The effect of simulated knee flexion on sagittal spinal alignment: novel interpretation of spinopelvic alignment

The role of the lower extremity on patient's cone of economy: an innovative approach

PURPOSE

To evaluate the effect of the lower extremities on cone of economy (CoE) calculations as well as to propose a novel assessment of seated balance using traditional CoE measurements.

METHODS

36 controls and 82 degenerative lumbar disease (LD) patients, (38 patients with unilateral radiculopathy (UR), 44 patients with neurogenic claudication (NC) with bilateral symptoms), were enrolled in the study. Functional balance tests were performed and recorded by 3D motion capture in both the standing (Romberg) and seated positions. Balance effort and CoE dimensions were calculated.

RESULTS

The lower extremities exert a significant impact on balance, as reflected in the total head (UR: 20.9, NC: 31.5 vs. H: 10.0 cm, p < 0.015), pelvis (UR: 73.2, NC: 110.0 vs. H: 36.4 cm, p < 0.002) and CoM (UR: 17.1, NC: 18.7 vs. H: 4.6 cm, p < 0.001) sway differences observed between LD patients and healthy controls. Significant differences in CoE dimensions were observed as captured by sagittal head (UR: 2.8 vs. H: 0.9 cm, p = 0.014) and pelvis (UR: 2.8 vs. H: 1.4 cm, p = 0.019) range of sway (RoS) and coronal pelvic RoS (UR: 1.1, NC: 1.1 vs. H: 0.6 cm, p < 0.012) between LD patients and healthy controls.

CONCLUSION

This study first provides a novel standardized means of isolating and quantifying the role of the lower extremity on the CoE in patients with LD, which highlights how spinal pathologies may directly impact and/or contribute to compensatory mechanisms in this region. As evidenced by 18.0-93.2 cm of total sway and 1.1-2.8 cm RoS, the lower extremities account for a significant amount of balance effort and CoE dimensions.

Type IIB Spino-pelvic Imbalance is an Independent Risk Factor for Flexion Contracture After Total Knee Arthroplasty

BACKGROUND

Sagittal imbalance leads to adjustments in the pelvis, hips, and knees to keep a level gaze with minimal energy use. People who have a stiff spine adjust their posture by extending their hips, bending their knees, and tilting their pelvis back. This study hypothesized that type IIB Spino-pelvic imbalance may influence the occurrence of flexion contracture after total knee arthroplasty (TKA).

METHODS

We retrospectively evaluated all patients who received a robotic-assisted TKA between 2019 and 2024 at a single center.

INCLUSION CRITERIA

patients who had a postoperative Range of Motion (ROM) > 90°, a residual postoperative flexion contracture > 0°, and a final surgery report from the robotic platform confirming full extension at the end of the surgery.

EXCLUSION CRITERIA

hip osteoarthritis or arthroplasty, preoperative stiff knees (full ROM < 70°), and Limb Length Discrepancy (LLD) > one centimeter. Patients were divided into the IA-IB-IIA-IIB categories according to the 2021 Journal of the American Academy of Orthopaedic Surgeons (JAAOS) Spino-pelvic classification. There were two different knee surgeons who meticulously measured the residual flexion contracture with a goniometer. Linear regressions were used to assess whether spino-pelvic alignment would be associated with flexion contracture. Logistic regressions assessed whether a type IIB independently predicted residual flexion contracture. Preoperative ROM, Hip-Knee-Ankle angle (HKA), age, and Body Mass Index (BMI) were set as potential confounders. The model's fit was assessed using the Hosmer-Lemeshow (P > 0.43).

RESULTS

A total of 112 patients were included. The postoperative median flexion contracture was two (Interquartiles Range [IQR], one to four) in Cohort 1 and 10 (IQR 7.2 to 14) at the final follow-up. There were 31 patients who were Type IA (27.7%), 20 patients (17.9%) Type IB, eight patients (7.1%) IIA, and 53 patients (47.3%) IIB. A higher incidence of residual flexion contracture was found in IIB patients (24.1, P < 0.001). Logistic regression revealed IIB as an independent predictor of postoperative flexion contracture (B = 0.7, SE = 0.3, Wald = 5.6, P = 0.016, 95% CI [confidence interval] = 4.3 to 6.9).

CONCLUSION

The sagittal spino-pelvic alignment is a predictor of residual postoperative flexion contracture following TKA.

The relationship between spinopelvic alignment and knee osteoarthritis in female patients: A cross-sectional study

BackgroundThe spine, pelvis, and lower extremities move in the form of a kinematic chain.ObjectiveThis study aimed to evaluate the relationship between spinopelvic parameters and knee osteoarthritis.MethodsSixty-nine participants (50-70 years) were diagnosed with knee osteoarthritis: early-stage (n = 36) and late-stage (n = 33). Knee osteoarthritis severity was assessed using standing antero-posterior radiographs (Kellgren-Lawrence scores). A visual Analog Scale was used to evaluate knee and lumbar pain, the Western Ontario and McMaster Universities Osteoarthritis Index to evaluate knee joint function and disability, and the Oswestry Low Back Pain Disability Index to evaluate disability associated with lumbar pain. Lateral scoliosis radiographs were taken of all the study participants; pelvic incidence, pelvic tilt, sacral slope, lumbar lordosis, thoracic kyphosis, and sagittal vertical axis values were measured and recorded.ResultsMultivariate logistic regression analysis was performed to determine the independent risk factors associated with the clinical and radiological osteoarthritis severity as Body Mass Index, sagittal vertical axis and lumbopelvic mismatch increased. The sacral slope values were determined to be independently negatively correlated with the clinical osteoarthritis severity. However, no correlation was determined with the radiological severity.ConclusionIn this study, we determined that global sagittal imbalance and lumbopelvic mismatch are associated with advanced knee osteoarthritis. Although pelvic retroversion was not found to be correlated with the radiographic severity of osteoarthritis, it was found to be associated with poor functional results.

A new 3D full-body scanner analyzing the sagittal and coronal balance of the adult spine: a preliminary prospective observational study

BACKGROUND

The degenerative spondylosis can cause the difficulty in maintaining sagittal and coronal alignment of spine, and X-ray parameters are the gold standard to analyze the malalignment. This study aimed to develop a new 3D full body scanner to analyze the spinal balance and compare it to X-ray parameters.

METHODS

Ninety-seven adult participants who suffer degenerative spondylosis underwent 3D full body scanning, whole spine X-rays, clinical questionnaires and body composition analyses. The 5 inflection points (ear, shoulder, hip, knee, ankle) of the 3D scanner in the sagittal plane were automatically labeled by an AI algorithm. Three concepts are created including "the angle between two points with respect to the plumb line", "the horizontal distances between two points in the sagittal plane" and "the angle between three points". For the coronal plane, the shoulder gradient was analyzed. X-ray parameters of cervical, thoracolumbar and whole spine sagittal balance and coronal balances were compared. The body composition data and clinical questionnaire scores were compared to x-ray and 3D scanner parameters.

RESULTS

The correlation coefficient (C.C.) of dAB_hor (horizontal distance between ear and shoulder in the sagittal plane) and C2-C7 SVA was 0.478 (p-value < 0.001). The C.C. of aAC_sag (sagittal angle of ear-hip from the plumb line) and ODHA was 0.336 (p < 0.001). About coronal balance, the C.C. of shoulder gradient and clavicle angle from x-ray was 0.373 (p < 0.001). The C.C.s were merely affected by body composition data. But in multiple regression analysis, BMI affected 3D scanner data. Clinical symptoms showed correlations with aBCD(shoulder-hip-knee) and aCDE(hip-knee-ankle angle), which may reflect a compensatory pelvic retroversion and knee flexion for positive sagittal imbalance.

CONCLUSIONS

This new 3D scanner has some strengths like radiation-free methods, correlation with x-ray parameters and clinical symptoms, independence to body composition data, and possibility of analyzing dynamic spine balance.

Lumbar osteopathic manipulative treatment can improve KOA symptoms: short-term efficacy observation and mechanism analysis

Background

Manipulative treatment can effectively improve knee pain and function, but no previous studies have shown that lumbar osteopathic manipulative treatment can improve knee symptoms. To explore the influence of lumbar manipulation on KOA and analyze its principlerelationship between coronal position of lumbar spine and KOA.

Methods

Patients were divided into OMT group and DT group according to treatment. WOMAC scores were compared between the two groups, and X-ray examinations before and after treatment were performed in OMT group to analyze the imaging changes.

Results

Both OMT group and DT group showed significant improvement in WOMAC score after treatment, and the improvement in OMT group was better than that in DT group. After OMT treatment, cTMI(P = 0.034), mL-SOD (P < 0.001), mΔL-KOD (P = 0.001), LL (P = 0.036), and FTA(P = 0.026) were significantly changed.

Conclusion

Compared with drug therapy, lumbar manipulation can better improve WOMAC scores in KOA patients. It relives symptoms by loosening muscles and correcting small joint disorders to improve local knee alignment.

Association Between Lumbar Spine Disorder and Genovarum: A Population-Based Cross-Sectional Study

Background

It is becoming increasingly important to study pathology at the knee and spine because of their role in causing pain and deformity in one another. Compression of the lumbar nerve root can disrupt innervation to the thigh muscles, cause an imbalance of muscle and result in varus deformity. In this study, we try to figure out the relation between lumbar spine disorders and genu varum and realize if lumbar spine disorders can cause varus deformity in a patient.

Methods

In this cross-sectional study, the number of 53 patients with knee varus greater than 20 degrees who visited the orthopedic clinics of Rasoul Akram and Moheb Mehr hospitals affiliated to Iran University of Medical Sciences between 2020 and 2022 were investigated in terms of association with lumbar disorders. The demographic characteristics and clinical findings of the patients were recorded and collected using a checklist by referring to the patient's medical profiles. Radiographic findings were evaluated by referring to the imaging department and using the Pacs system. The diagnosis of the patients was based on the history and findings of the knee graph, which was measured with a goniometer to measure the knee angle. The frequency of lumbar disorders caused by pressure on the lumbar nerves in patients with genu varum deformity including canal stenosis, osteoarthritis, spondylolisthesis, and disc herniation was investigated. To investigate lumbar problems, patients' history and radiographic images as well as lumbosacral and knee MRI of patients were used.

Results

The mean age was 66.3 ± 7.66 years. 40 (75.5%) cases were female and 13 (24.5%) cases were male. Lumbar canal stenosis with 28(52.8%) and disc herniation with 32(60.4%) were the most common lumbar disorders in patients with knee varus more than 20 degrees. The mean age of patients with varus of more than 20 degrees with lumbar disorders was significantly higher than that of patients without lumbar disorders. (P: 0.001) There was no significant difference between gender distribution and lumbar disorders in patients with varus more than 20 degrees. Significant positive correlation between genu varum with lumbar canal stenosis (r: 0.53, P: 0.001), osteoarthritis (r: 0.38, P: 0.004), spondylolisthesis (r: 0.39, P: 0.002) and disc herniation (r: 0.46, P: 0.001) was reported2.

Conclusion

An association between lumbar disorders and varus more than 20 degrees was found to be considerable.

Asymmetric Flexion Contracture is Associated With Leg Length Inequality in Patients With Knee Osteoarthritis: Data From the Osteoarthritis Initiative

OBJECTIVE

To evaluate whether knee flexion contracture (FC) was associated with leg length inequality (LLI) and/or morbidity in knee osteoarthritis (OA).

DESIGN

We accessed 2 databases: (1) the Osteoarthritis Initiative (OAI) cohort, including participants with, or at-risk of OA, and (2) the Ottawa Knee Osteoarthritis cross-sectional database (OKOA), including participants with primary advanced knee OA. Both included demographics, radiographic data, knee range of motion, leg length, pain, and function scales.

SETTING

Tertiary care academic rheumatology and orthopedic clinics.

PARTICIPANTS

Patients with or at-risk of primary OA. We included 881 OAI and 72 OKOA participants (N=953).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

The primary outcome tested the association between the difference in knee extensions of the OA and contralateral knees (the knee extension difference, or KExD) and LLI. This was evaluated using bivariate regression, followed by a multivariable linear regression model.

RESULTS

OAI participants had less severe knee OA [Kellgren and Lawrence (KL) score 1.9±1.3] vs OKOA (KL score 3.4±0.6). The KExD correlated with LLI for both databases (OAI: R=0.167; P≤.001; OKOA: R=0.339; P=.004). Multivariable regression showed an effect of KExD on LLI in both databases (OAI: β=0.37[0.18,0.57]; P<.001, OKOA: β=0.73[0.20,1.26]; P=.007). When broken down by subgroup, the OAI moderate-severe OA group showed a significant effect of KExD on LLI (β=0.60 [0.34,0.85]; P<.001).

CONCLUSIONS

OA-related loss of knee extension was associated with LLI for those with moderate-severe OA. Because LLI correlates with worse knee OA symptoms, discovering an FC should cue clinicians to evaluate for LLI, an easily-treatable finding that may help reduce OA-associated morbidity for those approaching the need for arthroplasty.

The relationship between pelvic tilt, frontal, and axial leg alignment in healthy subjects

INTRODUCTION

The relationship between anterior pelvic tilt and overall sagittal alignment has been well-described previously. However, the relationship between pelvic tilt, frontal, and axial leg alignment remains unclear. The aim of the study was to analyze the relationship between pelvic tilt and frontal and axial leg alignment in healthy subjects.

MATERIAL AND METHODS

Thirty healthy subjects (60 legs) without prior surgery underwent standing biplanar long leg radiograph. Pelvic parameters (pelvic tilt, pelvic incidence, sacral slope), hip-knee-ankle angle (HKA), femoral antetorsion and tibial torsion were measured using SterEOS (EOS Imaging) software. EOS was acquired with the feet directing straight anteriorly, which corresponds to a neutral foot progression angle (FPA). The influence of HKA, femoral antetorsion, tibial torsion and gender on pelvic tilt was analyzed in a univariate correlation and multiple regression model.

RESULTS

Sixteen female subjects and 14 male subjects with a mean age of 27.1 years ± 10 (range 20-67) were included. HKA, femoral antetorsion, and tibial torsion correlated with anterior pelvic tilt in univariate analysis (all p < 0.05). Anterior pelvic tilt increased 1.1° (95% CI: 0.7 to 1.5) per 1° of knee valgus (p < 0.001) and 0.5° (95% CI: 0.3 to 0.7) per 1° of external tibial torsion (p < 0.001). Overall, linear regression model fit explained 39% of variance in pelvic tilt by the HKA, femoral antetorsion and tibial torsion (R2 = 0.385; p < 0.001).

CONCLUSION

Valgus alignment and increasing tibial torsion demonstrated a weak correlation with an increase in anterior pelvic tilt in healthy subjects when placing their feet anteriorly. The relationship between frontal, axial leg alignment and pelvic tilt needs to be considered in patients with multiple joint disorders at the hip, knee and spine. Alteration of the frontal, or rotational profile after realignment surgery or by implant positioning might influence the pelvic tilt when the FPA is kept constant.

Relationship between spinal imbalance and knee osteoarthritis by using full-body EOS

BACKGROUND

Orthostatic state is maintained by harmonizing the spine, pelvis and lower extremities. In the past few decades, several studies have demonstrated the associations between spinal imbalance and generalized osteoarthritis. The compensatory mechanisms of pelvis translation and knee flexion, however, have not been fully assessed.

METHODS

A total of 213 volunteers, over 40 years of age, were recruited. Radiological measurements were performed by EOS imaging system. Pelvic tilt (PT), pelvic incidence (PI), lumbar lordosis (LL), sagittal vertical axis (SVA), global tilt (GT), hip-knee-angle (HKA), knee flexion angle (KFA), lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA) were measured. On the basis of SRS-Schwab, the subjects were classified into decompensated group (PI-LL > 20°), compensated group(10° ≤ PI-LL ≤ 20°), and normal group (PI-LL < 10°). Differences in radiographic parameters among groups were evaluated. Data of Knee Society Score (KSS) and Oswestry Disability Index (ODI) score were collected via questionnaires.

RESULTS

Decompensated group showed larger pelvic parameters (PT) and low extremity parameters (LDFA, MPTA, HKA and KFA) than normal group (P < 0.05). Pelvic parameter was larger in the compensated group (median = 31°) compared to the normal group (median = 17°) (P < 0.05). There was no difference in low extremity parameters between the compensated and normal groups. At the sagittal plane, the radiological parameters of spine were greater in subjects with patellofemoral joint pain (PFP) than without PFP (P = 0.058). Higher PI-LL values were observed in women (P < 0.05).

CONCLUSIONS

A correlation between sagittal spinal imbalance and knee joint angles was recognized. The progression of knee and low back pain was associated with the severity of sagittal spinal imbalance. Pelvic retroversion was considered to be the probable compensatory mechanism.

The effect of ethnicity on the age-related changes of spinopelvic characteristics: a systematic review

Spinopelvic characteristics influence the hip's biomechanical behaviour. However, to date there is little knowledge defining what 'normal' spinopelvic characteristics are. This study aims to determine how static spinopelvic characteristics change with age and ethnicity among asymptomatic, healthy individuals. This systematic review followed the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines to identify English studies, including ≥ 18-year-old participants, without evidence of hip or spine pathology or a history of previous surgery or interventional treatment, documenting lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI). From a total of 2,543 articles retrieved after the initial database search, 61 articles were eventually selected for data extraction. When all ethnicities were combined the mean values for LL, SS, PT, and PI were: 47.4° (SD 11.0°), 35.8° (SD 7.8°), 14.0° (SD 7.2°), and 48.8° (SD 10°), respectively. LL, SS, and PT had statistically significant (p < 0.001) changes per decade at: -1.5° (SD 0.3°), -1.3° (SD 0.3°), and 1.4° (SD 0.1°). Asian populations had the largest age-dependent change in LL, SS, and PT compared to any other ethnicity per decade at: -1.3° (SD 0.3°) to -0.5° (SD 1.3°), -1.2° (SD 0.2°) to -0.3° (SD 0.3°), and 1.7° (SD 0.2°) versus 1.1° (SD 0.1°), respectively. Ageing alters the orientation between the spine and pelvis, causing LL, SS, and PT to modify their orientations in a compensatory mechanism to maintain sagittal alignment for balance when standing. Asian populations have the largest degree of age-dependent change to their spinopelvic parameters compared to any other ethnicity, likely due to their lower PI.

Total knee arthroplasty in patients with lumbar spinal fusion leads to significant changes in pelvic tilt and sacral slope

BACKGROUND

The knee-hip-spine syndrome has been well elucidated in the literature in recent years. The aim of this study was to evaluate the effect of total knee arthroplasty (TKA) on spinopelvic sagittal alignment in patients with and without pre-TKA lumber spinal fusion.

METHODS

This is a retrospective cohort study of 113 patients who underwent TKA for primary osteoarthritis. Patients were stratified into the following three groups: (1) patients who had pre-TKA spinal fusion (SF, n = 19), (2) patients who had no spinal fusion but experienced pre-TKA flexion contracture (FC, n = 20), and (3) patients without flexion contracture or spinal fusion before TKA (no SF/FC, n = 74). Spinopelvic sagittal alignment parameters, including pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), thoracic kyphosis (TK), and plumb line-sacrum distance (SVA) were measured preoperatively and 3 months postoperatively on lateral standing full-body low-dose images.

RESULTS

TKA resulted in significant pre- to postoperative changes in pelvic tilt (average ∆ PT = - 8.6°, p = 0.018) and sacral slope (average ∆ SS = 8.6°, p = 0.037) in the spinal fusion (SF) group. Non-significant changes in spinopelvic sagittal alignment parameters (PT, SS, LL, TK, SVA) were noted postoperatively in all patients in the FC and the no SF/FC groups.

CONCLUSIONS

TKA can lead to meaningful changes in spinopelvic alignment in patients with prior lumbar fusion compared to those without spinal fusion. Patients with spinal fusion who are candidates for both hip and knee replacements should consider undergoing TKA first since changes in spinopelvic sagittal alignment can increase the risk of future complications.

LEVEL III EVIDENCE

Retrospective Cohort Study.

Effect of Unilateral Knee Extension Restriction on the Lumbar Region during Gait

Unilateral knee extension restriction might change trunk alignment and increase mechanical load on the lumbar region during walking. We aimed to clarify lumbar region mechanical load during walking with restricted knee extension using a musculoskeletal model simulation. Seventeen healthy adult males were enrolled in this study. Participants walked 10 m at a comfortable velocity with and without restricted right knee extension of 15° and 30° using a knee brace. L4-5 joint moment, joint reaction force, and muscle forces around the lumbar region during walking were calculated for each condition. Peaks of kinetic data were compared among three gait conditions during 0%-30% and 50%-80% of the right gait cycle. Lumbar extension moment at early stance of the bilateral lower limbs was significantly increased in the 30° restricted condition (p ≤ 0.021). Muscle force of the multifidus showed peaks at stance phase of the contralateral side during walking, and the erector spinae showed force peaks at early stance of the bilateral lower limb. Muscle force of the multifidus and erector spinae increased with increasing degree of knee flexion (p ≤ 0.010), with a large effect size (η ² = 0.273-0.486). The joint force acting on L4-5 showed two peaks at early stance of the bilateral lower limbs during the walking cycle. The anterior and vertical joint force on L4-5 increased by 14.2%-36.5% and 10.0%-23.0% in walking with restricted knee extension, respectively (p ≤ 0.010), with a large effect size (η ² = 0.149-0.425). Restricted knee joint extension changed trunk alignment and increased the muscle force and the vertical and anterior joint force on the L4-5 joint during walking; this tendency became more obvious with increased restriction angle. Our results provide important information for therapists engaged in the rehabilitation of patients with knee contracture.

Effect of osteoarthritic knee flexion deformity correction by total knee arthroplasty on sagittal spinopelvic alignment in Indian population

BACKGROUND

Sagittal alignment of the spine, pelvis, and lower extremities is essential for maintaining a stable and efficient posture and ambulation. Imbalance in any element can result in compensatory changes in the other elements. Knee flexion is a compensatory mechanism for spinopelvic sagittal alignment and is markedly affected in severe knee osteoarthritis (OA). The correction of knee flexion deformity (KFD) by total knee arthroplasty (TKA) can lead to complementary changes in the sagittal spinopelvic parameters (SSPs).

AIM

To determine the SSP changes in patients with knee OA, with or without KFD undergoing TKA.

METHODS

The study was conducted in 32 patients who underwent TKA. A neutral standing whole-spine lateral radiograph was performed before surgery and 3 mo after surgery in these patients. Subjects were divided into two groups (Group 1 obtained > 10° corrections in KFD; group B obtained < 10° correction). The pelvic tilt (PT), pelvic incidence (PI), sacral slope (SS), lumbar lordosis (LL), and sagittal vertical axis (SVA) were measured.

RESULTS

The median of change in PT, PI, SS, LL, and SVA was 0.20 mm, 1.00 mm, 2.20 mm, −0.40 mm, and 6.8 mm, respectively. The difference in the change in SSPs between the two groups was statistically non-significant.

CONCLUSION

SSPs, such as PI, PT, SS, LL, and SVA, do not change significantly following TKA in end-stage knee OA despite a significant correction (> 10°) in KFD.

The Influence of Knee Osteoarthritis on Spinopelvic Alignment and Global Sagittal Balance

Osteoarthritis (OA) of the knee is thought to lead to a loss of lumbar lordosis (LL) as a compensation for knee flexion contracture. Changes in sagittal alignment are not limited to the lumbar spine and involve a complex interplay of alignment of the hip, pelvis, and spine. While spine-hip interactions have been previously explored, the influence of knee OA sagittal alignment parameters on spinopelvic alignment and global sagittal balance remains unexplored. Standing radiological examination using EOS biplanar radiography was examined in 108 patients with knee OA. Whole-body sagittal alignment parameters (thoracic kyphosis, LL, pelvic incidence, pelvic tilt [PT], femoropelvic angle [FPA], femoral tilt angle [FTA], tibial tilt angle, and knee flexion angle [KFA]) and global balance parameters (sagittal vertical axis [SVA] and odontoid hip axis [OD-HA] angle) were measured three dimensionally (3D). The correlation coefficients among all parameters were assessed. A multiple stepwise linear regression model was built to investigate the direct association between SVA or OD-HA angle (dependent variables) and sagittal alignment parameters and demographic data (independent variables). Significant correlations between KFA, FPA, FTA, SVA, and OD-HA angle were found. FTA was correlated with LL and FPA. The FTA was the most influential predictor of both global sagittal balance parameters (p < 0.001). Knee OA leads to changes in global sagittal balance with effects at the hip, knee, pelvis, and spine. FTA (forward flexion of the femur vs. the vertical plane) is the largest driver of global sagittal plane balance in patients with knee OA.

Investigation of the Relationship Between Hip and Knee Osteoarthritis and Disordered Spinal and Pelvic Morphology

Introduction

A critical question is the causal relationship between hip or knee osteoarthritis (OA) and disordered spinal and pelvic morphology. The aim of this study is to examine this correlation. Therefore, we studied the effect of total hip or knee arthroplasty (THA/TKA) on truncal parameters to determine the causal relationship between these two situations.

Materials and methods

This is a prospective study of the effect of THA or TKA in patients with hip or knee OA on truncal morphological parameters. Patients with one-sided hip or knee OA who chose to undergo THA or TKA were enrolled and surveyed. A control group (CG) was also surveyed for comparison with the patients. The patients were preoperatively examined for truncal parameters using the Diers Formetric four-D analysis system (surface topography technique) to calculate several truncal parameters in all planes at four months and 12 months postoperatively. Measurable examinations were performed using the Statistical Package for the Social Sciences (SPSS) version 17.00 (SPSS Inc., Chicago), and statistical significance was set at a p-value of <0.05.

Results

The study examined 34 patients who underwent THA, including 19 women and 15 men with a mean age of 67.62 ± 8.28 years. The study also examined 45 patients who underwent TKA, including 34 women and 11 men, with a mean age of 72.42 ± 7.0 years. These patients were also compared with a CG that consisted of 25 normal individuals, including 12 women and 13 men, with a mean age of 69.28 ± 10.11 years.

The results of this study from four months after THA revealed that the lordotic angle, trunk torsion, pelvic inclination, pelvic obliquity, and pelvis rotation were improved to normal levels. At 12 months after THA, only the pelvic obliquity was improved to normal levels. At four months after TKA the lordotic angle, pelvic inclination, and pelvic obliquity were improved to normal levels. However, the fleche cervicale and vertebral rotation were worse. At 12 months after TKA, only the pelvic obliquity was improved to normal levels.

Conclusions

THA and TKA to correct hip and knee OA do not correct the disordered morphology of the trunk in the long term. Thus, hip or knee OA does not seem to be responsible for disordered trunk morphology. However, it cannot be ruled out whether the disturbed morphology is responsible for the appearance of the hip and knee OA.

Understanding "Kyphosis" and "Lordosis" for Sagittal Balancing in Two Common Standing Postures

STUDY DESIGN

Cross-sectional radiographic comparison study.

OBJECTIVE

The aim of this study was to understand whole-body balancing in directed and natural standing postures, through comparison of kypholordotic ratios on whole-body radiographs of young, healthy subjects.

SUMMARY OF BACKGROUND DATA

Recent studies highlighted the importance of understanding whole-body balancing, proposing the use of the more physiological natural standing posture, together with the conventional directed standing posture, for imaging.

METHODS

Sixty healthy, 21-year-old subjects (36 males, 24 females) were recruited. EOS whole-body radiographs of subjects in directed and natural standing postures were obtained. Radiographic parameters compared include C2-sagittal vertical axis (C2-SVA), C7-SVA, C2-7-SVA, global cervical angles (C0-T1 and C2-C7), regional cervical angles (C0-C2, C2-C4, C4-C7), T1-slope, global thoracic angles (T1-T12 and T1-inflection vertebra [Inf]), thoracolumbar angle (T11-L2), global lumbar angles (T12-S1 and Inf-S1), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), spinocoxa angle (SCA), and femoral alignment angle (FAA). Kypholordotic ratios of T1-12/T12-S1, T1-Inf/Inf-S1, Tl-Inf/SCA, and (T1-Inf + FAA)/(T1-slope + SCA) were calculated and compared.

RESULTS

Compared to directed standing, natural standing has greater C2-SVA and C7-SVA, more lordotic global and regional cervical angles (except C0-2 angle), higher T1-slope, larger T1- T12 and T1-Inf kyphotic angles, smaller T12-S1 and Inf-S1 lordotic angles, larger PT, more lordotic SCA, and smaller SS and FAA angles. T1-12/T12-S1 and T1-Inf/Inf-S1 ratios in natural standing, and (Tl-Inf + FAA)/(T1-slope + SCA) ratio in both postures approximate 1. There were significant differences between postures for Tl-l2/Tl2-Sl, Tl-Inf/Inf-Sl and Tl-Inf/SCA ratios.

CONCLUSION

Whole-body balancing requires understanding of the balance between kyphosis and lordosis, which varies with the posture of patients. Analysis of kypholordotic ratios obtained in this study allude to the importance of performing whole-body imaging in the directed standing posture, and whole-spine or whole-body imaging in the natural standing posture, so as to fully understand spinal and whole body balancing for spinal realignment surgeries.Level of Evidence: Level 3.

Truncal Changes in Patients Suffering Severe Hip or Knee Osteoarthritis: A Surface Topography Study

Backgroud

Osteoarthritis (OA) of the hip and knee is a degenerative disease with complications, including reduced range of motion and pain. Although OA of the hip and knee is common, there are few studies that investigated if patients with this condition had affected morphological truncal parameters. The objectives of this study were to compare the morphology of the spine and the pelvis of patients with hip or knee OA to that of a control group (CG) and to comment on the proposed mechanisms of these changes and the clinical effects on patients.

Methods

This study included three groups of individuals. The first group consisted of 34 patients (15 men and 19 women with a mean age of 67.62 ± 8.28 years) suffering from hip OA. The second group consisted of 45 patients (11 men and 34 women with a mean age of 72.47 ± 7.0 years) suffering from knee OA. These patients were compared with a CG, which consisted of 25 individuals (13 men and 12 women with a mean age of 69.28 ± 10.11 years). The DIERS formetric 4D analysis system was used to calculate several truncal parameters in all planes. All analyses were accomplished using the SPSS ver. 17.0, and p < 0.05 was used to determine statistical significance.

Results

Patients with hip OA presented with significantly increased values than those in the CG for sagittal imbalance, scoliosis angle, vertebral rotation, trunk torsion, and pelvic obliquity, and decreased values than those in the CG for fleche lombaire. Patients with knee OA presented with significantly increased values than those in the CG for sagittal imbalance, apical deviation, scoliosis angle, vertebral rotation, trunk torsion, and pelvic obliquity. Patients with hip or knee OA, compared to the CG, had greater forward inclination of the spine, greater scoliosis, greater vertebral rotation and trunk torsion, and greater obliquity of the pelvis at the frontal plane.

Conclusions

Patients with severe hip or knee OA could have truncal morphology alterations, in addition to reduced hip or knee range of motion and pain. These alterations could cause significant negative effects, which may then seriously affect the patients' quality of life.

Spinopelvic Alignment and Low Back Pain before and after Total Knee Arthroplasty

STUDY DESIGN

Prospective cohort study.

PURPOSE

This study aims to examine changes in spinopelvic alignment, sagittal global balance, and low back pain (LBP) following the removal of knee flexion contracture by total knee arthroplasty (TKA).

OVERVIEW OF LITERATURE

The limitation of the knee extension was correlated with the decrease in lumbar lordosis (LL). Currently, there are no studies evaluating the spinopelvic alignment and LBP before and after TKAs.

METHODS

Sagittal spinopelvic alignment was evaluated in 110 subjects using radiographs of the whole spine. Parameters measured in this study included sagittal vertical axis (SVA), LL, sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI). The distribution of sagittal plane modifier grade was evaluated according to the Scoliosis Research Society-Schwab classification of adult spinal deformity (ASD). Consequently, personal history related to LBP was obtained, and the association of pre- and postoperative LBP and spinopelvic alignment was investigated.

RESULTS

Preoperatively, 66% of all subjects showed LBP and mostly exhibited anteriorly shifted global imbalance associated with a decrease in LL and knee flexion contractures, and the subject who had severe flexion contracture of the knee joint showed more forwardly shifted global balance with backward PT and decrease in LL. After TKAs, the knee flexion contractures were eliminated in most cases, and one-third of subjects experienced decrease in LBP. However, SVA increased more and associated with slight decrease of PT and increase of SS. No significant differences were confirmed between pre- and postoperative values of LL and PI. In addition, there were no significant differences in postoperative values of spinopelvic parameters between subjects with and without relieved LBP.

CONCLUSIONS

Although one-third of subjects experienced decrease of LBP after TKAs, the sagittal global imbalance was not restored through the removal of knee flexion contracture.

Radiographic and clinical evidence: osteoarthritic knee can change surgical result for lumbar degenerative disease patient undergone surgery for 3-year follow-up: a retrospective comparative clinical study

Background

There is a paucity of reports clarifying the implication of knee osteoarthritis (OA) on spinal sagittal alignment of patients undergone surgery for lumbar spine. This study aimed to analyze how osteoarthritic knee affects radiographic and clinical results of degenerative lumbar disease patients undergone lumbar fusion.

Methods

We retrospectively reviewed the medical records and radiographs of 74 consecutive degenerative lumbar disease patients who underwent posterior instrumentation and fusion surgery between May 2016 and June 2017 and were followed up for minimum 3 years postoperatively. The patients were divided into 2 groups according to the severity of knee OA by Kellgren-Lawrence grading (KLG) scale (group I, KLG 1 or 2 [n = 39]; group II, KLG 3 or 4 [n = 35]). Patient demographic data, comorbidities, spinal sagittal parameters and clinical scores were extracted and compared at preoperative, postoperative 1 month and the ultimate follow-up between the groups. In radiographic assessment, sagittal alignment parameters and sagittal balance were used. In clinical assessment, the scores of Oswestry disability index (ODI) and Scoliosis Research Society questionnaire (SRS-22) were used. For the frequency analysis of categorical variables across the groups, chi-square test was used and student t tests was used to compare the differences of continuous variables.

Results

In radiographic assessment, TLK (thoracolumbar kyphosis), LL (lumbar lordosis), PT (pelvic tilt), C7 SVA (sagittal vertical axis) in both groups improved significantly after surgery (p <  0.05). However, LL, PT, C7SVA improved at postoperative 1 month in the group II were not maintained at the ultimate postoperative follow-up. In clinical assessment, preoperative Oswestry disability index (ODI, %) and all SRS-22 subscores of the group I and II were not different (p > 0.05). There were significant differences between the groups at the ultimate follow-up in ODI (− 25.6 vs − 12.1, p <  0.001), SRS total score (%) (28 vs 20, p = 0.037), function subscore (1.4 vs 0.7, p = 0.016), and satisfaction subscore (1.6 vs 0.6, p < 0.001).

Conclusion

Osteoarthritic knee with KLG 3 or 4 have a negative influence on maintaining postoperative spinal sagittal alignment, balance, and the clinical outcomes achieved immediately by posterior instrumentation and fusion for lumbar degenerative disease.

Trial registration

This study was retrospectively registered with approval by the institutional review board (IRB) of our institution (approval number: 2018–11-007).

Correction surgery for adult spinal deformity improves not only spinopelvic alignment but also the three-dimensional alignment of the lower extremities

BACKGROUND

It is well known that correction surgery for adult spinal deformity (ASD) improves sagittal and coronal spinopelvic alignment, but the surgery effect on lower extremities (LE) is not well clarified. The aim of this study was to test the hypothesis that LE alignment also improves following spinopelvic correction surgery for ASD as a function of compensatory mechanism, and to clarify an effect of the severity of knee osteoarthritis (OA) on the improvement.

METHODS

We retrospectively evaluated spinopelvic alignment, hip knee ankle angle (HKA), knee flexion angle (KF), and severity of the knee OA in thirty-nine patients with ASD before, two weeks and three months after the surgery. The grade of knee OA was evaluated by Kellgren Lawrence grading, and classified grade 0 to 2 into mild, and 3, 4 into severe OA. All the values were compared by paired t test or Wilcoxon signed rank test with significant p value of <0.05.

RESULTS

Following the surgery, not only spinopelvic, but also bilateral HKA and KF were significantly improved. HKA in mild OA side was more normalized compared to that in severe side. Although KF of both bilateral mild and bilateral severe OA groups improved, the improvement of mild group was more significant.

CONCLUSION

The 3D alignment of LE improved following spinopelvic correction surgery. The improvement was inadequate in cases with severe knee OA.

Functionally Oriented Alignment of the Lower Extremity Reflecting the Direction of Gait for Healthy Elderly, Knee Osteoarthritis, and Total Knee Arthroplasty Subjects

Purpose

The objective of this study was to evaluate the functional lower extremity alignment based on both position and motion [functionally oriented alignment (FOA)] of the knee in healthy elderly, varus osteoarthritis (OA), and total knee arthroplasty (TKA) subjects.

Methods

This study evaluated 87 knees in 24 healthy elderly (72 ± 5 years), 39 varus OA (72 ± 6 years), and 24 TKA (75 ± 4 years) subjects. A 3D assessment system was used on 3D models and biplanar long-leg radiographs with the toe angle reflecting gait direction, by applying a 3D-to-2D image registration technique. In the world coordinate system, the y-, z-, and x-axes were defined as gait direction, gravity direction, and the cross product of y- and z-axes, respectively. The parameters were: (a) coronal inclination, sagittal inclination, and transverse direction of the femur and tibia relative to the ground and (b) the difference between the yz-plane of the world coordinate system (functional plane) and the yz-plane of the femoral or tibial coordinate system (anatomical plane).

Results

The femur had more medial and posterior inclination and the tibia had more lateral and anterior inclination in osteoarthritic knees as compared to healthy knees, and TKA knees had inclinations similar to healthy knees. Rotation was similar or different in the anatomical and functional planes among the subjects with the healthy, knee OA, and TKA.

Conclusions

The association between the anatomical and functional planes and the position of each bone relative to gravity varied depending on the condition of the knees.

Level of Evidence: Level of III

Impact of sagittal spine-pelvis-leg alignment and muscle strength on quality of life and low back pain in rural Japanese community- dwelling middle-aged and elderly persons

BACKGROUND

Lower limb compensation for spinal sagittal malalignment and its impact on quality of life (QOL) and low back pain (LBP) have not been well studied.

OBJECTIVE

To clarify postural compensation and the impact of spinal and lower limb sagittal alignment and muscle strength on QOL and LBP in persons > 50 years old.

METHODS

In this cross-sectional study, 122 rural community-dwelling, healthy adults (56 males, 66 females; average age 71.1 years; age range, 52-88 years) underwent assessments of QOL (36-Item Short-Form Health Survey; SF-36), LBP (Roland-Morris Disability Questionnaire; RDQ), thoracic kyphosis (TK), lumbar lordosis (LL), sacral inclination (SI), grip strength, lower limb strength, and back extensor strength (BES). On univariate and multivariate analyses, variables that correlated with QOL and the RDQ were identified.

RESULTS

LL was moderately correlated with SI and weakly correlated with the knee flexion angle (KFA). LL, KFA, C7-L5D, and BES were correlated with SF-36 subscales and the RDQ. KFA contributed to the physical component summary of the SF-36. Female sex and BES contributed to the RDQ.

CONCLUSIONS

Knee flexion compensated for lumbar kyphosis, but affected physical QOL scores negatively; BES was the most reliable contributor to QOL and the RDQ.

Unravelling the knee-hip-spine trilemma from the CHECK study

AIMS

The aetiologies of common degenerative spine, hip, and knee pathologies are still not completely understood. Mechanical theories have suggested that those diseases are related to sagittal pelvic morphology and spinopelvic-femoral dynamics. The link between the most widely used parameter for sagittal pelvic morphology, pelvic incidence (PI), and the onset of degenerative lumbar, hip, and knee pathologies has not been studied in a large-scale setting.

METHODS

A total of 421 patients from the Cohort Hip and Cohort Knee (CHECK) database, a population-based observational cohort, with hip and knee complaints < 6 months, aged between 45 and 65 years old, and with lateral lumbar, hip, and knee radiographs available, were included. Sagittal spinopelvic parameters and pathologies (spondylolisthesis and degenerative disc disease (DDD)) were measured at eight-year follow-up and characteristics of hip and knee osteoarthritis (OA) at baseline and eight-year follow-up. Epidemiology of the degenerative disorders and clinical outcome scores (hip and knee pain and Western Ontario and McMaster Universities Osteoarthritis Index) were compared between low PI (< 50°), normal PI (50° to 60°), and high PI (> 60°) using generalized estimating equations.

RESULTS

Demographic details were not different between the different PI groups. L4 to L5 and L5 to S1 spondylolisthesis were more frequently present in subjects with high PI compared to low PI (L4 to L5, OR 3.717; p = 0.024 vs L5 to S1 OR 7.751; p = 0.001). L5 to S1 DDD occurred more in patients with low PI compared to high PI (OR 1.889; p = 0.010), whereas there were no differences in L4 to L5 DDD among individuals with a different PI. The incidence of hip OA was higher in participants with low PI compared to normal (OR 1.262; p = 0.414) or high PI (OR 1.337; p = 0.274), but not statistically different. The incidence of knee OA was higher in individuals with a high PI compared to low PI (OR 1.620; p = 0.034).

CONCLUSION

High PI is a risk factor for development of spondylolisthesis and knee OA. Low pelvic incidence is related to DDD, and may be linked to OA of the hip. Level of Evidence: 1b Cite this article: Bone Joint J 2020;102-B(9):1261-1267.

Examination of the changes in lower extremities related to progression of adult spinal deformity: a longitudinal study of over 22 years

This longitudinal observational study investigated the relationship between changes in spinal sagittal alignment and changes in lower extremity coronal alignment. A total of 58 female volunteers who visited our institution at least twice during the 1992 to 1997 and 2015 to 2019 periods were investigated. We reviewed whole-spine radiographs and lower extremity radiographs and measured standard spinal sagittal parameters including pelvic incidence [PI], lumbar lordosis [LL], pelvic tilt [PT], sacral slope [SS] and sagittal vertical axis [SVA], and coronal lower extremity parameters including femorotibial angle (FTA), hip–knee–ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA) and mechanical lateral distal tibial angle (mLDTA). Lumbar spondylosis and knee osteoarthritis were assessed using the Kellgren–Lawrence (KL) grading system at baseline and at final follow-up. We investigated the correlation between changes in spinal sagittal alignment and lower extremity alignment and changes in lumbar spondylosis. The mean age [standard deviation (SD)] was 48.3 (6.3) years at first visit and 70.2 (6.3) years at final follow-up. There was a correlation between changes in PI-LL and FTA (R = 0.449, P < 0.001) and between PI-LL and HKA (R = 0.412, P = 0.001). There was a correlation between changes in lumbar spondylosis at L3/4 (R = 0.383, P = 0.004) and L4/5 (R = 0.333, P = 0.012) and the knee joints. Changes in lumbar spondylosis at L3/4 and L4/5 were related to changes in KOA. Successful management of ASD must include evaluation of the state of lower extremity alignment, not only in the sagittal phase, but also the coronal phase.

Sagittal Spinopelvic Alignment in Asymptomatic Iranian Adults Aged 18 to 40 Years

BACKGROUND

Recent studies have revealed the increasing importance of sagittal spinopelvic alignment. Knowing the values of sagittal spinopelvic parameters, which are affected by ethnicity, is essential in the normal asymptomatic population. In the current study, these parameters were measured in a sample of asymptomatic Iranian population.

METHODS

Seventy asymptomatic participants without complaint of musculoskeletal problems were enrolled. They had no complaint about musculoskeletal problems. Lateral full-length spinal and pelvic x-rays were taken. The following parameters were measured on x-rays and presented as mean ± standard deviation: pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), lumbar lordosis (LL), thoracic kyphosis (TK), lumbar tilt (LT) and thoracic tilt (TT).

RESULTS

The population consisted of 37 males and 33 females aged 26.6 ± 4.27 years. The mean values of PI, SS, PT, LL, TK, LT, and TT were 44.5 ± 10.1, 35.4 ± 6.7, 9.1 ± 7.9, 41.9 ± 14.7, 28.8 ± 8.3, 11.9 ± 7.4 and -7.5 ± 5.7 (median: -10; 5th percentile: -14; 95th percentile: 4.4) degrees, respectively. The variables were similar between males and females except for LL which was significantly higher in females (37.8 ± 16.5 versus 46.5 ± 11; P = 0.013). In addition, the linear regression model revealed age to be independently related with PI (beta = 0.344; P = 0.004) and PT (beta = 0.366; P = 0.002). PI (r = 0.344, P = 0.004) and PT (r = 0.359, P = 0.002) were positively correlated with age. Additionally, PI was positively correlated to SS, PT and LL and negatively to TT.

CONCLUSION

These findings may be used as referential values for sagittal spinopelvic parameters in the Iranian population. The positive correlation of PI with age questions the constancy of PI throughout life. However, larger studies are required.

Stiffness After Total Knee Arthroplasty: Is It a Result of Spinal Deformity?

BACKGROUND

There are no studies to date analyzing the effect of spinal malalignment on outcomes of total knee arthroplasty (TKA). Knee flexion is a well-described lower extremity compensatory mechanism for maintaining sagittal balance with increasing spinal deformity. The purpose of this study was to determine whether a subset of patients with poor range of motion (ROM) after TKA have unrecognized spinal deformity, predisposing them to knee flexion contractures and stiffness.

METHODS

We retrospectively evaluated a consecutive series of patients who underwent manipulation under anesthesia (MUA) for poor ROM after TKA. Using standing full-length biplanar images, knee alignment and spinopelvic parameters were measured. Patients were stratified by pelvic incidence minus lumbar lordosis as a measure of spinal sagittal alignment with a mismatch of ≥10° defined as abnormal, and we calculated the incidence of sagittal spinal deformity.

RESULTS

Average ROM before MUA was extension 3° and flexion 83°. About 62% of patients had a pelvic incidence minus lumbar lordosis mismatch of ≥10°. In the spinal deformity group, post-MUA ROM was improved for flexion only, whereas both flexion and extension were improved in the nondeformity group.

CONCLUSION

Compensatory knee flexion because of sagittal spinal deformity may predispose to poor ROM after TKA. Patients with clinical suspicion should be worked up preoperatively and counseled accordingly.

A review of cervical spine alignment in the normal and degenerative spine

With recent advancements in surgical spine technology and techniques, the importance of regional and global spine alignment has become an important factor in surgical planning. Our review aims to consolidate the current literature on cervical and global alignment parameters and its relationship to cervical symptomatology, quality of life (QOL), requirements for surgery, potential surgical complications and health-related quality of life (HRQOL) outcomes.

Can knee flexion contracture affect cervical alignment and neck tension? A prospective self-controlled pilot study

BACKGROUND CONTEXT

The coordination of the alignment between the lower extremities and cervical spine helps to achieve balance and horizontal gaze during standing and walking. Malalignment in any segment can disturb the global balance, causing compensation in another segment. Knee flexion contracture (KFC) can cause spine inclination with increased C7 tilt or C7 SVA (sagittal vertical axis). Cervical alignment and the posterior muscles are essential for maintaining the horizontal gaze which is closely related to neck tension (NT).

PURPOSE

This study aimed to determine whether KFC can affect cervical alignment and its potential effects on the posterior muscles and NT.

DESIGN

A prospective pilot study was carried out in preoperative (pre-op) and postoperative (post-op) phases.

PATIENT SAMPLE

This study included 22 consecutive patients with KFC and 12 control subjects in our department who agreed to participate from between August 1, 2018 and February 28, 2019 in our department.

OUTCOME MEASURES

Visual analog scale (VAS) and neck disability index (NDI) were used. The sagittal alignment parameters and cervical range of motion (ROM) were measured on radiographic images, and included the C0-C2 lordosis (C0-2L), C2-C7 lordosis (C2-7L), C2 SVA, C7 SVA, T1 slope, thoracic kyphosis, lumbar lordosis (LL), pelvic tilt, sacral slope, and knee flexion angle (KA). Surface electromyography-based flexion-relaxation ratio (FRR) and ultrasound-based shear wave elastography (SWE) were performed.

METHODS

The control group was matched for age, sex, and body mass index with the KFC group. Patients in the KFC group underwent arthroscopic surgery to correct knee alignment. Comparisons between pre-op and post-op phases were performed using paired sample t tests, comparisons between KFC and control groups were performed using independent samples t tests. The correlation analysis between the parameters was performed using Spearman analysis. Funding for this study was provided by the National Natural Science Foundation of China (60,000 USD), Beijing Municipal Administration of Hospitals Incubating Program (50,000 USD), and Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support (20,000 USD). There were no conflicts of interest associated with this study.

RESULTS

The average follow-up time for this pilot study was 11.4±1.5 days. Pre-op, the KFC group had higher KA, T1S, C7 SVA, C2 SVA, C0-2L, SWE, VAS, and NDI compared with the control group, but all of these parameters were decreased significantly post-op. The LL, FRR of splenius capitis (FRRsc), and ROM of the KFC group pre-op were lower than the control group, and all of these were increased significantly post-op. There were no differences in pelvic tilt, sacral slope, C2-7 L, or TK between the KFC and control groups, or in FRR of splenius capitis (FRRutr) between pre-op and post-op phases. KA had strong correlations with LL (r=-0.83), which correlated well with C7 SVA (r=-0.75). C7 SVA correlated strongly with C2 SVA (r=0.79), which also correlated strongly with C0-2 L (r=0.76). C0-2 L correlated well with FRRsc (r=-0.65) and SWEsc (r=0.72), and both of them correlated well with VAS (r=-0.54, r=0.71) and NDI (r=-0.57, r=0.76). ROM correlated well with FRRsc (r=0.71), SWEsc (r=-0.74), VAS (r=-0.66), and NDI (r=-0.66).

CONCLUSIONS

KFC may cause spine inclination and craniocervical malalignment, leading to NT and ROM reduction. The results of this pilot study may be helpful in guiding further studies concerning KFC and NT.

Knee-Hip-Spine Syndrome: Improvement in Preoperative Abnormal Posture following Total Knee Arthroplasty

An ergonomic upright body posture is maintained by the alignment of the spine, pelvis, and lower extremities, and the muscle strength of body trunk and lower extremities. The posture varies with age because of the degenerative changes in the involved structures and the weakening of the muscles. The compensatory mechanisms underlying these changes have recently been evaluated, and the loss of lumbar lordosis results in spinal kyphosis, pelvic retroversion, hip extension, knee flexion, and ankle dorsiflexion. These mechanisms are referred to as the hip–spine and knee–spine syndromes. The spine, hip, and knee are anatomically connected, and the pain and discomfort of the lower back, hip, and knee frequently arise due to degenerative changes of these structures. Thus, these mechanisms are considered as the knee–hip–spine syndrome. Spinal fusion, total hip arthroplasty, and total knee arthroplasty are the surgical procedures for severe degeneration, and their clinical outcomes for the affected sites are promising. However, despite surgeries, other structures may degenerate and result in complications, such as proximal junctional kyphosis and hip dislocation, following spinal fusion. Therefore, it is necessary to evaluate each patient under specific conditions and to treat each section while considering associations between the target structure and entire body. The purpose of this article is to introduce postural maintenance, variations with age, and improvements with surgical interventions of spine, hip, and knee as the knee–hip–spine syndrome.

Contribution of sex and body constitution to three-dimensional lower extremity alignment for healthy, elderly, non-obese humans in a Japanese population

BACKGROUND

Humans support their bodies exclusively by vertical balance in bipedal locomotion, and the body, especially the lower extremity, generally changes with age. Sex and body constitution are assumed to be associated with lower extremity alignment, but this association remains to be elucidated. This study sought to clarify this association in healthy, elderly, non-obese humans in a Japanese population.

METHODS

The present study investigated 55 healthy volunteers (mean age: 70 ± 6 years). A 3D extremity alignment system was applied under weight-bearing conditions on biplane long lower extremities X-rays using a 3D-to-2D image registration technique. The evaluation parameters included 3D hip-knee-ankle angle (3DHKA) alignment in the coronal (coronal alignment) and sagittal planes (sagittal alignment) and rotational alignment between the femur and tibia. The influences of sex and body constitution on all the alignment were analyzed.

RESULTS

Multiple linear regression analysis with the dependent variable of each alignment showed that sex was the dominant factor for coronal and rotational alignment (coronal: p <  0.01; rotational: p <  0.01), and body weight was the dominant factor for sagittal alignment (p <  0.01).

CONCLUSIONS

The association of sex with coronal and rotational alignment and of body constitution with sagittal alignment were proved in healthy, elderly, non-obese humans in a Japanese population. This finding can lead to further understanding of the etiology of many diseases and age-related changes.

Spinal Deformity Surgery: A Critical Review of Alignment and Balance

Correction of the overall coronal and/or sagittal plane deformities is one of the main predictors of successful spinal surgery. In routine clinical practice, spinal alignment is assessed using several spinal and pelvic parameters, such as pelvic incidence and tilt, sacral slope, lumbar lordosis, thoracic kyphosis, and sagittal vertical axis. Standard values have been defined for all these parameters, and the formulas of correction have been set for determining the surgical strategy. However, several factors can potentially bias these formulas. First, all standard values are measured using conventional plain radiographs and are, therefore, prone to bias. The radiologist, measuring surgeon, and patient are possible confounding influencing factors. Second, spino-pelvic compensatory effects and biomechanically relevant structures for the patient’s posture, including ligaments, tendons, and muscles, have received minimal consideration in the literature. Therefore, even in cases of appropriately planned deformity correction surgeries, complications, revision rates, and surgical outcomes significantly vary. This study aimed to illustrate the current clinical weaknesses of the assessment of spinal alignment and the importance of holistically approaching the musculoskeletal system for any spinal deformity surgery. We believe that our detailed insights regarding spinal, sagittal, and coronal alignments as well as the considerations of an individual’s spinal balance will contribute toward improvement in routine patient care.

Inter-rater reliability of DartfishTM movement analysis software for measuring maximum flexion and extension at the hip and knee in older adults with osteoporosis and osteopenia

Various methods are used to measure hip and knee joint motion angles; however, their use is often limited by cost or inability to measure dynamic movements. The assessment of movement patterns is clinically useful in individuals with osteoporosis (OP) and osteopenia (OPe) through its potential to optimize fracture risk assessment. This study evaluates the inter-rater reliability of using Dartfish^TM 2-D Motion Analysis Software to measure maximum flexion and extension angles at the hip and knee in individuals with OP or OPe while performing five tasks of the Safe Functional Motion test. Twelve participants were videotaped performing the pour, footwear, newspaper, sweep, and sit-to-floor tasks. Five raters used Dartfish^TM to analyze maximum flexion and extension angles at the hip and knee, and an intra-class correlation coefficients (ICC) and SEM were calculated for each measurement. In all five tasks, ICC and SEM values ranged from 0.23 to 0.95, and 1.75 to 11.54 degrees, respectively, with maximum knee flexion angles generally having higher ICC, and lower SEM point estimates. The results indicate that Dartfish^TM measurements of maximum knee flexion angles in uniplanar tasks demonstrate a moderate to excellent degree of inter-rater reliability, while measurements at the hip joint should be used with caution. Given that the results of this study display moderate to excellent reliability, they lay the groundwork for future research aimed at determining the validity of these measurements. Such research would help to further develop the base of evidence surrounding the usefulness of Dartfish^TM Motion Analysis in fracture risk analysis among individuals with OP.

Combination of whole-spine lateral radiograph and lateral scanogram in the assessment of global sagittal balance

BACKGROUND CONTEXT

Global balance of human standing is analyzed as the geometric sum of the individual alignments extending from the spinal column to the pelvis, and to the lower limbs. The innovative EOS system has opened new perspectives for the global analysis of whole-body alignment, but its use is very limited because of its high cost. An alternative may be to combine the whole-spine lateral radiograph and the lateral scanogram in the global sagittal analysis of whole-body alignment.

PURPOSE

We examined to determine the validity and reliability of a lateral scanogram in the measurement of sacropelvic parameters.

STUDY DESIGN/SETTING

A retrospective radiological study was carried out.

PATIENT SAMPLE

We randomly selected 100 sets of digital radiographs, both whole-spine radiographs and lower-limb scanograms, from our database.

OUTCOME MEASURES

Sacropelvic parameters, including pelvic incidence, sacral slope, and pelvic tilt, were measured on both whole-spine radiographs and lower-limb scanograms by three independent examiners on three separate occasions.

METHODS

Agreement regarding the measurements on both image types was calculated to assess the validity of the lateral scanogram for use in whole-body alignment determinations. Intraobserver and interobserver reliabilities among the types of measurements were calculated.

RESULTS

The sacropelvic area on the lateral scanogram was not visible in 19 patients (19%). In the remaining 81 patients, the sacropelvic parameters on the lateral scanogram were similar to those on the whole-spine lateral radiograph (Pearson correlation coefficient, 0.764-0.805). Intraobserver and interobserver reproducibilities for both modalities were good to excellent (intraclass correlation coefficient, 0.657-0.984).

CONCLUSIONS

Sacropelvic parameter measurements on lateral scanogram were reliable and were similar to those measured on whole-spine lateral radiograph. Thus, global alignment can be evaluated using the lateral scanogram in combination with the whole-spine lateral radiograph.

The association between whole body sagittal balance and risk of falls among elderly patients seeking treatment for back pain

Objectives

The objective of this study was to assess the association between whole body sagittal balance and risk of falls in elderly patients who have sought treatment for back pain. Balanced spinal sagittal alignment is known to be important for the prevention of falls. However, spinal sagittal imbalance can be markedly compensated by the lower extremities, and whole body sagittal balance including the lower extremities should be assessed to evaluate actual imbalances related to falls.

Methods

Patients over 70 years old who visited an outpatient clinic for back pain treatment and underwent a standing whole-body radiograph were enrolled. Falls were prospectively assessed for 12 months using a monthly fall diary, and patients were divided into fallers and non-fallers according to the history of falls. Radiological parameters from whole-body radiographs and clinical data were compared between the two groups.

Results

A total of 144 patients (120 female patients and 24 male patients) completed a 12-month follow-up for assessing falls. A total of 31 patients (21.5%) reported at least one fall within the 12-month follow-up. In univariate logistic regression analysis, the risk of falls was significantly increased in older patients and those with more medical comorbidities, decreased lumbar lordosis, increased sagittal vertical axis, and increased horizontal distance between the C7 plumb line and the centre of the ankle (C7A). Increased C7A was significantly associated with increased risk of falls even after multivariate adjustment.

Conclusion

Whole body sagittal balance, measured by the horizontal distance between the C7 plumb line and the centre of the ankle, was significantly associated with risk of falls among elderly patients with back pain.

Cite this article: J. Kim, J. Y. Hwang, J. K. Oh, M. S. Park, S. W. Kim, H. Chang, T-H. Kim. The association between whole body sagittal balance and risk of falls among elderly patients seeking treatment for back pain. Bone Joint Res 2017;6:–344. DOI: 10.1302/2046-3758.65.BJR-2016-0271.R2.

Relationships among spinal mobility and sagittal alignment of spine and lower extremity to quality of life and risk of falls

Spinal deformities can affect quality of life (QOL) and risk of falling, but no studies have explored the relationships of spinal mobility and sagittal alignment of spine and the lower extremities simultaneously. Purpose of this study is to clarify the relationship of those postural parameters to QOL and risk of falling. The study evaluated 110 subjects (41 men, 69 women; mean age, 73 years). Upright and flexion and extension angles for thoracic kyphosis, lumbar lordosis, and spinal inclination were evaluated with SpinalMouse^®. Total-body inclination and hip and knee flexion angles in upright position were measured from lateral photographs. Subjects were divided into Fallers (n=23, 21%) and Non-fallers (n=87, 79%) based on past history of falls. QOL was assessed using the Short Form 36 Health Survey (SF-36^®). Age, total-body inclination, spinal inclination upright and in extension, thoracic kyphosis in flexion, lumbar lordosis upright and in extension, and knee flexion correlated significantly with the SF-36. Multiple regression analysis revealed total-body inclination and knee flexion to have the most significant relationships with the SF-36. SF-36, total-body inclination, spinal inclination in extension, thoracic kyphosis in flexion, lumbar lordosis upright and in extension, and hip and knee flexion angles differed significantly between Fallers and Non-fallers (P<0.05 for all). Multivariate logistic regression analyses revealed lumbar lordosis in extension to be a significant predictor of falling (P=0.038). Forward-stooped posture and knee-flexion deformity could be important indicator of lower QOL. Moreover, limited extension in the lumbar spine could be a useful screening examination for fall prevention in the elderly.

The global alignment in patients with lumbar spinal stenosis: our experience using the EOS full-body images

Lumbar stenosis is frequently observed and treated by spine surgeons. The extent of neurological decompression and the potential spinal fixation are the basic concerns when surgery is planned. But this segmented approach to the problem is sometimes insufficient due to the complex functional situations induced by a sagittal imbalance of the patient and the combination of pathologies known as hip-spine or knee-spine syndromes. A total of 373 consecutive patients included from our EOS and clinical data base. Patients were divided in two groups. Group A included patients presenting exclusive spinal issues (172 cases) out of whom 117 (68 %) had sagittal imbalance. Among 201 patients with associated lower limbs issues (group B), 122 (61 %) had sagittal imbalance. The perception of imbalance was noticed in 54 % (93 cases) in group A and 57 % (115 cases) in group B. In the global series of 239 imbalanced cases, the key point was a spine issue for 165 patients (the 117 patients with only spine problems and 48/122 cases with combined spine and lower limbs problems). But in the patients with combined spine and lower limbs problems, we individualized hip-spine syndromes (24/122 patients) and knee-spine syndromes (13/122 patients). In some cases, (37/122 patients) the anatomical and functional situations were more complex to characterize a spine-hip or a hip-spine problem. The EOS full-body images provide new information regarding the global spinal and lower limbs alignment to improve the understanding of the patient functional posture. This study highlights the importance of the lower limb evaluation not only as compensatory mechanism of the spinal problems but also as an individualized parameter with its own influence on the global balance analysis. Level of evidence IV diagnostic case series.

Sagittal alignment of the spine-pelvis-lower extremity axis in patients with severe knee osteoarthritis: A radiographic study

Objectives

Normal sagittal spine-pelvis-lower extremity alignment is crucial in humans for maintaining an ergonomic upright standing posture, and pathogenesis in any segment leads to poor balance. The present study aimed to investigate how this sagittal alignment can be affected by severe knee osteoarthritis (KOA), and whether associated changes corresponded with symptoms of lower back pain (LBP) in this patient population.

Methods

Lateral radiograph films in an upright standing position were obtained from 59 patients with severe KOA and 58 asymptomatic controls free from KOA. Sagittal alignment of the spine, pelvis, hip and proximal femur was quantified by measuring several radiographic parameters. Global balance was accessed according to the relative position of the C7 plumb line to the sacrum and femoral heads. The presence of chronic LBP was documented. Comparisons between the two groups were carried by independent samples t-tests or chi-squared test.

Results

Patients with severe KOA showed significant backward femoral inclination (FI), hip flexion, forward spinal inclination, and higher prevalence of global imbalance (27.1% versus 3.4%, p < 0.001) compared with controls. In addition, patients with FI of 10° (n = 23) showed reduced lumbar lordosis and significant forward spinal inclination compared with controls, whereas those with FI > 10° (n = 36) presented with significant pelvic anteversion and hip flexion. A total of 39 patients with KOA (66.1%) suffered from LBP. There was no significant difference in sagittal alignment between KOA patients with and without LBP.

Conclusions

The sagittal alignment of spine-pelvis-lower extremity axis was significantly influenced by severe KOA. The lumbar spine served as the primary source of compensation, while hip flexion and pelvic anteversion increased for further compensation. Changes in sagittal alignment may not be involved in the pathogenesis of LBP in this patient population.

Cite this article: W. J. Wang, F. Liu, Y.W. Zhu, M.H. Sun, Y. Qiu, W. J. Weng. Sagittal alignment of the spine-pelvis-lower extremity axis in patients with severe knee osteoarthritis: A radiographic study. Bone Joint Res 2016;5:198–205. DOI:10.1302/2046-3758.55.2000538.