosening were recorded. Loosening was defined as the diameter of the cable loop expanded. The function of the knee was evaluated by using the method of Böstman, Kiviluoto and Nirhamo [18] by one of the authors at the latest follow-up (Table 1).
Table 1 Details of the clinical grading scale of Böstman et al. [18]. Variable
Point
Range of movement (ROM) Full extension and the ROM N 120°or within 10°of the normal side 6 Full extension, movement 90° to 120° 3 Pain None or minimal on exertion 6 Moderate on exertion 3 In daily activity 0 Work Original job 4 Different job 2 Cannot work 0 Atrophy, difference of circumference of thigh 10 cm proximal to the patella b12 mm 4 12 to 25 mm 2 N25 mm 0 Assistance in walking None 4 Cane part of the time 2 Cane all the time 0 Effusion None 2 Reported to be present 1 Present 0 Giving way None 2 Sometimes 1 In daily life 0 Stair-climbing Normal 2 Disturbing 1 Disabling 0 Total score Excellent 30 to 28 Good 27 to 20 Unsatisfactory b20
3. Surgical technique The fracture was exposed through midline longitudinal incision. For closed fractures, the retinaculum was left intact to help reduction. In open fractures, debridement was conducted before reduction. When the retinaculum was disrupted, our reduction maneuver involved passing temporary suture (1 vicryl) around the patella to cobble the fragments together. Then the articular surface was palpated and reduction adjusted
accordingly through arthrotomy. Final reduction was checked by image intensifier. One braided titanium cable (Atlas titanium cable) was cut in halves. The cables were passed circumferentially around the patella (Fig. 2A, B) forming two loops, one at one third and one at two thirds of the patellar in depth from the articular surface (Fig. 2C, D). Making
Fig. 1. (A–C) A lateral radiograph (A) shows displaced and comminuted fractures of the patellar. A lateral radiograph (B) and an anteroposterior radiograph (C) were taken at 6 weeks after the operation, which show displaced comminuted fragments were reduced and fixed by two loops of titanium cables and have got a bony union at 8 weeks after the operation.
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The affected limb was raised in postoperative days for 1 week. There was no immobility after the operation, functional exercises were started as early as the first day after the internal-fix operation. CPM (continuous passive movement) machines were used to facilitate the early postoperative range of motion exercises of the knee. Patients were allowed to mobilize as comfort allowed under the supervision of the physiotherapists, and partially or full weight bearing was acceptable from the third day after operation. 4. Results
Fig. 2. (A–D) Diagrams show that the displaced comminuted patellar fracture is reduced and then fixed circumferentially with two loops of titanium cables (A, B), one at one third and one at two thirds of the patellar in depth from the articular surface (C, D), and the cables are next to the bone tissue of the patellar (B, D).
The mean time between injury and surgery was 3 days (range, 2 to 7 days). The mean operation time was 54 min (range, 35 to 70 min). The mean time between the operation and the union was 46 days (range 40 to 68 days). No cerclage loosening or fragment displacement was noted. There was no nonunion, delayed union or infection. No evidence of post-traumatic osteoarthritis was found at the latest follow-up. The roentgenographic evaluation did not show any fraying of cables or metallic debris. A breakage of one loop of the cable was detected at the sixth week after the operation (Fig. 3A, B), the patient was asymptomatic. She was not allowed to full weight bear until bony union which was confirmed in another four weeks. Elective operation was conducted to remove the titanium cables in out-patient clinic operation rooms after the fractures had been bony united. A 0.5 centimeter incision was made at the site of the crimps after local anesthesia. After the crimps were exposed and the cables cut, the titanium cables could be removed easily. Nine patients (including the patient with cable breakage) were operated to remove the cables in out-patient clinic operation rooms after the bony union was achieved, and no fraying, fragmentation or metallic debris was noted at the time of cable removal. Satisfactory results were obtained in terms of the recovery of knee function. The mean score at the final follow-up was 28.6 points (range 26 to 30 points) by the method of Böstman et al. [18]. Seventeen patients (81%) had excellent, four (19%) had good result, no patients had an unsatisfactory result.
5. Discussion
sure the cables were next to the bone (Fig. 2B, D), the cables were tensioned to 30 lbs. The articular surface was checked again by palpation and image intensifier, and the knee was flexed to 90° to confirm that the fragments would not separate over 1 mm, before crimps were applied and the excess cables were cut. The soft tissue envelope was then repaired over the patellar with suture and the wound was closed in layers.
In our series, the functional results were excellent in 81%, and good in 19%, which were better than that were reported in literature [11,12]. A review of 49 patellar fractures shows that 22% of fractures displaced more than 2 mm at the fracture site with early mobilisation after tension band wiring [12]. Another report of 26 patellar fractures of which 18 cases received modified tension band internal fixation, five cases for tension band wiring and three cases for circumferential wire loop fixation, the functional results were poor in 50% [11].
Fig. 3. (A–B) A breakage of one loop of the cable was detected through an anteroposterior radiograph (A) and a lateral radiograph (B) in a 25-year-old female patient at the sixth week, and the bone union had been achieved without any malunion.
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Due to the variety of the patellar fracture patterns, there is no single surgical technique to deal with all of them. Anterior tension band fixation constructs are among the mainstay of the treatment of patella fractures and lead to reliable results with simple transverse fracture patterns. However, comminuted fractures of the patella require much more extensive articular reconstruction than interdigitating two large fragments to achieve a good result [19]. Circumferential wiring with stainless steel wires is not accepted for its weakness and loosening in fixation [7]. Functional exercise with CPM and active quadriceps exercises were started as early as the first operative day in our cases, no loss of the fixation or displacement of the fragments was found. Maybe this is one of the reasons that satisfactory results were noted at the end of the therapy. In contrast, according to the literature, early mobilisation is important but causes detrimental displacement at the fracture site [20]. The main reason for the loss of fixation in tension band wiring is the friction and plastic deformation caused by the wire sliding around the Kirschner wire [21].As a result, most of the comminuted patellar fractures treated with tension band have to be immobilized for weeks after operation [22,23], which would reduce the losses of fixation but at the cost of the final knee function. The characteristics of the titanium cable allow it to fix patellar fractures more firmly without any loosening than that stainless steel wires can. The tensile strength of a braided titanium cable is three to six times to a traditional stainless steel monofilament wire with the comparable diameter, and the fatigue resistance is nine to 48 times [8]. When the same force was exerted on the stainless steel wire and the titanium cable for 24 h, creep occurs in the stainless steel wire but not in the titanium cable [8]. Though the cobalt chrome cable is generally considered to be stronger than the titanium cable, considering the potential problems of fraying, fragmentation and the metallic debris from the cobalt chrome cable in arthroplasty which were reported in literature [14–17], we alternated to the titanium cable. Perhaps it is the character of the titanium made that we did not find any frying, fragmentation and metallic debris in our series, it is also maybe attributed to the limitation of the follow-up time in our series. And also we do not find any reports about fraying, fragmentation and the metallic debris of the cables in the fracture but in arthroplasty. In addition, the more sophisticated tensioning device allows an exact tension to be applied to the fracture in comparison with the simplistic wire twisting. Cables also seem to conform to the outline of the patella better after tensioning compared to the stainless steel wire, therefore providing more even compression to the fragments. The histocompatibility of the titanium is good enough to minimise the scar tissue caused by the internal implants, thus, removal of the implant is easy should the need arises due to prominence. Steel implants also create a significant artifact on MRI, reducing the postoperative usefulness of this imaging modality. Titanium has the advantage of producing minimal MRI artifact [24] thus the articular surface could be assessed by this modality. One breakage of the cable was detected in a 25-year-old female patient at the sixth week after surgery, it was probably associated with the patient falling down when climbing up the stairs and with the operated knee extended suddenly and powerfully with full weight bearing. Plain films showed that the other loop of the cable was unbroken and the fracture had been united, without any complaints the patient was not allowed full weight bearing in another 2 weeks. The cables were removed 6 months after the operation, and the patient was satisfied with the excellent result of the knee function, the grading at the final follow-up was 30 points. In conclusion, although our study is limited by the lack of a control group, and the titanium cable is more expensive than the stainless steel wire, the results of our review suggest that treatment of comminuted patellar fracture is better with titanium cable cerclage than that with the stainless wire. Firm fixation with controlled tension
allows early functional exercise and weight bearing, which contributes to an excellent and good result in short-term and long-term recovery. This new surgical technique may be particularly useful in comminuted fractures when patellar excision would otherwise be considered. 6. Conflict of interest statement Each author certifies that he has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article. Acknowledgements We would like to thank Professor Gou Sanhuai, who gave us general support. We thank Doctor Zhang Ying, Chen Fangjing, and Xu Shengming for helping us gather the data. We thank Tian Ye and Shen Xiaolong for the critical review of our paper, and we appreciate Dong Ren, Zhu Yuzhao, and Guo Wei for the participation in our clinical trail. We so appreciate Tsai Nick for his advice during the revision. References [1] Galla M, Lobenhoffer P. Patella fractures. Chirurg 2005;76:987–97. [2] Hung LK, Lee SY, Leung KS, Chan KM, Nicholl LA. Partial patellectomy for patellar fracture: tension band wiring and early mobilisation. J Orthop Trauma 1993;7: 252–60. [3] Nerlich M, Weigel B. Patella. In: Rüedi TP, Murphy WM, editors. AO principals of fracture management. Stuttgart and New York: Thieme; 2000. p. 483–97. [4] Saltzman CL, Goulet JA, McClellan RT, Schneider LA, Matthews LS. Results of treatment of displaced patella fractures by partial patellectomy. J Bone Joint Surg Am 1990;72-A:1279–85. [5] Whittle AP. Fractures of lower extremity. In: Canale ST, editor. Campbell's operative orthopaedics, Ninth ed., vol. 3. St Louis: Mosby; 1998. p. 2042–179. [6] Ozdemir H, Ozenci M, Dabak K, Aydin AT. Outcome of surgical treatment for patellar fracture. Turkish J Trauma Emergency Surg 2001;7:56–9. [7] Weber MJ, Janecki CJ, McLeod P, Nelson CL, Thompson JA. Efficacy of various forms of fixation of transverse fractures of the patella. J Bone Joint Surg Am 1980;62:215–20. [8] Dickman CA, Papadopoulos SM, Crawford NR, Brantley AG, Gealer RL. Comparative mechanical properties of spinal cable and wire fixation systems. Spine 1997;22: 596–604. [9] Carpenter James E, Kasman Roberta, Matthews Larry S. Fractures of the patella. J Bone Joint Surg Am 1993;75:1550–61. [10] Edwards B, Johnell O, Redlund-Johnell L. Patellar fractures. A 30-year follow-up. Acta Orthop Scand 1989;60:712–4. [11] Ndiaye A, Sy MH, Dansokho AV, Sow CM, Massiala G, Bassene N. Early evaluation of surgical treatment for patella fractures. Dakar Med 1996;41:119–23. [12] Smith ST, Cramer KE, Karges DE, Watson JT, Moed BR. Early complications in the operative treatment of patella fractures. J Orthop Trauma 1997;11:183–7. [13] Ritter MA, Eizember LE, Keating ME, Faris PM. Trochanteric fixation by cable grip in hip replacement. J Bone Joint Surg 1991;73:580–1. [14] Johnston RC, Kelly SS. Debris from cobalt–chrome cable may cause acetabular loosening. Clin Orthop 1992;285:140–6. [15] Turner RH, McCarthy JC, Kremchek T, Renten JJ. Reattachment of the greater trochanter after total hip replacement: using the Dall–Miles cable grip system. Presented at the Ninth Combined Meeting of the Orthopaedic Associations of the English Speaking World, Toronto, Canada, June 1992; 1992. [16] Silverton CD, Jacobs JJ, Rosenberg AG, Kull L, Conley A, Galante JO. Complications of a cable grip system. J Arthroplasty 1996;11:400–4. [17] Altenburg AJ, Callaghan JJ, Yehyawi TM, Pedersen DR, Liu SS, Leinen JA, et al. Cemented total hip replacement cable debris and acetabular construct durability. J Bone Joint Surg Am 2009;91:1664–70. [18] Böstman O, Kiviluoto O, Nirhamo J. Comminuted displaced fractures of the patella. Injury 1981;13:196–202. [19] Gardner MJ, Griffith MH, Lawrence BD, Lorich DG. Complete exposure of the articular surface for fixation of patellar fractures. J Orthop Trauma 2005;19:118–23. [20] John J, Wagner WW, Kuiper JH. Tension-band wiring of transverse fractures of patella. The effect of site of wire twists and orientation of stainless steel wire loop: a biomechanical investigation. Int Orthop 2007;31:703–7. [21] Schauwecker R. The practice of osteosynthesis. Stuttgart: Georg Thieme; 1974. [22] Petersen KK, Keller J, Jensen J. Patellar fractures. Modified tension band osteosynthesis. Ugeskr Laeger 1989;151:937–9. [23] Shabat S, Folman Y, Mann G, Gepstein R, Fredman B, Nyska M. Rehabilitation after knee immobilization in octogenarians with patellar fractures. J Knee Surg 2004;17: 109–12. [24] Doran SE, Papadopoulos SM, Miller LD. Internal fixation of the spine using a braided titanium cable: clinical results and postoperative magnetic resonance imaging. Neurosurgery 1996;38:493–7.
Contents lists available at ScienceDirect
The Knee
Management of displaced comminuted patellar fracture with titanium cable cerclage Li Yang, Ouyang Yueping, Yuan Wen ⁎ Department of Orthopaedic Surgery, Changzheng Hospital Affiliated to Second Military Medical University, 450 Feng Yang Road, Shanghai 200003, PR China
a r t i c l e
i n f o
Article history: Received 6 September 2009 Received in revised form 25 January 2010 Accepted 10 February 2010 Keywords: Patellar fracture Displaced fracture Comminuted fracture Titanium cable Cerclage
a b s t r a c t Management of a displaced comminuted patellar fracture is challenging. Tension band wiring and lag screw fixation are not suitable for such a fracture pattern. Stainless steel wiring with various configurations has been the mainstay of treatment. However, issues of loss of fixation and breakage of wire have not been resolved yet. Partial or total patellectomy is the last resort with a detrimental effect on quadriceps power. Braided titanium cable is stronger in tensile strength and better in fatigue resistance than the stainless steel monofilament wire, and the tension of fixation could be controlled by a graded instrument in its application. We used titanium cable to treat 21 consecutive patients with displaced comminuted patellar fracture. Patients were followed up for a mean period of 24 months (12 to 32 months). The mean score at the final follow-up was 27 points (25 to 30) using the Böstman method. There was no complication except breakage of one cable at the sixth week after the operation and the fracture had united despite the breakage. This technique is simple and effective for these difficult fractures and avoided prolonged immobilisation of the knee. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Comminuted fractures of the patella which disrupt the extensor mechanism of the knee require operative treatment. The aim of the treatment is to preserve the bone of the patella, restore the joint surface and provide stable fixation for early mobilisation. Since partial or total patellectomy results in the loss of quadriceps muscle power, it should be avoided if possible [1]. Excision of the small fragments of the bone with the attachment of the patellar tendon by a transosseous pull-out suture is usually indicated [2–5]. Weakness of synthetic nonabsorbable sutures and partial patellectomy requires immobilisation of the knee after operation, which delays rehabilitation and may result in the weakness of the quadriceps muscle [2–4]. Some authors advocate patellotibial cerclage or the use of the figure-of-eight wiring to protect the pull-out suture in order to allow early rehabilitation, but these procedures make it difficult to adjust the length of the patellar tendon [2–5]. This may result in breakage of the wire requiring a second operation for its removal [3–5]. Fixation by using lag screw or conventional figure-of-eight tension band is advocated in patients with transverse fractures for the best results [6]. But such construct is not suitable for displaced comminuted fractures. Stainless steel wire has been associated with breakage and loss of fixation [7]. Braided cables have replaced the wire in upper cervical fusion, arthroplasty and periprosthetic fractures for their superior
⁎ Corresponding author. Tel.: + 86 21 81885632; fax: + 86 21 63720099. E-mail address: [email protected] (Y. Wen). 0968-0160/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.knee.2010.02.005
strength and fatigue resistance [8], furthermore, tension could be controlled through tensioning device. Therefore, we trialed the titanium cable cerclage in treatment of the displaced comminuted patellar fractures. Fractures with multiple fragments are defined as comminuted fractures [9]. Displaced fractures are those with an articular incongruity (step-off) of more than 2 mm or separation of the fragments of more than 3 mm [10]. During the study, patients with displaced patellar transverse fractures were treated with AO modified tension bands. Simple fractures involving a part of the articular surface and the inferior pole of the patella, which are disrupting the patellar ligament were treated with lag screw or ectomy. Fractures that didn't disturb the quadriceps mechanism were treated conservatively. Another aim of the titanium cable cerclage is to develop the advantage of stainless steel wire cerclage (fit for most of the comminuted patellar fractures and operate simply), and to overcome its disadvantage (loosening and breakage [11–13]). Cobalt–chrome cable fixation has been associated with fretting and metallic debris in total hip arthroplasty [14–17], and we wonder if this is a concern with titanium cerclage for the fracture fixation in the knee. Finally, we asked whether this simple procedure can fix comminuted patellar fractures firmly to allow early functional exercise, and get satisfactory results. 2. Patients and methods The inclusion criteria of the patients with titanium cable cerclage were as follows; the general physical condition of the patients could withstand the anesthesia and operation, fractures involved the
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patellar articular surface and without any deep infection, fractures with multiple fragments and with an articular incongruity (step-off) of more than 2 mm or a separation of the fragments of more than 3 mm, and fractures disrupted the quadriceps mechanism. The exclusion criteria were; the general physical condition of the patients could not withstand the anesthesia and operation, fractures didn't involve any articular surface, fractures with deep infection, fragments were less than three, fractures with an articular incongruity (step-off) of less than 2 mm and the separated distance was less than 3 mm, and fractures with quadriceps mechanism were not disturbed. We retrospectively reviewed 21 consecutive patients (12 males and nine females) with displaced comminuted patellar fractures (Fig. 1A) who were treated surgically due to the inability to straight leg raise, three of whom with three fragments, 16 with four fragments and two with five ones. Eighteen were closed, and three were open fractures (Gustilo II). No patient was found with any associated injuries. Two patients had type 2 diabetes, two had hypertension, the others were not found with background disease. All the patients were treated with titanium cable cerclage in our department between May 2005 and September 2008. Their mean age was 40 years (range, 25 to 65 years). There was no loss to follow-up, and the minimum followup was 12 months (mean, 24 months; range, 12 to 32 months). Anteroposterior radiographs (Fig. 1B) and lateral radiographs (Fig. 1C) were obtained at 2 days, 6 weeks, 8 weeks, and 12 weeks after surgery, and subsequently half-yearly follow-ups. And the roentgenographic results were independently assessed by radiologists who were not involved in the study. Cable breakage, fraying, fragmentation, and the presence of metallic debris and loosening were recorded. Loosening was defined as the diameter of the cable loop expanded. The function of the knee was evaluated by using the method of Böstman, Kiviluoto and Nirhamo [18] by one of the authors at the latest follow-up (Table 1).
Table 1 Details of the clinical grading scale of Böstman et al. [18]. Variable
Point
Range of movement (ROM) Full extension and the ROM N 120°or within 10°of the normal side 6 Full extension, movement 90° to 120° 3 Pain None or minimal on exertion 6 Moderate on exertion 3 In daily activity 0 Work Original job 4 Different job 2 Cannot work 0 Atrophy, difference of circumference of thigh 10 cm proximal to the patella b12 mm 4 12 to 25 mm 2 N25 mm 0 Assistance in walking None 4 Cane part of the time 2 Cane all the time 0 Effusion None 2 Reported to be present 1 Present 0 Giving way None 2 Sometimes 1 In daily life 0 Stair-climbing Normal 2 Disturbing 1 Disabling 0 Total score Excellent 30 to 28 Good 27 to 20 Unsatisfactory b20
3. Surgical technique The fracture was exposed through midline longitudinal incision. For closed fractures, the retinaculum was left intact to help reduction. In open fractures, debridement was conducted before reduction. When the retinaculum was disrupted, our reduction maneuver involved passing temporary suture (1 vicryl) around the patella to cobble the fragments together. Then the articular surface was palpated and reduction adjusted
accordingly through arthrotomy. Final reduction was checked by image intensifier. One braided titanium cable (Atlas titanium cable) was cut in halves. The cables were passed circumferentially around the patella (Fig. 2A, B) forming two loops, one at one third and one at two thirds of the patellar in depth from the articular surface (Fig. 2C, D). Making
Fig. 1. (A–C) A lateral radiograph (A) shows displaced and comminuted fractures of the patellar. A lateral radiograph (B) and an anteroposterior radiograph (C) were taken at 6 weeks after the operation, which show displaced comminuted fragments were reduced and fixed by two loops of titanium cables and have got a bony union at 8 weeks after the operation.
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The affected limb was raised in postoperative days for 1 week. There was no immobility after the operation, functional exercises were started as early as the first day after the internal-fix operation. CPM (continuous passive movement) machines were used to facilitate the early postoperative range of motion exercises of the knee. Patients were allowed to mobilize as comfort allowed under the supervision of the physiotherapists, and partially or full weight bearing was acceptable from the third day after operation. 4. Results
Fig. 2. (A–D) Diagrams show that the displaced comminuted patellar fracture is reduced and then fixed circumferentially with two loops of titanium cables (A, B), one at one third and one at two thirds of the patellar in depth from the articular surface (C, D), and the cables are next to the bone tissue of the patellar (B, D).
The mean time between injury and surgery was 3 days (range, 2 to 7 days). The mean operation time was 54 min (range, 35 to 70 min). The mean time between the operation and the union was 46 days (range 40 to 68 days). No cerclage loosening or fragment displacement was noted. There was no nonunion, delayed union or infection. No evidence of post-traumatic osteoarthritis was found at the latest follow-up. The roentgenographic evaluation did not show any fraying of cables or metallic debris. A breakage of one loop of the cable was detected at the sixth week after the operation (Fig. 3A, B), the patient was asymptomatic. She was not allowed to full weight bear until bony union which was confirmed in another four weeks. Elective operation was conducted to remove the titanium cables in out-patient clinic operation rooms after the fractures had been bony united. A 0.5 centimeter incision was made at the site of the crimps after local anesthesia. After the crimps were exposed and the cables cut, the titanium cables could be removed easily. Nine patients (including the patient with cable breakage) were operated to remove the cables in out-patient clinic operation rooms after the bony union was achieved, and no fraying, fragmentation or metallic debris was noted at the time of cable removal. Satisfactory results were obtained in terms of the recovery of knee function. The mean score at the final follow-up was 28.6 points (range 26 to 30 points) by the method of Böstman et al. [18]. Seventeen patients (81%) had excellent, four (19%) had good result, no patients had an unsatisfactory result.
5. Discussion
sure the cables were next to the bone (Fig. 2B, D), the cables were tensioned to 30 lbs. The articular surface was checked again by palpation and image intensifier, and the knee was flexed to 90° to confirm that the fragments would not separate over 1 mm, before crimps were applied and the excess cables were cut. The soft tissue envelope was then repaired over the patellar with suture and the wound was closed in layers.
In our series, the functional results were excellent in 81%, and good in 19%, which were better than that were reported in literature [11,12]. A review of 49 patellar fractures shows that 22% of fractures displaced more than 2 mm at the fracture site with early mobilisation after tension band wiring [12]. Another report of 26 patellar fractures of which 18 cases received modified tension band internal fixation, five cases for tension band wiring and three cases for circumferential wire loop fixation, the functional results were poor in 50% [11].
Fig. 3. (A–B) A breakage of one loop of the cable was detected through an anteroposterior radiograph (A) and a lateral radiograph (B) in a 25-year-old female patient at the sixth week, and the bone union had been achieved without any malunion.
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Due to the variety of the patellar fracture patterns, there is no single surgical technique to deal with all of them. Anterior tension band fixation constructs are among the mainstay of the treatment of patella fractures and lead to reliable results with simple transverse fracture patterns. However, comminuted fractures of the patella require much more extensive articular reconstruction than interdigitating two large fragments to achieve a good result [19]. Circumferential wiring with stainless steel wires is not accepted for its weakness and loosening in fixation [7]. Functional exercise with CPM and active quadriceps exercises were started as early as the first operative day in our cases, no loss of the fixation or displacement of the fragments was found. Maybe this is one of the reasons that satisfactory results were noted at the end of the therapy. In contrast, according to the literature, early mobilisation is important but causes detrimental displacement at the fracture site [20]. The main reason for the loss of fixation in tension band wiring is the friction and plastic deformation caused by the wire sliding around the Kirschner wire [21].As a result, most of the comminuted patellar fractures treated with tension band have to be immobilized for weeks after operation [22,23], which would reduce the losses of fixation but at the cost of the final knee function. The characteristics of the titanium cable allow it to fix patellar fractures more firmly without any loosening than that stainless steel wires can. The tensile strength of a braided titanium cable is three to six times to a traditional stainless steel monofilament wire with the comparable diameter, and the fatigue resistance is nine to 48 times [8]. When the same force was exerted on the stainless steel wire and the titanium cable for 24 h, creep occurs in the stainless steel wire but not in the titanium cable [8]. Though the cobalt chrome cable is generally considered to be stronger than the titanium cable, considering the potential problems of fraying, fragmentation and the metallic debris from the cobalt chrome cable in arthroplasty which were reported in literature [14–17], we alternated to the titanium cable. Perhaps it is the character of the titanium made that we did not find any frying, fragmentation and metallic debris in our series, it is also maybe attributed to the limitation of the follow-up time in our series. And also we do not find any reports about fraying, fragmentation and the metallic debris of the cables in the fracture but in arthroplasty. In addition, the more sophisticated tensioning device allows an exact tension to be applied to the fracture in comparison with the simplistic wire twisting. Cables also seem to conform to the outline of the patella better after tensioning compared to the stainless steel wire, therefore providing more even compression to the fragments. The histocompatibility of the titanium is good enough to minimise the scar tissue caused by the internal implants, thus, removal of the implant is easy should the need arises due to prominence. Steel implants also create a significant artifact on MRI, reducing the postoperative usefulness of this imaging modality. Titanium has the advantage of producing minimal MRI artifact [24] thus the articular surface could be assessed by this modality. One breakage of the cable was detected in a 25-year-old female patient at the sixth week after surgery, it was probably associated with the patient falling down when climbing up the stairs and with the operated knee extended suddenly and powerfully with full weight bearing. Plain films showed that the other loop of the cable was unbroken and the fracture had been united, without any complaints the patient was not allowed full weight bearing in another 2 weeks. The cables were removed 6 months after the operation, and the patient was satisfied with the excellent result of the knee function, the grading at the final follow-up was 30 points. In conclusion, although our study is limited by the lack of a control group, and the titanium cable is more expensive than the stainless steel wire, the results of our review suggest that treatment of comminuted patellar fracture is better with titanium cable cerclage than that with the stainless wire. Firm fixation with controlled tension
allows early functional exercise and weight bearing, which contributes to an excellent and good result in short-term and long-term recovery. This new surgical technique may be particularly useful in comminuted fractures when patellar excision would otherwise be considered. 6. Conflict of interest statement Each author certifies that he has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article. Acknowledgements We would like to thank Professor Gou Sanhuai, who gave us general support. We thank Doctor Zhang Ying, Chen Fangjing, and Xu Shengming for helping us gather the data. We thank Tian Ye and Shen Xiaolong for the critical review of our paper, and we appreciate Dong Ren, Zhu Yuzhao, and Guo Wei for the participation in our clinical trail. We so appreciate Tsai Nick for his advice during the revision. References [1] Galla M, Lobenhoffer P. Patella fractures. Chirurg 2005;76:987–97. [2] Hung LK, Lee SY, Leung KS, Chan KM, Nicholl LA. Partial patellectomy for patellar fracture: tension band wiring and early mobilisation. J Orthop Trauma 1993;7: 252–60. [3] Nerlich M, Weigel B. Patella. In: Rüedi TP, Murphy WM, editors. AO principals of fracture management. Stuttgart and New York: Thieme; 2000. p. 483–97. [4] Saltzman CL, Goulet JA, McClellan RT, Schneider LA, Matthews LS. Results of treatment of displaced patella fractures by partial patellectomy. J Bone Joint Surg Am 1990;72-A:1279–85. [5] Whittle AP. Fractures of lower extremity. In: Canale ST, editor. Campbell's operative orthopaedics, Ninth ed., vol. 3. St Louis: Mosby; 1998. p. 2042–179. [6] Ozdemir H, Ozenci M, Dabak K, Aydin AT. Outcome of surgical treatment for patellar fracture. Turkish J Trauma Emergency Surg 2001;7:56–9. [7] Weber MJ, Janecki CJ, McLeod P, Nelson CL, Thompson JA. Efficacy of various forms of fixation of transverse fractures of the patella. J Bone Joint Surg Am 1980;62:215–20. [8] Dickman CA, Papadopoulos SM, Crawford NR, Brantley AG, Gealer RL. Comparative mechanical properties of spinal cable and wire fixation systems. Spine 1997;22: 596–604. [9] Carpenter James E, Kasman Roberta, Matthews Larry S. Fractures of the patella. J Bone Joint Surg Am 1993;75:1550–61. [10] Edwards B, Johnell O, Redlund-Johnell L. Patellar fractures. A 30-year follow-up. Acta Orthop Scand 1989;60:712–4. [11] Ndiaye A, Sy MH, Dansokho AV, Sow CM, Massiala G, Bassene N. Early evaluation of surgical treatment for patella fractures. Dakar Med 1996;41:119–23. [12] Smith ST, Cramer KE, Karges DE, Watson JT, Moed BR. Early complications in the operative treatment of patella fractures. J Orthop Trauma 1997;11:183–7. [13] Ritter MA, Eizember LE, Keating ME, Faris PM. Trochanteric fixation by cable grip in hip replacement. J Bone Joint Surg 1991;73:580–1. [14] Johnston RC, Kelly SS. Debris from cobalt–chrome cable may cause acetabular loosening. Clin Orthop 1992;285:140–6. [15] Turner RH, McCarthy JC, Kremchek T, Renten JJ. Reattachment of the greater trochanter after total hip replacement: using the Dall–Miles cable grip system. Presented at the Ninth Combined Meeting of the Orthopaedic Associations of the English Speaking World, Toronto, Canada, June 1992; 1992. [16] Silverton CD, Jacobs JJ, Rosenberg AG, Kull L, Conley A, Galante JO. Complications of a cable grip system. J Arthroplasty 1996;11:400–4. [17] Altenburg AJ, Callaghan JJ, Yehyawi TM, Pedersen DR, Liu SS, Leinen JA, et al. Cemented total hip replacement cable debris and acetabular construct durability. J Bone Joint Surg Am 2009;91:1664–70. [18] Böstman O, Kiviluoto O, Nirhamo J. Comminuted displaced fractures of the patella. Injury 1981;13:196–202. [19] Gardner MJ, Griffith MH, Lawrence BD, Lorich DG. Complete exposure of the articular surface for fixation of patellar fractures. J Orthop Trauma 2005;19:118–23. [20] John J, Wagner WW, Kuiper JH. Tension-band wiring of transverse fractures of patella. The effect of site of wire twists and orientation of stainless steel wire loop: a biomechanical investigation. Int Orthop 2007;31:703–7. [21] Schauwecker R. The practice of osteosynthesis. Stuttgart: Georg Thieme; 1974. [22] Petersen KK, Keller J, Jensen J. Patellar fractures. Modified tension band osteosynthesis. Ugeskr Laeger 1989;151:937–9. [23] Shabat S, Folman Y, Mann G, Gepstein R, Fredman B, Nyska M. Rehabilitation after knee immobilization in octogenarians with patellar fractures. J Knee Surg 2004;17: 109–12. [24] Doran SE, Papadopoulos SM, Miller LD. Internal fixation of the spine using a braided titanium cable: clinical results and postoperative magnetic resonance imaging. Neurosurgery 1996;38:493–7.