Spontaneous Fracture of the Atlas in a Patient with Pycnodysostosis and Mandibular Osteomyelitis - A Case Report

Abstract

Rationale:

Mandibular osteomyelitis is a common complication in pycnodysostosis; however, spontaneous atlas fracture has not been previously reported.

Patient Concerns:

Persistent mandibular pain, swelling, and purulent discharge following tooth extraction, along with recent cervical discomfort.

Diagnosis:

Left mandibular osteomyelitis and type 3 atlas (C1) fracture in a patient with a prior diagnosis of pycnodysostosis.

Treatment:

Cervical immobilisation with a Philadelphia collar for 8 weeks, sequestrectomy under local anaesthesia, irrigation, debridement and targeted antibiotics.

Outcomes:

Favorable progress with no signs of infection or cervical symptoms after 6 months, along with partial bone healing in the mandible and stabilization of the C1 fracture.

Take-away Lessons:

In patients with pycnodysostosis, maxillofacial procedures must include prior cervical evaluation. Vertebral fractures may occur without evident trauma and present with minimal symptoms, posing a high clinical risk if undetected.

INTRODUCTION

Pycnodysostosis is a rare autosomal recessive disorder first described in 1962, with an incidence of 1 in 1.7 million. It is caused by mutations in the CTSK gene, which encodes cathepsin K, a lysosomal cysteine protease in osteoclasts responsible for degrading collagen types I and II and osteonectin. Mutations in this gene lead to bone fragility, predisposing patients to pathological fractures, particularly in long bones.[1,2,3] This abnormal bone metabolism increases the susceptibility of patients to develop osteomyelitis, added to local factors such as maxilla and mandible morphology, continuous trauma, alveolar surgical procedures and conditions affecting the teeth, such as periapical and periodontal disease.[2] We report a case of a 30-year-old male with mandibular osteomyelitis and a spontaneous atlas fracture.

CASE REPORT

A 30-year-old male presented in August 2023 with pain, swelling and purulent discharge in the left mandibular region, following the extraction of the first and second lower left molars in January 2023 due to dental caries. Despite multiple courses of antibiotic therapy, his symptoms persisted. He had a history of multiple fractures and had been diagnosed with pycnodysostosis 5 years earlier.

During the physical examination, the patient was found to be oriented, cooperative and had characteristic features of pycnodysostosis syndrome: small face, proptosis, blue sclerae, prominent nose, frontal and occipital protuberances, obtuse mandibular angle, as well as anteroposterior and transverse bimaxillary hypoplasia [Figure 1]. Intraorally, there was severe dental crowding, anterior and posterior crossbite, an ulcer in the posterior region of the left hemimandible with exposed bone segments and purulent discharge, as well as painful points on palpation [Figure 2]. The patient presented a video of a computed axial tomography scan performed in February 2023, which showed loss of lingual bone cortex in the region of the lower left second molar, as well as the presence of hyperdense and hypodense images, suggestive of bone sequestration of approximately 1 cm in diameter. The patient returned in October 2023 with worsening pain and halitosis. Therefore, a cone beam tomography was performed, where the absence of lingual cortex in the region of the lower left first molar was observed, with mixed areas and the presence of a hypodense area without continuity with the adjacent bone, suggestive of bone sequestration [Figure 3]. A C1 discontinuity with diastasis, absent in a previous video, was observed, consistent with a type 3 Gehweiler fracture [Figure 4]. The patient reported a cervical creaking 15 days earlier, followed by 3 days of pain that was relieved with massage. At consultation, he was asymptomatic and referred to the surgical service, where the diagnosis was confirmed, and a Philadelphia collar was recommended for 8 weeks.

Figure 1.

Facial photograph of the patient displaying a distinctive phenotype

Figure 2.

Intraoral view showing an ulcer in the posterior region of the left hemimandible, with exposed bone and purulent discharge

Figure 3.

Volumetric reconstruction of the patient displaying a distinctive phenotype

Figure 4.

(a) Internal view of volumetric reconstruction showing a type 3 fracture of the atlas. (b) View of the volumetric reconstruction superposition at 10 weeks showing no displacement or changes in consolidation

During those weeks, the patient reported increased pain at the abduction site and difficulty eating due to the pressure of the collar. In coordination with the spinal surgery service, treatment for osteomyelitis was initiated. The procedure was performed under local anaesthesia with the patient in the Fowler position and the collar in place. A sequestrectomy was performed, with sample collection for microbiological culture, saline lavage and debridement. Treatment was initiated with amoxicillin/clavulanic acid (875/125 mg every 12 h for 5 days), along with 0.12% chlorhexidine rinses (1 min, 3 times daily for 15 days). Culture and antibiogram revealed no specific bacteria or resistance, so antibiotics were continued for 4 weeks. Biopsy showed several bone tissue fragments with separate trabeculae with irregular edges, lacunae without osteocytes and several areas of mature bone tissue surrounded by basophilic material compatible with bacterial colonies, confirming the diagnosis of osteomyelitis [Figure 5].

Figure 5.

Microphotograph 10x of histological section showing lacunae without osteocytes

The patient progressed well, with no pain or purulent discharge and adequate soft-tissue healing, and resumed normal activities. At 16 weeks, a cone beam tomography was requested to assess the osteomyelitis and the atlas fracture. No changes were observed in the displacement and repair of the atlas [Figure 4].

In the area of the lower left first molar, bone defects in the process of healing were observed, with a slightly irregular contour and increased surrounding bone density. In the area of the lower left second molar, loss of the lingual bone plate was observed, with a defined bone defect and sclerotic contour; however, no relevant changes were noted [Figure 6]. Images show early bone repair without free fragments. The collar was removed, care instructions given and the patient resumed normal activities. Over 6 months of follow-up, osteomyelitis improved without cervical discomfort. The patient was informed of treatment options for airway and occlusion but declined orthognathic surgery.

Figure 6.

(a) Volumetric reconstruction of a left mandibular sectional tomography showing an osteolytic area and bone sequestration. (b) View of the volumetric reconstruction at 10 weeks showing an initial bone repair process, with no free bone fragments

DISCUSSION

Pycnodysostosis is a rare genetic disorder caused by CTSK gene mutations, leading to defective bone resorption.[2,4] Osteomyelitis, due to reduced vascularity, is the most common oral complication.[2,5,6] The characteristics of the disorder, as originally defined by them, are proportional dwarfism; increased bone density, with a tendency to pathological fractures; dysplasia of the terminal phalanges; cranial abnormalities, including persistent fontanelles, open sutures and frontal and occipital protuberances and hypoplasia of the mandible. An extremely high rate of parental consanguinity has been reported in patients with pycnodysostosis, and the disease is considered an autosomal recessive inheritance. Its oral manifestations include deep, high-arched and deformed palate, dental malocclusion, enamel hypoplasia, hypercementosis, retained deciduous teeth and impaction of permanent teeth.[2,7,8]

In our review of the literature, we found only one described case of a 21-year-old patient with this syndrome, who sustained a fracture in the first four cervical vertebrae due to a fall from his own height. Atlas fractures, comprising up to 13% of cervical fractures, typically result from high-energy trauma and present with neck pain or spasms but without persistent neurological deficits.[4]

Treatment depends on fracture stability, defined as ≥7 mm lateral displacement on computed tomography (CT) or transverse ligament tear on magnetic resonance imaging. Most C1 fractures are managed conservatively with 8–12 weeks of immobilisation. Type 3 fractures are the most unstable.[4,9,10] Osteomyelitis is a common oral complication in patients with pycnodysostosis. Decreased vascularisation, gradual elimination of marrow spaces, increased endosteal bone production and immunocompromise contribute to a higher risk and complicate treatment, which may sometimes require extensive resections.[1,5,9] Despite advances, it remains difficult to treat, and no universally accepted treatment protocol exists. Conservative approaches are usually preferred, including antibiotic therapy based on cultures and antibiograms, along with analgesics, anti-inflammatories, hyperbaric oxygen therapy, vestibular fat flap rotation, curettage, sequestrectomy and prophylactic resections in persistent sclerotic areas after sequestrectomy.[5,6,8]

Antimicrobial therapy and surgical debridement are the main treatments for osteomyelitis.[1,9] Despite phenotypic manifestations and multiple fractures, the patient reached age 25 without diagnosis or treatment. The severe C1 fracture posed a serious neurological risk, and surgery without an updated CT could has been life-threatening. Patients with pycnodysostosis may also seek maxillofacial procedures, so a full cervical evaluation is essential before any intervention.[5,6] The limitations of this article lie in the fact that, as a single case report. Nevertheless, this finding underscores the importance of carefully evaluating the cervical region prior to any intervention.

CONCLUSIONS

Pycnodysostosis syndrome is exceptionally rare, and an early diagnosis is crucial to prevent complications. In addition to seeking treatment for the management of osteomyelitis in the maxillofacial area, patients may also seek evaluation for distraction boning or orthognathic surgery. Therefore, it is imperative that they undergo a complete cervical evaluation before undergoing any intervention.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.