Effects of action observation treatment in recovery after total knee replacement: a prospective clinical trial

Abstract

Objective:

We hypothesized that self-administered action observation treatment can increase the effectiveness of inpatient rehabilitation of patients after a primary total knee replacement.

Design:

A pilot randomized controlled trial.

Setting:

Thirty-one inpatients, admitted to our Physical and Rehabilitation Medicine Department.

Subjects:

After a primary total knee replacement were randomly assigned to either an experimental (n=14) or control (n=17) group.

Intervention:

All subjects received conventional physiotherapy and were required to perform additional self-administered exercises explained in a written informative brochure. Subjects in the experimental group were asked to watch a video showing a person exercising whilst the control group watched a nature video without exercises being shown.

Main outcomes measure:

Changes in Visual Analogue Scale, active and passive range of motion of knee, Barthel index, Short Form-36 Health Survey, Tinetti scale, Lequesne index measurements.

Results:

At the end of the intervention period, the increase of the active range of motion over the active flexion and extension in the experimental group was higher than in the control group; the difference between groups was 15.6° (95%CI 5.3–24.8) and 3.4° (95%CI 1.1–5.6), for active flexion and active extension respectively; between-group effect sizes were large at post-treatment period (d>1.3).

Conclusions:

adding action observation training to conventional inpatient physiotherapy is associated with a greater degree of recovery in patients who have undergone a primary total knee replacement.

Keywords

Total knee replacement action observation treatment rehabilitation

Introduction

Postoperative rehabilitation is required for a successful outcome following total knee arthroplasty.¹ Traditionally rehabilitative programs aim to increase range of motion, to strengthen quadriceps, to restore normal gait, and to recover independence in activities of daily living. Exercises, supervised by a physical therapist, should be started as soon as possible.² In the last decade action observation treatment, in addition to conventional physiotherapy has been proposed as a treatment method in rehabilitative medicine. This treatment consists of repetitive visual perception of specific movements of human bodies,³ it aims to facilitate the learning process of a subjects through the observation of a video showing activities or motor tasks performed by another subject.⁴ Motion perception relies on activity in the superior temporal sulcus and in the mirror neuron system; these neurons are activated during certain movements or when the same movement, performed by another subject, is observed.⁵ There is growing evidence of the applicability of action observation training in rehabilitative medicine, indeed it has been applied in the rehabilitation of stroke,^6,7 of Parkinson disease,^3,8 of cerebral palsy⁹ and of aphasia.¹⁰

There is a lack of studies on the efficacy of action observation training in the rehabilitation of orthopedic inpatients, to our knowledge there are only two studies dealing with this topic. Belelli et al.¹¹ found that action observation training could have had some effect on motor recovery of orthopaedic patients after hip and knee arthroplasty while Park et al.¹² applied action observation training in the rehabilitation of post surgical patients finding that action observation treatment could help decreasing pain and contracture of patients who received total knee arthroplasty and in improving their function. Nevertheless those are small studies and one of them included a mixed population of hip and knee arthroplasty.¹¹

We hypothesized that action observation training could be applied for self-administered exercises associated to conventional inpatient rehabilitation to help improving rehabilitative outcomes (range of motion, pain intensity, functional status, gait, quality of life) of patients undergoing primary total knee replacement.

Methods

We conducted a pilot randomized controlled trial. Informed consent was obtained from all participants and procedures were conducted according to the Declaration of Helsinki. The protocol was approved by the Local Ethical Committee. The present document was prepared according to Consolidated Standards of Reporting Trials publishing guidelines.¹³ It is registered with ClinicalTrials.gov, identifier NCT02707419. From April 2014 to September 2014, all patients consecutively admitted to our Physical and Rehabilitation Medicine department for rehabilitation after elective primary total knee replacement were invited to participate in the present study. At the admission anamnesis, physical examination and a standardized multidimensional assessment was performed by an experienced physician specialized in Physical and Rehabilitation Medicine in order to evaluate the eligibility criteria.

Exclusion criteria were 1) age 18 years or younger and 90 years or older, 2) bilateral knee replacement or previous total knee replacement; 3) indication by the referring orthopedic surgeon to avoid weight bearing on the operated limb or walking; 4) pre-existing motor impairment (i.e. hemiparesis, poliomyelitis, lumbar sciatica); 5) Mini-Mental State Examination^14,15 score of 21 out of 30 or lower; 6) severe vision impairment; 7) severe hearing impairment; 8) delirium on the admission to the department according to Confusion Assessment Method,^16,17 9) unwillingness to participate. All eligible patients signed written informed consent before they entered the study. All the eligible patients who agreed to participate in the present study were randomly assigned either to experimental group or to control group. Randomization was performed with closed envelopes which had been filled randomly indicating experimental or control treatment group allocation

The participants in both groups were treated by an experienced physiotherapist, blinded to all data. All outcomes were collected by an external observer blinded to the treatment allocation of the participants. The variables were measured at baseline and after intervention. Each patient received 30 minutes of rehabilitation twice a day, 5 days a week for 2 weeks. The first 15 minutes were conventional exercises done with a physiotherapist and the second 15 minutes were conventional exercises done independently. All patients were taught how to do the independent exercises by the physiotherapist and were given written instructions to follow. The physiotherapist assisted patients in both group while learning the independent exercises, until they were able to perform them correctly. Before the independent exercise the experimental group watched a video of the exercises being performed while the control group watched a video of nature scenes. The exercises video can be accessed at https://youtube/kecjQO6IC3w.

Conventional physiotherapy consisted of mobilization, exercises and transfer practice; they encompass exercises for isometric and isotonic strengthening of quadriceps, strengthening of lower limb muscles, isotonic strengthening for hip abductors the exercises were initially performed in the supine position and included ankle dorsiflexion and plantar flexion, static quadriceps and inner range quadriceps, gluteal contractions, hip and knee flexion.^18,19 In both group a Continuous Passive Motion device (kinetic, Promed, s.r.l. Nardo, LE, Italy) was applied twice a day for 20 minutes, after the conventional treatment. There were no differences in analgesic and anti-inflammatory drugs consumption between groups.

Data on pain intensity, active and passive range of motion, functional status, comorbidity burden, quality of life and gait features were recorded at the admission and soon after the treatment. The following scale were administered: Visual Analogue Scale,²⁰ active range of motion, passive range of motion,²¹ Barthel index,²² Cumulative Illness Rating Scale,²³ Short Form-36 Health Survey,²⁴ Tinetti scale²⁵ and Lequesne.²⁶ All the outcomes were collected by the same external assessor, blinded to the treatment allocation of the patients.

Statistical analysis

Data were analyzed using SPSS version 21.0 (SPSS Inc, Chicago, IL), conducted following an intention-to-treat analysis using the last value forward method. Group data were summarized as means and standard deviations. The Kolmogorov-Smirnov test confirmed the normality of the distribution of the data. The t Student test was used to determine the level of significance of the differences between the pre and post treatment measurements. We used a 2x2 repeated measures analysis of variance to determine the differences in time (pre-intervention and post-intervention) as the within-subjects factor and group (experimental or control) as the between-subjects factor. The main hypothesis of interest was Group by Time interaction. Between-group differences were expressed as mean differences with 95% confidence intervals. Between-groups effect sizes were calculated using Cohen’s d coefficient. An effect size greater than 0.8 was considered large, around 0.5 moderate, and less than 0.2 small. In all analyses, p<0.05 was considered statistically significant.

Results

Screening identified 31 consecutive participants, who met the eligibility criteria and agreed to participate, they were randomized to the experimental (n=14) or control (n=17) group, as presented in Figure 1. The baseline characteristics of the participants in each group are presented in Table 1.

Table 1.

Baseline demographics for both groups.*

	Experimental (n=14)	Control (n=17)	P-Value*
Age (years)	70.4±7.5	70.1±7.7	0.85
Female gender (n (%))	7 (50.0%)	14 (82.4%)	–
Side, right (n (%))	6 (42.9%)	12 (70.6%)	–
Days between operation and beginning of treatment	6.8±1.4	8.3±1.5	0.02
Length of hospitalization (days)	19.0±3.9	19.3±5.0	0.84
Active flexion	60.0±18.8	52.9±16.4	0.32
BMI	30.0±5.8	28.8±3.8	0.85
CIRS Si	1.5±0.2	1.4±0.2	0.80
CIRS Ci	2.7±1.5	2.2±1.2	0.60
MMSE	28.5±1.5	28.5±2	0.72

BMI: Body Mass Index; CIRS: Cumulative Illness Rating Scale; SI: Severity index; CI: Comorbidity index; MMSE: Mini Mental State Examination.

Data are expressed as means ± standard deviations (SD).

Response to treatment

Pain intensity

Visual analogue scale revealed a significant effect of time difference in experimental group (F_[1.0]=20.744, p<0.001), but not for group interaction for pain intensity. Between-groups effect sizes were small at post-treatment period (all, d=0.1), (Table 2).

Table 2.

Mean (SD) for Outcome at all study visits for each group, mean (SD) difference within groups, and mean (95% CI) difference between groups.

Outcome	Groups				Difference within groups		Effect Size	Difference between groups
	Day 0		Day 10		Day 10 minus Day 0		Day 10 minus Day 0	Exp minus Con
	Exp	Con	Exp	Con	Exp	Con	Cohen’s d	31
	(n=14)	(n=17)	(n=14)	(n=17)	(n=14)	(n=17)
Pain (VAS)	70.6 (19.2)	67.0 (19.7)	49.6 (24.3)	47.1 (17.5)	−21.0* (6.6)	−19.9* (6.1)	0.1	2.5 (–15.3 to 20.2)
Active flexion	60.0 (18.8)	52.9 (16.4)	95.7 (8.6)	80.1 (13.7)	35.7* (4.6)	27.2* (4.0)	1.4	15.6 (5.2 to 24.8)
Active extension	−5.7 (3.5)	−6.4 (4.1)	−0.4 (1.2)	−3.7 (3.5)	5.4* (1.0)	2.7* (0.9)	1.3	3.4 (1.1 to 5.6)
Passive flexion	77.1 (17.8)	69.8 (15.1)	98.8 (17.2)	90.0 (8.1)	21.7* (4.9)	20.2* (4.5)	0.7	8.8 (–1.9 to 19.4)
Passive extension	−4.8 (3.7)	−4.6 (4.1)	−0.8 (2.9)	−1.6 (2.6)	4.0* (0.9)	3.0* (0.8)	0.3	0.8 (–1.8 to 1.0)
Barthel Index	72.5 (4.1)	68.9 (7.2)	92.1 (3.5)	88.0 (7.3)	19.5* (2.2)	19.1* (1.9)	0.7	4.1 (–0.9 to 9.1)
SF-36 motory	26.5 (6.3)	27.2 (3.4)	39.4 (7.9)	33.6 (7.4)	12.9* (2.3)	6.3* (2.1)	0.8	5.8 (–0.7 to 12.3)
SF-36 mentality	53.3 (11.3)	54.3 (11.5)	55.4 (9.0)	51.5 (10.4)	2.1 (3.6)	−2.8 (3.3)	0.4	3.9 (–4.5 to 12.2)
Tinetti scale	18.1 (3.0)	16.5 (2.2)	24.5 (1.7)	21.6 (3.1)	6.5* (0.8)	5.1* (0.7)	1.2	2.9 (0.8 to 5.0)
Lequesne Index	19.5 (2.8)	20.3 (1.8)	10.5 (4.4)	13.9 (2.6)	−9.0* (0.9)	−6.4* (0.8)	0.9	−3.4 (–6.4 to - 3.5)

SF-36: Short Form (36) Health Survey; VAS: Visual Analougue Scale.

Significantly different within-group, P<0.05 (95% confidence interval).

Range of motion

Regarding the results of the active range of motion over the active flexion and extension demonstrated a significant time factor (F=109.067 and F=36.198; all, p<0.001). Active flexion and extension range of motion tend to be higher in experimental group than in control group by difference between groups 15.6° (95%CI 5.3–24.8) and 3.4° (95%CI 1.1–5.6), respectively. Between-groups effect sizes were large at post-treatment period (d>1.3) (Table 2).

Outcomes for passive range of motion over the flexion and extension demonstrated a significant time factor (F=40.149 and F=32.473; all, p<0.001, respectively) but not for group interaction. Between-groups effect sizes were moderate to large (between, d=0.3 and d=0.7) at post-treatment period (Table 2).

Functional status and gait

Functional status and gait features, assessed by Barthel index; Tinetti scale and Lequesne index, showed a significant effect of time (F_[1.0]=174.087; F_[1.0]=126.667; F_[1.0]=153.382; all, p<0.001, respectively) interaction. Between-groups effect sizes were moderate to great at post-treatment period (between, d=0.72 and d=1.15) (Table 2).

Quality of life

Regarding the results of the Short Form-36 motor, they revealed a significant effect of time (F_[1.0]=37.09; p<0.001) for motor recovery. Between-groups effect sizes were moderate at post-treatment period (d=0.76).

For Short Form-36 mental component summary revealed no significant effect of time (F_[1.0]=0.24; p=0.9) and for group-by-time (F_[1.0]=1.004; p=0.3) interactions (Table 2).

Discussion

The findings suggest that self-administered action observation treatment, in addition to conventional physiotherapy could be effective in improving rehabilitative outcomes after total knee arthroplasty. In this pilot randomized controlled trial, indeed, active flexion and extension of the knee tend to be improved in the group of patients treated with action observation treatment

Observing a person performing a meaningful motor task is well known to activate a network of cortical areas, called mirror neuron system.^{5, 27} This finding has set the basis for a rehabilitative technique known as “Action Observation Treatment”, which has been applied in the rehabilitation of motor deficit after stroke,^{6, 7} Parkinson’s disease,⁸ cerebral palsy⁹ and motor performance in elderly people.²⁸ Up to our knowledge, only two small studies deals with the applicability of Action Observation Treatment in orthopedic rehabilitation and their results are slightly different from ours.

Park et al.¹² suggests that Action Observation Treatment improves pain, stiffness and function in patients undergoing total knee arthroplasty while Bellelli et al.¹¹ proved that, in addition to conventional physiotherapy, Action Observation Treatment may ameliorate the recovery of the post-surgical orthopedic patients. In our paper we show that, after total knee replacement, Action Observation Treatment, associated to conventional physiotherapy, determines improved rehabilitative outcomes; in particular we found that, patients in the experimental group tended to have a better degree of active flexion and extension of the knee. Unlike Park et al., between the two groups, we did not find any difference in pain assessed by visual analogue scale.

This study has also failed to show significant differences between groups in Short Form-36, Lequesne, Barthel Index and Tinetti score. Regarding the former, there has been non significant trend to better outcomes in the experimental group. A larger study with adequate sample size will show whether the differences exist or not for these outcome variables. Bellelli et al.¹¹ found a higher score in Functional Independence Measure and Tinetti scale in patients who received Action Observation Treatment after orthopedic surgery (hip and knee arthroplasty were considered together); in our study we did not find any difference for Tinetti scale score, but we found that the action observation treatment group tend to have a better active degree of flexion and extension of the knee; none of the previous studies had evaluated this feature, that we think is informative of the rehabilitative process; moreover Bellelli et al.¹¹ considered hip and knee arthroplasty together, while we analyzed only knee arthroplasty and this might explain lack of differences in Tinetti scale score.

Traditionally rehabilitation of post-surgical orthopedic patients is mainly focused on peripheral structures (joints, muscles and subcortical motor actions), our results suggest a possible role of Action Observation Training as a “booster” in the conventional rehabilitative treatment of muscle skeletal diseases. It has been supposed that action observation training with a “top-down” approach could ameliorate the motor recovery of patients who had undergone a total knee replacement. In every motor task and during walking as well, cortical input are of uttermost importance for the execution of the task. Brain plasticity and cortical input are crucial element of the motor recovery process not only in neurological disease, but also in muscle skeletal disorders.²⁹ The findings of this study suggest a possible role of action observation training in the clinical rehabilitation after total knee replacement; this may imply that the addition of a higher load of “cortical” rehabilitation to standard rehabilitation programs can improve the final result. Whether this approach might reduce time for inpatients rehabilitation is a matter of interest because, if confirmed, it could help to reduce the economic burden of extended hospitalization. Moreover, it may be a possible approach to continue home training after discharge.

Limitations of this study are the relative small number of patients, which may explain the absence of significant differences in some of the outcomes; short follow up data, and no sample size calculation, but this is an exploratory randomized controlled trial set to fine-tune a larger study. Improvement of active range of motion is an important outcome but by itself does not describe a global better outcome. A new study with adequate sample sizes to detect differences in Short Form-36 scores, Barthel Index, Tinetti scale and Lequesne Index will be started on the basis of this pilot study.

Self-administered action observation training added to conventional physiotherapy, seems associated with a greater degree of recovery in patients who have undergone a primary total knee replacement. This study suggests top-down effects of this treatment in motor recovery of post-surgical orthopedic patients. In order to confirm the favourable effect of action observation treatment in rehabilitation, it should been evaluated in larger randomized controlled trials.

Due to its easy applicability and its possibly home application to continue training after discharge, action observation treatment could be very handle in the modern fast track rehabilitation of the patients who have undergone total knee replacement. Larger studies, including patients with modern fast track, are needed to prove action observation treatment effective, and eventually include it in rehabilitative programs of post-surgical orthopedic patients.

Clinical messages

Action observation treatment in addition to conventional physiotherapy seems to increase the efficacy of rehabilitation of patients after total knee replacement.

Action observation treatment could be considered as ancillary strategy in the rehabilitation of post surgical orthopedic patients.

Footnotes

Acknowledgements

The authors thanks PS and PT for their assistance.

Conflict of interest

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

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