The use of the three-phase bone scan in the early diagnosis of heterotopic ossification (HO) and in the evaluation of Didronel therapy

Abstract

Abstract. The purpose of this study is to investigate the use of a three-phase bone scan for early detection of HO formation and as a method of evaluating Didronel treatment.A marked vascular blush and blood pool was noted about the hips sometimes with a normal bone scan and normal X-ray of the hips. This appeared to represent the pre cursor phase of HO formation since, on repeat scans, the bone scan showed accumulation of the bone-seeking radionuclide usually in 2 to 4 weeks and the X -ray revealed ossification.Fifty-two patients treated with Didronel between October 1978 and December 1979 were reviewed to determine the value of Didronel treatment.There were 23 patients in the series who either showed HO by X-ray on admission or developed HO on follow-up X-rays before beginning Didronel therapy. A three phase bone scan revealed increased vascularity and accumulation of radioactivity on the bone scan in all areas of ossification on the X-ray and in some areas that did not appear to be involved. The other 29 patients had serial three-phase bone scans, X-ray study, and an alkaline phosphatase determination at approximately 2-week intervals. Didronel treatment was started as soon as the precursor phase of HO was demon strated on the three-phase bone scan in most of these patients. Nine have not developed ossification that could be seen in X-rays during 3 months of continuing study.Six patients seen at follow-up during the past year had known HO of 4 to 7 years' duration. The three-phase bone scan was used to predict the maturity of HO in these patients.Our study indicates that increased vascularity precedes rather than being secondary to HO formation as is suggested in the literature. Didronel treatment appears to be most effective if initiated during this precursor phase.

Neurogenic heterotopic ossification in spinal cord injury

“…18 NHO will become evident on plain radiography upon accumulation of minerals about 2 ± 6 weeks after the three-phase bone scan ®rst becomes positive. 70,129,137 In several studies radiographic signs of NHO were found on average 1 ± 10 weeks after the ®rst clinical signs. 19,36,47 Plain radiography may be positive even in asymptomatic patients as early as 4.5 weeks after the SCI.…”

“…The blood¯ow and blood pool phases of the bone scan are able to detect NHO as early as 2.5 weeks after SCI and are followed by a positive static bone phase 1 ± 4 weeks later. 28,129 Bone scans return to normal as the NHO matures usually within 6 ± 18 months after its ®rst clinical signs. 70 Compared to plain radiography, bone scanning is a more sensitive diagnostic test for early NHO, but radiography is more speci®c.…”

“…28 In monitoring NHO maturation, the three-phase bone scan seems the most sensitive tool and currently the`golden standard'. 49,126,129,132 Nonetheless, the criteria for maturity rating on the bone scans remains a topic of discussion. Whether a qualitative assessment eg a continuous decrease in the uptake or a steady state in the radionuclide accumulation, or a quantitative assessment such as speci®c uptake ratios should be considered as the best maturity index remains unclear.…”

“…10,45,49,173,174,176 It has been suggested that the recurrence after resection can be reduced if NHO is removed only once the ®rst and second phase of the bone scan have normalized. 10,52,115,129,132 However, such a maturity rating does not guarantee that NHO recurrence is unlikely. Garland et al 49 reported that still 36% recurrence of clinically signi®cant NHO was found in SCI patients with mature NHO on the bone scan.…”

Prolonged fever and heterotopic ossification in a C4 tetraplegic patient. Case report

“…To this end, radionuclide bone scan is the most sensitive diagnostic tool and has been reported to precede clinical manifestations by up to 6 weeks. 16 More recently, ultrasound has also been found to be useful especially in situations where deep vein thrombosis is a differential diagnosis. 17 Apart from the use of disodium etidronate in the treatment of established HO, careful regular stretching of involved joints to maintain range of motion is also important.…”