This rabbit study tested whether low, physiologic doses of corticosteroid injected directly into normal Achilles tendon weaken it. It correlated tensile failing-strength testing with light and scanning electron microscopy from 48 hours to 6 weeks. The goal was to settle whether steroid harms normal tendon at doses far below the massive doses used in earlier studies.
When you inject steroid for tendinopathy, aim in or around the sheath and avoid driving the needle into the tendon substance. This study shows that direct intratendinous steroid weakens a normal tendon by roughly 35% for up to two weeks through collagen necrosis, and the weakening is not dose-dependent.
That two-week window explains the classic teaching to counsel patients against vigorous activity or loading after a peritendinous steroid injection. It also grounds the caution against repeated injections into the same site, since each injection creates a fresh vulnerable period.
The study reconciled a real debate: earlier work claiming no harm had injected under the paratenon, whereas harm appears when steroid is concentrated directly in the tendon. Steroid gives pain relief but buys a temporary strength deficit, so protect the tendon until it recovers.
This rabbit study tested whether low, physiologic doses of corticosteroid injected directly into normal Achilles tendon weaken it. It correlated tensile failing-strength testing with light and scanning electron microscopy from 48 hours to 6 weeks. The goal was to settle whether steroid harms normal tendon at doses far below the massive doses used in earlier studies.
When you inject steroid for tendinopathy, aim in or around the sheath and avoid driving the needle into the tendon substance. This study shows that direct intratendinous steroid weakens a normal tendon by roughly 35% for up to two weeks through collagen necrosis, and the weakening is not dose-dependent.
That two-week window explains the classic teaching to counsel patients against vigorous activity or loading after a peritendinous steroid injection. It also grounds the caution against repeated injections into the same site, since each injection creates a fresh vulnerable period.
The study reconciled a real debate: earlier work claiming no harm had injected under the paratenon, whereas harm appears when steroid is concentrated directly in the tendon. Steroid gives pain relief but buys a temporary strength deficit, so protect the tendon until it recovers.