Abstracts: AAOMPT Conference, 2002

Abstract

Background/Purpose: The purpose of this case report is to describe the clinical management of a patient with sacroiliac joint dysfunction (SIJD) and a concomitant asymmetrical hip-joint rotation range of motion. The patient was a 53-year-old male whose chief complaint was right low back pain (LBP) that interfered with work and leisure activities. Physical therapy consisted of manual therapy, stretching, and postural education to address SIJ and hip motion abnormalities. At the conclusion of 6 visits, the hip-joint rotation range of motion was more symmetrical. The patient reported self-correction of unilateral standing and sitting postures. He returned to full-time work and to playing golf, and he rated pain at 0-1/10. This patient's asymmetrical hip-joint rotation range of motion may have been associated with SIJD, either as a result of trauma or subsequent habitual postural adjustments. Clinician awareness of the possible relationship between SIJD and asymmetrical hip joint rotation range of motion is recommended.     

Formative Dynamics: The Pelvic Girdle

Abstract

Altered mechanics and/or forces related to the lumbar/pelvic/hip regions may result in pelvic-girdle dysfunction and or instability, which then may contribute to the development, persistence, or reoccurrence of low back pain (LBP). This series of three case studies outlines an integrated biomechanical clinical evaluation and treatment approach utilizing manual care, education, and exercise in the treatment of patients with chronic pelvic-girdle dysfunction and/or instability.

This integrated approach was used on three patients with a primary diagnosis of sacroiliac joint (SIJ) dysfunction. These patients had similar patterns of altered mechanics, movement patterns, and muscle imbalances. The treatment they received was an integration of three components: 1) restoration of optimal soft tissue/joint mechanics to the thoracic/lumbar/pelvic region and lower quarters; 2) patient education in specific self-stretching/mobilization exercises, spinal/pelvic stabilization exercises, and body mechanics training; 3) pelvic external bracing and/or prolotherapy injections (sclerosing) for those patients with hypermobile/unstable, chronic and recurring pelvic girdle dysfunction. Treatment varied from 24 to 35 visits over a 3-4 month period. The treatment outcomes demonstrated a correlation between improved patient function and pain reduction after restoring optimal mobility, functional strength, and movement patterns. These benefits lasted well beyond the course of treatment. Further research is needed to determine whether patients with chronic pelvic-girdle dysfunction and/or instability who receive this integrated approach will consistently achieve lasting pain relief and restoration of function when compared with no treatment or other treatment approaches.     

Sacroiliac joint dysfunction as a reason for the development of acetabular retroversion: a new theory

Abstract

Acetabular retroversion has been recently implicated as an important factor in the development of femoral acetabular impingement and hip osteoarthritis. The proper function of the hip joint requires that the anatomic features of the acetabulum and femoral head complement one another. In acetabular retroversion, the alignment of the acetabulum is altered where it opens in a posterolaterally instead of anterior direction. Changes in acetabular orientation can occur with alterations in pelvic tilt (anterior/posterior), and pelvic rotation (left/right). An overlooked problem that alters pelvic tilt and rotation, often seen by physical therapists, is sacroiliac joint dysfunction. A unique feature that develops in patients with sacroiliac joint dysfunction (SIJD) is asymmetry between the left and right innominate bones that can alter pelvic tilt and rotation. This article puts forth a theory suggesting that acetabular retroversion may be produced by sacroiliac joint dysfunction.     

Obturator nerve impingement caused by an osteophyte in the sacroiliac joint: A case report

BACKGROUNDCases of obturator nerve impingement (ONI) caused by osteophytes resulting from bone hyperplasia on the sacroiliac articular surface have never been reported. This paper presents such a case in a patient in whom severe lower limb pain was caused by osteophyte compression of the sacroiliac joint on the obturator nerve.CASE SUMMARYA 65-year-old Asian man presented with severe pain and numbness in his left lower limb, which became aggravated during walking and showed intermittent claudication. The physical examination revealed that the muscle strength of the left lower limb had decreased and that the passive knee flexion test result was positive. Computed tomography (CT) and 3D reconstruction showed a large osteophyte located in the anterior lower part of the left sacroiliac joint. The results of electrophysiological examination showed peripheral neuropathy. A CT-guided obturator nerve block significantly reduced the severity of pain in this patient. According to the above findings, ONI caused by the osteophyte in the sacroiliac joint was diagnosed. This patient underwent an operation to remove the bone spur and symptomatic treatment. After therapy, the patient''s pain and numbness were significantly relieved. The last follow-up was performed 6 mo after the operation, and the patient recovered well without other complications, returned to work, and resumed his normal lifestyle.CONCLUSIONOsteophytes of the sacroiliac joint can cause ONI, which leads to symptoms including severe radiative pain in the lower limb in patients. The diagnosis and differentiation of this disease should attract the attention of clinicians. Surgical excision of osteophytes should be considered when conservative treatment is not effective.     

Letters to the Editor

Abstract

The purpose of this case series was to explore the effects of tibio-femoral (TF) manual traction on pain and passive range of motion (PROM) in individuals with unilateral motion impairment and pain in knee flexion. Thirteen participants volunteered for the study. All participants received 6 minutes of TF traction mobilization applied at end-range passive knee flexion. PROM measurements were taken before the intervention and after 2, 4, and 6 minutes of TF joint traction. Pain was measured using a visual analog scale with the TF joint at rest, at end-range passive knee flexion, during the application of joint traction, and immediately post-treatment. There were significant differences in PROM after 2 and 4 minutes of traction, with no significance noted after 4 minutes. A significant change in knee flexion of 25.9°, which exceeded the MDC₉₅, was found when comparing PROM measurements pre- to final intervention. While pain did not change significantly over time, pain levels did change significantly during each treatment session. Pain significantly increased when the participant's knee was passively flexed to end range; it was reduced, although not significantly, during traction mobilization; and it significantly decreased following traction. This case series supports TF joint traction as a means of stretching shortened articular and periarticular tissues without increasing reported levels of pain during or after treatment. In addition, this is the first study documenting the temporal aspects of treatment effectiveness in motion restoration.     

Critical Analysis of the Sequence and Extent of the Result of the Pathological Failure of Self-Bracing of the Sacroiliac Joint

Abstract

When the sacrum is loaded with superincumbent weight, the sacroiliac joint functions as a self-compensating force couple. This couple creates and tends to rotate around an axis perpendicular to itself. The location of this axis may vary and depends upon the forces applied to the couple. As ligamentous tension increases in the couple, the sacroiliac joints are drawn tightly together through a mechanism of self-bracing. Self-bracing and its normal release or diminution provides for the storage and release of energy, which enhances the efficiency of normal ambulation and which modifies external forces. Failure of the force couple causes failure of the transverse axis of rotation of the sacroiliac joint and failure of the self-bracing mechanism. Because of the decrease in friction and stability, the innominate bones rotate anteriorly on the sacrum on an acetabular axis with the onset of pain and an alteration in apparent leg length. The resultant dysfunction may range from slight to severe, from minor ligamentous sprains to major sprains, muscle separations, and rents in the joint capsule. These rents may leak synovial fluid to the fifth lumbar nerve root, the lumbosacral plexus, and other tissues; and the resulting lesion may mimic disc dysfunction or create the impression of a multifactorial etiology. However it is seldom included in assessment of low back pain. A critical analysis of the biomechanics demonstrates the sequence and extent of involvement of adjacent tissues and structures, and it provides some direction for the restoration of normal function.     

CT导引下的骶髂关节造影及其临床意义初探

目的探讨ＣＴ导引下的骶髂关节造影术及其临床意义。方法对５例骶髂关节病变患者和１５例腰腿痛的志愿者进行ＣＴ导引下的骶髂关节造影,造影后行ＣＴ扫描、Ｘ线拍片并填写疼痛图。结果骶髂关节ＣＴ扫描显影良好,Ｘ线片影像欠清晰。２例有骶髂关节病变患者的ＣＴ扫描发现有造影剂外溢及隐窝。本组共１４例感造影后穿刺侧臀部及大腿后上方酸痛,５例骶髂关节病变患者诉造影术引发的疼痛与术前疼痛部位相同。结论ＣＴ导引下的骶髂关节造影术与传统的造影方法相比,即避免了过多接触Ｘ线照射引起的伤害,又提高了工作效率,为临床诊断和开展相关研究提供了有意义的影像学信息。     

A multiple regression normalization approach to evaluation of gait in total knee arthroplasty patients

BackgroundGait features characteristic of a cohort may be difficult to evaluate due to differences in subjects' demographic factors and walking speed. The aim of this study was to employ a multiple regression normalization method that accounts for subject age, height, body mass, gender, and self-selected walking speed in the evaluation of gait in unilateral total knee arthroplasty patients.MethodsThree-dimensional gait analysis was performed on 45 total knee arthroplasty patients and 31 aged-matched controls walking at their self-selected speed. Gait data peaks including joint angles, ground reaction forces, net joint moments, and net joint powers were normalized using subject body mass, standard dimensionless equations, and a multiple regression approach that modeled subject age, height, body mass, gender, and self-selected walking speed.FindingsNormalizing gait data using subject body mass, dimensionless equations, and multiple regression approach resulted in a significantly lower knee adduction moment and knee extensor power in total knee arthroplasty patients compared to controls (p < 0.05). In contrast to normalization using body mass and dimensionless equations, multiple regression normalization greatly reduced variance in gait data by minimizing correlations with subject demographic factors and walking speed, resulting in significantly higher peak hip extension angles and peak hip flexion powers in total knee arthroplasty patients (p < 0.05).InterpretationTotal knee arthroplasty patients generate greater hip extension angles and hip flexor power and have a lower knee adduction moment than healthy controls. This gait pattern may be a strategy to reduce muscle and joint loading at the knee.     

Limitations in activities in patients with osteoarthritis of the hip or knee: The relationship with body functions,comorbidity and cognitive functioning

Purpose. To determine the relationship between body functions, comorbidity and cognitive functioning on the one side and limitations in activities on the other, in elderly patients with osteoarthritis (OA) of the hip or knee.

Method. A cross-sectional cohort study was conducted in which 288 patients with hip or knee OA were included. Patients were recruited from rehabilitation centres and hospitals (Departments of Orthopedics, Rheumatology or Rehabilitation). Apart from demographic and clinical data, information about limitations in activities, body functions (pain, muscle strength, range of joint motion), comorbidity and cognitive functioning was collected by questionnaires and tests. Statistical analyses included univariate and stepwise multivariate regression analysis.

Results. Self-reported limitations in activities (Western Ontario and McMaster Universities Osteoarthritis Index) were significantly associated with pain, muscle strength knee extension, range of motion (ROM) hip flexion and morbidity count. Performance-based limitations in activities (timed walking test) were significantly associated with ROM (knee flexion, hip flexion and knee extension), muscle strength hip abduction, pain, cognitive functioning and age.

Conclusions. Self-reported limitations in activities in hip or knee OA are largely dependent on pain and to a lesser extent on range of joint motion, muscle strength and comorbidity. Performance-based limitations in activities are largely dependent on range of joint motion and muscle strength, and to a lesser extent on pain, cognitive functioning and other factors. These findings point to the role of body functions in limitations in activities in OA of the hip or knee. Although less important, comorbidity and cognitive functioning play a role as well.     

动态CT观察髌股关节排列异常

目的 分析动态CT评估髌股关节排列的方法 和价值.方法 分别在屈膝0°、10°、20°、30°时用CT检测30例60膝髌股关节,观察膝关节不同屈曲角度髌股关节的排列,测量各屈曲度髌股关节的股骨滑车角、相称角及外侧髌股角,分析不同角度对髌股排列异常的检出率.结果 本组分别在膝关节0°、10°、20°、30°选取髌骨棘与股骨滑车凹最深的层面测量,有15膝的相称角大于16°,为髌骨外侧半脱位,16膝为髌骨外倾,10膝髌骨外侧倾斜合并半脱位.统计学分析证实膝关节屈曲10°和20°对髌骨外倾、半脱位检出率高.结论 动态CT能评估髌股关节排列,膝关节屈曲10°和20°是诊断髌股关节排列异常的重要位置.     

胎儿膝关节反屈超声表现

目的 观察胎儿膝关节反屈的超声表现。方法 回顾性分析15胎膝关节反屈胎儿的产前超声资料，其中14胎于引产后、1胎于分娩后获得明确诊断，观察其产前超声声像图特征。结果 15胎中，超声诊断正确12胎，漏诊3胎。膝关节反屈超声表现为胎儿患侧膝关节屈曲方向异常，呈向心性屈曲（即膝关节弯曲时下肢远端肢体向靠近躯干侧运动），受累侧肢体运动受限，无自主屈曲活动。15胎中，7胎膝关节反屈孤立发生，但均合并畸形；8胎为各种综合征的下肢表现，包括2胎Larsen综合征、5胎先天性多发性关节挛缩症及1胎窒息性胸廓发育不良。结论 胎儿膝关节反屈超声表现具有一定特征性，有助于产前筛查。     

Sacroiliac joint diagnostics in the Hamburg Construction Workers Study

BACKGROUND: In the medical literature, test procedures for sacroiliac joint diagnostics are viewed as controversial. The provocation tests are based on provoked sacroiliac pain, whereas the palpation tests examine the motion of the sacroiliac joint or describe the condition indirectly if limitation of the sacroiliac function is present. It must be presumed that the use of different test results in the detection of varying functional phenomena of a sacroiliac dysfunction or, alternatively, that identical effects of a dysfunction are evaluated in differing ways. OBJECTIVE: This article presents results with regard to the consistency of tests for sacroiliac joint dysfunctions carried out on participants from the building trade. DESIGN AND PARTICIPANTS: The consistency of the tests (standing flexion test, spine test, iliac compression test, iliac springing test) used in a cross-section investigation of a cohort of 480 male construction workers is presented. To evaluate the degree of consistency of the test procedure the percentage agreement and the kappa value, including a confidence interval of 95%, are given. RESULTS: The consistency between the iliac compression test and the three sacroiliac palpation tests could not be shown to be statistically significant. The consistency between the three palpation tests was moderate to good and the percentage agreement was acceptable (87.4%, 88.6%, 80.9%). CONCLUSIONS: It may be assumed that the palpation tests characterize the same dysfunction of the sacroiliac joint. Standing flexion test, spine test, and iliac springing test seem to be valuable tools for sacroiliac joint diagnostics.     

Immediate effects of a new microprocessor-controlled prosthetic knee joint: a comparative biomechanical evaluation

Bellmann M, Schmalz T, Ludwigs E, Blumentritt S. Immediate effects of a new microprocessor-controlled prosthetic knee joint: a comparative biomechanical evaluation.ObjectiveTo investigate the immediate biomechanical effects after transition to a new microprocessor-controlled prosthetic knee joint.DesignIntervention cross-over study with repeated measures. Only prosthetic knee joints were changed.SettingMotion analysis laboratory.ParticipantsMen (N=11; mean age ± SD, 36.7±10.2y; Medicare functional classification level, 3–4) with unilateral transfemoral amputation.InterventionsTwo microprocessor-controlled prosthetic knee joints: C-Leg and a new prosthetic knee joint, Genium.Main Outcome MeasuresStatic prosthetic alignment, time-distance parameters, kinematic and kinetic parameters, and center of pressure.ResultsAfter a half-day training and an additional half-day accommodation, improved biomechanical outcomes were demonstrated by the Genium: lower ground reaction forces at weight acceptance during level walking at various velocities, increased swing phase flexion angles during walking on a ramp, and level walking with small steps. Maximum knee flexion angle during swing phase at various velocities was nearly equal for Genium. Step-over-step stair ascent with the Genium knee was more physiologic as demonstrated by a more equal load distribution between the prosthetic and contralateral sides and a more natural gait pattern. When descending stairs and ramps, knee flexion moments with the Genium tended to increase. During quiet stance on a decline, subjects using Genium accepted higher loading of the prosthetic side knee joint, thus reducing same side hip joint loading as well as postural sway.ConclusionsIn comparision to the C-Leg, the Genium demonstrated immediate biomechanical advantages during various daily ambulatory activities, which may lead to an increase in range and diversity of activity of people with above-knee amputations. Results showed that use of the Genium facilitated more natural gait biomechanics and load distribution throughout the affected and sound musculoskeletal structure. This was observed during quiet stance on a decline, walking on level ground, and walking up and down ramps and stairs.     

Activation of the quadriceps muscle during semisquatting with different hip and knee positions in patients with anterior knee pain.

OBJECTIVE: We measured the surface electromyographic activities of vastus medialis obliquus and vastus lateralis in 16 subjects with patellofemoral joint pain syndrome. DESIGN: Each subject performed bilateral static knee extension exercises at 60% of his or her maximal voluntary effort under different combinations of hip rotation (30 degrees of medial rotation, neutral, 45 degrees of lateral rotation) and knee flexion (20 and 40 degrees) in a standing position. The ratio of surface-integrated electromyographic signals of vastus medialis obliquus over vastus lateralis was calculated for each of the six conditions. Because of significant interaction of hip rotation and knee flexion in the two-way analysis of variance, data were analyzed separately with paired t tests for the effect of knee positions and one-way repeated measures analysis of variance for hip positions. RESULTS: At 20 degrees of knee flexion, there was no significant difference among the three hip positions, whereas at 40 degrees of knee flexion, medial rotation of the hip resulted in significantly higher vastus medialis obliquus over vastus lateralis activity ratio than lateral rotation (P < 0.05). CONCLUSIONS: There was relatively more activation of vastus medialis obliquus than vastus lateralis at 40 degrees of semisquat with the hip medially rotated by 30 degrees. This finding has clinical implications for training the vastus medialis obliquus in patients with patellofemoral joint pain syndrome.     

Relationship of the mobility of the sacroiliac joint with foot plant pressure

[Purpose] To evaluate mobility of the sacroiliac joint and plantar pressure changes. [Participants and Methods] This was an analytical study comprised of 300 participants, using a functional kinetic evaluation involving the test of standing flexion (SFT), the test of Downing, the test of Gillet, and the analysis of baropodometry. [Results] There was an association between mobility of the sacroiliac joint and the standing center of gravity. However, the mobility of this joint was not associated with plantar pressure and the plantar contact area. [Conclusion] These data suggest that sacroiliac mobility is linked to the center of gravity. This connection may precede sacroiliac dysfunction and may help to improve the accuracy of the tests.Key words: Sacroiliac mobility, Sacroiliac joint, Plantar pressure     

Sell-Irritationspunkt S1

Objectives

The aim of the present study was to evaluate the morphological correlate of the irritation point S1 described by Karl Sell (Sell’s irritation point S1). Furthermore, the reliability of this irritation point in the context of the 3-stage diagnostics was analyzed concerning the diagnosis of sacroiliac dysfunction.

Patients and methods

The hip joint, lumbar spine and sacroiliac joint were tested in 228 patients using the basis investigation described by James Cyriax to find the source of low back pain. Furthermore, Sell’s irritation point S1 was included in the clinical examination. After the clinical tests using a protocol a distinction could be made between the following sources of low back pain: (1) internal disc disruption of the lower lumbar spine, (2) sciatic nerve pain, (3) sacroiliac joint and (4) zygapophyseal joint of L5/S1. Sell’s irritation point S1 was tested before and after treatment.

Results

An internal disc disruption as the source of low back pain was found in 112 (49.1?%) patients. In 12 (8.8?%) patients the sacroiliac joint was the primary source of low back pain. Sciatic pain was diagnosed in 86 (37.7?%) patients and a combination of discogenic pain and zygapophyseal pain L5/S1 was found in 10 (4.4?%) patients. Sell’s irritation point S1 was negative before treatment in 120 (52.6?%) and positive in 108 (47.4?%) patients. After treatment Sell’s irritation point S1 was unchanged in 136 (59.6?%), more painful in 2 (0.9?%) and less painful in 90 (39.5?%) patients. In comparison between patients of the sacroiliac group and non-sacroiliac group a p-value of 0.252 was statistically analyzed. Sell’s irritation point S1 is neither reliable nor valid with respect to clinical examinations to determine the sacroiliac joint as a source of low back pain.     

Intraoperative experiments combined with gait analyses indicate that active state rather than passive dominates the spastic gracilis muscle's joint movement limiting effect in cerebral palsy

BackgroundIn cerebral palsy, spastic muscle's passive forces are considered to be high but have not been assessed directly. Although activated spastic muscle's force-joint angle relations were studied, this was independent of gait relevant joint positions. The aim was to test the following hypotheses intraoperatively: (i) spastic gracilis passive forces are high even in flexed knee positions, (ii) its active state forces attain high amplitudes within the gait relevant knee angle range, and (iii) increase with added activations of other muscles.MethodsIsometric forces (seven children with cerebral palsy, gross motor function classification score = II) were measured during surgery from knee flexion to full extension, at hip angles of 45° and 20° and in four conditions: (I) passive state, after gracilis was stimulated (II) alone, (III) simultaneously with its synergists, and (IV) also with an antagonist.FindingsDirectly measured peak passive force of spastic gracilis was only a certain fraction of the peak active state forces (maximally 26%) measured in condition II. Conditions III and IV caused gracilis forces to increase (for hip angle = 45°, by 32.8% and 71.9%, and for hip angle = 20°, by 24.5% and 45.1%, respectively). Gait analyses indicated that intraoperative data for knee angles 61–17° and 33–0° (for hip angles 45° and 20°, respectively) are particularly relevant, where active state force approximates its peak values.InterpretationActive state muscular mechanics, rather than passive, of spastic gracilis present a capacity to limit joint movement. The findings can be highly relevant for diagnosis and orthopaedic surgery in individuals with cerebral palsy.     

Kinematic and Kinetic Predictors of Y-Balance Test Performance

BackgroundThe Y-Balance Test (YBT) assesses dynamic stability and neuromuscular control of the lower extremity. Several authors have analyzed kinematic predictors of YBT performance with conflicting results, but the influence of kinetic factors is not well understood.PurposeTo examine kinematic predictors of YBT performance and determine the joint kinetics which predict YBT performance.Study DesignCross-sectional study.MethodsThirty-one physically active individuals performed YBT trials on a force plate while whole body kinematics were recorded using a motion capture system. Sagittal, frontal, and transverse plane joint kinematics and joint moments were calculated at maximum reach in each YBT reach direction. Variables correlated with reach distances at the p < 0.2 level were entered into a stepwise linear regression.ResultsIn the anterior direction, knee flexion and torso rotation (R²=0.458, p<0.001) and knee extensor and hip abductor moments (R²=0.461, p<0.001) were the best kinematic and kinetic predictors of reach distance. In the posterior medial direction, hip flexion, ankle dorsiflexion, and ankle rotation accounted for 45.8% of the variance in reach direction (p<0.001) while hip and knee extensor, and hip abductor moments explained 72.6% of the variance in reach distance (p<0.001). In the posterior lateral direction, hip flexion and pelvic rotation (R²=0.696, p<.001) and hip extensor moments (R²=0.433, p=0.001) were the best kinematic and kinetic predictors of reach distance.ConclusionThe ability to generate large hip and knee joint moments in the sagittal and frontal plane are critical for YBT performance.Level of Evidence3.     

Resolving anterior hip pain in a young male footballer following arthroscopic surgery for Femoroacetabular Impingement Syndrome: A case report

BackgroundThere appear to be limited studies available regarding the conservative management of patients following hip joint arthroscopic surgery, or investigating reasons for which patients still report hip and groin pain post surgery.ObjectivesTreatment was applied to restore spino-pelvic mechanics and to reduce soft tissue restrictions in hip joint motion. Neuromuscular movement control and work capacity exercises were encouraged to support the integrity of the hip joint and spino-pelvic complex.Clinical featuresA 22-year-old male footballer, (height 190cm and weight 82kg) presented reporting an eighteen-month history of hip and groin pain, having previously undergone bilateral arthroscopic surgery twelve months earlier for Femoroacetabular Impingement Syndrome. Strength measurements were recorded using the MicroFET 2 Wireless Digital Handheld Dynamometer. Trunk muscular endurance was evaluated with Sorenson test.ResultsFive treatment consultations over a five-week period resulted in pain reduction, (Visual Analogue Scale 8/10 to 0/10). Improvement in range of motion, right hip flexion (70–100°) and left (80–100°), right internal rotation (30–45°) and left (40–45°). Improvement in strength, specifically right hip flexion (0.29–0.43Nm/kg, 48%) and right hip abduction (0.35–0.46Nm/kg, 31%). Improvement in trunk muscular endurance increased 41% from 170 seconds to 240 seconds.ConclusionThis case report supports the rationale that the post arthroscopic management of Femoroacetabular Impingement Syndrome, should include both treatment to address spino-pelvic restrictions, if appropriate, combined with exercises that specifically target hip flexor strength. However, a larger randomized study would provide a clearer understanding for the management of this particular subset of patients.     

The piriformis muscle syndrome: An exploration of anatomical context,pathophysiological hypotheses and diagnostic criteria

IntroductionThe piriformis muscle syndrome (PMS) has remained an ill-defined entity. It is a form of entrapment neuropathy involving compression of the sciatic nerve by the piriformis muscle. Bearing this in mind, a medical examination is likely to be suggestive, as a classical range of symptoms corresponds to truncal sciatica with frequently fluctuating pain, initially in the muscles of the buttocks.Pathophysiological hypothesesThe piriformis muscle is biarticular, constituting a bridge in front of and below the sacroiliac joint and behind and above the coxo-femoral joint. It is essentially a lateral rotator but also a hip extensor, and assumes a secondary role as an abductor. Its action is nonetheless conditioned by the position of the homolateral coxo-femoral joint, and it can also function as a hip medial rotator, with the hip being flexed at more than 90°. The main clinical manoeuvres are derived from these types of biomechanical considerations. For instance, as it is close to the hip extensors, the piriformis muscle is tested in medial rotation stretching, in resisted contraction in lateral rotation. On the other hand, when hip flexion surpasses 90°, the piriformis muscle is stretched in lateral rotation, and we have consequently laid emphasis on the manoeuvre we have termed Heel Contra-Lateral Knee (HCLK), which must be prolonged several tens of seconds in order to successfully reproduce the buttocks-centred and frequently associated sciatic symptoms.ConclusionA PMS diagnosis is exclusively clinical, and the only objective of paraclinical evaluation is to eliminate differential diagnoses. The entity under discussion is real, and we favour the FAIR, HCLK and Freiberg stretching manoeuvres and Beatty's resisted contraction manoeuvre.