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At least 109 records · Page 6Linked to original sources
PubMed1991

Regeneration of Achilles tendon with a collagen tendon prosthesis. Results of a one-year implantation study.

We previously reported on the short-term biocompatibility of a reconstituted type-I collagen prosthesis that had been tested in the Achilles tendons of rabbits. Preliminary results indicated that, by ten weeks after implantation, carbodiimide-cross-linked implants had been replaced by neotendon in a manner that was similar to that of autogenous tendon grafts that had been used as controls. Also by ten weeks after implantation, glutaraldehyde-cross-linked collagen implants were encapsulated and appeared to have caused an acute inflammatory response. In the present study, carbodiimide and glutaraldehyde-cross-linked collagen implants and autogenous grafts that served as controls were implanted for fifty-two weeks as a replacement for a three-centimeter section of the Achilles tendon of rabbits. The absence of a crimp in a cross-linked implant and the presence of a crimp in normal tendon and in tendon that formed after an implant had been resorbed made it possible to distinguish between a cross-linked implant and new host tendon that had replaced the implant after it was resorbed. New collagen that had replaced the implant and autogenous (control) tendon graft were compared with normal Achilles tendon with respect to the angle and length of the crimp. The autogenous grafts and the carbodiimide-cross-linked collagen implants had been completely resorbed and replaced by neotendon. The neotendon that was present fifty-two weeks after implantation was similar, but not identical, to normal tendon. In contrast, the glutaraldehyde-cross-linked implant was essentially inert, had not been resorbed, and was surrounded by a capsule of collagenous connective tissue. The neotendon in the capsule was also similar, but not identical, to normal tendon. There were more cells in the capsule than in the autogenous grafts or in the carbodiimide-cross-linked implants. The results of the present study indicate that rapid repair is achieved with a carbodiimide-cross-linked collagenous implant that has a structure and mechanical properties that are similar to those of an autogenous tendon graft and that biodegrades at a similar rate. Prolonged biodegradation of a glutaraldehyde-cross-linked collagenous implant results in formation of a capsule and only limited formation of neotendon.

Achilles Tendon↗
PubMed1996

Adenovirus-mediated gene transfer into tendon and tendon sheath.

In this study, we successfully transferred the Escherichia coli beta-galactosidase gene. LacZ, into the chicken tendon and tendon sheath by a recombinant adenovirus. The recombinant adenovirus Adv-beta gal that carried the E. coli LacZ gene was constructed by homologous recombination in 293 cells (human transformed embryonic kidney) between the expressing vector and the ClaI large fragment of adenovirus 5 genome. Each chicken received a 10 microliters injection containing 10(5) plaque-forming units of recombinant virus Adv-beta gal. into the tendon sheath of the long toe Samples of tendon and tendon sheath were harvested at 3.30, and 75 days after the injection. The LacZ gene transfer was detected for its coding product beta-galactosidase by staining with X-gal solution. The results showed that all tendon and tendon sheath samples from the three harvest times stained positive (blue). The tendon sheath samples were more extensively stained; staining of the tendon was limited to the epitenon layer. These data suggest that a functional exogenous gene can potentially be transferred into the tendon and tendon sheath by similar techniques; such techniques may be used to improve healing and reduce adhesion formation.

Adenoviridae↗
PubMed2004

The comparison of patellar tendon-bone autografting and free flexor-tendon autografting in infraspinatus defect of the shoulder: biomechanical and histological evaluation in a sheep model.

The purpose of this study was to investigate the biomechanical and histological features of patellar tendon-bone autografting and free flexor-tendon autografting, which were fixed by two different techniques at the tendon-bone junction in reconstruction of an infraspinatus defect in sheep. Merino type sheep ( n=10) were divided into two groups. Following a defect in the infraspinatus tendon, in group I (flexor-tendon autografting) the free end of the flexor tendon was passed through the holes in the greater tuberosity for fixation. In group II (patellar tendon-bone autografting), fixation was obtained by impaction of the tibial bone plug to the greater tuberosity. Twelve weeks later, animals were sacrificed and specimens were evaluated biomechanically and histologically. Recovery of tensile mechanical properties was achieved to a level of approximately 50% in Group I and 70% in Group II at the end of the 12th week. No difference in the stiffness values was found. In group I, there was a difference between operated and contralateral (non-operated) tendons for the ultimate tensile strength values, but no difference was found in group II. Histologically, in group I, the defective area, which filled with a hypercellular connective tissue, could hardly be differentiated from the normal tendon tissue. In group II, complete incorporation of the bone block was seen in all specimens. These results suggested that patellar tendon-bone autografting is more advantageous than free flexor-tendon autografting in infraspinatus defect, providing rapid healing and better mechanical properties, especially in the early period of healing.

Animals↗
PubMed1999

In situ microdialysis in tendon tissue: high levels of glutamate, but not prostaglandin E2 in chronic Achilles tendon pain.

This investigation was to our knowledge the first to use the microdialysis technique to study concentrations of substances in a human tendon. In four patients (mean age 40.7 years) with a painful nodule in the Achilles tendon (chronic Achilles tendinosis) and in five controls (mean age 37.2 years) with normal Achilles tendons (confirmed by ultrasonography) the local concentrations of glutamate and prostaglandin E2 were measured under resting conditions. A standard microdialysis catheter was inserted into the Achilles tendon under local anesthesia. Sampling was performed every 15 min over a 4-h period. The results showed significantly higher concentrations of glutamate in tendons with tendinosis than in normal tendons (196 +/- 59 vs. 48 +/- 27 mumol/l, P < 0.05), and there were no significant changes in glutamate concentration over the period of investigation. There were no significant differences in the mean concentrations of prostaglandin E2 (83 +/- 22 vs. 54 +/- 24 pg/ml) between tendons with tendinosis and normal tendons. In conclusion, in situ microdialysis appears a useful method to study certain metabolic events in tendon tissue. The higher concentrations of the excitatory neurotransmitter glutamate in Achilles tendons with a painful nodule may possibly be involved in the pain mechanism in this chronic condition. Furthermore, there were no signs of inflammation in the tendons with painful nodules, as indicated by the normal prostaglandin E2 levels.

Achilles Tendon↗
PubMed2004

Characterisation of proteoglycans and their catabolic products in tendon and explant cultures of tendon.

Tendons are collagenous tissues made of mainly Type I collagen and it has been shown that the major proteoglycans of tendons are decorin and versican. Little is still known about the catabolism of these proteoglycans in tendon. Therefore, the aim of the study was to characterise the proteoglycans including their catabolic products present in uncultured bovine tendon and in the explant cultures of tendon. In this study, the proteoglycans were extracted from the tensile region of deep flexor tendon and isolated by ion-exchange chromatography and after deglycosylation analysed by SDS-polyacrylamide electrophoresis, Western blotting and amino-terminal amino acid sequence analysis. Based on amino acid sequence analysis, approximately 80% of the total proteoglycan core proteins in fresh tendon was decorin. Other species that were detected were biglycan and the large proteoglycans versican (splice variants V(0) and/or V(1)) and aggrecan. Approximately 35% of decorin present in the matrix showed carboxyl-terminal proteolytic processing at a number of specific sites. The analysis of small proteoglycans lost to the medium of tendon explants showed the presence of biglycan and decorin with the intact core protein as well as decorin fragments that contained the amino terminus of the core protein. In addition, two core protein peptides of decorin starting at residues K(171) and D(180) were observed in the matrix and one core protein with an amino-terminal sequence commencing at G(189) was isolated from the culture medium. The majority of the large proteoglycans present in the matrix of tendon were degraded and did not contain the G1 globular domain. Furthermore the aggrecan catabolites present in fresh tendon and lost to the medium of explants were derived from aggrecanase cleavage of the core protein at residues E(373)-A(374), E(1480)-G(1481) and E(1771)-A(1772). The analysis of versican catabolites (splice variants V(0) and/or V(1)) also showed evidence of degradation of the core protein by aggrecanase within the GAG-beta subdomain, as well as cleavage by other proteinase(s) within the GAG-alpha and GAG-beta subdomains of versican (variants V(0) and/or V(2)). Degradation products from the amino terminal region of type XII collagen were also detected in the matrix and medium of tendon explants. This work suggests a prominent role for aggrecanase enzymes in the degradation of aggrecan and to a lesser extent versican. Other unidentified proteinases are also involved in the degradation of versican and small leucine-rich proteoglycans.

Amino Acid Sequence↗
PubMed2003

A computational model for the adaptation of muscle and tendon length to average muscle length and minimum tendon strain.

This paper hypothesizes that average muscle length and minimum tendon strain govern muscle and tendon length adaptation in all situations. A model has been implemented to test this hypothesis, and simulations have been performed for normal development, bone lengthening, immobilization, and retinacular release experiments in young and adult animals. The simulation results predict that both muscle and tendon lengthen during normal development, with the rate of tendon growth slowing faster than the rate of muscle growth. The results also predict that muscle length increases during bone lengthening in both young and adult animals, while tendon length increases only in young animals. For immobilization in adult animals, the results predict that muscle length increases when the muscle is immobilized in a lengthened position and decreases when the muscle is immobilized in a shortened position with no change in tendon length. For immobilization in young animals, the results predict reduced muscle growth and increased tendon growth regardless of immobilization position. Finally, the simulations predict that retinacular release which increases excursion of the musculotendinous unit leads to increased muscle length with decreased tendon length in young animals and decreased muscle length with no change in tendon length in adult animals. These simulation results are consistent with experimental findings reported in the literature by other investigators. This suggests that average muscle length and minimum tendon strain may represent general principles that govern muscle and tendon length adaptation.

Adaptation, Physiological↗
PubMed2003

Inhibition of tendon cell migration by dexamethasone is correlated with reduced alpha-smooth muscle actin gene expression: a potential mechanism of delayed tendon healing.

Local corticosteroid injection is commonly used to treat sports-related tendon injuries. However, isolated cases of tendon rupture following injection suggest that this treatment may impair the healing process. Tendon healing requires the migration of tendon cells to the repair site, followed by the proliferation and synthesis of the extracellular matrix. This study was designed to determine the effect of dexamethasone on the migration of tendon cells intrinsic to rat Achilles tendon at concentrations similar to those typically used for local injection treatment. Furthermore, the existence of a correlation between this effect and the expression of the contractile actin isoform, alpha-smooth muscle (SM) actin, which is associated with cell motility, was also examined. Using cultured tendon cells, migration was evaluated by counting the number of initial outgrowths from the tendon explants and by transwell filter migration assay. The distribution and assembly of alpha-SM actin were assessed by immunocytochemistry. The mRNA and protein expressions of alpha-SM actin were determined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis. Dose-dependent dexamethasone inhibition was demonstrated for both tendon cells outgrowth from the explants, ex vivo, and migration of tendon cells through the transwell filter, in vitro. Immunocytochemical staining revealed significant decreases in both the amount and assembly of alpha-SM actin in cells. Suppression of mRNA expression and protein level of alpha-SM actin was revealed from RT-PCR and Western blot analyses. In conclusion, dexamethasone inhibits tendon cell migration that is correlated with decreased gene expression of alpha-SM actin.

Achilles Tendon↗
PubMed2003

Tendon morphogenesis in the developing avian limb: plasticity of fetal tendon fibroblasts.

The differentiation and patterning of tendon fibroblasts is at present a poorly understood aspect of musculoskeletal development in the vertebrate limb. Precursors of tendon fibroblasts originate in the somatic mesoderm adjacent to the early limb bud and gradually become incorporated into the limb mesenchyme as development proceeds. It is unclear whether these progenitor cells are committed to the tendon lineage at this early stage, or whether cells become committed only as they are incorporated into a developing tendon. Following a review of our current knowledge of early tendon development, we present recent results from our preliminary studies looking at tendon cell commitment. Using a lacZ encoding replication-deficient retrovirus, we have mapped regions of the early limb bud that contain presumptive tendon progenitor cells, and later used these sites for implanting labelled fetal tendon fibroblasts into developing limbs. Following implantation, we found that these cells successfully re-incorporated into developing proximal and distal tendons, but also surprisingly contributed to other tissue lineages within the limb. Our results suggest that fetal tendon fibroblasts may not be irreversibly committed to a tendon cell fate in the limb and may be somewhat plastic in their ability to integrate into other tissue lineages during development.

Animals↗
PubMed2005

Surface-active phospholipid (surfactant) in equine tendon and tendon sheath fluid.

AIM: To investigate the presence of surface-active phospholipid (SAPL, or surfactant) in equine tendon and tendon sheath fluid. METHODS: The left front flexor tendon and sheath were removed from five Thoroughbred horses. Phospholipid was extracted from tendon sheath fluid using Folch reagent and quantified using spectroscopy. Transmission electron microscopy (TEM) was used to observe the tendon surfaces. RESULTS: The presence of phospholipid (90.6 (SD 4.3) microg/ml) in tendon sheath fluid, plus the appearance of oligolamellar layers and lamellar bodies on the tendon surface were indicative of SAPL. CONCLUSIONS: Evidence of SAPL was found in equine tendon, and may have a similar lubricating function as reported for synovial joints. CLINICAL RELEVANCE: These findings may have important implications for normal tendon function and possible therapeutic adjuncts for tendon and tendon sheath injuries.

Animals↗
PubMedDate not supplied

A prospective randomized comparison of patellar tendon versus semitendinosus and gracilis tendon autografts for anterior cruciate ligament reconstruction.

Seventy patients with patellar tendon or hamstring tendon autografts for single-incision anterior cruciate ligament reconstruction were evaluated at least 2 years after surgery. All reconstructions were performed by the same surgeon, and metal interference screws were used for fixation of all grafts. No significant differences were noted between groups for Lysholm score, reduction in activity, KT-1000 arthrometer findings, quadriceps muscle size, return to sports, or ability to jump and do hard cuts and pivots. Significantly more patients in the patellar tendon group had patellofemoral pain at 6 months after surgery than did the hamstring tendon patients (48% versus 20%), and at last follow-up the incidence of patellofemoral pain was 42% and 20%, respectively. Fourteen patients in the patellar tendon group and seven in the hamstring tendon group had loss of motion (approximately 5 degrees ). Four patients (two in each group) had treatment failures and their results were not included in the clinical examination data. At 2 years' follow-up, 97% of patients with patellar tendon grafts and 100% of patients with hamstring tendon grafts rated their results as good or excellent. We found that hamstring tendon grafts performed similarly to patellar tendon grafts, although fewer patients in the hamstring tendon group had patellofemoral pain and loss of motion.

Adolescent↗
PubMed2006

A prospective, randomized comparison of semitendinosus and gracilis tendon versus patellar tendon autografts for anterior cruciate ligament reconstruction: five-year follow-up.

BACKGROUND: There are still controversies about graft selection for primary anterior cruciate ligament reconstruction. Prospective randomized long-term studies are needed to determine the differences between the materials. HYPOTHESIS: Five years after anterior cruciate ligament reconstruction, there is a difference between hamstring and patellar tendon grafts in development of degenerative knee joint disease. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: From June 1999 to March 2000, 64 patients were included in this prospective study. A single surgeon performed primary arthroscopically assisted anterior cruciate ligament reconstruction in an alternating sequence. In 32 patients, anterior cruciate ligament reconstruction was performed with hamstring tendon autograft, whereas in the other 32 patients, anterior cruciate ligament reconstruction was performed with patellar tendon autograft. RESULTS: At the 5-year follow-up, no statistically significant differences were seen with respect to the Lysholm score, clinical and KT-2000 arthrometer laxity testing, anterior knee pain, single-legged hop test, or International Knee Documentation Committee classification results; 23 patients (82%) in the hamstring tendon group and 23 patients (88%) in the patellar tendon group returned to their preinjury activity levels. Graft rupture occurred in 2 patients from the hamstring tendon group (7%) and in 2 patients from the patellar tendon group (8%). Grade B abnormal radiographic findings were seen in 50% (13/26) of patients in the patellar tendon group and in 17% (5/28) of patients in the hamstring tendon group (P = .012). CONCLUSION: Both hamstring and patellar tendon grafts provided good subjective outcomes and objective stability at 5 years. No significant differences in the rate of graft failure were identified. Patients with patellar tendon grafts had a greater prevalence of osteoarthritis at 5 years after surgery.

Adolescent↗
PubMed2003

[Reconstruction of the ruptured extensor pollicis longus tendon using a tendon interposition graft].

To restore function of the ruptured extensor pollicis longus (EPL) tendon, two operative principles have been described: reconstruction of the original tendon using a tendon interposition graft or a tendon transposition operation, most commonly transposition of the extensor indicis. From 1992 to 1998, we reconstructed the extensor pollicis longus tendon using an interposition graft in 58 patients. 48 patients were available for follow-up after a mean of 31 months. The mean age of the 25 women and 23 men was 49 years. The time between tendon rupture and reconstruction ranged from one to 40 weeks. The tendon rupture occurred in 19 patients following a radius fracture, in 22 patients without history of trauma and in seven patients it was due to a sharp injury. Using the clinical score of Geldmacher and Köckerling, five patients achieved a very good, 35 patients a good and eight patients a satisfactory result. No patient had a poor result. According to the statistical analyses, these results were independent of the age of the patients, the origin of the rupture or the time interval between rupture and tendon reconstruction. The average DASH score measured 14. Considering our results, secondary reconstruction of the original EPL tendon appears to be a valuable alternative to the commonly performed tendon transpositions. It yields good clinical results with little remaining functional impairment and without the need to sacrifice another functional motor. We strongly recommend this technique in patients who require an independent and strong extension of the index finger in their profession (surgeons, musicians) and in patients with severe trauma that does not allow the sacrifice of another intact motor unit.

Adolescent↗
PubMed2004

Tendon injury response: assessment of biomechanical properties, tissue morphology and viability following flexor digitorum profundus tendon transection.

Insertion site injuries of the flexor digitorum profundus (FDP) tendon often present for delayed treatment. Apart from gross observations made at the time of surgery, the changes that occur in the flexor tendon stump during the interval from injury to repair are unknown. These changes may include tendon softening and loss of viability, which may contribute to the poor outcomes observed clinically and experimentally. Thirty-eight FDP tendons from 23 adult dogs were transected sharply from their insertions on the distal phalanges and were not repaired. Dogs were allowed full weight bearing and were euthanized 7 or 21 days after injury. Biomechanical testing indicated that the resistance of injured tendons to pullout of a Kessler-type suture was not different from control tendons at 7 days and was increased at 21 days by 25% (p<0.05). Morphologically, at 7 and 21 days the cut surface had a smooth appearance and the end of the injured tendon was increased in thickness by 30% and 50%, respectively (p<0.05). Histologically, we observed increased cellularity and dramatic fibroblast proliferation within the injured tendon stump; there was no evidence of decreased cell viability. We conclude that during the interval from 0 to 21 days after FDP insertion-site injury, tendons cells are viable, proliferative and synthesizing new matrix. This leads to increased tendon size and enhanced resistance to suture pullout. These findings offer a scientific rationale supporting the clinical practice of surgical re-attachment within the first 3 weeks after injury.

Animals↗
PubMed2001

Asymptomatic hypoechoic regions on patellar tendon ultrasound: A 4-year clinical and ultrasound followup of 46 tendons.

Patellar tendon ultrasound appearance is commonly used in clinical practice to diagnose patellar tendinopathy and guide management. Using a longitudinal study design we examined whether or not the presence of a hypoechoic ultrasonographic lesion in an asymptomatic patellar tendon conferred a risk for developing jumper's knee compared with a tendon that was ultrasonographically normal. Ultrasonographic, symptomatic and anthropometric assessment was completed at baseline and followup. Magnetic resonance imaging was performed on four tendons that resolved ultrasonographically in the study period. Forty-six patellar tendons were followed over 47+/-11.8 months. Eighteen tendons were hypoechoic at baseline and 28 were ultrasonographically normal. Five tendons resolved ultrasonographically in the study period. Magnetic resonance imaging in four of these tendons was normal. Seven normal patellar tendons at baseline developed a hypoechoic area but only two became symptomatic. Analysis of ultrasonography at baseline and clinical outcome with Fisher's exact test shows there is no association between baseline ultrasound changes and symptoms at followup. In this study there is no statistically significant relationship between ultrasonographic patellar tendon abnormalities and clinical outcome in elite male athletes. Management of jumper's knee should not be solely based on ultrasonographic appearance; clinical assessment remains the cornerstone of appropriate management.

Adult↗
PubMed2002

Carbon fibres and plasma-preserved tendon allografts for gap repair of flexor tendon in bovines: gross, microscopic and scanning electron microscopic observations.

The efficacy of carbon fibres and plasma-preserved tendon allografts for gap repair in the superficial digital flexor tendon in the mid-metatarsal region was evaluated in 12 crossbred calves. Experimental tenectomies were performed, followed by implantation of carbon fibres in group I (12 legs) and plasma-preserved tendon allografts in group II (12 legs). Gross observations in group I showed filling of the defect with granulation tissue with more vascularity on day 7, which was less prominent at day 14. On day 30, the neotendon formed was slightly thicker and comparable to normal tendon in appearance and texture. On day 90, it exhibited all the characteristics of a fully developed tendon. Whereas, in group II increased vascularity at the site and encapsulation of the graft with connective tissue in early periods was observed. The gap between graft and host was filled with fibrous connective tissue. Peritendinous adhesions were maximum on day 7 which were gradually reduced in both groups. Microscopically, an acute inflammatory reaction in the periphery of carbon fibres was observed on day 7. Immature fibroblasts were arranged in a haphazard pattern at this stage. By day 14, numerous newly formed capillaries and comparatively more mature fibroblasts were present in between and around the carbon fibres which were aligning parallel to the longitudinal axis of the tendon. By day 30 the healing tissue exhibited longitudinal orientation of collagen fibres and was at a more advance stage of maturation. By day 90, the neotendon formed simulated the picture of normal tendon. In the grafted tendon group, there was normal healing tissue at the functional sites between host and grafted tendon. The fibroblastic activity appeared to be both extrinsic and intrinsic in origin. The connective tissue had invaded the graft to a variable distance and there was resorption of graft which was replaced by newly formed connective tissue on day 90. Scanning electron microscopic observation revealed formation of neotendon between carbon fibre strands, resulting in thickening of the implant. In later stages parallel collagen fibres resembling normal tendon were observed in both groups.

Animals↗
PubMed2003

[Reconstruction of the extensor pollicis longus tendon by transposition of the extensor indicis tendon].

Rupture of the extensor pollicis longus-tendon (EPL) is a frequent complication after distal radius fractures. Other traumatic and non-traumatic reasons for this tendon lesion are known, including a theory about a disorder in the blood supply to the tendon itself. We examined 40 patients after reconstruction of the EPL-tendon in a mean follow-up time of 30 months. All patients were clinically examined and a DASH questionnaire was answered by all patients. The method to reconstruct the EPL-tendon was the transposition of the extensor indicis-tendon. After the operations the thumb was put in a splint for four weeks in a "hitch-hiker's-position". 31 ruptures of the tendon (77.5 %) were a result of trauma. In 20 of them (50 %) a distal radius fracture had occurred. Clinical examination included measurements of the movement of the thumb- and index-finger joints, the grip strength and the maximal span of the hand. Significant differences were not found. The isolated extension of the index finger was possible in all patients. But it was reduced in ten cases which represent 25 %. Our results were evaluated by the Geldmacher score to evaluate the reconstruction of the EPL-tendon. 20 % excellent, 65 % good, 12.5 % fair and 2.5 % poor results were reached. The Geldmacher score was used critically. We suggest its modification for the evaluation of thumb abduction. The DASH score reached a functional value of ten points which represents a very good result. In conclusion the extensor indicis-transposition is a safe method to reconstruct the EPL-tendon. Its substantial advantage is taking a healthy muscle as the motor, thereby avoiding the risk of using a degenerated muscle in late tendon reconstruction. A powerful extension of the index finger will be maintained by physical education. Generally, the loss of the extension of the index finger is negligible. It does not disturb the patients. But it has to be discussed with the patient before the operation.

Adolescent↗
PubMed1985

Changes induced by ozone and ultraviolet light in type I collagen. Bovine Achilles tendon collagen versus rat tail tendon collagen.

High-molecular-mass aggregates were made soluble from insoluble collagens of bovine Achilles tendon and rat tail tendon by limited thermal hydrolysis. These polymeric collagen aggregates were cross-linked by 390-nm-fluorescent 3-hydroxy-pyridinium residues (excited at 325 nm) in the former tendon and by unknown non-fluorescent residues in the latter. With the solubilized insoluble-collagens from both tendons, as well as with acid-soluble collagen from rat tail tendon, other 350-385-nm fluorescence intensities (excited at 300 nm) were found to be higher in monomeric chains than in dimeric and polymeric chains. Low levels of ozone inhibited fibril formation of acid-soluble collagen particularly from young rat tail tendon, reacting with tyrosine residues and the 350-385-nm fluorophores. Aldehyde groups, involved in cross-linking, were not effectively modified by ozone. beta-Components (alpha-chain dimers) were not efficiently dissociated even by higher doses of ozone compared to gamma-components (alpha-chain trimers). Polymeric chain aggregates from bovine Achilles tendon collagen, whose 3-hydroxy-pyridinium cross-links are cleaved by ozone, were more readily dissociated by ozone than those from rat tail tendon collagen. Ultraviolet (300-nm) light, which destroyed the 350-385-nm fluorophores, inhibited fibril formation less effectively than ultraviolet (275-nm) light, which is absorbed by tyrosine residues, and did not dissociate collagen polymers from rat tail tendon. On the other hand, ultraviolet (320-nm) light, absorbed by 3-hydroxy-pyridinium cross-links which were rapidly photolyzed, partially dissociated polymeric collagen aggregates from bovine Achilles tendon after subsequent heating.

Achilles Tendon↗
PubMed1999

The effect of gap formation at the repair site on the strength and excursion of intrasynovial flexor tendons. An experimental study on the early stages of tendon-healing in dogs.

BACKGROUND: Elongation (gap formation) at the repair site has been associated with the formation of adhesions and a poor functional outcome after repair of flexor tendons. Our objectives were to evaluate the prevalence of gap formation in a clinically relevant canine model and to assess the effect of gap size on the range of motion of the digits and the mechanical properties of the tendons. METHODS: We performed operative repairs after sharp transection of sixty-four flexor tendons in thirty-two adult dogs. Rehabilitation with passive motion was performed daily until the dogs were killed at ten, twenty-one, or forty-two days postoperatively. Eight tendons ruptured in vivo. In the fifty-six intact specimens, the change in the angles of the proximal and distal interphalangeal joints and the linear excursion of the flexor tendon were measured as a 1.5-newton force was applied to the tendon. The gap at the repair site was then measured, and the isolated tendons were tested to failure in tension. RESULTS: Twenty-nine tendons had a gap of less than one millimeter, twelve had a gap of one to three millimeters, and fifteen had a gap of more than three millimeters. Neither the time after the repair nor the size of the gap was found to have a significant effect on motion parameters (p > 0.05); however, the ultimate force, repair-site rigidity, and repair-site strain at twenty newtons were significantly affected by these parameters (p < 0.05). Testing of the tendons with a gap of three millimeters or less revealed that, compared with the ten-day specimens, the forty-two-day specimens failed at a significantly (90 percent) higher force (p < 0.01) and had a significantly (320 percent) increased rigidity (p < 0.01) and a significantly (60 percent) decreased strain at twenty newtons (p < 0.05). In contrast, the tensile properties of the tendons that had a gap of more than three millimeters did not change significantly with time. CONCLUSIONS: Our data indicate that, in a dog model involving sharp transection followed by repair, a gap at the repair site of more than three millimeters does not increase the prevalence of adhesions or impair the range of motion but does prevent the accrual of strength and stiffness that normally occurs with time.

Animals↗