Following his discharge from hospital, the boy received further injuries and was found dead.
A report released by Health and Disability Commissioner Anthony Hill today found a DHB, which was not named, failed to provide adequate care for the boy and recommended the organisation provide the family with a letter of apology.
When the 16-month-old began to avoid using his left leg, his mother took him to hospital for treatment.
X-rays failed to pick up any issues and it was not until the mother took her son in for the third time that an MRI was organised.
Two weeks after the first visit the MRI and a bone scan confirmed he had a spiral fracture in his tibia.
A paediatric consultant told Hill he considered the injury could have been non-accidental on the boy's second visit but did not document it.
On the third visit, the boy and his mother went home before the on-call paediatric consultant could do a child protection assessment.
It was not until the pair came to the hospital again about 10 days later that a student nurse noted a missing tooth, two black fingernails and a missing fingernail and faded bruising on his forehead and cheek.
The student told a registered nurse immediately. The boy's mum told staff the tooth injury had occurred at kindergarten and his fingers had been jammed in a door.
It was not until he was transferred to another hospital for a bone scan that it was noted the boy's father was in prison for domestic violence and his mother's new partner was on home detention for assault.
Because of the number of unexplained injuries, the boy was referred to Oranga Tamariki and the police child protection team.
Oranga Tamariki were asked to prepare a safety plan before the boy could be discharged but he went home after police arrived and spoke to his mother.
He was later found dead with further injuries.
Hill said he was "very concerned that it took multiple presentations to hospital, and a transfer to [another] hospital, before the diagnosis of non-accidental injury was explicitly considered and noted in the clinical notes".
Three doctors admitted non-accidental injury was considered but it was not documented or escalated, Hill said.
He said the boy's care demonstrated the challenges clinicians face when diagnosing non-accidental injuries.
Hill found that the DHB's systems did not encompass an adequate safeguard for the boy, and that the evidence overwhelmingly demonstrated a systemic failing on the part of the DHB.
"In my view, the system that was meant to wrap around this boy had the information it needed to diagnose his fracture and non-accidental injuries earlier. However, a series of failings in assessment, communication, documentation, and co-ordination of care, and a failure to adhere to policies and procedures prevented this from occurring," he said.
Children's Commissioner Andrew Becroft said, based on his current understanding of the report which he would be reviewing more carefully, it was a "profoundly concerning incident that experts in our office call dreadful and appalling".
"Based on the report there seems to be a wholesale failure by a series of medical professionals," he told the Herald.
"There seems to have been at least five medical opportunities to identify possible non-accidental issues."
He noted at least three medical professionals had considered the possibility but not recorded it.
It was disappointing that all the work done creating and implementing family violence intervention programmes could not do anything to help this child, he said.
"This is as bad a systems failures could possibly be imagined.
"I would expect much better from each DHB in future."
Becroft said he was hopeful it was an isolated incident and would serve to remind medical professionals of the importance of the systems and protocols in place.
"We'd want to be reassured that each DHB has a very effective family violence plan that's being adhered to. It emphasises a need for absolute vigilance."
Hill recommended that the DHB provide a letter of apology to the boy's family.
He also recommended a series of audits to identify failings in systems around family violence screening and paediatric skeletal surveys and report back on what improvements could be made.
Finally, he recommended the DHB follow up with a multi-agency meeting with Oranga Tamariki and the New Zealand Police to discuss the findings from the DHB's serious adverse event report and the Commissioner's report.