p. 1635 Histomorphic Analysis of the Development of the Pars Interarticularis and Its Association With Isthmic Spondylolysis
H. Claude Sagi, James G. Jarvis, and Hans K. Uhthoff

The pars interarticularis of the fetal lumbar spine was examined histologically to determine an etiology for spondylolysis. The ossification center for each half of the neural arch arises in the region of the pars in lower lumbar vertebrae. A stress riser appears to develop, predisposing to fatigue fracture in childhood.

p. 1641
Chronic Double-Level Cauda Equina Compression: An Experimental Study on the Dog Cauda Equina With Analyses of Nerve Conduction Velocity
Guang-Ping Mao, Shinichi Konno, Itaru Arai, Kjell Olmarker, and Shinichi Kikuchi

Nerve conduction velocity was studied in the dog cauda equina subjected to chronic double-level compression. Unlike the acute situation, chronic double-level compression does not induce more changes than single-level compression.

p. 1645
Collagen Crosslinks in Human Lumbar Intervertebral Disc Aging
Hemlata K. Pokharna and Frank M. Phillips

Forty-two postmortem lumbar intervertebral discs were harvested from nine individuals whose ages ranged from 24 to 89 years. The degree of disc degeneration was graded, and pyridinoline and pentosidine crosslink concentrations were determined. The data revealed an increase in pentosidine and a decrease in pyridinoline crosslinks of collagen to be a function of disc aging and degeneration. These changes may contribute to the age-related loss of disc integrity.

p. 1649
A Kinematic Study of the Cervical Spine Before and After Segmental Arthrodesis
David A. Fuller, John S. Kirkpatrick, Sanford E. Emery, R. Geoffrey Wilber, and Dwight T. Davy

The acute kinematic consequence of segmental arthrodesis in the cervical spine on the remaining open motion segments was studied. Fusions were simulated and tested in a cadaveric model. Sagittal plane rotation was not increased disproportionately at the motion segments immediately adjacent to a segmental arthrodesis.

p. 1668
Pain Drawings in the Assessment of Nerve Root Compression: A Comparative Study With Lumbar Spine Magnetic Resonance Imaging
James J. Rankine, Donal G. Fortune, Charles E. Hutchinson, David G. Hughes, and Chris J. Main

The ability of the pain drawing to predict the presence of nerve compression on magnetic resonance imaging has been assessed. Considerable overlap in the appearances of the pain drawing between patients with and without nerve compression was observed, and only 58% of patients with nerve compression were identified.

p. 1689
The Saskatchewan Health and Back Pain Survey: The Prevalence of Neck Pain and Related Disability in Saskatchewan Adults
Pierre Côté, J. David Cassidy, and Linda Carroll

The population-based survey in this study showed that neck pain is highly prevalent in Saskatchewan. However, most of this neck pain is trivial in nature. Although the 6-month period prevalence of neck pain is more than 50%, approximately 5% of Saskatchewan adults are significantly disabled by it.

p. 1708
Sweet's Syndrome Associated With Spinal Surgical Intervention: A Case Report
David A. Propst, Constance R. Bossons, and Chester E. Sutterlin, III

After undergoing a surgical procedure of the cervical spine, a patient developed multiple cutaneous lesions consistent with Sweet's Syndrome. All skin lesions healed uneventfully, and the patient benefited from a painless and solid cervical arthrodesis.

p. 1711
Surgical Management for Instability and Paraplegia Caused by Spinal Sarcoidosis: A Case Report
George P. Tzagarakis, Panayiotis J. Papagelopoulos, George S. Sapkas, and John K. Tsarouchas

A patient with destruction of L2 and L3 vertebrae resulting from sarcoidosis and with progressive paraplegia is reported. She underwent a two-stage anterior vertebrectomy and vertebral body replacement by a titanium cylinder, followed by posterior stabilization and fusion. After surgery, the patient experienced complete neurologic recovery.