GRAFTING POSTERIOR TIBIAL NERVE WITH IPSILATERAL SURAL NERVE CABLES IN LEG REPLANTATION – A COMMON SENSE APPROACH

INTRODUCTION

Microscopic surgery of the foot and leg including replantation was widely reported in 1970’s (2).

Initially, the enthusiasm for replantation at all levels was high, whether amputation involved both legs or their distal parts (13, 14).

However, improvements in quality of the lower limb prosthesis followed by reports of complications of replantations (6) brought a plateau in this enthusiasm. Experience has shown that viability should not be taken as the only criteria in decision making for reconstruction versus amputation (4). A functional extremity and an acceptable length of time for rehabilitation are considered equally important. In order to achieve this, therapy trauma must be minimized.

Better institution of physiotherapy and distraction osteogenesis to lengthen the shortened limbs (11) improved the outcome of replantations but, recovery of good sensibility remained the vital parameter in the functional outcome of such cases (1, 9).

It is well known that primary tensionless end-to-end anastomosis of transected nerves provides the best possible outcome, however in the case of a missing segment nerve grafts have to be utilized. The factors that could affect the results of peripheral nerve reconstruction by autografts are delaying surgery, age of the patient, nature of injury, length of the autograft, and height of the injury (10). The following case depicts many of these parameters and we are presenting it as it represents a good example of a unique and a common sense modality of treatment in managing such conditions.

CASE REPORT

A 30-year-old male lorry driver presented to the casualty department with a completely amputated left leg (Fig. 1). The injury was sustained by a one-inch wide nylon belt used to lift heavy weights into his lorry. The belt was left unwound on the front seat after unloading without realizing that one of its ends remained outside the door. When the lorry drove off, the outside end was entangled in the wheel of the lorry, pulled the belt out of the door, caught the leg and badly severed it (Fig. 2).

The amputation was sustained at the junction of the lower and middle third of the leg with crushing of structures for one centimeter on both sides. The option of replantation was offered to the, otherwise fit and healthy, patient who had a great motivation for it. The operation was performed and reperfusion was achieved after an ischemia of four hours. The patient made an uneventful postoperative recovery and started partial weight-bearing mobilization two months after his operation followed by full mobilization after another two months. With only 20 degrees of plantar and dorsiflexion at his ankle, he was able to walk without a limp aided by a one-inch shoe heel raise. He was able to return to average duties in six months period (Fig. 3).

On annual review, good reinnervation of the sole of the replanted foot was noticed. The patient was able to differentiate between hot and cold objects, feel light touch and pressure and “would become uncomfortable if gravel entered his shoes”. He had no complaints of cold intolerance and the insensate area of sural nerve distribution was considered of insignificant disability in the replanted leg.

TECHNIQUE

The amputated part was perfused initially by inserting a size 6-feeding tube as a temporary shunt in the divided ends of the posterior tibial artery followed by bone fixation with an external fixator using bone grafts. Tendons and vessels were repaired achieving good perfusion.

After meticulous debridement to almost healthy-looking ends on either side, the posterior tibial nerve was found to have a 4-cm defect. The ipsilateral sural nerve was harvested by an open method, retro-posed, divided into four cables and anastomosed in the gap within the posterior tibial nerve. The incision for harvesting the sural nerve served the purpose of fasciotomy of the superficial posterior compartment and through the same incision the deep compartment was also released. The procedure was completed with distally-based fasciocutaneous flaps to cover the skin defect.

DISCUSSION

The outcome of the nerve grafts is greatly affected by the selection of a proper donor nerve and the method of its retrieval. Nerve grafts should be chosen considering the length and thickness of the nerve required (5). Commonly used, donor nerves for grafting are sural nerve, medial cutaneous nerve of the arm, medial and lateral cutaneous nerves of forearm, posterior and lateral cutaneous nerves of thigh, and intercostobrachial nerves.

The recent addition of superficial peroneal nerve (3) strengthens the armamentarium of donor nerves but as yet there is no nerve, which offers versatile qualities in all circumstances. The resultant morbidity at the nerve graft donor site has been tried to be kept to a minimum by different harvesting methods such as multiple puncture techniques and endoscopic retrieval (7).

However, it has not been shown that selection of the donor nerve should be considered individually not only to obtain the best match of the nerve required but also in the light of the future requirements of rehabilitation which can be affected by the resultant donor site morbidity.

The simplicity of harvesting a nerve from the ipsilateral limb is by virtue of its presence in the same sterilized area. Although traction injuries of limbs can result in damage along the nerves to a variable extent, similar and avulsions injuries are generally not considered for replantations in the first place. The fasciotomies are strongly recommended in these severe injuries requiring long operations and using the incision required for obtaining the nerve graft to decompress the superficial and deep compartments add to the effectiveness of the method. As the sensibility of a replanted limb is decreased anyway (8), utilizing a nerve from the same limb does not worsen the leg sensibility significantly and at the same time pain, scarring, and decreased sensation in the other leg can be prevented. The four commonly used parameters to reflect recovery of nerve repair are reinnervation, tactile gnosis, integrated sensory and motor functions, and pain or discomfort (12). The common sense approach of using the ipsilateral sural nerve for grafting the defect in posterior tibial nerve has shown good sensory recovery with decreased donor site morbidity, easier rehabilitation and quicker return to normal daily activities in leg replantation and hence worth reminding.

Address for correspondence:

Kaka Hama Attar MRCS

395A Hale End Road

Woodford Green

Essex IG8 9LL

United Kingdom

E-mail: hamaattar@yahoo.co.uk