Reflection of power DOPPLER activity in the subacromial space on nocturnal pain in patients with rotator cuff tears: a cross-sectional study.

BACKGROUND: Nocturnal shoulder pain is seen in patients with rotator cuff tears (RCTs). The purpose of the present study was to determine whether Doppler ultrasound parameters predict the intensity of nocturnal pain in patients with RCTs. METHODS: A total of 60 patients with RCTs were included. Doppler ultrasound parameters (peak systolic velocity in the anterior humeral circumflex artery, Doppler activity in the glenohumeral joint and subacromial space [SAS]) and clinical parameters were examined. For the presence of nocturnal pain, the clinical parameters were compared with and without nocturnal pain. For the intensity of the nocturnal pain, a multivariate analysis of clinical parameters and nocturnal pain intensity was performed. RESULTS: In all, 39 patients (65%) reported nocturnal pain, and the mean pain intensity was 47.0 (standard deviation, 26.0) on the visual analog scale. In nocturnal pain presence analysis, Doppler activity in the SAS showed significant associations (P < .001). In nocturnal pain intensity analysis, Doppler activity in the SAS and diabetes showed significant associations (P < .001, P = .01, respectively). CONCLUSION: Doppler activity in the SAS emerges as an independent factor associated with the presence and intensity of nocturnal pain in patients with RCTs. Our findings may provide a basis for further exploration and refinement of treatment strategies.

Inhibitory effect of JAK inhibitor on mechanical stress-induced protease expression by human articular chondrocytes.

OBJECTIVE: To investigate whether janus kinase (JAK) inhibitor exhibits a chondro-protective effect against mechanical stress-induced expression of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) and matrix metalloproteinase (MMPs) in human chondrocytes. MATERIALS AND METHODS: Normal human articular chondrocytes were seeded onto stretch chambers and incubated with or without tofacitinib (1000 nM) for 12 h before mechanical stimulation or cytokine stimulation. Uni-axial cyclic tensile strain (CTS) (0.5 Hz, 10% elongation, 30 min) was applied and the gene expression levels of type II collagen α1 chain (COL2A1), aggrecan (ACAN), ADAMTS4, ADAMTS5, MMP13, and runt-related transcription factor 2 (RUNX-2) were examined by real-time polymerase chain reaction. Nuclear translocation of RUNX-2 and nuclear factor-κB (NF-κB) was examined by immunocytochemistry, and phosphorylation of mitogen-activated protein kinase (MAPK) and signaling transducer and activator of transcription (STAT) 3 was examined by western blotting. The concentration of interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α in the supernatant was examined by enzyme-linked immunosorbent assay. RESULTS: COL2A1 and ACAN gene expression levels were decreased by CTS, but these catabolic effects were canceled by tofacitinib. Tofacitinib significantly down-regulated CTS-induced expression of ADAMTS4, ADAMTS5, MMP13, and RUNX2, and the release of IL-6 in supernatant by chondrocytes. Tofacitinib also reduced CTS-induced nuclear translocation of RUNX-2 and NF-κB, and phosphorylation of MAPK and STAT3. CONCLUSION: Tofacitinib suppressed mechanical stress-induced expression of ADAMTS4, ADAMTS5, and MMP13 by human chondrocytes through inhibition of the JAK/STAT and MAPK cascades.

Shortening Oblique Osteotomy with Screw Fixation for Correction of the Lesser Metatarsophalangeal Joints of Rheumatoid Forefoot.

The metatarsophalangeal (MTP) joints are often and predominantly affected in rheumatoid arthritis. The aim of the current study was to describe surgical techniques of shortening oblique osteotomy for lesser metatarsal bone with screw fixation at the osteotomy site, and to investigate the short-term clinical outcomes of our procedure. Twenty-seven feet (78 toes) of 24 RA patients underwent the shortening oblique osteotomy for the correction of deformity at the lesser MTP joints. The average Japanese Society of Surgery of the Foot (JSSF) standard rating system for the RA foot and ankle scale improved significantly from 59.6 points preoperatively to 88.3 points postoperatively (p＜0.001). Twenty-four feet (89% ) were free from metatarsalgia and symptomatic callosities at the lesser MTP joint after surgery. Our present findings showed satisfactory early clinical outcomes of the shortening oblique osteotomy of the metatarsal bone with screw fixation for RA forefoot.

Clinical and radiographic study of partial arthrodesis for rheumatoid wrists.

OBJECTIVES: To retrospectively investigate the clinical and radiographic results of partial arthrodesis for the wrists with rheumatoid arthritis (RA). METHODS: Forty-one wrists with RA were treated by radiolunate (RL) or radiolunotriquetral (RLT) arthrodesis with ulnar head resection. The average follow-up period after surgery was 7.1 years. Preoperative radiographs of all wrists were classified according to Schulthess classification. We performed RL arthrodesis for all Type II (n = 26) and Type III wrists (n = 7), and RLT arthrodesis for Type III wrists (n = 8). Pre- and postoperative pain score (visual analog scale), grip strength, range of motion, and radiographic parameters were statistically compared. RESULTS: Pain scores in all groups were significantly improved at final follow-up (P < 0.05). Grip strength increased from 5.9 to 12.4 (kg) significantly in Type II wrists (P < 0.01), from 7.2 to 9.1 in Type III wrists after RLT arthrodesis, but decreased from 6.9 to 6.0 in Type III wrists after RL arthrodesis. In all groups, the arc of pronation and supination improved significantly (P < 0.05), and all radiographic parameters improved. CONCLUSIONS: RL arthrodesis for Type II wrists showed satisfactory clinical results. RLT arthrodesis would be a reliable method in case of unstable wrist joint.

Risk factors for surgical site infection and delayed wound healing after orthopedic surgery in rheumatoid arthritis patients.

OBJECTIVE: To investigate the prevalence and the risk factors of surgical-site infection (SSI) and delayed wound healing (DWH) in patients with rheumatoid arthritis (RA) underwent orthopedic surgery. METHODS: We reviewed the records of 1036 elective orthopedic procedures undertaken in RA patients. Risk factors for SSI and DWH were assessed by logistic regression analysis using age, body mass index, disease duration, pre-operative laboratory data, surgical procedure, corticosteroid use, co-morbidity, and use of conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) and biological DMARDs (bDMARDs) as variables. RESULTS: SSI and DWH were identified in 19 cases and 15 cases, respectively. One case of SSI and three cases of DWH were recorded among 196 procedures in patients using bDMARDs. Foot and ankle surgery was associated with an increased risk of SSI (odds ratio (OR), 3.167; 95% confidence interval (CI), 1.256-7.986; p = 0.015). Total knee arthroplasty (TKA; OR, 4.044; 95% CI, 1.436-11.389; p = 0.008) and disease duration (OR, 1.004; 95% CI, 1.000-1.007; p = 0.029) were associated with an increased risk of DWH. CONCLUSIONS: Our results indicated foot and ankle surgery, and TKA and disease duration as risk factors for SSI and DWH, respectively. bDMARDs was not associated with an increased risk of SSI and DWH.

Hyaluronan suppresses mechanical stress-induced expression of catabolic enzymes by human chondrocytes via inhibition of IL-1ß production and subsequent NF-κB activation.

OBJECTIVE: To investigate the inhibitory effect of hyaluronan (HA) on mechanical stress- induced expression of a disintegrin and metalloproteinase with thrombospondin type 1 motifs (ADAMTS)-4, -5 and matrix metalloproteinase (MMP)-13 by human chondrocytes. MATERIALS AND METHODS: Normal human articular chondrocytes were pre-incubated with or without 1.0 mg/mL HA (2700 kDa) for 12 h at 37 °C in stretch chambers, then they were exposed to uni-axial cyclic tensile strain (CTS, 0.5 Hz, 10% elongation). The expression of ADAMTS-4, -5, and MMP-13 were analyzed by real-time polymerase chain reaction and Immunocytochemistry. The concentration of IL-1ß in the supernatant was measured using enzyme-linked immunosorbent assay (ELISA). The nuclear translocation of runt-related transcription factor 2 (RUNX-2) and nuclear factor-κB (NF-κB) was examined by ELISA and immunocytochemistry, and phosphorylation of NF-κB was examined by western blotting. RESULTS: HA inhibited mRNA expression of ADAMTS-4, -5, and MMP13 after 24 h CTS via inhibition of IL-1ß secretion and NF-κB activation. However, HA failed to inhibit CTS-induced RUNX-2 expression and subsequent expression of ADAMTS-5 and MMP-13 1 h after CTS. CONCLUSIONS: Our results demonstrated that HA significantly suppressed mechanical stress-induced expression of catabolic proteases by inhibition of the NF-κB-IL-1ß pathway, but did not suppress mechanical stress-induced RUNX-2 signaling.

MRI of rheumatoid arthritis:comparing the outcome measures in rheumatology clinical trials (OMERACT) scoring and volume of synovitis for the assessment of biologic therapy.

The outcome measures in rheumatology clinical trials (OMERACT) scores are the most mature quantitation system for rheumatoid arthritis (RA) on magnetic resonance imaging (MRI). Direct measuring techniques of synovial volume have been reported with good reproducibility, although few reports have demonstrated the changes of these measures in response to treatment. To assess these clinical responses, we evaluated the correlation of the changes of clinical activity score 28-joints disease activity score (DAS28-CRP) with the changes of OMERACT scores and with synovial volume measurements. Eight RA patients who were treated by biologic agents were examined with MRI of the dominant affected wrist and finger joints before and one year after the treatment. The total OMERACT score was reduced from 48.0 to 41.3, and synovial volume was reduced from 15.4 to 8.8 milliliters. Positive correlations were seen between the changes of DAS28-CRP and the changes of OMERACT synovitis score (r＝0.27), OMERACT total score (r＝0.43) and synovial volume (r＝0.30). Limited to synovium assessment, synovial volume showed a better correlation with DAS28-CRP than the OMERACT synovitis score. On the other hand, the OMERACT total score showed a higher correlation with DAS28-CRP than synovial volume, probably because the OMERACT total score includes scores for bone erosion and bone edema as well.

Short-term results of the PROSNAP linked elbow prosthesis with a snap-in structure and modular flange for the reconstruction of severely damaged rheumatoid elbows.

BACKGROUND: We aimed to evaluate the early clinical results of the reconstruction of problematic elbow joints due to rheumatoid arthritis (RA) using a PROSNAP linked elbow prosthesis (Kyocera Medical, Osaka, Japan) for total elbow arthroplasty. METHODS: Seventeen elbows in 14 RA patients were replaced with a PROSNAP elbow with cement fixation. The patients comprised 1 man and 13 women, with a mean age of 63.9 years (range, 52-83 years) at the time of surgery. The preoperative conditions of the elbows were arthritis mutilans (n = 10), an ankylosed or stiff elbow with a preoperative range of motion of 45° or less (n = 4), and loosening of a primary total elbow arthroplasty (n = 3). The mean follow-up period was 47.7 months (range, 32-69 months), with a 100% follow-up rate. The clinical outcome of the elbows was evaluated by the Mayo Elbow Performance Index (maximum, 100 points). RESULTS: The mean postoperative Mayo Elbow Performance Index score improved from 57.6 points to 97.1 points. Preoperatively, 3 of the 17 elbows were judged as good, 7 as fair, and 7 as poor; at final follow-up, 16 elbows were judged as excellent and 1 as good. Complications were noted in 1 elbow (6%), which had undergone a postoperative fracture. CONCLUSIONS: The PROSNAP elbow prosthesis can be safely implanted through a relatively easy procedure and provides satisfactory short-term clinical outcomes for the reconstruction of severely damaged RA elbows. LEVEL OF EVIDENCE: Level IV, case series, treatment study.

Enhanced Achilles Tendon Gliding Through Ultrasound-Guided Manual Therapy Post-surgical Repair: A Case Report.

Achilles tendon rupture is a common injury with established surgical treatments, but optimizing postoperative recovery remains challenging. Dynamic tendon gliding is necessary for normal ankle function, yet its role in recovery is not fully understood. This report highlights a novel approach using dynamic ultrasound imaging and ultrasound-guided manual therapy to improve Achilles tendon gliding post-surgery. A 65-year-old man presented eight weeks after surgical repair of a left Achilles tendon rupture. Despite full weight-bearing ability and normal range of motion, the patient exhibited persistent dysfunction, such as an inability to perform single-leg stands and single-leg heel raises. Suspecting a dynamic issue with the Achilles tendon, dynamic ultrasound revealed significant adhesion between the Achilles tendon and Kager's fat pad. To address this, ultrasound-guided manual therapy, involving specific mobilization of the tendon under ultrasound visualization, was initiated. The patient underwent 16 sessions over eight weeks, during which real-time ultrasound confirmed gradual improvement in tendon gliding. Post-treatment, the patient achieved marked functional recovery, demonstrated by the ability to perform single-leg heel raises and toe walking. His Achilles tendon Total Rupture Score improved from 47 to 75 points, with sustained benefits observed at the 26-week follow-up. Ultrasound-guided manual therapy targeting tendon gliding dysfunction improved functional recovery in this patient. This approach underscores the importance of addressing tendon gliding in rehabilitation protocols to optimize outcomes. Further research is needed to validate these findings with a broader patient population.

Blood flow velocity in the anterior humeral circumflex artery and tear size can predict synovitis severity in patients with rotator cuff tears.

BACKGROUND: Rotator cuff tears are often associated with synovitis, but the ability of noninvasive ultrasonography to predict the severity of synovitis remains unclear. We investigated whether ultrasound parameters, namely peak systolic velocity in the anterior humeral circumflex artery and Doppler activity in the glenohumeral joint and subacromial space, reflect synovitis severity. METHODS: A total of 54 patients undergoing arthroscopic rotator cuff repair were selected. Doppler ultrasound was used to measure peak systolic velocity in the anterior humeral circumflex artery and Doppler activity in the glenohumeral joint and subacromial space, and these values were compared with the intraoperative synovitis score in univariate and multivariate analyses. RESULTS: Univariate analyses revealed that tear size, peak systolic velocity in the anterior humeral circumflex artery, and Doppler activity in the glenohumeral joint were associated with synovitis in the glenohumeral joint (P=0.02, P<0.001, P=0.02, respectively). In the subacromial space, tear size, peak systolic velocity in the anterior humeral circumflex artery, and Doppler activity in the subacromial space were associated with synovitis severity (P=0.02, P<0.001, P=0.02, respectively). Multivariate analyses indicated that tear size and peak systolic velocity in the anterior humeral circumflex artery were independently associated with synovitis scores in both the glenohumeral joint and the subacromial space (all P<0.05). CONCLUSIONS: These findings demonstrate that tear size and peak systolic velocity in the anterior humeral circumflex artery, which can both be measured noninvasively, are useful indicators of synovitis severity. Level of evidence: IV.

A new perspective on tissue gliding dysfunction bordered by deep fascia as an indicator of delayed onset muscle soreness: A case report.

INTRODUCTION: The deep fascia, especially its thickness and stiffness, plays an important role in the mechanism of delayed onset muscle soreness (DOMS). Here, we present a patient with DOMS associated with a tissue gliding dysfunction bordered by the deep fascia. CASE PRESENTATION: A 25-year-old woman developed DOMS of the left upper arm. We confirmed the tissue gliding dysfunction during manual skin traction by ultrasound imaging and treated with acupuncture aimed at stimulating the deep fascia. Tissue gliding between subcutaneous and muscle tissues bordered by the deep fascia was analyzed qualitatively and quantitatively, i.e., phases and distance of displacement. At the initial examination, the tissue gliding phases were in the same direction synchronously and the distance of displacement was 0.66mm. After the DOMS symptoms improved with direct acupuncture to the deep fascia, the phases changed independently in opposite directions and their displacement was 7.04mm. CONCLUSIONS: In this patient, tissue gliding played an important role in the symptoms of DOMS. This case report focusing on tissue gliding provides a new perspective on understanding the pathogenesis of DOMS.

Discovering the Forgotten Trauma Behind Chronic Shoulder Pain: The Critical Role of a Thorough Medical Interview.

We report a rare case of a patient experiencing pain and dysfunction attributable to bone fragments from a trauma sustained over two decades prior. A 43-year-old Japanese woman presented with persistent left shoulder pain. Initial radiographs revealed glenohumeral joint osteoarthritis, an unusual finding for her age. Her medical history included a previously overlooked traumatic dislocation of the left acromioclavicular joint over 20 years ago. Computed tomography scans later uncovered bone fragments below the coracoid process without signs of scapular or tuberosity fractures. The fragments were arthroscopically removed, resulting in significant pain relief. The patient's Shoulder Pain and Disability Index score improved from 60 to 9 at the six-month postoperative follow-up. This case underscores the importance of considering historical trauma in patients presenting with atypical shoulder pain and highlights the potential diagnostic value of revisiting a patient's medical history when unusual lesions are discovered.

Synchronization of Blood Flow Velocity in the Anterior Humeral Circumflex Artery and Reduction in Night Pain After Arthroscopic Rotator Cuff Repair: A Case Report.

Rotator cuff tears are commonly associated with pain at rest and at night particularly if lying on the affected shoulder. This case describes a 54-year-old man who reported concerns of severe night pain in his left shoulder and had to undergo arthroscopic rotator cuff repair. The severity of night pain and blood flow velocity in the anterior humeral circumflex artery (AHCA) were measured over time. The patient reported his night pain as 10/10 on the numerical rating scale in the first week after surgery. In the fourth week, he rated his night pain as 6/10, and in the fifth week, his pain was <2/10. We measured blood flow velocity in the AHCA using a 3-11MHz color Doppler and power Doppler ultrasound (SONIMAGE HS2, Konica Minolta, Tokyo, Japan), and we calculated peak systolic velocity. The course of peak systolic velocity in the AHCA ranged from 27.7 to 62.4 cm/s until four weeks after surgery when his night pain was severe; AHCA flow velocity ranged from 16.7 to 19.3 cm/s five weeks after surgery when his night pain had reduced. The initially high blood flow velocity in the AHCA decreased almost simultaneously with the improvement in night pain. Our case highlights that blood flow velocity in the AHCA synchronized with the severity of night pain, which may contribute to the understanding of sleep disturbances in patients after arthroscopic rotator cuff repair.

Video Evidence of Tissue Sliding Improvement by Ultrasound-Guided Hydrorelease on Scars After Arthroscopic Knee Surgery: A Case Report.

Postoperative scarring is a complication of arthroscopic knee surgery that causes a lack of terminal extension and tissue sliding defects. We present video evidence of tissue sliding before and after ultrasound-guided hydrorelease in a 53-year-old man. The patient presented with pain in the scarred area following arthroscopic knee surgery. His active and passive extension was -5° with restricted patellar mobility. Dynamic ultrasonography revealed scar tissue sliding defects. For ultrasound-guided hydrorelease, a needle (22G, 60 mm) was aimed at a site within 10 mm depth of the hypoechoic change in the scar area below the patella, and saline solution (10 mL) mixed with 1% lidocaine (10 mL) and 10 mg prednisolone was injected. Immediately after injection, the patient's extension was 0° with no pain or limitation of patellar mobility, and dynamic ultrasonography showed tissue sliding improved. Video evidence from dynamic ultrasonography clarifies the direction of the inadequate slide and the indication for and efficacy of ultrasound-guided hydrorelease. This case highlights the benefits of video evidence from dynamic ultrasonography before and after ultrasound-guided hydrorelease.

Successful Pain Relief With Duloxetine in a Patient With Chronic Postsurgical Pain After Open Reduction and Internal Fixation: A Case Report.

Chronic postsurgical pain (CPSP) is a common complication of surgery. We report that a patient with CPSP after open reduction and internal fixation (ORIF) had pain relief with duloxetine, and that the conditioned pain modulation (CPM) efficiency may predict the efficacy of duloxetine. A 54-year-old woman with CPSP after ORIF due to proximal humeral fracture was presented to our orthopedic clinic one month after surgery. Despite several analgesics, she still had pain three months after surgery, pain during activity was 74 on the visual analogue scale (VAS), 16 on the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), 18 on the PainDETECT questionnaire, and CPM efficiency was -5.7%. The patient was treated with duloxetine, starting at 20mg/day and increasing every week. Three months after starting duloxetine, pain on the VAS was 18, ASES was 61, PainDETECT questionnaire was 6, and CPM efficiency was -39.8%. The dose of duloxetine was decreased every week and then withdrawn. Neuropathic pain may be involved even in patients with CPSP after ORIF, and duloxetine may be efficacious in such cases. CPM testing may provide useful information for clinicians in selecting appropriate drugs and in determining when to withdraw drugs.

A New Procedure for Ultrasound-Guided Hydrorelease for the Scarring After Arthroscopic Knee Surgery.

Postoperative scarring is one of the complications after arthroscopic knee surgery, which is usually treated with manual therapy or arthroscopic debridement. The incidence of symptomatic scarring requiring surgery within six months postoperatively has been reported to be approximately 0.06-6.00%. We treated a patient after arthroscopic surgery with a new "ultrasound-guided hydrorelease" procedure and we describe it. A 50-year-old woman with a history of arthroscopic anterior cruciate ligament reconstruction of the right knee presented to our clinic 10 months ago with a complaint of right anterior knee pain. Ultrasound imaging showed an infrapatellar fat pad (IPFP) scarring and sliding defects. The pre-treatment Kujala scale was 62 points and the visual analogue scale was 72. The inferolateral side of the patella was palpated to identify the scarring after arthroscopy at the IPFP area. An ultrasound probe was applied vertically to identify the site of adhesion of interest. Ultrasound-guided hydrorelease was performed using 7.0mL saline injected by needle (22G, 60mm) directed at the site with hypoechoic changes in the IPFP. After the procedure, the normalization of the IPFP sliding was confirmed by an ultrasound image. Four weeks after this procedure, the patient improved, with a Kujala scale of 82 points and a visual analogue scale of 28. The most important finding from this patient's course is that her chief complaint of anterior knee pain improved by ultrasound-guided hydrorelease into the IPFP scarring after arthroscopic knee surgery. The procedure should be considered as a treatment for scarring after arthroscopic knee surgery.

Outcomes of Resection and Joint-Preserving Arthroplasty for Forefoot Deformities for Rheumatoid Arthritis.

BACKGROUND: We investigated the clinical outcomes of resection and joint-preserving arthroplasty for forefoot deformities in patients with rheumatoid arthritis. METHODS: Sixteen feet of 14 women (average age, 67.1 years; range, 53-82) underwent resection arthroplasty of the metatarsal head (resection group), and 18 feet of 15 women (average age, 61.3 years; range, 40-73) underwent a metatarsophalangeal joint-preserving procedure with shortening oblique metatarsal osteotomies of the lesser toes (joint preservation group). The mean disease duration in the resection and joint preservation groups was 23.6 and 19.1 years, and the average follow-up period was 37.3 and 33.5 months, respectively. The classification of Larsen was used to assess the severity of destruction of the metatarsophalangeal (MTP) joint. Preoperative and postoperative clinical evaluation included Japanese Society for Surgery of the Foot (JSSF) score and postoperative complications. RESULTS: The number of preoperative radiographic destruction of the MTP joints (Larsen grade II, III, IV, and V) was 0, 29, 39, and 12 joints in the resection group and 13, 67, 9, and 1 joints in the joint preservation group. The mean JSSF score improved significantly from 61.3 to 83.9 points in the resection group ( P < .001) and from 62.2 to 90.8 points in the joint preservation group ( P < .001). In the resection group, recurrence of callosities and claw toe deformity was observed in 6 and 3 feet, respectively. In the joint-preserving group, recurrence of callosities and hammer toe deformity was observed in 1 foot each. CONCLUSION: The resection arthroplasty and joint-preserving procedure showed satisfactory clinical outcomes. However, whether both procedures can maintain the good clinical results without the recurrence of forefoot deformity will require longer follow-up. LEVEL OF EVIDENCE: Level III, retrospective comparative series.

Observation of Landau levels in potassium-intercalated graphite under a zero magnetic field.

The charge carriers in graphene are massless Dirac fermions and exhibit a relativistic Landau-level quantization in a magnetic field. Recently, it has been reported that, without any external magnetic field, quantized energy levels have been also observed from strained graphene nanobubbles on a platinum surface, which were attributed to the Landau levels of massless Dirac fermions in graphene formed by a strain-induced pseudomagnetic field. Here we show the generation of the Landau levels of massless Dirac fermions on a partially potassium-intercalated graphite surface without applying external magnetic field. Landau levels of massless Dirac fermions indicate the graphene character in partially potassium-intercalated graphite. The generation of the Landau levels is ascribed to a vector potential induced by the perturbation of nearest-neighbour hopping, which may originate from a strain or a gradient of on-site potentials at the perimeters of potassium-free domains.

He and Ar beam scatterings from bare and defect induced graphite surfaces.

The effect of the local electronic modification of the graphite surface on the gas-graphite interaction has been investigated by the molecular beam scattering technique. The angular intensity distributions of He and Ar beams scattered from pristine and defect induced graphite surfaces have been measured at various surface temperatures. From the He scattering results, the cross-section for the He diffuse scattering per defect is estimated as being as much as 113 nm(2). The origin of the extremely large cross-section is ascribed to the modulated electronic states of graphite around the defect based on the STM measurements, which is due to the local breaking of the π conjugated system of graphite. From the Ar scattering results, the effective mass of the graphite surface for the Ar collision has been estimated as M = 114 u, based on the analysis with the hard cube model. The new component appears in the scattering distribution of Ar for the defect induced graphite surface. The component has a larger peak position angle than that for the pristine graphite surface, indicating that the normal component of the translational energy of the Ar atom was greatly lost by the collision at the electronically modified area of graphite.