High-yield overview

Joint-preserving en-bloc resection for a diaphyseal sarcoma · osteosarcoma, Ewing sarcoma

Wide marginThe non-negotiable

Native joints preservedThe whole advantage

NonunionThe dominant complication

6–12 monthsTypical time to union

Critical Must-Knows

Intercalary resection is an en-bloc, joint-PRESERVING resection of a diaphyseal bone segment for a malignant (or aggressive) bone tumour that does NOT reach the adjacent epiphysis and articular surface. The oncological margin is paramount and must never be trimmed to save the joint — if the tumour reaches the epiphysis, convert to a joint-sacrificing resection.
The defining advantage is preservation of the native joints (and, in children, the growth plates), which gives superior function over a joint-replacing reconstruction. It is feasible only when pre-operative MRI shows a clear margin of normal bone between the tumour and the epiphysis.
The reconstruction decision is biological versus mechanical, choosing between a structural intercalary allograft, a vascularised fibular graft, an allograft-vascularised fibula composite (the Capanna technique), or an intercalary metallic spacer.
The dominant complications are nonunion at one or both host-graft junctions, late graft fracture, deep infection and hardware failure — all made worse by chemotherapy and radiotherapy.
Rigid fixation at BOTH junctions and a healthy biological environment drive union. In an irradiated or chemotherapy-compromised bed, prefer living tissue — a vascularised fibula or the Capanna composite — over an avascular allograft alone.

When & Why

Indication. A primary malignant bone tumour — most often osteosarcoma or Ewing sarcoma, less commonly other sarcomas — or an aggressive locally destructive lesion, arising in the diaphysis (or diaphyseal-metaphyseal region) of a long bone (femur, tibia, humerus), where limb-salvage surgery is appropriate and the tumour can be removed with a wide margin while leaving the adjacent epiphysis and articular surface intact. The feasibility test. Pre-operative MRI of the whole bone must show a clear margin of normal bone between the tumour (including its extraosseous extension and reactive zone) and the adjacent epiphysis, so that osteotomies can be placed through normal bone and the joint capsule and ligaments preserved. If the tumour extends to the epiphysis or joint, intercalary resection is not appropriate — convert to an intra-articular (joint-sacrificing) resection and a joint-replacing reconstruction. Workup before theatre. Confirm the diagnosis on biopsy (placed within the eventual incision so it is excised en-bloc), stage the patient (whole-bone MRI for skip lesions, chest CT for pulmonary metastases, a bone scan or whole-body MRI, often PET-CT), and give neoadjuvant chemotherapy for osteosarcoma and Ewing sarcoma. Plan the proximal and distal osteotomy levels from the MRI, accounting for the pre-chemotherapy tumour extent plus a safe cuff. The key reconstruction decision — biological versus mechanical:

Structural allograft

A cadaveric bone segment cut to the defect. Biological but avascular — immediate structure with slow, partial incorporation and a real risk of nonunion and late fracture.

Vascularised fibula

A free or pedicled living fibula on its peroneal pedicle. Unites reliably and hypertrophies with load — the best choice in irradiated or compromised beds, at the cost of donor-site morbidity.

Capanna composite

The vascularised fibula nested inside the medullary canal of a structural allograft. Combines the allograft's immediate mechanical stability with the living fibula's biology — the workhorse for large defects.

Intercalary spacer

A custom or modular metallic endoprosthesis, usually on a cemented intramedullary stem. Immediate stability and rapid recovery, but non-biological, with long-term loosening.

Consent specifically for local recurrence, nonunion requiring further surgery, late graft fracture, deep infection (which can mean graft removal), hardware failure, limb-length discrepancy, and — if a fibula is used — donor-site problems (foot drop from peroneal nerve injury, ankle pain or valgus). Setup. Supine for most long-bone sites, a tourniquet where the limb allows, general anaesthesia with regional adjuncts, and fluoroscopy to mark the osteotomy levels and check fixation. A two-team approach is standard when a vascularised fibula is harvested from the contralateral leg while the resection proceeds, shortening operating time.

The Operation

The goal: resect the diaphyseal tumour en-bloc with a wide margin while preserving the adjacent joints, then reconstruct the segmental defect with a construct that is mechanically stable and biologically capable of uniting, restoring length, alignment and rotation so the limb functions.

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Image Needed: Clinical PhotoHigh Priority

Intra-operative view of a long-bone intercalary defect reconstructed with an allograft–vascularised-fibula composite (Capanna technique) spanning the segment and locked with an intramedullary nail, the native joints above and below preserved.

Context: A verified image is being sourced.

Pending image generation or sourcing

Operative sequence

Step 1Position, plan and mark the biopsy tract

Supine, tourniquet where applicable, fluoroscopy in the field.
Re-confirm the planned proximal and distal osteotomy levels against the pre-operative MRI on intra-operative imaging — they must sit in normal bone beyond the tumour and its reactive zone.
Mark the previous biopsy tract so it is excised en-bloc in continuity with the specimen.

Step 2Incision and biopsy-tract excision

A longitudinal incision over the involved segment — lateral femur, anteromedial tibia, anterolateral or deltopectoral humerus — designed to incorporate and excise the biopsy tract.
Carry the incision directly to bone through one internervous plane; do not raise subcutaneous flaps over the tumour.

Step 3Dissection to bone — protect the neurovascular bundle

Develop the internervous or intermuscular plane and elevate muscle to expose the bone circumferentially at the planned osteotomy levels, keeping a continuous cuff of normal tissue around the tumour and any extraosseous component (a WIDE margin).
Identify, isolate and protect the named neurovascular bundle for that bone: the superficial femoral and profunda vessels for the femur, the anterior tibial artery and deep peroneal nerve crossing the interosseous membrane for the tibia, and the radial nerve in the spiral groove for the humerus. Ligate perforators as they are met.

Step 4Define osteotomy levels and protect the joints

Using fluoroscopy and the pre-operative MRI, mark the proximal and distal cuts through normal bone, confirming a wide margin beyond tumour plus reactive zone.
Confirm the epiphyses, the joint capsule and the cruciate/collateral ligaments are clear of the field and will remain in continuity with the preserved bone ends.

Step 5Proximal and distal osteotomies — the resection

Complete both cuts and deliver the diaphyseal segment en-bloc with its biopsy tract and soft-tissue cuff.
Immediately confirm margins — measure the bony cuff at each end and send marrow from the osteotomy faces for frozen section. The native joints remain attached to their epiphyses.

Step 6Measure the defect and prepare the reconstruction

Record the defect length, the canal diameter and the required alignment and rotation.
Cut the allograft to length, or size the endoprosthesis; concurrently, a second team harvests the vascularised fibula with its peroneal pedicle, or assembles the Capanna composite by nesting the fibula inside the allograft medullary canal.

Step 7Reconstruction and fixation — rigid at BOTH junctions

Seat the construct and obtain rigid fixation at both host-graft junctions: compression plating, a locked intramedullary nail, or both.
For the Capanna composite, a long locked intramedullary nail spans the host-allograft-fibula-host unit and gives immediate stability; for the vascularised fibula alone, complete the microvascular anastomosis to recipient vessels and confirm flow.

Step 8Confirm alignment, length, rotation and stability

Fluoroscopic check of overall alignment, limb length and rotation, comparing with the contralateral side.
Confirm rigid stability and that the preserved native joints move freely through a full, stable range.

Step 9Soft-tissue cover and closure

Achieve well-vascularised muscle cover over the graft, construct and anastomosis; in an irradiated or thin bed, plan a local or free flap at the outset.
Meticulous haemostasis, closed-suction drains, and layered closure over the reconstruction.

The margin is paramount — never compromise it to save the joint

The entire purpose of the operation is oncological control. If the pre-operative MRI or the intra-operative findings show tumour extending to the epiphysis, articular surface or joint capsule, abandon the intercalary resection and convert to a joint-sacrificing (intra-articular) resection. Likewise protect the named neurovascular bundle for the bone, and — when harvesting the fibula — the common peroneal nerve at the fibular neck and the ankle syndesmosis (leave 6 to 8 cm of distal fibula and stabilise the ankle).

Fixation at both junctions — the key to union

Rigid fixation at BOTH host-graft junctions is the single most important technical driver of union. The Capanna composite earns its place because the allograft supplies immediate mechanical stability while the vascularised fibula supplies living bone that hypertrophies and unites reliably — the best answer for a large or biologically compromised defect.

Why chemo and radio change your choice

Neoadjuvant chemotherapy (notably methotrexate and the multi-agent osteosarcoma and Ewing regimens) and radiotherapy markedly raise the risks of nonunion, graft fracture and infection. In an irradiated or chemotherapy-compromised bed, prefer living tissue — a vascularised fibula or the Capanna composite — over an avascular allograft alone.

Aftercare & Complications

Rehabilitation | Phase | Timing | Protection | Milestones | |-------|--------|------------|------------| | 1 | 0–6 weeks | Splint or brace; non- or toe-touch weight-bearing in the lower limb | Wound healing, DVT prophylaxis, isometrics | | 2 | 6–12 weeks | Progressive weight-bearing as callus and union signs appear | Radiographic union at one or both junctions | | 3 | 3–6 months | Full weight-bearing once union is confirmed | Return to light daily activity | | 4 | 6–24 months | Activity graded to graft incorporation and fibula hypertrophy | Living-fibula hypertrophy; full activity | Union typically takes 6 to 12 months. A vascularised fibula hypertrophies with load over one to two years, whereas an avascular allograft incorporates only partially. Functional outcomes (Musculoskeletal Tumour Society, MSTS, scores) are generally good, and the central benefit — a preserved native joint — usually outperforms a joint-replacing reconstruction. Complications

Complications — recognition, prevention, management
Complication	Recognition	Prevention	Management
Nonunion (junction)	Persistent pain with no bridging callus on serial radiographs at 6–12 months; confirmed on CT	Rigid fixation at both junctions; healthy biological environment; avoid a gap at the osteotomy	Exclude infection; autograft and revise fixation; convert to a vascularised fibula if refractory
Graft fracture (allograft)	Acute pain or deformity after minor trauma, often months to years later	Avoid stress-risers; protected loading until incorporated; composite with a vascularised fibula	Revision fixation with bone graft, or conversion to a vascularised fibula or endoprosthesis
Deep infection	Wound breakdown, sinus, systemic sepsis, raised inflammatory markers	Prophylactic antibiotics, meticulous soft-tissue cover, minimise dead space	Debridement and antibiotics; often graft removal with staged revision
Hardware failure	Pain with loosening or breakage of plate, screws or nail on radiograph	Appropriate implant choice and biological fixation	Revision fixation
Local recurrence	New mass or pain; new lesion on imaging	A wide margin at the index operation	Wide re-resection; may require amputation
Donor-site morbidity (fibula)	Foot drop from common peroneal nerve injury; ankle pain or valgus	Protect the peroneal nerve; leave 6–8 cm of distal fibula; stabilise or fuse the syndesmosis	Ankle bracing; tendon transfer for a drop foot; ankle fusion if unstable

Viva & Exam Focus

Mnemonic

REBUILDREBUILD — the intercalary reconstruction thought-sequence

Resect wide

The margin is paramount — never trim it to save the joint

Environment

Is the bed chemotherapy- or radiotherapy-compromised?

Biological or mechanical

Choose the construct — allograft, fibula, composite or spacer

Union

Rigid fixation at BOTH host-graft junctions

Intact joints preserved

The whole point of the intercalary approach

Look out for nonunion, fracture, infection

The dominant complications

Donor site

Fibula — protect the peroneal nerve and the ankle

Clinical Decision Scenarios

Practise clinical reasoning and management decisions out loud

Viva scenarioStandard

Clinical prompt

“A 17-year-old has an osteosarcoma of the femoral diaphysis; the MRI shows the tumour does not reach the distal femoral epiphysis. Outline your management and the reconstruction options.”

Practical approach

I confirm the diagnosis on biopsy (the tract placed within the eventual incision), stage the patient with whole-bone MRI for skip lesions, a chest CT and a bone scan, and start neoadjuvant chemotherapy. Because the tumour is diaphyseal with a clear margin to the epiphysis on MRI, an intercalary, joint-preserving resection is appropriate — a wide en-bloc resection of the involved diaphysis with the adjacent epiphyses and the knee preserved. I plan the osteotomy levels from the MRI to achieve a wide margin through normal bone. For reconstruction the options are a structural intercalary allograft, a vascularised fibular graft, an allograft-vascularised fibula composite (the Capanna technique), or an intercalary endoprosthesis. My choice balances defect size and the biological environment: in a large or chemotherapy-compromised defect I favour living tissue — a vascularised fibula or the Capanna composite — fixed rigidly at both junctions, because the dominant complications are nonunion, fracture and infection. Preserving the native knee and its growth potential is the functional advantage of the intercalary approach.

Key clinical points

Biopsy, stage, and neoadjuvant chemotherapy before resection

Intercalary resection is feasible only if MRI shows a clear margin to the epiphysis

Four reconstruction options; favour living tissue (fibula or Capanna composite) in compromised beds

The advantage is the preserved native joint and growth potential

Common pitfalls

Offering an intercalary resection when the tumour reaches the epiphysis or joint

Forgetting that the margin is paramount and cannot be trimmed to preserve the joint

Further questions

“How would your reconstruction choice change if this field had received pre-operative radiotherapy?”

Viva scenarioAdvanced

Clinical prompt

“Six months after an intercalary resection of the tibia reconstructed with an allograft there is no bridging at the distal host-graft junction and the patient has pain. How do you manage this nonunion?”

Practical approach

I confirm a nonunion with serial radiographs and a CT — nonunion at one junction is the commonest allograft complication. First I exclude and treat reversible factors: infection (inflammatory markers and an aspirate), smoking, and inadequate mechanical stability. For an aseptic, hypertrophic nonunion with stable hardware I bone-graft the junction (autograft) and optimise the mechanics; if the construct is unstable I revise the fixation. If the nonunion is atrophic or oligotrophic, the bed is poor, or initial grafting fails, I convert to living tissue — a vascularised fibular graft, alone or as a Capanna composite — which unites reliably even in compromised environments. Throughout I protect the soft-tissue envelope and keep the patient under oncological surveillance, because a nonunion can mask local recurrence; I also reassess the proximal junction and the graft itself for fracture or infection.

Key clinical points

Nonunion at a junction is the commonest allograft complication

Exclude infection first, then address biology and mechanics

Autograft with revised fixation for an aseptic nonunion; convert to a vascularised fibula if it fails or the bed is poor

Maintain oncological surveillance — a nonunion can hide local recurrence

Common pitfalls

Treating a nonunion without first excluding infection or local recurrence

Persisting with an avascular allograft in a compromised biological bed

Further questions

“What are the donor-site complications of a vascularised fibular graft, and how do you prevent them?”

Exam day cheat sheet

Intercalary resection — exam-day essentials

Indication

Diaphyseal sarcoma (osteosarcoma, Ewing) with a clear MRI margin to the epiphysis
Biopsy, stage and neoadjuvant chemotherapy first

The principle

En-bloc WIDE resection preserving the adjacent joints and growth plates
Margin is paramount — convert to a joint-sacrificing resection if the tumour reaches the epiphysis

Reconstruction

Four options: allograft, vascularised fibula, Capanna composite, intercalary spacer
Favour living tissue (fibula or composite) in chemotherapy- or radiotherapy-compromised beds

Fixation

Rigid fixation at BOTH host-graft junctions (compression plating and/or a locked intramedullary nail)

Complications

Nonunion, graft fracture, infection, hardware failure — all worsened by chemo and radio
Donor site: peroneal nerve and ankle (fibula)

Background & Evidence

Epidemiology. Osteosarcoma and Ewing sarcoma are the commonest primary malignant bone tumours of children and young adults. Both frequently involve the long-bone metaphysis and diaphysis (femur around the knee, proximal tibia and humerus); a diaphyseal location is classic for Ewing sarcoma and occurs in a subset of osteosarcoma. Only those tumours that spare the epiphysis on MRI are candidates for a joint-preserving intercalary resection. Pathoanatomy. The tumour arises in the medullary canal and may erode the cortex into the extraosseous soft tissues; the surrounding reactive oedema zone and any skip lesions must be accounted for when planning margins. Neoadjuvant chemotherapy usually shrinks the tumour and devitalises the extraosseous component, but the margin is planned on the original pre-chemotherapy extent plus a safe cuff. Joint preservation depends on an uninvolved epiphysis and an intact physis and articular surface. Enneking staging grades musculoskeletal sarcomas by biological grade (low-grade I, high-grade II), anatomical site (intracompartmental A, extracompartmental B) and the presence of metastasis (III); together with the surgical margin concepts below, it determines whether limb-salvage with a wide margin is achievable. Intercalary resection always targets a wide margin — intralesional or marginal margins risk local recurrence.

Surgical margins in musculoskeletal tumour surgery (Enneking)
Margin	Definition	Place in intercalary resection
Intralesional	Dissection passes through the tumour — tumour is left behind	Unacceptable for a sarcoma
Marginal	Dissection through the reactive zone immediately outside the tumour	High risk of recurrence — not adequate alone
Wide	A continuous cuff of normal tissue around the tumour and its reactive zone	The minimum acceptable margin — the target of intercalary resection
Radical	Removal of the entire compartment containing the tumour	Generally not required if a wide margin is achievable

Key evidence. Enneking established the staging system and margin principles that govern limb-salvage resection. Mankin's large allograft series defined the role and the complication profile of structural allografts (nonunion, fracture and infection depending on graft type, fixation and biological environment). Weiland established vascularised fibular transfer for skeletal defects, showing that a living fibula unites reliably and hypertrophies with load even in compromised beds. Capanna's allograft-vascularised fibula composite combined the allograft's mechanical stability with the fibula's biology, improving union in large and compromised defects.

References

Evidence

A system for the surgical staging of musculoskeletal sarcoma

Enneking WF, Spanier SS, Goodman MA • Clinical Orthopaedics and Related Research (1980)

Key Findings:

Established the surgical staging system that grades musculoskeletal sarcomas by grade, anatomical site and metastasis
Defined the surgical margin concepts (intralesional, marginal, wide, radical) that govern limb-salvage resection and the decision to preserve a joint

Evidence

Long-term results of allograft replacement in the management of bone tumors

Mankin HJ, Gebhardt MC, Jennings LC, Springfield DS, Tomford WW • Clinical Orthopaedics and Related Research (1996)

Key Findings:

A large multi-decade series of massive allografts from a major tumour centre, reporting outcomes across intercalary, osteoarticular and arthrodesis grafts
Showed that union and complication rates (nonunion, fracture, infection) depend on graft type, fixation quality and the biological environment

Evidence

The allograft–vascularised fibula composite for intercalary reconstruction (Capanna technique)

Capanna R, Campanacci DA, Beltrami G, et al. • Clinical Orthopaedics and Related Research (2007)

Key Findings:

Described nesting a vascularised fibula inside a structural allograft to reconstruct large intercalary defects
The composite combines the allograft's immediate mechanical stability with the living fibula's biology, improving union in large and biologically compromised defects

Evidence

Vascularised free bone grafts (vascularised fibular transfer) for skeletal defects

Weiland AJ, Moore JR, Daniel RK • Clinical Orthopaedics and Related Research (1983)

Key Findings:

Established the vascularised fibula as a reliable reconstructive option for segmental skeletal defects
A living fibula unites reliably and hypertrophies with load, performing well even in irradiated or compromised beds