Pelvic, trunk and upper limb biomechanics during walking in individuals with spinal deformities: a systematic review and meta-analysis

Abstract

Background

Spinal deformities represent a major public health concern, characterized by abnormal curvature and alignment of the spine. We aimed to investigate the alterations in pelvic, trunk, and upper limb biomechanics during walking in individuals with spinal deformities compared to healthy controls.

Methods

We searched four databases including PubMed, Web of Science, Scopus and Embase from their inception through 2nd january 2025. Two authors screened studies and separately extracted data from included studies. The Newcastle–Ottawa Scale was applied to assess quality of included studies. GRADE was employed to assess the overall quality of the evidence in the meta-analysis. Subgroup and sensitivity analyses were performed to address potential heterogeneity. Mean differences and 95% confidence intervals (CI) were calculated with random effects model in RevMan version 5.4.

Results

Seventeen studies with a total of 893 participants were included in the systematic review. In scoliosis, meta-analysis showed strong evidence of increased thorax-pelvis sagittal ROM, strong evidence of non-significant increase in SVA, moderate evidence of increased pelvic frontal ROM, sagittal thoracic curve ROM, CVA, and moderate evidence of non-significant change in 3-dimensional thorax movement, sagittal lumbar ROM, thorax-pelvis frontal and transverse ROM compared to controls during walking. The meta-analysis for other variables related to scoliosis indicated moderate evidence of non-significant changes. Meta-analysis showed moderate evidence of increased sagittal pelvic ROM in sagittal trunk malalignment, and moderate evidence of non-significant increase in pelvic ROM in adult spinal deformities compared to controls during walking.

Conclusion

This review highlights the complexity of pelvic, trunk and upper limb biomechanics in individuals with spinal deformities. Understanding these alterations is essential for creating targeted interventions and improving clinical outcomes.

Trial registration

The protocol was registered with PROSPERO (CRD42024602489).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-025-06063-w.

Introduction

Spinal deformities are a significant public health issue, defined by abnormal curvature and alignment of the spine [1]. Adult scoliosis occurs in skeletally mature individuals with a coronal Cobb angle greater than 10°. It can be idiopathic or degenerative, often resulting from age-related changes like disc degeneration and vertebral fractures [2]. Adolescent idiopathic scoliosis (AIS) affects about 1–4% of adolescents [3], with a prevalence of 0.47–5.2%, mainly in girls [4], and is seen in 1–3% of those aged 10 to 16 [3]. Adult spinal deformities (ASD) include various three-dimensional conditions such as scoliosis, kyphosis, and sagittal imbalance [5], affecting 2–32% of adults and up to 68% of older adults [6]. Kyphosis features excessive outward thoracic curvature, while lordosis involves an exaggerated inward lumbar curve. These deformities can lead to progressive issues, causing pain, neurological symptoms [7], and functional limitations, including ongoing discomfort, difficulties with posture, balance problems, and an increased risk of falls [8].

Spinal deformities such as scoliosis, and sagittal malalignment significantly impact gait biomechanics [9], leading to inefficient movement and increased energy expenditure [10]. Individuals with scoliosis often exhibit abnormal gait patterns, including decreased frontal pelvic tilt [11] and increased coronal vertical angle (CVA) [12, 13], which correlate with the severity of their spinal curvature. Sagittal malalignment leads to compensatory mechanisms like increased sagittal vertical axis (SVA) and increased pelvic range of motion (ROM), resulting in abnormal gait and altered joint kinematics [14]. The abnormal walking biomechanics may contribute to chronic pain conditions like lower back pain [15], hip pain [16], and sciatica [17]. Furthermore, kyphosis exacerbates these issues by increasing mean sagittal thorax angle during gait, further destabilizing the spine and affecting overall mobility [15] which may increase the risk of injuries by placing abnormal stress on joints and muscles [18].

Despite the growing recognition of the issues regarding dynamic spinal alterations in individuals with spinal deformities, no systematic reviews or meta-analyses was found specifically addressing upper limb biomechanics during walking in individuals with spinal deformities. Therefore, our aim was to systematically review studies that assess upper limb biomechanics during walking in populations with various spinal deformities, including scoliosis, lordosis, kyphosis, and another sagittal malalignment. We hypothesised that pelvic, trunk and upper limb biomechanics during walking is different between subject with spinal deformities and healthy controls. By synthesising existing literature on this topic, we hoped to enhance understanding of how these conditions influence gait mechanics and inform future clinical practices aimed at improving individual outcomes. This assessment was essential for tailoring gait retraining plans monitoring treatment effectiveness that address specific alignment issues, making it imperative to consider these factors for enhancing patient outcomes.

Methods

This systematic review was conducted in accordance with the PERSiST guidelines set for systematic reviews [19] and the protocol was registered with PROSPERO (CRD42024602489).

Search strategy

We identified relevant studies using four electronic databases: PubMed, Web of Science, Scopus, and Embase. The search was conducted on 2nd January 2025. The key terms used in our search strategy comprised broad terms categorized into three specific groups:

1. malalignment OR kyphosis OR lordosis OR “flat back” OR “sway back” OR “forward head” OR “upper cross syndrome” OR spinal or “spinal deformity” OR deformity OR scoliosis OR scoliotic.

2. pelvis OR pelvic OR trunk OR thorax OR cervical OR head OR thoracic OR thoracolumbar OR lumbosacral OR lumbar OR shoulder OR “arm swing” OR “kyphosis angle” OR “lordosis angle” OR “range of motion” OR moment OR angle.

3. walk

4. (1 AND 2 AND 3)

We conducted a manual search of reference lists from previous studies, relevant systematic reviews, and Google Scholar concerning upper limb biomechanics in individuals with spinal deformities during walking, aiming to ensure a thorough identification of all relevant studies.

Eligibility criteria

Independent searches were conducted based on predefined inclusion criteria and data extraction forms. Full-text articles were evaluated according to specific inclusion criteria, which necessitated a comparison of upper limb biomechanics during walking between healthy individuals and those with spinal deformities. The studies included were limited to those published in English and required abstracts that examined upper limb biomechanics in both groups. Exclusions were made for non-English publications, studies focusing solely on individuals without spinal deformities, those that did not report on upper limb biomechanics, studies lacking a control group of healthy participants, as well as those concentrating on spinal injuries or post-operative outcomes, and articles classified as e-posters, conference abstracts, or unavailable research papers.

Study selection

The review of titles, abstracts, and full texts was carried out by FK and SHM independently following the predetermined inclusion criteria. In instances of disagreement, the two authors conferred on the manuscript to reach a consensus.

Quality assessment

FK and SHM assessed the methodological quality of the included studies using the Newcastle–Ottawa Scale, which was specifically modified for cross-sectional studies (with scores classified as poor, fair, and high for ≤ 4, 4–6, and ≥ 7, respectively) [20]. However, since the responsiveness criterion was not relevant to our studies, the overall score was deemed to be 8. The Grading of Recommendations Assessment, Development and Evaluation (GRADE system) [21] was utilized to investigate the total quality of the evidence in the meta-analysis.

Data collection

Data extraction from the selected studies was carried out by (FK) and subsequently verified by (SHM). This review concentrated on extracting biomechanical data related to the upper limb. To maintain consistency, the data were organized by the type of spinal deformity in the Results and Discussion sections. Extracted variables included radiographic features, study design, sample size, participant characteristics (age, sex, height, mass, BMI), tools, funding, outcomes, type of deformity.

Synthesis of results

Mean differences or standardized mean differences, along with 95% confidence intervals (CIs), were computed using a random effects model in RevMan version 5.4. A meta-analysis was conducted when a minimum of two studies evaluated the same outcome measure with comparable methodologies. The statistical heterogeneity of the combined data was assessed using I² statistics and their corresponding P-values (P < 0.05). To assess the impact of each study and the robustness of the final results, a sensitivity analysis [22] was performed by sequentially excluding individual studies from the analysis. The results were analyzed based on the levels of evidence established by van Tulder et al. [23] modified by Mousavi et al. [24] (Table 1).

Table 1.

Definitions of modified level of evidence

Level of evidence	Description
Strong evidence	Pooled results from three or more studies, including a minimum of two high-quality studies which are statistically homogenous (p > 0.05)- may be associated with a statistically significant or non-significant pooled results
Moderate evidence	Statistically significant pooled results from multiple studies, including at least one high-quality study, which are statistically heterogeneous (p < 0.05); or from multiple low- or moderate-quality studies which are statistically homogenous (p > 0.05); or statistically insignificant pooled results from multiple studies, including at least one high-quality study, which are statistically homogenous (p > 0.05)
Limited evidence	Results from multiple low- or moderate-quality studies which are statistically heterogeneous (p < 0.05); or from one high-quality study
Very limited evidence	Results from one low- or moderate-quality study
Conflicting evidence	Pooled results that are insignificant and from multiple studies, regardless of quality, which are statistically heterogeneous (p < 0.05, i.e., inconsistent)

Results

Study selection

The main literature search yielded a total of 8247 items: PubMed (1362 studies), Web of Science (2140), Scopus (2475) and Embase (2270) from which 2215 items remained after duplicate removal. We excluded 2201 studies due to not meeting the inclusion criteria and included 14 studies after screening of titles and abstracts for further eligibility check. Three studies added by hand search; a total of 17 studies were included. Figure. 1 shows the flow diagram of the selection process and number of excluded studies at each stage.

Fig. 1.

Flow chart of study selection process

Study characteristics

Table 2 summarizes the characteristics of the included studies. Twelve studies examined the impact of scoliosis, one study investigated the effects of kyphosis and lordosis, one study assessed both sagittal malalignment and scoliosis, one study assessed both ASD and scoliosis, and three studies analyzed the influence of ASD on upper limb biomechanics. Total sample size of included studies was 460 in experimental and 433 in control groups.

Table 2.

Study characteristics

Authors	Type	Radiograph	Outcomes	Sample size	Age	Height (cm)	Weight (kg)	BMI (kg/m2)	Measurement tools	Study design	Funding and conflict of interest
Mahaudens et al. 2005	Idiopathic Scoliosis	X-ray evidence of progressive idiopathic scoliosis with a lumbar or thoraco-lumbar curve	Pelvic maximum up/downward position, anteroposterior tilt, in/external rotation	E: 12, C: 12	E: 13.2 ± 0.8, C: 12.9 ± 0.9	E: 156 ± 11, C: 158 ± 11	E: 41.2 ± 0.8, C: 46.4 ± 9		4 infrared cameras	Case–control	None
Delpierre et al. 2019	Idiopathic Scoliosis	E: Cobb angle: 56	Thorax, thorax-pelvis, pelvis 3D ROM	E: 4 males, 18 females, C: 4 males, 18 females	E: 16.9 ± 3.1, C: 18.5 ± 0.8	E: 162.4 ± 8.4, C: 169.5 ± 8.1	E: 52.1 ± 8.4, C: 60.8 ± 9.6		Vicon motion capture and Nexus software	retrospective study	None
Huysmans et al	Idiopatic and de novo scoliosis	Indication for spinal fusion, idiopatic or de novo scoliosis	Trunk tilt, lateroflexion and rotation, pelvic tilt, rotation and obliquity	E: 24, C: 50	E: 20, C: 22	E: 171 C: 173	E: 68.5, c: 70.3		12 cameras, Vicon 100 Hz	observational retrospective case–control	None
Schmid et al. 2016	Adolescent Idiopathic Scoliosis	both a thoracic and a thoracolumbar/lumbar curve component	Thoracic Curves, Thoracolumbar/lumbar Curves (sagittal and frontal), pelvis, lumbar, thoracic, cervical, thoracic vs pelvis (sagittal, frontal and transverse)	E: 2 males, 12 females, C: 8 males, 7 females	E: 15.2, c: 1.62	E: 152, c: 162	p; 55.6, c: 54.2		12 Vicon 200- 300 Hz	Cross sectional observational study	None
Wu et al. 2019	Adolescent Idiopathic Scoliosis	Lenke 1: Cobb angles 52.7° ± 10.5°	Lumbosacral extensor, Lumbosacral lateral flexor peak muscle moment, pelvis-global (anteroposterior tilt, contra/ipsilateral rotation, up/downward list), trunk-pelvis (sagittal, contra/ipsilateral rotation, ipsi/contralateral frontal), trunk-global (anteroposterior tilt, contra/ipsilateral rotation, up/downward list, lumbar sagittal & ipsi/contralateral frontal)	E: 16 female, C: 16 female	E: 14.9 ± 1.7, C: 14.8 ± 2.7	E: 154.7 ± 5.0, C: 154.9 ± 5.6	E: 41.7 ± 7.2, C: 44.7 ± 6.3		8-camera, Vicon 120 Hz	Case–control	Financial support (NSC98-2320-B-039–041) by National Science Council, Taiwan
Tekin et al. 2023	Adolescent Idiopathic Scoliosis	Single or double curve pattern	Right and left, max and ROM, for arm swing angle	E: 7 male, 19 Female, C: 8 male, 13 female	E:14.9 ± 2.6, C: 14.5 ± 3.2	E:163.6 ± 11.2, C:156.7 ± 19.7	E: 51.9 ± 11.4, C:50.7 ± 19.1	E: 19.2 ± 2.9, C: 19.7 ± 3.6	smartphone camera, Kinovea	Case–control	None
Haddas et al. 2018	Adult degenerative scoliosis	Cobb Angle > 25°	Pelvic & trunk ROM	E: 20, C: 15	E:62.71 ± 6.9, C: 55.01 ± 6.1	E: 164 ± 0.1, C:171 ± 0.1	E:79.37 ± 22.2, C:72.14 ± 15.7		10 cameras, Vicon Nexus 2.0 Inc	Case–control	None
Engsberg eta al. 2003	Lumbar scoliosis	Fixed and not fixed sagittal imbalance	3D shoulder-pelvis mean and ROM, SVA-G, CVA-G	E: 8 Females, C: 9 Females	49 ± 10				6 camera HiRes Motion 6 Analysis Cor- poration System 60 Hz	Case–control	None
Park et al. 2015	Adolescent Idiopathic Scoliosis	Cobb angle > 10°	3D pelvic ROM	E:39, C:30 female	E: 15.1 ± 2.1, C: 14.8 ± 2.7	E:155.2 ± 8.2, C: 154.9 ± 5.6	E: 45.6 ± 9.5, C: 44.7 ± 6.3		Vicon motion analysis system (six-camera system 460, 120 Hz, Vicon Motion Systems, Oxford, UK)		Supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (No. NRF-2013R1A1A2009495). No competing interests
Mar et al. 2020	progressive and symptomatic degenerative scoliosis	PI-LL (none: < 10˚, moderate: 10 − 20˚, marked: > 20˚), SVA (none: < 40 mm, moderate: 40–95 mm, marked: > 95 mm), and PT (none: < 20˚, moderate: 20 − 30˚, marked: > 30˚). Mild was defined by only “none” or “moderate” sagittal modifiers whereas Severe was defined as one or more “marked” sagittal modifiers	CVA, SVA, TPA, LL, PT ROM	E:40 female, 12 male, C: 25 female, 21 male	E: 58.1 ± 15.8, C: 43 ± 14	E: 160 ± 10, C: 170 ± 10	E: 71.0 ± 18.6, C: 73.9 ± 15.8	E: 26.8 ± 5.1, C: 24.8 ± 3.5	three dimensional (3D) motion tracking system (Vicon, Oxford, UK)	Retrospective review at a single institution	None
Miko et al. 2001	Adolescent Idiopathic Scoliosis	Cobb angle: 10°−45°	Load at apical vertebra (force & moment)	P:18, C:8 female	P: 14.3 ± 1.4, C: 14.8 ± 1.3				Vicon 370		None
Mahaudens et al. 2009	Adolescent Idiopathic Scoliosis	Cobb angle ≥ 40	3D pelvis and shoulder ROM, pelvis velocity	P:16, C:13 female	P: 14–17, C: 15–16	163.4 (8.5), C: 164.3 (4)	P: 50.2 (7.1), C: 54.7 (2.9)	P: 18.8 (2.1), C: 20.2 (1)	6 infrared cameras (BTS, Italy), 100 Hz	Case–control	Supported by Orthopedie Van Haesendonk firm
yagi et al. 2016	ASD (combined frontal and sagittal)	main-curve Cobb angle > 20° or a C7 sagittal vertical axis (SVA) > 5 cm	Thoracolumbar kyphosis, pelvis angle	E: 33 Females, C: 33 Females	E: 22.8 ± 2.5, C: 23.9 ± 2.5	E:150.9 ± 7.9, C:148.9 ± 04.7	E: 52.5 ± 2.5, C: 53.3 ± 7.3	E: 22.8 ± 2.5, C: 23.9 ± 2.5	Camera	Prospective case series	None
Kawkabani et al. 2021	ASD (combined frontal and sagittal)	Any of the (PT > 25˚, SVA > 50 mm, Cobb angle > 20˚, and/or TK > 60˚)	Trunk 3D, L1L3-L3L5, T10L1-L1L3, T10L1-T2T10, T2T10-C7T2, pelvic tilt, obliquity and rotation	E:13 males, 39 females, C: 31 males, 32 females	E: 43 ± 21, c: 40 ± 12	E: 163 ± 11, c: 167 ± 9	E: 71 ± 16, c: 72 ± 14		8 cameras, Vicon 200 Hz	retrospective study	Funded by the University of Saint-Joseph (grant FM361) and EUROSPINE (TFR2020#22). The funding sources did not intervene in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the article for publication
Nassim et al. 2024	ASD (combined frontal and sagittal)	One or more of (PT > 20˚, SVA > 50 mm, Cobb angle > 20˚, pelvic incidence – lumbar lordosis mismatch (PI-LL) > 10˚ and/or T1T12 thoracic kyphosis TK > 60˚)	Thorax & pelvic flexion mean & ROM	E: 124, C: 47	E: 54 ± 19, C: 53 ± 8	E:161 ± 10, C: 165 ± 8	E: 72 ± 14, C: 73 ± 11		8 infrared cameras (Vicon Motion Systems)	Prospective study	funded by the University of Saint-Joseph (grant FM361) and EUROSPINE (TFR 2020#22). The funding sources did not intervene
Severijn et al. 2021	Sagittal or frontal malalignment	Decompensated sagittal malalignment: (SVA ≥ 4 cm with PI-LL > 10˚ and/or PT > 20˚) ± coronal deformity, compensated sagittal malalignmen: (SVA ≤ 4 cm with PI-LL > 10˚ and/or PT > 20˚) ± coronal deformity, frontal malalignmen: (Cobb angle ≥ 20˚)	SVA, kyphosis, Lordosis, pelvis	E:43, C: 18	E: 62 ± 14.3, c: 64.5 ± 15	E:167.5 ± 7.8, c: 160.3 ± 9	E: 66.9 ± 14.1, c: 63.2 ± 13.2	E:23.9 ± 3.4, c: 24.5 ± 5.3	10 cameras, Vicon 100 Hz	Prospective study	KU Leuven C2 funds, Medtronic and a strategic basic research PhD grant (SB/1S56017N) of the Research Foundation − Flanders (FWO)
Semaan et al. 2022	Frontal, kyphosis or sagittal malalignment	PT > 25°, SVA > 50 mm, PI-LL > 10°, Cobb angle > 20° and/or T1T12 > 60°	Mean & ROM sagittal head flexion, sagittal thorax & pelvis-L3-L5, shoulder-pelvis axial rotation, L1L3-L3L5 sagittal, T10L1-L1L3 sagittal, T2T10-T10L1 sagittal, C7T2-T2T10 sagittal, pelvic tilt, obliquity and rotation	E: 119, C: 60	E: 51.5 ± 19.2, c: 48.6 ± 10.1	E:161.9 ± 9.5, c: 166.1 ± 8	E: 72.1 ± 14.5, C: 73 ± 12.7		8 cameras, Vicon 200 Hz	cross-sectional	None

Quality assessment

Table 3 shows the results of quality assessment using Newcastle–Ottawa Scale. The average score of eligible studies was 7.5. Nine studies received a score of 8 [11, 15, 25–31], seven studies scored 7 [13, 14, 32–36], and one study was rated 6 [37]. The overall GRADE system quality of evidence was rated as high, high and moderate quality for scoliosis, ASD and Sagittal malalignment and, respectively (Table 4). No evidence of publication bias was observed in funnel plots.

Table 3.

Results of quality assessment using Newcastle–Ottawa Scale

Authors	Representativeness	Sample size	Non-responsiveness	Tools	Confounding	Blinding	Statistics	Total
Mahaudens et al. [35]	1	0		2	1	2	1	7
Delpierre et al. [25]	1	1		2	1	2	1	8
Huysmans et al. [26]	1	1		2	1	2	1	8
Schmid et al. [37]	1	0		2	0	2	1	6
Wu et al. [33]	1	0		2	1	2	1	7
Tekin et al. [27]	1	1		2	1	2	1	8
Haddas et al. [11]	1	1		2	1	2	1	8
Engsberg eta al. [13]	1	0		2	1	2	1	7
Park et al. [28]	1	1		2	1	2	1	8
Mar et al. [34]	1	1		2	0	2	1	7
Miko et al. 2001	1	0		2	1	2	1	7
Mahaudens et al. [35]	1	0		2	1	2	1	7
yagi et al. [29]	1	1		2	1	2	1	8
Kawkabani et al. [30]	1	1		2	1	2	1	8
Nassim et al. [31]	1	1		2	1	2	1	8
Severijn et al. [14]	1	1		2	0	2	1	7
Semaan et al. [15]	1	1		2	1	2	1	8
								7.470588235

Table 4.

GRADE system quality of evidence

Certainty assessment							№ of patients		Effect		Certainty	Importance
№ of studies	Study design	Risk of bias	Inconsistency	Indirectness	Imprecision	Other considerations	GRADE	placebo	Relative (95% CI)	Absolute (95% CI)
Scoliosis vs Control—Frontal pelvic ROM (°)
5	non-randomised studies	not serious	serious	not serious	not serious	publication bias strongly suspected very strong association all plausible residual confounding would reduce the demonstrated effect dose response gradient	0 cases 0 controls		RR −2.34 (−4.02 to −0.65)	-	⨁⨁⨁⨁ High
							-	0.0%		0 fewer per 1,000 (from 0 to 0 fewer)
Scoliosis vs Control—Sagittal pelvic ROM (°)
7	non-randomised studies	not serious	serious	not serious	not serious	all plausible residual confounding would reduce the demonstrated effect dose response gradient	0 cases 0 controls		RR 0.2 (−0.2 to 0.6)	-	⨁⨁⨁◯ Moderate
							-	0.0%		0 fewer per 1,000 (from 0 to 0 fewer)
Scoliosis vs Control—Transverse pelvis ROM (°)
5	non-randomised studies	not serious	serious	not serious	not serious	publication bias strongly suspected all plausible residual confounding would reduce the demonstrated effect dose response gradient	0 cases 0 controls		RR −0.38 (−1.49 to 0.73)	-	⨁⨁◯◯ Low
							-	0.0%		0 fewer per 1,000 (from 0 to 0 fewer)
Scoliosis vs Control—Sagittal vertical axis (cm)
3	non-randomised studies	not serious	not serious	not serious	not serious	all plausible residual confounding would reduce the demonstrated effect dose response gradient	0 cases 0 controls		RR 1.79 (−0.39 to 3.97)	-	⨁⨁⨁⨁ High
							-	0.0%		0 fewer per 1,000 (from 0 to 0 fewer)
Scoliosis vs Control—Thorax-pelvis sagittal ROM (°) in gait cycle
3	non-randomised studies	not serious	not serious	not serious	not serious	strong association all plausible residual confounding would reduce the demonstrated effect dose response gradient	0 cases 0 controls		RR 0.51 (0.05 to 0.98)	-	⨁⨁⨁⨁ High
							-	0.0%		0 fewer per 1,000 (from 0 to 0 fewer)
ASD vs Control—ROM pelvis (°)
4	non-randomised studies	not serious	serious	not serious	not serious	strong association all plausible residual confounding would reduce the demonstrated effect dose response gradient	0 cases 0 controls		RR 0.56 (−0.05 to 1.16)	-	⨁⨁⨁⨁ High
							-	0.0%		0 fewer per 1,000 (from 0 to 0 fewer)

CI confidence interval, RR risk ratio

Outcomes

Figure 2 shows the graphical abstract of the results of meta-analysis.

Fig. 2.

Graphical abstract of the results of meta-analysis. Thick lines represent strong evidence, thin lines show moderate evidence, and dashed line shows non-significant and solid lines show significant results

Scoliosis

Strong evidence showed significant increase in thorax-pelvis sagittal ROM [12, 25, 37] with high certainty and being stable in sensitivity analysis, and pelvic frontal ROM [11, 25, 28, 36, 37] with high certainty in GRADE assessment. Strong evidence showed non-significant increase in SVA [12–14] which proved to be stable in our sensitivity analysis and high certainty. Moderate evidence showed significant increase in CVA [12, 13], and not-significant change in 3-dimensional thorax movement [25, 37] and sagittal lumbar [12, 37] ROM, thorax-pelvis frontal and transverse ROM [25, 37], thoracic curve sagittal ROM [14, 37]. Besides, conflicting evidence showed non-significant increase in pelvic sagittal [11, 14, 15, 25, 28, 34, 36, 37] with moderate certainty and non-significant decrease in transverse ROM [15, 25, 28, 36, 37] with low certainty in GEADE assessment. Sensitivity analysis by removing the study by Mar et al. 2020 revealed strong evidence of non-significant results for sagittal pelvic ROM and removing Delpierre et al. 2019 revealed strong evidence of non-significant results for pelvic transverse ROM.

Furthermore, there are limited evidence of decreased thorax-pelvis frontal and transverse ROM in stance phase and frontal and transverse ROM in gait cycle, pelvic transverse and frontal ROM in stance phase and transverse ROM in the gait cycle [25], pelvic contra/ipsilateral rotation at initial contact [33], shoulder-pelvis sagittal average angle [13], trunk lateroflexion and ROM, pelvic obliquity, ROM and velocity [26], and increased shoulder-pelvis axial rotation mean and ROM, shoulder-pelvis frontal average angle [13], pelvic tilt ROM and anterior trunk tilt [26] during gait in individuals with scoliosis compared to healthy controls.

Moreover, limited evidence suggests decreased thorax transverse ROM at stance phase [25] and thorax curve sagittal and frontal average and cervical [37] and trunk frontal ROM [11], and increased mean thorax sagittal ROM, mean T2T10-T10L1, thoracolumbar-lumbar frontal average [37], lumbar sagittal ROM in initial contact [33] and frontal ROM average [37], lumbar ipsi/contralateral side bending during initial contact and lumbar sagittal ROM at toe-off [33] during walking in individuals with scoliosis compared to healthy controls.

Limited evidence showed decreased total right arm swing and right arm maximum flexion angle in scoliosis individuals compared to control during walking [27]. Limited evidence showed decreased significant frontal shoulder ROM and non-significant increase in sagittal and decrease in transverse ROM [36].

Limited evidence showed increased peak lumbosacral extensor and lateral flexor moment in the gait cycle on the concave side [33] and decreased maximum right side axial force and second peak of right side axial moment [32] in scoliosis individuals compared to control during walking (see Fig. 3).

Fig. 3.

Results of meta-analysis for pelvis and upper limb biomechanics during walking in individuals with Scoliosis vs Control (a-d) and sensitivity analysis (e)

Adult spinal deformity

Result showed moderate evidence of non-significant increase in pelvic ROM [14, 29, 30, 38] with high certainty in ASD vs healthy controls during walking. However, sensitivity analysis revealed strong evidence of significant increase in pelvic ROM by removing the study by Nassim et al. 2024 and strong evidence of non-significant change by removing the stud by Yagi et al. 2016.

Conflicting evidence showed decreased non-significant change in mean pelvic tilt [38]. Moreover, there are limited evidence of increased mean thorax [38] and trunk [30] sagittal ROM, minimum and maximum thoracolumbar kyphosis [29], mean L1L3-L3L5 sagittal ROM [30], maximum and minimum pelvic tilt [29] (see Fig. 4).

Fig. 4.

Results of meta-analysis for pelvis and upper limb biomechanics during walking in individuals with ASD vs Control (a) and sensitivity analysis (b)

Sagittal malalignment

Moderate evidence showed increased sagittal pelvic ROM [14, 15] in subjects with sagittal malalignment compared to healthy controls during walking.

Additionally, there are limited evidence of increased SVA and lumbar lordosis in subjects with compensated sagittal malalignment compared to healthy subjects during walking [14]. Limited evidence showed decreased mean head sagittal ROM and shoulder-pelvis axial ROM, pelvic obliquity and rotation, and increased thorax sagittal ROM, L1L3-L3L5 sagittal ROM, mean T10L1-L1L3 and T2T10-T10L1 sagittal ROM, C7T2—T2T10 sagittal ROM in subjects with sagittal malalignment compared to healthy controls during walking [15].

Additionally, hyper-kyphosis showed limited evidence of increased mean thorax sagittal angle, mean T10L1-L1L3 sagittal, T2T10-T10L1 sagittal, C7T2—T2T10 sagittal angle, and decreased shoulder-pelvis axial rotation, mean pelvic tilt, pelvic obliquity and rotation ROM [15] (see Fig. 5).

Fig. 5.

Results of meta-analysis for pelvis and upper limb biomechanics during walking in sagittal malalignment individuals vs Control (a)

Discussion

This systematic review and meta-analysis aimed to elucidate the biomechanical alterations in the pelvic, trunk and upper limb during walking in subjects with spinal deformities, providing a comprehensive understanding of how conditions such as scoliosis, ASD, and sagittal malalignment impact pelvic, trunk and upper limb motion.

The studies evaluated three types of deformities: scoliosis, sagittal malalignment, and adult spinal deformity (ASD). Scoliosis was identified in individuals with a Cobb angle greater than 10°. ASD was characterized by a pelvic tilt in the sagittal plane of over 20°, a sagittal vertical axis exceeding 40 mm, and a Cobb angle greater than 20°. Those with sagittal malalignment displayed different types of misalignments in the sagittal plane, such as dropped head, hyperkyphosis, swayback, and flat back.

Our findings offer important insights and directions for future research in this area. Meta-analysis showed moderate evidence of non-significant increase in pelvic sagittal ROM in ASD, and moderate evidence of increased sagittal pelvic ROM in individuals with sagittal malalignment compared to control during walking.

In scoliosis, meta-analysis showed strong evidence of significant increase in thorax-pelvis sagittal ROM, strong evidence of non-significant increase in SVA, moderate evidence of significant increase in pelvic frontal ROM, sagittal thoracic curve ROM, CVA, and moderate evidence of not-significant change in 3-dimensional thorax movement, sagittal lumbar ROM, thorax-pelvis frontal and transverse ROM in scoliosis group compared to controls during walking.

Scoliosis

Our findings provide strong evidence of a significant increase in thorax-pelvis sagittal ROM [12, 25, 37] and pelvic frontal ROM [11, 25, 28, 36, 37] during walking in individuals with scoliosis compared to healthy individuals. Sensitivity analysis revealed strong evidence of non-significant change in pelvic sagittal and transverse ROM.

The observed increase in thorax-pelvis sagittal ROM can largely be attributed to the compensatory mechanisms that arise due to the scoliotic curvature. Scoliosis alters the mechanics of the entire body, necessitating changes in the orientation and movement of the pelvis and thorax to maintain balance and stability while walking [25, 39]. This compensatory strategy is particularly evident as the body attempts to offset reduced mobility in other spinal regions, which often become stiffened due to the deformity [40]. The increased thorax-pelvis sagittal ROM may therefore be seen as a biomechanical response aimed at preserving functional mobility despite the limitations imposed by the spinal curvature. The consequences of these increased ROMs are multifaceted and warrant careful consideration. First, the heightened thorax-pelvic sagittal ROM can lead to increased energy expenditure to stabilize the upper body while maintaining forward progression. This phenomenon has been documented in scoliotic patients, where the demands of compensatory movements necessitate greater physical exertion [41, 42].

Similarly, the significant increase in pelvic frontal ROM indicates a need for greater lateral movement to maintain a stable gait pattern. Individuals with scoliosis frequently experience uneven load distribution across the hip joints [40, 43], leading to an asymmetrical gait. This compensatory lateral movement is essential for achieving balance and preventing falls, yet it may also reflect an adaptation to the altered biomechanics associated with scoliosis [42, 44]. Furthermore, the increased pelvic frontal ROM may contribute to gait asymmetry and instability, which could have long-term musculoskeletal implications and place additional stress on the lower limbs and spine, potentially exacerbating the scoliotic condition over time. This increased stress may lead to secondary complications, such as lower back pain or hip joint problems, further complicating the clinical management of individuals with scoliosis [30].

The strong evidence of non-significant change in pelvic sagittal and transverse ROM suggests that while deformities associated with scoliosis may influence overall gait mechanics, the specific pelvic motions in these planes remain relatively unchanged when compared to individuals without scoliosis. This may be due to adapting their gait patterns to compensate for their spinal curvature which decreased energy expenditure.

Moreover, our findings provide strong evidence of a non-significant increase in SVA during walking in individuals with scoliosis [1, 7, 12]. This non-significant change can alter walking biomechanics due to structural changes in the pelvis and spine, increased muscular activity, particularly in the erector spinae and quadratus lumborum muscles, which helps maintain pelvic equilibrium and normal three-dimensional pelvic displacements during gait [45]. This compensatory mechanism is likely responsible for the stability of SVA. The ability to maintain a stable SVA despite structural deformities underscores the effectiveness of compensatory mechanisms in individuals with scoliosis. However, this compensation comes at the cost of increased muscular strain and may predispose individuals to long-term musculoskeletal issues [35, 46]. While the overall alignment and balance during walking may seem unaffected, the increased muscular effort leads to higher external work and reduced efficiency of the locomotor system [40, 45]. Over time, this can result in fatigue and discomfort for individuals with scoliosis. Moreover, the prolonged activation of lumbar muscles can contribute to back pain, potentially affecting quality of life [15].

The results of our study provide moderate evidence for a significant increase in CVA [12, 13], alongside non-significant changes in thoracic movements across all three planes [25, 37], as well as in sagittal lumbar ROM [12, 37], thorax-pelvis frontal and transverse ROM [25, 37], and thoracic curve sagittal ROM [14, 37]. The observed increase in CVA can be attributed to various factors, primarily the presence of scoliosis, which disrupt the natural alignment of the spine and pelvis. Notably, scoliosis surgery has been found to significantly reduce thoracic and lumbar Cobb angles while leaving the sagittal vertical axis relatively unchanged, suggesting that certain aspects of spinal alignment may remain resistant to surgical correction [47]. Additionally, coronal malalignment, particularly in older women with diminished bone density, can significantly affect spinal parameters, including the CVA [48]. This could imply that while there is a notable change in coronal alignment, the thoracic spine's overall mobility may not be affected to the same extent. This lack of significant change might suggest that compensatory mechanisms are at play or that thoracic mobility is resilient to changes in coronal alignment. The results also raises questions about how different planes of movement interact and whether interventions aimed at correcting coronal alignment might inadvertently affect sagittal mobility or vice versa. Clinicians should consider these aspects when designing treatment plans for patients with spinal issues.

An increase in CVA often triggers compensatory mechanisms in adjacent spinal structures and the pelvis, which can lead to pain and dysfunction and may also result in further complications, such as adjacent segment degeneration [49].

Furthermore, the lack of significant changes in thoracic movements and lumbar ROM suggests a nuanced picture of spinal mechanics. This stability in thoracic and lumbar movements may help individuals maintain a degree of normal function despite increases in CVA. However, it emphasizes the complexity of spinal biomechanics and indicates the need for comprehensive treatment approaches that address both alignment and mobility issues [50, 51].

Overall, our findings underscore the importance of considering a multifactorial approach to understanding the implications of spinal deformities and their management. Future research should continue to investigate the interplay between spinal alignment and function, aiming to develop targeted interventions that facilitate both structural correction and functional rehabilitation in individuals with spinal abnormalities.

Adult spinal deformities

The results of our study reveal moderate evidence for non-significant increase in pelvic range of motion (ROM) [14, 29, 30, 38] during walking in individuals with ASD compared to healthy controls. Additionally, conflicting evidence surrounding mean pelvic tilt [30, 38] in this population suggests a need for deeper analysis of the underlying factors influencing these discrepancies.

Sensitivity analysis revealed strong evidence of non-significant change in pelvic ROM. However, removing another study leaded to strong evidence of significant results. One of the primary reasons for the conflicting reports on pelvic ROM during walking can be traced back to the type and severity of spinal deformity, including conditions such as sagittal malalignment or hyper-kyphosis or frontal malalignment, likely influence pelvic ROM differently, contributing further to the inconsistent results observed across studies. Individual variability in spinal curvature, as well as compensatory mechanisms—where individuals may adopt different strategies to maintain pelvic equilibrium—can mask underlying changes in motion metrics [52]. Increased muscle activation during gait to compensate for deformities is a noteworthy factor, as it may obscure meaningful changes in pelvic motion that a simple comparison fails to capture. Furthermore, individual differences in muscle strength, particularly in the hip and trunk extensors, can affect pelvic motion, as seen in studies comparing different groups of ASD patients [11, 15, 29, 36, 53].

the conflicting evidence surrounding pelvic ROM and pelvic tilt in ASD during walking reveals significant challenges in both clinical and research contexts. The implications of these findings are critical for clinical practice and patient management. The absence of consistent changes in pelvic ROM complicates the development of standardized assessment protocols and treatment strategies for ASD patients. If interventions designed to enhance gait and posture do not yield predictable changes in pelvic motion, it becomes difficult to assess their effectiveness and guide clinical decision-making [54]. Furthermore, the variability in findings poses challenges in forecasting long-term outcomes, including risks for complications such as falls or progressive spinal deterioration [30]. From a clinical standpoint, variability in spinal curvature suggests that personalized treatment approaches may be necessary for individuals with ASD. Besides, from a research perspective, the inconsistencies highlighted by our findings underscore the importance of taking into account the individual differences in compensatory mechanisms and muscle strength, which are critical to understanding the intricacies of gait in this population.

Sagittal malalignment

Our findings reveal moderate evidence of increased sagittal pelvic ROM [14, 15]. One primary cause is the compensatory mechanism including pelvic retroversion, knee flexion, and pelvic shift to maintain an erect posture and horizontal gaze [30, 55] to maintain balance and forward gaze. Additionally, increased pelvic ROM is often associated with reduced hip extension and increased knee flexion at initial contact, which can be a result of spastic rectus femoris activation and weak hamstring or trunk muscles [56]. This compensatory mechanism is also observed in patients with spinal deformities, where increased pelvic tilt and trunk flexion are used to counteract the imbalance [57, 58].

The increased sagittal pelvic ROM can result in altered walking kinematics and increased energy expenditure. Individuals with sagittal malalignment often exhibit increased anterior pelvic tilt and trunk flexion, which can lead to a more flexed posture during walking [57, 59]. This altered posture can result in decreased walking speed, reduced step length, and increased single support time, contributing to gait instability [14, 37]. Furthermore, the increased pelvic ROM can exacerbate the load on the lower limb joints, potentially leading to joint pain and further mobility issues [60]. These changes can significantly impact the quality of life [15] as maintaining an erect posture requires higher energy expenditure [40] and can lead to fatigue and discomfort [15].

In hyper-kyphotic individuals, our findings supported limited evidence showing increased mean thorax sagittal ROM, mean L1-L3 and C7-T2 sagittal ROM, and decreased shoulder-pelvis axial ROM, alongside reduced pelvic obliquity and rotation ROM compared to healthy controls [15]. These altered dynamics may represent compensatory adjustments in response to the exaggerated thoracic curvature, reflecting a complex interaction where the upper body must accommodate changes in posture while attempting to preserve efficient locomotion mechanics.

Such findings emphasize the need for targeted therapeutic interventions utilizing biofeedback [61], virtual reality [62], physiotherapy [63] or traditional methods that address not only spinal deformities, mobilizing and stabilizing specific segments, but also their cascading effects on the biomechanics of gait. The effects of gait retraining [24, 64] on individuals with spinal deformities should be investigated, focusing on targeted interventions for different body segments influenced by spinal misalignment. Focusing on a specific body segment can influence other body parts due to the biomechanical chain, altering the coordination of segments during dynamic tasks [65].

Limitations and recommendations for future studies

This study's primary limitation lies in the heterogeneity of the populations with adolescent scoliosis and sagittal malalignment [14], influenced by variables such as age and diagnosis. This variability complicates the interpretation of treatment outcomes [29, 30]. Although gait comparisons yielded consistent results, the lack of matching for sex and height necessitates further research involving larger and more homogeneous samples to effectively address these factors. Future studies should stratify participants based on specific characteristics to enhance the validity of the findings.

Concerning scoliosis, existing studies exhibit several limitations, including inadequate controls [12], small sample sizes [37], and potential projection errors from employing a global coordinate system for curvature angles [37]. The presence of double scoliosis curves further complicates comparisons between the convex and concave sides, while significant inter-subject variability suggests that focusing on only one side may not provide a comprehensive understanding [27]. Future research should aim for larger, well-controlled samples and adopt standardized methodologies, including bilateral motion analysis, to improve reliability and applicability.

Conclusion

This systematic review and meta-analysis showed significant differences in pelvic, trunk and upper limb movement patterns during walking between individuals with spinal deformities and healthy controls. These changes are likely compensatory mechanisms implemented to restore balance and stability. The results emphasize the need for personalized rehabilitation approaches to enhance gait efficiency and mobility, especially given the complexity of spinal deformities. Future research should tackle current limitations, including small sample sizes and group diversity, by standardizing measurement methods and including a wider variety of spinal conditions. By combining clinical outcomes with laboratory findings, clinicians can gain deeper insights into gait changes and create more effective treatment strategies for spinal deformities.

Authors'contributions

Fateme khorramroo: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration; Resources, Software, Supervision, Validation, Visualization, Roles/Writing - original draft, and Writing - review & editing. Reza Rajabi: Conceptualization, Formal analysis, Investigation, Methodology, Project administration, Supervision, Validation, and Writing - review & editing. Seyed Hamed Mousavi: Conceptualization, Data curation, Methodology, Formal analysis, Project administration, Investigation, Supervision, Visualization, Validation, Writing - review & editing.

Funding

None.

Data availability

Data is provided within the manuscript or supplementary information files.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.