Hip torsional deformities at lumbar disc disease

Background Presence of lumbar spine disorder with hip diseases is dened as Hip-Spine syndrome, there might be a relation between hip torsional deformities and lumbar disc disease which has not claried previously. Purpose of the present study was to nd whether hip torsional parameters (femur, acetabular anteversion) and clinical ndings (hip range of motion, hip score) differ at patients with lumbar disc disease. Methods Patients with lomber disc herniation (n: and control subjects (n: without any lumbar or were Femoral anteversion (FeAv), acetabular anteversion (AA), of (CE), of were


Introduction
Presence of lumbar spine disorder with hip diseases is de ned as Hip-Spine syndrome and rst called in 1983 [1]. Various hip pathologies like exion deformities, osteoarthritis, and limited hip range of motion, possibly femur retroversion have been related to lumbar pathologies [1][2][3][4][5]. There are reports getting relief of lower back pain when hip conditions are treated with hip arthroscopy or arthroplasty [2,5]. In addition, in a recent biomechanical study, it was shown that limitation of the terminal hip extension due to ischiofemoral impingement led to increase of lumbar facet (L3-4 and L4-5) joint load compared to normal native hips [6].
Additionally, torsional deformities and/ or limited range of motion of the hip have been reported to be linked to hip osteoarthritis that increase in femoral anteversion and /or acetabular retroversion or decreased acetabular anteversion predisposes to hip osteoarthritis [7][8][9][10][11][12].
The purpose of the present study is to examine the relation of hip torsional parameters (femur, acetabular anteversion), clinical ndings (hip range of motion, harris hip score) to lumbar disc disease [13].
Hypothesis is that patients with lumbar disc herniation would have decreased femur and/or acetabular version and ROM compared to control subjects without any hip or spine disease.

Materials And Methods
Patients with lomber disc herniation without any hip related symptoms and osteoarthritis ndings at their pelvic x-rays, whom were elected to go surgery at our neurosurgery department, comprised the study group (group P). The control group (Group C) was based on the computed tomographic analysis of hip joints that had already been performed on patients who were referred to our radiology department, because of abdomino-pelvic diseases and who had healthy hip joints in their scanograms without any symptoms related to lumbar vertebrae or hip joint. Our local ethics committee approved this study.
Written and informed consents were obtained from both the patients and the control subjects. 20 patients (group P), 20 control subjects (group C) were included. Demographic data is present at Table  I. The CT examinations were performed in supine position with femurs in neutral rotation and the hips and knees in extension and with the patellae pointing directly upwards. Scanograms were obtained between the anterior superior iliac spine and the level distal to the knee joint in the frontal plane.
Patients were scanned according to standard departmental protocols at 120 kVp and 140 to180 mAs depending on patient weight and/or girth. Axial CT images with 3 mm slice thickness were obtained within the framework of standart departmental protocols.
The FeAv was calculated as the angle between the projected head-neck line and the line that intersects the anterior and posterior condylar tangents. The tomogram section with largest head diameter was projected on the other section with largest, best vision of femur neck. The centres of femur head and femur neck were identi ed. The projected head-neck line was determined by connecting these two centres. While measuring acetabular anteversion, A coronal slice (slice B ) was selected giving optimum visualization of the pelvic teardrop (Figure 1

Statistics
The SPSS for Windows version 15.0 (SPSS Inc., Chicago,IL, USA) was used to place the data. Chi-Square test was used to compare the groups for the distribution female and male subjects. Mann-Whitney test was used to investigate sex, tested variables difference between groups. Wilcoxon signed rank test was used to compare herniated side's parameters to contralateral asymptomatic side.

Results
There was no difference between groups regarding age and Sex (p>0.05).
Data is presented at Table II (bilateral sides+unilateral=herniated side, control: mean value of both sides).
HHS score, degree of extension plus exion was lower at diseased side compared to control subjects (p<0.001).
When only unilaterally affected patients were included, AA was also found to be lower compared to control subjects (AA: 13±4(12) 0 , p:0.01). At unilaterally affected patients, diseased side had lower degrees exion and extension, HHS points compared to contralateral asymptomatic side (p<0.001). Furthermore, there was a trend of lower AA at symptomatic side compared to contralateral side that came close to statistical signi cance (p:0.07).

Discussion
As there is a link between hip and spine disorders, present study aims to nd whether there is a causal relation between hip torsional deviations and lumbar disc disease. Partially supporting the hypothesis, diseased side had lower degrees of acetabular anteversion compared to control subjects at unilaterally affected patients.
Both femoral anteversion , acetabular antversion abnormalities have been described in pathogenesis of hip osteoarthritis [7][8][9][10][11][12]15] and hip osteoarthritis is being linked to lumbar spine disease. However; none of study in the literature directly searched causal relationship of these parameters at lumbar disc disease.
Present study found no difference when bilateral cases were included; which in turn may point the mechanic and /or hip torsional parameters has an etiopathogenetic role at unilateral disease.
According to a recent review reported, patients with low back pain frequently have limited hip range of motion especially the hip exion and patients had relief of back pain when hip osteoarthritis was treated with arthroplasty [16]. However; they did not nd any study pointing out bene cial effect of the improvement of hip internal rotation after hip arthroscopy for femoro-acetabular impingement on lumbopelvic stress. Differing from present study, patient with advanced hip osteoarthritis receiving hip arthroplasty with nonspeci c lumbar spine disease were reported [2, [16][17].
We also found decreased hip exion and extension at patient group similarly reported in the literature.
Recently Chadayammuri et al reported decreased degree of hip exion (mean 104 0 ) with acetabular retroversion with no effect of femoral torsion [7]. At an anatomic study of ischio-femoral impingement model with concamittant decrease of terminal hip extension, Gomes-Hoyos et al reported increase of the L3-4 and L4-5 lumbar facet joint load [6].
There are limitations. Firstly, we excluded hip osteoarthritis with questioning of symptoms and from pelvic radiographs and did not stage speci cally status of the hip according to the Tönnis staging which in turn early stages of Tönnis grading might have in uenced the results [12]. Secondly, we did not measure the degree of hip rotation and abd/adduction, since we did not speci cally look for the presence of femoro-acetabular impingement rather measure the main movement arc of the hip ' exion/extension' which is reported to be linked to spine disorders [16]. Although patients were under pain medication during the study, loss of hip extension, exion might have been overestimated by the patient group due to possible muscular spasm secondary to back or leg pain. Lastly, we did not evaluate the effect of grade or the level of the lumbar disc herniation which possibly is the subject of future studies. On behalf of all the contributors I will act and guarantor and will correspond with the journal from this point onward.

List Of Abbreviations
This article has not been published and has no con ict of interest.
We hereby transfer, assign, or otherwise convey all copyright ownership, including any and all rights incidental thereto, exclusively to the journal, in the event that such work is published by the journal.
We would like to suggest following referees for the article.

Data and Materials
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Con ict of Interest
The authors declare that they have no con ict of interest.
----  Figure 1 Coronal image showing the acetabulum divided by three lines