[Partial Achilles tendon ruptures exist]

In this case report a typical case with partial Achilles tendon rupture is described. Because of unspecific symptoms, near normal MRI and no clinical signs of total rupture the diagnosis was delayed for almost four months. Open surgery showed a partial Achilles tendon rupture without significant signs of tendinopathy. The tendon was sutured and the post-operative period was uneventful.

Acetabular anteversion is associated with gluteal tendinopathy at MRI

OBJECTIVE

Gluteal tendinopathy and greater trochanteric pain syndrome (GTPS) remain incompletely understood despite their pervasiveness in clinical practice. To date, no study has analyzed the morphometric characteristics of the hip on magnetic resonance imaging (MRI) that may predispose to gluteal tendinopathy. This study aimed to evaluate whether acetabular anteversion (AA), femoral neck anteversion (FNA), and femoral neck-shaft angle (FNSA) are associated with MRI features of gluteal tendinopathy.

MATERIALS AND METHODS

A total of 203 MRI examinations of the hip met our inclusion and exclusion criteria. A single blinded investigator measured AA, FNA, and FNSA according to validated MRI techniques. Two blinded subspecialty-trained musculoskeletal radiologists then independently evaluated the presence of gluteal tendinosis, trochanteric bursitis, and subgluteal bursitis. Statistical analysis was performed using a one-way analysis of variance (ANOVA; post-hoc Tukey's range test).

RESULTS

At MRI, 57 patients had gluteal tendinosis with or without bursitis, 26 had isolated trochanteric bursitis, and 11 had isolated subgluteal bursitis. AA was significantly (p = 0.01) increased in patients with MRI evidence of gluteal tendinosis with or without bursitis [mean: 18.4°, 95 % confidence interval (CI): 17.2°-19.6°] compared with normal controls (mean: 15.7°, 95 % CI: 14.7°-16.8°). Similarly, AA was significantly (p = 0.04) increased in patients with isolated trochanteric bursitis (mean: 18.8°, 95 % CI: 16.2°-21.6°). No association was found between FNA or FNSA and the presence of gluteal tendinopathy. Interobserver agreement for the presence and categorization of gluteal tendinopathy was very good (kappa = 0.859, 95 % CI: 0.815-0.903).

CONCLUSION

Our MRI study suggests that there is an association between increased AA and gluteal tendinopathy, which supports a growing body of evidence implicating abnormal biomechanics in the development of this condition.

Therapeutic effects of high molecular weight hyaluronan injections for tendinopathy in a rat model

BACKGROUND

Tendinopathy is the most common tendon disorder. The etiology is still uncertain, and the disorder poses many therapeutic problems. In a few clinical studies, analgesic effects of high molecular weight hyaluronan (HMW HA) injections were observed, but the underlying mechanisms were not elucidated. In the present study, we analyzed the therapeutic effects of hyaluronan injections for tendinopathy in an animal model.

METHODS

We made the tendinopathy rat model using a rodent treadmill machine. Rats with tendinopathy were injected with HMW HA (HA group), normal saline (NS group), or nothing (control group) into the space between the patellar tendon and the fat pad bilaterally, or were injected with HMW HA into the right knees and with saline to the left knees (HA/NS group), 5 times every 4 days. To assess the pain-relieving effect of HA, the spontaneous locomotor activities at night (12 h) and weight bearing of hind paws were measured every day. Histological sections of the patellar tendon stained with hematoxylin-eosin or prepared by TdT-mediated dUTP nick end labeling were microscopically analyzed.

RESULTS

The number of spontaneous locomotor activities in the HA group was significantly larger than those in NS or control groups, and in the HA group they recovered up to a healthy level. The percent weight distribution of the right hind paws was significantly increased along with the number of injections. On histologic examinations, the numbers of microtears, laminations, or apoptotic cells in the patellar tendons in the HA group were significantly lower than those in the NS or the control groups.

CONCLUSIONS

The injections of HMW HA were effective for pain relief and for partial restoration of the patellar tendon in our tendinopathy rat model, and thus may become an effective therapeutic modality for the disease.

Achilles and patellar tendon morphology in dancers with and without tendon pain

OBJECTIVES

To examine Achilles and patellar tendon morphology in dancers with and without tendon pain.

METHODS

Fifty-three dancers with and without Achilles and/or patellar tendon pain participated. Eleven age-matched non-dancers served as controls. Longitudinal ultrasound images of the middle and distal Achilles and proximal and distal patellar tendons were acquired. To assess macromorphology, the thickness of the middle and distal Achilles and proximal and distal patellar tendons were measured. Micromorphology was analyzed by selecting 2 x 2-mm2 regions of interest in the tendons; spectral analysis using the fast Fourier transform was run for several kernels (2 x 2-mm2 subimages) within each image, and the peak spatial frequency (PSF) was extracted. A one-way ANOVA compared asymptomatic, symptomatic, and control tendon thickness and PSF.

RESULTS

Macromorphology: There was no significant difference between asymptomatic and symptomatic dancers in middle or distal Achilles tendon thickness and distal patellar tendon thickness. Proximal patellar tendons in control subjects were thinner than those in asymptomatic (p=0.036) and symptomatic (p=0.003) dancers. Micromorphology: There was no significant difference in PSF between asymptomatic and symptomatic dancers and controls in the Achilles or patellar tendon.

CONCLUSION

Increased proximal patellar tendon thickness without changes in tendon micromorphology suggests that tendon adaptations are more likely activity-related and less likely influenced by degeneration.

Changes in morphological and elastic properties of patellar tendon in athletes with unilateral patellar tendinopathy and their relationships with pain and functional disability

BACKGROUND

Patellar tendinopathy (PT) is one of the most common knee disorders among athletes. Changes in morphology and elasticity of the painful tendon and how these relate to the self-perceived pain and dysfunction remain unclear.

OBJECTIVES

To compare the morphology and elastic properties of patellar tendons between athlete with and without unilateral PT and to examine its association with self-perceived pain and dysfunction.

METHODS

In this cross-sectional study, 33 male athletes (20 healthy and 13 with unilateral PT) were enrolled. The morphology and elastic properties of the patellar tendon were assessed by the grey and elastography mode of supersonic shear imaging (SSI) technique while the intensity of pressure pain, self-perceived pain and dysfunction were quantified with a 10-lb force to the most painful site and the Victorian Institute of Sport Assessment-patella (VISA-P) questionnaire, respectively.

RESULTS

In athletes with unilateral PT, the painful tendons had higher shear elastic modulus (SEM) and larger tendon than the non-painful side (p<0.05) or the dominant side of the healthy athletes (p<0.05). Significant correlations were found between tendon SEM ratio (SEM of painful over non-painful tendon) and the intensity of pressure pain (rho  = 0.62; p = 0.024), VISA-P scores (rho  = -0.61; p = 0.026), and the sub-scores of the VISA-P scores on going down stairs, lunge, single leg hopping and squatting (rho ranged from -0.63 to -0.67; p<0.05).

CONCLUSIONS

Athletes with unilateral PT had stiffer and larger tendon on the painful side than the non-painful side and the dominant side of healthy athletes. No significant differences on the patellar tendon morphology and elastic properties were detected between the dominant and non-dominant knees of the healthy control. The ratio of the SEM of painful to non-painful sides was associated with pain and dysfunction among athletes with unilateral PT.

The effects of substance P on pluripotent tendon cells: an in vitro and in vivo study

Pluripotent tendon cells (PTCs) play important roles in maintaining metabolic balance and the development of tendinopathy. Recently, substance P (SP) was identified as an important factor in the pathogenesis of tendinopathy. A better understanding of SP's effects on PTCs is essential to gain more insight into tendinopathy. This study aims to investigate the effects of SP on PTCs in vitro and in vivo. For the in vitro study, we quantified exogenous SP production by PTCs and determined the effects of SP on the proliferation and differentiation of PTCs. For the in vivo study, we used a rat patella tendon injection model to investigate the biological effects of SP on PTCs and tendons. Our results showed that exogenous SP production by PTCs was 1.80 pg/10(6) cells and SP significantly enhanced the proliferation of PTCs. Reverse transcription polymerase chain reaction (RT-PCR) results showed that SP upregulated the expression of non-tenocyte genes but downregulated the expression of tenocyte-related genes in the differentiation of PTCs. Moreover, Histological examination showed that SP induced disorganizes of tissue and tendinosis-like changes in vivo. Taken together, these findings indicate that SP enhanced PTCs' proliferation, induced non-tenocyte differentiation and plays an important role in the development of tendinopathy.

Detailed shoulder MRI findings in manual wheelchair users with shoulder pain

Shoulder pain and pathology are common in manual wheelchair (MWC) users with paraplegia, and the biomechanical mechanism of injury is largely unknown. Establishing patterns of MRI characteristics in MWC users would help advance understanding of the mechanical etiology of rotator cuff disease, thus improving the logic for prescribed interventions. The purpose of this study was to report detailed shoulder MRI findings in a sample of 10 MWC users with anterolateral shoulder pain. The imaging assessments were performed using our standardized MRI Assessment of the Shoulder (MAS) guide. The tendon most commonly torn was the supraspinatus at the insertion site in the anterior portion in either the intrasubstance or articular region. Additionally, widespread tendinopathy, CA ligament thickening, subacromial bursitis, labral tears, and AC joint degenerative arthrosis and edema were common. Further reporting of detailed shoulder imaging findings is needed to confirm patterns of tears in MWC users regarding probable tendon tear zone, region, and portion. This investigation was a small sample observational study and did not yield data that can define patterns of pathology. However, synthesis of detailed findings from multiple studies could define patterns of pathological MRI findings allowing for associations of imaging findings to risk factors including specific activities.

Serum and MRI biomarkers in mobile device texting: a pilot study

OBJECTIVE

We aimed to determine if serum biochemical and MRI biomarkers differed between high volume (> or =230 texts sent/day; n = 5) and low volume (< or =25 texts sent/day; n = 5) texters. A secondary aim was to ascertain what correlations between the biochemical and imaging biomarkers could tell us about the pathophysiology of early onset tendinopathies.

BACKGROUND

Text messaging has become widespread, particularly among college-aged young adults. There is concern that high rates of texting may result in musculoskeletal disorders, including tendinopathies. Pathophysiology of tendinopathies is largely unknown.

METHOD

Ten females with a mean age of 20 were recruited. We examined serum for 20 biomarkers of inflammation, tissue degeneration, and repair. We used conventional MRI and MRI mean intratendinous signal intensity (MISI) to assess thumb tendons. Correlations between MISI and serum biomarkers were also examined.

RESULTS

Three high volume texters had MRI tendinopathy findings as did one low volume texter. Increased serum TNF-RI was found in high volume texters compared to low volume texters, as were nonsignificant increases in MISI in two thumb tendons. Serum TNF-RI and TNF-alpha correlated with MISI in these tendons, as did ILI-RI.

CONCLUSION

These results suggest that early onset tendinopathy with concurrent inflammation may be occurring in prolific texters. Further studies with larger sample sizes are needed for confirmation. Application: High volume texting may be a risk factor for thumb tendinopathy in later years. Multidisciplinary research using biochemical and imaging biomarkers may be used to gain insight into pathophysiological processes in musculoskeletal disorders.

Soft-focused extracorporeal shock waves increase the expression of tendon-specific markers and the release of anti-inflammatory cytokines in an adherent culture model of primary human tendon cells

Focused extracorporeal shock waves have been found to upregulate the expression of collagen and to initiate cell proliferation in healthy tenocytes and to positively affect the metabolism of tendons, promoting the healing process. Recently, soft-focused extracorporeal shock waves have also been found to have a significant effect on tissue regeneration. However, very few in vitro reports have dealt with the application of this type of shock wave to cells, and in particular, no previous studies have investigated the response of tendon cells to this impulse. We devised an original model to investigate the in vitro effects of soft-focused shock waves on a heterogeneous population of human resident tendon cells in adherent monolayer culture. Our results indicate that soft-focused extracorporeal shock wave treatment (0.17 mJ/mm(2)) is able to induce positive modulation of cell viability, proliferation and tendon-specific marker expression, as well as release of anti-inflammatory cytokines. This could prefigure a new rationale for routine employment of soft-focused shock waves to treat the failed healing status that distinguishes tendinopathies.

The intraoperative use of ultrasound facilitates significantly the arthroscopic debridement of calcific rotator cuff tendinitis

INTRODUCTION

During arthroscopy, the localization of calcific deposit in patients suffering from calcifying tendinitis can be demanding and time consuming, frequently using ionizing radiation. Intraoperative ultrasound has been recently promoted, facilitating deposit localization and reducing radiation dose.

MATERIAL AND METHODS

In this prospective, randomized, controlled and clinical observer-blinded pilot trial, 20 patients with calcific tendinitis were operated. In group I, the deposit was localized conventionally. In group II, the deposit was localized using intraoperative ultrasound. The needle punctures to detect the deposit and operation times were noted. Patients were postoperatively evaluated after 2 and 6 weeks and 9 months.

RESULTS

In group II, the needle punctures to detect the deposit were significantly lower than in group I (p < 0.0001). Operation time to localize the deposit was also significantly less in group II (p < 0.033). In both groups, patients improved significantly with increased shoulder function (p < 0.0001) and decreased pain (p < 0.0001) 2 weeks and 9 months (p < 0.001) after surgery. The difference between the groups was not significant. Excellent radiological findings were obtained in both groups after 9 months.

CONCLUSIONS

Intraoperative US significantly facilitates the detection of calcific deposits during arthroscopic debridement by speeding up surgery and reducing the number of needle punctures. Hence, we have changed our method of detecting calcific deposits intraoperatively from fluoroscopy to ultrasound.

An overview of structure, mechanical properties, and treatment for age-related tendinopathy

Tendons transfer tensile loads from muscle to bone, which enable joint motions and stabilize joints. Tendons sustain large mechanical loads in vivo and as a result, tendons were frequently injured. Aging has been confirmed as a predisposing factor of tendinopathy and bad recovery quality following tendon repair. Current treatment methods are generally not effective and involve either symptomatic relief with non-steroidal antiinflammatory drugs and physical therapy or surgery when conservative treatments failed. The limitation in treatment options is due to our incomplete knowledge of age-related tendinopathy. Studies over the past decades have uncovered a number of important mechanical and cellular changes of aging tendon. However, the basis of aging as a major risk factor for tendon injury and impaired tendon healing remained poorly understood. The objectives of this review are to provide an overview of the current knowledge about the aging-associated changes of structure, mechanical properties and treatment in tendon and highlight causes and therapies for age-related tendinopathy.

Comparison of the effect of intra-tendon applications of recombinant human platelet-derived growth factor-BB, platelet-rich plasma, steroids in a rat achilles tendon collagenase model

This study compared the effect of intra-tendon (IT) delivery of recombinant human platelet-derived growth factor-BB (rhPDGF-BB), platelet-rich plasma (PRP) and corticosteroids in a rat tendinopathy model. Seven days after collagenase induction of tendinopathy, a 30-µl IT injection was administered. Treatments included: saline; 3 µg rhPDGF-BB; 10 µg rhPDGF-BB; PRP; and 300 µg triamcinolone acetonide (TCA). Outcomes were assessed 7 and 21 days after treatment. All groups exhibited good to excellent repair. Relative to saline, cell proliferation increased 65% in the 10 µg rhPDGF-BB group and decreased 74% in the TCA group; inflammation decreased 65% in the TCA group. At 7 days, maximum load-to-failure was increased in the 3 µg rhPDGF-BB group relative to saline, PRP, and TCA (p < 0.025). On day 21, maximum load-to-rupture was increased in the 10 µg rhPDGF-BB group relative to saline, PRP, and TCA (p < 0.035) and in the 3 µg rhPDGF-BB group compared to saline and TCA (p < 0.027). Stiffness in the 10 µg rhPDGF-BB group was increased compared to saline, PRP, and TCA (p < 0.038). Histology demonstrated similar repair in all groups. PRP and TCA did not improve mechanical properties compared to saline. Injections of rhPDGF-BB increased maximum load-to-failure (3 and 10 µg) and stiffness (10 µg) relative to controls and commonly used treatments. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:145-150, 2014.

Patellar tendinopathy - recent developments toward treatment

Patellar tendinopathy (PT) is a clinical and chronic overuse condition of unknown pathogenesis and etiology marked by anterior knee pain typically manifested at the inferior pole of the patella. PT has been referred to as "jumper's knee" since it is particularly common among populations of jumping athletes, such as basketball and volleyball players. Due to its common refractory response to conservative treatment, a variety of new treatments have emerged recently that include dry-needling, sclerosing injections, platelet-rich plasma therapy, arthroscopic surgical procedures, surgical resection of the inferior patellar pole, extracorporeal shock wave treatment, and hyperthermia thermotherapy. Since PT has an unknown pathogenesis and etiology, PT treatment is more a result of physician experience than evidence-based science. This review will summarize the current literature on this topic, identify current research efforts aimed to understand the pathological changes in abnormal tendons, provide exposure to the emerging treatment techniques, and provide suggested direction for future research.

Increased mast cell numbers in a calcaneal tendon overuse model

Tendinopathy is often discovered late because the initial development of tendon pathology is asymptomatic. The aim of this study was to examine the potential role of mast cell involvement in early tendinopathy using a high-intensity uphill running (HIUR) exercise model. Twenty-four male Wistar rats were divided in two groups: running group (n = 12); sedentary control group (n = 12). The running-group was exposed to the HIUR exercise protocol for 7 weeks. The calcaneal tendons of both hind limbs were dissected. The right tendon was used for histologic analysis using Bonar score, immunohistochemistry, and second harmonic generation microscopy (SHGM). The left tendon was used for quantitative polymerase chain reaction (qPCR) analysis. An increased tendon cell density in the runners were observed compared to the controls (P = 0.05). Further, the intensity of immunostaining of protein kinase B, P = 0.03; 2.75 ± 0.54 vs 1.17 ± 0.53, was increased in the runners. The Bonar score (P = 0.05), and the number of mast cells (P = 0.02) were significantly higher in the runners compared to the controls. Furthermore, SHGM showed focal collagen disorganization in the runners, and reduced collagen density (P = 0.03). IL-3 mRNA levels were correlated with mast cell number in sedentary animals. The qPCR analysis showed no significant differences between the groups in the other analyzed targets. The current study demonstrates that 7-week HIUR causes structural changes in the calcaneal tendon, and further that these changes are associated with an increased mast cell density.

[Experiment of bone morphogenetic protein 2 induced chondrogenic differentiation of human Achilles tendon-derived stem cells in vitro]

OBJECTIVE

To investigate the effects of bone morphogenetic protein 2 (BMP-2) on the chondrogenic differentiation of human Achilles tendon-derived stem cells (hATDSCs) in vitro.

METHODS

Achilles tendon was harvested from a voluntary donor with acute Achilles tendon rupture. And nucleated cells were obtained by digesting with collagenase and were cultured to the 3rd passage. The flow cytometry was used to measure the immunophenotyping; and Oil red O staining, alizarin red staining, and Safranin O/fast green staining were used to identify the adipogenic differentiation, osteogenic differentiation, and chondrogenic differentiation, respectively. The hATDSCs pellet was cultured in complete culture medium with (experimental group) or without recombinant human BMP-2 (rhBMP-2) (control grup) for 3 weeks. Chondrogenic differentiation of hATDSCs was evaluated by HE staining, Safranin O/fast green staining, and immunohistochemical staining for collagen type II; and the mRNA expressions of SOX9, collagen type II, and Aggrecan were detected by real-time fluorescence quantitative PCR.

RESULTS

Primary hATDSCs cultured in vitro showed clonal growth; after cell passage, homogeneous spindle fibroblast-like cells were seen. The cells were positive for CD44, CD90, and CD105, while negative for CD34, CD45, and CD146. The results were positive for Oil red O staining at 3 weeks after adipogenic differentiation, for alizarin red staining at 4 weeks after osteogenic differentiation, and for Safranin O/fast green staining at 3 weeks after chondrogenic differentiation. After hATDSCs were induced with rhBMP-2 for 3 weeks, pellets formed in the experimental group, and the size of pellets was significantly larger than that in the control group; the results of HE staining, Safranin O/fast green staining, and immunohistochemical staining for collagen type II were all positive. The results of real-time fluorescence quantitative PCR showed that the mRNA expressions of SOX9, collagen type II, and Aggrecan in the experimental group were significantly higher than those in the control group (P < 0.05).

CONCLUSION

BMP-2 can promote proteoglycan deposition and induce chondrogenic differentiation of hATDSCs in vitro. The effect of BMP-2 on hATDSCs might provide a possible explanation for histopathological changes of tendinopathy.

Nanostructural and nanomechanical responses of collagen fibrils in the collagenase-induced Achilles tendinitis rat model

Achilles tendons are vulnerable to acute or chronic injuries that lead to inflammation. We investigated nanostructural and nanomechanical changes in collagen fibrils from rat Achilles tendons over a period of 9 weeks after injury using atomic force microscopy (AFM). To evaluate the nanostructural changes in Achilles tendons, we measured the diameter and D-banding of collagen fibrils by AFM. And the adhesion forces, which were related to cross-linking of collagen, were calculated from the retraction process of a force-distance curve. We successfully observed the time course of changes in collagen fibrils during healing using AFM. The diameters and D-banding in healed tendons were similar to those of uninjured tendons at 9 weeks after injury, but the adhesion forces remained different from those of uninjured tendons. Our AFM results depicted the minute changes in Achilles tendon surface by natural healing quite well, even drawbacks to naturally healed tendon. Understanding changes in collagen cross-linking and structure while healing will lead to better understanding of healing mechanisms and subsequent improvements in treatment. And AFM can be applied as powerful tool to evaluate structural and property changes in collagen fibrils before and after injury and/or treatment in Achilles tendon.

Sports-related extensor carpi ulnaris pathology: a review of functional anatomy, sports injury and management

The extensor carpi ulnaris (ECU) muscle plays a key role not only in the active movements of wrist extension and ulnar deviation but also in providing stability to the ulnar side of the wrist. Its position relative to the other structures in the wrist changes with forearm pronation and supination. As such, it must be mobile yet stable. The ECU tendon relies on specific stabilising structures to hold it in the correct positions to perform its different functions. These structures can be injured in a variety of different athletic activities such as tennis, golf and rugby league, yet their injury and disruption is predictable when the mechanics of the ECU and the techniques of the sport are understood. The ECU tendon is also vulnerable to tendon pathologies other than instability. It lies subcutaneously and is easily palpated and visualised with diagnostic ultrasound, allowing early diagnosis and management of its specific conditions. Treatment includes rest, splintage and surgery with each modality having specific indications and recognised outcomes. This review described the functional anatomy in relevant sporting situations and explained how problems occur as well as when and how to intervene.

Tendon extracellular matrix damage detection and quantification using automated edge detection analysis

The accumulation of sub-rupture tendon fatigue damage in the extracellular matrix, particularly of type I collagen fibrils, is thought to contribute to the development of tendinopathy, a chronic and degenerative pathology of tendons. Quantitative assessment of collagen fibril alignment is paramount to understanding the importance of matrix injury to cellular function and remodeling capabilities. This study presents a novel application of edge detection analysis to calculate local collagen fibril orientation in tendon. This technique incorporates damage segmentation and stratification by severity which will allow future analysis of the direct effect of matrix damage severity on the cellular and molecular response.

Imaging horse tendons using multimodal 2-photon microscopy

Injuries and damage to tendons plague both human and equine athletes. At the site of injuries, various cells congregate to repair and re-structure the collagen. Treatments for collagen injury range from simple procedures such as icing and pharmaceutical treatments to more complex surgeries and the implantation of stem cells. Regardless of the treatment, the level of mechanical stimulation incurred by the recovering tendon is crucial. However, for a given tendon injury, it is not known precisely how much of a load should be applied for an effective recovery. Both too much and too little loading of the tendon could be detrimental during recovery. A mapping of the complex local environment imparted to any cell present at the site of a tendon injury may however, convey fundamental insights related to their decision making as a function of applied load. Therefore, fundamentally knowing how cells translate mechanical cues from their external environment into signals regulating their functions during repair is crucial to more effectively treat these types of injuries. In this paper, we studied systems of tendons with a variety of 2-photon-based imaging techniques to examine the local mechanical environment of cells in both normal and injured tendons. These tendons were chemically treated to instigate various extents of injury and in some cases, were injected with stem cells. The results related by each imaging technique distinguish with high contrast and resolution multiple morphologies of the cells' nuclei and the alignment of the collagen during injury. The incorporation of 2-photon FLIM into this study probed new features in the local environment of the nuclei that were not apparent with steady-state imaging. Overall, this paper focuses on horse tendon injury pattern and analysis with different 2-photon confocal modalities useful for wide variety of application in damaged tissues.

Masses in the extensor mechanism of the knee: an unusual presentation of gout

Tophaceous gout presenting as a soft tissue mass in an unusual location can pose a diagnostic challenge for radiologists. Tophi sometimes occur in a variety of unusual anatomic locations making them difficult to distinguish from tumors such as sarcomas. We report two cases of gout in the extensor mechanism of the knee, with imaging findings that were initially concerning for a neoplasm. One mass occurred in the patellar tendon and the other mass involved the quadriceps tendon. Both lesions had enigmatic imaging findings and to arrive at a definitive diagnosis, incisional biopsies were performed.

Histomorphologic changes of the long head of the biceps tendon in common shoulder pathologies

PURPOSE

To assess molecular and histologic differences between the proximal (intra-articular) and distal (extra-articular) portions of the long head of the biceps (LHB) tendon in 3 different disease states (biceps instability, tendinosis, and degenerative joint disease [DJD]) compared with a healthy tendon (fresh frozen).

METHODS

We used 32 LHB tendons of patients undergoing tenodesis (mean age, 54.7 ± 10.1 years) and 9 harvested tissue donors. Tendons were divided according to 4 diagnostic groups: (1) biceps instability, (2) tendinosis, (3) DJD, and (4) normal control. After sectioning, tendons were fixed in formalin and stained with H&E and alcian blue for histologic analysis. Measurements of collagen organization by use of polarized light microscopy was then performed, and protein expression for type I and type III collagen, tenascin C, and decorin was determined.

RESULTS

There were no statistical differences found for protein expression of type I or type III collagen, tenascin C, or decorin. The proximal and distal regions of the tendons had statistically significant differences in alcian blue staining, with the proximal portion containing a higher amount of proteoglycan (instability, P = .001; tendinosis, P = .005; DJD, P = .008; control, P = .011). When compared with the nonpathologic control tendons, a significant increase in alcian blue staining for the proximal region was seen in all 3 groups. Total polarized light analysis showed that the distal tendon had a significantly higher intensity (organization) compared with the proximal tendon (P < .001); this was also seen in all of the diagnostic groups (instability, P = .010; tendinosis, P = .013; DJD, P = .07; control, P = .028).

CONCLUSIONS

This study showed a greater degree of degeneration of the proximal (intra-articular) regions of the LHB tendon when compared with the distal regions in all pathologic groups. However, no major differences at the cellular level were found among groups.

CLINICAL RELEVANCE

The pathomechanisms of the various forms of known LHB diagnoses are not yet fully understood and basic science studies may help in understanding their etiology and therefore optimizing treatment options.

[Musculotendinopathy of the gastrocnemius muscle in a Labrador Retriever. A case report]

Musculotendinopathy at the origin of the gastrocnemius muscle is a rare disease mostly described in herding dogs. The etiology is based on repeated myotendinous strain of the muscle in athletic dogs. Clinically, the patient displays chronic pelvic limb lameness and pain at the lateral fabella during palpation of this area. There is no instability of the stifle present. Radiographic findings (osteophyte formation at the origin of the muscle and the lateral fabella) support the potential diagnosis. Magnetic resonance tomography shows edematous changes and enhancement after intravenous application of contrast agent in the area of the origin of the lateral gastrocnemius head. With conservative treatment (i. e. leash confinement, NSAID application and physiotherapy) the prognosis is good. This case report describes clinical findings, diagnostic imaging, therapy and long-term outcome of an athletic Labrador Retriever presented with this disease.

Light microscopic histology of quadriceps tendon ruptures

PURPOSE

To assess histological changes and possible differences in the quadriceps of patients undergoing open repair of the tendon after spontaneous rupture, and subjects with no history of tendon pathology.

MATERIALS

Biopsies were harvested from the quadriceps tendon of 46 patients (34 men, 12 women) who had reported unilateral atraumatic quadriceps tendon rupture and had undergone surgical repair of the tendon. Samples were also harvested from both the tendons in 11 (N = 11 × 2) patients, nine males and two females, dying from cardiovascular disorders. For each tendon, three slides were randomly selected and examined under light microscopy, and assessed using a semiquantitative grading scale (range 0-21) which considers fibre structure, fibre arrangement, rounding of the nuclei, regional variations in cellularity, increased vascularity, decreased collagen stainability, and hyalinisation.

RESULTS

The pathological sum-score averaged 19.2 ± 3.7 in ruptured tendons and 5.6 ± 2.0 in controls, and all variables considered were significantly different between the two groups, showing an association between tendon abnormalities and rupture (0.05 < P < 0.001).

CONCLUSION

This study confirms that the presence of histological degenerative changes in torn quadriceps tendons increases the risk of rupture.

Cytokines in rotator cuff degeneration and repair

The pathogenesis of rotator cuff degeneration remains poorly defined, and the incidence of degenerative tears is increasing in the aging population. Rates of recurrent tear and incomplete tendon-to-bone healing after repair remain significant for large and massive tears. Previous studies have documented a disorganized, fibrous junction at the tendon-to-bone interface after rotator cuff healing that does not recapitulate the organization of the native enthesis. Many biologic factors have been implicated in coordinating tendon-to-bone healing and maintenance of the enthesis after rotator cuff repair, including the expression and activation of transforming growth factor-β, basic fibroblast growth factor, platelet-derived growth factor-β, matrix metalloproteinases, and tissue inhibitors of metalloproteinases. Future techniques to treat tendinopathy and enhance tendon-to-bone healing will be driven by our understanding of the biology of this healing process after rotator cuff repair surgery. The use of cytokines to provide important signals for tissue formation and differentiation, the use of gene therapy techniques to provide sustained cytokine delivery, the use of stem cells, and the use of transcription factors to modulate endogenous gene expression represent some of these possibilities.

Emerging ideas: the effect of hypercholesterolemia on tendons

BACKGROUND

High levels of total cholesterol, triglycerides, and low-density lipoprotein are toxic to the vascular endothelium and thus have long been associated with atherosclerosis. Several clinical studies have suggested that elevated cholesterol also has a negative effect on tendon structure and function. Data from our preliminary studies show that the patellar tendons of hypercholesterolemic knockout mice exhibit reduced baseline elastic modulus and strength postinjury compared with controls.

QUESTIONS/HYPOTHESES

We therefore hypothesized elevated cholesterol would be associated with diminished tendon mechanical properties.

METHOD OF STUDY

Using hypercholesterolemic (B6.129P2-Apoetm1Unc/J) mice, patellar tendons from control (C57BL/6) and knockout mice will be injured surgically at two different times. Subsequently, mechanical testing will be performed and data evaluated for differences in baseline and in healing between cholesterol groups. For healing assessment, data from the injured limb of each animal will be normalized to that of the sham-operated contralateral limb.

SIGNIFICANCE

We anticipate that such studies eventually will enable us to elucidate the link between elevated cholesterol and tendon disease. If a mechanistic cause of hypercholesterolemia causing tendon disease is clarified, then potentially therapeutic interventions such as the use of pharmacotherapy may be used to help combat this. In the future, it may become worthwhile to consider the presentation of tendinopathy as a trigger to measure serum cholesterol just as one might consider measuring serum glucose in patients presenting with adhesive capsulitis.