Craniopagus twins — conjoined at the skull — represent one of the rarest and most surgically demanding conditions in medicine. The twins share not just a point of contact but, in most cases, venous drainage structures that cross between their brains. Blood from both children flows through a common venous system before returning to the heart. Separating them requires severing that shared system and reconstructing adequate venous drainage for each child independently — while both remain alive on the operating table. It had not previously been done successfully in India.
The twins were brought to a major public hospital in Delhi in July 2017, aged approximately two years. CT and MRI imaging confirmed that they were joined at the posterior skull and shared a circular sinus — the venous drainage channel connecting their cranial venous systems. The neurosurgical team assessed the anatomy in detail. The shared sinus could not simply be ligated; one twin required a surgically created venous bypass before separation could proceed. The procedure would need to be staged — and each stage would last many hours.
Before the first incision, the team requested 3D printed models of the twins' brain and skull anatomy from Osteo3d. The models were derived from the imaging data, rendering the conjoined cranial vault and the underlying neural structures in physical form. The team rehearsed the surgical approach on these models — working through the sequence of steps, identifying the anatomical decision points, and confirming the spatial relationships that CT images alone could not fully convey. For a procedure with no precedent at this institution, the ability to practise on a physical representation of the specific anatomy in front of them was not a convenience. It was part of how the surgery became possible.
The first stage lasted approximately twenty-five hours. The neurosurgeons created a venous bypass for one twin, diverting venous drainage away from the shared circular sinus and establishing an independent route. Partial separation of the brain tissue was achieved. The twins were then allowed to recover before the definitive separation. The final stage took place on 25 October 2017 — a twenty-hour procedure during which the remaining shared structures were divided and the cranial reconstruction was completed for each child.
Both twins survived the separation. One child made a strong neurological recovery. She was assessed as developing well across domains of neuropsychological evaluation and was considered ready for school before discharge. Her twin sustained neurological injury from which full recovery did not occur, and required ongoing feeding and care support. Both children were discharged more than two years after admission.
This case became the first successful craniopagus separation in India in which both twins survived the procedure. It was the result of meticulous preparation across imaging, surgical planning, anaesthesia, and nursing — a team effort sustained across a period of months. The 3D printed models were one element of that preparation: a way of translating imaging data into a physical object the surgical team could hold, examine, and rehearse on before the clock started. In a procedure measured in hours and milligrams of venous pressure, that preparation was part of how the outcome became what it was.
Osteo3d Team
Clinical Affairs