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IXXX10.1177/1071100712469334Foot & Ankle InternationalKlammer et al 2013
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Posterior Pilon Fractures: A Retrospective Case Series and Proposed Classification System
Foot & Ankle International XX(X) 1–11 © The Author(s) 2013 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/1071100712469334 http://fai.sagepub.com
Georg Klammer, MD1, Anish R. Kadakia, MD2, David A. Joos, MD3, Jeffrey D. Seybold, MD3, and Norman Espinosa, MD1 Abstract Background: Posterior malleolus fractures occur in 7% to 44% of ankle fractures and are associated with worse clinical outcomes. Fractures that involve the posteromedial plafond extending to the medial malleolus have been described previously in small case series. Failure to identify this fracture pattern has led to poor clinical outcomes and persistent talar subluxation. The purpose of this study was to report our outcomes following fixation of this posterior pilon fracture and to describe a novel classification system to help guide operative planning and fixation. Methods: Eleven patients were identified following fixation of a posterior pilon fracture over a 4-year span; 7 returned at minimum 1-year follow-up to complete a physical examination, radiographs, and RAND-36 (health-related quality of life score developed at RAND [Research and Development Corporation] as part of the Medical Outcomes Study) and American Orthopaedic Foot & Ankle Society (AOFAS) ankle/hindfoot questionnaires. Patient records were reviewed to evaluate for secondary complications or operative procedures. Results: Our mean postoperative AOFAS ankle/hindfoot score was 82. Anatomical reduction of the plafond was noted radiographically in 7 of 11 patients, with the remainder demonstrating less than 2 mm of articular incongruity. Five of 7 patients demonstrated ankle and hindfoot range of motion within 5 degrees of the uninvolved extremity. Four complications required operative intervention; 2 patients reported continued pain secondary to development of CRPS. Conclusion: The posterior pilon fracture is a challenging fracture pattern to treat, and it has unique characteristics that require careful attention to operative technique. Our results following fixation of this fracture pattern are comparable with results in the literature. In addition, a novel classification scheme is described to guide recognition and treatment of this fracture pattern. Level of Evidence: Level IV, retrospective case series. Keywords: posterior pilon, ankle, fracture, trimalleolar, syndesmosis Fractures of the posterior malleolus have been estimated to occur in 7% to 44% of all ankle fractures.3,4,12,25 Multiple studies have demonstrated that trimalleolar fractures fare worse than unimalleolar or bimalleolar fractures3,12,16,25; higher energy mechanism, inadequate reduction of the tibial articular surface or syndesmosis, and persistent subluxation of the talus all are implicated as causative factors leading to posttraumatic arthritis and disability. Biomechanical data correlating posterior malleolar fragment size with presence or absence of talar subluxation and increased contact stresses are inconclusive,7,10,15,20,22,27 and surgeon practice regarding when to fix the fragment shows considerable variation.8 Factors aside from anteroposterior fragment size have been left largely unevaluated. In 1979 Pankovich and Shivaram,18 and in 1990 Ebraheim et al,6 described a pattern of medial malleolar fractures through the posterior colliculus that related to a classification introduced by Bonnin2 to distinguish different types of
medial malleolar fractures. Karachalios et al13 recognized a distinct variant of posterior malleolar fracture in which the posterior malleolar fragment is split into a posteromedial and posterolateral fragment (Figure 1). Weber28 described a series of 10 patients with similar posterior malleolar fractures often extending into the posterior colliculus of the medial malleolus. All patients in this series demonstrated a characteristic double contour sign on anteroposterior radiographs indicating the presence of an additional posteromedial fracture fragment (Figure 2). Anteroposterior fragment 1
Balgrist Hospital, University of Zurich, Zurich, Switzerland Illinois Bone and Joint Institute LLC Glenview, Glenview, IL, USA 3 Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA 2
Corresponding Author: Anish R. Kadakia, Illinois Bone and Joint Institute LLC Glenview, 2401 Ravine Way, Glenview, IL 60025, USA Email:
[email protected]
2
Figure 1. Typical appearance of the posterior malleolar fracture, where the fragment typically involves the whole tibialis posterior lip exiting the medial malleolus through or anterior to the posterior colliculus. Most often it is split into an anteromedial and a posteromedial fragment with a zone of posteromedial comminution. Reprinted with permission of M. Weber.28
Foot & Ankle International XX(X) the posteromedial fragment remains attached to the tibialis posterior tendon sheath. Furthermore, posteromedial and posterolateral articular comminution may prohibit reduction. Anatomical reduction of the posterolateral fragment alone may still allow posteromedial talar subluxation as illustrated in Weber’s series,28,29 possibly secondary to the posterior displacement of the deltoid ligament origin attached to the posteromedial fragment. In our practice we have observed a series of the fractures described above and given them the term posterior pilon fractures to differentiate them from the standard trimalleolar or Volkmann fractures. To restore the competence of the posterior inferior tibiofibular ligament11 and to avoid chronic posteromedial subluxation,28 we perform open reduction and fixation of the posterolateral and posteromedial fragments regardless of their size. Fixation of this type of posterior malleolar fracture has been described through posteromedial or combined posteromedial–posterolateral approaches.11,17,24,28 The purpose of this study was to report the outcomes of 11 patients who presented to our clinic with this unusual posterior pilon fracture and were treated with open reduction and internal fixation through a posterolateral approach. Given these cases, we propose a classification system that details the variations of this fracture type and guides operative strategy.
Methods
Figure 2. Radiological signs of posterior pilon fractures on anteroposterior and lateral views: double contour sign at the medial malleolus (white arrow); involvement of the whole tibialis posterior metaphysis leading to a double joint line sign. Reprinted with permission of M. Weber.28
size is often underestimated on lateral radiographs in this specific fracture type because the fracture plane is more coronal compared with the classic Volkmann fracture.28 Although the posterolateral fragment attached to the posterior tibiofibular ligament may be indirectly and anatomically reduced by means of ligamentotaxis, this is more unlikely if
Institutional review board approval was obtained prior to initiation of this study. We retrospectively identified all patients with trimalleolar fractures that fit the posterior pilon fracture pattern treated by open reduction and internal fixation by a single foot and ankle fellowship-trained surgeon (ARK) between September 2006 and March 2010. Of note, not every patient underwent preoperative computed tomography (CT) scans, as this was not part of our initial imaging protocol for this fracture pattern. Patients with a minimum 1-year follow-up from their initial fracture fixation were considered eligible for the study. Patients were contacted to enroll in the study and were asked to present to the clinic for postoperative physical examination and radiographs. Each patient’s pain, satisfaction, and functional status were measured via completion of standardized questionnaires including RAND-36 (36-item health-related quality of life score developed at RAND [Research and Development Corporation] as part of the Medical Outcomes Study) and American Orthopaedic Foot & Ankle Society (AOFAS) ankle/hindfoot scores. Informed consent was obtained, and compensation was provided for participation. Patients’ records were reviewed to evaluate for any known secondary complications or operative procedures. We identified 11 patients who underwent fixation of a posterior pilon fracture during the study period; 7 of them
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Figure 3. Intraoperative photograph of the standard posterolateral incision used for this fracture (solid line). The sural nerve (dashed line) is at risk in the proximal aspect of the incision and must be identified and protected.
Figure 4. Intraoperative view demonstrating the posteromedial (PM) and the posterolateral (PL) fracture fragments as visualized through a single posterolateral approach.
agreed to return for a follow-up visit (mean follow-up 22.7 months; range, 15-30 months). The mean age of the 11 patients included was 39 years (range, 25-69 years).
Operative Technique Patients were positioned prone on a radiolucent table. The foot was allowed to hang free, aiding reduction of the fracture. A standard posterolateral approach was taken initially on all fractures using a longitudinal incision immediately lateral to the Achilles tendon.11 Incision length was dependent on the height of the fibula fracture, with proximal extension of the incision performed as required (Figure 3). The sural nerve was identified and protected. Through the superficial interval between the Achilles tendon and the sural nerve, the fascia overlying the flexor hallucis longus was exposed and subsequently incised. Through the interval between peroneal and flexor hallucis longus tendons, the posterior aspect of the ankle was identified and the posterior pilon fracture exposed (Figure 4). Care was taken to preserve the posterior inferior tibiofibular ligament to maintain the integrity of the syndesmosis (Figure 5). The comminuted posteromedial plafond was accessed through the fracture from a cranial direction or between the posteromedial and posterolateral fragments in an open book fash-
Figure 5. The posterior inferior tibiofibular ligament (black arrow) must be preserved to maintain the integrity of the syndesmosis.
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Figure 6. (A) Lateral fluoroscopic image with provisional fixation of the posteromedial and posterolateral fracture fragments. Note that the contour of the joint is restored; however, there is lack of compression of the posterior fracture fragments. (B) With buttress plate fixation of both fragments and compression of the fracture fragments, the joint is anatomically restored.
ion. Depending on size, the affected chondral fragments were anatomically reduced between the primary posteromedial fragment and the remainder of the plafond, or excised. Fragments were fixed temporarily using K-wires with definitive fixation achieved via 2.7-mm or 3.5-mm plates and screws, which was completed before or after reduction of the posterolateral fragment (Figure 6). One or 2 plates were used in a buttress fashion, depending on the exact fracture pattern and degree of comminution (Figure 7). If there was any difficulty with posteromedial fragment reduction, a direct medial incision was made, which was required in 2 patients. Further posteromedial fragment reduction and fixation were then possible without need for extensive posteromedial dissection, conserving the attachment of the tibialis posterior tendon sheath and vascularization of the posteromedial fragment.28 Fracture patterns including an anteromedial fragment allowed inferior retraction of the medial malleolus to gain intra-articular access and confirmation of articular surface reduction. The anteromedial fragment of the medial malleolus was then reduced and secured with 2.4-mm or 2.7-mm screws. The fracture fragment in these cases was smaller than that seen in a standard bimalleolar fracture, requiring the use of smaller diameter screws for fixation (Figure 8). In each case, the posterolateral approach alone, or the posterolateral approach in combination with the medial incision, provided adequate exposure. After the fixation of the tibialis posterior plafond, the fibula was approached through the same posterolateral incision. In most cases, indirect reduction of the fibula was achieved through prior fixation of the posterior malleolar
Figure 7. Intraoperative photograph depicting the final fixation of the posteromedial and posterolateral fragment with one-third tubular plates. In this case, comminution at the fracture site prevented cortical apposition, which is not uncommon in these injuries. The fixation is performed from proximal to distal to aid in compression of the posterior fracture fragments. Note that tibialis posterior fixation is completed prior to fixation of the fibula in order to visualize the joint under fluoroscopy.
fractures. Furthermore, intraoperative lateral radiography to confirm correct reduction of the pilon was not impeded by the fibular plate. The fracture was reduced and a third tubular plate applied in an antiglide fashion. Tibiofibular diastasis on preoperative CT scans indicated syndesmotic disruption. We believe that in the presence of
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Figure 8. (A) Small anteromedial fracture fragment that occurs with this particular injury. (B) Intraoperative view depicts the small fragment (black arrow) that has been retracted with a dental pick. With this exposure, the joint can be visualized and concomitant articular injuries can be addressed. (C) Intraoperative fluoroscopy demonstrates the final construct with a single 2.4-mm screw placed within the anteromedial fragment for fixation. Attempting to use a larger diameter screw may result in blowout of the fracture fragment and should be avoided. This is in contrast to the standard 3.5/4.0-mm screws used in traditional medial malleolar fractures.
Figure 9. (A) Axial computed tomography scan of a patient with a posteromedial and posterolateral fragment with preserved integrity of the anterior inferior tibiofibular ligament (AITFL), as noted through lack of diastasis (arrow). In this case, with fixation of the posterolateral fragment, the stability of the syndesmosis should be restored. (B) The obvious widening of the anterior aspect of the syndesmosis is consistent with injury to the AITFL that will not be restored with reduction of the posterolateral fragment. In this case, supplemental fixation of the syndesmosis is required in addition to reduction and fixation of the posterior malleolus. Given the interposed fragment between the posterolateral fragment and tibia, an indirect reduction of that piece is impossible.
clear disruption of the syndesmotic complex with widening of both the anterior and posterior aspects of the syndesmosis, isolated fixation of the posterior malleolus was not sufficient for syndesmotic stabilization (Figure 9). However, direct intraoperative provocative testing was always used, and if there was any indication of syndesmotic disruption, syndesmotic screws were placed. A short leg splint in
resting plantar flexion was applied given the posterior location of the incision to maximize perfusion to the wound.
Postoperative Treatment The splint and sutures were removed at 2 weeks, and the patient was placed in a cast boot and started on active range
6 of motion exercises. Patients were kept non-weight-bearing for 6 weeks and then allowed to bear weight as tolerated in the boot. They were transitioned to an ankle support orthosis at 8 to 9 weeks and allowed to return to desired activities, excluding impact activity, until 16 weeks postoperatively, provided no syndesmotic fixation was performed. Syndesmotic screws, if present, were removed routinely 4 to 5 months following initial fixation, after which impact activity was permitted.
Study Visit At a minimum of 1 year, each available patient had a standardized physical examination of the operative and nonoperative extremity, underwent a 3-view series of weight-bearing ankle radiographs, and completed questionnaires containing basic demographic information, RAND36 scores, and AOFAS ankle/hindfoot scores. Patient radiographs were reviewed using the grading scale proposed by Kellgren and Lawrence14 to identify posttraumatic osteoarthritis. The radiographs were graded independently by the authors. The highest numerical score for each patient was included in the results.
Results The results of subjective and objective testing are summarized in Table 121 (including RAND-36 values in a healthy population for comparison). The quality of reduction on postoperative radiographs was rated as good (no articular step-off or talar subluxation) in 7 patients and as fair (less than 2-mm step-off or minimal talar subluxation) in 4, all of the latter belonging to the group available for follow-up. Total AOFAS-scores demonstrated an average of 82 points (maximum 100), and RAND36 scores reached between 63% and 97% of the values obtained in a healthy population21 (the lowest score being for energy/fatigue). Of note, preoperative scores were not available for comparison, as the patients were identified retrospectively at least 1 year after their traumatic injury. In 5 patients, complications occurred that required further operative intervention. These included nerve decompression for sural neuritis (patient 8), exostectomy for fibular exostosis and drilling of a talar chondral defect (patient 3), medial hardware removal with medial osteophyte excision for localized pain (patient 8 and 11), arthroscopy for anterior ankle impingement due to scar formation (patient 4), and Achilles tendon lengthening with joint debridement (patient 5). Three patients underwent removal of syndesmotic screws (patients 5, 8, and 9). Two patients reported continuous pain due to development of complex regional pain syndrome (CRPS) postoperatively (patients 4 and 8). Three of these complications occurred in 1 patient (Table 1, patient 8). This patient developed sural neuritis
Foot & Ankle International XX(X) and medial ankle pain and underwent sural nerve decompression and medial hardware removal. The same patient was also later diagnosed with complex regional pain syndrome. In a 29-year-old healthy female (Table 1, patient 9), a deep infection developed after syndesmotic screw removal 5 months postoperatively. She underwent hardware removal and debridement and required 1 subsequent irrigation and debridement before clearance of her infection. One patient in our study (Table 1, patient 4) reported markedly low AOFAS and RAND-36 scores. This patient developed CRPS postoperatively, along with persistent ankle pain, without obvious injury to any major nervous structure. She eventually underwent ankle arthroscopy, which revealed anterior ankle synovitis and chondral softening of the anteromedial tibial plafond without full-thickness defect. No posterior chondral irregularity was found at the time of arthroscopy. She continued to have difficulty with pain and symptoms of CRPS throughout her entire follow-up period.
Discussion The posterior pilon fracture is a recently described variant of the trimalleolar ankle fracture13,28 that we believe is unique and potentially difficult to treat. As opposed to classic posterior malleolar fractures, in which the fragment is a laterally based dorsal wedge, in the posterior pilon fracture a majority of the tibialis posterior lip is fractured. This fracture is often based medially and extends into a coronal plane fracture through the posterior aspect of the medial malleolus (posterior colliculus). This fracture extension into the medial malleolus has been reported in 19% of posterior malleolar fractures.9 Weber28 reported this fracture pattern in 8% of the malleolar fractures treated surgically at his institution. Most often the posterior lip is separated in a posterolateral and a larger posteromedial fragment with characteristic posteromedial impaction.9,28 This fragmentation has been shown to allow persistent posteromedial talar subluxation and requires anatomical reduction and fixation.28 In our review, we found 2 additional fracture components that occur with this type of fracture: an additional anteromedial tibial fragment including the anterior half of the medial malleolus, which due to its small size is difficult to secure, and syndesmotic disruption. The presence of tibiofibular syndesmotic injury concurrently with a posterior pilon fracture has not, to our knowledge, been described previously in the literature. Three of 11 patients in our study presented with this specific injury. The mechanism leading to syndesmotic disruption is probably secondary to excessive ankle dorsiflexion; however, the implications of a syndesmotic injury concurrent with a posterior pilon fracture are unknown. Posterior pilon fractures may be difficult to recognize on conventional radiographic views. In addition to the double contour sign28 outlined above, a metaphyseal fracture line
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Patient 3
Patient 4
50 75 100 55 88 100 68 85 2
7/45 10/50 7/2 10/5 69
8/25 20/50 10/20 22/11 98 95 25 100 65 76 88 78 85 0 Removal syndesmotic screw transfixation at 5 mo, Achilles lengthening and debridement at 17 mo
56 F Left 3 15 Fair
Patient 6
25 F Left 2S 24 Fair
Patient 5 33 F Right 3S NA Good
Patient 8 25 F Right 1S NA Good
Patient 9
80 100 100 55 80 100 55 65 0 Superficial Asymptomatic Sural neuritis, infection after CRPS, medial medial hardware removal syndesmotic malleolus screw for medial ankle nonunion pain, syndesmosis removal requiring I&D HWR
2/40 4/40 2/1 5/3 87
35 M Right 3 16 Fair
Patient 7 25 F Left 2 NA Good
Patient 10
Mild medial ankle pain with HWR and medial osteophyte excision 8 mo postoperatively
69 F Left 3 NA Good
Patient 11
75 71 86 51 71 84 70 74
82
22.7
39
94 94 92 81 87 96 87 76
RAND-36 Mean Healthya
Abbreviations: AOFAS, American Orthopaedic Foot and Ankle Society hindfoot score; CRPS, complex regional pain syndrome; DF, ankle dorsiflexion; EF, energy/fatigue; EH, role limitations due to emotional problems; EW, emotional well-being; GH, general health; HWR, hardware removal; I&D, irrigation and debridement; NA, not available for follow-up >1 year postoperatively; OA, osteoarthritis; P, plantar flexion; PF, physical functioning; PH, role limitations due to physical health; RAND-36, 36-item health-related quality of life score developed at RAND (Research and Development Corporation) as part of the Medical Outcomes Study; ROM, range of motion; SF, social functioning. a RAND-36 scores of healthy subjects (from Saharinen et al21). b Reduction quality: good, no articular step-off or talar subluxation; fair, 2 mm step-off or marked talar subluxation. c Noninjured side. d Out of 100. e Kellgren and Lawrence arthritis score14 at follow-up.
Age at injury 33 46 47 36 Gender M F F F Side Right Right Right Left Fracture type 3 3 3 3 Follow-up, mo 26 23 25 30 Reduction Good Fair Good Good qualityb ROM DE/P 20/38 15/45 5/50 5/35 DE/Pc 20/35 15/45 9/55 15/40 I/E 15/8 15/5 N/A 5/5 I/Ec 15/10 15/5 N/A 10/5 AOFASd 90 100 98 29 RAND-36 scalesd PF 100 100 100 0 PH 100 100 100 0 EH 100 100 100 0 EF 50 65 70 0 EW 72 68 92 24 SF 100 100 100 0 Pain 90 100 100 0 GH 80 90 100 15 OA gradee 0 1 2 1 CRPS, stiffness. Notes Fibular synovitis and exostosis, anteromedial chondral tibial plafond defect in talus treated chondromalacia, with drilling status post ankle arthroscopy and debridement
Patient 1 Patient 2
Table 1. Patient Data
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Table 2. Classification of Fractures Involving the Tibialis Posterior Plafond and Implication for Operative Strategy Fracture Type
1
Fibula
2
3
Fracture type Weber type B or C
PM
Typically medially based wedge with posteromedial comminution Sagittal plane fragment split Fragment may be split
MM
PM fracture line may exit MM PM fracture line may exit MM through posterior colliculus through posterior colliculus. May have additional anteromedial MM fracture
PM fracture line exits medial malleolus anterior of the posterior colliculus with additional anteromedial MM fragment
Syndesmoticdisruption modifier (S)
+ AITFL rupture
+ AITFL rupture
Operative strategy
Syndesmotic screw transfixation
+ AITFL rupture
Posterolateral approach: 1. ORIF posteromedial fragment 2. ORIF posterolateral fragment 3. ORIF fibular fracture Medial or limited posteromedial Medial approach required to reduce approach optional if unable to and fixate anteromedial fragment achieve reduction of PM fragment or additional MM fracture Syndesmotic screw transfixation Syndesmotic screw transfixation
Abbreviations: AITFL, anterior inferior tibiofibular ligament; MM, medial malleolar fragment; ORIF, open reduction internal fixation; PM, posterior malleolar fragment.
involving the entire width of the posterior distal tibia (a double joint line sign) corresponding to a large, displaced posterior malleolar fragment1 may indicate a posterior pilon type fracture (Figure 2). For further fracture assessment, we recommend performing a CT scan after closed reduction in order to adequately plan the intervention, and this has now become part of our standard preoperative imaging protocol. Drawing on our findings in this study, we classified posterior pilon fractures into 3 primary categories by increasing degree of complexity. As syndesmotic disruption may occur with any of the 3 fracture types, we suggest the use of a modifier to complete a classification to guide operative treatment strategy (Table 2). Ultimately, larger prospective studies will be required to define the prognostic power of our classification system. In summary, type 1 fractures with a single medially based posterior malleolar fragment can be addressed through a posterolateral approach alone (Figure 10). Type 2 fractures, in which the posterior fragment is split with possible posteromedial comminution, may require an additional medial or limited posteromedial approach to assist in reduction and fixation of the posteromedial fragment or separate medial malleolar fracture (Figure 11). In type 3 fractures, the fracture line of the posterior malleolus exits the medial malleolus anterior to the posterior colliculus, and an additional anteromedial fragment is present. A medial approach is always necessary for reduction and
fixation of the additional anteromedial fragment (Figure 12). The fibula fracture is addressed after fixation of the tibia. If disruption of the anterior tibiofibular ligament is present (modifier S), additional syndesmotic screw transfixation is performed (Figure 10). This retrospective study presents the experience and outcomes of the senior author’s approach to operative treatment of the posterior pilon fracture. We found that the posterolateral approach was a safe exposure to adequately visualize, reduce, and fix the posterolateral and posteromedial tibial fragments. When required, an additional medial approach was used, limiting soft tissue dissection posterior to the tibialis posterior tendon. Patient outcomes as measured in this study using the RAND-36 and AOFAS scores were variable. One patient had very low scores secondary to development of CRPS. Excluding this patient’s results markedly improves the mean overall RAND-36 and AOFAS scores in our cohort, although many patients still did not meet the healthy subject RAND36 scores in multiple categories (Table 1). However, overall AOFAS scores are comparable to the series by Weber28 (mean follow-up 16.2 months, AOFAS score mean 94.3 [range, 83-100]). Of note, in the Energy/Fatigue category of the RAND-36 scores, all study patients scored lower than the healthy subject average. Physical Functioning, Role Limitations Secondary to Physical Health, and Pain scores
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Figure 10. Anteroposterior and lateral views of a patient with a type 1S posterior pilon fracture (Table 1, patient 9): (A) preoperatively and (B) at 1 year postoperatively after removal of the syndesmotic screws. The posterior malleolar fracture involves the whole tibial metaphysis exiting the medial malleolus through the posterior colliculus. The letters “LW” are radiographic markers utilized by the x-ray techs to indicate left/ right. They are not of significance.
varied widely between patients. Our data would suggest that approximately 2 years after sustaining this fracture, patients would not be expected to have subjective quality of life scores equivalent to those of healthy controls. At last follow-up, 5 of 7 patients achieved ankle dorsiflexion, plantar flexion, and hindfoot inversion and eversion within 5 degrees of the uninvolved extremity. Only 1 patient (Table 1, patient 5) sustained a loss of motion in all dimensions. The average range of motion impairment after open reduction and internal fixation of tibial plafond fractures has been reported at 12%, more than double that reported in fractures treated with external fixation with or without limited internal fixation.19 As that study used a different outcome measurement instrument, direct comparison with our results is not possible. However, we would expect a similar result for posterior pilon-type fractures and have shown that
Figure 11. Anteroposterior and lateral views of a patient with a type 2 posterior pilon fracture (Table 1, patient 10). (A) On the preoperative radiographs, a positive double contour sign can be appreciated indicating involvement of the whole tibialis posterior metaphysis. (B) This is confirmed on axial CT scans, where additional posteromedial comminution can be seen (white arrow) with syndesmotic gapping (white arrowhead) excluded. (C) Postoperative radiographs demonstrate double plating of the posterior malleolar fragment. The letters “LDB” are radiographic markers utilized by the x-ray techs to indicate left/right. They are not of significance.
open anatomical reduction and stable internal fixation led to a near-normal range of motion in most of our cases. Although many of our patients achieved successful overall results with a complex fracture pattern, others performed poorly despite successful restoration of joint congruity with
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Figure 12. Anteroposterior and lateral views of a patient with a type 3 posterior pilon fracture (Table 1, patient 7). (A) Preoperative radiographs; (B)axial CT scan showing the split posterior malleolar fragment extending anterior to the medial malleolus with anteromedial fragment seen on sagittal plane view through the medial malleolus; (C) postoperative views.
absolute rigid fixation. Due to use of different outcome measurements across studies, comparison among series of malleolar fractures is difficult. Our results reinforce previously reported data regarding the poor outcomes of trimalleolar ankle fractures compared with more simple fracture patterns.3,12,16,23,25 However, our data might better be compared with pilon fractures where articular reduction correlates with radiographic evidence of ankle arthritis and clinical outcomes are multifactorial.5 It is suspected that trauma to the soft tissues and cartilage has a major role in
Foot & Ankle International XX(X) the outcomes of pilon fractures as well as the described posterior pilon fracture. For this reason, and to distinguish from classical trimalleolar fractures with a posterolateral Volkmann fragment, we prefer to term the specific fracture type described above as posterior pilon fractures. Kellgren osteoarthritis grades varied between 0 and 2 in the 7 patients for whom radiographic follow-up greater than 1 year postoperatively was available. Pretraumatic osteoarthritis grades naturally were not available. The 2 patients scoring at grade 2 were the oldest patients of the series; however, primary osteoarthritis of the ankle is rare.26 For tibial plafond fractures, radiographic evidence of osteoarthritis development was best predicted by injury severity and quality of reduction.5 The patient number is too small to draw conclusions regarding the risk factors for development of early posttraumatic osteoarthritis in our series. Limitations of this study include its retrospective nature, small sample size, lack of a control group, and short followup period. Preoperative scores were not available for comparison due to the retrospective nature of this study. In addition, visual analog pain scores were not recorded as part of the data collection. Subjective reports of pain and satisfaction are included, however, as part of the more comprehensive AOFAS and RAND-36 questionnaires. The quality of reduction and presence of posttraumatic degenerative changes were also graded solely on plain radiographs. Although CT scan would offer more complete assessment of the entire articular surface, we did not obtain postoperative CT scans to limit both costs of the study and additional radiation exposure to the patient. We found the posterior pilon fracture to be a relatively rare fracture pattern at our institution. Multiple centers may be necessary to recruit adequate numbers of patients for future studies. It is a weakness of this study that our classification system, although comprehensive, is based on our limited experience of this rare fracture type and not every patient will easily fit into a predetermined classification. As a result, multiple fracture types in our classification only included 1 patient (and none with a type 1 fracture) from our series. Nonetheless, the classification provides a systematic method for evaluating these fractures and identifying the critical aspects that require attention in the operating room. Prospective, randomized trials are required to adequately elicit the critical factors affecting the outcomes of these fractures and subsequently guide the treatment of posterior pilon fractures. In conclusion, trimalleolar ankle fractures continue to be challenging ankle fractures to treat. The involvement of the posteromedial tibial plafond represents a unique fracture type that behaves differently than traditional teaching would suggest. We agree with the conclusions of prior case series that this fracture pattern is important to recognize and provides a classification pattern that may help guide appropriate treatment.
Klammer et al Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
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