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R D Coutts

Publications and source records attributed to R D Coutts.

At least 37 records · Page 2Linked to original sources
PubMed1997

A methodology for the quantitative assessment of articular cartilage histomorphometry.

OBJECTIVE: Traditionally, histological analysis of cartilage and cartilage repair has been performed qualitatively. While new techniques and grading systems have attempted to improve the quantitative nature of histological assessment, the advent of computer-based analysis systems have enabled development of more quantitative methodologies for cartilage repair. The objective of this study was to develop such a methodology for a more quantitative assessment of cartilage repair using a color-based image analysis system. DESIGN: Repair parameters were defined to describe the degree of cartilage restoration: repair dimensions, degree of attachment, surface roughness and repair location. This technique was experimentally applied to a cartilage repair study using cultured perichondrial cells implanted in a polylactic acid matrix in the rabbit femoral condyle. Specimens were examined and compared with the contralateral normal knee. RESULTS: Results showed increases in cartilage height, repair area, and surface roughness over controls for both 6 and 12 weeks. Surface elevation was significantly decreased at 6 weeks over 12 weeks. The percentage of repair improved between 6 and 12 weeks. Results were compared with a traditional grading system and demonstrated close correlation. Intraobserver and interobserver precision analysis were performed and demonstrated the reproducibility of the quantitative results by and between individuals. CONCLUSIONS: The methodology was deemed successful for a more objective analysis of cartilage with the added advantage of providing measured parameters that can assist in making comparisons between different studies using the same methodology.

Animals↗
PubMed1997

Quantitation and localization of cartilage degeneration following the induction of osteoarthritis in the rabbit knee.

OBJECTIVE: To develop and apply a new video imaging technique to quantify and localize Indian ink staining of cartilage of the rabbit femorotibial joint after the induction of osteoarthritis by unilateral transection of the anterior cruciate ligament (ACLT). METHODS: Nine weeks after surgery, femora and tibiae from 11 ACLT and contralateral control knees were harvested and positioned to obtain calibrated gray-scale images of the ink-painted articular cartilage surfaces that are opposed with the knee in 90 degrees flexion. Images were processed so that areas of normal cartilage gave a relatively high reflectance score, whereas ink-stained fibrillated cartilage and exposed bone gave low scores. RESULTS: Comparison of the medial and lateral femoral condyles and tibial plateaus (MFC, LFC, MTP, LTP) of control and ACLT knees showed that the area of the MTP not covered by the meniscus had a significantly lower reflectance score (P < 0.001) than other areas. ACLT led to an 11% decrease (P < 0.001) in the overall reflectance score. The reflectance score decreased as a traditional morphological grading of degeneration increased. ACLT-induced degeneration had a predilection for the posteromedial aspects of the joint, and to a lesser extent, the anterolateral aspects. In the tibial plateaus, ACLT caused significant degeneration in the covered, but not the uncovered, areas. Image scores of opposing cartilage surfaces (i.e., MFC vs MTP and LFC vs LTP) were significantly (R = 0.56-0.70, P < 0.001) correlated in ACLT and control knees. DISCUSSION: Identification and characterization of cartilage areas prone to degeneration may be particularly useful for further analysis of biochemical and biomechanical mechanisms in osteoarthritis, as well as the efficacy of therapeutic interventions.

Animals↗
PubMed1997

Osteochondral repair using perichondrial cells. A 1-year study in rabbits.

Articular cartilage repair remains a clinical and scientific challenge with increasing interest focused on the transplantation of chondrogenic cells. This study evaluated the repair response during a 1-year period after implantation of allogenic perichondrium cell polylactic acid composite grafts into 3.7 x 5 mm osteochondral defects drilled into the medial femoral condyles of 82 adult New Zealand White rabbits. The repair tissue was evaluated grossly, histologically, histomorphometrically, biochemically, and biomechanically at 6 weeks, 12 weeks, 6 months, and 1 year after implantation. After gross evaluation, cartilaginous material appeared to fill the defect in 70 experimental knees, for an overall repair frequency of 85%. The histomorphometric results and the histologic appearances were variable. None of the specimens were completely normal at 1 year. Only specimens with subchondral bone reformation displayed a definable cartilage appearing surface with chondrocytes surrounded by dense matrix. Subchondral bone reformation was inconsistent, reaching 50% at 1 year. Biochemically, the repair tissue matured during a 1-year period into a hyaline Type II collagen dominant tissue, whereas glycosaminoglycan content remained low at all time periods. The measured compressive properties of the repair tissue at 1 year were not significantly different from those of the contralateral knee that was not surgically treated. The treatment of osteochondral defects in the rabbit knee with allogenic perichondrium cell polylactic acid composite grafts yielded a high percentage of grossly successful repairs that showed inconsistent subchondral bone reformation. These results suggest that healthy subchondral bone is important to articular cartilage repair. They also highlight that a cartilaginous appearing tissue at gross inspection may not represent structurally normal articular cartilage. Continued multidisciplinary studies on the arthroplastic potential of rib perichondrial cells are needed before human studies, which rarely can extend beyond gross assessment of repair tissue appearance can be undertaken.

Animals↗
PubMed1996

Characterization of a model of osteoarthritis in the rabbit knee.

A new computerized method of histomorphometry was used to assess the development of osteoarthritis (OA) in a rabbit model. Three groups of 10 New Zealand White rabbits with closed epiphyses underwent unilateral anterior cruciate ligament transection (ACLT) and contralateral arthrotomy (sham). Groups were killed at 4, 8 and 12 weeks. At the time of death the femoral condyles were assessed grossly following the application of India ink using the following grading scale. Grade 1: intact surface; grade 2: minimal fibrillation; grade 3: overt fibrillation; grade 4: erosion. All histological sections were assessed using a color image analysis system. The mean thickness and area were measured for a defined cartilage region. The root mean square surface roughness (based on deviations from an idealized smooth surface) was calculated to assess the surface profile of the articular cartilage. The results were as follows. After ACLT, no full-thickness ulceration was noted at 4 weeks. Four of the medial femoral condyles at 8 weeks and six at 12 weeks showed full-thickness ulceration of the articular cartilage. The per cent cartilage area and cartilage thickness (ACLT divided by sham) in almost all regions showed decreases with time, indicating progressive erosion. The surface of the ACLT knees was much rougher than that of sham of the knees. These results demonstrate the usefulness of a quantitative methodology using a computerized video analysis system to assess the articular cartilage following ACLT in a rabbit model for the development of OA.

Animals↗
PubMed1995

Articular cartilage repair using allogeneic perichondrocyte-seeded biodegradable porous polylactic acid (PLA): a tissue-engineering study.

Efforts to expand treatment options for articular cartilage repair have increasingly focused on the implantation of cell-polymer constructs. The purpose of this study is to determine the suitability of porous D,D-L,L-polylactic acid as a carrier for delivering repair cells obtained from rib perichondrium into full-thickness articular cartilage defects. In vitro characterization of perichondrocyte-polylactic acid composite grafts was combined with in vivo assessment of the early articular cartilage repair in a clinically relevant model. Using a fluorescent double-stain protocol to visualize live and dead cells in situ, primary cells cultured from perichondrium were found to be capable of attaching to and surviving within a porous D,D-L,L-polylactic acid matrix. These perichondrocyte-polylactic acid composite grafts were then implanted within osteochondral defects drilled into the left medial femoral condyles of 16 adult New Zealand white rabbits. Experimental animals were sacrificed 6 weeks after implantation and the repair tissue was evaluated grossly, histologically, and biochemically. Grossly, 96% (15/16) of the experimental animals demonstrated repairs consisting of a smooth, firm neocartilage which appeared similar in color and texture to the surrounding articular surface. Matrix staining for cartilaginous protein was seen surrounding chondrocyte-like cells in the cartilage regions of the repair. Cellular alignment was found to be related to scaffold architecture. These results suggest that scaffolds composed of porous D,D-L,L-polylactic acid support the growth of cartilaginous repair tissue and are compatible with both in vitro and in vivo survival of chondrogenic cells.

Absorption↗
PubMed1995

Gait parameters following stroke: a practical assessment.

Mechanical methods of quantifying gait are more sensitive to change than is direct clinical inspection. To assess gait parameters and patterns of patients with stroke, and the temporal changes of these parameters, a foot-switch gait analyzer was used to test 49 ambulatory patients with stroke and 24 controls. Patients walked significantly slower than controls, with decreased cadence, increased gait cycle, and increased time in double limb support. Patients' hemiplegic limbs spent more time in swing and stance when compared to controls; their unaffected limbs spent significantly more time in stance and single limb support compared to controls. Patients' hemiplegic side, when compared with the unaffected side, spent less time in stance and more time in swing. A flatfoot pattern was typically noted on the affected side. General gait parameters improved over time, with the largest changes occurring in the first 12 months. However, the percentage of time spent in double and single limb support, stance and swing, parameters which describe the asymmetrical pattern of gait, did not change over time. Abnormal gait was due to difficulty in moving the body over an unstable limb. Gait analysis can be of importance in documenting abnormalities and determining the effects of therapeutic modalities.

Adult↗
PubMed1992

Rib perichondrial autografts in full-thickness articular cartilage defects in rabbits.

This study investigated the resurfacing of full-thickness articular defects in the adult rabbit medial femoral condyle using a rib perichondrial graft. The graft was secured to a 4-mm-diameter bone core removed from the femoral condyle. Two postoperative treatment protocols were studied: one group had ad libitum cage activity (CAGE; n = 95) and the other group received two weeks of passive motion (PM; n = 73; eight hours per day, five days per week) followed by cage activity. Animals in both groups were killed at six, 12, 26, and 52 weeks. Repair tissue resembling hyaline cartilage formed in a majority of animals at all time periods and in both postoperative treatment groups. The overall success rates in which repair tissue formed were 58% in the CAGE group and 56% in the PM group. However, over time, a maturation of the neocartilage into nearly normal hyaline articular cartilage was noted with the percentage of Type II collagen increasing from 55% at six weeks to 82% at one year. The complex shear modulus of the repair tissue for both groups became similar to normal cartilage with increased healing time. There was no statistical difference in shear moduli between the two treatment modalities. These results show that cartilage repair tissue derived from rib perichondrium could mature into hyaline articular cartilage over time and would not degrade by one year after repair.

Animals↗
PubMed1991

The use of polylactic acid matrix and periosteal grafts for the reconstruction of rabbit knee articular defects.

In order to find a material that would improve cartilage repair, we investigated the use of porous polylactic acid matrix (PLA) with and without periosteal grafts in large articular defects in the medial femoral condyles of 18 New Zealand white rabbit knees. The right knee defect was filled with PLA, the left defect was filled with PLA and a periosteal graft. All animals were killed at 12 weeks. PLA allowed for the de novo growth of neocartilage at the articular surface in all specimens and appeared to serve as a scaffolding for cell migration and matrix formation. Histologically, small amounts of PLA remained under the neocartilage with the majority being replaced by bone. PLA was a suitable carrier for periosteal grafts with a high graft survival rate (89%) and proliferation of a neocartilage which was thicker and more closely resembled articular cartilage than PLA alone knees. Biochemically, there was more type II collagen in the grafted knees (83%) than in the PLA alone knees (65%). Biomechanical tests of the neocartilage included equilibrium displacement, aggregate modulus, and apparent permeability. These tests were not statistically different between PLA alone and grafted knees. Comparison to normal cartilage indicated that the neocartilage was less stiff but had similar permeability. A consistent repair of the articular defects was achieved with and without periosteal grafts resulting in a tissue that closely resembled hyaline articular cartilage.

Animals↗
PubMed1991

The influence of functional electrical stimulation on the properties of vastus lateralis fibres following total knee arthroplasty.

The influence of functional electrical muscle stimulation (FES) on selected properties of vastus lateralis muscle fibres was studied in patients recovering from total knee arthroplasty for osteoarthritis. Prior to surgery, on the average, muscle biopsies from the vastus lateralis could be characterized as having a predominance of Type I fibres which were significantly larger in cross-sectional area than the Type II fibres in the same sample. Following surgery, muscle biopsies from a group of patients (n = 7) which received continuous passive motion and no FES, exhibited a marked increase in the proportion of Type II fibres along with a general atrophy of both the Type I and Type II fibres. Patients receiving passive motion and FES (n = 9) also showed an increase in the relative percentage of Type II fibres. Post-operatively, however, there was no significant reduction in fibre area in the stimulated muscles. These data suggest that FES was effective in attenuating the muscle atrophy associated with total knee arthroplasty but had no influence on those metabolic properties which were related to muscle fibre type classification criteria.

Aged↗
PubMed1991

The changes in intramuscular pressure and femoral vein flow with continuous passive motion, pneumatic compressive stockings, and leg manipulations.

Intramuscular pressure was measured continuously in the deep compartment of the calf and anterior thigh of volunteers while their legs were cyclically moved from 0 degrees to 90 degrees back to 0 degrees (angle of knee flexion) in an anatomic continuous passive motion (CPM) device and a nonanatomic CPM device. Femoral venous flow was measured continuously using a thermodilution technique in volunteers while their legs were moved in both CPM devices, during inflation of a pneumatic stocking, and during several leg manipulations. Baseline intramuscular pressures in the deep calf and anterior thigh were 10.0 +/- 1.9 mmHg and 4.9 +/- 1.9 mmHg, respectively (mean +/- standard error). Both the anatomic and nonanatomic CPM devices produced a statistically significant maximal increase in pressure in the calf. By contrast, only a decrease in pressure occurred in the thigh with both devices. Baseline femoral vein flow measured by the thermodilution technique was 311 +/- 38 ml per minute. Significant increases in femoral vein flow were seen with both CPM devices. The maximal flow produced by the anatomic CPM was 1199 ml per minute and was approximately four times higher than baseline flow and approximately 1.4 times the maximal flow change seen with the nonanatomic CPM (836 ml per minute). The greatest net increase in flow was observed between 60 degrees and 90 degrees of knee flexion with both devices. Overall, passive straight-leg elevation produced the largest flow (1524 ml per minute), followed by the anatomic CPM and nonanatomic CPM, and then by active ankle dorsiflexion(640 ml per minute), pneumatic stocking inflation (586 ml per minute), manual calf compression (532 ml per minute), and passive dorsiflexion (385 ml per minute)(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Cartilage resurfacing of the rabbit knee. The use of an allogeneic demineralized bone matrix-autogeneic perichondrium composite implant.

A full-thickness articular-cartilage defect was created in the medial femoral condyles of 32 adult rabbits. The defects were filled with demineralized bone or a composite of demineralized bone and perichondrium. Results of cartilage repair were assessed after 12 weeks of implantation. We conclude that demineralized bone matrix used as a subchondral matrix in a cartilage repair model 1) stimulates and induces subchondral bone ingrowth, 2) provides a surface on which cartilage repair can proceed, and 3) can be utilized as a platform on which perichondrium can be fixed to provide a cellular source for cartilage repair. Repair tissue that developed from perichondrium was thicker, more closely resembled normal articular cartilage, and was of a less fibrous nature than the repair tissue that developed de novo on the demineralized bone matrix.

Animals↗
PubMed1989

Morphological and biomechanical evaluations of neocartilage from the repair of full-thickness articular cartilage defects using rib perichondrium autografts: a long-term study.

Neocartilage regenerated from rib perichondrium autografts implanted into full thickness cartilage defects made in the femoral condyle of rabbit knees were evaluated for periods up to 1 yr. Two postoperative treatment effects were studied, one with ad lib. caged activity (CAGE) and the other with the operated knee placed on a continuous passive motion machine for 2 weeks (8 h day-1 for 5 days week-1) followed by caged activity (PM). Animals were sacrificed at 6, 12, 26 and 52 weeks after surgery. The neocartilage was evaluated histologically and biomechanically and compared with the contralateral unoperated side. Visually, the neocartilage appeared to have an appearance similar to that of surrounding cartilage at 52 weeks, with an excellent degree of confluence with the neighboring tissue. The newly grown tissues were morphologically similar to normal hyaline articular cartilage. The dynamic shear moduli for the neocartilage from both the CAGE and PM groups significantly increased with postoperative healing time (p less than 0.05). However, there was no statistical difference between the two treatment modalities (p greater than 0.10), indicating that the passive motion did not enhance the long-term repair of the cartilage defect. These results support our hypothesis that neocartilage regenerated from perichondrial autograft remains intact over time.

Animals↗
PubMed1988

The chondrogenesis of rib perichondrial grafts for repair of full thickness articular cartilage defects in a rabbit model: a one year postoperative assessment.

The purpose of this study was to investigate the results or rib perichondrial grafting after the creation of a full thickness articular cartilage defect. In a rabbit model, rib perichondrium was used to repair defects created in the femoral condyle. The formation of repair tissue (neocartilage) and its chondrogenesis into a tissue resembling articular cartilage was found over time. The gross, histological and biochemical characteristics of the neocartilage were evaluated at intervals of 6, 12, 18, 26 and 52 weeks post transplant, and compared to normal articular cartilage. The neocartilage was characterized by the early formation of relatively large amounts of glycosaminoglycans. A steady increase in the proportion of type II collagen over the time periods was also observed. Improved attachment of the neocartilage to host tissues was seen over the period of 6 to 52 weeks. Successful grafts were seen to proliferate to fill the articular defect and to undergo a chondrogenesis over a post transplant time period of one year.

Animals↗
PubMed1987

Perichondrial autograft for articular cartilage. Shear modulus of neocartilage studied in rabbits.

Perichondrial autografts were used for the repair of large, full-thickness articular cartilage defects in the rabbit medial femoral condyle. The effects of duration of implantation and activity were studied by evaluating the neocartilage mechanically and morphologically. The complex shear moduli for the neocartilage were found to increase during the 26 weeks' observation time. Complete filling of the defect with neocartilaginous tissue was seen in a total of 24 successful experimental samples. It appeared that in the initial 6 weeks passive motion applied intermittently for 2 weeks enhanced the formation of quality neocartilage, i.e., the magnitude of the complex shear moduli was higher than those nontreated. However, these differences disappeared when longer time periods were considered.

Animals↗