Long-standing increased bone turnover at the fixation points after anterior cruciate ligament reconstruction: a positron emission tomography (PET) study of 8 patients

Background?A secure incorporation of the graft in a bone tunnel is a prerequisite for successful anterior cruciate ligament reconstruction. In this cross-sectional pilot study, we studied the healing process with positron emission tomography (PET) scanning.

Patients and methods?8 young patients underwent an anterior cruciate ligament reconstruction with a bonepatellar tendon-bone graft (BTB, n = 4) or a quadruple semitendinosus and gracilis graft (ST/G, n = 4). Regional bone turnover was quantified with an 18F-fluoride PET scan in each patient 1 day, 3 weeks, 7 months, or 22 months after surgery.

Results?The highest activity level was found 3 weeks after surgery, but the activity at the femoral fixation points was markedly increased even after 7 months. The bone turnover was almost normalized 22 months after the operation.

Interpretation?It would take at least 7 months until an anterior cruciate ligament graft, fixed with an interference screw, is completely incorporated. This finding is important for postoperative rehabilitation. Furthermore, PET is a feasible tool when studying new ways of fixing soft tissue to bone.