The microvasculature in the equine distal phalanx: implications for fracture healing.

OBJECTIVES: To describe the intra-osseous microvasculature of the distal phalanx of the equine forelimb with regard to its potential clinical relevance. METHODS: Eleven clinically normal equine forelimbs were used from six adult horses (range: 4 to 18 years old) euthanatized for reasons unrelated to lameness. In each limb the median artery was catheterized at the level of the carpus and India ink was injected under constant manual pressure. The limbs were frozen and 5 mm thick sections of the foot were cut in the sagittal, coronal, or transverse planes on a band saw. The sections were fixed in 10% formalin and cleared using a modified Spalteholz technique. Once cleared, the sections were photographed and the microvascular anatomy identified. RESULTS: The vascular injections revealed a rich intra-osseous microvascular supply of the distal phalanx originating from the medial and lateral palmar digital arteries. In addition, numerous smaller vessels from the terminal arch, formed by anastomosis of the medial and lateral palmar digital arteries, could be seen branching into the distal aspects of the distal phalanx. This distal portion of the distal phalanx appeared more densely vascularized than the proximal part in all specimens examined. CLINICAL SIGNIFICANCE: The increased vascularity demonstrated in the distal portion of the distal phalanx appears to correlate with improved fracture healing reported in this area. This may also explain why healing fractures which involve both the distal and proximal portions of the distal phalanx have been described as progressing from distal-to-proximal.

Nonvascularized toe phalangeal transfer and distraction lengthening for symbrachydactyly.

Symbrachydactyly describes a spectrum of congenital hand differences consisting of digital loss resulting in fused short fingers. As the principles for distraction lengthening have evolved, the technique of nonvascularized toe phalangeal transfer to the hand with shortened digits has provided patients with improved outcomes. Nonvascularized toe phalanx to hand transplant with distraction lengthening restores functional length to a skeletally deficient, poorly functioning hand while maintaining an overlying layer of vascular and sensate tissue. The primary goal is improvement of digital length to enhance mechanical advantage and prehension. We describe the technique of nonvascularized toe phalangeal transfer and distraction lengthening for symbrachydactyly, including the following steps: nonvascularized proximal toe phalanx harvest, toe phalanx transfer to hand, pin placement, osteotomy, and closure.

Creation of a four-joint-digit after second toe to digit transplantation: restoration of form and function.

The authors describe the non-orthotopic insertion of an Ascension two-piece pyrocarbon proximal interphalangeal joint at the osteosynthesis level of bilateral toe-to-digit transplantations in an attempt to restore both anatomic length and composite fist formation after traumatic multidigit loss. The non-orthotopic joints provided an additional 30 and 35 degrees of stable flexion to the reconstructed index and longs digits enabling the patient to form a composite fist. There was no evidence of joint instability or loosening. Total active motion was 240 and 235 degrees at the index and long fingers, respectively. Creation of two four joint fingers by the addition of non-orthotopic joints in toe-to-digit reconstructions successfully restored form and function after multidigit loss.

Blood supply to the first metatarsal head and vessels at risk with a chevron osteotomy.

BACKGROUND: Chevron osteotomy, a commonly performed procedure for the treatment of hallux valgus, results in osteonecrosis of the first metatarsal head in 0% to 20% of cases. The aim of this study was to map out the arrangement of the vascular supply to the first metatarsal head and its relationship to the limbs of the chevron osteotomy. METHODS: Ten cadaveric lower limbs were injected with an India ink-latex mixture, and the feet were dissected to assess the blood supply to the first metatarsal head. The dissection was carried out by tracing the branches of the dorsalis pedis and posterior tibial vessels. A distal chevron osteotomy was mapped, with the limbs of the osteotomy set at an angle of 60 degrees from the geometric center of the first metatarsal head. The relationship of the limbs of the osteotomy to the blood vessels was recorded. RESULTS: The first metatarsal head was found to be supplied by branches from the first dorsal metatarsal, first plantar metatarsal, and medial plantar arteries. The first dorsal metatarsal artery was the dominant vessel among the three arteries in eight specimens. All of the vessels formed a plexus at the plantar-lateral aspect of the metatarsal neck, just proximal to the capsular attachment, with a varying number of branches from the plexus then entering the metatarsal head. The plantar limb of the proposed chevron cuts exited through this plexus of vessels in all specimens. Contrary to the widely held view, only minor vascular branches could be found entering the dorsal aspect of the neck. CONCLUSIONS: The identification of the plantar-lateral corner of the metatarsal neck as the major site of vascular ingress into the first metatarsal head suggests that constructing the chevron osteotomy with a long plantar limb exiting well proximal to the capsular attachment may decrease the postoperative prevalence of osteonecrosis of the first metatarsal head.

Vascularized bone blocks from the toe phalanx to solve complex intercalated defects in the fingers.

PURPOSE: Vascularized bone transplants resist infection and allow rapid healing but keeping small bony segments vascularized, as needed for a finger defect, is a challenge. The purpose of this article is to present a cohort of patients with traumatic intercalated compound bony defects in the fingers that were reconstructed by a vascularized toe phalanx (or part of a phalanx) in a single stage. METHODS: Eight patients were treated with an intercalary vascularized bone graft that included a part of the proximal phalanx (3 patients), most of the middle phalanx (4 patients), or a portion of each phalanx (1 patient) of a second toe (totaling 9 bone blocks). There was an associated soft-tissue defect in each patient, an infection in 6 patients, and cartilage loss in 4 patients. The toes were pedicled on the proper digital artery (6 patients) or a segment of the first dorsal metatarsal artery (2 patients). A mean length of 12 mm of vascularized bone was transferred. The associated skin island varied from a minimum of 2 x 1 cm to a maximum of 5 x 3 cm. Bleeding from all of the bone surfaces was evidenced once the clamps were released. The homolateral digital nerve and the contralateral neurovascular pedicle of the toe were kept in place. The toe defect was treated by soft-tissue arthroplasty or arthrodesis. No toe was amputated. RESULTS: Radiologic bony union was evident at 4 to 6 weeks, except in 1 patient with an acute infection whose distal union failed to unite at 6 weeks because the infection recurred. Finger length loss averaged 3 mm. All patients returned to their preoperative occupation. CONCLUSIONS: In this group of patients the toe phalanx reliably maintained its vascularization, allowing us to solve compound osteocutaneous defects in the fingers in a single stage. Donor site morbidity was minimal.