Triradiate Extensile Approach to the Acetabulum

What it exposes. The triradiate (Y) extensile approach gives simultaneous access to the acetabular dome, the iliac wing, the sciatic buttress and the posterior column in a single lateral-position exposure. It exists for the small group of acetabular fractures in which neither a single anterior nor a single posterior approach can deliver an anatomic reduction. Why this approach is chosen. A both-column (associated) fracture by definition separates the entire acetabulum from the axial skeleton through a fracture of the ilium, so articular reduction must begin on the iliac wing and be carried down to the joint. The triradiate exposure lets the surgeon build the reduction from proximal to distal under direct vision. Primary indications: - Both-column (associated type) acetabular fractures requiring simultaneous exposure of the anterior and posterior columns

• Transverse plus posterior wall fractures where a single approach cannot deliver anatomic reduction
• T-shaped fractures with both anterior and posterior column involvement
• Fractures with extensive sciatic buttress or iliac wing extension that defeat a single incision
• Selected delayed acetabular reconstruction or malunion surgery
• Selected complex revision acetabular surgery where extensile exposure is genuinely required Contraindications and relative contraindications: - Morel-Lavallee lesion or significant soft-tissue degloving over the hip and lateral thigh (raises infection and wound break-down risk)
• Polytrauma patient medically unfit for a prolonged extensile procedure
• Any fracture that can be reduced through a single non-extensile approach (an extensile exposure would then be unjustified overkill)
• Low-demand elderly patients who may be better served by non-operative care or acute total hip arthroplasty in selected both-column patterns Alternative and preferred approaches: - Combined single-incision strategy (modern default): an anterior approach (ilioinguinal, iliopectineal, or modified Stoppa) for the anterior column combined with a Kocher-Langenbeck for the posterior column, staged as needed
• Extended iliofemoral approach (Letournel): the classic extensile alternative, stripping the muscles off the outer iliac table
• Kocher-Langenbeck alone: for isolated posterior column or posterior wall injuries
• Ilioinguinal or modified Stoppa alone: for predominantly anterior injuries

Position and landmarks. The patient is placed in lateral decubitus with the affected side up, supported with a beanbag or pelvic supports. The whole iliac crest and the entire limb are prepped and draped free on a radiolucent table so the limb can be manipulated; image intensifier access is confirmed from both sides, and a cell saver with cross-matched blood is available because extensile acetabular surgery can bleed. The greater trochanter is the geometric centre of the incision and the pivot of the exposure. The ASIS marks the target of the anterosuperior limb, the PSIS the target of the posterosuperior limb, the iliac crest the superior border the proximal limbs parallel, and the lateral femoral shaft the line of the distal limb. The triradiate (Y) incision has three limbs meeting at the greater trochanter: an anterosuperior limb running obliquely upward and forward toward the ASIS paralleling the iliac crest, a posterosuperior limb running upward and backward toward the PSIS along the iliac crest, and a vertical distal limb running distally along the lateral thigh for about 8 to 12 cm. The three limbs are raised as flaps so that the fascia lata, gluteal fascia and iliac crest can be opened to expose the trochanter, the abductor mechanism and the iliac wing.

The triradiate is an extensile, osteotomy-based approach rather than a single true internervous-plane approach. It mobilises whole muscle compartments rather than descending a single interval, then converts the exposure into an extensile one with a greater trochanteric osteotomy. Bony anatomy. The acetabulum forms at the junction of the ilium, ischium and pubis. Conceptually it is divided into an anterior column (iliopubic limb) and a posterior column (ilioischial limb), with the dome or roof as the weight-bearing articular surface. A both-column fracture leaves no part of the acetabulum attached to the axial skeleton. The triradiate approach is designed to reach the dome, the sciatic buttress (the solid bone above the dome that holds the reduction), the outer table of the ilium and the posterior column. Muscular layers of the lateral hip: | Layer | Muscle | Nerve Supply | Role in the Approach | |-------|--------|--------------|----------------------| | Superficial anterior | Tensor fasciae latae | Superior gluteal | Defines the anterior limb interval | | Superficial posterior | Gluteus maximus | Inferior gluteal | Reflected posteriorly in the posterior limb | | Deep abductor | Gluteus medius | Superior gluteal | Reflected with the trochanter | | Deep abductor | Gluteus minimus | Superior gluteal | Reflected with the trochanter | | Short external rotators | Piriformis, obturator internus, gemelli | Nerve to obturator internus, piriformis | Divided to reach the posterior column |

The internervous plane. The key interval the triradiate exploits is the same one used by the Kocher-Langenbeck — between gluteus maximus (inferior gluteal nerve) posteriorly and gluteus medius and minimus with the tensor fasciae latae (superior gluteal nerve) anteriorly. This plane reaches the greater trochanter and the short external rotators without denervating either muscle mass. The trochanteric osteotomy then converts this into an extensile exposure: the entire superior-gluteal-nerve compartment (gluteus medius, minimus and tensor fasciae latae) is detached from the femur as one block with the greater trochanter and reflected superiorly, swinging the abductors off the hip joint capsule and the ilium.

Structures at risk, by layer

Neurovascular anatomy at a glance: | Structure | Location | Clinical significance | |-----------|----------|----------------------| | Superior gluteal nerve | Exits the greater sciatic notch, runs deep to gluteus minimus | Supplies the abductors; injury causes abductor lurch | | Superior gluteal artery | Largest branch of the internal iliac, exits above piriformis | Avulsion causes massive haemorrhage | | Sciatic nerve | Exits below piriformis, runs over the short external rotators | Peroneal division is most vulnerable | | Inferior gluteal nerve | Exits below piriformis, supplies gluteus maximus | At risk if gluteus maximus is split too proximally | | Medial femoral circumflex artery (deep branch) | Runs along quadratus femoris toward the trochanter | Main blood supply to the femoral head | | Lateral femoral cutaneous nerve | Runs near the ASIS | At risk in the anterior limb | Extensile options. The triradiate is extensile by design — its three limbs define the directions in which it can be lengthened, and extension simply lengthens the subperiosteal dissection along that limb without crossing a new internervous plane: - Proximally and anteriorly along the iliac crest to strip muscle off the outer iliac table for full iliac wing access and high anterior column involvement

• Posteriorly and superiorly toward the PSIS and sacroiliac joint region when the fracture extends into the posterior ilium
• Distally down the femur for access to the proximal femoral shaft or to mobilise vastus lateralis when trochanteric fixation or proximal femoral work is needed Closure. Re-attach the greater trochanter anatomically — secure fixation is critical because trochanteric nonunion or migration is a signature complication. Use two or three lag screws across the trochanter into the femur, or a claw plate with a tension band construct in osteoporotic bone. Repair the divided short external rotators to their tendon stumps or the capsule and re-attach the piriformis if it was taken down. Close the fascia lata over the distal limb, the deep gluteal fascia posteriorly, and the subcutaneous and skin layers. Place a suction drain for the extensile dead space and start heterotopic ossification prophylaxis (indomethacin and/or local radiation) because the extended dissection carries a high rate of heterotopic bone formation.

• Both-column (associated) acetabular fracture — proximal-to-distal reduction built on the iliac wing under direct vision; the principal indication.
• Transverse plus posterior wall fracture — simultaneous anterior and posterior articular reduction and buttress fixation.
• T-shaped fracture — access to both limbs of the T through one exposure.
• Sciatic buttress and iliac wing extension — direct access to the solid bone that holds the reduction.
• Delayed reconstruction or malunion — extensile access for osteotomy and re-alignment.

Guidelines, Registries & Global Practice

Acetabular fractures are managed at major trauma centres worldwide, and the principles converge across examination systems. A CT scan with three-dimensional reconstruction is the standard for planning any operatively treated acetabular fracture, and the Letournel and Judet classification remains the universal language for describing fracture morphology and selecting the approach. Side-by-side principles (where guidance converges): | Body | Position on extensile approaches | |------|----------------------------------| | AO Foundation | Anatomic articular reduction is the goal; extensile approaches are reserved for complex associated fractures that no single incision can reduce, and combined single-incision strategies are preferred whenever they suffice | | BOA or BOAST (trauma) | Early resuscitation and soft-tissue assessment; definitive fixation once the patient and soft tissues permit; multidisciplinary care for polytrauma | | OTA and AAOS | Restoration of the weight-bearing dome and the mechanical axis as primary goals; CT-based planning and surgeon experience are strongly associated with outcome | Global practice variation. In well-resourced centres, extensile exposures have largely been replaced by combined single-incision surgery and intra-operative three-dimensional imaging. In resource-limited settings, the same biomechanical principles are pursued with conventional fluoroscopy and the available implant inventory, and extensile approaches may still feature because staged combined surgery and advanced imaging are less available. Heterotopic ossification prophylaxis practice varies by unit, with indomethacin, local radiation, or both used according to local protocol and the perceived risk. Consent (globally applicable). Discuss heterotopic ossification, abductor dysfunction and Trendelenburg gait, trochanteric nonunion, sciatic nerve injury (with foot drop), infection, major bleeding, and the risk of post-traumatic arthritis and eventual total hip arthroplasty if the articular surface is damaged.