Scientists have discovered a new and extremely destructive hereditary joint disorder in a US family.
Bones stopped from running together by cartilage
The disorder is marked by the bubbling and peeling away from the bone of protective cartilage tissue.
It was discovered in a 49-year-old man who had suffered from joint pain which failed to respond to treatment for most of his life.
US researchers, writing in Arthritis and Rheumatism, say their work may aid research into joint degeneration.
The researchers, from Case Western Reserve University and the University of California, San Diego, say the new condition is far more severe than most cases of osteoarthritis - another condition that results from damage to the cartilage.
The man at the centre of the study began to develop problems at the age of three.
Doctors concluded that he had abnormal bone structure and tried to treat him by immobilising both his legs.
At the age of 10, he began to complain of knee and hip pain. By age 13, he had lost significant hip mobility and his left leg was shorter than his right.
At age 16, he underwent a surgery to separate the hip and insert a plate.
Eventually, in his 40s, he had his hip replaced completely.
Over the years, he was misdiagnosed with various disorders, including Osgood-Schlatter disease, Legg-Calvé-Perthes disease, and spondylo-epiphyseal dysplasia.
But the researchers say what made his case compelling was the fact that his three children - two daughters and a son - all suffered similar symptoms.
All three children have had multiple surgical procedures on the knees, hips, and shoulders, and both daughters have had total hip replacement surgery.
The researchers examined blood samples from affected and unaffected family members.
They isolated the same two tiny genetic mutations in all four affected people.
But this proved inconclusive as the same mutations were also found in three unaffected family members.
Further research revealed that all four affected family members had signs of excessive fluid and large amounts of loose material in their tissues.
But the most interesting observation was that in each of the affected individuals the cartilage was prone to bubbling and peeling off in layers to expose bone at a very early age.
This damage occurred at a very fast rate, leaving bones completely unprotected and joints exceptionally vulnerable to shattering.
This is different to more standard forms of osteoarthritis in which the cartilage gradually erodes as a result of long-term inflammation of the joint, leading to increased stress on the bone and joint damage.
Researcher Professor Roland Moskowitz said: "The findings may have broader ramifications if a protein or enzyme related to the mutation can now be defined, allowing us to better understand normal cartilage-bone interplays.
"With this understanding, we can then address "run-of-the -mill" osteoarthritis to see if these proteins/enzymes play a role in others with the more common disorder."
Dr Michael Briggs, of the University of Manchester, told the BBC News website the features of the disease bore similarities to a group of genetic bone diseases known as the chondrodysplasias.
"Further research needs to be undertaken to determine if this bone disease is unique to the one family, or if it is part of the clinical spectrum of chondrodysplasia."