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 .
Prosthesis alignment affects axial rotation motion after total knee replacement: a prospective in vivo study combining computed tomography and fluoroscopic evaluations
Background Clinical consequences of alignment errors in  total knee replacement ( TKR ) have led to the rigorous evaluation of surgical alignment techniques . Rotational alignment in the transverse plane has proven particularly problematic , with errors due to component malalignment relative to bone anatomic l and marks and an overall mismatch between the femoral and tibial components ’ relative positions . Ranges of nominal rotational alignment are not well defined , especially for the tibial component and for relative rotational mismatch , and some studies advocate the use of mobile-bearing TKR to accommo date the result ing small rotation errors . However , the relationships between prosthesis rotational alignment and mobile-bearing polyethylene insert motion are poorly understood . This prospect i ve , in vivo study evaluates whether component malalignment and mismatch affect axial rotation motions during passive knee flexion after TKR . Methods Eighty patients were implanted with mobile-bearing TKR .  Rotational alignment of the femoral and tibial components was measured from postoperative CT scans . All TKR were categorized into nominal or outlier groups based on defined norms for surgical rotational alignment relative to bone anatomic l and marks and relative rotational mismatch between the femoral and tibial components . Axial rotation motion of the femoral , tibial and polyethylene bearing components was measured from fluoroscopic images acquired during passive knee flexion . Results Axial rotation motion was generally accomplished in two phases , dominated by polyethylene bearing rotation on the tibial component in early to mid-flexion and then femoral component rotation on the polyethylene articular surface in later flexion . Opposite rotations of the femur-bearing and bearing-baseplate articulations were evident at flexion greater than 80 ° . Knees with outlier alignment had lower magnitudes of axial rotation and distinct transitions from external to internal rotation during mid-flexion . Knees with femoral-tibial rotational mismatch had significantly lower total axial rotation compared to knees with nominal alignment . Conclusions Maintaining relative rotational mismatch within ±5 ° during TKR provided for controlled knee axial rotation during flexion . TKR with rotational alignment outside of defined surgical norms , with either positive or negative mismatch , experienced measurable kinematic differences and presented different patterns of axial rotation motions during passive knee flexion compared to TKR with nominal mismatch . These findings support previous studies linking prosthesis rotational alignment with inferior clinical and functional outcomes .Trial Registration Clinical Trials
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 .