human
***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: We have compared the biomechanical nature of the reconstruction of the hip in conventional total hip arthroplasty ( THA ) and surface replacement arthroplasty ( SRA ) in a r and omised study involving 120 patients undergoing unilateral primary hip replacement . The contralateral hip was used as a control . Post-operatively , the femoral offset was significantly increased with THA ( mean 5.1 mm ; -2.8 to 11.6 ) and decreased with SRA ( mean -3.3 mm ; -8.9 to 8.2 ) . Femoral offset was restored within sd 4 mm in 14 ( 25 % ) of those with THA and in 28 ( 57 % ) of the patients receiving SRA ( p < 0.001 ) . In the THA group , the leg was lengthened by a mean of 2.6 mm ( -6.04 to + 12.9 ) , whereas it was shortened by a mean of 1.9 mm ( -7.1 to + 2.05 ) in the SRA group , compared with the contralateral side . Leg-length ine quality was restored within sd 4 mm in 42 ( 86 % ) of the SRA and 33 ( 60 % ) of the THA patients . The radiological parameters of acetabular reconstruction were similar in both groups . Restoration of the normal proximal femoral anatomy was more precise with SRA . The enhanced stability afforded by the use of a large-diameter femoral head avoided over-lengthening of the limb or increased offset to improve soft-tissue tension as occurs sometimes in THA . In a subgroup of patients with significant pre-operative deformity , restoration of the normal hip anatomy with lower pre-operative femoral offset or significant shortening of the leg was still possible with SRA The purpose of this study was to compare conventional and navigated technique and a recently developed straight hip stem for uncemented primary total hip arthroplasty . The results of two consecutive implantation series of 42 patients ( nonnavigated ) and 42 patients ( navigated )  were analysed for implant positioning and complications . All surgeries were performed by the investigator . Radiographic analysis of cup position showed a significant improvement with reduced radiologic inclination ( 53 degrees nonnavigated /44 degrees navigated ; P < .001 ) and higher anteversion ( 7 degrees nonnavigated /12 degrees navigated ; P < .001 ) . The mean postoperative limb length difference was 6.2 mm ( SD , 9.0 for nonnavigated ) and 4.4 mm ( SD , 6.4 for navigated ) . Intraoperative and early postoperative complications were not different . No dislocation occurred in either group . There was one intraoperative trochanter fracture that was not revised ( nonnavigated ) and one revision because of a periprosthetic fracture caused by fall down during rehabilitation ( navigated ) . We conclude that acetabular implant positioning can be significantly improved by the use of navigated surgery technique . The data for postoperative limb length difference were still similar but within the expected range in both groups . The effect of improved cup positioning on mid and longterm results for both groups has to be investigated further We prospect ively evaluated acetabular cup placement in total hip arthroplasty with an imageless computer navigation system  or using conventional manual technique . The achieved cup orientation in the manual group had substantially larger variances and greater placement error than the navigation cases . The use of navigation was ab and oned in 3 cases because of excessive pelvic tilt and unreliable registration of the pelvis . Computer navigation system helped improve the accuracy of the acetabular cup placement for total hip arthroplasty in this study . The variation between the intraoperative navigation readings and the computed tomographic values suggests that relying on palpation of bony l and marks through drapes and tissue is a limitation of this method . Further , the variation in pelvic tilt has an effect on cup placement that requires further studies We report the kinematic and early clinical results of a patient- and observer-blinded r and omised controlled trial in which CT scans were used to compare potential impingement-free range of movement ( ROM ) and acetabular component cover between patients treated with either the navigated ' femur-first ' total hip arthroplasty ( THA ) method ( n = 66 ; male/female 29/37 , mean age 62.5 years ; 50 to 74 ) or conventional THA ( n = 69 ; male/female 35/34 , mean age 62.9 years ; 50 to 75 ) . The Hip Osteoarthritis Outcome Score , the Harris hip score , the Euro-Qol-5D and the Mancuso THA patient expectations score were assessed at six weeks , six months and one year after surgery . A total of 48 of the patients ( 84 % ) in the navigated ' femur-first ' group and 43 ( 65 % ) in the conventional group reached all the desirable potential ROM boundaries without prosthetic impingement for activities of daily living ( ADL ) in flexion , extension , abduction , adduction and rotation ( p = 0.016 ) . Acetabular component cover and surface contact with the host bone were > 87 % in both groups . There was a significant difference between the navigated and the conventional groups ' Harris hip scores six weeks after surgery ( p = 0.010 ) . There were no significant differences with respect to any clinical outcome at six months and one year of follow-up . The navigated ' femur-first ' technique improves the potential ROM for ADL without prosthetic impingement , although there was no observed clinical difference between the two treatment groups Background This study compared the efficacy and safety of 3 different anesthesia techniques used in  total hip arthroplasty ( THA ) . Material / Methods We allocated 198 patients preparing to undertake THA into 3 groups : general anesthesia group ( GA group , n=66 ) , caudal epidural anesthesia group ( CEA group , n=66 ) , and spinal-epidural anesthesia group ( SEA group  , n=66 ) . We compared postoperative adverse effects occurring in patients of the 3 anesthesia groups . The Visual Analog Scale ( VAS ) score , Minimum Mental State Examination ( MMSE ) score , and β-amyloid ( Aβ ) expression were calculated to determine the effects of different anesthesia on the postoperative pain and cognitive dysfunction of patients . Results The CEA and SEA groups had lower rates of perioperative adverse effects than in the GA group . Patients in the GA group required significantly higher administration of analgesics after the surgery than those in CEA and SEA groups . Higher Aβ expression levels and VAS scores , as well as lower MMSE scores , were also seen in the GA group compared with the other 2 groups . Conclusions CEA and SEA were more effective than GA in THA , and CEA seemed to be a better anesthesia technique than SEA Background Restoration of biomechanics is a major goal in THA .  Imageless navigation enables intraoperative control of leg length equalization and offset reconstruction . However , the effect of navigation compared with intraoperative fluoroscopy is unclear . Questions / purpose sWe asked whether intraoperative use of imageless navigation ( 1 ) improves the relative accuracy of leg length and global and femoral offset restoration ; ( 2 ) increases the absolute precision of leg length and global and femoral offset equalization ; and ( 3 ) reduces outliers in a reconstruction zone of ± 5 mm for leg length and global and femoral offset restoration compared with intraoperative fluoroscopy during minimally invasive ( MIS ) THA with the patient in a lateral decubitus position . Methods In this prospect i ve study a consecutive series of 125 patients were r and omized to either navigation-guided or fluoroscopy-controlled THA  using sealed , opaque envelopes . All patients received the same cementless prosthetic components through an anterolateral MIS approach while they were in a lateral decubitus position . Leg length , global or total offset ( representing the combination of femoral and acetabular offset ) , and femoral offset differences were restored using either navigation or fluoroscopy . Postoperatively , residual leg length and global and femoral offset discrepancies were analyzed on magnification-corrected radiographs of the pelvis by an independent and blinded examiner using digital planning software . Accuracy was defined as the relative postoperative difference between the surgically treated and the unaffected contralateral side for leg length and offset , respectively ; precision was defined as the absolute postoperative deviation of leg length and global and femoral offset regardless of lengthening or shortening of leg length and offset throughout the THA . All analyses were performed per intention-to-treat . Results Analyzing the relative accuracy of leg length restoration we found a mean difference of 0.2 mm ( 95 % CI , −1.0 to + 1.4 mm ; p = 0.729 ) between fluoroscopy and navigation , 0.2 mm ( 95 % CI , −0.9 to + 1.3 mm ; p = 0.740 ) for global offset and 1.7 mm ( 95 % CI , + 0.4 to + 2.9 mm ; p = 0.008 ) for femoral offset . For the absolute precision of leg length and global and femoral offset equalization , there was a mean difference of 1.7 ± 0.3 mm ( p < 0.001 ) between fluoroscopy and navigation . The biomechanical reconstruction with a residual leg length and global and femoral offset discrepancy less than 5 mm and less than 8 mm , respectively , succeeded in 93 % and 98 % , respectively , in the navigation group and in 54 % and 95 % , respectively , in the fluoroscopy group . Conclusions Intraoperative fluoroscopy and imageless navigation seem equivalent in accuracy and precision to reconstruct leg length and global and femoral offset during MIS THA with the patient in the lateral decubitus position . Level of Evidence Level I , therapeutic study . See the Instructions for Authors for a complete description of levels of evidence We present a match-paired study between computer-assisted and freeh and techniques using a short modular femoral stem ( Metha ; B. Braun Aesculap , Tuttlingen , Germany ) in  total hip replacement ( THR ) .  Surgical time , clinical outcome , dislocation rate , limb length , and offset in 44 patients with ideal indication for this more conservative implant were assessed . Despite both longer surgical time and similar early outcomes , the results showed how computer-assisted techniques allow easier management of limb length discrepancy and offset restoring . We believe that navigated short modular stems are safe for less invasive THR Navigation in primary total hip arthroplasty has a history of over 20 years . During this process , imageless computer navigation can be particularly helpful in optimally restoring the hip ’s biomechanics . This involves the accurate placement of the acetabular component with the determination of the anteversion and abduction , whereby the navigated femur-first technique also allows for a calculation of the combined anteversion . Additional critical parameters such as the reconstruction of the rotation centre , as well as the femoral and acetabular offset , can also be optimally adjusted . Last but not least , an intra-operative evaluation and equalisation of the leg length is possible . Nonetheless , the disadvantages of this surgical technique in terms of the high costs in the acquisition and preservation of the necessary devices , as well as the longer operation time , must be taken into account . However , economic aspects are not the only thing preventing widespread use of the navigation technique . Determining the plane of reference ( APP ) for the optimal orientation of the implants is based on palpation of the bony l and marks – and this is influenced by the thickness of the soft tissue layer . Furthermore , the experience of the surgeon constitutes a variable that influences the accuracy of navigation . In summary , hip navigation certainly offers an interesting technique for the optimisation of  total hip arthroplasty with reconstruction of proper biomechanics . At the same time , there is currently a lack of high- quality r and omised controlled long-term trials that evaluate the clinical advantage for the patients , together with cost utility and survival rates . Cite this article : Renner L , Janz V , Perka C , Wassilew GI . What do we get from navigation in primary THA ? EFORT Open Rev 2016;1:205 - 210 . 10.1302/2058 - 5241.1.000034 
    Output:
    
agent
Results Significant differences were found in the femoral offset and overall complication rate between the conventional and navigation groups .
Additionally , the conventional group had significantly less anteversion than the navigation group .
However , the navigation group had significantly better inclination .
The operation time was significantly shorter in the conventional than navigation group .
Conclusion Both the OrthoPilot navigation system and conventional total hip arthroplasty result in significant improvements in patient function with similar overall complication rates and have their own advantages in achieving good cup position .
The conventional procedure has a shorter operation time than does use of a navigation system
***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: We have compared the biomechanical nature of the reconstruction of the hip in conventional total hip arthroplasty ( THA ) and surface replacement arthroplasty ( SRA ) in a r and omised study involving 120 patients undergoing unilateral primary hip replacement . The contralateral hip was used as a control . Post-operatively , the femoral offset was significantly increased with THA ( mean 5.1 mm ; -2.8 to 11.6 ) and decreased with SRA ( mean -3.3 mm ; -8.9 to 8.2 ) . Femoral offset was restored within sd 4 mm in 14 ( 25 % ) of those with THA and in 28 ( 57 % ) of the patients receiving SRA ( p < 0.001 ) . In the THA group , the leg was lengthened by a mean of 2.6 mm ( -6.04 to + 12.9 ) , whereas it was shortened by a mean of 1.9 mm ( -7.1 to + 2.05 ) in the SRA group , compared with the contralateral side . Leg-length ine quality was restored within sd 4 mm in 42 ( 86 % ) of the SRA and 33 ( 60 % ) of the THA patients . The radiological parameters of acetabular reconstruction were similar in both groups . Restoration of the normal proximal femoral anatomy was more precise with SRA . The enhanced stability afforded by the use of a large-diameter femoral head avoided over-lengthening of the limb or increased offset to improve soft-tissue tension as occurs sometimes in THA . In a subgroup of patients with significant pre-operative deformity , restoration of the normal hip anatomy with lower pre-operative femoral offset or significant shortening of the leg was still possible with SRA The purpose of this study was to compare conventional and navigated technique and a recently developed straight hip stem for uncemented primary total hip arthroplasty . The results of two consecutive implantation series of 42 patients ( nonnavigated ) and 42 patients ( navigated )  were analysed for implant positioning and complications . All surgeries were performed by the investigator . Radiographic analysis of cup position showed a significant improvement with reduced radiologic inclination ( 53 degrees nonnavigated /44 degrees navigated ; P < .001 ) and higher anteversion ( 7 degrees nonnavigated /12 degrees navigated ; P < .001 ) . The mean postoperative limb length difference was 6.2 mm ( SD , 9.0 for nonnavigated ) and 4.4 mm ( SD , 6.4 for navigated ) . Intraoperative and early postoperative complications were not different . No dislocation occurred in either group . There was one intraoperative trochanter fracture that was not revised ( nonnavigated ) and one revision because of a periprosthetic fracture caused by fall down during rehabilitation ( navigated ) . We conclude that acetabular implant positioning can be significantly improved by the use of navigated surgery technique . The data for postoperative limb length difference were still similar but within the expected range in both groups . The effect of improved cup positioning on mid and longterm results for both groups has to be investigated further We prospect ively evaluated acetabular cup placement in total hip arthroplasty with an imageless computer navigation system  or using conventional manual technique . The achieved cup orientation in the manual group had substantially larger variances and greater placement error than the navigation cases . The use of navigation was ab and oned in 3 cases because of excessive pelvic tilt and unreliable registration of the pelvis . Computer navigation system helped improve the accuracy of the acetabular cup placement for total hip arthroplasty in this study . The variation between the intraoperative navigation readings and the computed tomographic values suggests that relying on palpation of bony l and marks through drapes and tissue is a limitation of this method . Further , the variation in pelvic tilt has an effect on cup placement that requires further studies We report the kinematic and early clinical results of a patient- and observer-blinded r and omised controlled trial in which CT scans were used to compare potential impingement-free range of movement ( ROM ) and acetabular component cover between patients treated with either the navigated ' femur-first ' total hip arthroplasty ( THA ) method ( n = 66 ; male/female 29/37 , mean age 62.5 years ; 50 to 74 ) or conventional THA ( n = 69 ; male/female 35/34 , mean age 62.9 years ; 50 to 75 ) . The Hip Osteoarthritis Outcome Score , the Harris hip score , the Euro-Qol-5D and the Mancuso THA patient expectations score were assessed at six weeks , six months and one year after surgery . A total of 48 of the patients ( 84 % ) in the navigated ' femur-first ' group and 43 ( 65 % ) in the conventional group reached all the desirable potential ROM boundaries without prosthetic impingement for activities of daily living ( ADL ) in flexion , extension , abduction , adduction and rotation ( p = 0.016 ) . Acetabular component cover and surface contact with the host bone were > 87 % in both groups . There was a significant difference between the navigated and the conventional groups ' Harris hip scores six weeks after surgery ( p = 0.010 ) . There were no significant differences with respect to any clinical outcome at six months and one year of follow-up . The navigated ' femur-first ' technique improves the potential ROM for ADL without prosthetic impingement , although there was no observed clinical difference between the two treatment groups Background This study compared the efficacy and safety of 3 different anesthesia techniques used in  total hip arthroplasty ( THA ) . Material / Methods We allocated 198 patients preparing to undertake THA into 3 groups : general anesthesia group ( GA group , n=66 ) , caudal epidural anesthesia group ( CEA group , n=66 ) , and spinal-epidural anesthesia group ( SEA group  , n=66 ) . We compared postoperative adverse effects occurring in patients of the 3 anesthesia groups . The Visual Analog Scale ( VAS ) score , Minimum Mental State Examination ( MMSE ) score , and β-amyloid ( Aβ ) expression were calculated to determine the effects of different anesthesia on the postoperative pain and cognitive dysfunction of patients . Results The CEA and SEA groups had lower rates of perioperative adverse effects than in the GA group . Patients in the GA group required significantly higher administration of analgesics after the surgery than those in CEA and SEA groups . Higher Aβ expression levels and VAS scores , as well as lower MMSE scores , were also seen in the GA group compared with the other 2 groups . Conclusions CEA and SEA were more effective than GA in THA , and CEA seemed to be a better anesthesia technique than SEA Background Restoration of biomechanics is a major goal in THA .  Imageless navigation enables intraoperative control of leg length equalization and offset reconstruction . However , the effect of navigation compared with intraoperative fluoroscopy is unclear . Questions / purpose sWe asked whether intraoperative use of imageless navigation ( 1 ) improves the relative accuracy of leg length and global and femoral offset restoration ; ( 2 ) increases the absolute precision of leg length and global and femoral offset equalization ; and ( 3 ) reduces outliers in a reconstruction zone of ± 5 mm for leg length and global and femoral offset restoration compared with intraoperative fluoroscopy during minimally invasive ( MIS ) THA with the patient in a lateral decubitus position . Methods In this prospect i ve study a consecutive series of 125 patients were r and omized to either navigation-guided or fluoroscopy-controlled THA  using sealed , opaque envelopes . All patients received the same cementless prosthetic components through an anterolateral MIS approach while they were in a lateral decubitus position . Leg length , global or total offset ( representing the combination of femoral and acetabular offset ) , and femoral offset differences were restored using either navigation or fluoroscopy . Postoperatively , residual leg length and global and femoral offset discrepancies were analyzed on magnification-corrected radiographs of the pelvis by an independent and blinded examiner using digital planning software . Accuracy was defined as the relative postoperative difference between the surgically treated and the unaffected contralateral side for leg length and offset , respectively ; precision was defined as the absolute postoperative deviation of leg length and global and femoral offset regardless of lengthening or shortening of leg length and offset throughout the THA . All analyses were performed per intention-to-treat . Results Analyzing the relative accuracy of leg length restoration we found a mean difference of 0.2 mm ( 95 % CI , −1.0 to + 1.4 mm ; p = 0.729 ) between fluoroscopy and navigation , 0.2 mm ( 95 % CI , −0.9 to + 1.3 mm ; p = 0.740 ) for global offset and 1.7 mm ( 95 % CI , + 0.4 to + 2.9 mm ; p = 0.008 ) for femoral offset . For the absolute precision of leg length and global and femoral offset equalization , there was a mean difference of 1.7 ± 0.3 mm ( p < 0.001 ) between fluoroscopy and navigation . The biomechanical reconstruction with a residual leg length and global and femoral offset discrepancy less than 5 mm and less than 8 mm , respectively , succeeded in 93 % and 98 % , respectively , in the navigation group and in 54 % and 95 % , respectively , in the fluoroscopy group . Conclusions Intraoperative fluoroscopy and imageless navigation seem equivalent in accuracy and precision to reconstruct leg length and global and femoral offset during MIS THA with the patient in the lateral decubitus position . Level of Evidence Level I , therapeutic study . See the Instructions for Authors for a complete description of levels of evidence We present a match-paired study between computer-assisted and freeh and techniques using a short modular femoral stem ( Metha ; B. Braun Aesculap , Tuttlingen , Germany ) in  total hip replacement ( THR ) .  Surgical time , clinical outcome , dislocation rate , limb length , and offset in 44 patients with ideal indication for this more conservative implant were assessed . Despite both longer surgical time and similar early outcomes , the results showed how computer-assisted techniques allow easier management of limb length discrepancy and offset restoring . We believe that navigated short modular stems are safe for less invasive THR Navigation in primary total hip arthroplasty has a history of over 20 years . During this process , imageless computer navigation can be particularly helpful in optimally restoring the hip ’s biomechanics . This involves the accurate placement of the acetabular component with the determination of the anteversion and abduction , whereby the navigated femur-first technique also allows for a calculation of the combined anteversion . Additional critical parameters such as the reconstruction of the rotation centre , as well as the femoral and acetabular offset , can also be optimally adjusted . Last but not least , an intra-operative evaluation and equalisation of the leg length is possible . Nonetheless , the disadvantages of this surgical technique in terms of the high costs in the acquisition and preservation of the necessary devices , as well as the longer operation time , must be taken into account . However , economic aspects are not the only thing preventing widespread use of the navigation technique . Determining the plane of reference ( APP ) for the optimal orientation of the implants is based on palpation of the bony l and marks – and this is influenced by the thickness of the soft tissue layer . Furthermore , the experience of the surgeon constitutes a variable that influences the accuracy of navigation . In summary , hip navigation certainly offers an interesting technique for the optimisation of  total hip arthroplasty with reconstruction of proper biomechanics . At the same time , there is currently a lack of high- quality r and omised controlled long-term trials that evaluate the clinical advantage for the patients , together with cost utility and survival rates . Cite this article : Renner L , Janz V , Perka C , Wassilew GI . What do we get from navigation in primary THA ? EFORT Open Rev 2016;1:205 - 210 . 10.1302/2058 - 5241.1.000034 
    Output:
    