- Discussion:
- S shaped skin incision is made, extending along the posterior border
of biceps and its tendon on the upper lateral side
of popliteal fossa, then transversely across the fossa and finally
along lower medial side of fossa posterior to
semitendinosus tendon;
- skin flaps are retracted and the deep fascia is incised in midline;
- small saphenous vein is ligated if necessary but
sural nerve must be
preserved;
- sural nerve is followed upwards to lead to the
tibal nerve which
is defined, together w/ space between nerve &
semimembranous so
that underlying head of
gastrocnemius can be displayed;
-
sural nerve, which lies superficial to deep fascia below the
knee, is used as a guide to the tibial nerve;
- follow sural nerve upwards to pierce the deep fascia and lead to
tibial nerve which is its parent trunk;
- in popliteal fossa the tibial nerve lies superficial to popliteal
vein, w/ popliteal artery deep to the vein;
- large vessels and nerves in popliteal fossa are obvious hazards;
- popliteal vessels are displaced laterally; in order to do this middle
geniculate and possibly superior medial genicular vessels
are ligated; (see
genicular system);
- medial head of the
Gastrocnemius is traced upwards, detached
from its origen and retracted towards the midline, so exposing
joint capsule which can then be opened;
- nerve and vessls to medial head of gastrocnemius must not be
damaged but as both this head of muscle & main neurovascular
bundle are retracted laterally, the risk is minimized;
