Current concepts on the morphology of popliteus tendon and its clinical implications.

In this review we described the anatomy and biomechanics of popliteus muscle and its tendon. Furthermore, we combined the anatomy with clinics and discussed a wide spectrum of disorders regarding the popliteus and its musculotendinous complex. There are three main anatomical regions of the popliteus musculotendinous complex: the proximal origin, the mid-portion, the distal part on the tibia. The unique localisation and various origins of the tendon, connected with structures such as fibular head, Wrisberg, Humphrey and posterior cruciate ligament, lateral meniscus, medial collateral ligament, give an implication to diagnosis and treatment. Popliteus dysfunction is often overlooked, that is the reason why diagnosis and treatment of its injuries is mostly insufficient. Repetitive or acute direct varus forces, when the tibia is in external rotation, and knee hyperextension or flexion with forced external rotation of the tibia, are the main mechanisms of trauma. Popliteus injuries mainly affect the athletic population and lead to severe activity limitations. Chronic disorders of the popliteus tendon, less known, are often described as tendinopathy and are frequently seen in runners. Their symptoms can mimic the lateral meniscal tears. On the other hand, high-energy traumatic injuries of the popliteus tendon often accompany complex, multi ligamentous injuries seen in competitive sports. We also presented the implication of popliteus tendon in knee arthroplasty, due to its particular exposition to iatrogenic trauma during surgery. The issues such as proper tibial component location and well-designed cut systems are crucial to avoid the popliteus impingement and preserve its structure.

The surgical treatment of the long head of biceps tendon and the autotenodesis phenomenon: an ultrasound and arthroscopic study.

BACKGROUND: Open or mini-invasive operative procedures are methods of choice in the treatment of the advanced degenerative process of tendinopathy of long head of biceps tendon (LHBT). Cosmetic arm deformity and fatigue are the main complaints after the surgery. Researchers have noticed that in some cases the typical cosmetic deformity is often barely noticeable and the pain is significantly reduced as it occurs after spontaneous LHBT rupture due to extremely advanced tendinopathy. MATERIALS AND METHODS: This study included 41 of 75 patients who underwent LHBT arthroscopy-assisted tenotomy, followed by examination conducted by means of dedicated clinical tests, the American Shoulder and Elbow Surgeons Score (ASES) and ultrasounds. RESULTS: The average time interval from surgery to follow-up in the cohort was 31 months, the mean outcome measured with the ASES was 87 points and the "Popeye deformity" complication was present in 15 individuals. In the group of 26 patients where the Popeye deformity was absent and the arm contour was similar to that of the opposite arm, sonographic examination revealed the LHBT stump at the level of the intertubercular groove that was hyperechogenic and wider than the part under the groove. CONCLUSIONS: Recent reports about the absence of the cosmetic deformity in the anterior area of the arm after shoulder arthroscopy are based on the autotenodesis phenomenon. The intra-articular part of LHBT is painlessly trapped in the bicipital groove by the surrounding soft tissues, which results in unchanged biceps muscle length; however, it is more probable to happen in patients without massive rotator cuff tears.

Osseointegration of hydroxyapatite coatings doped with silver nanoparticles: scanning electron microscopy studies on a rabbit model.

BACKGROUND: Modern joint arthroplasties rely on osseointegration of metal components through bone ingrowth into hydroxyapatite (HA) layers. However, such surfaces are prone to colonisation by bacteria and formation of biofilms. Application of silver nanoparticles (SNs) to hydroxyapatite coatings could reduce the risk of infection; however, little is known about how this would affect the process of bone ingrowth. This study examined osseointegration of conventional and SN doped HA coatings in a rabbit model. MATERIALS AND METHODS: In this study, 12 cylindrical implants coated with conven- tional and SN doped HA were implanted into New Zealand white rabbit femora, with each animal receiving both types of implants. After 12 weeks, rabbits were sacrificed, their femora were harvested and implants removed during pull-out testing. Retrieved samples were dehydrated, sputter coated and observed using a scanning electron microscope (SEM) to verify bony ingrowth and retention of SNs. RESULTS: The percentage of implant in direct contact with bone was measured in cross-sections of implants. The SEM analysis demonstrated that osseointegration of the SN doped coatings was similar to the conventional HA samples. A similar morphology of newly formed trabecular bone was observed in both implants, with silver doped HA-coated implants retaining multiple nanoparticles in areas which were not overgrown by bone. Analysis of the bone-implant contact area revealed comparable results for both types of coatings. These finding indicated that SN doped HA coatings are characterised by good osseointegrative properties. CONCLUSIONS: Since SNs were found in areas not covered by mineralised bone, it is assumed that the antimicrobial properties of the modified coating may be retained for 12 weeks after implantation. Additional studies are required to fine--tune the composition of HA coatings with SNs, to ensure optimal osseointegrative and antimicrobial properties.

Sonography in the instability of the long head of the biceps tendon confronted with histopathologic and arthroscopic findings.

BACKGROUND: Disorders of the long head of the biceps (LHB) tendon are a common source of shoulder pain and disability. This tendon can be well visualised using ultrasonography; however, little is known if such examination allows clinicians to predict pathological changes of the tendon structure. In the study described below, we compare preoperative sonographic findings with the data from shoulder arthroscopy and microscopic examination of the excised tendon fragments in 19 consecutive patients with LHB tendinopathy and clinical suspicion of its instability. MATERIALS AND METHODS: Preoperative ultrasonographic (US) inspection assessed several features of the tendon, whereas its stability was verified arthroscopically. In all cases, tenodesis or tenotomy procedures were performed and excised tendon fragments were harvested for microscopic examination based on the semiquantitative Bonar score. RESULTS: The most common US findings were hypoechoic areas, tendon thickening, an increased power Doppler signal and mechanical instability. Just as shoulder arthroscopy confirmed all mechanical instability cases detected in US, microscopic assessment revealed advanced degeneration in all samples. CONCLUSIONS: Our study indicates that US is a useful tool in identifying cases of advanced instability and LHB tendinopathy, whereas biceps tendon instability is a biomechanically complex, gradually progressing phenomenon, frequently associated with additional shoulder lesions.

Tendon - function-related structure, simple healing process and mysterious ageing.

Tendons are connective tissue structures of paramount importance to human ability of locomotion. The understanding of their physiology and pathology is gaining importance as advances in regenerative medicine are being made today. So far, very few studies were conducted to extend the knowledge about pathology, healing response and management of tendon lesions. In this paper we summarise actual knowledge on structure, process of healing and ageing of the tendons. The structure of tendon is optimised for the best performance of the tissue. Despite the simplicity of the healing response, numerous studies showed that the problems with full recovery are common and much more significant than we thought; that is why we discussed the issue of immobilisation and mechanical stimulation during healing process. The phenomenon of tendons' ageing is poorly understood. Although it seems to be a natural and painless process, it is completely different from degeneration in tendinopathy. Recent studies of biological treatment reported faster and optimal healing of the tendons when augmented by growth factors and stem cells. Despite advances in biology of tendons, management of their injuries is still a challenge for physicians; therefore, further studies are required to improve treatment outcomes.

Electron microscope study of the advanced tendinopathy process of the long head of the biceps brachii tendon treated arthroscopically.

BACKGROUND: The ultrastructural alterations related to tendinopathy have not been well described. Most studies on this subject have been conducted many years ago and focused on material from the Achilles tendon. It was demonstrated that various comorbidities can affect ultrastructural alterations in the advanced tendinopathy; however, there is very little data on ultrastructural morphology in tendinopathies related to mechanical overload as in case of the long head of the biceps brachii tendon (LHBT). The aim was to determine intermediate ultrastructural alterations in middle to severe grade the LHBT tendinopathy and to establish if they are different than those reported in the literature for other anatomical locations. MATERIALS AND METHODS: In this study we examined the ultrastructure of a series of the LHBT fragments arthroscopically removed due to tendinopathy and inve-stigated the morphology of tenocytes and collagen fibres in cases of the LHBT tendinopathy. RESULTS: In pathological samples tenocytes were randomly scattered, their shape was round and the shape of nuclei was also disrupted. The presence of apoptotic--like features in tenocytes' nuclei was noted. All samples showed replacement of collagen fibrils by non-collagen extracellular matrix and diffuse collagen disorganisation. CONCLUSIONS: It was demonstrated at ultrastructural level that the LHBT tendino-pathy is not simply a wear and tear phenomenon, since chronic degeneration of the extracellular matrix and tenocytes were present, similarly as in tendinopathies, in other anatomical locations. (Folia Morphol 2018; 77, 2: 371-377).

Process of neovascularisation compared with pain intensity in tendinopathy of the long head of the biceps brachii tendon associated with concomitant shoulder disorders, after arthroscopic treatment. Microscopic evaluation supported by immunohistochemical.

BACKGROUND: Tendinopathy of the long head of the biceps brachii tendon (LHBT) is one of the most common, painful conditions of the anterior part of the shoulder and often coexists with rotator cuff tears. Multifactorial aetiopathology of tendi-nopathy is poorly understood; however, several studies indicated that it is seen predominantly in areas with decreased vascularity of the tissue; the pathology is also characterised by expansive and abundant neovascular in-growth. The aim of the study was to investigate the relationship between the neovascularisation of proximal part of the LHBT and pain along the bicipital groove. MATERIALS AND METHODS: Tissue material was obtained from 28 patients who underwent a shoulder arthroscopy and experienced pain along the bicipital groove measured using Visual-Analog Scale (VAS) score. CD31 and CD34 molecules were visualised by immunohistochemical method to assess biceps tendon neovascula-risation and quantify it based on a Bonar scoring system. RESULTS: Although all patients reported pain prior to arthroscopy (mean VAS score was 7.5), microscopic examination did not reveal neovascularisation in all cases. Immunohistochemical staining for CD31 and CD34 allowed for very precise visualisation and quantification of neovascularisation; however there was also no correlation between vessels in-growth scores and pain. CONCLUSIONS: The obtained data suggest that neovascularisation process in tendino-pathy is not directly related to pain; however, further studies are needed to explain its significance in the LHBT tendinopathy. (Folia Morphol 2018; 77, 2: 378-385).