Abnormal Bone Morphology in Charcot-Marie-Tooth Disease

Background: Although long suspected, it has yet to be shown whether the foot and ankle deformities of Charcot-Marie-Tooth disease (CMT) are generally associated with abnormalities in osseous shape. Computed tomography (CT) was used to quantify morphologic differences of the calcaneus, talus, and navicular in CMT compared with healthy controls. Methods: Weightbearing CT scans of 21 patients (27 feet) with CMT were compared to those of 20 healthy controls. Calcaneal measurements included radius of curvature, sagittal posterior tuberosity-posterior facet angle, and tuberosity coronal rotation. Talar measurements included axial and sagittal body-neck declination angle, and coronal talar head rotation. Surface-mesh model analysis of the hindfoot was performed comparing the average of the CMT cohort to the controls using a CT analysis software (Disior Bonelogic 2.0). Means were compared with a t test ( P < .05). Results: CMT patients had significantly less talar sagittal declination vs controls (17.8 vs 25.1 degrees; P < .05). Similarly, CMT patients had less talar head coronal rotation vs controls (30.8 vs 42.5 degrees; P < .001). The calcaneal radius of curvature in CMT patients was significantly smaller than controls (822.8 vs 2143.5 mm; P < .05). CMT sagittal posterior tuberosity–posterior facet angle was also significantly different from that of controls (60.3 vs 67.9 degrees respectively; P < .001). Surface-mesh model analysis demonstrated the largest differences in morphology at the navicular tuberosity, medial talar head, sustentaculum tali, and anterior process of the calcaneus. Conclusion: This is the first study to quantify the morphologic differences in hindfoot osteology seen in CMT patients. Patients identified with osseous changes of the calcaneus, especially a smaller axial radius of curvature, may benefit from a 3-dimensional osteotomy for correction.

The Plantar Fascia Talar Head Correlation: A Radiographic Parameter With a Distinct Threshold to Validate Flatfoot Deformity and Its Corrective Surgery on Conventional Weightbearing Radiographs

Background: Corrective surgery for flexible flatfoot deformity (FD) remains controversial, and one of the main reasons for this is the lack of standardized radiographic measurements to define an FD. Previously published radiographic parameters to differentiate between a foot with and without an FD do not have a commonly accepted and distinct threshold. Methods: The plantar fascia–talar head correlation (PTC) with its defined threshold was assessed by measuring the distance between the medial border of the plantar fascia and the center of the talar head (DPT) on conventional dorsoplantar and lateral weightbearing radiographs; the authors were blinded to the clinical diagnosis of the 189 patients’ first visits. Feet were sorted into groups with and without an FD based on their clinical examination. The effect of operative corrections of FD on the PTC was retrospectively evaluated on an additional 38 patients. Results: The sensitivity of the PTC was 0.98 (95% CI: 0.9-1) and specificity 0.96 (95% CI: 0.92-0.98), respectively, to identify an FD, consistent with the clinical examination. Thirty-five of 38 surgeries sufficiently corrected the FD and the PTC comparable to that in subjects without an FD. Three corrections with a residual FD did not adequately correct the PTC. Conclusion: The PTC is a reliable radiographic parameter with a distinct threshold that is sensitive and specific for the differentiation of feet with and without an FD including feet with and without residual FD after corrective surgery. The PTC is applicable to monitor the needed intraoperative amount of correction using simulated weightbearing fluoroscopy. Level of Evidence: Level III, diagnostic.

Single Medial vs 2-Incision Approach for Double Hindfoot Arthrodesis: Is There a Difference in Joint Preparation?

Background: Double hindfoot arthrodesis is a reliable treatment option in lower extremity deformity and arthritis. Single (medial) and 2-incision techniques have been described. The purpose of this study was to evaluate the extent of cartilage debrided in each approach and to evaluate the competency of the deltoid ligament. Methods: Eight matched pairs of cadaveric specimens were acquired. One limb from each pair was randomly assigned to the single medial incision and the other to the 2-incision technique. Stress radiographs were obtained prior to dissection to evaluate for valgus tibiotalar tilt. The talonavicular and subtalar articular surfaces were denuded of cartilage and the joints disarticulated. The percentage of cartilage debrided was determined using ImageJ software. Postoperative tibiotalar tilt was measured with a technique and threshold previously described by our group. The intraclass correlation coefficient was calculated to determine inter- and intraobserver reliability. Results: The single medial incision demonstrated significantly less cartilage denuded than the 2-incision technique at the talar head (61.1% ± 20.4% vs 88.1% ± 6.1%, P < .001), and the posterior facets of the talus (53.5% ± 7.6% vs 73.6% ± 7.0%, P < .001) and calcaneus (55.3% ± 16.5% vs 81.0% ± 7.4%, P = .001). Overall, 75% of specimens that underwent a single medial incision approach demonstrated increased valgus tibiotalar tilt postdissection, whereas none that underwent the 2-incision technique developed increased tibiotalar tilt ( P < .01). The average tibiotalar tilt among these specimens was 4.6 ± 1.3 degrees (range 2.5-5.7 degrees). For all measurements, the intraclass correlation coefficient was greater than 0.8. Conclusion: The posterior facet of the subtalar joint and talar head are at risk of subtotal debridement, as well as increased tibiotalar tilt with the single medial incision technique. Adequate debridement may require greater soft tissue dissection, possibly at the expense of medial ankle stability. Level of Evidence: Level III, retrospective cohort study.

Management and Outcome of Hindfoot Trauma With Concomitant Talar Head Injury

Background: Talar head fractures account for 2.6% to 10% of all talar fractures and are often associated with concomitant musculoskeletal injuries. The current literature only describes a total of 14 patients with talar head fractures and, with that, guidelines for management are lacking. The aim of the current study was to evaluate the management and long-term outcome of patients who have hindfoot trauma with concomitant talar head fractures. Methods: This study includes a retrospective cohort of patients with talar head fractures. Patient characteristics, trauma mechanism, fracture characteristics, treatment, follow-up, and complications were reported. Functional outcome was assessed using the Foot Function Index (FFI) and the American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot score. Quality of life was measured by the EuroQol-5D (EQ-5D). Twenty-one patients with acute fractures of the talar head were identified. The mean follow-up time was 4.9 years. Results: All patients sustained additional ipsilateral foot and/or ankle injuries. Fifteen patients had operative management of their talar head fracture. There were no postoperative wound infections and no cases of avascular necrosis. All fractures united, and 29% of patients developed posttraumatic osteoarthritis. The overall mean FFI score index was 34.2, and the mean AOFAS score was 70.7. The mean EQ-5D index score was 0.74. Conclusion: Talar head fractures always coincided with other (foot) fractures. Management and long-term functional outcome were affected by the extent of associated injuries. Due to the low incidence and high complexity of talar head fractures, early referral to dedicated foot surgeons and centralization of complex foot surgery is recommended. Level of Evidence: Level IV, retrospective case series.

Fractures of the Talar Head: A Series of 16 Patients

Category: Hindfoot; Trauma Introduction/Purpose: Fractures of the talar head are very rare accounting for just 5-10% of talus fractures and fewer than 1% of all fractures. As such, limited clinical literature is available to guide management of these injuries. We present the largest clinical series on talar head fractures to date. Methods: We performed a retrospective review of all patients presenting to three level-1 trauma centers with major fractures of the talus (fractures of the neck, body or head) over a 14-year period. From this cohort of patients, we identified patients presenting with fractures of the talar head with available computed-tomographic (CT) imaging of the foot allow proper fracture evaluation and characterization. In total, 258 patients with major fractures of the talus were identified. Sixteen patients (6.2%) with talar head fractures met inclusion criteria. Results: Most injuries were due to falls from height and only 4 were isolated. The navicular was fractured in 7 patients (43.8%). Six patients (37.5%) exhibited comminuted fracture patterns, while the remaining demonstrated simpler shear or impaction injuries. Four patients underwent fixation of the talar head, 3 were treated with primary stabilization or fusion of the talonavicular joint, and two patients were treated with head fragment excision. The talar head was managed in a closed fashion in the remaining seven patients, five of which presented with comminuted fracture patterns. Eight patients showed radiographic evidence of post- traumatic arthritis (PTA) at mean follow-up of 15.5 months. In all instances of PTA, the patient had sustained a comminuted talar fracture, an associated navicular fracture or both. Conclusion: Talar head fractures are extremely rare injuries with sparse literature to guide clinical management. Simple shearing or impaction fractures may be amenable to surgical fixation with favorable radiographic outcomes. Comminuted fractures and/or concomitant navicular trauma at the time of injury may be associated with increased incidence of talonavicular arthrosis.