Structure and histopathology of the insertional region of the human Achilles tendon

Animal models of tendon calcification: Past, present, and future

Tendon calcification is a common clinical condition that frequently occurs as a complication after tendon injury and surgery, or as an expression of fibrodysplasia ossificans progressiva. This condition can be referred to by various names in clinical practice and literature, including tendon ossification, tendon mineralization, heterotopic ossification, and calcific tendonitis. The exact pathogenesis of tendon calcification remains uncertain, but current mainstream research suggests that calcification is mostly cell mediated. To further elucidate the pathogenesis of tendon calcification and to better simulate the overall process, selecting appropriate experimental animal models is important. Numerous animal models have been utilized in various clinical studies, each with its own set of advantages and limitations. In this review, we have discussed the advancements made in research on animal models of tendon calcification, with a focus on the selection of experimental animals, the sites of injury in these models, and the methods employed for modeling.

Entheseal surface (Sharpey's fiber insertion) alterations identify past trauma; bone base robusticity, level of routine activity

Sharpey's fiber alterations, referred to as entheseal reaction or enthesopathy, have long been considered an indicator of daily activities. Such semantic transformation seems to conflate processes which alter the characteristics of tendonous and ligamentous attachments to bone with the rugosity and extent of their base/footprint. Rather than reflecting normal activities, it is suggested that surface reactions are actually the response to the application of sudden or unconditioned repetitive stresses-analogous to stress fractures. Thus, they are distinct from enlargement of the base/footprint, the bone remodeling process responsible for the robusticity of the area to which the enthesis attaches, which is actually a measure of actual muscle activity. Surface reactions in attachment areas represent injury, be it mechanical stress fracture-equivalents or inflammation-derived. Bone base/footprint is the reaction of the enthesis to stresses of routine physical activities. The character of underlying bone supporting Sharpey's fibers may be augmented by applied stress, but there is neither a physiologic mechanism nor is there evidence for significant addition of Sharpey's fibers beyond ontogeny. Behavior is responsible for the physiologic response of robusticity; spiculation, pathology.

Insertional Achilles tendinopathy: A radiographic cross-sectional comparison between symptomatic and asymptomatic heel of 71 patients

Purpose

This retrospective study aimed to investigate whether the standard radiographic indicators for Haglund's syndrome are applicable to insertional Achilles tendinopathy.

Methods

Patients who underwent surgery for insertional Achilles tendinopathy in one heel and experienced no pain in the other heel were enrolled in this study. Preoperative calibrated radiographs of the lateral view of the calcaneus were assessed using (1) calcaneal pitch angle, (2) Fowler-Phillip angle, (3) posterior calcaneal angle, (4) Chauveau-Liet angle, (5) X/Y ratio, (6) Haglund's deformity height, (7) Haglund's deformity peak angle, (8) calcification length, (9) calcification width, (10) parallel pitch test, and (11) presence of free body. The Wilcoxon signed rank test and McNemar's test were used for statistical analyses.

Results

Seventy-one patients (52 males; mean age, 57.2; mean body mass index, 27.1) were included. Mean values for each index in the symptomatic and asymptomatic heels were as follows, respectively: (1) 23.5, 23.0 (p = 0.30); (2) 58.9, 57.8 (p < 0.05); (3) 7.6, 9.2 (p < 0.05); (4) 15.8, 13.9 (p < 0.05); (5) 2.8, 2.8 (p = 0.87); (6) 5.4, 5.0 (p < 0.05); (7) 99.6, 99.0 (p = 0.44); (8) 10.5, 7.6 (p < 0.001); and (9) 5.1, 4.4 (p < 0.05). The sensitivity, specificity, and area under curve of significant indicators were as follows, respectively: (2) 0.78, 0.37, 0.55; (3) 0.45, 0.72, 0.58; (4) 0.63, 0.54, 0.57; (6) 0.45, 0.69, 0.59; (8) 0.48, 0.80, 0.66; and (9) 0.63, 0.54, 0.59. The presence of free body also showed a significant difference between both heels (p < 0.05).

Conclusion

Some radiographic indicators for Haglund's syndrome are applicable to the diagnosis of insertional Achilles tendinopathy. A comparison of the parameters of Haglund's syndrome with those of insertional Achilles tendinopathy may illuminate the etiology and pathology of insertional Achilles tendinopathy and lead to novel treatments.

The Structure, Biology, and Mechanical Function of Tendon/Ligament-Bone Interfaces

After tendon or ligament reconstruction, the interface between the hard bone and soft connective tissue is considerably weakened and is difficult to restore through healing. The tendon/ligament-bone interface is mechanically the weakest point under tensile loading and is often the source of various postoperative complications, such as bone resorption and graft laxity. A comprehensive understanding of the macro- and microfeatures of the native tendon/ligament-bone interface would be beneficial for developing strategies for regenerating the tissue. This article discusses the structural, biological, and mechanical features of the tendon/ligament-bone interfaces and how these can be affected by aging and loading conditions.

Epidemiology of insertional and midportion Achilles tendinopathy in runners: A prospective cohort study

BACKGROUND

Achilles tendinopathy (AT) is a common problem among runners. There is only limited evidence for risk factors for AT, and most studies have not defined the AT subcategories. No study has compared the incidence and risk factors between insertional AT and midportion AT, though they are considered distinct. This study aimed to assess incidence and risk factors of AT based on data from a large prospective cohort. The secondary aim was to explore differences in risk factors between insertional and midportion AT.

METHODS

Participants were recruited from among registered runners at registration for running events. Questionnaires were completed at baseline, 1 month before the event, 1 week before the event, and 1 month after the event. Information concerning demographics, training load, registered events, and running-related injuries were collected at baseline. The follow-up questionnaires collected information about new injuries. A pain map was used to diagnose midportion and insertional AT. The primary outcome was the incidence of AT. Multivariable logistic regression analysis was applied to identify risk factors for the onset.

RESULTS

We included 3379 participants with a mean follow-up of 20.4 weeks. The incidence of AT was 4.2%. The proportion of insertional AT was 27.7% and of midportion AT was 63.8%; the remaining proportion was a combined type of insertional and midportion AT. Men had a significantly higher incidence (5%, 95% confidence interval (95%CI): 4.1%-6.0%) than women (2.8%, 95%CI: 2.0%-3.8%). AT in the past 12 months was the most predominant risk factor for new-onset AT (odds ratio (OR) = 6.47, 95%CI: 4.27 -9.81). This was similar for both subcategories of AT (insertional: OR = 5.45, 95%CI: 2.51-11.81; midportion: OR = 6.96, 95%CI: 4.24-11.40). Participants registering for an event with a distance of 10/10.55 km were less likely to develop a new-onset AT (OR = 0.59, 95%CI: 0.36-0.97) or midportion AT (OR = 0.47, 95%CI: 0.23 -0.93). Higher age had a significant negative association with insertional AT (OR = 0.97, 95%CI: 0.94-1.00).

CONCLUSION

The incidence of new-onset AT among recreational runners was 4.2%. The proportion of insertional and midportion AT was 27.7% and 63.8%, respectively. AT in the past 12 months was the predominant risk factor for the onset of AT. Risk factors varied between insertional and midportion AT, but we could not identify clinically relevant differences between the 2 subtypes.

Calcaneal tuberosity avulsion fractures - A review

Calcaneal tuberosity avulsion fracture, an extra-articular injury, is a rare fracture caused internally by Achilles tendon driven following intense contraction of gastrocnemius-soleus complex, and externally by low-energy (possibly high-energy). Moreover, the risk of injuries of the skin and Achilles tendon around calcaneal tuberosity is closely related to Lee classification and Carnero-Martín de Soto Classification of calcaneal tuberosity avulsion fracture. Although the diagnosis confirmed by X-ray, digital imaging and computed tomography (CT), magnetic resonance imaging (MRI) should also be used to evaluate soft tissue. In recent years, the understanding of this fracture has witnessed the development of different internal fixation devices and surgical procedures. These advances have been further elaborated scientifically in terms of their ability to provide stable fracture reduction ad resistance to Achilles tendon forces. In order to obtain a comprehensive knowledge of the disease, this article reviewed the new understanding of the anatomy, typing, risk factors, and treatment modalities of calcaneal tuberosity avulsion fracture in recent years.

Take a load off: skeletal implications of sedentism in the feet of modern body donors

Background and Objectives

Modern biocultural environments continue to place selective pressures on our skeletons. In the past century, a major cultural pressure has been the rise in sedentism. However, studies considering the effects of sedentism on the foot have largely considered pathological changes to the gross foot without particular regard for the pedal skeleton. To address this gap in the literature, temporal trends in the development of osteoarthritis and entheseal changes on the tarsals and metatarsals were analyzed in the context of biodemographic data for recent modern humans.

Methodology

The sample utilized for this project is comprised of 71 individuals from the William M. Bass Donated Skeletal Collection, with birth years ranging from 1909 to 1993. Temporal trends in osteoarthritis and entheseal changes were determined via ANCOVA, using year of birth as the explanatory variable and biodemographic variables (age, sex, stature, body mass index and tibial robusticity) as covariates.

Results

Results indicate that entheseal changes and osteoarthritis have decreased over time, and these trends are statistically significant. Temporal trends in pedal entheseal changes and osteoarthritis vary by sex.

Conclusions and Implications

The increase in sedentary behavior over time has usually been framed as a net negative for human health and well-being. However, considered in isolation, the decrease in entheseal changes and osteoarthritis presented here might be considered a positive development as they suggest overall less stress on the modern human foot. This study also has the potential to inform the health sciences and general public about biocultural contributors to modern foot health.

Mechanical force regulates Sox9 expression at the developing enthesis

Entheses transmit force from tendons and ligaments to the skeleton. Regional organization of enthesis extracellular matrix (ECM) generates differences in stiffness required for force transmission. Two key transcription factors co-expressed in entheseal tenocytes, scleraxis (Scx) and Sox9, directly control production of enthesis ECM components. Formation of embryonic craniofacial entheses in zebrafish coincides with onset of jaw movements, possibly in response to the force of muscle contraction. We show dynamic changes in scxa and sox9a mRNA levels in subsets of entheseal tenocytes that correlate with their roles in force transmission. We also show that transcription of a direct target of Scxa, Col1a, in enthesis ECM is regulated by the ratio of scxa to sox9a expression. Eliminating muscle contraction by paralyzing embryos during early stages of musculoskeletal differentiation alters relative levels of scxa and sox9a in entheses, primarily owing to increased sox9a expression. Force-dependent TGF-β (TGFβ) signaling is required to maintain this balance of scxa and sox9a expression. Thus, force from muscle contraction helps establish a balance of transcription factor expression that controls specialized ECM organization at the tendon enthesis and its ability to transmit force.

Minimally invasive surgeries for insertional Achilles tendinopathy: A commentary review

Studies of minimally invasive surgery for insertional Achilles tendinopathy are limited. To establish this surgery, the following techniques must be minimally invasive: Exostosis resection at the Achilles tendon insertion, debridement of degenerated Achilles tendon, reattachment using anchors or augmentation using flexor hallucis longus (FHL) tendon transfer, and excision of the posterosuperior calcaneal prominence. Studies on these four perspectives were reviewed to establish minimally invasive surgery for insertional Achilles tendinopathy. Techniques for exostosis resection were demonstrated in one case study, where blunt dissection around the exostosis was performed, and the exostosis was resected using an abrasion burr under fluoroscopic guidance. Techniques for debridement of degenerated Achilles tendon were demonstrated in the same case study, where the space left after resection of the exostosis was used as an endoscopic working space, and the degenerated Achilles tendon and intra-tendinous calcification were debrided endoscopically. Achilles tendon reattachment techniques using suture anchors have been demonstrated in several studies. However, there are no studies on FHL tendon transfer techniques for Achilles tendon reattachment. In contrast, endoscopic posterosuperior calcaneal prominence resection is already established. Additionally, studies on ultrasound-guided surgeries and percutaneous dorsal wedge calcaneal osteotomy as minimally invasive surgery were reviewed.

Mesenchymal stem cells and macrophages and their interactions in tendon-bone healing

Tendon-bone insertion injuries (TBI), such as anterior cruciate ligament (ACL) and rotator cuff injuries, are common degenerative or traumatic pathologies with a negative impact on the patient's daily life, and they cause huge economic losses every year. The healing process after an injury is complex and is dependent on the surrounding environment. Macrophages accumulate during the entire process of tendon and bone healing and their phenotypes progressively transform as they regenerate. As the "sensor and switch of the immune system", mesenchymal stem cells (MSCs) respond to the inflammatory environment and exert immunomodulatory effects during the tendon-bone healing process. When exposed to appropriate stimuli, they can differentiate into different tissues, including chondrocytes, osteocytes, and epithelial cells, promoting reconstruction of the complex transitional structure of the enthesis. It is well known that MSCs and macrophages communicate with each other during tissue repair. In this review, we discuss the roles of macrophages and MSCs in TBI injury and healing. Reciprocal interactions between MSCs and macrophages and some biological processes utilizing their mutual relations in tendon-bone healing are also described. Additionally, we discuss the limitations in our understanding of tendon-bone healing and propose feasible ways to exploit MSC-macrophage interplay to develop an effective therapeutic strategy for TBI injuries.

The Translational potential of this article

This paper reviewed the important functions of macrophages and mesenchymal stem cells in tendon-bone healing and described the reciprocal interactions between them during the healing process. By managing macrophage phenotypes, mesenchymal stem cells and the interactions between them, some possible novel therapies for tendon-bone injury may be proposed to promote tendon-bone healing after restoration surgery.

Treatment of Calcific Insertional Achilles Tendinopathy: Knotless Internal Brace versus Knot-Tying Suture Bridge

Background: This study aimed to compare the knotless internal brace technique and the knot-tying suture bridge technique via the medial approach in the treatment of calcific Achilles tendinopathy. Methods: The clinical data of 25 cases of calcific Achilles tendinopathy in which nonoperative treatments had failed were retrospectively collected. All the patients received Achilles tendon debridement and Haglund deformity excision through a medial approach, followed by repair using the knotless internal brace technique or the knot-tying suture bridge technique. Pain was evaluated by using the visual analog scale (VAS). The American Orthopedic Foot and Ankle Score (AOFAS) questionnaire was administered preoperatively and postoperatively. Results: The mean follow-up time was 2.6 (range 2–3.5) years. There were no wound complications and no Achilles tendon ruptures. At 1 year postoperatively, the internal brace group was superior to the suture bridge group in terms of the VAS scores (p = 0.003). However, no differences were noticed between the two groups in either the VAS or the AOFAS scores at 2 years postoperatively. Conclusions: The medial approach in combination with the suture bridge technique was effective in treating calcific Achilles tendinopathy. The knotless internal brace technique involved less pain compared to the knot-tying suture bridge technique only at the early postoperative stage.

Effects of hindlimb unloading and subsequent reloading on the structure and mechanical properties of Achilles tendon-to-bone attachment

While muscle and bone adaptations to deconditioning have been widely described, few studies have focused on the tendon enthesis. Our study examined the effects of mechanical loading on the structure and mechanical properties of the Achilles tendon enthesis. We assessed the fibrocartilage surface area, the organization of collagen, the expression of collagen II, the presence of osteoclasts, and the tensile properties of the mouse enthesis both after 14 days of hindlimb suspension (HU) and after a subsequent 6 days of reloading. Although soleus atrophy was severe after HU, calcified fibrocartilage (CFc) was a little affected. In contrast, we observed a decrease in non-calcified fibrocartilage (UFc) surface area, collagen fiber disorganization, modification of morphological characteristics of the fibrocartilage cells, and altered collagen II distribution. Compared to the control group, restoring normal loads increased both UFc surface area and expression of collagen II, and led to a crimp pattern in collagen. Reloading induced an increase in CFc surface area, probably due to the mineralization front advancing toward the tendon. Functionally, unloading resulted in decreased enthesis stiffness and a shift in site of failure from the osteochondral interface to the bone, whereas 6 days of reloading restored the original elastic properties and site of failure. In the context of spaceflight, our results suggest that care must be taken when performing countermeasure exercises both during missions and during the return to Earth.

Tendon healing: a concise review on cellular and molecular mechanisms with a particular focus on the Achilles tendon

Tendon is a bradytrophic and hypovascular tissue, hence, healing remains a major challenge. The molecular key events involved in successful repair have to be unravelled to develop novel strategies that reduce the risk of unfavourable outcomes such as non-healing, adhesion formation, and scarring. This review will consider the diverse pathophysiological features of tendon-derived cells that lead to failed healing, including misrouted differentiation (e.g. de- or transdifferentiation) and premature cell senescence, as well as the loss of functional progenitors. Many of these features can be attributed to disturbed cell-extracellular matrix (ECM) or unbalanced soluble mediators involving not only resident tendon cells, but also the cross-talk with immigrating immune cell populations. Unrestrained post-traumatic inflammation could hinder successful healing. Pro-angiogenic mediators trigger hypervascularization and lead to persistence of an immature repair tissue, which does not provide sufficient mechano-competence. Tendon repair tissue needs to achieve an ECM composition, structure, strength, and stiffness that resembles the undamaged highly hierarchically ordered tendon ECM. Adequate mechano-sensation and -transduction by tendon cells orchestrate ECM synthesis, stabilization by cross-linking, and remodelling as a prerequisite for the adaptation to the increased mechanical challenges during healing. Lastly, this review will discuss, from the cell biological point of view, possible optimization strategies for augmenting Achilles tendon (AT) healing outcomes, including adapted mechanostimulation and novel approaches by restraining neoangiogenesis, modifying stem cell niche parameters, tissue engineering, the modulation of the inflammatory cells, and the application of stimulatory factors.Cite this article: Bone Joint Res 2022;11(8):561-574.

Concepts of Entheseal Pain

Pain is the main symptom in entheseal diseases (enthesopathies) despite a paucity of nerve endings in the enthesis itself. Eicosanoids, cytokines, and neuropeptides released during inflammation and repeated nonphysiologic mechanical challenge not only stimulate or sensitize primary afferent neurons present in structures adjacent to the enthesis, but also trigger a "neurovascular invasion" that allows the spreading of nerves and blood vessels into the enthesis. Nociceptive pseudounipolar neurons support this process by releasing neurotransmitters from peripheral endings that induce neovascularization and peripheral pain sensitization. This process may explain the frequently observed dissociation between subjective symptoms such as pain and the structural findings on imaging in entheseal disease.

Update on Fibrocartilaginous Disease Clinical Examination

This article provides an update on fibrocartilaginous disease clinical examination. Lesser metatarsophalangeal joint instability is a challenging entity for the foot and ankle surgeon. A correct diagnosis is crucial to instill an appropriate treatment plan that will result in a successful outcome and a satisfied patient. Insertional Achilles tendon disorders are common among active and inactive patients. There is also a high predilection for Achilles tendon pathology among athletes. In this article demographics and patient history, causative factors, differential diagnosis, physical examination, clinical tests, and radiographic evaluation are discussed for plantar plate disorders and insertional Achilles disorders.

Triple Hemisection Percutaneous Achilles Tendon Lengthening for Severe Ankle Joint Deformity

Objective

To investigate the efficacy of modified percutaneous Achilles tendon lengthening for severe ankle joint deformity.

Methods

This retrospective case series study included 33 patients with an average age of 25.2 years who underwent surgery in our hospital from April 1, 2010 to March 1, 2018. Triple hemisection percutaneous Achilles tendon lengthening was performed. One stage surgery, other soft tissue surgery or bone correction surgery could be performed. After surgery, a plaster cast was used to fix the functional position, and rehabilitation training was carried out as planned. Complications during the perioperative period were recorded. Statistical analysis of the patients' visual analogue scale (VAS) and American Orthopedic Foot and Ankle Society (AOFAS) score before and at the last follow‐up was performed. The recurrence rate of Achilles tendon contracture at the last follow‐up and the patients' satisfaction rate were investigated.

Results

All patients were followed up, with an average follow‐up period of 56.31 months (8–104 months). All achieved good ankle joint function and appearance improvement And there were no infection or skin necrosis complications. In two cases, the incision was poorly healed at non‐Achilles tendon site and was cured by change of dressing. The average VAS score at the last follow‐up was reduced from (2 ± 1.48) points before surgery to (0.26 ± 0.51) points (P = 0.001), and the average AOFAS score was increased from (64.97 ± 13.56) points before surgery to (90.06 ± 10.06) points (P = 0.001). During the follow‐up period, there was no chronic rupture of Achilles tendon. There were two cases of recurrence of foot drop (5.7%), and the patients' satisfaction rate was 93.9%.

Conclusion

In the surgical treatment of severe ankle joint deformity, the application of triple hemisection percutaneous Achilles tendon lengthening for Achilles tendon contracture has the advantages of less trauma, beautiful incision, and reliable efficacy. The satisfaction rate of patients with this treatment is high, and it is worth promoting in the clinic.

Local anisotropy in mineralized fibrocartilage and subchondral bone beneath the tendon-bone interface

The enthesis allows the insertion of tendon into bone thanks to several remarkable strategies. This complex and clinically relevant location often features a thin layer of fibrocartilage sandwiched between tendon and bone to cope with a highly heterogeneous mechanical environment. The main purpose of this study was to investigate whether mineralized fibrocartilage and bone close to the enthesis show distinctive three-dimensional microstructural features, possibly to enable load transfer from tendon to bone. As a model, the Achilles tendon-calcaneus bone system of adult rats was investigated with histology, backscattered electron imaging and micro-computed tomography. The microstructural porosity of bone and mineralized fibrocartilage in different locations including enthesis fibrocartilage, periosteal fibrocartilage and bone away from the enthesis was characterized. We showed that calcaneus bone presents a dedicated protrusion of low porosity where the tendon inserts. A spatially resolved analysis of the trabecular network suggests that such protrusion may promote force flow from the tendon to the plantar ligament, while partially relieving the trabecular bone from such a task. Focusing on the tuberosity, highly specific microstructural aspects were highlighted. Firstly, the interface between mineralized and unmineralized fibrocartilage showed the highest roughness at the tuberosity, possibly to increase failure resistance of a region carrying large stresses. Secondly, fibrochondrocyte lacunae inside mineralized fibrocartilage, in analogy with osteocyte lacunae in bone, had a predominant alignment at the enthesis and a rather random organization away from it. Finally, the network of subchondral channels inside the tuberosity was highly anisotropic when compared to contiguous regions. This dual anisotropy of subchondral channels and cell lacunae at the insertion may reflect the alignment of the underlying collagen network. Our findings suggest that the microstructure of fibrocartilage may be linked with the loading environment. Future studies should characterize those microstructural aspects in aged and or diseased conditions to elucidate the poorly understood role of bone and fibrocartilage in enthesis-related pathologies.

The transition from enthesis physiological responses in health to aberrant responses that underpin spondyloarthritis mechanisms

PURPOSE OF REVIEW

Despite immunology and translational therapeutics advances in inflammatory arthritis over the past two decades, the enthesis, which is the epicentric of the spondyloarthritis family pathological process, retains many mysteries because of tissue inaccessibility that hampers direct immune study. As entheses are subject to almost continuous mechanical stress and spondyloarthritis is linked to microdamage or injury and joint stress, it is cardinal to understand the physiological changes occurring within the entheses not only to be able to differentiate disease from health but also to understand the transition normal physiology break down and its merges into spondyloarthritis-related disease.

RECENT FINDINGS

Imaging has played a major role in understanding the enthesis in human. Remarkable insights from enthesis functioning and microdamage in normal and with ageing including those linked to body mass index is emerging. The impact of mechanical stress and degenerative conditions on the development of the secondary entheseal vascular changes is not understood. Of note, ultrasound studies in psoriasis have shown higher power Doppler changes compared to controls pointing towards a role for vascular changes in the development of enthesitis in psoriatic arthritis.

SUMMARY

The literature pertaining to normal entheses changes with age, microdamage and vascular changes in health is providing a roadmap for understanding of the enthesis and its potential role in evolution of spondyloarthritis including psoriatic arthritis.

Effect of Ankle Motion and Tensile Stress at the Achilles Tendon on the Contact Pressure Between the Achilles Tendon and the Calcaneus

Impingement between the Achilles tendon and the posterosuperior prominence of the calcaneus is considered to be a cause of insertional Achilles tendinopathy. The corresponding treatment intends to reduce tensile stress from calf muscles and avoid hyper-dorsiflexion of the ankle joint for decreasing the contact pressure; however, no study has reported on whether these treatments can decrease impingement. Thus, this study investigated the hypothesis that the tensile stress of the Achilles tendon and ankle motion affect the contact pressure between the Achilles tendon and the posterosuperior prominence of the calcaneus. Six fresh-frozen cadaveric lower leg specimens were procured. Each specimen was set to a custom foot-loading frame and loaded with a ground reaction force of 40 N and a tensile load of 70 N along the Achilles tendon. The contact pressure between the Achilles tendon and the posterosuperior prominence of the calcaneus was measured using a miniature pressure sensor under different tensile loadings of the Achilles tendon at the neutral ankle position. Similarly, the contact pressures during the ankle motion from a neutral position to maximum dorsiflexion were measured. The tensile load of the Achilles tendon and ankle motion affected the contact pressure between the Achilles tendon and the posterosuperior prominence of the calcaneus. The contact pressure increased with tensile load or ankle dorsiflexion. Conditions with increasing the tensile load of the Achilles tendon or under ankle dorsiflexion increase the contact pressure between the Achilles tendon and the posterosuperior prominence of the calcaneus.

Why heel spurs are traction spurs after all

It is unclear whether plantar and posterior heel spurs are truly pathological findings and whether they are stimulated by traction or compression forces. Previous histological investigations focused on either one of the two spur locations, thereby potentially overlooking common features that refer to a uniform developmental mechanism. In this study, 19 feet from 16 cadavers were X-ray scanned to preselect calcanei with either plantar or posterior spurs. Subsequently, seven plantar and posterior spurs were histologically assessed. Five spur-free Achilles tendon and three plantar fascia entheses served as controls. Plantar spurs were located either intra- or supra-fascial whereas all Achilles spurs were intra-fascial. Both spur types consistently presented a trabecular architecture without a particular pattern, fibrocartilage at the tendinous entheses and the orientation of the spur tips was in line with the course of the attached soft tissues. Spurs of both entities revealed tapered areas close to their bases with bulky tips. Achilles and plantar heel spurs seem to be non-pathological calcaneal exostoses, which are likely results of traction forces. Both spur types revealed commonalities such as their trabecular architecture or the tip direction in relation to the attached soft tissues. Morphologically, heel spurs seem poorly adapted to compressive loads.

Enthesopathy-An Underappreciated Role in Osteoarthritis?

Osteoarthritis (OA) continues to be a debilitating disease worldwide, to date, no therapies have been definitely proven to modify disease progression or moderate symptom relief long term other than joint replacement. A contributing factor may be the lack of attention to the potential role of the periarticular enthesis and development and progression of OA. The enthesis is the site of attachment for a tendon, ligament, or joint capsule to the bony skeleton, thereby allowing centralized transmission and dissipation of mechanical loads. Because of this design, the enthesis is a site of stress concentration subject to inflammation during sports-related activities or spondyloarthropathies, which may lead to long-term degeneration. Our hypothesis is that functional incompetence of the enthesis resulting from either degenerative or inflammatory changes could be an initiating factor for OA and may thus provide a novel basis for the development of future disease management in this phenotype of patients.

Effect of storage and preconditioning of healing rat Achilles tendon on structural and mechanical properties

Tendon tissue storage and preconditioning are often used in biomechanical experiments and whether this generates alterations in tissue properties is essential to know. The effect of storage and preconditioning on dense connective tissues, like tendons, is fairly understood. However, healing tendons are unlike and contain a loose connective tissue. Therefore, we investigated if storage of healing tendons in the fridge or freezer changed the mechanical properties compared to fresh tendons, using a pull-to-failure or a creep test. Tissue morphology and cell viability were also evaluated. Additionally, two preconditioning levels were tested. Rats underwent Achilles tendon transection and were euthanized 12 days postoperatively. Statistical analyzes were done with one-way ANOVA or Student's t-test. Tissue force and stress were unaltered by storage and preconditioning compared to fresh samples, while high preconditioning increased the stiffness and modulus (p ≤ 0.007). Furthermore, both storage conditions did not modify the viscoelastic properties of the healing tendon, but altered transverse area, gap length, and water content. Cell viability was reduced after freezing. In conclusion, preconditioning on healing tissues can introduce mechanical data bias when having extensive tissue strength diversity. Storage can be used before biomechanical testing if structural properties are measured on the day of testing.

The pathological features of hip abductor tendon tears - a cadaveric study

Background

The hip abductors are crucial in maintaining pelvic stability. Tears in these tendons are common and often debilitating. There is uncertainty regarding both the histological and macroscopic features of hip abductor tears. This study aims to clarify both the macroscopic and microscopic features of the tendon and enthesis in hip abductor tendon tears.

Methods

Thirty-six cadavers with an average age of 81 were dissected, and the hip abductor mechanisms removed en-bloc. The presence, location and size of the tears were recorded and analysed. The samples were processed into histological blocks and viewed using both transmitted and polarised light. Tendon histology was graded using the modified Movin’s score in three sections (deep, middle and superficial layers) and the enthesis graded separately using 5-point criteria. Analysis of variance was used to confirm histological features associated with tears.

Results

Tears were found in 24 of 36 samples (67%). The most common finding was an isolated tear in the gluteus minimus (46%), followed by concurrent gluteus medius and gluteus minimus tears (33%). Histology revealed significantly more degeneration in both the tendon (p = 0.0005) and enthesis (p = 0.0011) when tears were present. Furthermore, these changes were concentrated in the deeper layers of the tendon (p = 0.0002) and enthesis (p = 0.003).

Conclusion

This study demonstrated degeneration as the primary pathology underlying hip abductor tendon tears. Degenerative changes occur in both the tendon and enthesis, with the deeper layers predominantly affected. These findings are important for guiding surgical repair techniques and to aid the development of novel materials and biologics.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-020-03784-3.

Study of the clinical and functional results of open calcaneoplasty and tendinous repair for the treatment of the insertional tendinopathy of the Achilles' tendon

BACKGROUND AND OBJECTIVES

Insertional tendinopathy accounts for 23% of the pathology of the Achilles tendon. Surgery is indicated when conservative treatment of pain and functional limitation fails. Our objective is to analyse the clinical-functional results of surgical treatment with disinsertion, debridement and double row reattachment with high strength suture tape.

MATERIAL AND METHODS

We present 13 patients with insertional Achilles tendinopathy, treated between February 2015 and October 2016. In all of them we performed inverted T-tendon disinsertion, debridement and calcareoplasty followed by double row tendon re-anchorage, without knots, with high resistance suture tape. Functional results were assessed with the AOFAS scale before and after surgery, with an average follow-up of 22 months.

RESULTS

The patients, 11 males and 2 females, with an average age of 43 years, presented a preoperative AOFAS score of 34.77±10.1 that reached 90.85±7 points after the operation, with an average increase of 56.08 points (IC 95% 48.13-64.02; P<0.01). The time to return to sports activities was 19 weeks (16-22). There were no complications.

CONCLUSION

The technique we present reports excellent results as a surgical treatment of insertional Achilles tendinopathy with intralesional calcification; it allows a wide contact surface between bone and tendon and an earlier return to previous sports activity.

Effects of Achilles Tendon Moment Arm Length on Insertional Achilles Tendinopathy

Insertional Achilles tendinopathy (IAT) is caused by traction force of the tendon. The effectiveness of the suture bridge technique in correcting it is unknown. We examined the moment arm in patients with IAT before and after surgery using the suture bridge technique, in comparison to that of healthy individuals. We hypothesized that the suture bridge method influences the moment arm length. An IAT group comprising 10 feet belonging to 8 patients requiring surgical treatment for IAT were followed up postoperatively and compared with a control group comprising 15 feet of 15 healthy individuals with no ankle complaints or history of trauma or surgery. The ratio of the moment arm (MA) length/foot length was found to be statistically significant between the control group, the IAT group preoperatively and the IAT group postoperatively (p < 0.01). Despite no significant difference in the force between the control and preoperative IAT groups, a significantly higher force to the Achilles tendon was observed in the IAT group postoperatively compared to the other groups (p < 0.05). This study demonstrates that a long moment arm may be one of the causes of IAT, and the suture bridge technique may reduce the Achilles tendon moment arm.

Magnetic Resonance Imaging of Enthesitis in Spondyloarthritis, Including Psoriatic Arthritis-Status and Recent Advances

Enthesitis, inflammation at the attachment sites of tendons, ligaments, fascia, and joint capsules to bones plays a critical role in the pathogenesis of spondyloarthritis (SpA), including psoriatic arthritis (PsA). Magnetic resonance imaging (MRI) has aided in a better understanding of pathophysiology, early diagnosis, prognostication, therapeutic outcomes, and follow up of enthesitis. The concept of enthesitis as a focal insertional pathology has transformed over the past decade, with the help of MRI, to a more widespread entity involving both bone and surrounding soft tissues. The utility of MRI in the differential diagnosis of suspected enthesitis has recently been explored. With the emergence of the treat-to-target concept, and a domain-based approach in the management of SpA, objective and sensitive monitoring of response to targeted therapy becomes prudent. Properties like high sensitivity, ability to image intra-osseous pathology along with surrounding structures exemplify the utility of MRI technology. Considering the lack of a comprehensive, validated MRI score the Outcome Measures in Rheumatology (OMERACT) MRI in Arthritis Working Group, informed by a systematic literature review, developed the first international, consensus-based MRI-scoring system, combined with MRI definitions of pathologies for enthesitis in patients with spondyloarthritis (SpA) and PsA. An atlas with representative images of each grade of the scoring system was subsequently developed by the group to aid readers interested in using the heel enthesitis MRI scoring system (HEMRIS). The HEMRIS can find utility in clinical trials targeting enthesitis as the primary outcome. MRI also finds value for global assessment of the total burden of enthesitis. The concept of whole-body MRI (WBMRI), enabling visualization of entheses throughout the body using a single image is relatively new. The MRI whole-body score for inflammation in peripheral joints and entheses (MRI-WIPE) is a promising scoring system, which is undergoing further testing in clinical trials and longitudinal cohorts evaluating global measures of inflammation at entheses. This review discusses the role of MRI in diagnosis and monitoring of enthesitis in SpA and PsA, along with recent advances in the field, based on published literature.

Repair of Achilles sleeve avulsion: a new transosseous suture technique

BACKGROUND

Achilles sleeve avulsion usually occurs from pre-existing insertional Achilles tendinopathy, leaving a calcific spur at the insertional site. The purpose of this study was to introduce a new technique using the spur base on the insertional site to drill the suture tunnel to repair Achilles sleeve avulsion.

METHODS

In total, 11 patients diagnosed with Achilles sleeve avulsion underwent this new surgical technique and were followed for a mean time of 40 months. Clinical outcomes were measured using the visual analog scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) score, Victorian Institute of Sports Assessment-Achilles (VISA-A) score, Tegner score, and time taken to return to activities. Preoperative and postoperative MRI, the ability to perform heel rise, and complications were also evaluated.

RESULTS

All cases (11/11) had insertional Achilles tendinopathy with calcific spur formation on the tendon's insertion. At final follow-up, the average VAS score improved from 5.3 to 0.1, AOFAS score improved from 44.8 to 97.9, VISA-A score improved from 23.6 to 96.6, and Tegner score improved from 0.9 to 4.9. Tendinopathy symptoms were eliminated. Patients returned to daily activities, work, and sports 3.5 months, 2.8 months, and 12.3months after operation, respectively. Patients took an average of 18.1 weeks after operation to perform the single heel rise test. No severe complications such as infection and rerupture were observed.

CONCLUSION

Our new transosseous suture technique is a promising alternative option in treating Achilles sleeve avulsion. More cases and longer follow up are needed in order to find the best reconstructive option for this pathology.

LEVELS OF EVIDENCE

Level IV.

Bilateral changes in tendon structure of patients diagnosed with unilateral insertional or midportion achilles tendinopathy or patellar tendinopathy

PURPOSE

Changes in tendon structure are commonly seen in patients with unilateral achilles (AT) or patellar (PT) tendinopathy but might also be present on the asymptomatic side, indicating a higher risk for developing symptoms. The aim of this study is to compare tendon structure of the symptomatic side with the asymptomatic side in AT and PT patients and control subjects.

METHODS

A total of 46 patients with unilateral AT (16 insertional and 30 midportion) and 38 with unilateral PT were included. For the control group, a total of 18 Achilles tendons and 25 patellar tendons were scanned. Tendon structure was assessed using ultrasound tissue characterisation (UTC), which quantifies tendon organisation dividing the structure into four different echo types (I-IV).

RESULTS

There were significant differences in echo types I, III, and IV between symptomatic and asymptomatic sides and controls. Additionally, there was a significant difference between the symptomatic and the asymptomatic side for all tendinopathy locations. In the insertional AT tendon portion, the symptomatic side showed a higher percentage of echo type III. For the midportion AT, the symptomatic side showed a lower percentage of echo type I and a higher percentage of echo types III and IV. For the patellar tendon, the symptomatic side showed a higher percentage of echo types III and IV. All differences were higher than the minimal detectable changes.

CONCLUSION

Although patients have symptoms unilaterally, the tendon structures are compromised on both sides. These results stress the importance of monitoring both symptomatic and asymptomatic tendon structures and in addition highlight that the asymptomatic side should not be used as reference in clinical practice.

LEVEL OF EVIDENCE

III.

Effectiveness of Extracorporeal Shockwave Therapy in the Treatment of Chronic Insertional Achilles Tendinopathy

BACKGROUND

Extracorporeal shockwave therapy (ESWT) has been proposed as a conservative treatment for insertional Achilles tendinopathy from limited evidence without placebo controls. Our objective was to assess the effectiveness of ESWT compared with sham controls in chronic insertional Achilles tendinopathy.

METHODS

A double-blind, randomized sham-controlled trial was conducted between 2016 and 2018. The inclusion criteria were patients aged 18 to 70 years diagnosed with chronic insertional Achilles tendinopathy who failed standard conservative treatment. After computerized randomization, patients were allocated into either low-energy ESWT or sham control. Pain, function, and other complaints were assessed using visual analog scale (VAS) and VAS foot and ankle (VAS-FA) at preintervention and weeks 2, 3, 4, 6, 12, and 24. Intention-to-treat analysis and repeated measurement were performed using STATA 15.0.

RESULTS

Sixteen patients in ESWT and 15 patients in sham control groups had nonsignificant different baseline characteristics with preintervention VAS (6.0 ± 2.6 vs 5.2 ± 2.2) and VAS-FA (64.8 ± 16.6 vs 65.3 ± 12.7). There was no significant difference in VAS, VAS-FA, and its domains in the long term between the 2 groups. In addition, the ESWT group had significant improvement in VAS (2.9 ± 2.2) at weeks 4 to 12, and sham controls group had significantly improved VAS (2.3 ± 2.6) at weeks 12 to 24. Complications were found only after ESWT treatment.

CONCLUSION

There was no difference at 24 weeks with the use of low-energy ESWT for chronic insertional Achilles tendinopathy, especially in elderly patients. However, it may provide a short period of therapeutic effects as early as weeks 4 to 12.

LEVEL OF EVIDENCE

Level I, randomized controlled study.

Treatment of Acute Achilles Tendon Rupture

There is no clear consensus on the optimal treatment of acute Achilles tendon rupture. Recently, studies have demonstrated the critical role of functional rehabilitation in the treatment of ruptured Achilles tendons. Hence, conservative treatment is preferred by a growing number of surgeons seeking to treat the condition without the risk of complications from surgery. However, operative treatment is still considered as a more reliable treatment option for acute Achilles tendon rupture. In this review article, we provide an overview of recent treatment strategies for acute rupture of the Achilles tendon.

Achilles tendon complex: The anatomy of its insertional footprint on the calcaneus and clinical implications

The Achilles tendon is the largest, and most commonly torn tendon in the body. The Achilles is usually torn at a region of relative hypo-vascularity proximal to its insertion. However, partial thickness tears and other pathologies often occur at its insertion on the calcaneus. Anatomically, the insertion is a confluence of the gastrocnemius and soleus muscles that fuse to form a myotendinous unit on the posterosuperior aspect of the calcaneus. This review aims to reveal the insertional footprint as individual fascicular components attaching to facets of calcaneal tuberosity. Understanding this anatomy is essential for interpreting tear patterns and surgical implications.

Insertional Tendinopathy of the Achilles: Debridement, Primary Repair, and When to Augment

Insertional Achilles tendinopathy is a degenerative enthesopathy associated with pain and dysfunction. Nonsurgical management is first attempted for a period of 3 to 6 months and may consist of physical therapy with eccentric training and other modalities. Surgical treatment can be successful with a variety of approaches. A thorough debridement through a midline tendon-splitting approach is associated with high satisfaction rates. Flexor hallucis longus transfer to augment the repair is considered in older, heavier patients or if more than 50% of the tendon was debrided. Early functional rehabilitation is associated with excellent outcomes.

Achilles Impingement Tendinopathy on Magnetic Resonance Imaging

Haglund's syndrome is impingement of the retrocalcaneal bursa and Achilles tendon caused by a prominence of the posterosuperior calcaneus. Radiographic measurements are not sensitive or specific for diagnosing Haglund's deformity. Localization of a bone deformity and tendinopathy in the same sagittal section of a magnetic resonance imaging scan can assist with the diagnosis in equivocal cases. The aim of the present cross-sectional study was to determine the prevalence of Haglund's syndrome in patients presenting with Achilles tendinopathy and note any associated findings to determine the criteria for a diagnosis of Haglund's syndrome. We reviewed 40 magnetic resonance imaging scans with Achilles tendinopathy and 19 magnetic resonance imaging scans with Achilles high-grade tears and/or ruptures. Achilles tendinopathy was often in close proximity to the superior aspect of the calcaneal tuberosity, consistent with impingement (67.5%). Patients with Achilles impingement tendinopathy were more often female (p < .04) and were significantly heavier than patients presenting with noninsertional Achilles tendinopathy (p = .014) or Achilles tendon rupture (p = .010). Impingement tendinopathy occurred medially (8 of 20) and centrally (10 of 20) more often than laterally (2 of 20) and was associated with a posterior prominence or hyperconvexity with a loss of calcaneal recess more often than a superior projection (22 of 27 versus 8 of 27; p < .001). Haglund's deformity should be reserved for defining a posterior prominence or hyperconvexity with loss of calcaneal recess because this corresponds with impingement. Achilles impingement tendinopathy might be more appropriate terminology for Haglund's syndrome, because the bone deformity is often subtle. Of the 27 images with Achilles impingement tendinopathy, 10 (37.0%) extended to a location prone to Achilles tendon rupture. Given these findings, insertional and noninsertional Achilles tendinopathy are not mutually exclusive and impingement might be a subtle, unrecognized cause of Achilles tendinopathy and subsequent rupture.

Current trends in tendinopathy: consensus of the ESSKA basic science committee. Part I: biology, biomechanics, anatomy and an exercise-based approach

Chronic tendinopathies represent a major problem in the clinical practice of sports orthopaedic surgeons, sports doctors and other health professionals involved in the treatment of athletes and patients that perform repetitive actions. The lack of consensus relative to the diagnostic tools and treatment modalities represents a management dilemma for these professionals. With this review, the purpose of the ESSKA Basic Science Committee is to establish guidelines for understanding, diagnosing and treating this complex pathology.

Insertional Achilles Tendinopathy

Posterior heel pain is a common condition of the foot and ankle and is seen in a variety of foot types. Nonoperative treatment methods consisting of shoes inserts, heel lifts, stretching, physical therapy, nonsteroidal antiinflammatory drugs, eccentric strength training, and other modalities have been shown to have mixed results. When indicated, surgical repair can produce good long-term results. Complications, although uncommon, most commonly result from wound healing complications.

Quantification of Internal Stress-Strain Fields in Human Tendon: Unraveling the Mechanisms that Underlie Regional Tendon Adaptations and Mal-Adaptations to Mechanical Loading and the Effectiveness of Therapeutic Eccentric Exercise

By virtue of their anatomical location between muscles and bones, tendons make it possible to transform contractile force to joint rotation and locomotion. However, tendons do not behave as rigid links, but exhibit viscoelastic tensile properties, thereby affecting the length and contractile force in the in-series muscle, but also storing and releasing elastic stain energy as some tendons are stretched and recoiled in a cyclic manner during locomotion. In the late 90s, advancements were made in the application of ultrasound scanning that allowed quantifying the tensile deformability and mechanical properties of human tendons in vivo. Since then, the main principles of the ultrasound-based method have been applied by numerous research groups throughout the world and showed that tendons increase their tensile stiffness in response to exercise training and chronic mechanical loading, in general, by increasing their size and improving their intrinsic material. It is often assumed that these changes occur homogenously, in the entire body of the tendon, but recent findings indicate that the adaptations may in fact take place in some but not all tendon regions. The present review focuses on these regional adaptability features and highlights two paradigms where they are particularly evident: (a) Chronic mechanical loading in healthy tendons, and (b) tendinopathy. In the former loading paradigm, local tendon adaptations indicate that certain regions may “see,” and therefore adapt to, increased levels of stress. In the latter paradigm, local pathological features indicate that certain tendon regions may be “stress-shielded” and degenerate over time. Eccentric exercise protocols have successfully been used in the management of tendinopathy, without much sound understanding of the mechanisms underpinning their effectiveness. For insertional tendinopathy, in particular, it is possible that the effectiveness of a loading/rehabilitation protocol depends on the topography of the stress created by the exercise and is not only reliant upon the type of muscle contraction performed. To better understand the micromechanical behavior and regional adaptability/mal-adaptability of tendon tissue it is important to estimate its internal stress-strain fields. Recent relevant advancements in numerical techniques related to tendon loading are discussed.

A Proposed Staging Classification for Minimally Invasive Management of Haglund's Syndrome with Percutaneous and Endoscopic Surgery

Haglund's syndrome encompasses several different pathologies, including Haglund's deformity, insertional Achilles tendonopathy, retrocalcaneal bursitis, and superficial bursitis. Traditionally treated with open surgery, there is increasing interest in a more minimally invasive approach to this difficult region to reduce complications and improve the rate and ease of recovery. We review the evidence available for 2 of these techniques: the endoscopic calcaneoplasty and percutaneous Zadek's calcaneal osteotomy (also known as Keck and Kelly's osteotomy). The senior author's classification for management of the condition is presented as well as describing his operative technique for these procedures.

The Degeneration of Meniscus Roots Is Accompanied by Fibrocartilage Formation, Which May Precede Meniscus Root Tears in Osteoarthritic Knees

BACKGROUND

Fibrocartilage metaplasia in tendons and ligaments is an adaptation to compression as well as a pathological feature during degeneration. Medial meniscus posterior roots are unique ligaments that resist multidirectional forces, including compression.

PURPOSE

To characterize the degeneration of medial meniscus posterior root tears in osteoarthritic knees, with an emphasis on fibrocartilage and calcification.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Samples of medial meniscus posterior roots were harvested from cadaveric specimens and patients during knee replacement surgery and grouped as follows: normal reference, no tear, partial tear, and complete tear. Degeneration was analyzed with histology, immunohistochemistry, and real-time polymerase chain reaction. Uniaxial tensile tests were performed on specimens with and without fibrocartilage. Quantifiable data were statistically analyzed by the Kruskal-Wallis test with the Dunn comparison test.

RESULTS

Thirty, 28, and 42 samples harvested from 99 patients were allocated into the no tear, partial tear, and complete tear groups, respectively. Mean modified Bonar tendinopathy scores for each group were 3.97, 9.31, and 14.15, respectively, showing a higher degree of degeneration associated with the extent of the tear (P < .05 for all groups). The characterization of root matrices revealed an increase in fibrocartilage according to the extent of the tear. Tear margins revealed fibrocartilage in 59.3% of partial tear samples and 76.2% of complete tear samples, with a distinctive cleavage-like shape. Root tears with a similar shape were induced within fibrocartilaginous areas during uniaxial tensile testing. Even in the no tear group, 56.7% of samples showed fibrocartilage in the anterior margin of the root, adjacent to the meniscus. An increased stained area of calcification and expression of the ectonucleotide pyrophosphatase/phosphodiesterase 1 gene were observed in the complete tear group compared with the no tear group (P < .0001 and P = .24, respectively).

CONCLUSION

Fibrocartilage and calcification increased in medial meniscus posterior roots, associated with the degree of the tear. Both findings, which impair the ligament's resistance to tension, may play a pivotal role during the pathogenesis of degenerative meniscus root tears in osteoarthritic knees. Fibrocartilage and calcification may be useful as diagnostic markers as well as markers of degeneration, which may aid in determining the treatment modality in meniscus root tears. The presence of fibrocartilage in intact roots may suggest an impending tear in osteoarthritic knees.

Histological evaluation of calcaneal tuberosity cartilage--A proposed donor site for osteochondral autologous transplant for talar dome osteochondral lesions

BACKGROUND

Osteochondral Autologous Transplant (OATs) as a treatment option for Osteochondral lesions (OCLs) of the talar dome frequently uses the distal femur as the donor site which is associated with donor site morbidity in up to 50%. Some studies have described the presence of hyaline cartilage in the posterior superior calcaneal tuberosity. The aim of this study was to evaluate the posterior superior calcaneal tuberosity to determine if it can be a suitable donor site for OATs of the talus

METHODS

In this cadaveric study, we histologically evaluated 12 osteochondral plugs taken from the posterior superior calcaneal tuberosity and compared them to 12 osteochondral plugs taken from the talar dome.

RESULTS

In the talar dome group, all samples had evidence of hyaline cartilage with varying degrees of GAG staining. The average hyaline cartilage thickness in the samples was 1.33 mm. There was no evidence of fibrocartilage, fibrous tissue or fatty tissue in this group. In contrast, the Calcaneal tuberosity samples had no evidence of hyaline cartilage. Fibrocartilage was noted in 3 samples only.

CONCLUSIONS

We believe that the structural differences between the talus and calcanium grafts render the posterior superior clancaneal tuberosity an unsuitable donor site for OATs in the treatment of OCL of the talus.

Insertional Achilles tendinopathy is associated with arthritic changes of the posterior calcaneal cartilage: a retrospective study

Background

To characterize the histological changes within the posterior calcaneal cartilage in patients with insertional Achilles tendinopathy (IAT) and test the relationships between severity of the histological changes and level of functional impairment.

Methods

Sixteen posterior calcaneal wall specimens of patients with IAT who had posterior calcaneal ostectomy were investigated. Hematoxylin-eosin stain, Toluidine-blue stain, Polarized light microscopy, and Masson Trichrome stain were used to characterize histological changes. Changes within the posterior calcaneal wall cartilage were graded according to Osteoarthritis Research Society International (OARSI) criteria. Functional scores were completed at the time of surgery according to the American Orthopedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score.

Results

Mean age of patients was 48.9 years. Histological findings within the posterior calcaneal wall cartilage specimens were consistent with arthritic changes. OARSI grading indicated Grade 2 changes in one specimen, mean AOFAS score 60; Grade 3 changes in three specimens, AOFAS score 73.7 ± 2.5; Grade 4 changes in four specimens, AOFAS score 44 ± 21.4; Grade 5 changes in eight specimens, AOFAS score 48 ± 9.9. Higher OARSI grades were correlated with lower AOFAS scores (rho = −0.65, p < 0.01).

Conclusions

Degenerative arthritic changes of the posterior calcaneal wall cartilage characterize patients with IAT and the severity of such changes is directly correlated to the degree of functional impairment.

Percutaneous ultrasonic debridement of tendinopathy-a pilot Achilles rabbit model

Background

Tendinopathy is a common clinical pathology, with mixed treatment results, especially when chronic. In this study, we examine the effects of an ultrasonic debridement modality in a rabbit tendinopathy model.

We asked four questions: 1) Was it possible to create and visualize with ultrasound a tendinopathy lesion in a rabbit Achilles tendon? 2) Was it possible to guide a 19-gauge ultrasonic probe into the tendinopathy lesion? 3) Following ultrasonic treatment, was tendinopathy debris histologically present? and 4) Was the collagen profile qualitatively and quantitatively normalized following treatment?

Methods

Skeletally mature female New Zealand white rabbits (n = 12) were injected with, ultrasonography localization, 0.150 ml of collagenase into the Achilles tendon. The collagenase-induced Achilles tendinopathy (3 weeks) was treated with percutaneous ultrasonic debridement. The tendons were harvested, at 3 weeks after treatment, and were subjected to histological assessment (modified Movin score) and biochemical analysis (collagen isoform content).

Results

Histopathological examination revealed that all tendons injected with collagenase showed areas of hypercellularity and focal areas of tendon disorganization and degeneration. The treated tendons had lower (improved) histopathological scores than injured tendons (P < 0.001). Western blot analysis showed that ultrasonic therapy restored, within statistical limits, collagen type I, III, and X expressions in a treated tendon, to qualitative and semi-quantitative levels of a normal tendon.

Conclusions

We were successfully able to create a collagenase-injected tendinopathy lesion in a rabbit Achilles tendon and visualize the lesion with an ultrasound probe. A 19-gauge ultrasonic probe was inserted into the tendinopathic lesion under direct ultrasound guidance, and minimal tendinopathic debris remained after treatment. The treated tendon demonstrated a normalized qualitative and semi-quantitative collagen profile and improved histological appearance in the short term. This technique demonstrates scientific merit with respect to the minimally invasive treatment of tendinopathy and warrants further studies.

Clinical relevance

Recalcitrant tendinopathy has evaded consistent non-operative treatment since the tendinopathic debris remains in situ, to some extent, with non-operative approaches. This percutaneous emulsification/evacuation approach, under direct ultrasound visualization, has the potential to cure recalcitrant tendinopathies without open surgery, which would benefit the patient and result in significant healthcare cost reductions.

Histopathological features of hypertrophic bone mass of temporomandibular joint ankylosis (TMJA): An explanation of pathogenesis of TMJA

Temporomandibular joint ankylosis (TMJA) is a severe organic disease with progressive limitation of the mouth opening. Histopathologically, a residual joint space is reported to consist of fibrous tissue and/or cartilage, indicating two types of interface (osteo-fibrous and osteo-chondral) of residual joint space. It is well known that adverse mechanical stress results in pathological changes of osteoarthritis and enthesopathy in these interfaces. What would happen pathologically in these interfaces of TMJA under repeated mandible movement has not been elucidated. Fourteen tissue samples of residual joint space and temporal and condylar bone were stained with hematoxylin and eosin and evaluated by collagen I and II immunohistochemistry. A pathological study of 14 TMJA patients showed that the residual joint space presented a fibrocartilage entheses structure and an articular cartilage structure. Moreover, these two structures were associated with pathological alterations of both osteoarthritis and enthesopathy, including degenerated and necrotized tissue, chondrocyte cloning, crack and fissure, various bone scleroses, and inflammatory granulation tissue. It is suggested that the pathological alterations of both osteoarthritis and enthesopathy occurred in TMJA, which hints at mechanical stress on TMJA development.

Further Data on Sesamoid Identity from Two Anuran Species

Considering that the identification of equivalent entities is the basis for any comparative analysis, we compare the histology, histochemistry, shape and dimensions of epiphyses, carpal and sesamoids in two anuran frogs. Our goal was to explore the morphological correspondence among these three skeletal elements in order to clarify the sesamoid identity. We studied the skeletogenesis, contour geometric morphometry and dimensions of forelimb elements of juveniles of two anurans species Leptodactylus bufonius and Rhinella arenarum. Skeletogenesis in anurans present a common trait between carpals and sesamoids: both elements exhibit endochondral ossification. A difference between these elements is the presence of fibrocartilage in the development of sesamoids. The geometric morphometry does not allow us to establish a shape pattern that can be compared either between sesamoids and epiphyses or carpals. With regard to dimensions, our data indicate that bones categorization based on these aspects is ambiguous and therefore is useless to classify of skeletal bones. The data about tissue differentiation of sesamoids provide evidence that support the idea that these elements should be considered part of the typical endowment of the vertebrate skeleton.

The short-term effect after a single injection of high-molecular-weight hyaluronic acid in patients with enthesopathies (lateral epicondylitis, patellar tendinopathy, insertional Achilles tendinopathy, and plantar fasciitis): a preliminary study

BACKGROUND

Hyaluronic acid (HA) with a high molecular weight of 2700 kDa is approved in Japan to treat osteoarthritis of the knee, periarthritis scapulohumeralis, and knee pain associated with rheumatoid arthritis. The purpose of this preliminary study was to investigate the short-term efficacy, safety, and injectable volume of HA in the treatment of enthesopathies.

METHODS

A total of 61 patients (16 with lateral epicondylitis, 14 with patellar tendinopathy, 15 with insertional Achilles tendinopathy, and 16 with plantar fasciitis) were each administered a single injection of HA (up to 2.5 ml). Efficacy and safety were assessed by comparing the visual analog scale (VAS) for pain and local symptoms before injection (baseline) and at 1 week after injection. We also investigated the injectable volume by means of the difference in syringe weight before and after injection and by the judgment of the administering investigator.

RESULTS

The injection of HA resulted in a change in VAS (mean ± SD) of -2.20 ± 2.26 cm for the four sites overall and -2.55 ± 2.43 cm for lateral epicondylitis, -2.01 ± 2.16 cm for patellar tendinopathy, -1.80 ± 1.91 cm for insertional Achilles tendinopathy, and -2.38 ± 2.61 cm for plantar fasciitis. The injection of HA also improved local symptoms in each site. It was also determined that 2.5 ml of HA can be injected in each of the four sites.

CONCLUSION

A single injection of HA resulted in similar improvements of pain in each of the four enthesopathies (lateral epicondylitis, patellar tendinopathy, insertional Achilles tendinopathy, and plantar fasciitis). These results suggest that HA could be clinically effective in the treatment of enthesopathies.