Introduction

The popliteus tendon is a component of the posterolateral corner of the knee, which controls the external rotation of the tibia. In our clinical practice, the femoral footprint of the popliteus tendon is occasionally excised as the bone is resected during total knee arthroplasty (TKA). Although the excision of the popliteus tendon femoral footprint could result in excessive external rotation of the tibia and may have adverse effects on the long-term outcomes of TKA, little attention has been paid to the popliteus tendon femoral footprint during TKA. The purpose of the present study is to assess the frequency of the excision and its associated risk factors.

Summary Statement

Paraspinal muscle contain higher proportion of slow-twich fibers. The fixation of the rat tail induced transition of muscle fiber types in the paravertebral muscles characterised by the decrease in the proportion of the slow type myosin heavy chain.

Summary Statement

The Dkk3-derived cells represent a branch of the periosteal mesenchymal lineage that produces fibrocartilage as well as regenerating the periosteal structures.

Introduction

Many literatures regarding more specific tests to diagnose the supraspinatus tendon injuries and the best rehabilitation methods to strengthen the supraspinatus have been published. However, conflicting results have been reported. 2-deoxy-2-[18F] fluoro-D-glucose (FDG) positron emission tomography (PET) has been recently used to assess skeletal muscle activities in various fields.

Introduction: Acoustic microscopy for medicine and biology has been developed for more than twenty years at Tohoku University [1–8]. Application of acoustic microscopy in medicine and biology has three major features and objectives. First, it is useful for intra-operative pathological examination because staining is not required. Second, it provides basic acoustic properties to assess the origin of lower frequency ultrasonic images. Third, it provides information on biomechanical properties at a microscopic level because ultrasound has close correlation with mechanical properties of the tissues. This paper describes the preliminary results obtained using 300 MHz ultrasound intensity microscopy for in vitro characterization of rat synovial cell cultures. The novelty of the approach lies in the fact that it allows remote, non-contact and disturbance-free imaging of cultured synovial cells and the changes in the cells’ properties due to external stimulants such as transforming growth factor beta-1 (TGFbeta1).

Materials and Methods: Ultrasound intensity microscope: An electric impulse was generated by a high speed switching semiconductor. The electric pulse was input to a transducer with sapphire rod as an acoustic lens and with the central frequency of 300 MHz. The reflections from the tissue was received by the transducer and were introduced into a Windows-based PC (Pentium D, 3.0 GHz, 2GB RAM, 250GB HDD) via a digital oscilloscope (Tektronix TDS7154B, Beaverton, USA). The frequency range was 1GHz, and the sampling rate was 20 GS/s. Four values of the time taken for a pulse response at the same point were averaged in order to reduce random noise. The transducer was mounted on an X-Y stage with a microcomputer board that was driven by the PC through RS232C. The Both X-scan and Y-scan were driven by linear servo motors. The ultrasound propagates through the thin specimen such as cultured cells and reflects at the interface between the specimen and substrate. A two-dimensional distribution of the ultrasound intensity, which is closely related to the mechanical properties, was visualized with 200 by 200 pixels.

Tissue preparation: The synovial membrane was obtained from non-operated male rats weighing from 380 to 400 g through medial parapatellar incision. The tissue was diluted and loosened 0.15% DispaseII (Boehringer, Mannheim) in DMEM for 2 hours at 37 C°. Then centrifuged at 400 g for 5 min and discard the supernatant. The cells were plated in 75 mm2 dish (Falcon) with Dulbecco’s modified Eagle’s medium (DMEM, GIBCO Laboratories) containing 10% fetal bovine serum (SIGMA Chemical Co.) at 37 C° in a CO2 incubator. To determine changes of intensity, the cells were treated with 1 ng/ml of human recombinant TGF-β1 (hTGF-β1, R& D Systems, Inc.) for 1 and 3 days after reaching confluent. The non-treated cells was harvested at 3 days after reaching confluent and defined as control. Randomized four points at each dish were measured and averaged data was defined as the representative value of each dish. The cells used for experiments were at the third passage.

Signal processing: The reflection from the tissue area contains two components. One is from the tissue surface and another from the interface between the tissue and the substrate (phosphate buffered saline). Frequency domain analysis of the reflection enables the separation of these two components and the calculation of the tissue thickness and intensity by Fourier-transforming the waveform [9].

Image analysis: Randomized point regions were determined using ultrasound intensity microscopic images. This was done by employing commercially available image analysis software (PhotoShop CS2, Adobe Systems Inc.). Ultrasound intensity microscopic images with a gradation color scale were also produced for clear visualization of the ultrasound intensity variations.

Statistics: Statistical analysis among groups was performed using one factor analysis of variance. Data were expressed as mean ± standard deviation. A value of P < 0.05 was accepted as statistically significant.

Results: The ultrasound intensity microscope can clearly visualize cells. The high intensity variations area of the reflected ultrasound energy at the central part of the cell corresponded to the nucleus and the high intensity area at the peripheral zone corresponded to the cytoskeleton mainly consisting of actin filaments. The intensity of the reflected ultrasound energy at the peripheral zone was significantly increased after stimulation with hTGF-b1.

Epigenetic DNA de-methylation at specific CpG promoter sites is associated with abnormal synthesis of matrix-degrading enzymes in human osteoarthritis (Arthritis Rheum 52:3110–24), but the mechanisms that trigger or cause loss of DNA methylation are not known. Since inflammatory cytokines are known to induce abnormal gene expression in cultured chondrocytes, we wanted to know whether this induction also involved loss of DNA methylation. If so, the abnormal gene expression would be permanent and transmitted to daughter cells rather than a simple up-regulation. To test this hypothesis, we selected IL-1b as the abnormally expressed gene. Healthy chondrocytes, harvested from human femoral head cartilage following a fracture, were divided into five groups: non-culture; control culture; culture with the de-methylating agent 5-aza-deoxycyti-dine (5-aza-dC); culture with the inflammatory cytokine IL-1b; or with TNF-a/oncostatin M. Total RNA and genomic DNA were extracted at confluency, relative mRNA expression of IL-1b was quantified by Syb-rGreen-based real-time PCR, and a method for quantifying the percent of cells with DNA methylation at a specific CpG site was developed (Epigenetics 2: 86–95).

The methylation status of 16 CpG sites in the promoter of IL-1b was determined by the bisulfite modification method. The two CpG sites important for the epigenetic regulation of IL-1b were at -247bp and -290bp, the latter was selected to quantify DNA methylation. 5-aza-dC halved DNA methylation, which resulted in 4–8 fold increases in IL-1b expression; showing that DNA de-methylation per se increases gene expression. However, far greater effects were seen with the inflammatory cytokines. IL-1b increased its own expression 50–100 fold, whereas TNF-a/OSM increased IL-1b expression 500–1000 fold. DNA methylation varied inversely, IL-1b reducing methylation to ~15% and TNF-a/OSM abolishing DNA methylation almost completely.

This is the first demonstration that inflammatory cytokines have the capacity to cause loss of DNA methylation. We also confirmed previous work that IL-1b induces its own expression in healthy chondrocytes, thus setting up a dangerous positive feed-back mechanism. If true in vivo, both the auto-induction and the heritable expression of IL-1b by a growing number of chondrocytes could explain the unrelenting progression of osteoarthritis.

To clarify the short-term results of conservative treatment for symptomatic full-thickness tears of the rotator cuff.

Between September 1996 and August 1999, 107 shoulders of 105 patients were diagnosed as full-thickness tears of the rotator cuff by MRI or arthrography at our institute. All patients were treated conservatively and only 3 shoulders underwent surgery because of persistent pain after 6 months of conservative treatment. Among 104 shoulders treated conservatively for more than 12 months, 102 shoulders of 100 patients were followed up with an average follow-up period of 33 months. Two patients were excluded: one had died and the other had been lost at the time of follow up. Among 102 shoulders, 56 shoulders of 56 patients were assessed by direct examination, and 44 shoulders of 46 patients were interviewed by telephone. There were 54 males and 46 females with an average of 64 years (44–80). The Shoulder Functional Evaluation by the Japanese Orthopaedic Association (JOA score) was used for assessment (full score = 75 points)

The overall JOA score improved significantly from 41.3 points (initial) to 63.5 points (follow-up) (p< .01). Satisfactory results (> - 60 points) were obtained in 71%. The pain score (full score = 30 points) improved from 8.3 points (initial) to 24.7 points (follow-up) (p< .01). At follow-up, 49% had no pain and 88% did not need any medication. The range of motion, abduction strength, and activities of daily living improved significantly (p< .01). Angle of external rotation at initial examination was positively correlated with the JOA score at follow-up (r=0.373, p> .01).

Short-term outcome of conservative treatment for symptomatic full-thickness tears of the rotator cuff was satisfactory in 71% of the patients.

Anatomy of the rotator cuff tendons, their relationship to the greater tuberosity, and the tensile and compressive properties of the cuff tendons have been extensively studied recently. From these anatomical and biomechanical studies, it has been clarified that stress concentration at the anterior portion of the supraspinatus tendon, shearing force, and mechanical friction as well as the degenerative weakness of the cuff tendons can all play a role in the occurrence of a tear. Strength of initial repair is limited, and thus the arm after repair should be positioned such that undue tension at the repair site is eliminated.

We investigated the function of biceps in 18 patients (19 shoulders) with lesions of the rotator cuff. Their mean age was 59 years. Another series of 18 patients (19 shoulders) with normal rotator cuffs as seen on MRI acted as a control group. Their mean age was 55 years. A brace was used to maintain contraction of biceps during elevation. Anteroposterior radiographs were obtained with the arm elevated at 0°, 45° and 90° with and without contraction of biceps. The distance between the centre of the head of the humerus and the glenoid was compared in the two groups.

We found that in the group with tears there was significantly greater proximal migration of the head of the humerus at 0° and 45° of elevation without contraction of biceps but depression of the head of the humerus at 0°, 45° and 90° when biceps was functioning. We conclude that biceps is an active depressor of the head of the humerus in shoulders with lesions of the rotator cuff.

We measured the isokinetic strength of abduction, adduction, internal rotation, and external rotation in ten patients with full-thickness tears of the supraspinatus and ten with partial-thickness tears. The measurements were repeated after intra-articular or intrabursal injection of local anaesthetic.

Pain blocks produced significant increases in strength in both full and partial-thickness tears. After the block, the strength in full-thickness tears compared with the opposite side was 67% to 81% in abduction and 67% to 78% in external rotation, both significantly smaller than those on the uninvolved side (p = 0.0064, p = 0.0170). In partial-thickness tears the strength after the block ranged from 82% to 111%, with no significant differences between the involved and uninvolved sides.

The decreases in strength of 19% to 33% in abduction and 22% to 33% in external rotation after full-thickness tears appear to represent the contribution of supraspinatus to the strength of the shoulder.

The stabilising effects on the glenohumeral joint of each of the rotator-cuff muscles and of the biceps were studied with the arm in abduction and external rotation in 13 cadaver shoulders. The muscles were loaded one at a time with forces proportional to their cross-sectional areas. We recorded the positions of the humeral head before and after the application to the humerus of an anterior force of 1.5 kg. When the capsule was intact, the anterior displacement with the subscapularis loaded was significantly larger than with the other muscles loaded (p = 0.0009). With the capsule vented, the displacement with the biceps loaded was significantly smaller than that with the subscapularis loaded (p = 0.0052). After creating an imitation Bankart lesion, the displacement with the biceps loaded was significantly less than with any of the rotator-cuff muscles loaded (p = 0.0132). We conclude that in the intact shoulder, the subscapularis is the least important anterior stabiliser, and that the biceps becomes more important than the rotator-cuff muscles as stability from the capsuloligamentous structure decreases. Strengthening of the biceps as well as the rotator-cuff muscles should be part of the rehabilitation programme for anterior shoulder instability.

We studied the contributions of the long and short heads of the biceps (LHB, SHB) to anterior stability in 13 cadaver shoulders. The LHB and SHB were replaced by spring devices and translation tests at 90 degrees abduction of the arm were performed by applying a 1.5 kg anterior force. The position of the humeral head was monitored by an electromagnetic tracking device with or without an anterior translational force; with 0 kg, 1.5 kg or 3 kg loads applied on either LHB or SHB tendons in 60 degrees, 90 degrees or 120 degrees of external rotation; and with the capsule intact, vented, or damaged by a Bankart lesion. The anterior displacement of the humeral head under 1.5 kg force was significantly decreased by both the LHB and SHB loading in all capsular conditions when the arm was in 60 degrees or 90 degrees of external rotation. At 120 degrees of external rotation, anterior displacement was significantly decreased by LHB and SHB loading only when there was a Bankart lesion. We conclude that LHB and SHB have similar functions as anterior stabilizers of the glenohumeral joint with the arm in abduction and external rotation, and that their role increases as shoulder stability decreases. Both heads of the biceps have been shown to have a stabilising function in resisting anterior head displacement, and consideration should therefore be given to strengthening the biceps during rehabilitation programmes for chronic anterior instability of the shoulder.