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Web-based radiograph interpretation accurate for tibial osteotomy
The picture archiving and communications system measured the tibial angle and height.
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Researchers found the web-based radiograph interpretation system – picture archiving and communications system – an accurate and reliable method of measuring high tibial osteotomy angle and height, according to a study presented by registrar surgeon Emily Mounsey. “While this is a recognized procedure, there’s no literature on the reliability and accuracy of a web-based system to calculate the osteotomy height and angle,” Mounsey said during her presentation at the 12th EFORT Congress 2011.
Mounsey and her team studied patients undergoing high tibial osteotomy between October 2004 and February 2010. They looked at full-length lower limb radiographs on the picture archiving and communications system (PACS).
A surgeon and two orthopedic registrars measured patients’ Fujisawa angle and osteotomy length. The team reviewed 30 radiographs in 28 patients in all.
“Long leg alignment X-rays were used to calculate the angle and height of the osteotomy required to shift the mechanical axis of the lower leg to the Fujisawa point, which is 62% across the knee from the medial side,” Mounsey said. “This is the required new mechanical axis from the center of the femoral head through the Fujisawa point and down to the new ankle position. The angle can be calculated from this position to the apex of the osteotomy, and through the center of the ankle the height of the osteotomy can then be identified.”
Mounsey reported that the difference between the standard, which was represented by the consultant and the other raters, was a mean of 0.43 mm. A Bland-Altman plot of agreement revealed “excellent agreement with only two outliers outside the standard deviation of the mean,” she said.
Raters with more experience showed better accuracy with the measurement technique. The correlation between all three raters was statistically significant. The greatest correlation was between the consultant and senior trainee and the lowest was between the consultant and junior trainee.
The concordance correlation varied between 0.81 and 0.63. The Bland-Altman plot between the consultant and junior trainee revealed two values outside of 1.96 standard deviation.
“There is a high correlation between all raters with measurements within clinically acceptable limits of less than 1 mm,” Mounsey said. “This increased accuracy of measurements with greater experience of the technique, as you might expect. To conclude, the measurement of high tibial osteotomy angle and height using PACS is reliable and reproducible and we recommend this as a technique for preoperative planning.” – by Renee Blisard
Reference:
- Mounsey E, Dawe E, Golhar A, Hockings M. Measurement of high tibial osteotomy using a web-based X-ray interpretation system. Paper #2623. Presented at the 12th EFORT Congress 2011. June 1-4. Copenhagen, Denmark.
- Emily Mounsey can be reached at Royal Devon & Exeter NHS Foundation Trust, Barrack Road, Exeter, EX2 5DW, United Kingdom; 01392 411611; email: ejmounsey@hotmail.com.
- Disclosure: Mounsey has no relevant financial disclosures.
Picture archiving and communications system (PACS) is now used in many medical institutions around the world. Preoperative planning for high tibial osteotomy (HTO) requires precise measurements to arrive at the appropriate correction post-surgery. Surgeons have been traditionally most comfortable measuring these angles on hip-to-ankle radiographs. With the advent of PACS, surgeons at our institution (including myself) were initially reluctant to go away from the hard copy radiographs for this purpose.
As Mounsey et al have shown in this paper, preoperative planning for HTO is accurate and reproducible using PACS. We have investigated this same issue at our institution and the results will be published soon in Knee Surgery, Sports Traumatology, Arthroscopy. We arrived at a similar conclusion using a different measurement.
I agree with the authors that when PACS is available, preoperative planning for HTO can be reliably performed. Furthermore, measuring angles for this purpose is easier using PACS compared to hard copy radiographs.
— Robert G. Marx, MD
Professor of
Orthopedic Surgery
Hospital for Special Surgery
New York
Disclosure: Marx has no relevant financial disclosures.