Displaced femoral neck fractures : studies on osteosynthesis and total hip arthroplasty

Abstract

The treatment of femoral neck fractures has for many years in Sweden been reduction and osteosynthesis with nails or screws. For displaced fractures the risk of complications such as avascular necrosis and non-union is up to 50 %, often leading to a secondary operation with an arthroplasty. Because of this high risk of complications the primary treatment in many countries is an arthroplasty. There is no consensus of which treatment that is to be recommended for a patient with a displaced femoral neck fracture. We performed a prospective randomized study between ostosynthesis and cemented total hip arthroplasty in 100 patients. All fractures were displaced, and patients participating in the study were independently living and without any other serious medical condition. Bone mass and muscle volume measurements were also performed. Scintigraphy of extracted femoral head specimens was also done. At the time of fracture there was no difference in bone mass between the fractured and the uninjured leg, but after six months there was a loss of trabecular bone on both sides, more pronounced on the fractured side. The muscle volume decreased on the fractured side, but increased on the uninjured side.

Independently of which treatment the patient had undergone, osteosynthesis or total hip arthroplasty, there was a loss of bone mass and muscle volume after eighteen months on the fractured side. The bone loss on the fractured side, in patients with avascular necrosis after a displaced femoral neck fracture, was still persistent six months after a reoperation with a total hip arthroplasty despite the gain in muscle volume on that side. The radionuclide inside the femoral head after a displaced femoral neck fracture was distributed in three different patterns, general uptake, uptake close to the fracture and uptake at the ligamentum capitis femoris. In this selected group of patients with displaced femoral neck fractures the functional results were better after total hip arthroplasty than osteosynthesis already after three months, and the superior results remained up to four years. The risk for a reoperation for patients treated with osteosynthesis was over 50 %.