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Changes in Innominate Tilt After Manipulation of the Sacroiliac Joint in Patients with Low Back Pain An Experimental Study MICHAEL T. CIBULKA, ANTHONY DELITTO, and RHONDA M. KOLDEHOFF The purposes of this study were to 1) propose a method to detect sacroiliac joint dysfunction (SIJD), 2) test the interrater reliability of the method on a group of patients with low back pain (LBP), and 3) document changes in innominate tilt after manipulation of the sacroiliac joint. Criteria for SIJD were established by the authors. Twenty-six patients with unilateral LBP were examined independently for presence of SIJD by two examiners. Interrater agreement for presence or absence of SIJD was found to be excellent (Cohen's Kappa = .88). Twenty of the patients who met the criteria for SIJD were randomly assigned to an Experimental Group (n = 10) or a Control Group (n = 10). The left and right innominate bones of these 20 patients were measured for tilt before and after the intervention period. The sacroiliac joint of the patients in the Experimental Group was manip- ulated during the intervention period, whereas the patients in the Control Group received no treatment. Data were analyzed using a mixed three-factor analysis of variance. The data analysis revealed that the manipulation procedure resulted not only in an altered innominate tilt of the same side but also in an equal and opposite tilt of the opposite side (F = 67.07; df = 1,18; p < .05). The results indicate that SIJD can be identified reliably in patients with LBP and that a manipulative procedure purported to be specific to the sacroiliac joint changes innominate tilt bilaterally and in opposite directions. Key Words: Backache; Manipulation, orthopedic; Manual therapy; Sacroiliac joint. Sacroiliac joint dysfunction (SIJD) has been hypothesized to be a common cause of low back pain (LBP).1-3 The presence or absence of SIJD is typically identified by two different palpatory tests, one that reportedly detects reduced movement and the other that identifies malalignment between the left and right innominate bones.4 Accurate detection and subse- quent treatment depend ultimately on the reliability and validity of the tests used to identify SIJD. Individual tests that are commonly used to identify SIJD have been shown to have questionable reliability.5 Reliability is necessary for dependability in a measure. Therefore, the reliability of tests used to detect SIJD must either be improved or abandoned. Two methods that have helped us improve the reliability of SIJD tests in our clinic include 1) discussing sources of disagreements that occur between therapists (eg, training) and 2) combining the results of four different tests used to confirm or deny the presence of SIJD. If these methods can improve the reliability of tests used to detect SIJD, physical therapists may be able to use these methods to identify patients with SIJD. Movement tests are used to detect reduced movement of one sacroiliac joint when compared with the opposite side.4 Palpatory tests are also used to detect malalignment by iden- tifying asymmetry between the left and right innominate bones.3(p56) Four different patterns of malalignment between the innominate bones have been described: 1) unilateral an- terior tilt of one innominate bone,6,7 2) unilateral posterior tilt of one innominate bone,6'7 3) bilateral antagonistic move- ment of the innominate bones (left and right innominate tilt in opposite directions),3(pl9),8 and 4) bilateral anterior tilt of the innominate bones.2 Despite the frequent use of movement tests, no study has been conducted on patients with SIJD to determine whether or how sacroiliac joint movement is altered by treatment. In addition, no study has been published using patients to deter- mine the relationship between the left and right innominate bones in SIJD. The purposes of this study were to 1) propose a method to evaluate the presence of SIJD in patients with LBP using a combination of clinical tests described previ- ously,1,3,4 2) test the interrater reliability of selected tests for SIJD on patients with LBP, and 3) document changes in the tilt of the innominate bones in patients with SIJD after a manipulation procedure commonly used to move the sacro- iliac joint. METHOD The study was conducted in two phases (Fig. 1). Phase 1 involved the establishment of SIJD in the patient population and the assessment of the reliability of the method used to M. Cibulka, MHS, is Physical Therapist, St. Louis Rehabilitation and Sports Clinic, 400 C Truman Blvd, Crystal City, MO 63019 (USA). A. Delitto, MHS, is Instructor, Program in Physical Therapy, Washington University Medical School, and Consulting Physical Therapist, Irene Walter Johnson Rehabilitation Institute, PO Box 8083, 660 S Euclid Ave, St. Louis, MO 63110. R. Koldehoff, BS, is Physical Therapist, St. Louis Rehabilitation and Sports Clinic. This article was submitted September 22, 1987; was with the authors for revision eight weeks; and was accepted March 15, 1988. Potential Conflict of Interest: 4. Volume 68 / Number 9, September 1988 1359 establish the presence or absence of SIJD. Only patients with SIJD were included in Phase 2. Subjects Twenty-six patients referred to our clinic for treatment of LBP of nonspecific origin initially participated in this study. Criteria for exclusion included pregnancy; diagnosis of anky- losing spondylitis; and presence of neurological signs such as anesthesia, absence of deep tendon reflexes, profound muscle weakness, and straight leg raise of less than 45 degrees. In addition, patients were excluded if they exhibited signs and symptoms consistent with symptom magnification as de- scribed by Waddell et al.9 All patients complained of LBP of sufficient degree to seek medical intervention. The pain in all patients was localized to the lumbar area and occasionally to the buttock area. No patient had pain below the knee. Phase 1 Establishing sacroiliac joint dysfunction. After receiving informed consent from all patients, each patient was assessed independently by two examiners (M.T.C. and R.M.K.) for the presence or absence of SIJD. We defined SIJD as being present in a patient if at least three of four tests commonly used to evaluate SIJD were positive. These tests were the standing flexion test, the prone knee flexion test, the supine long sitting test, and palpation of posterior superior iliac spine (PSIS) heights for asymmetry on sitting. Measurement of sacroiliac joint dysfunction. The first clin- ical test used to evaluate the presence or absence of SIJD was the standing flexion test.1,4 The standing flexion test is de- signed to detect abnormal movement in the sacroiliac joints. This test was only used to determine whether a patient had SIJD. In this test, the patient stood with feet 30.5 cm apart. The examiner's (M.T.C. or R.M.K.) thumbs were placed on the inferior slope of the PSISs. The patient was then asked to forward bend slowly and completely. A positive test existed when one of the PSISs moved cranially more than the opposite PSIS. The side that moves more cranially is purported to be the hypomobile side.1,4 The prone knee flexion test was used to assess both abnor- mal movement and malalignment in SIJD.1,4 The prone knee flexion test was performed with the patient positioned prone on a treatment table with the head in the midline position and his shoes on. The therapist stood at the foot of the table and grasped the patient's shoes with the thumbs passing over the heels of the shoes. The shoes were approximated, and the relative lengths of the lower extremities were compared by inspecting the heels of the shoes. The patient's knees were then flexed to 90 degrees, and any change in the length of the lower extremities was noted. A positive test resulted when an observable change occurred between prone leg length and prone knee flexion leg length in either leg. A negative test resulted when no change in lower extremity leg length oc- curred from the prone to the knee-flexed position. If a positive test was found, the patient was also evaluated to determine direction of innominate tilt. A posterior tilt of the innominate bone is characterized by a relative shortening of the lower extremity in the prone-lying position as compared with rela- tive lengthening on knee flexion coupled with a positive standing flexion test on that side. Conversely, an anterior tilt of the innominate bone is characterized by a relative length- ening of the lower extremity in the prone-lying position as REFERRED WITH LOW BACK PAIN PHASE 1 ASSESSED FOR PRESENCE OF SIJD IF NO SLID, EXCLUDED FROM PHASE 2 IF SIJD, ENTER IN PHASE 2 Fig. 1. Diagram of the general flow of the study. Interrater agree- ment of presence or absence of sacroiliac joint dysfunction (SIJD) was assessed in Phase 1. When the examiners were in agreement concerning the presence of SIJD, the patient was assigned to Phase 2 of the study. compared with relative shortening on knee flexion. A positive prone knee flexion test will presumably reflect SIJD.1,4 The supine long sitting test was also used to assess abnormal movement and malalignment in SIJD.1,4 The supine long sitting test was performed with the patient positioned supine. The examiner placed his thumbs under the inferior border of each medial malleolus. The two medial malleoli were then brought together for comparison. The patient sat up with extended knees, and the relative length of the malleoli were reassessed. A positive test was considered to be an observable change in leg length between the two positions. As in the prone knee flexion test, the lengthening or shortening of the left and right side is relative, and a positive test is reflective of SIJD.1,4 Palpation of the patient's PSISs in the sitting position was also performed to help confirm SIJD and to help determine the direction of innominate tilt.3(p56) An inequality of PSISs on sitting is indicative of SIJD.3(p56) The patient sat on a flat surface, and the PSISs were evaluated by placing each thumb under the PSISs and then observing for symmetry. An uneven height of one PSIS as compared with the other PSIS confirmed the presence of SIJD. The side where the PSIS was low, when compared with the opposite side, suggests that the innominate bone was tilted posteriorly.3(p56) Reliability. Intertester reliability was defined by the level of agreement (beyond chance agreement) between the two ex- aminers' independent classifications of patient status. Cohen's Kappa statistic10 was used to assess level of agreement. Phase 2 Of the 26 patients who agreed to participate in Phase 1, 20 (13 male, 7 female) were found to have SIJD after examina- tion by both investigators (M.T.C. and R.M.K.), and were subsequently admitted to Phase 2 of the study. These 20 patients were then randomly and independently assigned to either a Control Group (n = 10) or an Experimental (manip- ulation) Group (n = 10). The mean age of patients who participated in Phase 2 was 26 ± 1 1 years (range = 15-47 years). Measurement of innominate tilt. An inclinometer was as- sembled to measure left and right innominate tilt in degrees (Fig. 2). The instrument was fashioned after the one described by Pitkin and Pheasant.8 Intratester reliability of this device has been shown to be "excellent" when assessed on one day (r =.84).11 1360 PHYSICAL THERAPY RESEARCH Fig. 2. Inclinometer used to measure unilateral innominate tilt. The method for measuring innominate tilt was determined as follows. Two therapists (M.T.C. and R.M.K.) performed the measurements. One measurer (R.M.K.) located and spot- ted the landmarks, and the other physical therapist (M.T.C.) obtained the actual measurement of innominate tilt. The anterior superior iliac spine (ASIS) and the PSIS were located, and a 1.5-cm round marker was placed over the centers of both the ASIS and PSIS. The patient was then asked to stand with knees straight, feet pointing forward and 30.5 cm apart. The investigator then placed one tip of the calipers on the ASIS and the other tip of the calipers on the ipsilateral PSIS and then read the amount of innominate tilt (angle of incli- nation) off the protractor. A zero-degree measurement (a neutral measurement) on the inclinometer denoted that if an imaginary line connected the ASIS and PSIS, the line would be horizontal. Positive degrees were used to describe an an- terior innominate tilt, and negative degrees were used to describe a posterior innominate tilt. Four measurements from each innominate bone were taken both before and after a treatment period. The four measure- ments were averaged to obtain a value used to evaluate the effect of manipulation on innominate tilt. The examiner who obtained the actual measurements was unaware of which patients received the manipulation. Treatment. The patients in the Control Group received no treatment during the treatment period, whereas the sacroiliac joint of patients in the Experimental Group was manipulated on the opposite side of the positive standing flexion test, using a technique described by Stoddard.12 The patient is positioned supine in a side-bent position with the convexity toward the therapist. The patient's upper trunk is rotated toward the therapist, and a posterior force is applied to the contralateral (with reference to the therapist) ASIS. We used this technique because it usually eliminates SIJD in one treatment session. The side to be manipulated was always the side corresponding to the lowest value (most negative) obtained with the calipers. Data Analysis The average measurements of the innominate tilt obtained from each patient were summarized using descriptive statistics and were analyzed with a three-way analysis of variance (ANOVA) using a mixed factorial design (2 x 2 x 2).13 Factor A consisted of the between-groups factor (Control Group vs Experimental Group). Factor B was a repeated-measures fac- tor and consisted of manipulated versus nonmanipulated side of the pelvis. Factor C was a repeated-measures factor and consisted of pretest versus posttest measurements. For signif- icant two- or three-way interactions, further analysis of simple main effects (F-ratio tests) was performed using the same computer program. Results were considered significant at the .05 level. RESULTS Results of the reliability assessment revealed a Cohen's Kappa of .88. Obtaining a Cohen's Kappa this high in a clinical test is considered excellent clinical agreement accord- ing to Feinstein.14 Table 1 summarizes measurements of innominate tilt before and after the treatment period in the Experimental and Control Groups. The ANOVA (Tab. 2) revealed a significant main effect with factor B and a signifi- cant two-way interaction between manipulated and nonma- nipulated sides (factor B) and before and after treatment (factor C). These results, however, are precluded by the sig- nificant three-way (A × B × C) interaction (F = 67.07; df = 1,18; p < .05). The results of the simple main effects analyses show that the manipulative technique, which was always performed on the innominate bone side with the most nega- tive angle with respect to the horizontal plane, changed the TABLE 1 Means and Standard Deviations (in Degrees) of Innominate Bone Measurements in Experimental and Control Groups Before and After Treatment Period Group Control Experimental Side with Most Negative Anglea Pretest Posttest s s -4.0 3.5 -3.2 4.5 -4.9 7.2 1.0 6.6 Side with Least Negative Angle Pretest Posttest s s 7.1 3.4 6.9 3.8 6.3 6.4 1.0 6.6 a Manipulation was always performed on the side with the most negative angle with respect to the horizontal plane. Volume 68 / Number 9, September 1988 1361 TABLE 2 Results of Three-way Analysis of Variance Using a Mixed Factorial Design (2 x 2 x 2) Source Factor Aa Error (A) Factor Bb A x B Error (B) Factor Cd A x C Error (C) B x C A x B x C Error (B x C) df 1 18 1 1 18 1 1 18 1 1 18 SS 14.45 1885.50 1312.20 125.00 230.80 1.80 0.00 9.20 186.05 130.05 34.90 MS 14.45 104.75 1312.20 125.00 12.82 1.80 0.00 0.51 186.05 130.05 1.94 F 0.14 102.34c 9.75c 3.52 0.00 95.96c 67.07c angle of the pelvis on the side to a more positive value (F = 24.46; df = 1,18; p < .05). Concomitant with this change on the manipulated side was an opposite and almost equal change in the innominate tilt of the nonmanipulated side, from a more positive to less positive value (F = 161.74; df = 1,18; p < .05). The differences in pretest and posttest measurements of innominate tilt in the Control Group were not significant. These results are summarized in Figure 3. DISCUSSION Analyzing only one test at a time, Potter and Rothstein have shown a lack of reliability of tests used to measure SIJD.5 Although unreliable measures can lead to high observer vari- ability, it is unlikely that a clinician will base an entire assessment of a patient on one test alone.15 Instead, the clinician depends on a battery of tests to rule out or confirm a clinical diagnosis such as SIJD. We have shown that using predetermined combinations of four of the same tests used individually by Potter and Rothstein5 was reliable between two investigators in diagnosing SIJD as defined in this study. A diagnoses-based combination of many tests increases the specificity of any test.16 In addition, the investigators in this study trained using a prescribed methodology. Perhaps this additional training added to the reliability of these measures. A manipulative technique specific to a unilateral sacroiliac joint created a significant change in innominate tilt bilaterally in all of the patients in the Experimental Group. The results of this study have shown that if the more posteriorly rotated of the innominate bones is manipulated, the inclination of this innominate bone will change in a more positive (anterior) direction concomitant with an opposite change (posterior tilting) of the opposite innominate bone. No change in innom- inate tilt, however, was recorded in 9 of the 10 patients in the Control Group. This result disconfirms the belief that the manipulative technique used in this study is specific only to the side manipulated. This result also confirms the suspicion of an expert in the area of SIJD (Richard E. Erhard, unpub- lished data, May 1987) that the manipulative technique results in a bilateral effect. The movement test (standing flexion test) was only used to confirm or deny the presence of SIJD. We could not find a reliable and valid method of monitoring sacral position and motion. Knowing the position of the sacrum in relation to Fig. 3. Pelvic tilt (in degrees relative to horizontal plane) of side with least negative angle of Control Group (LC), side with least negative angle of Experimental Group (LE), side with most negative angle of Control Group (MC), and side with most negative angle of Experi- mental Group (ME), both before and after treatment. Manipulative technique was always applied to the sacroiliac joint of the side with the most negative angle. both innominate bones would allow the clinician to determine whether the manipulative technique had a bilateral effect on the sacroiliac joints. Future studies are needed of sacroiliac joint movement and its relation to sacral position in patients with SIJD. The relationship between innominate tilt and muscle im- balance leading to LBP has been hypothesized elsewhere.17 The results of this study suggest that treatments designed to primarily affect unilateral inn