Relevance of osteotomy and implant characteristics in inter- and subtrochanteric osteotomies. Experimental examination under alternating and static load after stabilisation with different devices including gamma nail osteosynthesis.

The purpose of this experimental examination was to determine the load-bearing capacity (LBC) of different inter- and subtrochanteric fractures under alternating physiological and static loads. These fractures are typical injuries of the geriatric patient, and full LBC restoration is needed for mobilisation. From patients over 60 years old at the time of death, 301 femora were obtained and randomly allocated to the following osteotomy (OT) groups: A1, flat and steep OT; A2, OT with 2/3 and complete medial cortical defect; reversed inter- (A3) and subtrochanteric OT; subtrochanteric resection and double plate compound osteosynthesis (DPCO); and the control group (no OT). Following osteosynthesis various devices were tested: condylar plate, 130 degrees angle nail plate, 145 degrees angle nail plate, double T profile angle nail plate, 135 degrees DHS, 150 degrees DHS after valgisating displacement OT, Ender nails, gamma nail and Orthofix external fixator. The femora were tested under alternating physiological load and under static load. The load-bearing capacity (LBC) was 5141 +/- 1621 N in flat A1 OT, 4501 +/- 1621 N in steep A1 OT and 3767 +/- 1500 N in A2 OT with partial defect. In reversed intertrochanteric OT the LBC was 3770 +/- 1798 N and in the reversed subtrochanteric OT, 5308 +/- 2330 N. In A2 OT with complete medial defect, only the gamma nail (5672 +/- 726 N) and the DHS after valgisating displacement OT (7261 +/- 1794 N) showed a high LBC and no alternating load instability. After subtrochanteric resection and DPCO (7415 +/- 1840 N) the LBC was the same as that of the control femora (7271 +/- 1941 N).(ABSTRACT TRUNCATED AT 250 WORDS)