Background: With the rising popularity of long-distance running in Hong Kong, running-related injuries have become more common, particularly patellofemoral pain syndrome (PFPS), which is one of the most prevalent conditions among endurance runners. PFPS can negatively affect training consistency, race performance, and long-term participation. While exercise therapy is the primary intervention, patient adherence and long-term outcomes remain limited. Traditional Chinese Medicine ointment (TCMO, Ng's formula) has shown anti-inflammatory and tissue-repairing properties, making it a promising adjunct therapy for PFPS.
Objective:
1. To evaluate the efficacy and safety of selected topical agents used in Traditional Chinese Medicine on PFPS in long-distance runners. 2. To assess the impact of these topical agents on running performance in PFPS patients.
Methods: A randomized, controlled, parallel-group, single-blinded trial will be conducted with 50 participants. Group A will receive TCMO combined with exercise therapy, while Group B will receive exercise therapy alone. The intervention lasts four weeks, with weekly follow-ups to monitor adherence. Primary outcomes include Kujala Scale (AKPS), eccentric step-down test, and fastest finishing time of recorded race distances. Safety will be monitored through participant reports and exclusion of individuals with contraindications.
Mean running distance > 20 km/week and 10 km/session. If kilometer per week conflicted with kilometers per session, for example, 40 km/week with a frequency of 5 times/week, it is classified according to kilometers per week.
Clinical diagnosis of Alzheimer's Disease
Be between 18 and 60 years of age and able to provide written informed consent.
Have experienced knee pain for more than four weeks.
Presence of absolute contraindications for Chinese herbal medicated plasters;
Pregnancy or lactation;
Oral or topical use of non-steroidal anti-inflammatory drugs within the past two weeks;
Steroid injections within the past two months;
Crossover
TCM ointment
Other interventionGroup A's TCMO intervention is a four-week topical therapy applied directly to the knee. Each participant receives one jar per week and applies the ointment once nightly on non-training days, and twice daily-before training and before sleep-on training days. A thin layer is spread slightly beyond the painful area to ensure coverage. Patients keep a logbook of applications, and researchers supervise the first use, provide instructions, and check technique during weekly visits. Safety is monitored through exclusion criteria and weekly follow-ups. This routine is designed to prevent pain during activity and aid recovery overnight, offering both immediate relief and long-term support.
Exercise therapy
Other interventionThe exercise therapy intervention in the protocol is a structured four-week program designed to strengthen hip and quadriceps muscles while improving flexibility. Participants complete 12 supervised sessions (three per week), each consisting of three sets of 10 repetitions performed at 60% of their 10-repetition maximum. The first two weeks focus on hip strengthening through abduction and external rotation exercises with sandbag resistance, while the following two weeks target quadriceps with straight leg raises and end-range knee extensions. Stretching routines for hamstrings, quadriceps, iliotibial band, and gastrocnemius are included, each held for 30 seconds and repeated three times. Weekly follow-ups ensure proper technique, adherence, and progression, with therapists reviewing exercise logs and adjusting resistance as needed. This intervention emphasizes muscle balance, pain reduction, and functional recovery, serving as the control arm against topical therapy in the trial.
Kujala Scale
Functional assessment through AKPS, also named as Kujala Scale would be used It is a 13-item self-administered questionnaire designed to record patients' subjective responses to specific activities and symptoms associated with anterior knee pain syndrome. Scores range from 0 to 100, with lower values indicating more severe pain and functional impairment. Chinese version of the AKPS assessment will be used to facilitate the communication with Chinese-speaking participants.
Eccentric step down test
The eccentric step down test will be used. It shows moderate specificity (0.82; 95% CI: 0.62, 0.93) and +LR (2.3; 95% CI: 1.9, 2.9), shows that probability of PFPS being present when there is a positive test is moderately increased. Reproduction of anterior knee pain during the test is considered a positive test result. Subjects will perform the test barefoot using a 15 cm step (or more precisely, equivalent to 50% of tibial length). Each subject will be instructed to stand on the step with hands on hips, step down as slowly and smoothly as possible while maintaining this posture throughout. The test will first be performed on one leg, then repeated on the other leg. Warm-up or practice trials are prohibited. If anterior knee pain (AKP) recurs during the test, it is recorded as a positive test result
Fastest finishing time of recorded distance
Finishing time would be used as measuring the running performance. According to Haugen et al. (2022) , fastest finishing time of 5000m, 10000m, half marathon (21,097.5m) and marathon (42,195m) within a racing season (180 days preceding the marathon race) is measured. The shorter finishing time will imply the rising performance for the runner. The fastest record of 5000m, 10000m, half marathon or marathon before week 0 would be collected as the baseline. Collection of finish time of one of these four distance would be done at week 2 and week 4.
Visual analogue scale (VAS)
Participants will be instructed to indicate their pain level on a line ranging from 0 to 10, with 0 representing no pain and 10 indicating unbearable pain. It has be proven valid and reliable \[21\]. The VAS will be applied at two moments: (1) pain in the last month (during the baseline assessment); and (2) before and after performing two functional activities: bilateral squatting at 90° (for 30 seconds) and step-up/down 26 cm (for 30 seconds). Squatting and stepping up and down are activities which exacerbates anterior knee pain for patient of PFPS \[7\]. The assessment will be done at week 0, week 2 and week 4. The higher the value of VAS, the more the pain.
Timed Up and Go
The Timed Up and Go (TUG) test is a standardized measurement tool for assessing functional mobility, balance, and gait. Participants begin seated, rise to a standing position as instructed, walk a fixed distance of 3 meters with safe steps, turn around, return to the chair, and sit down. The total time is recorded using a stopwatch, with the duration from standing up to resitting serving as the test result. Each participant must complete three trials, and the final analysis is based on the average of these three trials.
Treatment Expectation Questionnaire (TEX-Q)
The Questionnaire could be used for evaluating the change of treatment expectation. Chinese version of this questionnaire would be used in this trial. It will be done at week 0 and week 4. Comparison of two data could be used to evaluate the extent of placebo effect.
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