Biomechanical Comparison of Double 2.3-mm Headless Cannulated Self-Compression Screws and Single 3.5-mm Cortical Screw in Lag Fashion in a Canine Sacroiliac Luxation Model: A Small Dog Cadaveric Study

OBJECTIVE

 The aim of this study was to evaluate the feasibility of safe positioning of double 2.3-mm headless cannulated self-compression screws (HCS) in a small dog cadaveric sacroiliac luxation model and to compare the static rotational biomechanical properties of fixation repaired using two different screw systems with a minimally invasive osteosynthesis technique: double 2.3-mm HCS and a single 3.5-mm standard cortical screw placed in a lag fashion.

STUDY DESIGN

 A unilateral small dog sacroiliac luxation model was stabilized using double 2.3-mm HCS (n = 11) or a single 3.5-mm cortical screw (n = 11). Radiographic and computed tomography (CT) imaging analyses and biomechanical testing of rotational force on the sacroiliac joint of both fixations were performed. The maximum load at failure and failure modes of each fixation were recorded and compared.

RESULTS

 Fluoroscopically guided percutaneous application of double HCS was safe in a unilateral sacroiliac luxation model in small dogs without violation of the vertebral and ventral sacral foramen. Furthermore, resistance to rotational force applied on fixation of the sacroiliac joint repaired with double 2.3-mm HCS estimated by maximum failure load was significantly higher than that of a single 3.5-mm cortical screw (p < 0.001).

CONCLUSION

 Although this was an experimental cadaveric study, based on our results, the use of smaller double HCS may be beneficial as an alternative to the conventional single lag screw for stabilization of sacroiliac luxation in small dogs.

Outcomes for 15 cats with bilateral sacroiliac luxation treated with transiliosacral toggle suture repair

OBJECTIVE

To report a surgical technique and outcomes of transiliosacral toggle suture repair to treat feline bilateral sacroiliac luxation/fracture (SILF).

STUDY DESIGN

Retrospective study.

ANIMALS

Fifteen client-owned cats.

METHODS

The medical records of cats with bilateral SILF treated using a transiliosacral toggle suture repair were reviewed. Short- and medium-term outcomes were assessed through standard postoperative clinical evaluation and radiographs, including measurements of angle of deviation (AoD), percentage of reduction (PoR), and pelvic canal width ratio (PCWR). Long-term functional follow up was obtained from a questionnaire derived from the Feline Musculoskeletal Pain Index (FMPI).

RESULTS

Fifteen cats were enrolled retrospectively, among which 13 survived to discharge. One minor wound complication, treated by secondary intention healing, was encountered. No major complication was reported. Immediately postoperatively, the mean absolute PoR values were 88.1 ± 11.2% and 91 ± 11.6% on the right and left side, respectively. The mean absolute AoD was 3.1 ± 2.8°, and the mean PCWR was 1.24 ± 0.08. The medium-term radiographic follow up at a median of 205 (71-682) days postsurgery revealed the good stability of the repair. Excellent functional outcomes were identified upon the analysis of 12 long-term questionnaires at a median of 365 (119-798) days postsurgery.

CONCLUSION

Anatomic reduction was satisfactory and comparable with previously described techniques with good implant placement documented. Functional outcomes based on FMPI-derived questionnaires were good to excellent in our population.

CLINICAL SIGNIFICANCE

Transiliosacral toggle suture stabilization of bilateral SILF was associated with good outcomes in cats. Further studies are required to compare biomechanical properties and outcomes between this technique and previously described transiliosacral stabilization.

Structural anatomy and morphometric analyses of sacra in greyhounds

This study was conducted to provide structural and morphological data on the sacra of greyhounds. Descriptive quantitative investigation was carried out on 171 sacra of greyhound`s cadavers and then classified into standard and fused sacra based on the number of fused sacral vertebrae. The weight, length and width of sacrum of sacra were measured. Both standard (59%) and fused sacra (41%) were identified. The average length and width of the standard sacrum were found to be 46.14 ± 2.53 mm and 57.89 ± 3.54 mm, respectively. The sacral length was 1.61-mm longer in males (p < .01), and the sacral width was 0.46-mm shorter in males but not significant (p = .51). The average weight of a standard sacrum was 26.54 ± 4.55 g and was 1.18 g heavier in males but not statistically significant (p = .24). Results showed that one-kilogram increase in the body mass was associated with a 0.3 mm (p < .001) increase in sacral length, and a 0.54 mm (p < .001) increase in sacral width, respectively. The morphological data of the standard and fused sacra provided in this study might help the veterinary community to improve treatment and rehabilitation and help the trainer to design the right training protocol for racing greyhounds. In addition, the results of this study are a step to understand the sacrum's functions and how the greyhound's body functions and future studies are required to investigate the biological importance of these findings.

A structural numerical model for the optimization of double pelvic osteotomy in the early treatment of canine hip dysplasia

Background: Double pelvic osteotomy (DPO) planning is usually performed by hip palpation, and on radiographic images which give a poor representation of the complex three-dimensional manoeuvre required during surgery. Furthermore, bone strains which play a crucial role cannot be foreseen.

Objective: To support surgeons and designers with biomechanical guidelines through a virtual model that would provide bone stress and strain, required moments, and three-dimensional measurements.

Methods: A multibody numerical model for kinematic analyses has been coupled to a finite element model for stress/strain analysis on deformable bodies. The model was parametrized by the fixation plate angle, the iliac osteotomy angle, and the plate offset in ventro-dorsal direction. Model outputs were: acetabular ventro-version (VV) and lateralization (L), Norberg (NA) and dorsal acetabular rim (DAR) angles, the percentage of acetabular coverage (PC), the peak bone stress, and moments required to deform the pelvis.

Results: Over 150 combinations of cited parameters and their respective outcome were analysed. Curves reporting NA and PC versus VV were traced for the given patient. The optimal VV range in relation to NA and PC limits was established. The 25° DPO plate results were the most similar to 20° TPO. The output L grew for positive iliac osteotomy inclinations. The 15° DPO plate was critical in relation to DAR, while very large VV could lead to bone failure.

Clinical significance: Structural models can be a support to the study and optimization of DPO as they allow for foreseeing geometrical and structural outcomes of surgical choices.

ORCID iD

ALA: http://orcid.org/0000-0002-4877-3630

AV: http://orcid.org/0000-0003-2837-7822

CB: http://orcid.org/0000-0002-7065-2552

EZ: http://orcid.org/0000-0003-4121-6126

MT: http://orcid.org/0000-0002-5699-6009