Contribution of biomechanics, orthopaedics and rehabilitation: the past present and future.

Biomechanics is a field that has a very long history. From its beginnings in ancient Chinese and Greek literature, the field of orthopaedic biomechanics has grown in the areas of biomechanics of bone, articular cartilage, soft tissues, upper extremities, spine and so on. Bioengineers in collaboration with orthopaedic surgeons have applied biomechanical principles to study clinically relevant problems, improving patient treatment and outcome. In the past 30 years, my colleagues and I have focused our research on the biomechanics of musculoskeletal soft tissues, ligaments and tendons in particular. Therefore, in this review article, the function of the knee ligaments and the associated homeostatic responses secondary to immobilisation and exercise will be described. Research on healing of the medial collateral ligament (MCL) of the knee and possible future approaches in improving the healing of the knee ligaments will be presented. Finally, improvement of the understanding of ligament reconstruction, specifically of the anterior cruciate ligament (ACL), through the use of robotics technology will be included. Throughout the manuscript, specific scientific findings that have guided or changed the clinical management of injury to these soft tissues will be emphasised.

Injury and repair of ligaments and tendons.

In this chapter, biomechanical methods used to analyze healing and repair of ligaments and tendons are initially described such that the tensile properties of these soft tissues as well as their contribution to joint motion can be determined. The focus then turns to the important mechanical and biological factors that improve the healing process of ligaments. The biomechanics of surgical reconstruction of the anterior cruciate ligament and the key surgical parameters that affect the performance of the replacement grafts are subsequently reviewed. Finally, injury mechanisms and the biomechanical analysis of various treatment techniques for various types of tendon injuries are described.

Passive and active rehabilitation for partial lacerations of the canine flexor digitorum profundus tendon in zone II.

The purpose of this study was to compare the effect of unrestricted active versus passive mobilization on the gliding function and structural properties (ultimate load and stiffness) of repaired and nonrepaired canine flexor digitorum profundus tendons following partial laceration at 1 week. Using a radiographic method, normalized tendon gliding of the flexor digitorum profundus tendon adjacent to the metacarpal bone and total joint rotation were shown to be significantly greater in passive than in active tendons. Each group differed from their control group, however, by an average of only 5%. Both rehabilitation (active vs. passive) and treatment (repair vs. nonrepaired) of the partial tendon laceration significantly affected gap formation. Both active rehabilitation and repair of the laceration significantly increased gap formation compared with passive rehabilitation and nonrepair of the partial laceration. Rehabilitation did not significantly affect the normalized ultimate loads and stiffness in the passive and active groups but the nonrepair groups displayed significantly higher ultimate loads and stiffness than the repair groups.

Effects of tenorraphy on the gliding function and tensile properties of partially lacerated canine digital flexor tendons.

Management of a partially lacerated digital flexor tendon within zone II remains controversial. To address this issue, we undertook an evaluation of the impact of tenorrhaphy on the gliding function and tensile properties of canine flexor tendons with lacerations involving either 30% or 70% of their cross-sectional area. Assessment of tendon excursion and joint rotation after 6 weeks of postoperative controlled passive mobilization failed to reveal any statistically significant benefit from tenorrhaphy on the gliding function. In fact, we demonstrated a significant negative effect of repair on tendons with 30% lacerations. Moreover, no significant differences between the structural properties or integrity of the repaired and nonrepaired tendons could be demonstrated. Thus, in light of the inherent tensile properties in these partially lacerated tendons, our data suggest that digital function of partially lacerated tendons of up to 70% of the cross-sectional area may be preserved without primary repair. However, additional work is needed to more definitively address this issue in a clinical context.