Small Improvements in Postoperative Outcome with Gap Balancing Technique Compared with Measured Resection in Total Knee Arthroplasty Measured Resection versus Gap Balancing Technique for Femoral Rotational Alignment: A Prospective Study Comparison of joint line position changes after primary bilateral total knee arthroplasty performed using the navigation-assisted measured gap resection or gap balancing techniques Is adapted measured resection superior to gap-balancing in determining femoral component rotation in total knee replacement? Intraoperative Comparison of Measured Resection and Gap Balancing Using a Force Sensor: A Prospective, Randomized Controlled Trial. Computer-assisted gap balancing technique improves outcome in total knee arthroplasty, compared with conventional measured resection technique Contact Kinematic Differences Between Gap Balanced vs Measured Resection Techniques for Single Radius Posterior-Stabilized Total Knee Arthroplasty. Kinematic femoral alignment with gap balancing and patient-specific instrumentation in total knee arthroplasty: a randomized clinical trial Comparison between two computer-assisted total knee arthroplasty: gap-balancing versus measured resection technique Gap balancing sacrifices joint-line maintenance to improve gap symmetry: a randomized controlled trial comparing gap balancing and measured resection. The reversed gap technique produces anatomical alignment with less midflexion instability in total knee arthroplasty: a prospective randomized trial Gap balancing versus measured resection technique using a mobile-bearing prosthesis in computer-assisted surgery Effects of the Balanced Gap Technique on Femoral Component Rotation in TKA Functional Outcome after Computer-Assisted Total Knee Arthroplasty Using Measured Resection versus Gap Balancing Techniques: A Randomised Controlled Study Accuracy of manual instrumentation of tibial cutting guide in total knee arthroplasty Rotational alignment of femoral component with different methods in total knee arthroplasty: a randomized, controlled trial Navigated total knee arthroplasty: a radiological analysis of 42 randomised cases.
Background : There is ongoing debate about how to obtain correct rotational alignment in total knee arthroplasty ( TKA ) . Two commonly used techniques are the measured resection ( MR ) and the gap balancing ( GB ) technique . Objective : The objective of the present study was to analyze which of these two techniques confers a clinical advantage up to 10 years postoperatively . Methods : Two hundred patients were r and omized to either MR or GB .  The primary outcome was the Knee Society Knee Score ( KS ) 10 years postoperatively . Secondary outcomes were passive range of motion , the Knee Society Function Score ( FS ) , and the Western Ontario and McMasters Universities Osteoarthritis Index ( WOMAC ) , along with implant survival . We employed a two one-sided test ( TOST ) and linear mixed models to assess clinical outcomes . Results : Mean KS was 82 ( 95 % confidence interval ( CI ) , 80 – 83 ) and 77 ( 95 % CI , 76 – 79 ) in the GB and MR group , respectively . The TOST test and linear mixed model both revealed statistical significance ( p < 0.001 ) . In addition , GB yielded better postoperative FS and WOMAC . However , between-group differences were consistently small . Implant survival rates at 10 years , with survival for any reason as the endpoint of interest , were 93.7 % ( 95 % CI , 86.4 % and 97.1 % ) and 89.8 % ( 95 % CI , 81.9 % - 94.4 % ) for the GB group and the MR group , respectively ( p = 0.302 ) . Conclusion : Gap-balancing is a safe and reliable technique . KS for the two study groups at 10 years can be considered equivalent , and the small postoperative advantages may not extend beyond clinical relevance Purpose . To compare the measured resection technique and the gap balancing technique for correction of the femoral rotational alignment . Methods . 57 women and 6 men ( mean age , 70 years ) with end-stage osteoarthritis and ±15 ° malalignment and ±10 ° flexion contracture of the knee underwent primary total knee arthroplasty through the medial approach using the measured resection technique ( n=34 ) or the gap balancing technique ( n=29 ) . Femoral rotational alignment was evaluated before and 7 days after surgery using computed tomography by referencing the 2 posterior condyles to the transepicondylar axis . Results . The 2 groups did not differ significantly in terms of correction of the femoral rotational alignment ( 3.4 ° ±1.4 ° vs. 3.5 ° ±3.1 ° , p=0.817 ) . Conclusion . The measured resection and the gap balancing techniques  achieved comparable correction of femoral rotational alignment Purpose This study aim ed to compare the clinical and radiological results of navigation-assisted TKAs performed using the measured gap resection or the gap balancing technique in thirty patients who underwent bilateral primary TKAs . Methods Sixty cases of navigation-assisted TKAs [ 30 TKAs performed using the measured gap resection technique  ( Group A ) and 30 TKAs performed using the gap balancing technique ( Group B ) ] were analyzed prospect ively with minimum follow-up of 2 years . The joint line positions were measured using preoperative and postoperative weight-bearing anteroposterior and lateral radiographs . Clinical results were evaluated using knee scores and functional scores . Results No significant differences in knee scores or functional scores were observed . Polyethylene thickness and flexion/extension gaps were significantly larger in Group B ( P < 0.05 ) . The meaningful proximal shift of the joint line was shown in Group B ( P < 0.05 ) . Conclusion The navigation-assisted TKA with measured gap resection technique could be a useful technique with regard to restoration of the joint line . Level of evidence II Obtaining a balanced flexion gap with correct femoral component rotation is one of the prerequisites for a successful outcome after total knee replacement ( TKR ) . Different techniques for achieving this have been described . In this study we prospect ively compared gap-balancing versus measured resection in terms of reliability and accuracy for femoral component rotation in 96 primary TKRs performed in 96 patients using the Journey system . In 48 patients ( 18 men and 30 women ) with a mean age of 65 years ( 45 to 85 ) a tensor device was used to determine rotation . In the second group of 48 patients ( 14 men and 34 women ) with a mean age of 64 years ( 41 to 86 ) , an ' adapted ' measured resection technique was used , taking into account the native rotational geometry of the femur as measured on a pre-operative CT scan . Both groups systematic ally reproduced a similar external rotation of the femoral component relative to the surgical transepicondylar axis : 2.4 ° ( SD 2.5 ) in the gap-balancing group and 1.7 ° ( SD 2.1 ) in the measured resection group ( p = 0.134 ) . Both gap-balancing and adapted measured resection techniques proved equally reliable and accurate in determining femoral component rotation after TKR . There was a tendency towards more external rotation in the gap-balancing group , but this difference was not statistically significant ( p = 0.134 ) . The number of outliers for our ' adapted ' measured resection technique was much lower than reported in the literature BACKGROUND For establishing femoral component position , gap-balancing ( GB ) and measured resection ( MR ) techniques were compared using a force sensor . METHODS Ninety-one patients were r and omized to undergo primary total knee arthroplasty using either MR ( n = 43 ) or GB ( n = 48 ) technique using a single total knee arthroplasty design .  GB was performed with an instrumented tensioner . Force sensor data were obtained before the final implantation . RESULTS GB result ed in greater range of femoral component rotation vs MR ( 1.5 ° ± 2.9 ° vs 3.1 ° ± 0.5 ° , P < .05 ) and posterior condylar cut thickness medially ( 10.2 ± 2.0 mm vs 9.0 ± 1.3 mm ) and laterally ( 8.5 ± 1.9 mm vs 6.4 ± 1.0 mm ) . Force sensor data showed a decreased intercompartmental force difference at full flexion in GB ( .8 ± 2.3 vs 2.0 ± 3.3u , 1u ≈ 15 N , P < .05 ) . CONCLUSION GB result ed in a greater range of femoral component rotation and thicker posterior condylar cuts result ing in an increased flexion space relative to MR . Intercompartmental force difference trended toward a more uniform distribution between full extension and full flexion in the GB vs MR group Purpose The objective of this prospect i ve study was to compare the functional outcome of conventional measured resection technique and computer-assisted gap balancing technique in TKA . Methods 140 patients were r and omized into two groups . The conventional measured resection technique without computer navigation was performed in Group 1 and the computer-assisted gap balancing technique in Group 2 . Range of motion , clinical laxity assessment with KT-1000 arthrometer , postoperative radiological films and various functional knee scores were documented at 6 months and 2 years . Results At 2 years , there were significantly more patients ( five patients , 7 % ) in the Group 1 with flexion contractures of more than 5 ° ( P = 0.05 ) . There were significantly more outliers in the Group 1 ( eight patients , 11 % ) , who demonstrated anterior tibial translation > 5 mm , than Group 2 ( two patients , 3 % ) ( P = 0.041 ) . The total excursion at 20 ° was significantly higher in Group 1 at 6 months ( P = 0.012 ) and after 2 years ( P = 0.031 ) . Group 2 was able to demonstrate significantly better limb alignment with fewer outliers ( more than 3 ° varus/valgus ) than Group 1 . At 6-month follow-up , Group 2 demonstrated better outcomes in Function Score ( P = 0.040 ) and Total Oxford Score ( P = 0.031 ) . At 2-year review , Group 2 had better outcome in the Total Oxford Score ( 0.030 ) . Conclusion Computer-assisted gap balancing technique was able to achieve more precise soft tissue balance and restoration of limb alignment with better knee scores as compared to the conventional measured resection technique in total knee arthroplasty . Level of evidence BACKGROUND Measured resection ( MR ) and gap balancing ( GB ) are common surgical techniques for total knee arthroplasty ( TKA ) . Controversy has arisen as each conceptually differs in how the knee is balanced through bone and soft tissue management . The objective of the present study was to compare both the frequency of condylar liftoff and the location of femorotibial contact from extension through midflexion between patients undergoing GB or MR TKA . METHODS A total of 24 knees ( 23 patients ) were r and omly assigned at referral to either a surgeon performing MR or GB TKA  with the same single radius , posterior-stabilized implant ( 12 per cohort ) . At 1-year postoperation , patients underwent biplanar radiographic imaging at 0 ° , 20 ° , 40 ° , and 60 ° of flexion  . Condylar liftoff , contact location , and magnitude of excursion on each condyle were measured . Preoperative and postoperative clinical outcome scores were also collected . RESULTS There was no difference ( P = .41 ) in the frequency of liftoff between cohorts . The MR cohort had more posterior contact on the medial condyle ( P < .01 ) and more anterior contact on the lateral condyle ( P < .01 ) throughout flexion . Motion patterns were similar between cohorts , with similar medial ( P = .48 ) and lateral ( P = .44 ) excursion , which was equal in magnitude between condyles for both MR ( P = .48 ) and GB ( P = .73 ) . There was no difference in clinical outcome scores between groups . CONCLUSION For this particular implant system , GB and MR appear to produce similar kinematic and patient-reported outcome results While patient-specific instrumentation ( PSI ) in total knee arthroplasty ( TKA ) allows for transfer of the preoperative plan onto bony l and marks , the soft tissue balancing is not affected . The goals of this r and omized clinical trial were to compare PSI and the measured resection technique ( conventional ) with PSI and the gap balancing technique .  Fifty patients were r and omized to TKA with conventional PSI ( PSI-S ) ( n = 25 ) or to PSI with additional gap balancing ( PSI-GB ) ( n = 25 ) . All patients were clinical ly examined at 3 and 12 months postoperatively . Data on the range of motion , the Knee Society Score , the Western Ontario and McMasters Universities Osteoarthritis Index , the High-Flexion Knee Score ( HFKS ) , and the Forgotten Joint Score ( FJS ) were compiled at follow-up . Statistically significant improvements were found for all clinical parameters in the PSI-GB group compared to the PSI-S group at 3 months postoperatively and for FS , FJS , and HFKS at 12 months . However , the relevance of these differences , as well as their effect on long-term outcomes , needs to be evaluated further . In conclusion , patient-specific instrumentation combined with gap balancing yielded good early clinical outcomes Two surgical strategies are possible in total knee arthroplasty ( TKA ) : a measured resection technique , in which bone l and marks are used to guide resections equal to the distal and posterior thickness of the femoral component , or a gap-balancing approach , in which equal collateral ligament tension in flexion and extension is sought before and as a guide to final bone cuts . In this study performed with computer assisted system , we compared the 2 different methods in 126 patients followed prospect ively in order to analyze the effect of both the techniques on joint-line ( JL ) maintenance , axial limb restoration and components position . The gap technique showed a statistical increase in the post-operative value when compared with the measured resection technique , ( P = 0.008 ) . When comparing the two groups regarding to the pre-operative deformity , we have found a statistical difference ( P = 0.001 ) in case of moderate pre-operative deformity ( less than 10 ° ) , and the measured resection technique showed a slight superiority in preserving a joint line more faithful to the pre-operative . We found an ideal alignment for the mechanical axis ( 180 ° ± 3 ° ) ( 95 % of cases ) . In six cases ( 5 % ) , the mean post-operative value exceeded ( varus or valgus ) the ideal value by more than 3 ° . In the frontal plane , a good alignment was observed for both femoral and tibial components without a significant difference between the two techniques . In the sagittal plane was found more alignment variability due to the different implants used and their ideal starting slope , from 7 ° to 3 ° . Finally , the surgeon can use the approach with which he has more confidence ; however , as the measured resection technique causes less reduction in the post-operative joint-line position , in case of shortening of patellar tendon or patella infera , this technique is preferable A total knee arthroplasty can be completed using two techniques ; measured resection or gap balancing . A prospect i ve blinded r and omized controlled trial was completed with 103 patients r and omized to measured resection ( n = 52 ) or gap balancing ( n = 51 ) . Primary outcome measure was femoral component rotation . Secondary outcome measures were joint-line change , gap symmetry and function and quality -of-life outcomes .  Gap balancing result ed in a significantly raised joint-line compared to measured resection .  Gap symmetry was significantly better using gap balancing .  Functional outcomes and quality -of-life were not significantly different at 24 months . Using computer navigation , gap balancing significantly raises the joint-line in order to improve gap symmetry . This does not result in a clinical difference in function or quality of life at 24 months Purpose No surgical technique is capable of controlling the stability of the joint in midflexion . The purpose of the present study was to present and evaluate a surgical technique that aims to reduce the need for soft-tissue release and optimize stability in midflexion . Methods Sixty knee joints were included in this prospect i ve r and omized study . Surgery was performed either according to a classical gap ( GT ) technique or using the reversed gap ( RG ) technique . In the RG , the femoral component was positioned parallel to the surgical transepicondylar axis using a preoperative MRI and a navigation system . The frontal alignment of the tibia was then selected to produce a symmetric flexion gap . Then , the frontal alignment of the femoral component was adjusted to produce a symmetric extension gap . Soft-tissue release was defined to be extensive if more than two steps or stabilizing structures were involved . Joint stability was measured at different flexion angles ( −5 ° to 120 ° ) using a gap tensioning device and the trial femoral implant . Results In the GT group , 16 knee joints ( 53 % ) showed an instability of more than 2 mm at 5 ° , 30 ° or 60 ° , compared with 8 knee joints ( 27 % ) in the RG group ( p = 0.035 ) . The RG did not lead to a reduction in the number of soft-tissue releases , but they were less extensive . Conclusion RG reduced midflexion instability and the number of extensive soft-tissue releases . It may simplify the operation by reducing the extent of soft-tissue releases and avoid instability-related problems of knee arthroplasty . Nevertheless , it should only be performed under controlled conditions until long-term clinical data are available . Level of evidence Navigation has been developed to help surgeons install implants more accurately and reproducibly ; at the same time , this tool is able to record quantitative information such as joint range of motion , laxity and kinematics intra-operatively . As for st and ard surgery , two strategies are possible to achieve either femoral component rotation or overall prosthetic alignment : a measured gap resection approach , in which bone l and marks are used to guide resections equal to the distal and posterior thickness of the femoral component , or a gap-balancing technique , in which equal collateral ligament tension in flexion and extension is tried to find before as a guide to final bone cuts . The purpose of this paper is to compare the two different methods in a 67 patients group su bmi tted to the same procedure using mobile-bearing ( MB ) prosthesis  in order to analyse the effect of both techniques on joint line maintenance , axial limb restoration and components position . The gap group ( GG ) consists of 31 patients in whom the arthroplasty was performed using a navigated gap-balancing technique . The measured group ( MG ) consists of 36 patients in whom a computer-assisted measured resection technique was used . The results of imaging and the number of outliers were not statistically different ( P = 0.56 ) for the mechanical axis and prosthetic positioning between the two groups . The gap technique showed a statistically significant alteration of the post-operative value when compared with the measured resection technique , ( P = 0.036 ) . The mean elevation of the joint line was 4.09 mm for the GG and 3.50 mm in the MG Abstract Femoral component rotation from a  total knee prosthesis  can be determined by either a measured resection technique or a balanced gap technique . With the balanced gap implantation technique , femoral component rotation can vary freely within the restrictions produced by soft tissue structures . Because internal rotation might cause patella problems , the effect of ligament releases on femoral component rotation in a prospect i ve clinical study was studied .  Femoral component rotation  was measured intraoperatively with a tensor applied in flexion at 150 N in 87 knees . Great interpatient variability was found ; femoral component rotation , reference from the posterior condyles , ranged from −4 ° to 13 ° . There was no difference in femoral component rotation of knees with or without ligament releases in extension . However , knees with major medial release had less external femoral component rotation than knees with minor lateral releases . Preoperative alignment had no influence on femoral component rotation . The use of the balanced gap implantation technique theoretically will result in a balanced flexion gap , but the amount of femoral component rotation will be variable owing to patient variability and variation in ligament releases . Level of Evidence : Level II , therapeutic study . See the Guidelines for Authors for a complete description of levels of evidence Purpose . To compare the 2-year outcome of  total knee arthroplasty ( TKA ) using the measured resection versus the gap balancing techniques . Methods . 21 men and 31 women aged 41 to 89 ( mean , 73 ) years who underwent primary TKA by a single surgeon for osteoarthritis and had an American Society of Anesthesiologists I or II physical status were prospect ively studied . Patients were r and omised to undergo computer-assisted TKA using the measured resection technique ( n=26 ) or the gap balancing technique ( n=26 ) . At the 2-year followup , patients were assessed by a single orthopaedic registrar blinded to the type of surgery using the Knee Society score ( KSS ) , functional Knee Society score ( FKSS ) , and revised Oxford Knee score ( ROKS ) . Results . In the measured resection group , the mean KSS , FKSS , and ROKS increased from 34.3 , 48 , and 21 to 85.9 , 89.6 , and 36.5 , respectively . In the gap balancing group , the respective scores increased from 35.4 , 50 , and 22.5 to 89.1 , 92.4 , and 40.6 . Postoperative with the gap balancing technique ; the respective p values were 0.46 , 0.44 , and 0.12 . Conclusion . Improvements in the knee scores were comparable with the 2 techniques Purpose The aim of this study was to evaluate the accuracy of conventional instrumentation for tibial resection in total knee arthroplasty ( TKA ) as assessed by a computer-based navigation system during each phase of the surgical procedure . The hypothesis is that conventional instrumentation fails to achieve optimal accuracy in final implant positioning , thus leading to surgical errors . Methods Forty primary TKAs were performed .  The resection guide was placed using an extramedullary guide . Accurate guide positioning was assessed by the navigation system prior to the osteotomy . The alignment measurement was repeated after resection and after component implantation in order to quantify the deviation caused by the manual positioning of the prosthetic components . A deviation ≥2 ° was considered unsatisfactory . Results In the frontal plane , unsatisfactory results observed were as follows : 15 % with reference to manual positioning of the resection guide and 10 % with reference to definition of the resection plane with a tendency towards varus malalignment . In the sagittal plane , unsatisfactory results were as follows : 45 % with reference to manual positioning of the resection guide and 40 % with reference to definition of the resection plane with a trend of decreased tibial slope angle . The deviation between bone resection and subsequent implant placement was ≥2 ° in none of the cases . Conclusions The study confirms the hypothesis that conventional instrumentation fails to achieve optimal accuracy in the positioning of the tibial component . During each phase of the surgical procedure , a tendency towards varus malalignment and a decreased tibial slope angle were observed . Levels of evidence II Background Femoral component rotation ( FCR ) is one of the most important factors in total knee arthroplasty . In this prospect i ve study , we used three different techniques for FCR and analyzed their accuracy with postoperative axial computed tomography ( CT ) images . We also evaluated effect of FCR to clinical outcome . Methods One hundred sixty-five patients were r and omly allocated into three groups . In the measured resection group , FCR was set by externally rotating the axis 3 ° off the posterior femoral condylar axis . In the tensor group , a gap-tensioning device set at 20 lbf was used . In the block group , spacer blocks of various thicknesses were used . The FCR angle ( FCRa ) was measured on postoperative axial CT as an angle between the clinical transepicondylar and posterior condylar axes of the femoral component . Outliers were defined as FCRas deviated more than 3 ° either internally or externally . Postoperative 2 year clinical scores and knee range of motion were checked . Results The tensor group had significantly better positioning of the femoral component to the neutral position compared with the measured resection group and the block group ( mean FCRa : internal rotation 1.79 , 0.43 and 2.63 ° , respectively , p < 0.001 ) . The outliers were also least frequent in the tensor group ( 35 , 16 and 40 % , respectively , p = 0.02 ) . There were no significant differences in postoperative 2 year clinical results among groups . Conclusions Gap technique with a 20-lbf tensor device was the most accurate and precise method for obtaining adequate FCR . Measured resection with 3 ° external rotation and gap technique with blocks could lead to internal rotation of the femoral component . Postoperative 2 year clinical results were not significantly different among groups with different techniques for FCR.Trial registration The study was registered in the Clinical Research information Service ( trial number : KCT0000129 ) in Korea . Registration date is 23rd of June , 2011 The purpose of this study was to evaluate the use of a  navigation device  in a cohort of 42 total knee arthroplasties ( TKA ) . The patients were r and omised into two groups . Total knee arthroplasties performed using the conventional technique formed the control group ( 21 knees ) ; the experimental group included 21 knees performed with the aid of a computed navigation system .  Postoperative mean values for the various measurements showed no significant difference in component alignment . However , the range of individual measurements for coronal and sagittal plane positioning was smaller in the navigated group , in which there were no outliers . Rotational alignment was not different between the two groups . This confirms the advantages and limitations of navigated TKA presented in larger studies
The meta‐ analysis showed that GB techniques result ed in statistically significant improvements in the restoration of mechanical and rotational alignment and mean Knee Society Scores and Knee Society Function scores two years post‐operatively , but result ed in greater elevation of the position of the joint line .
There is no significant difference in the other radiographic data .
Conclusion This study suggests that GB may provide better radiographic and clinical outcomes than MR when used to determine mechanical rotation in TKAs
Aims There are two techniques widely used to determine the rotational alignment of the components in total knee arthroplasty ( TKA ) ;  gap balancing ( GB ) and measured resection ( MR ) .
Which technique is the best remains controversial .
We aim ed to investigate this in a systematic review and meta‐ analysis .