Orthonotes
by the.bonestories
Menu
Viable (hypertrophic/oligotrophic) vs non‑viable (atrophic, necrotic, defect, comminuted). Radiographic callus indicates biology; absence suggests poor biology. Guides treatment: stability alone for viable; add graft/biologics for non‑viable. viable → improve stability; nonviable → improve stability + add biology.
10 AI-generated high-yield questions by our AI engine
Nonunion is defined as the failure of a fracture to unite within the expected timeframe for that fracture, with radiological and clinical evidence that further healing will not occur without intervention. While delayed union implies that healing is proceeding but more slowly than expected, nonunion indicates that the biological healing process has ceased. The distinction is not merely academic — the underlying biology of the nonunion determines the appropriate treatment. The Weber and Cech classification remains the most clinically useful system because it directly classifies nonunions by their biological activity, guiding whether mechanical stabilisation alone, biological stimulation, or both are required.
The Weber and Cech classification (1976) divides nonunions into two major groups based on their biological viability — the presence or absence of vascularity and biological activity at the fracture ends. This directly determines the treatment strategy.
| Type | Subtype | Biology | X-Ray Appearance | Cause | Treatment Principle |
|---|---|---|---|---|---|
| Viable (Vascular) — `Reactive` | Hypertrophic (`Elephant foot`) | Excellent vascularity; active osteoblasts; abundant callus; the biology is adequate — the problem is mechanical instability preventing callus maturation | Abundant exuberant callus at both fracture ends (`elephant foot` shape); callus is large and bulbous; fracture line still visible through the callus | Inadequate mechanical stability (e.g., cast that has cracked, nails that have dynamised too early, intramedullary nail that is too thin or unlocked too early) | Stabilisation alone is sufficient — the biological environment is excellent; rigid internal fixation (exchange nailing, compression plating) will lead to union without bone grafting; the callus will mature once stability is provided |
| Moderately hypertrophic (`Horse hoof`) | Good vascularity; moderate callus; adequate biology but slightly less active than elephant foot | Moderate callus with a `horse-hoof` pattern; smaller callus than elephant foot | Moderate instability; partially effective fixation | Stabilisation ± bone graft; if biology is borderline, addition of autograft or bone graft substitute is prudent | |
| Oligotrophic | Some vascularity; minimal callus; the fracture ends are viable but not actively forming callus; the biology is present but not stimulated (often because the fragments are distracted or not in contact) | Very little or no visible callus; fracture ends are visible but not sclerotic; gap between the ends; fragments are not in contact | Fragment distraction; fibrous interposition; inadequate reduction (gap too large for callus to bridge) | Stabilisation + reduction to bring fragments into contact + bone graft; the lack of contact between viable ends explains the minimal callus; once contact is restored and stability provided, bone graft stimulates union | |
| Non-viable (Avascular) — `Areactive` | Torsion wedge | Intermediate fragment (torsion or butterfly fragment) is avascular; has lost its blood supply; the main fragments are viable but the intermediate fragment is dead | An intermediate fragment with no callus; the main fragments may have some callus but the dead intermediate fragment does not | Comminuted fracture with displacement; the intermediate fragment`s periosteal blood supply is stripped | Stabilisation + bone graft (to replace or revascularise the avascular fragment); the dead fragment may need to be excised and replaced with graft, or the nonunion compressed across it |
| Comminuted | Multiple devascularised fragments; none of the fragments have adequate blood supply; the fracture zone is a biologically dead field | Multiple fragments with no callus; sclerotic, avascular-appearing fragments; no biological activity visible | High-energy comminuted fracture; extensive periosteal stripping; open fracture | Stabilisation + aggressive bone grafting (iliac crest autograft is the gold standard); the avascular zone must be debrided to bleeding bone and packed with autograft; or Masquelet technique (induced membrane) for large avascular segments | |
| Defect / Atrophic | True bone defect — one or both fracture ends have undergone resorption; the bone ends are `pencil-shaped`, tapered, and avascular; no callus; no biological activity; this is the worst biological scenario | `Pencil-point` or `cigar-end` tapering of the fracture ends; no callus; sclerotic bone; gap between the ends (defect); the medullary canal is sealed at the atrophic end | Long-standing nonunion; repeated failed surgeries; infection; poor vascularity; systemic factors (smoking, diabetes) | Most demanding treatment: stabilisation + aggressive debridement of atrophic ends to bleeding bone + large volume bone graft (iliac crest autograft, bone transport via Ilizarov/Taylor Spatial Frame, Masquelet induced membrane technique for defects >2 cm); both stability AND biology must be restored from scratch |
10 AI-generated high-yield questions by our AI engine