The effect of flexion balance on functional outcomes in cruciate-retaining total knee arthroplasty

Medial Laxity Leads to Inferior Postoperative Clinical Outcomes and Function in Total Knee Arthroplasty

BACKGROUND

Achieving proper soft-tissue balance is essential for improving total knee arthroplasty outcomes. This multicenter study aimed to analyze the effects of the gap angle and medial and lateral component gaps on clinical outcomes.

METHODS

This retrospective multicenter cohort study was conducted on 656 knees in 11 centers. A tensor device was used to measure the joint gap and varus-valgus angle of the joint gap, and medial and lateral component gaps were determined by subtracting the polyethylene thickness. Correlations between the gap angle, component gap, and clinical outcomes using the Knee Society Score (KSS) and the new Knee Society Score (2011 KSS) were analyzed.

RESULTS

The varus gap angle in flexion positively correlated with the KSS knee score (r = 0.118, P = 0.0183), KSS function score (r = 0.164, P = 0.0009), 2011 KSS symptoms (r = 0.148, P = 0.0030), and 2011 KSS functional activities (r = 0.129, P = 0.0099). The medial component gap in extension negatively correlated with the KSS function score (r = -0.113, P = 0.0241) and that in flexion negatively correlated with the 2011 KSS symptoms (r = -0.127, P = 0.0078) and the 2011 KSS patient satisfaction score (r = -0.119, P = 0.0126). The lateral component gap had no correlation with clinical outcomes. The valgus gap group in flexion showed poorer clinical outcomes than the severe varus, varus, and/or balanced gap groups. The slightly loose group of the medial component gap in extension showed lower 2011 KSS symptoms (P = 0.0352) and functional activities (P = 0.0085) than that in the tight group.

CONCLUSIONS

The valgus joint gap and medial looseness are negatively correlated with clinical outcomes, and residual varus joint gap and lateral laxity can be tolerated. Bone resection and soft-tissue release should be performed carefully to prevent medial looseness.

Intraoperative lateral laxity greater than 4° is associated with inferior functional improvement in posterior-stabilised total knee arthroplasty

PURPOSE

The study aimed to determine the impact of intraoperative lateral laxity at extension on clinical and functional outcomes 1 year after posterior-stabilised total knee arthroplasty (PS-TKA).

METHODS

In total, 91 varus-type osteoarthritic knees that underwent PS-TKA using the medial preservation gap technique were included. After the femoral trial component placement and patellofemoral joint reduction, the soft-tissue balance was assessed using an offset-type tensor with a 40-lb joint-distraction force. Patients were divided into the following three groups according to the intraoperative lateral laxity at extension (i.e., varus ligament balance) using the mean ± 1 standard deviation: Groups A, ≤0°; B, 0-4°; and C, >4°. The 2011 Knee Society Score (KSS) and 3-m timed up-and-go test (TUG) time 1-year postoperatively, and their improvements were compared among the groups.

RESULTS

While significant improvements were observed in all subscales of the 2011 KSS and TUG post-TKA (p < 0.05), the improvement of functional activities and TUG time were significantly lower in Group C than in Group B (p < 0.05). However, no significant differences were observed in symptom improvement, patient satisfaction or patient expectation scores among the groups.

CONCLUSION

An excessive lateral laxity (varus angle) >4° at extension was associated with lower improvement in functional ability 1-year postoperatively. Therefore, excessive intraoperative lateral laxity should be avoided in PS-TKA.

LEVEL OF EVIDENCE

Level IV.

Limited medial posterior capsular release increases the intraoperative medial component gap while maintaining the joint varus angle at extension in posterior-stabilized total knee arthroplasty

PURPOSE

There is a lack of robust evidence for the magnitude of the effects of posterior capsular release (PCR) on intraoperative component gaps during total knee arthroplasty (TKA). The purpose of the present study was to quantify and compare the effects of partial versus full PCR on the intraoperative component gaps at various degrees of flexion during posterior-stabilized TKA.

METHODS

Full PCR was performed on 39 consecutive cases (full PCR group), and partial PCR (the medial side up to and including the intercondylar notch) was performed on the subsequent 39 consecutive cases (partial PCR group) during posterior-stabilized TKA using the measured resection technique for varus knee osteoarthritis. Medial component gaps and varus angles at 0°, 10°, 45°, 90°, and a maximum of flexion were measured with a tensor device before and after the PCR. Differences between the two groups in post-release medial component gap increase and post-release joint varus angle increase were assessed using a t test. Pre- to post-release medial component gaps and joint varus angles in each group were compared using a paired samples t test.

RESULTS

In both groups at 0° and 10° of flexion, post-release medial compartment gaps were significantly greater than pre-release gaps (all P < 0.001). At 45°, 90° and maximum flexion, the medial compartment gap increase did not exceed the minimal detectable change in either group. At 0° and 10° of flexion, there was no significant difference in post-release medial compartment gap change between the two groups. In the full PCR group, post-release joint varus angles at 0° of flexion were significantly greater than pre-release angles (P < 0.001), while there was no significant pre- and post-release difference in the partial PCR group. The change in post-release joint varus angles at 0° of flexion was significantly greater in the full PCR group than in the partial PCR group.

CONCLUSION

Both full and partial PCR show similar clinical usefulness for increasing the medial component gap at extension and reducing component gap mismatch. A partial PCR can be used to avoid increasing joint varus angles at 0° of flexion.

LEVEL OF EVIDENCE

Level 2 (prospective comparative study).

The Usefulness of a Simplified Navigation-Based Instrumentation for a Novice Surgeon in Primary Total Knee Arthroplasty: A Retrospective Analysis of a Randomized Controlled Trial

Background

A novel simplified navigation-based instrumentation system has been developed. It simplifies the existing navigation system and facilitates convenient bone cutting by positioning the tracker on an existing cutting block without additional pin fixation. This study aimed to compare the outcomes of this newly developed simplified navigation-based instrumentation system in primary total knee arthroplasty (TKA) performed by a novice surgeon with those of conventional surgical techniques.

Methods

From January 2020 to July 2020, 67 knees that underwent primary TKA using the ExactechGPS TKA Plus (group A) were compared to 68 knees that underwent primary TKA using a conventional technique (group B). All patients had a minimum follow-up of 24 months. The operative details such as tourniquet time were investigated. Postoperative hip-knee-ankle (HKA) angle and component position angles in the coronal and sagittal planes (α, β, γ, and δ angles) were evaluated. The outlier rates were compared between the groups as those lying outside ± 3°. Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, the Western Ontario and McMaster Universities Osteoarthritis Index for pain and function, and range of motion were compared.

Results

There was no statistically significant difference in average tourniquet time between the groups (74.3 vs. 70.3 minutes, p = 0.061). Outlier rates for HKA angle (7.5% vs. 23.5%, p = 0.010) and β angle (1.5% vs. 22.1%, p < 0.001) in group A were significantly lower than those in group B. There were no significant differences in clinical outcomes between the groups.

Conclusions

Primary TKA performed by a novice surgeon using a simplified navigation-based instrumentation system did not significantly increase the operation time, and more accurate lower extremity mechanical alignment and tibial component alignment in the coronal plane could be obtained.

Medial osteophyte resection width correlates with correction of the medio-lateral component gap imbalance during posterior-stabilized total knee arthroplasty

BACKGROUND

There is a lack of robust evidence for a correlation between the medial osteophyte resection and correction of the medio-lateral gap imbalance during total knee arthroplasty. The purpose of the present study was to quantify the effect of osteophyte resection on the medio-lateral component gap imbalance during posterior-stabilized total knee arthroplasty.

METHODS

Forty-five cases of primary posterior-stabilized total knee arthroplasty using the measured resection technique with posterior-stabilized prosthesis for varus knee osteoarthritis were reviewed. Medial and lateral joint gaps at 0°, 10°, 45°, and 90° of flexion, and maximum flexion were measured intraoperatively before and after the osteophyte resection. The relationship between medial osteophyte resection width and change of joint varus angle and medial component gap were assessed using Pearson's correlation coefficient.

FINDINGS

Medial component gap and joint varus angle values at post medial osteophyte resection were significantly larger and lower than at pre-resection (Medial gap: pre 9.5 ± 1.8 mm, post 10.3 ± 1.8 mm, P < 0.001, Joint angle: pre 5.2 ± 2.9°, post 4.2 ± 2.9°, P < 0.001). There was no significant difference between pre and post medial osteophyte resection in lateral component gaps. Per each 1 mm of medial osteophyte resection width, increases of 0.13 mm medial component gap and 0.2° valgus were observed (Medial gap: r = 0.38, P < 0.001, Joint angle: r = 0.38, P < 0.001).

INTERPRETATION

Medial osteophyte resection increases the medial component gap without lateral component gap increase, while decreasing the joint varus angle in primary posterior-stabilized total knee arthroplasty for varus knee osteoarthritis. Osteophyte resection width was found to correlate with correction of the medio-lateral component gap imbalance.

Both Intraoperative Medial and Lateral Joint Stabilities at Midflexion Influence Postoperative Patient-Reported Outcome Measures Following Bi-Cruciate Stabilized Total Knee Arthroplasty

Bi-cruciate stabilized (BCS) total knee arthroplasty (TKA) was developed to approximate normal knee kinematics and is expected to improve clinical outcomes. However, the effects of soft tissue balance at the medial or lateral compartment on patient-reported outcome measures (PROMs) following BCS TKA are unclear. The purpose of this study was to clarify the relationship between the medial or lateral component gaps and PROMs following BCS TKA. One hundred seventeen knees with varus deformities which underwent BCS TKA were included in this study. They were divided into two groups according to the validated Japanese version of the Knee Injury and Osteoarthritis Outcome Score for each subscale of pain, symptoms, and activities of daily living (ADL) at 1 year postoperatively: group H consisted of patients with ≥90 points and group L consisted of patients with <90 points. Intraoperative medial and lateral joint laxities at 0°, 30°, 60°, 90°, and 120° flexion measured using a tensor device were compared between the two groups in each subscale. In the pain subscale, the medial joint laxities at 30° (p < 0.05) and 60° flexion (p < 0.05) in group H were significantly smaller than those in group L. In the ADL subscale, the medial joint laxity at 60° flexion in group H was significantly smaller than that in group L (p < 0.05). In the symptom subscale, the lateral joint laxity at 60° flexion in group H was significantly smaller than that in group L (p < 0.05). Surgeons should pay attention to the importance of both medial and lateral joint stabilities to achieve better postoperative PROMs following BCS TKA.

Anatomical evaluation of the femoral attachment of the posterior oblique ligament

INTRODUCTION

Tibiofemoral joint instability reduces patient satisfaction after total knee arthroplasty (TKA). However, surgeons sometimes encounter excessive medial joint laxity without medial over-release on the tibial side. It was hypothesized that over-resection of the posteromedial femoral condyle can injure the medial stabilizers, especially the posterior oblique ligament (POL) at its femoral attachments.

MATERIALS AND METHODS

Thirteen fixed cadaveric knees were exposed, and 3 anatomical points were identified: the posterior edge and midpoint of the POL femoral attachment, and the posterior edge of the superficial medial collateral ligament (sMCL) femoral attachment. The distance from the surface of the posteromedial femoral condyle to each point was measured. Correlations between each point and the anterior-posterior or medial-lateral dimensions of the distal femur were also calculated.

RESULTS

The average distances to the posterior edge and midpoint of the POL femoral attachment and the posterior edge of the sMCL femoral attachment were 13.7 mm (9.0-18.4), 17.9 mm (11.5-22.6), and 22.7 mm (14.7-29.4), respectively. There were moderate correlations between the distance to each point and the anterior-posterior or medial-lateral dimensions of the distal femur.

CONCLUSIONS

The minimal distance from the surface of the posteromedial condyle to the POL posterior edge was 9.0 mm. Over-resection of the posteromedial femoral condyle, even with a general TKA femoral component, might injure the POL at its femoral attachments, especially in patients with small distal femurs, while the sMCL is rarely damaged.

LEVEL OF EVIDENCE

Level IV.

Intraoperative physiological lateral laxity in extension and flexion for varus knees did not affect short-term clinical outcomes and patient satisfaction

PURPOSE

Medial release during total knee arthroplasty (TKA) is used to correct ligament imbalance in knees with varus deformity. However, questions remain on whether residual ligament imbalance would be related to inferior clinical results. The purposes of the present study were to measure the intraoperative joint gap and to evaluate the effect of intraoperative soft tissue condition on the new Knee Society Score (KSS 2011) at 2-year follow-up, without the maneuver of additional medial release to correct the asymmetrical gap balance.

METHODS

Varus-valgus gap angle and joint gap were measured using a tensor device without medial release for 100 knees with preoperative varus deformity. The knees were categorized according to the varus-valgus gap angle and the laxity. The preoperative and postoperative clinical outcomes using KSS 2011 were compared between the groups.

RESULTS

The average varus-valgus angles had a residual imbalance of 2.8° varus and 1.3° varus in extension and flexion, respectively. In comparison, according to varus-valgus joint gap angle and knee laxity in extension and flexion, no significant differences were found in postoperative range of motion and subscale of KSS 2011 among the groups.

CONCLUSION

Intraoperative asymmetrical joint gap and physiological laxity do not affect early clinical results after TKA.

LEVEL OF EVIDENCE

III.

Reliability of stress radiography in the assessment of coronal laxity following total knee arthroplasty

BACKGROUND

Stress radiography is used in the valuation of soft tissue laxity following total knee arthroplasty (TKA). However, reliability and agreement is largely unknown.

METHODS

In this prospective reliability study, we included 15 participants with prior TKA. Standardized coronal stress radiographs were obtained in both extension and flexion and with both varus and valgus stress. All radiographs were repeated (test-retest). In extension the Telos stress device was used, and flexion radiographs were obtained using the epicondylar-view. Three independent raters measured angulation between femoral and tibial component from all radiographs. Reliability was assessed by intra-class correlation coefficient (ICC) and agreement visualized with Bland-Altman plots and by mean difference and limits of agreement (LOA).

RESULTS

Stress radiography in extension showed excellent reliability with ICC = 0.96 (0.95-0.98) and LOA of ±1.2°. Stress radiography at 80-90° of flexion showed good to excellent reliability when measuring medial laxity with ICC = 0.94 (0.89-0.97) and LOA of ±1.7°; however, when measuring lateral laxity the reliability was only moderate to good with ICC = 0.70 (0.51-0.84) and LOA of ±6.3°.

CONCLUSION

Stress radiography is clinically applicable and the methods described in this study provide excellent reliability for measurement of laxity in extension. The reliability of measurements in flexion is good to excellent when measuring medial laxity but only moderate to good when measuring lateral laxity.

Relationship between outcome scores and knee laxity following total knee arthroplasty: a systematic review

Background and purpose - Instability following primary total knee arthroplasty (TKA) is, according to all national registries, one of the major failure mechanisms leading to revision surgery. However, the range of soft-tissue laxity that favors both pain relief and optimal knee function following TKA remains unclear. We reviewed current evidence on the relationship between instrumented knee laxity measured postoperatively and outcome scores following primary TKA. Patients and methods - We conducted a systematic search of PubMed, Embase, and Cochrane databases to identify relevant studies, which were cross-referenced using Web of Science. Results - 14 eligible studies were identified; all were methodologically similar. Both sagittal and coronal laxity measurement were reported; 6 studies reported on measurement in both extension and flexion. In knee extension from 0° to 30° none of 11 studies could establish statistically significant association between laxity and outcome scores. In flexion from 60° to 90° 6 of 9 studies found statistically significant association. Favorable results were reported for posterior cruciate retaining (CR) knees with sagittal laxity between 5 and 10 mm at 75-80° and for knees with medial coronal laxity below 4° in 80-90° of flexion. Interpretation - In order to improve outcome following TKA careful measuring and adjusting of ligament laxity intraoperatively seems important. Future studies using newer outcome scores supplemented by performance-based scores may complement current evidence.

Intraoperative medial joint laxity in flexion decreases patient satisfaction after total knee arthroplasty

INTRODUCTION

The relationship between postoperative tibiofemoral ligament balance and patient satisfaction in total knee arthroplasty (TKA) has been explored previously. However, the optimal intraoperative medial-lateral ligament balance during knee flexion in terms of postoperative patient satisfaction remains unknown. We evaluated the effect of intraoperative flexion instability on patient satisfaction after TKA.

MATERIALS AND METHODS

This study consisted of 46 knees with varus osteoarthritis undergoing TKA. Medial-lateral component gaps at 0° knee extension and 90° flexion were measured intraoperatively using a knee balancer. Differences in postoperative patient outcomes at 3 weeks and 1 year were compared between medially tight knees in 90° flexion with a medial component gap of < 4 mm and medially loose knees in 90° flexion with a gap of ≥ 4 mm. Outcomes were measured using the 2011 Knee Society Scoring System (2011 KS).

RESULTS

The median total 2011 KS score at 1 year postoperatively in the medially loose knees [median 97; interquartile range (IQR) 75-117] was significantly lower than that in the medially tight knees (median 128; IQR 104-139, P < 0.01), while preoperative and 3-week postoperative scores were similar. In addition, medial flexion gaps were not significantly associated with total 2011 KS scores before surgery or at 3 weeks postoperatively. However, at 1 year after surgery, medial component flexion gaps were negatively associated with the total 2011 KS score (R = - 0.42; P < 0.01) and the 2011 KS satisfaction subscale score (R = - 0.36; P = 0.01).

CONCLUSIONS

Excessive intraoperative medial joint laxity of ≥ 4 mm at 90° flexion progressively decreased patient satisfaction for 1 year. Since intraoperative medial laxity in flexion is likely to interfere with functional recovery after TKA, medial stabilization during TKA is important throughout knee flexion.

LEVEL OF EVIDENCE

Therapeutic study, Level III.

Objective quantification of ligament balancing using VERASENSE in measured resection and modified gap balance total knee arthroplasty

BACKGROUND

Soft tissue balancing which is above all most important factor of total knee arthroplasty, has been performed by subjective methods. Recently objective orthosensor has been developed for compartment pressure measurement. The purpose of this study was: (1) to quantify the compartment pressure of the joint throughout the range of motion during TKA using orthosensor, (2) to determine the usefulness of orthosensor by analyzing correlation between the pressure in both compartment with initial trial and after final implantation, and (3) to evaluate the types and effectiveness of additional ligament balancing procedures to compartment pressure.

METHODS

Eighty-four patients underwent total knee arthroplasty (TKA) using VERASENSE Knee System. TKA was performed by measured resection and modified gap balance technique. Compartment pressure was recorded on full extension, 30°, 60°, 90° and full flexion at initial (INI), after each additional procedure, and after final (FIN) implantation. "Balanced" knees were defined as when the compartment pressure difference was less than 15 pounds.

RESULTS

Thirty patients (35.7%) showed balanced knee initially and 79 patients (94.0%) showed balance after final implantation. The proportion of balanced knee after initial bony resection, modified gap balancing TKAs showed significantly higher proportion than measured resection TKAs (P = 0.004) On both compartment, the pressure was generally decreased throughout the range of motion. Linear correlation on both compartment showed statistically significant throughout the range on motion, with higher correlation value on the lateral compartment. Total 66 additional ligament balancing procedures were performed.

CONCLUSION

Using orthosensor, we could obtain 94% quantified balance knee, consequently. And between the techniques, measured resection TKA showed less balanced knee and also required more additional procedures compared to modified gap balancing TKA. Furthermore, with the acquired quantified data during appropriate ligament balancing, the surgeon could eventually reduce the complications associated with soft tissue imbalance in the future.

Medial rather than lateral knee instability correlates with inferior patient satisfaction and knee function after total knee arthroplasty

BACKGROUND

It is commonly thought that balanced medial and lateral tibiofemoral joint gaps are essential, but the effect of joint laxity on clinical outcome after total knee arthroplasty (TKA) is unclear. It was hypothesised that medial joint laxity correlates with inferior patient satisfaction and knee function, although lateral joint laxity is allowed to a certain degree in TKA.

METHODS

This study included 50 knees that underwent primary TKA. Knee laxity was measured with postoperative stress radiographs in flexion and extension, and patient satisfaction and knee function were evaluated by the 2011 Knee Society Knee Scoring System.

RESULTS

In a comparison of medially tight and medially loose knees in flexion, the scores for satisfaction, symptoms, standard activity, and advanced activity were significantly better in medially tight than in medially loose knees (satisfaction: 29.8, 22.2; symptoms: 20.3, 15.9; standard activities: 24.2, 19.1; and advanced activities: 15.3, 8.7, in the tight and loose knees, respectively). Neither lateral joint laxity during knee flexion nor medial joint laxity during knee extension was associated with a poor postoperative clinical outcome, whereas lateral joint laxity and the standard activity score in extension had a moderate positive correlation.

CONCLUSIONS

Knees with medial joint laxity during flexion resulted in an inferior postoperative outcome, and lateral joint laxity did not influence patient satisfaction or function. Care should be taken to maintain medial joint stability during the TKA procedure.

Baropodometry on patients after total knee arthroplasty

PURPOSE

It is well known that total knee replacement surgery decreases pain and improves function, but the effect on postural assessment needs to be studied better with the use of new technological devices. Total knee arthroplasty (TKA) improves motor coordination and stability of the knee. On the other hand, changing joint functionality can modify the balance. The aim of this trial is to record and analyze the static and dynamic baropodometric data of patients in the first few months following joint replacement. For the physiatrist, this tool can be useful to check if the rehabilitation treatment protocols and times are correct.

METHODS

We designed a prospective observation longitudinal study to assess postural stability following TKA. Between December 2014 and May 2015, sixty consecutive patients were recruited through local orthopedic physician offices and hospitals. The patients scheduled to undergo TKA were recruited and were monitored before surgery (T0) and at 1 (T1), 3 (T2) and 6 months (T3) after knee surgery. The correction of varus/valgus deviation at X-ray and the Knee Society Score were performed to verify the functional recovery. We used static and dynamic baropodometric analysis to evaluate postural assessment.

RESULTS

After surgery, there was a significant improvement in physiological alignment of knee axes (p < 0.0001) and of Knee and Function Scores (excellent, mean values 80.5 and 80.7, respectively, p < 0.0001). The static analysis showed that the center of gravity and the pressure on the foot of the operated limb were corrected toward the physiological center (p < 0.0001) and the body weight displaced to the forefeet and to the hindfeet reduced bilaterally (p < 0.0001). The type of footprint did not change. The dynamic analysis confirmed the significant normalization of the pressure on the foot of the operated limb at all follow-ups (p < 0.0001). The percentage of load was reduced on the operated limb (p = 0.0096) and speed of step, cadence and semi-step length increased (p < 0.0001).

CONCLUSION

These data show the progressive recovery of stability after TKA from the immediate postoperative to the subsequent months. The clinical and functional improvement correlated with a load redistribution between the two limbs. The baropodometry could be an excellent noninvasive method for monitoring effects of rehabilitation treatment.

Intraoperative Measurements and Tools to Assess Stability

Knee stability is the ability for the joint to maintain an appropriate functional position throughout its range of motion. Knee instability can be defined as excessive laxity during activities of daily living. Intraoperative knee laxity can be affected by implant design, alignment of components, and soft-tissue balancing. Soft-tissue balance is a major contributor to knee instability. Mechanical balancing instruments can be classified as spacer blocks or joint-distraction devices. Conventional wisdom favors rectangular and equal flexion-extension gaps. However, knee balance is elusive even with mechanical balancing instruments. First-generation electronic balancing devices are equivalent in concept to spacer blocks instrumented with force sensors. Second-generation electronic balancing devices are equivalent in concept to mechanical distraction devices instrumented with pressure and displacement sensors. Electronic ligament balancers can be useful in documenting intraoperative knee laxity for quantifiable correlation with postoperative outcomes, thus directly relating postoperative stability to surgical balance, and may predict outcomes and knee stability.

Can Intraoperative Sensors Determine the "Target" Ligament Balance? Early Outcomes in Total Knee Arthroplasty

BACKGROUND

The optimal "target" ligament balance for each patient undergoing total knee arthroplasty (TKA) remains unknown. The study purpose was to determine if patient outcomes are affected by intraoperative ligament balance measured with force-sensing implant trials and if an optimal "target" balance exists.

METHODS

A multicenter, retrospective study reviewed consecutive TKAs performed by 3 surgeons. TKA's were performed with standard surgical techniques and ligament releases. After final implants were made, sensor-embedded smart tibial trials were inserted, and compartment forces recorded throughout the range of motion. Clinical outcome measures were obtained preoperatively and at 4 months. Statistical analysis correlated ligament balance with clinical outcomes.

RESULTS

One hundred eighty-nine consecutive TKAs were analyzed. Patients were grouped by average medial and lateral compartment force differences. Twenty-nine TKAs (15%) were balanced within 15 lbs and 53 (28%) were "balanced" greater than 75 lbs. Greater improvement in University of California Los Angeles activity level was associated with a mediolateral force difference <60 lbs. (P = .006). Knee Society objective, function, and satisfaction scores, and self-reported health state were unrelated to mediolateral balance in the knee.

CONCLUSION

Intraoperative force-sensing has potential in providing real-time objective data to optimize TKA outcomes. These data support some early outcomes may improve by balancing TKAs within 60 lbs difference. Close follow-up is warranted to determine if gait pattern adaptations affect longer term outcomes with greater or less ligament "imbalance."