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Ex Vivo Biomechanical Evaluation of the Canine Cranial Cruciate Ligament‐Deficient Stifle with Varying Angles of Stifle Joint Flexion and Axial loads after Tibial Tuberosity Advancement
Author(s) -
Hoffmann Daniel E.,
Kowaleski Michael P.,
Johnson Kenneth A.,
Evans Richard B.,
Boudrieau Randy J.
Publication year - 2011
Publication title -
veterinary surgery
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 79
eISSN - 1532-950X
pISSN - 0161-3499
DOI - 10.1111/j.1532-950x.2011.00807.x
Subject(s) - cruciate ligament , stifle joint , cadaveric spasm , patellar ligament , medicine , weight bearing , knee joint , cadaver , patella , load cell , orthodontics , biomechanics , tibia , anatomy , tendon , patellar tendon , surgery , anterior cruciate ligament , structural engineering , engineering
Objective: To evaluate the effect of tibial tuberosity advancement (TTA) on cranial tibial thrust (CrTT), retropatellar force (RPF), patellar tendon load (PTL), and patellar tendon angle determined by the tibial plateau angle (PTA TPA ) method or common tangent (PTA CT ) method in the canine cranial cruciate ligament (CrCL)‐deficient stifle joint. Study Design: Ex vivo cadaver study. Sample Population: Cadaveric canine hind limbs (n=30). Methods: Stifle joints were subjected to 3 differing loading conditions using a constrained limb press model (Group1: 30% body weight axial load at stifle and talocrural joint angles of 135 ± 5° and 145 ± 5°, respectively; Group 2: 30% body weight axial load at stifle and talocrural angles of 145 ± 5° and 135 ± 5°, respectively; and Group 3: 50% body weight axial load at stifle and talocrural joint angles of 135 ± 5° and 145 ± 5°, respectively). The CrCL was transected in situ under load; sensors allowed direct measurement of CrTT, RPF, and PTL. Lateral radiographic projections were used to assess PTA TPA and PTA CT . Descriptive statistics were used to report CrTT (by design this force returned to 0‐point values, defined as the neutral point of advancement [NPA]). At the NPA, RPF was compared with baseline using a 2‐tailed sign test. PTL within groups were compared using a paired t‐test; pair‐wise comparisons of PTA TPA and PTA CT were performed using a paired t‐test. Comparisons between loading conditions were made with a 1‐way ANOVA and Tukey's post hoc test. Equivalence tests were used to test mean PTA TPA and PTA CT for equivalence to 90°. Significance was set at a P ‐value of .05. Results: CrTT returned to baseline values, and RPF and PTL at NPA were reduced below baseline values in all specimens in a near linear fashion with TTA. At the NPA, PTA TPA >PTA CT in 2 of the 3 loading conditions, but insufficient evidence to suggest they differed in the third. Mean PTA TPA and PTA CT varied between loading conditions. The threshold for each of the groups evaluated, at which the PTA could be significantly different from 90°, was larger for PTA TPA than PTA CT in all groups, as greater variation was observed with PTA TPA versus PTA CT . Conclusion: This study further supports the claim that reduction of CrTT occurs after TTA in the CrCL‐deficient stifle joint through an alteration of PTA. Additionally, RPF and PTL also decrease after TTA. The PTA CT may be a more precise method of determining PTA.