Recurrent Piriformis Syndrome after Surgical Release

Editorial Review

Recurrent Piriformis Syndrome after Surgical Release

Philipp Kobbe MD, Boris A Zelle MD, Gary S Gruen MD

Published online February 9th 2008

The Association of Bone and Joint Surgeons 2008

JACO Editorial Previewer: J. Christopher Romney DC FACO

Published: September 2017

Journal of the Academy of Chiropractic Orthopedists

September 2017, Volume 14, Issue 3

The original article copyright belongs to the original publisher. This review is available from: © 2017 Romney and the Academy of Chiropractic Orthopedists. This is an Open Access article which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Authors’ Abstract:

Objective: To establish, in patients with subacromial impingement syndrome, the relationship between pain and shoulder function, as determined by the Constant score, and morphological findings, as determined by radiographs and magnetic resonance imaging (MRI) and the relationship between acromial shape and minimum acromiohumeral distance (AHD).

Design: Cross-sectional study.

Setting: Tertiary care center.

Patients: Forty-seven patients (33 males and 14 females; mean age, 51.7 years) with unilateral subacromial impingement syndrome who had failed to respond to conservative therapy for at least 6 months.

Interventions: The Constant score was determined preoperatively; acromial shape (type I, flat; type II, curved; and type III, hooked) was evaluated on preoperative outlet view radiographs and oblique sagittal T1-weighted MRIs; AHD was evaluated on preoperative anteroposterior radiographs and oblique coronal T1-weighted MRIs.

Main Outcome Measures: Correlation coefficients and the simple kappa statistic were calculated. Student t test and mean differences with 95% confidence limits were reported for group comparisons.

Results: The Constant score was fairly correlated with AHD (r = 0.39, P , 0.01) but not with acromial shape. Patients with an AHD 7 mm or less on MRI scored significantly lower than those with an AHD more than 7 (mean difference, 18.5; P, 0.01). Acromial shape and AHD were not correlated on radiographs or MRI.

Conclusions: AHD seems to better reflect the clinical status of patients with subacromial impingement, but without rotator cuff tears, than acromial shape. Acromial shape is not a good descriptor of subacromial space narrowing.

JACO Editorial Summary:

  • The article was written by authors from the Department of Radiology, Medical University of Vienna, Vienna, Austria; Institute of Radiology, Waldviertelklinikum Horn, Horn, Austria; Second Orthopedic Department, Orthopaedic Hospital Speising, Vienna, Austria; and Department of Orthopaedic Surgery, Great Ormond Street Hospital for Children, Institute of Child Health, University College London, London, UK.
  • The purpose of this cross-sectional study was to evaluate the correlation between imaged shoulder morphology and shoulder function as measured by the Constant score.
  • The Constant score is a validated assessment instrument that measures should function across four domains that include pain, activities of daily living, shoulder ROM, and muscle strength. The instrument uses a 100 point scale with a higher score reflecting better function and lower pain.
  • Forty seven patients with subacromial impingement syndrome received radiographs and MRI’s to assess acromion morphology and acromiohumeral distance (AHD).
  • Acromial morphology was assessed by imaging as Type 1, 2 or 3 as described by Bigliani, Epstien et al.
  • Acromiohumeral distance was assessed by MRI and radiographic imaging. An AHD of 7 mm or less is considered abnormal.
  • The Constant score correlated fairly with AHD but not with acromial shape.
  • Patients with an AHD 7 mm or less on MRI had a significantly lower Constant score than those with an AHD greater than 7.
  • Acromial shape and AHD were correlated, neither on radiographs nor on MRI.


The results of this investigation suggest that assessment and reporting of acromiohumeral distance (AHD) is to be preferred to morphology assessment in that it correlates better with functional assessment of the shoulder.