In the present study, The use of ultrasound allows observation of new bone formation in the distraction gap, also visualize the formation of blood vessels in the distraction gap, including the velocity and resistance of blood vessels, and can also indicate the environment of new bone formation. It's considered that ultrasound detection of new bone and angiogenesis in the process of bone lengthening in children could be a good supplement to X-ray evaluation, and even partially replace the former, reducing the radiation burden of pediatric patients.
Limb lengthening is one of most common surgical techniques for correcting limb deformities in pediatric patients. The evaluation of new bone formation in the distraction gap is very important for the prognosis of limb lengthening. After limb lengthening, weekly or biweekly plain X-ray is the most commonly-used method to evaluate new bone formation in the distraction gap. However, Ordinary X-ray (film or digital) cannot provide details of regeneration or vascular regeneration like ultrasound examination, and radiation damage caused by X-ray or CT has unpredictable negative effects on minors. Ultrasound and X-ray examination were performed every 2 weeks during lengthening in 30 pediatric patients. Ultrasound was used to observe the formation of new bone, the number of vertical vessels and the blood flow resistance index, which were compared with the corresponding X-ray findings.New bone states could be divided by US into three stages: stage I (early lengthening): no obvious callus formation was found X-ray and ultrasound; stage II (lengthening stage): X-ray showed low density callus formation and uneven density, which was divided into three stages by ultrasound: IIa, punctate callus could be seen; IIb, linear callus was found, but not connected; IIc, connected linear callus was found; stage III (healing stage): the broken ends of the bone were joined, the periosteum was continuous, and the callus had disappeared. X-ray showed healing of the lengthened bone.
Study Type
OBSERVATIONAL
Enrollment
63
The use of ultrasound allows observation of new bone formation in the distraction gap, also visualize the formation of blood vessels in the distraction gap with SMI, including the velocity and resistance of blood vessels, and can also indicate the environment of new bone formation. All US examination were performed by one US doctor.
Children's Hospital of Fudan University
Shanghai, China
Gray scale of US in bone gap.
New bone states were divided into three stages: stage I (early lengthening): no obvious callus formation was found X-ray and ultrasound; stage II (lengthening stage): X-ray showed low density callus formation and uneven density, which was divided into three stages by ultrasound: IIa, punctate callus could be seen; IIb, linear callus was found, but not connected; IIc, connected linear callus was found; stage III (healing stage): the broken ends of the bone were joined, the periosteum was continuous, and the callus had disappeared.
Time frame: From the first day of lengthening to the removal of the external fixator.（Approximately 6 months.）
New vessels of bone gap.
The number of vessels in the lengthening gap, assessed via ultrasound techniques like SMI, reflects the vertical vessels growing into the distraction gap. This metric offers insights into the microvascular environment and angiogenesis of the new bone, aiding in evaluating healing progress and guiding lengthening protocol adjustments.
Time frame: From the first day of lengthening to the removal of the external fixator.（Approximately 6 months.）
Resistance index of new vessles.
The resistance index of new vessels, measured using ultrasound techniques like SMI, assesses blood flow resistance in the newly formed vessels within the lengthening gap.
Time frame: From the first day of lengthening to the removal of the external fixator.（Approximately 6 months.）
Healing index
The healing index, calculated as healing time in months divided by lengthening distance in centimeters, serves as an objective indicator of limb lengthening prognosis. A smaller healing index signifies a faster healing rate.
Time frame: From the first day of lengthening to 2 months after the removal of the external fixator.（Approximately 8 months.）
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