ORIGINAL ARTICLE
Entrapped Posteromedial Structures in Pilon Fractures Jonathan G. Eastman, MD,* Reza Firoozabadi, MD,† Stephen K. Benirschke, MD,† David P. Barei, MD,† and Robert P. Dunbar, MD†
Objectives: To analyze a patient cohort who sustained a tibial pilon fracture and report the incidence of interposed posteromedial soft tissue structures.
Design: Retrospective cohort review. Setting: Regional Level 1 Trauma Center. Patients/Participants: About 394 patients with 420 pilon frac-
cases, removal of the entrapped structure(s) may not be possible through the more commonly used anterolateral and anteromedial surgical approaches, and a separate posteromedial exposure may be required. Failure to recognize the presence of an interposed structure could lead to malreduction, impaired tendon function, neurovascular insult, and the need for further surgery. Key Words: pilon, entrapped structure, posteromedial
tures treated between January 2005 and November 2011.
Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Intervention: Each patient’s preoperative radiographs and com-
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puted tomography (CT) images were reviewed. The axial and reconstructed images were used in bone and soft tissue windows to identify any posteromedial soft tissue structures incarcerated within the fracture.
Main Outcome Measurements: Medical charts reviewed for the presence of preoperative neurologic deficit, separate posteromedial incision, and whether attending radiology CT interpretation noted the interposed structure. Results: 40 patients with 40 fractures (9.5%) had an entrapped posteromedial structure. The tibialis posterior tendon was interposed in 38/40 fractures (95%) and the posterior tibial neurovascular bundle in 4/40 fractures (10%). Preoperative neurologic deficit occurred in 5/40 patients (12%). A posteromedial incision was used in 11/40 fractures (27%). The attending radiology CT interpretation noted the interposed structure in 8/40 fractures (20%).
Conclusions: In addition to the osseous injuries, CT imaging can demonstrate the posteromedial soft tissue structures. In our series, the tibialis posterior tendon was commonly incarcerated. In some Accepted for publication November 21, 2013. From the *Department of Orthopaedic Surgery, Davis Medical Center, University of California, Sacramento, CA; and †Department of Orthopaedic Surgery and Sports Medicine, Harborview Medical Center, University of Washington, Seattle, WA. R. P. Dunbar is part of the speakers bureau/gives paid presentations for AO, receives research support as a PI from Smith & Nephew, receives other financial or material support from Innovision, Synthes, and Zimmer, is on the editorial board/governing board of Journal of Orthopaedics and Traumatology and OrthoInfo, and is a board member/committee appointment for the Orthopaedic Trauma Association. The remaining authors report no conflict of interest. Institutional Review Board (IRB) approval was obtained for this study. Presented in part at the Annual Meeting of the Orthopaedic Trauma Association, October 3–6, 2012, Minneapolis, MN, and as a podium presentation at the Annual Meeting of the American Academy of Orthopaedic Surgeons, March 19–23, 2013, Chicago, IL. Reprints: Jonathan G. Eastman, MD, Department of Orthopaedic Surgery, Davis Medical Center, University of California, 4860 Y St, Suite 3800, Sacramento, CA 95817 (e-mail: [email protected]). Copyright © 2013 by Lippincott Williams & Wilkins
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INTRODUCTION Tibial pilon fractures remain surgically challenging and have a substantial impact on the patient’s quality of life and function.1–4 The surgical goals of tibial pilon fracture management include anatomical articular reduction, restoration of axial alignment, and stable internal fixation while minimizing soft tissue complications. Although open reduction and internal fixation of these fractures, commonly performed as a staged procedure, is an accepted surgical treatment, the complex periarticular osseous fracture anatomy and often thin and traumatized overlying soft tissue envelope can make the satisfactory attainment of these goals difficult.5,6 The choice of the surgical exposures, the sequence of articular and extraarticular fracture fragment reduction, and the appropriate placement of fracture stabilizing implants requires a thorough understanding of the injury pattern.5–10 Pilon fractures have been shown to have several reproducible main fracture fragments including the anterolateral (Chaput) fragment, the posterolateral (Volkmann) fragment, and the medial malleolar fragment.11 The displacement that occurs between these major fracture fragments at the moment of injury may create space that allows for the intrusion and subsequent entrapment of one or more of the immediate adjacent musculotendinous or neurovascular structures as they course through the lower leg and proceed past the ankle and into the foot. Interposition can occur between the medial edge of the posterolateral Volkmann fragment and the posterior edge of the medial malleolar fragment. Uncorrected incarceration of some or all of the contents of the tarsal tunnel within the posteromedial fracture fragments would likely lead to fracture malreduction, impaired tendon excursion and function, tibial nerve dysfunction, and the need for further reconstructive surgeries. Recognition of this occurrence is critical and may require alteration of the surgical tactic, including choice of surgical exposure, the use of adjunctive exposures, and changing the timing of provisional or definitive surgery, among others. J Orthop Trauma Volume 28, Number 9, September 2014
J Orthop Trauma Volume 28, Number 9, September 2014
We have recently encountered several patients who sustained a tibial pilon fracture with entrapment of posteromedial soft tissue structures. To the best of our knowledge, there has been no series in the orthopaedic literature specifically reporting on this clinical scenario. The purposes of this article, therefore, were to highlight the incidence of interposed posteromedial soft tissue structures in the tibial pilon fractures and to describe the associated injury factors and associated clinical implications in a retrospectively reviewed cohort of patients.
PATIENTS AND METHODS After obtaining institutional review board (IRB) approval, a nearly 6-year review was performed from our prospectively collected trauma database at a regional Level 1 Trauma Center. This database has recorded all operatively managed fractures at our institution since 1989. Fractures are entered and coded according to the OTA/AO Fracture Classification System12 by orthopaedic trauma fellows trained in this classification system. Data are stored and manipulated using a commercially available software program (Microsoft Access). Inclusion criteria required skeletally maturity, a complete medical chart relative to their injury, adequate preoperative radiographic imaging, including a computed tomography (CT) scan, and to have had their definitive surgical procedure performed at the investigating institution. From January 1, 2005 through October 30, 2011, all skeletally mature patients older than 18 years of age who sustained an intraarticular fracture of the distal tibia were identified. This time period was chosen based on the integration of patient information into the electronic medical record database and the availability of patient’s imaging for review through the picture archiving and communication system. The search was conducted by searching for fractures classified as either OTA/AO 43-B or C type injuries, and it provided 394 patients with 420 intraarticular distal tibia fractures that were included in the study. The medical records including initial consultation and physical examination documentation, preoperative radiographs and CT scans, and the attending surgeon operative reports were reviewed for each patient. All preoperative imaging was reviewed including radiographs of the tibia and ankle, as well as CT scans obtained before definitive internal fixation. The axial images and the sagittal and coronal reconstructed images were reviewed in detail using both bony and soft tissue windows to identify an interposed posteromedial soft tissue structure. Two authors, both orthopaedic trauma fellows, reviewed all imaging. In order for a structure to be accepted as entrapped, both authors had to agree. Entrapment was defined as the presence of the tibialis posterior tendon, flexor digitorum longus tendon, the posterior tibial neurovascular bundle, or the flexor hallucis longus tendon completely interposed between the 2 main fracture fragments (Figs. 1, 2). The presence of any neurologic deficit of the foot and ankle was noted. The operative reports were reviewed to see whether a separate formal posteromedial incision was used in any patient noted to have an interposed soft tissue structure. The final attending radiology interpretation was also reviewed to verify Ó 2013 Lippincott Williams & Wilkins
Pilon Fractures
whether the presence of an interposed soft tissue structure was commented on.
RESULTS Between January 1, 2005 and October 30, 2011, 394 patients with 420 pilon fractures were identified. From this patient population, there were 40 patients with 40 fractures (9.5%) with an entrapped posteromedial soft tissue structure. There were 27 men and 13 women. The mechanism of injury was a fall from height in 24 of 40 patients (60%), motor vehicle accident in 9 of 40 patients (22.5%), motorcycle collision in 5 of 40 patients (12.5%), a gun shot wound in 1 of 40 patients (2.5%), and a plane crash in 1 of 40 patients (2.5%). About 10 of 40 fractures (25%) were open injuries. These were classified by Gustilo and Anderson as type II in 5 of 10 patients (50%), type IIIA in 4 of 10 patients (40%), and type IIIB in 1 of 10 patients (10%). The OTA/AO classification showed 26 fractures (65%) as 43-C3 injuries, 12 fractures (30%) as 43-C2, and 2 fractures (5%) as 43-C1 injuries. The Injury Severity Score for this cohort of patients averaged 15 (9–27). 32% of the patients were considered multiply injured with an Injury Severity Score .17. The CT scans were taken before any surgical intervention in 6 of 40 fractures (15%) and were performed after initial spanning external fixation with or without fibular plating in 34 of 40 fractures (85%). All 6 patients who underwent a CT scan before spanning external fixation were transferred from an outside institution with the CT already performed. In review of clinical notes, 3 of the 6 patients had an additional CT scan after the initial spanning external fixation procedure to further delineate the osseous injury and fracture morphology. Without any formal removal attempts during the initial temporary spanning external fixation procedure, 2 of these 3 patients still had the interposed structure present, whereas 1 of 3 patients no longer had the interposed structure present. Of the patients with entrapped structures, the tibialis posterior tendon was interposed in 38 of 40 fractures (95%), the flexor digitorum longus tendons in 9 of 40 fractures (22%), the posteromedial neurovascular bundle in 4 of 40 fractures (10%), and the flexor hallucis longus in 1 fracture (2.5%). A neurologic deficit with detectable plantar dysesthesia was present in 5 of 40 patients (12%). 2 of these 5 patients had preoperative neurologic dysfunction with accompanying entrapment seen on the CT scan, whereas 3 of these 5 patients had some degree of plantar dysesthesia without evidence of posterior tibial neurovascular bundle seen on the CT scan. A separate posteromedial approach was used in 11 of 40 fractures (27%). From the review of the operative reports, 5 of these 11 patients (45%) underwent a posteromedial approach because of the fracture pattern, without any specific mention of the entrapped structure that was subsequently noted at the time of surgery. The remaining 6 of the 11 patients (55%) required the approach specifically to address the interposed structure. About 2 of these 6 patients had preexisting dysesthesia with accompanying CT evident entrapment of the neurovascular bundle, and the posteromedial approach was performed first. The other 4 of these 6 patients initially had a standard anterolateral approach. In each case, the fracture could not be reduced, www.jorthotrauma.com |
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FIGURE 1. Anteroposterior radiograph (A) with the corresponding axial CT images in bone windows (B) and soft tissue windows (C) of a left pilon fracture showing complete interposition of the tibialis posterior tendon between the medial malleolar and posterolateral fracture fragments. The flexor digitorum tendon is immediately posteromedial to the tibialis posterior tendon.
and the interposed structure required a separate posteromedial incision for removal, reduction, and fixation. The final attending radiology read of the CT scan commented on the interposed structure in only 8 of the 40 fractures (20%).
DISCUSSION Pilon fractures are often the result of a high-energy injury resulting in a significant injury to the distal tibia and fibula. These fractures have been shown to have reproducible main fracture fragments that are present with or without variation in each injury.11,13 When there is adequate displacement between any of these fracture segments, surrounding soft tissue structures can become interposed. Although not in tibial pilon fractures, several prior series have shown the posteromedial musculotendinous and neurovascular structures of the ankle as the reason a reduction was unobtainable. The tibialis posterior tendon has previously been noted as the cause in irreducible ankle fracture dislocations14–18 and in irreducible lateral subtalar dislocations.19–21 The flexor digitorum longus tendon and the posteromedial neurovascular bundle have also been documented to impede reduction in complex ankle injuries.22–24 Through our retrospective review of a large series of patients who sustained a pilon fracture, nearly 10% of the patients had posteromedial soft tissue structure interposition within the posteromedial fracture site. The tibialis posterior tendon was the most commonly interposed structure in our series, but any or even multiple posteromedial structures may be entrapped in one fracture. Before looking at the radiographs or CT scans, a detailed physical examination can alert a surgeon to an entrapped structure. The tibialis posterior tendon was the most common interposed posteromedial structure noted in this cohort. After the initial spanning external fixation procedure, the flexor digitorum longus and flexor hallucis longus tendons can be tested for motion. With inhibited toe flexion or extension on physical examination, the presence of tendon entrapment should be considered. Unfortunately, with
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the ankle joint rendered immobile by the external fixator, the excursion of the tibialis posterior cannot be checked. This fact makes it even more important to carefully examine all the available imaging to ensure no structure is entrapped. Similarly, the course, divisions, and anatomic variations of the tibial nerve have been studied extensively.25,26 Applying this knowledge allows the surgeons to understand how proximal injury clinically manifests distally in the foot. Of the patients in our series with an entrapped structure, 10% of the patients had the posterior tibial neurovascular bundle trapped in the fracture site. This can cause a wide range of neurologic impairment but commonly produces some degree of plantar dysesthesia. The patients with tibial nerve dysfunction had the deficit since the time of injury. Although there is a theoretical possibility of the neurovascular bundle being between 2 fracture fragments and then being pinched as the limb is being distracted because of ligamentotaxis, no patients in this series developed neurologic dysfunction after the placement of spanning external fixation. Once definitive fixation was performed and the nerve was ensured to be free of the fracture site, the neurologic examination improved in all patients. By 6 months postoperatively, all patients had improved substantially but still had some degree of altered or plantar hypersensitivity. By clinically identifying tibial nerve dysfunction early, surgeons can look for evidence of entrapment on advanced imaging, correlate this with the physical examination, and develop an appropriate corrective surgical plan that will ensure no residual interposition. The OTA/AO classification system has evolved as a standardized and commonly accepted method of describing skeletal injuries and has been specifically investigated for fractures of the distal tibia.12,27 In our series, the OTA/AO classification showed 26 fractures (65%) as 43-C3 injuries, 12 fractures (30%) as 43-C2, and 2 fractures (5%) as 43-C1 injuries. Overall, the incidence of interposition was higher in the 43-C3 injuries, which are more typically associated with a higher energy injury mechanism. The increased degree of force typically produces more osseous damage and Ó 2013 Lippincott Williams & Wilkins
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FIGURE 2. Anteroposterior ankle radiograph (A) with the accompanying axial CT imaging in bone windows (B) and soft tissue windows (C) of a left pilon fracture demonstrating complete entrapment of the posterior tibial neurovascular bundle within the fracture site. The tibialis posterior and flexor digitorum longus tendons are seen anterior and medial.
associated fracture displacement that may allow the adjacent posteromedial tissues to become interposed. Although less common, care should be taken to not overlook the lower energy injury patterns as entrapment may also occur. Multiplanar radiographs of the ankle demonstrate the injury pattern and provide initial insight into surgical planning. Full-length radiographs of the tibia and fibula depict fracture extension of the pilon fracture into the metaphysis and diaphysis, as well as associated proximal fibula fractures. CT imaging builds from this initial information and provides more specific details of the injury. The axial sequences and the sagittal and coronal reconstructions delineate the individual fracture fragments, clarify metaphyseal and diaphyseal involvement, and show the presence and location of articular impaction. Tornetta and Gorup28 showed that the CT scan added additional information 82% of the time and noted a 64% rate of change in the operative plan after incorporating the findings of the CT scan. Although this was primarily focused on the bony anatomy and surgical approaches, CT imaging can also help identify and diagnose tendon pathology around the ankle.29–31 Taking note of an interposed structure could change the surgical approach chosen. More specifically, it could deem an additional posteromedial approach necessary to address the entrapped tendon or nerve, if it cannot be properly addressed through an anteromedial or anterolateral approach. In our series, 11 of 40 patients (27%) with an entrapped structure required a separate posteromedial approach. If needed, a posteromedial approach allows for direct visualization of the entrapped structure in addition to the reduction of the medial malleolar fracture component (Fig. 3). Further temporary or definitive fixation may also be performed through the same exposure (Fig. 4). Failure to recognize the presence of an interposed structure could lead to a malreduction, impaired tendon function, neurovascular insult, and the need for further surgery. Due to a number of factors, missed or delayed diagnosis of orthopaedic injuries in polytrauma patients unfortunately occurs. A recent literature review showed a wide spread distribution of missed injuries and delayed diagnoses Ó 2013 Lippincott Williams & Wilkins
incidence rates from 1.3% to 39%. Up to 22.3% of patients were found to have clinically significant injuries.32 Although not commonly thought of as a missed injury, not identifying the interposition of a structure can also potentially have significant clinical ramifications. Due to the retrospective nature of our series, we could not investigate whether the attending surgeon specifically took notice of the interposed structure before definitive fixation. One variable that we were able to look at was whether or not the attending radiologist commented on the presence of an interposed structure. In our series, only 20% of the patients with an entrapped structure were identified in the radiologist’s interpretation of the CT scan. With the often markedly impressive bony injuries seen with pilon fractures, the surrounding posteromedial soft
FIGURE 3. Clinical photograph showing complete interposition of the tibialis posterior tendon, which was irreducible from the anterolateral surgical approach. This separate posteromedial exposure was necessary to remove the tendon from the fracture site to obtain appropriate reduction. Editor’s note: A color image accompanies the online version of this article. www.jorthotrauma.com |
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REFERENCES
FIGURE 4. Clinical photograph showing extraction of tibialis posterior tendon, reduction, and internal plate fixation through posteromedial approach. Editor’s note: A color image accompanies the online version of this article.
tissues can get overlooked. In an attempt to provide the best care possible, we can educate ourselves and our radiology colleagues to always study the surrounding soft tissue structures and identify any pathology present. The weaknesses of this study include it being a retrospective study, and it is therefore subject to all biases and inherent limitations thereof. The operative reports and clinical notes were not documented in standardized fashion or with specific data entry protocols. Some potentially pertinent details from the surgical procedures or the perioperative period could have not been dictated or noted. As seen in this cohort, entrapped structures in pilon fractures are not overly common. Although this represents a large series of patients, larger numbers of patients with these injuries are needed to further assess the incidence and clinical impact of this scenario. In conclusion, pilon fractures are complex injuries to take care of for numerous reasons, and soft tissue management is paramount in the treatment algorithm. Careful attention must be paid to preoperative radiographs and CT imaging to identify the involved fracture fragments and articular impaction. In addition to the osseous injury, CT images can demonstrate whether nearby soft tissue structures are entrapped within the fracture. The presence of an interposed structure is more common in the higher energy and more complicated fracture patterns; however, it is also present in less complex injuries as well. The tibialis posterior tendon and posterior tibial neurovascular bundle were the 2 most commonly interposed structures, but multiple structures may be entrapped in the fracture site. Addressing an entrapped posteromedial structure may be possible working posteriorly through an anteromedial or anterolateral surgical approach. In some cases, this may prove to not be possible, and a separate posteromedial approach may be required. Each pilon fracture and injury to the soft tissue envelope is unique, and individualizing treatment is paramount. Taking account of all the involved factors will help achieve the optimal surgical, functional, and clinical outcome in these complex injuries.
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1. Crist BD, Khazzam M, Murtha YM, et al. Pilon fractures: advances in surgical management. J Am Acad Orthop Surg. 2011;19:612–622. 2. Wyrsch B, McFerran MA, McAndrew M, et al. Operative treatment of fractures of the tibial plafond: a randomized, prospective study. J Bone Joint Surg Am. 1996;78:1646–1657. 3. Williams TM, Nepola JV, DeCoster TA, et al. Factors affecting outcome in tibial plafond fractures. Clin Orthop Relat Res. 2004;423:93–98. 4. Pollack AN, McCarthy ML, Bess RS, et al. Outcomes after treatment of high-energy tibial pilon fractures. J Bone Joint Surg Am. 2003;85-A: 1893–1900. 5. Sirkin M, Sanders R, DiPasquale T, et al. A staged protocol for soft tissue management in the treatment of complex pilon fractures. J Orthop Trauma. 1999;13:92–97. 6. Patterson MJ, Cole JD. Two-staged delayed open reduction and internal fixation of severe pilon fractures. J Orthop Trauma. 1999;13:85–91. 7. Watson JT, Moed BR, Karges DE, et al. Pilon fractures: treatment protocol based on severity of soft tissue injury. Clin Orthop Relat Res. 2000; 375:78–90. 8. Gardner MJ, Mehta S, Barei DP, et al. Treatment protocol for open AO/ OTA type C3 pilon fractures with segmental bone loss. J Orthop Trauma. 2008;22:451–457. 9. Dillin L, Slabaugh P. Delayed wound healing, infection, and nonunion following open reduction and internal fixation of tibial plafond injuries. J Trauma. 1986;26:1116–1119. 10. McFerran MA, Smith SW, Boulas HJ, et al. Complications encountered in the treatment of pilon fractures. J Orthop Trauma. 1992;6: 195–200. 11. Topliss CJ, Jackson M, Atkins RM. Anatomy of pilon fractures of the distal tibia. J Bone Joint Surg Br. 2005;87:692–697. 12. Muller ME, Nazarian S, Koch P, et al. The Comprehensive Classification of Fractures of Long Bones. Berlin, Germany: Springer-Verlag; 1990. 13. Bucholz RW, Heckman JD, Court-Brown CW, et al. Rockwood and Green’s Fractures in Adults. 6th ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2010. 14. Anderson JG, Hansen ST. Fracture-dislocation of the ankle with posterior tibial tendon entrapment within the tibiofibular interosseous space: a case report of a late diagnosis. Foot Ankle Int. 1996;17:114–118. 15. Walker RH, Farris C. Irreducible fracture-dislocations of the ankle associated with interposition of the tibialis posterior tendon: case report and review of the literature of a specific ankle fracture syndrome. Clin Orthop Relat Res. 1981;160:212–216. 16. Pietu G, Letenneur J, Huguet D. Dislocation of the tendon of the posterior tibial muscle and fracture of the lateral malleolus. Another equivalent of bimalleolar fracture? Rev Chir Orthop Reparatrice Appar Mot. 1993; 79:127–130. 17. Ermis MN, Yagmurlu MF, Kilinc AS, et al. Irreducible fracture dislocation of the ankle caused by tibialis posterior tendon interposition. J Foot Ankle Surg. 2010;49:166–171. 18. Hsiao KC, Tu CH. Irreducible fracture-dislocation of the ankle: report of two cases. J Formos Med Assoc. 1994;93(suppl 3):S161–S165. 19. Woodruff MJ, Brown JN, Mountney J. A mechanism for entrapment of the tibialis posterior tendon in lateral subtalar dislocation. Injury. 1996; 27:193–194. 20. de Palma L, Santucci A, Marinelli M. Irreducible isolated subtalar dislocation: a case report. Foot Ankle Int. 2008;29:523–526. 21. Waldrop J, Ebraheim NA, Shapiro P, et al. Anatomical considerations of posterior tibialis tendon entrapment in irreducible lateral subtalar dislocation. Foot Ankle. 1992;13:458–461. 22. Meinhard BP, Girgis I, Moriarty RV. Irreducible talar dislocation with entrapment by the tibialis posterior and the flexor digitorum longus tendons. A case report. Clin Orthop Relat Res. 1993;286: 222–224. 23. Pankovich AM. Fracture-dislocation of the ankle. Trapping of the postero-medical ankle tendons and neurovascular bundle in the tibiofibular interosseous space: a case report. J Trauma. 1976;16:927–929. 24. Coonrad RW, Bugg EI. Trapping of the posterior tibial tendon and interposition of the soft tissue in severe fractures about the ankle joint. J Bone Joint Surg Am. 1954;36A:744–750. 25. Lumsden DB, Schon LC, Easly ME, et al. Topography of the distal tibial nerve and its branches. Foot Ankle Int. 2003;24:696–700.
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J Orthop Trauma Volume 28, Number 9, September 2014 26. Davis TJ, Schon LC. Branches of the tibial nerve: anatomic variations. Foot Ankle Int. 1995;16:21–29. 27. Martin JS, Marsh JL, Bonar SK, et al. Assessment of the AO/ASIF fracture classification for the distal tibia. J Orthop Trauma. 1997;11:477–483. 28. Tornetta P III, Gorup J. Axial computed tomography of pilon fractures. Clin Orthop Relat Res. 1996;323:273–276. 29. Rosenberg ZS, Feldman F, Singson RD, et al. Ankle tendons: evaluation with CT. Radiology. 1988;166:221–226.
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Entrapped Posteromedial Structures in Pilon Fractures Jonathan G. Eastman, MD,* Reza Firoozabadi, MD,† Stephen K. Benirschke, MD,† David P. Barei, MD,† and Robert P. Dunbar, MD†
Objectives: To analyze a patient cohort who sustained a tibial pilon fracture and report the incidence of interposed posteromedial soft tissue structures.
Design: Retrospective cohort review. Setting: Regional Level 1 Trauma Center. Patients/Participants: About 394 patients with 420 pilon frac-
cases, removal of the entrapped structure(s) may not be possible through the more commonly used anterolateral and anteromedial surgical approaches, and a separate posteromedial exposure may be required. Failure to recognize the presence of an interposed structure could lead to malreduction, impaired tendon function, neurovascular insult, and the need for further surgery. Key Words: pilon, entrapped structure, posteromedial
tures treated between January 2005 and November 2011.
Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Intervention: Each patient’s preoperative radiographs and com-
(J Orthop Trauma 2014;28:528–533)
puted tomography (CT) images were reviewed. The axial and reconstructed images were used in bone and soft tissue windows to identify any posteromedial soft tissue structures incarcerated within the fracture.
Main Outcome Measurements: Medical charts reviewed for the presence of preoperative neurologic deficit, separate posteromedial incision, and whether attending radiology CT interpretation noted the interposed structure. Results: 40 patients with 40 fractures (9.5%) had an entrapped posteromedial structure. The tibialis posterior tendon was interposed in 38/40 fractures (95%) and the posterior tibial neurovascular bundle in 4/40 fractures (10%). Preoperative neurologic deficit occurred in 5/40 patients (12%). A posteromedial incision was used in 11/40 fractures (27%). The attending radiology CT interpretation noted the interposed structure in 8/40 fractures (20%).
Conclusions: In addition to the osseous injuries, CT imaging can demonstrate the posteromedial soft tissue structures. In our series, the tibialis posterior tendon was commonly incarcerated. In some Accepted for publication November 21, 2013. From the *Department of Orthopaedic Surgery, Davis Medical Center, University of California, Sacramento, CA; and †Department of Orthopaedic Surgery and Sports Medicine, Harborview Medical Center, University of Washington, Seattle, WA. R. P. Dunbar is part of the speakers bureau/gives paid presentations for AO, receives research support as a PI from Smith & Nephew, receives other financial or material support from Innovision, Synthes, and Zimmer, is on the editorial board/governing board of Journal of Orthopaedics and Traumatology and OrthoInfo, and is a board member/committee appointment for the Orthopaedic Trauma Association. The remaining authors report no conflict of interest. Institutional Review Board (IRB) approval was obtained for this study. Presented in part at the Annual Meeting of the Orthopaedic Trauma Association, October 3–6, 2012, Minneapolis, MN, and as a podium presentation at the Annual Meeting of the American Academy of Orthopaedic Surgeons, March 19–23, 2013, Chicago, IL. Reprints: Jonathan G. Eastman, MD, Department of Orthopaedic Surgery, Davis Medical Center, University of California, 4860 Y St, Suite 3800, Sacramento, CA 95817 (e-mail: [email protected]). Copyright © 2013 by Lippincott Williams & Wilkins
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INTRODUCTION Tibial pilon fractures remain surgically challenging and have a substantial impact on the patient’s quality of life and function.1–4 The surgical goals of tibial pilon fracture management include anatomical articular reduction, restoration of axial alignment, and stable internal fixation while minimizing soft tissue complications. Although open reduction and internal fixation of these fractures, commonly performed as a staged procedure, is an accepted surgical treatment, the complex periarticular osseous fracture anatomy and often thin and traumatized overlying soft tissue envelope can make the satisfactory attainment of these goals difficult.5,6 The choice of the surgical exposures, the sequence of articular and extraarticular fracture fragment reduction, and the appropriate placement of fracture stabilizing implants requires a thorough understanding of the injury pattern.5–10 Pilon fractures have been shown to have several reproducible main fracture fragments including the anterolateral (Chaput) fragment, the posterolateral (Volkmann) fragment, and the medial malleolar fragment.11 The displacement that occurs between these major fracture fragments at the moment of injury may create space that allows for the intrusion and subsequent entrapment of one or more of the immediate adjacent musculotendinous or neurovascular structures as they course through the lower leg and proceed past the ankle and into the foot. Interposition can occur between the medial edge of the posterolateral Volkmann fragment and the posterior edge of the medial malleolar fragment. Uncorrected incarceration of some or all of the contents of the tarsal tunnel within the posteromedial fracture fragments would likely lead to fracture malreduction, impaired tendon excursion and function, tibial nerve dysfunction, and the need for further reconstructive surgeries. Recognition of this occurrence is critical and may require alteration of the surgical tactic, including choice of surgical exposure, the use of adjunctive exposures, and changing the timing of provisional or definitive surgery, among others. J Orthop Trauma Volume 28, Number 9, September 2014
J Orthop Trauma Volume 28, Number 9, September 2014
We have recently encountered several patients who sustained a tibial pilon fracture with entrapment of posteromedial soft tissue structures. To the best of our knowledge, there has been no series in the orthopaedic literature specifically reporting on this clinical scenario. The purposes of this article, therefore, were to highlight the incidence of interposed posteromedial soft tissue structures in the tibial pilon fractures and to describe the associated injury factors and associated clinical implications in a retrospectively reviewed cohort of patients.
PATIENTS AND METHODS After obtaining institutional review board (IRB) approval, a nearly 6-year review was performed from our prospectively collected trauma database at a regional Level 1 Trauma Center. This database has recorded all operatively managed fractures at our institution since 1989. Fractures are entered and coded according to the OTA/AO Fracture Classification System12 by orthopaedic trauma fellows trained in this classification system. Data are stored and manipulated using a commercially available software program (Microsoft Access). Inclusion criteria required skeletally maturity, a complete medical chart relative to their injury, adequate preoperative radiographic imaging, including a computed tomography (CT) scan, and to have had their definitive surgical procedure performed at the investigating institution. From January 1, 2005 through October 30, 2011, all skeletally mature patients older than 18 years of age who sustained an intraarticular fracture of the distal tibia were identified. This time period was chosen based on the integration of patient information into the electronic medical record database and the availability of patient’s imaging for review through the picture archiving and communication system. The search was conducted by searching for fractures classified as either OTA/AO 43-B or C type injuries, and it provided 394 patients with 420 intraarticular distal tibia fractures that were included in the study. The medical records including initial consultation and physical examination documentation, preoperative radiographs and CT scans, and the attending surgeon operative reports were reviewed for each patient. All preoperative imaging was reviewed including radiographs of the tibia and ankle, as well as CT scans obtained before definitive internal fixation. The axial images and the sagittal and coronal reconstructed images were reviewed in detail using both bony and soft tissue windows to identify an interposed posteromedial soft tissue structure. Two authors, both orthopaedic trauma fellows, reviewed all imaging. In order for a structure to be accepted as entrapped, both authors had to agree. Entrapment was defined as the presence of the tibialis posterior tendon, flexor digitorum longus tendon, the posterior tibial neurovascular bundle, or the flexor hallucis longus tendon completely interposed between the 2 main fracture fragments (Figs. 1, 2). The presence of any neurologic deficit of the foot and ankle was noted. The operative reports were reviewed to see whether a separate formal posteromedial incision was used in any patient noted to have an interposed soft tissue structure. The final attending radiology interpretation was also reviewed to verify Ó 2013 Lippincott Williams & Wilkins
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whether the presence of an interposed soft tissue structure was commented on.
RESULTS Between January 1, 2005 and October 30, 2011, 394 patients with 420 pilon fractures were identified. From this patient population, there were 40 patients with 40 fractures (9.5%) with an entrapped posteromedial soft tissue structure. There were 27 men and 13 women. The mechanism of injury was a fall from height in 24 of 40 patients (60%), motor vehicle accident in 9 of 40 patients (22.5%), motorcycle collision in 5 of 40 patients (12.5%), a gun shot wound in 1 of 40 patients (2.5%), and a plane crash in 1 of 40 patients (2.5%). About 10 of 40 fractures (25%) were open injuries. These were classified by Gustilo and Anderson as type II in 5 of 10 patients (50%), type IIIA in 4 of 10 patients (40%), and type IIIB in 1 of 10 patients (10%). The OTA/AO classification showed 26 fractures (65%) as 43-C3 injuries, 12 fractures (30%) as 43-C2, and 2 fractures (5%) as 43-C1 injuries. The Injury Severity Score for this cohort of patients averaged 15 (9–27). 32% of the patients were considered multiply injured with an Injury Severity Score .17. The CT scans were taken before any surgical intervention in 6 of 40 fractures (15%) and were performed after initial spanning external fixation with or without fibular plating in 34 of 40 fractures (85%). All 6 patients who underwent a CT scan before spanning external fixation were transferred from an outside institution with the CT already performed. In review of clinical notes, 3 of the 6 patients had an additional CT scan after the initial spanning external fixation procedure to further delineate the osseous injury and fracture morphology. Without any formal removal attempts during the initial temporary spanning external fixation procedure, 2 of these 3 patients still had the interposed structure present, whereas 1 of 3 patients no longer had the interposed structure present. Of the patients with entrapped structures, the tibialis posterior tendon was interposed in 38 of 40 fractures (95%), the flexor digitorum longus tendons in 9 of 40 fractures (22%), the posteromedial neurovascular bundle in 4 of 40 fractures (10%), and the flexor hallucis longus in 1 fracture (2.5%). A neurologic deficit with detectable plantar dysesthesia was present in 5 of 40 patients (12%). 2 of these 5 patients had preoperative neurologic dysfunction with accompanying entrapment seen on the CT scan, whereas 3 of these 5 patients had some degree of plantar dysesthesia without evidence of posterior tibial neurovascular bundle seen on the CT scan. A separate posteromedial approach was used in 11 of 40 fractures (27%). From the review of the operative reports, 5 of these 11 patients (45%) underwent a posteromedial approach because of the fracture pattern, without any specific mention of the entrapped structure that was subsequently noted at the time of surgery. The remaining 6 of the 11 patients (55%) required the approach specifically to address the interposed structure. About 2 of these 6 patients had preexisting dysesthesia with accompanying CT evident entrapment of the neurovascular bundle, and the posteromedial approach was performed first. The other 4 of these 6 patients initially had a standard anterolateral approach. In each case, the fracture could not be reduced, www.jorthotrauma.com |
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FIGURE 1. Anteroposterior radiograph (A) with the corresponding axial CT images in bone windows (B) and soft tissue windows (C) of a left pilon fracture showing complete interposition of the tibialis posterior tendon between the medial malleolar and posterolateral fracture fragments. The flexor digitorum tendon is immediately posteromedial to the tibialis posterior tendon.
and the interposed structure required a separate posteromedial incision for removal, reduction, and fixation. The final attending radiology read of the CT scan commented on the interposed structure in only 8 of the 40 fractures (20%).
DISCUSSION Pilon fractures are often the result of a high-energy injury resulting in a significant injury to the distal tibia and fibula. These fractures have been shown to have reproducible main fracture fragments that are present with or without variation in each injury.11,13 When there is adequate displacement between any of these fracture segments, surrounding soft tissue structures can become interposed. Although not in tibial pilon fractures, several prior series have shown the posteromedial musculotendinous and neurovascular structures of the ankle as the reason a reduction was unobtainable. The tibialis posterior tendon has previously been noted as the cause in irreducible ankle fracture dislocations14–18 and in irreducible lateral subtalar dislocations.19–21 The flexor digitorum longus tendon and the posteromedial neurovascular bundle have also been documented to impede reduction in complex ankle injuries.22–24 Through our retrospective review of a large series of patients who sustained a pilon fracture, nearly 10% of the patients had posteromedial soft tissue structure interposition within the posteromedial fracture site. The tibialis posterior tendon was the most commonly interposed structure in our series, but any or even multiple posteromedial structures may be entrapped in one fracture. Before looking at the radiographs or CT scans, a detailed physical examination can alert a surgeon to an entrapped structure. The tibialis posterior tendon was the most common interposed posteromedial structure noted in this cohort. After the initial spanning external fixation procedure, the flexor digitorum longus and flexor hallucis longus tendons can be tested for motion. With inhibited toe flexion or extension on physical examination, the presence of tendon entrapment should be considered. Unfortunately, with
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the ankle joint rendered immobile by the external fixator, the excursion of the tibialis posterior cannot be checked. This fact makes it even more important to carefully examine all the available imaging to ensure no structure is entrapped. Similarly, the course, divisions, and anatomic variations of the tibial nerve have been studied extensively.25,26 Applying this knowledge allows the surgeons to understand how proximal injury clinically manifests distally in the foot. Of the patients in our series with an entrapped structure, 10% of the patients had the posterior tibial neurovascular bundle trapped in the fracture site. This can cause a wide range of neurologic impairment but commonly produces some degree of plantar dysesthesia. The patients with tibial nerve dysfunction had the deficit since the time of injury. Although there is a theoretical possibility of the neurovascular bundle being between 2 fracture fragments and then being pinched as the limb is being distracted because of ligamentotaxis, no patients in this series developed neurologic dysfunction after the placement of spanning external fixation. Once definitive fixation was performed and the nerve was ensured to be free of the fracture site, the neurologic examination improved in all patients. By 6 months postoperatively, all patients had improved substantially but still had some degree of altered or plantar hypersensitivity. By clinically identifying tibial nerve dysfunction early, surgeons can look for evidence of entrapment on advanced imaging, correlate this with the physical examination, and develop an appropriate corrective surgical plan that will ensure no residual interposition. The OTA/AO classification system has evolved as a standardized and commonly accepted method of describing skeletal injuries and has been specifically investigated for fractures of the distal tibia.12,27 In our series, the OTA/AO classification showed 26 fractures (65%) as 43-C3 injuries, 12 fractures (30%) as 43-C2, and 2 fractures (5%) as 43-C1 injuries. Overall, the incidence of interposition was higher in the 43-C3 injuries, which are more typically associated with a higher energy injury mechanism. The increased degree of force typically produces more osseous damage and Ó 2013 Lippincott Williams & Wilkins
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FIGURE 2. Anteroposterior ankle radiograph (A) with the accompanying axial CT imaging in bone windows (B) and soft tissue windows (C) of a left pilon fracture demonstrating complete entrapment of the posterior tibial neurovascular bundle within the fracture site. The tibialis posterior and flexor digitorum longus tendons are seen anterior and medial.
associated fracture displacement that may allow the adjacent posteromedial tissues to become interposed. Although less common, care should be taken to not overlook the lower energy injury patterns as entrapment may also occur. Multiplanar radiographs of the ankle demonstrate the injury pattern and provide initial insight into surgical planning. Full-length radiographs of the tibia and fibula depict fracture extension of the pilon fracture into the metaphysis and diaphysis, as well as associated proximal fibula fractures. CT imaging builds from this initial information and provides more specific details of the injury. The axial sequences and the sagittal and coronal reconstructions delineate the individual fracture fragments, clarify metaphyseal and diaphyseal involvement, and show the presence and location of articular impaction. Tornetta and Gorup28 showed that the CT scan added additional information 82% of the time and noted a 64% rate of change in the operative plan after incorporating the findings of the CT scan. Although this was primarily focused on the bony anatomy and surgical approaches, CT imaging can also help identify and diagnose tendon pathology around the ankle.29–31 Taking note of an interposed structure could change the surgical approach chosen. More specifically, it could deem an additional posteromedial approach necessary to address the entrapped tendon or nerve, if it cannot be properly addressed through an anteromedial or anterolateral approach. In our series, 11 of 40 patients (27%) with an entrapped structure required a separate posteromedial approach. If needed, a posteromedial approach allows for direct visualization of the entrapped structure in addition to the reduction of the medial malleolar fracture component (Fig. 3). Further temporary or definitive fixation may also be performed through the same exposure (Fig. 4). Failure to recognize the presence of an interposed structure could lead to a malreduction, impaired tendon function, neurovascular insult, and the need for further surgery. Due to a number of factors, missed or delayed diagnosis of orthopaedic injuries in polytrauma patients unfortunately occurs. A recent literature review showed a wide spread distribution of missed injuries and delayed diagnoses Ó 2013 Lippincott Williams & Wilkins
incidence rates from 1.3% to 39%. Up to 22.3% of patients were found to have clinically significant injuries.32 Although not commonly thought of as a missed injury, not identifying the interposition of a structure can also potentially have significant clinical ramifications. Due to the retrospective nature of our series, we could not investigate whether the attending surgeon specifically took notice of the interposed structure before definitive fixation. One variable that we were able to look at was whether or not the attending radiologist commented on the presence of an interposed structure. In our series, only 20% of the patients with an entrapped structure were identified in the radiologist’s interpretation of the CT scan. With the often markedly impressive bony injuries seen with pilon fractures, the surrounding posteromedial soft
FIGURE 3. Clinical photograph showing complete interposition of the tibialis posterior tendon, which was irreducible from the anterolateral surgical approach. This separate posteromedial exposure was necessary to remove the tendon from the fracture site to obtain appropriate reduction. Editor’s note: A color image accompanies the online version of this article. www.jorthotrauma.com |
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REFERENCES
FIGURE 4. Clinical photograph showing extraction of tibialis posterior tendon, reduction, and internal plate fixation through posteromedial approach. Editor’s note: A color image accompanies the online version of this article.
tissues can get overlooked. In an attempt to provide the best care possible, we can educate ourselves and our radiology colleagues to always study the surrounding soft tissue structures and identify any pathology present. The weaknesses of this study include it being a retrospective study, and it is therefore subject to all biases and inherent limitations thereof. The operative reports and clinical notes were not documented in standardized fashion or with specific data entry protocols. Some potentially pertinent details from the surgical procedures or the perioperative period could have not been dictated or noted. As seen in this cohort, entrapped structures in pilon fractures are not overly common. Although this represents a large series of patients, larger numbers of patients with these injuries are needed to further assess the incidence and clinical impact of this scenario. In conclusion, pilon fractures are complex injuries to take care of for numerous reasons, and soft tissue management is paramount in the treatment algorithm. Careful attention must be paid to preoperative radiographs and CT imaging to identify the involved fracture fragments and articular impaction. In addition to the osseous injury, CT images can demonstrate whether nearby soft tissue structures are entrapped within the fracture. The presence of an interposed structure is more common in the higher energy and more complicated fracture patterns; however, it is also present in less complex injuries as well. The tibialis posterior tendon and posterior tibial neurovascular bundle were the 2 most commonly interposed structures, but multiple structures may be entrapped in the fracture site. Addressing an entrapped posteromedial structure may be possible working posteriorly through an anteromedial or anterolateral surgical approach. In some cases, this may prove to not be possible, and a separate posteromedial approach may be required. Each pilon fracture and injury to the soft tissue envelope is unique, and individualizing treatment is paramount. Taking account of all the involved factors will help achieve the optimal surgical, functional, and clinical outcome in these complex injuries.
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