Diagnosis of medial meniscal lesions in the canine stifle using multidetector computed tomographic positive-contrast arthrography.

OBJECTIVE: To assess diagnostic value and clinical utility of multidetector computed tomographic positive contrast arthrography (CTA) for meniscal lesions in dogs. STUDY DESIGN: Prospective case series. STUDY POPULATION: Client-owned dogs (n = 55) with cranial cruciate ligament injuries. METHODS: Sedated dogs underwent CTA using a 16-slice scanner, and subsequently received mini-medial arthrotomy for meniscal assessment. Scans were anonymized, randomized, and reviewed twice for meniscal lesions by three independent observers with varying experience. Results were compared with surgical findings. Reproducibility and repeatability were assessed with kappa statistics, intraobserver changes in diagnosis by McNemar's test, and interobserver differences using Cochran's Q test. Test performance was calculated using sensitivity, specificity, proportion correctly identified, and positive and negative predictive values and likelihood ratios. RESULTS: Analysis was based on 52 scans from 44 dogs. Sensitivity for identifying meniscal lesions was 0.62-1.00 and specificity was 0.70-0.96. Intraobserver agreement was 0.50-0.78, and interobserver agreement was 0.47-0.83. There was a significant change between readings one and two for the least experienced observers (p < .05). The sum of sensitivity and specificity exceeded 1.5 for both readings and all observers. CONCLUSION: Diagnostic performance was suitable for identifying meniscal lesions. An effect of experience and learning was seen in this study.

Objective and owner-reported outcomes after modified cranial closing wedge ostectomy: a case series.

Immediate and longer-term outcomes of a cranial closing wedge ostectomy variant for management of canine cranial cruciate ligament disease were assessed in this single-center retrospective consecutive study. Records and radiographs were retrieved and assessed by three independent observers to evaluate tibial plateau angle, anatomical-mechanical axis angle, tibial tuberosity distalization, and mechanical axis length before and after surgery. Kinetic gait analysis and owner questionnaires were used to assess clinical outcomes. Seventeen stifles from fifteen dogs were evaluated radiographically. Mean error from target tibial plateau angle was 0.4 degrees. Anatomical-mechanical axis angles reduced from mean 2.9 degrees preoperatively to mean - 0.9 degrees postoperatively. Tibial tuberosity distalization was mean 5.0% of mechanical axis length, and mean reduction in mechanical axis length was 0.1%. Increased tibial plateau angles were noted in 8/17 stifles, with a mean of 9.6 degrees at short-term follow-up. Major complications were observed in 9/17 stifles. Long term follow-up (mean 832 days) was obtained with gait analysis in 8/15 dogs and with questionnaire in 11/15. Most dogs (9/11) were weakly to moderately affected by osteoarthritis symptoms. All values for peak vertical force and vertical impulse normalized to body weight exceeded local lower reference limits for normal dogs, indicating acceptable limb use. Satisfactory immediate and long-term clinical outcomes appear to be possible with this technique, but the high incidence of shorter-term complications may caution against the technique or the fixation and management described here.

Effect of center of rotation of angulation-based leveling osteotomy on ex vivo stifle joint stability following cranial cruciate ligament transection and medial meniscal release with and without a hamstring load.

OBJECTIVE: To evaluate the effect of center of rotation of angulation (CORA)-based leveling osteotomy (CBLO) and hamstring load on stifle stability following cranial cruciate ligament transection (CCLx) and medial meniscal release (MMR). STUDY DESIGN: Ex vivo experimental study. SAMPLE POPULATION: Cadaver hind limb preparations (n = 7). METHODS: After instrumentation, constant quadriceps and gastrocnemius loads with an optional hamstring load in a 3:1:0.6 ratio were applied, and stifles were extended from fully flexed using an electrical motor during fluoroscopic recording. The recording process was repeated after each of CCLx, MMR and CBLO and the extracted landmark coordinates were used for calculation of cranial tibial translation (CTT) and patellar ligament angle (PTA). RESULTS: Mean initial tibial plateau angle was 28.1°: post-CBLO the mean was 9.7°. Cranial tibial translation developed from 50° and 75° with CCLx and MMR respectively (p < .04, < .02) without hamstring loading. Hamstring loading mitigated CTT due to CCLx and delayed CTT until 120° for MMR (P < .02) in this model. CBLO prevented CTT, except at 140° without hamstring loading (P = .01). Similar results were seen for PTA, but CBLO curves were parallel to and lower than intact values at all tested angles (P < .04), consistent with induced effective joint flexion. CONCLUSION: CBLO to a target tibial plateau angle of 10° largely eliminated CTT induced by CCLx and MMR. Hamstring loads of 20% quadriceps load improved stifle stability in this model. IMPACT: Stifle stability following CBLO appears to be multifactorial and depends on meniscal integrity, joint angle, and hamstring strength.

Quantifying the variability between multiple multiplanar reconstructions of computed tomography scans.

BACKGROUND: Multiplanar reconstructions of computed tomography (CT) scans can alleviate issues with bone or joint positioning during scan acquisition. The repeatability of these reconstructions is dependent on human operators applying reconstruction criteria, and therefore is subject to error, which could affect measurement reliability for angular or spatial measurements made for orthopaedic surgery. We describe a method for quantifying inter-reconstruction variability numerically and graphically using metadata from the CT header to find vectors describing reconstruction axis alignment. The approach is demonstrated using 3 sets of computed tomographic reconstructions of 24 vulpine femorotibial joints. RESULTS: Vectors describing axis alignments permitted identification and subsequent analysis of deviations from optimal alignment between reconstruction sets. For the worked example, alignment deviations equivalent to femoral abduction/adduction were nearly twice those for extension/flexion, and simulation of the effects of these deviations on measurements closely matched published data. CONCLUSIONS: The method presented here is straightforward and permits numerical and graphical analysis of reconstruction variability. Reconstruction alignment variability should be considered before adopting new reconstruction criteria for clinical use, and evaluated whenever there is suspicion that reconstruction variability could unduly influence subsequent measurements. These evaluations may help drive improvements in reconstruction criteria. The methods described here could also be employed for comparing patient positioning between scans and between different scan modalities.

The quadriceps angle: reliability and accuracy in a fox (Vulpes vulpes) pelvic limb model.

OBJECTIVES: To evaluate the effect of measurement technique and limb positioning on quadriceps (Q) angle measurement, intra- and interobserver reliability, potential sources of error, and the effect of Q angle variation. STUDY DESIGN: Cadaveric radiographic study and computer modeling. ANIMALS: Pelvic limbs from red foxes (Vulpes vulpes). METHODS: Q angles were measured on hip dysplasia (HD) and whole limb (WL) view radiographs of each limb between the acetabular rim, mid-point (Q1: patellar center, Q2: femoral trochlea), and tibial tuberosity. Errors of 0.5-2.0 mm at measurement landmarks alone and in combination were modeled to identify the effect on Q angle. The effect of measured Q angles on the medial force exerted on the patella (F(MEDIAL)) was calculated. RESULTS: The HD position yielded significantly (P < .001) more medial Q angles than the WL position. No significant difference was observed between Q1 and Q2, but Bland-Altman plots indicated they were not equivalent. Intra- and interobserver agreement was substantial. Q2 errors were inherently greater than Q1: the mid-point and tibial tuberosity are the most important sources of Q angle variability. Increasing Q angles significantly increased the exerted F(MEDIAL) (P < .0001, gradient 1.7%). CONCLUSIONS: Measurements are reliable, but Q2 is more prone to error than Q1, and the 2 measurement techniques are not interchangeable. Positional errors must be kept below 1.3 mm (Q1) or 0.8 mm (Q2).