Radionuclide scintimetry for diagnosis of complications following femoral neck fracture

Isotope imaging

Patients with a wide variety of rheumatological conditions can be usefully investigated by nuclear medicine techniques and particularly by bone scintigraphy. This aspect of nuclear medicine work is increasing and the trend can be expected to continue. The principal conditions that can be imaged are sports medicine injuries, osteomyelitis, avascular necrosis, reflex sympathetic dystrophy syndrome, enthesopathies and bio-mechanical stress lesions, inflammatory arthropathies, metabolic bone disease and miscellaneous bone conditions such as costo-chondritis. Single photon emission tomography (SPECT) has provided new indications for bone scintigraphy such as the evaluation of spondylolysis and facet syndrome in the spine and of meniscal tears and ligamental lesions.

Technetium 99m-MDP scintigraphy of patients undergoing implant prosthetic procedures: a follow-up study

The clinical evaluation of peri-implant tissue is mainly based on x-rays. In recent years, radioisotope scintigraphy using Tc-99m-MDP (technetium-99m-methylene diphosphonate) proved to be a useful and reliable clinical method for measuring increased metabolic activity at specific sites of the skeletal tissue. Twenty-six (26) patients (26 to 75 years) who were diagnosed for implant prosthetic treatment modality were randomly chosen to participate in this study. Each patient was injected with 20 mCi of Tc-99m-MDP was scanned 2 hours later by gamma-camera for isotope uptake levels in the jaws. Each patient was scanned 1 to 4 times, starting 2 weeks after implant surgery and up to the 40th week postsurgery. Blade and screw type implants using the non-submerged, one-stage technique were placed. Therefore, the prosthetic reconstruction was initiated 2 weeks after implant surgery. In order to compare the different scans we formulated a relative "bone scan index" (BSI). The results of 62 scans were plotted as BSI against time after implant surgery. A mathematical regression analysis of the BSI was also performed. At the initial stage of 2 to 3 weeks after surgery the BSI is high and then gradually declines. While BSI of the implants in the mandible reaches baseline levels after 12 weeks, the BSI in the maxilla reaches baseline only after 20 weeks. On the other hand, there was no difference in BSI with regard to blade or screw type implant. Here we were able to demonstrate that the process is independent of implant modality and depends on the specific metabolic properties of the jaw.(ABSTRACT TRUNCATED AT 250 WORDS)

Complications of fractures and their healing

The role of nuclear medicine studies in diagnosing late complications of fractures is described. Static bone scintigraphy is not helpful in predicting delayed or non-union of fractures. Several investigators have developed simple formulae comparing uptake in fracture site with adjacent or contralateral normal bone and described criteria that will predict problems with healing. These types of tests should only be used in patients who are at risk for delayed union. The scintigraphic diagnosis of infection complicating a fracture is difficult. Bone scintigraphy alone is not useful and combined 67Ga/99mTc MDP scanning has been disappointing. Most published series support the role in 111In WBC in this situation, but not all cases are correctly diagnosed. 111In (Chloride) cannot differentiate an infected from a delayed-healing fracture. Bone scintigraphy has a significant role in determining whether a bone graft is viable or not. Reflex sympathetic dystrophy is a rare complication of a fracture; it can be diagnosed by increased periarticular uptake on bone scan in all the joints of the affected part. Bone scintigraphy, especially when done with SPECT, is a very sensitive test for the diagnosis of avascular necrosis (AVN).

Sequential scintimetry after femoral neck fracture. Methodologic aspects and prediction of healing complications

Forty-five patients with recent cervical hip fractures were included in a prospective, clinical, radiographic and sequential scintimetric study. Striking changes in radionuclide uptake over the entire hip region on the fracture side were found during the first 5 postoperative months. Fractures that healed without complications showed the highest relative femoral head uptake at 1 week and a peak value at 6 weeks, followed by a gradual decline at the subsequent examinations. Fractures with complications (redisplacement, nonunion, or late segmental collapse) showed a lower initial uptake and a more gradual increase and only a slight tendency towards increased uptake after 3 months. The accuracy in predicting nonunion with scintimetric examination alone is high both at 1 and at 6 weeks, and the accuracy is almost equally high with combined scintimetric, radiographic, and clinical assessment 3-5 months postoperatively.

Sequential scintimetry in prediction of healing rate after femoral neck fracture

Thirty-one femoral neck fractures which united without complications (nonunion or late segmental collapse) were included in a prospective sequential scintimetric study. Roentgenologically, three subgroups with different healing rates could be distinguished: rapid union, normal union, and delayed union. All fractures showed a rapid increase in relative femoral head radionuclide uptake after the 1-week scintimetry, followed by a gradual decline after 6 weeks-3 months. However, both the initial rise in activity and the time for maximal uptake tended to differ between the three groups. For rapid union and normal union the peak activity was registered at 6 weeks and for delayed union at 3 months. It is concluded that sequential scintimetric assessment of femoral head uptake can identify different healing rates and that this difference can be partly explained by a transient impairment of vascular supply to the femoral head in fractures with delayed healing.

Comparison of skeletal and bone marrow radionuclide scintimetry of femoral neck fracture

Twenty-six patients with late complications following femoral neck fracture were examined with both skeletal and bone marrow radionuclide scintimetry. There was no correlation between the methods with respect to the quantitative assessment of femoral head vascularity based on different uptake ratios comparing the fractured and the intact side. Skeletal scintimetry always had good image quality and permitted reliable differentiation between nonunion of the fracture and late segmental collapse, in contrast to bone marrow scintimetry which gave poor image quality. Skeletal scintimetry thus seems superior to bone marrow scintimetry for assessment and differential diagnosis of late complications following femoral neck fracture. It is emphasized that the physiological mechanisms for radionuclide uptake must be taken into account when comparing scintimetric studies using different tracers.