The Effect of Knee Height Asymmetry on Gait Biomechanics.

BACKGROUND: Though the primary goal for limb length discrepancy (LLD) management is to equalize the leg lengths, symmetry between corresponding long bones is usually not achieved, leading to knee height asymmetry (KHA). To date, there is minimal information on what effect KHA has on gait biomechanics and joint loading. Thus, the purpose of this study is to determine the impact of KHA on gait biomechanics. METHODS: Seventeen subjects with KHA after limb equalizing surgery and 10 healthy controls were enrolled. Subjects participated in 3D gait analysis collected using self-selected speed. Lower extremity kinematics, kinetics, work generated/absorbed, and total work were calculated. Standing lower limb x-rays and scanograms were used to measure LLD and calculate the tibia-to-femur (TF) ratio for each limb. Two sample t tests were used to compare differences in standing LLD, TF ratio, and work between groups. Bivariate correlation using Pearson correlation coefficients was conducted between TF ratio and total mechanical work, as well as between knee height asymmetry indices and total work asymmetry (α=0.05). RESULTS: Among participants, there were no differences between LLD; however, there were differences between TF ratio and knee height asymmetry. We found a nonsignificant relationship between TF ratio and total mechanical work for individual lower extremities. Therefore, the length of individual bones (TF ratio) relative to each other within the individual lower extremity was not associated with the amount of work produced. However, when a difference exists between sides (asymmetry, ie, TF ratio asymmetry), there were associated differences in work (work asymmetry) produced between sides (r=0.54, P =0.003). In other words, greater knee height asymmetry between limbs resulted in more asymmetrical mechanical work during walking. CONCLUSIONS: These findings may have implications for the management of LLD. Asymmetrical total mechanical work could lead to atypical joint loading during gait. Surgeons may want to consider prioritizing achieving knee height symmetry as a postoperative goal when correcting limb length discrepancy. LEVEL OF EVIDENCE: Level III, Case Control Study.

Fingertip Injuries and Amputations: A Review of the Literature.

The fingertip is defined as the part of the digit distal to the insertion of the extensor and flexor tendons on the distal phalanx. Devastating injuries to the hand occur every year that lead fingertip amputations in thousands of people. The highest incidence rates are usually seen in children less than five years old and in adults over the age of 65. There are various presentations of injury that may end up with post-traumatic fingertip amputation, including lacerations, avulsions, and crush injuries. The fingertip is vital for sensation, as it has a high concentration of sensory receptors, and hence the restoration of sensation is the most important focus of treatment. The three main goals of treatment are the restoration of sensation and durability in the tip and assuring proper bone support to allow for nail growth. Many complications can arise after fingertip amputation, including delayed wound healing, nail deformities with poor aesthetics, hypersensitivity, residual pain, cold intolerance, scar retraction, flexion contractures, chronic ulceration, infection, and flap loss. The objective of this study is to provide an overview of the anatomy of the fingertip, the presentation of fingertip injuries and their management, and complications that might arise after surgery.