Tendon Length Research Articles

How susceptible are our Achilles Tendons? Sonoanatomical assessment. A cross-sectional study

Objectivethe aim of this study is to observe whether there are ultrasound changes between men and women in the Achilles tendon at rest, at maximum passive force is applied and during walking. Material and methodsit was a cross-sectional study involving 27 healthy young participants recruited as volunteers between April to July 2022. A variety of data was recorded: (age, Body Mass Index, sex, smoking, current injury status, allergies, medications, previous surgeries, type of sport, and number of weekly workouts) and ultrasound measurements at rest and at passive force (Cross Sectional Area Achilles Tendon length, tendon thickness, Cross Sectional Area and pennation angle of the soleus muscle to the Achilles Tendon). Resultswomen demonstrated a statistically significant lower proximal and median thickness both at rest (4.5 vs 5.1 mm with p < 0.001 for proximal thickness; 4.4 vs 5.3 mm with p < 0.001 for median thickness) as well as during maximum eccentric contraction (4.3 vs 4.8 mm with p=<0.001 for proximal thickness; 4.1 vs 4.8 mm with p < 0.001 for median thickness). Conclusionthere are significant sonoanatomical differences in vivo Achilles tendon between men and women.

Quantification of the Field of View for Standard Lateral Arthroscopy of the Canine Shoulder.

The aim of this study was to define the extent of the biceps tendon, subscapularis tendon, and cranial border of the medial glenohumeral ligament within the field of view during standard lateral shoulder arthroscopy in the dog. We also examine the effect of joint flexion on the field of view of the biceps tendon. This was a cadaveric study using 21 shoulders of large breed dogs. Each shoulder was explored with a 30-degree arthroscope using standard lateral ports. For each supporting structure, the margins within the arthroscopic field of view were marked with ink. In 11 shoulders, the distal margin of the biceps tendon was identified and marked first with the limb at a standing angle and then in flexion. The margins of the cranial border of the medial glenohumeral ligament were marked at the standing angle. In 10 additional shoulders, the margins of the subscapularis tendon were evaluated. Each joint was fully dissected and the portion of each stabilizing structure within the field of view was quantified. Fifty-eight percent of the cranial border of the medial glenohumeral ligament was within the arthroscopic view. At a standing angle, 48% of the intra-articular length of the biceps tendon was within the arthroscopic view, compared to 63% with the limb flexed. Twenty percent of the subscapularis tendon was within the arthroscopic view. A significant portion of the biceps tendon and medial stabilizing structures of the canine shoulder are outside the field of view of arthroscopy through a standard lateral approach. The limitations of the arthroscopic field of view should be appreciated when evaluating the shoulder.

Magnetic resonance imaging could precisely define the mean value of tendon thickness in partial rotator cuff tears

PurposeRotator 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.MethodsFrom 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.ResultsOverall, 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).ConclusionThe 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.Level of evidenceLevel II, Retrospective Comparative Trial

Correlation of anthropometric parameters with semitendinosus tendon length in anterior cruciate ligament injured patients

Anterior cruciate ligament reconstruction (ACLR) surgery is now a common procedure performed following a tear of the anterior cruciate ligament. The length of the harvested hamstring tendon is critical to the outcome of the surgery as it may influence the final length and thickness of the graft. The goal of this study was to attempt to establish a relation- ship between the height, weight and body mass index and the harvested length of the semitendinosus tendon of patients having ACLR surgery. This was a retrospective study. The weight, height, and body mass index (BMI) of patients for primary anterior cruciate ligament reconstruction were noted. The average length of the tendon was noted. The correla- tion between each of these anthropometric parameters and the tendon length was estimated. The range of values for the semitendinosus length, height and weight in males and females respectively were 24-39cm (31.26 +/- 2.93) and 26-35cm (29.26 +/- 2.08); 1.6-1.96 m and 1.65-1.8m; and 52-110kg and 60-106kg. Only the height revealed a moderate correlation with the length of the harvested tendon among the male patients. Linear regression analyses yielded the equation Sem- itendinosus tendon length = 23.25xheight-10.28 at a p-value of 0.002. Patient height could be predictive of the length of the harvested semitendinosus tendon.

Structural Musculotendinous Parameters That Predict Failed Tendon Healing After Rotator Cuff Repair.

Healing of the rotator cuff after repair constitutes a major clinical challenge with reported high failure rates. Identifying structural musculotendinous predictors for failed rotator cuff repair could enable improved diagnosis and management of patients with rotator cuff disease. To investigate structural predictors of the musculotendinous unit for failed tendon healing after rotator cuff repair. Cohort study; Level of evidence, 2. Included were 116 shoulders of 115 consecutive patients with supraspinatus (SSP) tear documented on magnetic resonance imaging (MRI) who were treated with an arthroscopic rotator cuff repair. Preoperative assessment included standardized clinical and imaging (MRI) examinations. Intraoperatively, biopsies of the joint capsule, the SSP tendon, and muscle were harvested for histological assessment. At 3 and 12 months postoperatively, patients were re-examined clinically and with MRI. Structural and clinical predictors of healing were evaluated using logistic and linear regression models. Structural failure of tendon repair, which was significantly associated with poorer clinical outcome, was associated with older age (β = 1.12; 95% CI, 1.03 to 1.26; P = .03), shorter SSP tendon length (β = 0.89; 95% CI, 0.8 to 0.98; P = .02), and increased proportion of slow myosin heavy chain (MHC)-I/fast MHC-II hybrid muscle fibers (β = 1.23; 95% CI, 1.07 to 1.42; P = .004). Primary clinical outcome (12-month postoperative Constant score) was significantly less favorable for shoulders with fatty infiltration of the infraspinatus muscle (β = -4.71; 95% CI, -9.30 to -0.12; P = .044). Conversely, a high content of fast MHC-II muscle fibers (β = 0.24; 95% CI, 0.026 to 0.44; P = .028) was associated with better clinical outcome. Both decreased tendon length and increased hybrid muscle fiber type were independent predictors for retear. Clinical outcome was compromised by tendon retearing and increased fatty infiltration of the infraspinatus muscle. A high content of fast MHC-II SSP muscle fibers was associated with a better clinical outcome. NCT02123784 (ClinicalTrials.govidentifier).

Evaluation of the morphometric features of Achilles tendon with tendinopathy: an MRI study

Objectives: The Achilles tendon, the biggest tendon in the body, transmits the mechanical force received from the body to the ankle through the calcaneus. The aim of this study was to evaluate the effects of morphometric characteristics of the soleus and gastrocnemius muscles that make up the Achilles tendon on tendinopathy by MRI. Methods: Foot magnetic resonance images of 128 patients (121 males and 107 females) were retrospectively analyzed. The cases were divided into two groups, the tendinopathy group and the control group. The length and the thickness of the Achilles tendon and the distance of the maximum thickness from the calcaneal insertion were measured in both groups and evaluated for differences between the groups and between genders.Results: In the comparison between genders, the thickness of the Achilles tendon and the distance of the maximum thickness to the calcaneal insertion were higher in males than in females. The length and the thickness of the Achilles tendon was significantly increased in the tendinopathy group compared to the control group. Conclusion: In this study, we investigated the relationship between Achilles tendinopathy and the morphometric properties of the muscles forming the Achilles tendon. The results of our study showed that Achilles tendon length and tendon thickness increased in patients with tendinopathy compared to the control group.

Muscle morphology and architecture of the medial gastrocnemius between typically developing children with different ancestral background.

Muscle ultrasonography is frequently used to improve the understanding of musculoskeletal impairments in children with spastic cerebral palsy (SCP). So far, most studies on muscle morphology and architecture have included typically developing children and children with SCP with similar ancestry, being mainly Caucasian. Less is known about differences in muscle morphology between children with different ancestral backgrounds. Therefore, the aim of this study was to compare muscle morphology and architecture of the medial gastrocnemius in typically developing children with African, South Asian and Southeast Asian descent from Suriname. This explorative cohort study identified children as Maroon (Ghana, African descent), Hindustani (India, South Asian) or Javanese (Indonesia, Southeast Asian), aged 5-10 years. Using 3D freehand ultrasound with the subject prone, the following medial gastrocnemius parameters were defined: muscle tendon unit (MTU) length, muscle belly length, tendon length, muscle volume, muscle thickness, anatomical cross-sectional area (ACSA), fascicle length, pennation angle, and physiological cross-sectional area (PCSA). In addition, differences between ancestral groups were assessed for the length of the MTU, muscle, tendon and fascicles in two passive stretch conditions corresponding to an externally applied joint torque of 1Nm and 4Nm. One-way ANOVA with post hoc t-tests were used to investigate differences between the ancestral groups. In total, 100 Hindustani (n = 34), Javanese (n = 34) and Maroon (n = 32) children were included. For statistical analyses, we matched the children by age, which resulted in groups of 25 children per ancestral group (n = 75). There were no differences found in MTU length, muscle belly length, ACSA, PCSA and muscle volume. Tendon length, fascicle length and pennation angle were different between ancestral groups. Compared to Javanese children, tendon length was longer (p = 0.001) and pennation angle (p = 0.001) was larger in Maroon children and fascicle length was shorter in both Maroon and Hindustani children (p < 0.001). While there was a difference found in MTU length at different conditions of passive stretch between ancestries, no differences were found in the muscle, tendon and fascicles. This is the first study that investigated macroscopic morphological and architectural parameters for the medial gastrocnemius in one extended cohort of typically developing children, stratified in three ancestral subgroups. The current results imply that ancestry-specific reference data for children are needed, especially for tendon length, fascicle length and pennation angle when investigating altered muscle morphology in neurological or neuromuscular pathologies, such as SCP. Future studies should report the ancestral background when describing muscle morphology and architecture of children and ancestral specifications should be included in normative databases.

Specific collagen peptides increase adaptions of patellar tendon morphology following 14-weeks of high-load resistance training: A randomized-controlled trial

ABSTRACT The purpose of this study was to investigate the effect of a supplementation with specific collagen peptides (SCP) combined with resistance training (RT) on changes in structural properties of the patellar tendon. Furthermore, tendon stiffness as well as maximal voluntary knee extension strength and cross-sectional area (CSA) of the rectus femoris muscle were assessed. In a randomized, placebo-controlled study, 50 healthy, moderately active male participants completed a 14-week resistance training program with three weekly sessions (70–85% of 1 repetition maximum [1RM]) for the knee extensors. While the SCP group received 5g of specific collagen peptides daily, the other group received the same amount of a placebo (PLA) supplement. The SCP supplementation led to a significant greater (p < 0.05) increase in patellar tendon CSA compared with the PLA group at 60% and 70% of the patellar tendon length starting from the proximal insertion. Both groups increased tendon stiffness (p < 0.01), muscle CSA (p < 0.05) and muscular strength (p < 0.001) throughout the intervention without significant differences between the groups. The current study shows that in healthy, moderately active men, supplementation of SCP in combination with RT leads to greater increase in patellar tendon CSA than RT alone. Since underlying mechanisms of tendon hypertrophy are currently unknown, further studies should investigate potential mechanisms causing the increased morphology adaptions following SCP supplementation. Trial registration: German Clinical Trials Register identifier: DRKS00029244..

Optimization Design Method of Tendon-Sheath Transmission Path Under Curvature Constraint

The application requirements of the tendon-sheath mechanism in the field of precision machinery are becoming increasingly extensive. However, the contact friction between the tendon and sheath seriously affects the transmission accuracy. In the case of unavoidable friction, optimizing the tendon transmission path to reduce tension loss and elastic deformation has become an important research direction. In this article, the influence law of the tendon transmission path on the tension and displacement transmission is obtained using the two parameters related to the curvature of the transmission path: total bending angle and equivalent tendon length. Then, based on the optimal control theory and minimum principle, the different transmission path solutions of the minimum tension loss, the minimum tendon deformation, and the coupling of tension and displacement are obtained; the numerical optimization method verifies the correctness of the proposed theory. Finally, an optimal design of a tendon-constrained synchronous rotation mechanism for the manipulator is carried out, and the linkage performance is greatly improved by optimizing the transmission path.

More than energy cost: multiple benefits of the long Achilles tendon in human walking and running.

Elastic strain energy that is stored and released from long, distal tendons such as the Achilles during locomotion allows for muscle power amplification as well as for reduction of the locomotor energy cost: as distal tendons perform mechanical work during recoil, plantar flexor muscle fibres can work over smaller length ranges, at slower shortening speeds, and at lower activation levels. Scant evidence exists that long distal tendons evolved in humans (or were retained from our more distant Hominoidea ancestors) primarily to allow high muscle-tendon power outputs, and indeed we remain relatively powerless compared to many other species. Instead, the majority of evidence suggests that such tendons evolved to reduce total locomotor energy cost. However, numerous additional, often unrecognised, advantages of long tendons may speculatively be of greater evolutionary advantage, including the reduced limb inertia afforded by shorter and lighter muscles (reducing proximal muscle force requirement), reduced energy dissipation during the foot-ground collisions, capacity to store and reuse the muscle work done to dampen the vibrations triggered by foot-ground collisions, reduced muscle heat production (and thus core temperature), and attenuation of work-induced muscle damage. Cumulatively, these effects should reduce both neuromotor fatigue and sense of locomotor effort, allowing humans to choose to move at faster speeds for longer. As these benefits are greater at faster locomotor speeds, they are consistent with the hypothesis that running gaits used by our ancestors may have exerted substantial evolutionary pressure on Achilles tendon length. The long Achilles tendon may therefore be a singular adaptation that provided numerous physiological, biomechanical, and psychological benefits and thus influenced behaviour across multiple tasks, both including and additional to locomotion. While energy cost may be a variable of interest in locomotor studies, future research should consider the broader range of factors influencing our movement capacity, including our decision to move over given distances at specific speeds, in order to understand more fully the effects of Achilles tendon function as well as changes in this function in response to physical activity, inactivity, disuse and disease, on movement performance.

Intermuscular differences in force generation ability among biarticular hamstring muscles during the late swing phase in maximal speed sprinting

ABSTRACT We aimed to investigate how intermuscular muscle-tendon architectural differences among biarticular hamstring muscles (biceps femoris long head [BFlh], semimembranosus [SM] and semitendinosus [ST]) influence intermuscular differences in muscle force during the late swing phase in maximal speed sprinting. Using a musculoskeletal model, we estimated the muscle-tendon kinematics, muscle force，and force generation ability, defined by force-length-velocity properties and pennation angle, of the biarticular hamstring muscles in 40 male athletes during the late swing phase. SM force generation ability was smaller during the first half of the late swing phase and larger during the second half than the BFlh and ST. The intermuscular differences in force generation ability were caused by the intermuscular differences in time-varying muscle-tendon unit, muscle fibre and tendon lengths, which might be affected by the muscle-tendon architecture of this model, particularly optimal muscle fibre length, tendon slack length and insertion location. Moreover, the peak muscle force was achieved earlier in the BFlh and ST than in the SM. These findings suggest that intermuscular differences in muscle-tendon architecture among the biarticular hamstring muscles can induce intermuscular differences in time-varying muscle force by influencing time-varying force generation ability and muscle-tendon kinematics during the late swing phase.

Height is a predictor of hamstring tendon length and ACL graft characteristics in adolescents

BackgroundKnowing the potential hamstring tendon length is relevant for planning ligament reconstructions in children and adolescents, as it is not uncommon to encounter small hamstring tendons intraoperatively. The aim of this study is to predict semitendinosus and gracilis tendon length based on anthropometric values in children and adolescents. The secondary aim is to analyse hamstring tendon autograft characteristics in a closed socket anterior cruciate ligament reconstructions and to evaluate the relationship with anthropometric variables. The hypothesis of this study was that height is predictor of hamstring tendon length and thereby graft characteristics.MethodsThis observational study included two cohorts of adolescents undergoing ligament reconstructions between 2007–2014 and 2017–2020. Age, sex, height and weight were recorded preoperatively. Semitendinosus and gracilis tendon length and graft characteristics were measured intraoperatively. Regression analysis was performed on tendon length and anthropometric values. Subgroup analyses of the closed socket ACL reconstruction were performed and the relation between anthropometric values and graft characteristics were analysed.ResultsThe population consisted of 171 adolescents from 13 to 17 years of age, with a median age of 16 years [IQR 16–17]. The median semitendinosus tendon length was 29 cm [IQR 26–30] and gracilis tendon length was 27 cm [IQR 25–29]. Height was a significant predictor of semitendinosus and gracilis tendon length. Subgroup analysis of the closed socket ACL reconstructions showed that in 75% of the procedure, the semitendinosus tendon alone was sufficient to create a graft with a minimum diameter of 8.0 mm.ConclusionsHeight is a significant predictor of semitendinosus and gracilis tendon length in adolescents between 13 and 17 years of age and outcomes are similar to data in adults. In 75% of the closed socket ACL reconstructions, the semitendinosus tendon alone is sufficient to create an adequate graft with a minimum diameter of 8 mm. Additional use of the gracilis tendon is more often necessary in females and shorter patients.Level of evidence3

Poster 293: Relationship between patellar tendon length and surgical treatment for patellar tendinosis

Objectives: Patellar tendinitis is a relatively common overuse injury that typically resolves with rehabilitation alone, however if it progresses to recalcitrant patellar tendinosis (RPT), surgical intervention is typically recommended. Patella alta, which has commonly been shown to lead to patellar dislocations, has recently shown to be related to patellar tendinitis. However, the relationship between patella alta and patellar tendinosis severe enough to warrant surgical intervention is unknown. The purpose of this study was to determine the association between patellar tendon length and surgical treatment for RPT. Methods: A cohort of 45 patients who were scheduled for surgery due to RPT, planning to receive a partial patellar tendinectomy, were retrospectively reviewed. A group of patients consented into a different study, planning to have an anterior cruciate ligament reconstruction (ACLR), were used as a control group. Exclusion criteria for the control group included previous patellar tendinosis. For both groups, the patellar tendon was measured preoperatively on a lateral radiograph with the knee in 60° of flexion, from the distal aspect of the inferior pole of the patella to the insertion site on the tibial tubercle. Other variables assessed were primary sport played and preoperative noninvolved quadriceps strength, measured isokinetically and normalized to body weight. The RPT patients were matched to the ACLR patients based on sex, height, and weight, leaving 45 patients in each group. Results: Mean age for the ACLR group was 26.0 ± 10.6 years and 25.1 ± 10.6 years for the RPT group. The groups had similar mean height (ACLR 70.2”, RPT 70.9”) and weight (ACLR 183.0 lbs, RPT 179.0 lbs), along with identical sex distribution with both having 71% males. Patients in the RPT group had statistically significantly longer patellar tendon lengths at 57.6 ± 7.4 mm compared to the ACLR group at 46.1 ± 7.5 mm, p&lt;.001. The most frequent sports played for those in the RPT group were basketball (38%) and volleyball (22%); whereas for the ACLR group, it was basketball (22%) and football (20%). Those in the RPT group were not found to have a statistically significantly higher distribution of any individual sport played, however when the jumping sports of basketball and volleyball were combined, the RPT group showed a statistically significantly higher distribution of patients playing these sports compared to the ACLR group (60% vs 31%, p=.006). Isokinetic quadriceps strength failed to show a statistically significant difference between groups, p=.358. Conclusions: After taking into account sex, height, and weight, patients scheduled for surgery due to RPT had longer patellar tendons compared to those without a history of patellar tendinosis. Patients with RPT are also more likely to play jumping sports compared to those who sustained an ACL tear. Those with longer than normal patellar tendons who are diagnosed with patellar tendinitis, before it progresses to RPT, should consider rehabilitation and tailor their workload to avoid symptom progression and ultimately surgery.

Poster 294: Patellar Tendon Insertion is Not Distalized following Tibial Tubercle Osteotomy with Distalization

Objectives: Patella alta is a common anatomic risk factor in patients with patellofemoral instability and/or patellofemoral cartilage lesions, occurring in nearly 25% of these patients. Distalization tibial tubercle osteotomy (TTO) is effective in patients with patella alta in association with patellofemoral instability and cartilage lesions. Prior studies have suggested that increased patellar tendon length itself is a risk factor for recurrent patellofemoral instability, and have proposed the addition of a patellar tendon tenodesis via placement of a suture anchor proximal to the distalization TTO. However, concerns regarding increased patellofemoral cartilage stresses with addition of patellar tendon tenodesis have limited its adoption. The purpose of this study was to evaluate patellar tendon length and alignment parameters on preoperative and postoperative MRI and to evaluate patient reported outcomes (PROs) following distalization tibial tubercle osteotomy (TTO) without patellar tendon tenodesis in patients with patella alta. Methods: We conducted a retrospective review of 20 adult patients who underwent distalization TTO for patellar alta at our institution (December 2014-August 2021). All patients underwent preoperative and postoperative magnetic resonance (MR) imaging of the affected knee. Distalization TTO utilized a wedge-shaped osteotomy measuring ˜5cm in length and was fixed with two 4.5mm bicortical fully threaded screws following TT transfer. Caton-Deschamps (CDI), axial and sagittal TT-TG indices1, patellar tendon length and distances from tibial plateau to patellar tendon insertion and tibial tubercle were assessed (Figure 1). PROs included IKDC Subjective Knee Evaluation, KOOS Quality of Life Form, Kujala Anterior Knee Pain From, and Veterans RAND 12 Item Mental (VR12-MH) and Physical Health (VR12-PH) Surveys. Clinical data, including demographics, complication and perioperative data, was obtained from preoperative and postoperative charts in our electronic medical record. Results: Average age at time of surgery was 27.4 years (range: 14 – 42 years) and all patients were female. Average BMI was 24.9 +/- 4.4 kg/m2. Eleven patients (55%) were diagnosed with isolated patellofemoral cartilage lesions, four patients (20%) were diagnosed with patellofemoral instability without associated cartilage lesions and five patients (25%) were diagnosed with both instability and cartilage lesions. At the time of TTO distalization, eleven patients (55%) underwent matrix-induced autologous chondrocyte implantation (MACI), nine patients (45%) underwent MPFL reconstruction, four patients (20%) underwent lateral release/lengthening, and three patients (15%) underwent osteochondral allograft (OCA) implantation. Fourteen patients (70%) underwent anteromedialization of the tibial tubercle in addition to distalization. Radiographic parameters demonstrated improved patellar height (CDI decreased from 1.36 to 1.11 (p &lt; 0.001), improved rotational alignment (axial TT-TG decreased from 14.3mm to 11.1mm (p = 0.018)) and anteriorization of the TT (sagittal TT-TG increased from -4.3mm to -1.4mm (p = 0.037)) following distalization TTO. Distance from the tibial plateau to the PT insertion decreased from 20.1mm preoperatively to 17.9mm postoperatively (p&lt; 0.020) and patellar tendon length decreased from 53.4mm preoperatively to 50.0mm postoperative (p &lt; 0.001). Average distalization was 6.4mm. IKDC scores increased from 37.1 to 60.5 (p = 0.011), KOOS QOL scores increased from 19.5 to 42.1 (p &lt; 0.001), Kujala scores increased from 50.9 to 70.6 (p = 0.018), VR12-MH scores increased from 52.7 to 59.2 (p = 0.024) and VR12-PH scores increased from 35.1 to 41.7 (p = 0.009). Of the patients with preoperative patellofemoral instability, there were no cases of recurrent instability postoperatively. Ten patients (50%) underwent elective removal of hardware of TTO screws at an average of 10.7 months. There were four (20%) complications in this cohort, with two cases (10%) of postoperative arthrofibrosis requiring manipulation under anesthesia, one case (5%) of postoperative MRSA infection of the MPFL graft and one case (5%) of tibial tubercle delayed union requiring bone grafting and revision fixation. Conclusions: Distalization TTO without patellar tendon tenodesis is an effective surgical technique for improving patellar height in patients with patella alta and patellofemoral instability and/or patellofemoral cartilage lesions, with improvements in radiographic parameters and PROs postoperatively. There were no cases of recurrent instability in this cohort. The patellar tendon insertion does not appear to be significantly distalized following distalization TTO, likely related to scarring of the patellar tendon just proximal to the osteotomy site postoperatively. Given the complexity of risk factors associated with patellofemoral instability and patellofemoral cartilage lesions, distalization TTO provides an additional tool for patient-specific surgical management, without the need for patellar tendon tenodesis.

Anatomical and Biomechanical Characteristics of Peroneus Longus Tendon: Applications in Knee Cruciate Ligament Reconstruction Surgery.

The peroneus longus tendon is used in many orthopedic surgeries to regenerate the external ligaments of the knee. This study aims to evaluate some anatomical, biomechanical, and load-bearing properties of the peroneus longus tendon for use in cruciate ligament reconstruction. The study design is a cross-sectional description. The study subjects were 20 samples of the peroneus longus tendon from fresh carcasses. The leg is still intact, not crushed, is well preserved, and it has never been used in research. The average length of the peroneus longus tendon was 29.25 ± 2.1 cm, and the average distance from the peroneus longus tendon to the deep peroneal nerve was 71.1 ± 8.63 mm. The peroneus longus tendon did not have an accessory ligament, the maximum tension of the peroneus longus tendon was 1170.4 ± 203 N, and the maximum length at break was 14.29 ± 3.88 mm. Removing the peroneus longus tendon will not affect the surrounding anatomical components. The maximum breaking force and the diameter of the peroneus longus tendon are similar to other graft materials, such as the hamstring tendon and patellar tendon.

Reliability of mechanical properties of the plantar flexor muscle tendon unit with consideration to joint angle and sex.

The reliability of mechanical measures can be impacted by the protocol used, including factors such as joint angle and the sex of participants. This study aimed to determine the inter-day reliability of plantar flexor mechanical measures across ankle joint angles and contraction types and consider potential sex-specific effects. 14 physically-active individuals participated in two identical measurement sessions involving involuntary and voluntary plantar flexor contractions, at three ankle angles (10° plantarflexion (PF), 0° (anatomical zero (AZ)), and 10° dorsiflexion (DF)), while torque and surface EMG were recorded. The reliability of mechanical parameters of maximal voluntary torque (MVT), rate of torque development (RTD), electromechanical delay, and tendon stiffness were assessed using absolute and relative reliability measures. MVT measures were reliable across ankle angles. RTD measures showed good group level reliability and moderate reliability for an individual during the early phase of contraction across ankle angles. Explosive voluntary torque measures tended to be less reliable from 50 ms onward, with varied reliability across angles for late-phase RTD. Tendon stiffness demonstrated the best reliability at the DF angle. Sex-based differences in the reliability of tendon measures found that females had significantly different initial tendon length between testing sessions. Despite this, tendon excursion, force, and stiffness measures demonstrated similar reliability compared to males. Ankle angle changes influence the reliability of plantar flexor mechanical measurements across contraction types, particularly for voluntary contractions. These results highlight the importance of establishing potential protocol effects on measurement reliability prior to quantifying plantar flexor mechanical measures.

Muscle fascicle and sarcomere adaptation in response to Achilles tendon elongation in an animal model.

Permanent loss of muscle function seen after an Achilles tendon rupture may partly be explained by tendon elongation and accompanying shortening of the muscle. Muscle fascicle length shortens, serial sarcomere number is reduced, and the sarcomere length is unchanged after Achilles tendon transection (ATT) and these changes are mitigated with suturing. Controlled laboratory study. Two groups of rats underwent ATT on one side with a contralateral control (CTRL): A) ATT with 3 mm removal of the Achilles tendon and no suturing (substantial tendon elongation), and B) ATT with suture repair (minimal tendon elongation). The operated limb was immobilized for 2 weeks to reduce load. Four weeks after surgery the rats were euthanized, and hindlimbs were analyzed for tendon length, gastrocnemius medialis (GM) muscle mass, length, fascicle length, sarcomere number and length. No differences were observed between the groups, and in both groups the Achilles tendon length was longer (15.2%, P<0.001), GM muscle mass was smaller (17.5%, P<0.001), and muscle length was shorter (8.2%, P<0.001) on the ATT compared to CTRL side. GM fascicle length was shorter (11.2%, P<0.001), and sarcomere number was lower (13.8%, P<0.001) on the ATT side in all regions. Sarcomere length was greater in the proximal (5.8%, P<0.001) and mid (4.2%, P=0.003), but not distal region on the ATT side. In this animal model, regardless of suturing, ATT resulted in tendon elongation, loss of muscle mass and length and reduced serial sarcomere number, which resulted in an "overshoot" lengthening of the sarcomeres.

Evaluation of transfer length of CFRP tendon in pretensioned concrete beam using embedded FBG sensors

This study aimed to determine the transfer length of pretensioned concrete beams strengthened with carbon fiber-reinforced polymer (CFRP) using a fiber Bragg grating (FBG) sensor. The transfer length is the distance along the tendon that is critical to ensuring effective prestressing force and structural capacity of the concrete beam. Typically, electric strain gauges are used to measure the transfer length, but they can produce measurement errors due to installation errors and data noise. In this study, an FBG sensor was embedded in a CFRP tendon instead of a strain gauge, enabling accurate measurements of tendon strain and transfer length.

Endoscopically Assisted Percutaneous Harvesting of the Flexor Hallucis Tendon in Zone 2: An Anatomical Study.

Flexor hallucis longus (FHL) transfer is a well-established method for treating chronic Achilles tendon ruptures and tendinopathy. Harvesting of the FHL tendon in zone 2 results in greater length but is also associated with an increased risk of injury to the medial plantar nerve and requires an additional plantar incision. Because of the anatomic proximity of the FHL tendon to the tibial neurovascular bundle in zone 2, the purpose of this study was to investigate the risk of vascular or nerve injury with arthroscopic assisted percutaneous tenotomy in zone 2 of the FHL tendon. Endoscopically assisted percutaneous FHL transfer was performed on 10 right lower extremities from 10 cadaveric human specimens. The FHL tendon lengths and the relationship between FHL tendon and the tibial neurovascular bundle at zone 2 was analyzed. We observed a complete transection of the medial plantar nerve in 1 case (10%). The mean length of the FHL tendon was 54.7 ± 9.5 mm and the mean distance from the distal stump of the FHL tendon to local neurovascular structures was 1.3 ± 0.7 mm. There is a risk of neurovascular injury after endoscopic FHL tenotomy in zone 2. The tenotomy site is within 2 mm of the local neurovascular structures in the majority of cases. The additional length gained from this technique is unlikely to be required for the majority of FHL tendon transfer procedures. If additional length is needed, we would recommend the use of intraoperative ultrasonography or a mini-open approach to minimize injury risk. Level V, expert opinion.

Clinical outcomes and tendon lengthening after arthroscopic rotator cuff repair.

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. 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 24months 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 2years 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. 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 24months after surgery was significantly longer than those before surgery (26.7±5.8mm, 27.9±6.6mm, 28.5±5.6mm, and 21.5±5.1mm, respectively). From before surgery to 24months after surgery, the MTJ location moved 8.4±8.6mm laterally and the tendon length increased 7.0±6.1mm. 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). 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.