Anatomy of the sural nerve and its relation to the ...

FOOT & ANKLE INTERNATIONAL Copyright ? 2000 by the American Orthopaedic Foot & Ankle Society, Inc.

Anatomy of the sural nerve and its relation to the Achilles Tendon

Jonathan Webb, FRCS*, Narain Moorjani, MB ChB** and Mike Radford, FRCS **

Bristol and Oxford, UK

ABSTRACT Sural nerve injury is a complication of Achilles Tendon (TA) rupture. We dissected 30 cadaveric lower limbs to describe the course of the sural nerve in relation to the TA. At the level of insertion of the TA into the calcaneum, the sural nerve was a mean 18.8 mm from the lateral border of the TA. The proximal course of the nerve was towards the midline such that it crossed the lateral border of the TA at a mean distance of 9.8 cm from the calcaneum. The significant individual variation in the position of the sural nerve in relation to the achilles tendon should be borne in mind when placing sutures in the proximal part of the achilles tendon. Percutaneous sutures should not be placed in the lateral half of the TA.

KEYWORDS Sural nerve, Tendo achilles rupture, Percutaneous tendo achilles repair

Percutaneous TA repair appears to reduce the re-rupture rate in comparison to non-operative treatment and wound complications compared to open operative methods, while maintaining the plantar flexion power obtained by open technlques.v" An increased incidence of sural nerve injury has been reported after percutaneous repair.":"

Previous anatomical studies describe the sural nerve in relation to the fibula but not in relation to the TA.3.6,9 This study aims to describe the course of the sural nerve, with particular reference to the TA to provide guidelines for the placement of sutures during percutaneous TA repair.

MATERIALS AND METHODS

We dissected 30 formalin preserved cadaveric lower

INTRODUCTION

limbs (15 left and 15 right) of which 18 were female and

The treatment of TA rupture remains a controversial topic in current surgical management. Operative techniques approximate the ruptured ends of the tendon by open or percutaneous methods and non-operative techniques by cast immobilization for between six to twelve weeks.

Operative methods have the advantage of restoring normal continuity, length and tension to the ruptured tendon as well as reducing re-rupture rates compared to non-operative management. 1,5,7,12.14 Open operative techniques, however, have a higher incidence of wound and thromboembolic compltcatrons.>">"

12 male. None of the limbs showed any evidence of previous surgery. A single cutaneous incision was made 1cm lateral to the palpable tendo achilles insertion into the calcaneum and extended proximally and slightly medially for a length of approximately 20 cm.

The gastrocsoleus muscle, TA, sural nerve and short saphenous vein were explored by blunt dissection. Pins were used to maintain the position of the nerve during dissection. Measurements were carried out using standard callipers.

The widths of TA and horizontal distances of the sural nerve to the TA lateral border were measured at 0,4,8,12 and 16 cm from the TA insertion into the calca-

neum.

Results are reported as mean with ranges in brackets.

"Senior House Officer, Department of Orthopaedic Surgery, Nuffield Orthopaedic Centre, Oxford, UK; "'Specialist Registrar, Department of Trauma, John Radcliffe Hospital, Oxford, UK.

Corresponding Author: ?Jonathan Webb FRCS (Orth) Department of Trauma & Orthopedic Surgery North Bristol NHS Trust South mead Hospital, Bristol BS10 5NB, UK Tel: +44 (0) 1179595913 Fax: +44 (0) 1179595924 E-mail: webbjonathan@

RESULTS

At insertion (Ocm) the average width of the TA was 18.7 mm (11-28 mm) and narrowed to 12.7 mm at 4 cm. From there the TA widths increased to 16.2, 28.2 and 38.2 mm at 8,12 and 16 cm respectively. (Table 1)

475

476

WEBB, MOORJANI AND RADFORD

Table 1

Widths of TA and distances of nerve from muscle/tendon

Distance from

TA insertion (ern)

o

TA width

(mm) 18.7 (11 to 28)

Horizontal distance of sural nerve

from TA lateral border (mm)

17.5 (3 to 40)

4

12.7 (8 to 16)

7.00 (3 to 14)

8

16.2 (13 to 31)

2.3 (-4 to 13)

12

28.2 (20 to 44) -3.30 (0 to -16)

16

38.2 (25 to 58) -10.4 (0 to -24)

The position of the sural nerve is described in relation to the lateral border of the achilles tendon. The position was recorded as positive if the nerve was lateral to the lateral border, and negative if it was medial to the lateral border. At the insertion, the sural nerve was 17.5 mm lateral to the lateral border of the TA and this reduced to 7.0 mm lateral at 4 cm. Between 8 and 12 cm the sural nerve moved from being 2.4 mm lateral to the lateral border of the TNGS complex to 3.30 mm medial to the TNGS complex, hence lying over the GS muscle belly. This distance increased to 10.4 mm medial to the GS complex at 16 cm. (Fig.1)

The nerve curves towards the midline as it courses proximally such that it crosses the lateral border of the TA 9.83 cm (6.55 - 16 cm) from the calcaneum.

DISCUSSION

The sural nerve is essentially a sensory nerve that carries multiple aborizing branches to the lateral aspect of the foot and ankle. It is formed from the medial sural cutaneous nerve and peroneal communicating branch in 80 % of cases and solely from the medial sural cutaneous nerve in the remaining 20%.13

The medial sural cutaneous nerve is a branch of the posterior surface of the tibial nerve, originating in the popliteal fossa. It descends between the two heads of gastrocnemius eventually becoming superficial by piercing the overlying fascia at the junction of the distal and middle thirds of the leg and then continues on to form the sural nerve. The peroneal communicating branch originates from the lateral sural cutaneous nerve (itself a branch of the common peroneal nerve) and descends medially superficial to the gastrocnemius fascia to join the medial sural cutaneous nerve. The sural nerve forms at a point 11-20 cm proximal to the lateral malleolus' and it is at this level and distal to it that the

Foot & Ankle InternationallVol. 21, No. 6/June 2000

nerve is in danger from percutaneous suturing of the TA.

Percutaneous repair of tendo achilles was first described in 197711 as an alternative method of repairing TA rupture to non-operative techniques that had resulted in higher re-rupture rates1,5,7,12,14 and open methods that had led to an incidence of wound and thromboembolic cornplicaticns.vv-"-" Ma and Griffiths" placed six stab incisions, three medial and three lateral, using a No 15 blade and a curved hemostatic clamp for blunt dissection down to the tendon. Their initial results did not identify any cases of sural nerve damage in the study of 18 patients. Subsequent studies, however, using the original technique described above, found an incidence of 10-14% of nerve injury.8,15 Klein et al (1991)8, having encountered postoperative sural nerve complications, actually modified the original technique midway during the study to widen one of the incisions to identify the nerve, with improved results.

Hockenbury et al' described a 60% (3/5) incidence of sural nerve injury during percutaneous repair of cadaveric TA's and in all three cases damage was caused by entrapment of the nerve 2.5 cm proximal to the tendon defect.

The highly variable position of the sural nerve has been emphasized in this study. This may account for the relatively high incidence of sural nerve injury in percutaneous repair techniques for achilles tendon rupture. Webb et al (1998)16 have recently described a percutaneous technique that involves three posterior incisions (one proximal, one distal and one over the TA rupture).

Gastrocsoleus

Sural nerve

Point at which sural nerve crosses -- lateral border of tendo-Achilles

9.83cm

Insertion of tendo- - Achilles into

Calcaneum

Medial

Lateral

Posterior view of Tendo-achilles and sural nerve

Fig.1 Posterior view of Tendo-achilles and sural nerve

Foot & Ankle InternationallVol. 21, No. 6/June2000

ANATOMY OF THE SURAL NERVE

477

By utilizing incisions only over the posterior aspect of the tendon and, by placing the proximal incision more medially, they have avoided injury to the sural nerve.

This cadaver study demonstrates that the proximal course of the sural nerve is towards the midline and that sutures placed near the lateral border of the TA put the sural nerve at risk of injury

ACKNOWLEDGEMENTS

We would like to thank Mr Roger White, Department of Anatomy, University of Oxford, and Sylvia Barker, Department of Medical Illustration, John Radcliffe Hospital, Oxford for their kind help and co-operation.

AEFEAENCES

1. Arner 0, Lindolm A.: Subcutaneous rupture of the Achilles Tendon: a study of 92 cases. Acta Chir Scand Suppl 239: 1-51, 1959.

2. Bradley JP, Tibone JE.: Percutaneous and open surgical repairs of Achilles tendon ruptures. A comparative study. American Journal of Sports Medicine 18(2): 188-195, 1990.

3. Eastwood OM, Iragau I, Atkins A.: The distal course of the sural nerve and its significance for incisions around the lateral hindfoot. Foot &Ankle 13(4): 199-202, 1992.

4. Gillies H, Chalmers J.: The management of fresh ruptures of the tendo Achilles. J. Bone and Joint Surg 53-A: 337-343, 1970.

5. Hockenbury AT, Johns JC.: A biomechanical in vitro comparison of open versus percutaneous repair of tendon Achilles. Foot & Ankle 11(2): 67-72,1990.

6. Huene DB, Bunnell WP.: Operative anatomy of nerves encountered in the lateral approach to the distal part of the fibula. J. Bone and Joint Surg. 77(7): 1021-1024, 1995.

7. Inglis AE, Scott N, SculcoTP, Patterson AH.: Rupture of the Tendo Achillis. An objective assessment of surgical and non-surgical treatment. J Bone & Joint Surg 58(A): 990-993, 1976.

8. Klein W, Lang OM, Saleh M.: The use of the Ma-Griffith technique for percutaneous repair of fresh ruptured Tendo Achilles. Chir Organi. Mov LXXVI: 223-228, 1991.

9. Lawrence SJ, Botte M.: The sural nerve in the foot and ankle: An anatomical study with clinical and surgical implications. Foot & Ankle Int 15(9): 490-494, 1994.

10. Lea A, Smith L.: Non-surgical treatment of tendo Achilles rupture. J Bone & Joint Surg 54(A): 1398-1407, 1972.

11. Ma GW, Griffith TG: Percutaneous repair of acute closed ruptured Achilles tendon. A new technique. Clinical Orthopedics and Related Research 128: 247-255,1977.

12. Nistor L.: Surgical and non-surgical treatment of Achilles tendon rupture : a prospective randomized study. J Bone & Joint Surg 63(A): 394-399, 1981.

13. Ortiguela ME, Wood MB, Cahill OA.: Anatomy of the sural nerve complex. The Journal of Hand Surgery 12(6): 1119-1123, 1987.

14. Quigley TB, Scheller AD.: Surgical repair of the ruptured Achilles tendon: analysis of 40 patients treated by the same surgeon. Am J Sports Med 8: 244-250, 1980.

15. Aowley 01, Scotland TA.: Rupture of the Achilles tendon treated by a simple operative procedure. Injury 14: 252-254, 1982.

16. Webb J, Bannister GC.: Percutaneous repair for rupture of the Achilles tendon. Anatomical, biochemical and clinical results of a new technique. J Bone & Joint Surg 81(B): 877-870,1999.

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download