Influence of limb alignment and prosthetic orientation on patient-reported clinical outcomes in total knee arthroplasty

Evaluating the Usability and Equivalence of Electronic Patient-Reported Outcome Measures for Individuals with a Lower-Limb Amputation

Introduction

Electronic versions of patient-reported outcome measures (PROMs) seem to have a clear administrative logging advantage to traditional paper versions. However, most of them have not been formally evaluated for their suitability to replace paper outcome measures for assessment of individuals with lower-limb amputations. The aim of this study is to examine the usability and equivalence of electronic to paper versions of PROMs suitable for use in prosthetic clinical care and research for persons with lower-limb loss.

Methods

In this cross-sectional study, 10 participants remotely completed the following PROMs online and then on paper: Orthotic and Prosthetic User Survey (OPUS), Modified Falls Efficacy Scale (MFES), Prosthetic Evaluation Questionnaire (PEQ), Patient Health Questionnaire–9 (PHQ-9), and Community Participation Indicators (CPI). Participants also answered open-ended and standardized questions regarding the usability of the electronic surveys. Wilcoxon signed rank tests, comparisons to minimum detectable change, intraclass correlation coefficients, and Bland-Altman plots were used to evaluate differences between the two survey versions, meaningful changes in scores, reliability, and systematic biases, respectively.

Results

Electronic surveys had fewer missing or ambiguous responses than paper surveys; however, the PEQ Social Burdens subscale could not be evaluated due to error in the creation of the electronic survey. No significant differences were found between scores of the two versions for any of the measures, but multiple participants had meaningful changes in the Appearance and Sounds PEQ subscales. All measures demonstrated acceptable reliability between versions, except the Appearance, Perceived Response, and Sounds subscales of the PEQ. No systematic biases in scores or usability concerns were found for any measures.

Conclusions

This study analysis showed that most of the electronic PROMs studied are easily used and demonstrate equivalence to the paper versions. However, the PEQ Appearance, Perceived Response, Sounds, and Social Burden subscales require further evaluation.

Clinical Relevance

Except for the PEQ, electronic versions of the PROMs in this study can likely be used interchangeably with paper versions among individuals with lower-limb loss.

Mechanical alignment tolerance of a cruciate-retaining knee prosthesis under gait loading—A finite element analysis

Component alignment is one of the most crucial factors affecting total knee arthroplasty’s clinical outcome and survival. This study aimed to investigate how coronal, sagittal, and transverse malalignment affects the mechanical behavior of the tibial insert and to determine a suitable alignment tolerance on the coronal, sagittal, and transverse planes. A finite element model of a cruciate-retaining knee prosthesis was assembled with different joint alignments (−10°, −7°, −5°, −3°, 0°, 3°, 5°, 7°, 10°) to assess the effect of malalignment under gait loading. The results showed that varus or valgus, extension, internal rotation, and excessive external rotation malalignments increased the maximum Von Mises stress and contact pressure on the tibial insert. The mechanical alignment tolerance of the studied prosthesis on the coronal, sagittal, and transverse planes was 3° varus to 3° valgus, 0°–10° flexion, and 0°–5° external rotation, respectively. This study suggests that each prosthesis should include a tolerance range for the joint alignment angle on the three planes, which may be used during surgical planning.

Functional outcomes of residual varus alignment versus mechanical alignment in total knee arthroplasty for varus osteoarthritis: A preferred reporting items for systematic reviews and meta-analyses-compliant meta-analysis

BACKGROUND

One in five patients with mechanical alignment (MA) after total knee arthroplasty (TKA) was reportedly dissatisfied. As constitutional varus knees are common, restoring the patients' natural residual varus (RV) alignment is as an appealing alternative to neutral MA. This meta-analysis aimed to evaluate the effects of RV alignment on the functional outcomes compared with those of MA in TKA for the knees with varus osteoarthritis.

METHODS

The MEDLINE/PubMed, Cochrane Library, and EMBASE databases were comprehensively searched for papers comparing the effects of RV alignment and MA on the functional outcomes from the time of inception of the databases to July 2020. Studies comparing the functional outcomes in the knees subjected to TKA with RV alignment (case group) and MA (control group) were included. The Knee Society knee and functional scores (KSKS and KSFS, respectively), Western Ontario and McMaster University Osteoarthritis Index (WOMAC), Oxford knee score (OKS), and forgotten joint score (FJS) were compared.

RESULTS

Seven studies were finally included; all studies showed a low risk of selection bias and provided detailed demographic data. The pooled mean difference in the KSKS (0.06, 95% confidence interval [CI]: -0.14 to 0.27; p = 0.55) and KSFS (0.08, 95% CI: -0.08 to 0.35; p = 0.56) between RV alignment and MA did not significantly differ. The pooled mean differences in the WOMAC (-0.25, 95% CI: -0.57 to 0.07; p = 0.12), OKS (0.06, 95% CI: -0.15 to 0.27; p = 0.56), and FJS (0.41, 95% CI: -0.18 to 1.00; p = 0.18) between the groups were not significant.

CONCLUSION

The beneficial effects of RV alignment on the functional outcomes are limited compared to those of MA in TKA for varus osteoarthritis to date. Currently, TKA with neutral MA should be considered as the gold standard.

Varus alignment after total knee arthroplasty results in greater axial rotation during deep knee bend activity

BACKGROUNDS

The correlation between in vivo knee kinematics and alignment has not been fully elucidated. Recently, similar or better clinical outcomes have been reported by restoration of mild varus alignment after total knee arthroplasty for preoperative varus knees. The aim of this study was to evaluate the effect of postoperative alignment on knee kinematics during a deep knee bend activity.

METHODS

In vivo knee kinematics of 36 knees (25 patients) implanted with tri-condylar total knee arthroplasty were analyzed with a three dimensional model fitting approach using fluoroscopy. Under fluoroscopic surveillance, individual video frames were digitized at 30° increments from full extension to maximum flexion. Postoperative coronal and sagittal alignments were assessed using radiographs, and rotational alignment was assessed with computed tomography. Pearson correlation coefficients were calculated to determine the correlations between the alignment data and kinematic factors.

FINDINGS

Correlation analysis showed that coronal alignment was significantly correlated with knee kinematics. The varus alignment of the limb and tibial component led to a greater axial rotation from full extension to maximum flexion and more rotated position in the mid to deep flexion range. Neither the rotational alignment of the femoral nor tibial components showed significant correlation with axial rotation from full extension to maximum flexion.

INTERPRETATION

Varus alignment resulted in greater axial rotation, which could represent near-normal knee kinematics. The current study can be a kinematic rationale reporting similar or better clinical and functional outcomes for the total knee arthroplasty with residual varus alignment.