Tumour Endoprosthesis Reconstruction

What types of endoprostheses are available?

Adult standard endoprostheses include:

• Distal femur — the most common, replacing the knee joint with a fixed-hinge design.
• Proximal tibia — includes a tibial tubercle attachment for the patellar tendon.
• Proximal femur — replaces the hip joint with an acetabular component.
• Intercalary — replaces mid-shaft segments while preserving native joints.
• Total femur — replaces the entire femur from hip to knee.

Expandable endoprostheses for children can be lengthened non-invasively with an external magnetic coil, or via a small surgical lengthening. Studies show mean lengthening of 31.6 mm across sessions with an 84% limb salvage rate.

Modular vs custom 3D-printed prostheses

• Modular: pre-manufactured components assembled in theatre — standard sizes, shorter waiting time, lower cost, 10-year survival 58–70%.
• Custom 3D-printed: patient-specific titanium with porous surfaces for osseointegration — perfect anatomical fit, joint preservation, and manufactured in 2–3 weeks versus months for traditional custom implants.

Patient journey — Priya, 12, Delhi

Priya was diagnosed with osteosarcoma of her distal femur after a confirmatory open biopsy. After neoadjuvant chemotherapy she underwent tumour resection with 2 cm margins (frozen-section confirmed), a non-invasive magnetic expandable endoprosthesis, and a gastrocnemius muscle flap for biopsy-scar coverage. Rehabilitation began on day 2. Over three years her prosthesis was lengthened 8 times (4 mm per session) in the outpatient clinic. She achieved 110° knee flexion, returned to badminton, and at 5-year follow-up remains disease-free with equal leg lengths.

Complications and how we manage them

Early (0–6 months): infection 8–14%, wound healing problems 15–20% (higher with adjuvant radiotherapy), dislocation 4%.

Late (>6 months): aseptic loosening 5.6% in modern modular implants; expandable mechanism failure 10–15% in paediatric implants.

Acute infections (<3 weeks) are treated with debridement and implant retention (DAIR) with a 60–80% success rate. Chronic infections undergo two-stage revision with an antibiotic spacer. The 10-year cumulative amputation risk is just 11%.

How long do these implants last?

• 5-year implant survival: 70–80%
• 10-year implant survival: 58–66%
• Major revision risk at 10 years: 18%
• Expandable prosthesis 5-year survival: 75–85% before conversion to adult prosthesis at skeletal maturity

Functional outcomes

• MSTS scores average 84% (range 67–90%) for modern prostheses.
• Knee flexion typically 90–120°.
• Cemented implants allow full weight bearing within days.
• Distal femur reconstructions offer the best functional results; proximal tibia has slightly reduced strength due to patellar-tendon attachment.

Recovery roadmap

1. 0–2 weeks: ICU monitoring 24–48 h, multimodal analgesia, early mobilisation with physiotherapy.
2. 2–6 weeks: progressive weight bearing, range-of-motion exercises, adjuvant therapy if planned.
3. 6 weeks–6 months: strengthening, functional training, return to daily activities and sport clearance.
4. Expandable lengthening: 10–15 min outpatient procedure, no anaesthesia, every 6–12 months as needed.

Take-home summary

Tumour endoprosthesis reconstruction delivers excellent limb salvage with good function for adults and children. Modular designs achieve 70–80% survival at 5 years; expandable prostheses keep growing children equal-legged; and 3D-printed custom implants represent the next step in personalised reconstruction.