Tendon Elongation Research Articles

Zigzag tenotomy of the extensor hallucis longus through minimally invasive surgery in cadaveric specimens: description of a new technique

BackgroundLengthening of the extensor hallucis longus (EHL) is performed to address various forefoot pathologies. The retraction of this tendon is strongly associated with the Hallux Abductus Valgus (HAV) deformity. Minimally Invasive Surgery (MIS) lengthening of the EHL is carried out in combination with other surgical techniques for HAV bone realignment. It is performed without ischemia, using local anesthesia and sedation if required by the patient. One of the advantages of this technique is immediate ambulation with a postoperative shoe without the need for a cast. The objective of the research was to demonstrate the efficacy and safety of the minimally invasive technique for lengthening the tendon in patients with HAV.Materials and methodsThe procedures were performed on 11 fresh cryopreserved cadaveric feet. HAV surgery was performed through dorsomedial and dorsolateral portals for Reverdin-Isham, Akin and adductor tenotomy. In addition, EHL tendon elongation was performed using the Beaver 67 MIS scalpel through an incomplete zigzag tenotomy. The specimens used did not present any type of disease nor had they undergone previous surgeries that could affect the technique. First, the plantar flexion of the metatarsophalangeal joint was measured with a goniometer to establish the degrees of this joint before proceeding with the technique, the tenotomy was performed and remeasured and finally the osteotomy was performed. In addition, an anatomical dissection of cadaveric specimens was performed and various anatomical and surgical relationships were analyzed and measured.ResultsThe data indicate that, after performing zigzag tenotomy, there is an average improvement of 13.91 degrees in plantar flexion.ConclusionsThe study confirms the effectiveness and safety of elongating the extensor hallucis longus tendon of the hallux using minimally invasive surgery. The zigzag technique for tendon elongation may be considered a viable minimally invasive treatment option for addressing tendon hyperextension in patients with HAV.

H-Loop Knotless Double-Row Repair Versus Krackow Repair for Achilles Tendon Rupture: A Biomechanical Study in a Cadaveric Model.

Surgery is widely recognized as an effective treatment for Achilles tendon rupture; however, there remains debate regarding the optimal surgical approach. To compare the biomechanical properties of 2 techniques, the H-loop knotless double-row (HLDR) suture repair and the Krackow suture repair, for Achilles tendon rupture in a cadaveric model. Controlled laboratory study. Ten matched Achilles tendon specimens from 5 male and 5 female donors were obtained. Each specimen from a matched pair was randomly distributed to 1 of 2 repair groups, the HLDR group or the Krackow group. Tendon elongation was recorded after exposure to 10, 100, 200, 400, 600, 800, and 1000 load cycles. The gap distance after application of a 100-N force, the force needed to produce a 2-mm gap, and the load to failure were measured. All biomechanical properties were compared between the HLDR and Krackow groups using the paired t test. The HLDR group consistently exhibited significantly less elongation than the Krackow group after exposure to the 7 load cycles (P < .01 for all). In addition, the HLDR group exhibited a significantly smaller gap distance after applying a 100-N force (0.30 ± 0.02 vs 8.10 ± 0.46 mm for Krackow group), required significantly more force to generate a 2-mm gap (419.68 ± 39.48 vs 22.29 ± 3.40 N for the Krackow group), and had a significantly higher ultimate failure load (519.91 ± 57.29 vs 220.30 ± 19.27 N for the Krackow group) (P < .01 for all). The study findings demonstrated that the HLDR technique had more advantages compared with the Krackow technique with regard to elongation after different cyclic loadings, gap distance after a 100-N load, force needed to produce a 2-mm gap, and load to failure in a cadaveric model. The HLDR technique could be a viable option for Achilles tendon rupture repair.

Effects of minute oscillation stretching training on muscle and tendon stiffness and walking capability in people with type 2 diabetes.

we investigated the effects of a 10week training program (i.e., minute oscillatory stretching; MOS) on the mechanical responses and walking capability in people with type 2 diabetes (T2D). seventeen T2D patients performed maximum voluntary contractions of the plantar flexor muscles during which Achilles tendon stiffness (kT) and muscle-tendon stiffness (kM) were evaluated at different percentages of the maximum voluntary force (MVC). In addition, each participant was requested to walk at different walking speeds (i.e. 2, 3, 4, 5, and 6kmh-1) while their net energy cost of walking (Cnet), cumulative EMG activity per distance travelled (CMAPD) and kinematic parameters (step length, step frequency, the ankle/knee range of motion) were evaluated. maximum tendon elongation increased after MOS training, and kT significantly decreased (between 0 and 20% of MVC). No differences were observed for muscle elongation or kM after training. Cnet decreased after training (at the slowest tested speeds) while no changes in CMAPD were observed. Step length and ankle ROM during walking increased after training at the slowest tested speeds, while step frequency decreased; no significant effects were observed for knee ROM. these results indicate the effectiveness of 10weeks of MOS training in reducing tendon stiffness and the energy cost during walking in people with T2D. This training protocol requires no specific instrumentation, can be easily performed at home, and has a high adherence (92 ± 9%). It could, thus, be useful to mitigate mechanical tendon deterioration and improve physical behaviour in this population.

Rehabilitation and Return to Sports after Achilles Tendon Repair.

Rehabilitation protocols post-Achilles tendon repair vary widely, particularly regarding weight bearing (WB) and immobilization duration, impacting recovery trajectories significantly. This commentary focuses on rehabilitation strategies following acute Achilles tendon repair (ATR), emphasizing early mobilization and progressive loading. Techniques such as blood flow restriction training (BFRT) and progressive loading to restore strength and tendon mechanical properties are discussed in the context of optimizing recovery, minimizing tendon elongation and facilitating safe return to sport (RTS). This manuscript highlights current evidence and clinical insights to guide practitioners in optimizing rehabilitation protocols for athletes recovering from ATR, aiming to improve functional outcomes and support safe return to athletic activity.

Reconstruction of Chronic Soft Tissue Mallet Fingers: Outcomes of Step-Plasty vs. Purse-String Suture.

After failed conservative therapy or in the absence of any intervention, a rupture of the digital subcutaneous extensor tendon at the distal interphalangeal (DIP) joint, known as mallet finger, may lead to a chronic extension deficit due to excessive scarring and tendon elongation. Various surgical techniques to restore the extension of the distal phalanx have been proposed, but an optimal approach has not yet been established. To tighten the extensor tendon, a purse-string suture can be applied. Although it has shown efficacy, it can result in significant bulging and scar formation. Using the "abbreviato" technique, the elongated part of the extensor tendon is excised, and the tendon is re-sutured. Also, tenodesis has been described, particularly in pediatric cases. In this retrospective follow-up study, we aimed to investigate if the step-plasty procedure previously described by Baumeister provides comparable, if not superior, functional and aesthetic outcomes compared to existing techniques for patients with chronic mallet finger. In this retrospective study, a consecutive series of 68 patients with chronic mallet fingers was enrolled. Patients were treated surgically using step-plasty of the respective extensor tendon. After skin incision and tenolysis, the elongated extensor tendon was incised in a Z-like fashion and stepwise resected in the transverse portion of the Z. The functional and aesthetic effects of this step-plasty technique were compared with results of 44 patients previously treated using purse-string sutures of the extensor tendon and evaluated using Crawford's and Levante's criteria. In all patients undergoing the step-plasty procedure, the extension deficit was significantly reduced from an average of 42 degrees preoperatively to 11 degrees postoperatively. In contrast, the control group treated by purse-string sutures showed a slightly higher postoperative extension deficit of 15 degrees. According to Levante's criteria, the results of our step-plasty procedure were significantly better than those achieved with purse-string sutures. Our study demonstrated that the treatment of older or chronic subcutaneous extensor tendon ruptures using the step-plasty technique led to a significant reduction in extension deficits. According to Levante's criteria, the postoperative outcome was significantly better in comparison to the purse-string suture technique. Additionally, no skin resection was required to improve the extension capability of the distal finger joint, compared to established surgical procedures.

Effects of tendon elongation on plantar pressure and clinical outcomes: A comparative analysis between open repair and minimally invasive surgery.

The aim of this study was to assess whether variances in Achilles tendon elongation are linked to dissimilarities in the plantar pressure distribution following two different surgical approaches for an Achilles tendon rupture (ATR). All patients who were treated with open or minimally invasive surgical repair (MIS) and were over 2 years post their ATR were eligible for inclusion. A total of 65 patients with an average age of 43 ± 11 years were included in the study. Thirty-five patients were treated with open repair, and 30 patients were treated with MIS. Clinical outcomes were evaluated using the American Orthopedic Foot and Ankle Society (AOFAS) and ATR Score (ATRS). Achilles tendon elongation was measured using axial and sagittal magnetic resonance imaging scans. Plantar pressure measurements for the forefoot, midfootand hindfoot during gait were divided into percentages based on total pressure, measured in g/cm2 for each area. The average AOFAS score was found 'excellent' (93 ± 2.8) in the MIS group, while it was found 'good' (87.4 ± 5.6) in the open repair group. In addition, the MIS group showed significantly superior ATRS scores (78.8 ± 7.4) compared to the open repair group (56.4 ± 15.4) (p < 0.001). The average tendon elongation in the MIS group was 11.3 ± 2 mm, while it was 17.3 ± 4.3 mm(p < 0.001) in the open repair group. While the open repair group showed significantly higher plantar pressure distribution in the initial contact and preswing phases compared to uninjured extremities, there was no significant difference between the uninjured extremities and the MIS group. In conclusion, the findings of this study demonstrated that minimally invasive surgery was associated with less tendon elongation, more proximity to the plantar pressure distributions of the uninjured extremity and superior clinical outcomes compared to open surgical repair. Therefore, minimally invasive surgery may be considered a more suitable option for acute Achilles tendon repair to achieve overall better outcomes. Level III.

NEGLECTED AND RELAPSED CLUBFOOT IN ADULTS: THE FUNCTIONAL OUTCOME OF ACUTE SURGICAL CORRECTION

BackgroundNeglected clubfoot in this series is defined as untreated equino-cavo-adducto-varus in older children, or adults. Relapsed clubfoot is the residual deformity that remains after single or multiple surgical interventions. Severe neglected clubfoot rarely exists today in developed countries, except in some emigrants from low- and middle-income countries. Acute surgical management with corrective mid-foot osteotomy and elongation of the Achilles tendon has excellent functional outcome.ObjectiveTo assess the functional outcome of acute correction of neglected Talipes-quino-varus deformity in adults.MethodsThis is cross sectional, hospital–based study that took place in Khartoum, Sudan. Forty patients were included in this study. Midfoot osteotomy and elongation of the Achilles tendon were performed to all patients. Data was collected using a questionnaire and the functional outcome has been assessed using the American Orthopaedic Foot and Ankle Society Score (AOFAS). This score was measured before surgery and one years after surgery.ResultsThe mean age was 19.9±4.7 years. Males were 25 (62.5%) and females were 15 (37.5%). The mean preoperative AOFAS score was 37.7±7.1 (poor). This score improved to 80.7±13.7 (good to excellent), two years after surgery. However, this indicates significant change in the functional outcome after the operation (P value &lt; 0.05). Excellent post-operative functional outcome was found among patients aged 18 – 23 years 18 (50%) P. value: 0.021. The majority of patients 36(90%) were fully satisfied with the operation, 2(5%) partially satisfied and 2(5%) were unsatisfied.ConclusionAcute correction of neglected and relapsed TEV with elongation of the Achilles tendon and single midfoot osteotomy has excellent functional outcome as assessed by AOFAS Score. The satisfaction with this procedure is impressive. The younger age population showed better outcomes with this procedure.

Classics. The covering of skin defect after operative correction of the talipes equino-varus

After operative correction of adduction in the first stage of operative treatment (ligamentotomy, tendon elongation etc) of neglected congenital talipes equino-varus in children aged 4–6 years, some defect of the skin on medial side of the foot arises when correct position is assumed. The author covers this defect by pedicled skin graft from the dorsal surface of the foot, using the opportunity that on lateral surface of the inverted foot there is an excess of skin in the form round protuberance covering the cuboid bone and tuberosity of the fifth metatarsal. By flattening this round protuberance the area of the skin graft increases in such extent that not only the defect may be easily covered but the whole graft can be sutured to the edges of the operative wound.

Biomechanical testing of ex vivo porcine tendons following high intensity focused ultrasound thermal ablation.

Magnetic resonance-guided focused ultrasound (MRgFUS) has been demonstrated to be able to thermally ablate tendons with the aim to non-invasively disrupt tendon contractures in the clinical setting. However, the biomechanical changes of tendons permitting this disrupting is poorly understood. We aim to obtain a dose-dependent biomechanical response of tendons following magnetic resonance-guided focused ultrasound (MRgFUS) thermal ablation. Ex vivo porcine tendons (n = 72) were embedded in an agar phantom and randomly assigned to 12 groups based on MRgFUS treatment. The treatment time was 10, 20, or 30s, and the applied acoustic power was 25, 50, 75, or 100W. Following each MRgFUS treatment, tendons underwent biomechanical tensile testing on an Instron machine, which calculated stress-strain curves during tendon elongation. Rupture rate, maximum treatment temperature, Young's modulus and ultimate strength were analyzed for each treatment energy. The study revealed a dose-dependent response, with tendons rupturing in over 50% of cases when energy delivery exceeded 1000J and 100% disruption at energy levels beyond 2000J. The achieved temperatures during MRgFUS were directly proportional to energy delivery. The highest recorded temperature was 56.8°C ± 9.34 (3000J), while the lowest recorded temperate was 18.6°C ± 0.6 (control). The Young's modulus was highest in the control group (47.3 MPa ± 6.5) and lowest in the 3000J group (13.2 MPa ± 5.9). There was no statistically significant difference in ultimate strength between treatment groups. This study establishes crucial thresholds for reliable and repeatable disruption of tendons, laying the groundwork for future in vivo optimization. The findings prompt further exploration of MRgFUS as a non-invasive modality for tendon disruption, offering hope for improved outcomes in patients with musculotendinous contractures.

Collagen Organization of Mouse Tendons and Mechanotransduction Gene Expression of Mouse Tendon Fibroblasts are Dependent on HIF1-alpha and Oxygen tension

Tendons are essential for transmitting skeletal muscle loads to bone yet tendons are unable to regenerate following load-induced injury.1–3 A major challenge in regenerating tendons lies in their low cell number, poor vascularization, and extracellular matrix (ECM) dense environment. The primary cells in tendons are fibroblasts (TFs) which form and organize the nascent collagen-rich ECM necessary for mechanical function and mechanotransduction. Eventually, TFs become embedded in this dense ECM with limited access to nutrients, where these cells also experience low levels of turnover. Development and elongation of tendon depends on the transcription factor, Scleraxis (Scx), which regulates the proliferation and differentiation of TF progenitors under mechanical loading while also promoting collagen deposition and organization.4-9 Collagen deposition is also controlled by hypoxia inducible factor-1a ( Hif1a), and we have recently shown that mouse Achilles tendons are under hypoxic stress during embryonic development, and the maturation of tendon enthesis relies on expression of Hif1a10,11. Hif1a regulates expression of Sox9 and genes associated with ECM deposition, such as Col1a1 and Col1a2.12 Yet, if and how hypoxia and Hif1a influences tendon organization and mechanotransductive gene expression remains unknown. In this study, we tested the hypothesis that both hypoxia and loss of Hif1a contribute to ECM organization in vivo and mechanotransductive gene expression in vitro. Hif1afl/wt wildtype (WT) and Hif1afl/fl; ScxCre+ ( Hif1acKO) mice were generated to study tendon ECM organization of developing (Postnatal day 14, P14) and mature (P56) Achilles tendons. Mouse hindlimbs were fixed, decalcified, paraffn sectioned, and stained with Picrosirius red to visualize collagen organization (n=3/genotype at both P14 and P56). Midsubstance Achilles tendons were imaged using brightfield and circular polarized light microscopy on an epifluorescent microscope (Leica). Images were acquired using a polarization camera and ThorCam software (ThorLabs Inc.) for quantitative polarized light microscopy (qPLI). Gene expression related to ECM ( Col1a1, Col1a2), progenitor markers ( Scx, Sox9), hypoxia ( Hif1a, Hif2a, Hilpda, Plin2), and mechanotransduction (Igfbp2, Igfbp3, and Igfbp9) was assessed using isolated and cultured mouse tail TFs from adult Hif1acKO and WT mice (n=3-4/group, age 4-6 months of age). Cells were cultured in normoxic (20% O2) or hypoxic (1% O2) conditions (for 1-wk) or were treated with a HIF stabilizer Roxadustat (FG-4592) to induce ‘pseudo-hypoxia’ or treated with a vehicle (DMSO) for 16h. RNA was isolated after 16h or 1-wk in culture and cDNA was used in SYBR-based quantitative PCR (qPCR). Data were normalized to 20% O2 conditions for fold change comparisons (2−ΔΔCq; Actb and Polr2a reference genes). Hif1acKO Achilles tendons had poor ECM organization compared to WT tendons at both ages. TFs from Hif1acKO mice had lower Hif1a expression compared to WT cells in both 20% and 1% O2. For WT TFs, Scx and Igfbp9 were downregulated in hypoxia compared to 20% O2 conditions, and the effect of hypoxia on Hif1acKO cells further downregulated Igfbp9 compared to 20% O2. Loss of Hif1a reduced Hilpda expression compared to WT TFs in hypoxia. FG treatment also resulted in increased Hilpda expression compared to hypoxia. Our findings support our hypothesis that Hif1a and hypoxia are regulators of ECM organization and mechanotransduction in mouse tendons. Identifying regulators of tendon ECM deposition and organization will inform therapeutic strategies for guided regeneration. REFERENCES: 1Fu C, et al. J Orthop Res. 2021.2Leong NL, et al. J Orthop Res. 2020. 3Shah SA, et al. J Orthop Res. 2017. 4Murchison ND, et al. Development. 2007. 5Killian ML, et al. FASEB j. 2016. 6Ideo K, et al. PLoS ONE. 2020.7Blitz E, et al. Development. 2013. 8Huang AH, et al. Development. 2019. 9Schweitzer R, et al. Development. 2001. 10Tata Z, et al. 2022, Proceedings of the ORS Annual Meeting. 11Phillips, et al. 2023, Proceedings of the ORS Annual Meeting.12Amarilio R, et al. Development. 2007. ACKNOWLEDGEMENTS: NIH NIAMS (R01AR079367, MLK; P30AR069620), NSF (CAREER 1944448, MLK). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Regional healing trajectory of the patellar tendon after bone-patellar tendon-bone autograft harvest for anterior cruciate ligament reconstruction.

Graft site morbidities after bone-patellar tendon-bone (BPTB) autograft harvest for anterior cruciate ligament reconstruction (ACLR) negatively impacts rehabilitation. The purpose of this study was to establish tendon structural properties 1-month after BPTB autograft harvest compared to the uninvolved patellar tendon, and subsequently to quantify the healing trajectory of the patellar tendon over the course of rehabilitation. Patellar tendon morphology (ultrasound) and mechanical properties (continuous shear wave elastography) from 3 regions of the tendon (medial, lateral, central) were measured in 34 participants at 1 month, 3-4 months, and 6-9 months after ACLR. Mixed models were used to compare tendon structure between limbs at 1 month, and quantify healing over 3 timepoints. The involved patellar tendon had increased cross-sectional area and thickness in all regions 1-month after ACLR. Thickness reduced uniformly over time. Possible tendon elongation was observed and remained stable over time. Tendon viscosity was uniform across the three regions in the involved limb while the medial region had higher viscosity in the uninvolved limb, and shear modulus was elevated in all three regions at 1 month. Viscosity and shear modulus in only the central region reduced over time. Statement of Clinical Significance: The entire patellar tendon, and not just the central third, is altered after graft harvest. Tendon structure starts to normalize over time, but alterations remain especially in the central third at the time athletes are returning to sport. Early rehabilitation consisting of tendon loading protocols may be necessary to optimize biologic healing at the graft site tendon.

Dynamics-Based Control and Path Planning Method for Long-Reach Coupled Tendon-Driven Manipulator

The Fukushima power station in Japan was affected by a major earthquake and tsunami in March 2011, inspecting the primary containment vessel remains difficult due to high radioactivity. Long-reach robot arms are useful in inspecting such hazardous environments, and a coupled tendon-driven mechanism enables realizing a long, light-weight, and thin manipulator. However, high elastic elongation of tendons due to gravity may lead to unstable joint control. In this paper, we introduce dynamics-based control as a feasible strategy for a long-reach tendon-driven robotic arm. Additionally, a planning method to identify the joint angle path ensuring stability is proposed. Considering stability analysis, the potential due to the tendon elasticity and gravity is evaluated and used as an index of joint stability. The rapidly exploring random tree is used as the planning algorithm. The effectiveness of the proposed method was demonstrated through the successful manipulation of a 5-kg payload by a 10-m long robotic arm.

Tendon Elongation and Function After Delayed or Standard Loading of Surgically Repaired Achilles Tendon Ruptures: A Randomized Controlled Trial

Background: Achilles tendon ruptures often result in long-term functional deficits despite accelerated (standard) rehabilitation. Purpose/Hypothesis: 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. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: 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. Results: 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. Conclusion: 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. Registration: NCT04263493 (ClinicalTrials.gov identifier).

Thyroid Eye Disease and Rare Manifestations of Severe Restrictive Strabismus with Large Hypertropia: A Case Report and Treatment Considerations

Introduction : Restrictive strabismus with large hypertropia is an infrequent manifestation of thyroid eye disease that arises due to severe thickening of the superior rectus muscle. This condition can lead to losing the visual axis in the primary gaze position, and prompt management is essential.&#x0D; Case Illustration : A Forty-seven-year-old man came to the hospital and presented with misalignment in both eyes, known for five months before admission. Ophthalmology examination revealed visual acuity for both eyes was 0.4—Large hypertropia with 50 prism diopters and exotropia with 20 prism diopters, and down shoot restrictions were found in both eyes. The patient had a history of hyperthyroidism since eight months ago and regularly took PTU medication. CT scan of the orbit showed hypertrophy on the extraocular muscle.&#x0D; Discussion : Continued fibroblast stimulation results in collagen deposition and subsequent fibrosis, ultimately leading to restrictive strabismus in TED patients. For patients with large hypertropia, the primary surgical approach remains recession of the involved restricted muscles, with or without tendon elongation surgery. Vertical rectus muscle resection is preferred for its low inflammation and restriction risk, while hemi hang-back is another suitable option.&#x0D; Conclusion : The recession of restricted muscles and tendon elongation, preferably vertical rectus muscle resection, is necessary for patients with rare manifestations of restrictive strabismus and large hypertropia in thyroid eye disease.

Variability in Outcome After Bilateral, Fluoroquinolones-Associated Achilles Tendon Rupture: A Case Report

BACKGROUND: Achilles tendon rupture can be debilitating, and there is substantial variability in outcomes after Achilles tendon rupture. Patient- and tissue-level characteristics are beginning to emerge as healing indicators with the potential of identifying impaired healing earlier in recovery. CASE PRESENTATION: Patient with fluoroquinolone-induced, bilateral Achilles tendon rupture managed nonoperatively. OUTCOME AND FOLLOW-UP: Tendon tissue level outcomes on ultrasound, strength, range of motion, and patient-reported outcomes are reported. With similar treatment of bilateral tendons, the patient achieved good healing outcomes (evidenced by limited tendon elongation and walking capacity) on one side but had limited healing (evidenced by tendon retraction and need for bracing with walking) on the other side. DISCUSSION: The findings from this case report highlight the variability of patient outcomes after Achilles tendon rupture, even when treatment and the systemic healing environment is similar. This report also demonstrates the potential clinical utility of routine ultrasound imaging to assess early tendon healing before strength and other functional outcomes can be assessed. JOSPT Cases 2024;4(1):12-18. Epub 13 November 2023. doi:10.2519/josptcases.2023.12109

INCREASED CD4+ TO CD8+ T-CELL RATIO AS A DRIVER OF IMPAIRED ACHILLES TENDON HEALING IN HUMAN PATIENTS

Early identification of patients at risk for impaired tendon healing and corresponding novel therapeutic approaches are urgent medical needs. This study aimed to clarify the role of CD3+ T-cells during acute Achilles tendon (AT) healing. Blood and hematoma aspirate were taken from 26 patients during AT reconstruction, and additional blood samples were obtained during clinical follow-up at 6, 26 and 52 weeks after surgery. T-cell subsets were analyzed by flow cytometry using CD3, CD4, CD8, CD11a, CD57 and CD28 antibodies. Clinical follow-up included functional tests, MRI assessments, and subjective questionnaires. In vitro, the functional behavior of patient-derived tenocytes was investigated in co-cultures with autologous unpolarized CD4+ or CD8+ T-cells, or IFNy-polarized CD8+ or IL17-polarized CD4+ Tcells (n=5-6). This included alterations in gene expression (qPCR), MMP secretion (ELISA), migration rate (scratch wound healing assay) or contractility (collagen gels). Analysis revealed that elevated CD4+ T-cell levels and reduced CD8+ T-cell levels (increased CD4/CD8 ratio) in hematoma aspirate and pre-operative blood were associated with inferior clinical outcomes regarding pain and function at 26 and 52 weeks. Increased levels of CD8+ -memory T-cell subpopulations in blood 6 weeks after surgery were associated with less tendon elongation. In vitro, tenocytes showed increased MMP1/2/3 levels and collagen III/I ratio in co-culture with unpolarized and/or IL17-polarized CD4+ T-cells compared to unpolarized CD8+ T-cells. This coincided with increased IL17 receptor expression in tenocytes co-cultured with CD4+ T-cells. Exposure of tenocytes to IL17-polarized CD4+ T-cells decreased their migration rate and increased their matrix contractility, especially compared to IFNy-polarized CD8+ T-cells. The CD4+ /CD8+ T-cell ratio could serve as prognostic marker for early identification of patients with impaired AT healing potential. Local reduction of CD4+ T-cell levels or their IL17 secretion represent a potential therapeutic approach to improve AT healing and to prevent weakening of the tendon ECM.

Progressive collapsing foot deformity: clinical presentation, diagnosis, and management options

Progressive collapsing foot deformity (PCFD) is a prevalent musculoskeletal disease that can cause significant deformity and disability. This review article aimed to overview the clinical presentation, diagnosis, and management options for PCFD. Google Scholar and PubMed were searched specifically for publications published up until May 2023 through several keywords. Inclusion criteria were articles on PCFD and articles published in English. The exclusion criteria were related to flexible flatfoot, vertical talus condition, and non-English articles. PCFD can present with various symptoms and signs, including elongation of the tibialis posterior tendon, hindfoot valgus deformity, forefoot abduction, weakness on the single-heel-rise test, and too-many-toes signs. The footprint assessment can be used easily and effectively to detect PCFD. Diagnosis of PCFD must be according to a thorough history taking, physical check-up, and appropriate imaging studies. Treatment options for PCFD range from conservative measures such as orthotic devices and physical therapy to more aggressive measures such as tendon transfers, arthroereisis, and implant-based reconstructions. The therapeutic plan should be individualized to the patient&amp;apos;s requirements and comorbidities. Different surgical modalities are available to manage flat foot deformity, including arthroereisis, lateral column lengthening, medializing calcaneal osteotomy, dorsal opening wedge osteotomy, and cotton osteotomy. Each intervention has its benefits and disadvantages, and the most appropriate modality should be selected according to the kind and severity of the deformity, the patient&amp;apos;s features and risk factors, and the surgeon&amp;apos;s experience. Pre- and postoperative patient-reported outcomes measurement information system scores can help to evaluate treatment outcomes.

Flextegrity arched structures for Lunar bases built from indigenous materials

Flextegrity is a broad structural concept, represented here by a chain of perforated massive segments in dry contact, coupled by a passing-through pre-tensioned tie-rod (tendon). Contact surfaces realize pure rolling along tailor-designed pitch lines, so that the relative rotation of adjacent segments determines the tendon elongation: the bending constitutive law can be optimized simply by re-shaping the contact surfaces. Flextegrity arches are placed side by side to form a vault, pressurized via an interposed air-tight membrane. The arch follows an almost complete circle (the vault approaches a tube), to minimize the actions on the foundations from internal pressure. The structure also supports a thick radiation shield above, made up of loose Lunar debris. The main characteristic is that the massive segments can be made from cast Lunar regolith, fused into solar-powered devices, whose weight is mitigated by the reduced Lunar gravity. Huge savings on mission budget are expected, because the only components from Earth are the tendons, made of high-performance lightweight carbon nanotube fibers, and the air-tight membrane. Small-scale prototypes are manufactured from cast concrete. The structural response is analyzed through a theoretical model. The concept is applied to a Moon base example, verifying compatibility with the strength of Lunar regolith under various actions, including meteoroid impact.

Neural-driven activation of 3D muscle within a finite element framework: exploring applications in healthy and neurodegenerative simulations

This paper presents a novel computational framework for neural-driven finite element muscle models, with an application to amyotrophic lateral sclerosis (ALS). The multiscale neuromusculoskeletal (NMS) model incorporates physiologically accurate motor neurons, 3D muscle geometry, and muscle fiber recruitment. It successfully predicts healthy muscle force and tendon elongation and demonstrates a progressive decline in muscle force due to ALS, dropping from 203 N (healthy) to 155 N (120 days after ALS onset). This approach represents a preliminary step towards developing integrated neural and musculoskeletal simulations to enhance our understanding of neurodegenerative and neurodevelopmental conditions through predictive NMS models.

Effects of muscular endurance and tendon extensibility on endurance of joint stiffness

ABSTRACT In some sporting events (e.g., long-distance running), the ability to maintain joint stiffness is considered an essential physical ability. However, the determinants of joint stiffness endurance remain unclear. This study aimed to examine the effects of muscular endurance and tendon extensibility on joint stiffness endurance. Thirteen males performed the fatigue task (5 sets of 50 hopping). Ankle joint stiffness during drop jump was measured before and after fatigue task. The maximum number of repetitions at 30% of one repetition maximum for plantar flexion was measured as muscular endurance. Maximal elongation of the Achilles tendon was measured during ramp (with a low strain rate of tendon) and ballistic (with a high strain rate of tendon) contractions as tendon extensibility. Joint stiffness significantly decreased by 7.5% after the fatigue task (p = 0.033). The maximum number of repetitions at 30% of 1RM (79.6 ± 48.7 repetitions) was not significantly correlated with the relative change in joint stiffness (r = 0.283, p = 0.348). The maximal elongation of the Achilles tendon measured during ramp and ballistic contractions were not significantly associated with the relative change in joint stiffness (r = 0.326, p = 0.277 for ramp contraction; r = 0.438, p = 0.135 for ballistic contraction). These results suggest that muscular endurance and tendon extensibility were unrelated to joint stiffness endurance.