Introduction

Cell-based tendon engineering is an attractive alternative therapeutic approach to established treatments of tendon injuries. Numerous cell types are promising source of tendon engineering; however, there are certain disadvantages for each cell type. Interestingly, dermal fibroblasts (DFs) are able to transdifferentiate into other cell types, they are widely distributed in dermis and easy to harvest and isolate. Furthermore, pilot clinical studies suggested a promising therapeutic potential of autologous DFs for discorded tendons (Connell et al., 2009&2011), but the underlining repair mechanisms remain unclarified. To investigate tenogenic differentiation process in great detail, we have previously established a three-dimensional (3D) cell sheet model, comprising of three consecutive step (expansion, stimulation and maturation) leading to the formation of 3D tendon-like tube (Hsieh et al., 2018; Yan et al., 2020). Hence, the aim of this study was to carry out pilot examination of the tenogenic potential of human DFs (hDFs) by implementing the 3D cell sheet model.

Metal-on-metal hip resurfacing arthroplasty (MoMHRA) has been a popular alternative treatment for young patients with hip osteoarthritis. Despite its advantages over total hip arthroplasty, the use of MoMHRA remains controversial. Achieving the correct positioning of the prosthetic is a concern due to the difficulty and novelty of this procedure. Furthermore, it has been reported that post-operative management using 2D radiographs contains high degrees of variance leading to poor detection of prosthetic malpositioning. In order to compensate for the lack of available technology, current literature has suggested the use of blood metal ion levels as indirect predictors of prosthetic malpositioning due to the abnormal release of metal ions, particularly Chromium and Cobalt, as a result of increase wear and tear. The purpose of this study was to determine whether 2D/3D registration technology can report prosthetic orientation in vivo and, to establish whether 3D technology can accurately deduce prosthetic wear by correlating prosthetic angles with metal ion counts.

To begin this study, post-operative x-rays (n=72) were used as the two-dimensional media to measure acetabular orientation. Only the acetabular component was examined in this study and acetabular orientation was defined as the function of inclination and version angles. Virtual three-dimensional models of the native, pre-operative pelvises and the acetabular implant were generated and were manually superimposed over the post-operative x-ray images according to anatomical landmarks. A manual 2D/3D registration program was specifically designed for this task. Inclination and version angles of the 2D/3D registered product were measured. Post-operative CT models, which offer the most accurate depiction of the prosthetic in vivo, were generated for validation. Contrary to the study's hypotheses and current literature, no significant difference was observed between 2D vs. 2D/3D vs. CT data, suggesting that 2D and 2D/3D measurements were similar to the results of the gold standard CT model (although 2D/3D measurements were more precise compared to 2D media). Furthermore, statistical analyses revealed no significant correlation in either 2D or 2D/3D compared to metal ion levels, although a stronger trend was demonstrated using 2D/3D measurements. These results are suggestive that 2D/3D registered measurements are equivocal to those using the conventional 2D x-ray and, manual 2D/3D registered measurements do not demonstrate greater efficacy in predicting prosthetic wear. Moreover, the data from this study also revealed insignificant correlations between the angles of acetabular orientation and metal ion release. Combined angles within and beyond the acceptable ranges for inclination (30°–50°) and version (5°–20°) angles did not produce significant trends with metal ion release. These results lead to the paradoxical conclusion that acetabular orientation does not influence prosthetic wear. The findings of this study are inconsistent with the reports in current literature and further investigation is required.

Introduction: ‘Stress profilometry’ involves pulling a pressure transducer through a loaded intervertebral discs in order to characterise the intensity of loading within it. The technique has been used to explore how stress distributions vary with age, spinal level, degeneration, creep loading, and injury. However, can the output of the strain-gauged transducer (which is calibrated in a fluid) really quantify stress perpendicular to its membrane when inserted into the fibrous matrix of degenerated discs?

Methods: Thirteen full-depth cylinders, 7mm in diameter, were cut from inner, middle and outer regions of the anterior and lateral annulus of two human upper-lumbar discs aged 74 and 82 yrs. Specimens were confined within a metal cylinder of internal diameter 7 mm. Two vertical slots on opposite sides of the metal cylinder allowed a pressure transducer, side-mounted near the tip of a 0.9 mm-diameter needle, to be pulled through the annulus sample. Constant compressive loading was applied for 20s to the top of the annulus sample, using a plane-ended 6.9 mm-diameter indenter, while the transducer was pulled through the sample. Transducer output was sampled at 25Hz. ‘Stress profiles’ were repeated with the transducer orientated vertically and horizontally, and with 6-21 values of compressive load, corresponding to stresses up to 3MPa. Average values of measured ‘stress’ were compared to applied stress (compressive force/indenter area).

Results: Measured (average) vertical compressive stress was linearly related to applied stress, with Rsq values averaging 0.97. The gradient of the line averaged 0.98 (range 0.77 – 1.28) indicating that measured stress values approximated to applied stress, and were not merely proportional to it. For horizontal measurements, the Rsq and gradient averaged 0.97 and 0.92 respectively. Abnormal results in 3/13 specimens appeared to be affected by transducer damage and were disregarded.

Conclusion: Stress profilometry can quantify compressive stress within the annulus of degenerated intervertebral discs. This fibrous tissue appears to be sufficiently deformable to allow efficient coupling of stress between the matrix and transducer membrane.

Modern gait analysis offers a unique means to measure the biomechanical response to diseases of the musculoskeletal system during activities of daily living. The objective of this on-going study is to quantify the biomechanical environment of the knee joint in subjects with moderate knee osteoarthritis (OA). We collected 3-D motion, ground reaction force, and electromyographic data from seven normal subjects and five subjects with moderate knee OA. There were no differences in stride characteristics or joint motion patterns between the two groups. In contrast, we found differences in knee joint kinetics between the moderate OA subjects and the normal control subjects.

The objective of this on-going study is to quantify the biomechanical environment of the knee joint in subjects with moderate knee osteoarthritis (OA). Our goal is to identify biomechanical characteristics related to treatment interventions.

The moderate knee OA patients walked with a visibly normal gait as measured by stride characteristics and joint angles. Differences were detected in the joint loading (ie adduction and flexion moments).

The biomechanical differences between normal and osteoarthritic knees will provide the basis upon which to design and evaluate non-invasive treatments for knee OA.

Subjects performed, in random order, five trials of their normal selected speed, and a fast walk (150% of the normal speed). Three-dimensional motion and force data were used to calculate three dimensional joint angles, moments and forces.

There were no differences in stride characteristics (walking speeds, stride lengths, or stride times) between the two groups. The moderate OA patients walked with normal knee joint motion patterns. In contrast, we found differences in knee joint kinetics between the moderate OA subjects and the normal control subjects. The magnitude of the adduction moment during stance was larger for the moderate OA patients at both walking speeds (p< 0.05). We also identified differences in the pattern of the flexion moment, but only at the higher walking speed (p< 0.05).

Gait analysis can provide insight into the mechanical factors of knee osteoarthritis by quantifying the dynamic loading and alignment of the knee during activities of daily living

The objective of this study was to determine if abnormal neuromuscular patterns exist in individuals with knee Osteoarthritis compared to those with healthy knees. We collected surface electromyographic signals during preferred speed and fast walk conditions from seven muscles crossing the knee joint. We found differences between the two groups that could lead to differences in joint loading, with the OA group having higher coactivity between hamstrings and quadriceps during initial loading. Further investigating these differences is warranted in particular given the trend for lower external extensor moments for the OA group at the fast walking speed.

The purpose of this study was to compare neuromuscular control of knee joint motion during walking between those with moderate Osteoarthritis (OA) and those with healthy knees (CON).

Moderate OA neuromuscular control patterns differed from those with healthy knees.

Detecting neuromuscular alteration associated with mild to moderate knee OA is important to direct therapeutic strategies aimed to slow down or possibly reverse disease progression.

Surface electromyographic (EMG) recordings were collected from seven muscles crossing the knee joint of CON (n=7) and those with moderate OA (n=4) during preferred speed and a fast-paced walks. A pattern recognition technique was applied to the EMG profiles. No differences (> 0.05) were reported between the two groups for spatial and temporal gait parameters or knee joint kinematics. Statistical differences were found (p< 0.05) in muscle activation patterns between the two groups and the differences were more prominent at the faster walking speed. The two vasti muscles had double peaks during stance and higher amplitudes at heel strike for the OA group. There was higher activity in the two hamstring muscles at heel contact and a burst of activity during late stance for the OA group.

The disproportionately higher knee flexor coactivity at heel strike may reflect a guarded response to pain, whereas the burst during weight transfer may reflect a stabilizing response as the knee moment changes from a flexor to an extensor moment. At normal walking speeds the neuromuscular control patterns were similar between groups, but differences were exaggerated when the system was stressed at higher speed.