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PubMed2006

The effect of corticosteroid on collagen expression in injured rotator cuff tendon.

BACKGROUND: Subacromial corticosteroid injections are commonly used in the nonoperative management of rotator cuff disease. The effects of corticosteroid injection on injured rotator cuff tendons have not been studied. Our aims were to characterize the acute response of rotator cuff tendons to injury through the analysis of the type-III to type-I collagen expression ratio, a tendon injury marker, and to examine the effects of corticosteroid on this response. METHODS: Sixty Sprague-Dawley rats were randomly assigned to four groups: control, tendon injury, steroid treatment, and tendon injury and steroid treatment. Six rats served as sham controls. Unilateral tendon injuries were created with full-thickness defects across 50% of the total width of the infraspinatus tendon, 5 mm from its humeral insertion. Steroid treatment with a single dose of methylprednisolone (0.6 mg/kg), equivalent to that given to humans, was injected into the subacromial space under direct visualization. Steroid treatment followed the creation of an injury in the rats in the injury and steroid treatment group. At one, three, and five weeks after the injury, the total RNA isolated from tendons was quantified with real-time polymerase chain reaction with use of primers for type-I and type-III collagen and ribosomal 18s RNA. RESULTS: The type-III to type-I collagen expression ratio remained at baseline at all time-points in the control and sham groups. At one week, the type-III to type-I collagen expression ratio increased more than fourfold above the control level in the tendon injury group (p = 0.017) and the tendon injury and steroid treatment group (p = 0.003). The ratio remained greater than twofold above the control at three weeks in both groups (p = 0.003 and p = 0.037) and returned to baseline at five weeks. Interestingly, the group that had steroid treatment only showed an increase of >4.5-fold (p = 0.001) in the type-III to type-I collagen expression ratio, without structural injury to the tendon. This ratio returned to baseline levels by three weeks. CONCLUSIONS: A single dose of corticosteroid does not alter the acute phase response of an injured rotator cuff tendon in the rat. However, the same steroid dose in uninjured tendons initiates a short-term response equivalent to that of structural injury.

Animals↗
PubMed2003

Effect of Achilles tendon lengthening on neuropathic plantar ulcers. A randomized clinical trial.

BACKGROUND: Limited ankle dorsiflexion has been implicated as a contributing factor to plantar ulceration of the forefoot in diabetes mellitus. The purpose of this study was to compare outcomes for patients with diabetes mellitus and a neuropathic plantar ulcer treated with a total-contact cast with and without an Achilles tendon lengthening. Our primary hypothesis was that the Achilles tendon lengthening would lead to a lower rate of ulcer recurrence. METHODS: Sixty-four subjects were randomized into two treatment groups, immobilization in a total-contact cast alone or combined with percutaneous Achilles tendon lengthening, with measurements made before and after treatment, at the seven-month follow-up examination, and at the final follow-up evaluation (a mean [and standard deviation] of 2.1 +/- 0.7 years after initial healing). There were thirty-three subjects in the total-contact cast group and thirty-one subjects in the Achilles tendon lengthening group. There were no significant differences in age, body-mass index, or duration of diabetes between the groups. Outcome measures were time to healing of the ulcer, ulcer recurrence rate, range of dorsiflexion of the ankle, peak torque (strength) of the plantar flexor muscles, and peak plantar pressures on the forefoot. RESULTS: Twenty-nine (88%) of thirty-three ulcers in the total-contact cast group and all thirty ulcers (100%) in the Achilles tendon lengthening group healed after a mean duration (and standard deviation) of 41 +/- 28 days and 58 +/- 47 days, respectively (p > 0.05). (One patient in the Achilles tendon lengthening group died before treatment was completed.) In the first seven months of follow-up, sixteen (59%) of the twenty-seven patients in the total-contact cast group who were available for follow-up and four (15%) of the twenty-seven patients in the Achilles tendon lengthening group who were available for follow-up had an ulcer recurrence (p = 0.001). At the time of the two-year follow-up, twenty-one (81%) of the twenty-six patients in the total-contact cast group and ten (38%) of the twenty-six patients in the Achilles tendon lengthening group had ulcer recurrence (p = 0.002). Compared with the group treated with the total-contact cast, the group treated with Achilles tendon lengthening had increased dorsiflexion and it remained increased at seven months (p < 0.001). Plantar flexor peak torque also decreased after Achilles tendon lengthening (p < 0.004), but it returned to baseline after seven months. Peak plantar pressures on the forefoot during barefoot walking were reduced (p < 0.0002) following Achilles tendon lengthening yet returned to baseline values within seven months after treatment. CONCLUSIONS: All ulcers healed in the Achilles tendon lengthening group, and the risk for ulcer recurrence was 75% less at seven months and 52% less at two years than that in the total-contact cast group. Achilles tendon lengthening should be considered an effective strategy to reduce recurrence of neuropathic ulceration of the plantar aspect of the forefoot in patients with diabetes mellitus and limited ankle dorsiflexion (</=5 degrees ).

Adult↗
PubMed2005

Dynamic observation on the effects of different suture techniques on the biomechanical properties in the healing of tendons.

To identify the best suture techniques for the tendon repair, the biomechanical properties of tendons sutured by different methods were dynamically examined. 140 chickens were divided into 2 groups equally: group A and group B. The tendon of the right side was subjected to injury-repair process, and the tendons of the left sides served as controls in both groups. In group A, "figure-of-8" suture, modified Kessler suture and Bunnell suture were used for the 2nd to 4th paws respectively, while in group B, Kleinert suture, Tsuge suture and Ikuta suture were used. On the day 0, 3, 7, 14, 21, 28, 42 after operation, 10 animals were sacrificed and the flexor tendons of both sides were harvested for strength test. The results showed that the initial strength of the repaired tendons and the strength after 6 weeks following tendon cut were far below those of intact tendons, irrespective of suture techniques used. With the 6 techniques, the P(max) of tendons repaired by Tsuge suture was increased continually, reaching the highest value on the 42nd day. The P(max) of tendons sutured by the modified Kessler suture was slightly lower than that by Tsuge suture, but it was increased steadily in healing. The tendons repaired by figure-of-8 suture yielded the lowest P(max). It was concluded that Tsuge suture and modified Kessler suture were the best techniques for tendon repair.

Animals↗
PubMed1994

Flexor sheath closure during delayed primary tendon repair.

We studied the effect of flexor tendon sheath closure on flexor tendon function after delayed primary flexor tendon suture in white leghorn chickens. The tendon suture was carried out after a tendon laceration. In the left foot the tendon sheath was closed after tendon suture, and in the right the sheath was excised over the tendon suture. Tendon gliding, joint motion, the fate of the closed sheath, peritendinous adhesions, and tendon healing were studied. The sutured sheath disappeared after suturing and was associated with poor tendon healing. Sheath closure did not improve flexor tendon function in a delayed primary repair.

Animals↗
PubMed2005

Effects of locking area on strength of 2- and 4-strand locking tendon repairs.

PURPOSE: The area of the tendon within the locking suture configuration of the modified Pennington repair is an important determinant of eventual tendon strength. This 2-strand repair's loop configurations encompass a large cross-sectional area of the tendon. Many recently proposed repairs, however, consist of locks in a number of narrow sites on the tendon surface and most are multistranded. It is not clear how the area within the locks affects tendon strength and whether the effects of locking areas change according to the number of repair strands. In this study we investigate the effects of locking area on repair strength of 2- and 4-strand tendon repairs. METHODS: Sixty-five fresh pig flexor tendons were divided equally into 6 groups and were transected completely. They were repaired with 2- or 4-strand techniques. The tendon-suture interface was a circle-locking junction and diameters of the locks were 1, 2, or 3 mm. The tendons were pulled in a tensile testing machine until failure of the repair and the mode of failure, 2-mm gap force, and ultimate strength were measured. RESULTS: In the tendons with either 2- or 4-strand repairs locks with a diameter of 2 or 3 mm had significantly greater gap formation force and ultimate strength than those of 1 mm. The gap formation and ultimate forces were not statistically different between tendons with locks of 2 or 3 mm in diameter. CONCLUSIONS: In both the 2- and 4-strand tendon repairs tested in this study repair strength increased as the diameter of locks of the repair increased from 1 mm to 2 or 3 mm. An increase in the diameter from 2 mm to 3 mm, however, did not increase the gap force and ultimate strength. These findings indicate that the cross-sectional area within the locks affects repair strength when the diameter of the locks is within a certain range (2 mm) and that further enlargement of the locking area does not increase strength.

Animals↗
PubMedDate not supplied

Tensile strength of a new suture for fixation of tendon grafts when using a weave technique.

PURPOSE: To evaluate a new corner stitch construct for tendon graft or tendon transfer fixation and compare the tensile strength with a conventional central cross-suture design in human cadaver tendons. METHODS: Flexor digitorum profundus tendons of the index, middle, and ring fingers (48 total) were used as recipients and palmaris longus, extensor indicis proprius, and extensor digitorum communis tendons of the index finger (48 total) were used as grafts from 16 fresh-frozen human cadaver hands. We compared the cross-stitch technique with a new corner stitch technique in tendon repairs made with 1, 2, or 3 weaves (8 per group). Tendons were sutured at each weave with either 2 full-thickness cross-stitches or 4 partial-thickness corner stitches of 4-0 nylon. Mattress sutures also were placed through the free tendon end for each repair type. The tensile strength of the tendon-graft composite was measured with a materials testing machine. RESULTS: The tensile strength of the repairs increased significantly with the number of weaves. When 2 or 3 weaves were used with the corner stitch or when 3 weaves were used with the cross-stitch, the repairs were significantly stronger. Although no significant difference in strength to failure was noted when comparing cross and corner stitches with equivalent numbers of weaves, qualitatively there was a difference in mode of failure with the 3-weave corner stitches failing primarily by intrasubstance tendon failure and the 3-weave cross-stitch repairs failing by tendon pullout. CONCLUSIONS: The corner stitch is as strong as conventional cross-stitch repairs and its superficial placement may be more favorable to tendon blood supply. This repair may be advantageous for clinical applications.

Fingers↗
PubMed2006

Analysis of relative motion splint in the treatment of zone VI extensor tendon injuries.

PURPOSE: Early protected motion after extensor tendon repair is desirable. The low-profile relative motion splint, described previously by Merritt et al, holds the affected digit in 15 degrees of extension relative to the uninjured digits to allow less-cumbersome early protected motion versus dynamic splinting. Although early clinical results have been favorable, formal biomechanic testing of this approach is lacking. We used an in vitro model to assess the effect of the low-profile relative motion splint on the biomechanics of zone VI extensor tendons by measuring tendon elongation with and without the splint. Tendon elongation also was measured after transection and repair of extensor tendons in zone VI with and without splint protection. METHODS: Ten fresh-frozen cadeveric upper extremities were prepared and mounted on a testing apparatus with the wrist in 25 degrees of extension. Alternating applications of extension and flexion loads to the tendons induced a full range of motion for 25 cycles. Differential variable reluctance transducers were applied to zone VI of the index, middle, and ring extensor tendons. Measurements of intact tendon microelongation (or strain) were obtained with and without the relative motion splint. The middle finger extensor tendon then was transected (in zone VI) and was repaired immediately. Measurements were repeated with and without splint protection. Elongation ratios were calculated and analyzed statistically. RESULTS: For the intact tendon of the middle finger splinting reduced the elongation by 1% in extension, by 2% in flexion, and by 3% in neutral position. After the transection and repair of this same tendon, the splint reduced the elongation by 5% in extension, by 7% in flexion, and by 6% in neutral position. Cycling without splint protection caused permanent stretching at the repair site. Reapplication of the splint decreased elongation at the repair site by 2% in extension, by 3% in flexion, and by 3% in neutral position. CONCLUSIONS: The relative motion splint reduces the effective strain on intact and repaired zone VI middle finger extensor tendons and supports its clinical use.

Aged↗
PubMed2002

Collagen fibril size and crimp morphology in ruptured and intact Achilles tendons.

The present study examined the hypothesis that collagen fibril diameter and crimp angle in ruptured human Achilles tendons differed from that of intact ones. Tissue samples were obtained from the central core (distal core) and the posterior periphery (distal superficial) at the rupture site, and the proximally intact (proximal superficial) part of the tendon in 10 subjects (38+/-8 years) with a complete tendon rupture. For comparisons corresponding tissue samples were procured from age (38+/-7 years) and gender matched intact Achilles tendons during routine forensic autopsy. The cross-sectional area density and diameter distribution of fibrils were analyzed using stereological techniques of digitized electron microscopy biopsy cross-sections, while crimp angle was measured by the changing banding pattern of collagen fibers when rotated between crossed polars. Nine of 10 persons with tendon ruptures reported that the injury did not occur during exceedingly large forces, and none experienced any symptoms in the days or months prior to the injury. Fibril diameter distribution showed no region-specific differences in either the ruptured or intact tendons for either group. However, in the distal core there were fewer fibrils in the ruptured compared to the intact tendons in 60-150 nm range, P<0.01. Similarly, in the distal superficial portion there were fewer fibrils in the ruptured compared to the intact tendons in the 90-120 nm range, 2P<0.05, while there were no differences in the proximal superficial tendons. Crimp angle did not display any region-specific differences, or any difference between the rupture and intact tendons. In conclusion, these data suggest that although crimp morphology is unchanged there appears to be a site-specific loss of larger fibrils in the core and periphery of the Achilles tendon rupture site. Moreover, the lack of symptoms prior to the rupture suggests that clinical tendinopathy is not an etiological factor in complete tendon ruptures.

Achilles Tendon↗
PubMed2002

Load-displacement properties of the human triceps surae aponeurosis and tendon in runners and non-runners.

The load-displacement and stress-strain characteristics of the human triceps surae tendon and aponeurosis, in vivo, was examined during graded maximal voluntary plantarflexion efforts in runners who trained 80 km/ week or more and age-matched non-runners. Synchronous real-time ultrasonography of triceps surae tendon and aponeurosis displacement, electromyography of the gastrocnemius, soleus and dorsiflexor muscles, and joint angular rotation were obtained. Tendon cross-sectional area and ankle joint moment arm were obtained from magnetic resonance imaging. Tensile tendon force was calculated from the joint moments and tendon moment arm and stress was obtained by dividing force by cross-sectional area. Strain was obtained from the displacements normalized to tendon length. Antagonist coactivation and small amounts of ankle joint rotation significantly affected tensile tendon force and aponeurosis and tendon displacement, respectively (P < 0.01). Plantarflexion moment was similar in runners (138 +/- 27 Nm, mean +/- SEM) and non-runners (142 +/- 17 Nm). Tendon moment arm was alike in non-runner (58.3 +/- 0.2 mm) and runners (55.1 +/- 0.1 mm). Similarly, there was no difference in tendon tensile force between runners (2633 +/- 465 N) and non-runners (2556 +/- 401 N). The cross-sectional area of the Achilles tendon was larger in runners (95 +/- 3 mm2) than non-runners (73 +/- 3 mm(2)) (P < 0.01). The load-deformation data yielded similar stiffness (runners 306 +/- 61 N/mm, non-runners 319 +/- 42 N/mm). The maximal strain and stress was 4.9 +/- 0.8% and 38.2 +/- 9.8 MPa in non-runners and 4.1 +/- 0.8% and 26.3 +/- 5.1 MPa in runners. The larger tendon cross-sectional area in trained runners suggests that chronic exposure to repetitive loading has resulted in a tissue adaptation.

Achilles Tendon↗
PubMed2000

Ultrasound evaluation of flexor tendon lacerations.

Thirteen injured digits in 10 patients (10 hands) with 20 potentially injured flexor tendons were preoperatively evaluated using real-time ultrasonography. The time interval between injury and ultrasonographic evaluation averaged 22 days. If a complete tendon laceration was found, the location of the proximal tendon stump was determined. Surgery was performed an average of 4 days after the ultrasonographic evaluation to determine the accuracy of the ultrasound study. Ultrasonography accurately identified the status of the flexor tendon in 11 of 13 digits and in 18 of 20 flexor tendons (12 intact, 2 partial lacerations, and 6 complete tendon lacerations). With complete tendon lacerations the location of the proximal tendon stump was accurately identified in 5 of 6 digits. There were 2 false ultrasound findings, including incorrectly identifying a 75% laceration in an intact index flexor and a complete tendon laceration in a 75% lacerated index finger flexor. Ultrasonography can help to evaluate the preoperative status of injured flexor tendons and, in cases of completely lacerated tendons, can help identify the location of the proximal tendon stump.

Adolescent↗
PubMedDate not supplied

[Standardized ultrasound diagnosis (13 MHz) of the tendon of the posterior tibial muscle--normal findings in probands with healthy feet].

OBJECTIVES: Tibialis posterior dysfunction is often diagnosed at a very late stage. However, the early diagnosis of tibialis posterior dysfunction is crucial for therapeutic aspects and especially for the operative prognosis. The morphological correlate of the tibialis posterior dysfunction consists of degenerative changes and thickening of the posterior tibial tendon [2, 9, 11]. By means of a high frequency linear array transducer, a standardized technique of examination as well as reference values of cross-sections of posterior tibial tendon are introduced. MATERIAL AND METHODS: Investigating 51 healthy subjects (102 feet) without any foot deformities, standardized planes were defined by use of a 13 MHz linear array transducer in order to delineate the posterior tibial tendon. At exact anatomic landmarks, tendon diameters were measured using two longitudinal sections proximal and distal to the medial malleolus. Likewise, two diameters and the resulting roughly calculated cross-section of the tendon were determined, using two transverse sections at the level of the subtalar joint facet and the medial malleolus. The findings obtained by ultrasound in four female patients with the diagnosis of a tibialis posterior dysfunction confirmed during surgery are compared to the aforementioned 51 healthy subjects. RESULTS: A healthy tendon appears homogeneous and echo-rich in orthogonal ultrasound and displays average areas of 18.4 sq.mm. (SD 5.9 sq.mm.) at the subtalar joint facet level and 19.2 sq.mm (SD 4.8 sq.mm.) at medial malleolus level in transverse sections. The corresponding areas obtained in patients with tibialis posterior dysfunction were clearly enlarged than in healthy subjects. In 85% of all feet examined at the level of the medial malleolus, the tendon is surrounded by a hypoechoic halo which has a size smaller than two times the cross-section of the flexor digitorum longus tendon. CONCLUSION AND CLINICAL RELEVANCE: Reference values of tendon thickness and of intratendinous echo-structures at reproducible landmarks facilitate delimitations from pathological tendon alterations. The exact delineation of intratendineal echoes by high frequency array transducers and standardized examination techniques that measure tendons size is a prerequisite to enable an early assessment and registration of degenerative alterations and thickening of the posterior tibial tendon.

Adolescent↗
PubMed1981

Effects of trauma and partial devascularization on protein synthesis in the avian flexor profundus tendon.

Destruction of the blood supply to tendons adversely affects healing of repaired flexor tendons. In cut and sutured avian flexor profundus tendons, protein synthesis was maximal on Day 10 post-trauma with a broad peak that spanned at least 12 days. Partial devascularization of cut-sutured tendons reduced protein synthesis to 43% of the value for nondevascularized-cut-sutured tendons on Day 10. Both collagen and noncollagen protein synthesis in cut-sutured tendons followed a bimodal pattern with peaks on postoperative Days 10 and 18. Collagen and noncollagen protein synthesis in partially devascularized tendons was decreased. Relative collagen synthesis, that is, the amount of collagen produced compared with the amount of all other proteins produced at the same time, was increased (Days 10 to 15) in the tendons that were cut-sutured and partially devascularized. The latter observations indicate that: 1) cutting a tendon results in increased protein synthesis; 2) partial devascularization of the cut tendon results in a lesser increase in protein synthesis; and 3) although overall protein synthesis, and collagen synthesis in particular, are reduced in partially devascularized, healing tendons, the relative amount of collagen produced is increased, emphasizing the importance of collagen to the healing tendon during the time of maximum synthesis.

Animals↗
PubMed2004

Flexor tendon wound healing in vitro: lactate up-regulation of TGF-beta expression and functional activity.

Flexor tendon wound healing in zone II is complicated by adhesions to the surrounding fibro-osseous sheath. These adhesions can significantly alter tendon gliding and ultimately hand function. Lactate and transforming growth factor-beta (TGF-beta) are two important mediators of wound healing that have been demonstrated to independently increase collagen production by cells of the tendon sheath, epitenon, and endotenon. This study examined the effects of lactate on TGF-beta peptide and receptor production by flexor tendon cells. Tendon sheath fibroblasts, epitenon tenocytes, and endotenon tenocytes were isolated from rabbit flexor tendons and cultured separately. Cell cultures were supplemented with 50 mM lactate, and the expression of three TGF-beta peptide isoforms (beta1, beta2, and beta3) and three receptor isoforms (R1, R2, and R3) was quantified with enzyme-linked immunosorbent assays. TGF-beta functional activity was also assessed with the addition of tendon cell conditioned media to mink lung epithelial cells transfected with a luciferase reporter gene expression construct responsive to TGF-beta. Supplementation of the cell culture medium with lactate significantly (p < 0.05) increased the expression of all TGF-beta peptide and receptor isoforms in all three cell lines. Tendon sheath fibroblasts exhibited the greatest increases in beta1 and beta2 peptide isoform expression (30 and 23 percent, respectively), whereas endotenon tenocytes demonstrated the greatest increase in beta3 peptide expression (32 percent). Epitenon tenocytes exhibited the greatest increases in receptor isoform R1 and R2 expression (17 and 19 percent, respectively). All three tendon cell types demonstrated significant (p < 0.05) increases in TGF-beta functional activity when exposed to lactate. Epitenon tenocytes demonstrated the greatest increase in activity (>4 times control values), whereas tendon sheath fibroblasts demonstrated the highest overall levels of total TGF-beta functional activity. Lactate significantly increased TGF-beta peptide (beta1, beta2, and beta3) expression, receptor (R1, R2, and R3) expression, and functional activity, suggesting a common pathway regulating tendon cell collagen production. Modulation of lactate and TGF-beta levels may provide a means of modulating the effects of TGF-beta on adhesion formation in flexor tendon wound healing.

Animals↗
PubMed2004

Full-thickness and partial-thickness supraspinatus tendon tears: value of US signs in diagnosis.

PURPOSE: To determine which US signs are important in the diagnosis of a surgically identifiable supraspinatus tendon tear. MATERIALS AND METHODS: Fifty consecutive ultrasonographic (US) studies of the shoulder in patients who underwent arthroscopic follow-up were retrospectively reviewed by a musculoskeletal radiologist. US images of the supraspinatus tendon were evaluated for tendon nonvisualization, abnormal tendon echogenicity, tendon thinning, greater tuberosity cortical irregularity, cartilage interface sign, joint fluid, and subacromial-subdeltoid bursal fluid. US findings were compared with arthroscopic results. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated for each US sign in the diagnosis of full-thickness tendon tear and again for any type of supraspinatus tendon tear. RESULTS: Arthroscopy revealed 21 full-thickness tears, five bursal surface partial-thickness tears, 10 articular surface partial-thickness tears, and 14 patients without tear of the supraspinatus tendon. The presence of greater tuberosity cortical irregularity and joint fluid was most important in the diagnosis of full-thickness supraspinatus tendon tear (sensitivity, 60%; specificity, 100%; positive predictive value, 100%; negative predictive value, 78%; accuracy, 84%). For diagnosis of any type of supraspinatus tendon tear (partial or full thickness), tendon nonvisualization, greater tuberosity cortical irregularity, and cartilage interface sign are most important, although a combination of signs did not improve accuracy. CONCLUSION: Secondary US signs, such as greater tuberosity cortical irregularity and joint fluid, are most valuable in the diagnosis of supraspinatus tendon tear.

Adult↗
PubMed2002

The blood supply of the posterior tibial tendon.

We studied the vascular pattern of human posterior tibial tendons by injection techniques and immunohistochemically using antibodies against laminin. The intravascular volume of the posterior tibial tendon was determined using a new method of injection of a solution of 99mTc and gelatin ink into the lower legs of cadavers. Three segments of 1 cm length from different regions of the human posterior tibial tendon were measured using a gamma well counter. The main blood supply arises from the posterior tibial artery. Blood vessels enter the paratenon of the posterior tibial tendon via a mesotenon from the posterior aspect. From the paratenon, the blood vessels penetrate the posterior tibial tendon and anastomose with a longitudinally orientated intratendinous network. The number of vessels in the substance of the tendon is consistently less than that in the surrounding paratenon. The distribution of blood vessels within the posterior tibial tendon is not homogeneous. In the retromalleolar region the intravascular volume was significantly reduced with a mean value of 15 microl/g of tendon tissue. There was no significant difference between the mean intravascular volumes of the proximal and distal areas (distal, 27.7 microl/g tendon tissue; proximal, 30 microl/g tendon tissue). The immunohistochemical investigation showed that there was no immunostaining for laminin in the anterior part of the tendon in the region where it passes behind the medial malleolus. This region is avascular. The most frequent site of rupture of the posterior tibial tendon is in the region behind the medial malleolus. A potential endogenous risk factor may be the limited healing potential of avascular tissue.

Aged↗
PubMed2005

Sonography of a rupture of the tendon of the extensor pollicis longus muscle: initial clinical experience and correlation with findings at cadaveric dissection.

OBJECTIVE: The objectives of our study were to report our initial clinical experience with sonography of the wrist for diagnosing a proximal rupture of the tendon of the extensor pollicis longus (EPL) muscle and to perform sonographic-anatomic correlation of the EPL tendon. MATERIALS AND METHODS: Clinical and imaging files of five patients who underwent sonography and subsequent open wrist surgery were reviewed retrospectively. Imaging was performed by four radiologists experienced in musculoskeletal sonography. Tendon retraction was evaluated on sonography and at surgery. In cadavers, sonography was performed in concert by two musculoskeletal radiologists during progressive stages of dissection of four embalmed specimens. One specimen was sliced in the transverse plane. RESULTS: In cadavers, the EPL tendon was located on or adjacent to Lister's tubercle and extended to the base of the thumb. The EPL tendon crossed over the extensor carpi radialis tendons where it exhibited a flattened aspect. In the five patients in the study, a tubular-shaped hypoechoic area was evident at the position of the ruptured EPL tendon on sonograms. At surgery, this area corresponded to fluid, hemorrhage, and scar tissue in the EPL tendon sheath. The assessment of tendon retraction on sonography correlated with findings at surgery. CONCLUSION: Sonography may aid in diagnosing a rupture of the EPL tendon and in the preoperative assessment of gap size and position of the retracted tendon ends. A characteristic tubular hypoechoic area may be seen crossing over the extensor carpi radialis tendons.

Aged↗
PubMed2005

[Clinical application of allogeneic tendon].

OBJECTIVE: To explore the clinical application of allogeneic tendon handled by ultra-deep-low-temperature. METHODS: From March 1995 to June 2002, tendons rupture and tendons defect were repaired by ultra-deep-low-temperature allogeneic tendon grafts in 96 cases, including 51 cases of flexor or extensor tendon defect of hand, 36 cases of coracoclavicular ligament rupture, 4 cases of cruciate ligament rupture, 2 cases of calcaneus tendon rupture and 3 cases of extensor tendon defect of foot. The interval between injury and operation was 1 day to 5 months. The length of defect was 4-12 cm with an average of 7 cm. The matching allogeneic tendons were selected during operation, and early function exercise was done after operation. Secondary release was performed in the cases of tendon adhesion. RESULTS: Follow-up time is from 6 months to 5 years (3.4 years on average). No rejection or rupture occurred after tendon allograft. The satisfactory result was achieved in 92.71% of the cases. CONCLUSION: The allogeneic tendon is similar to auto-tendon in transplanting, healing and function is useful clinically.

Adolescent↗
PubMed1991

The revascularization of healing flexor tendons in the digital sheath. A vascular injection study in dogs.

The role of revascularization in the nutritional support of repair of the flexor tendons is not completely understood. To explore the extent to which intrasynovial flexor tendons revascularize after transection and suture, a vascular injection study was carried out in a canine model. The tendons to the second and fifth digits of the forepaw in twelve adult mongrel dogs were transected and repaired. There were twenty-four experimental tendons and twenty-four normal tendons. The limb was placed in a polyurethane shoulder-spica cast, and the paw was treated with immediate protected passive mobilization. At three, seven, ten, seventeen, and twenty-eight days, the animals were killed and the major arteries supplying both the paw that had been operated on (left) and the contralateral normal paw (right) were injected with 200 milliliters of India ink. Segments of repaired and normal tendons were then clarified by a modified Spalteholz technique. The normal tendons demonstrated a well developed mesotenon that provided vascularization of the proximal portion of the flexor digitorum profundus tendon. A consistent three-cubic-millimeter avascular intrasynovial portion of tendon was noted. Distally, vessels arose from the vinculum breve, supplying the terminal twenty millimeters of tendon substance. In the experimental tendons, longitudinal and transverse clarified sections showed consistent revascularization of the site of repair by proximal vessels in the absence of ingrowth of peripheral adhesions. Vessels in the epitenon progressively extended for a distance of ten millimeters, through normally avascular regions, to reach the site of repair by the seventeenth postoperative day. Intratendinous vessels about the site of repair consistently originated from surface vessels, rather than from extensions of pre-existing intratendinous vessels. New vessels penetrated all areas, including the normally avascular volar segments of tendon, irrespective of previous topical zones of avascularity. Proximal vascular plexi were characterized by large tortuous vessels with frequent circuitous branches. More distal vessels had a longitudinally oriented, feathery appearance.

Animals↗