UNASSIGNED: Achilles tendon ruptures often result in long-term functional deficits despite accelerated (standard) rehabilitation.
UNASSIGNED: The purpose of this study was to investigate if delayed loading would influence functional, clinical, and structural outcomes of the muscles and tendon 1 year after a surgical repair. It was hypothesized that delaying the loading would reduce the heel-rise height deficit 1 year after Achilles tendon rupture.
UNASSIGNED: Randomized controlled trial; Level of evidence, 1.
UNASSIGNED: In total, 48 patients with a surgically repaired Achilles tendon rupture were randomized to 2 groups: the standard group received the currently accepted rehabilitation, and the delayed group received the same rehabilitation except that initial loading was delayed by 6 weeks. The primary outcome was the heel-rise height difference between the injured and uninjured sides at 1 year. The secondary outcomes were (1) tendon length measured with magnetic resonance imaging, (2) muscle fascicle length and pennation angle of the gastrocnemius medialis muscle, (3) Doppler activity measured with ultrasonography, (4) Achilles tendon Total Rupture Score (ATRS), and (5) isometric muscle strength.
UNASSIGNED: The mean heel-rise height deficits for the standard and delayed groups were -2.2 cm and -2.1 cm, respectively (P = .719). The soleus part of the tendon was already elongated 1 week after surgery in both groups without a between-group difference (side-to-side difference: standard, 16.3 mm; delayed, 17.5 mm; P = .997) and did not change over 52 weeks. The gastrocnemius tendon length was unchanged at 1 week but elongated over time without a between-group difference (side-to-side difference at 52 weeks: standard, 10.5 mm; delayed, 13.0 mm; P = .899). The delayed group had less Doppler activity at 12 weeks (P = .006) and a better ATRS (standard, 60 points; delayed, 72 points; P = .032) at 52 weeks.
UNASSIGNED: Delayed loading was not superior to standard loading in reducing the heel-rise height difference at 1 year. The data indirectly suggested reduced inflammation in the initial months and a better patient-reported outcome at 1 year in the delayed group. The soleus part of the tendon was already markedly elongated (35%) 1 week after surgery, while the length of the gastrocnemius tendon was unchanged at 1 week but was 6% elongated at 1 year. Together, these data indirectly suggest that the delayed group fared better, although this finding needs to be confirmed in future investigations.
UNASSIGNED: NCT04263493 (ClinicalTrials.gov identifier).

This study evaluates the suitability of the plantaris tendon (PT) as a tendon graft donor for sports trauma reconstruction and proposes a predictive model for estimating PT length by using an individual\'s height and leg length. Anatomical dissection of 50 cadavers (32 males and 18 females) yielded precise measurements of PT length and width while also recording height and leg length. Among the lower limbs, 89% were suitable for at least one recommended graft suitability criterion. In addition, PT length exhibited robust positive correlations with height and leg length. Predictive equations were established for estimating the PT length based on leg length and height with consistency across sexes and sides: PT length = 0.605 + 0.396 × leg length (r = 0.721) and PT length = 1.480 + 0.193 × height (r = 0.626). This study underscores the grafting potential of the PT, providing a predictive tool that can aid surgeons in addressing tendon graft challenges within sports trauma scenarios.

OBJECTIVE: Rotator Cuff (RC) lesions are classified in full-thickness and partial-thickness tears (PTRCTs). To our knowledge, no studies investigated the mean size of shoulder tendons in healthy and PTRCT patients using MRI scans. The aim of the study was to provide data to obtain and compare the mean value of tendon sizes in healthy and PTRCTs groups.
METHODS: From 2014 to 2020, 500 were included in the study. They were divided into two groups: Group 1 (100 subjects) was composed of people positive for partial-thickness rotator cuff tears (PTRCTs), while the 400 subjects in Group 2 were negative for PTRCTs.
RESULTS: Overall, of the patients included in the study, 231 were females and 269 were males. The mean age of the patients was 49 ± 12.7 years. The mean thickness of the supraspinatus tendon (SSP) was 5.7 ± 0.6 mm in Group 1, 5.9 ± 0.6 mm in Group 2 (p < 0.001). The mean length of the ISP tendon was 27.4 ± 3.2 mm in Group 1, 28.3 ± 3.8 mm in Group 2 (p = 0.004). The mean width of the SSP tendon was 17 ± 1.6 mm in Group 1, 17.6 ± 2 mm in Group 2 (p = 0.004). The mean width of the infraspinatus tendon (ISP) tendon was 17.7 ± 1.4 mm in Group 1, 18.3 ± 2.1 mm in Group 2 (p = 0.02).
CONCLUSIONS: The anatomical data present in this paper may serve as a tool for surgeons to properly manage PTRCTs. The findings of the present study aimed to set the first step towards reaching unanimity to establish international cut-off values to perform surgery. Additionally, they could widely increase diagnostic accuracy, improving both conservative and surgical approaches. Lastly, further clinical trials using more accurate diagnostic MRI tools are required to better define the anatomical differences between PTRCT and healthy patients.
METHODS: Level II, Retrospective Comparative Trial.

BACKGROUND: There is a phenomenon in which the tendon appears to increase the length after rotator cuff repair. However, it is unclear in which cases tendon lengthening occurs and how the degree of lengthening affects the surgical outcome. This study aimed to evaluate preoperative and postoperative musculotendinous junction (MTJ) and tendon length on magnetic resonance imaging and assess the postoperative tendon lengthening and its impact on postoperative outcomes.
METHODS: We reviewed 109 patients with good repair integrity after arthroscopic rotator cuff repair. Patients whose supraspinatus tendons were simply pulled out laterally without any additional procedures were included. They underwent serial magnetic resonance imaging before surgery and at 3, 6, and 24 months after surgery. The location of the MTJ in relation to the line of the glenoid fossa and the supraspinatus tendon length were measured. Clinical evaluation was conducted 2 years after surgery, including the range of shoulder motion, shoulder strength index (affected/unaffected strength), Constant score, University of California, Los Angeles score, and pain numeric rating scale. The characteristics of the preoperative tendon, change in tendon length over time, amount of the lateral shift of MTJ location and tendon length, and impact of tendon lengthening on postoperative clinical outcomes were analyzed.
RESULTS: The preoperative tendon retraction significantly correlated with the MTJ location (r = -0.75; P < .0001) and preoperative tendon length (r = -0.46; P < .0001). The tendon length at 3, 6, and 24 months after surgery was significantly longer than those before surgery (26.7 ± 5.8 mm, 27.9 ± 6.6 mm, 28.5 ± 5.6 mm, and 21.5 ± 5.1 mm, respectively). From before surgery to 24 months after surgery, the MTJ location moved 8.4 ± 8.6 mm laterally and the tendon length increased 7.0 ± 6.1 mm. A significant and weak negative correlation was found between tendon lengthening and the abduction strength index (r = -0.22; P = .03); however, no significant correlation with pain, range of shoulder motion, external rotation strength index, Constant score, and University of California, Los Angeles score was found. Multiple linear regression analysis also showed that tendon lengthening was only associated with the abduction strength index (standardized coefficient = -0.20, P = .03).
CONCLUSIONS: Tendon lengthening and lateral shift of MTJ location were observed after arthroscopic rotator cuff repair, and they correlated with preoperative tendon retraction. Although the amount of tendon lengthening had negative weak correlation with abduction strength index, it did not affect other postoperative outcomes.

OBJECTIVE: The aim of this study was to investigate how the Achilles tendon resting angle (ATRA), an indirect measurement of tendon elongation, correlates with ultrasonography (US) measurements of the Achilles tendon length 6 and 12 months after an acute ATR and relates to other clinical outcome measurements such as heel-rise height, jumping ability and patient-reported outcome measurements (PROMs).
METHODS: Patients were included following acute Achilles tendon rupture (ATR). Achilles tendon length, ATRA, heel-rise height (HRH), drop countermovement jump (Drop CMJ) and PROMs (Achilles tendon total rupture score (ATRS) and physical activity scale (PAS)) were evaluated 6 and 12 months after injury. Achilles tendon length was evaluated using US, while the ATRA was measured with a goniometer.
RESULTS: Sixty patients (13 women, 47 men), mean (SD) age 43 (9) years, with an acute ATR undergoing either surgical (35%) or non-surgical (65%) treatment were evaluated. A negative correlation (r = - 0.356, p = 0.010) between relative ATRA and tendon elongation was seen at 12 months after ATR. There were also significant positive correlations at 6 and 12 months between relative ATRA and HRH (r = 0.330, p = 0.011 and r = 0.379, p = 0.004). There were no correlations between ATRA and ATRS or ATRA and Drop CMJ, at either 6 or 12 months after the injury.
CONCLUSIONS: In combination with other clinical evaluations such as HRH and US, ATRA could be a clinical tool for indirect measurements of tendon elongation. However, ATRA cannot be recommended as a direct surrogate for US for determining Achilles tendon length.
METHODS: III.

OBJECTIVE: To determine the relationships among calf muscle function, tendon length and gait biomechanics in patients surgically treated for chronic Achilles tendon rupture.
METHODS: Twenty-one patients with chronic Achilles tendon rupture (mean age 62 ± 13 years) were evaluated by heel-rise endurance test, Achilles Tendon Resting Angle (ATRA), ultrasound measurement of tendon length and three-dimensional gait analysis. A bivariate two-sided correlation test was performed on all variables in all patients.
RESULTS: Better performance across all parameters of the heel-rise endurance test correlated with faster walking speed (r = 0.52-0.55), greater peak ankle power (r = 0.56-0.64), shorter stance phase (r = -0.52 to -0.76) and less peak ankle dorsiflexion angle (r = -0.49 to -0.64) during gait. Greater ATRA correlated with longer stance time (r = 0.47), greater peak ankle dorsiflexion angle (r = 0.48), less heel-rise repetitions (r = -0.52) and less heel-rise total work LSI (r = -0.44 to -0.59).
CONCLUSIONS: Greater calf muscle endurance, especially heel-rise total work, is moderately correlated (r = 0.49-0.76) to better ankle biomechanics during gait in patients surgically treated for CATR. The heel-rise endurance test may be a clinical proxy for power development in the ankle joint during gait.
METHODS: IV.

The precise location of the Master Knot of Henry (MKH) has important clinical significance, but its anatomical definition has not been agreed upon. The purpose of this study is to present a linear regression equation for predicting length variables based on foot length, by evaluating the correlation of length variables related to flexor hallucis longus (FHL) and flexor digitorum longus (FDL), with respect to the location of the MKH. A total of 95 limbs were dissected from 48 adult cadavers, and were fixed in formalin. Measurements were made for the length parameter, with reference to the landmark. The relevance between length variables was analyzed through simple correlation analysis and linear regression analysis. The foot length was 213.69 ± 17.53 mm, MKH-great toe distal phalanx was 140.16 ± 14.69 mm, MKH-FHL insertion was 124.55 ± 13.46 mm, MKH-little toe distal phalanx was 121.79 ± 13.41 mm, MKH-FDL little toe insertion was 109.07 ± 14.16 mm, and the FHL-FDL angle was 33.15 ± 5.39. The correlation coefficient between all the length variables for foot length showed a high positive correlation. We derived a regression equation that can predict the length of each variable. This regression formula is considered to be highly useful because it can estimate the positional relationship of the MKH relatively simply.

OBJECTIVE: Evaluate the one-year postoperative outcomes in patients with Chronic Achilles tendon rupture.
METHODS: Patients surgically treated for Chronic Achilles tendon rupture (n = 22, 14 males and 8 females, mean age 61 ± 15) were evaluated by Achilles tendon Total Rupture Score, The Physical Activity Scale, The Foot and Ankle Outcome Score, Calf muscle endurance test, counter movement jump, Hopping, ultrasound measurement of tendon length, Achilles Tendon Resting Angle, dorsi flexion range of motion and calf muscle circumference. Muscle function and tendon length outcomes on the injured side were compared with the healthy side.
RESULTS: The patients scored a mean of 62 ± 26 on the Achilles tendon Total Rupture Score. Median scores on the injured compared with the healthy side were lower in heel-rise repetitions (20 vs 24 cm, p = 0.004), hel-rise height (8 vs 10 cm, p < 0.001), heel-rise total work (872 vs 1590 joule, p < 0.001) and hopping ratio (0.37 vs 0.48, p = 0.005). Median calf circumference was smaller (37 vs 38 cm, p = 0.001) and the mean tendon elongation greater on the injured side; Achilles tendon resting angle (55 vs 50°, p < 0.001) and ultrasound (22.4 vs 20.5 cm, p = 0.006).
CONCLUSIONS: At one year postoperatively, patients with chronic Achilles tendon rupture reported persistent limitations in subjective foot and ankle function. Heel-rise height and total work as well as hopping ratio were not recovered, and there was an elongation of the injured Achilles tendon compared with the healthy tendon.
METHODS: IV.

Eccentric training proved to be effective in hamstring injury prevention; however, little is known about effects of eccentric hamstring training at long muscle length on hamstring flexibility. Hence, the aim was to evaluate the effect of eccentric training at long muscle lengths on flexibility and passive properties of the hamstring muscles. 34 physically active young adults were randomized to either the control or intervention group (6 weeks of eccentric hamstring training at long muscle length; control group resumed with their usual activities). Maximal passive hip flexion range of motion (ROM), passive hamstring stiffness, shear modulus and tendon length of the biceps femoris long head (BFlh) were measured pre- and post-intervention. A significant time × group effect was observed for maximal passive hip ROM. Post-hoc testing revealed a significant increase in the intervention group (+11.2%; p < 0.001; d = 1.55). Additionally, a significant time effect was shown for shear modulus in a relaxed position (p < 0.001). No significant interaction was shown for other parameters. Results indicate that eccentric hamstring training at long muscle length elicits large gains in hamstring flexibility, which are most likely not related to changes in passive hamstring stiffness or BFlh distal tendon length.

The purpose of this study was to investigate the structural properties (length and cross-sectional area) of both the Patellar and Achilles tendons at around adolescent growth spurt. One hundred-twenty children and adolescents participated in this study. Based on estimated age at peak height velocity, the participants were separated into three groups (before takeoff of adolescent growth spurt group, from takeoff of adolescent growth spurt until peak height velocity group and after peak height velocity group). An ultrasonography technique was used to determine structural properties of the Patellar and Achilles tendons. Significant group difference was observed in tendon length for the Patellar and Achilles tendons among groups. However, there were no significant differences in the ratio of the Patellar tendon to upper leg length and the ratio of the Achilles tendon to lower leg length among groups. The cross-sectional area of all regions for the Patellar and Achilles tendons in adolescents with after takeoff adolescent growth spurt group was greater than those of before takeoff adolescent growth spurt group. These results indicate that the cross-sectional area of both the Patellar and Achilles tendons increase with takeoff of adolescent growth spurt and tendons lengthen without the changes in the ratio of tendon length to bone length. In addition, the increases in the cross-sectional area of both the Patellar and Achilles tendons occur in whole regions but not specific regions.