Preoperative radiography versus computed tomography for surgical planning for ankle fractures

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1 Journal of Orthopaedic Surgery 2016;24(2): Preoperative radiography versus computed tomography for surgical planning for ankle fractures Ka Hei Leung, 1 Christian Xin Shuo Fang, 1 Tak Wing Lau, 1 Frankie Ka Li Leung 1,2 1 Department of Orthopaedics and Traumatology, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China 2 Shenzhen Key Laboratory for Innovative Technology in Orthopaedic Trauma, The University of Hong Kong-Shenzhen Hospital, Shenzhen, China ABSTRACT Purpose. To review preoperative radiography and computed tomography (CT) of the ankle in 69 patients who underwent surgery for ankle fractures to determine the value of CT in diagnosis and surgical planning. Methods. Preoperative radiography and CT of the ankle of 46 women and 23 men aged 17 to 90 (mean, 48.8) years were reviewed. CT was deemed necessary when radiographs showed the following features: (1) comminuted fracture of the medial malleolus involving the tibial plafond, (2) comminuted fracture of the posterior malleolus, (3) presence of loose bodies, and/or (4) suspected Chaput or Volkman fracture fragment. Two orthopaedic surgeons independently reviewed the radiographs to look for any of the above features for which CT was indicated. In patients whose radiographs did not show any of the above features, each surgeon formulated a surgical plan based on radiographs alone and decided if any modification was needed after reviewing the CT scan. Results. Based on radiographs of the 69 patients, 19 (28%) patients had features of posterior malleolar comminution (n=7), medial malleolar comminution (n=7), suspected Chaput fracture fragment (n=1), suspected Volkman fracture fragment (n=1), and combination of 2 lesions (n=3), and were deemed to require CT. In 10 (20%) of the remaining 50 patients, the surgical plan was modified after review of the CT scan. The intra- and inter-observer agreement was good to excellent. Conclusion. Radiography alone is not adequate for surgical planning for ankle fractures. More accurate imaging tools such as CT are needed to enable a more accurate diagnosis and surgical planning. Key words: ankle fractures; joint loose bodies; radiography; tomography, X-ray computed INTRODUCTION Surgical treatment is indicated for unstable ankle fractures such as displaced bimalleolar fractures, Address correspondence and reprint requests to: Dr Ka Hei Leung, Room 429, Block K, Queen Mary Hospital, 102 Pokfulam Road, Hong Kong. leungkahei@hotmail.com

2 Vol. 24 No. 2, August 2016 Preoperative radiography versus computed tomography for surgical planning for ankle fractures 159 lateral malleolar fractures together with medial soft tissue injury, and fractures associated with syndesmosis disruptions. 1 Surgical planning is usually based on standard anteroposterior, lateral, and mortise-view radiographs. 2 The outcome is usually good when there is no comminution of the articular surface or loose bodies. 3 7 Nonetheless, unsatisfactory outcome may occur owing to failure to recognise and treat displaced fracture fragments, articular incongruity, and/or syndesmotic injuries Computed tomography (CT), magnetic resonance imaging (MRI), intra-operative 3-dimensional imaging (Intraop 3D), and arthroscopy can help detect these lesions. CT has good inter-observer agreement. 15 This study reviewed preoperative radiography and computed tomography of the ankle in 69 patients who underwent surgery for ankle fractures to determine the value of CT in diagnosis and surgical planning. MATERIALS AND METHODS Preoperative radiography and CT of the ankle of 46 women and 23 men aged 17 to 90 (mean, 48.8) years who underwent surgery for ankle fractures in our hospital between January 2012 and December 2013 were reviewed using a DICOM-based viewer (Centricity version 3.1.4, GE Healthcare, United Kingdom). Patients with pilon fracture were excluded (because CT would be necessary for delineation 16 ), as were skeletally immature patients with open physis (because of differing fracture pattern). Common indications for the use of CT are the presence of comminuted intra-articular fractures, loose bodies in the ankle joint, and/or syndesmosis on radiographs CT was deemed necessary when radiographs showed the following features: (1) comminuted fracture of the medial malleolus involving the tibial plafond, (2) comminuted fracture of the posterior malleolus, (3) presence of loose bodies, and/or (4) suspected Chaput or Volkman fracture fragment (Figs. 1 to 4). Two orthopaedic surgeons independently reviewed the radiographs to look for any of the above features for which CT was indicated. In patients whose radiographs did not show any of the above features, each surgeon formulated a surgical plan based on radiographs alone and decided if any modification was needed after reviewing the CT scan. One of the surgeons repeated the decision making process at least 3 months later to evaluate the intra-observer agreement. The inter- and intra-observer agreement was evaluated using the Spearman correlation test. 20 Figure 1 Radiographs showing comminuted posterior malleolar fracture, and syndesmotic diastasis and a suspected Volkmann fracture fragment. Figure 2 Radiograph showing a Weber C bimalleolar fracture. Computed tomography showing a Chaput fracture fragment. (c) The fragment is fixed with 2 interfragmentary compression screws (instead of a syndesmotic screw). The agreement of a correlation coefficient of was considered as slight, as fair, as moderate, as good, and 0.81 as excellent. 21 A p value of <0.05 was considered statistically significant. RESULTS Based on radiographs of the 69 patients, 19 (28%) patients had features of posterior malleolar (c)

3 160 KH Leung et al. Journal of Orthopaedic Surgery comminution (n=7), medial malleolar comminution (n=7), suspected Chaput fracture fragment (n=1), suspected Volkman fracture fragment (n=1), and combination of 2 lesions (n=3), and were deemed to require CT. The Spearman correlation coefficient for intra- and inter-observer agreement was 0.75 and 0.85, respectively (p<0.001). In 10 (20%) of the remaining 50 patients, the surgical plan was modified after review of the CT scan (Table). The Spearman correlation coefficient for intra- and inter-observer agreement was 0.76 and 0.88, respectively (p<0.05). DISCUSSION Ankle fracture patterns cannot be shown clearly (c) Figure 3 Radiograph showing a Weber C fracture with lateral and posterior malleolar fractures and diastasis of the syndesmosis. Computed tomography showing a loose body inside the distal tibiofibular joint. (c) The syndesmosis is opened to remove the loose body. on radiographs. 15,22 25 In 24% of patients with ankle fracture, surgical plan (based on radiographs) was modified after review of the CT scan. 15 The modifications involved the medial malleolus, the posterior malleolus, a Tillaux fragment, and removal of loose bodies with or without microfractures. In our study, 3 types of lesion could potentially have been missed: posterior malleolar lesion, presence of loose bodies, and bony avulsion around the syndesmosis. Radiographs are unreliable in assessing posterior malleolar fractures. 22,24 Radiographs underor over-estimated the size of the fragment in 54% of trimalleolar ankle fractures. 22 Radiographs grossly underestimated the comminution and impaction of the articular surface in trimalleolar fractures. 24 In our study, one simple bimalleolar fracture with no obvious posterior involvement on radiographs was revealed on CT to be a sizable posterior malleolar fragment with articular incongruity. In 3 patients, loose bodies were identified on CT and required removal or microfracture treatment of the exposed bone surface. Although the ankle joint and medial and lateral gutters can be visible on radiographs, slight rotation of the limb may overlap the bones and obscure loose fragments. Clear visualisation of syndesmosis is difficult because of overlapping of the distal tibia and fibula. Arthroscopy found a 38% incidence of talar dome lesion in supination-external rotation stage IV ankle fractures. 26 The use of CT to detect loose bodies and associated osteochondral defect may improve clinical outcome. 27 A Chaput fragment in one patient with a Weber C fracture was finally picked up by CT (Fig. 3). The Chaput fragment was actually an avulsion fracture of the anteroinferior tibiofibular ligament. It signifies disruption of the syndesmosis. 28 If it is not identified, most surgeons would simply fix the high fibular fracture and supplement with a syndesmosis screw. If it is identified, it can be fixed back to the distal tibia to obviate the need for removal (c) Figure 4 Radiographs showing a Maisonneuve injury with a fibular fracture, medial malleolar fracture, and no obvious posterior malleolar fracture. Computed tomography showing a comminuted posterior malleolar fracture that involves one third of the articular surface. (c) The medial malleolar fracture is fixed with a syndesmotic screw, and the posterior malleolar fracture is fixed with open reduction and internal fixation.

4 Vol. 24 No. 2, August 2016 Preoperative radiography versus computed tomography for surgical planning for ankle fractures 161 Table Surgical planning based on radiographs and its modification based on computed tomographic features in 10 patients Radiographic feature Surgical plan Computed tomographic feature Modification of surgical plan Weber B bimalleolar fracture (n=4) Bimalleolar fixation Posterior malleolar fracture of significant size or articular incongruity (n=3) Open reduction and internal fixation (ORIF) of posterior malleolar fragment Weber B lateral malleolar fracture (n=2) Weber C lateral malleolar fracture (n=3) Weber C bimalleolar fracture (n=1) Lateral malleolar fixation Lateral malleolar fixation & syndesmotic fixation Bimalleolar fixation & syndesmotic fixation Loose fragments in medial gutter (n=1) Posterior malleolar fracture of significant size or articular incongruity (n=1) Loose osteochondritis dessicans fragment from the lateral talar dome (n=1) Posterior malleolar fracture of significant size or articular incongruity (n=2) Removal of loose bodies ORIF of posterior malleolar fragment Removal of loose fragment and microfracture ORIF of posterior malleolar fragment Loose body inside the syndesmosis (n=1) Open reduction of syndemosis and removal of loose body Displaced Chaput fracture fragment (n=1) ORIF of Chaput fragment of the syndesmosis screw. Mal-reduced and mal-united intra-articular ankle fractures can lead to accelerated arthritis. The anatomy of the ankle joint confers natural protection against degeneration. As a result the prevalence of symptomatic arthritis at the ankle was only around 1% in the population while that at the knee was around 12%. 29 The protective mechanisms include a high joint congruency, motion mainly on a single plane, stiffness and other specific biological properties of the ankle cartilage. 30 These protective mechanisms can be disturbed by an incongruent ankle joint. Post-traumatic arthritis is the most common cause of ankle degeneration. More accurate imaging modalities are thus necessary. 23,24,31 36 MRI is highly accurate for the diagnosis of syndesmosis disruption and other soft tissue injury such as deltoid ligament and osteochondritis dessicans, 31,32 but it has a high operational cost and is not widely available. Delineation of osseous pathology may be inferior to CT. CT is more sensitive than radiography in detecting the pattern of posterior malleolar injury and syndesmotic diastasis Arthroscopy can be used to diagnose and assist reduction of the articular surface and syndesmosis, 33,34 but it requires high expertise and prolongs the operating time. Intraop 3D can provide useful information that cannot be obtained from radiography, 35,36 but it does not allow surgical planning as its use is in real-time. The surgical plan can only be modified intra-operatively. Moreover, its cost and radiation exposure remains a concern. CONCLUSION Radiography alone is not adequate for surgical planning for ankle fractures. More accurate imaging tools such as CT are needed to enable a more accurate diagnosis and surgical planning. DISCLOSURE No conflicts of interest were declared by the authors. REFERENCES 1. Michelson JD. Ankle fractures resulting from rotational injuries. J Am Acad Orthop Surg 2003;11: Brandser EA, Berbaum KS, Dorfman DD, Braksiek RJ, El-Khoury GY, Saltzman CL, et al. Contribution of individual projections alone and in combination for radiographic detection of ankle fractures. AJR Am J Roentgenol 2000;174: Chaudhary SB, Liporace FA, Gandhi A, Donley BG, Pinzur MS, Lin SS. Complications of ankle fracture in patients with diabetes. J Am Acad Orthop Surg 2008;16: Baraza N, Lever S, Dhukaram V. Home therapy pathway - safe and streamlined method of initial management of ankle fractures. Foot Ankle Surg 2013;19: McDaniel WJ, Wilson FC. Trimalleolar fractures of the ankle. An end result study. Clin Orthop Relat Res 1977;122:37 45.

5 162 KH Leung et al. Journal of Orthopaedic Surgery 6. Baird RA, Jackson ST. Fractures of the distal part of the fibula with associated disruption of the deltoid ligament. Treatment without repair of the deltoid ligament. J Bone Joint Surg Am 1987;69: Harper MC, Hardin G. Posterior malleolar fractures of the ankle associated with external rotation-abduction injuries. Results with and without internal fixation. J Bone Joint Surg Am 1988;70: Beris AE, Kabbani KT, Xenakis TA, Mitsionis G, Soucacos PK, Soucacos PN. Surgical treatment of malleolar fractures. A review of 144 patients. Clin Orthop Relat Res 1997;341: Day GA, Swanson CE, Hulcombe BG. Operative treatment of ankle fractures: a minimum ten-year follow-up. Foot Ankle Int 2001;22: Berkes MB, Little MT, Lazaro LE, Pardee NC, Schottel PC, Helfet DL, et al. Articular congruity is associated with short-term clinical outcomes of operatively treated SER IV ankle fractures. J Bone Joint Surg Am 2013;95: Weening B, Bhandari M. Predictors of functional outcome following transsyndesmotic screw fixation of ankle fractures. J Orthop Trauma 2005;19: Chissell HR, Jones J. The influence of a diastasis screw on the outcome of Weber type-c ankle fractures. J Bone Joint Surg Br 1995;77: Jaskulka RA, Ittner G, Schedl R. Fractures of the posterior tibial margin: their role in the prognosis of malleolar fractures. J Trauma 1989;29: Langenhuijsen JF, Heetveld MJ, Ultee JM, Steller EP, Butzelaar RM. Results of ankle fractures with involvement of the posterior tibial margin. J Trauma 2002;53: Black EM, Antoci V, Lee JT, Weaver MJ, Johnson AH, Susarla SM, et al. Role of preoperative computed tomography scans in operative planning for malleolar ankle fractures. Foot Ankle Int 2013;34: Dvaidovitch RI, Egol KA. Ankle fractures. In: Bucholz RW, Heckman JD, Court-Brown CM, Tornetta III P, editors. Rockwood and Green s fractures in adults. Vol II, 7th ed. Lippincott Williams & Wilkins; 2010: Schmidt AH, Kallas KM. Imaging considerations in orthopaedic trauma. In: Bucholz RW, Heckman JD, Court-Brown CM, Tornetta III P, editors. Rockwood and Green s fractures in adults. Vol I, 7th ed. Lippincott Williams & Wilkins; 2010: Olsen JR, Hunter J, Baumhauer JF. Osteoporotic ankle fractures. Orthop Clin North Am 2013;44: Carr JB. Malleolar fractures and soft tissue injuries of the ankle. In: Browner JB, editor. Skeletal trauma: basic science, management, and reconstruction. Vol II, 4th ed. Saunders; 2009: Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986;1: Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977;33: Ferries JS, DeCoster TA, Firoozbakhsh KK, Garcia JF, Miller RA. Plain radiographic interpretation in trimalleolar ankle fractures poorly assesses posterior fragment size. J Orthop Trauma 1994;8: Ebraheim NA, Lu J, Yang H, Mekhail AO, Yeasting RA. Radiographic and CT evaluation of tibiofibular syndesmotic diastasis: a cadaver study. Foot Ankle Int 1997;18: Buchler L, Tannast M, Bonel HM, Weber M. Reliability of radiologic assessment of the fracture anatomy at the posterior tibial plafond in malleolar fractures. J Orthop Trauma 2009;23: Magid D, Michelson JD, Ney DR, Fishman EK. Adult ankle fractures: comparison of plain films and interactive two- and three-dimensional CT scans. AJR Am J Roentgenol 1990;154: Sorrento DL, Mlodzienski A. Incidence of lateral talar dome lesions in SER IV ankle fractures. J Foot Ankle Surg 2000;39: O Loughlin PF, Heyworth BE, Kennedy JG. Current concepts in the diagnosis and treatment of osteochondral lesions of the ankle. Am J Sports Med 2010;38: Somford MP, Wiegerinck JI, Hoornenborg D, van den Bekerom MP. Ankle fracture eponyms. J Bone Joint Surg Am 2013;95:e198(1-7). 29. Thomas RH, Daniels TR. Current concepts review: ankle arthritis. J Bone Joint Surg Am 2003;85: Huch K, Kuettner KE, Dieppe P. Osteoarthritis in ankle and knee joints. Semin Arthritis Rheum 1997;26: Oae K, Takao M, Naito K, Uchio Y, Kono T, Ishida J, et al. Injury of the tibiofibular syndesmosis: value of MR imaging for diagnosis. Radiology 2003;227: Jeong MS, Choi YS, Kim YJ, Kim JS, Young KW, Jung YY. Deltoid ligament in acute ankle injury: MR imaging analysis. Skeletal Radiol 2014;43: Holt ES. Arthroscopic visualization of the tibial plafond during posterior malleolar fracture fixation. Foot Ankle Int 1994;15: Takao M, Ochi M, Naito K, Iwata A, Kawasaki K, Tobita M, et al. Arthroscopic diagnosis of tibiofibular syndesmosis disruption. Arthroscopy 2001;17: Richter M, Geerling J, Zech S, Goesling T, Krettek C. Intraoperative three-dimensional imaging with a motorized mobile C-arm (SIREMOBIL ISO-C-3D) in foot and ankle trauma care: a preliminary report. J Orthop Trauma 2005;19: Richter M. Computer aided surgery in foot and ankle: applications and perspectives. Int Orthop 2013;37: