Strength and histological characteristics of periosteal fixation to bone after elevation

Loss of brow elevation in the early postoperative period has been well documented; however, there has been no study quantifying the minimum time necessary to achieve lasting brow elevation. Previous work in our laboratory has demonstrated that complete readherence of periosteum to bone can take 12 weeks to occur after periosteal elevation. The correlation between adherence and the development of strength has never been examined.

To correlate histological characteristics of raised forehead periosteum with the strength of the periosteum-bone union postoperatively.

Eighteen New Zealand white rabbits.

Rabbit foreheads were elevated in a subperiosteal plane and the flap reapproximated with chromic sutures. Animals were killed at 14, 28, 45, 63, or 84 days postoperatively, and all tissue superficial to the periosteum removed. The tension required to avulse sections of periosteum was then measured. Skulls were then sectioned and prepared for histological analysis of remaining periosteum. Avulsion forces and histological findings were compared with those unoperated-on controls.

The forces necessary to avulse periosteum in the 14- and 28-day groups were significantly lower than for control animals; values at 45, 63, and 84 days were not significantly different from control animals. Healing periosteum displayed varying degrees of thickness, cellularity, edema, and vascular congestion. These features peaked at 28 days postoperatively then gradually resolved to near-control values by 84 days. Significant periosteal-to-bone contact did not appear until 45 days postoperatively.

Our results promote the use of methods of brow fixation that support mobilized soft tissues for a minimum of 6 weeks, until the elevated periosteum has significantly readhered to the underlying bone.