In my last post, I discussed how using a cluster of signs and symptoms can significantly improve our diagnostic accuracy for differentiating issues in the neck and upper extremity. Moving down the kinetic chain, there are other regions of the body in which cluster diagnoses have been identified. In this month’s post, I want to highlight how a cluster of tests can help us differentiate pain at the sacroiliac (SI) joint as well as identify if arthritis is occurring within the knee.
In 2005, Laslett et al. wrote an article which redefined a way which many of us examine the SI joint. His article examined the validity of movement and provocation testing and demonstrated that the best way in which we can differentiate pain in this joint, from other surrounding joints, is through a cluster of tests which provoke pain. Provocation tests, which have been around for a couple of decades, appear to be our best way of discriminating an issue occurring in this region. Palpatory tests (such as iliac crest height, standing and seated flexion, and long sitting) suffer from very low agreement in terms of validity and inter-rater reliability and clinical use, according to the literature, is questionable.
Proposed provocation tests that appear to hold clinical value include the distraction, compression, thigh thrust, Gaenslen’s (right and left) and sacral thrust test. Alone, these tests tell us little but 2 out of 4 positive provocation tests (distraction, compression, thigh thrust or sacral thrust) demonstrate a sensitivity of .88 , specificity of .78, positive likelihood ratio (LR) of 4.00 and negative LR of .16 for SI joint pathology. 3 out of all 6 provocation tests have a sensitivity of .94, specificity of .78, positive LR of 4.29 and negative LR of .80 for SI joint pathology ( the reference standard for determining if there is truly dysfunction at this joint is pain relief after an intra-articular injection). Other authors have reexamined Laslett’s results and a systematic review in 2009 confirmed that a cluster of provocation tests has discriminative power. Before using this cluster of tests, it is expert opinion that one clears the lumbar spine and hip for other contributing pathology.
Distraction Test: The patient is supine the examiner applies pressure to “spread” the ASISs.
Compression Test: The patient is in sidelying. The tester is behind the patient with both hands applying a downward pressure through the anterior portion of the ilum, spreading the SIJ.
Thigh Thrust Test: The patient is supine and the hip is flexed to 90 degrees with the knee bent. The tester then applies a posterior shearing force to the SIJ through the femur. Avoid excessively adducting during this exam.
Gaenslen’s Test: The patient is lying supine near the side of table. The examiner stands on the side of the patient and places the patient’s leg closest to them off the edge of the table. The examiner then instructs the patients to actively flex the opposite leg to their chest and hold. The examiner then applies pressure to the leg hanging off of the edge of table, forcing it into extension.
Sacral Thrust: The patient is prone and the examiner applies an anterior pressure through the sacrum.
In addition to the cluster testing for SI joint dysfunction, a 2010 article in the Annals of Rheumatic Disorders attempted to develop evidence-based recommendations for the clinical diagnosis of knee osteoarthritis. It has been stated that 25% of individuals over the age of 55 suffer from knee pain. Out of these individuals, about half have been shown to have OA changes on radiograph and a fourth are disabled because of it. Because of this prevalence, these examiners wanted to determine a quick algorithm to use to diagnose knee OA.
The examiners of this study used a Delphi consensus approach and analyzed recommendations given by experts in 12 European countries as compared to a systematic review of available literature. They then calculated the diagnostic accuracy for the answers given by the experts to formulate a mathematical probability for someone having knee OA. They found that when three specific signs and three specific symptoms were present, the probability of someone over the age of 45 having OA was 99%. The three signs include: crepitus, restricted movement, bony enlargement and three symptoms include: persistant knee pain, limited morning stiffness and reduced function. It is proposed that clinical assessment alone, looking at these six variables, can provide a confident rule-in diagnosis.
Overall, literature is indicting that a multitude of tests used together, is the best method in forming a clinical diagnosis. In next months blog, I plan on highlighting a topic I discussed early this year: pain.