Figures & data
Figure 1. A. A 59-year-old man had sudden onset of knee pain and was diagnosed with osteonecrosis by MRI. B. There were no or discrete signs of osteonecrosis in the plain radiographs. Alendronate was given for 6 months and the pain disappeared. C. Radiograph after 1 year. Radiographically, no signs of osteonecrosis ever appeared.
Figure 2. A. An 82-year-old women suddenly noticed pain in her right knee. A mild osteoarthritis was seen and regarded as the cause of the symptoms. No treatment was given. (This radiograph was taken 1 month after start of symptoms). B. One year after start of symptoms, the symptoms were the same and a visible osteonecrosis was now seen with a Lotke index of 33%. The patient was referred to our department. C. The patient was treated for 13 months. Radiograph taken at follow-up 2 years after the start of treatment. The ostenecrosis had healed completely but the patient had developed mild osteoarthritis of Ahlbäck grade 1.
Figure 3. A. A 83-year-old woman at symptom start. Bisphosphonate treatment was initiated within 3 months after symptom debut. B. The patient used the drug for three months but had unwanted side effects and stopped the medication. The pain persisted and osteoarthritis gradually developed (Ahlbäck 4) and 2 years later, the patient had a joint replacement.
Table 1. Radiographic outcome and the size of the lesion (Lotke index)