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The Utility of Tc-99m Hydroxydiphosphonate Single-Photon Emission Computed Tomography/Computed Tomography in Symptomatic Kohler’s Disease
Address for correspondence: Dr. Wasen AlYaqout, Kuwait Institute for Medical Specializations, Kuwait City, Kuwait. E-mail: wasenalyaqout@gmail.com
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Received: ,
Accepted: ,
This article was originally published by Wolters Kluwer - Medknow and was migrated to Scientific Scholar after the change of Publisher.
Abstract
Kohler’s disease (KD) is a rare disorder of the foot in children where there is avascular necrosis of the navicular bone (NB). It presents with pain and limping and is often misdiagnosed as an infection. However, by adding single-photon emission computed tomography-computed tomography (SPECT-CT) of the foot, the lesion is localized to the NB, leading to the diagnosis of KD. We report the case of a 6-year-old boy with limping and foot pain, who underwent a bone scan using Tc-99m hydroxydiphosphonate and SPECT-CT of the feet. SPECT-CT was necessary not only to localize the exact site of the pathology in an area with small bones but also to confidently reach the diagnosis of KD and proceed with the correct management plan.
Keywords
Antalgic limp
avascular necrosis
foot pain
Kohler’s disease
navicular bone
Tc-99m hydroxydiphosphonate single-photon emission computed tomography-computed tomography
A 6-year-old male patient presented with limping and left ankle pain with no history of trauma for 1 month. Upon presentation, the temperature was 37°C, oxygen saturation was 99%, and heart rate was 110* 6 pm. Three-phase bone scintigraphy is performed by injecting 10.3 mCi of Tc-99m hydroxydiphosphonate intravenously. Flow images over the feet show very mild hyperemia to the left foot. Spot blood pool and whole-body blood pool images show a focus on increased tracer pooling at the medial side of the left midfoot [Figure 1]. Delayed whole-body images show the physiological distribution of tracer activity within the skeleton and growth plates. Spot views of the feet also show the same findings with a focus on intensely increased tracer uptake at the medial side of the tarsal bones of the left foot [Figure 2]. Single-photon emission computed tomography-computed tomography (SPECT-CT) of the feet localizes this significantly increased uptake to be within the left navicular bone (NB) that appears to be flattened, sclerotic, and fragmented on the CT component [Figure 3]. Positive early activity indicates the healing phase of avascular necrosis (AVN) which coincides with the patient clinical improvement.
Kohler’s disease (KD) is an entity that describes the childhood onset of AVN of the NB.[1] It was first described by Kohler in 1908 and is a self-limiting disorder that occurs as a result of osteonecrosis of the ossification centers during childhood.[2] The disease is usually unilateral but can occur bilaterally in up to 20% of cases.[3] KD typically presents in boys from 2 years to 10 years of age and is up to six times more common in boys than girls.[3] One of the proposed mechanisms of the occurrence of KD is ischemia of the NB that can occur due to vascular insufficiency, coagulation disorders, or hereditary causes.[1] Since the NB is one of the last to ossify, as the child grows and exerts more weight on the foot, the denser and already calcified surrounding bones like the talus and cuneiform bones mechanically compress it.[4,5] Consequently, the blood vessels feeding the NB become compressed, leading to ischemia and necrosis of the bone.[4]
A typical presentation of KD is foot pain and limping in a child.[6] Pain is gradual in onset and increases with physical activity.[6] Physical examination reveals swelling, erythema, and tenderness on the dorsum of the affected foot.[2,6] Clinically, this presentation could overlap with inflammatory arthritis, infection, or even tarsal coalition.[3] Initial radiographs may be normal, and bone scans can show photopenia in NB in the early avascular phase of the disease.[6] In later stages, bone scanning shows increased tracer uptake indicating revascularization or a healing phase.[6] Typically, radiographs show one of two patterns with the most common being the flattening of the NB (wafer-like) appearance with loss of trabeculation and patchy sclerotic areas.[3,6] Less commonly, X-rays show diffusely increased density and sclerosis in a normally shaped NB.[3,6]
The resolution of KD is spontaneous, and radiographs typically show complete resolution in 9 years.[2] Treatment is reserved for symptomatic patients with gait abnormalities and involves using painkillers and foot casts.[6]
In conclusion, KD is a self-limiting childhood disease, presenting as foot pain and limping. Bone scintigraphy with SPECT-CT is a valuable tool in reaching the correct diagnosis.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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