The effect of knee arthroplasty on balancing ability in response to sudden unidirectional perturbation in the early postoperative period

Changes in Mediolateral Postural Control Mechanisms During Gait After Total Knee Arthroplasty

BACKGROUND

Patients who have total knee arthroplasty (TKA) likely suffer from decreased postural stability because of postoperative changes in musculoskeletal structure and loss of proprioception. The purpose of this experimental biomechanical study was to determine if patients who have TKA improve their dynamic postural control during walking after TKA as compared with before TKA. The secondary purpose was to assess changes in postural control between post-TKA patients and healthy controls.

METHODS

Twenty-three patients who had primary knee osteoarthritis scheduled to undergo unilateral or bilateral TKA were prospectively enrolled. Each patient was tested at 3 months, 6 months, and 12 months after TKA. Ten healthy controls matched for age, sex, and body mass index were selected from a database of previous healthy volunteers without knee osteoarthritis. Ten Vicon cameras and four AMTI force platforms were used to collect the marker and center of pressure (COP) data while participants performed gait.

RESULTS

Initial improvement in the double stance ratio was found by 6 months after TKA compared with before TKA. Patients showed improved postural control as evidenced by a faster mediolateral COP velocity and decreased double stance ratio at 12-month post-TKA compared with pre-TKA (P < .05). However, patients who underwent TKA exhibited limited ability to maintain consistent COP movement during walking with increased variability in COP parameters as compared with controls (P < .05).

CONCLUSION

Patients exhibited improvement in dynamic postural control after TKA with time, but had higher variability in COP parameters during gait than controls. It is possible that therapy aimed to improve proprioceptive balance after TKA may improve dynamic postural control.

Effects of total knee arthroplasty for primary knee osteoarthritis on postural balance: A systematic review

BACKGROUND

Knee osteoarthritis is often related to physical function impairment. Although total knee arthroplasty is considered effective for advanced cases of knee osteoarthritis, its effects on postural balance is a topic of debate.

RESEARCH QUESTION

What are the effects of total knee arthroplasty for primary knee osteoarthritis on postural balance compared to preoperative status and/or to healthy controls?.

METHODS

Longitudinal studies (with more than 1-month follow-up) assessing postural balance measures (either clinical-based such as balance scales or laboratory-based such as postural sway) were considered eligible and selected in a 2-phase process. Six main electronic databases were searched, complemented by 3 grey literature sources. The risk of bias was evaluated using the Joanna Briggs Institute Critical Appraisal Tools.

RESULTS

A total of 19 studies were included for qualitative synthesis, of which 14 had low and 5 had a moderate risk of bias. The follow-up period ranged from 1-24 months. Most studies (n = 11) presented comparisons to preoperative status only. From these, 7 studies reported relevant improvements in postural balance, 2 reported partial improvements, and 2 no improvements. The remaining studies (n = 8) presented comparisons to healthy controls and, although improvements following total knee arthroplasty were consistently observed, only one study reported postural balance measures comparable to that of controls.

CONCLUSIONS

The majority of studies reported relevant improvements (especially in clinical-based measures) compared to preoperative evaluations, although inconsistencies were found possibly due to variability in studies' populations, assessment tools, and follow-up times. Despite this, persistent deficits in postural balance were commonly observed when compared to healthy controls.

SIGNIFICANCE

This evidence synthesis could better inform clinicians and researchers about the therapeutic effects and limitations of total knee arthroplasty concerning postural balance. Standardization of assessment tools is recommended to strengthen the certainty of cumulative evidence.

Response to perturbation during quiet standing resembles delayed state feedback optimized for performance and robustness

Postural sway is a result of a complex action–reaction feedback mechanism generated by the interplay between the environment, the sensory perception, the neural system and the musculation. Postural oscillations are complex, possibly even chaotic. Therefore fitting deterministic models on measured time signals is ambiguous. Here we analyse the response to large enough perturbations during quiet standing such that the resulting responses can clearly be distinguished from the local postural sway. Measurements show that typical responses very closely resemble those of a critically damped oscillator. The recovery dynamics are modelled by an inverted pendulum subject to delayed state feedback and is described in the space of the control parameters. We hypothesize that the control gains are tuned such that (H1) the response is at the border of oscillatory and nonoscillatory motion similarly to the critically damped oscillator; (H2) the response is the fastest possible; (H3) the response is a result of a combined optimization of fast response and robustness to sensory perturbations. Parameter fitting shows that H1 and H3 are accepted while H2 is rejected. Thus, the responses of human postural balance to “large” perturbations matches a delayed feedback mechanism that is optimized for a combination of performance and robustness.

Rolling balance board of adjustable geometry as a tool to assess balancing skill and to estimate reaction time delay

The relation between balancing performance and reaction time is investigated for human subjects balancing on rolling balance board of adjustable physical parameters: adjustable rolling radius R and adjustable board elevation h. A well-defined measure of balancing performance is whether a subject can or cannot balance on balance board with a given geometry (R, h). The balancing ability is linked to the stabilizability of the underlying two-degree-of-freedom mechanical model subject to a delayed proportional-derivative feedback control. Although different sensory perceptions involve different reaction times at different hierarchical feedback loops, their effect is modelled as a single lumped reaction time delay. Stabilizability is investigated in terms of the time delay in the mechanical model: if the delay is larger than a critical value (critical delay), then no stabilizing feedback control exists. Series of balancing trials by 15 human subjects show that it is more difficult to balance on balance board configuration associated with smaller critical delay, than on balance boards associated with larger critical delay. Experiments verify the feature of the mechanical model that a change in the rolling radius R results in larger change in the difficulty of the task than the same change in the board elevation h does. The rolling balance board characterized by the two well-defined parameters R and h can therefore be a useful device to assess human balancing skill and to estimate the corresponding lumped reaction time delay.

A randomized controlled trial assessing the effects of preoperative strengthening plus balance training on balance and functional outcome up to 1 year following total knee replacement

PURPOSE

To investigate the effects of including balance training in a preoperative strengthening intervention on balance and functional outcomes in patients undergoing total knee replacement (TKR) and compare these effects to those induced by preoperative strengthening and no intervention.

METHODS

Eighty-two subjects scheduled for TKR were randomly allocated into the strengthening (ST, n = 28) group: a preoperative lower limb strengthening intervention; the strengthening + balance (ST + B, n = 28) group: same intervention augmented with balance training; and the control group (n = 26). The Berg Balance Scale (BBS) and the function in daily living subscale of the Knee Injury and Osteoarthritis Outcome Score (KOOS-ADL) were the primary outcomes. The secondary measures included balance and mobility, self-reported status, and knee function. The outcomes were assessed at baseline, 1 week before surgery, and 2, (primary endpoint), 6 and 52 weeks after surgery.

RESULTS

Compared with the controls, the participants in the ST and ST + B groups presented significant improvements from baseline to the end of the preoperative intervention in BBS (p = 0.005) and KOOS-ADL (p < 0.001). At 6 weeks post-surgery, the knee extensor strength values were similar in the two treatment groups and significantly higher than that in the controls. Overall, the participant outcomes in all groups stabilized at 1 year after surgery.

CONCLUSION

A preoperative strengthening intervention, regardless of whether it is complemented with balance training, enhances strength but not balance or functional outcomes at 6 weeks after surgery. Patients are expected to present similar performance at 1 year postoperatively, but adequately statistically powered trials are needed to confirm the findings.

LEVEL OF EVIDENCE

II.

TRIAL REGISTRATION

NCT02995668.

Instrumented platforms for balance and proprioceptive assessment in patients with total knee replacement: A systematic review and meta-analysis

BACKGROUND

The functional outcome of total knee replacement (TKR) is usually satisfying. However, patients may show functional limitations for years after surgery, which have been ascribed to impairments in balance and proprioception, mainly during standing tasks. A number of instrumentations and parameters have been used, rising confusion for clinical decisions on the assessment of patients.

RESEARCH QUESTION

Which are the most widespread and consistent procedures to assess balance and proprioception following TKR?

METHODS

A literature review was conducted in Pubmed, PEDro, and Cochrane database. From a total sample of 112 articles, 23 original studies published between 2008 and 2019 met inclusion criteria. The primary outcomes selected were variables related to balance and proprioception assessment in static and dynamic tasks performed with instrumented platforms. Data from papers using the same instrumentation, on patients with unilateral TKA and at least 12 months postoperatively were synthesized quantitatively in a random effect meta-analysis.

RESULTS

Fourteen articles were appropriate for the review. A large variability was found both in the instrumentation and the parameters used. The Neurocom Balance Master System™ was the most used instrument (four articles). On a total population of 186 patients with unilateral TKR 12 months postoperatively, a low degree of heterogeneity was found adopting the random effect in the four tasks explored (Firm and Foam Surface both with Eyes Open and Eyes Closed).

SIGNIFICANCE

This review found a large variability in the instrumentation used to assess balance and proprioception in patients operated on TKR. The meta-analysis demonstrated that the Neurocom Balance Master System™ for static assessment of balance showed an acceptable consistency and can be considered as a reference for further studies. However, balance and proprioception impairments following TKR have not been widely quantified by means of instrumented platforms. Further research is needed to address this issue, and improve clinical practice.

How proprioception changes before and after total knee arthroplasty: A systematic review

BACKGROUND

Proprioception is one of the most significant factors in balance, joint stability, graceful movement, coordination, and injury prevention. It involves a wide set of receptors located within joints, muscles, and tendons. Given the neurophysiological processes involved in proprioception response are multiple and complex, there is not one single method to measure it. Particularly, proprioception of the knee joint, whether it is healthy, affected by osteoarthritis, or after replacement, is the most investigated by in literature.

RESEARCH QUESTION

This review addresses the analysis of proprioception in the knee joint before and after total knee arthroplasty (TKA). The aim is to obtain an overview of the proprioceptive skills in subjects who suffered from osteoarthritis and were subjected to knee replacement, evaluating changes in proprioception before and after the surgery.

METHODS

The research was conducted within four databases: Web of Science®, PubMed Central®, Cochrane®, and PEDro®, between January 2008 and February 2018. Accurate exclusion criteria and selection strategy were applied to screen the 170 articles found.

RESULTS

Ultimately, 13 papers were fully evaluated and included in this review, divided into two classes: i) works directly measuring proprioception, ii) studies indirectly evaluating proprioception. Contrasting results emerged from the analysis, and no consensus was found in the literature about the improvement or worsening in proprioception before and after TKA.

SIGNIFICANCE

Since currently there is high variability in methods, protocol and parameters used to evaluate knee proprioception, further investigations based on a consistent dataset, a well-defined protocol, measurable outcomes, timeline follow-ups, and rehabilitation programs should be performed in order to obtain reliable results on the effects of TKA on knee proprioception and balance.

Effectiveness and recovery action of a perturbation balance test - a comparison of single-leg and bipedal stances

Dynamic balancing abilities can be assessed with perturbation tests. The present study examined the effectiveness of balancing (damping ratio) and the recovery action (directional ratio) in bipedal and dominant single-leg stance in the young population. Twenty-four healthy young adult participants completed unidirectional lateral perturbations successfully using a Posturomed© platform (Haider Bioswing, Germany). Single-leg stances had similar damping scores (p = 0.551) to and lower directional ratio values (p = 0.002) than bipedal recoveries. This shows that different recovery actions can achieve similar effectiveness in the two stances. A test evaluation methodology that simultaneously utilises performance and motion characteristic parameters was demonstrated.