Overview and Spinal Implications of Leg Length Discrepancy: Narrative Review

Can We Screen for Limb Length Discrepancy on Spinal Radiographs of Patients With Adolescent Idiopathic Scoliosis?

BACKGROUND

The aim of this study was to determine whether height differences in the levels of the iliac crests and femoral heads on erect spinal radiographs can be used as indirect measurements for the screening and surveillance of limb length discrepancy (LLD) in patients with scoliosis.

METHODS

Whole body posteroanterior (PA) and lateral erect radiographs of patients with adolescent idiopathic scoliosis (AIS) were retrospectively reviewed. Patients with congenital, syndromic, and neuromuscular scoliosis were excluded. A direct measurement of each limb was taken from the highest point of the femoral head to the middle of the tibial plafond; any difference between the sides was recorded as the LLD. In addition, the PACS Software tool was used to measure femoral head height difference (FHHD) and iliac crest height difference (ICHD). Pearson's correlation, linear regression, and Bland-Altman plots were used to determine the relationships between LLD and FHHD, and LLD and ICHD.

RESULTS

Radiographs of 141 patients (92 women, 49 men) with an average age of 12.0±2.65 years were analyzed. A strong correlation (r=0.730, P<0.001) was found between LLD and FHHD; the correlation between LLD and ICHD was weaker (r=0.585, P<0.001). The Bland-Altman analysis showed good agreements of LLD with FHHD and ICHD. Linear regression analysis predicted an LLD of ≤10 mm based on an FHHD of ≤11.5 mm or an ICHD of ≤15.3 mm.

CONCLUSIONS

FHHD and ICHD on spinal PA radiographs can be used for the screening and monitoring of LLD in patients with AIS with FHHD being the preferred indirect measurement. These measurements are readily learned and quick to perform. The FHHD and ICHD can be measured on any erect scoliosis PA radiograph. Therefore, these proxy measurements can be used to screen and monitor for LLD in patients with AIS.

LEVEL OF EVIDENCE

Level III.

Does the limb lengthening reduce the incidence of hip dislocation in patients with neurological disorders and insufficient muscle tension who undergoing hip arthroplasty?

Background

The soft-tissue tension is closely associated with postoperative hip dislocation in patients undergoing total hip arthroplasty (THA), especially for those patients with neurological disorders and insufficient muscle tension. The aim of this study is to explore the effect of limb lengthening on the incidence of complications following THA in patients with neurological disorders and insufficient muscle tension.

Methods

This retrospective analysis examines individuals with neurological disorders, such as ischemic stroke and poliomyelitis, who underwent primary total hip arthroplasty (THA) at our medical center between January 2015 and April 2021. Demographic and baseline characteristics (such as age, gender, muscle strength) were obtained from medical records. The limb length, offset and the positional parameters of both acetabular and femoral component were measured on pre- and postoperative plain radiograph. The primary outcome was the occurrence of hip dislocation. The secondary outcome included the incidence of other complications and the hip function (determined by Harris score). The correlation between the occurrence of hip dislocation and limb lengthening was analyzed.

Results

A total of 258 patients were finally analyzed. The hip dislocations were identified in 35 patients (overall incidence = 13.57%). The incidence of early dislocation was lower in patients whose limb-length discrepancy (LLD) was over 20 mm (incidence = 4.1% for LLD >20 mm, 12.2% for LLD 10 mm-20 mm and 17% for LLD <10 mm). The odds ratio (OR) was 0.206 and 95% confidence interval (CI) was 0.058-0.737 (compared between LLD <10 mm and LLD >20 mm). But the no difference was identified regarding on the incidence of late dislocation among patients with different LLD. Moreover, the overall incidence of other complications was elevated in patients with LLD >20 mm (incidence = 17.58% for LLD >20 mm, 11.11% for LLD 10 mm-20 mm and 3.19% for LLD <10 mm; OR = 6.464, 95% CI = 1.768-23.640). And the Harris scores, which reflected the hip function, was gradually decreased with the increasing in LLD. In terms of the relationship between the offset and dislocation rate, it was found that increased offset discrepancy was associated with decreased dislocation incidence (incidence = 4.71% for offset discrepancy >10 mm, 12.5% for offset discrepancy 5 mm-10 mm and 17.20% for offset discrepancy <5 mm; OR = 0.238, 95% CI = 0.076-0.742). Furthermore, increased offset discrepancy also bring a reduction in late dislocation. The incidences of late dislocation were 0%, 2.5% and 10.8% for offset discrepancy >10 mm, offset discrepancy 5 mm-10 mm and 17.20% for offset discrepancy respectively. Different from that of LDD, the incidences of other complications were similar among patients with different offset discrepancy. Besides, no influence of offset discrepancy on the hip function was identified in this study.

Conclusion

Unfortunately, although increasing in limb length could partially reduce early dislocation postoperatively, it could not affect the incidence of late dislocation in those patients with neurological disorders and insufficient muscle tension. Moreover, over limb lengthening was associated with other postoperative complications and worse hip function. Instead, additional offset could reduce the probability of postoperative dislocation, without increasing the incidence of other complications. Therefore, femoral stem with lower cervico-diaphyseal angle (higher offset) should be recommended to patients with neurological disorders who were in high risk of postoperative dislocation. Isolated increasing in limb length should be avoided.

Deep learning generated lower extremity radiographic measurements are adequate for quick assessment of knee angular alignment and leg length determination

PURPOSE

Angular and longitudinal deformities of leg alignment create excessive stresses across joints, leading to pain and impaired function. Multiple measurements are used to assess these deformities on anteroposterior (AP) full-length radiographs. An artificial intelligence (AI) software automatically locates anatomical landmarks on AP full-length radiographs and performs 13 measurements to assess knee angular alignment and leg length. The primary aim of this study was to evaluate the agreements in LLD and knee alignment measurements between an AI software and two board-certified radiologists in patients without metal implants. The secondary aim was to assess time savings achieved by AI.

METHODS

The measurements assessed in the study were hip-knee-angle (HKA), anatomical-tibiofemoral angle (aTFA), anatomical-mechanical-axis angle (AMA), joint-line-convergence angle (JLCA), mechanical-lateral-proximal-femur-angle (mLPFA), mechanical-lateral-distal-femur-angle (mLDFA), mechanical-medial-proximal-tibia-angle (mMPTA), mechanical-lateral-distal-tibia- angle (mLDTA), femur length, tibia length, full leg length, leg length discrepancy (LLD), and mechanical axis deviation (MAD). These measurements were performed by two radiologists and the AI software on 164 legs. Intraclass-correlation-coefficients (ICC) and Bland-Altman analyses were used to assess the AI's performance.

RESULTS

The AI software set incorrect landmarks for 11/164 legs. Excluding these cases, ICCs between the software and radiologists were excellent for 12/13 variables (11/13 with outliers included), and the AI software met performance targets for 11/13 variables (9/13 with outliers included). The mean reading time for the AI algorithm and two readers, respectively, was 38.3, 435.0, and 625.0 s.

CONCLUSION

This study demonstrated that, with few exceptions, this AI-based software reliably generated measurements for most variables in the study and provided substantial time savings.

Parietal abdominal pain with lower leg discrepancy: a case report

BACKGROUND

This report involves the first publication describing a case of parietal abdominal pain due to lower limb length discrepancy.

CASE PRESENTATION

A Caucasian male patient in his 50s was referred to our rehabilitation department with chronic abdominal pain that began in childhood. This chronic pain was associated with episodes of acute pain that were partially relieved by grade 3 analgesics. The patient was unable to sit for long periods, had recently lost his job, and was unable to participate in recreational activities with his children. Investigations revealed contracture and hypertrophy of the external oblique muscle and an limb length discrepancy of 3.8 cm (1.5 inches) in the left lower limb. The patient was effectively treated with a heel raise, physiotherapy, intramuscular injection of botulinum toxin, and lidocaine. The patient achieved the therapeutic goals of returning to work, and reducing analgesic use.

CONCLUSIONS

Structural misbalances, as may be caused by lower leg discrepancy, may trigger muscular compensations and pain. Complete anamnesis and clinical examination must not be trivialized and may reveal previously ignored information leading to a proper diagnosis.

Kaposiform Hemangioendothelioma with Bone Destruction: A 16-Year Follow-Up Cohort Study of the Clinical Characteristics and Prognosis

BACKGROUND

Kaposiform hemangioendothelioma (KHE) is a rare, locally aggressive vascular tumor that often occurs in infants and young children. The goal of this study was to analyze the clinical characteristics of KHE patients with bone destruction and provide clinical guidance for diagnosis and treatment.

METHODS

We conducted a descriptive cohort study with follow-up from January 2007 to January 2023 to collect demographic information and tumor-related clinical information from KHE patients with bone destruction.

RESULTS

A total of 269 KHE patients were included in the study, of whom 70 (26.0%) patients had tumors with bone destruction. The median age at diagnosis of patients with bone destruction was 19.0 months, which was much later than that of patients without bone destruction (P < 0.001). Patients with bone destruction were more likely to have a decreased range of motion (ROM) (P < 0.001). Metaphysis involvement was more likely to occur in the lower limb bones (P = 0.039), and the lower limb bones were more likely to be associated with decreased ROM (P = 0.001). Tumors involving extracompartmental bone were more likely to have decreased ROM (P = 0.003) and exhibit the Kasabach-Merritt phenomenon (P = 0.006).

CONCLUSIONS

Based on the rarity and significant heterogeneity of KHE patients with bone destruction, we should give full play to the role of multidisciplinary teams in addressing disease to reduce the long-term complications of KHE with bone destruction and improve the quality of life of patients.

TYPE OF STUDY

Prognostic Study.

LEVEL OF EVIDENCE

Level II.

Effects of Artificially Induced Leg Length Discrepancy on Treadmill-Based Walking and Running Symmetry in Healthy College Students: A Lab-Based Experimental Study

Leg length discrepancy (LLD) is a common postural deviation of musculoskeletal origin, which causes compensatory reactions and often leads to injury. The aim of the study was to investigate the effect of artificially induced LLD on gait symmetry by means of the spatiotemporal gait parameters and ground reaction forces (GRFs) using a treadmill equipped with capacitive sensors (instrumented) as well as the EMG activity of trunk and hip muscles during walking and running. Twenty-six healthy male and female college students were required to perform two sets of four 2.5-min walking and running trials on an instrumented treadmill at 5.6 and 8.1 km·h-1, respectively, without (0) and with 1, 2, and 3 cm LLD implemented by wearing a special rubber shoe. Statistical analysis was performed using one-way repeated measures or a mixed-design ANOVA. Most spatiotemporal gait parameters and GRFs demonstrated an increase or decrease as LLD increased either on the short-limb or the long-limb side, with changes becoming more apparent at ≥1 cm LLD during walking and ≥2 cm LLD during running. The EMG activity of trunk and hip muscles was not affected by LLD. Our findings showed that gait symmetry in terms of treadmill-based spatiotemporal parameters of gait and GRFs is affected by LLD, the magnitude of which depends on the speed of locomotion.

Mechanical behaviors of titanium, nickel-titanium, and stainless elastic intramedullary nail in fixation of tibial diaphyseal fractures

INTRODUCTION

Elastic nails have been widely used in the diaphyseal fracture fixation of long bones in adolescents. However, high complication rates have been reported in cases involving weights exceeding 55 kg. The existing nails are fabricated with different metals in clinical settings; however, the effect of the materials on the mechanical responses of the fractured bone remains unclear. Hence, the present study is conducted to compare the mechanical responses of typically used metals, namely titanium, stainless, and nickel-titanium, for elastic nails in the fixation of tibial diaphyseal fractures.

MATERIAL AND METHODS

A sawbone tube is used to determine the contact force, which is developed after constraining the nail inside the narrow canal using different nail materials. Furthermore, a finite element (FE) model of the tibial diaphyseal fracture is developed to predict the fracture gap deformation based on different nail materials under axial compression and bending loads. The push-out force in the FE simulation is compared with that of a case without an end cap.

RESULTS

In the sawbone tube, the results indicate that the contact force developed by the titanium nail is significantly higher than those developed by stainless and nickel-titanium nails. The contact forces developed by the titanium, stainless steel, and nickel- titanium nails are 385 (SD 34), 358 (SD 49), and 258 (SD 42) N, respectively. In the FE simulation, the titanium nail yields the highest push-out force when an end cap is not used, and the push-out forces in axial compression are 201, 183, and 87 N in the titanium, stainless, and nickel-titanium nails under axial compression, respectively. By contrast, the stainless nail yields the smallest gap deformation when an end cap is used.

CONCLUSION

Results of the present study show that the end cap is an important factor affecting the mechanical responses of nails fabricated using different materials. Titanium nails are preferred when an end cap is not used, whereas stainless nails are preferred when an end cap is used.

The efficacy and safety of direct superior approach (DSA) for total hip arthroplasty: a systematic review and meta-analysis

OBJECTIVE

To systematically evaluate the clinical safety and efficacy of the direct superior approach and the conventional surgical approach.

DATE SOURCES

From PubMed, Embase, the Cochrane Library, and China Knowledge Network up to January 30, 2023.

MAIN RESULTS

A total of 7 case series involving 4306 patients undergoing total hip arthroplasty were included, including 679 patients with direct superior approach. All outcome measures: Oxford Hip Score [MD = 0.30, 95% CI (- 0.87, 1.47), P = 0.62], Hip Harris Score [MD = - 0.18, 95% CI (- 0.86, 0.49), P = 0.59], intraoperative blood loss [MD = - 54.14, 95% CI (- 102.75,-5.52), P = 0.03], transfusion rate [MD = 0.49, 95% CI (0.29, 0.83), P = 0.008], Limb Length Differences [MD = - 0.21, 95% CI (0.02, 0.39), P = 0.03], Length of Stay [MD = - 0.61, 95% CI (- 0.69, - 0.52), P < 0.00001].

CONCLUSIONS

The DSA was superior to conventional access in terms of incision length, bleeding, postoperative transfusion rate, and early postoperative HHS. In addition, our study found that because the DSA has less tissue damage, it has the potential advantages of accelerating patient recovery after surgery, shortening hospitalization time, and reducing patient economic pressure, which can significantly improve patient quality of life and satisfaction.

Femoral Magnetic Lengthening After Distal Femur Endoprosthetic Reconstruction in a Pediatric Patient: A Case Report

CASE

A 10-year-old boy with osteosarcoma of the left distal femur underwent resection with compressive osseointegration endoprosthetic reconstruction, gradually resulting in a 4.5-cm leg-length difference with significant predicted progression. Two years after resection, he underwent right distal femur and proximal tibia epiphysiodesis and placement of a left femoral magnetic lengthening nail. At 2 years after lengthening and skeletal maturity, the patient has symmetric limb lengths, no pain, and returned to sports.

CONCLUSION

A magnetic lengthening nail with contralateral epiphysiodesis is a viable option for correcting limb-length discrepancy after distal femur endoprosthetic reconstruction in a pediatric patient.

The radiation dose, clinical and anatomical implications of erect lumbar spine radiography: A single centre pre-post implementation evaluation

INTRODUCTION

Lumbar radiographs remain a common imaging examination despite strategies to reduce their use. Many authors have demonstrated benefits in changing from traditional supine and recumbent lateral projections to a prone and/or erect orientation. Despite evidence of clinical and radiation dose optimisation, widespread adoption of these strategies has stalled. This article describes the single-centre implementation and evaluation of erect PA and lateral projections.

METHOD

This was an observational study pre- and post-implementation of an erect imaging protocol. Patient BMI, image field size, source image and source object distances and DAP were collected together with assessment of radiographic spinal alignment and disc space demonstration. Effective dose was calculated with organ specific doses.

RESULTS

76 (53.5%) patients were imaged in the supine AP and recumbent lateral position, 66 (46.5%) had erect PA and lateral radiographs. Despite the larger BMI of the erect cohort and similar field sizes, effective dose was lower in the PA position by an average of 20% (p < 0.05), however, no significant difference in lateral dose. Anatomical improvements were evident with greater visualisation of intervertebral disc spaces in the PA erect (t = -9.03; p < .001) and lateral (t = -10.298; p < .001) orientations. Erect PA radiographs demonstrated a leg length discrepancy in 47.0% (0.3-4.7 cm) and a scoliosis in 21.2% of cases, with a significant link between these findings (r (64) = 0.44; p < .001).

CONCLUSION

Erect lumbar spine radiography provides information on clinical outcomes not available with recumbent projections. The improvements in anatomical visualisation and radiation dose reduction supports the local change in practice.

IMPLICATIONS FOR PRACTICE

- Erect imaging can reduce effective dose with an optimised acquisition protocol - additional pathological information can be revealed by the erect posture. - postural awareness is critical to interpret images accurately.

Impact of bilateral motion control shoes with outsole adjustment on gait asymmetry in individuals with mild leg length discrepancy

BACKGROUND

Footwear adjustment is recommended in the management plan of leg length discrepancy. However, it is not clear how the outsole of motion control shoe adjustment influences trunk symmetry and walking performance.

RESEARCH QUESTION

Does bilateral adjustment of the outsole affect trunk and pelvis symmetry and ground reaction force during walking in individuals with leg length discrepancy?

METHODS

20 mild leg length discrepancy participants were recruited into a cross-sectional study. All subjects performed a walking trial with their habitual shoes to determine the outsole adjustment. Four trials of walking were carried out in the order of unadjusted and bilateral adjusted motion control air-cushion shoes. Shoulder level differences and trunk and pelvic motion were assessed, while the ground reaction force at the heel strike was reported. A paired t-test was performed to compare the differences between the conditions with a significance level at p < 0.05.

RESULTS

During walking trials, mild leg length discrepancy participants with the adjusted shoe displayed lower variations in the maximum shoulder height differences (p = 0.001) and trunk rotation angle (p = 0.002) than those with the unadjusted shoe. Also, there was a significant reduction in the vertical ground reaction force (p = 0.030), but not in the anteroposterior or mediolateral directions, during walking in the adjusted shoe condition compared to the unadjusted shoe condition.

SIGNIFICANCE

The outsole adjustment of the bilateral motion control shoes can improve trunk symmetry while decreasing the ground impact at the heel strike. The study provides additional information to prescribe or recommend footwear adjustment to improve walking symmetry in leg length discrepancy participants.

Asymmetry of the pelvis in Polish young adults

Introduction

Symmetry is one of the criteria of correct body posture in upright position. The spatial positioning of the pelvic girdle is crucial to it. Functional and structural asymmetries within the lumbo-pelvic-hip complex can have a significant influence on the structure and functions of many human body organs and systems. The aim of the study was to present the results of inclinometer measurements of selected landmarks of the pelvic girdle in young adults aged 19-29.

Methods

The analysis of occurrence of spatial pelvic asymmetry was based on the authors' original, clinical classification and the significance of the body mass and height for the analyzed asymmetries. The inclinometer measurements of the selected landmarks of the pelvic girdle were performed in a sample consisting of 300 young individuals. Then, the occurrences of the spatial asymmetry of the pelvis were analyzed based on the authors' own clinical classification using alignment symmetry of the iliac crests, the anterior superior iliac spines and the trochanters major as a criterion. All study subjects with asymmetry <1 degree were treated as those with a symmetrical pelvis.

Results

The significance of gender, body mass and height for the analyzed asymmetries was assessed. Symmetric positioning of the iliac crests was observed in only 32% of the respondents. The iliac crest depression on the left side was more frequently observed - in 41% of the respondents. This occurred more often in women (44%) than in men (38%). In the group of women, the rotated pelvis was the most often observed (39.4%) asymmetry, while for men, it was the oblique pelvis (40%). More detailed analysis by pelvic asymmetry subtypes showed their statistical differentiation between women and men (p    <     0.0001). Analysis of moderate rotation of the pelvis for men, were reported slightly higher values but these differences were not statistically significant (p = 0.253). Women, in turn, showed slightly higher mean values but here too, the differences were not statistically significant (p = 0.245).

Discussion

Asymmetries in the pelvis area are common; they were observed in less than three-quarters of the examined population. Oblique pelvis was found in less than a quarter of women and in more than one-third men with the predominant structural asymmetries. Rotated pelvis was observed in more than one-third of women and men with dominating functional asymmetries. There were no linear correlations between the body mass and height, and the angle of asymmetries.

The Importance of Monitoring and Factors That May Influence Leg Length Difference in Developmental Dysplasia of the Hip

In unilateral Developmental Dysplasia of the Hip (DDH), avascular necrosis (AVN), femoral or pelvic osteotomy, and residual dysplasia causing subluxation of the proximal femur may influence Leg Length Discrepancy (LLD). This can lead to gait compensation, pelvic obliquity, and spinal curvature. The aim of this study is to determine the prevalence of LLD, establish which limb segment contributes to the discrepancy, describe how AVN influences LLD, and ascertain variables that may influence the need for LLD corrective procedures.

METHODOLOGY

This study assessed long-leg radiographs at skeletal maturity. Radiographs were assessed for the articulo-trochanteric distance (ATD) and femoral and tibial length. AVN was classified according to Kalamchi-MacEwen.

RESULTS

109 patients were included. The affected/DDH leg was longer in 72/109 (66%) patients. The length difference was mainly in the subtrochanteric segment of the femur. AVN negatively influenced leg length. Older (≥three years) patients with multiple procedures were more likely to have AVN. LLD interventions were performed in 30 (27.5%) patients. AVN grade or type of DDH surgery did not influence the odds of needing a procedure to correct LLD.

CONCLUSIONS

Procedures to correct LLD were performed irrespective of previous DDH surgery or AVN grades. In most patients, the affected/DDH leg was longer, mainly in the subtrochanteric segment of the femur, largely influenced by femoral osteotomy in patients with multiple operative procedures for DDH. We recommend careful monitoring of LLD in DDH.

Tilt and mobility of the hip girdle in the sagittal and frontal planes in healthy subjects aged 19-30 years

BACKGROUND

Disturbances in pelvic girdle tilt can cause compensatory changes affecting postural dysfunctions, and can lead to hip and groin strain changes and back pain. However, we still have no clear information on the normative values of pelvic girdle tilt and mobility.

OBJECTIVE

The study aimed to (1) evaluate the position and mobility of the pelvic girdle in the sagittal and frontal planes in asymptomatic adults aged 19-30, (2) evaluate the possible variation of results according to gender and to develop a proposal for normative values, and (3) evaluate whether body mass, height and BMI are related to the magnitude of hip girdle position and mobility.

METHODS

The research was conducted in a sample group consisting of 346 men and women using the scaled form of the anthropometric level of the Duometr® The values of position and mobility of the pelvic girdle in the sagittal and frontal planes were analyzed.

RESULTS

Differences were noted in the values of the pelvic tilt (p= 0.033) between the men and women. The women showed slightly higher values of posterior range of motion (p= 0.0002) and total range of motion (p= 0.002). The other parameters did not show any significant variation. There was no clear association between body weight, height and BMI and the study variables, except for a small, significant correlation between BMI and posterior pelvic tilt in women (r= 0.175, p= 0.005). In the frontal plane there were no differences in the analyzed variables in terms of gender or side of the body measured.

CONCLUSIONS

There was no association between the anthropometric variables and the pelvic girdle tilt and mobility. No size variation by gender was observed in the frontal plane. Slight differences were observed in the sagittal plane. Normative values are proposed.

The Comparison of Lower Extremity Length and Angle between Computed Radiography-Based Teleoroentgenogram and EOS® Imaging System

Background and objectives: The differences between computed radiography-based teleoroentgenograms (CR-based teleoroentgenograms) and an EOS® imaging system were evaluated by measuring lower extremity lengths and alignments. Materials and methods: The leg length [L], femur length [F], tibia length [T], and hip−knee−ankle (HKA) angle were measured in 101 patients with lower extremity disease by a CR-based teleoroentgenogram with computed radiography and an EOS®. The additive length of the femoral and tibial segments (F + T) was determined by adding the two length values. Then, the differences among all five parameters between the two techniques were analyzed. The magnification (mm) was calculated by subtracting the length measurements on the EOS® from those in the scanogram. Furthermore, the magnification percentage (%) was calculated by dividing the magnification with the measurements on the EOS®. Results: The magnification errors (mean ± standard deviation), when comparing both right and left sides, were 7.80 ± 1.41%, 7.3 ± 6.01%, 5.16 ± 1.25%, and 6.45 ± 0.94% for L, F, T, and F + T, respectively. For limb length, the CR-based teleoroentgenogram had an average magnification of 6.8% (range, 5.2 to 7.8%) compared to the EOS® imaging. The two groups displayed a statistical difference (p < 0.01), except for the HKA angle. Conclusions: The CR-based teleoroentgenogram had a magnification of about 6.8% compared to the EOS® imaging system in evaluating lower extremity length. Therefore, more attention must be given to CR-based teleoroentgenograms to correct angular deformities.