Defining Talar Head and Neck Pathology: The Malvern Classification System

The Journal of Foot & Ankle Surgery xxx (2017) 1–9

Contents lists available at ScienceDirect

The Journal of Foot & Ankle Surgery journal homepage: www.jfas.org

Review Article

Defining Talar Head and Neck Pathology: The Malvern Classification System Christopher Robin Hood Jr., DPM, AACFAS 1, Jason Roy Miller, DPM 2, 3, Josuha Kevin Hollinger, DPM 4 1

Fellowship-Trained Foot and Ankle Surgeon, Premier Orthopaedics and Sports Medicine, Malvern, PA Fellowship Director, Department of Foot and Ankle Surgery, Premier Orthopaedics and Sports Medicine, Malvern, PA Residency Director, Podiatric Medicine and Surgery Residency/Reconstructive Rearfoot Ankle Surgery, Phoenixville Hospital, Phoenixville, PA 4 Fellow, Pennsylvania Intensive Lower Extremity Fellowship, Premier Orthopaedics and Sports Medicine, Malvern, PA 2 3

a r t i c l e i n f o

a b s t r a c t

Level of Clinical Evidence: 4

Talar fractures account for <1% of all fractures in the body and 3% to 6% of pedal fractures. Of these fractures, avulsion and neck fractures represent the most and second most common type, respectively. Several classification systems exist for talar fractures of the talar dome (Berndt-Hardy), talar neck dislocation (Hawkins), and talar body (Sneppen) anatomic locations. Although diverse, they are not all encompassing for fracture patterns of the talus. Another set of pathologic issues occur about the talar head and neck region that can be seen in the clinical setting. Thus, a new classification system (Malvern classification system for talar head/neck fractures) was devised and defined for this location. The system represents a comprehensive review of the available published data and synthesis into an organized classification system. Ó 2017 by the American College of Foot and Ankle Surgeons. All rights reserved.

Keywords: avulsion fracture classification fracture Hawkins talus trauma

Fractures of the talus account for <1% of all fractures in the body, consisting of 3% to 6% of all pedal fractures (1). In reviewing the classification system data, we found named systems for the talar dome (Berndt-Harty), talar neck dislocation (Hawkins), and talar body (Sneppen) fracture patterns (1–4). Within these systems, examples exist of small fragment fracture pathology for both the talus and the navicular (Table 1). However, no system has included these fractures that involve the talar neck and head region. Although often small in size, fractures and anatomic variants resembling fractures to this anatomic location are seen in the clinical setting and have been reported in published studies mainly on a case by case basis. In a further review of the published data, other types of talar head and neck pathology have not been categorized in the current classification systems. Realizing that the currently published systems (i.e., BerndtHarty, Hawkins, Sneppen) are not all encompassing (Table 2), specifically for this region of the talus, a new system was devised to define the pathology to this anatomic location of the talus. The name of the system, Malvern, is a tribute to the borough of our primary office located 25 miles west of Philadelphia, Pennsylvania.

Historically, the naming of the town is a mystery. One theory is that the town, owing to its raised elevation compared with the surrounding communities, mirrored the Malvern Hills in England and/or Malvern Hill in Virginia and was thus named by the original settlers. The new system, the Malvern classification system (Tables 3 and 4), defines the pathology localized to the talar head and neck. This system was determined from the observed pathologic issues encountered at our office and a detailed review of the published data. The purpose of the present study was to report a new proposed classification system for defining talar head and neck pathology. The system is designed to define the pathology by anatomic location, incidence, mechanism of injury, radiographic characteristics, key characteristics, and recommended treatment options. This project represents a comprehensive review of the available data synthesized into an organized classification system and commonly seen pathologic features located to the talar head and neck that has, to this point, not been organized into a succinct classification system compared with other portions of this bone. Materials and Methods

Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Christopher Robin Hood, Jr., DPM, AACFAS, Premier Orthopaedics and Sports Medicine, 266 Lancaster Avenue, Suite 200, Malvern, PA 19355. E-mail address: [email protected] (C.R. Hood Jr.).

Initially, we discussed various types of potential pathology to the talar head and neck according to historical experience and office presentations. From the discussion, a list was formulated, creating the initial framework for the Malvern classification system in its rawest format. To enhance the validity of the list, we performed a literature search and review to define the various forms of pathology that occur about the talar head and neck. A PubMed advanced key word search was performed on March 1, 2016.

1067-2516/$ - see front matter Ó 2017 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2017.07.008

2

C.R. Hood Jr. et al. / The Journal of Foot & Ankle Surgery xxx (2017) 1–9

Table 1 Classification of small avulsion-type fractures about the talus and navicular Bone

System

Description

Navicular (body fractures) Talus (dome fractures) Talus (body fractures) Talus (body fractures) Talus (lateral process fractures)

Watson-Jones 2 Berndt-Harty 2 and 3 Sneppen, group 3 Sneppen, group 4 Hawkins type 1 to 3

Dorsal lip avulsion fracture Partially/fully detached fragment of osteochondral fracture Fracture of posterior tubercle of talus/Shepherd’s fracture Fracture of lateral process of talus; snowboarder’s fracture Fracture of lateral process of talus defined as (1) simple, (2) comminuted, and (3) chip

Data from Melenevsky et al (5).

The search criteria keywords used include talar head, talar neck, talar pathology. The search did not employ any language filters, date filters, or article-type filters. The titles, abstracts, and/or database tags of the resulting studies were reviewed to determine their validity regarding their relevancy to the primary search goal of obtaining studies demonstrating pathology to the talar head and neck. From these reports, a secondary identification process was performed using the relevant cited references within the initially discovered reports to provide a complete search discovery of talar head and neck pathology that fit the primary purpose of the present review. The secondary review was performed by recalling the studies referenced in the initially discovered studies to collect more information pertaining to the main review points. Image reprint requests were obtained. The inclusion criterion was contained to studies reporting on pathology to the talar head and neck and excluding pathology not accompanied by >3 of the necessary information points for our review (i.e., incidence, mechanism of injury, radiographic characteristics, key characteristics, recommended treatment options). The zone of pathology was defined as the talar head and neck area and was the only inclusion criterion (Fig. 1). If possible, from the reported data, the location, incidence, mechanism of action/injury/existence, imaging information, treatment, and any additional key points were identified. Specifically regarding imaging information, details have been described regarding important film views (dorsoplantar, lateral, oblique) and imaging series (radiographs [XRs], magnetic resonance imaging [MRI], or computed tomography [CT]) required for a more accurate diagnosis. The treatments range from closed reduction (CR), immobilization in a controlled ankle motion (CAM) boot, open reduction and internal fixation (ORIF), and periods of non-weightbearing (NWB) and protected weightbearing (PWB). Key points, including any further facts, anecdotal information, or important information from the published data review, were also notated.

Results From the audit and review of the published data, we developed the Malvern classification system (Table 3). For each pathology identified, a type was defined according to the location, incidence (cited data), mechanism of injury, imaging modality useful for identification, and data-cited treatment options (Tables 4 and 5). Discussion Osseous pathology about the talar head and neck has been minimally reported in published studies. Talar fractures account for <1% of all fractures in the body (3% to 6% of all pedal fractures), with fractures located at the neck representing 0.14% to 0.32% of fractures (1). This location represents the second most common injury to the talus, surpassed only by avulsion fractures (6). Examples were mainly found from small case series or case reports, with anecdotal treatments described in the series or report by the manuscript’s author. Some of these fractures were actually anatomic variants misdiagnosed as fractures and vice versa. It has been reported that upward of 40% to

Table 2 Talar head and neck classified pathology Bone

System

Description

Navicular (body Watson-Jones 2 Dorsal lip avulsion fracture fractures) Talus (neck fractures) Hawkins type 1 Nondisplaced vertical fracture of talar neck Talus (body fractures) Sneppen group 2 Sagittal shearing fracture (if extending from talar body through and to neck/head Data from Melenevsky et al (5).

60% of talar avulsion fractures to the head and neck have been misdiagnosed (7). We sought to provide diagnostic keys and cues to decrease the rate of misdiagnosis and to report on other types of pathology of the talar head and neck not currently classified. Both the patient interview and the clinical examination play a key role in the diagnosis. The physician should determine the inciting mechanism to concentrate on certain anatomic locations of the foot. As 1 series demonstrated, patients suspected of having an ankle sprain or a fracture should have the dorsal talus palpated or examined radiographically for avulsion pathology (7). Furthermore, the mechanism or lack thereof will help in differentiating accessory ossicles from fractures. For fractures, patients will describe a history of trauma, explaining some type of twist, fall, or violent motion to the foot as the starting point of their pain. The physical examination will often reveal pain to the touch and swelling and bruising to the area overlying the talar head and neck or navicular bone. Some patients will complain of recurrent or recalcitrant discomfort to this anatomic area expressed as a deep ache or self-limiting with activity, suggesting stress fracture, bone marrow lesion, or articular pathology. Imaging is another important component in the diagnosis. No statistics have been reported on the laterality incidence of accessory ossicles of the foot. However, when suspicious for pathology that is traumatic in origin, ordering bilateral films for comparison is prudent. Typically, lateral and oblique XRs are a good starting point. Canale and Kelly described a technique for more accurate talar neck visualization (8). Termed the “Canale view,” the ankle is maximally plantarflexed, the foot pronated 15
, and the beam angled 75
from the horizontal plane. Often, most of these fractures will be visualized on 3-view plain XRs of the foot and/or ankle. The radiographic signs include cortical breaks, sclerotic lines, densities in the soft tissue, and/or an increase in soft tissue density, usually adjacent to the fracture site. One report suggested that any ankle injury requiring XRs of the ankle should also have anteroposterior films of the foot to evaluate the talonavicular joint (TNJ) and talar head (9). The radiographic sensitivity for detecting talar fractures ranges from 74% to 78% (9). Advanced

Table 3 Malvern classification system for dorsal talar head and neck Category

Description

Type 1 1A 1B

Accessory ossicle Os supratalare Os supranaviculare (i.e., os talonavicular dorsal, talonavicular ossicle, or Piere’s bone) Talar dorsal head and neck fracture Talar dorsal head and neck avulsion fracture Talar dorsal head and neck cortical fracture Talar neck fracture Talar neck stress fracture Talar neck fracture, nondisplaced (Hawkins 1) Talar head fracture Talar head fracture, nondisplaced Talar head fracture, displaced Talar head osteochondral lesion

Type 2A 2B Type 3A 3B Type 4A 4B Type

2

3

4

5

C.R. Hood Jr. et al. / The Journal of Foot & Ankle Surgery xxx (2017) 1–9

3

Table 4 Malvern classification system in detail Type

Pathology

1 1A

Accessory ossicles Os supratalare

1B

Os supranaviculare

2 2A

2B

3 3A 3B

4

5

Talar dorsal head and neck fracture Talar dorsal head and neck avulsion fracture

Talar dorsal head and neck cortical fracture

Talar neck fracture Talar neck stress fracture Talar neck fracture, nondisplaced (defined as Hawkins 1; Marti type 1)

Location

Incidence (%)

Mechanism

Imaging Studies

Accessory bone on dorsal aspect of talar neck Accessory bone on dorsal aspect of navicular, sometimes found intra-articularly at TNJ, close to midpoint

0.2 to 2.4

Developmental variation; congenital Developmental variation; congenital; can fuse with underlying bone

Lateral or oblique foot XR; sagittal foot MRI Lateral or oblique foot XR; sagittal foot MRI

Twisting (or abd/add) force applied to foot (plantarflexed position) causing injury to TNJ capsule (common in middle-age high heelwearing females); hyperplantarflexion (anterosuperior neck at attachment site of ankle capsule) Twisting (or abd/add) force applied to foot (plantarflexed position) causing injury to TNJ capsule (common in middle-age high heelwearing females); hyperplantarflexion (anterosuperior neck at attachment site of ankle capsule)

Lateral or oblique foot XR; ankle XR

Dorsal margin of talar head and neck; related to soft tissue insertions of dorsal talonavicular ligament, deep anteroinferior tibiotalar ligament, anterior ankle capsule; loose fragments seen in soft tissue; potential for concomitant navicular avulsion fracture Dorsal margin of talar head and neck, close to or with possible extension to TNJ; related to soft tissue insertions of dorsal talonavicular ligament, deep anterior tibiotalar ligament, anterior ankle capsule; larger size, with appreciated cortical discontinuity

1.0 to 3.5

0.5 to 2; most common avulsion at anterosuperior neck at anterior ankle capsule

Unknown; reported on case series basis

Lateral or oblique foot XR; CT

Talar neck, paralleling TNJ in cancellous region of bone Talar neck, vertical in orientation; fracture is isolated and nondisplaced, without subluxation

0.047 (military population)

Insufficiency and fatigue

Lateral foot XR; bone scan; MRI

Talar neck fractures constitute 50% of all talar fractures; isolated Hawkins type 1 account for 5 to 20

Forced dorsiflexion; MVA; FFH

Lateral foot XR; MRI or CT

Talar head articular surface at TNJ

Account for 2.6 to 10 of all talar injuries; reported to be least common of all talar fractures

Hyperdorsiflexion; compressive load through sustentaculum of calcaneus; axial compressive force through talar head from navicular in plantarflexed foot causes 2 fracture patterns: (1) articular crush with communition and (2) shear fracture; articular crush seen in area of middle facet Hyperdorsiflexion; compressive load through sustentaculum of calcaneus; axial compressive force through talar head from navicular in plantarflexed foot causes 2 fracture patterns: (1) articular crush with communition and (2) shear fracture; articular crush seen in area of middle facet Acute versus chronic repetitive trauma; nonunion of OCL fragment or SCB

Oblique or Canale and Kelly foot XR; ankle mortise XR; CT; live fluoroscopic TNJ stress or plain film anteroposterior XRs (fully inverted and everted) to determine joint and fragment stability

4A

Talar head fracture Nondisplaced talar head fracture

4B

Displaced talar head fracture

Talar head articular surface at TNJ

Account for 2.6 to 10 of all talar injuries; reported to be least common of all talar fractures

Talar head OCL

OCL adjacent to SCB plate at TNJ articulation

Rare

Oblique or Canale and Kelly foot XR; ankle mortise XR; CT; live fluoroscopic TNJ stress or plain film anteroposterior XRs (fully inverted and everted) to determine joint and fragment stability

Lateral foot XRs; MRI

Abbreviations: abd, abduction; add, adduction; CT, computed tomography; FFH, fall from height; MRI, magnetic resonance imaging; MVA, motor vehicle accident; OCL, osteochondral lesion; SCB, subchondral bone; TNJ, talonavicular joint; XR, radiograph.

imaging, such as MRI or CT, could be necessary to correlate the clinical symptoms if osseous pathology is not apparent or the pain level does not parallel the radiographic findings. Mickel et al (6) in 2008 reported a case in which the patient’s XR and CT scan demonstrated a

talar neck avulsion fracture. However, the continued pain that was out of proportion with the findings prompted a MRI study, which revealed a nondisplaced talar neck fracture (6). Additionally, MRI can be helpful for determining the “acuteness” of the pathology by the increased

4

C.R. Hood Jr. et al. / The Journal of Foot & Ankle Surgery xxx (2017) 1–9

Fig. 1. (Top) Borders of the talar neck shown on 3-dimensional computed tomography scan and radiograph. Lines divide the talus into 3 regions: head, neck, and body. (Bottom) Image showing vascular anatomy of the talus. Reproduced, with permission, from Melenevsky et al (5).

Table 5 Treatment options stratified by Malvern classification system Type

Pathology

1

2A 2B

Accessory ossicles Os supratalare Os supranaviculare Talar dorsal head and neck fracture Talar dorsal head and neck avulsion fracture Talar dorsal head and neck cortical fracture

3A 3B

Talar neck fracture Talar neck stress fracture Talar neck fracture, nondisplaced

1A 1B 2

3

4

Talar head fracture 4A 4B

5

Nondisplaced talar head fracture Displaced talar head fracture

Talar head OCL

Treatment WB in CAM boot if symptomatic; excision if symptomatic or recalcitrant WB in CAM boot if symptomatic; excision if symptomatic or recalcitrant Most will be stable, warranting no specific management CR with WB in CAM boot for 2 to 6 wk; excision if symptomatic; if deemed unstable, ORIF with KWs or mini-rail for 6 wk with NWB, advancement to WB after fixation removal Activity modification for 2 to 4 wk; case report detailed treatment with NWB in SLC for 3 wk NWB in CAM/SLC for 6 to 8 wk, followed by WB in CAM for another 4 to 8 wk; conservative treatment reserved for true nondisplaced neck fractures CR versus ORIF, depending on instability, comminution, and articular nature; stress test of TNJ to evaluate for same NWB for 4 to 8 wk in CAM/SLC with radiographic evidence of healing noted at w6 to 8 wk ORIF with NWB for 6 to 12 wk in SLC; published data recommend excision of fragments if <50% of articular surface and attempted reduction if >50% of articular surface; anatomic reduction key to reduce likelihood of TNJ osteoarthritis or AVN; fusion should be considered for severe comminution Short period of rest with anti-inflammatory medication and activity modification; operative treatment reserved for persistently painful lesions or if OCL fragment separates from SCB

Abbreviations: AVN, avascular necrosis; CAM, controlled ankle motion; CR, closed reduction; KWs, Kirschner wires; NWB, non-weightbearing; ORIF, open reduction and internal fixation; SCB, subchondral bone; SLC, short leg cast; TNJ, talonavicular joint; WB, weightbearing.

C.R. Hood Jr. et al. / The Journal of Foot & Ankle Surgery xxx (2017) 1–9

5

Fig. 2. Radiographic views of type 1A, os supratalare, an accessory ossicle located on the dorsal aspect of the talar head and/or neck. Images courtesy of the senior author (J.R.M.).

uptake around the lesion versus an accessory ossicle or any ligamentous insufficiency. MRI can also be helpful in evaluating osteochondral lesions (OCLs), bone marrow lesions, and stress fractures (10). Sormaala et al (11) reported that 67% (n ¼ 40) of all talar stress fractures occurred in the talar head, with 75% of these in the upper half. CT scans can help in visualizing cortical breaks or articular extension of various fracture patterns and are recommended routinely for any suspected talar fracture. Rarely occurring in isolation, talar fractures have a reported association with articular disruptions and fractures of adjacent bones in 67% and 77% of cases, respectively (12). Dale et al (12) reported that CT imaging provided additional fracture information, including greater extension of the fracture, additional fractures of adjacent bones, intra-articular bone fragments, and dislocations not seen on XRs in 93% of talar fracture (all variants) cases. Most of the classified pathology will heal with conservative treatment, consisting of a period of PWB in a CAM boot. Certain patterns will require a period of NWB (3,13). If pain becomes recalcitrant, many of these small ossicles or avulsion fragments can be excised. ORIF should be reserved for fragments that are large, intra-articular >50%, or comminuted (13). Fracture patterns that jeopardize the motion to the subtalar joint (STJ) or TNJ should be anatomically reduced and fixed when necessary. Examples include Malvern types 3B and 4A-B, in which the talar component of the STJ middle facet can hinder sustentaculum motion across this joint (9). Furthermore, comminution of the talar head can cause medial column shortening and muscular imbalance (9). Overall, the rate of healing to this area is high owing to the vascular supply by the periosteal branches of the dorsalis pedis and peroneal arteries (14) (Fig. 1). The Hawkins 1 variant (Malvern type 3B) and talar head

(Malvern type 4) pose the greatest risk of avascular necrosis (AVN) because these have a higher energy etiology, although the AVN rates for Malvern 3B/Hawkins 1 fractures have been reported at approximately 10% (3,13). Talar head/neck stress fractures (Malvern 3A) also pose a risk owing to a cited median delay in diagnosis of 40 and 85 days for the upper and lower talar head, respectively (11). The difference in the delay can be attributed to upper head injuries presenting with greater pain. Specifically considering each of the injury types, the imaging options for identification and the treatment options would seem to be the most helpful to clinicians when evaluating and treating patients with such injuries. When evaluating the accessory ossicles, Malvern types 1A (os supratalare) (15–18) and 1B (os supranaviculare) (15–18) can be easily seen on lateral and oblique XRs or sagittal MRI studies (Figs. 2 and 3). Often, it is important to correlate the ossicle finding with the mechanism of the presenting injury or symptoms, because these “ossicles” could be incidental findings or avulsion fragments (Malvern type 2A) (15). The treatment of both typically involves rest using PWB in a CAM boot until the symptoms decrease such that it is comfortable for the patient to transition back to normal foot gear and activity. Potential complications include exostosis formation or intra-articular impingement, which can result in dorsal foot irritation. If this occurs, excision of the fragment or exostosis is suggested. Talar dorsal head and neck fractures, whether avulsion (Malvern 2A) (7,15,19–24) or cortical break (Malvern 2B) (7,15,19–21), are often seen on lateral or oblique XRs (Figs. 4 and 5). Additionally, discontinuity in the S-shaped cyma line with the presence of fragments suggests ligamentous disruption and acute injury (21). Avulsion fractures can be distinguished from accessory ossicles by history (e.g., trauma), physical

Fig. 3. Radiographic views of type 1B, os supranaviculare, an accessory ossicle located on the proximal dorsal aspect of the navicular or talonavicular joint. (Left) Clinical radiograph of a patient presenting to the senior author’s clinic with fifth metatarsal pain. The patient was noted to have a base fracture with this ossicle as an incidental finding. Images courtesy of the senior author (J.R.M.).

6

C.R. Hood Jr. et al. / The Journal of Foot & Ankle Surgery xxx (2017) 1–9

Fig. 4. Radiographic views of type 2A, small avulsion (Left) and slightly larger avulsion (Right) fracture off the dorsal talar neck, with concurrent dorsal navicular avulsion fracture (Left and Right). The patient presented to the senior author’s office after a hyperplantarflexion and inversion injury mechanism. Images courtesy of the senior author (J.R.M.).

examination findings of swelling, bruising, and tenderness, or a radiographic lack of osseous cortical continuity (22). A reported 60% of these injuries will be missed in normal “ankle sprain” suspected mechanisms when the talus is skipped using the Ottawa ankle rule diagnosis scheme (7). More lateral fragments (lateral neck/body) can represent anterior talofibular ligament avulsions (insertion: anterior border of lateral articular surface on the talar neck). However, it is more common for anterior talofibular ligament avulsions to occur at the fibular end (origin: anterosuperior lateral malleolus tip) in vivo for histopathologic reasons (23). Because of difficulties in appreciating type 2A fractures on standard views, Miyamoto et al (24) developed a radiographic technique to assist in visualization. Treatment includes rest, similar to that for Malvern type 1A-B. Talar head and neck cortical fractures can result in instability in the Chopart joint (i.e., talonavicular and calcaneocuboid); demonstration of this instability warrants surgical correction to stabilize healing (21). Otherwise, CR with PWB in a CAM boot for 2 to 6 weeks can be used. On return to normal activity, excision might be warranted if the patient becomes symptomatic. If deemed unstable at the initial evaluation, treatment should be ORIF with Kirschner wires or mini-rail fixation for 6 weeks with NWB, followed by PWB in a CAM boot after fixation removal and a subsequent return to normal shoe gear as pain dictates (21). Talar neck pathology includes stress fractures (Malvern 3A) (11,25,26) and full fractures (Malvern 3B) (1,3,5,12,14,27,28) (Figs. 6 and 7). Both types can be appreciated on lateral XRs or CT and MRI

series. Stress fractures on XRs are usually normal in the acute setting, with linear sclerosis paralleling the TNJ appreciated 3 to 4 weeks later. Bone scans will show focal uptake, and MRI will show a decreased signal intensity fracture line on all sequences, with increased signal adjacent seen on T2-weighted images (25). Anterior talar neck stress fractures are more often associated with navicular stress fractures (11). During the physical examination, one should evaluate for soft tissue swelling, erythema, point tenderness, and local pain that is subjectively relieved with rest and exacerbated with continued activity (25). Malvern type 3B (i.e., Hawkins 1; Marti type 1) fractures have a 0% to 13% incidence of talar AVN, while the incidence of STJ arthritis is rare. One should evaluate for concomitant calcaneal and spinal fractures if the mechanism was high energy. A study by Dale et al (12) showed that most talar neck fractures extend from the talar body or head. Treatment of Malvern type 3A fractures has ranged from activity modification for 2 to 4 weeks to NWB in a short leg cast (SLC) for 3 weeks, with subsequent PWB until transitioning to normal shoe gear (11). Malvern 3B fractures should be treated with NWB in a CAM boot or SLC for 6 to 8 weeks followed by PWB in a CAM boot for another 4 to 8 weeks. Conservative treatment should be reserved for true nondisplaced talar neck fractures, although ORIF could be necessary for displaced talar neck fractures (5). Talar head fractures can be nondisplaced (Malvern 4A) or displaced (Malvern 4B) (1,5,9,10,12,13) (Figs. 8 and 9). Both are best seen on oblique or Canale and Kelly foot XRs, ankle mortise XRs, or CT

Fig. 5. Radiographic views of type 2B, dorsal talar neck avulsion cortical fracture. The patients presented to the senior author’s office after a hyperplantarflexion injury mechanism. Notice larger size compared to avulsion fractures. Images courtesy of the senior author (J.R.M.).

C.R. Hood Jr. et al. / The Journal of Foot & Ankle Surgery xxx (2017) 1–9

7

Fig. 6. (A) Type 3A, talar neck stress fracture, seen on T1-weighted magnetic resonance imaging sequence. Reproduced, with permission, from Bischoff et al (27). (B) Talar neck stress fracture on (Left) T1-weighted and (Right) T2-weighted magnetic resonance imaging sequence of the patient presenting to the senior author’s office. Images courtesy of the senior author (J.R.M.).

series. One should look for accompanying subluxation or dislocation or adjacent bone fractures. These fractures are often found with STJ instability or dislocation or lateral column injuries (cuboid) (9). To assess the stability of fractures at the TNJ (displaced versus nondisplaced), live fluoroscopic TNJ stress testing or plain film anteroposterior XRs (fully inverted and everted) should be used to determine joint and fragment stability (9). Treatment has varied between CR and ORIF, depending on instability, comminution, and articular nature (13). Type 4A injuries are typically treated with NWB for 4 to 8 weeks in a CAM boot or SLC with radiographic evidence of healing noted at approximately 6 to 8 weeks. Type 4B should be treated by ORIF with NWB for 6 to 12 weeks in SLC. The published data have recommended excision of fragments if <50% of the articular surface and attempted reduction if >50% of the articular surface is involved. Anatomic reduction is key to reducing the likelihood of TNJ osteoarthritis and AVN (5). Primary fusion should be considered for severe comminution. Early et al (9) provided surgical techniques for this injury. Overall, these fractures will often be nondisplaced owing to the strong intertarsal ligaments. One should stress nondisplaced fractures to confirm stability of the fragment and TNJ (9). CR can be hindered by head penetration through the extensor retinaculum. Once a fracture has been identified on XR, a CT scan should be ordered to evaluate the extent of articular extension and degree of displacement or rotation and determine whether any talar neck involvement is present (5). Malvern type 4B has a reported 10% rate of AVN in talar head fractures (13).

Talar head osteochondral lesions (Malvern type 5) can be viewed as injuries similar to those of the talar dome (10) (Figs. 10 and 11). Malvern type 5 injuries are best visualized using the same modalities used for Malvern type 4, which will show radiographic findings of a sclerotic margin around a radiolucent defect at the head. MRI series will show a decreased T1-weighted or increased T2-weighted signal intensity in the subchondral bone, indicative of potential loss of cartilage integrity. Conservatively, a short period of rest with antiinflammatory medication and activity modification is suggested. Operative treatment can be reserved for persistently painful lesions or if OCL fragments separate from the subchondral bone, with core decompression or bone marrow-simulating techniques as options for treatment. Fusion should be reserved for chronic and persistent pain. Findings from the reported cases (n ¼ 4) have shown that lesions can persist radiographically despite patients being asymptomatic. This suggests that more aggressive treatments can be reserved for symptomatic patients (10). The present study had several limitations. We realize that an internal practice audit with years of data available would have been ideal to further define the particular pathology of the talar head and neck, with accompanying details such as the rate of incidence, patient-stated mechanism of injury, mode of discovery, and so forth; however, this was not practical. This was attempted through an International Classifications of Disease (ICD), versions 9 and 10, patient search. The office ICD audit was not all inclusive for multiple reasons. Because the study was retrospective and included data from the

Fig. 7. (Left) Lateral radiographic view of type 3B, talar neck nondisplaced fracture. Note fracture extending to the subtalar joint posterior facet. Reproduced, with permission, from Herring (28). (Right) Talar neck nondisplaced fracture (arrow) seen on sagittal computed tomography scan. Note fracture extending to subtalar joint posterior facet. Reproduced, with permission, from Melenevsky et al (5).

8

C.R. Hood Jr. et al. / The Journal of Foot & Ankle Surgery xxx (2017) 1–9

Fig. 8. Type 4A, talar head fractures seen as (Left) sheer, (Middle) sheer with nonreducible medial subluxation of the talonavicular joint, and (Right) sheer with middle facet comminution and impaction. Reproduced, with permission, from Early et al (9).

practice of 3 foot and ankle physicians, no standardization in practice methods were used among them (e.g., how one defines the pathology, choice in ICD code used, collection of patient information, and recording of details); thus, consistent medical data documentation to allow for measured patient discovery was not possible. Pertaining to the codes used for discovery, patients might not have been identified if the physician had not coded the fracture specifically (e.g., using neck or avulsion) and used a general talar fracture code. Furthermore, it was impossible to identify stress fracture injuries to the talus owing to the lack of a specific code and most likely a generic code was used of bone marrow edema (code D75.89) or stress fracture of the foot (codes M84.374A, M84.375A). Searching for these codes would have resulted in a plethora of patient data to analyze. Additionally, no code exists for talar head fracture. Also, the nature of the ICD, version 10, limits the types of fractures that could be quantified in an office audit. Finally, because the study was retrospective, subjectivity was present regarding how each physician initially defined the pathology (e.g., os supratalare versus talar head/neck avulsion fracture) and how the preparing author (C.R.H.) defined this. Thus, the internal audit was

abandoned, and a full, comprehensive, published data search was performed, as demonstrated. Although academic in nature, we hope our classification system will increase awareness of talar head and neck injuries that have not been well reported in published studies. As Mickel et al (6) and Schmitt et al (21) revealed, greater pathology can be masked and ignored when just a simple avulsion fracture is visualized on XRs. As more case series or retrospective reviews are performed and reported, more information will be gained regarding the incidence, treatment, and long-term outcomes. In conclusion, case reports are very rare regarding the individual instances of this talar head and neck pathology. Although true talar neck fractures have been classified adequately (Hawkins type 1), other pathologic entities such as accessory ossicles, neck avulsion fractures, neck cortical fractures, neck stress fractures, and head OCLs have not been adequately classified. In the present report, we sought to further advance the recognition and knowledge of talar head and neck pathology and give context to these fracture patterns to assist the physician in the clinic.

Fig. 9. Type 4B, talar head sheer fracture minimally displaced, seen on (Left) anteroposterior radiograph and (Right) axial computed tomography scan. Reproduced, with permission, from Melenevsky et al (5).

C.R. Hood Jr. et al. / The Journal of Foot & Ankle Surgery xxx (2017) 1–9

9

Fig. 10. Type 5, talar head osteochondral lesion, seen on (Left) lateral radiograph and (Right) sagittal T1-weighted magnetic resonance imaging sequence. Reproduced, with permission, from Thacker et al (10).

Fig. 11. Type 5, talar head osteochondral lesion, seen on (Left) sagittal T1-weighted and (Right) T2-weighted magnetic resonance imaging sequences. Note loss of cartilage/subchondral bone plate with underlying bone marrow edema. Image courtesy of the senior author (J.R.M.).

References 1. Summers NJ, Murdoch MM. Fractures of the talus: a comprehensive review. Clin Podiatr Med Surg 29:187–203, 2012. 2. Berndt AL, Harty M. Transchondral fractures (osteochondritis dessecans) of the talus. J Bone Joint Surg Am 41A:988–1020, 1959. 3. Hawkins LG. Fractures of the neck of the talus. J Bone Joint Surg 52:991–1002, 1970. 4. Sneppen O, Buhl O. Fractures of the talus. Acta Orthop Scand 45:307–320, 1974. 5. Melenevsky Y, Mackey RA, Abrahams MRB, Thomson NB III. Talar fractures and dislocations: a radiologist’s guide to timely diagnosis and classification. Radiographics 35:765–779, 2015. 6. Mickel TJ, Andersen R, Keeling J, McKenna P. Occult talar neck fracture associated with talar avulsion diagnosed by MRI: a case report. Foot Ankle Int 29:956–958, 2008. 7. Robinson KP, Davies MB. Talus avulsion fractures: are they accurately diagnosed? Injury 46:2016–2018, 2015. 8. Thomas JL, Boyce BM. Radiographic analysis of the canale view for displaced talar neck fractures. J Foot Ankle Surg 51:187–190, 2012. 9. Early JS. Management of fractures of the talus: body and head regions. Foot Ankle Clin 9:709–722, 2004. 10. Thacker MM, Dabney KW, Mackenzie WG. Osteochondritis dissecans of the talar head: natural history and review of literature. J Pediatr Orthop 21:373–376, 2012. 11. Sormaala MJ, Niva MH, Kiuru MJ, Mattila VM, Pihlajam€ aki HK. Bone stress injuries of the talus in military recruits. Bone 39:199–204, 2006. 12. Dale JD, Ha AS, Chew FS. Update on talar fracture patterns: a large level I trauma center study. AJR Am J Roentgenol 201:1087–1092, 2013. 13. Ibrahim MS, Jordan R, Lotfi N, Chapman AWP. Talar head fracture: a case report, systematic review and suggested algorithm of treatment. Foot 25:258–264, 2015. 14. Rammelt S, Zwipp H. Talar neck and body fractures. Injury 40:120–135, 2009.  E, Camins A, Danu  s M, Saurı A. Accessory ossicles 15. Mellado JM, Ramos A, Salvado and sesamoid bones of the ankle and foot: imaging findings, clinical significance and differential diagnosis. Eur Radiol 13(suppl 6):L164–L177, 2003.

16. Coskun N, Yuksel M, Cevener M, Arican RY, Ozdemir H, Bircan O, et al. Incidence of accessory ossicles and sesamoid bones in the feet: a radiographic study of the Turkish subjects. Surg Radiol Anat 31:19–24, 2009. lu M. The incidence of accessory bones of the foot and their clinical 17. Cilli F, Akc¸aog significance. Acta Orthop Traumatol Turc 39:243–246, 2005. 18. Nwawka OK, Hayashi D, Diaz LE, Goud AR, Arndt WF, Roemer FW, Malguria N, Guermazi A. Sesamoids and accessory ossicles of the foot: anatomical variability and related pathology. Insights Imaging 4:581–593, 2013. 19. Argyropoulos M, Clark D, Harvie P. Bilateral talar avulsion fractures secondary to seizure: a case report. J Foot Ankle Surg 51:373–374, 2012. 20. Schweitzer ME, Deely DM, Glaser JB. Helical CT of talar fractures. Skeletal Radiol 26:137–142, 1997. 21. Schmitt JW, Werner CML, Ossendorf C, Wanner GA, Simmen H-P. Avulsion fracture of the dorsal talonavicular ligament: a subtle radiographic sign of possible chopart joint dislocation. Foot Ankle Int 32:722–726, 2011. lu A, Demiryu € rek D, Firat A, Oznur A, Ozsoy MH. Differential diagnosis in 22. Bayramog a professional basketball player with foot pain: is it an avulsion fracture or an os supranaviculare? Joint Dis Relat Surg 20:59–61, 2009. 23. Kumai T, Takakura Y, Rufai A, Milz S, Benjamin M. The functional anatomy of the human anterior talofibular ligament in relation to ankle sprains. J Anat 200:457– 465, 2002. 24. Miyamoto W, Takao M, Nishiguchi K, Uchio Y. Technique tip: a radiographic projection for an avulsion fracture of the talar attachment of the anterior talofibular ligament. Foot Ankle Int 29:435–437, 2008. 25. Umans H, Pavlov H. Insufficiency fracture of the talus: diagnosis with MR imaging. Radiology 197:439–442, 1995. 26. Perry DR, O’Toole ED. Stress fracture of the talar neck and distal calcaneus. J Am Podiatry Assoc 71:637–638, 1981. 27. Bischoff MJ, Reininga IH, van Raaij TM. Atraumatic bilateral insufficiency fractures of the talar neck in a rheumatoid patient. J Foot Ankle Surg 52:231–234, 2013. 28. Herring W. Aviator’s fracture. Learning Radiology. Available at: http://learningradiology. com/mobile/imagesmobile/Aviator’s Fx.jpg. Accessed January 2, 2015.