Martin Kramer

Correlation of histology of healed fractures and tissue surrounding implants with ultrasonographic and radiographic appearance

OBJECTIVESnTo determine if there was histological correlation with ultrasonographic images of healed fractures and implant-associated tissue after fracture treatment by plate osteotomy.nnnMETHODSnEight adult dogs were included in this retrospective study. Ultrasonography (B-mode and power Doppler) and radiography were performed before plate removal. Surgical biopsies were taken of the fracture site and the tissue adjacent to the plate. These were stained with haematoxylin and eosin to assess histomorphology and bone content and immunolabelled with CD31 to assess vascularity.nnnRESULTSnUltrasound and radiographic diagnoses of a healed fracture correlated with histological finding of bone healing. Ultrasonography and histology findings of vascularity were also highly correlated. The tissue surrounding the surgical implants was significantly more vascularised on both ultrasonography and histology than that at the fracture site itself.nnnCLINICAL RELEVANCEnUltrasonography can be used to diagnose fracture healing in plated fractures. Power Doppler ultrasonography examination of fracture healing should be performed away from surgical implants to avoid false-positive results of vascularisation.

Evaluation of nonunion fractures in dogs by use of B-mode ultrasonography, power Doppler ultrasonography, radiography, and histologic examination

OBJECTIVEnTo investigate the use of ultrasonography to assess nonunion of fractures in dogs and to compare results of ultrasonography, radiography, and histologic examination.nnnSAMPLE POPULATIONn8 nonunion fractures in 6 dogs (1 each in 5 dogs and 3 in 1 dog); dogs ranged from 7 to 94 months of age and weighed 6 to 30 kg.nnnPROCEDURESnDiagnostic assessment consisted of complete clinical and orthopedic examinations, radiography, B-mode (brightness mode) ultrasonography, and power Doppler ultrasonography. Biopsy samples were obtained during surgery for histologic examination. They were stained with H&E and immunolabeled by use of anti-CD31 antibodies. Correlations of power Doppler score, power Doppler count, vessel area, and radiographic prediction with the mean number of vessels counted per hpf were derived.nnnRESULTSnRadiographically, 7 of 8 nonunion fractures were diagnosed as atrophic and were therefore estimated to be nonviable. Vascularity of nonunion fractures during power Doppler ultrasonography ranged from nonvascularized to highly vascularized. Absolute vessel count during histologic examination ranged from 0 to 63 vessels/hpf; 5 nonunion sites had a mean count of > 10 vessels/hpf. Vascularity during power Doppler ultrasonography was highly correlated with the number of vessels per hpf, whereas the correlation between the radiographic assessment and histologic evaluation was low.nnnCONCLUSIONS AND CLINICAL RELEVANCEnRadiographic prediction of the viability of nonunion fractures underestimated the histologically assessed vascularity of the tissue. Power Doppler ultrasonography provided a more accurate estimation of the viability of the tissue and therefore the necessity for debridement and autografts during revision surgery.