J Orthop Sports Phys Ther. 2008;38(9):572-577, published online 29 May 2008. doi:10.2519/jospt.2008.2779

STUDY DESIGN: Randomized controlled prospective experimental study. OBJECTIVES: To examine the effects of transcutaneous low-voltage microamperage stimulation (LVMAS) on the mechanical strength of Achilles tendon repair in rats at 4 weeks after injury. BACKGROUND: Understanding the effect of LVMAS on the healing of injured tendons is hampered by the lack of related experimental studies, especially from the aspect of biomechanical outcome measures. METHODS AND MEASURES: Fourteen, 3-month-old, male Sprague-Dawley rats received surgical transection to the medial portion of their right Achilles tendon. The rats were divided into a LVMAS group (n=7) and control group (n=7). From day 6 post-surgery onwards, the LVMAS group received daily treatment of transcutaneous LVMAS (2.5 V, 100 μA/cm², 10 pulses per second, positive current) for a total of 22 sessions, while the control group received placebo LVMAS by the same investigator during that period. On day 31, the Achilles tendons were harvested for biomechanical testing for load relaxation, stiffness, and ultimate tensile strength along the longitudinal direction. RESULTS: The normalized Achilles tendon ultimate tensile strength of the LVMAS group (mean ± SD, 110.5% ± 25.0%) was higher than the control group (75.3 ± 20.8%) (P=.014), but no significant difference was found in normalized stiffness and load relaxation between the 2 groups (P=.239 and .350, respectively). CONCLUSION: The results of this study suggest that the administration of transcutaneous LVMAS could improve healing and consequently the tensile strength of partially transected Achilles tendons of rats at 4 weeks after injury.

J Orthop Sports Phys Ther. 2007;37(7):399-403, published online 16 April 2007.  doi:10.2519/jospt.2007.1412

KEY WORDS: asymmetrical biphasic, biomechanical testing, electrical stimulation, tendon injuries

Study Design: Within-subject repeated-measures study. Objectives: To examine the immediate effects of counterforce forearm brace on isokinetic strength, stretch reflex, passive stretching pain threshold of the wrist extensors, and proprioception of the wrist in subjects with lateral humeral epicondylosis for different strap tensions of a forearm brace. Background: Counterforce forearm bracing has been used for treating lateral humeral epicondylosis, but the effect of brace tension has not been well reported. Methods and Measures: Fifteen subjects diagnosed with lateral humeral epicondylosis on their dominant arm were tested under 4 randomized conditions: (1) no brace, (2) brace with minimal tension, (3) brace with 25-N tension, and (4) brace with 50-N tension. The tests included isokinetic wrist extensors strength, passive stretching force in wrist flexion to elicit pain in the wrist extensors, wrist proprioception, and stretch reflex latency of the extensor carpi ulnaris. A repeated-measures MANOVA was used to analyze the data and significant results were further analyzed with post hoc linear contrasts (α = .05). Results: Among the 4 conditions, significant differences were found in wrist proprioception (P = .032) and pain threshold to passive stretching of the wrist extensors (P = .05), but were not found in wrist extension isokinetic strength and stretch reflex latency of the extensor carpi ulnaris. Conclusion: A forearm counterforce brace, as applied in this study, affects wrist joint proprioception and increases the pain threshold to passive stretching of the wrist extensors in subjects with lateral humeral epicondylosis, but it has no effect on wrist extensor strength and stretch reflex latency of the extensor carpi ulnaris.

J Orthop Sports Phys Ther. 2004;34(2):72-78. doi:10.2519/jospt.2004.0992

Key Words: orthosis, pain, proprioception, tennis elbow