Comparative Analysis of Musculoskeletal Responses in Patellofemoral Osteoarthritis Patients: A Study on Retro-walking Treadmill Protocols using an Experimental Design

1. Student, Faculty of Physiotherapy, SGT University, Gurugram, Haryana, India. 2. Associate Professor, Faculty of Physiotherapy, SGT University, Gurugram, Haryana, India. 3. Assistant Professor, Faculty of Physiotherapy, SGT University, Gurugram, Haryana, India. 4. Associate Professor, Faculty of Physiotherapy, SGT University, Gurugram, Haryana, India.

Abstract

Introduction: Knee Osteoarthritis (OA) is a significant cause of disability globally and is rapidly becoming a major health issue. The part of the knee most affected by OA is the patellofemoral joint. This type of arthritis poses challenges for both patients and healthcare providers in managing symptoms and improving the quality of life for those affected. However, there’s a lack of data on specific therapies for the patellofemoral joint.

Aim: To investigate if a varied frequency treadmill exercises protocol involving retro-walking has a greater impact on musculoskeletal responses, leading to better improvements in individuals with symptomatic Patellofemoral Joint Osteoarthritis (PFOA).

Materials and Methods: The present study was an experimental research design i.e., between -subjects experimental design in which 60 participants with patellofemoral arthritis were enrolled based on the inclusion criteria. The study was conducted in the Department of Orthopaedics, SGT Medical College Hospital and Research Institute in Gurugram, Haryana, India for a duration of one year (May 2022- May 2023). Participants were randomly randomised to three distinct exercise program groups with varying intensity levels for retro-walking on a treadmill for six weeks, and all three groups received conventional treatment six days/week for six weeks. All participants were evaluated at three-time intervals of baseline, at the end of the third week, and after intervention (end of the sixth week) for the evaluation of several musculoskeletal parameters affecting patellofemoral arthritis. Statistical analysis was carried out using the IBM Statistical Package for the Social Sciences (SPSS) version 26.0. Comparison for within group differences between various outcome measures at various intervals of time was done using repeated measures of Analysis of Variance (ANOVA) and post-hoc analysis for mean values with Least Significant Difference (LSD) whereas for between group analysis One-way ANOVA and post-hoc Analysis for mean values was done with p-value set at <0.05.

Result: Significant statistical and clinical differences were observed in musculoskeletal responses, Q-angle (p-value=0.001) and popliteal angle (p-value=0.001) in the high frequency group (group C) performing the protocol five times a week for six weeks leading to a better quality of life followed by group B and group A, respectively.

Conclusion: The main finding of the present study suggested that the dosage for retro-walking on treadmill among patients with patellofemoral arthritis requires at least walking for five times/week for six weeks to get more clinical improvement in Musculoskeletal Disorders (MSD).

Musculoskeletal abnormalities, Osteoarthritis knee, Patellofemoral pain syndrome, Treadmill test

The MSDs are the second-leading cause of disability worldwide, according to the Global Burden of Disease (GBD) study (1). The burden of age-related MSDs varies, with approximately 20-33% of individuals worldwide experiencing pain associated with these disorders (2). Arthritis is a notable MSD that significantly contributes to the overall disability burden worldwide (1). OA affects approximately 50% of all MSDs. Among individuals aged 60 years and above worldwide, the knee is the most affected joint in cases of OA and causes severe financial burden and mobility difficulties (3). Most notably, knee OA symptoms are more likely to arise from the patellofemoral joint than from the tibiofemoral joint. Even isolated, moderate radiographic PFOA can generate significant symptoms that significantly affect daily living activities (3). PFOA is a disorder that affects the knee joint, resulting in pain, stiffness, and reduced function. PFOA, a common form of OA, presents substantial challenges for both patients and healthcare practitioners in terms of symptom management and increasing the quality of life for individuals affected. In recent years, there has been an increasing interest in exploring alternate and focused exercise programs to reduce the impact of PFOA. Both low- and high-income countries are gradually seeing an increase in the prevalence of PFOA (4). Symptoms are reported by 9.6% of men and 18% of women (5) with a gradual onset of symptoms, often in an asymmetrical pattern. The primary and most prominent symptom of OA is pain, which is occasionally described as a deep ache (6). Weight-bearing joints are typically aggravated by standing and walking, while rest tends to provide relief. Although pain is usually intermittent, it can become persistent over time. In knee OA, localised pain is frequently experienced below the patellofemoral attachment or along the inner joint line. As patellofemoral arthritis progresses, joint mobility becomes increasingly restricted (7). The loss of movement and function often prompts patients to seek frequent medical attention, along with the presence of pain. Diminished mobility can make it more challenging to carry out daily tasks, including walking and engaging in household chores. Walking is a type of exercise that uses the closed kinetic chain, allowing for early mobilisation and weight bearing during knee rehabilitation (8). For those with knee OA, regular walking activities are helpful and advised to lessen pain and disability. Existing studies that have investigated possible differences between Forward Walking (FW) and Backward Walking (BW) have shown that there are no appreciable differences between the two and that BW is simply FW mirrored (9),(10),(11). Utthoff A et al., reported that only a small number of earlier studies examined the effects of BW; the majority of studies examined the effects of backward running (12). Prior research has indicated that in healthy adults, the program of backward running may provide benefits beyond those of forward running. Retro-walking is thought to be a useful closed kinetic chain workout for enhancing the strength of the body’s lower muscles and equilibrium. According to a Masumoto K et al., backward running preserves isometric and concentric quadriceps activity while reducing eccentric activity (13). Given that 2021-2030 has been designated as the decade of healthy ageing by the World Health Organisation (WHO), it is critical to give equal weight to life expectancy and quality of life (14).

Considering all the factors the primary objective of the current study was to close current knowledge gaps on the best exercise regimens for patients with patellofemoral arthritis by thoroughly examining varied frequency treadmill training at three different frequency levels while retro-walking and also comparing them. With the research hypothesis stating that the different frequencies (low, intermediate and high frequency) will have a significant effect on the various musculoskeletal parameters (pain, popliteal angle, Q-angle, balance, muscle strength, ROM, Cadence and functional disability) and a predetermined treadmill walking dosage meant to enhance positive impacts on patients and improve their general wellbeing. This study intends to provide insightful information about the development of evidence-based exercise therapy for improving PFOA and forms the basis for cause and effect relationship among patellofemoral arthritis and musculoskeletal parameters. Comprehending the impact of varying exercise frequencies on musculoskeletal results is important in creating rehabilitation plans customised to the specific requirements of patients suffering from PFOA.

Material and Methods

The study employed an experimental study design and was conducted in the Department of Orthopedics, SGT Medical College Hospital and Research Institute in Gurugram, Haryana, India. It spanned one year (from May 2022 to May 2023) and involved randomly allocating subjects into three experimental groups. Sealed closed envelope method was done in 1:1 allocation ratio. The study received approval from the Institutional Ethics Committee (IEC) of SGT University’s Faculty of Physiotherapy (SGTU/FPHY/2022/424). Informed consent was obtained from all participants. Ethical standards adhered to the principles of the Declaration of Helsinki, 1964.

Inclusion criteria: Individuals aged between 50 and 70 years diagnosed with PFOA, experiencing unilateral knee pain for at least three months, and scoring 5 or less on the NPRS scale (15) were included in the study.

Exclusion criteria: A history of recent knee surgery, severe knee pain inhibiting treadmill exercise, cardiopulmonary conditions, neurological disorders, inflammatory joint diseases, balance problems, or reliance on assistive devices for ambulation were excluded from the study.

Sample size estimation: A total of 65 subjects were screened for participating in the study. Using an effect size of d 0.5, alpha err prob 0.05, and power (1-Beta err Prob) 0.6, the G Power program version 3.19 was used to compute the sample size for the current study. Based in the effect size estimates, a total sample size of 60 participants were recruited with 20 participants each in group A (low frequency group), group B (intermediate frequency group) and group C (high frequency group).

Outcome measure: The outcome measures used in the study are shown in (Table/Fig 1) (16),(17),(18),(19),(20),(21),(22). (Table/Fig 2),(Table/Fig 3) shows Q-angle and popliteal angle measurement using universal goniometer.

Study Procedure

Convenience sampling was used to choose participants at random. Before any testing, the participants were given a thorough explanation of the process and their informed consent was obtained. The present study was carried out at the SGT University Hospital’s Physiotherapy OPD. As shown in (Table/Fig 4), the study included participants who met the inclusion and exclusion criteria. The subjects gave written consent prior to the treatment. Following a preliminary examination, each participant in the study was randomly allocated to one of three groups: group A (low frequency group; that is, twice a week), group B (intermediate frequency group; that is, three times a week), or group C (high frequency group; that is, five times a week). An assessment was made on the baseline measurement. All the groups followed the protocol and data was collected at the three timelines i.e., baseline, at the end of 3rd week and end of 6th week after intervention.

Treadmill Protocol-15 Minutes (Table/Fig 5) (19):

Day 0- For five minutes, a practice session was provided to help with skill adaptation and preferred walking speed selection.

Consecutive days: Same protocol was followed by all the three experimental groups but with different frequency depending on the Group.

• Three minutes of retro-walking on a treadmill set at 0% incline for initial three minutes.
• Raise the speed to the permitted level and maintain it for five minutes at 0% inclination.
• Keep walking at the same pace for the next five minutes, but increase the incline by 10%.
• Lower the inclination to 0% and progressively lower the pace for the final two minutes until the treadmill stops.

Conventional Protocol (9): All the three experimental groups received the conventional treatment on all six days for six weeks.

Conventional treatment, where the participant was lying supine, and a hot pack was applied to the knee for 10 minutes. Following that, this group followed the exercise program which included the combination of open kinetic chain and closed kinetic chain exercises which are:

1. Static quads exercise (3 sets×10 rep)
2. Dynamic quads exercise (3 sets×10 rep)
3. Knee bending (3 sets×10 rep)
4. Hip extension (3 sets×10 rep)
5. Hip abduction (3 sets×10 rep)

Each exercise was given for five minute and each conventional treatment session was administered for 35 minutes daily.

Statistical Analysis

IBM SPSS 26.0 for Windows Version was used to statistically analyse the pain, Q-angle, popliteal angle measurement, knee ROM, functional impairment, dynamic balance, muscle strength, and cadence of 60 patients. For this aim, data was entered into an Excel spreadsheet, tabulated, and statistical analysis was carried out. The mean and standard deviation of each variable were established. The results were deemed statistically significant at p<0.05.

Comparison for within group differences between various outcome measures at various intervals of time-baseline, end of three weeks of treatment and end of six weeks of treatment for all groups was done using repeated measures of ANOVA and post-hoc analysis for mean values was done with LSD whereas for between group analysis One-way ANOVA and post-hoc analysis for mean values was done.

Results

A total of 60 patients with PFOA were recruited for the present study, comprising 36 females and 24 males. Group A had a mean age of 58.40±9.26 years, while group B had a mean age of 59.80±7.02 years and group C had a mean age of 61.70±7.83 years. Descriptive analysis was conducted to assess the age and gender distribution in both groups. No significant age difference was observed between the groups. Regarding gender distribution, group A included 9 males (45%) and 11 females (55%), while group B included eight males (40%) and 12 females (60%) whereas group C included 13 females (65%) and seven males (35%). There was no significant difference in gender distribution between the groups. (Table/Fig 6) displays the demographics of the participants in Groups A, B, and C.

The comparison of mean NPRS values at baseline and at the end of the 3rd week and 6th week after treatment between group A, group B and group C is shown in (Table/Fig 7). The NPRS scores comparison between group A, group B and group C demonstrated highly significant postintervention values (p-value<0.0001) at 3rd week as well as in 6th week. A statistical difference in the mean values of the Q-angle and Popliteal angle postintervention between group A, group B and C at the end of 3rd and 6th week was also observed. Similarly, a highly significant difference was found in the mean values of knee ROM, Dynamic Balance and WOMAC scores postintervention (p-value<0.0001) using an One-way anova at the end of the 3rd week and 6th week after treatment between group A, group B and group C as shown in (Table/Fig 7).

The comparison of post-hoc analysis of NPRS, Q-angle, knee ROM, popliteal angle, dynamic balance, WOMAC and Cadence score at end of 3rd week and end of 6th week between the groups is shown in (Table/Fig 8) to infer the specific time interval where the difference was observed on comparison between group A vs group B vs group C.

The comparison of mean muscle strength of hip and knee values at baseline and at the end of the 3rd week and 6th week after treatment between group A, group B and group C is shown in (Table/Fig 9). The muscle strength scores comparison between group A, group B and group C demonstrated highly significant postintervention values (p-value< 0.0001) on flexors and extensors group of knee muscles at 3rd week as well as in 6th week. A One-way ANOVA revealed a statistical difference in the mean values of the hip muscle strength of flexors, extensors, abductors and adductors postintervention between group A, group B and C at the end of 3rd and 6th week as shown in (Table/Fig 9).

The comparison of post-hoc analysis of the muscle strength scores of knee and hip musculature at end of 3rd week and end of 6th week between the groups is shown in (Table/Fig 10) to infer the specific time interval where the difference was observed on comparison between group A vs group B vs group C.

Discussion

This study aimed to assess the impact of different frequencies of treadmill exercise protocols on various musculoskeletal parameters during retro-walking in individuals with PFOA. The results indicated that the high frequency group, which engaged in retro-walking on a treadmill five times a week for six weeks alongside conventional treatment, experienced significant reductions in pain and improvements in the Q-angle, popliteal angle, knee ROM, dynamic balance, Activities of Daily Living (ADLs), and cadence. This improvement was particularly notable among participants aged 40-70 years.

The findings suggest that group C showed the most substantial improvement, followed by group A and B, respectively, after the third and sixth weeks of the retro-walking treadmill program. One possible explanation is that retro-walking on a treadmill could alleviate pain by triggering the endogenous opioid system. This system releases natural opioids like endorphins, which can help alleviate pain. Supporting this idea, Kuptniratsaikul V et al., reported that a four-week aerobic exercise regimen, which included retro-walking on a treadmill, raised plasma beta-endorphin levels in individuals with knee OA (23). The rise in beta-endorphins was linked to enhancements in pain severity and physical performance. Alghadir AH et al., inferred that the biomechanical actions of the muscles around the knee and ankle were reversed during retro-walking (4). During retro-walking, the knee plays a significant role as the primary power generator, engaging the hamstring, quadriceps, and ankle plantar flexors to absorb stress. This movement also results in anterior shear stress at the knee joint, contrasting with the posterior shear stress experienced during forward walking. Retro-walking notably reduces the patellar compressive force compared to forward walking. Walking, a widely accessible and affordable form of physical exercise is known to help alleviate symptoms of depression, obesity, and cardiovascular disease. In this study, significant improvements in the Q-angle were observed in group B and highly significant improvements in group C. The Q-angle, which measures the alignment of the patella in relation to the femur, is associated with the risk of knee pain and OA. Retro-walking on a treadmill has been found to improve the Q-angle in knee OA patients, likely through various physiological mechanisms. Alghadir AH et al., suggested that retro-walking on a treadmill may enhance quadriceps muscle strength and activation (4). The enhancements in quadriceps muscle strength and activation were linked to a reduction in the Q-angle, indicating that retro-walking on a treadmill may enhance the Q-angle by improving quadriceps muscle function. This improvement was also observed in the knee ROM in group C, followed by group A and B, respectively, after the 3rd and 6th week of the retro-walking treadmill program. Retro-walking has the potential to enhance neuromuscular control thereby improving knee ROM. Neuromuscular control refers to the nervous system’s ability to regulate muscle activity. Patients with knee OA often experience reduced neuromuscular control, which can lead to decreased knee ROM and increased pain. Retro-walking may improve neuromuscular control, resulting in enhanced knee ROM and reduced pain (24). Retro-walking has shown promise in enhancing joint flexibility, especially in the knee joint. Individuals with knee OA often suffer from reduced joint flexibility, which can restrict knee ROM and exacerbate pain. Retro-walking has been found to enhance joint flexibility, thereby improving knee ROM and reducing pain. The findings of Chand D et al., align with present study, indicating that retro-walking on a treadmill can enhance knee joint flexibility and is linked to increased knee ROM in knee OA patients (25). The current study’s findings were statistically significant (p-value<0.05), indicating that the intervention had a notable effect, particularly in group C, followed by group A and B. Retro-walking on a treadmill involves a distinct knee joint movement pattern compared to forward walking. This movement can aid joint mobilisation, reducing stiffness, and enhancing joint lubrication. These effects may lead to increased knee ROM and could potentially influence the popliteal angle (26). The findings suggest that group C showed the most significant improvement, followed by group A and B, respectively, after the 3rd and 6th weeks of the retro-walking treadmill program. Baby E and Thachil A proposed that one of the primary mechanisms by which retro-walking enhances balance in patients with knee OA is by activating ankle extensor muscles like the gastrocnemius and soleus (27). During retro-walking, the muscles responsible for plantarflexion, which is the downward movement of the foot toward the ground, are particularly active. This is because the body’s weight is shifted backward during retro-walking, requiring these muscles to work harder compared to forward walking. The increased activation of these ankle extensor muscles helps stabilise the ankle joint and improve balance. The current study found significant improvement between the groups, as shown by the statistical analysis. Retro-walking involves various muscle groups, including the quadriceps, hamstrings, glutes, and calves. This finding aligns with a study by Fitzgerald GK et al., which concluded that regular retro-walking can activate and strengthen these muscles, crucial for supporting joint stability and functional movements. Enhanced muscle strength and endurance can improve functional performance, reduce disability, and the study demonstrated that muscle strength improvement yielded significant results in all groups (28). Plotkin DL et al., observed muscle transitions during exercise training, noting that walking can activate both slow-twitch (Type I) and fast-twitch (Type II) muscle fibers. Slow-twitch fibers are resistant to fatigue and crucial for endurance, whereas fast-twitch fibers are responsible for generating force and power (29). Participating in retro-walking can activate a wider range of muscle fibers, enhancing muscle strength. Additionally, research by Suetta C et al., demonstrated that retro-walking could challenge neuromuscular control, coordination, and balance (30). The repetitive backward movement involved in retro-walking stimulates neural pathways that enhance muscle coordination and motor unit recruitment. This stimulation can lead to improved muscle activation patterns and more efficient muscle contractions, ultimately increasing muscle strength. Present study demonstrated a significant improvement in cadence across all groups. Korkmaz C and Toy AB suggested that retro-walking, which entails walking backward, may enhance knee flexion during the swing phase of gait (31). This greater knee flexion could lead to longer strides and possibly increase the pace, improving balance. Another suggested reason is that retro-walking involves several muscle groups like the quadriceps, hamstrings, glutes, and calves. With repetitive backward walking, these muscles can develop better coordination and timing, resulting in more effective muscle activation patterns during walking. Improved muscle activation can increase force and power production, allowing for a quicker and more consistent pace (32). This study will help the physiotherapists to use different frequency treadmill exercise protocol in patients with PFOA patients as rehabilitative intervention in a clinical setting with appropriate dosage of treatment protocol. Implementing long-term follow-up assessments to evaluate the sustained effects of the interventions over time and incorporating Patient-Reported Outcome Measures (PROMs) to capture participants’ perspectives on treatment effectiveness, quality of life, and satisfaction with the interventions can be studied in the future.

Limitation(s)

The present study had some potential limitations. First, due to lack of power with three small groups, this study might have been underpowered to detect a significant effect of each treatment group and there was no control group. Only patellofemoral arthritis was included. Making participants walk on treadmill requires more monitoring of other cardiovascular or any other associated complications so monitoring needs to be very comprehensive.

Conclusion

The effect of three different frequency treadmill exercise protocol significantly improved pain, Q-angle, popliteal angle, knee ROM, functional disability, dynamic balance, muscle strength and cadence outcomes during retro-walking in PFOA patients. Moreover, this study concluded that there was a highly significant improvement in Group C followed by Group A and B respectively after 3rd and 6th week of retro-walking treadmill program.

Contribution of Author: CC: Conception and design of the study; PR: Analysis and interpretation of data; ST: Drafting of the article; SK: Final drafting of manuscript.

DOI and Others

DOI: 10.7860/JCDR/2024/71100.19709

Date of Submission: Apr 05, 2024
Date of Peer Review: May 01, 2024
Date of Acceptance: Jun 17, 2024
Date of Publishing: Aug 01, 2024

AUTHOR DECLARATION:
• Financial or Other Competing Interests: None
• Was Ethics Committee Approval obtained for this study? Yes
• Was informed consent obtained from the subjects involved in the study? Yes
• For any images presented appropriate consent has been obtained from the subjects. Yes

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