Enneking zone-guided wide-margin resection with staged anterior-posterior approaches — an advanced limb-salvage operation
- Enneking zones dictate both resection extent and reconstruction need: Zone I (ilium) and III (pubis or ischium) often allow resection without reconstruction; Zone II (periacetabulum) always requires reconstruction or hip transposition; Zone IV (sacrum) requires staged anterior-posterior sacrectomy with nerve-root level determining bowel, bladder and sexual function loss.
- Wide margins (greater than 1 cm soft-tissue cuff or an intact fascial plane) are mandatory for chondrosarcoma and chordoma. Intralesional or marginal resection in these histologies yields local recurrence rates exceeding 50 percent and markedly reduced survival.
- Massive blood loss is the dominant intraoperative risk — average 3 to 8 L for hemipelvectomy and up to 15 L for high sacrectomy. Preoperative embolisation, cell salvage, tranexamic acid and a rapid transfusion protocol are mandatory; vascular control of the internal iliac system is achieved first through the anterior approach.
- Sacral nerve-root sacrifice level determines functional outcome. Bilateral S1 to S2 preservation maintains continence and sexual function in most patients; bilateral S2 to S3 sacrifice produces urinary retention, faecal incontinence and loss of sexual function in greater than 80 percent. Unilateral sacrifice is usually tolerated if the contralateral roots remain intact.
- The anterior approach is performed first for vascular control and visceral mobilisation; the posterior approach follows for definitive resection and reconstruction. Wound infection and flap necrosis exceed 30 percent after primary closure, so soft-tissue coverage with plastic surgery (VRAM or gluteal flap) is planned pre-operatively.
When & Why
Internal hemipelvectomy is a limb-sparing en-bloc resection of part of the pelvis or sacrum for a primary malignant bone or soft-tissue tumour. It is offered when staging (CT chest, abdomen and pelvis plus a bone scan or PET-CT) shows no disease outside the planned resection field and a wide margin is achievable with acceptable morbidity. The aim is cure for chondrosarcoma, chordoma, Ewing sarcoma and osteosarcoma, and durable local control for selected solitary metastases from radioresistant primaries.
Primary pelvic or sacral malignancy (chondrosarcoma, chordoma, Ewing sarcoma, osteosarcoma) with no metastatic disease on staging; a locally recurrent pelvic tumour after prior resection with resectable margins and acceptable morbidity; a solitary metastasis to the pelvis or sacrum from a radioresistant primary (renal cell, thyroid) where wide resection offers a survival benefit.
An Enneking Zone II or high Zone IV tumour where limb salvage with reconstruction offers better function than external hemipelvectomy; a young patient with good performance status and no major comorbidities; patient preference for limb salvage after full discussion of reconstruction options and functional trade-offs.
Metastatic disease outside the planned resection field (lungs, liver, distant bone); unreconstructible neurovascular involvement (sciatic nerve encased, internal iliac vessels unresectable); patient refusal of a permanent stoma or catheter when high sacrectomy is required; active infection or open wound in the field. Relative: poor performance status (ECOG greater than 2) or major cardiopulmonary disease, prior pelvic radiation with poor soft-tissue quality, or age greater than 75 years with limited life expectancy.
Consent must be explicit and documented. Discuss the real chance of a permanent colostomy and catheter if a high sacrectomy is planned, the risk of sciatic or lumbosacral plexus injury with permanent foot drop, wound infection and flap failure rates, reconstruction failure and the likely need for further surgery, and the expected functional outcome (independent ambulation with a cane after Zone II reconstruction, not a return to sport). Setup and blood-loss strategy. Position supine for the anterior stage and prone for the posterior stage, with the two stages performed 24 to 48 hours apart or on the same day with a position change. Place arterial and central venous lines, a urinary catheter and bilateral ureteric stents pre-operatively. Activate a massive transfusion protocol with cell salvage, a tranexamic acid bolus and infusion, and a rapid infuser.
The Operation
The goal is an en-bloc, wide-margin resection guided by the Enneking zone plan, with vascular control of the internal iliac system gained first through an anterior approach and the definitive osteotomy and reconstruction completed posteriorly. The exposure is laid out in full as the opening steps below — it is the heart of the operation.
Operative sequence — staged anterior then posterior
- Supine for the anterior stage, prone for the posterior stage. The two stages are performed 24 to 48 hours apart (preferred for high sacrectomy) or on the same day with a position change.
- Arterial and central venous lines, a urinary catheter and bilateral double-J ureteric stents are placed pre-operatively.
- Blood-loss strategy running from incision: cell salvage, tranexamic acid bolus and infusion, rapid infuser, and an activated massive transfusion protocol.
- Preoperative embolisation of tumour-feeding vessels 24 to 48 hours before surgery reduces blood loss by 30 to 50 percent in hypervascular tumours (renal cell, chordoma).
- Use an extended ilioinguinal or Stoppa incision. This is the anterior exposure that gives access to the iliac crest, pubic rami and sacroiliac joint.
- Expose the iliac crest, the pubic rami and the sacroiliac joint systematically.
- Identify and protect the femoral nerve and the external iliac vessels early; they define the safe corridors for deeper dissection.
- Ligate the internal iliac artery and vein distal to the posterior division. These vessels lie medial to the sacroiliac joint.
- Control the superior gluteal and obturator vessels. This step must be completed before any posterior osteotomy.
- Anterior vascular ligation roughly halves posterior-stage blood loss and is the single most important step in preventing massive haemorrhage.
- Mobilise the stented ureters and the bladder medially. Ureters cross the pelvic brim and are displaced by large masses; the pre-operative stents make them easy to find.
- For sacral tumours, mobilise the rectum off the sacrum to the level of the planned proximal osteotomy (to the sacral promontory for high sacrectomy).
- Place a swab or malleable retractor to protect the viscera during the later osteotomy.
- For Zone II or III resections, perform the anterior portion of the osteotomy through the pubic rami and ilium under direct vision.
- Protect the contents of the sciatic notch with a malleable retractor before cutting.
- A temporary external fixator can be applied if spinopelvic stability is compromised before the posterior stage.
- Turn the patient prone. Use a posterior midline incision from L4 to the coccyx with transverse extensions at the iliac crest level (a Mercedes-Benz or T-incision).
- Raise full-thickness fasciocutaneous flaps to expose the posterior ilium, sacrum and gluteal muscles.
- This posterior exposure is where the definitive osteotomy, nerve-root management and reconstruction are completed.
- Identify the sciatic nerve in the greater sciatic notch, where it exits inferior to the piriformis, and tag it with a vessel loop before any osteotomy.
- For Zone II resections, trace the nerve proximally to the lumbosacral plexus, which lies on the posterior pelvic wall medial to the sacroiliac joint.
- Do not assume the nerve is safe because the tumour is medial — Zone II tumours frequently displace the sciatic nerve laterally against the notch.
- Perform the posterior osteotomies according to the Enneking zone plan. For high sacrectomy, osteotomise through the S1 body or above under direct vision with a high-speed burr or osteotome.
- Protect the dura and cauda equina with a malleable retractor during the sacral osteotomy.
- Deliver the specimen en bloc once all osteotomies are complete. Send proximal and soft-tissue margins for frozen section and re-resect if positive.
- Zone I or III: usually no reconstruction, or a simple iliofemoral arthrodesis if the abductor mechanism is sacrificed.
- Zone II: always reconstruct — a custom endoprosthesis or hip transposition (femoral head fixed to the residual ilium). A flail hip is never acceptable.
- High sacrectomy: lumbopelvic fixation with dual iliac screws, S1 pedicle screws and rods; consider a 3D-printed custom prosthesis when available.
- Rotate a gluteal myocutaneous flap (the workhorse for posterior coverage, based on the superior gluteal artery) or a vertical rectus abdominis myocutaneous (VRAM) flap (preferred for anterior coverage or when the gluteal vessels are sacrificed).
- Close in layers over drains. Apply negative-pressure wound therapy if flap perfusion is marginal.
- Primary closure or skin graft alone fails in greater than 30 percent of cases, so flap coverage is planned with plastic surgery before the first stage.
- Internal iliac vein injury during ligation causes massive venous bleeding. Pack the field and ligate proximal and distal control points; do not clip blindly.
- Ureteric injury is prevented by pre-operative stents and gentle medial retraction; recognise and repair any transection.
- Rectal perforation during mobilisation produces pelvic sepsis. Mobilise the rectum fully to the sacral promontory for high sacrectomy and repair immediately with diversion if recognised.
- Attempting a posterior-only resection without anterior vascular control makes massive haemorrhage almost inevitable — the internal iliac system and the presacral venous plexus (anterior to the sacrum below S2) are the leading causes of intraoperative death.
- Sciatic nerve transection during the notch osteotomy causes permanent foot drop. Identify and tag the nerve with a vessel loop before cutting, and remember Zone II tumours displace it laterally.
- Presacral venous bleeding: pack with haemostatic agents and apply pressure; do not attempt blind clipping.
- Dural tear during high sacral osteotomy: repair primarily or patch, and place a lumbar drain if a CSF leak persists.
- Flap venous congestion demands an immediate return to theatre for exploration.
Perform the anterior approach first. Vascular ligation of the internal iliac system roughly halves blood loss, ureteric stents placed the day before protect the ureters, and rectal mobilisation to the sacral promontory is confirmed with a finger before closing the anterior wound. For high sacrectomy, staging the anterior and posterior approaches 48 hours apart reduces physiological insult and blood loss compared with a single combined sitting.
A single-stage combined anterior-posterior resection increases operative time and blood loss without proven oncological benefit. Reserve it for carefully selected low sacrectomy or Zone III cases; default to the staged sequence for Zone II and high sacrectomy.
Aftercare & Complications
Post-operative protocol | Phase | Timing | Milestones | Precautions | |-------|--------|------------|-------------| | Intensive monitoring | Day 0 to 7 | ICU for 48 to 72 hours with massive transfusion readiness; drain and flap monitoring; LMWH and mechanical DVT prophylaxis; early enteral nutrition | Ureteric stents removed at 7 to 10 days if no leak | | Mobilisation | Week 2 to 12 | Bed to chair once the flap is stable (day 5 to 7); hip precautions if reconstructed (no active abduction for 6 weeks); protected sitting with a custom orthosis after lumbopelvic fixation | No bending or lifting after lumbopelvic fixation; wound review and suture removal at 2 weeks | | Rehabilitation | Month 3 to 12 | Progressive weight-bearing as tolerated; core, gait and upper-body therapy; stoma, catheter and sexual rehabilitation | Surveillance MRI at 3, 6 and 12 months, then annually for 5 years | Functional outcomes by resection level | Resection level | Continence and sexual function | Typical needs | |------------------|---------------------------------|---------------| | Low sacrectomy (below S3) | Greater than 80 percent maintain continence and sexual function | Usually none | | Middle sacrectomy (S2 to S3) | 40 to 60 percent retain partial continence | Most require intermittent self-catheterisation | | High sacrectomy (S1 to S2) | Greater than 80 percent lose bowel, bladder and sexual function | Permanent stoma and catheter in the majority | | Zone II custom prosthesis | MSTS score 60 to 75 percent | Independent ambulation with a cane; return to sedentary work | Complications
- Incidence
- Average 3 to 8 L; up to 15 L for high sacrectomy
- Recognition
- Sudden hypotension and tachycardia with visible bleeding from the presacral plexus or internal iliac branches
- Prevention and management
- Prevention: preoperative embolisation, anterior vascular ligation first, cell salvage, tranexamic acid, rapid infuser. Management: pack, ligate visible vessels, activate the massive transfusion protocol, consider interventional radiology if unstable
- Incidence
- Greater than 30 percent with primary closure; 15 to 25 percent with a flap
- Recognition
- Erythema, purulent discharge, flap necrosis, exposed hardware or prosthesis
- Prevention and management
- Prevention: VRAM or gluteal flap planned pre-operatively, perioperative antibiotics, negative-pressure dressing. Management: early debridement, culture-directed antibiotics, flap revision
- Incidence
- 5 to 15 percent permanent deficit
- Recognition
- Immediate foot drop, loss of plantarflexion, sensory loss in the sciatic distribution
- Prevention and management
- Prevention: identify and tag the sciatic nerve before osteotomy; avoid excessive traction. Management: ankle-foot orthosis; exploration and repair if recognised intra-operatively; tendon transfer for permanent deficit
- Incidence
- Greater than 80 percent after bilateral S2 sacrifice
- Recognition
- Urinary retention requiring a catheter, faecal incontinence requiring a stoma, loss of erection or ejaculation
- Prevention and management
- Prevention: pre-operative counselling with a stoma nurse; document the nerve-root level on consent. Management: permanent suprapubic catheter or intermittent self-catheterisation, colostomy, sexual rehabilitation referral
- Incidence
- 20 to 40 percent at 5 years for lumbopelvic fixation
- Recognition
- Pain, hardware breakage, progressive deformity, loss of sitting balance
- Prevention and management
- Prevention: rigid dual iliac screw construct; consider a custom prosthesis; protected weight-bearing for 3 months. Management: revision fixation with larger screws or anterior column support; custom revision prosthesis
- Incidence
- 20 to 50 percent at 5 years for chondrosarcoma or chordoma
- Recognition
- New mass on surveillance MRI, rising tumour markers, a new neurologic deficit
- Prevention and management
- Prevention: wide margins confirmed by frozen section; en-bloc resection without tumour violation. Management: re-stage; re-resect if feasible; palliative radiation or systemic therapy if unresectable
- Incidence
- Recognised complication of high sacrectomy
- Recognition
- Clear fluid from the wound on day 1 to 3
- Prevention and management
- Prevention: meticulous dural closure or patching; prophylactic lumbar drain for 5 days. Management: head-up bed rest, lumbar drainage (10 to 15 mL per hour), antibiotics; return to theatre for dural repair if persistent beyond 5 to 7 days
Viva & Exam Focus
ENNEKINGENNEKING — pelvic resection zones and reconstruction
SACRECTSACRECT — staged sacrectomy and functional trade-offs
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 42-year-old man presents with a 12 cm chordoma of the sacrum extending to the S1 to S2 level on MRI. Staging shows no metastases. What is your surgical plan and how do you counsel him regarding functional outcomes?”
“You are planning internal hemipelvectomy for a 35-year-old woman with chondrosarcoma involving the acetabulum (Enneking Zone II). She asks about reconstruction options and expected function. How do you respond?”
“A 58-year-old man undergoes high sacrectomy for chordoma with sacrifice of bilateral S1 and S2 roots. On post-operative day 3 he develops a CSF leak from the wound. How do you manage this?”
Enneking zones and reconstruction
- Zone I (ilium): usually no reconstruction; hip stable if the acetabular roof is preserved
- Zone II (periacetabulum): always reconstruct — custom endoprosthesis or hip transposition; a flail hip gives poor function
- Zone III (pubis or ischium): usually no reconstruction; hip stable
- Zone IV (sacrum): low (below S3) preserves continence; middle (S2 to S3) risks partial loss; high (S1 to S2) produces a permanent stoma and catheter in greater than 80 percent
- Lumbopelvic fixation after high sacrectomy: dual iliac screws plus S1 pedicle screws; non-union exceeds 20 percent at 5 years
Surgical approach sequence
- Anterior first: vascular ligation (internal iliac), visceral mobilisation, ureteric stents, anterior osteotomy if planned
- Posterior second: sciatic nerve identification, en-bloc osteotomies, reconstruction, flap coverage
- Staged 24 to 48 hours apart for high sacrectomy; a single stage increases blood loss and operative time
- Pre-operative embolisation 24 to 48 hours before reduces blood loss 30 to 50 percent in hypervascular tumours
- Plastic surgery consultation is mandatory — a VRAM or gluteal flap reduces wound complications from greater than 40 percent to 15 to 25 percent
Critical danger structures
- Sciatic nerve: identify and tag in the greater sciatic notch before a Zone II osteotomy; injury causes permanent foot drop
- Internal iliac vessels: ligate during the anterior approach; uncontrolled bleeding is the leading cause of intraoperative mortality
- Presacral venous plexus: anterior to the sacrum below S2; pack and apply pressure; avoid blind clipping
- Ureters: pre-operative stents are mandatory; injury produces a urinoma and fistula
- Rectum: mobilise to the sacral promontory for high sacrectomy; perforation produces pelvic sepsis
Margin and histology principles
- Chondrosarcoma and chordoma: wide margins (greater than 1 cm soft tissue or intact fascia) are mandatory; marginal resection yields greater than 50 percent recurrence
- The chordoma proximal osteotomy must be at least 1 cm above the upper tumour extent on MRI; a marginal proximal margin is the most common recurrence site
- Ewing sarcoma and osteosarcoma: neoadjuvant chemotherapy response (greater than 90 percent necrosis) improves survival; wide resection is still required
- Confirm proximal and soft-tissue margins with frozen section intra-operatively; re-resect if positive
- Intralesional or marginal resection in chondrosarcoma or chordoma is never acceptable for cure
Functional trade-offs by level
- Low sacrectomy (below S3): greater than 80 percent maintain continence and sexual function
- Middle sacrectomy (S2 to S3): 40 to 60 percent retain partial continence; most need intermittent catheterisation
- High sacrectomy (S1 to S2): greater than 80 percent need a permanent stoma and catheter; sexual function lost in the majority
- Zone II custom prosthesis: MSTS 60 to 75 percent; independent ambulation with a cane; hip precautions 6 to 12 weeks
- Hip transposition: MSTS 55 to 65 percent; lower infection risk than a prosthesis; limited abduction strength
Blood loss and reconstruction failure
- Average blood loss 3 to 8 L, up to 15 L for high sacrectomy — cell salvage, TXA and a rapid infuser are mandatory
- Wound infection or dehiscence: greater than 30 percent with primary closure; 15 to 25 percent with a flap
- Reconstruction non-union or hardware failure: 20 to 40 percent at 5 years for lumbopelvic fixation
- Local recurrence: 20 to 50 percent at 5 years for chondrosarcoma or chordoma; wide margins and frozen-section confirmation reduce risk
- Surveillance: MRI at 3, 6 and 12 months then annually for 5 years; lifelong implant surveillance if reconstructed
Background & Evidence
Why wide margins matter. Wide en-bloc resection with negative margins is the only curative treatment for chondrosarcoma and chordoma. Intralesional or marginal resection yields local recurrence rates of 50 to 70 percent and 5-year survival below 50 percent. Chordoma requires at least a 1 cm proximal bony margin on MRI; a marginal resection at the osteotomy line is the dominant recurrence mechanism. Neoadjuvant or adjuvant radiation improves local control in chordoma but does not replace wide surgical margins. For Ewing sarcoma and osteosarcoma, neoadjuvant chemotherapy followed by wide resection is standard, and a good histologic response (greater than 90 percent necrosis) improves survival; pelvic Ewing sarcoma has a worse prognosis than extremity sites, but complete resection with wide margins remains essential. Internal hemipelvectomy with reconstruction is preferred over external hemipelvectomy in responsive tumours. The Enneking classification is the universal language for pelvic resection planning. It defines four zones that guide both resection extent and the reconstruction decision.
- Anatomy resected
- Iliac wing from the sacroiliac joint to the acetabular roof
- Reconstruction
- Usually none; the hip stays stable if the acetabular roof is preserved
- Key structure at risk
- Abductor mechanism if it is sacrificed
- Anatomy resected
- Acetabulum and adjacent ilium and pubis
- Reconstruction
- Always required: custom endoprosthesis, hip transposition or allograft-prosthetic composite
- Key structure at risk
- Sciatic nerve and superior gluteal neurovascular bundle
- Anatomy resected
- Anterior pelvic ring (pubic rami and ischium) sparing the acetabulum
- Reconstruction
- Usually none; the hip stays stable
- Key structure at risk
- Obturator nerve and vessels during medial dissection
- Anatomy resected
- Sacrum, classified as low (below S3), middle (S2 to S3) or high (S1 to S2 or above)
- Reconstruction
- Lumbopelvic fixation after high sacrectomy; staged anterior-posterior approach
- Key structure at risk
- Sacral nerve roots — level dictates bowel, bladder and sexual function
Reconstruction outcomes. Custom 3D-printed endoprostheses and hip transposition after Zone II resection achieve better functional scores than a flail hip (MSTS scores 60 to 75 percent versus less than 40 percent). Lumbopelvic fixation after high sacrectomy allows sitting and limited ambulation, though non-union and hardware failure rates exceed 20 percent at 5 years. VRAM and gluteal myocutaneous flaps reduce wound complication rates from greater than 40 percent with primary closure to 15 to 25 percent.
References
Surgical management of sacral chordoma: a retrospective analysis of 166 cases
- Retrospective review of 166 sacral chordomas treated with en-bloc sacrectomy
- Wide margins achieved in 58 percent; local recurrence rate 44 percent at 5 years
- Survival significantly better with wide margins (66 percent) versus marginal or intralesional (40 percent)
En bloc resection of primary sacral tumors: classification of surgical approaches and outcome
- En bloc resection with wide margins achieved local control in the majority of sacral chordoma and sarcoma cases
- A staged anterior-posterior approach reduced complication rates compared with a single stage
Prognostic factors in chordoma of the sacrum and mobile spine: a study of 39 patients
- Wide surgical margins were the most important factor for local control and survival in sacral chordoma
- Local recurrence rate was high with inadequate margins; 5-year survival improved with en-bloc resection
Surgical treatment of pelvic sarcomas: oncologic and functional outcome
- Overall survival 52 percent at 5 years after pelvic sarcoma resection
- Reconstruction improved functional scores versus a flail hip after internal hemipelvectomy