Cadaveric Study on Variations in the Level of Bifurcation of Sciatic Nerve and its Clinical Implications

Abstract

Introduction: Sciatic nerve is the thickest nerve of the human body arising from the sacral plexus. It bifurcates into tibial nerve and common fibular nerve at any level from the pelvis to the popliteal fossa. Variations in the level of bifurcation of sciatic nerve is having correlation with many clinical conditions like piriformis syndrome, sciatica, sleeping foot, foot drop, etc. Aim: To observe the variations in the level of bifurcation of sciatic nerve into tibial nerve and common fibular nerve, to correlate the variations with their clinical implications and to discuss the findings of the present study with the available literature regarding the same. Materials and Methods: A total of 102 lower extremities from 51 formalin fixed cadaver were used in the present study. All these 102 lower extremities were divided into six groups (Group A to F), according to the level of bifurcation of sciatic nerve into tibial nerve and common fibular nerve; in the pelvis (Group A), in the gluteal region (Group B), in the upper (Group C), middle (Group D) and lower (Group E) part of posterior compartment of thigh, in the popliteal fossa (Group F). Numbers and percentages of the lower extremities falling in particular group were calculated and table was formed accordingly. Results: In the present study, we found 24 (23.53%) lower extremities in Group A, 4 (3.92%) in Group B, 2 (1.96%) in Group C, 3(2.95%) in Group D, 48(47.06%) in Group E and 21(20.59%) in Group F. The lower part of posterior compartment of thigh was the most common (47.06%), within the pelvis prior to exit into the gluteal region is the second most common (23.53%) and the upper part of posterior compartment of thigh was the least common (1.96%) level of bifurcation of sciatic nerve into tibial nerve and common fibular nerve in the present study. Conclusion: Variations in the level of bifurcation of sciatic nerve into tibial nerve and common fibular nerve is not so rare. The knowledge of variations in the level of bifurcations of sciatic nerve will help in early diagnosis and treatment of sciatic nerve entrapment or neuropathies and simultaneously reducing the associated morbidities.

Keywords

• common fibular nerve
• pelvis
• piriformis
• popliteal fossa
• tibial nerve