Biomedical Engineering Reference
In-Depth Information
not yet progressed to OA) can be four times as much as treatment of the defect itself [
216
], and a
similar scenario can be expected for OA.
2.5 MOTIVATION FORTISSUE ENGINEERING
Based on over 25,000 arthroscopies surveyed, it has been shown that osteochondral and chondral
lesions are the most common, accounting for 67% of the observations, while OA accounts for
29% [
165
]. As presented earlier, the cartilage's inability to mount a sufficient healing response
eventually results in degenerative changes, and the proportion of lesions to OA observed is expected
to change in the near future due to the baby boomers, with concomitant rises in management and
treatment costs. Aside from OA being linked to the aging population, it is more important to note
that these lesions frequently occur in the youth, a population whose needs for long-term solutions
are much greater than their elders.
A need for tissue engineering rises from the prevalence of joint injuries in adolescents. “Little
Leaguer's Elbow,” osteochondrosis, and osteochondritis dissecans are joint diseases that occur mainly
in children, due to the increased vulnerability to stress in the growing skeleton. One out of three
school-age children will sustain an injury severe enough to require medical treatment. Emergency
room visits are the highest among children and young adults. ACL treatments, as well, are seen in
higher frequencies (and are rising) in these two groups [
274
,
275
]. With the estimated 30 million
children who participate in organized sports activities, the yearly costs for injuries within this group
have been projected to be $1.8 billion [
276
]. Kids may play on multiple teams with overlapping
schedules, and it is not uncommon to see the absence of well-defined standards for when training
becomes excessive. Little League began to implement a pilot pitch-count program only in 2005 [
277
],
though its initially set standards were quickly relaxed. While elbow and shoulder injuries are common
in baseball, a global survey of adolescent knee injuries put the incidence rate at greater than 25% in
sports participants [
278
], particularly in basketball [
279
,
280
]. In terms of articular cartilage defects,
young patients with knee injuries show 75% superficial (grade I-II) and 25% deep lesions (grade III-
IV) [
229
]. This is particularly alarming as data from 1995, 1996, and 1997 indicate that roughly
20% of the knee injuries in adolescents required surgery [
281
-
283
]. The urge to succeed that comes
from the child, parents, and coaches has gone to such a degree that overuse injuries are common. It is
difficult for some parents to realize that their children's hard work in sports can result in catastrophic
cartilage injuries. Unfortunately, no consistently successful solutions exist for the cartilage repair
problem in children and adolescents.
The formation of repair fibrocartilage serves only as a temporary biomechanical fix, and a
long-term solution for youth afflicted with joint injuries would be ideal. Even in cases where the
articular cartilage is not damaged in the primary traumatic event (e.g., osteophytes and ligament
damage), the malalignment that can result [
284
] has been shown to predict cartilage loss [
285
]. A
survey of global adolescent knee injuries shows that females are more prone to these injuries than
males. Recent estimates put the rate of incidences at greater than 25% in sports participants [
278
].
Basketball has been linked to the highest rates of knee injury, as the frequent jumping associated
