Early Predictors of Recovery From Nonoperatively Treated Achilles Tendon Rupture: 1 Year Follow-Up Study.

PURPOSE: To investigate early structural and mechanical predictors of plantarflexor muscle strength and the magnitude of Achilles tendon (AT) nonuniform displacement at 6 and 12 months after AT rupture. METHODS: Thirty-five participants (28 males and 7 females; mean ± SD age 41.7 ± 11.1 years) were assessed for isometric plantarflexion maximal voluntary contraction (MVC) and AT nonuniformity at 6 and 12 months after rupture. Structural and mechanical AT and plantarflexor muscle properties were measured at 2 months. Limb asymmetry index (LSI) was calculated for all variables. Multiple linear regression was used with the 6 and 12 month MVC LSI and 12 month AT nonuniformity LSI as dependent variables and AT and plantarflexor muscle properties at 2 months as independent variables. The level of pre- and post-injury sports participation was inquired using Tegner score at 2 and 12 months (scale 0-10, 10 = best possible score). Subjective perception of recovery was assessed with Achilles tendon total rupture score (ATRS) at 12 months (scale 0-100, 100=best possible score). RESULTS: Achilles tendon resting angle (ATRA) symmetry at 2 months predicted MVC symmetry at 6 and 12 months after rupture (ß = 2.530, 95% CI 1.041-4.018, adjusted R2 = 0.416, p = 0.002; ß = 1.659, 95% CI 0.330-2.988, adjusted R2 = 0.418, p = 0.016, respectively). At 12 months, participants had recovered their pre-injury level of sports participation (Tegner 6 ± 2 points). The median (IQR) ATRS score was 92 (7) points at 12 months. CONCLUSION: Greater asymmetry of ATRA in the early recovery phase may be a predictor of plantarflexor muscle strength deficits up to 1 year after rupture. TRIAL REGISTRATION: This research is a part of "nonoperative treatment of Achilles tendon rupture in Central Finland: a prospective cohort study" that has been registered in ClinicalTrials.gov (NCT03704532).

Achilles tendon and triceps surae muscle properties in athletes.

PURPOSE: The aim of this study was to investigate internal Achilles tendon (AT) displacement, AT shear wave velocity (SWV), and triceps surae (TS) muscle shear modulus in athletes. METHODS: Internal AT displacement was assessed using ultrasound during isometric contraction. Shear wave elastography was used to assess AT SWV (m × s-1) at rest and TS muscle shear modulus (kPa) during passive ankle dorsiflexion. RESULTS: A total of 131 athletes participated in this study. Athletes who had not exercised within two days had greater AT non-uniformity and mean anterior tendon displacement, and lower SWV at the proximal AT measurement site (mean difference [95% CI]: 1.8 mm [0.6-2.9], p = 0.003; 1.6 mm [0.2-2.9], p = 0.021; - 0.9 m × s-1 [- 1.6 to - 0.2], p = 0.014, respectively). Male basketball players had a lower mean AT displacement compared to gymnasts (- 3.7 mm [- 6.9 to - 0.5], p = 0.042), with the difference localised in the anterior half of the tendon (- 5.1 mm [- 9.0 to - 1.1], p = 0.022). Male gymnasts had a smaller absolute difference in medial gastrocnemius-minus-soleus shear modulus than basketball players (59.6 kPa [29.0-90.2], p < 0.001) and track and field athletes (52.7 kPa [19.2-86.3], p = 0.004). Intraclass correlation coefficients of measurements ranged from 0.720 to 0.937 for internal AT displacement, from 0.696 to 0.936 for AT SWE, and from 0.570 to 0.890 for TS muscles. CONCLUSION: This study provides a reliability assessment of muscle and tendon SWV. The relative differences in passive TS muscle shear modulus suggest sport-specific adaptation. Importantly, in healthy individuals, lower AT displacement after exercise may reflect the time required for tendon recovery.

Achilles Tendon Stiffness: Influence of Measurement Methodology.

OBJECTIVE: Mechanical stiffness derived from force-elongation curves is fundamentally different from shear wave (SW) elastography-based tissue properties. We compared these techniques, with a total of five methods of assessing Achilles tendon (AT) stiffness. METHODS: Seventeen participants (12 male and 5 female) with unilateral AT rupture performed submaximal contractions at 30% and 10% maximal isometric contraction torque of the un-injured limb. SW velocity was acquired at rest. Force-elongation curves were assessed from the free AT and the medial gastrocnemius (MG) tendon. Mechanical stiffness was determined near the end of the linear region of the force-elongation curve and from the toe region. Bivariate correlations between mechanical stiffness and SW velocity, as well as pairwise t-tests between limbs, were computed. RESULTS: In the injured limb, SW velocity correlated with MG tendon and free AT toe-region stiffness during 10% (r = 0.59, p = 0.020 and r = 0.60, p = 0.011, respectively) and 30% of submaximal contractions (r = 0.56, p = 0.018 and r = 0.67, p = 0.004, respectively). The un-injured limb showed no associations. In both limbs pooled together, SW velocity correlated with MG tendon toe-region stiffness in 30% of submaximal contractions (r = 0.43, p = 0.012). Free tendon mechanical stiffness was lower in the injured limb, with a mean difference of 148.5 Nmm⁻¹ (95% CI: 35.6-261.3, p = 0.013), while SW velocity was higher in the injured limb (1.67 m × s⁻¹, 95% CI; -2.4 to -0.9, p < 0.001). CONCLUSION: SW elastography may reflect AT viscoelastic properties at the initial slope of the force-length curve with strains <1% but cannot offer insight into AT mechanics at higher loads. Extended toe regions in the injured limb could have caused the association between mechanical stiffness and SW-based stiffness.

Wearing an ultrasound probe during walking does not influence lower limb joint kinematics in adolescents with cerebral palsy and typically developing peers.

BACKGROUND: Enhancing traditional three-dimensional gait analysis with a portable ultrasound device at the lower-limb muscle-tendon level enables direct measurement of muscle and tendon lengths during walking. However, it is important to consider that the size of the ultrasound probe and its attachment on the lower limb may potentially influence gait pattern. RESEARCH QUESTION: What is the effect of wearing an ultrasound probe at the lower limb in adolescents with cerebral palsy and typically developing peers? METHODS: Eleven individuals with cerebral palsy and nine age-matched typically developing peers walking barefoot at their self-selected speed were analyzed. Data collection occurred under three conditions: the reference condition (GAIT), and two conditions involving placement of the ultrasound probe over the distal medial gastrocnemius-Achilles tendon junction (MTJ) and over the medial gastrocnemius mid-belly to capture fascicles (FAS). Data processing included calculating differences between conditions using root mean square error (RMSE) for joint kinematics and comparing them to the overall mean difference. Additionally, Spearman correlations were calculated to examine the relationship between kinematic RMSEs and walking speed. RESULTS: No significant differences in stance phase duration or walking speed were observed among the three conditions. Average RMSEs were below 5° for all parameters and condition comparisons in both groups. In both the TD and CP groups, RMSE values during the swing phase were higher than those during the stance phase for all joints. No significant correlations were found between height or body mass and swing phase RMSEs. In the CP group, there was a significant correlation between joint kinematics RMSEs and differences in walking speed at the hip, knee and ankle joints when comparing the MTJ condition with the GAIT condition. SIGNIFICANCE: This study confirms joint kinematics alterations are smaller than 5° due to wearing to the leg an ultrasound probe during walking.

ISB clinical biomechanics award winner 2023: Medial gastrocnemius muscle and Achilles tendon interplay during gait in cerebral palsy.

BACKGROUND: The interplay between the medial gastrocnemius muscle and the Achilles tendon is crucial for efficient walking. In cerebral palsy, muscle and tendon remodelling alters the role of contractile and elastic components. The aim was to investigate the length changes of medial gastrocnemius belly and fascicles, and Achilles tendon to understand their interplay to gait propulsion in individuals with cerebral palsy. METHODS: Twelve young individuals with cerebral palsy and 12 typically developed peers were assessed during multiple gait cycles using 3D gait analysis combined with a portable ultrasound device. By mapping ultrasound image locations into the shank reference frame, the medial gastrocnemius belly, fascicle, and Achilles tendon lengths were estimated throughout the gait cycle. Participants with cerebral palsy were classified into equinus and non-equinus groups based on their sagittal ankle kinematics. FINDINGS: In typically developed participants, the Achilles tendon undertook most of the muscle-tendon unit lengthening during stance, whereas in individuals with cerebral palsy, this lengthening was shared between the medial gastrocnemius belly and Achilles tendon, which was more evident in the equinus group. The lengthening behaviour of the medial gastrocnemius fascicles resembled that of the Achilles tendon in cerebral palsy. INTERPRETATION: The findings revealed similar length changes of the medial gastrocnemius fascicles and Achilles tendon, highlighting the enhanced role of the muscle in absorbing energy during stance in cerebral palsy. These results, together with the current knowledge of increased intramuscular stiffness, suggest the exploitation of intramuscular passive forces for such energy absorption.

Medial gastrocnemius muscle fascicle function during heel-rise after non-operative repair of Achilles tendon rupture.

BACKGROUND: To better understand muscle remodelling in dynamic conditions after an Achilles tendon rupture, this study examined the length of medial gastrocnemius muscle fascicles during a heel-rise at 6- and 12-months after non-operative ATR treatment. METHODS: Participants (15 M, 3F) were diagnosed with acute Achilles tendon rupture. Medial gastrocnemius subtendon length, fascicle length and pennation angle were assessed in resting conditions, and fascicle shortening during bi- and unilateral heel-rises. FINDINGS: Fascicle shortening was smaller on the injured side (mean difference [95% CI]: -9.7 mm [-14.7 to -4.7 mm]; -11.1 mm [-16.5 to -5.8 mm]) and increased from 6- to 12 months (4.5 mm [2.8-6.3 mm]; 3.2 mm [1.4-4.9 mm]) in bi- and unilateral heel-rise, respectively. The injured tendon was longer compared to contralateral limb (2.16 cm [0.54-3.79 cm]) and the length decreased over time (-0.78 cm [-1.28 to -0.29 cm]). Tendon length correlated with fascicle shortening in bilateral (r = -0.671, p = 0.002; r = -0.666, p = 0.003) and unilateral (r = -0.773, p ≤ 0.001; r = -0.616, p = 0.006) heel-rise, at 6- and 12-months, respectively. In the injured limb, the change over time in fascicle shortening correlated with change in subtendon length in unilateral heel-rise (r = 0.544, p = 0.02). INTERPRETATION: This study showed that the lengths of the injured tendon and associated muscle can adapt throughout the first year after rupture when patients continue physiotherapy and physical exercises. For muscle, measures of resting length may not be very informative about adaptations, which manifest themselves during functional tasks such as unilateral heel-rise.

Cross-cultural adaptation and validation of the Kerlan-Jobe Orthopaedic Clinic shoulder and elbow score in Finnish-speaking overhead athletes.

BACKGROUND: The Kerlan-Jobe Orthopaedic Clinic Shoulder and Elbow score (KJOC) is developed to evaluate the shoulder and elbow function in overhead athletes. To date, the score has not been adapted into Finnish language. The aim of this study was to perform a cross-cultural adaptation of the Kerlan-Jobe Orthopaedic Clinic Shoulder and Elbow score (KJOC) into Finnish language and evaluate its validity, reliability, and responsiveness in overhead athletes. METHODS: Forward-backward translation method was followed in the cross-cultural adaptation process. Subsequently, 114 overhead athletes (52 males, 62 females, mean age 18.1 ± 2.8 years) completed the Finnish version of KJOC score, Disabilities of the Arm, Shoulder and Hand (DASH), American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) and RAND-36 to assess validity of the KJOC score. To evaluate reliability and responsiveness, the participants filled in the KJOC score 16 days and eight months after the first data collection. Validity, reliability, and responsiveness of the Finnish KJOC score were statistically tested. RESULTS: Minor modifications were made during the cross-cultural translation and adaptation process, which were related to culture specific terminology in sports and agreed by an expert committee. Construct validity of the KJOC score was moderate to high, based on the correlations with DASH (r = - 0.757); DASH sports module (r = - 0.667); ASES (r = 0.559); and RAND-36 (r = 0.397) questionnaires. Finnish KJOC score showed excellent internal consistency (α = 0.92) and good test-retest reliability (2-way mixed-effects model ICC = 0.77) with acceptable measurement error level (SEM 5.5; MDC 15.1). Ceiling effect was detected for asymptomatic athletes in each item (23.2-61.1%), and for symptomatic athletes in item 5 (47.4%). Responsiveness of the Finnish KJOC score could not be confirmed due to conflicting follow-up results. CONCLUSION: The Finnish KJOC score was found to be a valid and reliable questionnaire measuring the self-reported upper arm status in Finnish-speaking overhead athletes.