Evaluation of surface blood flow in intact and ruptured canine cruciate ligaments using laser Doppler flowmetry.

OBJECTIVE: To evaluate the usefulness of laser Doppler flowmetry (LDF) to measure surface blood flow in canine cruciate ligaments, compare measurements in different sites of intact and partially ruptured canine cranial cruciate ligaments (CrCL) and intact caudal cruciate ligaments (CaCL), and investigate any association between surface blood flow in partially ruptured CrCL and synovitis or duration of clinical signs.

STUDY DESIGN: Case-controlled clinical study.

ANIMALS: Sixteen dogs with partially ruptured CrCL and five dogs with intact CrCL.

METHODS: Blood cell flux (BCF) readings during three measurement cycles using LDF at two sites in each ligament (mid-substance and the distal portion of the CrCL, and mid-substance and the proximal portion of the CaCL) were recorded. Synovial changes were graded grossly and histologically using the Osteoarthritis Research Society International histopathology scoring system.

RESULTS: The within-run coefficients of variation (CV) for a single BCF measurement cycle were 12.2% and 12.7% in the ruptured and intact CrCL groups, respectively. The between-run CV for three measurement cycles was 20.8% and 14.8%, respectively. The intraclass correlation coefficient (ICC, absolute agreement) was 0.66 for a single measurement cycle and 0.86 for the average of three cycles. No difference in average BCF readings was found between any two sites in either group, but BCF readings in both CrCL sites were significantly higher in the ruptured CrCL group than the intact CrCL group. No associations between BCF and synovial grades or duration of lameness were identified.

CONCLUSIONS: Laser Doppler flowmetry can be used to assess surface blood flow in intact and partially ruptured canine cruciate ligaments with acceptable precision. Using this method, surface blood flow appears greater in partially ruptured canine CrCL than intact CrCL. Further studies are required to determine if this is a sequela of trauma or synovitis.