Diagnosis of the cause of massive edema of the lower limbs in patients after spinal cord injury (SCI) can be difficult because of loss of pain sensation, commonly occurring in this group of patients. This paper reviews several different pathologies that can lead to lower-limb edema and the associated diagnostic difficulties. We present four cases of patients with massive edemas of lower limbs at different times after SCI undergoing treatment in the Department of Rehabilitation, University Hospital in Bydgoszcz, Poland. All patients had a lack of pain sensation in the lower limbs and significantly elevated levels of D-dimer. In two cases, deep vein thrombosis (DVT) and intramuscular hematomas (IHs) were diagnosed. IHs were probably a consequence of antithrombotic treatments implemented due to the occurrence of DVT. Heterotopic ossification (HO) was diagnosed in a third case, and, in another patient, who was hospitalized for the longest period after injury, we found humeral bone fractures. Heterotopic ossification, intramuscular haematomas, and bone fractures of the lower limb can mimic DVT. Careful observation of the edema evolution is recommended, as the onset of new symptoms may indicate a different cause of edema from that initially established.