Internal Hemipelvectomy and Pelvic Reconstruction

• MRI of the whole pelvis with contrast — local staging: intraosseous and extraosseous extent, relationship to iliac vessels, sciatic and femoral nerves, SI joint, hip joint, bladder/rectum; defines osteotomy planes
• CT chest — pulmonary staging (bone sarcomas metastasise to lung)
• CT pelvis — cortical detail, matrix mineralisation, and the dataset for navigation or 3D-printed cutting guides/custom implants
• Whole-body staging — bone scan or FDG-PET per tumour type; PET valuable for Ewing response assessment
• Bloods, alkaline phosphatase/LDH where relevant; fertility and psychology referral in young patients

• Image-guided core needle biopsy at the treating sarcoma centre, tract agreed with the resecting surgeon
• Tract must lie within the planned incision and be excisable en bloc; avoid transgluteal routes that contaminate posterior flaps, and avoid crossing intermuscular planes or entering the joint
• Mark the entry site (tattoo/photograph) for excision at resection
• Discuss at sarcoma MDT before definitive surgery; neoadjuvant chemotherapy for osteosarcoma and Ewing; chondrosarcoma proceeds straight to surgery

• Virtual surgical planning: fused CT-MRI to define osteotomies with a planned margin (commonly 5 to 10 millimetres beyond MRI-defined tumour plus a soft-tissue cuff); patient-specific cutting guides or computer navigation reduce intralesional resection rates
• Vascular plan: preoperative angio-CT if vessel abutment; vascular surgeon on standby; consider ureteric stents (palpable ureters) and urinary catheter
• Bowel prep and defunctioning discussion if rectum at risk
• Cross-match substantial blood, cell salvage available (contested in sarcoma — many avoid it or use leucocyte filtration), tranexamic acid
• Plastic surgery involvement for flap coverage plan (pedicled rectus abdominis is the workhorse)
• Consent for internal hemipelvectomy, possible external hemipelvectomy, nerve deficit, infection requiring implant removal, and mortality

Indication: iliac wing tumour sparing acetabulum and SI joint (or taken with SI joint as zone I plus IV).

• Position: floppy lateral or lateral decubitus allowing anterior and posterior access
• Approach: utilitarian pelvic incision along the iliac crest (extensile ilioinguinal-type anteriorly, extending posteriorly toward the PSIS); elevate abductors laterally and iliacus medially off remaining bone only, keeping muscle cuff on tumour
• At-risk: superior gluteal artery at the greater sciatic notch (retraction injury causes torrential bleeding that retracts into the pelvis — control iliac inflow first), L5 nerve root and lumbosacral trunk anterior to the ala, femoral nerve within iliacus
• Osteotomies: supra-acetabular cut and cut adjacent to (or through) the SI joint under guide/navigation
• Reconstruction decision: if a supra-acetabular bone bridge remains, no reconstruction. If the ring is discontinuous between sacrum and acetabulum, options are: accept controlled proximal migration (modest limb shortening, often acceptable function), or restore continuity with an iliosacral bar/screw construct plus vascularised free fibula or structural allograft to fuse sacrum to residual ilium — favoured in young, high-demand patients where limb-length and abductor mechanics matter

The reconstructive challenge. Resection sacrifices the hip. PIPADRAW essentials:

• Position: floppy lateral; whole limb, abdomen and hemipelvis prepped
• Imaging/equipment: navigation or patient-specific guides; custom implant or prosthesis system; cell salvage decision made; vascular instruments open
• Approach: extensile utilitarian incision — iliofemoral limb plus ilioinguinal limb; identify and sling femoral vessels and nerve; identify sciatic nerve posteriorly; ligate obturator bundle if within resection
• Dissection: extraperitoneal medial dissection off bladder; osteotomies through ilium and pubic ramus (with or without ischium) with a wide cuff; divide hip capsule or take femoral head with specimen if joint involved
• At-risk structures: external iliac/femoral vessels (medial), sciatic nerve (posterior), obturator bundle, superior gluteal artery, bladder and urethra medially
• Reconstruction: as per the selection section below
• Closure: dead-space management, abductor reattachment where possible, pedicled rectus abdominis or gluteal flap if envelope deficient, suction drains
• Aftercare: protected weight bearing 6 to 12 weeks (construct dependent), abduction brace after endoprosthesis in many units, thromboprophylaxis extended

• Supine; Pfannenstiel-type or ilioinguinal-based approach; catheterise
• At-risk: corona mortis (retropubic anastomosis between obturator and external iliac systems — ligate deliberately), bladder and membranous urethra deep to the symphysis, obturator neurovascular bundle in the obturator canal, spermatic cord/round ligament, pudendal structures near the ischium
• Weight-bearing arch is intact, so no skeletal reconstruction — the femoroacetabular and sacroiliac load path is preserved
• Reconstruct the pelvic floor to prevent herniation: mesh or fascial/flap repair; adductor origin can be sutured to residual structures
• Function after isolated zone III resection is excellent; main morbidity is urogenital and hernia

• Resection crosses the SI joint into the ala; usually combined with zone I
• Requires posterior exposure and often a combined anterior-posterior strategy; sacral roots and lumbosacral trunk define the resection's neurological cost
• If posterior ring continuity is lost, spinopelvic (lumbopelvic) fixation — pedicle screws L4/L5 to iliac or remaining pelvic bone, often with a fibula or allograft strut — restores the load path; without it, progressive proximal migration and instability
• Highest complication rates of all zones: wound problems over the sacrum, CSF leak, neurological deficit

Friedel-type hip transposition (iliofemoral pseudarthrosis): the femoral head is moved proximally and stabilised against the residual ilium or lateral sacrum, contained by a soft-tissue sling (capsule, mesh, abductor reattachment); a stable pseudarthrosis forms.

• Advantages: no implant, so no implant infection or loosening; resource-independent; durable; reoperation burden lowest of all options; surprisingly good MSTS scores — commonly 60 to 70 percent in reported series
• Disadvantages: limb shortening 2 to 5 centimetres (shoe raise), Trendelenburg gait, prolonged bracing while the pseudarthrosis stabilises
• Best for: extensive resections with poor bone stock for an implant, resource-limited settings, high infection risk (irradiated field, prior infection), and as the default fallback when endoprosthetic reconstruction fails

Stemmed acetabular ('ice-cream-cone', LUMiC-type) prosthesis: a conical hydroxyapatite-coated stem cemented or press-fit into the residual ilium, carrying a dual-mobility or constrained acetabular articulation with a conventional femoral stem.

• Advantages: off-the-shelf or modular (no manufacturing delay — important after neoadjuvant chemotherapy), immediate structural stability, restores hip centre and length, good early function
• Requirements: adequate residual ilium/SI-adjacent bone to accept the stem — not an option after very high zone I plus II resections
• Disadvantages: infection (the leading failure mode), dislocation (mitigated by dual mobility), stem loosening/breakage, stress fracture of residual ilium
• Best for: zone II with or without zone III resections with preserved iliac bone stock — currently the most widely used endoprosthetic solution

Custom 3D-printed hemipelvic endoprosthesis: patient-specific titanium implant designed on the resection CT with matching cutting guides; porous trabecular surfaces for osseointegration at sacrum/ilium; integrated acetabular component.

• Advantages: anatomical restoration of hip centre, screw trajectories planned into best bone, precise fit even for combined-zone defects, early weight bearing in many series
• Disadvantages: cost and manufacturing lead time (a problem if margins change intraoperatively — the implant cannot adapt), infection risk unchanged, availability limited by resources
• Best for: complex combined-zone defects in centres with the design pipeline; increasingly the preferred option where accessible

• Massive pelvic allograft or allograft-prosthesis composite (APC): biological restoration of bone stock with a cemented total hip into the allograft acetabulum. Risks: infection, nonunion at host-graft junctions, allograft fracture and resorption; demanding graft matching and banking infrastructure. Best in young patients where bone stock restoration matters and a good soft-tissue envelope exists.
• Iliofemoral or ischiofemoral arthrodesis: femur fused to residual ilium/ischium. Stable, strong, low late-failure — but stiff hip, difficulty sitting, and high nonunion rates; now rarely chosen except in heavy manual workers or salvage.
• Saddle prosthesis: historic — a saddle articulating over a notch cut in residual ilium. High rates of proximal migration, iliac fracture, dislocation, infection and poor function; largely abandoned in favour of ice-cream-cone and custom designs. Know it for the exam as a cautionary answer, not a recommendation.
• Resection without reconstruction (flail hip): acceptable in low-demand or palliative settings; shortening and instability, but pain relief and mobility with aids.