Abstract
Background:
Tendon–bone insertion (TBI) consists of both hard and soft tissues. TBI injury with delayed repair is not uncommon. High-dose extracorporeal shockwave (ESW) is effective for treating nonunion fracture, whereas low-dose ESW is used for tendinopathy therapy. The dosing effect of ESW on delayed TBI healing is lacking.
Hypothesis:
Low-dose ESW might have a healing enhancement effect comparable to that of high-dose ESW in treating delayed TBI healing.
Study Design:
Controlled laboratory study.
Methods:
Partial patellectomy was adopted to create a delayed TBI healing model by shielding the healing interface between tendon and bone. Ninety-six female New Zealand White rabbits with unilateral delayed TBI healing at the knee joint were divided into 3 groups: controls, low-dose ESW (LD-ESW; 0.06 mJ/mm2, 4 Hz, 1500 impulses), and high-dose ESW (HD-ESW; 0.43 mJ/mm2, 4 Hz, 1500 impulses). The TBI shielding was removed at week 4 after partial patellectomy, followed by treatment with control or ESW at week 6. The rabbits were euthanized at week 8 and week 12 for radiological, microarchitectural, histological, and mechanical assessments of healing tissues.
Results:
Radiologically, both the LD-ESW group and the HD-ESW group showed larger new bone area than the controls at week 8 and week 12. Microarchitectural measurements showed that the LD-ESW and HD-ESW groups had larger new bone volume than the controls at week 12. Histological assessments confirmed osteogenesis enhancement. Both the LD-ESW and HD-ESW groups showed significantly higher failure load at the TBI healing complex than the control group at week 12. No significant difference was detected between the 2 ESW treatment groups at week 8 or week 12.
Conclusion:
Extracorporeal shockwave, a unique noninvasive physical modality, had similar effects between the low and high dose for treating delayed TBI healing.
Clinical Relevance:
Low-dose ESW for TBI delayed healing might be more desirable and have better compliance in clinical applications.
Keywords
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