Measured Resection Versus Gap Balancing for Total Knee Arthroplasty

Surgically balanced total knee arthroplasties have shown improved functional and clinical outcomes. Two different alignment methods have been proposed, the measured resection technique which uses femoral landmarks on the one hand and the ligament balanced technique which uses spreaders on the other. As anatomical landmarks also vary widely, with regards to the tibial cut irrespective of the collateral ligaments, we hypothesized that anatomical landmarks are not suitable for ideal femoral component rotational alignment. Ten cadaveric bilateral knees underwent TKA using a navigational device and a double tensiometer. By means of the navigational device, flexion gaps were balanced by femoral component size, rotation and flexion until a symmetric flexion and extension gap was obtained. Acquired femoral component rotation was compared to femoral landmarks (Whiteside Line, posterior condylar line and trans-epicondylar line). Using the Whiteside line, the posterior condylar line and the surgical trans-epicondylar line to identify femoral component rotation did not balance the flexion gap as well as navigation. Depending on the parameter, deviations in femoral rotation of up to 6° were observed compared to the gap balancing technique. Furthermore, large deviations between these landmarks were observed. Based on this study flexion gap balancing can be better optimized using ligament balancing technique. As this technique is highly dependent on the proximal tibial cut, we do recommend the use of navigational devices, which additionally assure a neutral leg alignment.

A goal of total knee arthroplasty is to obtain symmetric and balanced flexion and extension gaps. Controversy exists regarding the best surgical technique to utilize to obtain gap balance. Some favor the use of a measured resection technique in which bone landmarks, such as the transepicondylar, the anterior-posterior, or the posterior condylar axes are used to determine proper femoral component rotation and subsequent gap balance. Others favor a gap balancing technique in which the femoral component is positioned parallel to the resected proximal tibia with each collateral ligament equally tensioned to obtain a rectangular flexion gap. Two scientific studies have been performed comparing the two surgical techniques. The first utilized computer navigation and demonstrated a balanced and rectangular flexion gap was obtained much more frequently with use of a gap balanced technique. The second utilized in vivo video fluoroscopy and demonstrated a much high incidence of femoral condylar lift-off (instability) when a measured resection technique was used. In summary, the authors believe gap balancing techniques provide superior gap balance and function following total knee arthroplasty.

Comparison of Gap Balancing vs Measured Resection Technique in Patients Undergoing Simultaneous Bilateral Total Knee Arthroplasty: One Technique per Knee

Introduction Background:Optimal femoral component rotation in total knee arthroplasty (TKA) is crucial to establish a balanced knee reconstruction. Unbalanced knees can lead to instability, patellofemoral problems, persistent pain, stiffness, and generally poorer outcomes including early failure. There are several methods to achieve the femoral component rotation such as balanced gap technique, measured resection technique, and bone landmarks such as transepicondylar line (TEA) and Whiteside line. The purpose of this study was to compare the balan ced gap technique with the TEA technique.Materials and Methods:This randomised prospective study compares the femoral component rotation obtained with the use of balanced gap technique and the TEA, as well as compares the differences due to preoperative knee desaxations. The study includes 50 knees, 19 with neutral alignment, 22 with varus, and 9 with valgus desaxation. The femoral component rotation was measured postoperatively on photodocumentation taken after determining the TEA and balanced gap technique line peroperatively. These lines were compared to the posterior femoral condyles obtaining the degree of rotation. In case of transepicondylar line it is condylar twist angle (CTA) and in case of ligament balancer rotation axis it is ligament balancer angle (LBA).Results:The statistically significant differences in femoral component rotation using the techniques mentioned above as well as differences in individual knee desaxations were observed. The average LBA was 3.42 degrees and average CTA 3.58 in neutral knees group, but in the varus knees the average CTA value was 2.27 degrees and LBA value was 1.05 degrees. The average CTA value in patients with valgus desaxation is 4.78 degrees and LBA value is 5.22 degrees. According to Tukey Post Hoc test a statistically significant difference in LBA value is between neutral and varus knees with a significance level of p = 0.000022 and the most significant difference between varus and valgus knees with a significance level of p = 0.000011.Conclusion:The statistically significant differences in femoral component rotation using the techniques mentioned above as well as differences in individual knee desaxations were observed.

Introduction The decision to retain or sacrifice the posterior cruciate ligament (PCL) during total knee arthroplasty (TKA) is debated among surgeons. This study aimed to determine the effects of PCL removal on gap balancing, bone-cut thickness, and component positioning. Methods This prospective study included 70 consecutive patients with varus deformity undergoing Mako (Stryker Orthopaedics, Fort Lauderdale, FL, USA) robot-assisted TKA between January 2022 and June 2022. Flexion and extension gaps were initially captured with the PCL intact, using the mechanical alignment start-point, after which the knees were balanced using the functional alignment philosophy. Following this, the PCL was sacrificed, and gaps were recaptured to assess the dynamic change in balance and bone cut thickness, with statistical analyses performed. Results The mean age of the population was 59.46 years (SD = 9.2), with a female preponderance (N = 50, or 71.40%). PCL resection significantly increased the mean flexion gap in the medial compartment from 15.7 mm (SD = 2.36) to 18.8 mm (SD = 1.83), and in the lateral compartment from 22.7 mm (SD = 1.66) to 24.5 mm (SD = 1.62), with minimal change in the extension gap. Rebalancing after PCL resection resulted in a reduction in posterior femoral bone resection thickness, with the posteromedial cut decreasing from 9.6 mm to 7.1 mm, and the posterolateral cut from 4.8 mm to 2.7 mm. Conclusion This study demonstrates that PCL resection consistently leads to a preferential increase in the flexion gap, with minimal impact on the extension gap. The flexion gap increased more significantly in the medial compartment than in the lateral compartment, in approximately a 3:2 proportion. Additionally, PCL resection was associated with decreased posterior femoral bone resection thickness and a trend toward reduced femoral component external rotation.

Component Rotation in Well-Functioning, Gap Balanced Total Knee Arthroplasty Without Navigation

ObjectivesBecause posterior cruciate ligament (PCL) resection makes flexiongaps wider in total knee replacement (TKR), preserving or sacrificinga PCL affects the gap equivalence; however, there are no criteriafor the PCL resection that consider gap situations of each knee.This study aims to investigate gap characteristics of knees andto consider the criteria for PCL resection.MethodsThe extension and flexion gaps were measured, first with thePCL preserved and subsequently with the PCL removed (in cases inwhich posterior substitute components were selected). The PCL preservationor sacrifice was solely determined by the gap measurement results,without considering other functions of the PCL such as ‘roll back.’ResultsWide variations were observed in the extension and flexion gaps.The flexion gaps were significantly larger than the extension gaps.Cases with 18 mm or more flexion gap and with larger flexion thanextension gap were implanted with cruciate retaining component.A posterior substitute component was implanted with the other cases.ConclusionsIn order to make adequate gaps, it is important to decide whetherto preserve the PCL based on the intra-operative gap measurementsmade with the PCL intact.Cite this article: Bone Joint Res 2014;3:95–100.

At present, the clinical efficacy of measured resection (MR) and gap balancing (GB) techniques in total knee arthroplasty (TKA) is still controversial. The objective of this study was to evaluate the clinical outcome indexes of the two surgical methods through a meta-analysis. The literature was systematically searched on PubMed, EMBASE, Cochrane Library, China National Knowledge Infrastructure (CNKI), WANFANG, Weipu (VIP), and China Biomedical Literature (CBM) electronic databases inception until June 12, 2022. RevMan 5.3 software (the Nordic Cochrane Center, the Cochrane Collaboration, Copenhagen, Denmark) was used to analyze all data of this study. The Cochrane risk bias assessment tool is a risk bias evaluation criterion recommended by the Cochrane Handbook for systematic reviews. Eleven studies involving 1268 knees in total were included. The main outcome indexes showed that the Knee Society Score (KSS) knee score (MD: -1.40; 95% CI: -2.57 to -0.22; p=0.02) and KSS knee function score (MD: -3.11; 95% CI: -3.72 to -2.50; p<0.001) in the GB group were higher 1 year after operation, while femoral component rotation angle (FCRA; MD: -0.75; 95% CI: -1.34 to -0.07; p=0.03) and the osteotomy volume of the posterior medial femoral condyle (MD: -0.76; 95% CI; -1.13 to -0.38; p<0.001) were greater in the GB group. In addition, there was no significant difference in the joint line change (MD: -0.03; 95% CI: -0.07 to 0.01; p=0.16) between the two groups. Secondary outcome results showed that the knee joint range of motion (ROM) in 3 months, and the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) score after 1 year were better in the GB group. However, the operation time of the MR group was shorter. In addition, this study revealed no significant differences in post-complications between these two groups. Although the GB technique may not provide better radiographic results or reduce the complication rate, the recovery of joint function showed earlier improvement.

Flexion Space Balancing Through Component Positioning and Its Relationship to Traditional Anatomic Rotational Landmarks in Robotic Total Knee Arthroplasty

Creating balanced flexion and extension gaps is a crucial technical goal in TKR. Both measured resection and gap balancing techniques are currently used to establish femoral rotation and a rectangular flexion gap. Current data suggests use of the measured resection technique often results in flexion gap asymmetry and an increased incidence of femoral condylar lift-off. Due to the bony deformities often encountered in knee osteoarthritis, reproducibly identifying important bone landmarks can be limited. The gap balancing technique is independent of bony anatomy and, in the authors’ opinion, can be used to provide more reproducible flexion gap stability.

PurposeThe purpose of this study was to evaluate the change in posterior cruciate ligament (PCL) tension by directly measuring the pressure changes in the knee joint when the ligament was released or resected during total knee arthroplasty.MethodsWe prospectively analyzed 54 patients who underwent primary total knee arthroplasty (67 knees) from October 2019 to January 2022. An electronic pressure sensor was used to measure the pressure changes in the medial and lateral chambers on PCL retention, recession or resection.ResultsAt 0°, 45°, 90° and 120° of flexion, the total pressure in the knee joint of PCL retention was significantly higher than with PCL recession, and even higher than PCL resection. PCL recession or resection affected knee joint extension, and the medial/lateral pressure in the knee joint decreased. Pressure in the lateral compartment showed no significant change during knee flexion, whereas pressure in the medial compartment was significantly decreased, which also led to a change in the ratios of the medial and lateral pressures in the knee joint. After PCL resection, the flexion gap (90°) increased significantly more than the extension (0°) gap, while 46 cases displayed the same change in the flexion and extension gaps after PCL resection of the 67 cases.ConclusionThe PCL retained partial function after tibial recession. PCL resection affected both the flexion and extension gaps; although the average flexion gap increased more than the extension gap, the change in most cases of these two gaps was the same.

Complications after total knee arthroplasty (TKA) often involve the patellofemoral joint, and problems with patellar maltracking or lateral instability have sometimes been addressed by external rotation of the femoral component. This work sought to measure the changes of knee kinematics caused by TKA and then to optimise the restoration of both the patellofemoral and tibiofemoral joint kinematics, by variation of femoral component internal-external rotation. The kinematics of the patella and tibia were measured in eight cadaveric knees during active extension motion. This was repeated with the knee intact, with a Genesis II TKA in the standard position (3° of external rotation) and with the femoral component at ±5° rotation from there. Both patellar and tibial motions were significantly different from normal with the standard TKA rotation, with 3° tibial abduction at 90° flexion and reversal of the screw-home from 5° external rotation to 6° internal rotation. The patella was shifted medially 6mm in flexion and tilted 7° more laterally near extension. Femoral rotation to address one abnormality caused increased abnormality in other degrees of freedom. Internal and then external rotation of 5° caused tibial abduction and then adduction of 5° at 90° flexion. These femoral rotations also caused increased patellar lateral tilt of 4° with femoral external rotation and decreased tilt by 4° with internal rotation. Thus, correction of tibial abduction in flexion, by external rotation of the femoral component, worsened the patellar lateral tilt near extension. It was concluded that femoral rotation alone could not restore all aspects of both patellar and tibial kinematics to normal with this specific implant. The clinical relevance of this is that it appears to be inadvisable to reposition the femoral component, in an attempt to improve patellar tracking, if that repositioning may then cause abnormal tibiofemoral kinematics. Further, the pattern of patellar tracking, with the type of TKA used in this study, could not be adjusted to normal by femoral component rotation.

Posterior cruciate ligament (PCL) resection during posterior-stabilized total knee arthroplasty (PS-TKA) has been reported to preferentially increase the tibiofemoral joint gap in flexion compared with extension. However, previous assessments of the joint gaps have been performed after bone resection and medial soft tissue release. Thus, these procedural steps may have the potential to influence soft tissue balance. In native knees, soft tissue laxity is generally greater in the lateral compartment than in the medial compartment both with the knee in extension and in flexion. Some surgeons may retain this natural soft tissue balance with less aggressive medial release during TKA. We performed this study to evaluate the impact of the PCL resection on the extension and flexion gaps in the absence of bone resection or medial soft tissue release. Tibiofemoral joint gaps for 41 patients (10 males and 31 females) in full extension and at 90 degrees of flexion both before and after the resections of both the anterior cruciate ligament (ACL) and PCL were assessed using a ligament tensioner device. The statistical analyze was performed using the Mann-Whitney U test. The results showed that medial gap in extension and flexion were 6.7 ± 1.0 and 7.3 ± 0.9 mm, and lateral gap in extension and flexion were 7.6 ± 1.1 and 8.4 ± 1.6 mm, respectively. Thus, physiological tibiofemoral gaps just after knee arthrotomy were trapezoidal and asymmetric shape with the significantly wider gaps in lateral and flexion, compared with the medial and extension, respectively (p < 0.05). However, the increases of the gaps with the ACL and PCL resections were less than 1 mm under the existence of medial soft tissues. As the medial collateral ligament is the primary restraint for the valgus instability, it was also considered to prevent the increase of the flexion gap although the PCL-which is the secondary restraint for the valgus instability-was resected. This finding is critically important for orthopedic surgeons applying PS-TKA implants, particularly for preserving soft tissues to achieve natural knee kinematics postoperatively.

Purpose : To assess the effects of a posterior cruciate ligament resection on the tibiofemoral joint gap in total knee arthroplasty. Materials and Methods : The effect of a PCL resection on the tibiofemoral joint gap was analyzed prospectively in 58 patients (69 knees) who had undergone TKA between May 2003 and April 2006. The knee was exposed using a modified subvastus approach. The medial soft tissue was released and a tibial cutting was made first. The tibial insertion of a PCL was protected during the tibial resection by inserting a thin osteotome in front of the posterior spine. An extension and flexion gap were measured using a balancer/tensor device (Stryker Howmedica OsteonicsⓇ, Allendale, NJ, USA) under manual maximal stress before and after the PCL resection. The change of the joint line and the posterior inclination on preoperative and postoperative lateral roentgenograms was also assessed. Results : After the PCL resection, the flexion gap and extension gap increased by an average of 3.6±1.5 mm and 2.0±1.0 mm, respectively. Although the PCL resection resulted in an increasing a flexion gap and extension gap, the increase in the flexion gap was larger than that of the extension gap by 1.6 mm. Conclusion : A PCL resection resulted in an increase in the flexion and extension gaps by 3.6 mm and 2.0 mm, respectively. Therefore, a PCL resection would be a good alternative method for controlling the flexion-extension gap in TKA.

Flexion gap stabilization by oversizing posterior condylar offset in deep-dished total knee replacement does not compromise flexion: A single-surgeon, retrospective, observational, mid-term series