Quantitative monitoring of blood supply to knee joint transplants in dogs.
BACKGROUND
Transplantation of vascularized knee joints has become technically feasible, but graft rejection as well as failures of the vascular anastomoses remain critical hazards. We therefore tested the potential of repetitive non-invasive duplex sonography to detect changes of the arterial blood flow following canine knee joint transplantation.


METHODS
Four transplantations and, as controls, 4 replantations of intact canine knee joints were performed. The follow-up was 6 months. During this period, repetitive duplex sonography measurements as well as tests of knee joint function were performed. Six months postoperatively, angiographies were performed and all joints were explanted for histological investigation.


RESULTS
The luminal diameters of the implanted popliteal artery remained constant in the transplanted animals (preop. 2.6 +/- 0.2 mm, 6 months postop. 2.7 +/- 0.2 mm) but decreased in the autografted controls (preop. 2.9 +/- 0.3 mm, postop. 2.0 +/- 0.3 mm). The time-averaged velocity of the popliteal artery blood flow decreased in both groups 1 month postoperatively. Subsequently, blood flow velocity recovered in transplanted animals but remained low in replanted controls. Significant arterial wall thickening was also detected in transplanted animals as compared to controls. Six months postoperatively, hypervascularization of transplanted joints was confirmed by angiography and thickening of the arterial wall by histology. Furthermore, histology identified mild to chronic allograft rejection in all transplanted joints in spite of controlled cyclosporin A trough level immunosuppression.


CONCLUSIONS
Chronic rejection of transplanted vascularized knee joints appears to be associated with vessel wall thickening and hypervascularization rather than with vascular rarefaction (picture of the 'arbre mort') that is characteristic of the rejection of most parenchymatous organs. Duplex sonography appears to be sensitive in detecting the corresponding changes of blood supply.
Schäfer
D
D
Department of Orthopaedic Surgery, Kantonsspital Basel, Switzerland.
Jäger
K
K
Fricker
R
R
Schläpfer
R
R
Rosso
R
R
Heberer
M
M
D000792:Angiography; D000818:Animals; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods*; D001783:Blood Flow Velocity; D016572:Cyclosporine / Q000097:blood / Q000627:therapeutic use; D004285:Dogs; D006084:Graft Rejection / Q000000981:diagnostic imaging / Q000473:pathology; D007166:Immunosuppressive Agents / Q000097:blood / Q000627:therapeutic use; D007596:Joints / Q000637:transplantation*; D007719:Knee Joint / Q000098:blood supply* / Q000000981:diagnostic imaging*; D014184:Transplantation, Homologous; D018617:Ultrasonography, Doppler, Pulsed
D007166:Immunosuppressive Agents; D016572:Cyclosporine