During limb salvage for a distal femoral osteosarcoma, a rotating hinge megaprosthesis is used. The most important consideration when planning this surgery in a skeletally immature child is:

• A Use of cemented fixation to avoid stress shielding
• B Avoidance of radiotherapy to the prosthesis site
• C Expected limb length inequality and the use of an expandable (growing) prosthesis ✓
• D Prophylactic contralateral epiphysiodesis

Explanation

In skeletally immature patients requiring distal femoral resection for osteosarcoma, the distal femoral physis contributes approximately 70% of femoral growth (9 mm/year). Resection of this physis without accommodation leads to progressive limb length discrepancy (LLD). Expandable (growing) prostheses with non-invasive magnetic lengthening mechanisms (e.g., STANMORE MPFL) allow staged lengthening to match contralateral limb growth, minimizing LLD. Cemented fixation is less durable in young patients due to high activity levels.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.