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Roentgenographic Assessment of Acromial Morphologic Condition in Rotator Cuff Impingement Syndrome.

·J Shoulder Elbow Surg·1995·84 citations·Shoulder & Elbow
PubMed
SummaryAbstract on PubMed →

This prospective study asked which shoulder radiographs actually reflect the true acromial spur in impingement syndrome. Preoperative measurements from four views were compared against direct intraoperative measurements in 23 patients undergoing open acromioplasty. Four blinded readers scored each view for reliability.

Study Snapshot

Design
Prospective cohort
Blinding: Single-blind
Setting: Single academic shoulder service
Objective
Whether specialized radiographic acromial measurements correlate with actual intraoperative spur morphology in impingement syndrome.
Outcome(s)
Interobserver reliability and radiographic-to-operative correlation of acromial measurements
Subjects
23 patients with refractory impingement
  • Open acromioplasty
Inclusion
  • Isolated impingement diagnosis
  • Refractory to conservative therapy
  • Positive impingement sign
Exclusion
  • Prior surgery on same shoulder
  • Neck pain or symptoms distal to elbow
  • Significant acromioclavicular joint disease
Statistics
Intraclass correlationSpearman correlation

Key Findings

  • The 30° caudal tilt measurement of spur distance from the acromial cortical line had the best interobserver reliability of the study at ICC 0.84 (excellent, >0.75). This is the view four blinded readers agreed on most.
  • The axillary view was essentially useless for spur assessment, with an ICC of 0.09 and poor correlation with every operative measurement. Reserve it for detecting an os acromiale and glenohumeral arthritis, not the spur.
  • Two views correlated with real anatomy in complementary planes. The caudal tilt spur-to-cortex measurement tracked operative spur length (p=0.048), while the outlet view acromial slope tracked standardized anterior acromion thickness (p=0.0067).
  • The 30° caudal tilt view was also the most practical: 96% of films were technically acceptable and 74% showed a grossly visible spur, both the highest of any view.
  • The acromial tilt angle (Aoki) had acceptable reliability at ICC 0.63 but did not correlate with any operative spur measurement, so reliability alone does not make a measurement clinically meaningful.
  • Among these refractory impingement patients, 70% had complete rotator cuff tears at surgery, underscoring that persistent impingement often signals structural cuff damage.
  • Mean operative acromial dimensions were:
    –Anterior projection beyond clavicle 10.0 mm
    –Anterior thickness 12.8 mm
    –Posterior thickness 8.1 mm
    –Dropping to 5.4 mm after acromioplasty.
Board PearlThe 30° caudal tilt view is the most reliable radiograph (ICC 0.84) for assessing the anterior acromial spur in impingement syndrome.

Clinical Relevance

When you order imaging for refractory impingement, the goal is to confirm a bony spur before committing to acromioplasty. This paper tells you which views to trust. The 30° caudal tilt view is the workhorse: it is the easiest to obtain, the most reproducible across readers, and it correlates with the actual three-dimensional spur length. It also lets you confirm adequacy of resection afterward.

The supraspinatus outlet view adds complementary information by capturing anterior acromion thickness and acromial shape, which ties back to the Bigliani flat/curved/hooked classification you need for boards.

The teaching point: don't rely on the axillary view for the spur. Its job is to catch an os acromiale and glenohumeral arthritis. A measurement can be reliable yet clinically meaningless, as the acromial tilt angle demonstrates here.

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Roentgenographic Assessment of Acromial Morphologic Condition in Rotator Cuff Impingement Syndrome.

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|

Roentgenographic Assessment of Acromial Morphologic Condition in Rotator Cuff Impingement Syndrome.

·J Shoulder Elbow Surg·1995·84 citations·Shoulder & Elbow
PubMed
SummaryAbstract on PubMed →

This prospective study asked which shoulder radiographs actually reflect the true acromial spur in impingement syndrome. Preoperative measurements from four views were compared against direct intraoperative measurements in 23 patients undergoing open acromioplasty. Four blinded readers scored each view for reliability.

Study Snapshot

Design
Prospective cohort
Blinding: Single-blind
Setting: Single academic shoulder service
Objective
Whether specialized radiographic acromial measurements correlate with actual intraoperative spur morphology in impingement syndrome.
Outcome(s)
Interobserver reliability and radiographic-to-operative correlation of acromial measurements
Subjects
23 patients with refractory impingement
  • Open acromioplasty
Inclusion
  • Isolated impingement diagnosis
  • Refractory to conservative therapy
  • Positive impingement sign
Exclusion
  • Prior surgery on same shoulder
  • Neck pain or symptoms distal to elbow
  • Significant acromioclavicular joint disease
Statistics
Intraclass correlationSpearman correlation

Key Findings

  • The 30° caudal tilt measurement of spur distance from the acromial cortical line had the best interobserver reliability of the study at ICC 0.84 (excellent, >0.75). This is the view four blinded readers agreed on most.
  • The axillary view was essentially useless for spur assessment, with an ICC of 0.09 and poor correlation with every operative measurement. Reserve it for detecting an os acromiale and glenohumeral arthritis, not the spur.
  • Two views correlated with real anatomy in complementary planes. The caudal tilt spur-to-cortex measurement tracked operative spur length (p=0.048), while the outlet view acromial slope tracked standardized anterior acromion thickness (p=0.0067).
  • The 30° caudal tilt view was also the most practical: 96% of films were technically acceptable and 74% showed a grossly visible spur, both the highest of any view.
  • The acromial tilt angle (Aoki) had acceptable reliability at ICC 0.63 but did not correlate with any operative spur measurement, so reliability alone does not make a measurement clinically meaningful.
  • Among these refractory impingement patients, 70% had complete rotator cuff tears at surgery, underscoring that persistent impingement often signals structural cuff damage.
  • Mean operative acromial dimensions were:
    –Anterior projection beyond clavicle 10.0 mm
    –Anterior thickness 12.8 mm
    –Posterior thickness 8.1 mm
    –Dropping to 5.4 mm after acromioplasty.
Board PearlThe 30° caudal tilt view is the most reliable radiograph (ICC 0.84) for assessing the anterior acromial spur in impingement syndrome.

Clinical Relevance

When you order imaging for refractory impingement, the goal is to confirm a bony spur before committing to acromioplasty. This paper tells you which views to trust. The 30° caudal tilt view is the workhorse: it is the easiest to obtain, the most reproducible across readers, and it correlates with the actual three-dimensional spur length. It also lets you confirm adequacy of resection afterward.

The supraspinatus outlet view adds complementary information by capturing anterior acromion thickness and acromial shape, which ties back to the Bigliani flat/curved/hooked classification you need for boards.

The teaching point: don't rely on the axillary view for the spur. Its job is to catch an os acromiale and glenohumeral arthritis. A measurement can be reliable yet clinically meaningless, as the acromial tilt angle demonstrates here.

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