gastrocnemius muscle flap - basics and full details

1. Gastrocnemius flap
Dr. Satish Kumar.S

2. Introduction
• Gastrocnemius muscle or musculocutaneous flap- workhorse flap in
knee and upper leg defects
• Constant dominant vascular pedicle-makes it one of the most reliable
flap
• Transposition results in little or no functional deficit provided soleus
and other head left intact

3. Anatomy - Gastrocnemius Muscle
• The gastrocnemius muscle has two fleshy heads of origin.
• The medial head arises from the popliteal surface of the femur,
superior to the medial condyle and posterior to the insertion of the
adductor magnus tendon.
• The lateral head arises from the lateral condyle of the femur.
• Distal to the popliteal fossa, the two fleshy heads unite into a fibrous
septum that separates the two muscle bellies throughout their
extent.

4. • The medial head is longer than the lateral head (15 to 20 cm;12 to
17 cm, respectively).
• The lesser saphenous vein and the sural nerve course within the
furrow between the two muscle bellies.
• At the midcalf, the muscle bellies end in a broad aponeurosis that
joins the aponeurosis of the soleus muscle to form the tendon of
Achilles.
• The tendon inserts into the calcaneum.
• The gastrocnemius muscle flexes the knee and plantarflexes the foot.
• The plantaris muscle and tendon lie between the medial
gastrocnemius and the soleus muscle and can be used to clearly
identify the plane of separation.

6. medial
soleus
lateral
T
A
TP
EDL
PTA/NER
ATA
FHL
PL
Sural n
FDL
peroneal
SPN&DPN

8. Arterial Anatomy – Popliteal artery
• Popliteal ar. courses medial to lateral
• Branches prox. to distal-
• A large lateral branch that supplies the
vastus lateralis & biceps femoris
• medial and lateral superior genicular
arteries, which curve around both femoral
condyles.
• sural arteries, one medial and one lateral
• arise superior to the level of the
articulation of the femur with the tibia.
• The middle genicular artery
• The medial and lateral inferior genicular
arteries,curves around tibial condyles

9. Arterial Anatomy
• The medial sural artery arises from the posterior surface of the
popliteal artery approximately 1 cm proximal to the femoral-tibial
articulation.
• Its external diameter at its origin is 2 to 2.5 mm
• The length of the artery from its origin to its entry into the muscle
hilum is 4 to 5 cm.
• The lateral sural artery arises from the posterior surface of the
popliteal artery in a more distal location
• Its external diameter is 2 to 2.4 mm with a pedicle length of 4 cm.

10. Venous drainage of the flap
• All arteries to these flaps are accompanied by venae comitantes.
• Primary: venae comitantes of the medial and lateral sural artery
Two venae comitantes are found with each artery. The diameter
of the veins is approximately 3.5 mm, ranging from 3 to 4 mm.
• Secondary: superficial veins such as the lesser saphenous vein
This vein can be included with the flap to augment drainage
particularly useful when a large skin island is included
with the flap.

11. NERVE SUPPLY
• The tibial nerve gives off the medial and lateral sural motor nerves
(the medial branch being usually 1–2 cm proximal to the lateral one)
in the proximal third of the popliteal fossa.
• Both nerves accompany the respective vascular pedicles to reach the
heads of the gastrocnemius.

12. Flap innervation
Motor
• Medial and lateral sural motor nerves that come of the tibial nerve
These nerves are approximately 4–5 cm in length and enter the
muscle on its deep proximal surface with sural vascular pedicle.
As the gastrocnemius is a rapid-contraction muscle, it is preferable
to cut the nerve when raising a pedicled flap to avoid muscle
contraction.

13. Sensory
• Skin overlying the medial gastrocnemius muscle
Posterior femoral cutaneous nerve and saphenous nerve(L3–L4)
innervate this area
The saphenous nerve follows the course of the greater saphenous
vein and can be found near the medial side of the gastrocnemius
• Skin overlying the lateral gastrocnemius muscle
The sural nerve (S1–S2) supplies the skin in this part of the calf and
the nerve can be found running along the lesser saphenous vein.
The nerve runs in a subfascial plane and pierces the fascia in the
posterior calf to travel more superficially and supply the skin.

14. Flap details
• Type I muscle –Mathes and Nahai
• Supplied by one dominant neurovascular pedicle
• Namely medial and lateral sural arteries
• Raised as a muscle flap or musculocutaneous flap
• Medial gastrocnemius –usually used for defects of upper leg and
knee

15. Medial Gastrocnemius Flap

16. Flap vascularity
• Arterial supply
• Dominant – medial sural artery
• Length: 5.1 cm (range 1.6–9.5 cm)
• Diameter: 2.5 mm (range 1.8–4 mm)
• Minor –
• Br. From lateral sural artery – located in distal half of
muscle
• Post. Tibial Ar.-
musculocutaneous br. From PTA in mid leg
muscular br.  soleus and distal medial gastrocnemius
Frequently, this br. is large- permits Inf. Based flap
• Venous – two venae comitantes

17. Flap design & marking
• Anatomical landmarks-
• A transverse line is marked in the posterior knee crease
(indicates the level of medial and lateral sural vessels)
• The midline raphe separating the medial and lateral heads and
the distal ends of the muscles
• Thinner the muscle, the easier will be to transpose
• A thick-bodied muscle is always more difficult to mobilize

18. Medial Musculocutaneous flap
• Skin width- medial border of tibia to median raphe
• Point of rotation- midline popliteal fossa
• Skin overlying muscle, can extend as
random beyond the muscle with 1:1 ratio
• Usually about 10cm from malleolus

19. Flap dimensions
• Muscle -Medial head
• Length: 15 cm (range 13–20 cm)
• Width: 7 cm (range 5–9 cm)
• Skin island dimensions
• Length: 10–15 cm (maximum 20 cm)
• Width: 6–10 cm (maximum 15 cm)

20. Operative technique
• Incision- posterior midline incision or a longitudinal incision between
the midline and the defect
• Key landmark-
• Sural nerve and SSV- lie superficial to the muscle bellies
• Locates the natural cleavage bet. the bellies
• Identify soleus-
• Aponeurotic layer ant. and post. Surfaces

21. Operative technique
• The muscle fascia is split, and the junction of the two heads is incised
• The loose avascular areolar tissue between soleus and gastrocnemius
- swept through with the finger down to the tendinous junction.
• the muscle is transected distally with a cuff of tendon attached for
use in fixation to the wound edge
• Muscle tunneled to the defect
• Drains kept in muscle bed

24. Medial Musculocutaneous flap
• midline posterior incision is made in the upper calf, and
• after identifying the sural nerve and lesser saphenous vein, the deep
dissection is done
• remainder of the peripheral skin incision is then made
• Musculocutaneous flap elevated
• Peritenon over soleus and achilles preserved
• Backcuts in prox. Skin may be required for flap rotation

25. Steps to maximise arc of rotation
• The tendons of gracilis and semitendinosus muscles- tenolysis for
free passage of flap
• The origin of the medial head of the gastrocnemius muscle can be
transected
• The neurovascular pedicle of the medial gastrocnemius muscle
should be identified- nerve is transected

26. Lateral Gastrocnemius flap

27. Vascularity
• Dominant- lateral sural ar.
• Minor- br from medial sural ar.
• Length- 4.8cm
• Veins- venae comitantes
• Nerves -
• Sural nerve- runs in subfascial plane and
pierces the fascia in posterior calf to become
superficial

28. Flap dimensions
• Muscle dimensions Lateral head
• Length: 12 cm (range 11–16 cm)
• Width: 5 cm (range 4–7 cm)
• The dimensions for skin islands over the lateral gastrocnemius
muscle are adjusted to be slightly smaller than medial head

29. Lateral musculocutaneous flap

30. Operative technique
• Similar to medial
• Caution- Prox. Encounter the
common peroneal nerve
• Passes from medial to lateral
over the upper portion of the
muscle belly

31. Medial Vs. Lateral
Medial gastrocnemius
• Longer
• Larger
• Optimally positioned along
tibial border
• Thus, reach is more- defects of
upper leg and knee
Lateral gastrocnemius
• Shorter
• Smaller
• Has to trespass lateral and
anterior compartments to reach
tibia
• Reach is small- upper lateral leg
and smaller knee defects

32. Technical points
• flap should be firmly fixed on the recipient site
• The short distal aponeurotic portion -buried into the edge of
recipient site - a solid attachment for the flap.
• Motor nerve to be cut
• avoids contraction of the muscle when it is attached on the recipient site
• allows the flap to shrink over time, essentially serving as a debulking
procedure.

33. Flap modifications
• Transposition flap:
• Most commonly used
• Islanding the flap- cutting the origin
• extra reach obtained
• Cautious not to injure pedicle
• Incising muscle fascia(bowman procedure)
• Additional length & improved contour
• Advancement flap
• Undermining in submuscular plane
• Advancement of musculocutaneous unit to cover upper tibial defects

34. Medial sural perforator flap
• Musculocutaneous flap
• Excessive bulk
• Significant donor defect
• Perforator flap
• Thin local flap
• Muscle function preserved and a lifeboat in future

35. Marking
• a line is drawn along the medial leg from the
midpoint of the popliteal crease to the
midpoint of the medial malleolus
• first major perforator- 8 cm from the popliteal
crease-distal half of a circle with a radius of 2
cm,
• Second major perforator-15 cm from the
popliteal crease-circle with a radius of 3 cm
• More distal the perforator- longer the pedicle

36. Gastrocnemius Musculocutaneous V-Y
Advancement Flap

37. • Gastrocnemius Musculocutaneous Cross-Leg Flap
• Not much in practice with availability of other local flaps and free flaps
• Free flap
• Vessel calibre-good
• Short pedicle
• Free functional muscle transfer

38. Arc of rotation
• Medial gastrocnemius-arc of rotation is circular and
the areas covered are
• the proximal third of the tibia(medial aspect and anterior
crest),
• the anterior aspect of the knee beyond the lateral border of
the patella,
• the distal third of the posterior aspect of the thigh, and
• the popliteal fossa.

39. Indications
• medial and anterior aspect of the leg and knee for the medial head
and the lateral aspect for the lateral head
• Localized areas of tibial osteomyelitis can be removed and the defect
reconstructed with well-vascularized muscle.
• Exposed metal plates can be similarly covered.
• functional transplant to restore forearm flexion,forearm extension, or
foot extension.

40. Advantages
• Muscle dissection is easy and quick
• Contour deformity following the use of one head is acceptable.
• When only one head is raised, functional loss is negligible, compared
to the benefit of the procedure
• Subsequent bony procedures can be carried out by elevating the
healed flap
• unnecessary to operate in the vicinity of its high vascular pedicle,
thereby decreasing the possibility of inadvertent damage to the flap's
blood supply

41. Disadvantages
• The posterior incision is not desirable in females.
• The donor site following musculocutaneous flap is not cosmetically
acceptable .
• Functional- some difficulty in galloping

42. Conclusion
• Effective to cover upper leg and knee defects
• Constant dominant vascular pedicle
• Easy and quick to harvest

47. THANK YOU