Biomedical Engineering Reference
In-Depth Information
to occur as a result of repetitive trauma within the joint. However, more
recent studies suggest the possibility of a metabolic or genetic origin that
may cause alteration of bone architecture.
these types of injury may cause a shearing of the cartilage or a focal bone
and cartilage injury with a saucer-shaped defect. Whereas, in the case of
defects without a history of trauma where bone injury occurs, the vascularised
bone scaffold is lost through formation of a cystic lesion that gradually fails
to support the overlying cartilage thus leading to its collapse.
Spontaneous OCD is only partial and transient and relies on the invasion
of the defect by chondroprogenitor cells (Cancedda
et al
., 2003). thus far,
surgical approaches based on tissue engineering strategies have targeted the
regeneration of the cartilage while failing to address the underlying bone
failure. More importantly, the techniques of choice are autologous chondrocyte
implantation (aCi) and mosaicplasty where cells are not used in conjunction
with biomaterials.
a multi-centre trial at orthopedic clinics and university hospitals was
conducted from 1997 to 2000 on 47 patients who were randomly assigned to
aCi or mosaicplasty and subjected to arthroscopic debridement of the lesion
at the time of enrollment. they were called for surgery 6 months after the
initial debridement (Dozin
et al
., 2005).
aCi and mosaicplasty showed similar clinical performance. the high
percentage of spontaneous improvement observed after simple debridement
questions the need for reconstructive surgery in patients with lesions similar
to those included in this clinical trial.
14.7.3 Long bone diaphysis defects and their treatment
with bone tissue engineering constructs
Bone tissue engineering was used to treat four patients with large bone
diaphysis defects and poor therapeutic alternatives (Marcacci
et al
., 2007).
the study was assessed after 7 years follow up. Progenitor cells isolated
from the patients' bone marrow stroma were expanded in culture and seeded
onto porous HA scaffolds designed to match the bone deficit in terms of
size and shape. implantation of the bone tissue engineering construct was
supported by either an Ilizarov apparatus or a monoaxial external fixator
that was positioned on the patient's affected limb. Patients were evaluated
at different post-surgery time intervals by conventional radiographs and
computed tomography scans. in one patient, an angiographic evaluation
was also performed after 6.5 years. no major complications occurred in
the early or late post-operative periods and a complete fusion between the
implant and the host bone was observed from 5 to 7 months after surgery.
the latest follow-up (6 to 7 years post-surgery) showed good integration of
the implants and no late fractures in the implant area. it has to be observed
