Application of a locking cortical pearl plate system to the feline lumbar vertebral column: a cadaveric study.

Abstract

Aims: To assess the feasibility and safety of a locking cortical pearl plate system for the repair of lumbar vertebral fractures and luxation in cats using an ex vivo feline model.

Methods: This cadaveric study of the lumbar vertebral column (L1-L7) involved 28 Domestic Short-hair cats without vertebral column pathology. Surrounding soft tissue was removed, except for the paravertebral musculature, joint capsules, and ligaments associated with the L1-L7 vertebrae. To determine whether the application of a 2.0-mm, 69-mm-long, 12-hole locking cortical pearl plate (LCPP) and screws was feasible, the dimensions of the feline lumbar vertebral bodies (length, width, and height) were measured using CT imaging. Width and height were evaluated at five locations along the length of the vertebrae with implant corridors (cor 1-cor4) located in between. Following CT, plates were applied to the vertebral columns. After implantation, another CT scan was performed to evaluate plate positions, screw trajectories, screw implantation angles, and vertebral canal breaching. Implantation was classified according to the modified Zdichavsky scoring system for vertebral canal penetration and grade I and IIa defined as acceptable.

Results: A total of 371 screws were inserted into the lumbar vertebral bodies, and breaching occurred in 32 cases (8.6%), of which 29 (90.6%) were at L6 and L7. The median angle of inserted screws was 61.6° (min 53.4°, max 76.3°). Aside from one location, no significant angle deviations were observed between breaching (median 62.8°; min 53.4°, max 76.3°) and non-breaching (median 61.2°; min 53.8°, max 74.7°) screws. All 267 screws implanted in L1-L5 were graded I or IIa (acceptable). In contrast, low rates of acceptable implantation were achieved for L6 (52/60; 86.7%) and L7 (24/44; 54.4%), caused by clustering of breachings in corridor 3 of the two vertebrae.

Conclusions: Application of the LCPP immediately proximal to the transverse processes and ventral to the pedicles with a screw implantation angle of 60° is feasible and appears safe for L1-L5, resulting in a low number of vertebral canal breaches and a high rate of acceptable implantations.

Clinical relevance: The 2.0-mm, 69-mm-long, 12-hole LCPP can be considered an acceptable option for treating feline vertebral fractures and luxations of L1-L5. It cannot be recommended for use in corridor 3 of L6 or L7 due to the high risk of breaching the vertebral canal.