Arch Orthop Trauma Surg (2014) 134:1661–1666 DOI 10.1007/s00402-014-2095-4
ORTHOPAEDIC SURGERY
Ankle injuries in distal tibial spiral shaft fractures: results from an institutional change in imaging protocol Stephen J. Warner • Patrick C. Schottel Matthew R. Garner • David L. Helfet • Dean G. Lorich
•
Received: 24 July 2014 / Published online: 22 October 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Introduction Posterior malleolus and other articular ankle injuries are known to concomitantly occur with tibial shaft fractures, especially spiral fractures of the distal one-third diaphysis. Due to our heightened awareness of this combined injury, our department instituted a new preoperative ankle imaging protocol for all distal one-third spiral tibia shaft fractures. The purpose of this study was to evaluate the effectiveness of an imaging protocol involving radiographs, CT and magnetic resonance imaging (MRI) in a distal one-third spiral tibia fracture cohort. Materials and methods All operatively treated patients with a spiral distal one-third tibial shaft fracture from February 2012 to March 2013 underwent a standardized ankle imaging protocol. Patients had preoperative orthogonal ankle radiographs as well as a CT scan of the tibia that included the ankle. All ankle imaging was scrutinized for evidence of an ankle injury. If no ankle fracture was identified, patients would then undergo an ankle MRI. Results Twenty-five patients met the inclusion and exclusion criteria for this study. Concomitant osseous ankle injuries were identified by radiograph and CT in 56 % (14/ 25) of cases. The remaining 44 % (11/25) of patients had no evidence of a combined injury by radiograph or CT and therefore underwent an MRI. Of the MRI cohort, 64 % (7/ 11) were found to have an occult ankle fracture. The S. J. Warner (&) P. C. Schottel M. R. Garner Orthopaedic Trauma Service, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA e-mail: [email protected] D. L. Helfet D. G. Lorich Orthopaedic Trauma Service, Hospital for Special Surgery and Weill Cornell Medical College, New York Presbyterian Hospital, New York, NY, USA
overall incidence of a combined injury using our protocol was 84 % (21/25). Identification of an occult injury led to a change in management for all of these patients. Conclusions Concomitant ipsilateral ankle and distal onethird spiral tibial shaft fractures are more common than previously reported. Utilizing a new imaging protocol, we found that the incidence of this combined injury was 84 %. Recognition of the ankle fracture component in this tibial shaft cohort can be important as it may alter the surgical plan and postoperative management. Keywords Tibial shaft fracture Ankle fracture MRI Distal spiral shaft fracture
Introduction Posterior malleolus and other articular ankle injuries are known to concomitantly occur with tibial shaft fractures [1– 7]. Recent publications utilizing computed tomography (CT) have shown that the rate of this combined injury is higher than previously reported, with incidences ranging between 39 and 49 % [5–7]. Additionally, the location and pattern of the tibial shaft fracture has been found to be predictive of an ipsilateral ankle injury with combination injuries more often occurring in patients with a distal one-third diaphyseal location and spiral pattern [7]. Therefore, due to the high rate of combined injuries in this particular patient cohort, some authors have advocated that clinicians should have a low threshold for advanced imaging in order to diagnose an occult ankle fracture. However, despite the addition of CT to aid in recognition of an ipsilateral ankle fracture, other imaging modalities such as magnetic resonance imaging (MRI) that could potentially improve identification of these occult injuries have not been studied as extensively.
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Recognition of a concomitant ipsilateral ankle injury in a tibial shaft fracture is important as it can often alter the surgical plan and rehabilitation protocol. Failure to properly treat the ankle fracture component during operative tibial fixation may result in further displacement and subsequent ankle articular incongruity, which is known to affect patient outcomes [8]. Therefore, some authors have advocated for surgical fixation of posterior malleolus fractures prior to intramedullary fixation [5, 9]. Due to the potential impact this combined injury has on treatment and its high incidence, our Orthopaedic department instituted a new preoperative ankle imaging protocol for all distal onethird spiral tibial shaft fractures. The purpose of this study was to evaluate the effectiveness of an imaging protocol involving radiographs and CT with the addition of MRI in identifying an ipsilateral ankle injury in a distal one-third spiral tibial shaft fracture cohort. We hypothesized that the addition of MRI would increase our ability to recognize ankle osseoligamentous injuries and provide a more accurate estimate of their incidence.
Materials and methods All operatively treated patients with a spiral distal one-third tibial shaft fracture from February 2012 to March 2013 were initially identified from the senior surgeon’s surgical case logs. To determine if a fracture was in the distal onethird of the tibia shaft, the full length of the tibia was measured and divided into equal thirds; only spiral fractures of the distal third were included. Patients were included for analysis if they completed the standardized ankle imaging protocol described below. Patients less than 16 years of age and individuals with evidence of a prior ankle fracture and retained surgical implants were excluded. Approval for this study was obtained from our hospital’s Institutional Review Board. Prior to this study, our institution’s preoperative imaging evaluation of distal one-third spiral tibial shaft fractures included orthogonal tibia radiographs with additional dedicated ankle views. A CT scan without iodinated contrast of the tibia that included the ankle was also obtained in all cases to assess for a concomitant ankle fracture. All CT scans were performed on a 64-slice scanner utilizing 1.25 mm axial slices. For this study, all radiographic and CT ankle imaging was similarly obtained in every patient with a distal one-third spiral tibial shaft fracture and evaluated by an on-call orthopaedic resident for evidence of an articular ankle injury such as a posterior malleolus fracture (PMF), medial malleolus fracture (MMF) or other tibial plafond fracture variant. However, if no articular ankle fracture was identified, patients would then undergo a dedicated ankle MRI with an extremity coil. It should be
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Arch Orthop Trauma Surg (2014) 134:1661–1666
noted that the location and severity of the fibula fracture, when present, was not influential when deciding to obtain an MRI. All MRI scans were performed with a 1.5T GE scanner (General Electric, Milwaukee, Wisconsin). Preoperative ankle MRIs were retrospectively evaluated by a fellowship trained attending musculoskeletal radiologist for the presence of an articular ankle fracture or injury to ankle ligaments such as the anterior and posterior inferior tibiofibular ligaments (AITFL or PITFL) or deltoid ligament complex. Ligaments were considered intact or ruptured based on the presence and integrity of ligamentous fibers or disruption of fiber orientation and increased signal intensity within the substance of the ligament. Statistical analysis was performed for categorical data by comparing event frequencies between groups using Fisher’s exact test. A p value \0.05 was considered statistically significant.
Results During the study period, 26 patients underwent operative fixation of a distal one-third spiral tibia fracture. One patient had prior open reduction and internal fixation of the ipsilateral ankle and was excluded from the study. The remaining 25 patients underwent the standardized imaging protocol. The average patient age was 47 years (range 16–94) and 52 % (13/25) were male. Concomitant ankle injuries were identified by radiograph in 28 % (7/25) of cases (Fig. 1) and by CT in 56 % (14/25) of cases (Fig. 2). The remaining 44 % (11/25) of patients had no evidence of a combined injury by radiograph or CT and therefore underwent an MRI of the ipsilateral ankle. Of the eleven patients with no radiographic or CT evidence of an ankle injury, 64 % (7/11) were found to have an occult articular ankle fracture (Fig. 3). Five of these occult ankle fractures were of the posterior malleolus (71 %), one was of the medial malleolus (14 %), and one was an AITFL avulsion fracture (14 %). The overall incidence of a combined ipsilateral tibial shaft and ankle fracture using our protocol was 84 % (21/25). The addition of MRI to our imaging protocol resulted in a 50 % increase in the diagnosis of a combined injury (Fig. 4). To determine whether ankle fractures associated with distal third spiral tibia fractures were part of a larger ankle injury, similar to that described by Lauge-Hansen for rotational ankle fractures [10, 11], we analyzed the eleven MRIs obtained in this study for the presence of ligamentous ankle injuries. Five patients had a ligamentous injury, all of which were a ruptured AITFL in patients with a posterior malleolus fracture. Only one patient with an articular ankle fracture, an AITFL avulsion fracture, did
Arch Orthop Trauma Surg (2014) 134:1661–1666
1663
Fig. 1 Anteroposterior (a) and lateral (b) radiographs of a distal third spiral tibial shaft fracture demonstrating the presence of a posterior malleolus fracture. Postoperative anteroposterior (c) and lateral
(d) radiographs demonstrating 2.7 mm interfragmentary screws stabilizing the posterior malleolus fracture
not have a ligamentous injury. The four patients without an articular ankle fracture had no evidence of a ligamentous ankle injury. Within the distal third of the tibia, the four fractures without additional osseoligamentous ankle injuries were all in the proximal third of this region. In comparison, of the other 21 fractures with associated ankle injuries, 14/21 (67 %) were in the proximal third and 7/21 (33 %) were in the middle third of the included region. The difference in fracture location within the distal one-third tibial shaft between patients with or without a ligamentous ankle injury was not statistically significant (p = 0.29). One MRI was unable to be evaluated for ligamentous injury due to motion artifact.
PMF. They found an 88 % incidence of a combined injury using all three imaging modalities [4]. This high percentage of concomitant distal one-third spiral tibial shaft and ankle fractures is very similar to our findings in a North American patient cohort. Of note, the study by Hou et al. [4] did not include ankle injuries other than PMFs. Defining the true incidence of this combined injury and properly identifying these patients has important implications for surgical treatment and rehabilitation protocols. The majority of current recommendations are to internally fix the articular fragment with interfragmentary screws prior to intermedullary nail fixation of the diaphyseal fracture to avoid intraoperative displacement [6, 12, 13]. In addition, restriction of the patient’s post-operative weight bearing has also been suggested to prevent subsequent displacement and articular incongruity [5]. Our typical treatment protocol is to stabilize all PMFs with one or two anterior to posterior 2.7 mm interfragmentary screws and a small fragment (e.g. 2.4 mm) reconstruction plate for MMFs. We also typically prescribe 6 weeks of non-weight bearing for patients with an articular ankle fracture component. In our study cohort, 71 % of patients underwent fixation of their articular ankle fracture and all patients had modifications to their postoperative ability to bear weight. Despite these recommendations and our routine practice of stabilizing these injuries and restricting postoperative weight bearing, the influence on patient outcomes of recognizing and treating the associated ankle injury is unclear and further work in this area is necessary.
Discussion Our results demonstrate that detection of an ankle injury in patients with a distal one-third spiral tibial shaft fracture can be improved with use of a standardized imaging protocol involving radiographs, CT and MRI. Using this protocol, we found that the incidence of a combined injury was 84 %. This rate is higher than previous reports of 39–49 % that used only radiographs and CT [5–7]. To our knowledge only one previous study has used MRI to assist with identifying an occult ankle injury in patients with an ipsilateral distal one-third spiral tibia fracture. Hou et al. [4] performed a similar imaging protocol in 34 Chinese patients consisting of radiographs and CT followed by MRI for patients without evidence of a
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Arch Orthop Trauma Surg (2014) 134:1661–1666
Fig. 2 Anteroposterior (a) and lateral (b) radiographs of a distal third spiral tibial shaft fracture with no obvious articular ankle injury fracture. Sagittal (c) and axial (d) CT imaging reveals a posterior
malleolus fracture. Postoperative anteroposterior (e) and lateral (f) radiographs demonstrating a 2.7 mm interfragmentary screw stabilizing the posterior malleolus fracture
Importantly, our study is not advocating that MRIs be routinely obtained in this study population. Instead, our results emphasize the fact that this combined injury pattern is almost always present. Combining our findings with those of Hou et al. [4], 86 % (51/59) of distal one-third spiral tibial shaft fractures had evidence of a concomitant ankle fracture. If advanced imaging is not obtained due to limited facility resources or patient and surgeon preference, we therefore recommend heightened awareness of possible PMF or other distal tibial articular fragment displacement during operative fixation or postoperatively with weight bearing. Complaints of ankle pain in this patient cohort should not be ignored. As part of our MRI analysis by a musculoskeletal radiologist, we also sought to identify evidence for ankle ligamentous injuries that may be associated with distal third spiral tibia fractures. We suspected that ankle fractures
associated with distal third spiral tibia fractures were part of a larger ankle injury, similar to that described by LaugeHansen for rotational ankle injuries. Consistent with this, all patients with a posterior malleolus fracture also sustained an AITFL rupture. In contrast, no ligamentous injuries were identified in patients without an articular ankle fracture. This supports the concept that posterior malleolus fractures associated with distal third tibial shaft fractures are likely the result of a rotational ankle injury. Interestingly, all four of the distal third tibial shaft spiral fractures without osseoligamentous injuries were located in the proximal aspect of this region. Additional analysis of this potential mechanism could further explain the nature of this injury pattern. As seen in previous studies, the majority of patients in our cohort had a low energy mechanism of energy [5]. A limitation of our study is the relatively small sample size of patients with distal one-third spiral tibial shaft
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Arch Orthop Trauma Surg (2014) 134:1661–1666
Fig. 3 Anteroposterior (a) and lateral (b) radiographs as well as sagittal (c) and axial (d) CT images of a distal third spiral tibial shaft fracture with no obvious articular ankle fracture. Sagittal (e) and axial
Distal third spiral tibial shaft fractures n=25
Ankle fracture identified on CT n=14
Ankle fracture identified on XR n=7
Underwent MRI n = 11 Ankle fracture identified on MRI n=7
No ankle fracture n=4
Fig. 4 Flow diagram illustrating the process and results of the imaging protocol for distal third spiral tibial shaft fractures
fractures. However, the incidence of ipsilateral ankle injuries as detected by CT in our study was similar to those previously reported [5–7], suggesting our cohort is representative
1665
(f) MR imaging reveals a posterior malleolus fracture. Postoperative anteroposterior (i) and lateral (j) radiographs demonstrating 2.7 mm interfragmentary screws stabilizing the posterior malleolus fracture
of other larger groups. An additional limitation is that only one fellowship-trained musculoskeletal radiologist read the 1.5T MRIs for evidence of osseous and ligamentous damage. Additional radiologist readers and the use of a stronger magnet could have provided more reliable results and increased our ability to detect a combined injury. However, given the similarity in incidences between our findings that those of Hou et al. [4], as well as the known sensitivity and specificity of MRI for visualizing ankle ligaments such as the PITFL and AITFL [14, 15], we believe our results are valid. In summary, we found that changing our distal one-third spiral tibia fracture imaging protocol increased the number of identified ipsilateral ankle fractures by 50 %. With the inclusion of MRI, we found an 84 % incidence of concomitant ankle fractures with distal third spiral tibia fractures. Recognition of these injuries is important as it can often alter surgical treatment and postoperative rehabilitation.
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1666 Conflict of interest No conflicts of interest declared for all authors regarding this manuscript.
References 1. Bo¨stman OM (1988) Displaced malleolar fractures associated with spiral fractures of the tibial shaft. Clin Orthop Relat Res 228:202–207 2. Lonner JH, Jupiter JB, Healy WL (1993) Ipsilateral tibia and ankle fractures. J Orthop Trauma 7:130–137 3. Stuermer EK, Stuermer KM (2008) Tibial shaft fracture and ankle joint injury. J Orthop Trauma 22:107–112 4. Hou Z, Zhang Q, Zhang Y et al (2009) A occult and regular combination injury: the posterior malleolar fracture associated with spiral tibial shaft fracture. J Trauma 66:1385–1390 5. Boraiah S, Gardner MJ, Helfet DL, Lorich DG (2008) High association of posterior malleolus fractures with spiral distal tibial fractures. Clin Orthop Relat Res 466:1692–1698 6. Purnell GJ, Glass ER, Altman DT et al (2011) Results of a computed tomography protocol evaluating distal third tibial shaft fractures to assess noncontiguous malleolar fractures. J Trauma 71:163–168 7. Schottel PC, Berkes MB, Little MTM et al (2014) Predictive radiographic markers for concomitant ipsilateral ankle injuries in tibial shaft fractures. J Orthop Trauma 28:103–107
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Arch Orthop Trauma Surg (2014) 134:1661–1666 8. Berkes MB, Little MTM, Lazaro LE et al (2013) Articular congruity is associated with short-term clinical outcomes of operatively treated SER IV ankle fractures. J Bone Joint Surg Am 95:1769–1775 9. Kukkonen J, Heikkila¨ JT, Kyyro¨nen T et al (2006) Posterior malleolar fracture is often associated with spiral tibial diaphyseal fracture: a retrospective study. J Trauma 60:1058–1060 10. Lauge-Hansen N (1954) Fractures of the ankle. III Genetic roentgenologic diagnosis of fractures of the ankle. Am J Roentgenol Radium Ther Nucl Med 71:456–471 11. Lauge-Hansen N (1950) Fractures of the ankle. II Combined experimental-surgical and experimental-roentgenologic investigations. Arch Surg 60:957–985 12. Georgiadis GM, Ebraheim NA, Hoeflinger MJ (1996) Displacement of the posterior malleolus during intramedullary tibial nailing. J Trauma 41:1056–1058 13. Konrath G, Moed BR, Watson JT et al (1997) Intramedullary nailing of unstable diaphyseal fractures of the tibia with distal intraarticular involvement. J Orthop Trauma 11:200–205 14. Takao M, Ochi M, Oae K et al (2003) Diagnosis of a tear of the tibiofibular syndesmosis. The role of arthroscopy of the ankle. J Bone Joint Surg Br 85:324–329 15. Vogl TJ, Hochmuth K, Diebold T et al (1997) Magnetic resonance imaging in the diagnosis of acute injured distal tibiofibular syndesmosis. Invest Radiol 32:401–409
ORTHOPAEDIC SURGERY
Ankle injuries in distal tibial spiral shaft fractures: results from an institutional change in imaging protocol Stephen J. Warner • Patrick C. Schottel Matthew R. Garner • David L. Helfet • Dean G. Lorich
•
Received: 24 July 2014 / Published online: 22 October 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Introduction Posterior malleolus and other articular ankle injuries are known to concomitantly occur with tibial shaft fractures, especially spiral fractures of the distal one-third diaphysis. Due to our heightened awareness of this combined injury, our department instituted a new preoperative ankle imaging protocol for all distal one-third spiral tibia shaft fractures. The purpose of this study was to evaluate the effectiveness of an imaging protocol involving radiographs, CT and magnetic resonance imaging (MRI) in a distal one-third spiral tibia fracture cohort. Materials and methods All operatively treated patients with a spiral distal one-third tibial shaft fracture from February 2012 to March 2013 underwent a standardized ankle imaging protocol. Patients had preoperative orthogonal ankle radiographs as well as a CT scan of the tibia that included the ankle. All ankle imaging was scrutinized for evidence of an ankle injury. If no ankle fracture was identified, patients would then undergo an ankle MRI. Results Twenty-five patients met the inclusion and exclusion criteria for this study. Concomitant osseous ankle injuries were identified by radiograph and CT in 56 % (14/ 25) of cases. The remaining 44 % (11/25) of patients had no evidence of a combined injury by radiograph or CT and therefore underwent an MRI. Of the MRI cohort, 64 % (7/ 11) were found to have an occult ankle fracture. The S. J. Warner (&) P. C. Schottel M. R. Garner Orthopaedic Trauma Service, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA e-mail: [email protected] D. L. Helfet D. G. Lorich Orthopaedic Trauma Service, Hospital for Special Surgery and Weill Cornell Medical College, New York Presbyterian Hospital, New York, NY, USA
overall incidence of a combined injury using our protocol was 84 % (21/25). Identification of an occult injury led to a change in management for all of these patients. Conclusions Concomitant ipsilateral ankle and distal onethird spiral tibial shaft fractures are more common than previously reported. Utilizing a new imaging protocol, we found that the incidence of this combined injury was 84 %. Recognition of the ankle fracture component in this tibial shaft cohort can be important as it may alter the surgical plan and postoperative management. Keywords Tibial shaft fracture Ankle fracture MRI Distal spiral shaft fracture
Introduction Posterior malleolus and other articular ankle injuries are known to concomitantly occur with tibial shaft fractures [1– 7]. Recent publications utilizing computed tomography (CT) have shown that the rate of this combined injury is higher than previously reported, with incidences ranging between 39 and 49 % [5–7]. Additionally, the location and pattern of the tibial shaft fracture has been found to be predictive of an ipsilateral ankle injury with combination injuries more often occurring in patients with a distal one-third diaphyseal location and spiral pattern [7]. Therefore, due to the high rate of combined injuries in this particular patient cohort, some authors have advocated that clinicians should have a low threshold for advanced imaging in order to diagnose an occult ankle fracture. However, despite the addition of CT to aid in recognition of an ipsilateral ankle fracture, other imaging modalities such as magnetic resonance imaging (MRI) that could potentially improve identification of these occult injuries have not been studied as extensively.
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Recognition of a concomitant ipsilateral ankle injury in a tibial shaft fracture is important as it can often alter the surgical plan and rehabilitation protocol. Failure to properly treat the ankle fracture component during operative tibial fixation may result in further displacement and subsequent ankle articular incongruity, which is known to affect patient outcomes [8]. Therefore, some authors have advocated for surgical fixation of posterior malleolus fractures prior to intramedullary fixation [5, 9]. Due to the potential impact this combined injury has on treatment and its high incidence, our Orthopaedic department instituted a new preoperative ankle imaging protocol for all distal onethird spiral tibial shaft fractures. The purpose of this study was to evaluate the effectiveness of an imaging protocol involving radiographs and CT with the addition of MRI in identifying an ipsilateral ankle injury in a distal one-third spiral tibial shaft fracture cohort. We hypothesized that the addition of MRI would increase our ability to recognize ankle osseoligamentous injuries and provide a more accurate estimate of their incidence.
Materials and methods All operatively treated patients with a spiral distal one-third tibial shaft fracture from February 2012 to March 2013 were initially identified from the senior surgeon’s surgical case logs. To determine if a fracture was in the distal onethird of the tibia shaft, the full length of the tibia was measured and divided into equal thirds; only spiral fractures of the distal third were included. Patients were included for analysis if they completed the standardized ankle imaging protocol described below. Patients less than 16 years of age and individuals with evidence of a prior ankle fracture and retained surgical implants were excluded. Approval for this study was obtained from our hospital’s Institutional Review Board. Prior to this study, our institution’s preoperative imaging evaluation of distal one-third spiral tibial shaft fractures included orthogonal tibia radiographs with additional dedicated ankle views. A CT scan without iodinated contrast of the tibia that included the ankle was also obtained in all cases to assess for a concomitant ankle fracture. All CT scans were performed on a 64-slice scanner utilizing 1.25 mm axial slices. For this study, all radiographic and CT ankle imaging was similarly obtained in every patient with a distal one-third spiral tibial shaft fracture and evaluated by an on-call orthopaedic resident for evidence of an articular ankle injury such as a posterior malleolus fracture (PMF), medial malleolus fracture (MMF) or other tibial plafond fracture variant. However, if no articular ankle fracture was identified, patients would then undergo a dedicated ankle MRI with an extremity coil. It should be
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Arch Orthop Trauma Surg (2014) 134:1661–1666
noted that the location and severity of the fibula fracture, when present, was not influential when deciding to obtain an MRI. All MRI scans were performed with a 1.5T GE scanner (General Electric, Milwaukee, Wisconsin). Preoperative ankle MRIs were retrospectively evaluated by a fellowship trained attending musculoskeletal radiologist for the presence of an articular ankle fracture or injury to ankle ligaments such as the anterior and posterior inferior tibiofibular ligaments (AITFL or PITFL) or deltoid ligament complex. Ligaments were considered intact or ruptured based on the presence and integrity of ligamentous fibers or disruption of fiber orientation and increased signal intensity within the substance of the ligament. Statistical analysis was performed for categorical data by comparing event frequencies between groups using Fisher’s exact test. A p value \0.05 was considered statistically significant.
Results During the study period, 26 patients underwent operative fixation of a distal one-third spiral tibia fracture. One patient had prior open reduction and internal fixation of the ipsilateral ankle and was excluded from the study. The remaining 25 patients underwent the standardized imaging protocol. The average patient age was 47 years (range 16–94) and 52 % (13/25) were male. Concomitant ankle injuries were identified by radiograph in 28 % (7/25) of cases (Fig. 1) and by CT in 56 % (14/25) of cases (Fig. 2). The remaining 44 % (11/25) of patients had no evidence of a combined injury by radiograph or CT and therefore underwent an MRI of the ipsilateral ankle. Of the eleven patients with no radiographic or CT evidence of an ankle injury, 64 % (7/11) were found to have an occult articular ankle fracture (Fig. 3). Five of these occult ankle fractures were of the posterior malleolus (71 %), one was of the medial malleolus (14 %), and one was an AITFL avulsion fracture (14 %). The overall incidence of a combined ipsilateral tibial shaft and ankle fracture using our protocol was 84 % (21/25). The addition of MRI to our imaging protocol resulted in a 50 % increase in the diagnosis of a combined injury (Fig. 4). To determine whether ankle fractures associated with distal third spiral tibia fractures were part of a larger ankle injury, similar to that described by Lauge-Hansen for rotational ankle fractures [10, 11], we analyzed the eleven MRIs obtained in this study for the presence of ligamentous ankle injuries. Five patients had a ligamentous injury, all of which were a ruptured AITFL in patients with a posterior malleolus fracture. Only one patient with an articular ankle fracture, an AITFL avulsion fracture, did
Arch Orthop Trauma Surg (2014) 134:1661–1666
1663
Fig. 1 Anteroposterior (a) and lateral (b) radiographs of a distal third spiral tibial shaft fracture demonstrating the presence of a posterior malleolus fracture. Postoperative anteroposterior (c) and lateral
(d) radiographs demonstrating 2.7 mm interfragmentary screws stabilizing the posterior malleolus fracture
not have a ligamentous injury. The four patients without an articular ankle fracture had no evidence of a ligamentous ankle injury. Within the distal third of the tibia, the four fractures without additional osseoligamentous ankle injuries were all in the proximal third of this region. In comparison, of the other 21 fractures with associated ankle injuries, 14/21 (67 %) were in the proximal third and 7/21 (33 %) were in the middle third of the included region. The difference in fracture location within the distal one-third tibial shaft between patients with or without a ligamentous ankle injury was not statistically significant (p = 0.29). One MRI was unable to be evaluated for ligamentous injury due to motion artifact.
PMF. They found an 88 % incidence of a combined injury using all three imaging modalities [4]. This high percentage of concomitant distal one-third spiral tibial shaft and ankle fractures is very similar to our findings in a North American patient cohort. Of note, the study by Hou et al. [4] did not include ankle injuries other than PMFs. Defining the true incidence of this combined injury and properly identifying these patients has important implications for surgical treatment and rehabilitation protocols. The majority of current recommendations are to internally fix the articular fragment with interfragmentary screws prior to intermedullary nail fixation of the diaphyseal fracture to avoid intraoperative displacement [6, 12, 13]. In addition, restriction of the patient’s post-operative weight bearing has also been suggested to prevent subsequent displacement and articular incongruity [5]. Our typical treatment protocol is to stabilize all PMFs with one or two anterior to posterior 2.7 mm interfragmentary screws and a small fragment (e.g. 2.4 mm) reconstruction plate for MMFs. We also typically prescribe 6 weeks of non-weight bearing for patients with an articular ankle fracture component. In our study cohort, 71 % of patients underwent fixation of their articular ankle fracture and all patients had modifications to their postoperative ability to bear weight. Despite these recommendations and our routine practice of stabilizing these injuries and restricting postoperative weight bearing, the influence on patient outcomes of recognizing and treating the associated ankle injury is unclear and further work in this area is necessary.
Discussion Our results demonstrate that detection of an ankle injury in patients with a distal one-third spiral tibial shaft fracture can be improved with use of a standardized imaging protocol involving radiographs, CT and MRI. Using this protocol, we found that the incidence of a combined injury was 84 %. This rate is higher than previous reports of 39–49 % that used only radiographs and CT [5–7]. To our knowledge only one previous study has used MRI to assist with identifying an occult ankle injury in patients with an ipsilateral distal one-third spiral tibia fracture. Hou et al. [4] performed a similar imaging protocol in 34 Chinese patients consisting of radiographs and CT followed by MRI for patients without evidence of a
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Arch Orthop Trauma Surg (2014) 134:1661–1666
Fig. 2 Anteroposterior (a) and lateral (b) radiographs of a distal third spiral tibial shaft fracture with no obvious articular ankle injury fracture. Sagittal (c) and axial (d) CT imaging reveals a posterior
malleolus fracture. Postoperative anteroposterior (e) and lateral (f) radiographs demonstrating a 2.7 mm interfragmentary screw stabilizing the posterior malleolus fracture
Importantly, our study is not advocating that MRIs be routinely obtained in this study population. Instead, our results emphasize the fact that this combined injury pattern is almost always present. Combining our findings with those of Hou et al. [4], 86 % (51/59) of distal one-third spiral tibial shaft fractures had evidence of a concomitant ankle fracture. If advanced imaging is not obtained due to limited facility resources or patient and surgeon preference, we therefore recommend heightened awareness of possible PMF or other distal tibial articular fragment displacement during operative fixation or postoperatively with weight bearing. Complaints of ankle pain in this patient cohort should not be ignored. As part of our MRI analysis by a musculoskeletal radiologist, we also sought to identify evidence for ankle ligamentous injuries that may be associated with distal third spiral tibia fractures. We suspected that ankle fractures
associated with distal third spiral tibia fractures were part of a larger ankle injury, similar to that described by LaugeHansen for rotational ankle injuries. Consistent with this, all patients with a posterior malleolus fracture also sustained an AITFL rupture. In contrast, no ligamentous injuries were identified in patients without an articular ankle fracture. This supports the concept that posterior malleolus fractures associated with distal third tibial shaft fractures are likely the result of a rotational ankle injury. Interestingly, all four of the distal third tibial shaft spiral fractures without osseoligamentous injuries were located in the proximal aspect of this region. Additional analysis of this potential mechanism could further explain the nature of this injury pattern. As seen in previous studies, the majority of patients in our cohort had a low energy mechanism of energy [5]. A limitation of our study is the relatively small sample size of patients with distal one-third spiral tibial shaft
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Arch Orthop Trauma Surg (2014) 134:1661–1666
Fig. 3 Anteroposterior (a) and lateral (b) radiographs as well as sagittal (c) and axial (d) CT images of a distal third spiral tibial shaft fracture with no obvious articular ankle fracture. Sagittal (e) and axial
Distal third spiral tibial shaft fractures n=25
Ankle fracture identified on CT n=14
Ankle fracture identified on XR n=7
Underwent MRI n = 11 Ankle fracture identified on MRI n=7
No ankle fracture n=4
Fig. 4 Flow diagram illustrating the process and results of the imaging protocol for distal third spiral tibial shaft fractures
fractures. However, the incidence of ipsilateral ankle injuries as detected by CT in our study was similar to those previously reported [5–7], suggesting our cohort is representative
1665
(f) MR imaging reveals a posterior malleolus fracture. Postoperative anteroposterior (i) and lateral (j) radiographs demonstrating 2.7 mm interfragmentary screws stabilizing the posterior malleolus fracture
of other larger groups. An additional limitation is that only one fellowship-trained musculoskeletal radiologist read the 1.5T MRIs for evidence of osseous and ligamentous damage. Additional radiologist readers and the use of a stronger magnet could have provided more reliable results and increased our ability to detect a combined injury. However, given the similarity in incidences between our findings that those of Hou et al. [4], as well as the known sensitivity and specificity of MRI for visualizing ankle ligaments such as the PITFL and AITFL [14, 15], we believe our results are valid. In summary, we found that changing our distal one-third spiral tibia fracture imaging protocol increased the number of identified ipsilateral ankle fractures by 50 %. With the inclusion of MRI, we found an 84 % incidence of concomitant ankle fractures with distal third spiral tibia fractures. Recognition of these injuries is important as it can often alter surgical treatment and postoperative rehabilitation.
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1666 Conflict of interest No conflicts of interest declared for all authors regarding this manuscript.
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