Controversies have surrounded the sacroiliac joint. The sacroiliac joint (SIJ) is a considerably complex and strong joint with limited mobility, mechanically serving as a force transducer and a shock absorber. Anatomical changes are seen in the SIJ throughout an individual's lifetime. The ligamentous system associated with the SIJ serves to enhance stability and offer proprioceptive feedback in context with the rich plexus of articular receptors. Stability in the SIJ is related to form and force closure. Movement in the SIJ is 3-D about an axis outside of the joint. The functional examination of the SIJ is related to a clinical triad.

Different anatomical structures and pathophysiological functions can be responsible for lumbar pain, each producing a distinctive clinical profile. Pain can arise from the intervertebral disc, either acutely as a primary disc related disorder, or as result of the degradation associated with chronic internal disc disruption. In either case, greatest pain provocation will be associated with movements and functions in the sagittal plane. Lumbar pain can also arise from afflictions within the zygapophyseal joint mechanism, as result of synovitis or chondropathy. Either of these conditions will produce the greatest pain provocation during three-dimensional movements, due to maximal stress to either the synovium or joint cartilage. Finally, patients can experience different symptoms associated with irritation to the dural sleeve, dorsal root ganglion, or chemically irritated lumbar nerve root. Differential diagnosis of these conditions requires a thorough examination and provides information that can assist the clinician in selecting appropriate management strategies.

Pain originating from spinal nerve roots demonstrates multiple pathogeneses. Distinctions in the pathoanatomy, biomechanics, and pathophysiology of spinal nerve roots contribute to pathology, diagnosis, and management of root-related pain. Root-related pain can emerge from the tension events in the dura mater and nerve tissue associated with primary disc related disorders. Conversely, secondary disc-related degeneration can produce compression on the nerve roots. This compression can result in chemical and mechanical consequences imposed on the nervous tissue within the spinal canal, lateral recess, intervertebral foramina, and extraforminal regions. Differences in root-related pathology can be observed between lumbar, thoracic, and cervical spinal levels, meriting the implementation of different diagnostic tools and management strategies.

Work-related musculoskeletal disorders (MSDs) have reached a costly epidemic proportion in recent years, producing ergonomic pain as their most frequent clinical consequence. While work-related MSDs have declined in incidence, their prevalence continues. Individuals develop symptoms as a consequence of numerous factors that include force, sustained posture, repetitive motion, and vibration. Different combinations of these factors lend to different pathomechanical and pathophysiological consequences that appear to be unique to different regions of the body and related to distinctive work environmental and task characteristics. Federal and state agencies have made considerable attempts to regulate the work environment in a preventative fashion in order to reduce the incidence of ergonomic pain and other sequelae of work-related MSDs.

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