SMITH–PETERSEN APPROACH
- What are the indications for the anterior approach to the hip?
This approach is predominantly used for irrigation and debridement of a septic arthritis of a native hip, or for reduction of displaced intracapsular hip fractures in the young.
Other uses for this approach include irreducible anterior dislocations of the hip, paediatric pelvic osteotomies, open reduction of DDH, arthrodesis and arthroplasty of the hip and tumour excision.
- What is the internervous plane utilised by this approach?
The internervous plane is between the femoral nerve and the superior gluteal nerve. Superficially, the plane is between sartorius (femoral nerve) medially and tensor fascia latae (superior gluteal nerve) laterally. The deep dissection utilises the inter- nervous plane between rectus femoris (femoral nerve) medially and gluteus medius (superior gluteal nerve) laterally.
- How would you position the patient?
Supine. The leg would be externally rotated initially to stretch the sartorius mus- cle to make it more prominent and also to stretch the capsule when making the capsulotomy.
- Where would you base your skin incision?
In an adult, I would base the incision along the anterior half of the iliac crest to the anterior superior iliac spine (ASIS). I would then curve the incision down so that it runs vertically for approximately 10 cm, heading towards the lateral side of the patella. The incision can start at the ASIS for indications such as washout of a native hip and reduction of a displaced intracapsular hip fracture. In a child, for washout of a septic hip joint, I would place a curvilinear skin incision in the groin crease.
- Can you describe the superficial dissection?
Externally rotate the leg to stretch the sartorius muscle.
Blunt dissection through the subcutaneous fat will avoid damage to the lateral cutaneous nerve of the thigh, which pierces the deep fascia of the thigh near this intermuscular interval between sartorius and tensor fascia latae (TFL).
Identify the internervous interval (which is easiest to palpate 2 to 3 inches below the ASIS) between sartorius medially and TFL laterally.
Incise the deep fascia over the medial portion TFL to protect the lateral cutane- ous nerve of the thigh, which usually lies just under the fascia of sartorius.
Retract the sartorius medially along with the nerve and the tensor fascia latae laterally and identify the ascending branch of the lateral circumflex femoral artery (which crosses the gap between sartorius and TFL): This must be ligated or coagulated.
- What about the deep dissection?
Develop plane between rectus femoris (femoral nerve) medially and gluteus medius (superior gluteal nerve) laterally.
If you are struggling for exposure, the origins of rectus femoris (straight head from the ASIS and reflected head from the superior lip of the acetabulum) can be detached to retract rectus femoris further medially, thus exposing the capsule.
Adduct and fully externally rotate the leg to put the capsule on stretch, then define the capsule with blunt dissection. Incise the hip joint capsule either longitudinally or with a T-shaped capsulotomy, depending on the extent of exposure required.
- What are the dangers of this approach?
Lateral cutaneous nerve of the thigh:
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- Reaches thigh by passing under inguinal ligament, generally 1 cm medial to the ASIS.
- The course is variable and it is most commonly seen when incising fascia between the sartorius and TFL.
- Injury may lead to painful neuroma or reduced sensation on the lateral aspect of thigh.
Ascending branch of lateral femoral circumflex artery:
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- Found proximally in the internervous plane between the tensor fascia latae and sartorius.
- Must be ligated or coagulated to prevent brisk bleeding from this large vessel.
- How can this approach be extended?
The approach can be extended proximally along the iliac crest to expose bone for harvesting bone graft.
Distally, the skin incision can be extended down the anterolateral aspect of the thigh and through the fascia lata. The interval between rectus femoris and vastus lateralis can be utilised to gain access to the entire femoral shaft