Implant design affects walking and stair navigation after total knee arthroplasty: a double-blinded randomised controlled trial

Muscle Activity and Biomechanics While Descending a Staircase After Total Knee Arthroplasty: A Study Comparing Different Posterior Stabilized and Medial Ball-and-Socket Designs

BACKGROUND

Many patients report more difficulty when descending stairs compared to level walking after total knee arthroplasty (TKA). Different implant designs can affect knee biomechanics and muscle activity during gait, but their effect during stair descent is unclear. The purpose of this study was to evaluate knee biomechanics and muscle activations of quadriceps, hamstrings, and gastrocnemius muscles during a stair descent task in patients who underwent TKA with either a posterior stabilized (PS) or medial ball-and-socket (MBS) implant and to compare them to a group of healthy controls.

METHODS

There were 28 TKA patients who were randomized to either an MBS (n = 14) or PS (n = 14) implant and were compared with 14 controls. Patients visited the biomechanics lab approximately 12 months after TKA, where knee biomechanics and muscle activity were measured as they descended a 3-step staircase.

RESULTS

Compared to the MBS and control groups, the PS group descended the stairs with a reduced knee flexion angle and greater hamstring muscle activation throughout single limb support. Knee joint moments and power were similar between the MBS and PS groups, but neither reached the level of the control group.

CONCLUSIONS

Lower knee flexion angles and increased hamstring muscle activity indicated that the PS group descended the stairs with a stiffer knee gait pattern than the MBS group. The MBS implant design may provide additional stability as patients require less muscle activity than the PS group.

Effect of single-radius design on in vivo kinematics during stair activities after total knee arthroplasty

BACKGROUND

The single-radius design is one of the major total knee arthroplasty (TKA) designs and widely used all over the world. The objective of this study was to compare in vivo kinematics between the anteroposterior (AP) single-radius design with mediolateral (ML) single-radius (Non Restricted Geometry; NRG) and ML dual-radius (Triathlon) during stair activities.

METHODS

A total of 21 knees in 18 patients (NRG group: 10 knees in 7 patients, Triathlon group: 11 knees in 11 patients) with a clinically successful posterior stabilized TKA were examined. Under fluoroscopic surveillance, each patient performed stair ascending and descending motions. In vivo kinematics were analyzed using 2D/3D registration technique. The knee flexion angle, rotation angle, varus-valgus angle, AP translation of the femorotibial contact point for both the medial and lateral sides of the knee, and post-cam engagement were evaluated.

RESULTS

There were no significant differences between the two groups in rotation angle and AP translation at each flexion angle. Examining the varus-valgus angle, the NRG group showed varus position at an early flexion angle during both stair activities.Post-cam engagement was observed in both groups during both stair activities. The mean flexion angle of engagement in the NRG group, the post of which was located anterior to the Triathlon, was larger than that in the Triathlon group during both stair activities.

CONCLUSION

Despite the same AP single-radius TKA, ML single-radius might affect varus motion at an early flexion angle.

Development of a three-dimensional muscle-driven lower limb model developed using an improved CFD-FE method

Analysis of the musculoskeletal movements (gait analysis) is needed in many scenarios. The in vivo method has some difficulties. For example, recruiting human subjects for the gait analysis is challenging due to many issues. In addition, when plenty of subjects are required, the follow-up experiments take a long period and the dropout of subjects always occurs. An efficient and reliable in silico simulation platform for gait analysis has been desired for a long time. Therefore, a technique using three-dimensional (3D) muscle modeling to drive the 3D musculoskeletal model was developed and the application of the technique in the simulation of lower limb movements was demonstrated. A finite element model of the lower limb with anatomically high fidelity was developed from the MRI data, where the main muscles, the bones, the subcutaneous tissues, and the skin were reconstructed. To simulate the active behavior of 3D muscles, an active, fiber-reinforced hyperelastic muscle model was developed using the user-defined material (VUMAT) model. Two typical movements, that is, hip abduction and knee lifting, were simulated by activating the responsible muscles. The results show that it is reasonable to use the improved CFD-FE method proposed in the present study to simulate the active contraction of the muscle, and it is feasible to simulate the movements by activating the relevant muscles. The results from the present technique closely match the physiological scenario and thus the technique developed has a great potential to be used in the in silico human simulation platform for many purposes.

Robust Randomized Controlled Data Is Lacking in Total Joint Arthroplasty

INTRODUCTION

 Randomized controlled trials (RCTs)are regarded as highest level of scientific evidence. There is belief that while prospective randomized control trials (PRCTs) are the gold standard for evaluating efficacy of interventions, there are very few conducted on lower extremity joint arthroplasty. However, there was a more than adequate amount (n=197) of published RCTs in knee arthroplasty during the 2021 calendar year. Therefore, we studied RCTs on knee arthroplasties for 2021 and assessed them for overall study topic reasons (i.e., devices as well as prostheses, rehabilitation, pain control, blood loss [tranexamic acid], and other), which were then subcategorized by: (1) country of origin; (2) sample size; and (3)whether or not they were follow-up studies. After this, we specifically focused on the studies (n=26) concerning devices or prostheses.

METHODS

 A search of PubMed on "knee arthroplasty" specifying "RCT" using their search function and dates between January 1, 2021 to December 24, 2021 resulted in the analyzed reports. A total of 17.3% reports analyzed rehabilitation methods while 28.4% studied pain control. A total of 20.3% examined blood loss topics and 20.8% investigated other topics.

RESULTS

 We found that 26 studies (13.2%) involved prosthetic design and implantation. Overall, only 15% knee arthroplasty RCTs were conducted in the United States, the mean total final sample size was 133±146 patients, and 7% were follow-up studies. None of the prostheses studies were performed in the United States, and the mean total final sample size of all of these studies was 86±54 patients, and 23% were follow-up studies. Total knee arthroplasty prospective RCTs were not performed in the United States.

CONCLUSION

 The authors believe that other study designs, such as database or registry analyses, are also appropriate in this rapidly advancing field of joint arthroplasty for the continuing evaluation and approval of new prostheses and techniques, while we await more PRCTs in our field.

Dynamic stability during stair negotiation after total knee arthroplasty

BACKGROUND

The assessment of dynamic stability is crucial for the prevention of falls in the elderly and people with functional impairments. Evidence that total knee arthroplasty improves balance in patients with severe osteoarthritis is scarce and no information exists about how the surgery affects dynamic stability during stair negotiation.

METHODS

This study aims to investigate if patients before and one year after surgery are less stable compared to asymptomatic controls. Seventeen control and twenty-seven patient participants with end-stage knee osteoarthritis that were scheduled to undergo unilateral total knee arthroplasty were recruited in this study. Participants' assessment was carried out by means of marker-based optical full-body motion capture with force platforms. The extrapolated Centre of mass and the margin of stability metrics were used to examine dynamic stability during stair ascent and descent.

FINDINGS

Patient participants, during both pre-operative and post-operative assessments, were equally balanced to the asymptomatic controls during stair gait (p > .188). Additionally, the patients' overall stability did not improve significantly one year after arthroplasty surgery (p > .252).

INTERPRETATION

Even if pain from arthritis and fear of falling is decreased following surgery, our results indicate that stability in stair walking in not affected by osteoarthritis and total knee arthroplasty.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02422251.