Aims

The main advantage of 3D-printed, off-the-shelf acetabular implants is the potential to promote enhanced bony fixation due to their controllable porous structure. In this study we investigated the extent of osseointegration in retrieved 3D-printed acetabular implants.

Medical records of children < /=5 years, treated by the London sarcoma service for malignant primary bone tumours (average new cases osteosarcoma (OS)/Ewings sarcoma (ES), all ages: 125/year) between 1999 and 2009, were reviewed.

Results: 5 OS and 6 ES. Mean age – 4.2 years (range 2.1–5.8), 8/11 males. OS primary sites: distal femur (2), proximal femur (1) and proximal humerus (2); localised tumours only. Primary sites in the ES cohort included 1 distal femur, 2 chest wall (1 – spinal extension), 1 buttock (spinal extension), 1 temporal bone and 1 ulna; 1 had bone/bone marrow involvement, 1 had chest metastases. 4/5 OS (Euramos, MRC B007) and 5/6 ES (Euro-Ewings 99) were entered into phase III clinical trials. Delayed surgery for OS occurred at mean 12.1 weeks (range 11–13) – 4 limb salvage prostheses with 2/4 non-invasive growers, 1 forequarter amputation. All had a good (> 90% necrosis) histologic response to neoadjuvant therapy. Delayed surgery for ES occurred at mean 21.7 weeks (range 12.8 – 35), 1 limb salvage with prosthesis (non-invasive grower), 1 biological reconstruction; remainder had tumour resections. Histologic response: 50% good. In the OS cohort, 1 child died a toxic death; 1 developed pulmonary metastases and died 2 years from diagnosis; 1 has a metastatic recurrence in the opposite humerus 2 years from diagnosis and starts 2nd line therapy; 1 had local recurrence 1 year from diagnosis but alive at 7.4 years;1 alive/disease free at 2.5 years. In the ES cohort 5/6 are alive disease free -1, 4.1, 5.2, 6.9 and 7 years from diagnosis; 2 needed 2nd line therapy for recurrent distant disease 4.5 and 5.8 years off therapy, 1 of whom has just recurred again (6.1 years from diagnosis).

Conclusion- improving early survival rates in the very young with OS remains a significant challenge. Quality of survival requires further age-appropriate study.