X-rays Miss Many Cases of Hip Osteoarthritis
It’s a good thing orthopaedists don’t rely solely on X-rays to diagnose hip osteoarthritis (OA), because an analysis of data from two large cohort studies casts doubt about the utility of radiographs in diagnosing hip OA in older patients.
Using pain localized to the groin or anterior hip or provoked by internal rotation as the clinical standard for diagnosing hip OA, the researchers compared participants’ reports of such pain with radiographic evidence. In the first cohort study (n=946), only 15.6% of hips in patients reporting frequent hip pain showed radiographic evidence of osteoarthritis. In the second study (n=4366), only 9.1% of hips in patients with frequent pain showed radiographic evidence of hip OA. Conversely, pain was not present in many hips with radiographic evidence of osteoarthritis.
These findings strongly indicate that many cases of hip arthritis would be missed if clinicians relied solely, or even largely, on radiographs. The findings also suggest that overdiagnosis of osteoarthritis would be likely if doctors relied on radiographs rather than examining patients and obtaining an appropriate history. The authors conclude that “health professionals should continue to evaluate and treat patients with hip pain suggestive of osteoarthritis despite negative radiographic findings.” This study is also a good reminder for physicians to treat patients, not imaging studies.
Protecting Surgeons’ Hands from Radiation during Fluoroscopy
The In
ternational Commission on Radiological Protection (ICRP) currently recommends a maximum of 50 rem (500 millisieverts, or mSv) of occupational hand-radiation exposure annually. A fascinating study using a surgeon manikin, mini and standard fluoroscopic c-arms, and a Sawbones model of distal radial fracture fixation showed that hand-radiation exposure averaged 31 µSv per minute. That finding suggests that hand surgeons would not approach the ICRP-recommended hand-exposure limit unless they performed close to 2,000 hand procedures involving fluoroscopy each year. However, authors Hoffler et al. are quick to add that “the effect of consistent exposure that does not exceed the annual limit, but continues for a multiple-decade career, is unknown.”
It comes as little surprise that treating a distal radial fracture can be a high-exposure event. To quantify the situation more precisely, Hoffler et al. fit a surgeon manikin with radiation-attenuating glasses, thyroid shield/apron, and gloves, and measured radiation exposure with dosimeters placed on the manikin in both exposed and shielded positions. They exposed the Sawbones model and the manikin, which was in a standard seated position for hand surgery, to radiation from three mini and three standard fluoroscopes for fifteen minutes continuously. The authors explained their rationale for fifteen minutes of continuous exposure as follows: “The mean fluoroscopy time for volar radial plating at our institution is sixty seconds…It is common for hand surgeons to use a fluoroscope fifteen times a month…If exposures average sixty seconds each, the hand surgeon could be routinely exposed to fifteen minutes of fluoroscopy monthly.”
The authors found that hand exposure was 13 times higher than exposures at the thyroid, groin, or chest. The eyes, the second-most exposed site, received an average of 4 µSv per minute. Radiation-attenuating gloves reduced hand exposure by a mean of 69%, and radiation-attenuating glasses decreased eye exposure by a mean of 65%. There were no significant differences in hand exposure between the mini and standard fluoroscopes.
OrthoBuzz encourages orthopaedic surgeons to consider these findings in light of the current proliferation of fluoroscopes outside the OR, especially in office settings. For their part, the authors encourage surgeons to minimize their own and their patients’ radiation exposure “by understanding the basic physics of x-ray radiation and maximizing all of the safety technologies that their specific fluoroscopy units offer,” including the use of personal protective equipment.
RA Progression Rate Predicts Need for Future Surgery
UK epidemiologists presenting at the annual meeting of the British Society for Rheumatology recently reported that X-ray evidence of rapid rheumatoid arthritis (RA) progression during the first 12 months of the disease can help predict the need for later surgery of hand, foot, hip, and knee joints. Lewis Carpenter and colleagues analyzed data from the Early Rheumatoid Arthritis Study and found that a change in the Larsen radiographic score of four units during the first 12 months of RA was associated with an 80% increased risk of subsequent surgery on joints of the hand and foot, and a 50% increase in the risk of later hip or knee surgery. (The 0 to 5 Larsen score includes both joint-erosion and joint-space narrowing components.) Carpenter told MedPage Today that these findings help “build the case for early treatment in rheumatoid arthritis” and support the argument that a “therapeutic window of opportunity” exists with RA.
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