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Multiplanar imaging shown to be reliable for assessing parameters of flatfoot
In patients with lateral hindfoot pain, subtalar arthrosis was better visualized on multiplanar scans.
Recent research shows that weight-bearing, multiplanar axial imaging provides reliable measures of flatfoot deformity.
The study also indicates that patients with flatfoot and lateral hindfoot pain have increased subtalar arthrosis and calcaneofibular impingement which can be better visualized with this 3-D imaging modality compared to conventional radiographs.
“The multiplanar imaging modality gives us a reliable way of assessing flatfoot parameters, particularly those of arthrosis and impingement,” Scott J. Ellis, MD, said during his presentation at the 25th Annual Summer Meeting of the American Orthopaedic Foot and Ankle Society. “It gives us a weight-bearing, 3-D view and avoids the limitations of our current modalities. The cause of lateral hindfoot pain is likely multifactorial stemming from subtalar arthrosis and impingement. Understanding the etiology of lateral hindfoot pain may lead us to better treatment algorithms.”
The moderator of the session, Victor Valderrabano, MD, PhD, called multiplanar imaging modality for flatfoot deformity “innovative.”
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“With this imaging technique, the surgeon may be able to develop a better and individualized treatment algorithm for symptomatic flatfeet patients for example, joint preserving surgery vs. arthrodesis,” Valderrabano told Orthopedics Today. “I personally think that this way of foot and ankle imaging will be the future — 3-D and weight-bearing.”
Patients with, without pain
Ellis and his colleagues obtained the radiographs and standing 3-D plantar images using the Multi-Diagnostic Eleva Scanning System (Philips Medical Systems) in 10 consecutive patients with Stage II flatfoot deformity with lateral hindfoot pain. They then compared these images to those of 10 consecutive patients Stage II flatfoot without pain. The patients in the study group had a mean age of 55.5 years and the control group a mean age of 61 years.
Two musculoskeletal radiologists who were blinded to the group allocation read the radiographs and multiplanar images. The investigators measured flatfoot parameters and studied various sources of impingement and arthroses with both imaging modalities. They also assessed interrater reliability and compared the multiplanar and radiographic parameter values for the study and control groups.
Reliability
“We showed excellent to good interrater reliability for many of the multiplanar parameters,” Ellis said.
He also noted that interrater reliability for many of the multiplanar sagittal parameters was categorized as good and excellent. However, the reliability for some coronal parameters, such as medial gutter distance, hindfoot alignment and lateral gutter distance was fair.
“More importantly, for the parameters of impingement and arthrosis, we showed good to excellent for virtually all of those,” Ellis said.
A comparison of the multiplanar parameters for the study and control groups showed that combined subtalar arthrosis, posterior facet subtalar arthrosis, calcaneocuboid arthrosis and calcaneofibular impingement were significant or trended toward significance for patients with pain.
“When we looked at standard radiograph, the only parameter that was significant for pain was calcaneocuboid arthrosis,” Ellis said.
He noted the small sample size and subjectivity of pain as limitations to the study. The investigators plan to prospectively follow more patients to understand the etiology of lateral hindfoot pain.
For more information:
- Scott J. Ellis, MD, can be reached at The Hospital for Special Surgery 535 East 70th St., New York, NY, 10021; 646-797-8305; e-mail: elliss@hss.edu. One of the study authors receives royalties from Philips Medical Systems for an online educational project unrelated to this study.
- Victor Valderrabano, MD, PhD, can be reached at the Orthopaedic Department, University Hospital of Basel, Spitalstrasse 21, Basel CH-4031, Switzerland; 41-61-265-7197; e-mail: vvalderrabano@uhbs.ch. He receives research or institutional support from Synthes and Orthocon.
Reference:
- Ellis SJ, Williams B, Deyer T, et al. Assessment of lateral hindfoot pain in flatfoot deformity using weightbearing multiplanar CT imaging. Presented at the 25th Annual Summer Meeting of the American Orthopaedic Foot and Ankle Society. July 15-18, 2009. Vancouver, British Columbia.