Achilles Tendon Length Research Articles

Ultrasonographic Evaluation for the Effect of Extracorporeal Shock Wave Therapy on Gastrocnemius Muscle Spasticity in Patients With Chronic Stroke.

Extracorporeal shock wave therapy (ESWT) has been suggested as a useful treatment for spasticity in patients with stroke. To date, most studies have used clinical or biomechanical assessments to determine the effects of treatment. To assess the effect of a single session of ESWT through ultrasonographic assessment on spasticity in patients with chronic stroke. Randomized controlled trial. Rehabilitation center. Eighteen patients with chronic stroke. Participants were randomly assigned to an ESWT group (n = 9) or control group (n = 9). In the ESWT group, a single session of ESWT was given in the medial head of the gastrocnemius muscle of the spastic side at 4 Hz, 2000 shots with intensity of stimulation using energy of 0.1 mJ/mm2 . Sham stimulation was provided by only making sound without putting the device into contact with the skin in the control group. The clinical trial registration number of this study is KCT0002582. Participants were evaluated prior to the treatment, 30 minutes, 1 week, and 4 weeks after treatment. Clinical measures included Modified Ashworth Scale (MAS), passive range of motion (PROM), and Fugl-Meyer Assessment (FMA). As the primary outcome measure, the ultrasonographic measures were Achilles tendon length (ATL), muscle fascicle length (MFL), muscle thickness (MT), and pennation angle (PA). There were no significant differences between the 2 groups for any demographic or baseline measures. At all follow-up evaluations, improvement was shown in MAS as well as changes from baseline of ultrasonographic measures in the ESWT group compared to the control group. In the case of ultrasonographic measures, the difference between the group was greatest at 4 weeks. At follow-up of 4 weeks, between-group difference was 0.66 points (P = .04) on MAS scores, 5.45 points (P = .004) on ATL scores, 4.95 points (P = .002) on MFL scores, 1.83 points (P < .001) on MT scores, and 3.73 points (P < .001) on PA scores. Some ultrasonographic measures of spasticity as well as MAS were improved after a single session of ESWT. Future studies with larger numbers of subjects compared with other spasticity metrics are necessary to further evaluate the treatment effect of ESWT. II.

Impaired mechanical properties of Achilles tendon in spastic stroke survivors: an observational study

ABSTRACTBackground: The spasticity could lead to decreased functional capacity and changes in musculoskeletal tissue.Objective: To compare the Achilles tendon properties between the affected and contralateral limbs of participants with spasticity due to stroke and the healthy subjects.Methods: Fifteen individuals with ankle spasticity due to stroke and 15 healthy subjects were recruited. Maximal isometric ankle joint torque was obtained with an isokinetic dynamometer, and an ultrasound was used to determine tendon length, tendon cross-sectional area, and the medial gastrocnemius myotendinous junction displacement. The Achilles tendon strength, displacement, stress, strain, stiffness, and Young’s modulus were obtained during a maximum voluntary isometric plantarflexion contraction.Results: There were no differences between Achilles tendon length among participants. Both limbs of participants with stroke showed reduced tendon cross-sectional area (~18%) compared to healthy limb. The affected limb showed decreased tendon strength (686 ± 293.3 N), displacement (10.6 ± 1.7 mm), Young’s modulus values (849 ± 235.6 MPa), and lower stiffness (196.6 ± 67.6 N/mm) compared to the contralateral limb (strength, 1357.1 ± 294.8 N; displacement, 15.2 ± 5.5 mm; Young’s modulus, 1431.8 ± 301.9 MPa; stiffness, 337.5 ± 98.1 N/mm) and to the healthy limb. The contralateral limb also showed decreased tendon strength (~26.2%) and stiffness (~21.5%) compared to the healthy group.Conclusion: There is a decrement in Achilles tendon morphological and mechanical properties of the affected limb in individuals with spasticity due to stroke. The contralateral limb had a thinner tendon more compliant likely to physical activity reduction.

Correlations between muscle-tendon parameters and acceleration ability in 20 m sprints.

In this study we investigated the relationships between muscle-tendon parameters and average/peak values of velocity, force and power in sprint running focusing on the acceleration phase. Eighteen male sprinters (100 m PB: 10.66±0.51 s) participated to the study. Instantaneous values of horizontal velocity (v) were recorded by means of a radar and instantaneous values of force (F) and power (P) were calculated based on these data. Muscle thickness, fascicle length and pennation angle of knee extensors and plantar flexors, as well as Achilles tendon length and CSA, were measured by means of ultrasonography. In the first 20 m of the sprint average and peak speed were 6.31±0.59 and 8.88±0.98 m·s-1, respectively; force was highest at the start of the sprint (Fpeak = 10.02±1.43 N·kg-1) and power peaked about 1 s after the start (26.64±5.99 W·kg-1). Muscle-tendon parameters showed stronger correlations with peak values of power (R range: 0.81–0.92), force (R range: 0.56–0.84) and speed (R range: 0.53–0.85) than with average values of velocity over the 20 m distance (R range: 0.41–0.61) (R <0.47 = NS; R >0.71 = P < .001). These data underline that the influence of muscle tendon parameters on sprint performance could be better appreciated when peak values of power can be calculated rather than by considering the simple measure of average velocity (e.g. distance/time).

Extended field of view ultrasound imaging to evaluate Achilles tendon length and thickness: a reliability and validity study

Extended field of view ultrasound imaging to evaluate Achilles tendon length and thickness: a reliability and validity study

Changes in Achilles tendon stiffness and energy cost following a prolonged run in trained distance runners.

During prolonged running, the magnitude of Achilles tendon (AT) length change may increase, resulting in increased tendon strain energy return with each step. AT elongation might also affect the magnitude of triceps surae (TS) muscle shortening and shortening velocity, requiring greater activation and increased muscle energy cost. Therefore, we aimed to quantify the tendon strain energy return and muscle energy cost necessary to allow energy storage to occur prior to and following prolonged running. 14 trained male (n = 10) and female (n = 4) distance runners (24±4 years, 1.72±0.09 m, 61±10 kg, 64.6±5.8 ml•kg-1•min-1) ran 90 minutes (RUN) at approximately 85% of lactate threshold speed (sLT). Prior to and following RUN, AT stiffness and running energy cost (Erun) at 85% sLT were determined. AT energy return was calculated from AT stiffness, measured with dynamometry and ultrasound and estimated TS force during stance. TS energy cost was estimated on the basis of AT force and assumed crossbridge mechanics and energetics. Following RUN, AT stiffness was reduced from 328±172 N•mm-1 to 299±148 N•mm-1 (p = 0.022). Erun increased from 4.56±0.32 J•kg-1•m-1 to 4.62±0.32 J•kg-1•m-1 (p = 0.049). Estimated AT energy return was not different following RUN (p = 0.99). Estimated TS muscle energy cost increased significantly by 11.8±12.3 J•stride-1, (p = 0.0034), accounting for much of the post-RUN increase in Erun (8.6±14.5 J•stride-1,r2 = 0.31). These results demonstrate that a prolonged, submaximal run can reduce AT stiffness and increase Erun in trained runners, and that the elevated TS energy cost contributes substantially to the elevated Erun.

Effects of high loading by eccentric triceps surae training on Achilles tendon properties in humans.

To document the magnitude and time course of human Achilles tendon adaptations (i.e. changes in tendon morphological and mechanical properties) during a 12-week high-load plantar flexion training program. Ultrasound was used to determine Achilles tendon cross-sectional area (CSA), length and elongation as a function of plantar flexion torque during voluntary plantar flexion. Tendon force-elongation and stress-strain relationships were determined before the start of training (pre-training) and after 4 (post-4), 8 (post-8) and 12 (post-12) training weeks. At the end of the training program, maximum isometric force had increased by 49% and tendon CSA by 17%, but tendon length, maximal tendon elongation and maximal strain were unchanged. Hence, tendon stiffness had increased by 82%, and so had Young's modulus, by 86%. Significant changes were first detected at post-4 in stiffness (51% increase) and Young's modulus (87% increase), and at post-8 in CSA (15% increase). Achilles tendon material properties already improved after 4weeks of high-load training: stiffness increased while CSA remained unchanged. Tendon hypertrophy (increased CSA) was observed after 8 training weeks and contributed to a further increase in Achilles tendon stiffness, but tendon stiffness increases were mostly caused by adaptations in tissue properties.

Muscle and tendon morphology alterations in children and adolescents with mild forms of spastic cerebral palsy

BackgroundEarly detection of changes at the muscular level before a contracture develops is important to gain knowledge about the development of deformities in individuals with spasticity. However, little information is available about muscle morphology in children with spastic diplegic cerebral palsy (CP) without contracture or equinus gait. Therefore, the aim of this study was to compare the gastrocnemius medialis (GM) and Achilles tendon architecture of children and adolescents with spastic CP without contracture or equinus gait to that of typically developing (TD) children.MethodsTwo-dimensional ultrasonography was used to assess the morphological properties of the GM muscle and Achilles tendon in 10 children with spastic diplegic CP (Gross Motor Function Classification System level I–II) and 12 TD children (mean age 12.0 (2.8) and 11.3 (2.5) years, respectively). The children with CP were not restricted in the performance of daily tasks, and therefore had a high functional capacity. Mean muscle and tendon parameters were statistically compared (independent t-tests or Mann-Whitney U-tests).ResultsWhen normalized to lower leg length, muscle-tendon unit length and GM muscle belly length were found to be significantly shorter (p < 0.05, effect size (ES) = 1.00 and 0.98, respectively) in the children with spastic CP. Furthermore, there was a tendency for increased Achilles tendon length when expressed as a percentage of muscle-tendon unit length (p = 0.08, ES = − 0.80) in the individuals with CP. This group also showed shorter muscle fascicles (3.4 cm vs. 4.4 cm, p < 0.01, ES = 1.12) and increased fascicle pennation angle (21.9° vs. 18.1°, p < 0.01, ES = − 1.36, respectively). However, muscle thickness and Achilles tendon cross-sectional area did not differ between groups. Resting ankle joint angle was significantly more plantar flexed (− 26.2° vs. − 20.8°, p < 0.05, ES = 1.06) in the children with CP.ConclusionsMorphological alterations of the plantar flexor muscle-tendon unit are also present in children and adolescents with mild forms of spastic CP. These alterations may contribute to functional deficits such as muscle weakness, and therefore have to be considered in the clinical decision-making process, as well as in the selection of therapeutic interventions.

Relationship Between Running Economy and Achilles Tendon Length.

Relationship Between Running Economy and Achilles Tendon Length.

Ultrasound estimates of Achilles tendon exhibit unexpected shortening during ankle plantarflexion

The purpose of this study was to investigate Achilles tendon (AT) length changes during a series of tasks that involved combinations of higher/lower force, and larger/smaller length changes of the medial gastrocnemius muscle-tendon unit (MTU). We sought to determine if common ultrasound-based estimates of AT length change were consistent with expectations for a passive elastic tendon acting in series with a muscle. We tested 8 healthy individuals during restricted joint calf contractions (high force, low displacement), ankle dorsi-/plantar-flexion (DF/PF) with the foot in the air (low force, high displacement), and heel raises (high force, high displacement). We experimentally estimated AT length change using two ultrasound methods, one based on muscle-tendon junction (MTJ) tracking and one based on muscle fascicle (MF) tracking. Estimates of AT length change were consistent with model expectations during restricted calf contractions, when the MTU underwent minimal length change. However, estimates of AT length changes were inconsistent with model expectations during the ankle DF/PF and heel raise tasks. Specifically, the AT was estimated to shorten substantially, often 10–20 mm, when the ankle plantarflexed beyond neutral position, despite loading conditions in which a passive, stiff spring would be expected to either lengthen (under increasing force) or maintain its length (under low force). These unexpected findings suggest the need for improvements in how we conceptually model and/or experimentally estimate MTU dynamics in vivo during motion analysis studies, particularly when the ankle plantarflexes beyond neutral.

Altered Achilles tendon function during walking in people with diabetic neuropathy: implications for metabolic energy saving.

The Achilles tendon (AT) has the capacity to store and release elastic energy during walking, contributing to metabolic energy savings. In diabetes patients, it is hypothesized that a stiffer Achilles tendon may reduce the capacity for energy saving through this mechanism, thereby contributing to an increased metabolic cost of walking (CoW). The aim of this study was to investigate the effects of diabetes and diabetic peripheral neuropathy (DPN) on the Achilles tendon and plantarflexor muscle-tendon unit behavior during walking. Twenty-three nondiabetic controls (Ctrl); 20 diabetic patients without peripheral neuropathy (DM), and 13 patients with moderate/severe DPN underwent gait analysis using a motion analysis system, force plates, and ultrasound measurements of the gastrocnemius muscle, using a muscle model to determine Achilles tendon and muscle-tendon length changes. During walking, the DM and particularly the DPN group displayed significantly less Achilles tendon elongation (Ctrl: 1.81; DM: 1.66; and DPN: 1.54 cm), higher tendon stiffness (Ctrl: 210; DM: 231; and DPN: 240 N/mm), and higher tendon hysteresis (Ctrl: 18; DM: 21; and DPN: 24%) compared with controls. The muscle fascicles of the gastrocnemius underwent very small length changes in all groups during walking (~0.43 cm), with the smallest length changes in the DPN group. Achilles tendon forces were significantly lower in the diabetes groups compared with controls (Ctrl: 2666; DM: 2609; and DPN: 2150 N). The results strongly point toward the reduced energy saving capacity of the Achilles tendon during walking in diabetes patients as an important factor contributing to the increased metabolic CoW in these patients. NEW & NOTEWORTHY From measurements taken during walking we observed that the Achilles tendon in people with diabetes and particularly people with diabetic peripheral neuropathy was stiffer, was less elongated, and was subject to lower forces compared with controls without diabetes. These altered properties of the Achilles tendon in people with diabetes reduce the tendon's energy saving capacity and contribute toward the higher metabolic energy cost of walking in these patients.

Gastrocnemius fascicle and achilles tendon length at the end of the eccentric phase in a single and multiple countermovement hop

The purpose of this investigation was to compare fascicle and tendon length of the gastrocnemius at the end of the eccentric phase during a hop utilizing a single countermovement (sCM) versus multiple countermovement (mCM1, mCM2, mCM3) strategy. Seventeen healthy males performed nine hopping trials of sCM and nine trials of mCM. Ankle and knee joint angle and lower leg length from videography and muscle ultrasound were used to calculate muscle-tendon unit (MTU), fascicle and tendon length. Sacral marker data was used to determine hopping height. Force- and displacement-time curves were utilized to calculate work. Muscle activity of the lateral and medial gastrocnemius was also measured. Fascicle length was significantly shorter (mCM3: 6.2 ± 1.5 cm, sCM: 7.3 ± 2.0 cm) and tendon length was significantly longer (mCM3: 36.5 ± 3.6 cm, sCM: 35.5 ± 3.8 cm) at the end of the eccentric phase in mCM3 in comparison to sCM. Maximal hopping height (mCM: 14.6 ± 3.1 cm, sCM: 13.1 ± 2.5 cm), eccentric phase gastrocnemius muscle activity (mCM medial gastrocnemius: 0.10 ± 0.03 mV, mCM lateral gastrocnemius: 0.08 ± 0.04 mV, sCM medial gastrocnemius: 0.07 ± 0.03 mV, sCM lateral gastrocnemius: 0.05 ± 0.04 mV), and both eccentric (mCM3: 46.6 ± 19.4 J, sCM: 38.5 ± 15.9 J) and concentric work (mCM3: 87.6 ± 26.5 J, sCM: 80.9 ± 27.6 J) were significantly higher for mCM3 compared to sCM. The results indicate that a multiple countermovement hop strategy results in shorter fascicle length and longer tendon length at the end of the eccentric phase. In addition, greater eccentric phase muscle activity during the third countermovement (mCM3) in comparison to a single countermovement hop (sCM) was observed. A multiple countermovement strategy appears to result in higher hopping height and greater work done in both the eccentric and concentric phase indicating possible contribution of stored-elastic energy from the tendon.

Achilles Tendon Resting Angle Relates to Tendon Length and Function.

Following Achilles tendon rupture, tendon elongation leads to long term deficits in calf function. A surrogate measure of Achilles tendon length, Achilles tendon resting angle (ATRA), has been described but has not been validated against length measured using ultrasound. Therefore, the purpose of this study was to validate the ATRA against ultrasound. Secondarily, this study aimed to identify the relationship of other factors (tendon mechanical properties, heel-rise test performance) to the ATRA. Individuals following unilateral Achilles tendon rupture were included. ATRA was measured in knee flexed and extended positions. Tendon elongation was measured using extended field of view ultrasound imaging. Continuous shear wave elastography quantified tendon mechanical properties. The relationship between variables was tested using Spearman's ρ. Subgroup analysis was used to compare subjects with less then or greater than 1 year following rupture. A total of 42 participants (with a mean of 18.2 months following rupture [SD = 35.9]) were included. Tendon elongation related with relative ATRA with knee flexed (ρ = .491, P = .001) and knee extended (ρ = 0.501, P = .001) positions. In individuals greater than 1 year following rupture, relative ATRA with the knee flexed related to shear modulus (ρ = .800, P = .01) and total work on the heel-rise test (ρ = -.782, P = .008) relative to the uninjured side. Relative ATRA in both knee flexed and knee extended positions has a moderate relationship to tendon elongation within the first year following rupture. After 1 year, the relative ATRA with knee flexed may be a better indicator of tendon elongation and also related to tendon mechanical properties and heel-rise test performance. Level III, case-control study.

Ultrasound measurements of Achilles tendon length using skin markings are more reliable than extended-field-of-view imaging.

Elongation of the Achilles tendon has been associated with poorer function in patients treated for ruptures. This has led to the development of various ultrasound-based measurements, and the purpose of the present study was to compare the reliability of three ultrasound-based measuring procedures. Twenty healthy individuals (40 tendons) were assessed by two testers at two occasions, 12 weeks apart. The tendon length was measured from the calcaneal insertion to the mid-sagittal muscle tendon junction (MTJ) using skin markings or extended-field-of-view (EFOV) imaging, or from the calcaneal insertion to the distal medial MTJ using skin markings. Test-retest and inter-tester reliability as well as side-to-side length differences were assessed for all three procedures. Test-retest intraclass correlation coefficients (ICCs) for measurements from the mid-sagittal MTJ using EFOV imaging and skin markings, and from the distal medial MTJ using skin markings were 0.83, 0.90 and 0.96 for tester 1 and 0.87, 0.91 and 0.96 for tester 2, respectively. The corresponding inter-tester ICCs were 0.85, 0.91 and 0.96. Side-to-side lengths were significantly different for measurements from the mid-sagittal MTJ and the distal medial MTJ using skin markings, with mean differences of 0.3 and 0.4cm, respectively. Test-retest and inter-tester ICCs were excellent for all three measuring procedures, however, the use of skin markings provided consistently better agreement and reliability compared to EFOV images. The best agreement and highest ICCs were achieved for measurements from the distal medial MTJ, but side-to-side length differences warrant caution when contralateral measurements are used to evaluate tendon elongation. III.

A cross-sectional study on the mechanical properties of the Achilles tendon with growth.

This study aimed to elucidate growth pattern of mechanical properties of the Achilles tendon and to examine if imbalance between growth of bone and muscle-tendon unit occurs during adolescence. Fourteen elementary school boys, 30 junior high school boys, 20 high school boys and 15 male adults participated in this study. Based on estimated age at peak height velocity (PHV), junior high school boys were separated into two groups (before or after PHV). An ultrasonography technique was used to determine the length, cross-sectional area, stiffness and Young's modulus of Achilles tendon. In addition, the maximum strain in "toe region" (strainTP) was determined to describe the balance between growth of bone and muscle-tendon unit. No group difference was observed in length, cross-sectional area and strainTP among the groups. However, stiffness and Young's modulus in after PHV groups were significantly higher than those of elementary school boys and before PHV groups(p ≤ 0.05). These results indicate that mechanical properties of Achilles tendon change dramatically at and/or around PHV to increased stiffness. The widely believed assumption that muscle-tendon unit is passively stretched due to rapid bone growth in adolescence is not supported.

Individuals Post Achilles Tendon Rupture Exhibit Asymmetrical Knee and Ankle Kinetics and Loading Rates During a Drop Countermovement Jump.

Study Design Cross-sectional laboratory study. Background Asymmetrical knee loading during jogging and hopping has been reported in individuals who have ruptured their Achilles tendon. No studies have examined knee loads in individuals post Achilles tendon rupture during high-demand tasks, such as single-limb landings. Objectives We sought to determine whether individuals post Achilles tendon rupture demonstrated asymmetrical knee loads and impact forces during drop countermovement jumps (CMJs). Methods Achilles tendon length and the single-leg heel-rise test for endurance were assessed in 34 individuals (31 male) 6.1 ± 2.0 years post Achilles tendon rupture. Movement patterns were assessed during a drop CMJ. Data were analyzed via repeated-measures analyses of variance, with comparisons between limbs and prior treatment history (surgery versus nonsurgery). Results An 8.6% longer Achilles tendon (P<.001) was found in the involved limb. During the single-leg heel-rise test, the involved limb demonstrated 22.4% less endurance and 14.6% lower heel-rise height (all, P<.001). During the landing phase of the drop CMJ, the involved limb exhibited 39.6% greater loading rate (P<.001), 16.8% greater eccentric knee power (P = .048), but 21.6% lower eccentric ankle power (P<.001). During the take-off phase, the involved limb exhibited 12.1% lower jump height and 19.9% lower concentric ankle power (both, P<.001). Conclusion Elevated eccentric knee joint power and higher loading rates during a drop CMJ in individuals who experienced Achilles tendon rupture several years earlier may be a compensation pattern for reduced plantar flexor function. This movement pattern may place individuals who have had an Achilles tendon rupture at greater risk for knee injuries. J Orthop Sports Phys Ther 2018;48(1):34-43. Epub 26 Oct 2017. doi:10.2519/jospt.2018.7684.

Calf Muscle Atrophy and Achilles Tendon Elongation After Acute Achilles Tendon Rupture

Calf muscle atrophy and Achilles tendon elongation seems to be the principal structural explanations for calf muscle strength deficit at short and long term follow up and also explain surgery related greater plantar flexion strength compared conservative treatment after acute Achilles tendon rupture. Despite good clinical results of surgery and conservative treatment for acute Achilles tendon rupture (ATR), surgery may result in 10-18% better calf muscle strength. However, 12-18% strength deficit compared to the unaffected leg usually remains even in long-term follow up. We aimed to assess whether Achilles tendon elongation and calf muscle volume changes could explain the difference in calf muscle strength between conservative treatment and surgery and side-to side strength deficit of calf muscle for patients with operatively treated ATR in long term follow-up. Group 1; 60 patients with acute ATRs were randomized to surgery or conservative treatment. Conservative treatment and post operative treatments were identical; cast immobilization for one week, followed by functional orthosis for 6 weeks, which allowed full weight bearing after week 1 and active plantar flexion after week 5 post injury. At 18 months, MRI was used to evaluate the volume of calf muscles and the length of the affected Achilles tendon. Group 2; 60 patients with acute ATRs were randomized to simple end-to-end repair or augmented repair, both with postoperative bracing allowing free active plantar flexion for 3 weeks. After follow-up of =13 years, 55 patients (28 non-augmented, 27 augmented) were re-examined and MRI was used to evaluate the volume of calf muscles, and the length of the Achilles tendons for both legs. Group 1; At 18 months, the mean differences between healthy and affected soleus muscle volumes were 83.2 cm3 (17.7%) after surgery and 115.5 cm3 (24.8%) after conservative treatments (difference between means: 33.1 cm3, 95% CI: 1.3 to 65.0, p = 0.042). Achilles tendon length from calcaneal insertion to soleus muscle MTJ for affected leg was 18.7mm longer for conservative treatment compared operative treatment (95% CI: 8.5 to 28.8, p<0.001). All patients in group 1 suffered up to 21% calf muscle atrophy for affected leg, which was compensated by 11% hypertrophy in flexor hallucis longus (FHL) (p=0.001 in all). Group 2; At 14 years patients in group 2 suffered up to 12% calf muscle atrophy for affected leg which was compensated by 5.4% hypertrophy in flexor halluces longus (FHL) (p=0.001 in all). Achilles tendon length from calcaneal insertion to medial gastrocnemius muscle MTJ for affected leg was 12.1mm longer compared healthy tendon (95% CI, 8.6 to 15.6, p<0.001). At 18 months ATR conservative treatment with a functional rehabilitation protocol resulted in greater soleus muscle atrophy and 19 mm longer calcaneus to soleus MTJ length to surgical treatment. At 14 years ATR operative treatment resulted up to 12% calf muscle atrophy and 12mm longer Achilles tendon of the affected leg. Calf muscle atrophy in the affected leg was compensated with hypertrophy of the FHL both in short and long term follow-up. Achilles tendon elongation may be the principal structural explanation of calf muscle atrophy and muscle strength deficit at short and long term follow-up after ATR.

Achilles Tendon Length, ATRS and Functional Outcomes 5 Years After Acute Achilles Tendon Rupture Treated Conservatively

Acute Achilles tendon ruptures, randomized to conservative treatment +/- early weight bearing, had elongated tendons and lower heel raise work, as well as a delayed heel lift during gait - 4.5 years post rupture. Weight bearing did not impact results. Achilles tendon rupture may lead to significant functional deficits, which mechanisms are poorly understood. The primary aim was to investigate if the Achilles tendon (AT) was longer, muscles weaker or gait changed on the injured leg 4-5 years after the injury. Secondary aim was to compare functional outcomes with patient reported Achilles Tendon Total Rupture Score (ATRS). We invited all participants from an RCT of conservatively treated AT Rupture (ATR) with or without early weight-bearing (early-WB, non-WB), and 12 moths of follow up. Of the original 56, 37 patients participated, 19 from early-WB (1 re-rupture (RR)), and 18 from non-WB (2 RR). Time from injury to follow up was 4.5 years (4.1 to 5.1). AT length was measured using ultrasound with a validated protocol (Barfod K.W. et al.). Heel raise work was measured on a 10 degree inclining platform. The exercise lasted until the patient could not maintain frequency or height of lift. Number and height of lift was measured using reflective markers in a Vicon system, and total work calculated. Foot pressure mapping (FPM) was measured barefoot, using an EMED platform (novel, Germany). T-test for limb to limb comparisons and linear regression for ATRS correlations was applied. Including RR in the sample did not impact the results. We found no differences in any of the variables between the early-WB and non-WB groups. Compared to the uninjured limb, the Achilles tendon was an average of 1.8 (1.2-2.3) cm longer on the injured limb, which produced 40% less work. A smaller calf circumference (p<0.001), larger dorsiflexion (p=0.001), and Achilles tendon resting angle (p<0.001) was found for the injured limb. Difference in mean medial forefoot peak pressure was approaching significance (healthy 484 (SD 165) KPa, injured: 439 (SD 160), p=0.08). Similarly the difference in pressure / time integral of the medial forefoot was approaching significance (Healthy: 129 (SD 35) KPa, injured: 115 (SD 44) KPa, p=0.08). Duration of contact time of the heel was extended and heel lift off was delayed in the injured limb (p= 0.02 for both). ATRS could not be linked to Achilles tendon length or total work using linear regression. Conservatively treated Achilles tendon ruptures were approximately 1.8 cm longer. The limb was persistently weaker. A subtle change in heel contact duration and time of heel rise could be detected on the injured limb. ATRS does not appear to correlate directly with AT length or loss of total work.

Tendon Length, Calf Muscle Atrophy, and Strength Deficit After Acute Achilles Tendon Rupture: Long-Term Follow-up of Patients in a Previous Study.

In this prospective study, we used magnetic resonance imaging (MRI) to assess long-term Achilles tendon length, calf muscle volume, and muscle fatty degeneration after surgery for acute Achilles tendon rupture. From 1998 to 2001, 60 patients at our center underwent surgery for acute Achilles tendon rupture followed by early functional postoperative rehabilitation. Fifty-five patients were reexamined after a minimum duration of follow-up of 13 years (mean, 14 years), and 52 of them were included in the present study. Outcome measures included Achilles tendon length, calf muscle volume, and fatty degeneration measured with MRI of both the affected and the uninjured leg. The isokinetic plantar flexion strength of both calves was measured and was correlated with the structural findings. The Achilles tendon was, on average, 12 mm (95% confidence interval [CI] = 8.6 to 15.6 mm; p < 0.001) longer (6% longer) in the affected leg than in the uninjured leg. The mean volumes of the soleus and medial and lateral gastrocnemius muscles were 63 cm (13%; p < 0.001), 30 cm (13%; p < 0.001), and 16 cm (11%; p < 0.001) lower in the affected leg than in the uninjured leg, whereas the mean volume of the flexor hallucis longus (FHL) was 5 cm (5%; p = 0.002) greater in the affected leg, indicating FHL compensatory hypertrophy. The median plantar flexion strength for the whole range of motion ranged from 12% to 18% less than that on the uninjured side. Finally, the side-to-side difference in Achilles tendon length correlated substantially with the strength deficit (ρ = 0.51, p < 0.001) and with medial gastrocnemius (ρ = 0.46, p = 0.001) and soleus (ρ = 0.42, p = 0.002) muscle atrophy. Increased Achilles tendon length is associated with smaller calf muscle volumes and persistent plantar flexion strength deficits after surgical repair of Achilles tendon rupture. Strength deficits and muscle volume deficits are partly compensated for by FHL hypertrophy, but 11% to 13% deficits in soleus and gastrocnemius muscle volumes and 12% to 18% deficits in plantar flexion strength persist even after long-term follow-up. Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Use of ankle resting angle as a surrogate for tendon elongation in individuals following Achilles tendon rupture

Category: Ankle, Sports Introduction/Purpose: Tendon elongation is associated with poor functional outcome in individuals after Achilles tendon rupture. While imaging modalities are reliable to measure Achilles tendon length, alternative time- and cost-effective measures are of interest. The resting angle of the ankle in prone both with knee extended1 and knee flexed2 have been used in the literature as surrogates for measuring Achilles elongation, however, their relationship to tendon length is not well-established. The purpose of this study is to validate the ankle resting angle as a measure of tendon elongation and examine the relationship of ankle resting angle to tendon elongation and calf strength. Methods: Individuals following unilateral Achilles tendon rupture, treated surgically, were included in this cross-sectional study. Individuals were excluded if they had deep wound infection or lumbar radiculopathy affecting the ankle plantar flexors. Ankle resting angle with knee extended and knee flexed to 90 degrees was measured using a digital inclinometer positioned on the lateral, plantar surface of the foot. Relative resting angle was calculated by subtracting the uninjured from the injured side. Tendon length to gastrocnemius was measured using B mode, extended field of view ultrasound imaging3 (tendon elongation = ruptured- uninjured). Calf strength was measured using the heel-rise test4. Limb symmetry indexes (LSI) were calculated (ruptured/uninjured sidex100) for total work performed on the heel-rise test. Results: Twenty-five individuals, a mean(SD) age of 44.2(13.6) years and mean(SD) of 22.5(39.1) months post-rupture, were included in this study. Mean(SD) relative resting angle with knee flexed was -5.4(6.4)° and mean (SD) relative resting angle with knee extended was -6.7(8.8)°. Mean(SD) tendon elongation was 1.56(1.20)cm. Mean(SD) heel-rise test work LSI was 45.8(23.8)%. Ankle resting angle with knee flexed related to elongation (r = -0.452, p = 0.027) and heel-rise test work LSI (r = 0.591, p=0.006). Ankle resting angle with knee extended related to elongation (r=-0.528, p=0.008) (Figure 1) but not heel-rise test work LSI. Conclusion: The results of this study suggest that ankle resting angle with knee extended and flexed are related to tendon elongation, however, calf strength also has a relationship to resting angle with knee flexed. This suggests that the ability of the calf to put passive tension on the foot is also a component of resting angle. The relationship between tendon elongation and resting angle with knee flexed may have been limited by methodological concerns, as tendon length was measured with the participant positioned with knees extended.

Heel-Rise Height Deficit 1 Year After Achilles Tendon Rupture Relates to Changes in Ankle Biomechanics 6 Years After Injury

Background: It is unknown whether the height of a heel-rise performed in the single-leg standing heel-rise test 1 year after an Achilles tendon rupture (ATR) correlates with ankle biomechanics during walking, jogging, and jumping in the long-term. Purpose: To explore the differences in ankle biomechanics, tendon length, calf muscle recovery, and patient-reported outcomes at a mean of 6 years after ATR between 2 groups that, at 1-year follow-up, had less than 15% versus greater than 30% differences in heel-rise height. Study Design: Cohort study; Level of evidence, 3. Methods: Seventeen patients with less than 15% (<15% group) and 17 patients with greater than 30% (>30% group) side-to-side difference in heel-rise height at 1 year after ATR were evaluated at a mean (SD) 6.1 (2.0) years after their ATR. Ankle kinematics and kinetics were sampled via standard motion capture procedures during walking, jogging, and jumping. Patient-reported outcome was evaluated with Achilles tendon Total Rupture Score (ATRS), Physical Activity Scale (PAS), and Foot and Ankle Outcome Score (FAOS). Tendon length was evaluated by ultrasonography. The Limb Symmetry Index (LSI = [Injured Side ÷ Healthy Side] × 100) was calculated for side differences. Results: The >30% group had significantly more deficits in ankle kinetics during all activities compared with patients in the <15% group at a mean of 6 years after ATR (LSI, 70%-149% and 84%-106%, respectively; P = .010-.024). The >30% group, compared with the <15% group, also had significantly lower values in heel-rise height (LSI, 72% and 95%, respectively; P < .001) and heel-rise work (LSI, 58% and 91%, respectively; P < .001) and significantly larger side-to-side difference in tendon length (114% and 106%, respectively; P = .012). Achilles tendon length correlated with ankle kinematic variables (r = 0.38-0.44; P = .015-.027) whereas heel-rise work correlated with kinetic variables (r = −0.57 to 0.56; P = .001-.047). LSI tendon length correlated negatively with LSI heel-rise height (r = −0.41; P = .018). No differences were found between groups in patient-reported outcome (P = .143-.852). Conclusion: Height obtained during the single-leg standing heel-rise test performed 1 year after ATR related to the long-term ability to regain normal ankle biomechanics. Minimizing tendon elongation and regaining heel-rise height may be important for the long-term recovery of ankle biomechanics, particularly during more demanding activities such as jumping.