How does bone grow together and why does the process stop?
For fracture healing, four conditions are needed: viable fragments with a blood supply, close contact between them, sufficient stability and time. If at least one is broken, instead of callus, cartilage or scar tissue is formed between the fragments, the ends of the bone are smoothed out and covered with a semblance of an articular surface. Further, the process is consolidated: mobility interferes with the germination of blood vessels, and without blood vessels, new bone does not form. The body can no longer break this circle on its own, so wait-and-see tactics do not work when a false joint has formed.
- Hypertrophic pseudarthrosis - there is blood supply, but lack of stability
- Atrophic pseudarthrosis - the ends of the fragments are thinned, the blood supply is poor
- Infected pseudarthrosis - chronic infection prevents fusion
- Delayed fusion - the process is progressing, but slower than expected
- Cartilage and a scar are formed between the fragments instead of a callus.
Causes and risk factors
Mechanical causes are associated with insufficient or, conversely, too rigid fixation, early loading, large distances between fragments, and loss of bone mass during a comminuted fracture. Biological causes include damage to blood vessels and soft tissues due to trauma, open fracture, infection, as well as general factors that reduce the ability of the bone to recover. Smoking is especially significant: it impairs the blood supply to the fracture zone and significantly increases the risk of nonunion. Some bones heal less well than others due to their blood supply.
- Unstable fixation and early axial loading
- Open and comminuted fractures
- Damage to soft tissues and blood vessels
- Infection at the fracture site
- Smoking, diabetes, obesity
- Vitamin D and protein deficiency, glucocorticoid intake
- Areas with poor blood supply: scaphoid, femoral neck, lower third of the leg
Symptoms
The main symptom is pain in the area of the former fracture under load, which does not decrease with time, and sometimes intensifies. A feeling of instability appears: the limb “fails”, and when supported there is a feeling of springy movement. With a pronounced pseudarthrosis, pathological mobility is visible or palpable where it should not be. Possible swelling, deformation and shortening of the limb, limited movement in adjacent joints due to prolonged sparing and decreased muscle mass.
- Pain on exertion months after injury
- Pathological mobility at the fracture site
- Feeling of limb instability
- Deformation and shortening
- Swelling and tenderness on palpation
- Muscle weakness and atrophy
Diagnostics
The basis is radiographs in two projections, always in comparison with previous images: the doctor looks to see if there is dynamics of the callus, what is the gap between the fragments, and whether the metal structure has shifted. Computed tomography more accurately shows whether there is at least partial bone fusion and is needed to plan the operation. If there is a suspicion of infection, blood tests are prescribed for inflammation and, if necessary, culture of material from the lesion. General factors must be assessed: the level of vitamin D, calcium, diabetes, smoking.
- X-ray in two projections in dynamics
- CT scan of limb bones to assess fusion
- Complete blood count and C-reactive protein
- Culture of material for suspected infection
- Vitamin D, calcium, phosphorus, alkaline phosphatase
- Assessment of comorbidities
Treatment
Tactics depend on the type of pseudarthrosis. In hypertrophic osteosynthesis, the main thing is to ensure stability: osteosynthesis is performed with a plate or an intraosseous rod, and sometimes an external fixation device is used. In case of atrophy, biological stimulation is additionally needed: removal of scar tissue, refreshment of the ends of fragments, bone grafting with one’s own or donor bone. An infected pseudarthrosis is treated in stages: first, the lesion is sanitized and the infection is suppressed, then the bone is restored. Be sure to eliminate common factors: quit smoking, compensate for diabetes and vitamin D deficiency. After surgery, gradual rehabilitation under the supervision of a doctor is necessary.
- Stable osteosynthesis with a plate or rod
- External fixation device for complex and infected forms
- Bone grafting for bone deficiency
- Staged treatment of infection
- Smoking cessation and metabolic correction
- Dosed exercise and physical therapy after surgery