Imaging of joint arthroplasties

The role of imaging in arthroplasty planning

Joint arthroplasty is a key orthopedic intervention for severe injuries and systemic dysplasias involving the epiphyses (e.g., multiple epiphyseal dysplasia) that lead to premature osteoarthritis. Arthrography, ultrasound, CT, and MRI are paramount in evaluating joint problems during the surgical planning stage and in the postoperative period.

Standard radiography is used to confirm intracapsular fractures of the proximal femur requiring joint replacement (hemiarthroplasty or total arthroplasty). The examination must include an anteroposterior (AP) pelvic projection to compare the injured side with the healthy one. Due to severe pain, the so-called groin lateral projection is used. This technique employs a horizontal beam with a 20-degree cranial angulation, centered on the greater trochanter, with the patient's opposite hip flexed. This eliminates the need to move the injured limb.

Diagnosis of occult and complex fractures

Up to 15% of femoral neck fractures may be non-apparent on initial radiographs. Radiographic signs of such occult injuries (including impacted non-displaced fractures) include:

• Interruption of trabecular lines.
• Presence of a sclerotic line.
• Disruption of the normal trabecular pattern.

If visualization on the AP radiograph is doubtful, quality of care criteria mandate mandatory CT or MRI to confirm or exclude an occult fracture.

High-resolution imaging is also critical in forearm injuries. CT or MRI of the upper extremity is strictly indicated for radial injuries to clarify the intra-articular nature of the fracture and assess associated capsule-ligamentous ruptures. In complex multifragmentary fractures of the proximal forearm, management tactics may include resection or radial head arthroplasty.

Hip fracture classification and risk of avascular necrosis

In proximal femur fractures, it is fundamentally important to assess the risk of losing the viability of the femoral head. Blood supply in this area is provided by recurrent arteries closely adjacent to the neck. Their damage leads to avascular necrosis (avascular necrosis), which develops in 15–35% of patients.

By localization, fractures are divided into:

1. Intracapsular (Intracapsular): subcapital, transcervical, basilar.
2. Extracapsular (Extracapsular): intertrochanteric, subtrochanteric (the risk of blood supply disruption is significantly lower in these).

The Garden classification (Garden classification) is used to assess intracapsular fractures. Types 3 and 4, accompanied by fragment displacement (e.g., displaced subcapital fracture), almost inevitably lead to blood flow disruption. This is why elderly patients with such injuries who were independently mobile prior to the incident are indicated for hemiarthroplasty or total arthroplasty. Younger patients (under 60 years) with non-displaced fractures (Garden 1 and 2) more often undergo internal fixation.

Quality criteria and patient management

Management protocols for patients with fractures requiring arthroplasty are strictly regulated:

• Timing of surgery: Arthroplasty (total or hemiarthroplasty) or hip osteosynthesis must be performed strictly no later than 48 hours after the patient's admission to the hospital. This is necessary to minimize the risk of thromboembolic, hypostatic, cardiac, and pulmonary complications.
• Initial examination: An orthopedic traumatologist is required to examine the admitted patient strictly no later than 1 hour from the moment of admission.
• VTE prophylaxis: All patients requiring surgical treatment for pathological fractures due to osteoporosis are indicated for low-molecular-weight heparins. Individual surgical risk factors (long operation time, combined approach) are taken into account.

Class and exam questions

What else to study on this topic

• Differential diagnosis of pathological fractures (metastases, myeloma, Paget's disease).
• Insufficiency fractures of structurally compromised pelvic ring and their MRI presentation.
• Whole-body MRI and STIR/DWI sequences for global assessment of multifocal diseases.
• Radiographic signs and clinical types of osteogenesis imperfecta (Sillence classification).
• Indications for CT and MRI in assessing cranial nerve and spinal cord compression.

Other topics in the "Additional Topics" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.