***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: The proximal femoral nail ( PFN ) is a recently introduced intramedullary system , design ed to improve treatment of unstable trochanteric fractures of the hip . In a multicentre prospect i ve clinical study , the intra-operative use , complications and outcome of treatment using the  PFN ( n = 211 ) were compared with those using the gamma nail ( GN ) ( n = 213 ) . The intra-operative blood loss was lower with the PFN ( 220 ml v 287 ml , p = 0.001 ) . Post-operatively , more lateral protrusion of the hip screws of the PFN ( 7.6 % ) was documented , compared with the gamma nail ( 1.6 % , p = 0.02 ) . Most local complications were related to suboptimal reduction of the fracture and /or positioning of the implant . Functional outcome and consolidation were equal for both implants . Generally , the results of treatment of unstable trochanteric fractures were comparable for the PFN and GN . The pitfalls and complications were similar , and mainly surgeon- or fracture-related , rather than implant-related We investigated whether a proximal femoral nail can be implanted without a distal locking screw in AO/OTA 31-A1 and 31-A2 pertrochanteric stable femur fractures . A multicentre , r and omised study was conducted in six level-two trauma centres in our area ( Puglia , Italy ) . A total of 333 patients received their allocated intervention ( 162 in the locking group [ LG ] and 171 in the unlocking group [ UG ] ) and 266 patients were included in the final analysis at 1year . Our data showed no statistically significant difference between the two groups at 1-year follow-up for ability to walk , SF-36 question naire results , residual pain ( visual analogue scale [ VAS ] score ) and level of overall satisfaction . There were also no statistically significant differences between groups for mortality and length of hospital stay . Conversely , the UG was associated with shorter operation and fluoroscopy times , shorter surgical incision length , and less blood loss and residual thigh pain . Pertrochanteric stable fractures ( 31-A1 , 31-A2 ) can be treated successfully with intramedullary nails without distal locking , reducing patient and clinical personnel radiation exposure and sanitary costs ( surgery time and screws costs ) Background : Most hip fractures are treated surgically , with use of either internal fixation or prosthetic replacement of the femoral head . The presence of these implants increases the risk of a later femoral fracture in susceptible osteoporotic patients . The purpose of this study was to analyze the incidence of and risk factors for implant-related fractures of the femur after previous hip fracture surgery . Methods : Over a ten-year period from January 1988 to December 1997 , 6230 patients ( median age , eighty-two years ; male : female ratio , 1247:4983 ) who sustained a total of 6696 hip fractures were admitted to the Edinburgh Orthopaedic Trauma Unit . Demographic information on the patients and details of the original treatment of the hip fracture were prospect ively coded and entered into a trauma data base . All subsequent readmissions due to a femoral fracture related to the implant were prospect ively audited and extracted for the purpose s of this study . Results : One hundred and forty-one patients sustained an ipsilateral fracture of the femur at a median of twenty-four weeks following the original hip fracture surgery . Survivorship analysis of the hip fracture population revealed an overall rate of subsequent femoral fracture of 2.9 % at five years , which increased to 5.1 % at ten years . The median age and gender distribution of the patients who sustained a subsequent femoral fracture were similar to those of the hip fracture population as a whole . Two-thirds of the fractures propagated from the tip of the implant . Analysis of the subsequent fractures according to the type of implant used to treat the original fracture revealed considerable differences in incidence . The incidence was relatively high in the patients initially treated with a Gamma nail ( 18.74 fractures per 1000 person-years ) or a cementless hemiarthroplasty ( 11.72 per 1000 person-years ) and was relatively low in those treated with a compression hip screw ( 4.46 per 1000 person-years ) , cannulated screws ( 4.50 per 1000 person-years ) , or a primary arthroplasty with cement ( 6.2 per 1000 person-years ) . The highest incidence of fracture was seen in the patients who had required an arthroplasty with cement as a revision procedure following failure of a primary implant ( 22.39 per 1000 person-years ) . Conclusions : Implant-related fractures following hip fracture surgery are more common than has previously been appreciated . The risk of later ipsilateral femoral fracture is increased by the use of a Gamma nail or a cementless hemiarthroplasty to treat the original hip fracture The aim of this non-r and omised prospect i ve study was to evaluate the short-term outcome of Gamma nail and dynamic hip screw ( DHS ) fixation in the treatment of subtrochanteric hip fractures due to low-energy trauma in the elderly . All of the 1,624 femoral hip fractures in 1,511 patients of the Oulu Hospital , aged over 49 years , were prospect ively registered from 1991−1999 using special forms . Seventy-three ( 4.5 % ) of the fractures were subtrochanteric . After exclusions , 58 patients constituted the final study group . Of these , 43 were treated with Gamma nails and 15 with DHS . Background factors before the fracture , complications , reoperations and functional parameters at 4 months were recorded using st and ardised forms . Intraoperative and hospital data were collected from patient records . The Seinsheimer fracture types IIIA , IIC and V were the most common fracture patterns when the Seinsheimer classification system was used , and Fielding II and AO 31A3.3 , respectively , were the most common types in the Fielding and AO classification system . There were four ( 9 % ) intraoperative complications in the Gamma nail group as compared to none in the DHS group . On the other h and , postoperative complications were more common in the DHS group ( 27 % ) than in the Gamma nail group ( 7 % ) . We recognised a correlation between certain fracture types and the likelihood of typical intra- or postoperative complications or difficulties with both devices : In Gamma nailing , difficulty in closed reduction as well as the rate of open reduction and the use of supplementary fixation were most frequent in the Seinsheimer IIC fractures . It is also noticeable that all of the postoperative device failures and fracture displacements of the DHS group occurred in the Seinsheimer type IIIA category . Detailed fracture classification is essential for the choice of the fixation device , and the present study confirms the presumption that , despite the perioperative problems associated with Gamma nailing , this technique may be preferable to plate fixation for specific fracture types with medial cortical comminution , such as Seinsheimer type IIIA.RésuméLe but de cette étude prospect i ve non r and omisée est d’évaluer l’évolution à court terme du traitement par clou Gamma ou par vis DHS des fractures sous-trochantériennes par traumatisme à basse énergie chez le sujet agé . Parmi les 1,624 fratures de la hanche enregistrées chez 1,511 patients de plus de 49 ans , de janvier 1989 à decembre 1996 , 73 ( 4,5 % ) étaient des fractures sous-trochantériennes . Le groupe d’étude était de 58 patients do nt 43 traités par clou Gamma et 15 avec vis DHS .  Les antécédents , les complications et les paramètres fonctionnels à 4 mois étaient notés avec recueil st and ardisé et les informations sur l’hospitalisation étaient relevées dans les dossiers des patients . Les fractures les plus fréquentes étaient de type Seinsheimer IIIA , IIC , et V ou de type Fielding II et AO 31A3 dans ce dernier système . Il y avait 4 complications opératoires dans le groupe Gamma et aucune dans le groupe DHS t and is que les complications post-opératoires étaient plus fréquentes dans le groupe DHS que dans l’autre . Il existait une corrélation entre certains types de fractures et la survenue de complications avec les 2 matériels utilisés : dans le groupe Gamma la difficulté de réduction et la nécessité d’une fixation complémentaire étaient plus fréquent avec les fractures de type Seinsheimer IIC ; dans le groupe DHS tous les échecs de fixation survenaient pour des fractures de type Seinsheimer IIIA . La classification précise des fractures est essentielle pour le choix du matériel . L’étude présente confirme que l’ostéosynthèse par clou Gamma est préférable lorsqu’il existe une comminution corticale interne comme dans les fractures de type Seinsheimer IIIA INTRODUCTION Few clinical studies have analyzed the utility of distal interlocking screws in stable and unstable intertrochanteric fractures treated with intramedullary devices . We performed a prospect i ve analysis comparing short unlocked versus short dynamic and short static distal locked intramedullary nails . MATERIAL S AND METHODS Nine level-II trauma centres were involved in the study . 240 patients over the age of 65 with a stable ( AO/OTA 31-A1 ) or unstable intertrochanteric fracture ( AO/OTA 31-A2 ) were prospect ively investigated . The same type of nail was used in every patient . Patients were r and omly divided into 3 groups according to the type of distal locking used . Intra-operative variables were examined and patients were followed clinical ly and radiographically at 1 , 3 , 6 , 12 months postoperatively . All complications were recorded . RESULTS A total of 212 patients completed 1 year of follow-up visits . In the Unlocking Group ( UG ) the operation time , blood loss , fluoroscopy time , total length of incision were significantly decreased compared to both the Dynamic Group ( DG ) and the Static Group ( SG ) ( p < 0.05 ) . Conversely , no reliable differences in intraoperative variables were noted between the Dynamic Group and the Static Group ( p > 0.05 ) . In terms of time of fracture union we found no differences among the three Groups ( p > 0.05 ) . Moreover , no cases of limb shortening > 1 cm or varus collapse were detected in any group . The 3 Groups were similar in terms of HHS , SF-12 and Barthel index results at 1-year follow-up ( p > 0.05 ) . Finally , no significant differences were demonstrated across the three Groups in terms of major complications . CONCLUSIONS This clinical study further confirms the hypothesis that short intramedullary nails do not need to be locked for stable and unstable intertrochanteric fractures Objectives : This study compared the torsional properties of stable intertrochanteric femur fractures in a cadaveric bone model using 2 different distal fixation strategies : unlocked long cephalomedullary nailing versus dynamically locked nailing . Methods : Fourteen matched pairs of cadaveric femora were r and omly assigned to 1 of 2 distal fixation treatment groups : a single distal interlock screw placed in the dynamic orientation or no distal screw fixation . A stable 2-part intertrochanteric fracture was produced . Specimens were potted and mounted in a double gimbal fixture , facilitating unconstrained motion in the sagittal and coronal planes . Specimens were cyclically loaded dynamically in both internal and external rotation . Range of motion , internal and external rotation stiffness , torsion stiffness , torsion yield , and ultimate torsion magnitude were calculated . Results : The sample s instrumented with a distal locking screw reported statistically significantly greater internal ( 1.54 ± 0.81 N·m per degree vs. 1.08 ± 0.35 N·m per degree ; P = 0.026 ) and external rotational stiffness ( 1.42 ± 0.72 N·m per degree vs. 0.86 ± 0.36 N·m per degree ; P = 0.009 ) . Sample s with locked distal fixation were statistically stiffer and displayed statistically less displacement at the yield and peak torque . The yield torque was statistically significantly higher in the sample s without distal fixation ( 14.2 ± 3.3 N·m per degree vs. 10.6 ± 3.8 N·m per degree ; P = 0.037 ) . The peak torque was comparable between locked and unlocked sample s ( 15.0 ± 4.6 N·m per degree vs. 16.2 ± 4.2 N·m per degree ; P = 0.492 ) . Conclusions : Distal locking of femoral intramedullary nails  increases the stiffness of the nail – femur construct . Unlocked sample s displayed statistically significant higher yield torque while maintaining comparable peak torque as the locked sample s. This study indicates that treating stable intertrochanteric fractures  with unlocked long intramedullary nails may be an acceptable option , although further clinical study will be needed to test this assertion 
    Output:
    
Conclusion : The present meta- analysis suggests that intramedullary nailing without distal locking is reliable and acceptable option for treating intertrochanteric fracture .
The advantages are reduced operative time , decreased fluoroscopy time , smaller size of incision and decreased complication rate .