CT Reveals Hidden Fracture Complexity in Warmblood P2 Injuries—Transforming Surgical Planning

Use of preoperative computed tomography (CT) to plan repair of comminuted fractures of the middle phalanx in six Warmblood horses: Configuration, treatment and long-term outcome

Marco Marcatili, Andrey Kalinovskiy, Christoph Lischer

Background

Comminuted fractures of the middle phalanx (P2) are common severe injuries in horses, arising from axial compression, bending, and torsion forces acting on a fixed hoof. These fractures frequently involve the proximal interphalangeal joint (PIPJ), produce acute non-weightbearing lameness, and often require internal fixation and arthrodesis. Radiography is the standard preoperative imaging modality, but its ability to characterize complex fracture patterns—particularly their three-dimensional configuration—is limited. Computed tomography (CT) is considered the gold standard for characterizing fracture configuration, yet published studies evaluating CT-assisted repair in heavier breeds such as Warmbloods are lacking. The authors aimed to describe the use of a standardized fast CT protocol (SFP) to assist surgical planning for comminuted P2 fractures, evaluate added diagnostic value, and report long-term outcomes.

Methods

This case series included six Warmblood horses presenting with comminuted P2 fractures between 2019 and 2024 at a single referral hospital. All underwent radiography followed by general-anesthesia CT using a standardized fast protocol assessing fracture configuration in transverse, frontal, and sagittal planes. Radiographic and CT findings were compared, and intraoperative visualization of the proximal P2 articular surface was also evaluated for added information. All horses underwent surgical repair consisting of fracture reduction, PIPJ arthrodesis, and internal fixation with two dorsally placed locking compression plates; additional cortical screws (4.5/5.5 mm) were inserted in lag fashion as indicated by CT. Postoperative management included antimicrobial therapy, NSAIDs, casting, and scheduled radiographic follow-up. Outcomes and complications were documented over at least 6 months.

Results

CT provided additional information beyond radiographs in all cases. It identified additional fracture lines, clarified fragment number and orientation—particularly in the distal third of P2—and precisely defined the intact cortical strut used for implant anchoring. CT also detected injuries not visible radiographically: dorsal navicular bone fractures in two horses and deep digital flexor tendon rupture in one. These findings altered surgical planning, including placement of lag screws, need for transfixation pin casting, and client counseling. Surgical repair was completed without intraoperative complications. Of the six horses, five survived hospitalization; one was euthanized due to severe postoperative colitis. Long-term (>6 months) follow-up showed four surviving horses with mild (3/5) lameness at trot; two returned to light hacking and two were retired. One horse sustained catastrophic refracture one year after surgery. Follow-up radiographs demonstrated osteoarthritis of the distal interphalangeal joint (DIPJ) in all horses for whom images were available.

Limitations

The study included a small sample size, limiting generalizability. Image interpretation was performed by a single associate member of ECVDI, potentially introducing observer bias. Some fractures may have displaced further during induction of anesthesia, increasing discrepancies between radiographs and CT. Postoperative CT was not performed due to anesthesia risks, limiting assessment of repair quality. Finally, lameness and outcome assessments relied partly on owner and referring veterinarian reports.

Conclusions

A standardized preoperative CT protocol reliably provided critical information on fracture configuration, concurrent soft tissue injury, and optimal screw and plate placement in Warmblood horses with comminuted P2 fractures. CT consistently revealed details not detectable radiographically or intraoperatively, enabling more precise surgical planning and improved construct stability. Although overall outcomes remained guarded and DIPJ osteoarthritis was common, CT-assisted fixation supported return to light activity in most surviving horses. The authors conclude that preoperative CT is a valuable tool in managing complex P2 fractures in heavier breeds.

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