Talocalcaneal coalition: A focus on radiographic findings and sites of bridging

Foot pain in children and adolescents: a problem-based approach in musculoskeletal ultrasonography

Various etiologies and risk factors contribute to foot pain in children and adolescents, including conditions such as Kohler's disease, Sever's disease, Iselin's disease, rigid flat foot, accessory navicular, Freiberg's disease, sesamoiditis, os trigonum syndrome, and more. High-frequency musculoskeletal ultrasonography can show both the bone surface and the surrounding soft tissue clearly from various angles in real-time, thereby providing a higher level of detail that is helpful for identifying the etiology of foot pain and monitoring disease progression compared with other imaging modalities. This review provides an overview of the epidemiology, pathophysiology, clinical manifestations and characteristic ultrasonographic findings of select foot pain conditions in children and adolescents.

Racial differences in prevalence and anatomical distribution of tarsal coalition

Previous studies have reported a prevalence of tarsal coalition of 0.03-13%. Calcaneonavicular coalition is known as main anatomical type, and the bilateral occurrence of tarsal coalition is known to be 50% or more. These are the results of studies on Caucasians, there have been few studies targeting large number of East Asians so far. We hypothesized that the prevalence and characteristics of tarsal coalition in East Asians might differ from those in Caucasians. The medical records of 839 patients who underwent bilateral computed tomography on foot and ankle in our hospital from January 2012 to April 2021 were retrospectively reviewed. The overall prevalence was 6.0%, talocalcaneal coalition was the most common anatomical type. The overall bilateral occurrence was 56.5%, talocalcaneal coalition had the highest bilateral occurrence (76.0%) among anatomical types. Isolated union of the posterior facet was the most common subtype of talocalcaneal coalition (43.2%). Talocalcaneal coalition had a significantly higher proportion of coalition-related symptomatic patients than calcaneonavicular coalition (p = 0.019). Our study showed a similar trend to other East Asian studies, confirming the existence of racial differences. The possibility of tarsal coalition in foot and ankle patients in East Asians should always be considered, and bilateral examination is essential for diagnosis.

Surgical Treatment of Calcaneonavicular and Talocalcaneal Coalitions

Tarsal coalition is determined by an absence of segmentation between one or more foot bones. The main symptom is activity-related foot pain, usually dorsolateral for calcaneonavicular coalitions and medial for talocalcaneal ones. At presentation, a symptomatic tarsal coalition must be treated conservatively for at least 6 months. If the conservative treatment fails and the foot is still painful, resection is the treatment of choice. Advantage of surgery is to restore mobility and reduce the risk of subsequent degenerative arthritis. Common pitfalls of surgery include failure to recognize associated coalitions, inadequate or extensive resection, and injury of adjoining bones.

A new classification of talocalcaneal coalitions based on computed tomography for operative planning

BACKGROUND

Current classifications emphasize the morphology of the coalition, however, subtalar joint facets involved should also be emphasized.

OBJECTIVE

The objective of this study was to develop a new classification system based on the articular facets involved to cover all coalitions and guide operative planning.

METHODS

Patients were diagnosed with talocalcaneal coalition using a CT scan, between January 2009 and February 2021. The coalition was classified into four main types according to the shape and nature of the coalition: I, inferiorly overgrown talus or superiorly overgrown calcaneus; II, both talus and calcaneus overgrew; III, coalition with an accessory ossicle; IV, complete osseous coalition (I-III types are non-osseous coalition). Then each type was further divided into three subtypes according to the articular facets involved. A, the coalition involving the anterior facets; M, the coalition involving the middle facets, and P, the coalition involving the posterior facets. Interobserver reliability was measured at the main type (based on nature and shape) and subtype (articular facet involved) using weighted Kappa. Results There were 106 patients (108 ft) included in this study. Overall, 8 ft (7.5%) were classified as type I, 75 ft (69.4%) as type II, 7 ft (6.5%) as type III, and 18 ft (16.7%) as type IV. Twenty-nine coalitions (26.9%) involved the posterior facets only (subtype-P), 74 coalitions (68.5%) involved both the middle and posterior facets (subtype-MP), and five coalitions (4.6%) simultaneously involved the anterior, middle, and posterior facets (subtype-AMP). Type II-MP coalition was the most common. The value of weighted Kappa for the main type was 0.93 (95%CI 0.86-0.99) (p<0.001), and the value for the subtype was 0.78 (95%CI 0.66-0.91) (p<0.001).

CONCLUSION

A new classification system of the talocalcaneal coalition to facilitate operative planning was developed.

The C-sign in normal feet: a prospective study and novel imaging algorithm for subtalar joint tarsal coalition

OBJECTIVE

The C-sign on lateral radiographs has been subject to considerable debate with respect to its reliable association to subtalar joint tarsal coalition. The purpose of this study was to determine to what degree subtalar joint pronation factors into (a) the appearance of both complete and incomplete type A C-signs and (b) the conspicuity of the middle facet in both flatfeet and rectus feet.

STUDY DESIGN

Forty-seven normal adult volunteers were enrolled into the study with a total of 92 feet, of which 42 were flexible flatfeet and 50 were rectus feet with normal subtalar joint range of motion. Lateral weight-bearing radiographs were taken of each foot in a position of (a) standing and (b) maximum subtalar joint pronation. Investigators evaluated images for the visibility of the middle facet, and the presence or absence of a continuous or interrupted type A C-sign.

PRINCIPAL RESULTS

No continuous C-signs were produced with extreme pronation in either the rectus/normal or flatfoot populations. Three incomplete type A C-signs were produced with pronation, two of which were in rectus feet. Two absent middle facet signs were also produced with pronation. Absent visualization of the facet had high positive and negative predictive values (1.00 and 0.99 respectively) for the presence of an incomplete C-Sign.

MAJOR CONCLUSIONS

The standard, routine lateral foot/ankle radiographic image protocol for suspected talocalcaneal coalition should be modified routinely positioning the foot maximally supinated, thereby minimizing the possibility of producing C-signs (complete or type A incomplete) and/or absent middle facet signs with pronation in either normal or flatfeet. A novel algorithmic approach can then be simply applied to determine when ancillary CT scanning is warranted for suspected posterior facet coalition.

Tarsal tunnel syndrome caused by posterior facet talocalcaneal coalition: A case report

RATIONALE

Tarsal tunnel syndrome (TTS) is a compressive neuropathy of the posterior tibial nerve and its branches. Tarsal coalition is defined as a fibrous, cartilaginous, or osseous bridging of 2 or more tarsal bones. TTS with tarsal coalition is uncommon. Here, we present a rare example of successful surgical management of TTS with posterior facet talocalcaneal coalition.

PATIENT CONCERNS

A 74-year-old woman presented with hypoesthesia, numbness, and an intermittent tingling sensation on the plantar area over the right forefoot to the middle foot area. The hypoesthesia and paresthesia of the right foot began 6 years previously and were severe along the lateral plantar aspect. The symptoms were mild at rest and increased during daily activities. Tinel sign was positive along the posteroinferior aspect of the medial malleolus.

DIAGNOSIS

Lateral ankle radiography showed joint-space narrowing and sclerotic bony changes with a deformed C-sign and humpback sign. Oblique coronal and sagittal computed tomography revealed an irregular medial posterior facet, partial coalition, narrowing, and subcortical cyst formation of the posterior subtalar joint. Magnetic resonance imaging showed an abnormal posterior talocalcaneal coalition compressing the posterior tibia nerve. Electromyography and nerve conduction velocity studies were performed, and the findings indicated that there was an incomplete lesion of the right plantar nerve, especially of the lateral plantar nerve, around the ankle level.

INTERVENTIONS

Surgical decompression was performed. Intraoperatively, the lateral plantar nerve exhibited fibrotic changes and tightening below the posterior facet talocalcaneal coalition. The coalition was excised, and the lateral plantar nerve was released with soft-tissue dissection.

OUTCOMES

The patient's symptoms of tingling sensation and hypoesthesia were almost relieved at 4 months postoperatively, but she complained of paresthesia with an itching sensation when the skin of the plantar area was touched. The paresthesia had disappeared almost completely at 8 months after surgery. She had no recurrence of symptoms at the 1-year follow-up.

LESSONS

The TTS with tarsal coalition is rare. Supportive history and physical examination are essential for diagnosis. Plain radiographs and computed tomography or magnetic resonance imaging are helpful to determine the cause of TTS and verify the tarsal coalition. After diagnosis, surgical excision of the coalition may be appropriate for management with a good outcome.

[Effectiveness of a modified posterior approach for arthroscopic resection on painful talocalcaneal coalition in adults]

Objective

To investigate the effectiveness of arthroscopic talocalcaneal coalition resection in painful adults via a modified posterior approach.

Methods

Between January 2015 and December 2017, 9 patients with painful talocalcaneal coalition accepted arthroscopic resection via the posterior malleolus high lateral observation approach combined with the lower medial operation approach. Of them, 6 were male and 3 were female, aged from 19 to 30 years (mean, 24 years). Among them, 2 cases had no definite local trauma and 7 cases had a history of sprain of foot and ankle. The disease duration ranged from 6 to 30 months, with a median of 12 months. Rozansky classification of talocalcaneal coalition for the 9 patients: 5 cases (5 feet) were type Ⅰ, 2 cases (2 feet) type Ⅱ, and 2 cases (2 feet) type Ⅲ. The patients had no sequelae of limb dysfunction and no limb joint surgery in the past. All the patients received anteroposterior and lateral X-ray films and CT scans of the ankle joint during follow-up. The visual analogue scale (VAS) score and American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hind foot score were used to evaluate the effectiveness.

Results

The operation time was 60-90 minutes (mean, 76 minutes). All patients were followed up 12-24 months (mean, 18 months). All the incisions healed by first intention, without infection, skin necrosis, lower extremity deep vein thrombosis, vascular nerve and tendon injury, bone bridge recurrence, and other complications. The ankle function recovered well and the pain was relieved obviously after operation, and the patients returned to work at 3-5 months after operation, with an average of 3.9 months. At last follow-up, the VAS score was 0.7±0.5, which was significantly improved ( t=20.239, P=0.000) when compared with preoperative score (4.2±0.5); the AOFAS ankle-hind foot score was 94±4, which was significantly improved ( t=-27.424, P=0.000) when compared with preoperative score (62±2). According to AOFAS ankle-hindfoot scoring system, the results were excellent in 7 cases and good in 2 cases at last follow-up.

Conclusion

It is more intuitive, more space, and more flexibility for operation via the modified posterior malleolus high lateral observation approach combined with the lower medial operation approach in talocalcaneal coalition. It is feasible to remove talocalcaneal coalition programmatically according to the specific anatomic signs during the operation.