Gelberman (1983) used light, scanning, and transmission electron microscopy to compare flexor tendon healing in dogs after either total immobilization or early controlled passive mobilization. The study asked whether mobilization changes the fundamental cellular mechanism of repair — not just the functional outcome.
For decades, adhesion ingrowth from the digital sheath was considered unavoidable after flexor tendon repair — tendon cells were thought incapable of self-repair, making extrinsic fibroblast invasion the only healing mechanism available.
This paper proved that early controlled passive motion fundamentally changes HOW a tendon heals: mobilized tendons heal via their own epitenon cells, restoring a smooth gliding surface by day 10 and maintaining it adhesion-free through 42 days.
In practice, this is why zone II flexor tendon repairs are immediately started on Duran-protocol passive mobilization (40–50 passive cycles daily from postoperative day 1), and why immobilization after repair is considered a driver of poor digital function rather than a safe default.
The threshold from Duran — cited in this paper's mechanistic discussion — is worth memorizing: just 3–5 mm of tendon excursion is sufficient to prevent firm adhesion formation within the sheath.
Gelberman (1983) used light, scanning, and transmission electron microscopy to compare flexor tendon healing in dogs after either total immobilization or early controlled passive mobilization. The study asked whether mobilization changes the fundamental cellular mechanism of repair — not just the functional outcome.
For decades, adhesion ingrowth from the digital sheath was considered unavoidable after flexor tendon repair — tendon cells were thought incapable of self-repair, making extrinsic fibroblast invasion the only healing mechanism available.
This paper proved that early controlled passive motion fundamentally changes HOW a tendon heals: mobilized tendons heal via their own epitenon cells, restoring a smooth gliding surface by day 10 and maintaining it adhesion-free through 42 days.
In practice, this is why zone II flexor tendon repairs are immediately started on Duran-protocol passive mobilization (40–50 passive cycles daily from postoperative day 1), and why immobilization after repair is considered a driver of poor digital function rather than a safe default.
The threshold from Duran — cited in this paper's mechanistic discussion — is worth memorizing: just 3–5 mm of tendon excursion is sufficient to prevent firm adhesion formation within the sheath.