Laboratory Tests (in Noninfected Nonunions) Physical Examination History Diagnosis

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The differential diagnosis of a fracture that does not show signs of healing includes delayed union, nonunion, synovial pseudoarthrosis, infection, and unrecognized pathological fracture [1]. History, physical examination, labo- ratory tests, imaging studies, and bone biopsy can give important information about this.

History

A detailed history of the patient with a diaphyseal fracture nonunion must be taken, including: patient nutritional status, systemic diseases, weight, and fracture history (including bone involved, damage to soft tissues, mechanism of fracture, type and duration of treatment, physiologic loading, pain, motion at the fracture site, soft tissue swelling, neurovascular limb compromise, and presence of infection).

Physical Examination

Physical examination contributes information about tenderness, instability (motion, crepitus), pain, functional loss, and possible signs of infection such as swelling, warmth, drainage, and erythema (Fig. 1).

Laboratory Tests (in Noninfected Nonunions)

Laboratory tests including determination of serum albumin levels, total lym-

phocyte count, and electrolyte values can give indications of nutritional defi-

ciencies. The Westergren erythrocyte sedimentation rate can remain elevat-

ed for several months after a fracture.

Imaging Studies (in Noninfected Nonunions)

X-Ray Studies

Four radiographic views (anteroposterior, lateral, and both oblique) are needed to assess long bone nonunion. Furthermore, stress view roentgenograms (obtained during application of varus-valgus or anterior-posterior force to the limb) and flu- oroscopic examination are often employed to demonstrate micromovements at the fracture site (Fig. 2).

Fig. 1. Clinical feature of a tibial nonunion with deformity and instability at the non- union site

Fig. 2a, b. Anteroposterior (a) and lateral (b) x-rays of a tibial hypertrophic nonunion

a b

Osteomedulloangiography

Osteomedulloangiography is employed to evaluate whether the medullary circulation at the site of a fracture has been reestablished. Contrast medium is injected, by intraosseous phlebography, into the medullay canal distal to the fracture site and a fluoroscopic examination shows whether it flows across the fracture. If intraosseous veins do not cross the fracture, delayed union or nonunion is very likely [1, 4].

Nuclear Medicine

In cases of noninfected nonunions, technetium methylene diphosphonate scintigraphy has been used to detect the presence of synovial pseudoarthro- sis with a high sensitivity: in these cases a cold cleft between two areas of high uptake is generally seen [1]. Furthermore, scintigraphy has gained increased importance in the “functional diagnosis” of nonunion.

Due to the relationship that exists between local bone metabolism (osteogenic activity) and deposition and remodeling of bone tissue [5], scintig- raphy is employed to assess nonunion biological activity.

Finally, scintigraphy is a particularly useful technique to distinguish between biologically active and nonresponsive nonunions because this dis- tinction is often clinically and radiographically difficult (Fig. 3).

Fig. 3a, b. a X-ray of a forearm non- union where the biological activity at the nonunion site is difficult to assess. b TC

scintigraphy is very useful to show biological activity

a

b

Computed Tomography

In particular cases CT scans can find fracture lines where standard radiogram cannot show persistence of fracture signs, for instance in oblique or spiroid fractures [6].

At the same time this kind of investigation can show the persistence of a frac- ture line in cases of hypertrophic nonunion with callus abundance (Fig. 4).

Fig. 4a, b. Combination of x-ray and CT scan of a distal tibial nonunion shows persistence of fracture signs

a

b

Magnetic Resonance Imaging

In noninfected nonunion, MRI can accurately visualize the vascular supply of the long bones, thus providing an indication of bone end viability and con- tributing to making a correct treatment choice [6].

In certain instances, MRI can be enhanced by the injection of an intra- venous contrast agent, such as gadolinium (Gd).

Bone Biopsy

A closed or open bone biopsy is sometimes indicated for differential diagno- sis of infected or noninfected nonunions, neoplasm, and systemic diseases.

Noninfected hypertrophic nonunions show a rich vascular plexus invad- ing the external callus. Into the fracture gap fibrous or fibrocartilaginous tis- sue with void capillaries is seen (Fig. 5).

In noninfected atrophic nonunions, fibrous tissue within the fracture is disorganized, and some areas of fibrocartilage are seen (Fig. 6).

Fig. 5. Histologic feature of a non- infected hypertrophic nonunion:

rare and void capillaries are seen into the fracture gap (Hema- toxylin and Eosin, original mag- nification: x 125)

Fig. 6. Microscopic feature of an

atrophic nonunion where fibrous

tissue with an area of cartilagi-

nous tissue can be obser ved

(Hematoxylin and Eosin, original

magnification: x 125)

Infected nonunions show signs of inflammation and trabecular resorption due to necrosis. If infection is suspected, multiple samples must be obtained, but it is often difficult to determine whether a nonunion is infected (Fig. 7). If microbiological investigations are negative or uncertain, histological analysis of specimens taken from the nonunion site are of particular use: a highly inflammatory infiltrate is strongly suggestive of infection [7].

References

1. Connolly JF (1991) Tibial non-union. Diagnosis and treatment. AAOS, Park Ridge (Illinois)

2. Hammer R, Edholm P, Lindholm B (1984) Stability of union after tibial shaft frac- ture: analysis by a non-invasive technique. J Bone Joint Surg Br 66:529–534 3. Carrata A, Rampini C, Failoni S (1988) Stato attuale della radiologia in tema di pseu-

doartrosi diafisaria. Apparato locomotore 2:43–49

4. Puranen J, Punto L (1981) Osteomedulloangiography: a method of estimating the consolidation prognosis of tibial shaft fractures. Clin Orthop Relat Res 161:8–14 5. Weber BG, Cech O (eds) (1976) Pseudoarthrosis. Huber, Berne

6. Weitzel PP, Esterhai JL (1994) Delayed union, non-union and synovial pseudoarth- rosis. In: Brighton CT, Friedlander GE, Lane JM (eds) Bone formation and repair.

AAOS, Rosemont (Illinois), pp 505–527

7. Simpson AH, Wood MK, Athanasou NA (2002) Histological assessment of the pre- sence or absence of infection in fracture non-union. Injury 33:151–155

Fig. 7. Microscopic feature of an in-

fected nonunion with sign of in-

flammation and trabecular bone

resorption (Hematoxylin and

Eosin, original magnification: x

125)