Top 5 Positioning Mistakes in Orthopedic Radiography

In orthopedic surgery, preoperative planning is everything. A flawless Tibial Plateau Leveling Osteotomy (TPLO) relies entirely on perfect radiographic positioning. A rotation of just 5 degrees can critically alter your angle measurements, leading to surgical under- or over-rotation, delayed healing, or catastrophic implant failure.

Here are the top five positioning mistakes we see daily at RapidVet, and exactly how to fix them in your practice.

1. The "Almost" True Lateral Stifle for TPLO

For TPLO planning, achieving a true, straight-line lateral view of the tibia and stifle is paramount. The femoral condyles must be perfectly superimposed.

• The Mistake: Subtle internal or external rotation. If the medial condyle is cranial to the lateral, the leg is internally rotated. This distortion artificially changes the tibial plateau angle (TPA).
• The Impact: An artificially low TPA reading can lead to under-rotation during surgery, leaving the dog with persistent cranial tibial thrust.
• The Fix: Use a sponge wedge under the tarsus to keep the tibia perfectly parallel to the table. Ensure the x-ray beam is centered exactly over the stifle joint, not midway down the tibia.

2. Inadequate Collimation and Centering

Scatter radiation degrades image contrast, creating a persistent, muddy gray overlay on the image.

• The Mistake: Leaving the collimator wide open to catch "the whole leg" when evaluating a specific joint.
• The Impact: Decreased diagnostic quality obscures subtle osteophytes or early subchondral bone defects characteristic of osteochondrosis dissecans (OCD) or early osteoarthritis. It also exposes the patient and staff to unnecessary scatter radiation based on ALARA principles.
• The Fix: Collimate tightly to include only the joint of interest and approximately 1/3 of the long bones proximal and distal to it. Center the primary beam directly over the joint space.

3. Neglecting the Contralateral Limb

Assuming standard angles and anatomies universally apply is a dangerous gamble, especially in highly specialized breeds.

• The Mistake: Only imaging the obviously lame leg.
• The Impact: Missing the patient's baseline normal. In juvenile animals with open physes, or when investigating subtle angular limb deformities (e.g., antebrachial growth deformities), comparing the affected limb to the "normal" contralateral limb is a vital diagnostic key.
• The Fix: Standardize protocols for complex lameness to always include comparison views of the opposite limb, particularly in growing puppies.

4. Improper Pelvic Symmetry for Dysplasia Screening

Whether for formal OFA submission or in-house evaluation of hip dysplasia, the extended ventrodorsal (VD) pelvic view demands absolute, painful symmetry.

• The Mistake: Allowing the pelvis to tilt slightly along its longitudinal axis.
• The Impact: Rotation artificially deepens the acetabulum on the "up" side (making it look healthier) and shallows it on the "down" side (mimicking severe dysplasia). The femurs will falsely appear to have different degrees of coverage.
• The Fix: The femurs must be completely parallel to each other and the spine. Crucially, inspect the obturator foramina: they must be identical in size and shape. Use a V-trough and secure the patient's thorax to prevent rotational torque transferring down the spine.

5. Forgetting to Sedate

This is arguably the root cause of the previous four mistakes.

• The Mistake: Attempting orthopedic imaging on an awake, painful, and tense animal.
• The Impact: You cannot fight muscle tension, fear, and joint pain to get a perfectly positioned orthopedic study. The struggle compromises positioning, requires multiple takes (increasing radiation exposure), and stresses the patient.
• The Fix: Develop a low-threshold protocol for heavy sedation or general anesthesia for all diagnostic musculoskeletal imaging. The diagnostic yield of a relaxed patient far outweighs the time spent waiting for sedation.

Need Pre-Surgical Review?

Orthopedic procedures are high-stakes, expensive, and carry significant morbidity if they go wrong. Before you cut, ensure your radiographic data is bulletproof. Send your pre-surgical DICOMs to our urgent 4-hour review team if a fracture demands immediate surgical intervention, or utilize our routine service for complex elective planning.