Author(s): David Guerrero Ramos, Itziar Pérez Terol, Francisca Peydro de Moya, Ignacio Bermejo Bosch

Low back pain is a health problem with enormous medical and social costs. One of the main causes is the degeneration of the intervertebral discs. This structural alteration presents a wide range of symptoms and requires new tools to facilitate the decision-making process and the most appropriate treatment approach.

This study describes a) the biomechanical analysis parameters that are relevant to the assessment of lumbar spine functionality using the NedLumbar/IBV software, and b) how instrumented biomechanical techniques can help healthcare professionals to select the optimal treatment strategy for each patient's pathology.

INTRODUCTION

Low back pain is a common health problem in adults, associated with enormous associated medical and social costs (1). It is the leading cause of disability worldwide (2). One of the major pathologies underlying back pain is the degeneration of the intervertebral discs caused by multiple factors such as genetic predisposition, aging, mechanical aggressions and/or the environment (1,3).

The intervertebral disc plays an important role in the mobility and stability of the intervertebral joint (4), and its structural deterioration compromises the integrity of the nucleus pulposus (2). Furthermore, each patient's subjective perception of pain makes it difficult to determine the true level of disability caused by discopathy and, therefore, to select the most appropriate treatment.

Biomechanical assessment is a tool that allows an objective evaluation of the extent to which discopathies affect the functionality of the lumbar spine. By measuring and then evaluating a series of parameters following the performance of a few simple gestures, physicians can make the most appropriate decision as to the strategy to be followed in each case. It also allows them to monitor the evolution of the follow up on the patient during his or her rehabilitation.

The purpose of this clinical case is to analyze the biomechanical parameters obtained from an assessment of the lumbar spine of a patient presenting a fracture and degenerative disc disease, using the NedLumbar/IBV software, in order to help the physician make the best decision regarding treatment.

CASE REPORT

A 54-year-old male presents with lumbar pain without irradiation to the lower limbs, which began after a sudden high-energy movement while descending a scaffold. His magnetic resonance imaging (MRI) report shows degenerative disc disease at all lumbar levels, without radicular involvement. The patient has an anterior vertebral plate fracture at the L3 level with bone edema, and an old vertebral fracture at the L1 level, while the results of the Lasègue and Bragard tests during the physical examination are positive .

The patient is referred to the Instituto de Biomecánica (IBV) for a functional assessment of the lumbar spine. These tests will help the physician to make the best decision as to the type of strategy that should be followed (surgical or conservative), and to plan rehabilitation appropriate to the biomechanical needs of the subject.

The software application used to perform the assessment is the NedLumbar/IBV (Figure 1), a medical software device for the biomechanical assessment of the lumbar spine that uses dynamic (force platform) and kinematic (3D photogrammetry) analysis recording techniques.

NedLumbar/IBV uses a protocolized functional assessment procedure that detects abnormal or non-functional pain-related movements. Two typical everyday activities are performed: getting up from a chair without armrests and lifting loads of 0.5 and 10 kg placed in front of the subject. It also compares the results obtained against a normality database developed by the IBV and associates the parameters obtained with a physiological pattern of movement according to the patient's characteristics. In this way, it provides an objective, reliable and easy-to-interpret complementary test that allows a more accurate and precise assessment of the subject's bodily damage.

Figure 1: Distribution of the markers while a subject performs the NedLumbar/IBV software test of getting up from a chair (left) and lifting a weight (right).

RESULTS AND DISCUSSION 

The overall result obtained (Figure 2) corresponds to an altered functionality, with a normality index of 68% (values equal to or greater than 90% are considered functionally normal). In addition, the collaboration index is 68% (values above 50% imply collaboration), which indicates that the patient’s effort corresponds to the maximum of his possibilities for the requested gestures.

Figure 2: Final result of the functionality of the lumbar spine through the biomechanical assessment of the activities of “Getting up from a chair” and “Lifting a weight”.

In the “Getting up from a chair” test (Figure 3), although the patient performs the activity with a slow movement (66%), the execution of the movement is smooth (100%), which implies good muscle coordination. However, the greater trunk inclination, the prolonged unloading phase and the limited extension indicate difficulty in generating strength and stability for lifting in the context of pain and weakness. In addition, a reduced mobility of the lumbar region can be observed with respect to subjects without any functional alteration (81%), which is compatible with his pain when mobilizing the lumbar spine.

Figure 3: Results obtained in absolute values (left) and in percentages of normality (right) for the variables of the “Getting up from a chair” activity.

The most demanding part of the test is the gesture that involves lifting a 10 kg box (Figure 4). What is most evident is that the movement is slow (73%), as in the previous test, which implies consistency with the results.

Figure 4: Results in absolute values (left) and in percentages of normality (right) for the variables of the activity “Lifting a weight of 10 kg”.

It can be observed that the patient employs a protective strategy by approaching the weight slowly, since the angular velocity of trunk flexion is 65%. In addition, when lifting the weight, he does so with insufficient str

ength due to pain and with a deficit of strength in trunk extension (as can be seen from the maximum angular acceleration of the trunk in extension of 55%). It should be noted that his flexibility in this gesture is good, with a lumbar range of 100%.

The following graph (Figure 5) shows how the velocity and acceleration throughout the entire trunk movement are below the normal range expressed in blue.

Figure 5: Representation of the angular velocity/acceleration of the trunk during the three repetitions of lifting 10 kg, together with its band of normality (blue).

In conclusion, it can be seen that the patient has a limitation in the initial lifting phase of the activities analyzed, probably related to his pain and lack of trunk strength.

Based on the results of the functional assessment of the lumbar spine using biomechanical assessment techniques (NedLumbar/IBV), the physician ruled out surgery in favor of a more conservative treatment focused mainly on an exercise program and non-steroidal anti-inflammatory drugs for pain relief.

The prescribed exercise program was tailored to the deficits revealed in the biomechanical assessment. It focused on working on the flexibility of the hamstrings to reduce back tension and decrease the limitation in the trunk lifting phase, and on providing a strengthening and postural awareness program centered primarily on dynamic lumbar stabilization in order to manage painful movements and gain muscle strength. In addition, low-impact aerobic conditioning was planned to ensure adequate nutrient and blood flow to the spinal structures damaged by degeneration.

CONCLUSIONS

After visualizing the parameters obtained through the NedLumbar/IBV application for the assessment of the lumbar spine, it is concluded that:

- The patient's functionality is altered in the movements analyzed, highlighting a deficit in the beginning of the execution of lifting loads, which reinforces the sensations of pain reported in the clinic.

- NedLumbar/IBV is a useful tool for clinicians in that it provides them with a simple and objective assessment of lumbar spine damage. In this case, the biomechanical assessment has helped to select a treatment that is more appropriate to the patient's discopathy.

- In addition, the biomechanical results served as a starting point for prescribing a personalized rehabilitation treatment focused on a program of flexibility, strengthening and proprioception exercises.

BIBLIOGRAPHY

(1) Lu X, Zhu Z, Pan J, Feng Z, Lv X, Battié MC, et al. Traumatic vertebra and endplate fractures promote adjacent disc degeneration: evidence from a clinical MR follow-up study. Skeletal Radiol. May 2022;51(5):1017-26.

(2) Curry WH, Pintar FA, Doan NB, Nguyen HS, Eckardt G, Baisden JL, et al. Lumbar spine endplate fractures: Biomechanical evaluation and clinical considerations through experimental induction of injury. J Orthop Res Off Publ Orthop Res Soc. June 2016;34(6):1084-91.

(3) Takegami N, Akeda K, Murata K, Yamada J, Sudo A. Association between non-traumatic vertebral fractures and adjacent discs degeneration: a cross-sectional study and literature review. BMC Musculoskelet Disord. 27 November 2020;21(1):781.

84) Wu J, Liu YY, Jin HJ, Wang Z, Liu MY, Liu P. Fate of the intervertebral disc and analysis of its risk factors following high-energy traumatic thoracic and lumbar fractures: MRI results of minimum five years after injury. Eur Spine J Off Publ Eur Spine Soc Eur Spinal Deform Soc Eur Sect Cerv Spine Res Soc. June 2022;31(6):1468-78.

AUTHOR'S AFFILIATION

Instituto de Biomecánica de Valencia
Universitat Politècnica de València
Edificio 9C. Camino de Vera s/n
(46022) Valencia. Spain