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- Author or Editor: Michael P. Kowaleski x
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Abstract
Objective—To evaluate the effects of pilot hole diameter and tapping on insertion torque and axial pullout strength of 4.0-mm cancellous bone screws in a synthetic canine cancellous bone substitute.
Sample—75 synthetic cancellous bone blocks (15 blocks/group).
Procedures—For groups 1 through 5, screw size-pilot hole diameter combinations were 3.5–2.5 mm (cortical screws), 4.0–2.5 mm, 4.0–2.5 mm, 4.0–2.0 mm, and 4.0–2.0 mm, respectively. Holes were tapped in groups 1, 2, and 4 only (tap diameter, 3.5, 4.0, and 4.0 mm, respectively). One 70-mm-long screw was inserted into each block; in a servohydraulic materials testing machine, the screw was extracted (rate, 5 mm/min) until failure. Mean group values of maximum insertion torque, axial pullout strength, yield strength, and stiffness were determined.
Results—Mean maximum insertion torque differed significantly among the 5 groups; the group 5 value was greatest, followed by group 3, 4, 2, and 1 values. Group 3, 4, and 5 axial pullout strengths were similar and significantly greater than the group 2 value; all values were significantly greater than that for group 1. Group 5 and 4 yield strengths were similar and significantly greater than the group 3, 2, and 1 values. Stiffness in group 3 was similar to group 4 and 2 values but significantly greater than the group 5 value; all values were significantly greater than that for group 1.
Conclusions and Clinical Relevance—These synthetic cancellous bone model findings suggested that tapping a 2.0-mm-diameter pilot hole when placing a 4.0-mm screw is the optimal insertion technique.
Abstract
OBJECTIVE To determine which method (lateral fabellotibial suture [LFS], tibial plateau leveling osteotomy [TPLO], tibial tuberosity advancement [TTA], or tightrope-like braided multifilament suture secured with metallic buttons [TR]) Veterinary Orthopedic Society (VOS) members preferred for treating cranial cruciate ligament rupture (CCLR) in dogs weighing > 15 kg (33 lb), identify factors associated with this preference, and assess concerns related to surgical implant material used.
DESIGN Cross-sectional study.
SAMPLE 187 VOS members.
PROCEDURES All registered VOS members received an online survey from June to July 2016. Responses were compiled and evaluated for associations with method preferences and perceived complications.
RESULTS Overall response rate was 38.4% (221/575). Respondents had graduated from veterinary school a mean of 23 years prior to survey completion, and collectively they performed approximately 30,000 CCLR surgeries annually. The most commonly preferred method was TPLO (147 [78.6%]), followed by TTA (26 [13.9%]), the LFS procedure (11 [5.9%]), and the TR procedure (3 [1.6%]). The preference for TPLO was independent of board certification or college of training (American, European, or other College of Veterinary Surgeons). Non-board-certified surgeons, including general practitioners, also favored TPLO. The most common perceptions were that titanium implants (used for TTA) were associated with the lowest incidence of major complications, whereas braided multifilament suture (used for the TR procedure) was associated with the highest incidence of major complications.
CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that TPLO was preferred for treating CCLR in dogs weighing > 15 kg and that the TR procedure was perceived as having the highest complication rate. With results of this survey in mind, use of the TR procedure should be considered cautiously when treating CCLR.
Abstract
Objective—To evaluate 2 plate designs for pancarpal arthrodesis and their effects on load transfer to the respective bones as well as to develop a computational model with directed input from the biomechanical testing of the 2 constructs.
Sample—Both forelimbs from the cadaver of an adult castrated male Golden Retriever.
Procedures—CT imaging was performed on the forelimb pair. Each forelimb was subsequently instrumented with a hybrid dynamic compression plate or a castless pancarpal arthrodesis plate. Biomechanical testing was performed. The forelimbs were statically loaded in the elastic range and then cyclically loaded to failure. Finite element (FE) modeling was used to compare the 2 plate designs with respect to bone and implant stress distribution and magnitude when loaded.
Results—Cyclic loading to failure elicited failure patterns similar to those observed clinically. The mean ± SD error between computational and experimental strain was < 15% ± 13% at the maximum loads applied during static elastic loading. The highest bone stresses were at the distal extent of the metacarpal bones at the level of the screw holes with both plates; however, the compression plate resulted in slightly greater stresses than did the arthrodesis plate. Both models also revealed an increase in bone stress at the proximal screw position in the radius. The highest plate stress was identified at the level of the radiocarpal bone, and an increased screw stress (junction of screw head with shaft) was identified at both the most proximal and distal ends of the plates.
Conclusions and Clinical Relevance—The FE model successfully approximated the biomechanical characteristics of an ex vivo pancarpal plate construct for comparison of the effects of application of different plate designs.
