Sciatic Nerve:

From; www.wheelessonline.com

- Anatomy:
     - arises from lumbrosacral plexus: L4, L5, S1, S2, S3;
     - nerve emerges from pelvis below piriformis & enters thigh between ischial tuberosity & greater trochanter;
     - in 10% of patients, the sciatic nerve is separated in greater sciatic foramen by all or part of the piriformis;
     - sciatic nerve is accompanied by PFCN & by inferior gluteal artery and its special branch to nerve;
     - nerve enters thigh beneath lower border of maximus;
     - descends near middle of thigh, lying on adductor magnus muscle & being crossed obliquely by long
            head of biceps femoris ;
     - nerve usually separates in upper part of popliteal space;

- Tibal Nerve  Branch:
     - from anterion branches of LS plexus: L4, L5, S1, S2, S3;
     - 2 branches from tibial division: below quadratus femoris:
          - upper branch passes to long head of  biceps femoris  & upper portion of semitendinosus;
          - lower branch: innervates lower portion of  semitendinosus  &
               semimembranous  & ischiocondylar portion of adductor magnus ;

- Common Peroneal Nerve:
     - from posterior branches: L4, L5, S1, S2;
     - nerve to short head of biceps femoris arises from lateral side of sciatic nerve (common peroneal portion)
            in middle of thigh & enters superficial surface of the muscle;

- Sciatic Nerve in THR: (see: nerve injuries from THR)
     - in THR the sciatic nerve may be injured by excessive tension when extremity has been lengthened significantly, especially in pts w/ DDH ;
     - sciatic nerve is at risk during leg lengthening;
     - peroneal division is most often affected;
     - w/ sciatic nerve injury following THR, keep pts leg flexed over side of bed;
            - if injury was due to traction, the nerve may recover in the relaxed position;

- Sciatic Nerver Injury from Kocher Langenbock Approach;
     - sciatic nerve palsy from Kocher Langenbock Approach;
     - can be prevented by intraop monitoring of amount of tension applied by assistants retracting the nerve;
     - early treatment consists of AFO
     - sciatic nerve recovery may occur over a 3 yr period;
     - tendon transfers are usually not performed unitl 3 yr post op;