Hip (Clements-Nakayama view)

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The Clements-Nakayama view of the hip is a highly specialized lateral projection utilized on patients with bilateral femoral fractures, or patients unable to mobilize due to postoperative requirements. When performed correctly the projection can yield images of a high diagnostic quality comparable to the horizontal beam lateral hip.

This projection can also be utilized to image the femoral shaft in the setting of bilateral femoral fractures (see figure 1).

Indications

The projection was first described in 1980 as a method to image patients after total hip arthroplasty however it can be utilized in most scenarios where a lateral view of the hip and the patient is unable to move.

Patient position

  • patient is supine with the side of interest close to the edge of the table
  • arms are placed on the chest

Detector position

  • image receptor is held in a detector stand and placed in landscape above the iliac crest of the affected side
  • ensure the detector is running parallel to the femoral neck (this can be calculated on the AP pelvis projection)

Technical factors

  • axiolateral projection
  • centering point
    • the central ray is projected inferiorly superiorly from the opposite side of the affected limb
    • there is a 15 posterior angle centered on the region of the femoral neck. Note, this angle is a guide and further angle is frequently required
    • the mediolateral angle is changed to accommodate align to the femoral neck
  • collimation
    • anteroposterior 9 cm each direction from the midline
    • inferosuperior 12 cm each direction from the centering point
  • orientation  
    • landscape
  • detector size
    • 24 x 30 cm (however this will vary with NOF vs. femoral shaft)
  • exposure
    • 80-90 kVp
    • 80-150 mAs (highly dependent on patient habitus)
  • SID
    • 100-150 cm
  • grid
    • a grid can be used, although it is not uncommon to utilize an air gap technique to achieve similar results

Image technical evaluation

The radiograph has a uniform exposure throughout, evident by the fine bony detail and no areas of overexposure. If the distal femur is overexposed, then a filter may be required.

The lesser trochanter can be seen in profile, while the proximal femoral shaft superimposes the greater trochanter.

The femoral neck is central to the image and shows no signs of radiographic foreshortening or elongation.

There is a clear visualization of the articular surface of the acetabulum and the head of the proximal femur.

Practical points

This is one of the harder projections in trauma imaging to master, it is used infrequently and requires a higher level of skill than standard hip views. Something to consider when setting up for a Clements-Nakayama view is the patient's soft tissue volume, patients with a higher proportion require a steeper posterior angle to clear the other leg.

The posterior angle is necessary to achieve a true lateral hip, however, be wary of any metal on the table that may project onto the image. This is why the patient should be as close as safely possible to the edge of the table closest to the detector.

The best way to approach the examination would be to consider this projection similar to a shoot through the hip, however, you are angling down rather than raising the leg.