On “Successful Management of Foot Drop by Nerve Transfers to the Deep Peroneal Nerve” (J Reconstr Microsurg 2008;24:419–428)

We read with great interest the original paper by Nath et al entitled “Successful Management of Foot Drop by Nerve Transfers to the Deep Peroneal Nerve.” The authors describe the transfer of nerve fascicles of either the superficial peroneal nerve or the tibial nerve to reinnervate deep peroneal nerve innervated muscle groups in patients with peroneal nerve injuries.

In this short communication, we want to comment on the reported findings. Peroneal nerve lesions are frequently seen following injury to the lower extremity. They are well described following hip dislocations and fractures, with the mechanisms being commonly either of an indirect traction/compression type or a direct/penetrating trauma to the lateral knee region.[1] [2] The resulting foot drop has devastating effects on patient rehabilitation. Apart from ankle foot orthosis, various surgical treatments have been utilized. These can be divided into bone-, tendon-, or nerve-based approaches or a combination hereof.[3] [4] The functional recovery of dorsiflexion after tendon transfer is known to be excellent and is well documented.[3] Similarly, a large series examining results of nerve repair versus common peroneal nerve decompression and nerve repair plus tendon transfer found excellent results in the latter group versus disappointing functional outcomes in the nerve repair only group.[4]

Although the technique of fascicular nerve transfer to the deep peroneal nerve for peroneal nerve lesions has been described earlier,[5] [6] Nath et al present the first clinical case using this technique. We congratulate the authors on their elegant technique study; however, we would like to focus our attention on the heterogeneity of their patient population with different causes of the peroneal nerve dysfunction. This limits the impact of study findings at this time on clinical practice.

A recent description of extensive remote injury to the myoneural junction in peroneal nerve injuries was reported by the Dellon group. Given these findings, one can argue that more proximal fascicular nerve transfers will not be effective in restoring function. Because of the histomorphologic changes to the myoneural interface, the authors of this study argue in favor of direct neurotization versus nerve repair.[7] However, the study of Nath et al documents functional recovery following fascicular transfers only. It can be argued that this effect might be solely due to the neural decompression performed during the nerve dissection. Thoma et al[8] described significant improvement of ankle dorsiflexion in 19 of 20 patients with common peroneal nerve palsies treated exclusively with peroneal nerve decompression.

We would like to ask the authors if they see limiting factors for the use of the described technique (e.g., old patients, proximal sciatic nerve lesions). Specifically, we are interested if the authors experienced posttraumatic fibrosis following deep soft tissue injuries of the lower leg, possibly affecting the tibialis anterior muscle. The conclusion of the study by Nath et al is limited because of lack of control for the beneficial effect of decompression alone.

The field of nerve transfers for peripheral nerve injuries to upper and lower extremities is exciting and continues to develop dynamically. At this time, however, we believe that more research needs to be done before any clinical recommendations can be made for the treatment of foot drop after common peroneal nerve injury, especially given the fact that tendon transfers reliably offer well-documented good functional rehabilitation.

REFERENCES

• 1 Kato N, Birch R. Peripheral nerve palsies associated with closed fractures and dislocations.  Injury. 2006;  37 507-512
• 2 Hillyard R F, Fox J. Sciatic nerve injuries associated with traumatic posterior hip dislocations.  Am J Emerg Med. 2003;  21 545-548
• 3 Wiesseman G J. Tendon transfers for peripheral nerve injuries of the lower extremity.  Orthop Clin North Am. 1981;  12 459-467
• 4 Garozzo D, Ferraresi S, Buffatti P. Surgical treatment of common peroneal nerve injuries: indications and results. A series of 62 cases.  J Neurosurg Sci. 2004;  48 105-112 discussion 112
• 5 Bodily K D, Spinner R J, Bishop A T. Restoration of motor function of the deep fibular (peroneal) nerve by direct nerve transfer of branches from the tibial nerve: an anatomical study.  Clin Anat. 2004;  17 201-205
• 6 Büyükmumcu M, Ustün M E, Seker M, Kocaoğullari Y, Sağmanligil A. The possibility of deep peroneal nerve neurotisation by the superficial peroneal nerve: an anatomical approach.  J Anat. 1999;  194 309-312
• 7 Prasad A R, Steck J K, Dellon A L. Zone of traction injury of the common peroneal nerve.  Ann Plast Surg. 2007;  59 302-306
• 8 Thoma A, Fawcett S, Ginty M, Veltri K. Decompression of the common peroneal nerve: experience with 20 consecutive cases.  Plast Reconstr Surg. 2001;  107 1183-1189