The cellular effect of a single interrupted suture on tendon

The effects on cell and matrix morphology of a single interrupted suture are described in rabbit (vascular) and mouse (avascular) digital flexor tendons. This model of tendon injury is reproducible and suitable for quantitative histological analysis. Tendons analysed at day 1, 3, 5, 7 and 14 after wounding demonstrated a well-demarcated "acellular zone" around the suture within 24 hours and persisting over 14 days. The placement of an untied suture in tendon did not produce this effect but tying and releasing the tied knot did. The rapidity of onset suggests that cells move from the zone of injury into less mechanically strained tissue. The acellular zone was apparent in rabbit hind paw flexor tendon which is vascularised and the corresponding tendon in mouse which has no intrinsic blood vessels. This phenomenon highlights biological events that must be considered in parallel with the current trend for multistrand locking flexor tendon suture repairs.