Small Animal Orthopaedics and Arthroscopy

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Case study: 3D printing using computed tomography (CT)

Bob Jackson, 2 year old, male neutered, English Springer Spaniel

Humeral intercondylar fissure (HIF) is a condition of the canine elbow, which is poorly understood. It was originally thought to be caused by the failure of the medial and lateral humeral condyles to fuse between eight and twelve weeks of age- incomplete ossification of the humeral condyle (IOHC). However, new evidence suggests HIFs may develop later in life, possibly as a result of abnormal loading. A genetic component is highly suspected given that spaniel breeds are largely affected. The condition can be asymptomatic, result in forelimb lameness or can give rise to a stress fracture.
Bob first presented as an emergency with a humeral bi-condylar “Y” fracture of the left elbow (Figure 1a). This was successfully repaired and Bob gradually returned to normal exercise post-surgery (Figure 1b). No intercondylar fissures were seen at the time on radiographs of the right elbow.

Figure 1 a) Left elbow bi-condylar fracture b) Post-operative radiograph of fracture repair using a combination of lag screws, locking compression plates and a SOP plate.
1a 1b
Two years later, Bob returned to Ridge Referrals with grade 2/5 right forelimb lameness. A CT scan revealed a humeral condylar fissure in the right elbow (Figure 2a). The fracture in his left elbow was likely caused by the same condition, so in order to treat the lameness and reduce the risk of another fracture, surgery was the most favourable option for Bob. Computer Aided Design (CAD) was used to generate a 3D model of the distal humerus from the CT scan (Figure 3), in addition to three custom-made drill guides of diameter 2.5mm, 3.2mm and 4.3mm, to allow a hole of increasing diameter to be drilled across the humeral condyles during surgery. This was followed by the placement of a 32mm x 5mm titanium screw across the humeral condyles. A post-operative CT revealed the screw was in an optimal position (Figure 2b). Bob was rested for 4 weeks following surgery and is now doing well and enjoying returning to his active life!

Figure 2 a) HIF in the right elbow (arrow) b) Post-operative CT scan

2a 2b
Figure 3 A: One of three custom made drill guides B: 3-D model of the distal humerus