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PubMed2006

Expression of insulin-like growth factor I, insulin-like growth factor binding proteins, and collagen mRNA in mechanically loaded plantaris tendon.

Insulin-like growth factor I (IGF-I) is known to exert an anabolic effect on tendon fibroblast production of collagen. IGF-I's regulation is complex and involves six different IGF binding proteins (IGFBPs). Of these, IGFBP-4 and -5 could potentially influence the effect of IGF-I in the tendon because they both are produced in fibroblast; however, the response of IGFBP-4 and -5 to mechanical loading and their role in IGF-I regulation in tendinous tissue are unknown. A splice variant of IGF-I, mechano-growth factor (MGF) is upregulated and known to be important for adaptation in loaded muscle. However, it is not known whether MGF is expressed and upregulated in mechanically loaded tendon. This study examined the effect of mechanical load on tendon collagen mRNA in relation to changes in the IGF-I systems mRNA expression. Data were collected at 2, 4, 8 and 16 days after surgical removal of synergistic muscle to the plantaris muscle of the rat, thus increasing the load to plantaris muscle and tendon. Nearly a doubling of the tendon mass was observed after 16 days of loading. A rapid rise in tendon procollagen III mRNA was seen after 2 days whereas the increase in procollagen I mRNA was significant from day 8. MGF was expressed and upregulated in loaded tendon tissue with a faster response than IGF-I, which was increased from day 8. Finally, IGFBP-4 mRNA was increased with a time pattern similar to procollagen III, whereas IGFBP-5 decreased at day 8. In conclusion, loading of tendon tissue results in an upregulation of IGF-I, IGFBP-4, and procollagen and is associated with an increase in tendon mass. Also, MGF is expressed with an early upregulation in loaded tendon tissue. We suggest that the IGF-I system could be involved in collagen synthesis in tendon in response to mechanical loading.

Animals↗
PubMed2005

Influence of 90-day simulated microgravity on human tendon mechanical properties and the effect of resistive countermeasures.

While microgravity exposure is known to cause deterioration of skeletal muscle performance, little is known regarding its effect on tendon structure and function. Hence, the aims of this study were to investigate the effects of simulated microgravity on the mechanical properties of human tendon and to assess the effectiveness of resistive countermeasures in preventing any detrimental effects. Eighteen men (aged 25-45 yr) underwent 90 days of bed rest: nine performed resistive exercise during this period (BREx group), and nine underwent bed rest only (BR group). Calf-raise and leg-press exercises were performed every third day using a gravity-independent flywheel device. Isometric plantar flexion contractions were performed by using a custom-built dynamometer, and ultrasound imaging was used to determine the tensile deformation of the gastrocnemius tendon during contraction. In the BR group, tendon stiffness estimated from the gradient of the tendon force-deformation relation decreased by 58% (preintervention: 124 +/- 67 N/mm; postintervention: 52 +/- 28 N/mm; P < 0.01), and the tendon Young's modulus decreased by 57% postintervention (P < 0.01). In the BREx group, tendon stiffness decreased by 37% (preintervention: 136 +/- 66 N/mm; postintervention: 86 +/- 47 N/mm; P < 0.01), and the tendon Young's modulus decreased by 38% postintervention (P < 0.01). The relative decline in tendon stiffness and Young's modulus was significantly (P < 0.01) greater in the BR group compared with the BREx group. Unloading decreased gastrocnemius tendon stiffness due to a change in tendon material properties, and, although the exercise countermeasures did attenuate these effects, they did not completely prevent them. It is suggested that the total loading volume was not sufficient to completely prevent alterations in tendon mechanical properties.

Adaptation, Physiological↗
PubMed1997

Connections between the tendons of the musculus flexor digitorum profundus involving the synovial sheaths in the carpal tunnel.

In the carpal tunnel anatomical interconnections between the tendons of the musculus flexor digitorum profundus are systematically present. These interconnections limit the mutual tendon displacements, which decreases finger independence and may be problematic in a musician's hand. The present study investigates a possible role of the synovial sheaths in the formation of these intertendinous connections in the carpal tunnel. To this end a morphological model is provided which correlates the often distinctly fibrous structure of the deep flexor tendons in the carpal tunnel and the frequent exchange of tendon fibres between the tendons to the different fingers, with the tendency of the synovial membranes to strongly adhere to the tendons. This model is validated by gross dissection results, and by cross sections of the flexor tendons in the carpal tunnel. In agreement with the model, the anatomic data show that the synovial membranes tend to invade and become trapped in tendons made up from individualised tendon strands, and also strongly adhere to the substantial amounts of tendon fibres which may be exchanged between the flexor tendons proximal to the lumbrical origins. These fibres and the synovial membranes may form a strong fabric able to withstand substantial stretching forces of interconnected oppositely pulled flexor tendons.

Adult↗
PubMedDate not supplied

Graft incorporation within the tibial bone tunnel after anterior cruciate ligament reconstruction with bone-patellar tendon-bone autograft.

We described histologic changes in patellar tendon autografts that occur over time within the tibial tunnel in specimens harvested from patients undergoing revision anterior cruciate ligament reconstruction. Ten patients, averaging 21.2 years of age, were divided into two groups based on the time period between their original and revision surgery: early revision (less than 1 year, four patients) and late revision (more than 1 year, six patients). Among the early revision group, the tendon within the tunnel showed increased cellularity and random collagen bundles. A specimen from the shortest early revision case revealed a normal original bone-tendon junction, whereas others showed an obscured structure. Between the tendon and the tunnel wall, granulation tissue was seen and the bone-tendon junction was still immature. In the late revision group, the tendon appeared similar to normal ligament. The original bone-tendon junction was not seen, and the tendon continued completely to the tunnel wall with Sharpey-like fibers. Observations in the early revision group suggest that tendon remodeling and bone-tendon integration continue for at least several months after transplantation. The original bone-tendon junction appears to have shifted to the proximal patellar tendon-tunnel wall junction with time. These findings are in agreement with prior animal studies.

Adolescent↗
PubMed2006

Ultrasonographic investigation of the Achilles tendon in elite badminton players using color Doppler.

BACKGROUND: The most frequent injuries in badminton players are in the lower extremities, especially in the Achilles tendon. HYPOTHESIS: The game of badminton may be related to abnormal intratendinous flow in the Achilles tendon as detected by color Doppler ultrasound. To a certain extent, this blood flow might be physiological, especially when examined after match. STUDY DESIGN: Cohort study (prevalence); Level of evidence, 3. METHODS: Seventy-two elite badminton players were interviewed regarding Achilles tendon pain (achillodynia) in the preceding 3 years. Color Doppler was used to examine the tendons of 64 players before their matches and 46 players after their matches. Intratendinous color Doppler flow was graded from 0 to 4. The Achilles tendon was divided into dominant (eg, right side for right-handed players and vice versa) and nondominant side and classified as midtendon, preinsertional, and calcaneal areas. RESULTS: Of 72 players, 26 had experienced achillodynia in 34 tendons, 18 on the dominant side and 16 on the nondominant side. In 62% of the players with achillodynia, the problems had begun slowly, and the median duration of symptoms was 4 months (range, 0-36 months). Thirty-five percent had ongoing pain in their tendons for a median duration of 12 months (range, 0-12 months). Achillodynia was not associated with the self-reported training load or with sex, age, weight, singles or doubles players, or racket side. Forty-six players were scanned before and after match. At baseline, color Doppler flow was present in the majority of players, and only 7 (16%) players had no color Doppler flow in either tendon. After match, all players had some color Doppler flow in 1 or both tendons. Achillodynia and color Doppler flow were related in the nondominant Achilles tendon (chi-square, P = .008). The grades of Doppler flow also increased significantly after match in the preinsertional area in both the nondominant (P = .0002) and dominant (P = .005) side tendons. CONCLUSION: A large proportion of the players had experienced achillodynia and habitually played with a degree of pain that demanded medication. The self-reported pain was associated with increased intratendinous color Doppler flow in the nondominant Achilles tendon. Doppler flow was found in most players before and in all players after the match and therefore may in part be a physiological response to activity.

Achilles Tendon↗
PubMed2004

The accessory extensor tendon of the first metatarsophalangeal joint.

The accessory extensor tendon of the first metatarsophalangeal joint (1st MTPJ) was evaluated in 32 cadaver feet. Eighty-one percent of feet possessed an accessory tendon to the 1st MTPJ. Of those feet possessing an accessory tendon to the 1st MTPJ, approximately 92% originated from the extensor hallucis longus muscle-tendon unit, while approximately 8% originated from the tibialis anterior muscle-tendon unit. All accessory tendons inserted onto the dorsal/dorsomedial capsule of the 1st MTPJ. Accessory tendons were found to be bilateral in the majority (87.5%) of specimens. Differences in sex distribution of the accessory tendon of the 1st MTPJ were not statistically significant. The difference in distribution of an accessory tendon to the 1st MTPJ in those feet that demonstrated clinical hallux valgus versus those that did not demonstrate hallux valgus was not statistically significant (p = 1.0000, respectively, Fisher's exact test). This tendon is unique to the human foot (lacking in primates) and is a fairly constant structure (80%). The data presented do not lend support for the accessory tendon of the 1st MTPJ to play a role in the development of hallux valgus. At the present time, the role of this accessory tendon on the biomechanics of the 1st MTPJ remains unknown.

Cadaver↗
PubMed2006

Suture holding capacity of the Achilles tendon during the healing period: an in vivo experimental study in rabbits.

BACKGROUND: Early motion and weightbearing is known to promote the healing of Achilles tendon repair. It is important to be informed about the repair strength for a secure rehabilitation. There are reports about the initial repair strength of Achilles tendons; however, they are mainly in vitro studies that represent the time zero strength of the repair. Softening of the tendon observed during the biological process of the tendon healing, which may effect the suture holding capacity and in turn the repair strength of the tendon has not been evaluated before. METHODS: In the current study, the suture holding capacity of rabbit Achilles tendon was observed at various times during the healing period. RESULTS: The suture holding capacity of the tendon at the end of the first and third weeks after surgery was found to be similar within 30% of the control tendon. However, at the end of the fourth week it was doubled reaching 65% of the control tendon. CONCLUSIONS: Intrinsic tendon insufficiency which causes a decrease in the suture holding capacity of the tendon may lead to pull-out of the suture material during the postoperative third week. This period is precarious for early motion and weightbearing since the suture holding capacity of the tendon doubled relative to the previous three weeks.

Achilles Tendon↗
PubMed1992

Microvascular anatomy of the peroneal tendons.

The etiology of longitudinal splitting of the peroneus brevis tendon is unclear. It has been hypothesized that compressive load applied to the tendon as it passes through the fibular groove may compromise the vascularity of the tendon with resultant inhibition of the repair response and degeneration of tendon structure. To investigate this possibility, a study of the microvascularity of the peroneal tendons was undertaken. Twelve fresh, frozen cadaveric limbs were injected with India ink. The vascularity of the peroneal tendons was examined in situ and the tendons were harvested and cleared using a modified Spalteholz technique. The vascularity of the cleared tendons was evaluated utilizing a dissecting microscope. The vascular supply of the peroneal tendons arises from two posterolateral vincula, one for the peroneus longus tendon and one for the peroneus brevis tendon. These vincula are supplied by branches of the posterior peroneal artery. A zone of hypovascularity within the peroneus brevis or peroneus longus tendon correlating with the site of peroneus brevis splits was not found. There was no relationship between increasing age of specimens and alteration in vascular supply.

Adolescent↗
PubMed1997

The effect of exercise-induced localised hyperthermia on tendon cell survival.

Tendons that store energy during locomotion, such as the equine superficial digital flexor tendon (SDFT) and human Achilles tendon, suffer a high incidence of central core degeneration which is thought to precede tendon rupture. Although energy storage contributes to the efficiency of locomotion, tendons are not perfectly elastic and some energy is lost in the form of heat. Recent studies have shown that the central core of equine SDFT reaches temperatures as high as 45 degrees C during high-speed locomotion. In this study, we test the hypothesis that hyperthermia causes tendon cell death and results in tendon central core degeneration. Tendon fibroblasts cultured from the core of the equine SDFT were subjected to a temperature of 45 degrees C in an in vitro system for 0-180 min, and cell survival fraction was measured and compared with that for equine dermal fibroblasts and a commercial rat kidney fibroblast cell line (NRK 49F). Tendon fibroblasts were significantly more resistant to hyperthermia than NRK 49F cells after 30, 45 and 60 min of heating and significantly more resistant than dermal fibroblasts after 45 and 60 min of heating. After 10 min of heating at 45 degrees C, the tendon fibroblast cell survival fraction was 91 +/- 4%, whereas heating for 10 min at 48 degrees C resulted in a drop in the cell survival fraction to 22 +/- 4%. In conclusion, while temperatures experienced in the central core of the SDFT in vivo are unlikely to result in tendon cell death, repeated hyperthermic insults may compromise cell metabolism of matrix components, resulting in tendon central core degeneration.

Animals↗
PubMed1999

High-resolution MR imaging of the asymptomatic Achilles tendon: new observations.

OBJECTIVE: Our aim was to describe the normal appearance of the Achilles tendon and peritendinous tissues in asymptomatic active volunteers using high-resolution MR imaging. MATERIALS AND METHODS: One hundred clinically asymptomatic Achilles tendons were imaged at 1.5 T with axial high-resolution T1-weighted gradient-echo (fast low-angle shot [FLASH]) and short inversion time inversion recovery (STIR) sequences. The tendons, peritendinous tissues, tendon insertions, and musculotendinous junctions were separately evaluated by two observers. RESULTS: The average anteroposterior diameter (+/-SD) of the asymptomatic Achilles tendons was 5.2+/-0.73 mm. The anterior margin was flat or concave in all, except for 10 tendons that showed mild convexity. A wave-like bulge, which shifted from lateral to medial in the craniocaudal direction, was detected in the anterior margin of 56 tendons. The signal intensity was heterogeneous in 45 tendons. In these tendons, distal stripes or punctate foci were seen. A small (3 mm) intermediate intensity intratendinous region thought to represent tendon degeneration was detected in four cases on FLASH images. The retrocalcaneal bursae contained a prominent fluid collection in 15 cases. The paratenon was visualized in all cases on both FLASH and STIR images. CONCLUSION: High-resolution MR imaging depicts the Achilles tendon and peritendinous soft tissues in great detail. The normal anatomy of the asymptomatic Achilles tendon is variable. We postulate that the variability may be a potential source of diagnostic misinterpretation.

Achilles Tendon↗
PubMed2004

Dynamic sonographic evaluation of peroneal tendon subluxation.

OBJECTIVE: Peroneal tendon subluxation is a major cause of posttraumatic lateral ankle pain. Because peroneal subluxation often occurs only when the foot is dorsiflexed and everted, findings on static imaging studies may appear to be normal. We therefore evaluated the effectiveness of sonography in revealing peroneal tendon subluxation in patients performing stress maneuvers. MATERIALS AND METHODS: From June 2001 to June 2003, 13 consecutive patients (10 females and three males; mean age, 30.4 years; age range, 16-66 years) in whom peroneal tendon subluxation was clinically suspected were scanned with a high-frequency linear array transducer by an experienced sonologist. The ankles in 10 asymptomatic volunteers were also scanned. Sequential axial and longitudinal sonograms of the peroneus longus and peroneus brevis tendons at rest were obtained and evaluated for tendinitis and tendon tears. Real-time axial sonograms were then obtained while the foot was dorsiflexed and everted. Of the 13 patients, 12 had sonographic findings of peroneal tendon subluxation and underwent surgical exploration. The sonographic and surgical reports of these 12 patients were compared. RESULTS: All 12 patients with sonographic findings of peroneal tendon subluxation were subsequently found to have subluxation at surgery. The positive predictive value of dynamic sonography for peroneal tendon subluxation was therefore 100%. Sonography revealed peroneus brevis tendon tears in five patients and a peroneus longus tear in one; all findings were confirmed at surgery, with no false-positive sonograms. Only four of the 20 asymptomatic ankles showed subluxation, and none had any other tendon abnormalities. CONCLUSION: Sonography is an effective technique for diagnosing peroneal tendon subluxation, as well as associated tears of the peroneal tendons.

Adolescent↗
PubMed2004

Determination of passive mechanical properties of the superficial and deep digital flexor muscle-ligament-tendon complexes in the forelimbs of horses.

OBJECTIVE: To determine the relative contributions of the muscles, tendons, and accessory ligaments to the passive force-length properties of the superficial (SDF) and deep digital flexor (DDF) myotendinous complexes. SAMPLE POPULATION: 8 cadaveric forelimbs from 6 adult Thoroughbreds. PROCEDURE: In vitro, limb configurations during slack position and myotendinous lengths during subsequent axial loading of forelimbs were recorded before and after transection of accessory ligaments. Expressions were derived to describe the force-length behavior of each muscle, tendon, and accessory ligament-tendon unit; linear stiffness was computed for these components. The elastic modulus was established for the SDF and DDF tendons. RESULTS; Linear stiffness was 2.80 +/- 0.38 kN/cm for the SDF muscle, 3.47 +/- 0.66 kN/cm for the DDF muscle, 2.73 +/- 0.18 kN/cm for the SDF tendon, 3.22 +/- 0.20 kN/cm for the DDF tendon, 6.46 +/- 0.85 kN/cm for the SDF accessory ligament, 1.93 +/- 0.11 kN/cm for the SDF accessory ligament-tendon unit, and 2.47 +/- 0.11 kN/cm for the DDF accessory ligament-tendon unit. The elastic modulus for the SDF and DDF tendons was 920 +/- 77 and 843 +/- 56 MPa, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Both the muscle-tendon and ligament-tendon portions of SDF and DDF myotendinous complexes had important roles in supporting the forelimb of horses. Although muscle tension can be enhanced by elbow joint flexion and active contraction, the accessory ligaments transmitted more force to the distal tendons than did the muscles under the conditions tested.

Animals↗
PubMed2001

Magnetic resonance imaging after operative repair of achilles tendon rupture.

We performed a magnetic resonance imaging (MRI) study in 16 consecutive patients who had undergone open repair of a unilateral Achilles tendon rupture (ATR) at an average of 32.5 (SD 3.2) (range 29-36) months from the operation. We measured the widest antero-posterior diameter of the tendon, the longest distance between the insertion of the Achilles tendon on the calcaneum and the musculo-tendinous junction of the soleus muscle on the Achilles tendon, the distance between the insertion of the Achilles tendon on the calcaneum and the point of maximal width of the tendon. We also ascertained whether areas of altered signal were present in and around the tendon. The operated tendons were always significantly thicker than the non-operated ones. There was a non-significant trend for the other measurements to be greater in the operated tendons. In five patients, areas of dishomogeneous signal were present in the operated tendon. These areas were less than 25% of the antero-posterior diameter of the tendon, and were clinically silent. These findings probably represent normal features of long-term tendon healing following open repair of an ATR.

Achilles Tendon↗
PubMed1992

Force- and moment-generating capacity of lower-extremity muscles before and after tendon lengthening.

A computer model of the human lower extremity was developed to study how surgical lengthening of tendon affects the force- and moment-generating capacity of the muscles. This model computes the maximum isometric force and the resulting joint moments that each muscle-tendon complex can develop at any body position. Tendon lengthenings were simulated by increasing the tendon length of each muscle-tendon complex and computing the change in the maximum isometric muscle force and joint moments at a specific body position. These simulations showed that the forces and moments developed by the ankle plantarflexors are extremely sensitive to changes in tendon length. For example, at a body position corresponding to the midstance phase of gait, the maximum isometric moment generated by soleus decreased 30% with a 1-cm increase in tendon length, and 85% with a 2-cm increase in tendon length. In contrast, 1- and 2-cm increases in iliopsoas tendon length decreased its hip flexion moment by only 4% and 9%, respectively. This article quantifies the sensitivity of muscle force and joint moments to changes in tendon length for the most commonly lengthened lower-extremity tendons. These results indicate how much each of these tendons should be lengthened to achieve an incremental decrease in muscle force or joint moment.

Ankle Joint↗
PubMed2004

Comparison of mechanical properties of rat tibialis anterior tendon evaluated using two different approaches.

Tendon injuries may result in variations of its mechanical properties. The published data of the tendon stiffness of small animals, such as mouse and rat, are exclusively obtained by measuring grip-to-grip (g-t-g) displacement. Local strain concentration and relative sliding of the specimens in the clamps might significantly affect the measured tendon deformation. In the present study, the mechanical properties of the rat tibialis anterior tendon measured using the proposed tendon mark method were compared to those evaluated using the g-t-g displacement method. Five male Sprague Dawley rats ( approximately 418 g) were used in this study. For the proposed method, reference marks were made on the tendons using permanent ink. A microscope video system was customized to observe and record the tendon deformation. Pattern recognition software was developed to obtain the displacement time-histories of the reference marks. The distance between the grips was approximately 7 mm; and the distance between the reference marks used for the data processing was approximately 5 mm. The cross-section areas of the specimens were measured using a custom-made slot gauge and by applying a constant compressive stress (0.15 MPa). The tendons were clamped between two custom-made metal grips and stretched on a testing machine at a constant speed (1 mm/s) up to failure. Throughout the tests, the tendon specimens were submerged in a PBS bath at 22 degrees C. The deformation of the specimens was evaluated using the g-t-g displacement method and the proposed method. The stress/strain curves obtained by using the g-t-g displacement can be characterized by an initial toe zone, a quasi-linear zone, and a final failure stage. The stress/strain curves determined using the proposed method are quite different from those obtained using the g-t-g displacement: it has a smaller toe zone and a stress-hardening transition, over which the tendon stiffness increases dramatically with the increasing strain. The tendon stiffness measured by using the g-t-g displacement method may underestimate the actual mechanical properties of tendon by approximately 43%.

Animals↗
PubMed2005

[The clinical application and biomechanical study of reconstruction of anterior and posterior cruciate ligament with hamstring tendons knot implant fixation].

OBJECTIVE: To investigate the feasibility of reconstruction of anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) with hamstring tendons knot implant fixation. METHODS: Fifty-two cases of ACL and PCL old injury were reconstructed under the arthroscopy with double bundles hamstring tendons knot implant fixated in the bottle-necked femoral tunnel. The tibia side were fixated by tendon weave suture cross tied a knot at the bone bridge of tibia. In this group reconstruction of ACL was in 25, PCL and ACL at the same time reconstruction in 15, PCL in 12. The failure test and displacement evaluation were used to study the biomechanics of reconstruction of ACL by hamstring tendon knot implant fixation (n = 13) in porcine knees. The control group were reconstructed with bone-patellar tendon-bone B-PT-B and interference screw (n = 11). The tibia side tendon weave suture immobility by cross tied a knot at the tibia bone bridge (n = 7) and interference screw in the tibia tunnel (n = 8). RESULTS: Forty-nine cases were followed up, average 14.6 months. The results of Lanchman test was negative in 46 cases, positive in 3 cases. Preoperative Lysholm score was 56.7, and postoperative was 92.8. According to the knee joint effective evaluate standard, 46 were excellent and 3 good. The maximal pull-out force of hamstring tendons knot implanted fixation had been greater than B-PT-B fixation by interference screw. There were similar displacement in 100 N and 400 N load between hamstring tendons knot implant fixation and B-PT-B (P > 0.05). Peak force test maximal displacement evaluation and failure energy absorption measurement showed that hamstring tendons knot implant fixation was significantly greater than B-PT-B (P < 0.01). The failure test and displacement evaluation of tendon fixation by weave suture knot at the tibia bone bridge cross tie were greater than B-PT-B fixation by interference screw. CONCLUSION: The methods of reconstruct of ACL and PCL by hamstring tendons knot implant fixation are feasible. The advantages include: it is biological fixation, not machine fixation; it may benefit for tendons with bone tunnel healing and decrease medical cost. Decreasing or eliminating displacement is helpful to prevent relaxation after reconstruction of ACL and PCL.

Animals↗
PubMed2005

Comparison of tenoscopic and ultrasonographic methods of examination of the digital flexor tendon sheath in horses.

The purpose of this study was to compare sonographic and tenoscopic findings with the purpose of establishing the accuracy and limitations of ultrasonograophy as a non-invasive diagnostic modality in evaluating the DFTS and its enclosed tendons. The medical records from 22 horses which underwent tenoscopic desmotomy of the palmar/plantar annular ligament were evaluated in a retrospective study. The qualitative assessment of sonogrophic and tenoscopic findings were documented for the digital flexor tendon sheath (DFTS), the palmar/plantar annular ligament (PAL), the superficial digital flexor tendon (SDFT) and the deep digital flexor tendon (DDFT). The abnormalities diagnosed sonographically within the DFTS were verifiable tenoscopically with a sensitivity of 90.9% and a specificity of 53.8%. The positive predictive value of sonographic examination at the DFTS was 62.5%. The sensitivity of the sonographic examination at the PAL was 68.8%, the specificity was 50% and the positive predictive value 73.3%. Sonographic examination of the SDF tendons revealed abnormal findings in 12 tendons. The tenoscopic examination confirmed these findings on six tendons when they had a pronounced fibrillated or rough tendon surface or tear on the border. Six superficial flexor tendons and seven deep digital flexor tendons had abnormalities seen tenoscopically which were not visible on sonographic examination. Sonographic examination located lesions of the DDFT in four limbs. On tenoscopic examination the lesions could be detected in seven other DDF tendons, including signs of inflammation at the tendon surface that were not seen ultrasonographically (sensitivity 36.4%). Recognition of the limitations of sonographic results should be kept in mind so as not to misinterpret findings, especially if echogenic materials are observed.

Animals↗
PubMed1988

[Functional properties of the Golgi tendon organs].

Golgi tendon organs are encapsulated mechanoreceptors present at the myo-tendinous and myo-aponeurotic junctions of mammalian skeletal muscles. Within the tendon organ capsule, the terminal branches of a large diameter afferent fibre, called Ib fibre, are intertwined with collagen bundles in continuity with tendon or aponeurosis at one end. The other end is connected with a fascicle of 5-25 muscle fibres, contributed by several motor units. The contraction of these fibres, exerting strain on the collagenous bundle and causing deformation of sensory terminals, is the adequate stimulus of the tendon organ. For this stimulus, the tendon organ has a very low threshold, so that a single fibre twitch can elicit a discharge from the receptor. A tendon organ can thus signal the contraction of a single one of the 10-15 motor units which contribute fibres to the fascicle connected with the receptor. The number of tendon organs present in a muscle, taken together with the fact that a given motor unit can activate several tendon organs, strongly suggests that the contraction of every motor unit in this muscle is monitored by at least one tendon organ. The exact nature of the information provided by tendon organs to the central nervous system remains an open question because no simple relation could be established between the discharge frequency of a receptor and the contractile forces of its activating motor units. It is known, however, that, due to their dynamic sensitivity, tendon organs are efficient in signaling rapid variations of contractile force. The dynamic parameters of muscle contraction prevail in the information carried by afferent discharges from tendons organs.

Afferent Pathways↗