Features of calcaneonavicular coalition on coronal computed tomography

Imaging of tarsal navicular disorders: a pictorial review

The tarsal navicular is a bone within the midfoot that plays a critical role in maintaining the arch of the foot. This bone is clinically relevant because it may be affected by a wide array of pathologies. Our approach includes a detailed description of the imaging characteristics and disorders affecting the tarsal navicular. Organization includes (a) normal imaging, (b) accessory ossicles, (c) coalition, (d) fractures, (e) Kohler's disease, (f) osteonecrosis, (g) osteochondral lesions, (h) arthropathies, and (i) tumors. The purpose of this article is to discuss normal variants and pathological processes that can affect the tarsal navicular, with emphasis on the often-overlooked imaging findings.

Stress fracture of the anterior process of the calcaneus: a case report

Stress fracture of the anterior process of the calcaneus is rare. We present a case of a 14-year-old female basketball player who suffered a stress fracture of the anterior process of the calcaneus that was not associated with a calcaneonavicular coalition. After conservative treatment failed, drilling of the fracture site was required to facilitate healing. A possible cause of this rare type of stress fracture seemed to be a long anterior process of the calcaneus.

LEVEL OF EVIDENCE

Therapeutic, Level IV: Case study.

Calcaneonavicular coalition: treatment by excision and fat graft

BACKGROUND

Symptomatic calcaneonavicular coalitions treated with resection and interposition of the extensor digitorum brevis (EDB) muscle often have unpredictable improvement of symptoms. Concerns with regard to skin cosmesis from a bony prominence on the lateral aspect of the foot and inadequate filling of the resection gap potentially causing reossification have motivated us to use fat graft interposition instead. The purpose of this study was to describe our surgical technique and report our clinical and radiographic outcomes for fat graft interposition after resection of a calcaneonavicular coalition.

METHODS

A retrospective review of all pediatric patients surgically treated with a calcaneonavicular coalition resection from January 1999 to December 2006, was performed. Presenting symptoms and examination findings were recorded. Postoperative examinations and imaging studies were evaluated to grade reossification, and functional outcomes were assessed for all patients with minimum 1-year postoperative follow-up. In addition, a cadaveric study was performed to compare the efficacy of EDB and fat graft interposition in terms of filling the postresection gap.

RESULTS

Foot pain was the most common presenting complaint, though limitation of activities, stiffness, preoperative hindfoot malalignment, and associated injuries were also frequently observed. One year after resection, 87% of the patients returned to sport or their past activities, whereas 5% had symptomatic regrowth requiring repeat resection. Seventy-four percent had improvement of subtalar motion and 82% had improvement of plantarflexion; which was identified as an additional clinical sign of a calcaneonavicular bar. Preoperative pain averaged 7 of 10, whereas postoperative pain averaged less than 1 of 10 at rest, while walking, and with activities. The cadaveric study showed that the EDB was able to fill on average only 64% of the resected gap, leaving approximately 10 mm of the plantar gap unfilled.

CONCLUSIONS

Reossification and reoperation rates with fat graft interposition in our series were lower than in most published reports of EDB interposition. Ankle and subtalar motion improved in a vast majority of the patients, and most patients returned to sport without requiring further surgery. Resection of a calcaneonavicular coalition with interposition of fat graft, when meticulously performed, is an effective way to relieve symptoms, restore subtalar motion, and return patients to activities, while preventing reossification.

Analysis of calcaneonavicular coalitions using multi-planar three-dimensional computed tomography

PURPOSE

Computed tomography (CT) is the current imaging standard for confirming the diagnosis of a calcaneonavicular coalition. The purpose of this study was to evaluate three-dimensional (3D) multi-planar CT images of calcaneonavicular coalitions and adjacent tarsal relationships, compared to controls, in order to obtain an understanding of the 3D anatomy for classification and as an aid to surgical resection.

METHODS

All patients who underwent CT of bilateral feet at our institution to evaluate a suspected calcaneonavicular coalition between 9/2005 and 3/2008 were retrospectively reviewed. Seventy-four feet (37 patients) were included in this analysis. In addition, 12 patients with a presumed normal calcaneonavicular relationship, who underwent CT of bilateral feet for various other diagnoses, were included as a control cohort. Seven measurements were performed on the 3D reconstructions to quantify the shape of the coalition (dorsal and plantar widths of the calcaneal and navicular contributions, coalition depth of the calcaneal and navicular contributions, and coalition length). The coalitions were classified into four types based on their appearance and their relationship to adjacent tarsal bones.

RESULTS

32/37 patients (86%) were noted to have bilateral involvement (69 coalitions). Coalitions were categorized into four types: Type I (forme fruste)-28%, Type II (fibrous)-23%, Type III (cartilaginous)-45% and Type IV (osseous)-4%. The average shape of the coalition was found to be a curved wedge, which was on average 16 mm wide dorsally, 7 mm wide on the plantar surface, 10 mm in length, and 25 mm in depth.

CONCLUSIONS

3D CT reconstructions enabled the classification of the spectrum of calcaneonavicular coalitions. The shape of the cuboid was found to correlate with the extent of ossification. In Type I or II coalitions, the cuboid extended medially plantar to the fibrous connection. In more complete Type III or IV coalitions, the cuboid was "squared off" and remained lateral to the osseous bridge. An understanding of the 3D anatomy is important when diagnosing milder forms of coalitions, and during resection in order to avoid iatrogenic injury to the calcaneus, head of the talus, or cuboid.

Imaging of the navicular

This article presented a rational approach to imaging of navicular pathology. The indications, techniques, and limitations of conventional radiographic imaging were discussed. In addition, the role of advanced imaging techniques, including MRI, CT, and NMI, in the diagnosis of navicular pathology was presented. By appropriately combining plain radiographic imaging with advanced imaging modalities, an accurate diagnosis is typically obtained.

Variations in Calcaneonavicular Morphology Demonstrated with Radiography

PURPOSE

To determine and classify radiographically demonstrated variations in calcaneonavicular morphology and to estimate prevalence in a clinically relevant patient population.

MATERIALS AND METHODS

Retrospective review was performed of foot radiographs obtained during diagnostic evaluation of 460 consecutive patients who presented to the emergency department with acute foot pain. Variations in calcaneonavicular morphology depicted on the medial oblique view (obtained at a 45 degrees angle) were classified into four groups according to morphologic type (types 1-4), and the prevalence of each type was calculated. Chi2 analysis was used to compare the prevalence of each type in male patients and in female patients. One-way analyses of variance were used to compare mean ages of patients for each type and mean calcaneonavicular gaps for each type.

RESULTS

The prevalence of morphologic types 1, 2, and 3 was 94.3%, 2.8%, and 2.8%, respectively. The combined prevalence of types 2 and 3 (calcaneonavicular coalitions produced by synchondrosis and syndesmosis, respectively) was 5.6% (95% CI: 3.5%, 7.8%). There were no patients with type 4 morphology (synostosis). The numbers of male patients and female patients with morphologic types 1-3 were approximately equal (P =.9), and there was no statistically significant correlation between any of these three morphologic types and patient age (P =.2). The calcaneonavicular gap was significantly narrower in types 2 and 3 than in type 1 (P =.01), which was characterized as the normal morphology.

CONCLUSION

The general prevalence of calcaneonavicular coalition (synchondrosis and syndesmosis) may be greater than previously reported, but further research is needed to prove the validity of this hypothesis.