Knee osteoarthritis (KOA) is one of the most common musculoskeletal disorders, characterized by progressive degeneration of joint structures, and is a major contributor to pain, limited mobility, and reduced quality of life, particularly among the elderly population (Wolf et al., 2024). This condition becomes increasingly complex in overweight older adults, where excessive mechanical stress on the knee joint accelerates cartilage damage and exacerbates clinical symptoms such as pain and dysfunction (Bliddal et al., 2014). Additionally, age-related physiological changes also contribute to reduced muscle strength and joint stability, thereby exacerbating functional limitations. Therefore, KOA is not only an individual clinical problem but also a significant public health burden. As a result, KOA in overweight older adults represents not only a complex clinical condition but also a growing public health concern due to its impact on independence, disability risk, and healthcare utilization.

Overweight status represents a clinically relevant factor in KOA management because excessive body mass not only increases compressive forces across the knee joint but also contributes to systemic inflammatory processes associated with disease progression. Previous biomechanical studies have demonstrated that each additional kilogram of body weight may substantially increase knee joint loading during walking. Consequently, overweight older adults often experience greater pain severity, reduced mobility, and poorer rehabilitation outcomes than normal-weight individuals, highlighting the need for targeted intervention strategies in this high-risk population.

The importance of this research is underscored by the high prevalence of knee osteoarthritis (KOA), its substantial impact on functional independence among older adults, and the associated long-term healthcare burden. Non-pharmacological interventions, particularly physiotherapy-based exercise therapy, are widely recommended as a primary approach in KOA management due to their effectiveness in reducing pain and improving physical function (Fransen et al., 2015). However, the effectiveness of exercise therapy alone may be limited, especially in individuals with overweight conditions, where increased biomechanical load and altered movement patterns can further complicate joint function and rehabilitation outcomes.

Several recent studies indicate that multimodal approaches, such as combining exercise therapy and manual therapy, may yield better outcomes than single-modality interventions. For example, a study by Runge et al. (2022) reported that the combination of manual therapy and exercise resulted in significant short-term improvements in pain and function among patients with osteoarthritis. Another study by Deyle et al. (2005) also showed that the combination of manual therapy and exercise resulted in greater functional improvement compared to exercise alone. Additionally, Tsokanos et al. (2021) emphasized in their systematic review that manual therapy plays a crucial role in improving joint mobility and reducing pain. A recent study by Espírito Santo et al. (2024) further supports the effectiveness of manual therapy in reducing musculoskeletal pain in the menopausal population. However, most of these studies still focus on the general population or postmenopausal women and have not specifically explored the population of overweight older adults.

Although previous studies generally support the use of combined exercise and manual therapy for knee osteoarthritis, the evidence remains inconsistent. Some randomized controlled trials have reported superior improvements in pain and function when manual therapy is added to exercise programs. In contrast, other studies have found only modest or short-term benefits, particularly for self-reported functional outcomes such as WOMAC scores. Furthermore, many studies have included heterogeneous populations without considering body weight status as a potential modifier of treatment response. As obesity and overweight substantially increase knee joint loading, alter gait mechanics, and contribute to chronic low-grade inflammation, intervention effects observed in the general KOA population may not be directly transferable to overweight older adults.

Previous research by Hosseini & Dudonienė (2025) showed that a combination of exercise and manual therapy is more effective than exercise alone in improving pain and mobility in postmenopausal women with KOA. However, that study did not consider overweight as a key variable that could influence treatment outcomes. This highlights a research gap, particularly regarding the effectiveness of multimodal physical therapy interventions in overweight older adults with KOA.

In light of the identified gap, this study examines the effects of combining exercise therapy with manual therapy in overweight older adults with knee osteoarthritis, a group with unique biomechanical and physiological characteristics. Furthermore, the study applies a comprehensive assessment framework encompassing pain, joint function, range of motion (ROM), and physical performance to capture the intervention's multidimensional impact.

No randomized controlled trial has specifically investigated the added value of manual therapy when combined with exercise therapy in overweight older adults with knee osteoarthritis. Unlike previous studies conducted in general KOA populations or postmenopausal women, the present study focuses on a high-risk subgroup characterized by increased biomechanical loading and functional limitations. Furthermore, this study simultaneously evaluates pain, self-reported function, knee range of motion, and objective physical performance outcomes, providing a comprehensive assessment of treatment effectiveness. Pain was selected as the primary outcome because it is the most common symptom driving disability and treatment seeking in KOA. WOMAC was included to assess disease-specific functional limitations, ROM to evaluate mechanical joint mobility, and TUG to capture objective functional performance and mobility capacity in daily activities.

A total of 40 participants were enrolled and randomly allocated to the intervention group (n = 20) or control group (n = 20). No participants were lost to follow-up, and all participants completed the post-intervention assessments. Therefore, data from all 40 participants were included in the final analysis. Intervention adherence was monitored through attendance records. Participants attended all scheduled treatment sessions, resulting in 100% adherence. No adverse events related to the exercise or manual therapy interventions were reported during the study period.

Abbreviations: SD, standard deviation; BMI, body mass index; OA, osteoarthritis; K–L grade, Kellgren–Lawrence classification. Data are expressed as mean ± SD. Between-group differences were analyzed using independent samples t-test.

Abbreviations: C, control group; I, intervention group; SD, standard deviation; VAS, Visual Analogue Scale; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index; ROM, range of motion; TUG, Timed Up and Go test. Data are presented as mean ± SD. Between-group intervention effects were analyzed using ANCOVA with baseline scores entered as covariates. Effect size is reported as partial eta squared (η²).

All participants completed the intervention and post-intervention assessments. No participants were lost to follow-up or excluded from the final analysis. Adherence to the intervention protocol was 100% in both groups, and no adverse events related to the exercise or manual therapy interventions were reported during the study period.

This study aimed to compare the effects of a combined exercise and manual therapy program with exercise alone on pain and functional outcomes in overweight older adults with knee osteoarthritis. The findings demonstrated that both interventions significantly improved pain, joint function, range of motion (ROM), and physical performance after 12 weeks. However, the combined intervention showed superior improvements in pain reduction (VAS), ROM, and functional mobility (TUG test) compared to exercise alone. At the same time, no significant between-group difference in WOMAC scores was observed.

Beyond statistical significance, the observed improvements are clinically meaningful. The intervention group demonstrated a reduction in VAS pain scores from 7.59 to 4.07, representing a mean improvement of 3.52 points. Previous studies have suggested that the minimally clinically important difference (MCID) for pain intensity in individuals with knee osteoarthritis is approximately 1.5–2.0 points on a 10-point scale. Therefore, the magnitude of pain reduction observed in the present study exceeded commonly accepted MCID thresholds, indicating that the benefits were not only statistically significant but also clinically relevant. Similar considerations may apply to improvements in functional mobility, as reflected in TUG performance, although MCID values can vary depending on patient characteristics and disease severity.

These findings are consistent with previous studies that have highlighted the effectiveness of exercise therapy in managing knee osteoarthritis. Exercise-based interventions have been widely reported to reduce pain and improve function by enhancing muscle strength and joint stability (Bennell et al., 2020). Furthermore, manual therapy provides additional benefits, particularly in reducing pain and improving joint mobility. Similar results were reported by Kandada & Heggannavar (2015), who found that combining manual therapy with exercise significantly improved pain and functional outcomes compared to exercise alone. In addition, systematic evidence suggests that multimodal physiotherapy approaches tend to yield better clinical outcomes than single-modality interventions (Abbott et al., 2013).

Although the findings generally align with previous reports supporting exercise-based rehabilitation and manual therapy for knee osteoarthritis, several alternative explanations should be considered. The additional benefits observed in the intervention group may not be attributable solely to the physiological effects of manual therapy. Increased therapist–participant interaction, enhanced treatment expectancy, and greater participant engagement could also have contributed to improved outcomes. Furthermore, the relatively short intervention period and the absence of long-term follow-up prevent conclusions regarding the durability of treatment effects. Therefore, the present findings should be interpreted as evidence of short-term efficacy rather than definitive long-term effectiveness.

Several underlying mechanisms can explain the greater improvements observed in the intervention group. Exercise therapy improves muscle strength, particularly in the quadriceps, which play a critical role in knee joint stabilization and load distribution (DeVita et al., 2018). Stronger musculature reduces mechanical stress on the joint, thereby decreasing pain and improving function. Meanwhile, manual therapy contributes through neurophysiological and biomechanical mechanisms (Carvalho et al., 2025). Joint mobilization techniques can stimulate mechanoreceptors, leading to pain inhibition via central and peripheral pathways, while also enhancing synovial fluid movement and joint lubrication (Bialosky et al., 2009). Additionally, myofascial release may reduce muscle stiffness and improve tissue extensibility (Laimi et al., 2018), thereby further increasing ROM and functional performance. These combined effects explain why the intervention group demonstrated superior outcomes in VAS, ROM, and TUG.

Interestingly, no significant between-group difference in WOMAC scores was observed, despite improvements in both groups. This may be due to the multidimensional nature of WOMAC, which includes pain, stiffness, and functional components. While manual therapy may strongly influence pain and mobility, broader functional improvements, as measured by WOMAC, may require longer intervention durations or additional behavioral and lifestyle modifications, such as weight management and long-term adherence to physical activity (Young et al., 2023).

Despite the consistent improvements observed in the present study, previous research has reported heterogeneous findings regarding the added value of combining manual therapy with exercise in knee osteoarthritis. For instance, a study published in Osteoarthritis and Cartilage reported improvements in clinical symptoms following combined interventions, yet no significant superiority was observed in WOMAC outcomes compared to usual care. In contrast, a randomized controlled trial by Deyle et al. (2005) demonstrated substantially greater improvements in WOMAC scores when manual therapy was integrated with exercise compared to a home-based exercise program. Furthermore, a systematic review and meta-analysis by Runge et al. (2022) concluded that while combined interventions provide meaningful short-term benefits, their long-term superiority over exercise alone remains inconclusive.

Some studies reported clinically meaningful benefits of combined interventions, whereas others failed to demonstrate superiority over exercise alone. These discrepancies may be attributable to differences in participant characteristics, intervention dosage, therapist expertise, and outcome measures used across studies. Such methodological heterogeneity complicates direct comparison and highlights the need for population-specific investigations.

The findings of the present study align with this pattern of variability, particularly with respect to WOMAC outcomes, where no significant between-group difference was observed despite clear improvements in both groups. Such discrepancies across studies may be attributed to differences in study design, participant characteristics, intervention dosage, and adherence levels. In particular, the inclusion of overweight older adults in the current study introduces additional biomechanical and physiological considerations that may influence responsiveness to intervention. Increased joint loading, altered movement patterns, and reduced muscle efficiency in this population may limit the extent to which improvements in pain and mobility translate into broader functional gains captured by multidimensional measures such as WOMAC.

From a clinical perspective, these findings suggest that physiotherapists should consider incorporating manual therapy into exercise-based rehabilitation programs for overweight older adults with knee osteoarthritis. A multimodal approach combining strengthening, flexibility, and manual techniques may optimize outcomes, particularly for pain reduction and mobility improvement. Additionally, interventions should be individualized based on patient tolerance, osteoarthritis severity, and functional limitations. Education on weight management and regular physical activity should also be emphasized to enhance long-term outcomes.

This randomized controlled trial demonstrated that adding manual therapy to an exercise-based rehabilitation program produced greater improvements in pain, knee range of motion, and functional mobility than exercise therapy alone in overweight older adults with knee osteoarthritis. Importantly, this study extends existing evidence by specifically focusing on an overweight older adult population, a subgroup characterized by increased biomechanical loading and elevated risk of functional decline that has been underrepresented in previous clinical trials.

The findings suggest that a multimodal rehabilitation approach combining therapeutic exercise and manual therapy may be particularly beneficial for addressing the complex clinical needs of overweight individuals with knee osteoarthritis. Given the substantial improvements observed in pain and mobility outcomes, clinicians should consider incorporating manual therapy as an adjunct to structured exercise programs when managing this population.

Future randomized controlled trials should include larger samples, prospective sample-size calculations, assessor blinding, and longer follow-up periods to assess the sustainability of treatment effects. In addition, future studies should investigate whether combining physiotherapy interventions with weight-management strategies and lifestyle modification programs can further enhance functional outcomes and quality of life in overweight older adults with knee osteoarthritis.

The data supporting this study's findings are available on request from the corresponding author. The data are not publicly available because they contain information that could compromise the privacy of research participants

This research does not receive external funding.

The author hereby declares that this research is free from conflicts of interest with any party.