Comparison of the Radiologic, Morphometric, and Clinical Outcomes between Kinematically and Mechanically Aligned Total Knee Arthroplasty: A Propensity Matching Study

Sparse and inconsistent reporting of pre- and post-operative radiographic angles of total knee arthroplasty using true unrestricted kinematic alignment: An umbrella review and secondary meta-analysis

PURPOSE

To identify, synthesise and critically appraise findings of systematic reviews and meta-analyses on pre- and post-operative radiographic angles (lateral distal femoral angle [LDFA], medial proximal tibial angle [MPTA] and hip-knee-ankle [HKA] angle) of unrestricted kinematic alignment versus mechanical alignment in total knee arthroplasty (TKA).

METHODS

Two authors searched MEDLINE, EMBASE and Epistemonikos for systematic reviews, with or without meta-analyses, that reported on TKA outcomes using unrestricted kinematic alignment. The methodological quality of the included systematic reviews and meta-analyses was independently assessed using A MeaSurement Tool to Assess systematic Reviews (AMSTAR-2). The effect size with its 95% confidence interval (CI) for radiographic angles was extracted from the systematic reviews and meta-analyses. The characteristics of clinical studies included in systematic reviews were listed and tabulated. Pre- and post-operative MPTA, LDFA and HKA angles were summarised using meta-analytic random-effects models.

RESULTS

Nineteen records were eligible for data extraction. Systematic reviews and meta-analyses included 44 clinical studies, of which 31 were on unrestricted kinematic alignment and 13 were on restricted versions of kinematic alignment. None of the included systematic reviews or meta-analyses fulfiled all seven critical AMSTAR-2 domains. Few comparative studies reported both pre- and post-operative angles (LDFA, n = 3; MPTA, n = 4; and HKA angle, n = 10). Mean pre- and post-operative LDFAs were 88.0° (range, 83-94°) and 88.0° (range, 80-96°) for the kinematic alignment group, and 88.2° (range, 83-95°) and 90.2° (range, 84-97°) for the mechanical alignment group. Mean pre- and post-operative MPTAs were 86.0° (range, 78-93°) and 87.1° (range, 78-94°) for the kinematic alignment group and 86.4° (range, 77-94°) and 89.6° (range, 84-95°) for the mechanical alignment group. Mean pre- and post-operative HKA angles were -3.3° (range, -24° to 24°) and -0.3° (range, -10° to 8°) for the kinematic alignment group and -6.9° (range, -25° to 7°) and -0.9° (range, -8° to 7°) for the mechanical alignment group.

CONCLUSION

Most systematic reviews and meta-analyses that report outcomes of TKA using kinematic alignment do not distinguish between the different versions of kinematic alignment. The clinical studies included in systematic reviews are limited and inconsistent in their reporting of radiographic angles. Different alignment strategies are often grouped under the umbrella term of kinematic alignment, which contributes to conflicting reports, confusion and unresolved questions regarding the efficacy of true unrestricted kinematic alignment.

LEVEL OF EVIDENCE

Level IV.

Kinematic alignment adequately restores trochlear anatomy, patellar kinematics and kinetics in total knee arthroplasty: A systematic review

PURPOSE

Patellofemoral pain, maltracking and instability remain common and challenging complications after total knee arthroplasty. Controversy exists regarding the effect of kinematic alignment on the patellofemoral joint, as it generally leads to more femoral component valgus and internal rotation compared to mechanical alignment. The aim of this systematic review is to thoroughly examine the influence of kinematic alignment on the third space.

METHODS

A systematic search of the Pubmed, Cochrane and Web of Science databases was performed to screen for relevant articles published before 7 April 2024. This led to the final inclusion of 42 articles: 2 cadaveric, 9 radiographic, 12 computer simulation and 19 clinical studies. The risk of bias was evaluated with the risk of bias in non-randomised studies - of interventions tool as the lowest level of evidence of the included clinical studies was IV. The effects of kinematic alignment on patellar kinematics and kinetics, trochlear anatomy reconstruction and patellofemoral complication rate were investigated.

RESULTS

Kinematic alignment closely restores native patellar kinematics and kinetics, better reproduces native trochlear anatomy than mechanical alignment and leads to a 0%-11.4% incidence of patellofemoral complications. A more valgus joint line of the distal femur can cause lateral trochlear undercoverage and a trochlear angle orientation medial to the quadriceps vector when applying kinematic alignment, both of which can be solved by using an adjusted design with a 20.5° valgus trochlea.

CONCLUSION

Kinematic alignment appears to be a safe strategy for the patellofemoral joint in most knees, provided that certain precautions are taken to minimize the risk of complications.

LEVEL OF EVIDENCE

Level IV clinical studies, in vitro research.

Bi-cruciate stabilized total knee arthroplasty restores the native knee alignments better than conventional posterior stabilized total knee arthroplasty

INTRODUCTION

This study aimed to compare the differences in the radiological, clinical, and functional outcomes and the estimated restoration rate of native knee alignment between total knee arthroplasty (TKA) with bi-cruciate stabilized (BCS) and posterior stabilized (PS) design.

MATERIALS AND METHODS

This retrospective study included consecutive patients between 2020 and 2021 who underwent TKA. The patients were divided into two groups (group I, Journey II BCS TKA [106 knees]; group II, Persona PS TKA [106 knees]) after 1:1 propensity score matching. We assessed the radiologic parameters in the coronal (constitutional hip-knee-ankle angle [aHKA] and joint line obliquity [JLO]), sagittal, and axial planes. The femoral roll-back, clinical, and functional outcomes were evaluated. The joint perception was evaluated using the forgotten joint score (FJS).

RESULTS

Group I had a higher restoration rate of aHKA and JLO postoperatively (P = 0.039 and P < 0.001). The changes in the patella tendon angle, posterior overhang of the femur, patella tilt angle, and patella lateral shift in group II were larger than those in group I (P < 0.001). Group I was superior in the range of motion (ROM) (P = 0.004), femoral roll-back (P < 0.001), and FJS (P = 0.021).

CONCLUSIONS

BCS TKA demonstrated better restoration of native knee alignments, including constitutional coronal knee alignment and native sagittal knee alignment, and lesser patella lateral shift than conventional PS TKA. In addition, BCS TKA was superior in ROM, femoral roll-back, and joint perception, which were associated with the degree of restoration of constitutional coronal knee alignment.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Patellofemoral knee pain following total knee arthroplasty. Comparison between adjusted mechanical and inverse restricted kinematic alignment

Objective

The aim of this study was to assess the functional, radiological, and clinical outcomes of patellofemoral joint in patients who had total knee arthroplasty (TKA) without patellar resurfacing for end-stage osteoarthritis using inverse restricted kinematic alignment (irKA) compared to a control group using adjusted mechanical alignment (aMA), both executed with the same implant at the same Institution. The hypothesis was that patients undergoing TKA without patellar resurfacing for end-stage osteoarthritis using irKA would have superior outcomes related to the patellofemoral joint in comparison to a control group using aMA.

Methods

A retrospective examination of registries' prospectively obtained from patients who underwent primary TKA at our Institution between 2016 and 2020 was performed. 40 consecutive patients who underwent TKA implant using irKA were compared to a control group of 80 who had undergone adjusted mechanically-aligned TKA. Groups were matched for age and body mass index. Clinical assessment included Visual Analog Scale (VAS), Knee Osteoarthritis Outcome Score (KOOS), Knee Society Score (KSS), and Kujala Knee Score. Standard weight-bearing anteroposterior and lateral view x-rays were used for radiographic evaluation. Patellar height was assessed using Caton-Deschamps (C-D) and Insall index on lateral view films.

Results

In comparison to pre-operative status, both groups had postoperative improvements in VAS, KOOS, KSS, and Kujala ratings (p<0.001). Regarding Kujala score, there were no statistically significant differences between the groups (p = 0.68). Insall index and C-D index results were not statistically different across groups (p = 0.02 and 0.74 respectively).

Conclusion

Improvements in post-operative clinical and functional outcomes following TKA were associated with either irKA or aMA. There were no discernible changes between the two groups in terms of postoperative patellofemoral discomfort or variations in patellar height.

Additional tying on the adjustable-loop device improves the outcomes of anterior cruciate ligament reconstruction using hamstring autograft

PURPOSE

The purpose of this study was to verify the efficacy of a novel technique for additional tying on the adjustable-loop device to prevent stress concentration on the graft loop end and gradual loop lengthening.

METHODS

A total of 124 patients who underwent anterior cruciate ligament reconstruction using hamstring autografts from 2014 to 2017 were included in this retrospective study. After 1:1 propensity score matching, two groups were formed (group I: 50 patients without tying vs. group II: 50 patients with tying). Anterior laxity was evaluated using side-to-side differences. Tunnel length, loop length, and graft-tunnel gap were measured using follow-up magnetic resonance imaging. The signal-to-noise ratio was calculated at the loop end, loop inner side, tunnel entrance, and graft mid-substance. The clinical outcomes were assessed using the International Knee Documentation Committee score, Lysholm score, pivot shift test, and Lachman test.

RESULTS

The average follow-up period was 63.2 ± 4.8 and 53.8 ± 11.9 months in groups I and II, respectively. Anterior laxity showed that side-to-side differences improved significantly 6 months postoperatively in both the groups. Although the anterior laxity improved in group II (2.9 ± 1.0 to 1.6 ± 0.8, p < 0.001), it deteriorated in group I (2.5 ± 1.5 to 3.3 ± 1.3 mm, p < 0.001) at the final follow-up. The graft-tunnel gap was significantly larger in group I (p < 0.001). The signal-to-noise ratios of the loop end and loop inner side were significantly higher in group I (p < 0.001 and p = 0.020, respectively). The clinical outcomes at the final follow-up were not significantly different between the groups.

CONCLUSION

The additional tying on the adjustable-loop device was not superior to the control group in clinical stability examination or outcome. However, it was effective in anterior laxity measured by stress radiographs, preventing stress on the adjustable-loop device, and gradual graft loop lengthening.

LEVEL OF EVIDENCE

Level III.