The Journal of Bone and Joint Surgery, Vol 73, Issue 6 868-881, Copyright © 1991 by Journal of Bone and Joint Surgery, Inc
The revascularization of healing flexor tendons in the digital sheath. A vascular injection study in dogs
RH Gelberman, V Khabie and CJ Cahill
Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston.
The role of revascularization in the nutritional support of repair of the
flexor tendons is not completely understood. To explore the extent to which
intrasynovial flexor tendons revascularize after transection and suture, a
vascular injection study was carried out in a canine model. The tendons to
the second and fifth digits of the forepaw in twelve adult mongrel dogs
were transected and repaired. There were twenty-four experimental tendons
and twenty-four normal tendons. The limb was placed in a polyurethane
shoulder-spica cast, and the paw was treated with immediate protected
passive mobilization. At three, seven, ten, seventeen, and twenty-eight
days, the animals were killed and the major arteries supplying both the paw
that had been operated on (left) and the contralateral normal paw (right)
were injected with 200 milliliters of India ink. Segments of repaired and
normal tendons were then clarified by a modified Spalteholz technique. The
normal tendons demonstrated a well developed mesotenon that provided
vascularization of the proximal portion of the flexor digitorum profundus
tendon. A consistent three-cubic-millimeter avascular intrasynovial portion
of tendon was noted. Distally, vessels arose from the vinculum breve,
supplying the terminal twenty millimeters of tendon substance. In the
experimental tendons, longitudinal and transverse clarified sections showed
consistent revascularization of the site of repair by proximal vessels in
the absence of ingrowth of peripheral adhesions. Vessels in the epitenon
progressively extended for a distance of ten millimeters, through normally
avascular regions, to reach the site of repair by the seventeenth
postoperative day. Intratendinous vessels about the site of repair
consistently originated from surface vessels, rather than from extensions
of pre-existing intratendinous vessels. New vessels penetrated all areas,
including the normally avascular volar segments of tendon, irrespective of
previous topical zones of avascularity. Proximal vascular plexi were
characterized by large tortuous vessels with frequent circuitous branches.
More distal vessels had a longitudinally oriented, feathery appearance.