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This Article Full Text Full Text (PDF) All Versions of this Article: 34/12/1992    most recent 0363546506290402v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Request Reprints Citing Articles Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Haraldsson, B. T. Articles by Magnusson, S. P. Search for Related Content PubMed PubMed Citation Articles by Haraldsson, B. T. Articles by Magnusson, S. P. Related Collections Animal studies Histology

Corticosteroids Reduce the Tensile Strength of Isolated Collagen Fascicles

Bjarki Thor Haraldsson, MS^*, Henning Langberg, MS, PhD^*, Per Aagaard, MS, PhD^*,, Anne-Marie Zuurmond, PhD, Benno van El, BSc, Jeroen DeGroot, PhD, Michael Kjær, MD, DSc^* and S. Peter Magnusson, PT, DSc^*,,||

From the ^* Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, Copenhagen, Denmark, Institute of Sports Exercise and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark, Business Unit Biomedical Research, TNO Quality of Life/TNO Pharma, Leiden, Netherlands, and the ^|| Department of Physiotherapy, Bispebjerg Hospital, Copenhagen, Denmark

Address correspondence to S. Peter Magnusson, DSc, Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark (e-mail: P.Magnusson{at}mfi.ku.dk).

Background: Overuse tendon injuries are frequent. Corticosteroid injections are commonly used as treatment, although their direct effects on the material properties of the tendon are poorly understood.

Purpose: To examine the influence of corticosteroids on the tensile strength of isolated collagen fascicles.

Study Design: Controlled laboratory study.

Methods: Single strands (300–500 µm) of rat-tail collagen fascicles were incubated in either high (1 mL of 40 mgmL^–1 mixed with 0.5 mL saline 9%) or low (1 mL of 40 mgmL^–1 mixed with 2 mL saline 9%) concentration of methylprednisolone acetate (Depomedrol) for 3 or 7 days, while the control segment from the same fascicle was kept in saline (N = 64). After the incubation period, the fascicles underwent displacement to failure in a mechanical test rig at 0.13 mm/s, and thereafter hydroxylysyl pyridinoline and lysyl pyridinoline cross-link content was evaluated in a high-performance liquid chromatography system. Data for each group were analyzed with a 2-way analysis of variance (time x incubation) for ultimate stress (mean ± standard deviation).

Results: In the high-concentration groups, strength was reduced after 3 (16.6 ± 4.6 MPa) and 7 (8.6 ± 1.7 MPa) days compared to the controls (30.2 ± 5.0 MPa and 25.6 ± 4.6 MPa, respectively; P < .05). In the low-concentration groups, strength was reduced after 3 (12.0 ± 3.1 MPa) and 7 days (10.9 ± 2.5 MPa) compared to the controls (31.5 ± 5.0 MPa and 32.4 ± 5.6 MPa, respectively; P < .05). The amount of cross-linking was unaffected by the intervention.

Conclusion: Data show that the tensile strength of isolated fascicles is markedly reduced after 3- and 7-day incubation in both high and low concentration of corticosteroids, although the observed effect on whole tendon remains unknown.

Clinical Relevance: Corticosteroids may weaken specific regions of the injected tendon and leave it more prone to rupture. This weakening effect is manifested in the individual collagen fascicles that constitute the tendon.

Key Words: corticosteroids • collagen fascicle • tensile strength • collagen cross-links