Proximal femoral sarcoma or metastasis · modular megaprosthesis
- The operation has two equal halves you must never separate: an oncologically correct WIDE resection of the proximal femur (a normal marrow margin beyond the tumour, confirmed on frozen section, with the biopsy tract excised en bloc), and a stable reconstruction of the hip. A perfectly implanted prosthesis after an intralesional resection is an oncological failure.
- The proximal femur carries the abductors and the hip capsule; resecting it sacrifices your hip stabilisers. The dominant complication — DISLOCATION — is driven by soft-tissue loss, and the single most important step that controls it is reconstruction of a pseudo-capsule (synthetic mesh) and reattachment of the abductors and greater trochanter.
- The distal stem is cemented into the residual femur; the modular body segment is sized to the measured resection length. A bipolar head is the default articulation (lowest dislocation when the acetabulum is native); use a dual-mobility or constrained construct when the abductors and capsule are sacrificed.
- Infection is the other major enemy — a large implant, a long operating time, and (in sarcoma) a patient on chemotherapy and often pre-operative radiotherapy. Meticulous technique, prophylactic antibiotics and reliable soft-tissue cover are non-negotiable.
- Separate curative-intent (primary sarcoma: wide margins, neoadjuvant chemotherapy, plan for decades of survivorship) from palliative (metastatic: immediate stability and full weight-bearing, prognosis-driven). The Mirels score flags the impending pathologic fracture; a Katagiri-type score frames prognosis.
When & Why
Indication. A tumour of the proximal femur that destroys bone to a degree the hip cannot be saved and ordinary internal fixation will not hold — either a primary bone sarcoma (osteosarcoma, Ewing sarcoma, chondrosarcoma) requiring a wide resection for cure, or metastatic bone disease (breast, lung, prostate, renal, thyroid, myeloma) with an impending or completed pathologic fracture and extensive proximal-femoral destruction. For the metastatic patient the question is mechanical: a Mirels score of 9 or greater predicts an impending fracture and justifies prophylactic stabilisation, and a lesion that has already destroyed the femoral neck or subtrochanteric region beyond what a cephalomedullary nail or plate-and-cement can reconstruct is best treated by replacing the proximal femur. Two populations, one operation, different rules. Keep them separate at every decision point: - Primary sarcoma (curative intent). Goal is a wide Enneking margin with long-term local control. Staging is complete before surgery (whole-bone MRI for marrow extent, CT chest and a bone scan or whole-body MRI for distant disease), the biopsy tract is planned to lie within the resection field, and reconstruction is built for decades. Neoadjuvant chemotherapy frames the timing.
- Metastatic disease (palliative, function-driven). Goal is pain relief, immediate stability and full weight-bearing in one operation, calibrated to prognosis. A shorter, faster construct and a familiar exposure are reasonable; oncological margins are not the point. Estimate prognosis (a Katagiri-type score, considering primary site, visceral metastases, performance status) so you neither over-treat a patient with weeks to live nor under-treat one with years. The one decision that matters — can you save the limb, and what do you rebuild it with? Neurovascular encasement, uncontrolled infection, or extensive contamination from a poorly placed biopsy may force amputation (hip disarticulation). Assuming the limb is salvageable, the proximal femur is resected and the choice is how to reconstruct:
The default. A modular body segment is sized to the resection length and a stem is cemented into the distal femur, giving immediate, durable stability and full weight-bearing. The trade-off is the loss of native abductor and capsule attachment, which you must reconstruct.
A bulk allograft restores bone stock and gives native soft-tissue anchors (greater trochanter, capsule, abductors) for reattachment. Favoured in younger, curative-intent patients — at the cost of graft non-union, resorption, fracture and higher infection.
For extensive diaphyseal disease, skip lesions or multi-focal metastatic involvement that runs beyond the proximal femur. Maximum implant and soft-tissue burden; reserved for salvage.
Consent specifically for the two dominant risks — dislocation and infection — plus leg-length inequality, the possibility of further surgery (revision, flap cover, or amputation for uncontrolled infection or local recurrence), and the lifelong implications of a large implant. For sarcoma, counsel on the impact of chemotherapy and radiotherapy timing on wound healing. Setup. Lateral decubitus (or supine with a sandbag under the ipsilateral buttock for the anterolateral exposure), on a radiolucent table with imaging available. General anaesthesia plus a regional catheter, large-bore access, and a cell saver where appropriate (the field is vascular). Prophylactic antibiotics at induction and repeat as the operation lengthens. Plan the draping so the whole leg is free to manipulate for trial reduction. A hip abduction orthosis (brace) must be ready on the shelf before you start — you will need it at the end.
The Operation
The goal: resect the proximal femur through normal tissue with the biopsy tract en bloc, restore femoral length and offset with a cemented modular megaprosthesis, and reconstruct the capsule and abductors so the hip stays reduced. The exposure is laid out in full below; for selected palliative metastatic replacements some surgeons use the familiar posterior (Southern/Moore) approach to the hip for speed, but the extended lateral/anterolateral approach is the workhorse because it allows en-bloc resection and an anterior dislocation — and a lower dislocation rate when the abductors are deficient.
Intra-operative view of the modular proximal femoral megaprosthesis trialled in the resected femoral bed — the cemented distal stem, modular body segment and bipolar head before reduction, with the sciatic nerve protected posteriorly and the capsule-mesh and trochanteric reattachment prepared.
Context: A verified image is being sourced.
Operative sequence
- Confirm the marrow extent on the pre-operative whole-bone MRI and mark the planned distal osteotomy — through normal marrow with a margin (commonly 3 cm or more beyond the tumour).
- Mark a long lateral incision over the greater trochanter and down the femur that incorporates the biopsy tract as an ellipse, so it is excised en bloc with the specimen. A badly placed biopsy tract that crosses a clean plane is the classic reason a salvageable case becomes an amputation — the tract and any haematoma are part of the tumour.
- Incise skin and fat down to fascia lata, ellipting the biopsy tract cleanly down to deep fascia and discarding it without ever breaching it.
- Divide fascia lata in line with the incision. Identify and coagulate the perforating branches of the profunda femoris as they pierce the lateral intermuscular septum — they are the source of most intra-operative bleeding.
- Reflect vastus lateralis anteriorly off the lateral intermuscular septum (or split it) to expose the proximal femoral shaft and the subtrochanteric region.
- Identify and protect the sciatic nerve posteriorly, deep to the short external rotators, before any posterior dissection.
- Protect the profunda femoris and its perforators medially and the femoral nerve and vessels anteriorly — keep close to bone on the medial proximal femur and ligate perforators as they are met.
- Expose the hip capsule anteriorly and superiorly. Manage the abductors to preserve them for later reconstruction: either osteotomise the greater trochanter with a sliver of bone (retaining gluteus medius–minimus and vastus lateralis in continuity), or release the anterior third of the abductors off the trochanter with a soft-tissue cuff.
- Open the capsule, release it circumferentially from the femoral neck and tag the flaps — this capsule will be used (or augmented with mesh) at reconstruction.
- Using the pre-operative plan and intra-operative measurement, mark the distal femoral osteotomy.
- After the cut, send marrow from the distal stump for frozen section to confirm the margin is clear. Only proceed once the margin is confirmed — lengthening the resection is easy now and impossible once the prosthesis is cemented.
- Osteotomise the femoral neck, then the shaft at the planned distal level.
- Dissect the proximal-femoral specimen free medially, ligating the remaining perforators, and deliver it en bloc with the biopsy tract. Measure the resection length precisely — this sets the modular body size.
- Ream the distal femoral canal and prepare a cement restrictor; lavage and dry the canal.
- Assemble the modular body segment to match the measured resection length; cement the distal stem with modern cementing technique, setting the component in appropriate anteversion and restoring femoral offset and length.
- Trial the head and neck; reduce and check leg length, offset and stability through a full arc of motion.
- With a native, uninvolved acetabulum, use a bipolar head — the default, with the lowest dislocation rate in the deficient-abductor setting.
- If the acetabulum is involved (or for added longevity in a selected patient), use a total hip replacement with an acetabular component — accepting a higher dislocation risk.
- When the abductors and capsule have been sacrificed (highest dislocation risk), use a dual-mobility (large jump distance) or, as a last resort, a constrained construct — the latter buys stability at the cost of restricted range of motion and higher loosening forces.
- Reconstruct a pseudo-capsule around the prosthesis using a synthetic mesh (Trevira, LARS or Dacron), suturing it to the residual capsule and soft tissues to encase the head-neck junction. This is the step that most reduces dislocation.
- Reattach the greater trochanter and abductor mass to the prosthesis — a trochanteric claw or grip with cerclage cables, or a mesh sleeve over the prosthesis — under appropriate tension. Without this there is no active abduction and the hip will dislocate.
- Achieve meticulous haemostasis, place deep drains, and close in layers over the reconstruction — viable, well-covered soft tissue is the best defence against infection.
- Apply a hip abduction orthosis in neutral-to-slight abduction before the patient leaves the table, to protect the abductor and capsule repair and reduce early dislocation.
Through every step, keep the sciatic nerve identified and protected posteriorly (it lies deep to the short external rotators and is at risk during posterior dissection and retractor placement) and control the perforating branches of the profunda femoris deliberately as they pierce the lateral intermuscular septum — they are the source of brisk bleeding and of post-operative haematoma that threatens the wound. If a vessel retracts, do not blind-clip medially where the femoral vessels lie; compress, expose and ligate under vision.
Proximal femoral replacement has one of the highest dislocation rates of any hip reconstruction because the abductors and capsule — the hip's soft-tissue stabilisers — are resected with the specimen. Reconstructing a pseudo-capsule with synthetic mesh and reattaching the greater trochanter/abductor mass restores a soft-tissue envelope around the prosthesis and is the single manoeuvre that most lowers dislocation. Articulation choice (bipolar, then dual-mobility, then constrained) is a sliding scale you escalate as soft-tissue loss increases.
A bipolar head is right when the acetabulum is native — it has the lowest dislocation rate when abductors are deficient. Reach for dual-mobility when the capsule and abductors are sacrificed, and reserve a constrained liner for the irreducibly unstable hip, because it restricts range of motion and transmits higher torque to the cement–bone interface. A total hip replacement is only chosen when the acetabulum is diseased or when added longevity justifies the dislocation risk.
Aftercare & Complications
Rehabilitation | Phase | Timing | Weight-bearing | Bracing and therapy | |-------|--------|----------------|---------------------| | 1 | 0–2 weeks | Touch-down to partial | Hip abduction orthosis at all times; bed exercises, chest care, DVT prophylaxis | | 2 | 2–6 weeks | Partial, increasing as the abductor repair allows | Continue brace; gait re-education, gentle hip abductor and quadriceps isometrics | | 3 | 6–12 weeks | Progress to full (metastatic often full earlier; sarcoma later) | Wean the brace as soft tissues heal; abductor strengthening | | 4 | 3–6 months | Full | Graded return to function; lifelong precautions if abductors are deficient | Most metastatic patients bear full weight early and gain rapid pain relief — the whole point of the operation. Sarcoma patients progress more cautiously around their abductor and capsule reconstruction and their chemotherapy cycles. A patient without functioning abductors will always need a brace or an abduction aid and should be counselled to a lifelong abduction precaution. Complications
| Complication | Recognition | Prevention | Management |
|---|---|---|---|
| Infection | Wound breakdown, persistent pain, sinus, raised inflammatory markers; often late and indolent | Prophylactic antibiotics, laminar flow theatre, minimal traffic, reliable soft-tissue cover, avoid irradiated wound when possible | Debridement and antibiotics; one- or two-stage revision; flap cover; amputation as last resort |
| Dislocation | Shortened, internally rotated leg, severe pain; recurrence on minimal movement | Bipolar/dual-mobility, capsule mesh, trochanter reattachment, correct leg length, post-operative brace | Closed reduction and brace; recurrent instability — revision with constrained construct |
| Aseptic loosening | Thigh pain, progressive radiolucency at the cement–bone interface, stem subsidence | Sound cement technique, adequate distal stem length, restored offset | Revision of the loose component |
| Leg-length inequality | Limp, low-back pain, apparent length difference on examination | Pre-operative templating, trial reduction, intra-operative measurement | Shoe raise; revision only if severe and symptomatic |
| Periprosthetic fracture | Pain and deformity around the stem tip, usually after a fall | Careful reaming, avoid notching the distal cortex | Revision to a longer stem; plating where appropriate |
| Local recurrence | New pain or mass, soft-tissue or marrow change on imaging | Wide Enneking margins confirmed on frozen section | Wide re-excision or amputation; oncology review for further therapy |
| Wound breakdown / haematoma | Edge necrosis, seroma, wound dehiscence in the early weeks | Meticulous haemostasis, drains, tension-free closure, healthy cover | Plastics cover, negative-pressure dressing, early debridement |
Viva & Exam Focus
REPLACEREPLACE — the operation in order
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 68-year-old woman with metastatic renal-cell carcinoma has a large lytic lesion of the proximal femur with a Mirels score of 10 but no fracture. How do you manage her?”
“A 24-year-old man has an Enneking Stage IIB high-grade osteosarcoma of the proximal femur. Describe your limb-salvage resection and reconstruction, and how you minimise dislocation.”
Indication
- Primary sarcoma (curative, wide margin) or extensive metastatic destruction (palliative, mechanical)
- Mirels 9 or greater equals impending pathologic fracture; Katagiri frames prognosis
Exposure
- Extended lateral/anterolateral approach; ellipse and excise the biopsy tract
- At risk: sciatic nerve posteriorly, profunda perforators and femoral vessels medially/anteriorly
Resection
- Enneking-wide; distal osteotomy through normal marrow, 3 cm or more beyond tumour
- Frozen-section margin; deliver the specimen en bloc with the biopsy tract
Reconstruction and dislocation
- Modular body sized to resection, cemented distal stem, restored offset and version
- Bipolar default; dual-mobility or constrained if abductors/capsule sacrificed
- Capsule mesh plus greater-trochanter reattachment is the key dislocation-mitigation step; brace post-operatively
Aftercare
- Weight-bearing calibrated to prognosis and abductor repair; hip abduction orthosis
- Watch infection and dislocation first; aseptic loosening long-term; lifelong abduction precautions if abductors deficient
Background & Evidence
Epidemiology. The proximal femur is one of the most common skeletal sites involved by both primary bone sarcomas and metastatic disease. Osteosarcoma and Ewing sarcoma cluster in the metadiaphyseal region around the knee and the proximal femur; chondrosarcoma frequently arises in the proximal femur and pelvis. Metastatic bone disease is far more common than primary tumour overall — breast, prostate, lung, renal and thyroid carcinoma and myeloma all seed the proximal femur, and a destructive lesion there in an adult is statistically far more likely to be metastatic than primary. Because the proximal femur carries the majority of load in gait, involvement there threatens both fracture and the loss of independent mobility. Pathoanatomy. The proximal femur is not just a load-bearing strut — it is the anchor for the hip abductors (gluteus medius and minimus on the greater trochanter) and the hip capsule, which together stabilise the joint. Tumour destruction of the femoral neck or subtrochanteric region therefore causes two problems at once: a mechanical loss of bony continuity (the pathologic fracture) and the removal of the hip's soft-tissue stabilisers when the segment is resected. It is this second problem — the loss of abductor and capsular attachment — that makes reconstruction uniquely demanding and drives the high dislocation rate, and it is why soft-tissue reconstruction, not the metalwork, is the make-or-break step of the operation. Surgical margins. The quality of the resection is graded by the Enneking system, and it determines local control in primary sarcoma. A wide margin — a cuff of normal tissue outside the reactive zone — is the standard aim for limb-salvage resection.
| Margin | Definition | Oncological adequacy |
|---|---|---|
| Intralesional | Dissection passes through the tumour; tumour left behind | Inadequate for sarcoma — high local recurrence |
| Marginal | Through the reactive zone / pseudocapsule | Leaves microscopic disease and skip lesions; inadequate alone |
| Wide | Through normal tissue, a cuff outside the reactive zone | The standard aim of limb-salvage resection |
| Radical | The entire compartment removed with the tumour | Historically curative; rarely required with modern wide excision |
References
Metastatic disease in long bones — a proposed scoring system for impending pathologic fracture
Defined the four-variable scoring system (site, pain, lesion type, size) that still guides the decision to stabilise an impending pathologic fracture prophylactically, with a threshold of 9 or greater indicating high risk.
A system for the surgical staging of musculoskeletal sarcoma
Established the grade–compartment–metastasis staging system and the surgical-margin definitions (intralesional, marginal, wide, radical) that still frame the planning of a sarcoma resection.
Prognostic factors and a scoring system for patients with skeletal metastasis
A validated prognostic score — built on primary site, visceral metastases and performance status — that calibrates how aggressive skeletal reconstruction should be in metastatic bone disease.
Endoprosthetic replacement of the proximal femur for tumour — outcomes and survivorship
A large centre series of proximal femoral endoprosthetic replacements reporting good functional outcomes, with infection and dislocation as the leading early modes of failure and aseptic loosening as the principal long-term concern.