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At least 973 records · Page 54Linked to original sources
PubMed1998

Influence of sensor size on the accuracy of in-vivo ligament and tendon force measurements.

In-vivo tendon forces are commonly measured using transducers, which detect tension in the tendon fibers. A poorly understood source of measurement errors is the difference in stress distribution within the tendon between experimental and transducer calibration conditions. The objective of this study was to investigate this source of error, and to determine whether these errors could be minimized by proper selection of transducer size. The study was conducted using the infrapatellar ligament (patellar tendon) of New Zealand White rabbits. Tendon force was measured with two different size implantable force transducers (IFTs), one Wide and one Narrow, and by a strain gaged load cell in series with the tendon. Tests were conducted at five different loading conditions selected to produce five different stress distributions within the tendon. One loading condition corresponded to a typical post-experiment calibration, and the data from that condition were used to develop a calibration equation for the transducer. The errors that resulted from using this calibration were determined by comparing the tendon force measured by the in-series load cell with the force predicted from the IFT output using the calibration equation. Changes in stress distribution produced measurement errors up to 64 N with the Narrow IFT but only 24 N with the Wide IFT. We found the measurement error was dependent on sensor width. Our results support the hypothesis that measurement errors can be caused by differences in tendon stress distribution between calibration and experimental conditions. We further showed that these errors can be minimized by using an IFT, which samples the tension in a large percentage of the tendon fibers. Information from this study can be used for selection of an appropriately sized implantable force transducer for measuring tendon and ligament force.

Animals↗
PubMed1999

Sonographic incidence of tendon microtears in athletes with chronic Achilles tendinosis.

OBJECTIVE: To assess the number and distribution of tendon microtears in asymptomatic controls and athletes with chronic Achilles tendinitis or partial thickness tears using high resolution ultrasound. METHODS: The mean number of microtears in three random tendon cross sections were recorded per tendon third in 19 asymptomatic volunteers, 16 athletes with symptomatic chronic Achilles tendinitis, and eight athletes with partial Achilles tendon rupture. RESULTS: Microtears were most numerous in the middle third section of the Achilles tendon. Some 67% of tendons in the control group had no microtears, and 28% showed a single microtear. Only 18% of the athletes with chronic Achilles tendinitis and none of the athletes with partial tendon rupture were without microtears in the middle third of their Achilles tendon. Of the tendons with chronic tendinitis, 13% had more than three microtears per section which increased to 87% in tendons exhibiting partial rupture. CONCLUSIONS: There appears to be an association between microtear formation and Achilles tendon rupture.

Achilles Tendon↗
PubMed1991

Frog semitendinosis tendon load-strain and stress-strain properties during passive loading.

The mechanical properties of the frog semitendinosis (ST) tendon, bone-tendon junction, and aponeurosis were measured during passive loading to a tension equal to maximum isometric tension (Po). Stiffness and strain in these regions continuously increased as load increased. Tendon stiffness was approximately four times the aponeurosis stiffness. Tendon Young's modulus at Po was only 188 MPa, which is approximately 10 times less than the modulus reported for most mammalian tendons. Similarly, tendon stress at Po was only approximately 3 MPa, which is also less than that predicted for many tendons. Tendon strain at Po was approximately 2% after passive loading. We conclude that different regions of the frog ST tendon have different mechanical properties and that the frog ST tendon operates physiologically in the "toe" region of the stress-strain curve with a variable stiffness that increases with load. Taken together, these results have significant implications in understanding muscle-tendon design and neuromotor control strategies.

Animals↗
PubMed2005

Elastic properties of human Achilles tendon are correlated to muscle strength.

The purpose of this study was to investigate whether the mechanical properties of the Achilles tendon were correlated to muscle strength in the triceps surae in humans. Twenty-four men and twelve women exerted maximal voluntary isometric plantar flexion (MVIP) torque. The elongation (DeltaX) and strain of the Achilles tendon (epsilon), the proximal part of which is the composite of the gastrocnemius tendon and the soleus aponeurosis, at MVIP were determined from the displacement of the distal myotendinous junction of the medial gastrocnemius using ultrasonography. The Achilles tendon force at MVIP (F) was calculated from the MVIP torque and the Achilles tendon moment arm. There were no significant differences in either the F-DeltaX or F-epsilon relationships between men and women. DeltaX and epsilon were 9.8 +/- 2.6 mm and 5.3 +/- 1.6%, respectively, and were positively correlated to F (r = 0.39, P < 0.05; r = 0.39, P < 0.05), which meant that subjects with greater muscle strength could store more elastic energy in the tendon. The regression y-intercepts for the F-DeltaX (P < 0.01) and F-epsilon (P < 0.05) relationship were significantly positive. These results might indicate that the Achilles tendon was stiffer in subjects with greater muscle strength, which may play a role in reducing the probability of tendon strain injuries. It was suggested that the Achilles tendon of subjects with greater muscle strength did not impair the potential for storing elastic energy in tendons and may be able to deliver the greater force supplied from a stronger muscle more efficiently. Furthermore, the difference in the Achilles tendon mechanical properties between men and women seemed to be correlated to the difference in muscle strength rather than gender.

Adult↗
PubMed1975

Tendon organs of cat medial gastrocnemius: responses to active and passive forces as a function of muscle length.

The responses of 13 Golgi tendon organs to graded force development of 29 motor units in medial gastrocnemius of the cat have been studied in five experiments. Of the 13 tendon organs, 11 were responsive to passive stretch within the physiological range of muscle length and 5 were "spontaneously" active at very short lengths where no passive tension could be recorded. The relationship between passive force and the firing rates of the various afferents ranged from a linear one to a power relation (Y = Axb + c) with b, a widely varying exponent. Results support the general conclusion that although many Ib afferents respond to passive force within the physiological range of muscle stretch, this form of stimulus is not a particularly effective one. The statis responses of Golgi tendon organs to active force development produced by single motor units was studied at different muscle lengths. In all cases the apparent sensitivity (change in firing rate per active force developed) decreased as muscle length approached Lo. The static responses of Golgi tendon organs to force developed by single motor units were also studied during fatiguing contractions. The data suggest a sigmoid relationship between force developed at the tendon and the Ib response. The collective response of all 13 tendon organs to active and passive forces at different muscle lengths was also examined. This analysis offered further support for the viewpoint that active motor unit contractions provide themost significant excitatory input to tendon organs and that changes in passive force during muscle stretch have comparatively little effect on the collective tendon organ response. The interaction between active and passive force inputs to the Golgi tendon organs is discussed in relation to the complicated nature of the relationship between forces measured at the tendon and those acting within the receptor capsule. When these complications were taken into account it was possible to explain the differences in responsiveness of a given tendon organ to active contraction of several motor units and to passive force in terms of a single force-firing rate curve for the receptor. It is concluded that changes in the force of contraction of single motor units result in relatively small changes in Ib afferent firing and that during normal muscle contractions, changes in the number of motor units acting on a single receptor must produce far more significant changes in firing rate than changes in the amount of force developed by any single unit. Changes in dynamic Ib sensitivity to single motor unit contractions are also shown to depend on length and in a similar way to the changes in static Ib sensitivity. During fatiguing contractions, a sigmoid relation was found between the dynamic Ib response and the rate of force development by single motor units.

Animals↗
PubMed1995

Proprioceptive consequences of tendon vibration during movement.

1. Previous studies have used tendon vibration to investigate kinesthetic illusions in the isometric limb and end point control in the moving limb. These previous studies have shown that vibration distorts the perceptions of static joint angle and movement and causes systematic errors in the end point of movement. In this paper we describe the effects of tendon vibration during movement while human subjects performed a proprioceptively coordinated motor task. In an earlier study we showed that the CNS coordinates this motor task-a movement sequence-with proprioceptive information related to the dynamic position and velocity of the limb. 2. When performing this movement sequence, each subject sat at a table and opened the right hand as the right elbow was passively rotated in the extension direction through a prescribed target angle. Vision of the arm was prevented, and the movement velocity was changed randomly from trial to trial, leaving proprioception as the only useful source of kinematic information with which to perform the task. 3. In randomly occurring trials, vibration was applied to the tendon of the biceps brachii, a muscle that lengthens during elbow extension. In some experiments the timing of tendon vibration was varied with respect to the onset of elbow rotation, and in other experiments the frequency of vibration was varied. In each experiment we compared the accuracy of the subject's response (i.e., the elbow angle at which the subject opened the hand) in trials with tendon vibration with the accuracy in trials without tendon vibration. 4. The effect of tendon vibration depended on the frequency of vibration. When the biceps tendon was vibrated at 20 Hz, subjects opened the hand after the elbow passed through the target angle ("overshooting"). Overshooting is consistent with an underestimate of the actual displacement or velocity of the elbow. Vibration at 30 Hz had little or no effect on the elbow angle at hand opening. Vibration at 40 Hz caused subjects to open the hand before the elbow reached the target angle ("undershooting"). Undershooting is consistent with an overestimate of the actual displacement or velocity of the elbow. The size of the error depended on the velocity of the passively imposed elbow rotation. 5. The effect of tendon vibration also depended on the timing of vibration. If 40-Hz vibration began at the onset of movement, the subject undershot the target. If 40-Hz vibration started 5 s before movement onset and continued throughout the movement, the undershoot error increased in magnitude. However, if 40-Hz vibration started 5 s before movement onset and then stopped at movement onset, the subject overshot the target. When vibration was shut off during movement, a transition occurred from an over-shooting error to an undershooting error at a time that depended on the velocity of elbow rotation. 6. In a separate experiment, subjects were instructed to match either the perceived dynamic position or the perceived velocity of rotation imposed on the right elbow by actively rotating the left elbow. In both matching tasks, tendon vibration produced oppositely directed errors depending on the frequency of vibration. Vibration at 20 Hz produced a perception of decreased elbow velocity and a bias in dynamic position in the flexion direction, and vibration at 40 Hz produced the opposite perceptions. 7. We conclude that muscle spindle afferents, which are activated by tendon vibration, are an important source of the dynamic position and velocity information that the CNS uses to coordinate this movement sequence task. The observed effects of vibration timing and frequency suggest that perceptual changes evoked by vibration cannot be explained by the simple summation of sensory input evoked by movement and by vibration. Rather, the bias in perception produced by vibration appears to be related to the difference between vibration- and movement-evoked activity in muscle spindle afferents.

Adult↗
PubMedDate not supplied

Ultrasonographic and power Doppler evaluation of the patellar tendon ten years after harvesting its central third for reconstruction of the anterior cruciate ligament: comparison of patients without or with anterior knee pain.

BACKGROUND: The long-term morphologic changes in the patellar tendon after harvesting its central third for the reconstruction of the anterior cruciate ligament have not been reported. HYPOTHESIS: Sonographic morphologic changes in the harvested patellar tendon are common 10 years after the harvesting procedure. STUDY DESIGN: Retrospective cohort study. METHODS: Thirty-one patients who had undergone an anterior cruciate ligament reconstruction using central-third bone-patellar tendon-bone autograft with a closure of the patellar tendon defect were included in this study. An ultrasonographic and Power Doppler examination was performed at a mean follow-up of 10 years. RESULTS: Ultrasonography of the harvested patellar tendon showed intratendinous calcification in 9 patients, hypoechoic lesion in 20 patients, hyperechoic lesion in 1 patient, and peritendinous changes in 1 patient. Only 3 (9.7%) of the 31 patients had no changes in the harvested patellar tendon. No abnormality was visible in the contralateral (normal) patellar tendons of the 31 patients. The harvested patellar tendon was significantly thicker than the contralateral patellar tendon (P < 0.05). CONCLUSIONS: Sonographic morphologic changes of the patellar tendon were common 10 years after the harvesting procedure, although no evidence of inflammatory process, as could be seen in Power Doppler flow, was found inside of any patellar tendon.

Adolescent↗
PubMedDate not supplied

The role of recreational sport activity in Achilles tendon rupture. A clinical, pathoanatomical, and sociological study of 292 cases.

During the last few decades, the incidence of tendon ruptures has increased in civilized countries. Our material comprises 749 patients who had 832 tendon ruptures treated surgically between 1972 and 1985. There were no competitive athletes among the patients studied. There were 292 single ruptures of the Achilles tendon, 274 of the proximal biceps brachii, 113 of the extensor pollicis longus, and 70 of other tendons. Forty-eight patients had multiple ruptures and 35 patients had reruptures. Achilles tendon ruptures often occurred in recreational sports activities (59%), in contrast to other tendon ruptures (2%; P less than 0.001). The mean age for patients who had Achilles tendon rupture was 35.2 years and for patients with other ruptures, 50.7 years (P less than 0.001). There was a connection between the high incidence of blood group O and tendon ruptures (P less than 0.001). In cases of multiple ruptures and reruptures, the frequency of blood group O was 71%. Sixty-two point three percent of the patients with Achilles tendon rupture were professionals or white collar workers, which is markedly more than in the Hungarian population (12.7%; P less than 0.001). Two hundred and six Achilles tendon ruptures were studied histologically, and all cases displayed pathological alterations. The results indicate that complete rupture of the Achilles tendon is usually a sequel to a sedentary life-style and participation in sports activities.

Achilles Tendon↗
PubMedDate not supplied

Anatomic considerations in harvesting the semitendinosus and gracilis tendons and a technique of harvest.

Although the semitendinosus and gracilis tendons have long been used in ligamentous reconstruction procedures of the knee, their anatomic relationships have not been explicitly detailed. Therefore, cadaveric dissections were performed on fresh-frozen adult knees to examine these relationships. Several key anatomic points are useful in the harvest of these tendons. Their conjoined insertion site is medial and distal to the tibial tubercle. They become distinct structures at a point that is farther medial and slightly proximal. Tendon harvest is facilitated by identifying the tendons proximal to this point. The superficial medial collateral ligament lies deep to the tendons in this area and should not be disturbed. The tendons are ensheathed in a dense fascial layer that may impede tendon stripping. The accessory insertion of the semitendinosus tendon (which was present in 77% of the knees dissected) should be identified and transected to avoid tendon damage at harvest. Knee flexion may reduce the risk of injury to the saphenous nerve as it crosses the gracilis tendon. Variation in tendon diameter affects graft strength.

Adult↗
PubMed2000

The development of fatigue quality in high- and low-stressed tendons of sheep (Ovis aries).

The time taken to rupture in cyclic fatigue tests, to a stress of 45 MPa, was used to compare the fatigue quality of tendons from sheep of varying ages. Muscle and tendon cross-sectional areas were used to calculate the stress-in-life of each tendon. For any given age, high-stressed plantaris tendons were of a higher fatigue quality than low-stressed extensor tendons. Both fatigue quality and stress-in-life increased with age for each tendon type. High-stressed tendons are subjected to large increases in stress-in-life during growth, and fatigue quality increased significantly with this stress. This relationship was not seen, however, in low-stressed tendons, which are not subjected to a comparable range of stresses over time. It is possible that cells modify tendon fatigue quality in response to tendon loading history. Whilst Young's modulus was seen to increase with age, no difference was detected between high- and low-stressed tendons.

Aging↗
PubMed2004

Immunohistochemical characterization of cells in adult human patellar tendons.

Cells in tendons are conventionally identified as elongated tenocytes and ovoid tenoblasts, but specific markers for these cells are not available. The roles and interplay of these cells in tendon growth, remodeling, and healing are not well established. Therefore, we proposed to characterize these cells with respect to cell turnover, extracellular matrix metabolism, and expression of growth factors. Here we examined 14 healthy human patellar tendon samples for the expression of various proteins in tenocytes and tenoblasts, which were identified as elongated tendon cells and ovoid tendon cells, respectively. Matrix metalloproteinase 1 (MMP1), procollagen type I (procol I), heat shock protein 47 (hsp47), bone morphogenetic protein 12 (BMP12), 13 (BMP13), and transforming growth factor beta1 (TGFbeta1) were detected by immunohistochemistry (IHC). An image analysis of the IHC staining for proliferation cell nuclear antigen (PCNA) and apoptotic cells was performed to determine the proliferation index and the apoptosis index in elongated and ovoid tendon cells. The ovoid tendon cells expressed higher levels of procol I, hsp47, MMP1, BMP12, BMP13, and TGFbeta1 than the elongated tendon cells. Both the proliferation index and the apoptosis index of ovoid tendon cells were higher than those of the elongated tendon cells. The results suggested that ovoid tendon cells, conventionally recognized as tenoblasts, were more active in matrix remodeling. The expression of BMP 12, BMP13 and TGFbeta1 might be associated with the different cellular activities of tenoblasts and tenocytes.

Adolescent↗
PubMed2004

The effects of intratendinous and retrocalcaneal intrabursal injections of corticosteroid on the biomechanical properties of rabbit Achilles tendons.

BACKGROUND: The use of corticosteroid injections in the treatment of retrocalcaneal bursitis is controversial. We assessed the effects of corticosteroid injections, both within the tendon substance and into the retrocalcaneal bursa, on the biomechanical properties of rabbit Achilles tendons. The systemic effects of bilateral corticosteroid injections were also studied. METHODS: The rabbits were divided into three treatment groups. The rabbits in Group I received injections of corticosteroid into the Achilles tendon on the left side and injections of normal saline solution into the Achilles tendon on the right, those in Group II received injections of corticosteroid into the retrocalcaneal bursa on the left side and injections of saline solution into the Achilles tendon on the right, and those in Group III received injections of corticosteroid into the Achilles tendon on the left side and injections of corticosteroid into the retrocalcaneal bursa on the right. These injections were given weekly for three weeks. At four weeks after the final injection, the tendons were harvested and were tested biomechanically to determine failure load, midsubstance strain and total strain, modulus of elasticity, failure stress, and total energy absorbed. The site of failure was also documented. The groups were compared according to the location of the injections, the type of injection (steroid or saline solution), and the total systemic load of steroid. RESULTS: Specimens from limbs that had received intratendinous injections of corticosteroid showed significantly decreased failure stress compared with those from limbs that had received intratendinous injections of saline solution (p = 0.008). Specimens from limbs that had received intrabursal injections of corticosteroid demonstrated significantly decreased failure stress (p = 0.05), significantly decreased total energy absorbed (p = 0.017), and significantly increased total strain (p = 0.049) compared with specimens from limbs that had received intratendinous injections of saline solution. Specimens from limbs that had received intratendinous injections of corticosteroid were biomechanically equivalent to specimens from limbs that had received intrabursal injections of corticosteroid. Specimens from rabbits that had received bilateral injections of corticosteroid demonstrated significantly decreased failure load (p = 0.011), modulus of elasticity (p = 0.015), failure stress (p = 0.03), and total energy absorbed (p = 0.015) compared with those from rabbits that had received unilateral injections of steroid. CONCLUSIONS: Local injections of corticosteroid, both within the tendon substance and into the retrocalcaneal bursa, adversely affected the biomechanical properties of rabbit Achilles tendons. Additionally, tendons from rabbits that had received bilateral injections of corticosteroid demonstrated an additive adverse effect, with significantly worse biomechanical properties compared with tendons from rabbits that had received unilateral injections of corticosteroid.

Achilles Tendon↗
PubMed2005

Ultrasound diagnosis of peroneal tendon tears. A surgical correlation.

BACKGROUND: Musculoskeletal ultrasound is an established diagnostic technique for the assessment of tendon injuries. The purpose of the present study was to determine whether ultrasound is effective for evaluating peroneal tendon injuries, with surgical findings used as the standard of reference. METHODS: Fifty-eight patients with a suspected peroneal tendon injury were prospectively evaluated with use of dynamic ultrasound. Twenty-five patients were found to have peroneal tendon tears and were managed operatively. Five patients with normal peroneal tendons on ultrasound examination also were managed operatively for other reasons and are included in the series as the peroneal tendons were inspected at the time of the procedure. Ultrasound and surgical criteria were used to grade the peroneal tendons on a scale from grade 0 (normal tendon) to grade III (tendon rupture). RESULTS: Of the sixty tendons that were evaluated operatively, twenty-five were found to be torn. The sensitivity, specificity, and accuracy of ultrasonography were 100%, 85%, and 90%, respectively. CONCLUSIONS: The use of dynamic ultrasound is effective for determining the presence or absence of a peroneal tendon tear and should be considered a first-line diagnostic tool.

Adolescent↗
PubMed1988

The functional characteristics of tendon blood circulation in the rabbit hindlimbs.

Neurohormonal, mechanical, and muscle exercise effects on tendon blood flow were studied in thirty-five rabbits. After anesthesia by urethane, experiments were performed on in situ preparation of the hindlimb under stable state in systemic blood pressure. Tendon and muscle blood flow were measured simultaneously by the hydrogen gas clearance method, and their temperature and PO2 were continuously observed by thermocouple and oxygen sensor, respectively. The resting blood flow in the denervated tendon tibialis anterior, gastrocnemius, and soleus (ml/(100 g.min] was 39.0 +/- 4.0, 34.5 +/- 8.2, and 30.2 +/- 4.3, respectively, whereas in their muscles it was 17.8 +/- 1.5, 17.1 +/- 2.1, and 12.6 +/- 1.1, respectively. The tendon tissue temperature and PO2 increased gradually until 15-20 min after cutting the sciatic nerve, and the increasing rate depended upon the initial control level before denervation. Intravenous injection of noradrenaline in the dose of 1-9.9 micrograms/kg produced a marked decrease in the tendon tissue temperature of the tibialis anterior, but a mild one in the muscle. The longitudinal tension force produced a decrease in the tendon tissue temperature of the tibialis anterior, but no change in the muscle. During muscle exercise, tendon blood flow and temperature tended to decrease, whereas the muscle blood flow and temperature increased markedly from the beginning of muscle exercise. There was no evidence to demonstrate the existence of exercise hyperemia in the tendon tissue. These data suggest that tendon blood circulation can be modified by many factors, and that mechanical and exercise effects may play a role in regulation of tendon blood flow channels and fluid transfer for the lubrication of tendon fiber movements.

Animals↗
PubMed1996

Flexor tendon tears in the hand: use of MR imaging to diagnose degree of injury in a cadaver model.

OBJECTIVE: Treatment of flexor tendon lacerations of the finger partly depends on the degree of injury, which is difficult to determine clinically. We used a cadaver model to investigate the potential of MR imaging in evaluating these injuries. MATERIALS AND METHODS: A scalpel was drawn transversely across the volar surface of four cadaver hands, producing various flexor tendon injuries. MR imaging of each hand was performed using axial two-dimensional spin-echo and three-dimensional gradient-recalled-echo sequences. The three-dimensional data sets were interactively reformatted along the long axis of each tendon. The hands were then dissected; injury to each digit was categorized, measured, and compared with the prospective MR interpretations. RESULTS: Twelve high-grade flexor tendon tears (10 complete tears, with 1- to 14-mm separation of the torn ends, and two partial tears involving 50% or more of the total tendon cross-sectional area) and two partial tears of less than 50% of tendon area were produced; four tendons were not injured. Using MR imaging, we diagnosed 11 of the 12 high-grade lesions (those involving at least 50% of the total tendon cross-sectional area); the MR images did not show one complete tear whose separation measured 2 mm long at dissection. All intact tendons were correctly identified. We underestimated the extent of five lesions but overestimated none. Using the reformatted images, we reduced the number of errors that we would have made interpreting the transverse images alone. CONCLUSION: In this cadaver model, using MR imaging we accurately distinguished different degrees of flexor tendon tears. The potential of this technique for noninvasively diagnosing flexor tendon injury in patients awaits clinical studies.

Cadaver↗
PubMed1998

Comparison of surgically attached and non-attached repair of the rat Achilles tendon-bone interface. Cellular organization and type X collagen expression.

The effects of surgical repair versus non-repair on cell morphology and type X collagen expression were investigated using a rat model of Achilles tendon avulsion. The animals were divided into four groups. In Group 1, tendon was reattached to the original attachment site by suturing through a drill hole in the calcaneus; in Group II, tendon was not reattached and a drill hole was not made; in Group III, tendon was not reattached but a drill hole was made; and the animals in Group IV were sham operated. In Group I (tendon reattached), at 2 weeks postoperatively, many hypertrophic chondrocytes appeared at the reattachment site adjacent to bone and type X collagen was detected immunologically both in the cells and in the extracellular matrix. After 4 weeks, the cells at the original site of attachment were arranged in rows along the newly formed tendon fibers and were stained with type X collagen antibody. By contrast, when tendon was not reattached (Groups II and III), a gap between the original attachment site and the tendon stump was observed through the entire postoperative period. At 8 weeks, the original attachment site was covered by fibrocartilaginous tissue and tendon became attached to the calcaneal fibrocartilage area, which is proximal to the original attachment site. Type X collagen was detected in the cells which were adjacent to bone. In Group IV (sham operation), there were no changes in histology or type X collagen distribution, either at the attachment site or in tendon and bone, compared with the non-operated control rats. These results suggest that surgical reattachment of tendon to the original site is important to help reorganize cells during the repair process. Type X collagen was identified immunohistochemically in the cells adjacent to bone in all the groups, suggesting that it may play a role in maintaining distinct areas of calcified and non-calcified fibrocartilage.

Achilles Tendon↗
PubMed1997

Diagnostic efficacy of ultrasonography in stage I posterior tibial tendon dysfunction: sonographic-surgical correlation.

The purpose of this study is to evaluate the diagnostic efficacy of ultrasonography in stage I posterior tibial tendon dysfunction. Fourteen of the 17 consecutive patients who underwent tenosynovectomy for stage I posterior tibial tendon dysfunction were included in this study. The preoperative diagnosis was based primarily on the clinical suspicion of dysfunction, which was confirmed by ultrasonography. Two measurements were obtained at the midpoint between the insertion site and the medial malleolus in both feet of the 14 patients: the diameter of the posterior tibial tendon and the diameter of the tendon sheath measured from its inner walls. The mean diameter of the tendon was 4.61 +/- 0.50 mm and that of the tendon sheath in the symptomatic foot was 7.24 +/- 0.75. In the unaffected foot, the mean diameter of the tendon was 3.30 +/- 0.34 mm and that of the tendon sheath was 3.64 +/- 0.35 mm, respectively. In the symptomatic tendon, the increase of peritendinous space was significantly higher than the increase in the tendinous portion (P < 0.0001). Surgical findings proved the accuracy of diagnosis in all patients. Although many cases of stage I posterior tibial tendon dysfunction remain undiagnosed owing to the mild clinical symptoms, this series indicates that ultrasonography is a valuable adjunctive diagnostic tool in the clinical examination and assists in achieving an accurate diagnosis of stage I posterior tibial tendon dysfunction, allowing early treatment.

Adult↗
PubMed2006

Sonographic measurement of achilles tendons in asymptomatic subjects: variation with age, body height, and dominance of ankle.

OBJECTIVE: This study was undertaken to evaluate the thickness, cross-sectional area, and length of Achilles tendons in asymptomatic subjects of different age groups and heights and between dominant and nondominant ankles. METHODS: High-resolution sonographic examinations of Achilles tendons were performed in 40 healthy subjects (14 men and 26 women). The subjects were categorized into 4 age groups: (1) 20 to 29 years, (2) 30 to 39 years, (3) 40 to 49 years, and (4) 50 years or older. The thickness, cross-sectional area, and length of the Achilles tendons of both ankles were measured. All Achilles tendons were measured with the ankle in a relaxed, neutral position. RESULTS: There was no significant difference in the thickness and length of Achilles tendons among subjects of different age groups (P>.05). The Achilles tendon cross-sectional area of subjects 50 years or older was significantly larger than that of subjects in the younger age groups (P<.05). There was a positive correlation between the height of the subjects and the length, thickness, and cross-sectional area of the Achilles tendons; however, the correlation coefficient was low (r=0.07-0.28; P>.05). Dominance of ankles did not affect the thickness and length of the Achilles tendons, whereas the cross-sectional area of the tendons was significantly larger in the dominant ankles (P<.05). CONCLUSIONS: Sonography is a useful imaging tool in the evaluation of Achilles tendons. Normal variations of the tendon morphologic characteristics should be considered in the clinical diagnosis.

Achilles Tendon↗