Date of Award

2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Program

Biomedical Sciences

Track

Neuroscience

Research Advisor

William Mihalko, MD, PhD

Committee

Denis DiAngelo, PhD; Douglas Powell, PhD; Phyllis Richey, PhD; R. Dale, PhD

Keywords

Biomechanics, Implant Designs, Joint Line Obliquity, Stair Negotiation, Surgical Alignment Techniques, Total Knee Arthroplasty

Abstract

Introduction. Total knee arthroplasty (TKA) has advanced over the past two decades from traditional post-operative neutral alignment methods with an overall goal of implant longevity to ones that are more personalized to better replicate individual native knee kinematics. Personalizing TKA knee kinematics to better replicate a patient’s native knee kinematics has evolved in response to a reported 20% dissatisfaction by patients with their TKA. These personalization advancements include innovations in surgical alignment techniques include the kinematic alignment (KA) and joint line obliquity (JLO) restoration, in contrast to the mechanical alignment (MA) technique that places everyone into the same mold. Additionally, implant designs have progressed to asymmetrical condylar geometry that restrict medial compartment anterior-posterior translation, simulating natural knee kinematics better than symmetrical tibial and femoral condylar geometries. This dissertation presents three studies, the first of which examines three-dimensional knee joint moment differences between MA and KA techniques. The second study assesses the impact of JLO restoration on frontal plane lower extremity joint moments. The third study explores how implant designs and surgical alignment techniques influence sagittal plane joint moments and muscle activation patterns during stair negotiation.

Methods. The first aim of this dissertation examined the influence of surgical alignment techniques and restoration of joint line obliquity on knee joint biomechanics. The first study analyzed the surgical alignment techniques (Aim 1, hypothesis 1a), and the second study analyzed the restoration of joint line obliquity (Aim 1, hypothesis 1b). For the first study (Aim 1, hypothesis 1a), a total of 28 patients (14 MA; 14 KA) performed five stair ascent and descent trails. Kinematics and kinetics were recorded using a three-stair instrumented staircase (1000 Hz, AMTI Inc., Watertown, MA) and an 8-camera motion capture system (200 Hz, OptiTrack, NaturalPoint Inc, MA) using an AI-based reconstruction software (Theia Markerless, Inc., Kingston, ON). Visual 3D calculated three-dimensional knee joint moments, and custom software (MATLAB) was used to find peak knee joint moments in each plane. Six independent sample t-tests or Wilcoxon-Signed Rank tests in case of non-normality were conducted to determine the effect of surgical alignment technique (MA and KA) during each task (stair ascent and descent) on independent variables. Cohen’s d was used to quantify effect size magnitude and were interpreted as follows: small, d 0.8. SAS 9.5 software (Version 9.5, SAS Institute Inc., Cary, NC) was used to perform all statistical analyses. The second study (Aim 1, hypothesis 1b) included 52 patients (30 unrestored; 22 restored) who completed ten stair ascent and descent trials. The same data collection setup was used as above for kinematics, kinetics and data analysis on frontal plane lower extremity moments. Independent sample t-tests or Wilcoxon-Signed Rank tests in case of non-normality were conducted to determine the effect of the restoration of JLO (Restored and Unrestored) during each task (stair ascent and descent) on peak frontal plane lower extremity joint moments. Aim 2 quantified the influence of implant designs on knee joint biomechanics during a stair negotiation task. The third study (Aim 2), split a total of 52 patients into four groups based on the surgical alignment technique utilized during surgery (MA or KA), and implant design (Attune, Medacta or Persona) utilized during surgery. These patients had the following implant and surgical techniques: 14 Attune MA, 14 Attune KA, 14 Persona MA, and 10 Medacta KA. Each participant performed five overground walking, stair ascent and stair descent trails. Surface electromyography (EMG, 2000 Hz, Delsys Inc, Natick, MA) was collected from the rectus femoris (RF) and bicep femoris (BF). Sagittal plane lower extremity joint moments were calculated using a six-degree-of-freedom model in Visual 3D (HAS-Motion, Kingston, Ontario, Canada). Peak extension joint moments, EMG mean activation and burst duration were calculated using custom software (MATLAB, MathWorks Inc., Natick, MA). A one-way repeated measures of analysis of variance was used to evaluate the effects of three types of implant designs on sagittal plane moments during stair ascent and descent. In the presence of a significant main effect of implant designs on independent variables was found, a Tukey’s post hoc analysis was conducted. Further, six independent sample t-tests or Wilcoxon-Signed Rank tests in case of non-normality were conducted to determine the effect of surgical alignment technique during each task on independent variables.

Results. The first study found patients displaying a more personalized knee joint alignment (KA) demonstrated greater three-dimensional knee joint moments to negotiate the stairs (Aim 1, hypothesis 1a). The second study found the restoration of joint line obliquity from the surgical alignment did not significantly influence frontal plane lower extremity joint moments (Aim 1, hypothesis 1b). The third study found surgical alignment techniques and not implant designs influenced knee extension joint moments to negotiate the stairs, where the KA technique resulted in greater knee joint extension moments compared to the MA technique to negotiate the stairs. Surgical alignment techniques influenced knee flexor activations, where the MA technique resulted in greater knee flexor activation patterns to descend the stairs. Implant designs influenced the knee flexor mean activation to descend the stairs where potentially greater anterior-posterior translation restriction inherent within the implant design led to reduced knee flexor average activation (Aim 2).

Conclusion. Aim 1, hypothesis 1a demonstrated that that the KA technique exhibited greater three-dimensional peak knee joint moments to negotiate the stairs. Due to the lack of difference in joint line, reduced trunk lean and preserving soft tissue structures in the KA technique, potentially the KA technique allows patients to move within the frontal plane instead of an avoidance strategy shown in the MA technique. Aim 1, hypothesis 1b indicated that JLO restoration does not affect frontal plane joint moments during stair negotiation. Thus, JLO restoration may not impact patient satisfaction post-surgery. Aim 2 revealed that while surgical alignment techniques affect sagittal plane joint moments, implant designs do not. Specifically, the KA TKA technique led to greater knee extension moments compared to the MA TKA technique. Implant designs influenced knee flexor activation where less inherent mechanical AP stability designs require greater knee flexor activation to provide knee joint stability.

Declaration of Authorship

Declaration of Authorship is included in the supplemental files.

ORCID

0000-0002-4054-5027

DOI

10.21007/etd.cghs.2024.0677

Additional Files
2024-019-Nelson-Tranum-DOA.pdf (170 kB)
Declaration of Authorship
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