Comprehensive Analysis of Pelvic Asymmetries in Low Back Pain, Scoliosis, Post-Traumatic Pelvic Dysfunctions and Obstetric Changes: A Narrative Review Focused on Clinical Relevance

Abstract

The human pelvis is a complex structure, which participates in the biomechanical functioning of the musculoskeletal system. Although it is considered a symmetrical entity, the morphology of the pelvis is subject to different factors that alter its anatomy, function or biomechanics, such as age, bipedal locomotion, obstetric changes and sexual dimorphism. However, how these factors influence pelvic asymmetry is unknown. Some evidence suggests that this condition leads to different pathological states, such as chronic low back pain, scoliosis, post-traumatic pelvic dysfunctions and obstetric changes. Therefore, pelvic asymmetries present a significant challenge in clinical practice due to their multifactorial nature and their potential impact on quality of life. Multidisciplinary research and collaboration are essential to improve understanding and develop more effective and specific identification and treatment approaches in the presence of pelvic asymmetries.

1. Introduction

Symmetry is fundamental to human biomechanics, but our body is inherently asymmetrical [1]. Human posture should present a symmetrical position in both the frontal and transverse planes. However, this symmetry is often disrupted due to functional and structural asymmetries. Functional asymmetries are related to the execution and control of movements, affecting their dynamics and efficiency, such as lateral dominance. Structural asymmetries involve physical differences in anatomy, impacting body mechanics and force distribution, and are caused by developmental diseases or conditions acquired after trauma or surgery. Therefore, the spatial position of the anatomical structures, such as the pelvis, is crucial for developing a correct body posture [2] and could be related to other musculoskeletal pathologies [3].

The human pelvis is a complex anatomical structure consisting of the hip bones, sacrum, and coccyx, which together form the pelvic ring [4]. It also includes muscles and fascia layers interwoven with vascular and nervous networks and connected to various viscera [5]. From a mechanical perspective, the pelvis is an integral element connecting the trunk and lower extremities [6] to support and transfer loads during different functional movements [2], where muscles, fasciae, and ligaments from the lumbar region, abdomen, and lower limbs converge, forming the base of the biomechanical functioning of the musculoskeletal system [7].

Pelvic asymmetry refers to the irregular alignment of the pelvic structures in the frontal plane (lateral pelvic tilt), sagittal plane (anterior/posterior iliac rotation), or transverse plane (axial pelvic rotation) in relation to the vertical axis [8]. Recent studies have examined pelvic ring asymmetry, finding that torsional forces in the axial plane cause unidirectional asymmetry [9], interpreted as an anatomical adaptation to repetitive unilateral biomechanical loads. This phenomenon is explained by the classic overload principle, which indicates that biological tissues anatomically adapt when stressed beyond their normal level during daily tasks [8]. For example, bipedal locomotion alters the shape and angulation of the sacrum throughout life [10]. In fact, it has been reported that approximately 80% of healthy individuals have rotated body patterns that could lead to the lumbopelvic complex being more prone to asymmetry due to the fascial tension [11,12]. However, it is unknown if kinematic symmetry varies between different daily activities [13] and its relevance in different clinical entities.

On the one hand, approximately 70–90% of adults exhibit a predisposition to use the right side in the upper limb [7], while there is a less pronounced tendency to use the left side in the lower limb. Evidence suggests that the human pelvis may present a leftward bias due to the biomechanical codependency with the lower extremities [10]. It is postulated that this asymmetric biomechanical pattern is related to gait asymmetries, producing uneven loads on the pelvis [14]. Lateralized movement patterns, such as adopting asymmetric standing positions, significantly impact the development of muscle tension imbalances. In most cases, when the right lower limb is dominant, it is often preferred for more frequent support and longer load time during walking. Over time, these preferences can lead to functional shortening or lengthening of the lower limb, resulting in an asymmetric pelvis position [7]. However, it remains unclear if there is a stable pattern of asymmetry is observed within the pelvis and if it becomes clinically relevant [10].

On the other hand, the morphology and size of the pelvic canal differ between sexes, giving rise to the concept of sexual dimorphism [15], that could lead to different patterns of pelvic asymmetries between sexes. The concept of sexual dimorphism refers to the morphological and functional differences between women and men, which are particularly evident in the pelvis and its kinematics. For instance, a greater height and smaller diameter of the pelvic ring are associated with the male sex [3]. The male pelvis also presents a longer and more curved sacrum and a narrower subpubic arch, pubis and pelvic inlet [16]; whereas the female pelvis is wider, with less prominent ischial spines [17]. Iliac crest asymmetry is more prevalent in females, while males exhibit a more pronounced lowering of the right iliac crest [2]. Nonetheless, there are few sex differences in the percentage of asymmetries, supporting that the female pelvis is not biologically less plastic than the male pelvis, indicating variable patterns of pelvic asymmetry [14]. This indicates that the pelvis exhibits remarkable biological plasticity, but its clinical relevance has not been adequately addressed. The combination of sex and age has been studied, with women aged 50 to 59 years exhibiting 36% more maximum pelvic ring deviation compared to women aged 20 to 29 years [18], resulting in a greater number of pelvic asymmetries. Nevertheless, there is no consensus on whether morphological differences between the sexes are the result of obstetric constraints or allometric growth trajectories [17], and the clinical relevance of these asymmetries remains poorly understood [3].

Therefore, the objective of this narrative review is to analyze the existing literature on pelvic asymmetries, focusing on their main clinical manifestations and how address them in different population groups, to improve understanding and develop more effective and personalized treatment approaches.

2. Materials and Methods

This narrative review was conducted following the methodology established by PRISMA guidelines [19] (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement to ensure adequate transparency and comprehensiveness in the selection and synthesis of the literature. Although PRISMA is designed for systematic reviews and meta-analyses, relevant elements were adopted for the comprehensive literature search, study selection, and data presentation. This review included systematic reviews, narrative reviews, and original research articles published between 2014 and 2024, indexed in the following databases: PubMed, PEDro and Google Scholar. The time range 2014–2024 was chosen to capture the most current and relevant information on pelvic asymmetries and to adhere to Price’s Law [20]. In addition, since 2014, guidelines for the reporting of health research study designs have been standardized [21].

For the bibliographic search, the following descriptors/keywords were used in both Spanish and English: pelvic asymmetries, pelvic morphology, sexual dimorphism, pelvic changes, pregnancy. Boolean operators and parentheses were used to prioritize the search by combining different formats to obtain the most relevant articles (

Table 1. String used according to the databases.

Database	String
PubMed	((“pelvic asymmetries” [MeSH] OR “pelvic morphology” [MeSH]) AND “sexual dimorphism” [MeSH]) AND ((“pregnancy changes” [MeSH] OR “pelvic changes” [MeSH]) AND (“2014” [PDAT]: “2024” [PDAT]))
PEDro	((“pelvic asymmetries” OR “pelvic morphology”) AND “sexual dimorphism”) AND ((“pregnancy changes” OR “pelvic changes”) AND (2014 TO 2024))
Google Scholar	((“pelvic asymmetries” OR “pelvic morphology”) AND “sexual dimorphism”) AND (“pregnancy changes” OR “pelvic changes”)

). This format allowed the retrieval of articles containing the keywords “pelvic asymmetries” or “pelvic morphology” combined with “sexual dimorphism” in addition to including subsets related to “pregnancy changes” or “pelvic changes” within the 2014–2024 range.

Additional information searches were conducted in the bibliographic reference lists of the included articles to ensure no relevant information was missed. The studies were selected by the authors based on the topic of study and focused on clinical relevance. Summary tables were then used to compile and contrast the key characteristics and findings of each study.

3. Results and Discussion

The bibliographic search initially obtained 153 documents, of which 96 were excluded based on the title and/or abstract analysis. Out of the remaining 57 documents, 37 were excluded for the following reasons: 15 due to duplication and 3 because they were published before 2014. Consequently, 19 articles were included in this literature review (Table 2 and Table 3). No additional studies were identified through manual searching of references. None of the studies found were randomized clinical trials aimed to correct pelvic asymmetries in any disorder. The studies by Yu et al. [8], Handrich et al. [4], and Colonna et al. [22] are listed in Table 2 and Table 3 because they provide information on both clinical manifestations and evaluation of pelvic asymmetries.

3.1. Clinical Manifestations of Pelvic Asymmetries

After analyzing the studies included in this review, the most significant clinical manifestations associated with pelvic asymmetries are discussed.

3.1.1. Low Back Pain

Low back pain is one of the most common musculoskeletal disorders, affecting 80% of the population at some point in their lives. The increasing prevalence of low back pain is extensively detailed in the literature, with approximately 85% classified as non-specific [23]. This term is used when the anatomopathological cause of the pain cannot be determined [24]. However, low back pain has been associated with changes in neuromuscular activity, reduced spinal mobility, limited lumbar muscle flexibility, and altered spinal kinematics [25], that could be related to pelvic asymmetries.

Dysfunction of the sacroiliac joint, that is commonly unilateral, is a common cause of low back pain, occurring in 16 to 30% of patients [26]. Since the gluteus minimus and medius muscles, piriformis muscle, multifidus, transverse abdominis and internal oblique muscles [27] contribute to the proper functioning of the hip joint, the sacroiliac joint cannot function independently; therefore, muscles also influence the articular stability [4]. Additionally, the sacrum is highly sensitive to biomechanical influences, as asymmetric forces transmitted from the upper body through the spine affect sacral asymmetries [3]. Asymmetric biomechanics of the lumbosacral and sacroiliac joint surfaces can increase unilateral muscle activity, which may subsequently lead to chronic non-specific low back pain. Thus, while pelvic asymmetry has been observed to contribute to the development of low back pain, specific empirical evidence demonstrating its association with low back pain in the young adult population is lacking [8].

Previous studies have shown that anterior pelvic tilt angle is associated with low back pain due to increased soft tissue tension in that region [8]. These changes lead to reduced lumbar spine function and altered mechanical muscle properties, which are crucial in physiological and pathophysiological processes, suggesting a relationship between pain and muscle stiffness in different disorders, such as low back pain [25], and asymmetrical muscles of the trunk and lumbopelvic region. This pattern causes fatigue of the spinal muscles and/or cumulative stress on osteoligamentous structures [28]. In this context, modifications in asymmetric mechanical changes related to muscle activity redistribution in adults with chronic low back pain have been described [24], where greater stiffness of the paravertebral muscles on the painful side compared to the non-painful side has been observed [29].

Thus, postural and structural asymmetry contributes to low back pain with an increase in anterior pelvic tilt (Figure 1), which represents the most common pattern of low back pain associated with pelvic asymmetries [30]. For instance, trunk movement in a seated posture is asymmetric in patients with low back pain because spine alignment is altered to compensate for pelvic asymmetry. Additionally, pelvic asymmetry indicates that alignment in the frontal or sagittal plane is asymmetric relative to the vertical axis [31]. Therefore, identifying the relationship between pelvic asymmetry and low back pain can aid in the early identification of chronic low back pain.

Currently, intervention strategies for low back pain associated with pelvic asymmetries recommend the use of manual therapy [32], which includes spinal manipulation and mobilization, improving spinal and pelvic mobility as well as reducing patient pain [33]. Future research should focus on improving the accuracy and objectivity of diagnostic evaluations and designing effective treatments for this relationship [34].

3.1.2. Scoliosis

Idiopathic scoliosis is a three-dimensional spinal deformity with an etiology that remains unclear but is likely multifactorial [35]. Approximately 80% of scoliosis cases are classified as idiopathic, defined for the adolescent age range from 10 to 19 years, with a prevalence of 3% in the general population [36]. The development and progression of scoliosis are related to growth. Scoliosis can be classified as idiopathic or secondary. Idiopathic scoliosis is further divided into infantile, juvenile, and adolescent or early-onset and late-onset types, while secondary scoliosis is associated with congenital disorders, neuromuscular conditions, tumors, trauma, or syndromic conditions [37].

Asymmetric loading on the vertebrae and discs may be a contributing factor to the onset and progression of idiopathic scoliosis. Observations indicate that the paravertebral muscles, which stabilize the spine, are the source of this asymmetric loading. Specifically, increased tone and stiffness, along with reduced relaxation time of stress and creep, have been found on the concave side of the spine in adolescent idiopathic scoliosis [35,38] a clearly asymmetrical disorder that influences pelvic asymmetries. Conversely, some studies indicate that the asymmetry of the paravertebral muscles is a consequence of spinal curvature [35]. Additionally, anomalies in the lower limbs, such as those observed in gastrocnemius and foot deformities, as well as dysmorphic fascial features, should be considered [37]. In this context, there are also studies exploring the relationship between the foot and ankle anomalies and the lumbosacral region, where asymmetries exist in non-contractile tissues [39].

Evidence suggests that pelvic asymmetries observed in scoliosis may not be anatomical but rather a result of compensatory pelvic rotation in the transverse plane. These asymmetries can impact biomechanics and force distribution, with directional asymmetries being responses to imbalanced loading [35]. It has been demonstrated that pelvic asymmetry follows a spiral pattern, with the iliac crests rotating clockwise and the pubic symphysis rotating counterclockwise (Figure 2). These variations in loading explain various pathologies associated with pelvic asymmetry, including chronic low back pain, as previously commented, and idiopathic scoliosis [3]. Furthermore, scoliotic discrepancies should be compensated only when the imbalance of the femoral heads is on the same side as the imbalance of the sacrum and the iliac crests; this corrective action should result in a reduction in the overhang in the coronal plane [22]. The clinical management of scoliosis is centered on conservative treatment utilizing scoliosis-specific physiotherapeutic exercises, which involve targeted stretching of the concave aspect of the curvature and muscular strengthening of the convex side. These interventions are based on the principles of three-dimensional postural self-correction, stabilization of the corrected posture, comprehensive patient education, and the systematic integration of optimal postural alignment into activities of daily living to enhance functional outcomes [40]. Understanding the relationship between pelvic asymmetries and scoliosis is crucial for developing more effective approaches in the treatment and prevention of this deformity, thereby improving the quality of life for patients.

3.1.3. Post-Traumatic Pelvic Dysfunctions

Post-traumatic pelvic dysfunctions often result from unstable pelvic fractures, characterized by the inability to maintain proper alignment of the pelvic bones after trauma [41]. This condition is clinically relevant as it can lead to significant complications such as chronic pain and biomechanical dysfunctions, severely affecting the patient’s quality of life [42]. Moreover, evidence indicates that pelvic asymmetry is present in 17% of pelvic fractures, with the incidence of pelvic asymmetry observed up to 48% in non-surgically treated patients. This can result in 34% of patients experiencing limited or total inability to participate in sports. The most commonly associated symptom is pelvic pain, primarily from the posterior pelvic ring, [43] due to a fracture of the posterior iliac crest caused by lateral compression forces. This results in hemipelvic instability during load transfer, due to displacement of the sacroiliac joint [44] (Figure 3A). Several studies demonstrate that the functional outcome of pelvic ring fractures depends on the degree of asymmetry in the pelvic ring, making anatomical reduction and surgical fixation of unstable pelvic fractures the preferred treatment option to ensure a favorable functional outcome [41].

Appropriate surgical treatment is essential to prevent complications such as non-union or secondary structural deformities [45], with the primary objective of the surgical intervention being the precise and stable reduction in the sacroiliac joint [44] (Figure 3B). However, restoring constitutional anatomy, including limb length and hip alignment, is also crucial to re-establish function and biomechanics for the patient [9]. Complex instabilities are associated with pelvic ring deformities and result from rotational or vertical instabilities that were either untreated initially, inadequately treated, or had an unsatisfactory outcome [45], leading to pelvic asymmetries of both fascial and bony origin. Therefore, timely and appropriate surgical intervention is critical to prevent complications such as non-union, structural deformities, or pelvic asymmetries.

3.1.4. Obstetric Changes

During pregnancy, changes in the alignment of the bones, especially around the pelvis, are vital for childbirth and postnatal health [46]. The size and shape of the pelvic canal are influenced by evolutionary pressures, traditionally explained by the Obstetrical Dilemma Hypothesis. This hypothesis posits that the female pelvis is a compromise between the demands of bipedal locomotion and childbirth. Although this idea has faced challenges recently, the influence of both obstetrical and locomotor factors on pelvic evolution is still widely accepted [14]. Additionally, pelvic rotation in relation to the body axis, or incorrect length of the muscles attached to the pelvic bones, could be the origin of pelvic asymmetries associated with changes in fascia tension, that could impair the biomechanics of the spine and lower limbs [5]. However, the specifics of when and how these changes occur are not completely clear. A deeper understanding of the chronology and nature of these changes, as well as postpartum recovery, could offer useful guidelines for well-being and allow for early detection of pelvic anomalies [47].

Table 2. Synthesis of studies according to clinical manifestations.

Clinical Manifestation	Author/Year	Type of Study	Outcomes
Low Back Pain	Devan et al. 2015 [28]	Systematic Review	Limited studies specifically investigate spinal and pelvic asymmetries during walking and other functional tasks in individuals with transfemoral and transtibial amputation.
	Yu et al. 2020 [8]	Original Article: observational, cross-sectional study	Two pelvic parameters were associated with the presence of non-specific chronic low back pain.
	Handrich et al. 2021 [4]	Original Article: observational, cross-sectional study	The pelvic ring, known for its complexity, has been shown not to be entirely symmetric. Six distinct pelvic ring asymmetries were identified in different anatomical regions.
	In et al. 2021 [31]	Original Article: observational, cross-sectional study	Pelvic asymmetry showed no significant difference between the sitting time and groups. Using a smartphone during prolonged sitting may lead to a slumped posture; these associations were more pronounced in adolescents with low back pain.
	Alcaraz-Clariana et al. 2022 [25]	Original Article: observational, test–retest study	Sequenced movements can modify muscle tone and stiffness as a function of age. Muscle mechanical properties should be assessed not only at the beginning of the physical examination at rest but also throughout the patient’s follow-up, considering their pain and age, in a clinical setting.
Scoliosis	Haleem et al. 2018 [37]	Narrative Review	Idiopathic scoliosis is a diagnosis of exclusion. The observed deformity could involve either spine/prominence ribs or asymmetry of the pelvis/shoulders. Treatment aims to halt curve progression and support lung development. In young child, growth modulation is the aim of treatment. Definitive surgery for idiopathic scoliosis is performed at skeletal maturity.
	Liu et al. 2019 [35]	Original Article: observational, cross-sectional study	Concave paravertebral muscle tone and stiffness were greater than those on the convex side in adolescents with idiopathic scoliosis. The asymmetric biomechanical characteristics of paravertebral muscles are closely related to the severity of scoliosis and the presence of pelvic asymmetries.
	Ren et al. 2024 [3]	Original Article: observational, cross-sectional study	Although there are differences in overall pelvic shape between sexes and ancestries, there is no relationship between these variables and pelvic asymmetry in the axial or sagittal planes in young adult osteological specimens.
	Colonna et al. 2024 [22]	Narrative Review	Scoliotic discrepancies should be compensated (conservatively or surgically) only when the imbalance of the femoral heads is on the same side as the imbalance of the sacrum and the iliac crests. This corrective action should result in a reduction in the overhang in the coronal plane.
Post-Traumatic Pelvic Dysfunctions	Cano-Luís et al. 2018 [45]	Narrative Review	The main cause of nonunion and pelvic deformity following pelvic fracture is the inadequate initial treatment of the fracture. Surgical approaches, reduction maneuvers and fixation techniques must be carefully planned, and the use of 3D printing at real size is very helpful in this regard.
	Mennen et al. 2022 [43]	Narrative Review	The field of pediatric pelvic surgery is currently does not fully grasp the complexity of the pediatric pelvic fractures, highlighting the need for a pediatric pelvic classification system and evidence-based treatment guidelines. Functional outcomes seem to be correlated with the frequency of pelvic asymmetry, likely due to an underestimation of the stability of the pelvic fracture.
	O’Callaghan et al. 2023 [9]	Original article: observational, retrospective study	Current computer-assisted surgery THR software reports measurements of global offset and hip length without considering pelvic asymmetry. Surgeons are not provided with confidence ranges to represent the potential impact of asymmetry on these measurements. Relying on these numbers to guide implant position may lead to placement errors if significant pelvic asymmetry is present in each patient.
Obstetric Changes	Tobolsky et al. 2016 [10]	Original article: observational, cross-sectional study	The varying patterns of asymmetry uncovered are consistent with prior work and may indicate that loading from the trunk and legs place differing stresses on the pelvis and canal, leading to unequal asymmetries. However, this is speculative, and the potential influence of genetics, biomechanics, and nutritional status on the development of pelvic and canal asymmetries presents a rich area for future study.
	Kurki et al. 2017 [14]	Original article: observational, cross-sectional study	Biomechanical loading of the pelvic girdle may influence asymmetry in both the canal and non-canal aspects of the pelvis; however, it is unlikely that these asymmetries negatively affect obstetric function, given the prevalence and directional percentages found in this study.
	Morino et al. 2019 [47]	Original article: observational, prospective, longitudinal cohort study	Some changes in pelvic alignment occur continuously during the perinatal period. Changes in the anterior width of the pelvis are not recovered one-month post-childbirth. Understanding these perinatal changes may help clinicians prevent complications due to pelvic misalignment.

Table 2. Synthesis of studies according to clinical manifestations.

Clinical Manifestation	Author/Year	Type of Study	Outcomes
Low Back Pain	Devan et al. 2015 [28]	Systematic Review	Limited studies specifically investigate spinal and pelvic asymmetries during walking and other functional tasks in individuals with transfemoral and transtibial amputation.
	Yu et al. 2020 [8]	Original Article: observational, cross-sectional study	Two pelvic parameters were associated with the presence of non-specific chronic low back pain.
	Handrich et al. 2021 [4]	Original Article: observational, cross-sectional study	The pelvic ring, known for its complexity, has been shown not to be entirely symmetric. Six distinct pelvic ring asymmetries were identified in different anatomical regions.
	In et al. 2021 [31]	Original Article: observational, cross-sectional study	Pelvic asymmetry showed no significant difference between the sitting time and groups. Using a smartphone during prolonged sitting may lead to a slumped posture; these associations were more pronounced in adolescents with low back pain.
	Alcaraz-Clariana et al. 2022 [25]	Original Article: observational, test–retest study	Sequenced movements can modify muscle tone and stiffness as a function of age. Muscle mechanical properties should be assessed not only at the beginning of the physical examination at rest but also throughout the patient’s follow-up, considering their pain and age, in a clinical setting.
Scoliosis	Haleem et al. 2018 [37]	Narrative Review	Idiopathic scoliosis is a diagnosis of exclusion. The observed deformity could involve either spine/prominence ribs or asymmetry of the pelvis/shoulders. Treatment aims to halt curve progression and support lung development. In young child, growth modulation is the aim of treatment. Definitive surgery for idiopathic scoliosis is performed at skeletal maturity.
	Liu et al. 2019 [35]	Original Article: observational, cross-sectional study	Concave paravertebral muscle tone and stiffness were greater than those on the convex side in adolescents with idiopathic scoliosis. The asymmetric biomechanical characteristics of paravertebral muscles are closely related to the severity of scoliosis and the presence of pelvic asymmetries.
	Ren et al. 2024 [3]	Original Article: observational, cross-sectional study	Although there are differences in overall pelvic shape between sexes and ancestries, there is no relationship between these variables and pelvic asymmetry in the axial or sagittal planes in young adult osteological specimens.
	Colonna et al. 2024 [22]	Narrative Review	Scoliotic discrepancies should be compensated (conservatively or surgically) only when the imbalance of the femoral heads is on the same side as the imbalance of the sacrum and the iliac crests. This corrective action should result in a reduction in the overhang in the coronal plane.
Post-Traumatic Pelvic Dysfunctions	Cano-Luís et al. 2018 [45]	Narrative Review	The main cause of nonunion and pelvic deformity following pelvic fracture is the inadequate initial treatment of the fracture. Surgical approaches, reduction maneuvers and fixation techniques must be carefully planned, and the use of 3D printing at real size is very helpful in this regard.
	Mennen et al. 2022 [43]	Narrative Review	The field of pediatric pelvic surgery is currently does not fully grasp the complexity of the pediatric pelvic fractures, highlighting the need for a pediatric pelvic classification system and evidence-based treatment guidelines. Functional outcomes seem to be correlated with the frequency of pelvic asymmetry, likely due to an underestimation of the stability of the pelvic fracture.
	O’Callaghan et al. 2023 [9]	Original article: observational, retrospective study	Current computer-assisted surgery THR software reports measurements of global offset and hip length without considering pelvic asymmetry. Surgeons are not provided with confidence ranges to represent the potential impact of asymmetry on these measurements. Relying on these numbers to guide implant position may lead to placement errors if significant pelvic asymmetry is present in each patient.
Obstetric Changes	Tobolsky et al. 2016 [10]	Original article: observational, cross-sectional study	The varying patterns of asymmetry uncovered are consistent with prior work and may indicate that loading from the trunk and legs place differing stresses on the pelvis and canal, leading to unequal asymmetries. However, this is speculative, and the potential influence of genetics, biomechanics, and nutritional status on the development of pelvic and canal asymmetries presents a rich area for future study.
	Kurki et al. 2017 [14]	Original article: observational, cross-sectional study	Biomechanical loading of the pelvic girdle may influence asymmetry in both the canal and non-canal aspects of the pelvis; however, it is unlikely that these asymmetries negatively affect obstetric function, given the prevalence and directional percentages found in this study.
	Morino et al. 2019 [47]	Original article: observational, prospective, longitudinal cohort study	Some changes in pelvic alignment occur continuously during the perinatal period. Changes in the anterior width of the pelvis are not recovered one-month post-childbirth. Understanding these perinatal changes may help clinicians prevent complications due to pelvic misalignment.

Significant obstetric changes occur in bone alignment, particularly in the pelvis, which are crucial for load transfer during daily activities. As body weight increases by over 10 kg in 40 weeks, the pelvis tilts forward, resulting in varying degrees of pelvic anteversion between sides [47]. The anterior part of the pelvis may take longer to recover compared to the posterior, potentially indicating to pelvic dysfunction and asymmetries [48]. Hormonal and fascial changes also occur, leading to pelvic asymmetries with increased elasticity, causing sacroiliac joint instability. Combined with alterations in the morphology of the symphysis and pubic bone due to parity and aging [10], this can disrupt load transfer through the lumbopelvic region, since asymmetries caused by aging in cadavers are well defined [49].

One of the most significant obstetric origins of pelvic asymmetries is episiotomy [50] (Figure 4), which is commonly performed on the right side, although its impact on pelvic asymmetries is not well documented [51]. Evidence also suggests that multiparous women exhibit more tension and less elasticity and viscoelastic properties in the left side of deep pelvic floor muscles [39]. In the clinical setting, management is primarily centered on pelvic floor exercises, which may be initiated in the immediate postpartum period. Additionally, abdominal wall strengthening exercises are utilized to reduce the incidence of rectus abdominis diastasis in women following both vaginal and cesarean deliveries, although adherence to exercise regimens typically declines postnatally [52]. However, there remains a lack of a standardized clinical protocol for addressing pelvic asymmetries induced by obstetric changes. In summary, assessing pelvic alignment during and after pregnancy is useful for evaluating the perinatal risk of lumbopelvic disorders in women and for developing appropriate treatments for pelvic asymmetries [47,53].

3.2. Clinical Evaluation

Clinical evaluation of pelvic asymmetries is significant for a comprehensive approach and prevention of various clinical conditions. Asymmetry is a dynamic process where local asymmetry can transform into generalized asymmetry, and functional asymmetry can evolve into structural asymmetry and vice versa. This complexity it challenging to determine the precise basis of asymmetry and its diagnosis [7]. In fact, no clinical methods provide a comprehensive basis for advanced diagnoses or support therapeutic decisions. Most information comes from radiological examinations of the pelvic girdle, which are used to develop diagnostic schemes and therapeutic recommendations due to their reliability, reproducibility, and accuracy. Additionally, palpation-based methods of pelvic girdle landmarks are used, although there are less reliable and exhibit greater variability [2].

3.2.1. Physical Examination

Traditional methods for studying the human pelvis have primarily focused on the physical assessments, including visual inspection and palpation. However, these methods have demonstrated poor reliability and are generally not recommended for clinical practice. In contrast, quantitative clinical measurement methods, such as the manual evaluation of iliac crest height [22], are considered simple, quick, and low cost [3].

Combining pain provocation tests has shown good diagnostic utility for detecting sacroiliac joint pain. A group of four to five tests, including the distraction test, the femoral shear test, the sacral thrust test, and the compression test, combined with an assessment using McKenzie-type repetitive movements, seems to offer the best diagnostic utility (positive likelihood ratio of 6.97) and is therefore recommended [54]. Nevertheless, there is no consensus in the literature regarding the validity and reliability of clinical evaluation methods due to variability in accurately identifying bony landmarks and, consequently, pelvic asymmetries [22].

3.2.2. Imaging Methods

In the past decade, several methods have been developed to perform precise postural evaluations during standing and detect possible pelvic asymmetries. Technological advances have led to the use of highly reliable and user-friendly tools, such as X-ray scanners, with the Raimondi method being the most widely used for quantifying axial vertebral rotation due to its reproducibility and ease of use [55], and computerized photographic systems, for assessing postural asymmetry. X-ray images are the standard method for evaluating spinal alignment because they provide clear images of anatomical landmarks [56]. However, they are not preferred for routine clinical and research procedures due to radiation exposure. Instead, computerized photographic systems are recommended for evaluating posture using anatomical landmarks, like the Formetric 4D rasterstereography [57] offer potential alternatives to X-rays for monitoring spinal deformities, though they need further research for validate their results. These systems are simple, non-invasive, affordable, and radiation-free [8], and they offer accurate measurements even in the presence of angular deformities, though their economic cost is higher. Magnetic resonance imaging is also used, providing the advantage of no radiation risks; however, it is expensive and has shown lower reproducibility and accuracy compared to computed tomography or ultrasound [22].

3.2.3. Latest Advancements

Recently, three-dimensional (3D) modeling and MRI have been utilized for anatomical studies of the pelvis [58]. 3D technology has proven highly accurate in reconstructing osteological samples, allowing the creation of exact and precise replicas of a patient’s bone anatomy for detail analysis [4,8], all without exposure to ionizing radiation [22]. In contrast, the accuracy of assessing hip kinematics using conventional marker-based motion capture is limited by soft tissue artifacts. To address this limitation, some researchers have begun employing high-precision biplane radiography technique combined with model-based tracking to evaluate the in vivo movement of the femur and pelvis [13].

Innovative methods include virtual and augmented reality, which integrate computer and imaging technologies. These technologies are increasingly used for preoperative simulation and training related to hip procedures, intraoperative navigation tools in the operating room, and postoperative rehabilitation [59]. Their impact on pelvic asymmetries is also being explored. Additionally, innovative methods such as Inertial Measurement Units, which are wireless and non-invasive, are being used to measure kinematics and assess lumbopelvic asymmetries [60].

Currently, more precise methods than digital palpation exist for evaluating the mechanical properties of the musculature involved in pelvic asymmetries. In this regard, elastography allows for real-time visualization and quantification of tissue stiffness and is known for its reliable and reproducible. This novel ultrasound-based technique allows for detailed assessment of the viscoelastic properties of soft tissues [61]. Another notable method is myotonometry, which measures muscle tone characteristics by applying a mechanical impulse to the tissue at rest or during isometric contraction [39,62].

Table 3. Synthesis of studies according to clinical evaluation.

Clinical Evaluation	Author/Year of the Study	Study Population	Outcomes
Physical Examination	Jedra et al. 2022 [7]	22 children (12 girls, 10 boys) aged 7 years	The development of pelvic girdle asymmetry is influenced by the increasing number of asymmetrically performed movements and asymmetric body positions assumed, which increase in number with age. The most notable increase in spinal asymmetry in individuals with an oblique/rotated pelvis is observed in the lumbar spine, demonstrating an association between pelvic girdle and spinal asymmetry.
	Bibrowicz et al. 2023 [2]	300 young individuals	Pelvic asymmetries are common, observed in less than three-quarters of the examined population. An oblique pelvis was found in less than a quarter of women and in more than a third of men, with structural asymmetries being predominant. A rotated pelvis was observed in more than a third of both women and men, with functional asymmetries being more common.
Imaging Methods	Colonna et al. 2024 [22]	Individuals with scoliosis, encompassing both adolescents and adults	From a clinical perspective, the focus is on the compensatory mechanisms employed by the pelvis in response to structural or functional leg length asymmetries, in order to guide therapeutic decisions.
Latest Advancements	Yu et al. 2020 [8]	28 individuals diagnosed with non-specific chronic low back pain and 28 controls	Measuring pelvic asymmetry may assist in the early identification of potential non-specific chronic low back pain, but further work is required.
	Handrich et al. 2021 [4]	A series of 150 protocols of European and Asian males and females were post-processed	Assessing pelvic asymmetry can be challenging. Techniques such as CT-based 3D statistical modeling and principal component analysis are used to address these challenges.
	Frawley et al. 2021 [62]	Consensus report of the International Continence Society (ICS) Working Group 16	A consensus-based Terminology Report for the assessment of pelvic floor muscles PFM function and dysfunction aims to aid clinical practice and stimulate further research.
	Johnson et al. 2022 [13]	24 asymptomatic young adults (13 women, 11 men)	Sex-based differences in hip kinematics during walking are minimal. Rotational asymmetry during walking is greater, but translational asymmetry is smaller compared to the knee and ankle. Additionally, asymmetry is greater during squatting than during walking.

Table 3. Synthesis of studies according to clinical evaluation.

Clinical Evaluation	Author/Year of the Study	Study Population	Outcomes
Physical Examination	Jedra et al. 2022 [7]	22 children (12 girls, 10 boys) aged 7 years	The development of pelvic girdle asymmetry is influenced by the increasing number of asymmetrically performed movements and asymmetric body positions assumed, which increase in number with age. The most notable increase in spinal asymmetry in individuals with an oblique/rotated pelvis is observed in the lumbar spine, demonstrating an association between pelvic girdle and spinal asymmetry.
	Bibrowicz et al. 2023 [2]	300 young individuals	Pelvic asymmetries are common, observed in less than three-quarters of the examined population. An oblique pelvis was found in less than a quarter of women and in more than a third of men, with structural asymmetries being predominant. A rotated pelvis was observed in more than a third of both women and men, with functional asymmetries being more common.
Imaging Methods	Colonna et al. 2024 [22]	Individuals with scoliosis, encompassing both adolescents and adults	From a clinical perspective, the focus is on the compensatory mechanisms employed by the pelvis in response to structural or functional leg length asymmetries, in order to guide therapeutic decisions.
Latest Advancements	Yu et al. 2020 [8]	28 individuals diagnosed with non-specific chronic low back pain and 28 controls	Measuring pelvic asymmetry may assist in the early identification of potential non-specific chronic low back pain, but further work is required.
	Handrich et al. 2021 [4]	A series of 150 protocols of European and Asian males and females were post-processed	Assessing pelvic asymmetry can be challenging. Techniques such as CT-based 3D statistical modeling and principal component analysis are used to address these challenges.
	Frawley et al. 2021 [62]	Consensus report of the International Continence Society (ICS) Working Group 16	A consensus-based Terminology Report for the assessment of pelvic floor muscles PFM function and dysfunction aims to aid clinical practice and stimulate further research.
	Johnson et al. 2022 [13]	24 asymptomatic young adults (13 women, 11 men)	Sex-based differences in hip kinematics during walking are minimal. Rotational asymmetry during walking is greater, but translational asymmetry is smaller compared to the knee and ankle. Additionally, asymmetry is greater during squatting than during walking.

3.2.4. The Utility of Diagnostic Tools for Managing Pelvic Asymmetries in the Clinical Setting

These diagnostic tools allow the identification case-specific structural and functional abnormalities should be case specific, supporting the development of personalized, evidence-based treatment strategies. Consequently, diagnostic methods for identifying hemipelvic anteversion and pelvic asymmetries in patients with low back pain include a combination of visual inspection, palpation of the iliac crests and anterior-posterior iliac spines [63] and specific tests, i.e., Patrick test, that are used to assess the hip and sacroiliac joint. Imaging methods such as X-rays are also used to identify pelvic tilt and spinal alignment, while computed tomography and magnetic resonance imaging provide a more detailed view of the pelvis and displacement of the sacroiliac joint [64].

The diagnosis used for detecting the spiral pelvis pattern and other pelvic asymmetries in scoliosis includes a clinical evaluation through visual inspection and palpation to identify asymmetries in the iliac crests, pelvic rotation, and spinal deviations, as well as the Adams test, which is a simple but subjective method. The primary imaging diagnostic tool is spinal radiography, with the Raimondi method being used for quantifying axial vertebral rotation [55]. Complementary imaging techniques, such as computed tomography and magnetic resonance imaging, can also be employed [65].

In pelvic trauma associated to pelvic asymmetries, the diagnostic tools also consist of a physical examination, including pain provocation tests through palpation of the iliac crests, pubis, and sacroiliac joint. Additionally, an assessment of pelvic instability is conducted through passive mobilizations using compression and distraction tests [54]. Various imaging methods are also used to provide more specific information about the extent of the fracture [42].

To assess pelvic asymmetries following childbirth, the evaluation of signs and symptoms through inspection and palpation, manual examination of tissue integrity, and assessment of potential asymmetries are applied. Additionally, functional tests are performed to evaluate the contraction and relaxation capacity of the pelvic floor muscles [66]. However, other affected areas, such as connective tissues, are not typically diagnosed in current clinical practice, requiring alternative technologies. In this sense, ultrasound and elastography offers a simple, cost-effective, and non-invasive method to evaluate birth trauma and associated conditions, such as episiotomy, through tomographic imaging [67].

3.3. Future Approach

Pelvic asymmetry is a common morphological feature that require innovations in assessment and therapeutic approaches. The management of pelvic asymmetries requires collaboration across multiple disciplines through a therapeutic alliance among healthcare professionals within a biopsychosocial care model. This approach allows to provide a comprehensive patient care, optimizing treatment, and improving clinical outcomes [68].

New diagnostic techniques are needed to specifically address pelvic asymmetries in the various involved structures. A comprehensive clinical and radiological study of the patient is essential to develop an effective and multidisciplinary therapeutic plan [45]. Enhanced diagnostic tools, such as artificial intelligence and 3D imaging, will enable more accurate and early detection of pelvic asymmetries and will determine their relationship with other disease features. Innovations in minimally invasive surgical techniques, personalized rehabilitation and orthotic devices, and wearable technology for real-time monitoring will improve treatment outcomes and patient comfort.

Therefore, it should be recognized that insufficient knowledge in addressing pelvic asymmetries, as well as a poor understanding of the basic pathophysiological mechanisms, can lead to erroneous considerations and the implementation of inappropriate therapeutic procedures that may jeopardize the health and life of the patient [69]. The implementation of randomized controlled trials is paramount for advancing the understanding of the impact of pelvic asymmetries on conditions such as low back pain, scoliosis, post-traumatic pelvic dysfunctions, and obstetric alterations. These trials will determine the efficacy of therapeutic interventions aimed at correcting these asymmetries and alleviating associated symptoms.

4. Conclusions

Pelvic asymmetry is a prevalent functional and morphological feature with important clinical implications for assessment and treatment strategies. Pelvic asymmetries are involved in low back pain, scoliosis, and post-traumatic pelvic dysfunctions. Nevertheless, no randomized clinical trial has been specifically designed to restore pelvic symmetry in these disorders. Future improvements in diagnostic tools, such as artificial intelligence and 3D imaging, will enhance early detection and accuracy. An inadequate understanding of pelvic asymmetries and their pathophysiological mechanisms can lead to incorrect treatment decisions, potentially endangering patient health and safety.