It is well documented that a conventional bone graft is a dead piece of bone, which gets is replaced gradually by creeping substitution from the adjoining bone, whenever and wherever it is being used. The healing of a bone defect, whether small or big, entirely depends upon regenerating power of the recipient bone.
Vascularized bone graft is a live piece of bone with intact endosteal and periosteal blood supply. With micro-vascular anastomosis of the vascular pedicle to a major recipient vessel, the transplanted segment of the bone behaves like a denervated segmental fracture, which heals by osteoblastic activity at both ends. The medullary cavity gets unified and continuous and the grafted bone acquires the size and the strength matching to the recipient bone.
Radioisotope bone scan is considered to be a definite test for vascularity and osteoblastic activities of the graft, which becomes positive within 24 – 48 hours. The utility of Vascularized bone grafts in clinical practice is unlimited, bringing in new philosophy of reconstruction for a variety of difficult bone defects. Conditions benefited most are congenital pseudo-arthrosis, limb salvage following large bone tumor excision or hypoplasia / Aplasia of the Ramus of the mandible, or Diaphyseal segment of long bones. Use of Vascularized fibular graft to re-vascularize the head of the femur, following avascular necrosis of the head, has been a new promising concept, which may be a substitute to a total hip replacement as more physiologic approach. Transfer of a Vascularized hyaline cartilage in Vascularized total joint transfers have already surpassed silastic joint replacement in small joints of hand.
Being able to maintain growth at the epiphyses, it has proved to be a good procedure for temporo-mandibular joint Ankylosis with or without hypoplasia, wherein Hemi-joint or head of the fibula has been used. Similar principle has been applied to radial club hand, wherein attempts are being made to construct the lower radio-ulnar-carpel joint by epiphyses transfer.
Improved understanding of the process of motor and sensory re-innervation of a striated muscle, following neuro-vascular microsurgical transfer have encouraged a free functional live muscle transfer (FFMT) procedure. Conditions benefited most are:
Muscles most commonly used are Gracilis, Latissimus Dorsi, Serratus anterior and/or Pectoralis minor. All these muscle have a long and constant dominant vascular pedicle, a rich network of motor neural supply and least functional deficit following transfer. In children, inner diameter of the dominant vascular pedicle could be as minute as 0.3 mm. Shorter the ischaemia time of the transferred muscle is, better are functional return of motor power. It has been well documented that, if the muscle ischaemia time is less than 50 minutes during the transfer, functional power may become as strong as Grade IV. Functional muscle transfer is never to be considered as first choice in acute facial or brachial plexus paralysis, but has a definite place in cases of long standing, even up to 20 years.
Dynamic replacement of the mimetic muscles of the face, with synchronized movements of both normal and paralyzed sides, have been made possible by microsurgical Cross Face Nerve Grafts (CFNG), followed by Functional Muscle Transfer (FFMT), using either Gracilis or pectoralis minor muscles. The nerve from the normal side controls movements of the transferred muscle, thereby a synchronized smile is assured.
Pre-ganglionic root avulsion injuries of brachial plexus are considered to be completely irreparable. The paralyzed limb is doomed either for uselessness or an amputation. Micro neural redistribution of remaining intact roots of the plexus and / or utilization of sparable adjoining motor nerves like Accessory spinal nerve, Dorsal branch of C-4 root, motor branches of the Inter-costal nerves (T-3 to T-9) and ipsi or contra-lateral lateral pectoral nerves, offer reasonable functional recovery in most of the these plexus injuries. Use of contra-lateral C-7 Root for neurotization the plexus with or without functional muscle transfer has also been demonstrated. Following neural redistribution work and based on the recovery in muscle power, either an adjacent or a distant functional live muscle transfer is considered. A combination of latissimus dorsi muscle and / or Gracilis with adductor longus muscle gives a reasonable stability to the shoulder joint. Gracilis muscle is used for providing flexion / extension of the elbow, wrist and finger joints in selected cases.
As functional rehabilitation with FFMT is neither based on local muscle nor on original nerve supply, there is no time limit for performing these procedures, however results are expected to be better in younger age group.
In recent years, a functional latissimus dorsi muscle has been used for re-vascularization of a severely damaged myocardium, wherein a coronary bypass surgery may not be possible or advocated. The transferred latissimus dorsi muscle is reconditioned to act and to contract like a myocardium with the help of a pace maker, thus making an artificial biological heart.
In situations like post-traumatic soft tissue loss involving either flexor or extensor group of muscles, or following a wide tumor excisions or in neuro-vascular insufficiency like Volkmann’s ischaemic contracture, a free functional muscle transfer has provided a new hope for good functional rehabilitation.
Microsurgical free functional tissue transfers have opened up a new chapter and revolutionized Reconstructive Surgery. It has added one very powerful tool in the armamentarium of Plastic and Reconstructive Surgeons.
Microsurgery has scaled a real height in a relatively short span of time. It has got an extremely vast clinical field and a promising future. Soon we may be able to microsurgical procedure through a Laparoscope for problems of infertility.
Dr. Ashok K. Gupta
Honorary Plastic and Microsurgeon.
Bombay Hospital and Medical Resch. Centre.
Bombay Suite No. 16, II floor.
Laud Mansion, 21 M. Karve Road,
Bombay – 400 004