76 Part I Chapter 3 Figure 3 Bone scan with SPECT/CT of a patient with persisting pain 7 months after ACL reconstruction with use of a biodegradable interference screw, which is used for graft fixation. (A) Unremarkable blood pool phase. (B) Markedly increased BTO centrally in both distal femur and proximal tibia on the left, with limited anatomical information on the localization of the uptake in relationship to the biodegradable interference screw and tibial tunnel. (C) Transversal and coronal SPECT/CT reconstructions of the left knee. Note the increased BTO at the medial side of the trajectory of the biodegradable interference screw (arrow), consistent with physiological reaction in the trajectory of the biodegradable screw, considering the short time after surgery. Low BTO at the lateral side corresponds to minimal pathological cystic degradation. (D) A focus of increased BTO at the tibial tunnel exit (arrowhead) indicates rotational instability due to nonanatomical ACL graft position.