Elsevier

The Journal of Arthroplasty

Volume 32, Issue 8, August 2017, Pages 2411-2416
The Journal of Arthroplasty

Primary Arthroplasty
Do Medial Pivot Kinematics Correlate With Patient-Reported Outcomes After Total Knee Arthroplasty?

https://doi.org/10.1016/j.arth.2017.03.019Get rights and content

Abstract

Background

Many total knee arthroplasty (TKA) implants are designed to facilitate a medial pivot kinematic pattern. The purpose of this study was to determine whether intraoperative medial pivot kinematic patterns are associated with improved patient outcomes.

Methods

A retrospective review of consecutive primary TKAs was performed. Sensor-embedded tibial trials determined kinematic patterns intraoperatively. The center of rotation (COR) was identified from 0° to 90° and from 0° to terminal flexion, and designated medial-pivot or non-medial pivot based on accepted criteria. Patient-reported outcomes were measured preoperatively and at minimum one-year follow-up.

Results

The analysis cohort consisted of 141 TKAs. Mean age and median BMI were 63.7 years and 33.8 kg/m2, respectively. Forty-percent of TKAs demonstrated a medial pivot kinematic pattern intraoperatively. A medial pivot pattern was more common with posterior cruciate-retaining (CR) and posterior cruciate-substituting/anterior lipped (CS) implants when compared to posterior stabilized (PS) TKAs (P ≤.0150). Regardless of bearing type, minimum one-year Knee Society scores and UCLA activity level did not significantly differ based on medial vs non-medial pivot patterns (P ≥.292). For patients with posterior cruciate-sacrificing implants, there were trends for greater median improvement in Knee Society objective (46 vs 31.5 points, P =.057) and satisfaction (23 vs 14 points, P =.067) scores in medial pivot knees.

Conclusion

A medial pivot pattern may not significantly govern clinical success after TKA based on intraoperative kinematics and modern outcome measures. Further research is warranted to determine if a particular kinematic pattern promotes optimal clinical outcomes.

Section snippets

Methods

After institutional review board approval was obtained, a retrospective review of a prospectively collected database of consecutive primary TKAs was undertaken. Procedures were performed between April 2013 and April 2014 by 2 board-certified arthroplasty surgeons at a single institution. Of the original 203 TKAs, 53 were excluded due to unavailability of the required size of the VERASENSE (OrthoSensor, Sunrise, FL) device (31), device malfunction (5), atypical hardware creating additional

Medial and Nonmedial Pivot Based on the Average COR From 0° to 90° Flexion

Pivot type could not be determined based on the COR from 0° to 90° for the 2 TKAs. For the remaining 139 knees, the average COR in the 90° flexion arc ranged from −324.03 to 605.81 mm with positive signifying the medial side. Medial pivot knees comprised 40% (55 of 139) of the total sample.

Pivot classification did not differ based on patient gender (75% female, χ2 = 0.739, P = .428), median BMI (32.9 kg/m2, W = 3723.5, P = .587), or median length of follow-up (19.6 months, W = 3947.5, P =

Discussion

TKA is a successful procedure which benefits thousands of patients annually. With the aging baby boomer population and an increase in younger patients indicated for surgery, the number of primary and revision TKAs are expected to drastically increase within the next 20 years [28]. Although TKA provides substantial benefits in terms of pain control and function to the majority of patients, our profession has been unable to replicate the nearly universal satisfaction rates seen with total hip

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    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 http://dx.doi.org/10.1016/j.arth.2017.03.019.

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