Semi-cylindrical recession trochleoplasty using 3D saw guides for canine patellar luxation

Medial patellar luxation (MPL) is a common orthopaedic condition in dogs that often requires surgical intervention. Semi-cylindrical recession trochleoplasty (SCRT) is a promising technique; however, the adjustment increments of commercially available SCRT saw guides are limited. As an alternative, the effectiveness of patient-specific 3D-printed saw guides for SCRT was assessed for three small dogs with MPL. An eight-year-old Chihuahua (6 kg) and a ten-year-old Maltese (5 kg) with MPL Grade 3, as well as a fiveyear- old Cocker Spaniel (10 kg) with MPL Grade 4, were included in this study. Preoperative computed tomography (CT) scans confirmed no angular bone deformities in the three dogs. The animals underwent SCRT using 3D-printed patient-specific saw guides, which allowed for customised adjustments to the trochlear groove depth, overcoming the 1.5 mm increment limitation of commercially available guides. Digital imaging and communications in medicine (DICOM) images from the CT scans were converted into stereolithography (STL) files and Fusion 360 was used to design the saw guides, which were then 3D-printed for use with SCRT under general anaesthesia. Postoperative orthopaedic examinations and radiographs performed two weeks after surgery showed that two of the dogs had no pelvic limb lameness or patellar reluxation. One patient did not achieve complete MPL correction, despite the appropriate trochlear groove depth being obtained, due to extrinsic factors. The 3D-printed patient-specific saw guides facilitated precise customisation of the trochlear groove depth during SCRT in the dogs analysed in this study, highlighting the potential to enhance surgical accuracy. Therefore, this approach has the potential to advance MPL treatment by enabling greater surgical precision and addressing challenges associated with operative time and technical difficulty. Further studies with larger sample sizes and standardised protocols are needed to fully assess the clinical benefits and cost-effectiveness of this method.