Kinesio tape combined with supervised rehabilitation provides satisfactory outcome in treating patellofemoral pain syndrome

INTRODUCTION

Patellofemoral pain syndrome (PFPS) is a common musculoskeletal condition characterized by anterior knee pain, typically exacerbated by activities that load the patellofemoral joint during weight-bearing with a flexed knee, such as stair climbing, squatting, jogging, or jumping. It is particularly prevalent among physically active individuals, with an estimated 8.75% of those engaged in intense physical training affected, significantly impacting their activities.^[1] The reported annual prevalence of PFPS is approximately 23% in adults and 29% in adolescents, and 5.1-14.9% in adolescent amateur athletes over one competitive season. Alarmingly, 57% of individuals with PFPS may experience prolonged symptoms, with unfavorable outcomes reported in 5-8 years.^[2]

In athletes, symptoms often arise due to increased patellofemoral stresses, frequently resulting from abnormal lower extremity biomechanics during activities such as drop landings with knee valgus. These biomechanical abnormalities include decreased hip rotation control, increased foot pronation, femoral anteversion, and tibial rotation, contributing to altered patellofemoral joint mechanics and pain.^[3]

Weakness of the vastus medialis obliquus (VMO) and hip musculature can lead to increased Q-angle, lateral patellar contact pressures, and subsequent cartilage erosion, contributing to the pathology of PFPS.^[4]

Pain as perceived by highly innervated tissues in the anterior area of the knee are the infrapatellar fat pad and synovial tissue, including the medial parapatellar plica.^[5,6]

Patients with PFPS generally present with pain around the patella, which aggravates with activities that load the patellofemoral joint. Patients may also describe pain on prolonged sitting (theater sign).^[7,8]

Management of PFPS is predominantly conservative, emphasizing quadriceps strengthening to enhance medial stability of the patella, hip abductor and external rotator strengthening, core stabilization, and gait retraining. Addressing gait abnormalities, such as rearfoot strike patterns that elevate patellofemoral stress, through forefoot strike pattern training has demonstrated reductions in pain.^[9,10] Adjunctive therapies, such as patellar bracing, taping, and orthobiologic interventions like platelet-rich plasma, also play a role in mitigating symptoms. There is substantial evidence supporting the efficacy of quadriceps exercises, whereas evidence for the effectiveness of alternative treatment modalities remains limited. Among taping techniques, McConnell and Kinesio taping (KT) methods are widely utilized. KT, introduced by Kenzo Kase, has gained popularity due to its versatility and proposed benefits, including providing positional stimulus, reducing pain, lifting fascia to enhance lymphatic drainage, and facilitating muscle balance. While some studies suggest that KT improves proprioception and muscle function, others report no significant changes in strength despite pain relief. The effectiveness of KT in managing PFPS remains a subject of debate in the literature.^[11] While some studies report improvements in muscle strength and proprioception following its application, others have found no such benefits, despite a consistent reduction in pain levels.^[12,13] Furthermore, there is a notable lack of research evaluating the impact of KT on activities of daily living in individuals with PFPS.

Understanding the interplay of biomechanical and biological factors in PFPS is essential for developing effective interventions and restoring tissue homeostasis, as suggested by Scott F. Dye’s.^[14]

Vastus lateralis contracts later than VMO during extension of knee. In case of VMO weakness, there was an increase in lateral patellofemoral extension load as reported by Neptune et al.^[15] Hence, VMO was facilitated in this study by KT and specific exercises for strengthening of VMO. This was considered to be leading to improvement in visual analog scale (VAS) and Kujala scores. Based on this fact, this study hypothesized that KT and exercise therapy would be useful in treating PFPS and also identified risk factors contributing to PFPS.

The Kujala Anterior Knee Pain Scale, while widely accepted for PFPS assessment, does not fully capture symptoms related to osteoarthritic changes. The scale’s specificity lies in its assessment of patellofemoral joint-related activities through a comprehensive set of 13 items. To complement this, the knee injury and osteoarthritis outcome score patellofemoral pain (KOOS-PF) subscale was employed in our study to better assess osteoarthritis-related dimensions of knee function.

MATERIALS AND METHODS

This was a prospective study conducted at a tertiary care center over 18 months. Fifty patients aged 18-40 years diagnosed with PFPS were enrolled after meeting the inclusion criteria. The sample size was estimated based on assessing the efficacy of KT combined with exercise therapy in reducing pain at follow-up in patients with PFPS, compared to exercise therapy alone. This estimation was informed by a study by Akbas et al., which reported good to excellent functional outcomes in 85% of patients.^[16] Assuming a similar proportion (P = 85%) and a 10% margin of error, the minimum required sample size at a 5% level of significance was calculated to be 49 patients.

Formula used:

n = 1.961.96p*q/d²

• p is the proportion of good to excellent outcomes (85% or 0.85).

• q = 1-p.

• d is the margin of error (10% or 0.1).

Sample size calculation:

n = 1.961.960.850.15/0.100.10 = 48.98 (~49 patients).

Fifty patients diagnosed with PFPS were included in the study after complete evaluation with anterior knee pain lasting 4-6 weeks, aged 18-40 years. Patients with a history of recent trauma to the knee joint, bony, tendon, ligament injury, and meniscal pathology, recent intra-articular injection, any previous procedure done to the same knee, sensitivity to Kinesio tape, or having a skin allergy were excluded from the study.

Intervention

Weekly KT was performed by a sports medicine specialist according to the method established by the KT Association International,^[17] with supervised exercise therapy (quadriceps, hamstring, and hip muscle strengthening) for 30 min once a week, followed by a home exercise program that was done twice/day for the rest of the week up to six weeks. Exercise therapy comprised of straight leg raises, short arc lifts, wall slides, hamstrings stretch, quadriceps stretch, calf stretch, lateral hip and thigh stretch, and core abdominal strengthening. Patients were also made to do isometric strengthening at 0°, 45°, and 90°, gluteal bridges, side-lying clamshells, and side-lying hip abduction. Pain and functional outcomes were assessed using VAS, Kujala, and KOOS-PF scores at baseline, 2, 4, 6 weeks, and 6 months. Around 5 cm width Kinesio^® Tex tapes were used for taping. KT was applied with VMO facilitation and patellar functional correction [Figure 1]. In the VMO facilitation, the interval between the superior anterior iliac spine and the patella midpoint while the patients were supine position was measured. The length of the tape was taken as half of this interval. A 2-inch I strip of Kinesio^® Tex Tape split to a Y. Tails of the Y strip prepared were considered as 1/2 of the tape length. The first part of the tape, which is called “base,” was applied without strain on the VMO body, and the lateral “Y” tail was applied along the pes anserinus and ended on the tibia, while on the knee extension. The patient was then asked to move his/her knee to full flexion. The medial “Y” tail was applied along the medial side of the patella and ended at the lower end of the patella. The rest, excluding the first and last 5 cm of the tape, was applied with 50% tension [Figure 1].

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Figure 1:

Kinesiotaping Technique (As per KT Association International) in Patellofemoral Pain Syndrome.

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Ethical clearance for the present study was obtained from the Institutional Review Board/Institutional Ethics Committee (IEC) of Vardhman Mahavir Medical College (VMMC) and Safdarjung Hospital, New Delhi. The study was reviewed and approved under protocol number IEC/VMMC/SJH/Thesis/06/2022/CC-280, dated February 16, 2022, in accordance with the ethical standards of the Declaration of Helsinki and the guidelines of the Indian Council of Medical Research (ICMR).

Informed consent was obtained from all the patients for being included in the study.

Statistical analysis

Data were entered in Microsoft Excel, and analysis was carried out in the Statistical Package for the Social Sciences, version 29. Qualitative parameters such as age, gender, knee involved, and other tests were presented as frequencies and percentages. Quantitative parameters such as weight, height, and Q angle. Hamstring-to-quadriceps (H/Q) ratio and duration of symptoms were reported as mean, standard deviation (SD), and median along with the minimum and maximum values. Similarly, mean, SD, and median along with the minimum and maximum values were reported for VAS, KOOS-PF, and Kujala scores. Difference in difference analysis was conducted to assess the improvement in scores between baseline to four weeks and between baseline to six months [Figure 2]. An independent t-test was used to do difference in difference analysis. Improvement in scores was compared across the age groups, gender, medial and lateral patellar facet tenderness, patellofemoral crepitus, and single leg squat test with VAS, KOOS-PF, and Kujala scores, which were done with an independent or student t-test. Bar diagrams and line diagrams were used for graphical representation. P < 0.05 was considered statistically significant. The effect size between baselines at the end for VAS was 2.4, for Kujala was 2.3, and for Koofs was 1.9. Cohen’s d was used to report the effect size for all these parameters between the baselines to the end of follow-up.

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Figure 2:

Difference in difference of scores (Change in VAS, KOOS-PF, and Kujala score from baseline up to six months). VAS: Visual analog scale, KOOS-PF: Knee injury, and osteoarthritis outcome score-patellofemoral.

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RESULTS

A total of 70 patients were recruited for the study; however, 20 dropped out and could not complete all the follow-ups. Out of the 50 who completed the follow-ups, 52% of patients were in the age group of 18-30 years, whereas 48% of them were in the age group of 31-40 years. Hence, there was almost equal distribution of patients in both the 18-30 years age range as well as 31-40 years age range. There were 10% more males than females in the patient population. Twenty-two percentages of subjects in the study were athletes, whereas 78% of them were sedentary. In the majority of patients, the right knee was involved, and 48% of patients complained of a recent increase in activity. Only 36% of patients were able to perform the single leg squat test, which is a functional movement assessment test that helps to test strength and balance of the supporting leg [Table 1]. The mean height of patients was 167.8 ± 10.8 cm, the mean weight was 67.2 ± 10 kg, the mean Q angle of patients was 15.7 ± 1.3°, the mean H/Q ratio was 0.7 ± 0.2, and the mean thigh foot angle was 15 ± 1.5 [Table 2]. The mean Q angle in males was 15.5 ± 1.2, while the mean Q angle in females was 15.9 ± 1.5 [Table 3].

The study demonstrated significant improvements in pain and functionality for patients with PFPS when KT was combined with supervised exercise therapy [Table 4]. Pain levels, as measured by VAS, showed a substantial reduction from a baseline mean score of 6.06 ± 1.46-2.26 ± 1.59 at 6 months (P < 0.001), indicating a marked decrease in perceived pain severity [Figure 3]. Functional capacity, assessed using the Kujala Score, improved significantly from a baseline mean of 59.68 ± 10.07-82.64 ± 9.66 (P < 0.001), highlighting enhanced knee functionality and reduced discomfort during daily activities [Figure 4]. The KOOS-PF showed clinical improvement from 45.43 ± 9.84 to 60.86 ± 12.52, which was also clinically significant (P < 0.001) [Table 5]. No adverse effects were reported in the study.

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Figure 3:

Visual analog scale (VAS) score at 2 weeks, 4 weeks, 6 weeks, and 6 months.

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Figure 4:

Knee injury and osteoarthritis outcome score - patellofemoral (KOOS-PF) and Kujala score at 2 weeks, 4 weeks, 6 weeks, and 6 months.

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DISCUSSION

This study demonstrated that the addition of KT to a structured rehabilitation protocol resulted in statistically significant improvements in key outcome measures for patients with PFPS. These improvements, reflected in reductions in VAS pain scores and enhancements in both the Kujala and KOOS-PF scores, were consistent across all follow-up time points, indicating progressive and sustained functional recovery. Our findings are aligned with those of Kuru et al. and Akbaş et al., who also reported improvements in Kujala scores with combined KT and exercise therapy (82.13 ± 4.91 and 81.69 ± 9.54, respectively).^[16,17] However, it is noteworthy that these prior studies did not demonstrate a statistically significant difference between KT-plus-exercise and exercise-only groups. This highlights the ongoing debate about the additive value of KT beyond conventional rehabilitation strategies and underlines the need for further high-quality trials to delineate KT’s mechanistic and clinical contributions.

Although KOOS-PF scores demonstrated an improving trend, statistical significance was not reached at the 4-week follow-up mark. The overall improving trend was in line with the findings by Nair et al., who reported a negative correlation between pain severity and quality of life in PFPS patients, with higher numerical pain rating scale scores associated with lower KOOS-PF scores.^[18]

Pain is a hallmark symptom of PFPS, commonly aggravated by activities involving deep knee flexion such as stair climbing, squatting, and prolonged sitting. In the present study, a significant reduction in VAS pain scores was observed across all follow-up periods, with patients reporting a return to near pre-onset activity levels by six months. These findings align with those of Akbaş et al., who reported similar decreases in VAS scores in both the KT and control groups.^[16] Although KT did not yield superior outcomes compared to exercise alone, it was associated with a more rapid improvement in hamstring flexibility. In addition, Aytar et al. noted immediate reductions in VAS scores following KT application; however, the lack of an accompanying exercise intervention in their study may have limited the overall therapeutic effect.^[19]

In the present study, the mean age of participants was 29.18 ± 7.48 years, with the majority falling within the 18-40-year age range, which contrasts with previous studies, such as those by Akbaş et al. and Günay et al., which included older populations.^[16,20] The relatively younger cohort in this study may reflect a higher baseline level of physical activity. Furthermore, a male predominance was observed (60%; male-to-female ratio of 1.5:1), which diverges from existing literature that reports a higher prevalence of PFPS in females-commonly attributed to anatomical and biomechanical factors such as increased Q-angle and lower limb strength imbalances. This variation may be influenced by gender-based differences in physical activity patterns within the Indian population, and the small sample size may have introduced sampling bias.

In this study, knee involvement was reported as right-sided in 32% of participants, left-sided in 42%, and bilateral in 26%, a distribution consistent with the findings of Aytar et al.^[19] Participants exhibited varying levels of occupation-related physical activity: 62% were classified as sedentary, 14% as moderately active, and 24% as engaged in sports activities, equally divided between non-impact (12%) and impact (12%) sports. The high proportion of sedentary individuals underscores the need for tailored intervention strategies targeting this demographic.

A systematic review by Bolgla and Boling concluded that exercise therapy remains the most effective conservative intervention for managing PFPS.^[21,22] In contrast, other modalities such as patellar taping, patellar bracing, knee bracing, and foot orthoses demonstrated limited efficacy when used in isolation, highlighting the superior benefits of exercise-based rehabilitation strategies.

Biomechanical parameters associated with PFPS were also evaluated in this study. The mean Q-angle among participants was 15.7 ± 1.3°, with gender-specific averages aligning with established norms-14° for males and 17° for females. Although a Q-angle >15-20° is commonly associated with knee extensor dysfunction and patellofemoral pain, the values observed in this cohort did not exceed this threshold significantly, suggesting that Q-angle was not a contributing risk factor in this sample.

In addition, the mean H/Q strength ratio was 0.7 ± 0.2, and the mean thigh-foot angle was 15 ± 1.5°. Given that an H/Q ratio above 0.6 and a thigh-foot angle within this range are considered normal, neither parameter appeared to be a significant biomechanical risk factor in the studied population.

The normal H/Q ratio in the context of isometric strength testing is generally considered to be in the range of 0.5-0.6. This means that the isometric strength of the hamstrings is typically about 50-60% of the isometric strength of the quadriceps. The mean H/Q ratio in the present study, being 0.7 ± 0.2, is within the normal range for such a population. Higher ratios (≥0.6) are preferable in athletes, since they depict a good balance between hamstrings and quadriceps, making knees less prone to injuries.

In terms of Q angle, similar results were found by Rathleff et al. in adolescents.^[23] Lankhorst et al. showed contradictory results, reporting significant quadriceps strength deficits in adults with PFPS compared to controls.^[23,24]

While Q-angle and thigh-foot angle abnormalities were not significant risk factors, 92% of participants had an H/Q strength ratio of <1, suggesting quadriceps and hamstring weakness as a contributing factor.

This study has limitations, including the absence of a control group and a lack of long-term follow-up. Future research should include large-scale, randomized controlled trials with extended follow-up periods to confirm these findings.

CONCLUSION

KT with supervised structured rehabilitation provides fast improvement in pain and improved functionality, underlining the effectiveness of combining both for PFPS. However, the disparity between Kujala and KOOS-PF in initial four-week scores suggests the need for further research to confirm these outcomes.