RESEARCH - Corticosteroids reduce the tensile strength of isolated collagen fascicles

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Am J Sports Med. 2006 Dec;34(12):1992-7. Epub 2006 Aug 10.

Corticosteroids reduce the tensile strength of isolated collagen

fascicles.Haraldsson BT, Langberg H, Aagaard P, Zuurmond AM, van El B,

Degroot J, Kjaer M, Magnusson SP.

Institute of Sports Medicine Copenhagen, Bispebjerg Hospital,

Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark.

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 mum) 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.

PMID: 16902230

http://www.ncbi.nlm.nih.gov/pubmed/16902230

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