- See:
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Blood Supply
-
Humeral Fracture Non Union:
-
Tibial Non Unions:
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Femoral Shaft Non Union
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Bone Healing:
- Discussion:
- frx of shaft of long bone should not be considered nonunion until at least 6 months post injury, esp treatment was complicated by infection;
- in contrast, a central fracture of the femoral neck can sometimes be defined as a non union after only 3 months;
- in established non union, sclerosis develops around the bone ends and medullary canals are sealed off;
- bone ends are joined by fibrous tissue;
- final stage of a nonunited fracture is formation of pseudoarthrosis (see
pseudoarthrosis of tibia);
- risk factors:
- NSAIDS;
- smoking
- infection
- radiographic findings supporting non union:
- absence of bone crossing the fracture site (bridging
trabeculae)
- sclerotic fracture edges
- persistent fracture lines
- lack of evidence of progressive change toward union on serial xray
- lack of callus (most unreliable finding)
- callus formation is expected in IM nail
- callus formation is not expected with plate fixation;
- Hypervascular or Hypertrophic: (horse hoof)
- hypertrophic non unions are rich in callus and have a rich blood supply in the ends of the fragments;
- they result from insecure fixation (inadequate stability) or premature wt bearing in a reduced fracture whose fragments are viable;
- fracture is capable of mounting a healing response
to injury
- hypertrophic nonunion
displays exuberant callus on radiographs
- there is increased uptake on radionuclide scans;
-
management:
- may have high incidence of union after rigid ORIF compression
plates or medullary nails, and cancellous bone grafts are optional;
-
handling of the non union site:
- note that fibrous scar tissue connecting the
bone ends of a hypertrophic nonunion has the capacity to turn
into bone;
- if angulatory deformity is not present, these nonunions do not have to be opened and debrided (w/ angulatory deformity open debridement
of the frx may be necessary because of stiffness and resistance to correction);
- hence debriding the nonunion
to excise the fibrous tissue between the bone ends is not required;
- opening the medullary canal proximally
and distally may promote healing w/o taking down a firm fibrous union;
-
plate fixation:
- providing adequate fracture stability may
be all that is necessary to induce fracture stability
- in many cases, however, the medullary canal of the non union site will not allow nail passage and therefore reaming is required;
- if reaming is to be performed, then consider opening frx site and reaming under direct vision since it is possible that blind reaming will result
in eccentric reaming and cortical perforation;
- Oligotrophic non unions:
- these are not hypertrophic, and callus is absent;
- they typically occur after major displacement of frx, distraction of fragments, or internal fixation w/o accurate apposition of fragments;
- has an intact blood supply
-
demonstrates radiotracer uptake on radionuclide scans
- has inadequate healing response
- Avascular or Atrophic:
- ends of the fragments have become osteoporotic and atrophic;
- the non union is inert and incapable of biologic reaction;
- will have cold bone scan;
- there is poor blood supply to the ends of the fragments;
- these are typically seen in tibial frx treated by plate & screws;
- these are usually final result when intermediate fragments are missing & scar tissue that lacks osteogenic potential is left in their place;
- radiographs may show eburnated, osteopenic, and/or sclerotic bone ends
-
management:
- open decortication must be carried out, and cancellous bone grafts should be added;
- ref:
Human atrophic fracture non-unions are not avascular.
- Comminuted Nonunions:
- these are characterized by the presence of one or more intermediate fragments that are necrotic;
- typically these nonunions result in the breakage of any plate used in stabilizing the acute fracture;
- Defect non unions;
- these are characterized by the loss of a fragment of the diaphysis of a bone;
- the ends of the fragments are viable, but union across the defect is impossible;
- as time passes the ends of the fragments become atrophic;
- these non unions occur after open fractures,
sequestration in osteomyelitis, and resection of tumors;
- BMPs:
- references:
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Application of recombinant BMP-7 on persistent upper and lower limb non-unions.
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Application of rhBMP-7 and platelet-rich plasma in the treatment of long bone non-unions A prospective randomised clinical study on 120 patients.
Vascularized fibular grafts in the treatment of osteomyelitis and infected nonunion.
Distraction osteogenesis in the treatment of stiff hypertrophic nonunions using the Ilizarov apparatus.
Mechanical and biological treatment of long bone non-unions.
Classification of non-union.
Metabolic and Endocrine Abnormalities in Patients With Nonunions.
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