Effect of laser acupuncture on pain, range of motion, and function in patellofemoral pain syndrome: a randomised controlled trial

Patellofemoral pain syndrome is a condition that primarily affects adolescents and young adults, being twice as common in women as in men. This condition is characterized by pain in the anterior knee region, especially when going up or down stairs, squatting, jumping, or remaining seated with the knee flexed for prolonged periods. The prevalence of this syndrome is considerable, affecting approximately 22.7% of the general population and 28.9% of adolescents, representing a significant socioeconomic impact on healthcare systems due to its persistent nature and the functional limitation it causes.

Conservative treatment of patellofemoral syndrome traditionally includes physical therapy with strengthening and stretching exercises, as well as physical modalities such as electrical stimulation and laser therapy. Recently, laser acupuncture has emerged as a promising alternative, combining the benefits of traditional acupuncture with the therapeutic effects of low-level laser therapy. This non-invasive technique uses laser energy to stimulate specific acupuncture points, promoting pain relief, reduced inflammation, improved blood circulation, and tissue regeneration.

This study aimed to evaluate the effects of laser acupuncture on pain, knee range of motion, and function in patients with patellofemoral pain syndrome. The researchers conducted a randomized, double-blind, placebo-controlled clinical trial involving 60 participants, predominantly young women between 18 and 25 years of age. Participants were randomly divided into two groups of 30 people each: Group A received true laser acupuncture applied at six specific knee points for 80 seconds per point with an energy of 4 joules, combined with a physical exercise program; Group B received sham laser acupuncture with the device turned off, also combined with the same exercise program.

Treatment was performed twice per week for four weeks, totaling eight sessions. The exercise program included isometric strengthening of the quadriceps, hip adduction, straight leg raise, squatting to 30 degrees of knee flexion, and stretching of the posterior thigh muscles, iliotibial band, and calf. The acupuncture points were selected based on previous scientific evidence, located around the knee joint to maximize therapeutic effects on patellofemoral pain.

Assessments were performed before and after the treatment period using validated and reliable instruments. Pain was measured using the visual analog scale, on which patients marked their pain intensity on a 10-cm line. Knee range of motion was assessed with a universal goniometer to measure flexion and extension. Knee function was evaluated using the Kujala scale, specifically developed to assess function in patients with patellofemoral pain, with scores ranging from 0 to 100 points.

The results demonstrated significant improvements in both groups after treatment, but the group that received true laser acupuncture showed superior benefits in all evaluated parameters. On the pain scale, the laser acupuncture group showed a 76.82% reduction in pain intensity, compared with 17.66% in the control group. This difference represents not only statistical significance but also clinical relevance, far exceeding the minimal clinically important improvement value established for this condition.

As for range of motion, the laser acupuncture group showed a 15.08% increase in knee flexion and a 62.88% improvement in extension, compared with increases of 4.95% and 16.97%, respectively, in the control group. On the functional assessment with the Kujala scale, the laser acupuncture group showed an improvement of 27.69% compared with 12.75% in the control group. All these differences were statistically significant and clinically relevant.

For patients and clinicians, these results offer important perspectives. Laser acupuncture appears to be a safe, non-invasive, and effective therapeutic modality for the treatment of patellofemoral pain syndrome. Throughout the study, only three participants experienced mild and temporary adverse effects, consisting of skin redness at the laser application site, which resolved spontaneously after a few hours without need for treatment. This technique may be especially valuable for patients seeking alternatives to nonsteroidal anti-inflammatory drugs or who wish to avoid more invasive procedures.

The combination of laser acupuncture with therapeutic exercises appears to enhance the effects of treatment, offering an integrated and conservative approach to this condition. Significant pain relief may facilitate patient participation in exercise programs, creating a positive cycle of functional improvement. In addition, the technique is well tolerated, does not produce heat or sound during application, and does not require the use of needles, making it suitable for patients who fear or have contraindications to traditional acupuncture.

It is important to recognize the limitations of this study for adequate interpretation of the results. The sample was composed predominantly of young women between 18 and 25 years of age, limiting the generalization of the findings to other populations, such as men or different age groups. The four-week treatment period, although demonstrating efficacy, may not be sufficient to assess long-term effects. In addition, the study did not include a follow-up period to verify the duration of the benefits obtained.

The diagnosis was based on clinical evaluation and plain radiographs, without the use of more advanced imaging such as magnetic resonance imaging or ultrasound, which could have increased diagnostic accuracy. Future studies should include more diverse populations, longer treatment periods, post-treatment follow-up, and more comprehensive diagnostic methods to consolidate these promising initial results.

In conclusion, this study provides robust scientific evidence that laser acupuncture, when combined with therapeutic exercises, offers significant benefits for patients with patellofemoral pain syndrome, exceeding the results obtained with exercise alone. This therapeutic modality represents a valuable option in the armamentarium of conservative treatments, offering effective pain relief, improvement in joint mobility, and functional recovery in a safe and well-tolerated manner.