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: Background Late infection is the second most frequent early complication after total hip arthroplasty ( THA ) and the most frequent after hemiarthroplasty . Known risk factors for infection after THA include posttraumatic osteoarthritis , previous surgery , chronic liver disease , corticoid therapy , and excessive surgical time . However , risk factors for hemiarthroplasty are not clearly established . Questions / purpose sWe therefore determined the preoperative and intraoperative risk factors for late infection ( more than 3 months after surgery ) in patients with hemiarthroplasties and THAs . Methods We retrospectively compared 47 patients with a hip arthroplasty ( 23 hemiarthroplasties , 24 total hip arthroplasties ) and late infection with 200 r and omly-selected patients with primary arthroplasty ( 100 hemiarthroplasties , 100 total hip arthroplasties ) during the same time period of time without any infection during followup . Potential risk factors were identified from medical records . Minimum followup was 12 months ( mean , 27 months ; range , 12–112 months ) for the study group and 18 months ( mean , 84 months ; range , 18–144 months ) for the control group . Results The following factors were more frequent in late infected hemiarthroplasties : female gender ; previous surgery ; obesity ( body mass index greater than 30 kg/m2 ) ; glucocorticoid and immunosuppressant treatments ; prolonged surgical time ; inadequate antibiotic prophylaxis ; prolonged wound drainage ; hematoma ; dislocation ; and cutaneous , urinary , and /or abdominal infections . The following were more frequent in infected total hip arthroplasties : posttraumatic osteoarthritis ; previous surgery ; glucocorticoids ; chronic liver disease ; alcohol and intravenous drug abuse ; prolonged surgical time ; prolonged wound drainage ; dislocation ; subsequent surgery ; and cutaneous , urinary , respiratory and abdominal infections . Diabetes did not appear to be a risk factor . Conclusions Our data suggest there are specific risk factors for infection in hemiarthroplasties . The major risk factors for late infection in hip arthroplasty must be recognized so they can be minimized or controlled if not possible to employ prophylactic measures .Level of Evidence Level III , prognostic study . See Guidelines for Authors for a complete description of levels of evidence Background The benefits of robotic techniques for implanting femoral components during THA are still controversial . Questions / Purpose sThe purpose of this study was to prospect ively compare the results and complications of robotic-assisted and h and -rasping stem implantation techniques . Method The minimum followup was 5 years ( mean , 67 months ; range , 60–85 months ) . One hundred forty-six primary THAs on 130 patients were included in this study .  Robot-assisted primary THA was performed on 75 hips and a h and -rasping technique was used on 71 hips . Results At 2 and 3 years postoperatively , the Japanese Orthopaedic Association ( JOA ) clinical score was slightly better in the robotic-assisted group . At 5 years followup , however , the differences were not significant . Postoperative limb lengths of the robotic-milling group had significantly less variance than the h and -rasping group . At 2 years postoperatively , there was significantly more stress shielding of the proximal femur in the h and -rasping group ; this difference was more significant 5 years postoperatively . Conclusions Substantially more precise implant positioning seems to have led to less variance in limb-length ine quality and less stress shielding of the proximal femur 5 years postoperatively . Level of Evidence Level II , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence The ROBODOC ® system was design ed to address potential human errors in performing cementless total hip replacement . The system consists of a preoperative planning computer workstation ( called ORTHODOC ) and a five-axis robotic arm with a high speed milling device as an end effector . The combined experience of the United States Food and Drug Administration multicenter trial and the German postmarket use of the system are reported . The United States study is controlled and r and omized with 136 hip replacements performed at three centers ( 65 ROBODOC ® and 62 control ) . Followup was 1 year on 127 hip replacements and 2 years on 93 hip replacements . No differences were found in the Harris hip scores or the Short Form Health Survey outcomes question naire . Length of stay also was not different , but the surgical time and blood loss were greater in the ROBODOC ® group . This was attributed to a learning curve at each center . Radiographs were evaluated by an independent bone radiologist and showed statistically better fit and positioning of the femoral component in the ROBODOC ® group . Complications were not different , except for three cases of intraoperative femoral fracture in the control group and none in the ROBODOC ® group . The German study reports on 858 patients , 42 with bilateral hip replacements and this includes 30 revision cases for a total of 900 hip replacements .  The Harris hip score rose from 43.7 to 91.5 . In these cases the surgical time declined quickly from 240 minutes for the first case to 90 minutes . No intraoperative femoral fractures occurred in 900 cases . Other complications were comparable with total hip replacements performed using conventional techniques . The ROBODOC ® system is thought to be safe and effective in producing radiographically superior implant fit and positioning while eliminating femoral fractures AIM Robotic assisted total hip arthroplasty  remains controversial , since wider exposure of the proximal femur and placement of the leg in maximal hip adduction and external rotation using a rigid leg-holder apparatus may impair significantly the hip abductors . Consequently , it is the purpose of this study to analyse and report both clinical outcome and hip abductor function following robotic assisted versus conventional total hip arthroplasty . MATERIAL AND METHODS 36 robotic-assisted ( CASPAR , Orto-Maquet , Rastatt , Germany ) and 35 conventional cementless total hip arthroplasties  were followed on average for 18 months regarding incidence of complications , Harris hip score , the scoring system according to Merle d'Aubigné and Postel , hip abductor function ( using a spring-balance ) , and incidence of Trendelenburg 's sign ( according to the Kuhfuss-classification ) . Statistical analysis was performed in case of continuous data using the t test and the Mann-Whitney test , respectively , and in case of categorical data using Fisher 's exact test and the chi-squared test , respectively . The level of significance was set as p < 0.05 . RESULTS Average duration of surgery ( CASPAR : 100.6 min ; conventional : 51.5 min ; p < 0.0001 ) as well as average loss of haemoglobin ( CASPAR : 4.5 mg/dL ; conventional : 3.3 mg/dL ; p = 0.0002 ) differed significantly , whereas the incidence of complications ( CASPAR : two dislocations , one sciatic paresis , one deep infection ; conventional : one dislocation , two fissures ) , revision rate ( CASPAR : 5.6 % ; conventional : 2.9 % ) , and incidence of heterotopic ossifications ( CASPAR : 30.6 % ; conventional : 17.1 % ) was comparable following both procedures ( p > 0.05 ) . Improvement of the Harris hip score also was comparable in both groups ( CASPAR : 40.9 to 86.1 points ; conventional : 39.5 to 88.0 points ; p = 0.21 ) , whereas improvement of the score according to Merle d'Aubigné and Postel was significantly greater following the manual procedure ( CASPAR : 10.1 to 16.0 points ; conventional : 8.3 to 16.6 points ; p < 0.0001 ) . Differences between the two groups were also significant regarding hip abductor function ( CASPAR : 76.1 % ; conventional : 93.8 % of the contralateral hip ; p < 0.0001 ) and incidence of Trendelenburg 's sign ( CASPAR : 61.1 % ; conventional : 25.7 % ; p = 0.0014 ) . CONCLUSION The significant functional impairment following robotic assisted THA should be taken critically into consideration prior to initiating such procedure The ROBODOC system has provided better fit and fill of the stem and less destruction of the bony architecture than with manual surgery . These benefits might affect femoral periprosthetic bone remodeling . We evaluated the effects of robotic milling in cementless total hip arthroplasty ( THA ) in a longitudinal 24-month follow-up study using dual energy X-ray absorptiometry ( DEXA ) and plain radiographs of 29 patients ( 31 hips ) after ROBODOC THA and 24 patients ( 27 hips ) after manual THA with the same stem design . To minimize the influence of other factors on bone remodeling , only female osteoarthritis patients , who had no drugs that might affect bone metabolism were enrolled . Significantly less bone loss occurred at the proximal periprosthetic areas in the ROBODOC group . In zone 1 , the decrease was 15.5 versus 29.9 % using conventional rasping ; in zone 7 , the loss was 17.0 % with ROBODOC compared to 30.5 % with conventional rasping ( p < 0.05 ) . On radiographs , endosteal spot welds in the proximal medial portion were more pronounced in the ROBODOC group ( 48 vs. 11 % in the conventional group , p < 0.05 ) . Our results suggest that robotic milling is effective in facilitating proximal load transfer around the femoral component and minimizing bone loss after cementless THA We performed a prospect i ve , r and omised controlled trial of unicompartmental knee arthroplasty comparing the performance of the Acrobot system with conventional surgery . A total of 27 patients ( 28 knees ) awaiting unicompartmental knee arthroplasty were r and omly allocated to have the operation performed conventionally or with the assistance of the Acrobot . The primary outcome measurement was the angle of tibiofemoral alignment in the coronal plane , measured by CT . Other secondary parameters were evaluated and are reported . All of the Acrobot group had tibiofemoral alignment in the coronal plane within 2 degrees of the planned position , while only 40 % of the conventional group achieved this level of accuracy . While the operations took longer , no adverse effects were noted , and there was a trend towards improvement in performance with increasing accuracy based on the Western Ontario and McMaster Universities Osteoarthritis Index and American Knee Society scores at six weeks and three months . The Acrobot device allows the surgeon to reproduce a pre-operative plan more reliably than is possible using conventional techniques which may have clinical advantages Abstract Restoration of femoral offset and acetabular inclination may have an effect on polyethylene ( PE ) wear in THA . We therefore assessed the effect of femoral offset and acetabular inclination ( angle ) on acetabular conventional ( not highly cross-linked ) PE wear in uncemented THA . We prospect ively followed 43 uncemented THAs for a minimum of 49 months ( mean , 64 months ; range , 49–88 months ) .  Radiographs were assessed for femoral offset , acetabular inclination , and  conventional PE wear . The mean ( ± st and ard deviation ) linear wear rate in all THAs was 0.14 mm/year ( ± 0.01 mm/year ) and the mean volumetric wear rate was 53.1 mm3/year ( ± 5.5 mm3/year ) . In THAs with an acetabular angle less than 45 ° , the mean wear was 0.12 mm/year ( ± 0.01 mm/year ) compared with 0.18 mm/year ( ± 0.02 mm/year ) in those with a reconstructed acetabular angle greater than 45 ° . Reproduction of a reconstructed femoral offset to within 5 mm of the native femoral offset was associated with a reduction in conventional PE wear ( 0.12 mm/year versus 0.16 mm/year ) . Careful placement of the acetabular component to ensure an acetabular angle less than 45 ° in the reconstructed hip allows for reduced conventional PE wear . Level of Evidence : Level II , prospect i ve study . See Guidelines for Authors for a complete description of levels of evidence Background Improper acetabular component orientation in THA has been associated with increased dislocation rates , component impingement , bearing surface wear , and a greater likelihood of revision . Therefore , any reasonable steps to improve acetabular component orientation should be considered and explored . Questions / purpose sWe therefore sought to compare THA with a robotic-assisted posterior approach with manual alignment techniques through a posterior approach , using a matched-pair controlled study design , to assess whether the use of the robot made it more likely for the acetabular cup to be positioned in the safe zones described by Lewinnek et al. and Callanan et al. Methods Between September 2008 and September 2012 , 160 THAs were performed by the senior surgeon . Sixty-two patients ( 38.8 % ) underwent THA using a conventional posterior approach , 69 ( 43.1 % ) underwent robotic-assisted THA using the posterior approach , and 29 ( 18.1 % ) underwent radiographic-guided anterior-approach THAs .  From September 2008 to June 2011 , all patients were offered anterior or posterior approaches regardless of BMI and anatomy . Since introduction of 
    Output:
    
agent
Conclusion The results of this meta- analysis suggest that robotic-assisted THA has certain advantages over conventional THA , including the results of component positioning and rates of intraoperative complications .
***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: Background Late infection is the second most frequent early complication after total hip arthroplasty ( THA ) and the most frequent after hemiarthroplasty . Known risk factors for infection after THA include posttraumatic osteoarthritis , previous surgery , chronic liver disease , corticoid therapy , and excessive surgical time . However , risk factors for hemiarthroplasty are not clearly established . Questions / purpose sWe therefore determined the preoperative and intraoperative risk factors for late infection ( more than 3 months after surgery ) in patients with hemiarthroplasties and THAs . Methods We retrospectively compared 47 patients with a hip arthroplasty ( 23 hemiarthroplasties , 24 total hip arthroplasties ) and late infection with 200 r and omly-selected patients with primary arthroplasty ( 100 hemiarthroplasties , 100 total hip arthroplasties ) during the same time period of time without any infection during followup . Potential risk factors were identified from medical records . Minimum followup was 12 months ( mean , 27 months ; range , 12–112 months ) for the study group and 18 months ( mean , 84 months ; range , 18–144 months ) for the control group . Results The following factors were more frequent in late infected hemiarthroplasties : female gender ; previous surgery ; obesity ( body mass index greater than 30 kg/m2 ) ; glucocorticoid and immunosuppressant treatments ; prolonged surgical time ; inadequate antibiotic prophylaxis ; prolonged wound drainage ; hematoma ; dislocation ; and cutaneous , urinary , and /or abdominal infections . The following were more frequent in infected total hip arthroplasties : posttraumatic osteoarthritis ; previous surgery ; glucocorticoids ; chronic liver disease ; alcohol and intravenous drug abuse ; prolonged surgical time ; prolonged wound drainage ; dislocation ; subsequent surgery ; and cutaneous , urinary , respiratory and abdominal infections . Diabetes did not appear to be a risk factor . Conclusions Our data suggest there are specific risk factors for infection in hemiarthroplasties . The major risk factors for late infection in hip arthroplasty must be recognized so they can be minimized or controlled if not possible to employ prophylactic measures .Level of Evidence Level III , prognostic study . See Guidelines for Authors for a complete description of levels of evidence Background The benefits of robotic techniques for implanting femoral components during THA are still controversial . Questions / Purpose sThe purpose of this study was to prospect ively compare the results and complications of robotic-assisted and h and -rasping stem implantation techniques . Method The minimum followup was 5 years ( mean , 67 months ; range , 60–85 months ) . One hundred forty-six primary THAs on 130 patients were included in this study .  Robot-assisted primary THA was performed on 75 hips and a h and -rasping technique was used on 71 hips . Results At 2 and 3 years postoperatively , the Japanese Orthopaedic Association ( JOA ) clinical score was slightly better in the robotic-assisted group . At 5 years followup , however , the differences were not significant . Postoperative limb lengths of the robotic-milling group had significantly less variance than the h and -rasping group . At 2 years postoperatively , there was significantly more stress shielding of the proximal femur in the h and -rasping group ; this difference was more significant 5 years postoperatively . Conclusions Substantially more precise implant positioning seems to have led to less variance in limb-length ine quality and less stress shielding of the proximal femur 5 years postoperatively . Level of Evidence Level II , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence The ROBODOC ® system was design ed to address potential human errors in performing cementless total hip replacement . The system consists of a preoperative planning computer workstation ( called ORTHODOC ) and a five-axis robotic arm with a high speed milling device as an end effector . The combined experience of the United States Food and Drug Administration multicenter trial and the German postmarket use of the system are reported . The United States study is controlled and r and omized with 136 hip replacements performed at three centers ( 65 ROBODOC ® and 62 control ) . Followup was 1 year on 127 hip replacements and 2 years on 93 hip replacements . No differences were found in the Harris hip scores or the Short Form Health Survey outcomes question naire . Length of stay also was not different , but the surgical time and blood loss were greater in the ROBODOC ® group . This was attributed to a learning curve at each center . Radiographs were evaluated by an independent bone radiologist and showed statistically better fit and positioning of the femoral component in the ROBODOC ® group . Complications were not different , except for three cases of intraoperative femoral fracture in the control group and none in the ROBODOC ® group . The German study reports on 858 patients , 42 with bilateral hip replacements and this includes 30 revision cases for a total of 900 hip replacements .  The Harris hip score rose from 43.7 to 91.5 . In these cases the surgical time declined quickly from 240 minutes for the first case to 90 minutes . No intraoperative femoral fractures occurred in 900 cases . Other complications were comparable with total hip replacements performed using conventional techniques . The ROBODOC ® system is thought to be safe and effective in producing radiographically superior implant fit and positioning while eliminating femoral fractures AIM Robotic assisted total hip arthroplasty  remains controversial , since wider exposure of the proximal femur and placement of the leg in maximal hip adduction and external rotation using a rigid leg-holder apparatus may impair significantly the hip abductors . Consequently , it is the purpose of this study to analyse and report both clinical outcome and hip abductor function following robotic assisted versus conventional total hip arthroplasty . MATERIAL AND METHODS 36 robotic-assisted ( CASPAR , Orto-Maquet , Rastatt , Germany ) and 35 conventional cementless total hip arthroplasties  were followed on average for 18 months regarding incidence of complications , Harris hip score , the scoring system according to Merle d'Aubigné and Postel , hip abductor function ( using a spring-balance ) , and incidence of Trendelenburg 's sign ( according to the Kuhfuss-classification ) . Statistical analysis was performed in case of continuous data using the t test and the Mann-Whitney test , respectively , and in case of categorical data using Fisher 's exact test and the chi-squared test , respectively . The level of significance was set as p < 0.05 . RESULTS Average duration of surgery ( CASPAR : 100.6 min ; conventional : 51.5 min ; p < 0.0001 ) as well as average loss of haemoglobin ( CASPAR : 4.5 mg/dL ; conventional : 3.3 mg/dL ; p = 0.0002 ) differed significantly , whereas the incidence of complications ( CASPAR : two dislocations , one sciatic paresis , one deep infection ; conventional : one dislocation , two fissures ) , revision rate ( CASPAR : 5.6 % ; conventional : 2.9 % ) , and incidence of heterotopic ossifications ( CASPAR : 30.6 % ; conventional : 17.1 % ) was comparable following both procedures ( p > 0.05 ) . Improvement of the Harris hip score also was comparable in both groups ( CASPAR : 40.9 to 86.1 points ; conventional : 39.5 to 88.0 points ; p = 0.21 ) , whereas improvement of the score according to Merle d'Aubigné and Postel was significantly greater following the manual procedure ( CASPAR : 10.1 to 16.0 points ; conventional : 8.3 to 16.6 points ; p < 0.0001 ) . Differences between the two groups were also significant regarding hip abductor function ( CASPAR : 76.1 % ; conventional : 93.8 % of the contralateral hip ; p < 0.0001 ) and incidence of Trendelenburg 's sign ( CASPAR : 61.1 % ; conventional : 25.7 % ; p = 0.0014 ) . CONCLUSION The significant functional impairment following robotic assisted THA should be taken critically into consideration prior to initiating such procedure The ROBODOC system has provided better fit and fill of the stem and less destruction of the bony architecture than with manual surgery . These benefits might affect femoral periprosthetic bone remodeling . We evaluated the effects of robotic milling in cementless total hip arthroplasty ( THA ) in a longitudinal 24-month follow-up study using dual energy X-ray absorptiometry ( DEXA ) and plain radiographs of 29 patients ( 31 hips ) after ROBODOC THA and 24 patients ( 27 hips ) after manual THA with the same stem design . To minimize the influence of other factors on bone remodeling , only female osteoarthritis patients , who had no drugs that might affect bone metabolism were enrolled . Significantly less bone loss occurred at the proximal periprosthetic areas in the ROBODOC group . In zone 1 , the decrease was 15.5 versus 29.9 % using conventional rasping ; in zone 7 , the loss was 17.0 % with ROBODOC compared to 30.5 % with conventional rasping ( p < 0.05 ) . On radiographs , endosteal spot welds in the proximal medial portion were more pronounced in the ROBODOC group ( 48 vs. 11 % in the conventional group , p < 0.05 ) . Our results suggest that robotic milling is effective in facilitating proximal load transfer around the femoral component and minimizing bone loss after cementless THA We performed a prospect i ve , r and omised controlled trial of unicompartmental knee arthroplasty comparing the performance of the Acrobot system with conventional surgery . A total of 27 patients ( 28 knees ) awaiting unicompartmental knee arthroplasty were r and omly allocated to have the operation performed conventionally or with the assistance of the Acrobot . The primary outcome measurement was the angle of tibiofemoral alignment in the coronal plane , measured by CT . Other secondary parameters were evaluated and are reported . All of the Acrobot group had tibiofemoral alignment in the coronal plane within 2 degrees of the planned position , while only 40 % of the conventional group achieved this level of accuracy . While the operations took longer , no adverse effects were noted , and there was a trend towards improvement in performance with increasing accuracy based on the Western Ontario and McMaster Universities Osteoarthritis Index and American Knee Society scores at six weeks and three months . The Acrobot device allows the surgeon to reproduce a pre-operative plan more reliably than is possible using conventional techniques which may have clinical advantages Abstract Restoration of femoral offset and acetabular inclination may have an effect on polyethylene ( PE ) wear in THA . We therefore assessed the effect of femoral offset and acetabular inclination ( angle ) on acetabular conventional ( not highly cross-linked ) PE wear in uncemented THA . We prospect ively followed 43 uncemented THAs for a minimum of 49 months ( mean , 64 months ; range , 49–88 months ) .  Radiographs were assessed for femoral offset , acetabular inclination , and  conventional PE wear . The mean ( ± st and ard deviation ) linear wear rate in all THAs was 0.14 mm/year ( ± 0.01 mm/year ) and the mean volumetric wear rate was 53.1 mm3/year ( ± 5.5 mm3/year ) . In THAs with an acetabular angle less than 45 ° , the mean wear was 0.12 mm/year ( ± 0.01 mm/year ) compared with 0.18 mm/year ( ± 0.02 mm/year ) in those with a reconstructed acetabular angle greater than 45 ° . Reproduction of a reconstructed femoral offset to within 5 mm of the native femoral offset was associated with a reduction in conventional PE wear ( 0.12 mm/year versus 0.16 mm/year ) . Careful placement of the acetabular component to ensure an acetabular angle less than 45 ° in the reconstructed hip allows for reduced conventional PE wear . Level of Evidence : Level II , prospect i ve study . See Guidelines for Authors for a complete description of levels of evidence Background Improper acetabular component orientation in THA has been associated with increased dislocation rates , component impingement , bearing surface wear , and a greater likelihood of revision . Therefore , any reasonable steps to improve acetabular component orientation should be considered and explored . Questions / purpose sWe therefore sought to compare THA with a robotic-assisted posterior approach with manual alignment techniques through a posterior approach , using a matched-pair controlled study design , to assess whether the use of the robot made it more likely for the acetabular cup to be positioned in the safe zones described by Lewinnek et al. and Callanan et al. Methods Between September 2008 and September 2012 , 160 THAs were performed by the senior surgeon . Sixty-two patients ( 38.8 % ) underwent THA using a conventional posterior approach , 69 ( 43.1 % ) underwent robotic-assisted THA using the posterior approach , and 29 ( 18.1 % ) underwent radiographic-guided anterior-approach THAs .  From September 2008 to June 2011 , all patients were offered anterior or posterior approaches regardless of BMI and anatomy . Since introduction of 
    Output:
    