Chiropractic adjustment has been shown to gap certain joints in the spine, thereby improving mobility in individuals with decreased movement capabilities. During normal motion, joints in the spine produce sounds and vibrations called crepitus. The purpose of this study is to assess how this crepitus may be used as an indicator for joint degeneration in healthy human subjects and those with low back pain, and if chiropractic adjusting causes change in this crepitus. The investigators hypothesize that change in crepitus after adjustment may be a useful indication of changes in joint mobility and joint stiffness.

Objective: This is an expansion of the initial study "Analysis of Crepitus in Human Subjects" to assess the feasibility of simultaneously recording zygapophyseal (Z) joint crepitus using piezoelectric accelerometers and Z joint motion using diagnostic ultrasound (US), and qualitatively assess the US images with particular focus on images taken of Z joints exhibiting crepitus. Like the original study (n=12), the results of a recently developed automated method (AM) is compared with two human observers in the analysis of recordings of human lumbar zygapophyseal (Z) joint crepitus. The recordings will be taken during ranges of motion performed before and after lumbar side-posture spinal manipulation (SMT). Methods: Six (6) healthy and 6 low back pain subjects will participate in the study. Using clinical study procedures developed previously, subjects will be given an initial phone screen before being scheduled for a clinical study appointment. At the appointment, subjects will undergo the informed consent process, and those consenting will be further screened and examined by the Research Clinician who will use the inclusion/exclusion criteria to determine eligibility for the study. Eligible subjects will be enrolled and scheduled for an accelerometry visit. At the accelerometry visit, 11 accelerometers will be applied to the lumbar region, allowing assessment of Z joint crepitus. US imaging of the right L4/L5 Z joint will be included. Each subject will undergo full flexion and full extension (ROM) while recordings are made from the accelerometers. Subjects will then undergo bilateral lumbar SMT, and immediately thereafter will undergo repeated ROM while recordings are made. Two human observers and the AM, blinded to the results of one another, will then assess the recordings to identify Z joints from which crepitus originated. The primary outcomes will be: 1) weighted kappa inter-rater reliability statistic comparing AM and the 2 human observers in identifying Z joint crepitus, and 2) ANOVA test statistic comparing time to complete the crepitus analysis by the AM and human observers. Hypotheses: 1) The automated method will be reliable, agreeing with the human observers' analysis. 2) The automated method will be significantly more time efficient than the analyses made by the human observers. Application: The investigators believe that this program will improve the efficiency of identifying the site of Z joint crepitus, thereby advancing the line of investigation designed to use crepitus as a biomarker of spinal joint dysfunction.

Inclusion Criteria:

Healthy (no LBP) Subjects (n=6):

• 30 to 75 years of age
• No previous history of LBP lasting for more than two weeks, or no more than three episodes of back pain of brief duration (one week) in any given year (to recruit healthy subjects with no history, or a minimal history, of LBP).
• No presence of current LBP
• Female with a BMI of 28 or less; Male with a BMI of 30 or less.

LBP Subjects Criteria (n=6):

• 30 to 75 years of age
• Current LBP of at least one-week (7 days) duration
• Female with a BMI of 28 or less; Male with a BMI of 30 or less.

Exclusion Criteria:

Healthy Subjects:

• Under 30 or over 75 years of age
• History of an episode of LBP lasting for more than two weeks, or more than three episodes of back pain of brief duration (one week) in any given year (see reasons for no LBP in Inclusion Criteria)
• Presence of Current LBP
• Prior spinal surgery
• Presence of current spinal fracture, tumor, infection, or scoliosis of greater than 5 degrees (Cobb's angle, scoliosis decreases ability to place the accelerometers); or other known significant pathology
• Known allergies to latex or adhesives (including Band-Aids) applied to the skin (accelerometers are taped to the skin)
• BMI over 30 for males; BMI over 28 for females (subject will be weighed at exam)
• Pregnancy (because of unique biomechanical patterns and changes in the ranges of motion that occur during pregnancy)
• Positive findings on any of the orthopedic or neurological tests listed on exam form; (because these subjects will be assessed as healthy individuals, indication of somatic pathology or neurological deficit are exclusionary criteria)
• Decreased range of motion (as measured with a goniometer) of the lumbar region (recording during flexion and extension ranges of motion are conducted in the study; consequently a full range of motion is necessary for the healthy subjects). The following ranges will be exclusionary: Flexion: < 40º (normal = 60º); Extension: < 10º (normal = 20º);
• Pain or discomfort during set-up for lumbar side-posture spinal manipulation (SMT) or during lumbar SMT given at the conclusion of the examination (the study assesses changes following SMT, consequently ability to tolerate SMT is important)
• Contraindication to manipulative treatment

LBP Subjects:

• Under 30 or over 75 years of age
• Absence of Current LBP of at least one-week (7 days) duration
• BMI over 30 for males; BMI over 28 for females (subject will be weighed at exam)
• Known allergies to latex or adhesives (including Band Aids) applied to the skin (accelerometers are taped to the skin)
• Pregnancy (because of unique biomechanical patterns and changes in the ranges of motion that occur during pregnancy)
• Pain radiating below the knee
• Presence of current spinal fracture, tumor, infection, or scoliosis of greater than 5 degrees (Cobb's angle, scoliosis decreases ability to place the accelerometers); or other known significant pathology
• Prior spinal surgery
• Negative findings on all of the orthopedic or neurological tests listed on exam form
• Contraindication to manipulative treatment

Participants will be recruited from the faculty, student and staff population at National University Of Health Sciences, Lombard, IL. If unable to recruit sufficient number of participants, recruitment will be extended to the general population of the Chicago, IL metro area.