Low intensity pulsed ultrasound increases the matrix hardness of the healing tissues at bone-tendon insertion - A partial patellectomy model in rabbits

Ling Qin, Pikkwan Fok, Hongbin Lu, San-Qiang Shi, Yang Leng, Kwoksui Leung

Research output: Journal article publicationJournal articleAcademic researchpeer-review

52 Citations (Scopus)


Background. This study evaluated the low intensity pulsed ultrasound enhancement on matrix hardness of the healing tissues at the bone-tendon junction. Methods. Sixteen 18 week-old mature female rabbits were used. An established transverse partial patellectomy was performed at the distal one-third of the patella. Animals were then divided according to their body weight into ultrasound group (n = 8) with daily treatment of low intensity pulsed ultrasound and control group (n = 8) without ultrasound treatment. Animals were euthanized at week 8 and 16 postoperatively to evaluate the radiographic new bone formation and the Vickers hardness of the matrix of the healing tissues at the bone-tendon junction. Findings. (1) Comparing with the control group, the anterior-posterior area of the new bone in the ultrasound treated group was found on average to be 3.0 and 3.1 times greater at week 8 and 16, respectively (P < 0.01). (2) The Vickers hardness of the new bone in ultrasound group was 11.3% (P < 0.05) significantly lower at week 8 but 20.0% (P < 0.05) significantly higher at week 16 as compared with that of the control group. (3) The Vickers hardness of the newly regenerated fibrocartilage zone, healing tendon, and cartilaginous metaplasia in ultrasound group was found higher than the control group at both week 8 and 16, but the difference was significant at week 16 only, being 44.1% (P < 0.05), 20.1% (P < 0.01), and 46.4% (P < 0.01) higher, respectively. Interpretation. The preliminary findings suggested for the first time that low intensity pulsed ultrasound treatment resulted in the enhancement of the matrix hardness in new bone, fibrocartilage, cartilaginous metaplasia, and healing tendon at the healing bone-tendon junction. These findings can be extrapolated into clinical practice, i.e. the more rapid healing induced by low intensity pulsed ultrasound, the earlier mobilization of the affected joint. The beneficial effects on prevention of the musculoskeletal deterioration resulting from the prolonged immobilization would be therefore expected.
Original languageEnglish
Pages (from-to)387-394
Number of pages8
JournalClinical Biomechanics
Issue number4
Publication statusPublished - 1 May 2006


  • Bone-tendon insertion healing
  • Low intensity pulsed ultrasound (LIPUS)
  • Micro-indentation

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine

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