The term pseudarthrosis comes from the Greek (pseudos = false, arthros = joint). It refers to a false joint formation (bony malhealing) in which the affected bone does not grow back together stably after a fracture. According to studies, delayed fracture healing or pseudarthrosis occurs in 5 to 10 % of cases. (1) According to the current definition of ESTROT (European Society of Tissue Regeneration in Orthopedics and Traumatology), the orthopaedic surgeon makes the diagnosis of pseudarthrosis if, in his opinion, a fracture does not heal without further intervention. Contrary to previous definitions, the previous duration of treatment no longer plays a role here.(2) In order to make a correct diagnosis in these cases, the orthopaedic surgeon must have a high level of knowledge and experience in this field. In addition to the medical history and a detailed physical examination, x-rays are necessary to recognise the lack of continuity of the bone. In some cases, especially if the X-ray findings are unclear, a computerised tomography (CT) scan or magnetic resonance imaging (MRI) may also be necessary.

Orthopaedic surgeons differentiate between atrophic and hypertrophic forms of pseudarthrosis. In atrophic pseudarthrosis, the bone is no longer sufficiently supplied with blood, which means that no new bone tissue (callus) can form at the fracture site and the fracture gap cannot close. Hypertrophic pseudarthrosis - the more common form - is characterised by the formation of too much bone or cartilage tissue around the fracture site, which prevents healing. For the sake of completeness, congenital pseudarthrosis should also be mentioned, although this is very rare.

In principle, all bone fractures, regardless of whether they are treated conservatively (by immobilisation) or surgically (osteosynthesis, insertion of intramedullary nails or stable-angle plates), can lead to complications in the form of delayed fracture healing or false joint formation (pseudoarthrosis). However, certain bones are affected more frequently than others. These include, for example, the long tubular bones in the thigh (femur), shinbone (tibia) or upper arm (humerus) as well as a carpal bone, the scaphoid bone (scaphoid) and the fracture of the base of the 5th metatarsal bone (Jones fracture).

A special case is the fracture of the scaphoid bone (scaphoid fracture). The carpal bone lies in the direct neighbourhood of the radius. A scaphoid fracture is often not treated, as patients do not even consult a doctor due to the generally moderate symptoms. However, an untreated scaphoid fracture harbours a high risk of pseudarthrosis formation, which can lead to permanent discomfort, serious limitations and arthrosis in the wrist.

Pseudarthrosis does not develop suddenly, but is subject to a gradual process. Redness and swelling over the fractured area are typical. As the stability of the bone is severely reduced in some cases, this often leads to malalignment, restricted movement, joint problems and muscle atrophy in the affected body part or limb, the function of which is then often severely restricted. Most patients are particularly distressed by the severe pain, which initially only occurs during movement, but can also occur at rest in advanced stages. Without therapy, this pain does not diminish but, on the contrary, becomes increasingly severe and therefore chronic.

Pseudarthrosis is a long-term condition that does not heal on its own and therefore requires treatment. Surgery is still the standard treatment. This is a procedure that is often more extensive than the first operation, in which a partial resection of the affected bone is performed and bone tissue is usually transplanted from the iliac crest into the fracture gap or foreign bone or bone replacement material is used. The surgical site must then be immobilised with an external fixator or stable-angle plates. This means that numerous and not insignificant complications are possible with this procedure. In addition to bleeding, secondary bleeding and haematoma, infections, wound healing disorders, scarring and chronic post-operative pain can occur. Nerve injuries can result in sensory disturbances or paralysis. In some cases, reduced mobility or joint stiffness may occur. Sudeck's syndrome (CRPS) cannot be ruled out either. In this case, the bone is severely degraded, resulting in painful inflammation. All of these are risks of complications, which of course do not necessarily occur, but only in some cases. However, the patient is always subjected to considerable stress during the procedure. In addition, the entire post-operative follow-up treatment virtually starts all over again. This is sometimes associated with long periods of rehabilitation and absence from work.