And it was a complicated procedure. Alan's fibula - the smaller of the two leg bones - was carefully removed, along with its blood vessels and supporting muscles, and reconnected the length of his breastbone and up his neck to support his head and neck.
Mr Hodgson describes the result simply: ''The bone acts like a great big strut. Imagine Alan's head is like the veranda on a house. If you don't have bracing to keep the veranda up, it will fall down.''
The procedure was developed overseas some years ago. A surgeon discovered that at about 22cm long, an adult's fibula was just long enough to fit from the third spinal vertebrae, just below the top of the spine, to the ninth vertebrae at the bottom of the breastbone.
''Fortunately, God designed the fibula to be just the right size to fit. He's obviously very clever,'' Mr Hogdson, a specialist spinal surgeon and head of the South Island scoliosis (spinal curvature) unit, said.
Removing the fibula does not create any mobility issues for the patient, as the larger and strong tibia bone takes over the leg work. The procedure is rare in this country. Alan's is just the seventh Mr Hodgson has carried out in his 25-year career. He says it is also rare to perform the procedure on people with Alan's condition - neurofibramatosis type 1 - which causes nerve tissue to grow tumours anywhere in and on the sufferer's body.
But for Alan, who he says has a particularly severe form of the condition, there was no choice.
A large lesion was slowly causing his neck to dislocate, his spinal cord to become kinked, and his body to become paralysed.
The operation involved four surgeons - Mr Hodgson and fellow orthopaedic surgeon Simon McMahon, and ear nose and throat surgeons Matthew Leaper and Jeff Robinson - as well as a team of anaesthetists and nurses and several trainee surgeons who were observing.
After a ''big breakfast'', the day was broken up into two- to three-hour surgery sessions with ''coffee and a donut'' in between, Mr Hodgson recalls.
Neurofibramatosis affects about 0.5% of the population. Alan is one of about a dozen New Zealand sufferers Mr Hodgson has treated over his career.
He says he is grateful to Alan and his parents for allowing surgeons in this country and around the world to learn more about his condition and the fibula graft.
An academic article about the procedure was published in an international surgical journal, and Alan has travelled to Dunedin to be interviewed by Otago Medical School students and trainee surgeons.
Alan has recovered well from the procedure and the strut is doing its job, Mr Hodgson says.
''I'm happy. His neck and spine X-rays look good.''
He put much of that down to Alan's attitude.
''He got a glint in his eye - a positive demeanour about him. He's a hard worker and he wants to get on. That's the strength of his whole family really.''
