Does backward gait require more proprioception and balance in older adults after total knee arthroplasty?

Abstract

Objectives

Some basic and instrumental daily living activities include backward gait. There is a need to clarify which parameters should be focused more on to improve backward gait in older individuals. This research investigated the proprioception, and balance in forward-backward gait of older individuals with total knee arthroplasty (TKA).

Methods

A prospective cross-sectional research was conducted with 105 older adults with TKA. Individuals' forward and backward gait performance was assessed with the Timed Up & Go Test (TUG) and 3 Meter Walk Back Test (3MBWT), respectively. Proprioception was measured with a mobile application-based inclinometer. Berg Balance Scale (BBS) and Activity Specific Balance Confidence Scale (ABC) were used to assess balance and balance confidence levels, respectively. A single clinician evaluated the individuals.

Results

TUG was weakly and positively correlated with the Right and Left Leg Proprioception Test (RLPT and LLPT) (r₁ = 0.386, r₂ = 0.391, p < 0.01). Also, the 3MBWT was weakly and positively correlated with RLPT and LLPT, respectively (r₁ = 0.293, r₂ = 0.251, p < 0.01). In addition, TUG was strongly and negatively correlated with BBS and ABC, respectively (r₁ = −0,693, r₂ = −0.722, p < 0.01). Besides, 3MBWT was strongly and negatively correlated with BBS and ABC (r₁ = −0.642, r₂ = −0.645, p < 0.01).

Conclusion

The study revealed that forward and backward walking were similarly associated with balance and proprioception in older adults with TKA. Clinicians should focus more on balance ability than proprioception to improve backward walking performance in older individuals with THA.

1. Introduction

Total knee arthroplasty (TKA) is the gold-standard surgical procedure to improve quality of life.¹ TKA is frequently preferred in cases where conventional treatment of severe primary knee osteoarthritis fails, particularly in older individuals over 65 years of age.² Studies have reported decreased gait performance, balance, and, therefore, ability to perform daily living activities in older adults after TKA.^3,4

Basic and instrumental activities of daily living involving transfer might involve forward and backward walking tasks.⁵ The essence of balance and proprioception ability for forward walking in older individuals with THA has been demonstrated in previous studies. One of these parameters, balance, is a complex function that integrates information about body position.^6,7 Balance is essential to maintain postural stability in performing activities of daily living.⁸ On the other hand, proprioception provides an essential input to individuals regarding joint position during walking. As a vital part of the somatosensory system, proprioception ability improves patients' physical performance after TKA.⁹ Moutzouri et al. reported that postural strategies and proprioception did not improve sufficiently after TKA.¹⁰ Although there are positive changes, such as decreased pain and improved function after TKA, balance impairment and changes in gait may occur in many patients due to decreased proprioception.^11,12 Therefore, assessing and improving balance, proprioception, and physical performance are crucial in rehabilitation programs for individuals with TKA.¹³

Although the parameters affecting forward walking have been examined in studies, it is inquisitive which parameters affect backward walking. It may be assumed that decreased visual input in backward walking may require more proprioception ability. In recent years, the 3-m Backward Test (3MBWT)¹⁴ has been a preferred test for determining proprioception, balance, protective reflexes, and fall risk.¹⁵ The 3MBWT, performed more difficultly by individuals, requires better balance safety because it includes neuromuscular control, balance, protective reactions, and proprioception. Moreover, studies have reported that 3MBWT is more sensitive to mobility and balance skills than forward walking.^15,16

There is a need to clarify which parameters should be focused more on to improve backward gait in older individuals.¹⁷ In clinical practice, emphasizing the importance of balance and proprioception training to improve daily living activities, including backward walking performance, would be valuable. This research investigated the proprioception, and balance in forward-backward gait of older individuals with total knee arthroplasty (TKA).

2. Methods

2.1. Subjects and clinical setting

The study was conducted with 105 total knee arthroplasty patients in the Orthopaedics and Traumatology Department of the Fethiye State Hospital between November 2022 and September 2023. In the present cross-sectional study, eligible patients were called from hospital records and invited to the trial. All assessments were performed by a physiotherapist experienced in orthopedic rehabilitation. The study was approved by Ege University Medical Research Ethics Committee (No: 22-10T/27, Date: 08.10.2022). Inclusion criteria were; (1) TKA surgery at least ≥6 months ago, (2) ability to communicate, (3) age ≥18 years, (4) volunteer to participate in the study. Exclusion criteria were (1) history of revision surgery or other surgery, (2) TKA due to rheumatoid arthritis, (3) neurologic, psychological or orthopedic disease that could affect the assessments, (4) postoperative complications such as deep vein thrombosis, (5) patients using assistive devices. The sample size was considered according to Cohen's d coefficient using Gpower software (19). Accordingly, effect size = 0.50, error probability 0.05 and statistical power 0.95 were calculated and at least 34 cases were sufficient.

2.2. Procedures

The socio-demographic and clinical characteristics of the patients were recorded at baseline. All assessments were performed by the same physiotherapist. TUG, 3MBWT, Proprioception measurement with iHandy Level phone application, BBS, Activity Specific Balance Confidence Scale (ABC) were used. The tests were explained in detail to the patient in advance. During the tests, all patients received standardized and identical verbal orders. The order of administration of the tests and questionnaires was kept the same for each patient. The patient was allowed to sit and rest for 1 min between tests.

2.2.1. Surgical procedure

Total knee arthroplasty was performed under general anesthesia. The mean surgical time was approximately 60–70 min. A tourniquet was used during the surgical operation. Conventional methods were preferred for post-operative pain management. Patients were used non-steroid anti-inflammatory drugs and paracetamol. Tramadol hydrochloride was also used in some patients during post-operative pain control.

2.2.2. Timed Up & Go Test (TUG)

TUG was used to assess functional mobility quickly and effectively. The participant is seated on a standard (44 cm) chair without armrests. The 3-m track is measured and marked. With the start command, the patient stands up and walks at a safe speed. The patient walks the track without stopping, turns back, and sits on the chair. The time between the start command and the patient sitting on the chair was noted.¹⁸

2.2.3. 3-M backward walk test

For the 3MBWT, the track is determined with a distance of 3 m between the start line and the finish line. Participants stand with their heels on the starting line. After the “start” command, the individual walks backward toward the finish line at a safe speed. The time was recorded with a stopwatch.⁵

2.2.4. Proprioception measurement with app-based inclinometer

With the knee in full extension, the smartphone is placed distal to the patient's tibial tuberosity. Afterward, the patient does “a single leg squat with eyes closed”. At 30° knee flexion angle, the patient stops with the stop command of the evaluator and maintains this position for 5 s. Then return to full knee extension. The patient performs the same movement, this time without the stop command. Thus, the target angle of 30° is tried to be achieved. The absolute degree difference between the target and actual is recorded.^19,20

2.2.5. Berg Balance Scale

BBS is performed to assess postural control and fall risk. The scale assesses expected balance during different activities with 14 items. Each item is scored on a scale from “0 (unable to perform) to 4 points (normal performance)”. The scores received from each item are summed to obtain a total score with a maximum of 56 points. Higher scores indicate better condition.²¹

2.2.6. Activity Specific Balance Confidence Scale

ABC assesses 16 activities to determine balance confidence in older people. Scores for each item range from “0% (no confidence) to 100% (full confidence)”. Higher scores indicate more confidence.²²

2.3. Statistical analysis

All statistical analyses were performed using “SPSS for Windows v25.0 software (SPSS Inc., Chicago, IL, USA)”. Pearson correlation coefficient was used to examine the relationship between forward and backward walking performances and balance and proprioception. There is a strong relationship if the correlation coefficient is 0.50 and above, a moderate relationship between 0.35 and 0.50, and a weak relationship if it is lower than 0.35. Our study determined the statistical significance level as p < 0.005.

3. Results

The present study was conducted with 105 participants with TKA. The demographic and clinical data of the participants were summarized in Table 1. The relationship between forward/backward walking performances with balance and proprioception is summarized in Table 2. Although not the study's central hypothesis, we also focused on the relationship between TUG and 3MBWT, thinking that the relationship between forward and backward gait may give direction to our hypothesis. First, TUG was positively and very strongly correlated with 3MBWT (r = 0.831, p < 0.01).

Table 1.

The baseline physical and clinical characteristics of the participants.

	TKA patients (n = 105)
Age (years, mean ± SD)	70.11 ± 7.09
Gender (women/men, n (%))	87(82.9)/18(17.1)
BMI (kg/m2, mean ± SD)	32.1 ± 5.21
Affected side (right/left/bilateral, n (%))	34(32.4)/41(39)/30(28.6)
Dominant side (right/left, n (%))	102(97.1)/3(2.9)
Living area (urban/rural, n (%))	64(61)/41(39)
Education status (primary/high school and above, n (%))	93(88.6)/12(11.4)
Smoking (yes/no, n (%))	5(4.8)/100(95.2)
Duration after TKA surgery (months, mean ± SD)	38.41 ± 32.84
Presence of chronic disease (present/absent, n (%))	86(81.9)/19(18.1)

SD: standard deviation, n: number of patients, BMI: Body Mass Index, TKA: Total Knee Arthroplasty.

Table 2.

The proprioception, and balance in forward-backward gait of older individuals.

n: 105	TUG	3MBWT
RLPT	0.386**	0.293**
LLPT	0.391**	0.251**
BBS	−0.693**	−0.642**
ABC	−0.722**	−0.645**

TKA: Total Knee Arthroplasty, n: number of patients, TUG: Timed Up and Go Test, 3MBWT: 3 Meter Backward Walk Test, RLPT: Right Leg Proprioception Test, LLPT: Left Leg Proprioception Test, BBS: Berg Balance Scale, ABC: Activities-Specific Balance Confidence Scale, BMI: Body Mass Index, **: p < 0.01; Pearson Correlation Test was used in all analyses.

Second, we focused on the parameters between forward walking and balance. TUG was strongly negatively correlated BBS and ABC, respectively (r₁ = −0,693, r₂ = −0.722, p < 0.01). TUG was weakly positively correlated with Right and Left Leg Proprioception Test (RLPT and LLPT), respectively (r₁ = 0.386, r₂ = 0.391, p < 0.01) (Table 2).

Thirdly, the relationship between individuals' backward walking performance and balance and proprioception was examined. The 3MBWT was strongly negatively correlated with BBS and ABC, respectively (r₁ = −0.642, r₂ = −0.645, p < 0.01). 3MBWT was weakly positively correlated with RLPT, LLPT and age, respectively (r₁ = 0.293, r₂ = 0.251, r₃ = 0.323, p < 0.01) (Table 2, Table 3).

Table 3.

The comparison of the scores between the gender.

	Women (n = 87)	Men (n = 18)	p
TUG (mean ± SD)	13.86 ± 3.86	13.09 ± 5.39	0.11a
3MBWT (mean ± SD)	10.89 ± 4.87	10.43 ± 5.79	0.462a
RLPT (mean ± SD)	5.38 ± 3.18	3.78 ± 3.73	0.019a
LLPT (mean ± SD)	5.56 ± 3.59	4.55 ± 3.66	0.218a
BBS (mean ± SD)	44.57 ± 8.3	47.22 ± 8.59	0.104a
ABC (mean ± SD)	65.83 ± 18.07	73.86 ± 19.39	0.06a

SD: standard deviation, n: number of patients, TUG: Timed Up and Go Test, 3MBWT: 3 Meter Backward Walk Test, RLPT: Right Leg Proprioception Test, LLPT: Left Leg Proprioception Test, BBS: Berg Balance Scale, ABC: Activities-Specific Balance Confidence Scale, a: Mann–Whitney U Test.

4. Discussion

The study revealed that forward and backward walking were similarly associated with proprioception and balance in older adults with TKA. According to our hypothesis, the requirement for greater proprioception in a physical performance task involving backward walking was not confirmed. Clinicians should focus more on balance ability than proprioception to improve backward walking performance in older individuals with THA. In summary, backwards walking performance represents the most balance, balance confidence and physical performance status of individuals with TKA.

Decreased proprioception, quadriceps muscle strength, balance and balance confidence performances have been previously demonstrated in older adults.23, 24, 25 Worsening of these parameters was demonstrated in adults with TKA.^12,26, 27, 28 No study has demonstrated the relationship between proprioception and backward walking performance in individuals with TKA. Moreover, the relationship between balance and confidence in balance and backward walking performance is engaging. This cross-sectional study may provide unique clinical outcomes in terms of these features. However, it should be noted that the results can only be generalized for patients in the chronic period, as proprioception and physical function may differ in the acute and subacute periods of the first six months after TKA.¹²

In our study, proprioception was mainly associated with forward walking performance. However, there was a similar relationship between backward walking performance and proprioception. In summary, proprioception is associated with both forward and backwards walking performance. On the other hand, a stronger correlation was noted between balance and balance confidence and proprioception. From this, it can be concluded that proprioception is predominantly used to maintain balance during walking. Balance maintenance is essential for both forward and backwards walking.^14,29 Therefore, although we cannot claim that proprioception's reduced visual input in forward walking cannot be tolerated, the low correlation does not indicate that proprioception ability is more remarkable in backward walking. Other deficits in the physical condition of the individuals (muscle strength, range of motion, advanced age) may have affected the backward walking performance more in terms of duration. Therefore, the correlation with proprioception performance may have been lower. Future studies may focus on testing proprioception during a sensor-based gait analysis to assess proprioception ability during forward and backwards walking performance.

Our study results showed that backward walking performance was most similar between forward walking and balance and trust in the subject. That is, individuals' performance in forward or backward walking was similar. The relative time to perform the test with decreasing visual input is similar.¹⁴ It can be interpreted that balance and balance confidence parameters are more critical than proprioception, especially for walking. However, it should be remembered that these concepts are generally in multiple relationships with each other. Forward walking performance was primarily related to backward walking and balance confidence. Balance confidence and forward gait may have been associated with forward gait, especially in daily living activities involving forward gait.

Another result of our study was that proprioception was higher in men than in women, as expected. However, this superiority was found only for right extremity proprioception. This outcome may have clinical implications for gender differences in proprioception, especially for the dominant and commonly used joint. The fact that the individuals were bilateral with right or left extremities did not affect the evaluation parameters. Unilateral patients would likely have better balance, balance confidence, proprioception and gait performance. However, in individuals with unilateral TKA, regression analysis considering cofactors such as the current status of the other extremity, the severity of OA or metabolic conditions of the individuals, which could not be evaluated within the scope of this study, may provide additional data.

The literature emphasizes decreased proprioception, physical function and balance ability in individuals with post-operative TKA.³⁰ However, it is also stated that impaired proprioception and balance are better than the pre-op period.31, 32, 33 In fact, it is also stated in the literature that there will be more proprioception gain in unicompartmental TKA alternatives to TKA.³⁴ In addition, it is stated that posterior cruciate ligament preservation does not provide any gain in terms of proprioception and clinical outcomes. However, the importance of surgery for preserving both ligaments in terms of proprioception was also emphasized.³⁵ Ünver et al. reported performance of 6–7 s for 3MBWT performance in individuals with TKA.¹⁴ Our study observed a lower physical performance of approximately 10 s. This result may be due to the older age of the individuals in our population.

4.1. Limitations

Mentioning some limitations of the study may be effective in designing future research methodologies. First, our study did not isolate individuals with TKA as unilateral or bilateral. On the other hand, the severity of another extremity OA in unilateral individuals was not detailed. In this respect, cofactors should be addressed more comprehensively in order to obtain more precise results from these sensitive evaluations. Secondly, we did not address the type of surgery or cruciate ligament preservation. This information may be valuable for multicenter studies with large sample sizes to create more homogeneous groups, primarily since the importance of rehabilitation history in terms of proprioception is known. In our study, it is seen that the number of female individuals is high. Since the difference between male and female proprioception is known,³⁶ gender may be an essential factor affecting the results.

5. Conclusion

The study revealed that forward and backward walking were similarly associated with proprioception and balance in older adults with TKA. According to our hypothesis, the requirement for greater proprioception in a physical performance task involving backward walking was not confirmed. Clinicians should focus more on balance ability than proprioception to improve backward walking performance in older individuals with THA. In summary, backwards walking performance represents the most balance, balance confidence and physical performance status of individuals with TKA.

Funding

None.

Consent to participate

Informed consent of the patients was obtained.

Ethical approval

The study was carried out in accordance with the ethical principles and the Helsinki Declaration. The study was approved by Ege University Medical Research Ethics Committee (No: 22-10T/27, Date: 08.10.2022).

CRediT authorship contribution statement

Fatih Özden: Conceptualization, Investigation, Methodology, Writing – original draft. İsmail Uysal: Conceptualization, Investigation, Methodology, Writing – original draft. İsmet Tümtürk: Conceptualization, Investigation, Methodology, Writing – original draft. Mehmet Özkeskin: Conceptualization, Investigation, Methodology, Writing – original draft. Fatih Özyer: Investigation, Writing – review & editing.

Declaration of competing interest

The authors report no conflicts of interest and certify that no funding has been received for this study and/or preparation of this manuscript.