Stress reactions and fractures around the ankle, especially in the distal tibia and fibula, are important overuse injuries in endurance athletes. While bone scan (Spyridonidis et al. 2014; Krestan et al. 2011) and MRI are established diagnostic tools (Sijbrandij et al. 2002), the sensitivity and specificity for SPECT/CT will have to be determined first. However, a more prominent role of SPECT/CT in the future is likely, since this modality combines the advantages of bone scintigraphy which shows metabolic activity, and CT may show osteopenia, the earliest finding in early stress fracture (Gaeta et al. 2005; Mohan et al. 2010) (Fig. 36.3).

Ankle impingement can be due to abnormal configuration of articulating bones; extreme movements of normally shaped joint partners, e.g. in ballet dancers; accessory bones interfering with otherwise normal joint partners, e.g. os trigonum or as a result of osteophyte formation around the ankle due to degenerative processes, e.g. in soccer’s ankle. It can be located anteriorly (e.g. soccer’s ankle) or posteriorly (e.g. dancer’s ankle). Only in true osseous impingement, bone scan and SPECT/CT play a role, since soft tissue impingement cannot be depicted with current nuclear imaging methods. However, most cases of bony impingement (in particularly anterior impingement) can sufficiently be diagnosed using conventional X-rays or MRI. SPECT/CT might help in unclear cases of persistent ankle pain and then identifies, e.g. an impinging os trigonum with increased metabolic uptake as a reason for deep or posterior ankle pain. In these patients, SPECT/CT is a richer source of information (Fig. 36.4).

Nuclear medicine techniques have no role in diagnosing acute traumatic fractures. However, SPECT/CT might help finding a) stress fractures (see above) or b) persistent pain in the context of an already detected and treated fracture. It is able to precisely show osseous nonunion as well as associated metabolic uptake representing symptomatic pseudoarthrosis (Figs. 36.5 and 36.6).

It is very interesting to see the differences of the size of the bone bruise/bone oedema in the MRI and the focal activity in the SPECT/CT. This is not only true for osteochondral lesions like discussed above but also for perfusion-based disorders such as avascular talar necrosis or chronic regional pain syndrome. While SPECT/CT specifically highlights metabolic activity of osteoblasts, for oedema pattern in MRI, it has been shown that this histologically equals a number of noncharacteristic histological abnormalities which make interpretation difficult (Zanetti et al. 2000). For atraumatic medial knee pain, it has even been shown that scintigraphy is more sensitive than MRI (Buck et al. 2009) (Fig. 36.7).