Excessive apoptosis in patellar tendinopathy in athletes

Effects of low-level laser therapy and eccentric exercises in the treatment of recreational athletes with chronic achilles tendinopathy

BACKGROUND

Eccentric exercises (EEs) are recommended for the treatment of Achilles tendinopathy, but the clinical effect from EE has a slow onset.

HYPOTHESIS

The addition of low-level laser therapy (LLLT) to EE may cause more rapid clinical improvement.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 52 recreational athletes with chronic Achilles tendinopathy symptoms were randomized to groups receiving either EE + LLLT or EE + placebo LLLT over 8 weeks in a blinded manner. Low-level laser therapy (lambda = 820 nm) was administered in 12 sessions by irradiating 6 points along the Achilles tendon with a power density of 60 mW/cm(2) and a total dose of 5.4 J per session.

RESULTS

The results of the intention-to-treat analysis for the primary outcome, pain intensity during physical activity on the 100-mm visual analog scale, were significantly lower in the LLLT group than in the placebo LLLT group, with 53.6 mm versus 71.5 mm (P = .0003) at 4 weeks, 37.3 mm versus 62.8 mm (P = .0002) at 8 weeks, and 33.0 mm versus 53.0 mm (P = .007) at 12 weeks after randomization. Secondary outcomes of morning stiffness, active dorsiflexion, palpation tenderness, and crepitation showed the same pattern in favor of the LLLT group.

CONCLUSION

Low-level laser therapy, with the parameters used in this study, accelerates clinical recovery from chronic Achilles tendinopathy when added to an EE regimen. For the LLLT group, the results at 4 weeks were similar to the placebo LLLT group results after 12 weeks.

VGluT2 expression in painful Achilles and patellar tendinosis: evidence of local glutamate release by tenocytes

The pathogenesis of chronic tendinopathy is unclear. We have previously measured high intratendinous levels of glutamate in patients with tendinosis, suggesting potential roles of glutamate in the modulation of pain, vascular function, and degenerative changes including apoptosis of tenocytes. However, the origin of free glutamate found in tendon tissue is completely unknown. Surgical biopsies of pain-free normal tendons and tendinosis tendons (Achilles and patellar) were examined immunohistochemically using antibodies against vesicular glutamate transporters (VGluT1 and VGluT2), as indirect markers of glutamate release. In situ hybridization for VGluT2 mRNA was also conducted. Specific immunoreactions for VGluT2, but not VGluT1, could be consistently detected in tenocytes. However, there were interindividual variations in the levels of immunoreactivity. The level of immunoreaction for VGluT2 was higher in tendinosis tendons compared to normal tendons (p < 0.05). In situ hybridization of VGluT2 demonstrated that mRNA was localized in a similar pattern as the protein, with marked expression by certain tenocytes, particularly those showing abnormal appearances. Reactivity for VGluT1 and -2 was absent from nerves and vessel structures in both normal and painful tendons. The current data demonstrate that tenocytes may be involved in the regulation of extracellular glutamate levels in tendons. Specifically, the observations suggest that free glutamate may be locally produced and released by tenocytes, rather than by peripheral neurons. Excessive free glutamate is expected to impact a variety of autocrine and paracrine functions important in the development of tendinosis, including tenocyte proliferation and apoptosis, extracellular matrix metabolism, nociception, and blood flow.

A "polypill" for acute tendon pain in athletes with tendinopathy?

Acute tendon pain in athletes is a condition that is difficult to manage. There are few treatment options that give adequate pain relief and have a theoretical basis for efficacy. We report the use of a novel "polypill" for tendon pain, and provide evidence for the basis for its use. We present it to stimulate discussion and research into a new area of tendinopathy.