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At least 73 records · Page 4Linked to original sources
PubMed2003

Effects of direction of tendon lacerations on strength of tendon repairs.

PURPOSE: We compared the tensile strength of different repair configurations on tendons with oblique and transverse lacerations. METHOD: Seventy-two fresh pig flexor tendons were divided randomly and repaired using the modified Kessler, the cruciate, or the 4-strand Massachusetts General Hospital (MGH) repair methods. The tendons were lacerated either transversely or obliquely. They were repaired with conventional and oblique suture repairs. The 2-mm gap formation force and ultimate strength were determined as biomechanical performance for each repair. RESULTS: The gap formation and ultimate strength of the tendons vary with orientations of tendon lacerations and suture methods. In the tendons repaired with the modified Kessler or the cruciate methods, the 2-mm gap formation and ultimate strength of obliquely cut tendons were significantly lower than those of transversely cut tendons. The obliquely placed modified Kessler or cruciate sutures significantly improved the repair strength in the tendons with an oblique laceration. In the tendons repaired with the MGH method, no statistical differences were found in the repair strength of obliquely and transversely lacerated tendons. CONCLUSIONS: The direction of tendon lacerations affects strength of certain repair configurations. The nonlocking modified Kessler or the cruciate tendon repairs are weakened considerably when the tendon laceration is oblique but their mechanical performance is strengthened by re-orienting the repair strands to lie parallel to the laceration. The cross-locked configuration of the MGH repair is not affected by the obliquity of the tendon laceration.

Analysis of Variance↗
PubMed2007

Patellar tendon length after anterior cruciate ligament reconstruction: a comparative magnetic resonance imaging study between patellar and hamstring tendon autografts.

Patellar tendon shortening after anterior cruciate ligament reconstruction may be associated with anterior knee pain or patellofemoral arthritis. The present study was designed to compare postoperative changes in patellar tendon length after anterior cruciate ligament reconstruction between patellar tendon and hamstring tendon autograft. Magnetic resonance images of both knees (operated and healthy) and functional outcome were documented at least 1 year postoperatively in 16 patellar tendon harvested patients and in 32 hamstrings harvested patients. Patellar tendon length, patella length and Insall-Salvati ratio were measured. The operated knee values were compared to the respective values of the non-operated control knees. A significant 4.2 mm or 9.7% patellar tendon shortening in patellar tendon group and a non-significant 1.14 mm or 2.6% shortening in hamstrings group was detected. No significant difference was detected in terms of major shortening-patella baja-(6% for the patellar tendon group vs. 0% for the hamstring group). There was no significant difference in anterior knee problems between the two groups as evidenced by the Shelbourne score (94 for the patellar tendon group vs. 98 for the hamstring group). Harvesting of the patellar tendon for anterior cruciate ligament reconstruction resulted in a significant shortening of the remaining tendon. In contrast harvesting of the hamstring tendons did not affect significantly the patellar tendon length. However, the incidence of patella baja and overall functional outcome was not significantly different between the two groups.

Adolescent↗
PubMed2004

Biomechanical and histologic comparison of Achilles tendon ruptures reinforced with intratendinous and peritendinous plantaris tendon grafts in rabbits: an experimental study.

INTRODUCTION: We hypothesized that the closer the reinforcing graft was to the repair zone, the more strength the healed tendon would achieved. Therefore, we compared the ruptured rabbit Achilles tendons reinforced with intratendinous and peritendinous plantaris grafts. MATERIALS AND METHODS: The experimental study was performed on Achilles tendons of 20 rabbits. First, they were divided into two groups: group I (n=10) underwent intratendinous graft and end-to-end tenorraphy, and group P (n=10) were repaired end-to-end and then reinforced with a peritendinous plantaris graft. An above-knee cast was applied during 6 weeks postoperatively. The two groups were compared to each other biomechanically and histologically. Seven randomly selected rabbits from each group were used for biomechanical evaluation. The remaining six rabbits (three from each group) were used for histologic comparison. Non-operated sides (n=20) served as the control group. RESULTS: The mean maximum load at rupture of the repaired and control groups was 159.9+/-31 N, 83+/-7.5 N, and 207.5+/-35 N for group I, group P, and the control group, respectively. Values between groups were significantly different considering maximum load and absorbed energy to rupture. There was no significant difference between groups I and P in respect to strain. Control group tendons (groups I-C and P-C) had significantly more lengthening capability than operated tendons. Macroscopically, group I tendons were thicker and stiffer than group P tendons. Histologically, differences between the group I and group P specimens revealed that the healing process was faster in tendons augmented intratendinously. CONCLUSIONS: In reinforcing Achilles tendon repair, the site of the tendon graft affected the result. When the graft was used intratendinously, the healed tendon was more similar biomechanically to normal tendon and had more graft-tendon orientation histologically than the tendon augmented peritendinously.

Achilles Tendon↗
PubMed2000

Blood supply of the peroneal tendons: injection and immunohistochemical studies of cadaver tendons.

We studied the vascular pattern of human peroneal tendons with injection techniques and immunohistochemically by using antibodies against laminin The main blood supply arises from the peroneal artery. The distal part of the peroneus longus tendon is supplied by branches of the medial tarsal artery. Blood vessels enter the peritenon of both tendons via a mesotenon from the posterior aspect. From the peritenon, the blood vessels penetrate the peroneus brevis and peroneus longus tendons and anastomose with a longitudinally-oriented intratendinous network. The amount of vessels in the tendon substance is consistently less than in the surrounding peritenon. The distribution of blood vessels in the peroneal tendons is not homogeneous. In the region where the peroneus brevis tendon passes through the fibular groove, the longitudinally-oriented intratendinous vascular network is interrupted and the tendon is almost avascular. In this region, the tendon is squeezed between the peroneus longus tendon and the bony slide bearing of the lateral malleolus. The peroneus longus tendon has two avascular zones. In the region where the peroneus longus tendon curves around the lateral malleolus and the peroneal trochlea of the calcaneus, the anterior part of the tendon which is directed towards the pulley is avascular. A second avascular zone is located more distally in the region where the tendon changes direction and wraps around the cuboid.

Adult↗
PubMedDate not supplied

The influence of tendon length and fit on the strength of a tendon-bone tunnel complex. A biomechanical and histologic study in the dog.

Using a dog model, we examined the influence of tendon length and fit within a bone tunnel on the pull-out strength of a tendon-bone tunnel complex at 6 weeks after fixation. Fourteen adult mongrel dogs (weight, 25 to 30 kg) underwent bilateral hindlimb surgery in which the extensor digitorum longus tendon was transplanted into an extraarticular metaphyseal bone tunnel. Our findings demonstrated that pull-out strength at 6 weeks was enhanced by increasing the length of tendon within the tunnel. The average load to failure with 1 cm of tendon within the tunnel was 153.7 +/- 78.6 N, compared with 265.5 +/- 93.3 N for the specimens with 2 cm of tendon in the tunnel. Tendon fit within the tunnel was also found to be important. The average load to failure when a tendon was placed in a 4.2-mm diameter tunnel was 301 +/- 61 N at 6 weeks. The average load to failure when the tendon was placed within a 6-mm diameter tunnel was 228 +/- 65 N. These differences were statistically different. Histologically, the interface between the tendon and bone appeared to be most mature when there was intimate bone-to-tendon contact. These data suggest that maximizing tendon length within a bone tunnel and minimizing tendon-tunnel diameter mismatch will maximize the strength of a tendon-bone tunnel complex at 6 weeks.

Animals↗
PubMed2005

[The research progress of accelerating tendon healing and preventing tendon adhesion].

OBJECTIVE: To study the status quo of the methods and materials for accelerating the tendon healing and preventing the tendon adhesion as to provide an essential reference for future research and clinical application. METHODS: The recent articles on methods of accelerating tendon healing and preventing tendon adhesion were extensively reviewed. RESULTS: Tendon healing was decided by the co-effects of both endogenous and exogenous ways, and the former was more important. It was affected by the tendon sheath, vincula tendinum and synovial fluid as well. Tendon adhesion was mostly caused by excessive participation of exogenous healing factors and serious damage of the situations around the tendon. Tendon healing was accelerated by methods like repairing, reconstruction of peri-tendon tissues, electric stimulation, physiotherapy, adding herbs or growth factors, and gene intervention. Tendon adhesion was reduced or prevented by methods like the restoration of tendon sheath, using substitutions, adding herbs/drugs, and improving suturing techniques. CONCLUSION: Via the appropriate methods and techniques combining the Chinese traditional and modern medicine, tendon healing can be accelerated and the quality of tendon healing can be improved.

Animals↗
PubMed1994

Tendons attached to prostheses by tendon-bone block fixation: an experimental study in dogs.

To develop a method of tendon attachment to a metallic endoprosthesis, we evaluated fixation strength, clinical function of the tendon, and morphological changes in an experimental model. The canine supraspinatus tendon was removed from the greater tubercle of the humerus and attached to a titanium prosthesis. In 12 animals, the bone block underlying the tendon insertion was preserved and attached in one limb; the soft part of the tendon was attached directly to the prosthesis in the contralateral limb. Fixation strength was evaluated after 16 weeks of in vivo implantation (12 specimens) and compared with the in vitro fixation strength (12 specimens) and with intact normal controls (six specimens from cadavera). Function of the tendon in vivo was evaluated by force-plate analysis (at 3-week intervals). All specimens were evaluated histologically. Sixteen weeks after surgery, the tendon-bone block attachment was significantly stronger (mean, 16%) than the direct tendon attachment and not significantly different from the normal control, and the direct tendon attachment was significantly weaker (mean, 68%) than the normal control. There was significantly more weight-bearing on the limbs with a tendon-bone block attachment than on the limbs with a direct tendon attachment at both 3 and 6 weeks postoperatively. Both front legs showed increased weight-bearing with time, but the differences were not statistically significant. Anchorage by tissue ingrowth to the titanium prosthesis was found consistently--there was bone ingrowth in the tendon-bone block attachments and fibrous tissue ingrowth in the direct tendon attachments. When a bone block was preserved, the strength and stiffness were comparable with those of a normal tendon insertion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2005

Magnetic resonance imaging appearance of the flexor carpi radialis tendon after harvest in ligamentous reconstruction tendon interposition arthroplasty.

OBJECTIVE: To determine whether the post-harvest magnetic resonance (MR) imaging appearance of flexor carpi radialis (FCR) tendons, harvested during ligamentous reconstruction tendon interposition (LRTI) of the thumb carpometacarpal (CMC) joint arthroplasty, is consistent with tendon regeneration. DESIGN: Operative reports and patient medical records for all patients undergoing LRTI arthroplasty between 1995 and 2003 at our institution were reviewed. MR images of the patients' forearms and wrists were obtained and interpreted by two musculoskeletal radiologists. Using the flexor carpi ulnaris (FCU) tendon as an internal standard, the extent of FCR tendon regeneration was expressed as a percentage by dividing the volume of regenerated FCR tendon by the volume of the FCU tendon. PATIENTS: Fourteen patients who had the full thickness of the FCR tendon harvested and who were available for MR imaging were identified and included in the study. RESULTS AND CONCLUSIONS: At least partial regeneration of the FCR tendon occurred in 11 of the 14 patients (79%). Of these, 2 patients (14%), demonstrated complete, or nearly complete regeneration. Partial regeneration of the FCR tendon was seen in 9 of the 14 patients (64%). In 3 patients (21%), there was no appreciable regeneration of the FCR tendon. Among patients who underwent full-thickness harvest of the FCR tendon for LRTI arthroplasty of the first CMC joint, the follow-up MR imaging appearance of the flexor carpi radialis tendon was consistent with tendon regeneration in 79% of those examined.

Aged↗
PubMed1989

Comparative study of vascularized and nonvascularized tendon grafts for reconstruction of flexor tendons in zone 2: an experimental study in primates.

Vascularized tendon grafts were compared with nonvascularized tendon grafts in a primate experimental model. In four monkeys, seven vascularized extensor hallucis longus grafts were placed in the foot's digital fibroosseous canal and these were compared with eight nonvascularized tendon grafts similarly placed in the opposite extremities. The juncture techniques and postoperative protocols were identical for both tendon groups. All tendons were explored 5 months after insertion. The vascular pedicle was patent in all vascularized tendons. Three tendon ruptures occurred in nonvascularized tendons and only one rupture occurred in a vascularized tendon. The digits with vascularized tendons demonstrated a significantly better simulated total active motion (117 degrees versus 128 degrees, p less than 0.05) than digits with nonvascularized tendons. The difference was even more significant when a localized tenolysis of the proximal juncture of the tendon graft was performed (215 degrees versus 138 degrees, p less than 0.01). This study supports the concept that vascularized tendon grafts may be advantageous in scarred tendon beds.

Animals↗
PubMedDate not supplied

Arthroscopic reconstruction of the posterior cruciate ligament: a comparison of quadriceps tendon autograft and quadruple hamstring tendon graft.

PURPOSE: Considerable controversies remain on the graft choice and fixation methods in the posterior cruciate ligament (PCL) reconstruction. The purpose of this study was to compare, at minimal 2-year follow-up, the outcomes of PCL reconstruction between using quadriceps tendon autograft and using quadruple hamstring tendon autograft. TYPE OF STUDY: Case series. METHODS: All patients received only PCL reconstruction without combined severe associated posterolateral instability. From 1996 to 1998, there were 24 patients who had a quadriceps tendon autograft, and 30 patients with hamstring tendon autograft. Twenty-two of the quadriceps tendon group and 27 of the hamstring tendon autograft group with 2 more years of complete follow-up were included for final analyses. Clinical assessments consisted of Lysholm knee scores, International Knee Documentation Committee (IKDC) scores, thigh muscle girth and strength, and radiographic evaluation. RESULTS: On the Lysholm knee rating, 86% of patients showed good or excellent results in the quadriceps tendon group and so did 89% of patients in the hamstring tendon group. Fifty-nine percent of the quadriceps tendon group and 56% of the hamstring tendon group revealed a 3- to 5-mm ligament laxity. Two patients with quadriceps tendon grafts and 4 patients with hamstring tendon grafts revealed grade II laxity. The IKDC rating showed no significant difference between the 2 groups in terms of activity level, ligament laxity, and final rating. In the thigh girth side-to-side difference, 82% of the quadriceps tendon group and 78% of the hamstring tendon group had less than a 10-mm difference. CONCLUSIONS: Comparable satisfactory results between the 2 surgical groups were shown at a minimal 2 years follow-up. We suggested that both grafts could afford good ligament reconstruction likelihood and that they are reasonably acceptable graft choices for PCL reconstruction.

Adult↗
PubMedDate not supplied

Arthroscopic anterior cruciate ligament reconstruction: a metaanalysis comparing patellar tendon and hamstring tendon autografts.

BACKGROUND: The best choice of graft tissue for use in anterior cruciate ligament reconstruction has been the subject of debate. HYPOTHESIS: Anterior cruciate ligament reconstruction with patellar tendon autograft leads to greater knee stability than reconstruction with hamstring tendon autograft. STUDY DESIGN: Metaanalysis. METHODS: A Medline search identified articles published from January 1966 to May 2000 describing arthroscopic anterior cruciate ligament reconstruction with either patellar tendon or hamstring tendon autograft and with a minimum patient follow-up of 24 months. RESULTS: There were 1348 patients in the patellar tendon group (21 studies) and 628 patients in the hamstring tendon group (13 studies). The rate of graft failure in the patellar tendon group was significantly lower (1.9% versus 4.9%) and a significantly higher proportion of patients in the patellar tendon group had a side-to-side difference of less than 3 mm on KT-1000 arthrometer testing than in the hamstring tendon group (79% versus 73.8%). There was a higher rate of manipulation under anesthesia or lysis of adhesions (6.3% versus 3.3%) and of anterior knee pain in the patellar tendon group (17.4% versus 11.5%) and a higher incidence of hardware removal in the hamstring tendon group (5.5% versus 3.1%). CONCLUSIONS: Patellar tendon autografts had a significantly lower rate of graft failure and resulted in better static knee stability and increased patient satisfaction compared with hamstring tendon autografts. However, patellar tendon autograft reconstructions resulted in an increased rate of anterior knee pain.

Adult↗
PubMed2004

Digital resistance and tendon strength during the first week after flexor digitorum profundus tendon repair in a canine model in vivo.

BACKGROUND: After flexor tendon repair, the strength of the repair and the resistance to digital motion are important considerations in deciding when to initiate postoperative rehabilitation. Our objective was to assess these factors in a short-term in vivo canine model of flexor tendon repair. METHODS: Forty-eight dogs were randomly allocated to four groups based on the duration of postoperative follow-up (one, three, five, or seven days). In each group, two flexor digitorum profundus tendons of one forepaw were exposed. One tendon (the repair tendon) was sharply transected and repaired with a modified Kessler suture, and the other one (the sham tendon) was simply exposed without laceration. The involved paw was immobilized until the animal was killed on the designated day. Three tendons from each dog, including the repair tendon, the sham tendon, and a control tendon from a corresponding normal digit on the contralateral side, were tested. RESULTS: The mean peak total digital resistance force in the repair group was lowest at five days (p < 0.01 compared with seven days; p > 0.05 compared with one and three days). The mean peak force needed to overcome the internal gliding resistance between the repaired tendon and sheath was significantly higher than that in both the sham and control groups at all time-points (p < 0.001); however, this value was also smallest at five days. There was no significant difference in suture strength at any time-point (p > 0.05). CONCLUSIONS: When we evaluated tendon-gliding and suture strength after flexor tendon repair, the least favorable ratio of repair strength to force needed to overcome the resistance to digital motion was noted on Day 7, whereas the best combination of tendon strength and low peak resistance force was noted on Day 5.

Animals↗
PubMed2006

Evaluation of passive and active rehabilitation and of tendon repair for partial tendon lacerations after three weeks of healing in canines.

BACKGROUND: Both passive and active rehabilitation have been shown to be superior to immobilization following partial tendon laceration, but few studies have directly compared these two rehabilitation protocols. In addition, controversy still remains over whether a partial tendon laceration should be repaired. METHODS: We evaluated gap formation, adhesions, gliding function and structural properties of repaired and unrepaired tendons following 3 weeks of unrestricted active rehabilitation versus passive mobilization for partial laceration of canine flexor digitorum profundus tendons. An ex vivo radiographic method was used to measure tendon excursion and rotation at each finger joint. The tendon was examined for adhesions, and gapping was measured with calipers. The tendons were tensile tested to failure. FINDINGS: We found no significant differences in tendon excursion, total joint rotation, or adhesions between any groups. Gap size was higher with active mobilization. We found no effect of rehabilitation protocol on the strength or stiffness of healing tendons at 3 weeks. Tendon repair did not affect tendon strength, but did produce higher stiffness in healing tendons at 3 weeks. INTERPRETATION: The results indicate that active rehabilitation appears safe for partial lacerations less than 60 percent. Though repair appears to weaken the tendon in the early stages of healing, it may provide some biomechanical benefit by the middle stages of healing.

Animals↗
PubMed2005

A 7-year follow-up of patellar tendon and hamstring tendon grafts for arthroscopic anterior cruciate ligament reconstruction: differences and similarities.

BACKGROUND: For arthroscopic anterior cruciate ligament reconstruction, the most commonly used graft constructs are either the hamstring tendon or patellar tendon. Well-controlled, long-term studies are needed to determine the differences between the 2 materials. HYPOTHESIS: There is a difference between hamstring and patellar tendon grafts in the clinical results of anterior cruciate ligament reconstructions at 7 years. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Two groups of 90 patients each, consecutively treated with hamstring or patellar tendon grafts, were followed and assessed at 1, 2, 5, and 7 years after surgery. RESULTS: At the 7-year review, abnormal radiographic findings were seen in 45% (24/53) of the patellar tendon group and in 14% (7/51) of the hamstring tendon group (P = .002). Although there was no significant difference between the groups in extension deficit (P = .22), the percentage of patients with an extension deficit increased significantly in the patellar tendon group from 8% at 1 year to 25% at 7 years (P = .02). No significant change was seen in the hamstring tendon group over time (P = .20). There was no significant difference in laxity between the groups on Lachman (P = .44), pivot-shift (P = .39), or instrumented (P = .44) testing. Graft rupture occurred in 4 patients from the patellar tendon group and in 9 patients from the hamstring tendon group (P = .15). Both autografts gave excellent subjective results, as evidenced by the International Knee Documentation Committee evaluation and Lysholm knee scores at 7 years. CONCLUSIONS: Both hamstring and patellar tendon grafts provided good subjective outcomes and objective stability at 7 years. No significant differences in the rate of graft rupture or contralateral anterior cruciate ligament rupture were identified. Patients with patellar tendon grafts had a greater prevalence of osteoarthritis at 7 years after surgery; therefore, the authors preferred hamstring tendons as the primary graft choice in anterior cruciate ligament reconstructions.

Anterior Cruciate Ligament↗
PubMed2003

Enveloping the tendon graft with periosteum to enhance tendon-bone healing in a bone tunnel: A biomechanical and histologic study in rabbits.

PURPOSE: Fixing and incorporating the tendon graft within the bone tunnel is a major concern when using grafts for ligament reconstruction. The periosteum contains multipotent stem cells and has the potential to form osteogenic and chondrogenic tissues. This study uses histologic and biomechanical analyses to examine the effect of periosteum on tendon-bone healing within a bone tunnel. TYPE OF STUDY: Experimental study in an animal model. METHODS: In this study, 36 adult New Zealand White rabbits were used. The long digitorum extensor tendon was transplanted into a bone tunnel of the proximal tibia. The periosteum from the proximal tibia was sutured on the surface of the tendon portion. The tendon was pulled through a drill-hole in the proximal tibia and attached to the medial aspect of the tibia. Histologic examination of the tendon-bone interface and biomechanical test for maximal pullout load were evaluated at 4, 8, and 12 weeks after operation. RESULTS: Histologic analysis of the tendon-bone interface showed a fibrous layer formed between the tendon and the bone by the periosteum. This layer became progressively integrated with the tendon and bone surface during the healing process. At 4 weeks, the cancellous bone lining in the bone tunnel was interdigitated with the fibrous interface tissue. At 8 weeks, progressive new bone grew into the interface fibrous layer. At 12 weeks, collagen fibers anchored to the bone and organization with fibrocartilage formation developed between the tendon and bone. Biomechanical testing revealed higher maximal pullout strength in the periosteum-enveloped group at all time points, with a statistically significant difference at 8 and 12 weeks. The periosteum-treated group had a higher interface strength-to-length ratio and significant increase at 8 weeks and 12 weeks. CONCLUSIONS: The histologic and biomechanical studies demonstrated that, if periosteum was sutured on the tendon that was transplanted within a bone tunnel, it resulted in a superior healing process and better healed strength. When doing ligament reconstruction with a tendon graft, the periosteum can be sutured to the graft to enhance tendon-bone healing.

Animals↗
PubMedDate not supplied

A biomechanical analysis of matched bone-patellar tendon-bone and double-looped semitendinosus and gracilis tendon grafts.

Biomechanical testing was done on 15 matched pairs of central-third bone-patellar tendon-bone and double-looped semitendinosus-gracilis grafts harvested from 15 cadaveric knees. Load to failure, composite graft stiffness, and the modulus of elasticity were calculated for each graft. Specimens were from 2 female and 13 male donors (average age, 40 years; range, 17 to 53). Average load to failure for the patellar tendon grafts was 1784 N (+/- 580), compared with 2422 N (+/- 538) for the hamstring tendon grafts (significantly different). There was no statistically significant difference in stiffness between grafts (patellar tendon, 210 N/mm; hamstring tendon, 238 N/mm). The elastic modulus was 225 MPa (+/- 129) for the patellar tendon grafts and 145 MPa (+/- 58) for the hamstring tendon grafts (significantly different). The average cross-sectional area for the hamstring tendon grafts was 57 mm2, compared with the 45 mm2 for the patellar tendon grafts. The hamstring tendon grafts were significantly stronger than the matched central-third patellar tendon grafts, but the two grafts were similar in stiffness. The patellar tendon grafts had a higher modulus than the hamstring tendon grafts.

Adult↗
PubMed1979

[An experimental study on repair and restoration of gliding function of the injured flexor tendon of the finger. Part 6: A mode of vascularization of the grafted tendon within the pseudosheath (author's transl)].

The so-called two-stage procedure has been used in the reconstructive surgery for the severely injured flexor tendon of the finger. However, only little has been known as to vascularity of the grafted tendon within the pseudosheath. In order to clarify this problem, a series of experimental studies were carried out using young chickens. First, the flexor tendon of the fourth digit of chicken with its sheath was replaced by a silicone rod. The distal end of the rod was sutured to the stump of the flexor digitorum profundus and the proximal end left free. Then, in ten to sixteen weeks, upon removal of the rod, the flexor digitorum profundus of the third digit was grafted through into the newly formed pseudosheath. The paw was immobilized with plaster case in moderate flexion for three weeks, then the chicken was allowed to walk freely. At the different time intervals, starting from the third day to the fifteen weeks after surgery, a mode of vascularization of the grafted tendon and its surrounding tissue was examined microangiographically. The vessels appear at the area of proximal and distal stump of the grafted tendon a week postoperatively, and additional vessels appear at the contact area of the pseudosheath and the grafted tendon two weeks postoperatively. These vessels formed mutual anastomosis in five to six weeks. With time, the vessels connecting between the epitenon and the pseudosheath gradually enlarge and assemble together to form vascular bundles, so that the appearance of the structure becomes similar to that of the mesotenon. Three weeks postoperatively, the vessels appeared in the grafted tendon, and grew gradually so that these vessels ran through the full length of the grafted tendon in five to six weeks. About ten weeks, the vascularity of the grafted tendon is more abundant than that of the normal tendon, but diminished gradually so as to resemble that of the normal tendon at the fifteeth week. Thus, the growth of the vessels of the tendon grafted by two-stage procedure is delayed by two weeks compared with that by the primary tendon grafting.

Animals↗
PubMed2003

[Biomechanical properties of tissue-engineered tendons after repairing digital flexor tendons in chickens].

Experiments have been performed to investigate why the biomechanical strength of repaired tendons is lower than that of the normal tendon when the engineered tendons are implanted in vivo to replace the tendon defects. We seeded the primary culture tendon cells derived from Roman chickens' digital flexor tendons on the degradable polyglycolic acid meshes to construct tissue-engineered tendons. The flexor tendon defects (0.5 cm-0.8 cm) excised in second digit bilaterally in 20 Roman chickens, had been repaired with the constructed tissue-engineered tendons. The samples of repaired tendons were collected at 2, 4, 6 and 8 weeks after operation. Tests for scaffold weight, hydroxyproline content, and mechanical strength of the samples were performed. We found that from 2 weeks to 8 weeks afteroperation, the weight of the scaffolds decreased significantly, almost disappearing at 8 weeks; the hydroxyproline content determining the total collagen content increased gradually without significance; mechanically, both energy at break and tensile strength showed a tendency of drastic decrease at first 4 weeks afteroperation and a gradual increase afterwards, but the tensile strength at 8 weeks afteroperation was only 23% of that of the normal tendon. We conclude that the lower biomechanical strength of repaired tendons is owing to the serious mismatch between scaffold degradation and collagen synthesis.

Achilles Tendon↗