Improving bone density at the rotator cuff footprint increases supraspinatus tendon failure stress in a rat model

The purpose of this study was to investigate whether supraspinatus tendon failure stress at the footprint can increase by improving the bone density at the rotator cuff footprint in a rat model. Bilateral ovariectomies were performed in twenty‐four 4‐month‐old Sprague‐Dawley rats. Half received bisphosphonate (zoledronic acid) and the other half received no treatment (OVX + ZOM and OVX, respectively). Twelve additional rats did not undergo ovariectomy or receive bisphosphonate treatment (CON). All rats were sacrificed at 7 months of age. Quantitative micro‐computed tomography was used to assess bone density in the proximal humerus. A series of stress–relaxation tests were performed to assess stiffness and failure stress of the supraspinatus tendon. Bone density in OVX + ZOM was significantly higher at the rotator cuff footprint when compared to CON and OVX rats (p < 0.0001). The supraspinatus tendons in the OVX group were significantly stiffer when compared to the CON and OVX + ZOM groups (p < 0.05). The failure stress of the OVX + ZOM group was significantly greater than the CON and OVX groups (22.89 ± 4.43 MPa vs. 18.36 ± 3.16 and 17.70 ± 4.92, respectively). In conclusion, improving the bone density at the rotator cuff footprint enhances failure stress of the suprapinatus tendon. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:308–314, 2010     

Diabetes mellitus alters the mechanical properties of the native tendon in an experimental rat model

The purpose of this study was to determine the effect of the diabetic phenotype on the mechanical properties of the native patellar tendon and its enthesis. Diabetes was induced via intraperitoneal injection of streptozotocin in Lewis rats. Control (n = 18) and diabetic animals (n = 20) were killed at 12 and 19 days for analysis. Statistical comparisons were performed using Student's t‐tests and a two‐tailed Fisher test with significance set at p < 0.05. Pre‐ and post‐injection intraperitoneal glucose tolerance tests demonstrated significant impairment of glycemic control in the diabetic compared to control animals (p = 0.001). Mean serum hemoglobin A1c levels at 19 days was 10.6 ± 2.7% and 6.0 ± 1.0% for the diabetic and control groups, respectively (p = 0.0001). Fifteen of sixteen diabetic animals demonstrated intrasubstance failure of the patellar tendon, while only 7 of 14 control specimens failed within the tendon substance. The Young's modulus of the diabetic tendon was significantly lower than control specimens by 19 days post‐induction (161 ± 10 N m^?2 compared to 200 ± 46 N m^?2, respectively) (p = 0.02). The metabolic condition of poorly controlled diabetes negatively affects the mechanical properties of the native patellar tendon. These altered structural properties may predispose diabetic patients to a greater risk of tendinopathy and/or traumatic rupture. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:880–885     

Ultrasound‐Guided Dry Needling of the Healthy Rat Supraspinatus Tendon Elicits Early Healing Without Causing Permanent Damage

Overuse‐induced tendinopathy is highly prevalent in the general population. Percutaneous fenestration, or dry needling, techniques have been increasing in popularity, but despite their current use, there are no controlled laboratory studies to provide fundamental support for this practice. The objective of this study was to establish a model for percutaneous needling of the rat supraspinatus tendon using ultrasound guidance and to evaluate the biological response of needling healthy tendon. A total of 44 male Sprague–Dawley rats (477 ± 39 g) were used to evaluate the effect of dry needling on healthy supraspinatus tendon properties. Ten rats were reserved as un‐needled control animals, and the remaining animals underwent either mild or moderate bilateral needling protocols and were sacrificed at 1 or 6 weeks post‐needling (n = 8–10/group). Color Doppler ultrasound imaging was performed to analyze blood flow within the tendon. Histological and immunohistochemical analyses were used to determine cellular, inflammatory, and extracellular matrix properties of the tissue. Finally, quasi‐static tensile mechanical analysis was performed to obtain viscoelastic, structural, and material properties to evaluate the tendon healing outcome. Data were tested for normality, and then two‐way analysis of variance tests were performed followed by post hoc tests for multiple comparisons. Both the mild and moderate needling groups caused a transient healing response at early time points as shown by a statistically significant (p < 0.05) reduction in mechanical properties, and increase in blood flow, inflammation, and production of collagen III and glycosaminoglycans as compared to the control. Furthermore, mild needling properties returned to or exceeded pre‐needling values at the 6‐week time point. Clinical significance: Needling the rat supraspinatus tendon is a feasible technique that causes a transient healing response followed by a return to, or improvement of, normal tendon properties, indicating potential applicability in understanding the effects of current practices utilizing dry needling of tendons in humans. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2035–2042, 2019     

Extended healing validation of an artificial tendon to connect the quadriceps muscle to the Tibia: 180-day study

Whenever a tendon or its bone insertion is disrupted or removed, existing surgical techniques provide a temporary connection or scaffolding to promote healing, but the interface of living to non‐living materials soon breaks down under the stress of these applications, if it must bear the load more than acutely. Patients are thus disabled whose prostheses, defect size, or mere anatomy limit the availability or outcomes of such treatments. Our group developed the OrthoCoupler? device to join skeletal muscle to prosthetic or natural structures without this interface breakdown. In this study, the goat knee extensor mechanism (quadriceps tendon, patella, and patellar tendon) was removed from the right hind limb in 16 goats. The device connected the quadriceps muscle to a stainless steel bone plate on the tibia. Mechanical testing and histology specimens were collected from each operated leg and contralateral unoperated control legs at 180 days. Maximum forces in the operated leg (vs. unoperated) were 1,400 ± 93 N (vs. 1,179 ± 61 N), linear stiffnesses were 33 ± 3 N/mm (vs. 37 ± 4 N/mm), and elongations at failure were 92.1 ± 5.3 mm (vs. 68.4 ± 3.8 mm; mean ± SEM). Higher maximum forces (p = 0.02) and elongations at failure (p = 0.008) of legs with the device versus unoperated controls were significant; linear stiffnesses were not (p = 0.3). We believe this technology will yield improved procedures for clinical challenges in orthopedic oncology, revision arthroplasty, tendon transfer, and tendon injury reconstruction. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1112–1117, 2012     

Gender‐specific in vivo measurement of the structural and mechanical properties of the human patellar tendon

Human patellar tendon stress (σ), strain (ε), stiffness (K), and tensile or Young's modulus (E), are determined in vivo through voluntary isometric contractions monitored with B‐mode ultrasonography. The limitations in previous studies are: (1) they have generally not accounted for the fact that the distal attachment of the patellar tendon (the tibial tuberosity) also displaces; thus, they have underestimated ε (and, hence, injury risk) while overestimating K; (2) no gender effect has been studied despite the fact that females are seen to have higher incidences of tendon‐related injuries. The current investigation therefore aimed to determine the gender specific values of σ, ε, K, and E of the patellar tendon while also accounting for distal displacement of the patellar tendon. Healthy young males (aged 23.1 ± 1.3 years, n = 10) and females (aged 21.3 ±0.9 years, n = 10) were tested. The maximal ε of the young males was ～5–10% higher than that reported in earlier literature. Average female versus male values for ε, σ, K, and E, taken at the same force level as the males for comparison purposes, were respectively 10.6 ± 1.0 versus 9.0 ± 1.0%, 36.9 ± 1.4 versus 28.9 ± 0.9 MPa, 1053 ± 108 versus 1652 ± 216 N · mm^?1, and 0.61 ± 0.08 versus 0.68 ± 0.10 GPa (p < 0.05). There are gender differences in tendon structural and mechanical properties. The current methodology may be useful in a clinical context where early prediction of injury risk and/or monitoring of reconstructed tendon needs to be an accurate, objective, and reliable method if optimal functionality is to be achieved. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1635–1642, 2007     

Histological and molecular analysis of the biceps tendon long head post‐tenotomy

Tendinopathy is a vexing clinical problem as its onset and development is often asymptomatic and unrecognized until tendon rupture. While extensively studied in the rotator cuff, Achilles, and patellar tendons, no study to date has examined the histological and molecular characteristics of the tendinopathic biceps long‐head (LHB). The anatomy of the LHB is unique in that it comprises intra‐ and extra‐articular portions, each exposed to differing loading patterns. Eleven LHBs post‐tenotomy were sectioned, fixed in formalin, and stained (H&E; Alcian Blue), and gross structural organization of collagen measured using polarized light microscopy. Protein expression of intra‐ and extra‐articular portions of the tenotomized biceps for IGF‐I, collagen III, and MMP‐1, ‐2, ‐3, and ‐13 was determined with Western blot analyses. The intra‐articular LHB exhibited significantly greater histological evidence of tendinopathy inclusive of increased proteoglycan (p < 0.05) and decreased organization as measured by polarized light microscopy (p < 0.01). The intra‐articular LHB also had significantly increased expression of collagen type III (p < 0.01) and of MMP‐1 and 3 (p < 0.01, p < 0.05 respectively). No significant differences were found for IGF‐I or for MMP‐2 and ‐13. The intra‐articular LHB exhibited histological characteristics of tendinopathy. Protein expression of the intra‐articular LHB did not universally display signs of tendinopathy in comparison to the extra‐articular portion of the tendon. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1379–1385, 2009     

Differential Effector Response of Amnion‐ and Adipose‐Derived Mesenchymal Stem Cells to Inflammation; Implications for Intradiscal Therapy

Intervertebral disc degeneration (IVDD) is a progressive condition marked by tissue destruction and inflammation. The therapeutic effector functions of mesenchymal stem cells (MSCs) makes them an attractive therapy for patients with IVDD. While several sources of MSCs exist, the optimal choice for use in the inflamed IVD remains a significant question. Adipose (AD)‐ and amnion (AM)‐derived MSCs have several advantages compared with other sources, however, no study has directly compared the impact of IVDD inflammation on their effector functions. Human MSCs were cultured in media with or without supplementation of interleukin‐1β (IL‐1β) and tumor necrosis factor‐α at concentrations reportedly produced by IVDD cells. MSC proliferation and production of pro‐ and anti‐inflammatory cytokines were quantified following 24 and 48 h of culture. Additionally, the osteogenic and chondrogenic potential of AD‐ and AM‐MSCs was characterized via histology and biochemical analysis following 28 days of culture. In inflammatory culture, AM‐MSCs produced significantly more anti‐inflammatory IL‐10 (14.47 ± 2.39 pg/ml; p = 0.004) and larger chondrogenic pellets (5.67 ± 0.26 mm²; p = 0.04) with greater percent area staining positively for glycosaminoglycan (82.03 ± 3.26%; p < 0.001) compared with AD‐MSCs (0.00 ± 0.00 pg/ml; 2.76 ± 0.18 mm²; 34.75 ± 2.49%; respectively). Conversely, AD‐MSCs proliferated more resulting in higher cell numbers (221,000 ± 8,021 cells; p = 0.048) and produced higher concentrations of pro‐inflammatory cytokines prostaglandin E₂ (1,118.30 ± 115.56 pg/ml; p = 0.030) and IL‐1β (185.40 ± 7.63 pg/ml; p = 0.010) compared with AM‐MSCs (109,667 ± 5,696 cells; 1,291.40 ± 78.47 pg/ml; 144.10 ± 4.57 pg/ml; respectively). AD‐MSCs produced more mineralized extracellular matrix (3.34 ± 0.05 relative absorbance units [RAU]; p < 0.001) compared with AM‐MSCs (1.08 ± 0.06 RAU). Under identical inflammatory conditions, a different effector response was observed with AM‐MSCs producing more anti‐inflammatories and demonstrating enhanced chondrogenesis compared with AD‐MSCs, which produced more pro‐inflammatory cytokines and demonstrated enhanced osteogenesis. These findings may begin to help inform researchers which MSC source may be optimal for IVD regeneration. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2445–2456, 2019     

Conventional Versus Invaginated Stripping of the Great Saphenous Vein: A Randomized,Double-Blind,Controlled Clinical Trial

Background An invaginated strip of the great saphenous vein (GSV) may be associated with diminished blood loss and less discomfort compared to conventional stripping in patients with unilateral primary GSV varicosis. Methods Ninety-two patients were randomized for conventional (CON) or invaginated (INVAG) stripping and were followed for 26 weeks postoperatively. Results Both groups (n = 46) were well balanced for age, gender distribution, and body mass index. The CON group lost twice as much blood compared to the INVAG group (CON: 28 ± 4 g, INVAG: 15 ± 2 g, p < 0.001). Infragenual incision length following a conventional strip was twice as long (CON: 16 ± 1 mm, INVAG: 8 ± 1 mm, p < 0.001). Pain as measured with a visual analog scale (minimal 0, max 10) decreased in both groups in a similar fashion from 3.2 ± 0.3 preoperatively to 0.6 ± 0.2 after 26 weeks (p < 0.001). Saphenous nerve damage after one month was observed in four CON patients compared to no patients following invagination. Return to work was not different (CON: 13 ± 2 days, INVAG: 11 ± 2 days). Conclusion Invagination of the GSV in uncomplicated primary varicosis may be associated with less surgical trauma compared to a conventional stripping technique.     

SDF‐1/CXCR4/CXCR7 is pivotal for vascular smooth muscle cell proliferation and chronic allograft vasculopathy

Chronic rejection remains a major obstacle in transplant medicine. Recent studies suggest a crucial role of the chemokine SDF‐1 on neointima formation after injury. Here, we investigate the potential therapeutic effect of inhibiting the SDF‐1/CXCR4/CXCR7 axis with an anti‐SDF‐1 Spiegelmer (NOX‐A12) on the development of chronic allograft vasculopathy. Heterotopic heart transplants from H‐2bm12 to B6 mice and aortic transplants from Balb/c to B6 were performed. Mice were treated with NOX‐A12. Control animals received a nonfunctional Spiegelmer (revNOX‐A12). Samples were retrieved at different time points and analysed by histology, RT‐PCR and proliferation assay. Blockade of SDF‐1 caused a significant decrease in neointima formation as measured by intima/media ratio (1.0 ± 0.1 vs. 1.8 ± 0.1, P < 0.001 AoTx; 0.35 ± 0.05 vs. 1.13 ± 0.27, P < 0.05 HTx). In vitro treatment of primary vascular smooth muscle cells with NOX‐A12 showed a significant reduction in proliferation (0.42 ± 0.04 vs. 0.24 ± 0.03, P < 0.05). TGF‐β, TNF‐α and IL‐6 levels were significantly reduced under SDF‐1 inhibition (3.42 ± 0.37 vs. 1.67 ± 0.33, P < 0.05; 2.18 ± 0.37 vs. 1.0 ± 0.39, P < 0.05; 2.18 ± 0.26 vs. 1.6 ± 0.1, P < 0.05). SDF‐1/CXCR4/CXCR7 plays a critical role in the development of chronic allograft vasculopathy (CAV). Therefore, pharmacological inhibition of SDF‐1 with NOX‐A12 may represent a therapeutic option to ameliorate chronic rejection changes.     

Systemic and renal effects of dopamine in the infant pig

Dopamine is commonly employed in the management of hypotensive patients. Although this medication increases cardiac index (CI) and renal artery (RA) flow in adults, its effect in infants has not been adequately studied. In 13 infant pigs (mean wt 3.05 ± 0.75 kg; age 3–4 weeks) CI, RA flow and systemic blood pressure (BP) were measured at varying renal artery perfusion pressures before and after the administration of dopamine. Pigs were anesthetized with ketamine, intubated, and maintained on a ventilator with succinylcholine. Jugular vein, pulmonary (Swan-Ganz), carotid, and femoral artery catheters were placed. Laparotomy was performed and RA flow was measured with an electromagnetic flow probe. A Blalock clamp was placed around the suprarenal aorta to obtain graded aortic occlusions to pressures of 80 and 50 mm Hg. Dopamine had no significant effect on the CI vs control at 5, 10, 15, 20, 25, or 50 μg/kg/min. BP increased 25 mm Hg on Dopamine (10 μg/kg/min) P > 0.05). RA flow remained stable (318 ± 74 vs 300 ± 68 ml/min) despite reduction in perfusion pressure to 80 mm Hg, suggesting an autoregulatory flow mechanism. At 50 mm Hg perfusion pressure however, RA flow decreased significantly to 220 ± 54 ml/min (P < 0.05) indicating a loss of autoregulation at lower perfusion pressures.Dopamine (10 μg/kg/min) did not change RA flow at control BP (335 ± 76 vs 318 ± 74 ml/min). At 80 mm Hg perfusion pressure however, RA flow fell from 335 ± 74 to 175 ± 50 ml/min (P < 0.001) demonstrating a suppression of renal autoregulation by dopamine. At 50 mm Hg, RA flow was markedly reduced to 22 ± 31 ml/min (P < 0.001). These data suggest: (1) dopamine has no significant effect on CI in infant pigs, (2) an RA flow mechanism is present in infant pigs which protects the kidney at reduced perfusion pressures, and (3) dopamine interferes with autoregulation and may be harmful to the infant kidney in hypotensive states.     

Sclerostin antibody inhibits skeletal deterioration due to reduced mechanical loading

Sclerostin, a product of the SOST gene produced mainly by osteocytes, is a potent negative regulator of bone formation that appears to be responsive to mechanical loading, with SOST expression increasing following mechanical unloading. We tested the ability of a murine sclerostin antibody (SclAbII) to prevent bone loss in adult mice subjected to hindlimb unloading (HLU) via tail suspension for 21 days. Mice (n = 11–17/group) were assigned to control (CON, normal weight bearing) or HLU and injected with either SclAbII (subcutaneously, 25 mg/kg) or vehicle (VEH) twice weekly. SclAbII completely inhibited the bone deterioration due to disuse, and induced bone formation such that bone properties in HLU‐SclAbII were at or above values of CON‐VEH mice. For example, hindlimb bone mineral density (BMD) decreased –9.2% ± 1.0% in HLU‐VEH, whereas it increased 4.2% ± 0.7%, 13.1% ± 1.0%, and 30.6% ± 3.0% in CON‐VEH, HLU‐SclAbII, and CON‐SclAbII, respectively (p < 0.0001). Trabecular bone volume, assessed by micro–computed tomography (µCT) imaging of the distal femur, was lower in HLU‐VEH versus CON‐VEH (p < 0.05), and was 2‐ to 3‐fold higher in SclAbII groups versus VEH (p < 0.001). Midshaft femoral strength, assessed by three‐point bending, and distal femoral strength, assessed by micro–finite element analysis (µFEA), were significantly higher in SclAbII versus VEH‐groups in both loading conditions. Serum sclerostin was higher in HLU‐VEH (134 ± 5 pg/mL) compared to CON‐VEH (116 ± 6 pg/mL, p < 0.05). Serum osteocalcin was decreased by hindlimb suspension and increased by SclAbII treatment. Interestingly, the anabolic effects of sclerostin inhibition on some bone outcomes appeared to be enhanced by normal mechanical loading. Altogether, these results confirm the ability of SclAbII to abrogate disuse‐induced bone loss and demonstrate that sclerostin antibody treatment increases bone mass by increasing bone formation in both normally loaded and underloaded environments. © 2013 American Society for Bone and Mineral Research.     

The effects of multiple freeze–thaw cycles on the biomechanical properties of the human bone‐patellar tendon‐bone allograft

Soft tissue allografts, such as the bone‐patellar tendon‐bone (BPTB) graft, have been frequently used for anterior cruciate ligament (ACL) reconstruction. As allografts are subjected to freezing and thawing for multiple cycles, the objective of this study was to measure the changes of the biomechanical properties of the human BPTB allograft after 4 and 8 freeze–thaw cycles in comparison to a single freeze–thaw cycle. Three BPTB specimens were procured from 21 human donors and divided into three groups: 1, 4, or 8 freeze–thaw cycles. Each freeze–thaw cycle consisted of freezing at ?20 ± 10°C for more than 6 h and thawing at 22 ± 3°C for at least 6 h. Tensile testing of the BPTB specimens consisted of loading between 50 N and 250 N for 100 cycles and then loading to failure. Cyclic loading revealed a similar amount of creep (～0.5 mm) among the three freeze–thaw cycles groups (p = 0.38). The stiffness of the BPTB graft for the 1, 4, and 8 freeze–thaw cycle groups were 244 ± 42 N/mm, 235 ± 39 N/mm, and 231 ± 40 N/mm, respectively (p = 0.43). Similar findings were obtained for the ultimate load of the BPTB graft (p = 0.14) and the tangent modulus of the PT substance (p = 0.41). The results of this study suggest that there would be little measurable effect on the structural properties of the BPTB graft or mechanical properties of the PT tissue substance following 8 freeze–thaw cycles. These BPTB allografts could potentially be re‐frozen without a loss in their biomechanical properties, given appropriate storage and care. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29: 1193–1198, 2011     

Atrial remodelling is less pronounced in female endurance-trained athletes compared with that in male athletes

Objectives. Little data exists on atrial adaptation to training in women. Furthermore, data on right atrial (RA) volumes is lacking for both male and female athletes. The objective of this study was therefore to investigate atrial volumes in male and female athletes. Design. A total of 75 athletes (33 women) and 53 controls (21 women) underwent cardiovascular magnetic resonance imaging. Left atrial (LA) and RA volumes were measured by manual delineation. The atrial appendage was included in the volumes, and pulmonary veins were excluded. Results. Atrial volumes were larger in athletes compared with those in controls (males: LA 116 ± 19 ml versus 93 ± 19 ml, RA 166 ± 32 ml versus 133 ± 23 ml, p < 0.0001, females: LA 90 ± 15 ml versus 83 ± 17 ml, p < 0.05, RA 119 ± 24 ml versus 108 ± 18 ml, p = 0.07). When normalized for body surface area, atrial volumes remained larger in athletes. However, when normalized for total heart volume (THV) there were no differences between groups except for LA volumes in females where controls had higher LA/THV compared with those in athletes (p < 0.05). Conclusion. Atrial volumes were significantly larger in athletes. Atrial volumes normalized for THV did not differ between athletes and controls indicating a balanced enlargement. There was only a small difference between female controls and female athletes, suggesting that atrial adjustment to training is more modest in women.     

Effects of corticosteroids and hyaluronic acid on torn rotator cuff tendons in vitro and in rats

Corticosteroids (CS) or hyaluronic acid (HA) is used in subacromial injection for the conservative treatment of rotator cuff tears (RCT); this study addresses the question of how CS and HA affect the tendon tissue and fibroblasts in vitro and in rats. Cell proliferation assays were performed in human tendon fibroblasts from RCT. Rats underwent surgery to create RCT, and the surgical sites were injected with CS or HA. The rotator cuff tendons were subjected to biomechanical testing, microscopic and immunohistochemical analysis of proliferating cell nuclear antigen (PCNA), and ultrastructural analysis. Cell proliferation was significantly decreased with CS in vitro (p < 0.05). Maximal load of CS‐treated tendons was significantly decreased compared with that of HA‐treated tendons (p < 0.05), as well as PCNA⁺ cells at 2 weeks (p < 0.05). Ultrastructural observations of the CS‐treated rats detected apoptosis of tendon fibroblasts 24 h after surgery. Histological and biomechanical data 4 weeks after surgery were not significant among the three groups. Unlike HA, CS caused cell death, and inhibition of the proliferation of tendon fibroblasts, leading to a delay of tendon healing involved and a subsequent decrease of biomechanical strength at the surgical site. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1523–1530, 2015.     

Ultrasonographic assessment of quadriceps and patellar tendon thicknesses in patients with patellofemoral pain syndrome

ObjectiveThe aim of this study was to compare ultrasonographically measured quadriceps and patellar tendon thicknesses between Patellofemoral Pain Syndrome (PFPS) patients and age- and gender-matched healthy controls.MethodsAmong patients who presented to physical therapy and rehabilitation outpatient clinic in January–December 2016, 61 volunteers (28 men and 33 women; mean age: 30.79 ± 6.55 years) who were eligible considering the inclusion and exclusion criteria were enrolled. 30 were diagnosed with PFPS, and the remaining were age- and gender-matched healthy volunteers. Mean age was 30.03 ± 5.67 years in healthy subjects and 45.2% were of male gender. The patient group had mean age of 31.57 ± 7.37 years and 46.7% of the patients were male. Q angles were measured at standing, supine and sitting positions. Patellar and femoral tendon thicknesses and areas were measured ultrasonographically. Kujala questionnaire were used to evaluate the functional status of the participants.ResultsNo significant difference was detected between groups regarding profession, educational background, and body mass indices (BMI) (p > 0.05). Q angle values were significantly higher in the patient group when compared to controls at standing (17.03 ± 3.84 vs. 13.87 ± 1.75°, p < 0.001), supine (16.20 ± 3.74 vs. 13.45 ± 1.79°, p = 0.001) and sitting (16.50 ± 3.28 vs. 13.71 ± 1.72°, p < 0.001) positions. Kujala score was significantly lower in the PFPS group when compared to controls (70.57 ± 8.37 vs. 98.58 ± 2.05, p < 0.001). Patellar (0.39 ± 0.08 vs. 0.32 ± 0.05 cm, p < 0.001) and quadriceps (0.64 ± 0.10 vs. 0.52 ± 0.09 cm, p < 0.001) tendon thicknesses were significantly higher in the PFPS group when compared to controls. There was no significant difference between groups regarding patellar tendon areas (p > 0.05). Patellar tendon thickness values of ≥0.35 cm were found to have 66.7% sensitivity and 67.7% specificity for PFPS diagnosis in the ROC curve analysis (area under curve: 0.771, 95% confidence interval: 0.655–0.887, p < 0.001). Quadriceps tendon thickness values of ≥0.54 cm were found to have 80% sensitivity and 71% specificity for PFPS diagnosis in the ROC curve analysis (area under curve: 0.824, 95% confidence interval: 0.710–0.939, p < 0.001). In PFPS patients, quadriceps tendon thickness had significant positive correlation with age (r = 0.405, p = 0.027) and BMI (r = 0.450, p = 0.013); and significant negative correlation with Kujala score (r = ?0.441, p = 0.015). In the multivariate regression analysis, quadriceps tendon thickness was independently associated with the presence of PFPS (Exp (B): 3.089, 95% confidence interval: 1.344–7.100, p = 0.008).ConclusionOur study demonstrates that ultrasonographically measured patellar and quadriceps tendon thicknesses are significantly higher in subjects with PFPS and particularly, quadriceps tendon thickness may be used for the diagnosis.Level of EvidenceLevel III, Therapeutic Study.     

Effects of lubricant and autologous bone marrow stromal cell augmentation on immobilized flexor tendon repairs

The purpose of the study was to test a novel treatment that carbodiimide‐derivatized‐hyaluronic acid‐lubricin (cd‐HA‐lubricin) combined cell‐based therapy in an immobilized flexor tendon repair in a canine model. Seventy‐eight flexor tendons from 39 dogs were transected. One tendon was treated with cd‐HA‐lubricin plus an interpositional graft of 8 × 10⁵ BMSCs and GDF‐5. The other tendon was repaired without treatment. After 21 day of immobilization, 19 dogs were sacrificed; the remaining 20 dogs underwent a 21‐day rehabilitation protocol before euthanasia. The work of flexion, tendon gliding resistance, and adhesion score in treated tendons were significantly less than the untreated tendons (p < 0.05). The failure strength of the untreated tendons was higher than the treated tendons at 21 and 42 days (p < 0.05). However, there is no significant difference in stiffness between two groups at day 42. Histologic analysis of treated tendons showed a smooth surface and viable transplanted cells 42 days after the repair, whereas untreated tendons showed severe adhesion formation around the repair site. The combination of lubricant and cell treatment resulted in significantly improved digit function, reduced adhesion formation. This novel treatment can address the unmet needs of patients who are unable to commence an early mobilization protocol after flexor tendon repair. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:154–160, 2016.     

Surface modification counteracts adverse effects associated with immobilization after flexor tendon repair

Although post‐rehabilitation is routinely performed following flexor tendon repair, in some clinical scenarios post‐rehabilitation must be delayed. We investigated modification of the tendon surface using carbodiimide derivatized hyaluronic acid and lubricin (cd‐HA‐Lub) to maintain gliding function following flexor tendon repair with postoperative immobilization in a in vivo canine model. Flexor digitorum profundus tendons from the 2nd and 5th digits of one forepaw of six dogs were transected and repaired. One tendon in each paw was treated with cd‐HA‐Lub; the other repaired tendon was not treated. Following tendon repair, a forearm cast was applied to fully immobilize the operated forelimb for 10 days, after which the animals were euthanized. Digit normalized work of flexion (nWOF) and tendon gliding resistance were assessed. The nWOF of the FDP tendons treated with cd‐HA‐Lub was significantly lower than the nWOF of the untreated tendons (p < 0.01). The gliding resistance of cd‐HA‐Lub treated tendons was also significantly lower than that of the untreated tendons (p < 0.05). Surface treatment with cd‐HA‐Lub following flexor tendon repair provides an opportunity to improve outcomes for patients in whom the post‐operative therapy must be delayed after flexor tendon repair. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1940–1944, 2012     

Insertional achilles tendinopathy associated with altered transverse compressive and axial tensile strain during ankle dorsiflexion

The purposes of this case‐control study (N = 20) were to examine the effects of insertional Achilles tendinopathy (IAT) and tendon region on tendon strain in patients with IAT compared to a control group without tendinopathy. An ultrasound transducer was positioned over the Achilles tendon insertion during dorsiflexion tasks, which included standing and partial squat. A non‐rigid image registration‐based algorithm was used to estimate transverse compressive and axial tensile strains of the tendon from radiofrequency ultrasound images, which was segmented into two regions (superficial tendon and deep). For transverse compressive strain, two‐way mixed effects ANOVAs demonstrated that there were interaction effects between group and tendon region for both dorsiflexion tasks (Heel lowering, p = 0.004; Partial squat, p = 0.008). For axial tensile strain, the IAT group demonstrated a main effect of lower tensile strain than the control group (Standing, p = 0.001; Partial squat, p = 0.033). There was also a main effect of greater tensile strain in the superficial region of the tendon compared to the deep during standing (p = 0.002), but not during partial squat (p = 0.603). Reduced transverse compressive and axial tensile strains in the IAT group indicate altered mechanical properties specific to the region of IAT pathology. Additionally, patterns of compressive strain are consistent with the theory of calcaneal impingement contributing to IAT pathology. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:910–915, 2017.