PROSPECTIVE FOLLOW UP OF PATIENTS AFTER OSTEOSYNTHESIS OF UNSTABLE OSTEOPOROTIC INTERTROCHANTERIC FRACTURES

Abstract

Aims: In spite of approved methods of osteosynthesis of proximal femoral fractures using modern implants stabilisation still may fail especially in unstable osteoporotic fractures which is a cause of revision surgeries and unsatisfactory functional results. The goal of our study was to determine predisposing factors of failure of either DHS or PFN osteosynthesis with respect to the degree of osteoporosis. At the same time we evaluated clinical results one year after surgery and evaluated occurrence of further osteoporotic fractures.

Methods: Within the framework of a research plan (2005–2009) patients with low energy fractures of trochanteric area with qCT proven osteoporosis have been randomised. Unstable intertrochanteric fractures were operated by either DHS or PFN osteosynthesis after adequate reduction. During surgery one bone sample was taken from the femoral head prior to insertion of head screw located at the tip of the screw and the second sample was taken from iliac crest. Samples from the femoral head were examined by histomorphometry. Relationship between histomorphometry and migration of osteosynthetic material was evaluated. After surgery patients were examined in osteology department including DEXA and received appropriate treatment of osteoporosis. Orthopaedic follow up was performed 6 weeks, 3, 6 and 12 months after surgery when patients were evaluated by Harris hip score. Results were evaluated statistically.

Results: From September 1. 2005 to August 31. 2006 55 patients with unstable intertrochanteric fractures had been randomised. DHS was used in 26 patients and PFN in 29 patients. The average age of the patients was 75,6 years. Only patients who were able to sign informed consent were elegible for randomisation. The average qCT T-score was −3,2 and the qCT Z-score was −1,1. In addition to osteoporosis osteomalacia was proven histologically in one patient. Secondary osteoporosis was proven in 15 per cent of all patients. 49 patients were examined 1 year after operation. Failure of osteosynthesis was observed in four cases (7,3 per cent, 2x DHS and 1x PFN cut out phenomenon, 1 case of PFN head screw migration). Migrating PFN screw was removed. There were no other revision surgeries. The average qCT T-score in patients with failure of osteosynthesis was −4,3, Z-score −2,1. The average HHS one year after surgery was 67,3.

Conclusions: In patients with proven osteoporosis in spite of correct surgical technique risk of osteosynthesis failure is increased. Optimized surgical techniques and implants may still improve surgical results in patients with severe osteoporosis (qCT T-score lower than −4).