Low Back Pain in Microgravity and Bed Rest Studies.

BACKGROUND: The prevalence of low back pain (LBP) for astronauts in space (68%) is higher than the 1-mo prevalence for the general population on Earth (39%). It is unclear whether differences occur between healthy subjects and astronauts with a history of LBP. Knowledge of this issue is important to assess whether a history of LBP could have an operational impact. METHODS: We evaluated LBP prospectively during short duration spaceflight (15 d; N=20) and compared this with similar data collected during two bed rest studies (N=40). Astronauts completed a questionnaire 5-10 d preflight, during each flight day, and 5-10 d postflight. RESULTS: All astronauts with a history of LBP also developed LBP in flight. These astronauts reported a significantly longer duration of LBP and a different pain location. LBP was most often experienced in the central area of the lower back during spaceflight with an incidence of 70% and a mean pain level of 3 (on a scale of 0-10). Pain resolved within 10 d of flight. No neurological signs were present. The most frequently reported countermeasure was assuming a "knees to chest (fetal tuck) position" combined with stretching. Greater LBP intensity was reported in spaceflight than bed rest with a trend indicating a greater number of days of pain during spaceflight. DISCUSSION: The current study represents a prospective study of LBP in spaceflight. The results indicate that LBP is self-limiting in spaceflight and should not pose an operational risk. Prior LBP on Earth appears to be a risk factor for LBP in spaceflight.

The potential effects of a biofeedback writing exercise on radial artery blood flow and neck mobility.

BACKGROUND: It has been suggested that sustained contraction of the deep neck muscles may reduce axial cervical range of motion (CROM) and radial artery blood flow velocity (vrad.art.mean). No studies have reported both phenomena in relation to acute hand, shoulder or neck trauma. PROCEDURES: The CROM and vrad.art.mean were measured in 20 police officers prior to and immediately after a 2-hours drive on a motorcycle and immediately after a 1-minute writing exercise using biofeedback. The CROM was measured using separate inclinometers and the vrad.art.mean was measured in both arms just proximal to the wrist using echo-Doppler. FINDINGS: During the study, one officer had a motorcycle accident resulting in acute symptoms of neck trauma. His vrad.art.mean was acutely reduced by 73% (right arm) and 45% (left arm). Writing with biofeedback increased his vrad.art.mean by 150% (right arm) and 80% (left arm). In the remaining 19 officers, the CROM to the right was significantly increased after the 2-hours driving task (p<0.05; paired subject t-test). Writing with biofeedback increased their CROM in both directions and vrad.art.mean in both arms (p<001). CONCLUSIONS: A 2-hours drive showed modest physical changes in the upper extremities. Biofeedback in writing tasks might relate to the influence of relaxation and diverting attention for neck mobility and arterial blood flow improvement.

Pregnancy-related pelvic girdle pain: intertester reliability of 3 tests to determine asymmetric mobility of the sacroiliac joints.

OBJECTIVE: Several tests have been developed to determine the extent of sacroiliac asymmetry during pregnancy-related pelvic girdle pain (PGP). This blinded control study investigated the intertester reliability of 3 such tests used in PGP. METHODS: A total of 62 women (ages 20-40 years) were recruited from regional obstetric practices and subsequently divided into 3 groups: (1) 20 women without PGP who were pregnant for more than 20 weeks, (2) 22 women with PGP who were pregnant for more than 20 weeks, and (3) a control group of 20 women who were not pregnant and had no back pain or PGP. All tests were performed by 2 physiotherapists independently of each other and blinded to each other's results. The 3 tests were the thumb-posterior superior iliac spines test, the heel-bank test, and the abduction test. RESULTS: To determine the level of agreement between the 2 testers, kappa values were calculated. The overall kappa is 0.30 (range, -0.22 to 0.83), which is considered as a poor agreement. The percentage agreement per test/category ranged from 45% to 95%. CONCLUSION: This study of 3 tests used to determine asymmetry of the sacroiliac joints in women with pregnancy-related PGP showed them to have a poor intertester reliability.

Effects of slouching and muscle contraction on the strain of the iliolumbar ligament.

The study consisted of biomechanical modelling and in vitro experiments. The objective of the study was to find a mechanical cause of acute low back pain (LBP) in everyday situations. The precise mechanism producing LBP is still under discussion. Most biomechanical studies link the concepts of stooped postures and buckling instability of the spine under high compressive load. No biomechanical model addresses situations with small or neglectable compressive spinal load. The proposed conceptual model describes strain on the iliolumbar ligaments (ILs) when slouching from standing upright. Delayed or absent recruitment of back muscles that protect against hyperkyphosis of the lumbar spine is a conditional factor. Erector spinae and multifidus muscle forces are included, representing a bifurcation in back muscle force: one part acting on the iliac bones and one part acting on the sacrum. The multifidus muscle action on the sacrum may produce nutation which can be counteracted by pelvic floor muscles, which would link back problems and pelvic floor problems. The effect of simulated muscle tension on the ILs and the L5-S1 intervertebral disc angle was measured using embalmed specimens. Forces were applied to simulate erector spinae and sacral part of multifidus tension, bilateral up to 100 N each. Strain gauge sensors registered elongation of the ILs. Explorative biomechanical model calculations show that dynamic slouching, driven by upper body weight and (as an example) rectus abdominis muscle force may produce failure load of the spinal column and the ILs. The quasi-static test on embalmed specimens showed a significant increase of IL elongation with simulated rectus abdominis muscle force. Adding erector spinae or multifidus muscle tension eased the ILs. Sudden slouching of the upright trunk may create failure risk for the spine and ILs. This loading mode may be prevented by controlling loss of lumbar lordosis with erector spinae and multifidus muscle force.

External fixation of the pelvic ring: an experimental study on the role of pin diameter, pin position, and parasymphyseal fixator pins.

BACKGROUND: The mechanical properties of current external fixator systems for unstable (type C) pelvic ring fractures are inferior to internal fixation, and are not optimal for definitive treatment. We explored methods to increase stability of external fixator constructs. METHODS: An experimental model was used for load tests. The same pelvic fixator was used while different pin diameters, pin positions, and modes of pubic symphysis fixation were tested. RESULTS: Changing of the pin diameter of the unthreaded part from 6 to 8 mm resulted in an increase in stiffness of 20%. An increase in stiffness by a factor of 1.9 was found by placing a pin on the iliac crest and one supra-acetabular. An additional increase by a factor of 3.6 was obtained by adding pubic symphysis plate fixation. Parasymphyseal pin fixation instead reduced stiffness, but not so much as when parasymphyseal pins were connected to the external fixator of the pelvic ring. The final configuration was at least 6 times stiffer than the initial configuration. INTERPRETATION: The new concept of parasymphyseal pin fixation connected to an external fixator of the pelvic ring produces a considerable increase in stability for the treatment of type C pelvic ring injuries, as does an increase in pin diameter and alternative pin positioning.

Creep behavior of commonly used suture materials in abdominal wall surgery.

BACKGROUND: The incidence of incisional hernia after abdominal wall closure is high. Furthermore, recurrence is a significant complication after correction of all abdominal wall hernias. Besides surgeon- and patient-related factors, in this experimental study a third factor, i.e., creep behavior of suture materials, is introduced and evaluated. MATERIALS AND METHODS: Creep measurements were performed on 0 and 2-0 Prolene (Ethicon, Johnson & Johnson Intl., Somerville, NJ) and 1 and 2-0 PDSII (Ethicon, Johnson & Johnson Intl.) sutures. Two different loads were used representing normal intra-abdominal pressure (IAP) and pathological IAP. A mean percentage of elongation was calculated for each type of suture material. Statistical analysis was performed using analysis of variance. RESULTS: All suture materials showed significant (3-51%) creep behavior. Prolene sutures showed more creep than PDSII sutures in both loading conditions. CONCLUSIONS: As significant creep was demonstrated for commonly used suture materials, creep might be a significant influential factor with regard to the etiology of incisional hernias and recurrence after abdominal wall hernia repair.

Prediction of torsional failure in 22 cadaver femora with and without simulated subtrochanteric metastatic defects: a CT scan-based finite element analysis.

BACKGROUND: In metastatic bone disease, prophylactic fixation of impending long bone fracture is preferred over surgical treatment of a manifest fracture. There are no reliable guidelines for prediction of pathological fracture risk, however. We aimed to determine whether finite element (FE) models constructed from quantitative CT scans could be used for predicting pathological fracture load and location in a cadaver model of metastatic bone disease. MATERIAL AND METHODS: Subject-specific FE models were constructed from quantitative CT scans of 11 pairs of human femora. To simulate a metastatic defect, a transcortical hole was made in the subtrochanteric region in one femur of each pair. All femora were experimentally loaded in torsion until fracture. FE simulations of the experimental set-up were performed and torsional stiffness and strain energy density (SED) distribution were determined. RESULTS: In 15 of the 22 cases, locations of maximal SED fitted with the actual fracture locations. The calculated torsional stiffness of the entire femur combined with a criterion based on the local SED distribution in the FE model predicted 82% of the variance of the experimental torsional failure load. INTERPRETATION: In the future, CT scan-based FE analysis may provide a useful tool for identification of impending pathological fractures requiring prophylactic stabilization.

Glenohumeral elevation-dependent influence of anterior glenohumeral capsular lesions on passive axial humeral rotation.

The purpose of this study was to assess the effect of standardized anterior glenohumeral capsular lesions on axial humeral rotation in a full arc of glenohumeral elevation. Using a testing apparatus, the range of internal and external humeral rotation was assessed in an arc of glenohumeral elevation in the scapular plane with steps of 15 degrees in six isolated shoulder joint specimens. Cutting of the glenohumeral joint capsule 1 cm laterally from, and parallel to the glenoid rim was performed in seven steps of 1 cm till the anterior capsule was cut. Capsular lesions were made in three ways: from inferior, from superior and from the middle of the capsule. Anterior capsular lesions resulted in significant increase of external humeral rotation. This occurred particularly at 15-60 degrees glenohumeral elevation. Lesions of the inferior part of the capsule mainly increased external rotation at 30-60 degrees glenohumeral elevation, lesions of the superior part mainly in lower elevation angles and lesions of the middle more gradually in the range till 60 degrees of glenohumeral elevation. Cutting of the anterior glenohumeral capsule barely increased passive axial humeral rotation at elevation angles over 60 degrees. Above 60 degrees glenohumeral elevation, tightening of the inferior posterior glenohumeral joint capsule prevented both internal and, increasingly, external humeral rotation. From these observations it is concluded that increased external rotation correlates with progressive anterior capsular lesions, mainly below 60 degrees glenohumeral elevation. To assess anterior glenohumeral capsular lesions in patients, axial humeral rotation tests should probably not exceed 60 degrees glenohumeral elevation, i.e. 90 degrees thoracohumeral elevation.

The mechanical effect of a pelvic belt in patients with pregnancy-related pelvic pain.

BACKGROUND: Many patients with pregnancy-related pelvic girdle pain experience relief of pain when using a pelvic belt, which makes its use a common part of the therapy, but there is no in vivo proof of the mechanical effect of the application of a pelvic belt. METHODS: The influence of a pelvic belt on sacroiliac joint laxity values was tested in 25 subjects with pregnancy-related pelvic girdle pain by means of Doppler imaging of vibrations in prone position with and without the application of a pelvic belt. The belt was adjusted just below the anterior superior iliac spines (high position) and at the level of the pubic symphysis (low position). FINDINGS: Sacroiliac joint laxity values decreased significantly during both applications of a pelvic belt (P<0.001). The application of a pelvic belt in high position decreased sacroiliac joint laxity to a significantly greater degree than the application of a belt in low position (P=0.006). The decrease of laxity significantly correlated with the decrease of the score on the active straight leg raise test (r=0.57 for the low position, P=0.003 and r=0.54 for the high position, P=0.005). INTERPRETATION: Application of a pelvic belt significantly decreases mobility of the sacroiliac joints. The decrease of mobility is larger with the belt positioned just caudal to the anterior superior iliac spines than at the level of the pubic symphysis. The findings are in line with the biomechanical predictions and might be the basis for clinical studies about the use of pelvic belts in pregnancy-related pelvic girdle pain.

Functional aspects of cross-legged sitting with special attention to piriformis muscles and sacroiliac joints.

BACKGROUND: Transversely oriented pelvic muscles such as the internal abdominal oblique, transversus abdominis, piriformis and pelvic floor muscles may contribute to sacroiliac joint stability by pressing the sacrum between the hipbones. Surface electromyographic measurements showed that leg crossing lowers the activity of the internal oblique abdominal muscle significantly. This suggests that leg crossing is a substitute for abdominal muscle activity. No previous studies addressed piriformis muscle and related pelvic structures in cross-legged sitting. METHODS: Angles of pelvis and femur were measured in healthy subjects in standing, normal sitting and cross-legged sitting, and were used to simulate these postures on embalmed pelvises and measure piriformis muscle elongation. Deformations of pelvic ring and iliolumbar ligament caused by piriformis muscle force were measured on embalmed pelvises. FINDINGS: Cross-legged sitting resulted in a relative elongation of the piriformis muscle of 11.7% compared to normal sitting and even 21.4% compared to standing. Application of piriformis muscle force resulted in inward deformation of the pelvic ring and compression of the sacroiliac joints and the dorsal side of the pubic symphysis. INTERPRETATION: Cross-legged sitting is common. We believe that it contributes to sacroiliac joint stability. This study demonstrates the influence of the piriformis muscle on sacroiliac joint compression. The elongation of the piriformis muscle bilaterally by crossing the legs may be functional in the build-up of active or passive tension between sacrum and femur.

Relations between pregnancy-related low back pain, pelvic floor activity and pelvic floor dysfunction.

To assess the occurrence of pelvic floor dysfunction (PFD) in pregnancy- related low back and pelvic pain (PLBP) patients, a cross-sectional study was performed, comprising 77 subjects. Each subject underwent physical assessment, and filled in the Urogenital Distress Inventory completed with gynaecological questions. Differences in the presence of PFD between PLBP patients and healthy controls as well as differences in pelvic floor muscle activity were tested for significance. Interaction by age and vaginal delivery were tested. PFD occurred in 52% of all PLBP patients, significantly more than in the healthy control group. In PLBP patients a significantly increased activity of the pelvic floor muscles could be demonstrated with respect to healthy controls. The occurrence of PFD and PLBP was influenced by a confounding effect of age. Clinicians should be aware of the relation between PLBP and PFD and hence address both problems at the same time.

The influence of slouching and lumbar support on iliolumbar ligaments, intervertebral discs and sacroiliac joints.

OBJECTIVE: To investigate lumbopelvic kinematics when moving into a slouch. DESIGN: A biomechanical model was developed. Load tests in vitro verified the model. BACKGROUND: The precise mechanism causing disc herniation and back sprain is still debated. Most biomechanical studies have focused on lifting in a stooped posture. Previous studies address instability situations due to Euler buckling of the spine under axial load. However, no studies address lumbosacral, iliolumbar and sacroiliac kinematics in slouching, i.e. flexing the spine in situations with negligible compressive spinal load. METHODS: Modeling started with the click-clack movement, i.e. the transition from lumbar lordosis to lumbar kyphosis by the combination of backward rotation of the pelvis and ventral flexion of the spine. The flexed spine was compared with a crowbar which uses the iliolumbar ligaments as fulcrum and pivot. To analyse the click-clack movement in sitting, unembalmed erect human trunks were moved from a forward position to a backward position, recording angular changes between L5, sacrum and ilium. RESULTS: When moving the trunk stepwise backward with support at shoulder level, L5 showed forward rotation with respect to the sacrum, but rotation of the sacrum with respect to the iliac bones was reversed (i.e. counternutation). L5 showed displacement in ventral direction with respect to the ilium. Measurements were in agreement with prediction from the crowbar model of the spine. CONCLUSIONS: Backward rotation of the pelvis combined with flexion of the spine, i.e. slouching, results in backward rotation of the sacrum with respect to the ilium, dorsal widening of the intervertebral disc L5-S1 and strain on the iliolumbar ligaments when protection from back muscles against lumbar flexion is absent. Lumbar backrest support almost eliminates lumbosacral and sacroiliac movement. RELEVANCE: Understanding why the iliolumbar ligaments are loaded in slouching contributes to the understanding of the biomechanics of low back pain in everyday situations with small or negligible compressive spinal load. The results recommend lumbar support: backrests with free shoulder space.

Critical notes on the technique of Doppler imaging of vibrations (DIV).

Buyruk et al. (1995a) have developed a noninvasive technique, Doppler imaging of vibrations (DIV), to measure objectively the laxity of the sacroiliac (SI) joints. The purpose of the present article was to review this technique. Therefore, all the articles about DIV were carefully studied. The reliability of the technique has been determined by the generalisability theory and seems to be good. The technique has also proven its clinical relevance. However, a thorough study into the validity of the technique is still missing. Such study is considered necessary because relevant assumptions in DIV appear generally not to be correct. Conclusions from the measurements with DIV so far should be drawn with great care.

Triple pelvic ring fixation in patients with severe pregnancy-related low back and pelvic pain.

STUDY DESIGN: Single-group prospective follow-up study. OBJECTIVES: To assess the functional outcome of internal fixation of the pelvic ring in patients with severe pregnancy-related low back and pelvic pain (PLBP) in whom all other treatments failed. BACKGROUND DATA: More than half of all pregnant women experience PLBP. In most cases, the pain disappears after childbirth. In some, however, the pain becomes chronic and patients may be wheelchair-bound or bedridden. After failure of all conservative treatment, surgical fixation of the pelvic ring seems to be the only remaining option for those severe cases. MATERIALS AND METHODS: The postsurgical functional outcome of 58 severe PLBP patients was evaluated with the Majeed score and endurance of walking, sitting, and standing. Inclusion criteria were serious disability and failure of all conservative treatment. The surgical technique consisted of a symphysiodesis and bilateral percutaneous placement of two sacroiliac screws under fluoroscopic guidance. RESULTS: With a follow-up of an average of 2.1 years, the difference between preoperative and postoperative Majeed score indicated that an improvement of more than 10 points was achieved in 69.8% and 89.3% of the patients at 12 and 24 months, respectively. The most important complications were irritation of nerve roots (8.6%), nonunion of the symphysis (15.5%), failure of the symphyseal plate (3.4%), and pulmonary embolism (1.7%). CONCLUSIONS: In this preliminary study, surgical fixation of the pelvic ring yielded satisfactory results in severe PLBP patients in terms of pain relief and improvement in ADL functions. These results should be confirmed in a randomized clinical trial.

External fixators for pelvic fractures: comparison of the stiffness of current systems.

We evaluated the stiffness of external fixation (EF) systems with a reproducible, standardized human pelvic replica of aluminum and perspex in which a type C pelvic ring injury was created. 12 EF systems were analyzed in 2 situations that necessarily occur during a walking cycle. Endpoints were defined as 15 mm of dislocation or tolerance of the maximum load in each situation. In the no weightbearing situation, all except 2 fixators failed; in the weightbearing situation, all fixators failed. Single bar systems performed better than frame configurations. Stability provided by any external fixator is low, and in the case of a type C pelvic ring injury, it is insufficient for patient mobilization and weightbearing. Single bar systems provide more stability than frames.

The prognostic value of asymmetric laxity of the sacroiliac joints in pregnancy-related pelvic pain.

STUDY DESIGN: Prospective cohort study. OBJECTIVE: To determine the prognostic value of asymmetric laxity of the sacroiliac joints during pregnancy on pregnancy-related pelvic pain postpartum. SUMMARY OF BACKGROUND DATA: In a previous study, we observed a significant relation between asymmetric laxity of the sacroiliac joints and moderate to severe pregnancy-related pelvic pain during pregnancy. METHODS: A group of 123 women were prospectively questioned and examined, and sacroiliac joint laxity was measured by means of Doppler imaging of vibrations at 36 weeks' gestation and at 8 weeks' postpartum. A left to right difference in sacroiliac joint laxity >or=3 threshold units was considered to indicate asymmetric laxity of the sacroiliac joints. RESULTS: In subjects with moderate to severe pregnancy-related pelvic pain during pregnancy, sacroiliac joint asymmetric laxity was predictive of moderate to severe pregnancy-related pelvic pain persisting into the postpartum period in 77% of the subjects. The sensitivity, specificity, and positive predictive value of sacroiliac joint asymmetric laxity during pregnancy for pregnancy-related pelvic pain persisting postpartum were 65%, 83%, and 77%, respectively. Subjects with moderate to severe pregnancy-related pelvic pain and asymmetric laxity of the sacroiliac joints during pregnancy have a threefold higher risk of moderate to severe pregnancy-related pelvic pain postpartum than subjects with symmetric laxity. CONCLUSION: These data indicate that in women with moderate to severe complaints of pelvic pain during pregnancy, sacroiliac joint asymmetric laxity measured during pregnancy is predictive of the persistence of moderate to severe pregnancy-related pelvic pain into the postpartum period.

Does a pelvic belt influence sacroiliac joint laxity?

OBJECTIVE: To evaluate the influence of different positions and tensions of a pelvic belt on sacroiliac joint laxity in healthy young women. BACKGROUND: Clinical experience has shown that positive effects can be obtained with different positions and tensions of a pelvic belt. A functional approach to the treatment of the unstable pelvic girdle requires an understanding of the effect of a pelvic belt on a normal pelvic girdle. METHODS: Sacroiliac joint laxity was assessed with Doppler imaging of vibrations. The influence of two different positions (low: at the level of the symphysis and high: just below the anterior superior iliac spines) and tensions (50 and 100 N) of a pelvic belt was measured in ten healthy subjects, in the prone position. Data were analysed using repeated measures analysis of variance. RESULTS: Tension does not have a significant influence on the amount by which sacroiliac joint laxity with belt differs from sacroiliac joint laxity without belt. A significant effect was found for the position of the pelvic belt. Mean sacroiliac joint laxity value was 2.2 (SD, 0.2) threshold units nearer to the without-belt values when the belt was applied in low position as compared to the case with the belt in high position. CONCLUSIONS: A pelvic belt is most effective in a high position, while a tension of 100 N does not reduce laxity more than 50 N. RELEVANCE: Information about the biomechanical effects of a pelvic belt provided by this study will contribute to a better understanding of the treatment of women with pregnancy-related pelvic pain.

Reliability and validity of hip adduction strength to measure disease severity in posterior pelvic pain since pregnancy.

STUDY DESIGN: A cross-sectional analysis was performed in patients with posterior pelvic pain since pregnancy (PPPP). The strength of adduction of the hips was measured and compared with the scores of commonly used disease severity measures of lumbopelvic pain. OBJECTIVES: To assess the reliability and validity of using hip adduction strength as measure of disease severity in patients with PPPP. SUMMARY OF BACKGROUND DATA: Various tools are used to measure disease severity in PPPP; there is still a need for simple tests with high reliability and validity. METHODS: Intra- and intertester reliability of hip adduction strength measurement was assessed in two small groups of women with PPPP. Validity of hip adduction strength to measure disease severity was investigated in a group of 200 patients with PPPP by comparing the test scores with the medical history, scores on self-reported scales on disability, pain, and tiredness, pain provocation tests, and the active straight leg raise test. Responsiveness of hip adduction strength was assessed in a group of 75 patients with PPPP. Global impression of improvement, scored by the patient, was used as criterion standard. The responsiveness of the hip adduction strength was expressed as the standardized response mean and was compared with the responsiveness of the Quebec Back Pain Disability Scale. RESULTS: The intratester reliability for measuring hip adduction strength and the intraclass correlation coefficient were both 0.79. The intertester reliability for measurement of adduction strength and the intraclass correlation coefficient were also both 0.79. Hip adduction strength correlated as expected with all disease severity measures. Responsiveness of the hip adduction strength was large (standardized response mean = 0.93) and slightly less than that of the Quebec Back Pain Disability Scale (standardized response mean = 1.20). CONCLUSION: Hip adduction strength can be recommended to measure disease severity in PPPP, especially to describe groups of patients and to evaluate the course of the disease in groups as well as in individual patients. Decreased hip adduction strength appears to be caused by the inability to use the hip muscles rather than by weakness of the muscles.

Reliability of sacroiliac joint laxity measurement with Doppler imaging of vibrations.

We developed a noninvasive technique, referred to as Doppler imaging of vibrations (DIV), to measure laxity of the sacroiliac joint (SIJ). The purpose of this study was to examine the reliability of SIJ laxity measurements. A total of 10 healthy women (mean 29.6 +/- 6 years old) participated in the study. At both sides, SIJ laxity was measured with DIV in threshold units (TU). Reliability and measurement error were assessed from repeated measurements by five testers on two occasions as well as by one experienced tester. Intraclass correlation coefficients ranged from 0.53 to 0.80 for all five testers, and from 0.75 to 0.89 for the one experienced tester. Only changes larger than 1.94 to 3.60 TU (any tester) or 1.45 to 2.38 TU (experienced tester) could be confidently detected. DIV is a reliable technique for SIJ laxity measurements in healthy subjects, when performed by an experienced tester.

Responsiveness of outcome measurements in rehabilitation of patients with posterior pelvic pain since pregnancy.

STUDY DESIGN: A cohort study was conducted. OBJECTIVE: To develop a test battery for evaluating the course of posterior pelvic pain since pregnancy. SUMMARY OF BACKGROUND DATA: Properly validated scales to evaluate the course of posterior pelvic pain since pregnancy are scarce. Moreover, the use of many tests would be too strenuous for the patient and has an unfavorable cost-benefit ratio. METHODS: The ability of 48 effect measures to detect clinically relevant changes over time (responsiveness) was tested in patients with posterior pelvic pain since pregnancy. In this test, 35 measures were evaluated in a group of 44 patients, and 16 measures in a group of 56 patients (three measures were evaluated in both groups). All the tests were performed at baseline and after 8 weeks treatment. A global impression of improvement (improved or not improved) scored by the patient was used as the standard for assessing the course of the disease. Responsiveness was examined by calculating the standardized response mean of the improved patients and by using a two-tailed Mann-Whitney nonparametric test to compare the patients who had improved and those who had not improved. RESULTS: Of the 48 effect measures, 26 measures of five categories (activities of daily living, pain, hip muscle strength, spine mobility, and spine muscle strength) showed good correlation with the patient's global impression of improvement. The measures in the "mobility of the pelvic joints" category were insufficient for assessing clinical change in posterior pelvic pain since pregnancy. The measures in the "fatigue" and "pain provocation tests" categories correlated only moderately with clinical change. CONCLUSIONS: It seems possible to gain appropriate information about the course of posterior pelvic pain since pregnancy with a small test battery. The usefulness of the Québec Back Pain Disability Scale, the hip adduction strength assessment, and the active straight-leg-raise test was proved by the current study. The value of 23 other instruments was substantiated, but further studies are needed to confirm their usefulness. The correlation of 22 evaluated measures with the patient's global improvement was too weak for them to be recommended as measures of clinical changes over time in posterior pelvic pain since pregnancy. It is recommended that clinicians and investigators compile a small test battery by selecting the best representatives of the five measurement categories that have good correlation with the patient's global impression of improvement.