Limb-sparing wide resection of periacetabular pelvic sarcoma, with reconstruction of the hip–pelvis junction
- Enneking divided pelvic resections into zones — I iliac wing, II periacetabular, III pubic/ischiopubic, IV sacral (an extended scheme). Type II is the commonest and most functionally significant because it removes the hip joint and disconnects the limb from the axial skeleton.
- Internal hemipelvectomy is the limb-salvage alternative to external hemipelvectomy (hindquarter amputation). It is offered when wide margins can be achieved while preserving the lower limb's neurovascular axis (external/internal iliac vessels, femoral and sciatic nerves, lumbosacral plexus) and adequate soft-tissue cover.
- Massive blood loss is the dominant intraoperative risk. Anticipate it: large-bore access, arterial and central lines, cell salvage, cross-matched blood, pre-operative embolisation for vascular tumours, and control of the iliac vessels with slings before any bone is cut.
- Infection is the leading post-operative complication and the commonest reason a salvaged limb is secondarily ablated. Dead space and prosthetic bulk drive it — pelvic-floor reconstruction and vascularised soft-tissue cover (e.g. a pedicled vertical rectus flap) matter as much as the bony work.
- Reconstruction after a Type II resection is chosen from a saddle prosthesis, a custom or 3D-printed modular endoprosthesis, hip transposition (a biological pseudarthrosis), an allograft-prosthetic composite, or a flail (resection) hip for limited functional demand.
When & Why
Indication. A primary malignant bone tumour of the innominate bone — most often chondrosarcoma in adults, osteosarcoma or Ewing sarcoma in younger patients — or a selected locally aggressive lesion, where wide surgical margins are achievable with limb preservation. The resection must leave a sensate, functional limb with adequate soft-tissue cover. Historically the only curative local option was external hemipelvectomy (hindquarter amputation); modern imaging, chemotherapy and reconstruction have made limb salvage the default in specialist centres. Pre-operative assessment is what makes the operation safe and the margins clean. Establish, in this order: - Local staging — MRI of the whole pelvis (marrow extent, soft-tissue mass, neurovascular and sacroiliac joint involvement, sacral foramina) plus CT pelvis for cortical detail and planning the osteotomy levels. The two are complementary, not interchangeable.
- Systemic staging — whole-body bone scan or PET-CT, and CT chest, to exclude metastatic disease that would change the plan.
- Biopsy — performed by the treating surgeon, along the line of the future incision, so the tract is excised en bloc with the specimen. A poorly placed biopsy tract seeds the flank or perineum and converts a salvageable limb into an amputation.
- Medical optimisation — neoadjuvant chemotherapy for osteosarcoma and Ewing sarcoma; pre-operative embolisation for hypervascular tumours; ureteric stents placed before incision; bowel preparation; cross-match of blood and cell-saver set up. The decision. Three management strategies exist for an operable pelvic sarcoma, and the choice is dictated by margins, neurovascular involvement and patient fitness:
The default when wide margins are achievable and the limb's neurovascular axis and cover can be preserved. Highest operative complexity and complication burden, but the limb is kept.
Reserved for tumours that cannot be excised with margins while preserving the limb — iliac or femoral neurovascular encasement, lumbosacral plexus involvement, or inadequate soft-tissue cover. Reliable local control at the cost of the limb.
For widely metastatic or surgically unfit patients: radiotherapy, chemotherapy, or palliative procedures for pain and stability. Curative resection is not the goal.
Setup. The patient is placed in a semilateral (lazy lateral) position on a bean-bag, freeing both the anterior ilioinguinal window and any posterior extension; all pressure points are padded. Establish large-bore intravenous access with arterial and central lines, a urinary catheter, and pre-incision ureteric stents so the ureters are palpable and identifiable throughout. Cell salvage is running and cross-matched blood is in theatre. Antibiotic prophylaxis is given. The femoral vessels, femoral nerve and ureter must remain identifiable at every stage of the dissection.
The Operation
The goal: expose the hemipelvis through an ilioinguinal/utilitarian approach, gain control of the iliac vessels and femoral nerve, osteotomise the pubis, ischium and ilium around the tumour, detach and deliver the periacetabular block en bloc with wide margins, then reconstruct the hip–pelvis junction and close with durable soft-tissue cover. The exposure is laid out in full below (and in depth on the ilioinguinal approach to the acetabulum page).
Schematic of the periacetabular (Enneking Type II) resection: the ilioinguinal/utilitarian exposure with the external iliac artery and vein controlled on slings lateral to the stented ureter, the femoral nerve protected on the psoas, and the three osteotomy lines marked — the superior pubic ramus, the ischium, and the supracetabular ilium — enclosing the acetabular block for en-bloc delivery.
Context: A verified image is being sourced.
Operative sequence
- Semilateral on a bean-bag; prep the leg and flank free so the limb can be manoeuvred.
- Confirm large-bore access, arterial and central lines, ureteric stents, cell saver and cross-matched blood are all in place.
- Re-state the planned osteotomy levels from the MRI/CT and mark the incision around the biopsy tract so it is excised en bloc.
- A single incision that can be extended for any pelvic resection: from the pubic symphysis along the inguinal ligament to the anterior superior iliac spine, then along the iliac crest to the posterior superior iliac spine.
- An elliptical excision incorporates the biopsy tract. The incision gives access to the retroperitoneum, the iliac wing and, through the lateral window, the hip and posterior column.
- Detach the abdominal-wall musculature and iliacus from the internal face of the iliac wing subperiosteally, sweeping the peritoneum and iliac vessels medially off the quadrilateral plate.
- This exposes the inner table of the ilium, the sacroiliac joint, and the pelvic brim — the landmarks for the proximal osteotomy. Pack to control oozing from the nutrient vessels.
- In the inguinal canal / lacuna vasorum, identify and sling the external iliac artery and vein; trace them to the common iliac bifurcation for proximal control.
- Identify the femoral nerve on the surface of iliacus, lateral to the vessels, and protect it; it is the nerve most often injured in this exposure.
- Identify the stented ureter medially and the spermatic cord or round ligament; develop the retropubic space bluntly, protecting the bladder.
- Ligate crossing branches (obturator, inferior epigastric) only after the main trunks are controlled. Do not divide anything until vessel loops are around the iliac vessels.
- Strip the obturator internus and externus off the inferior pubic ramus and ischium, protecting the obturator nerve and vessels in the obturator foramen.
- Pass a Gigli saw or angled osteotome around the superior pubic ramus (just lateral to the symphysis, at the planned margin) and osteotomise.
- Divide the ischium at its planned level to free the inferior/anterior column.
- From the iliac window, make the proximal (supracetabular) iliac cut at the level dictated by the MRI margin — above the acetabulum, sparing the sacroiliac joint wherever the tumour allows.
- The three cuts (pubis, ischium, ilium) now isolate the periacetabular block. Confirm each cut is beyond tumour on pre-operative imaging and on direct inspection.
- Open the hip capsule and osteotomise the femoral neck (or dislocate the hip, depending on reconstruction), separating the limb from the acetabular block.
- The periacetabular specimen is now mobile, attached only by soft tissue and the vessels already controlled.
- Divide remaining soft-tissue attachments (capsule, short external rotators, gluteal muscles to the margin) and deliver the periacetabular block with the tumour en bloc.
- Obtain frozen-section margins from the osteotomy beds and any close soft-tissue surface; extend a margin if it is positive.
- Achieve meticulous haemostasis — the raw pelvic surface and divided pelvic-floor muscles bleed briskly. The cell saver and slung iliac vessels are your safety net.
- Choose the reconstruction from the options in the table below — a saddle or custom/3D-printed endoprosthesis, a hip transposition, an allograft-prosthetic composite, or a flail hip — based on the defect, the remaining bone stock, patient demand and prognosis.
- Reconnect the femur to the residual pelvis (prosthesis) or stabilise the proximal femur against the ilium (transposition/flail), and reconstruct the pelvic ring if continuity was lost.
- Reconstruct the pelvic floor and abdominal wall (non-absorbable mesh) to prevent visceral herniation into the dead space.
- Provide vascularised soft-tissue cover for any prosthesis — frequently a pedicled vertical rectus abdominis (VRAM) or omental flap — because dead space around a bulky implant is the substrate for infection.
- Layered closure over multiple drains; confirm distal pulses and limb perfusion before leaving theatre.
Gain control of the common/external iliac artery and vein on slings and protect the femoral nerve before any osteotomy. Anticipate heavy bleeding from the cancellous osteotomy surfaces, the obturator and superior gluteal vessels, and the pelvic-floor venous plexus: run the cell saver, have cross-matched blood in theatre, and consider pre-operative embolisation for hypervascular tumours. If an iliac vessel is injured, apply direct pressure, restore proximal and distal control, and repair primarily or with a graft — call vascular surgery early.
The biopsy must be taken by the treating surgeon along the line of resection, and the tract excised en bloc. A biopsy placed through the flank, buttock or perineum contaminates compartments that cannot be excised with the specimen and is a classic, avoidable reason a limb-salvage candidate is converted to a hindquarter amputation.
| Reconstruction | Description | Advantages | Drawbacks and risks |
|---|---|---|---|
| Saddle prosthesis | A U-shaped saddle articulates with a notch cut in the residual ilium, linking femur to pelvis without an acetabular cup | Relatively quick, established technique, preserves leg length to a degree | High dislocation, loosening and infection rates; iliac notches can fracture; largely superseded |
| Custom / 3D-printed modular endoprosthesis | A patient-specific or modular implant (iliac flange, screws/rods) carrying an acetabular cup to rebuild the hip | Best restoration of anatomy and stability; modern standard in specialist centres | Expensive; long fabrication for custom devices; still high infection and mechanical-failure burden |
| Hip transposition | The proximal femur is pulled up and tethered to the residual ilium with soft tissue/sutures, accepting a flail pseudarthrosis | No bulky implant, lower infection risk, biological | Limb shortening, instability and Trendelenburg gait; function modest but durable |
| Allograft-prosthetic composite (APC) | A structural pelvic allograft replaces the bony defect, with a total-hip component cemented into it | Restores bone stock and a biological surface; good for younger patients | Graft fracture/non-union and infection; long-term concerns |
| Flail hip / resection arthroplasty | No bony reconstruction; the limb is left flail and managed with a brace | Simplest and fastest; for limited functional demand or poor prognosis | Marked shortening and instability; ambulation often limited; salvage option |
Aftercare & Complications
Rehabilitation is reconstruction-dependent and slow, dictated by the implant, the soft-tissue flap and the nerve status. | Phase | Timing | Mobilisation | Focus | |-------|--------|--------------|-------| | 1 | 0–2 weeks | Bed-to-chair; protected, non- or touch-weight-bear | Flap and wound healing; DVT prophylaxis; analgesia | | 2 | 2–6 weeks | Progressive weight-bearing per reconstruction (prosthesis slower; transposition as tolerated) | Hip stability; protect any nerve deficit | | 3 | 6–12 weeks | Full weight-bearing as the construct allows | Gait re-education, abductor strengthening, brace wean | | 4 | 3–12 months | Return to function within the limb's limits | Endurance; limb-length and gait adaptation; ongoing surveillance imaging | Functional outcome tracks the resection zone: Type I (iliac) and Type III (pubic) patients do well when the acetabulum and abductors are spared; Type II patients walk with a limp, often need a walking aid, and never recover a normal gait. MSTS (Musculoskeletal Tumour Society) scores after a Type II resection typically sit around half of normal — functional, but clearly limited. Complications
| Complication | Recognition | Prevention | Management |
|---|---|---|---|
| Massive haemorrhage | Falling pressure, rising drain/swab blood loss, tachycardia | Pre-op embolisation; iliac-vessel control before bone cuts; cell saver; cross-match | Direct pressure, vessel control, repair/graft, activate massive transfusion |
| Deep infection / prosthetic infection | Wound breakdown, persistent fever, discharging sinus over the implant | Vascularised flap cover, pelvic-floor mesh, prophylactic antibiotics, minimise dead space | Debridement, antibiotics, often single- or two-stage exchange or secondary ablation |
| DVT / pulmonary embolism | Calf swelling, dyspnoea, pleuritic pain | Mechanical and chemical prophylaxis, early mobilisation | Anticoagulation; IVC filter if contraindicated |
| Nerve injury (femoral, obturator, sciatic, L5 root) | New quadriceps/foot weakness, sensory loss | Identify and protect nerves on slings; avoid traction at osteotomies | Neurophysiology, expectant care; explore if transection suspected |
| Ureteric / bladder injury | Haematuria, low urine output, intra-operative dye leak | Pre-op stents; stay on bone during retropubic dissection | Intra-operative repair with urology, stenting |
| Prosthesis dislocation / loosening / failure | Sudden pain and deformity; progressive loosening on radiograph | Appropriate implant selection, stable reconstruction, restore abductor tension | Closed vs open reduction; revision of loose components |
| Local recurrence | New mass or pain; surveillance-imaging change | Wide margins, en-bloc biopsy-tract excision, adjuvant therapy | Re-resection or ablation; chemoradiotherapy as indicated |
| Inguinal hernia / abdominal-wall weakness | Bulge over the groin, visceral symptoms | Robust pelvic-floor and abdominal-wall mesh reconstruction | Surgical repair of the hernia |
| Limb-length discrepancy / flail instability | Shortening, abnormal gait, brace dependence | Choose reconstruction matched to defect and demand | Footwear modification, brace; revision if severe |
Viva & Exam Focus
PROTECTPROTECT — the operation in one word
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 38-year-old man has a chondrosarcoma of the right acetabulum. How do you plan the resection, and what determines whether you can offer limb salvage rather than a hindquarter amputation?”
“You have controlled the iliac vessels and completed the osteotomies, but on delivering the periacetabular block the posterior (sacroiliac) margin is positive on frozen section. How do you manage this?”
Indication & decision
- Primary pelvic sarcoma resectable with wide margins and a viable limb
- Limb salvage vs external hemipelvectomy hinges on neurovascular/plexus involvement and cover
Enneking zones
- I iliac · II periacetabular · III pubic · IV sacral (extended scheme)
- Type II removes the hip — the commonest and most functionally significant resection
Exposure & structures at risk
- Utilitarian/ilioinguinal incision; excise the biopsy tract en bloc
- Control iliac vessels and femoral nerve; protect the stented ureter, obturator and lumbosacral plexus
The resection
- Three osteotomies — pubis, ischium, supracetabular ilium
- Disconnect the hip; deliver the block en bloc; check frozen-section margins
Reconstruction
- Saddle · custom/3D-printed endoprosthesis · hip transposition · allograft-prosthetic composite · flail
- Match the construct to the defect, bone stock, demand and prognosis
The two big complications
- Massive blood loss — anticipate it (embolisation, cell saver, vessel control)
- Infection — the leading cause of secondary ablation; flap cover and pelvic-floor reconstruction
Background & Evidence
Epidemiology. Primary malignant bone tumours of the pelvis are uncommon but disproportionately lethal — the pelvis accounts for a minority of all primary bone sarcomas yet a large share of sarcoma mortality, because lesions grow large before they are felt and lie close to viscera and major vessels. Chondrosarcoma is the commonest primary malignant pelvic tumour in adults; osteosarcoma and Ewing sarcoma predominate in adolescents and young adults. Many patients present late with a large, palpable mass. Pathoanatomy. The innominate bone is formed by the fusion of the ilium, ischium and pubis at the triradiate cartilage of the acetabulum. The acetabulum is the keystone of the pelvic ring: remove it (a Type II resection) and the lower limb is disconnected from the axial skeleton, which is why reconstruction is unavoidable and always imperfect. Cradled around the pelvis are the common, external and internal iliac vessels, the femoral nerve on iliacus, the obturator nerve and vessels through the obturator foramen, the lumbosacral plexus and sciatic nerve posteriorly, and the ureter, bladder and rectum medially — every one of them a constraint on what can be excised and reconstructed.
| Zone | Region removed | Functional consequence | Reconstruction need |
|---|---|---|---|
| I | Iliac wing | Usually good; abductor lever arm may be shortened | Often none; bone graft if continuity lost |
| II | Periacetabular | Loss of the hip; limb disconnected from the axis | Required — prosthesis, transposition, APC or flail |
| III | Pubis / ischiopubic ramus | Good if the acetabulum is spared | Usually none; pelvic-floor repair if medial wall gone |
| IV | Sacral ala (extended scheme) | Variable; depends on nerve roots sacrificed | Often none; lumbopelvic stabilisation if unstable |
| Combined | e.g. I+II, II+III, I+II+III (total hemipelvectomy) | Worse as more of the ring and hip are lost | Larger, more complex reconstruction |
Adjuvant therapy. Neoadjuvant and adjuvant chemotherapy is standard for osteosarcoma (a platinum/doxorubicin/high-dose methotrexate regimen) and Ewing sarcoma (a vincristine/doxorubicin/cyclophosphamide alternating with ifosfamide/etoposide regimen); chondrosarcoma is chemo-resistant, so surgery stands alone. Radiotherapy has a role in Ewing sarcoma and for close or positive margins, and proton-beam therapy is increasingly used for pelvic sarcomas to spare adjacent bowel and bladder. Key evidence. Enneking and Dunham's 1978 description of resection with local reconstruction for primary malignant innominate tumours established the zonal classification and showed that limb salvage could match the local control of amputation in selected patients — the foundation of the modern operation. Reconstruction has since evolved from Harrington-style devices and the saddle prosthesis, through custom and modular implants, to patient-specific 3D-printed endoprostheses championed by high-volume centres, which restore anatomy more faithfully but have not eliminated the persistent infection and mechanical-failure burden. Across series, the two threats that define outcomes remain local recurrence (margin-dependent) and deep infection (the leading cause of secondary ablation).
References
Resection and local reconstruction for primary malignant tumors of innominate bone
- The foundational description of limb-salvage resection of the innominate bone, defining the Type I, II and III pelvic resection zones that still guide planning.
- Showed that local reconstruction after resection could preserve the limb without sacrificing oncological control in appropriately selected patients.
Salvage of the limb in the treatment of malignant pelvic tumors
- A landmark Mayo Clinic series establishing limb salvage as a viable alternative to hemipelvectomy for pelvic sarcoma when wide margins could be achieved.
- Defined the oncological and functional basis on which limb-preserving pelvic resection is offered.
Reconstruction using the saddle prosthesis following excision of primary and metastatic periacetabular tumors
- A widely cited series of saddle-prosthesis reconstruction after periacetabular resection, reporting the early functional results that popularised the device.
- Documented the complications — dislocation, infection and loosening — that motivated later custom and modular implants.
Three-dimensionally printed modular hemipelvic endoprosthesis for periacetabular tumour resection
- A large high-volume centre series of patient-specific 3D-printed modular endoprostheses for periacetabular reconstruction.
- Reported improved anatomical fit and osseointegration over earlier devices, while infection and mechanical failure remained significant.