Palpate the posterior superior iliac spines (PSISs)

Physical examination procedures involving palpation for positional asymmetry of bony landmarks.


These palpation tests also for joint hypomobility or hypermobility and assesses the difference in muscles and tissue between sides.  Pain is also assessed.


Anatomical landmarks

  • Anterior superior iliac spine (ASIS)
  • The posterior superior iliac spine (PSIS)
  • The iliac crest
  • The sacral sulcus
  • The sacral apex
  • Inferior lateral angle of the sacrum (SILA).



Seated bilateral PSIS palpation Examiner places thumbs on PSISs, assessing for vertical displacement. Inferior PSIS –> posterior innominate rotation; Superior PSIS–>anterior rotation
Prone PSIS identification as anatomical landmark Examiner identifies PSIS in relation to sacrum. Using a PSIS landmark may increase accuracy of numerating lumbar segments
Palpation of PSIS Y-axis unleveling, seated vs. standing, as indicator of anatomic LLI Vertical PSIS displacement seated compared with standing displacement. Any difference in vertical PSIS displacement seated compared with standing displacement suggests anatomical LLI
Sacroiliac motion palpation Seated or standing, examiner observes or palpates for sacroiliac excursion during movement (sitting flexion test8, step test9, etc.) or endfeel with digital pressure. Lack of excursion during active or passive sacroiliac movement indicates restriction; hard end-feel with digital pressure indicates fixation
Pain provocation Digital pressure applied to PSISs. Tenderness of PSIS on palpation indicates sacroiliac dysfunction
PSIS identification to allow sulcus depth determination Thumbs probe relative depth of the sacroiliac joints. Asymmetry indicates inter-innominate sacral base rotation


Reliability studies, PSIS palpation

Author, date Palpatory method (bilateral unless unilateral noted) Examiners/participants (E/P) Reliability (ϰ, % agreement, or other statistic) Quality. score (n/11) Study conclusions
Potter, 1985 Seated and standing, cadual aspect E: 8 PTs
P: 17 buttock pain
%=35.29 seated
%=35.29 standing (interexaminer only)
4 Need for improved methods for SI palpation; PSIS palpation under the conditions of this study was unreliable.
Byfield, 1992 Standing position, aspect of PSIS not specified E: 10 DCs & 10 students
P: 2 patients, clinical status unspecified
“Horizontal spread” for DCs 1.1 (0.7) cm, for students 2.0 (0.1) cm
“Vertical spread” for DCs 1.4 (0.7) cm, for students 4.5 (2.2) cm students
4 The DC’s skin marks for PSIS location were more “concentrated” than students’ marks; DCs were “reasonably” reliable.
Simmonds, 1992 Prone, not further specified E: 20 PTs
P: 20 asymp.
Intraexaminer: mean distance between UV skin marks= 8 ±5 mm
Interexaminer: mean distance between UV skin marks= 20 ±13 mm
5 PSIS palpation was associated with a statistically significant low within-rater but high between-rater error.
Paydar, 1994 Seated, caudal aspect E: 2 DC students
P: 32 asymp.
ϰ=.25 (intraexaminer)
ϰ=.15 (interexaminer)
2 The clinical decision on which sacroiliac joint to treat should not be based on palpatory findings alone.
Lindsay, 1995 Prone, not further specified E: 2 experienced manual therapists
P: 8 skiers (unknown symptom status)
Apparently dichotomous protocol
ϰ= −.10
%=50 (interexaminer only)
3 PSIS palpation failed to meet a predetermined agreement criterion of 70%; sacroiliac very unreliable.
O’Haire, 2000 Prone, caudal aspect E: 10 DO students
P: 10 asymp.
ϰ=.07 to .58, mean .33
%=43–94 (intraexaminer)
ϰ=.04, %=51 (interexaminer only)
6 Only slight inter-examiner reliability; efforts should be made to improve levels of agreement.
Riddle, 2002 Seated E: 34, pairwise
P: 65 pain
%=55.6 (interexaminer only)
5 Pain provocation tests appear to have more support for identifying sacroiliac problems than sacroiliac alignment or movement tests.
Fryer, 2005 Prone, caudal aspect E: 10 final year osteopathic students (5 trained)
P: 10 asymp. female volunteers
ϰ=0.49 untrained, .54 trained (intraexaminer)
ϰ=0.15 untrained; .08 trained
%=53 trained, %=34 untrained (interexaminer)
7 Training did not improve reliability
Kim, 2007 Prone, caudal aspect E: 4, experienced
P: 60 patients
Wilcoxon statistic: mean PSIS delta = .60(.60) mm (interexaminer only) 6 Palpating the PSIS with accuracy might be difficult.
Kimita, 2008 Prone, caudal aspect E: 2 students, 2 experienced DOs
P: 5 symptomatic, 4 asymp.
ϰ= −.29 to 0.39 (intraexaminer)
ϰ= .38 to 0.35 (interexaminer)
10 Inter-examiner reliability was low, irrespective of examiners’ years of experience.
van Kessel-Cobelens, 2008 Seated, caudal aspect E: 2 PTs
P: Total 60
20 Control
22 w/pelvic pain, 20 wks pregnant
20 no pelvic pain, 20 weeks pregnant (interexaminer only)
Total group: ϰ=0.26, %=63
Control: ϰ=0.47, %=75
Pain: ϰ=.20, %=60
Non-pain: ϰ=0.10, %=55
7 Poor interexaminer reliability for palpation, should not be used for diagnostic purposes.
Sutton, 2012 Standing, caudal aspect, unilateral E: 15 final year osteopathy students, 15 3rd year, 10 exp. osteopaths
P: 1 asymp. model; 5mm wedge inserted 2/3 trials (interexaminer only)
3rd year students ϰ=.025; 4th year ϰ=.065; DOs ϰ=.058; all combined ϰ=.063 6 Inter-reliability of palpation to locate PSISs and assess levels is poor in both students and experienced osteopaths.
Suwanasri, 2014 Standing, aspect unspecified E: PTs, number unclear
P: 10 PT students
ϰ<.40 2 Inter-reliability of palpation to locate PSISs is poor.

Abbreviations: DO=Osteopath, DC=Chiropractor, PT=Physiotherapist, E=Examiner, P=Patient, ϰ=Kappa, mm=millimeter, asymp.= asymptomatic patient

This study was conducted with no funding beyond the internal support provided by Palmer West and Life West Chiropractic Colleges


There is little evidence at this time in support claims that palpatory procedures can detect subtle misalignments with regard to PSIS palpation.


Other Studies

Interexaminer Reliability and Accuracy of Posterior Superior Iliac Spine and Iliac Crest Palpation for Spinal Level Estimations

Hye Won Kim, Young Jin Ko, Won Ihl Rhee, Jung Soo Lee, Ji Eun Lim, Sang Jee Lee, Sun Im and Jong In Lee

The purpose of this study was to compare the posterior superior iliac spine (PSIS) and the iliac crest as accurate anatomical landmarks for identifying spinal level.  This study was conducted in 2 stages, firstly examiners examined 60 patients and blindly identified iliac crest and PSIS levels, secondly, examiners attached a radio opaque marker at presumed PSIS and iliac crest levels in 72 patients  which was then cross checked with radiographic identification.  The interexaminer reliability of palpation was significantly greater for PSIS level than for the iliac crest. Spinal levels of estimated PSISs identified by palpation ranged from the L5-S1 interspace to the S2 spinous process, and the spinal levels of estimated iliac crest ranged from the L2-3 interspace to the L5 spinous process.  Although PSIS palpation showed statistically higher interexaminer reliability than iliac crest level, clinicians should be cautious when applying this method as a measurement tool because estimated spinal level by palpation can be influenced inadvertently by examiner skill and anatomical variations.

Journal of Manipulative and Physiological Therapeutics, 2007, 30(5), 386-389