Biomechanical Causes Analysis And Precaution Of Intraoperative Periprosthetic Fracture Of The Femur In Total Hip Replacement With The Collum Femoris Preserving Prosthesis

Objective:As is received by both sides of doctors and patients increasingly,total hip replacement (THR)cures advanced stage of sickness of the hip . Postoperative long-term complications , such as osteolysis,prosthesis loosening,stress shielding and osteoporosis,accompanying with no- collum femoris preserving ,always lead to prosthesis overhauling . Some patients need to several prosthesis overhauling , but obvious deossification seriously affects postoperative effects . Total hip replacement with collum femoris preserving (CFP) prosthesis , which is designed by Germanic L I N K company and Doctor P i p ino , who is famous as a joint expert in Italy , are gradually cured advanced stage of sickness of the hip in young patients . Because of postoperative normal stress force distribution after CFP ,bone mass of proximal femur seldom loss .【1】According to related postoperative mid-term effect reports ,the rates of postoperative complications and femoral pain in total hip replacement with collum femoris preserving is obviously lower than that in traditinational hip replacement . Although the rate of periprosthetic fracture of the femur (PFF) is not high ,it is difficult to select a perfect opportunity to treat it . The way of treatment directly affects service life of prosthesis and qualities of patients , lives .The purpose of this clinical test is to analyze the main causes of intraoperative periprosthetic fracture of the femur in total hip replacemen with collum femoris preserving,deepen understanding the relationship of the prosthesis,marrow of the femur and the osteotomy height of femoral neck retrospectively and to cut down the complication .Methods:A retrospective study(January 1,2009, to January 1,2011 ) is conducted on 7 of 294(bilaterally affected in 31 patients)non-cenmented THR with collum femoris preserving cases ,wich occurred intraoperative periprosthetic fracture of the femur . All the 7 patients enecourted in primary THR . The series comprised 6 males and 1 female(bilaterally affected in 4 patients) . The average age was 51.5 years(range 32 to 62 years). Four patients suffered from avascular necrosis of thefemoral head , two osteoarthrisis secondary to acetabular dysplasia ,one osteoarthrisis secondary to femoral head necrosis . Comparing preoperative X-ray with postoperative X-ray with intraoperative periprosthetic fracture of the femur,we measured the width of bone medullary cavity and prosthesis at the plane of lesser trochanter(T),20mm above and bolow the lesser trochanter(T+20,T+20) ,fracrure(F) ,femoral neck anteversion(FNA),cervicofemoral(CA), the reserved length of trochanteric fossa(RLTF), and the neck length (NL) . Meanwhile we random select 100 cases ( January 1,2009 to January 1,2011) ,who received non-cenmented collum femoris preserving THR ,but not occurred intraoperative periprosthetic fracture of the femur . The series comprised 50 males and 50 female . The average age was 48.1 years(range 23 to 71 years). Also we measured the 100 patients and the 7 patients reserved length of trochanteric fossa(RLTF),the coronal rate of prosthesis end and marrow(R),calcar femorale (CF) .Results:1 In our hospital , 7 of 294 total hip replacement with collum femoris preserving prosthesis take plae femorar fractures , and the rate is 2.38﹪。2 Sorted by fracture position , 2 femoral neck , 1 greatest curvature of prosthesis corresponging femur , 4 the end of prosthesis corresponging femur .3 In the 7 occurred intraoperative periprosthetic fracture of the femur , reserved length of trochanteric fossa is 2.2～17.6mm , calcar femorale 16～24mm , the coronal rate of prosthesis end and marrow range from 83.3﹪to 100﹪.4 In the random select 100 cases , reserved length of trochanteric fossa is 12～21mm , calcar femorale 16～28.8mm , the coronal rate of prosthesis end and marrow range from 66.7﹪to 83.3﹪. Conclusion:1 When osteotomy angle changes , the prosthesis approach to hemi-femur and abnormal stress distribution . The end of prosthesis corresponging femur , where stress concertration , is easy to take place oblique fracture ( typeⅣof AAOS classification).2 If femoral cortex humble , and the potoperative large rangeability of emoral neck anteversion and cervicofemoral , greatest curvature of prosthesis corresponging femur is apt to take place comminuted fractures(typeⅤof AAOS classification).3 If the diameter of proximal prosthesis is bigger , and that of end of prosthesis suitable , it is easy to take place split fracture at femoral neck and calcar femorale take place(typeⅡorⅢof AAOS classification) . If the end diameter of prosthesis is bigger , that of proximal prosthesis suitable ,the end of prosthesis corresponging femur , is easy to take place oblique fracture (typeⅣof AAOS classification) .