RESEARCH - Steroids reduce the tensile strenth of isolated collagen fascicles

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Am J Sports Med. 2006 Aug 10; [Epub ahead of print]

Corticosteroids Reduce the Tensile Strength of Isolated Collagen Fascicles.

Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, Copenhagen,

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 microm) 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/entrez/query.fcgi?db=pubmed & cmd=Retrieve & dopt=Abstra\

ctPlus & list_uids=16902230

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