Surgical Approaches and Key Anatomy

General approach to an approach

When describing a surgical approach, use a consistent sequence:

1. indication
2. patient position
3. surface landmarks and incision
4. superficial interval
5. deep interval
6. important structures at risk
7. exposure obtained
8. closure and key complications

Deltopectoral approach

Uses

• proximal humeral surgery
• shoulder arthroplasty
• anterior instability procedures
• selected drainage procedures

Interval

The superficial interval lies between:

• deltoid laterally
• pectoralis major medially

The cephalic vein lies in the deltopectoral groove.

Deep exposure identifies the conjoint tendon and clavipectoral fascia. The axillary nerve must be respected inferiorly, particularly around the subscapularis and proximal humerus.

Important anatomy

The axillary nerve traverses the quadrangular space with the posterior circumflex humeral vessels.

Anterior approach to the radius

Uses

• radius fracture fixation
• selected forearm exposure

The classic anterior approach uses the plane around brachioradialis and flexor-pronator structures.

Structures at risk

• radial artery distally
• superficial radial nerve
• posterior interosseous nerve proximally

When exposing the proximal radius, protect the posterior interosseous nerve as it passes through the supinator.

Cubital fossa

Boundaries

• superior: line between epicondyles
• medial: pronator teres
• lateral: brachioradialis

Key contents

From lateral toward medial, remember the major structures:

• radial nerve lies laterally
• biceps tendon
• brachial artery
• median nerve

Shoulder posterior spaces

Quadrangular space

Contains:

• axillary nerve
• posterior circumflex humeral vessels

Triangular space

Contains:

• circumflex scapular vessels

Triangular interval

Contains:

• radial nerve
• profunda brachii vessels

Anterior hip approach

The anterior hip interval uses the plane between muscles supplied by different nerves.

Superficially the interval is between:

• sartorius
• tensor fasciae latae

Important structures include the lateral femoral cutaneous nerve and branches of the lateral circumflex femoral vessels.

Posterior hip approach

Uses

• total hip arthroplasty
• hemiarthroplasty
• exposure of posterior acetabulum and proximal femur

The gluteus maximus is split in line with its fibres. Short external rotators are identified and reflected as required.

Structure at risk

The sciatic nerve is the major deep structure at risk and should be understood in relation to the short external rotators and posterior capsule.

Greater sciatic foramen

Piriformis divides the foramen into suprapiriform and infrapiriform regions.

Above piriformis:

• superior gluteal nerve and vessels

Below piriformis:

• sciatic nerve
• inferior gluteal nerve and vessels
• posterior femoral cutaneous nerve
• pudendal nerve and internal pudendal vessels
• nerves to obturator internus and quadratus femoris

Ilioinguinal approach

Used for selected anterior pelvic and acetabular exposures.

The approach develops windows around:

• iliac fossa
• muscular and vascular compartments beneath the inguinal ligament
• retropubic region

Important structures at risk include:

• external iliac/femoral vessels
• femoral nerve
• lateral femoral cutaneous nerve
• spermatic cord or round ligament structures
• obturator neurovascular structures
• lymphatics

This approach requires precise knowledge of the inguinal canal and pelvic brim.

Femoral triangle

Boundaries

• superior: inguinal ligament
• lateral: sartorius
• medial: adductor longus

Major contents from lateral to medial:

• femoral nerve
• femoral artery
• femoral vein
• lymphatics

Posterior approach to the knee

Boundaries of popliteal fossa

Superolateral:

• biceps femoris

Superomedial:

• semimembranosus and semitendinosus

Inferolateral:

• lateral head of gastrocnemius

Inferomedial:

• medial head of gastrocnemius

Deep contents

The tibial nerve is most superficial, followed by popliteal vein and popliteal artery as the dissection proceeds deeper.

Careful identification of neurovascular structures is essential before deep exposure.

Anterior ankle approach

The anterior neurovascular bundle lies around the extensor tendons.

A practical medial-to-lateral sequence across the front of the ankle is:

• tibialis anterior
• extensor hallucis longus
• anterior tibial vessels/deep fibular nerve region
• extensor digitorum longus
• fibularis tertius

The exact relation between nerve and artery can vary around the ankle.

Tarsal tunnel

Behind the medial malleolus are:

• tibialis posterior tendon
• flexor digitorum longus tendon
• posterior tibial vessels
• tibial nerve
• flexor hallucis longus tendon

Posterolateral ankle approach

Provides access to:

• posterior malleolus
• posterior fibula
• posterolateral ankle
• peroneal tendons in selected procedures

Important structures include the sural nerve, peroneal tendons and the posteromedial neurovascular bundle, depending on the depth and direction of dissection.

Lower-leg compartments

Four compartments:

• anterior
• lateral
• superficial posterior
• deep posterior

Anterior

Contains ankle dorsiflexors, anterior tibial vessels and deep fibular nerve.

Lateral

Contains fibularis longus and brevis with the superficial fibular nerve.

Superficial posterior

Contains gastrocnemius and soleus.

Deep posterior

Contains tibialis posterior, long toe flexors, posterior tibial vessels and tibial nerve.

Compartment release principle

A fasciotomy must decompress all affected compartments completely. In the leg, a two-incision technique is commonly used to release all four compartments while protecting the superficial fibular nerve laterally and the saphenous structures medially.

Principles common to all approaches

A surgical approach should provide adequate exposure while respecting:

• internervous or intermuscular planes where relevant
• major neurovascular structures
• blood supply to skin and bone
• future reconstructive options
• previous scars
• extensile pathways

The shortest skin incision is not necessarily the least invasive operation. Deep dissection, muscle damage and devascularisation matter more than incision length alone.

Shoulder and proximal humerus

In the deltopectoral approach, identify the deltopectoral groove and cephalic vein, open the clavipectoral fascia and understand the relationship of the conjoint tendon, subscapularis, biceps and axillary nerve.

The axillary nerve is especially vulnerable inferior to the shoulder joint and around the surgical neck. It should be protected by knowledge of its course rather than blind retraction.

A deltoid-splitting approach provides direct lateral access but places the axillary nerve at risk as it passes around the humerus deep to the deltoid.

Humeral shaft

Posterior approaches require deliberate identification and protection of the radial nerve. The nerve courses in the spiral groove with the profunda brachii vessels and then pierces the lateral intermuscular septum distally.

Approach selection should consider fracture level and whether direct visualisation of the radial nerve is required.

Elbow

The ulnar nerve runs behind the medial epicondyle and must be considered during medial and many posterior exposures.

For lateral elbow approaches, the posterior interosseous nerve is at risk around the radial neck and supinator. Forearm rotation changes its relationship to the operative field.

Forearm

In the anterior Henry approach, important structures include the radial artery and superficial radial nerve, with the posterior interosseous nerve at risk proximally.

The posterior Thompson approach uses a different interval and requires awareness of the posterior interosseous nerve in the proximal forearm.

Hip

The anterior hip approach uses the superficial interval between sartorius and tensor fasciae latae, with the lateral femoral cutaneous nerve vulnerable superficially.

The posterior approach splits gluteus maximus and reflects the short external rotators. The sciatic nerve lies posteriorly and must be protected. Repair of posterior soft tissues contributes to stability after arthroplasty.

The direct lateral approach involves the abductor mechanism and can risk superior gluteal nerve injury if dissection extends too proximally.

Knee

A standard medial parapatellar arthrotomy provides broad exposure for arthroplasty. Alternative approaches may be selected according to previous scars, deformity and need for extensile exposure.

The common peroneal nerve is vulnerable around the fibular neck, particularly in correction of valgus deformity or posterolateral surgery.

Tibia and ankle

Anterolateral approaches around the proximal tibia require awareness of the common peroneal nerve and anterior compartment structures.

At the ankle, incision planning should respect thin soft-tissue envelopes and cutaneous nerves. The superficial peroneal nerve is particularly variable as it becomes subcutaneous distally.

Surgical anatomy strategy

For every approach, be able to state:

1. patient position
2. landmarks
3. skin incision
4. superficial interval
5. deep interval
6. nerve and vessel at risk
7. structure exposed
8. how the approach can be extended

FRCS synthesis

An approach answer is strongest when anatomy is linked to a surgical hazard. Rather than reciting muscle names, explain which structure can be injured, where it is encountered and how you avoid that injury.