Early Detection by ^99mTc-Sn-Pyrophosphate Scintigraphy of Femoral head Necrosis Following Medial Femoral Neck Fractures

Abstract

A selected series of 24 patients with displaced medial femoral neck fracture, treated with closed reduction and osteosynthesis with cancellous bone screws (ASIF), were investigated.

During an observation period of 6 to 26 months, serial hip joint scintigraphies were performed and compared with serial X-ray examinations. At the first scintigraphic examination performed on average 5–6 weeks after the fracture, two separate investigators found a decreased amount of activity or no activity in the femoral head of 10 and 8 patients, respectively. At the second scintigraphic examination performed on average 11.1 weeks after the fracture both investigators found no activity or a decreased amount of activity in 8 patients. This figure declined to 7 during the following period, because one patient with decreased activity was recorded as having normal activity IS months after the fracture. These 7 patients all developed radiological signs of femoral head collapse on average 16.3 months after the fracture (range 5–26 months), whereas their scintigrams displayed decreased or absent tracer uptake on average 1.2 months after the fracture (P < 0.01). None of the patients with initially normal or increased uptake later showed decreased or absent uptake during the study and none developed radiological collapse.

It may be concluded that absent or decreased uptake of ^{9, m}Tc-Sn-pyrophosphate in the femoral head following medial femoral neck fracture indicates femoral head necrosis and a high risk of late segmental collapse, whereas normal or increased uptake implying preserved blood supply means that late segmental collapse will probably never develop.

Key Words:

• bone vitality
• femoral head collapse
• femoral head necrosis
• medial femoral neck fracture
• scintigraphy
• ^99m Tc-Sn-pyrophosphate