Digital Flexor Tendon Research Articles

Static, dynamic and non‐weightbearing ultrasound evaluation of the digital flexor tendon sheath improves sensitivity and specificity of manica flexoria tears diagnosis in cobs and ponies

SummaryBackgroundUltrasonography (US) is commonly used as a first‐line imaging modality in horses with lameness localised to the digital flexor tendon sheath (DFTS). The reported sensitivity of US for the detection of manica flexoria (MF) tears is low.ObjectivesTo report sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV) of US for diagnosing MF tears.Study designProspective observational study.MethodsSixty‐seven horses (70 limbs) with lameness localised to the DFTS were enrolled. All the horses underwent a standardised US examination of the DFTS including weightbearing (WB), nonweightbearing (NWB) and dynamic NWB US examination. The presence or absence of a MF tear was recorded. All the horses underwent tenoscopic examination as part of the treatment plan. The US diagnosis was recorded and compared with tenoscopic findings. Sensitivity, Sp, PPV and NPV were calculated.ResultsCobs and ponies were over‐represented (46/67 horses). Ultrasonographic examination correctly predicted the presence of a MF tear in 34/37 (92%) limbs (true positive). In 31/33 (94%) limbs, the MF was considered normal during US examination and this was confirmed during surgery (true negative). In two of 33 (6%) cases, US led to a false‐positive diagnosis. In three of 37 (8%) cases, US failed to identify the presence of a MF tear (false negative (FN)). In all three cases, the MF was only partially torn. The calculated sensitivity of ultrasonography for the detection of MF tears was 92%, specificity 94%, PPV 94% and NPV 91%. There was no significant difference in the ability of operators to identify MF tears.Main limitationsTwo different operators (both DECVS) performed the ultrasonographic examination. The operator performing the US examination was not blinded to the results of the lameness examination. The tenoscopic examination was performed by the same surgeon who had performed the lameness and ultrasonographic examination.ConclusionsUltrasonographic examination of the DFTS is an accurate diagnostic modality to rule in or out the presence of a MF tear. Partial MF tears that do not affect its distal border and/or its attachment onto the SDFT can be challenging to diagnose during US examination.

Comparison of Ultrasound and Magnetic Resonance Imaging for Identifying Soft Tissue Abnormalities in the Palmar Aspect of the Equine Digit.

Damage to the soft tissue structures of the digit is a common source of equine lameness. While magnetic resonance imaging (MRI) allows for the most complete diagnostic imaging of the equine digit, ultrasound is more readily available and less expensive. This prospective diagnostic accuracy study compares ultrasound to MRI for the diagnosis of injuries visible with ultrasound within the digit, including the deep digital flexor tendon (DDFT), collateral sesamoidean ligament (CSL), and navicular bursa. Clinical patients underwent an MRI of the digit and a blinded ultrasound of the digit between the heel bulbs, and results of the two modalities were compared. A total of 70 ultrasound and MRI exams of 45 horses were included. Ultrasound had good sensitivity (85%), moderate specificity (60%), and accuracy of 70% for evaluating the dorsal tearing of the DDFT. Accuracy was lower for navicular bursa effusion (67%), navicular bursa proliferation (61%), and CSL enlargement (61%). Tearing of the DDFT distal to the navicular bone was identified with MRI in 27 limbs, 20 of which also had dorsal damage proximal to the navicular bone identified with ultrasound. Ultrasound evaluation remains a useful screening tool, particularly for the assessment of DDFT tearing proximal to the navicular bone but risks under-diagnosing pathology to the navicular bursa and CSL. Clinically significant concurrent damage to the distal DDFT and other osseous and soft tissues in the hoof capsule is unlikely to be identified without MRI.

Contrast administration via ultrasound-guided injection of the cranial tibial artery results in contrast enhancement of the soft tissues of the metatarsus in horses undergoing CT.

Delivery of mesenchymal stem cells (MSC) via intravascular techniques to treat diffuse and/or inaccessible soft tissue injuries has grown in popularity. The purpose of the current prospective, analytical pilot study was to utilize CT to validate this novel technique and provide additional evidence to support its use for injectate delivery to specific soft tissue structures. Of particular interest was the proximal suspensory ligament, which presents a challenging injection target. Six adult horses without lameness underwent CT of the distal hindlimbs. Scans were obtained prior to ultrasound-guided catheterization of the cranial tibial artery, in addition to early and delayed scans acquired following intra-arterial contrast administration. Region of interest analysis of the superficial and deep digital flexor tendons and suspensory ligament was used to assess contrast enhancement within these structures. Linear mixed models were used to determine statistical significance. Significant (P<0.05) mean contrast enhancement was seen in all postinjection time points in all soft tissue structures of interest. This indicates that ultrasound-guided injection of the cranial tibial artery results in perfusion of injectate throughout the distal hind limb, including the major soft tissue structures of the metatarsus. This provides further support for this technique as a method of MSC delivery to multifocal or inaccessible injury of these structures, including the proximal suspensory ligament.

Ultrasonographic visualization of morphological changes in the tendon tissue of the superficial flexor of the finger in sports horses with tendinopathy

At least one half of population of sport horses during life suffer from superficial digital flexor tendon (SDFT) pathologies, particularly tendinitis and tendinopathies. Etiology of these injuries differs, and their evolution depends on some morphological peculiarities and type of equestrian sport. Success in early detection of preclinical signs of tendinopathy plays a key role in diagnostics and effective treatment in order to preserve athletic potential of a horse. Although in terms of clinical assessment it is not always possible to detect these early pathological changes in tendon tissue without ultrasonography. In this situation elicitation of correlation between morphological and ultrasonic signs seems to be of great importance, because it adds diagnostic and prognostic value of an ultrasound assessment of a patient. Taking into account all mentioned above the aim this study is investigating morphological and ultrasound characteristics of SDFT in middle and distal parts at the cannon and in the area of fetlock joint in normal horses and dressage and show jumping horses with tendinitispathy. In the present study, methods of anatomical preparation and description were used, histological studies were carried out according to the generally accepted methodology, as well as ultrasonographic studies of sports horses using Mindray DС-70 device. Structural features of the SDF tendon were revealed, which explain the chronicity of the pathological process and predispose to incomplete regeneration of the tendon, leading to a deterioration in its functional characteristics and a decrease in the horse's performance. The data obtained deepen the understanding of the etiology and pathogenesis of tendinopathy of the SDFT and allow more detailed interpretation of data obtained by ultrasonographic studies carried out during diagnostic procedures in sport horses, as well as adjusting treatment regimens.

Biomechanical Uniaxial Analysis of Porcine Tendon in the CellScale BioTester® 5000

Abstract Background The study was aimed to evaluate whether a mechanical biaxial tester can be used in a uniaxial mode to evaluate the mechanical properties of tendons. Materials and methods The study was carried out on specimens of porcine superficial digital flexor tendon (n = 9). The mechanical properties (elastic modulus, and stress at 15% strain) were measured two times consecutively in the uniaxial mode with the BioTester® 5000 (CellScale) equipment. Results Values of 0.313 ± 0.096 MPa for the elastic (Young’s) modulus and of 0.702 ± 0.174 MPa for the stress (at 15% strain) were measured, indicating that the porcine superficial digital flexor tendon is not a strong tendon. Conclusions When suitable specimens cannot be obtained for a biaxial evaluation, tendons can be evaluated mechanically in the BioTester® 5000 employing the uniaxial mode.

Guidelines on offloading foot ulcers in persons with diabetes (IWGDF 2023 update).

Offloading mechanical tissue stress is arguably the most important of multiple interventions needed to heal diabetes-related foot ulcers. This is the 2023 International Working Group on the Diabetic Foot (IWGDF) evidence-based guideline on offloading interventions to promote healing of foot ulcersin persons with diabetes. It serves as an update of the 2019 IWGDF guideline. We followed the GRADE approach by devising clinicalquestions and important outcomes in the PICO (Patient-Intervention-Control-Outcome) format, undertaking a systematic review and meta-analyses, developing summary of judgement tables and writing recommendations and rationales for each question. Each recommendation is based on the evidence found in the systematic review, expert opinion where evidence was not available, and a careful weighing of GRADE summary of judgement itemsincluding desirable and undesirable effects, certainty of evidence, patient values, resources required, cost effectiveness, equity, feasibility, and acceptability. For healing a neuropathic plantar forefoot or midfoot ulcer in a person with diabetes, use a non-removable knee-high offloading device as the first-choice offloading intervention. If contraindications or patient intolerance to non-removable offloading exist, consider using a removable knee-high or ankle-high offloading device as the second-choice offloading intervention. If no offloading devices are available, consider using appropriately fitting footwear combined with felted foam as the third-choice offloading intervention. If such a non-surgical offloading treatment fails to heal a plantar forefoot ulcer, consider an Achilles tendon lengthening, metatarsal head resection, joint arthroplasty, or metatarsal osteotomy. For healing a neuropathic plantar or apex lesser digit ulcer secondary to flexibile toe deformity, use digital flexor tendon tenotomy. For healing rearfoot, non-plantar or ulcers complicated with infection or ischaemia, further recommendations have been outlined. All recommendations have been summarised in an offloading clinical pathway to help facilitate the implementation of this guideline into clinical practice. These offloading guideline recommendations should help healthcare professionals provide the best care and outcomes for persons with diabetes-related foot ulcers and reduce the person's risk of infection, hospitalisation and amputation.

Influence of autological growth factors on activation of regenerative processes of the superficial digital flexor tendon of horses

Injury of the superficial digital flexor tendon is known for slow and functionally incomplete recovery, which is a problem in the equestrian horse farming. In the clinical studies, we used platelet-rich plasma, obtained from horse blood, and a specially designed scheme of rehabilitation after physical loads for the treatment of injuries of the superficial digital flexor tendon of horses. We analyzed four clinical cases of injuries of the superficial digital flexor of horses, of which 3 cases were treated using platelet-rich plasma, injected under ultrasound-diagnostic control, and one case that was treated without its administration. Ultrasound studies of the superficial digital flexor tendon revealed the following changes: increase in the volume of the tendon, damage to the fiber structure, and absence of fibrosity on the longitudinal images, and hypo-echogenic or anechogenic structure on transverse and longitudinal images. The results of the platelet-rich-plasma treatment of the horses were compared with the control (without utilization of platelet-rich plasma). As seen on the ultrasound images during the intermediate-control stage (2.5–4.0 months after injury), the horses that had received injection of platelet-rich plasma and had undergone the complex of physical exercises were forming new fibers of the superficial digital flexor tendon, which had distinct structure and alignment. This indicated the process of their physiological development. Four and a half months after being injured, the horse that had only received a symptomatic treatment combined with a complex of rehabilitating physical loads had poorly structured fibers in the damaged area, with their disordered alignment, as revealed by the longitudinal images. This suggested the formation of a scar. Transverse images showed the anechogenic areas of the injury suffered by this horse. The method of preparing and administration of platelet-rich plasma is relatively cheap, given the equipment and a qualification of a veterinary doctor. Taking into account its identified efficacy for recovery of the superficial digital flexor tendon, it would be promising to conduct further clinical trials using platelet-rich plasma for treating other injured tendons of horses, which can notably increase the quality of recovered connective tissues.

Research trends on digital flexor tendon: A bibliometric analysis based on CiteSpace

BackgroundA host of experts have shown interest in the digital flexor tendon. However, few have conducted a bibliometric analysis of this field. PurposeThis study aimed to carry out comprehensive and practical research on the academic status and the development trend in this area. MethodsAll papers regarding digital flexor tendons announced from 1991 to 2022 were retrieved and downloaded from the Web of Science Core Collection. CiteSpace was utilized to analyze the information on publication output, journals, authors, countries, institutions and keywords. ResultsA total of 3100 publications met the inclusion criteria, which were made up of articles and reviews. The publications and cite frequency increased rapidly per year (t = 10.652, P < 0.001; t = 19.716, P < 0.001). Journal of Hand Surgery American Volume had the largest number of studies (307 publications). Amadio PC was identified as the most prolific author, and Dyson SJ (336 citations) was the most cited author. The United States had the highest publications (35.39%), followed by England. Though Australia ranked tenth, which had the greatest impact (centrality = 0.43). This study collected 20 clusters and 25 citation bursts on the basis of keywords. ConclusionThis study recommends that international cooperation and linkages among authors, countries and institutions should be strengthened. Ultrasound, tenosynovitis, platelet-rich plasma, and 3-loop pulley suture have been the focus of current research. The surgical and non-surgical treatment of digital flexor tendon injury would be future frontiers.

Flexor Tendon Repair Techniques: M-Tang Repair.

The authors present the methods and outcomes from six institutes where M-Tang repairs with early active flexion exercise are used for zone 2 digital flexor tendon repair. The authors had close to zero repair ruptures, and few digits needed tenolysis. The excellent to good results are generally between 80% and 90%. In the pandemic period, less stringent therapy supervision might have allowed some patients to move too aggressively, with repair ruptures not seen before the pandemic in one institute. In Nantong, Yixing, and Saint John, the rupture incidence is zero to 1%. In Florence and Heidelberg, the rupture incidence was 3%.

Ultrasound Morphometry and Mean Echogenicity of Digital Flexor Tendons, Suspensory Ligament, and Accessory Ligament of Digital Deep Flexor Tendon in Gaited Horses.

The objective of this study was to evaluate and compare the sonographic characteristics of the digital flexor tendons and ligaments of the palmar/plantar of the metacarpal and metatarsal regions in gaited horses, as well as to establish normal reference ultrasound values for Mangalarga Marchador (MM) and Campeiro breeds. Transverse sonographic images were obtained of 50 adult and healthy horses from the MM (n = 25) and Campeiro (n = 25) breeds. The images were taken in six metacarpal/metatarsal zones, and the following measurements were taken: transverse area, circumference, dorsopalmar/plantar length, lateromedial length, and mean echogenicity. Differences were observed between breeds in the fore- and hindlimbs, and, even when not significant, the Campeiro breed tended to have higher values for most variables and structures. Variations between zones and between structures in the same zone followed a similar trend in both breeds for all variables. In addition, the dimensions and variations between zones and structures were different between the fore- and hindlimbs, highlighting the need for specific values for the digital flexor tendons and ligaments of the metatarsal plantar region. In conclusion, the digital flexor tendons, suspensory ligaments, and accessory ligaments of the digital deep flexor tendon are influenced by the breed factor in gaited horses, and they are different between the fore- and hindlimbs.

Large fibrosarcoma of the equine distal limb treated by surgical excision using a harmonic scalpel

SummaryAn 18‐year‐old Warmblood gelding was presented for investigation of a large, firm mass over the medial and plantar aspect of the left distal metatarsal and fetlock region. The mass was first identified 4 months prior to referral, following a traumatic incident, and had over time gradually increased in size. Clinical examination and diagnostic imaging revealed a large soft tissue mass adjacent to the metatarsophalangeal joint and digital flexor tendon sheath, with no overt involvement of underlying bone. The mass was surgically excised under general anaesthesia using a harmonic scalpel with limited margins to avoid compromise of adjacent anatomical structures. Following histology, the mass was diagnosed as a fibrosarcoma. Twelve months after surgical resection, no signs of recurrence were evident. This report demonstrates that fibrosarcoma of the equine distal limb may be successfully managed with surgical excision. The use of a harmonic scalpel should be considered as an alternative to sharp excision when treating fibrosarcoma or other infiltrative tumours, particularly those located in regions where only limited surgical margins may be achieved.

The cross-sectional area ratio of a specific part of the flexor pollicis longus tendon- a stable sonographic measurement for trigger thumb: a cross-sectional trial

BackgroundTrigger thumb is a pathologic condition of the digital pulleys and flexor tendons. To find a cutoff value of the cross-sectional area ratio of specific parts of the flexor pollicis longus tendon to diagnosis trigger thumb in the high-frequency ultrasound examination.MethodsWe evaluated 271 healthy volunteers and 57 patients with clinical diagnosis of trigger thumb. The cross-sectional area of the metacarpophalangeal joint of flexor pollicis longus tendon (C1) and the cross-sectional area of the midpoint of the first metacarpal of flexor pollicis longus tendon (C2) were analyzed.ResultsThere is no difference between gender, age and left and right hands in the ratio of C1 to C2 (C1/ C2). The mean of C1/ C2 in the healthy thumb was 0.983 ± 0.103, which was significantly smaller in comparison to the diseased thumb (P < 0.05). Based on the receiver operating characteristic curve, we chose the diagnostic cut-off value for the C1/ C2 to be 1.362 and 1.153 in order to differ a trigger thumb from children and adults.ConclusionsThe C1/ C2 of the healthy thumb was relatively stable, with a mean value of 0.983 ± 0.103. The cutoff value of C1/C2 to distinguish healthy thumb from diseased thumb in children and adults were 1.362 and 1.153, respectively.

Interleukin-1β and methylprednisolone acetate demonstrate differential effects on equine deep digital flexor tendon and navicular bone fibrocartilage cells in vitro

To investigate the effects of interleukin-1β (IL-1β) and methylprednisolone acetate (MPA) on equine intrabursal deep digital flexor tendon (DDFT) and navicular bone fibrocartilage (NBF) cells in vitro. Third passage DDFT and NBF cells from 5 healthy donor horses ages 11-17 years euthanized for reasons unrelated to musculoskeletal conditions. Aggregate cultures were incubated with culture medium alone (control), 10 ng/mL IL-1β, 10 ng/mL IL-1β + 0.05 mg/mL MPA, or 10 ng/mL IL-1β + 0.5 mg/mL MPA for 24 hours. Extracellular matrix (ECM) gene expressions were assessed via real-time polymerase chain reaction (rtPCR). Culture media matrix metalloproteinase (MMP) -3 and -13 concentrations were quantified via ELISA. Total glycosaminoglycan (GAG) content in the cell pellets and culture media was also assessed. IL-1β and IL-1β combined with MPA significantly downregulated ECM gene expression to a greater extent in NBF cells compared with DDFT cells. IL-1β and IL-1β combined with MPA significantly upregulated MMP-3 culture media concentrations in DDFT cells only, and MMP-13 culture media concentrations to a greater extent in NBF cells compared with DDFT cells. NBF cells were more susceptible to IL-1β and MPA-mediated ECM gene expression downregulation in vitro. These results serve as a first step for future work to determine intrabursal corticosteroid regimens that limits or resolve the inflammation as well as take into consideration NBF cell biosynthesis in horses with navicular disease, for which currently no information exists.

Osteítis séptica secundaria a una herida accidental en plantar de nudo del miembro posterior en un equino Reporte de caso

The objective of this study was to report a clinical case and its subsequent evolution of a mare with septic osteitis in the proximal sesamoid bones in a hind limb due to a traumatic injury. The patient, an 8-year-old Thoroughbred race mare, from a sporting activity; who was admitted to the Veterinary Hospital Center of the Veterinary School in 2020, presenting a plantar wound of the phalangeal metatarsal joint of the right hind limb, product of a trauma when performing swimming exercises in a stream. In the clinical evaluation, a wound with a section of the superficial and deep digital flexor tendon was determined, evolving to tendosynovitis and septic arthritis with subsequent septic osteitis of the proximal sesamoid bones as a complication. The treatment consisted of a multimodal approach, with the purpose of controlling the infection and contamination of the wound, its repair and analgesia. Due to the aggressive treatment established after diagnosing septic osteitis, the patient evolves favorably, decreasing the degree of pain and lameness observing in subsequent radiographic examens, controlled bone infection and in the process of bone remodeling with ankylosis of the metatarsal phalangeal joint; which was beneficial in this case due to the disruption of the fetlock suspensory apparatus.

Histotripsy Bubble Dynamics in Elastic, Anisotropic Tissue-Mimicking Phantoms.

Elastic, anisotropic tissue such as tendon has proven resistant to mechanical fractionation by histotripsy, a subset of focused ultrasound that uses the creation, oscillation and collapse of cavitation bubbles to fractionate tissue. Our objective was to fabricate an optically transparent hydrogel that mimics tendon for evaluation of histotripsy bubble dynamics. Ex vivo bovine deep digital flexor tendons were obtained (n=4), and varying formulations of polyacrylamide (PA), collagen and fibrin hydrogels (n=3 each) were fabricated. Axial sound speeds were measured at 1 MHz for calculation of anisotropy. All samples were treated with a 1.5-MHz focused ultrasound transducer with 10-ms pulses repeated at 1 Hz (p+=127 MPa, p-=35 MPa); treatments were monitored with passive cavitation imaging and high-speed photography. Dehydrated fibrin gels were found to be the most similar to tendon in cavitation emission energy (fibrin=0.69 ± 0.24, tendon=0.64 ± 0.19 [× 1010 V2]) and anisotropy (fibrin=3.16 ± 1.12, tendon=19.4). Bubble cloud area in dehydrated fibrin (0.79 ± 0.14 mm2) was significantly smaller than most other tested hydrogels. Finally, anisotropy was found to have moderately strong linear relationships with cavitation energy and bubble cloud size (r=-0.65 and -0.80, respectively). Dehydrated fibrin shows potential as a repeatable, transparent, tissue-mimicking hydrogel for evaluation of histotripsy bubble dynamics in elastic, anisotropic tissues.

A Randomized, Self-Controlled Case Series Evaluating Core Osteostixis of Osseous Cyst-Like Lesions of the Navicular Bone to Improve Lameness in Horses with Podotrochlear Syndrome.

Podotrochlear syndrome is a common cause of lameness in Quarter Horses involving both soft tissue and bony structures within the heel region. Current surgical treatment of podotrochlear syndrome addresses pathological changes affecting the soft tissue structures of the navicular region but does not address either edema or cyst-like lesions of the navicular bone. The objective of this randomized, self-controlled case series was to determine whether core osteostixis improved lameness in Quarter Horses with podotrochlear syndrome characterized by bilateral magnetic resonance imaging (MRI) findings of osseous cyst-like lesions of the navicular bone. Seven Quarter Horses that had not responded to standard medical management were included. Each horse had an affected forefoot randomly assigned to surgical treatment with navicular bursoscopy and core osteostixis; the contralateral limb was assigned to navicular bursoscopy only. Video recordings were used to assign lameness scores and make comparisons of each limb at baseline and 24 weeks post-operatively by an observer blinded to the surgical treatment. A second MRI was performed 24 weeks after surgery to reevaluate navicular bone edema, osseous cyst-like lesions of the navicular bone, and tears of the deep digital flexor tendon (DDFT). Reduction of lameness score from baseline was significantly (P = 0.0254) greater for the limbs treated with core osteostixis than limbs treated with bursoscopy. New DDFT tears were noted in 3 of 7 limbs treated with core osteostixis and in 1 of 7 bursoscopy limbs. Results of this study suggest that core osteostixis of the navicular bone combined with navicular bursoscopy can improve lameness in horses with osseous cyst-like lesions. Further evaluation of this technique is warranted.

Silver nanoparticles and platelet-rich fibrin accelerate tendon healing in donkey

This study investigated the effect of the silver nanoparticles (AgNPs) and platelet-rich fibrin (PRF) in the healing of the severed superficial digital flexor tendon in donkeys (SDFT). Twenty-seven adult donkeys were used in the study. The animals were divided into three equal groups. The first group (control group) in which the severed SDFT was sutured without the addition of any adjuvant. In the second group, there was a suture of severed SDFT with the addition of 1 ml of 1 mM silver nanoparticles (AgNPs group). The third group was subjected to the cutting of SDFT and then the addition of PRF after its suture. Each group of animals was divided into three equal subgroups that were examined after 1, 2, and 3 months. Each group of animals was clinically evaluated by assessing lameness. Gross and microscopic examinations of the healed tendons were performed after 1, 2, and 3 months of surgery. In comparison to the control group, the lameness degree decreased in the PRF and AgNPs groups, particularly in the third month after surgery. Furthermore, the lameness decreased significantly after the 3rd month relative to the 1st-month lameness in the AgNPs group. Interestingly, it was found that the PRF and AgNPs enhanced cell alignment and collagen deposition at the site of tendon injury, particularly among third-month subgroups. Therefore, it could be concluded that the PRF and AgNPs are effective materials for enhancing SDFT healing in donkeys.

A novel approach for tendinopathy induction in donkeys using artificial heat stimulation strategy

Animal models for tendonitis are essential for studying the disease’s mechanism and pathogenesis, and evaluating different therapeutic protocols. The temperature seems to play a significant role in tendinitis initiation. The aim of this study was the generation of a novel, safe and cheap tendinitis model, and validation of its reliability. The effect of microwave diathermy (30 watts for 30 min) on the flexor tendons of donkeys as animal models was investigated after 15, 30 and 60 days. The evaluation was based on geometric analysis, ultrasonography, histomorphometric analysis and scanning electron microscopy (SEM). Microwave diathermy was capable of successfully inducing well-defined lesions in the superficial digital flexor tendon (SDFT) as well as the deep digital flexor tendon (DDFT). The results showed that all the animals exhibited signs of lameness, starting on day 15 and reaching on maximum on day 30. A significant increase in limb circumference was also detected on day 30 (P&lt;0.05). Furthermore, the geometrical analysis of the proportion of induced lesion (PIL) in correlation with the tendon diameter, revealed that PIL was at the maximum width on day 30 (20.6 ± 1.2% for SDFT and 15.7 ± 0.7% for DDFT), as detected by ultrasound. Moreover, a high number of rounded tenocytes, bleeding, severe matrix disruption, and an increase in fiber thickness were detected by histomorphometric analysis. Also, the matrix alignment was severely disrupted in both SDFT and DDFT by day 30, as confirmed by SEM. In conclusion, using microwave diathermy for induction of tendonitis in donkey is a reliable, minimally invasive, and cost-effective tendonitis model.

Single collagen fibrils isolated from high stress and low stress tendons show differing susceptibility to enzymatic degradation by the interstitial collagenase matrix metalloproteinase-1 (MMP-1)

Bovine forelimb flexor and extensor tendons serve as a model for examining high stress, energy storing and low stress, positional tendons, respectively. Previous research has shown structural differences between the collagen fibrils of these tissues. The nanoscale collagen fibrils of flexor tendons are smaller in size, more heavily crosslinked, and respond differently to mechanical loading. Meanwhile, energy storing tendons undergo less collagen turnover compared to positional tendons and are more commonly injured. These observations raise the question of whether collagen fibril structure influences the collagen degradation processes necessary for remodelling. Atomic force microscopy was used to image dry collagen fibrils before and after 5-hour exposure to matrix metalloproteinase-1 (MMP-1) to detect changes in fibril size. Collagen fibrils from three tissue types were studied: bovine superficial digital flexor tendons, matched-pair bovine lateral digital extensor tendons, and rat tail tendons. Compared to control fibrils exposed only to buffer, a significant decrease in fibril cross-sectional area (CSA) following MMP-1 exposure was observed for bovine extensor and rat tail fibrils, with larger fibrils experiencing a greater magnitude of CSA decrease in both fibril types. Fibrils from bovine flexor tendons, on the other hand, showed no decrease in CSA when exposed to MMP-1. The result did not appear to be linked to the small size of flexor fibrils, as equivalently sized extensor fibrils were readily degraded by the enzyme. Increased proteolytic resistance of collagen fibrils from high stress tendons may help to explain the longevity of collagen within these tissues in vivo.

Ex vivo pilot study evaluating needle tenoscopy of the digital flexor tendon sheath and its suitability to assist palmar annular ligament transection

SummaryBackgroundThe digital flexor tendon sheath (DFTS) is a common site of pathology in the UK equine population, often necessitating tenoscopic exploration. Common intrathecal pathologies may lead to fetlock canal constriction. The palmar/plantar annular ligament (PAL) is often surgically transected to relieve constriction or to facilitate surgical access and instrumentation.ObjectivesThe objectives of this study were (1) to establish whether diagnostic quality needle tenoscopy can be achieved in the proximal DFTS in cadaver limbs; (2) to determine if needle tenoscopy can be used to safely guide PAL transection; and (3) to evaluate iatrogenic damage when undertaking needle tenoscopy and PAL transection.Study designEx vivo experimental.MethodsSix cadaveric limbs were used and needle tenoscopy of the DFTS was performed via biaxial approach at the base of the sesamoids. Access to and diagnostic assessment of the proximal DFTS, as well as the completeness of needle tenoscopically guided transection of the PAL was recorded. Limbs were dissected and examined for iatrogenic damage and completion of PAL transection.ResultsPositioning of the cannula/obturator unit was achieved on the first attempt 11/12 times. Laterally 16/24 and medially 18/24 proximal DFTS channels were accessed. Images were of diagnostic quality in 12/24 and 11/24 channels following lateral and medial approach, respectively. The PAL was completely transected in 4/6 limbs with partial transection in 1/6 limbs. The superficial digital flexor tendon (SDFT) was longitudinally lacerated instead of the PAL in one limb, with other iatrogenic damage limited to mild fibrillation to the intersesamoidean ligament.Main limitationsEx vivo and sample size.ConclusionsThe findings in this pilot study suggest that needle tenoscopically guided PAL transection in the live horse is not recommended currently. While diagnostic needle tenoscopy offered partial assessment of most of the proximal DFTS, further refinement is necessary before needle tenoscopy could be considered a viable alternative to traditional tenoscopy.