Lumbar Spine, L-S junction and semg 2/26/08

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Myles Briggs
5 years ago
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1 Lumbar Spine, L-S junction and semg 2/26/08

2 EMG

3 What is EMG? EMG stands for electromyography. It is the study of muscle electrical signals. EMG is sometimes referred to as myoelectric activity. How is it measured? EMG is measured using similar techniques to that used for measuring EKG, EEG or other electrophysiological signals. Electrodes are placed on the skin overlying the muscle. Alternatively, wire or needle electrodes are used and these can be placed directly in the muscle.

4 What does the EMG signal actually indicate? When EMG is acquired from electrodes mounted directly on the skin, the signal is a composite of all the muscle fiber action potentials occurring in the muscle(s) underlying the skin. These action potentials occur at somewhat random intervals so at any one moment, the EMG signal may be either positive or negative voltage. Individual muscle fiber action potentials are sometimes acquired using wire or needle electrodes placed directly in the muscle.

5 What are some of the applications for which EMG might be used? There are many, many applications for the use of EMG. Can you name some?? clinically for the diagnosis of neurological and neuromuscular problems. diagnostically by gait laboratories and by clinicians trained in the use of biofeedback or ergonomic assessment. research laboratories, including those involved in biomechanics, motor control, neuromuscular physiology, movement disorders, postural control, physical therapy, and many others.

6 EMG Exam Video Exam

7 What are some applications for EMG could Sports Medicine???

8 Let s do some semg s

9 Lumbosacral juction Extension of the lumbar spine

10 Lumbosacral juction-extension of the lumbar spine Forces on the Lumbosacral juction-why is this important? The lumbosacral junction and the L4 L5 junction are the most common sites of disc lesions in the low back lumbosacral junction is susceptible to anterior slippage of L5 on S1, a phenomenon known as spondylolisthesis An understanding of the forces generated at this joint complex helps explain the pathomechanics associated with these disorders

11 What are we going to cover? Forces sustained at the Sacroiliac joints Forces on the sacroiliac joint are even less well studied than those on the lumbosacral junction. Because the joint appears to allow at least small movements, an appreciation of the forces exerted across the joint may improve the clinician s understanding of the pathomechanics of sacroiliac joint dysfunction

12 FORCES SUSTAINED AT THE LUMBOSACRAL JUNCTION (transitional zone) Lumbosacral junction is prone to injury, including disc lesions and spondylolisthesis. Loads on the joint contribute to pathology. Or, we can think of it as posture.

13 How much force does the L-S joint sustain? lbs lifting=22-33 lbs Compression load on the disc can range from lbs! Calculations of the joint moments and forces depend on the assumptions made in the model, including the size of the trunk and pelvis, the shape of the lumbar curve, and the muscles and ligaments included in the model as well as the movements of the spine that are studied.

16 First, let s figure out your load forces Take your body weight x 112% Take your body weight x 240% Take your body weight x.70%

17 Two-Dimensional Example of the Analysis of Forces on the Pelvis while walking Simplified model predicts muscle loads of 112% of body weight and compressive load of 240% and shear forces of 0.70% body weight. Magnitude of compressive and shear forces is affected by size of load being lifted and orientation of the pelvis. Let s go to the lab paper-page 2.

18 Loads at the Lumbosacral Junction Current studies provide general approximations of loads on joint LOADS IN THE LUMBOSACRAL REGION DURING BENDING AND LIFTING-Review again- Estimated compressive loads range from 270 to 1,236 lb, and peak anterior shear from 90 to 270 lb. Estimates depend on assumptions used in model. Understanding the effects of posture and lifting techniques on anterior shear forces will help clinicians to develop effective treatment and prevention strategies. First page of lab: Effects of Hip Muscles on the Pelvis

19 LOADS ON THE LUMBOSACRAL JOINT DURING WALKING Loads smaller in walking than in lifting Peak in double limb support when pelvis is maximally tilted anteriorly Lab: Last page of Lab

20 FORCES SUSTAINED AT THE SACROILIAC JOINTS Overview of the Analytical Model of the Sacroiliac Joint Analysis is complicated by the number of unknowns. Please calculate your body weight x 1.1=

21 Sacroiliac Joint Forces from the Literature Loads from 0.85 and 1.1 times body weight reported during static single-limb stance. Walking appears to generate larger loads at the sacroiliac joint.

23 MECHANICS OF PELVIC FRACTURES (think of loading and OA or Osteoporosis) Most pelvic fractures result from impact loading such as in motor vehicle accidents. Stress fractures can occur from repeated loading such as running or marching. Most common in narrowest part of pubic ramus

24 CLINICAL Importance: STRESS FRACTURES OF THE PELVIS Symptoms of pelvic stress fractures include groin pain, which is also a common symptom in individuals with chronic hip dysfunction. Practitioners may need to coinside the presence of pelvic stress fractures in small women, particularly Caucasian women, with complaints of groin pain and who exhibit no direct signs of hip dysfunction. A history of repeated loading, such as running, also is relevant

Lower Back Pain. Sensory motor function. 1 Principles of Exercise Therapy. Global muscles vs Local muscles. Research in Spine Rehabilitation

Lower Back Pain. Sensory motor function. 1 Principles of Exercise Therapy. Global muscles vs Local muscles. Research in Spine Rehabilitation 1 Principles of Exercise Therapy Lower Back Pain 1. Facet joint pain 2. Spondylolysis & Spondylisthesis 1. Exercise Therapy turns the patient into an active participant and not just a passive recipient