Radiographic and scintigraphic courses of union in cervical interbody fusion: hydroxyapatite grafts versus iliac bone autografts.

UNLABELLED

This study investigated the radiographic and scintigraphic courses of union in cervical interbody fusion using hydroxyapatite (HA) grafts or iliac bone autografts.

METHODS

Twelve patients underwent both serial plain radiography and bone scintigraphy during the 12 mo after surgery. Serial plain radiographs were obtained every month until the end of the study period. Bone scintigrams with 99mTc-hydroxymethylene diphosphonate (HMDP) were obtained at 2 wk and at 1, 2, 3, and 6 mo. Uptake of 99mTc-HMDP in the graft was expressed as a ratio of the counts in the graft to those in the axis.

RESULTS

In the HA graft group, the plain radiographs of all patients showed a radiolucent stripe that disappeared 7.3 +/- 1.5 (mean +/- SD) months after surgery. In the autograft group, a radiolucent stripe around the graft was not seen for any patient, and union was confirmed by follow-up radiographs within 6 mo after surgery. The serial changes in the 99mTc-HMDP uptake ratio showed no difference between the 2 groups. The 99mTc-HMDP uptake ratio peaked 1 mo after surgery and decreased rapidly to a plateau within 2 mo.

CONCLUSION

In the HA graft group, despite the presence of a radiolucent stripe around the graft for more than 6 mo, the scintigraphic course of union was not different from that in the autograft group. The likelihood is that the presence of a radiolucent stripe around the HA graft in the early months after surgery is not always a sign of pseudoarthrosis.