This thought-provoking book is the product of a meeting on lumbar segmental instability, a subject of great controversy, that was held in Brussels, Belgium. The organizers of the meeting assembled an international group of specialists that included neurosurgeons and orthopaedic surgeons as well as radiologists, anatomists, biostatisticians, engineers, and others who study the basic science of the spine.
One of the authors, Eisenstein, explains the reason for the controversy: "The problem with spinal instability is not the concept but the fact that the concept means so many different things to different people." He discusses the problems of jargon and misinterpretation and points out that the definitions of key words are not always universally understood or accepted.
The section on basic science includes chapters on the biomechanics of the spine, the clinical relevance of the biomechanics of lumbar spinal instability, biomechanical measurements, and the semantics of lumbar instability. The text is fairly well written and provides basic information on the current state of knowledge.
In the section on clinical presentation and pathophysiology, Mulholland highlights the fact that there are several meanings of the word instability and notes that the term can be used in relation to the hip, knee, and other joints with detectable movements that demonstrate clinical instability. In the spine, however, such abnormal movements, if present at all, are difficult to detect. As Mulholland points out, the unstable spine must be defined in terms of the pain pattern, dysfunction, and anatomical findings, and the treatment must address the relevant pathophysiology. He identifies the problem that arises when the term instability is applied to all patients who have disabling back pain and then is used as a justification for operative intervention. He also raises a concern about the plethora of spinal instrumentation that is available and states that it is imperative to carefully match the intervention with the pathological entity.
Balagué, in a chapter on the natural history of lumbar instability, points out that the unstable spine is well understood in relation to acute spinal trauma, infections, tumors, and even spondylolisthesis but is poorly understood in relation to degenerative disorders. The chapter on spinal instability secondary to metastatic cancer, by Galasko, is well written and informative. Porter describes the relationship between central spinal stenosis and instability, and van Akkerveeken raises the question of whether lateral stenosis is a feature of lumber segmental instability. In the last chapter in this section, Crock addresses the possibility that spinal instability can be an iatrogenic condition and offers suggestions for treatment.
The short section on the use of radiographs and magnetic resonance imaging for the diagnosis of instability does not address the problem of how to ascertain that instability is, in fact, present.
The section on nonoperative treatment provides generic information about the use of manipulation and orthoses but does not include a discussion of their specific role in relation to instability. There is a long section on operative treatment in which various authors describe the different types of instrumentation that are available; however, the results obtained with these systems are not analyzed in relation to instability.
The section on economic considerations is particularly pertinent in this era of rising health-care costs. Mélot provides an excellent overview of the principles of cost-benefit analysis and recommends that the appropriate method of analysis should be determined according to the context in which clinical decisions need to be made. The problem with applying this concept to health care, he believes, is partly due to the reluctance of practitioners to assign a monetary value to patients' health outcomes. The costs and ethics of operative intervention for lumbar instability are discussed by Greenough. The author points out that, before cost-effectiveness or cost benefit can be analyzed, the quality of the information must be markedly improved. Specifically, investigators must use a recognized measure, both preoperatively and postoperatively, to evaluate outcomes; the follow-up period must be at least two years; and the data must be compared with those for controls. Otherwise, the analysis and conclusions lack validity. The author asks, "Is it ethical for spine surgeons to stabilize the spine without measurement of their results?"—a question that is very relevant in health care.
Waddell et al., in a chapter that resembles a meta-analysis, conclude that there is no scientific evidence to support the assertion that operative intervention is effective for the treatment of lumbar spondylosis.
The chapter by Mulholland entitled "Is It Ethical to Operate on a Controversial Pathology?" is excellent and will stimulate the reader to use caution when managing a patient who has back pain. The concepts discussed by Nachemson in the chapter entitled "Scientific Diagnosis or Unproved Label for Back Pain Patients?" are relevant. Nachemson is critical of the care provided in this era of rising costs and states that, in a shrinking health-care economy, only treatments that can be demonstrated to be effective should be used. The author asserts that treatment should not be based on conjecture or unproved hypotheses.
I encourage physicians who manage patients who have back pain to read this book.
Leela Rangaswamy, M.D.
Deputy Editor
The Journal of Bone and Joint Surgery
Needham, Massachusetts