# An Anatomical Study on Canine Cadavers Investigating the Caudolateral Approach Involving the Elevation of the Anconeus Muscle and Splitting of the Triceps Brachii Muscle for the Potential Treatment of T-Y Humeral Fractures

## TL;DR

This study explores a new surgical approach in dogs to better access and treat complex humeral fractures by elevating the anconeus muscle and splitting the triceps brachii.

## Contribution

The study introduces a caudolateral approach involving muscle elevation and splitting to improve access for T-Y humeral fracture repairs in dogs.

## Key findings

- The caudolateral approach provided good access to the condyle, epicondyles, and humeral shaft in all cadavers.
- Olecranon osteotomy significantly increased the visible area of the articular surface of the humeral condyle.
- The radial nerve was consistently identifiable and protectable during the procedure.

## Abstract

Humeral condylar and epicondylar fractures (T-Y fractures), are one of the most challenging orthopedic injuries to treat in dogs. Despite advances in internal fixation techniques, complications following repairs to these fractures often occur. It is widely recognized that achieving anatomical reduction in intra-articular fractures is important for restoring joint function. Due to the anatomical complexity of the distal humerus and elbow joint, it is often difficult to expose all lines of a T-Y fracture appropriately. Currently, the combined lateral and medial approach is the preferred method for treating distal humeral fractures in small animals. This approach provides good exposure of the lateral and medial epicondyles and the humeral diaphysis. However, access to the articular surface of the condyle is limited. In this anatomical cadaveric study, we present the results of using the caudolateral approach, which involves elevating the anconeus muscle and splitting the triceps brachii. We find this approach useful because it provides good access to the condyle, the epicondyles, and the humeral shaft. It can also help surgeons see fracture lines more clearly during repair. Appropriate reduction and instrumentation of T-Y fractures are crucial for restoring elbow joint function.

Due to the complex anatomical structure of the distal humerus, elbow joint, and the soft tissue mantle (the triceps brachii muscle, large nerves, and vessels), fractures of the distal humerus and humeral condyle are difficult to treat. In most cases, strong instrumentation is needed to stabilize the fractures. To improve exposure of the distal humerus and humeral condyle, we proposed a caudolateral approach that involves elevating the anconeus muscle and splitting the triceps brachii. This study presents the results of using this approach in 16 canine cadavers. After exposing the distal humerus and maximally flexing the elbow joint, photographs were taken of the condyle from the same distance before and after olecranon osteotomy. The visible surface area of the articular cartilage was then calculated in square pixels after calibrating the photographs. It was possible to reach the distal and middle humerus in all cases. The only vital structure that could be easily identified and protected in all cadavers was the radial nerve. The visible area of the articular surface of the humeral condyle increased after olecranon osteotomy. The A0 (visible area before osteotomy) was significantly smaller than the A1 (visible area after osteotomy) in all dogs (p < 0.001). The ratio of A0 to A1 ranged from 57% to 67% in 15 dogs (median: 64%, interquartile range (IQR): 61–66%), with a very high value of 85% observed in one dog. This experiment used cadavers with intact elbows. This could limit the study’s findings because the effectiveness of the proposed access in reducing T-Y fractures was not assessed. The caudolateral approach is a valuable alternative to other methods for treating T-Y humeral fractures in dogs. Olecranon osteotomy widens access to the condyle. Further studies are needed to evaluate the necessity of olecranon osteotomy in clinical cases.