Correction of kyphotic deformity before and after transection of the anterior longitudinal ligament - a cadaver study

Abstract

With a custom-made measuring unit, two separate experiments, involving six and five cadaveric torsos with intact rib cages and sternums, respectively, were carried out to determine the effect of the transection of the anterior longitudinal ligament with and without osteodiscectomy and its influence on the thoracic kyphosis. The open or thoracoscopically assisted anterior release, as part of the operative treatment of scoliosis or kyphosis, usually consists of a transection of the anterior longitudinal ligament (ALL) and an additional discectomy. A complete osteodiscectomy, however, is not always possible with a minimally invasive approach. As part of our biomechanical research, we attempted to quantify the amount of correction achievable with a defined force prior to and following the isolated transection of the anterior longitudinal ligament. The aim of the study was to clarify whether or not an isolated transection of the anterior longitudinal ligament is sufficient to obtain an adequate anterior release of the spine. In the surgical treatment of kyphotic deformities, anterior release of the spine is performed in the form of a transection of the ALL and discectomy. Recently, video-assisted thoracic surgery has become increasingly popular in spine surgery. As part of this change in surgical technique, the question has arisen as to what extent an isolated transection of the ALL provides an adequate release of the thoracic spine. Eleven human spines were retrieved from fresh cadavers, dissected, and attached to a specially constructed apparatus. The spine was attached to the construct at the twelfth vertebral body. C6 and C7 were fixed in synthetic resin. We installed the instruments in such a manner as to reproducibly apply a torsional moment of 10 Nm to the spine. Motion was only permitted in the sagittal plane. Segmental transections of the ALL were carried out from T3 to T7. For comparison, the sagittal Cobb angle was also documented following an anterior release combined with an osteodiscectomy. With the isolated transection of the ALL, an average correction of the sagittal Cobb angle of 4 degrees in each functional spinal motion segment was recorded. In comparison, the additional osteodiscectomy led to a further average increase of only 2 degrees per level. The measurements performed on human cadavers showed that the isolated transection of the ALL leads to a sufficient anterior release of the thoracic spine, allowing a correction of the kyphotic deformity. The release with a concomitant osteodiscectomy represents a more time-consuming and more invasive procedure resulting in only a slightly greater amelioration of the sagittal Cobb angle, while being associated with a greater patient morbidity.

Age-related hyperkyphosis: update of its potential causes and clinical impacts—narrative review

“…A cadaver study reported that anterior longitudinal ligament transection at T3–T7 resulted in a Cobb angle reduction of 16° [44]. This association was strengthened in a cross-sectional study of 1172 older adults in the Health, Ageing and Body composition cohort.…”

Age-Related Hyperkyphosis: Its Causes, Consequences, and Management

“…Cadaver studies suggest that calcification and ossification of the anterior longitudinal ligament in the thoracic region might contribute to increased Cobb’s angle of kyphosis 4. Furthermore, shorter pectoral and hip flexor muscles are linked to severe hyperkyphosis, although it is not known whether the short muscles pull the shoulders and hips anteriorly, or whether the kyphotic posture results in shorter anterior musculature.…”

Back muscle strength and spinal mobility are predictors of quality of life in middle-aged and elderly males

“…However, many elderly people have abnormal posture, represented by hyperkyphosis, without pain or a history of such fractures. Recent studies demonstrates that many older adults who are mostly affected by hyperkyphosis do not have vertebral fractures [3], and other postulated causes of hyperkyphosis include postural changes [4], degenerative disc disease [5], muscular weakness [6,7], ligamentous degeneration [8], and genetic predisposition [9]. Such abnormal posture may be associated with multiple adverse health outcomes, including gait disorder, becoming bedridden.…”