Traumatic Injury to the Subtalar Joint

Current Lack of Evidence on Treatment Strategies and Clinical Outcomes for Osteochondral Lesions of the Subtalar, Talonavicular, and Calcaneocuboid Joints: A Systematic Review

OBJECTIVE

In contrast to osteochondral lesion (OCL) of the ankle, OCLs in other joints of the foot, such as subtalar joint, talonavicular joint, calcaneocuboid joint, and the midfoot, are rare conditions, but they can also lead to significant morbidity. The objective of this systematic review was to summarize the clinical evidence for the treatment of OCLs of the subtalar, talonavicular, calcaneocuboid, and the other midfoot joints.

DESIGN

A systematic search of the MEDLINE, EMBASE, and Cochrane Library databases was performed in January 2021 based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines by 2 independent reviewers. Included studies were evaluated with regard to LOE (level of evidence) and QOE (quality of evidence). Variable reporting outcome data, clinical outcomes, and complications were evaluated.

RESULTS

Seventeen studies with 21 patients were included, all of which were case reports (level 5) without any case series reporting greater than 3 patients. There were 5 patients with OCL in the subtalar joint, 15 patients in the talonavicular joint, and 1 patient in the calcaneocuboid joint. Thirteen case reports (4 subtalar joint, 8 talonavicular joint, and 1 calcaneocuboid joint) reported surgical treatment. Surgical procedures mainly included debridement, bone marrow stimulation, fixation, and bone grafting, through open or arthroscopy, all of which resulted in successful outcomes. Four case reports (1 subtalar joint, 3 talonavicular joint) reported successful conservative treatment. Other 13 case reports reported successful surgery after failed conservative treatment. No complications and reoperations were reported.

CONCLUSIONS

The current systematic review revealed that there is no available evidence to ascertain clinical outcomes of both conservative and surgical treatments for cartilage lesions in the talonavicular joint, subtalar joint, and the midfoot joints, owing to the extreme paucity of literature. Both nonoperative and operative treatments can be considered, but no treatment strategies have been established.

Comparison of different intraoperative reduction monitoring methods in a cadaveric intraarticular calcaneal fracture model: 3D scan vs arthroscopy vs nanoscopy

AIMS

Visualization of the subtalar joint surface in surgical management of calcaneal factures remains a big challenge and anatomic reduction of the articular surface is essential for a good clinical outcome. We hypothesize that video-assistance can provide superior fracture reduction compared to fluoroscopy and that nanoscopy (NSC) achieves more extensive visualization compared to fracturoscopy (FSC).

METHODS

Ten human cadaveric feet with artificially pre-fractured intraarticular calcaneal fractures with involvement of the posterior facet were treated via a minimal invasive subtalar approach. After initial control of reduction by 2D fluoroscopy, the reduction was further analyzed intraoperatively by FSC and NSC. 3D Scan served as gold standard control of reduction. Need of revision of reduction after the different visualization techniques was recorded and the extent of visualization of the subtalar joint surface in the medio-lateral dimension was compared for FSC and NSC. To quantify access and visualization of the medial and posterior facet, a depth gauge was used to measure from laterally at the clinically widest portion of the calcaneus targeted to the sustentaculum tali. The distance in millimetres was referred to the complete medio-lateral distance seen on paracoronal CT at the widest portion of the calcaneus.

RESULTS

Fracture analysis in preoperative CT-scans according to Sanders classification revealed four type IC, two IIA, three IIC and one IIIAC fractures. Mean visualization of the medial and posterior facet was significantly improved with NSC (30.4 ± 3.78 mm) compared to FSC (23.6 ± 6.17 mm) (p = 0.008). An imperfect reduction requiring revision was more often required with NSC compared to FSC. Insufficient reduction using video-assistance was found in two cases.

CONCLUSION

In order to optimize subtalar joint reduction and congruency, video-assisted techniques, especially NSC, provide superior visualization and thus can improve reduction in the surgical treatment of intraarticular calcaneal fractures.

Imaging of osteoarthritis from the ankle through the midfoot

Ankle, hindfoot, and midfoot osteoarthritis (OA) is most commonly posttraumatic and tends to become symptomatic in younger patients. It often results from instability due to insufficiency of supportive soft tissue structures, such as ligaments and tendons. Diagnostic imaging can be helpful to detect and characterize the distribution of OA, and to assess the integrity of these supportive structures, which helps determine prognosis and guide treatment. However, the imaging findings associated with OA and instability may be subtle and unrecognized until the process is advanced, which may ultimately limit therapeutic options to salvage procedures. It is important to understand the abilities and limitations of various imaging modalities used to assess ankle, hindfoot, and midfoot OA, and to be familiar with the imaging findings of OA and instability patterns.

Study on Sustentaculum Tali Fragment Constancy in Intraarticular Calcaneus Fracture

OBJECTIVES

To establish reproducible measurements of the sustentaculum tali (ST) fragment regarding fracture classification and patient-related factors.

DESIGN

Retrospective.

SETTING

Trauma center, University Hospital.

PATIENTS

A retrospective analysis of the 142 fractured calcanei of 122 patients (101 men and 21 women) treated at our institution between 2012 and 2020 was performed. As control, 62 unaffected calcanei were used.

INTERVENTION

Radiographic images were evaluated twice within 2 weeks by 2 orthopaedic surgeons and 1 postgraduate student. Angulation and diastasis were used to distinguish ST fragment constancy based on computed tomography. Using these parameters, the prevalence of inconstant ST fragments was assessed. We also analyzed factors related to ST fragment inconstancy. Patient factors included age, body mass index, smoking, and diabetes. Radiographic factors included the Sanders classification, location of the outermost fracture line of the posterior facet, presence of an intraarticular fracture of the ST, and ST fragment width.

MAIN OUTCOME MEASUREMENTS

Angulation and diastasis were used to confirm the ST fragment constancy. Potential risks for inconstant ST fragment subsequently defined.

RESULTS

According to the criteria, ST fragment inconstancy was observed in 34.5%. ST fragment width was significantly smaller in the inconstant group ( P < 0.001). Severe comminution of the posterior facet ( P < 0.05), intraarticular fracture of the ST ( P < 0.001), and diabetes ( P < 0.05) were significantly higher in the inconstant group. The cut-off value of the ST fragment width was 20.5 mm.

CONCLUSIONS

In intraarticular calcaneus fractures, small ST fragment width, comminuted fracture, intraarticular fracture of the ST, and diabetes were associated with the inconstant group. The ST fragment was expected to be inconstant when the width was less than 20.5 mm.

A rare case of floated talar head accompanying medial subtalar dislocation

INTRODUCTION AND IMPORTANCE

Concomitant medial subtalar dislocation and a rotated displaced talar neck fracture may result in poor outcomes. This study aimed to explain this extremely rare injury and assess the clinical outcomes following surgical treatment.

CASE PRESENTATION

A 22-year-old Iranian man referred to the emergency department with a gross deformity and pain in his right foot and ankle after a falling from 2 m. Plain radiographs showed a rotated free talar head accompanying medial subtalar dislocation. Closed reduction was performed in the emergency department under sedation. Prompt open reduction and internal fixation of talar fracture was done, after removal of free osseocartilaginous fragments in the subtalar and talonavicular joints. At 25 months postoperatively, the clinical outcomes were assessed using the American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scale and visual analogue scale for pain which were 73 and 3, respectively. In exam, the patient had a stiffed subtalar joint without talar osteonecrosis or collapse.

CLINICAL DISCUSSION

Several osseous and soft tissue barriers could prevent a successful closed reduction of a subtalar dislocation. Associated cartilage injuries or fractures may result in poor clinical outcomes such as persistent pain, limping, osteoarthritis, and osteonecrosis. Immediate open reduction and rigid fixation of associated fractures and resection of small free osseocartilaginous fragments may prevent further soft tissue damages and preserve clinical functions.

CONCLUSIONS

Satisfactory clinical outcome could be expected following proper on-time approach to a subtalar dislocation associated with a rotated displaced talar neck fracture.

Calcaneal reconstruction using a femoral head allograft and biologic adjuncts: A case report

We present a case of calcaneal reconstruction after both an improvised explosive device injury and subsequent salvage procedures left the patient with a large calcaneal defect and damaged hindfoot soft tissue. A subtalar arthrodesis was performed with a femoral head allograft, where it was fused to the remaining calcaneus and superiorly through the talus, to successfully reconstruct this defect. Demineralized bone matrix, bone morphogenetic protein, and concentrated bone marrow aspirate were also added as adjuncts to promote bone remodeling. At final follow-up, the patient denied pain, was fully weight-bearing, and had resumed an active lifestyle. Level of Evidence: Level V, Case Report.

Approach to Displaced Intra-Articular Calcaneus Fractures After Attempted Suicide Among Patients With Psychiatric Disorders: Nonsurgical or Surgical?

Displaced intra-articular calcaneus fracture is one of the injurious events in psychiatric patients after high-jump suicide attempts. These patients are reported to have poorer compliance and worse postoperative outcomes compared to those with no psychiatric condition.  We aimed to compare nonsurgical and surgical treatment with respect to functional and radiological outcomes and complications in this patient. We evaluated medical records of 42 psychiatric patients who had displaced intra-articular calcaneal fractures after high-jump suicide attempt. 20 (54%) of these were treated nonsurgically and further 17 patients (46%) received surgical intervention. We compared to nonsurgical and surgical approaches statistically. The mean follow-up period were 30.4 ± 8.02 months and 31.8 ± 7.5 months in the nonsurgical and surgical groups, respectively. Böhler's angle was significantly higher in the surgical group (30.4 ± 6.4) than that in the nonsurgical group (16.1 ± 3.7) (p = .001). AOFAS scores and supination levels were significantly higher in the surgical group than that in the nonsurgical group (p ≤ .05). During the follow-up period, one patient from the surgical group re-attempted high-jump suicide and died, and another one caused the subtalar joint to re-collapse after full weightbearing on the first postoperative day. Surgical treatment of displaced intra-articular calcaneal fractures following a high-jump suicide attempt in psychiatric patients may not cause increased complication rates. However, behavioral manifestations of the psychiatric disorder might be associated with several complications. Should any surgical intervention be decided, minimal invasive approach would be the appropriate choice.

Closed isolated anterolateral calcaneal dislocation: a case report

Background

Complete isolated calcaneal dislocation, defined as dislocation of talocalcaneal and calcaneocuboid joints with intact talonavicular joint without significant fracture, is an exceedingly rare injury.

Case presentation

A 49-year-old man, after a motor vehicle collision, presented with a closed isolated anterolateral dislocation of the calcaneus associated with fracture of the sustentaculum tali, cuboid, lateral process of the talus, and avulsion fracture of superior peroneal retinaculum. Urgent successful closed reduction was immediately performed in the emergency room under sedation. Two days later, through sinus tarsi approach extended proximally to posterior of the lateral malleolus and distally to the calcaneocuboid joint, peroneal tendons were reduced in the retromalleolar groove and avulsion fracture of the superior peroneal retinaculum was reduced and fixed by a suture anchor. A chondral lesion (6 × 8 mm) was seen in the posterior facet of the calcaneus for that chondroplasty and microfracture were performed. Also, small bony fragments from the cuboid were excised. The reduced calcaneocuboid joint was fixed by two Kirschner wires. In the second stage, 10 days later, through medial approach to the talocalcaneal joint, multiple free bony fragments were excised. Then sustentaculum tali was reduced and fixed using a lag screw. Postoperatively, a non-weight bearing short leg cast was applied for six weeks. The patient had permission to start partial weight bearing 6 weeks after removal of K-wires. Finally, at the 10th postoperative week, he had full weight-bearing without any aid instrument. He was able to return to his regular activities about 6 months after the injury. At 34 months, the American Orthopaedic Foot and Ankle Society ankle-hindfoot scale was 92 from 100. The foot function index percentile was 7% and the visual analogue score for pain was 1.9. The last radiographs revealed normal configuration of talocalcaneal, calcaneocuboid, and talonavicular joints with a little joint space narrowing in posterior part of the subtalar joint.

Conclusion

Patients with isolated anterolateral calcaneal dislocations, even with multiple associated fractures, can have acceptable outcomes, if it is urgently diagnosed and properly managed.

Retrospective analysis of treatment strategies and clinical outcome of isolated talar dislocations

Talar dislocations are rare injuries of the foot and ankle and require quick and decisive diagnostic and therapeutic decisions. Evidence concerning the treatment and outcome of these injuries is sparse. The aim of this study was to analyze all talar dislocations of the last ten years treated in a large German level I trauma center in an effort to add to the experience on these injuries.

METHODS

All patients with a talar dislocation injury were retrospectively included. Medical reports, x-ray and computertomography scans were analyzed for the sex, age, trauma mechanism, and injury classifications as well as for the clinical outcome as measured by the Foot Function Index (FFI).

RESULTS

A total of 18 patients were included in this study: Luxatio pedis cum talo (n = 1), Luxatio tali totalis (n = 3), Luxatio pedis sub talo (n = 14). Analysis of the therapeutic algorithms revealed that only one patient was treated conservatively, the other 17 patients underwent operation. In most cases, stabilization was achieved using an external fixator and if necessary, the subtalar and talonavicular joints were temporarily stabilized using K-wires. The mean follow-up time was 4.25 years (2.05 SD) and the mean FFI-sum score 45.00 (42.26 SD). Two patients required subtalar fusion two years after the injury.

CONCLUSION

Isolated talar dislocations can have a good outcome and be effectively treated in the emergency setting by basic techniqes if neurovasular structures are not injured. Often, these injuries are associated with fractures of adjacent bones which then need complex reconstruction.

Subtalar Dislocations

Subtalar dislocations are uncommon injuries that involve disruption of the talocalcaneal and talonavicular joints. Whereas medial subtalar dislocations are usually caused by low-energy mechanisms and are reducible by closed means, lateral subtalar dislocations occur due to high-energy trauma, have associated foot injuries, and may require open reduction. Good outcomes can be expected for low-energy medial dislocations, whereas high-energy dislocations have guarded outcomes. Hindfoot deformity and chronic instability can result from nonanatomic reduction and inadequate stabilization. Arthrosis of the subtalar joint can occur despite anatomic reduction and is attributable to the cartilage damage at the time of injury.

Calcaneal Fractures-Which Approach for Which Fracture?

Treatment of calcaneal fractures has to be tailored to the individual pathoanatomy. If operative treatment is chosen, anatomic reconstruction of the calcaneal shape and joint surfaces is mandatory. For most of the displaced, intraarticular fractures, this can be achieved by less invasive reduction and fixation via a sinus tarsi approach, which may be extended along the "lateral utility" line for calcaneocuboid joint involvement or calcaneal fracture-dislocations. Purely percutaneous fixation is the treatment of choice for displaced extraarticular fractures and simple intraarticular fractures with adequate control of joint reduction. Specific approaches are used for rare calcaneal fracture variants.

Recognition, Treatment, and Outcome of Calcaneal Fracture-Dislocation

BACKGROUND

Calcaneal fracture-dislocations are rare but potentially disabling injuries that are regularly overlooked at first presentation. To date, only about 50 cases have been reported in the literature.

METHODS

Over a period of 8 years, 10 patients (average age 61.7 years) with acute fracture-dislocations of the calcaneus were treated at 2 level 1 trauma centers. The calcaneocuboid joint was involved in 9 patients. There was a concomitant fracture of the lateral talar process and of the tip of the distal fibula in 7 patients each. Open reduction and internal fixation was performed in 9 of 10 patients via an oblique lateral dislocation approach. One patient underwent primary subtalar fusion. All patients were seen for clinical and radiographic follow-up at an average of 3 years using patient-reported outcome scores.

RESULTS

Anatomic fixation was achieved in all patients as judged by postoperative computed tomographic imaging. In the 9 patients treated with internal fixation, the Foot Function Index averaged 12.8, the EuroQol 5D score averaged 0.89 and the visual analog scale score for patient satisfaction averaged 79.3 at final follow-up. Signs of mild subtalar arthritis were seen in 6 patients. No secondary subtalar fusions were needed.

CONCLUSION

When recognized and treated early, prognosis of calcaneal fracture-dislocation was favorable. A dislocation approach starting over the distal fibula, continuing over the sinus tarsi, and extending toward the calcaneocuboid joint allowed for adequate visualization of the subtalar joint and treatment of all components of the injury.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Outcomes of management of displaced intra-articular calcaneal fractures

Despite the advances in operative management, displaced intra-articular calcaneal fractures (DIAFCs) are often associated with long term sequelae, permanent disability, a considerable reduction in quality of life, and a high socio-economic cost. Randomized controlled trials have shown that patient reported outcomes of surgery are no better than those of nonoperative management. Methodological flaws and selection bias may have influenced the results, however, and subgroup analysis showed that some patients could benefit from surgery, whilst patients' preference can be the decisive factor in choosing a management modality. Fractures with significant lateral wall displacement predisposing to impingements often require surgery, and management has to be individualized and tailored to the patient. Surgery does not usually achieve excellent results, though it exposes the patient to potential risks and complications. Wound healing problems and infections affect around 20% of patients when the extensile lateral approach has been used. Sinus tarsi approach and minimally invasive surgery may be viable alternatives, offering similar results with fewer wound complications, but most of the available studies are of low to moderate quality. Late subtalar joint arthrodesis is often required: however, such procedure would be less technically difficult and could result in better foot function should the shape of the calcaneus have been anatomically restored with surgery in the acute phase.

[External fixator: temporary fixation and soft tissue management of the ankle]

OBJECTIVE OF SURGERY

Joint-spanning transfixation of the ankle joint aims at mostly temporary retention of the reduction, i.e. restoring length and axial alignment and stabilization of the ankle mortise in highly unstable fractures around the ankle and under critical soft tissue conditions. In selected cases, external fixation serves as an additional stabilization also following completed internal fixation or the fracture can be treated in the external fixator. The goal of surgery is to allow quick soft tissue recovery, prevention of redislocation and stabilization of the ankle and adjacent structures.

INDICATIONS

a) Fractures of the tibial pilon; b) very distal, extra-articular lower leg fractures (without the option for pin positioning in the distal fragment); c) highly unstable malleolar fractures with tendency to subluxation and dislocation fractures; d) critical soft tissue conditions around the ankle; e) dislocation fractures of the talus, Chopart and Lisfranc joints (if necessary with additional transarticular transfixation).

CONTRAINDICATIONS

Missing consent to surgery by the conscious patient, life-threatening general condition by other prioritized injuries.

SURGICAL TECHNIQUE

Percutaneous pin placement of the appropriate caliber into so-called safe zones of the tibia, metatarsus and calcaneus, as needed. Additional transfixation of the Chopart and Lisfranc joints with K‑wires as needed. Fixation of the struts with the foot in a neutral position. Besides consideration of biomechanical principles, pin placement must be done in anticipation of the definitive stabilization and future approaches respecting the anatomical structures while achieving maximum stability and soft tissue protection.

POSTOPERATIVE MANAGEMENT

Following initial transfixation, elevation of the injured leg for soft tissue protection, local cooling and bed rest are indicated. In cases of compartment syndrome and open fractures with temporary soft tissue coverage, second look surgery after 24-72 h is mandatory. For exact fracture analysis and optimal planning of the definitive surgical strategy, the indications for CT imaging should be generously considered. The timing of definitive care depends on the local soft tissue status and the overall condition of the patient.

RESULTS

The presence of a dislocation at the time of the accident represents a negative prognostic factor for ankle fractures. Higher rates of posttraumatic arthrosis are also found in pilon fractures and trimalleolar fractures, direct cartilage damage and rupture of the syndesmosis. In cases of anatomic reconstruction of the mortice and ankle joint congruence, good to excellent results can be achieved in 75-89%.

Managing Severely Malunited Calcaneal Fractures and Fracture-Dislocations

Severe calcaneal malunions are debilitating conditions owing to substantial hindfoot deformity with subtalar arthritis and soft tissue imbalance. Type III malunions are best treated with a subtalar distraction bone block fusion. Additional osteotomies may be required for severe varus or superior displacement of the calcaneal tuberosity. Type IV malunions result from malunited calcaneal fracture-dislocations and require a 3-dimensional corrective osteotomy. Type V malunions warrant additional ankle debridement and reconstruction of the calcaneal shape to provide support for the talus in the ankle mortise. Accompanying soft tissue procedures include Achilles tendon lengthening, peroneal tendon release, and rerouting behind the lateral malleolus.

Talus Secundarius: Case Series

BACKGROUND

Talus secundarius is a very rare accessory bone at the lateral border of the foot. It is attached via a synchondrosis or small synostosis to the lateral aspect of the talar body and has additional facets to the tip of the lateral malleolus and the superior aspect of the calcaneus.

METHODS

Over a period of 8 years, we have seen 5 patients with 6 cases of talus secundarius with an average age of 17 years at first presentation to the senior author. One ossicle was an incidental finding and completely asymptomatic. In the other 5 cases, the average duration of symptoms was 21 months at that time. In 3 cases, additional accessory bones were seen around the talus.

RESULTS

The average size of the ossicles was 18 × 12 × 8 mm. Complete removal resulted in considerable pain reduction without further functional restriction in 4 cases. Two cases (1 asymptomatic, 1 with mild intermittent symptoms) were treated nonoperatively. The average Foot Function Index improved from 22.6 to 4.8 in all patients and from 31.0 to 4.5 in the patients treated with excision for symptomatic talus secundarius (P < .01).

CONCLUSION

The knowledge of accessory bones at the foot is important, as missed diagnosis may lead to prolonged course of pain and unnecessary protection in the affected patients. Resection of symptomatic ossicles substantially reduces pain, but patients have to be counseled that some symptoms may prevail in a congenital deformity.

LEVEL OF EVIDENCE

Level IV, prospective case series.

Centre of Rotation of the Human Subtalar Joint Using Weight-Bearing Clinical Computed Tomography

Accurate in vivo quantification of subtalar joint kinematics can provide important information for the clinical evaluation of subtalar joint function; the analysis of outcome of surgical procedures of the hindfoot; and the design of a replacement subtalar joint prosthesis. The objective of the current study was to explore the potential of full weight-bearing clinical computed tomography (CT) to evaluate the helical axis and centre of rotation of the subtalar joint during inversion and eversion motion. A subject specific methodology was proposed for the definition of the subtalar joint motion combining three-dimensional (3D) weight-bearing imaging at different joint positions with digital volume correlation (DVC). The computed subtalar joint helical axis parameters showed consistency across all healthy subjects and in line with previous data under simulated loads. A sphere fitting approach was introduced for the computation of subtalar joint centre of rotation, which allows to demonstrate that this centre of rotation is located in the middle facet of the subtalar joint. Some translation along the helical axis was also observed, reflecting the elasticity of the soft-tissue restraints. This study showed a novel technique for non-invasive quantitative analysis of bone-to-bone motion under full weight-bearing of the hindfoot. Identifying different joint kinematics in patients with ligamentous laxity and instability, or in the presence of stiffness and arthritis, could help clinicians to define optimal patient-specific treatments.

Natural Value of Böhler's Angle in Normal Chinese Population

Objective

To determine the value of Böhler's angle (BA) in a group of Chinese people, analyze possible factors that influence it, and compare BA with that in previous literature.

Methods

A total of 143 cases, aged from 4 to 79 years, were enrolled in the study, including 64 males and 79 females (79 left feet and 64 right feet). Radiographs were independently measured by six observers. Age, sex, body side, subtalar joint congruity (STJC), and X‐beam obliquity (TT) were recorded. The database was assessed based on intraobserver agreement, data distribution, the randomness of case selection, and the ratio equality of binomial variables. Then, the normal value of BA was established, as well as the correlation between BA and other parameters.

Results

In the present study, the interobserver reliability of BA, STJC, and TT was excellent. The BA data revealed a normal distribution, and the randomness of case selection was verified for age, sex, and body side. The ratio of sex and body side was equal. Homogeneity of variance was observed when comparing the value of BA between different groups. The value of BA was 31.6° ± 5.19° (range, 20.08°–47.19°), which was not related to age, sex, body side, and minor X‐ray beam obliquity. BA application was not suitable for individuals younger than 10 years. The mean value of BA in this study was not identical with those in previous reports. This demonstrated that BA varies for different races.

Conclusion

For Chinese people, 30° to 33° is recommended as the target value of BA for calcaneal fracture reduction, except in children under 10 years of age.

Influence of the ankle position and X-ray beam angulation on the projection of the posterior facet of the subtalar joint

OBJECTIVE

Using digitally reconstructed radiographs (DRRs), we determined how changes in the projection angle influenced the assessment of the subtalar joint.

MATERIALS AND METHODS

Weightbearing computed tomography (CT) scans were acquired in 27 healthy individuals. CT scans were segmented and processed to create DRRs of the hindfoot. DRRs were obtained to represent 25 different perspectives to simulate internal rotation of the ankle with and without caudal angulation of the X-ray beam. Subtalar joint morphology was quantified by determining the joint space curvature, subtalar inclination angle (SIA), calcaneal slope (CS), and projection of the subtalar joint line on three-dimensional (3-D) reconstructions of the calcaneus.

RESULTS

The curvature of the projected joint space was altered substantially over the different DRR projections. Simulated caudal angulation of the X-ray beam with respect to the ankle decreased the SIA and CS significantly. Internal rotation also had a significant impact on the SIA and CS if the X-ray beam was in neutral or in 10° of caudal angulation. An antero-posterior (AP) view of the ankle showed the posterior area of the posterior facet, whereas a more anterior area was visible with internal rotation of the foot and caudal angulation of the X-ray beam.

CONCLUSION

Internal rotation of the foot of 20° is recommended to assess the posterior aspect of the posterior facet, whereas a combined 20° internal rotation of the foot and 40° caudal angulation of the X-ray beam is best to assess the anterior aspect of the posterior facet of the subtalar joint.

Hindfoot Injuries: How to Avoid Posttraumatic Varus Deformity?

Posttraumatic hindfoot varus may result from nonoperative treatment or inadequate reduction and fixation of talar and calcaneal fractures. Adequate visualization of the talar neck via bilateral approaches is essential in avoiding malreduction. In cases of medial comminution of the talar neck, lag screws must be avoided and the use of single or double plates should be considered. A Schanz screw introduced into the calcaneal tuberosity is instrumental in realigning shortening, varus, or valgus deformity of the heel. Special attention should be paid to addressing impaction of the medial facet of both the talus and calcaneus to avoid hindfoot varus.