Substantial Biomechanical Improvement by Extracorporeal Shockwave Therapy After Surgical Repair of Rodent Chronic Rotator Cuff Tears

Abstract

Background: Characteristics of chronic rotator cuff tears include continuous loss of tendon structure as well as tendon elasticity, followed by a high failure rate after surgical reconstruction. Several studies have already shown the beneficial effect of extracorporeal shockwave therapy (ESWT) on tissue regeneration in tendon pathologies. Hypothesis: ESWT improves biomechanical tendon properties as well as functional shoulder outcomes in chronic rotator cuff reconstruction in rodents. Study Design: Controlled laboratory study. Methods: After tendon detachment and 3 weeks of degeneration, a subsequent transosseous reattachment of the supraspinatus tendon was performed in 48 adult male Sprague-Dawley rats (n = 16 per group). Rodents were randomly assigned to 3 study groups: no ESWT/control group, intraoperative ESWT (IntraESWT), and intra- and postoperative ESWT (IntraPostESWT). Shoulder joint function, as determined by gait analysis, was assessed repeatedly during the observation period. Eight weeks after tendon reconstruction, the rats were euthanized, and biomechanical and gene expression analyses were performed. Results: Macroscopically, all repairs were intact at the time of euthanasia, with no ruptures detectable. Biomechanical analyses showed significantly improved load-to-failure testing results in both ESWT groups in comparison with the control group (control, 0.629; IntraESWT, 1.102; IntraPostESWT, 0.924; IntraESWT vs control, P≤ .001; IntraPostESWT vs control, P≤ .05). Furthermore, functional gait analyses showed a significant enhancement in intensity measurements for the IntraPostESWT group in comparison with the control group ( P≤ .05). Gene expression analysis revealed no significant differences among the 3 groups. Conclusion: Clearly improved biomechanical results were shown in the single-application and repetitive ESWT groups. Furthermore, functional evaluation showed significantly improved intensity measurements for the repetitive ESWT group. Clinical Relevance: This study underpins a new additional treatment possibility to prevent healing failure. Improved biomechanical stability and functionality may enable faster remobilization as well as an accelerated return to work and sports activities. Furthermore, as shockwave therapy is a noninvasive, easy-to-perform, cost-effective treatment tool with no undesired side effects, this study is of high clinical relevance in orthopaedic surgery. Based on these study results, a clinical study has already been initiated to clinically confirm the improved functionality by ESWT.

Extracorporeal shock wave promotes activation of anterior cruciate ligament remnant cells and their paracrine regulation of bone marrow stromal cells’ proliferation, migration, collagen synthesis, and differentiation

“… 23 , 24 ESW treatment potentiates soft tissue regeneration. 25 - 27 Studies have shown that ESW treatment activates proliferation, migration, and gene expression in different cells. 28 - 31 ESW has been proposed as a non-invasive treatment that potentiates graft healing after ACL reconstruction surgery.…”

A Combination Treatment of Raloxifene and Vitamin D Enhances Bone-to-Tendon Healing of the Rotator Cuff in a Rat Model

“…Most rat studies involving rotator cuff healing have a limitation that there is no baseline data for the intact tendon-to-bone junction. 6,15,25,31,32…”

Zoledronic Acid Substantially Improves Bone Microarchitecture and Biomechanical Properties After Rotator Cuff Repair in a Rodent Chronic Defect Model

“…To ensure a proper fixation of tendon tissue, the Prolene suture was left in situ and used for RC reconstruction later. 19 The deltoid muscle was readapted and wound closure was performed with a No. 5.0 Vicryl suture (Ethicon).…”

“…The distal part of the humerus was then potted in polymethyl methacrylate. 19 Biomechanical testing was performed at room temperature. The SSP tendon was gripped in a specially designed sandpaper clamp at direct proximity of the insertion site of the tendon.…”