Failure Analysis And Reoperation Of Dynamic Hip Srew Fixation For Intertrochanteric Fractures In The Eldly

Objective:To analyze the causes assosiated with the faliure of dynamic hip srew fixation in the eldly and to explore effective way of reoperation.METHODS:A total of150elderly patients with an intertrochanteric fracture treated with DHS in the Second Affiliated Hospital of Shan dong medical university and Weihai Hospital from January2007to January2011were retrospectively analyzed.Eight possible factors (sex,age, comorbidity,type of fractures,bone density, reduction states, implant placement, posteromedial cortex distance) were analyzed using t-test and x2-test. P<0.05was considered statistically significant.All variables that don’t meet to this criterion were eliminated directly as irrelevant variables. All relevant factors are introduced to the Logistic regression model to output the correlation between the variables.Individualized reoperation planning was made according to assessment of the risk factors of11failed patents treated with DHS in the Second Affiliated Hospital of Shan dong medical university and Weihai Hospital from January2007to January2011. PFN was used to restablize the young failed pations with more requirement of motion and no severe osteoporosis. Hemiarthroplasty was applied to the elder patients with less requirement of motion and severe osteoporosis. All patients were followed up to get detailed information.Harris scoring system was used to evaluate the hip function after reoperation.Result:All cases were followed up for3to24months, and19cases got fixation failure.In single variable analysis,type of fractures,bone density, implant placement, posteromedial cortex distance had significant relation to failure of DHS (P=0.02,0.02,0.00,0.00),but sex,age, comorbidity had no significant relation to failure of DHS(P=0.76,0.86,0.40).There was no significance between the two groups in anatomical reduction or functional reduction(P=0.67). The multivariate logistic regression analysis shows that type of fractures,bone density, TAD, posteromedial cortex distance were risk factors leading to the failure of DHS and TAD was the dominant factor. According to the analysis of the patients,the failure of DHS may due to:comminuted fracture and inappropriate implant placement(7patients),severe osteoporosis(3patients),too early loading(patients). After fixator removal,4cases were treated with PFN fixation,7cases were treated with hemiarthroplasty. In the following5-24months,all cases got bone healing and satisfactory hip function witout fixation failure and necrosis of femoral head.Conclusion1.Type of fractures,bone density, TAD and posteromedial cortex distance were risk factors leading to the failure of DHS.2.As for the application of dynamic hip screw fixation, the TAD value should be not higher than25mm for the general patients. It might be inadvisable to overemphasize anatomical reduction, but an anatomical reduction with posteromedial apposition is necessary.3.Dynamic hip screw is not the first choice for the elder cases of unstable fractures combined with severe osteoporosis.4.Individualized reoperation planning should be made according to the patents age,type of fractures,bone density and requirement of motion.Both PFN and hemiarthroplasty could be used to treat the failed patients of DHS,and could obtain ideal surgical outcome.