Dynamic bone scanning in fractures

Nonunion using a canine model

The investigation involved a search for a model of atrophic nonunion. Fifty-two mature, adult, mongrel dogs were used to study the repair after creating a 0.5-cm bone defect in the mid-diaphysis of the radius. In addition, a 2-cm wide strip of periosteum was circumferentially resected from each osteotomy extremity. No immobilization was used thereafter. The reparative process was assessed by X-rays, histology, vascular injection, and scintigraphy. The dogs we distributed into three groups according to the time of follow-up (1, 3, and 6 months). Two kinds of repair were recognized after 3 months and were well-established after 6 months: disturbed healing with much callus (54%) and disturbed healing with absent or scanty callus (46%). In the first instance, the periosteum had regenerated and produced the external callus. The bone ends were capped with fibrocartilage; the vascularization around the defect was increased and displayed a well-defined vascular picture. In the healing pattern with absent external callus (atrophic nonunion), the bone defect was enlarged and filled with fibrous tissue, but there was no deficient vascularization in and around the osteotomy. Radioactivity counting showed an increased uptake around the osteotomy site in both types of repair, which persisted over time but was higher in the 1-month group. It was concluded that the present model yields a consistent pattern of a disturbed reparative process that mimics human cases of atrophic or hypertrophic nonunion. The differences between the two kinds of repair seemed to be related to the periosteal capacity of regeneration.

Impedence osteography: clinical applications of a new method of imaging fractures

Fracture healing usually proceeds without difficulty. However, the diagnosis of delayed or non-union is not simple and can present difficulties in management. Normal fracture healing is briefly reviewed along with some methods of assessing the progress of union. The results of using the technique of impedence osteography in a preliminary study of fracture healing are presented. These indicate that the technique can clearly show a fracture and differentiate between normal bone, a united fracture and a non-union.

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).

Static and sequential dynamic scintigraphy of the tibia following fracture

Eighty patients who had sustained a fracture of the tibial shaft were studied by scintigraphy using technetium-99m labelled methylene diphosphonate (99Tcm MDP) and a gamma camera. Static scintigrams were obtained in the early stages following injury and examined for the presence of 'cold spots' which may indicate loss of blood supply to fracture fragments; these were found in 10 per cent of cases but did not bear any definite relationship to the normal progression of union. Sequential dynamic scintigrams were obtained at intervals up to 20 weeks after fracture to determine whether a pattern of uptake of tracer could be identified which correlated with the subsequent progression of union, but no significant difference was observed between fractures healing promptly (less than 20 weeks) and those in which healing was delayed (greater than 20 weeks).

The use of bone scanning for the diagnosis and management of musculoskeletal trauma

Bone scanning provides a unique way of monitoring early metabolic changes in bone and its adjacent soft tissues after trauma. An abnormal scan may often precede radiographic changes by days or weeks. This accounts for its usefulness in the early diagnosis of occult fractures and in fractures not clinically suspected or seen on initial x-ray films in the patient with multiple trauma. Dynamic imaging along with static imaging can be used to evaluate fracture healing and predict delayed union and nonunion. The combined technique is useful in assessing many of the complications arising after trauma and provides a reliable method of observing their treatment. It is also a useful noninvasive technique in the evaluation of pathologic fractures. Bone scanning is becoming an increasingly useful adjunctive procedure in the diagnosis and management of musculoskeletal trauma. However, as with any diagnostic technique, it provides only part of the overall picture and must always be carefully correlated with the history, physical findings, radiographic changes, and other laboratory data.