Biomechanical comparison of humeral condyles with experimental intracondylar fissures immobilized with a transcondylar positional or a lag screw: An ex-vivo study in dogs

A 3D Printed Anatomically Pre-Contoured Plate for the Treatment of Y-T Humeral Condylar Fractures: A Feline Cadaveric Study

(1) Background: Anatomically pre-contoured plates usually require only minimal or even no intraoperative contouring. For complex cases, such plates also assist the surgeon as an anatomical template during fracture reduction. In this study, we present our experience of using a 3D printing technology for the treatment of bicondylar humeral fractures in feline cadavers. (2) Methods: Surgeries were performed on 15 pairs of front limbs amputated at the scapula. The limbs were obtained from 15 adult cats without obvious pathology of the skeleton. After flexion of the elbow and subperiosteal elevation of the anconeus muscle, the humeral Y-T fractures were created using a bone chisel and mallet. A custom-made anatomically pre-contoured interlocking plate was used to reduce and stabilise the medial aspect of the humeral condyle to the humeral diaphysis. After reduction of the humeral condyle, a positional locking screw was then inserted from the medial to the lateral side and a straight 2.4/2.7 interlocking bone plate was used to stabilise the lateral part of the condyle to the humeral diaphysis. (3) Results: The length of the humerus ranged from 98.2 to 107.0 mm and did not differ significantly between the left and right bone. The diameter of the isthmus of the humeral condyle ranged from 5.2 to 5.5 mm and did not differ significantly between the left and right bone. In all 30 limbs, bicondylar fracture was accompanied by epicondylar comminution. In 7/30 limbs (4 left, 3 right) the fracture of the humeral shaft was also present. In the left limbs, the postoperative articular surface defect of the humeral condyle was small (<1 mm) in 11/15 cases, moderate (1-2 mm) in 2/15 cases and large (>2 mm) in 2/15 cases in which the condylar screw was incorrectly inserted. In the right limbs, the postoperative articular surface defect of the humeral condyle was small (<1 mm) in 14/15 cases and moderate (1-2 mm) in 1 case. (4) Conclusions: 3D printing and the technology of metal powder sintering offers a wide range of possibilities for the development of new surgical implants. The anatomically pre-contoured bone plate appears to be a valuable tool in the reduction and stabilisation of Y-T humeral fractures in adult domestic cats weighing 3.0 to 4.5 kg.

The effect of an aiming device on the accuracy of humeral transcondylar screw placement

OBJECTIVES

(1) To evaluate the accuracy of an aiming device on placement of humeral transcondylar screws compared to fluoroscopic methods. (2) To compare experience level on outcome.

STUDY DESIGN

Randomized, match pair, prospective ex-vivo study.

SAMPLE POPULATION

A total of 68 dogs.

METHODS

Canine cadaveric forelimbs were randomly assigned to either aiming device or fluoroscopic-guided groups, and to diplomate or resident. Digital radiography was used to evaluate screw trajectory deviation and eccentricity on the humeral condyle. Procedure time, outcome based on experience, and complications were recorded.

RESULTS

The aiming device screw trajectory angle was decreased in the right limb (1.9 ± 1.1°) compared with the left (3.6 ± 1.1°, p = .0178), and compared to fluoroscopy (3.4 ± 1.1° p = .0128). There was no difference between leg laterality with fluoroscopy (p = .9979). Trajectory angle was increased with resident versus diplomate (3.4 ± 1.1° and 2.5 ± 1.1° respectively, p = .0366). Eccentricity deviation was decreased using fluoroscopy versus aiming device (3.1 ± 0.36 mm, 4.2 ± 0.36 mm, respectively, p = .0017). The risk of joint involvement was 8 times greater in aiming device groups, though not significant (p = .0575). Significant complications included increased drill attempts in fluoroscopic groups (p = .0237).

CONCLUSION

The aiming device provided accurate placement of transcondylar screws, in terms of both position on the condyle and trajectory angle. Results were similar to fluoroscopic-guided method.

CLINICAL SIGNIFICANCE

An aiming device is an acceptable means of placing humeral transcondylar screws. The use of the aiming device had an eight times increased risk of joint involvement compared to fluoroscopy.