Are Patients More Satisfied With a Balanced Total Knee Arthroplasty?

doi:10.1016/j.arth.2019.03.036

The Journal of Arthroplasty

Volume 34, Issue 7, Supplement, July 2019, Pages S195-S200

https://doi.org/10.1016/j.arth.2019.03.036 Get rights and content

Abstract

Background

Patient-reported outcome measures are increasingly recognized as an important tool in quantifying the clinical success of arthroplasty surgery. The aim of this study is to measure post-operative joint awareness and satisfaction in patients with and without a quantitatively balanced knee following primary total knee arthroplasty (TKA).

Methods

In this multi-center study, a total of 318 eligible patients were assigned to one of the 2 patient groups: sensor-guided TKA or surgeon-guided TKA. In the sensor-guided group, quantitative balancing was performed according to intercompartmental tibiofemoral load measurements measured by an instrumented tibial trial component. In contrast, for the surgeon-guided group, the knees were balanced according to the surgeons’ standard manual techniques while blinding the surgeon to the sensor measurements. Patients were blinded to their allocation and filled out the validated Forgotten Joint Score and 2011 Knee Society Satisfaction questionnaires at 6 weeks and 6 months. For the purposes of this study, the subjects were pooled and stratified by their state of soft tissue balance, based on the mediolateral load differential through the range of motion.

Results

In the surgeon-guided group, approximately 50% of the cases yielded a quantitatively balanced knee. Significantly more balanced knees were observed in the sensor-guided group (84.0%). More importantly, for both outcome measures, the balanced group of patients reported significantly better outcomes scores.

Conclusion

This demonstrates that using sensor feedback during knee arthroplasty surgery results in a more reproducible procedure, resulting in a higher percentage of balanced patients who in turn demonstrate superior clinical outcomes compared to unbalanced patients.

Section snippets

Patient Population

Following protocol approval by the Institutional Review Board at each of the 6 participating institutions (11 surgeons), a consent was obtained from 332 patients scheduled for primary TKA. Inclusion criteria included diagnosis of osteoarthritis, age between 18 and 80 years, angular coronal deformity in extension less than 20°, a flexion contracture of less than 20°, a passive arc of motion of at least 90°, and primary arthroplasty. Patients with prior TKA surgery, avascular necrosis, ligament

Potential Confounding Factors

To assure an unbiased evaluation of the effect of balancing, potential confounding factors were evaluated prior to an in-depth multi-variate analysis. These factors included the patient’s age, gender, and BMI as well as if the patient is currently smoking or employed and whether the patient has undergone previous surgery on the operated knee. All factors have been compared between the balanced and unbalanced cohorts as well as the surgeon-guided and sensor-guided cohorts. An overview is

Discussion

This prospective, multi-center, blinded controlled trial is the first to report a comparison of patient-reported outcomes between quantitatively balanced and unbalanced TKA using the FJS and the 2011 KSS Satisfaction and Expectations scores. We found that patients with a quantitatively balanced total knee, defined by an average mediolateral load differential less than 15 lbs at 10°, 45°, and 90°, had better outcomes scores at 6 weeks and 6 months compared to patients with quantitatively

Acknowledgements

The authors acknowledge the assistance of Michael Conditt, PhD, and Matthias Verstraete, PhD, employees of OrthoSensor, Inc for their assistance in statistical analysis and preparation and proofreading of the manuscript.

References (31)

H. Behrend et al.
The “forgotten joint” as the ultimate goal in joint arthroplasty: validation of a new patient-reported outcome measure
J Arthroplasty
(2012)
P.H. Bullens et al.
Patient satisfaction after total knee arthroplasty: a comparison between subjective and objective outcome assessments
J Arthroplasty
(2001)
W.C. Schroer et al.
Why are total knees failing today? Etiology of total knee revision in 2010 and 2011
J Arthroplasty
(2013)
K.A. Gustke et al.
A new method for defining balance: promising short-term clinical outcomes of sensor-guided TKA
J Arthroplasty
(2014)
E. Schnaser et al.
The position of the patella and extensor mechanism affects intraoperative compartmental loads during total knee arthroplasty—a pilot study using intraoperative sensing to guide soft tissue balance
J Arthroplasty
(2015)
P. Sculco et al.
The role of the tourniquet and patella position on the compartmental loads during sensor-assisted total knee arthroplasty
J Arthroplasty
(2018)
K.A. Gustke et al.
A targeted approach to ligament balancing using kinetic sensors
J Arthroplasty
(2017)
J.A. Geller et al.
The use of electronic sensor device to augment ligament balancing leads to a lower rate of arthrofibrosis after total knee arthroplasty
J Arthroplasty
(2017)
D.F. Dalury et al.
Why are total knee arthroplasties being revised?
J Arthroplasty
(2013)
R.K. Elmallah et al.
Can we really feel a balanced total knee arthroplasty
J Arthroplasty
(2016)

S.M. Kurtz et al.

Impact of the economic downturn on total joint replacement demand in the United States: updated projections to 2021

J Bone Joint Surg Am

(2014)

R.B. Bourne et al.

Patient satisfaction after total knee arthroplasty: who is satisfied and who is not?

Clin Orthop Relat Res

(2010)

G.R. Scuderi et al.

The new knee society scoring system

Clin Orthop Relat Res

(2012)

S. Cao et al.

Simplified Chinese version of the Forgotten Joint Score (FJS) for patients who underwent joint arthroplasty: cross-cultural adaptation and validation

J Orthop Surg Res

(2017)

D.F. Hamilton et al.

Validation of the English language Forgotten Joint Score-12 as an outcome measure for total hip and knee arthroplasty in a British population

Bone Joint J

(2017)

Cited by (61)

Improved Clinical Outcomes With Dynamic, Force-Controlled, Gap-Balancing in Posterior-Stabilized Total Knee Arthroplasty
2024, Journal of Arthroplasty
Optimal soft-tissue management in total knee arthroplasty (TKA) may reduce symptomatic instability. We hypothesized that TKA outcomes using a computer-assisted dynamic ligament balancer that acquires medial and lateral gap sizes throughout the motion arc would show improved Knee Society Scores (KSS) compared to TKAs done with a traditional tensioner at 0 and 90°. We also sought to quantify the degree to which the planned femoral rotation chosen to optimize medio-lateral balance throughout the arc of motion deviated from the femoral rotation needed to achieve a rectangular flexion gap at 90° alone.
Baseline demographics, clinical outcomes, KSSs, and femoral rotations were compared in 100 consecutive, computer-assisted TKAs done with the balancer (balancer group) to the immediately prior 100 consecutive computer-assisted TKAs done without the balancer (control group). Minimum follow-up was 13 months and all patients had osteoarthritis. Mean knee motion did not differ preoperatively (110.1 ± 13.6° balancer, 110.4 ± 12.5° control, P = .44) or postoperatively (119.1 ± 10.3° balancer, 118.8 ± 10.9° control, P = .42). Tourniquet times did not differ (93.1 ± 13.0 minutes balancer, 90.7 ± 13.0 minutes control, P = .13). Postoperative length of stay differed (40.2 ± 20.9 hours balancer, 49.0 ± 18.3 hours control, P = .0009). There were 14 readmissions (7 balancer, 7 control), 11 adverse events (4 balancer, 7 control), and 3 manipulations (1 balancer, 2 control). The cohorts were compared using Student’s t-tests, Shapiro-Wilk normalities, Wilcoxon rank-sums, and multivariable logistic regression analyses.
Postoperative KSS improvements were higher in the balancer group (P < .0001). In multivariable regression analyses, the balancer group experienced 7 ± 2 point improvement in KSS Knee scores (P < .0001) and 4 ± 2 point improvement in KSS Function scores (P = .040) compared to the control group.
The statistically and clinically significant improvements in postoperative KSS demonstrated in the balancer cohort are likely driven by improved stability throughout the motion arc. Further study is warranted to evaluate replicability by non-design surgeons.
SMART (self- monitoring analysis and reporting technology) and sensor based technology applications in trauma and orthopaedic surgery
2023, Journal of Orthopaedics
Innovations in implant designs and computer technology have led to the development of smart implants and prostheses in the field of orthopedics and trauma. Sensor-guided devices enable close monitoring of physical, chemical and biological environment around the implants, which has been purported to meliorate the intra-operative precision and post-operative surveillance of patients.
We evaluate the current applications of sensor-based technology in the management of patients with a spectrum of musculoskeletal conditions.
A thorough search of literature was performed on May 1, 2023, using the 5 databases (Embase, PubMed, Google Scholar, Cochrane Library and Web of Science) in order to identify suitable studies published between 2000 and 2023. All the studies which reported on SMART implants and Sensor based technology in the diverse sub-specialties of orthopedics like trauma, arthroplasty, spine surgery, infections, arthroscopy or sports medicine and paediatric orthopedics were considered. The keywords used for the search included ‘Sensor technology’, ‘SMART implant’ and “Orthopedics”.
Thirty articles were considered for this narrative review. A generation of SMART implants has been developed due to advancements in the microchip technology. Sensor based technology has been utilised in various subspecialties of arthroplasty (in assessing ligament balancing intra-operatively; or prosthetic loosening and gait analysis during follow-up), trauma surgery (as SMART instruments intra-operatively; or in the assessment of bone healing, distraction osteogenesis and functional recovery during follow-up), spine surgery (identification and protection of neural elements from iatrogenic injuries intra-operatively; and assessment of fusion across the instrumented levels during follow-up), paediatric orthopedics (compliance assessment for foot abduction orthosis in congenital talipes equinovarus), infection (monitoring of infection and biofilm formation), rehabilitation (gait analysis) and sports medicine (rotational stability and ligament compliance in patients with ligament injuries or reconstruction).
SMART implants and Sensor based technology have applications in the surgical planning, intra-operative performance, post-operative monitoring and patient surveillance diverse subspecialties of orthopedics and trauma. Future research in newer designs, cost-effective SMART implants and refinement of Sensor based technology will enhance Patient Related Outcome Measures (PROMs).
Laxity, Balance, and Alignment of a Simulated Kinematic Alignment Total Knee Arthroplasty
2023, Arthroplasty Today
Kinematic alignment (KA) and related personalized alignment strategies in total knee arthroplasty (TKA) target restoration of native joint line obliquity and alignment. In practice, deviations from exact restoration of the prearthritic joint surface are tolerated for either the femur or tibia to achieve ligamentous balance. It remains unknown what laxity, balance, and alignment would result if a pure resurfacing of both femur and tibia were performed in a KA TKA technique.
We used data from 382 robot-assisted TKA performed with a digital joint tensioner to simulate TKA with a pure resurfacing KA technique for both femur and tibia. All knees had the posterior cruciate ligament retained. Knees were subdivided into 4 groups based on preoperative coronal alignment: valgus, neutral, varus, and high varus. Medial and lateral laxity in extension and flexion, balance in extension and flexion, and coronal plane alignment were compared between groups using analysis of variance testing.
In simulated pure resurfacing KA TKA across a range of preoperative coronal plane deformities, only 11%-31% of knees would have mediolateral extension ligament balance within ±1 mm, and 20%-41% would have a medial flexion gap that is looser than the lateral flexion gap. Over 45% of knees would have coronal hip-knee-ankle angle >3 degrees from mechanical neutral.
In simulations of pure resurfacing KA TKA, there was wide variability in the resulting laxity and alignment outcomes. Most knees had alignment and balance outcomes outside of normally accepted ranges. Techniques that deviate from pure resurfacing in order to achieve balance appear favorable.
Medial Varus Proximal Tibial Resection is Superior to Pie-Crusting of the Medial Collateral Ligament During Primary Total Knee Arthroplasty
2023, Journal of Arthroplasty
Medial varus proximal tibial (MPT) resection or soft tissue releases (STRs) of the medial collateral ligament (MCL) in the form of pie-crusting can be performed to achieve a balanced knee in a varus deformity. Studies comparing the 2 modalities have not been addressed within the literature. Therefore, the aims of this study were to assess the following: (1) compartmental changes between the 2 methods and (2) changes in patient-reported outcome measurements.
Using our institution’s total joint arthroplasty registry, patients who underwent primary total knee arthroplasty from January 1, 2017, to December 31, 2019, were identified. The MPT resection and STR patients were 1:1 matched with baseline parameters yielding 196 patients. Outcomes of interest included: changes in compartmental pressures at 10, 45, and 90° degrees and change to the Short-Form 12, Western Ontario and McMaster Universities Osteoarthritis Index, and Forgotten Joint Scores (FJSs) at the 2-year follow-up period. A P value less than .05 was used as our threshold for statistical difference.
The MPT resection led to significant reductions in compartmental pressures at 10° [43 versus 19 pounds (lbs.), P < .0001], 45° (43 versus 27 lbs., P < .0001), and 90° degrees (27 versus 16 lbs., P < .0001) compared to STR. MPT resection also had significantly improved Short-Form 12 (47 versus 38, P < .0001), Western Ontario and McMaster Universities Osteoarthritis Index (9 versus 21, P < .0001), and Forgotten Joint Score (79 versus 68, P = .005).
Bone modification was superior to pie-crusting of the MCL in achieving consistent pressure balancing and improved outcomes. The investigation can guide surgeons on the preferred method to achieve a well-balanced knee.
Collateral Ligament Tension and Balance Alone Does Not Ensure Improved Outcome After Total Knee Arthroplasty
2023, Journal of Arthroplasty
It is hypothesized that suboptimal soft tissue and collateral ligament balance is a cause of patient dissatisfaction following total knee arthroplasty (TKA). This analysis examined the association between compartment pressures during TKA and patient-reported outcome measurements (PROMs).
This single-institution, retrospective cohort study of prospectively collected compartment pressure data measured during TKA comprised 145 patients who underwent surgery between 2015 and 2021 and completed 1-year follow-up PROMs. The primary outcome included pressures, in pounds (lbs), of the medial and lateral compartments in extension (5°), mid-flexion (45°), and flexion (90°), and associated PROMs. The difference been the 1-year and preoperative PROMs was used to separate the top 25% from the bottom 75% performers. Pressures were compared using Student's T-tests and multivariate linear regressions, while controlling for preoperative deformity. A subgroup analysis of the most popular implant was performed.
Higher medial compartment pressures were seen in our total cohort (Knee Society Score (KSS) mid-flexion 24 versus 18 lbs, P = .03, flexion 24 versus 17 lbs P = .01) and within our subgroup analysis (Short form- Mental (SF-M) extension 32 versus 21 lbs P = .01, KSS mid-flexion 27 versus 16 lbs P = .005, extension 31 versus 20 lbs P = .003). This trend persisted in the subgroup analysis when controlling for preoperative deformity (KSS extension +16.22 lbs P ≤ .001, mid-flexion +17.6 lbs. P = .001, and flexion +9.2 lbs, P = .005).
Several groups demonstrated higher medial versus lateral pressures. However, this pattern was not consistent across PROMs, suggesting that compartment pressures at the time of TKA are an important factor but not the sole predictor of patient satisfaction.
What is the Value of a Balanced Total Knee Arthroplasty? Getting It Right the First Time
2023, Journal of Arthroplasty
Instability is a leading cause of early failure following total knee arthroplasty (TKA). Enabling technologies can improve accuracy, but their clinical value remains undetermined. The purpose of this study was to determine the value of achieving a balanced knee joint at the time of TKA.
A Markov model was developed to determine the value from reduced revisions and improved outcomes associated with TKA joint balance. Patients were modeled for the first 5 years following TKA. The threshold to determine cost-effectiveness was set at an incremental cost effectiveness ratio of $50,000/quality-adjusted life year (QALY). A sensitivity analysis was performed to evaluate the influence of QALY improvement (ΔQALY) and Revision Rate Reduction on additional value generated compared to a conventional TKA cohort. The impact of each variable was evaluated by iterating over a range of ΔQALY (0 to 0.046) and Revision Rate Reduction (0% to 30%) and calculating the value generated while satisfying the incremental cost effectiveness ratio threshold. Finally, the impact of surgeon volume on these outcomes was analyzed.
The total value of a balanced knee for the first 5 years was $8,750, $6,575, and $4,417 per case, for low, medium, and high-volume surgeons, respectively. Change in QALY accounted for greater than 90% of the value gain with a reduction in revisions making up the rest in all scenarios. The economic contribution of revision reduction was relatively constant regardless of surgeon volume ($500/case).
Achieving a balanced knee had the greatest impact on ΔQALY over early revision rate. These results can help assign value to enabling technologies with joint balancing capabilities.

View all citing articles on Scopus

: One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to https://doi.org/10.1016/j.arth.2019.03.036.

View full text

Primary ArthroplastyAre Patients More Satisfied With a Balanced Total Knee Arthroplasty?

Abstract

Background

Methods

Results

Conclusion

Section snippets

Patient Population

Potential Confounding Factors

Discussion

Acknowledgements

J Arthroplasty

J Arthroplasty

J Arthroplasty

J Arthroplasty

J Arthroplasty

J Arthroplasty

J Arthroplasty

J Arthroplasty

J Arthroplasty

J Arthroplasty

Impact of the economic downturn on total joint replacement demand in the United States: updated projections to 2021

J Bone Joint Surg Am

Patient satisfaction after total knee arthroplasty: who is satisfied and who is not?

Clin Orthop Relat Res

The new knee society scoring system

Clin Orthop Relat Res

Simplified Chinese version of the Forgotten Joint Score (FJS) for patients who underwent joint arthroplasty: cross-cultural adaptation and validation

J Orthop Surg Res

Validation of the English language Forgotten Joint Score-12 as an outcome measure for total hip and knee arthroplasty in a British population

Bone Joint J

Primary Arthroplasty
Are Patients More Satisfied With a Balanced Total Knee Arthroplasty?