Noboru Matsumura - Academia.edu (original) (raw)

Papers by Noboru Matsumura

Modern Rheumatology Case Reports

The Keio Journal of Medicine

Percutaneous ultrasonic tendon needling has been used to treat persistent lateral epicondylitis, ... more Percutaneous ultrasonic tendon needling has been used to treat persistent lateral epicondylitis, and its efficacy has been demonstrated. However, whether ultrasonography is necessary remains unclear. The purpose of this retrospective study was to evaluate the efficacy of percutaneous tendon needling without ultrasonography for lateral epicondylitis. A total of 36 patients who underwent tendon needling without ultrasonography for lateral epicondylitis were retrospectively included in the study. The tendinotic lesion was needled by fenestration approximately 20-30 times without sonographic assistance. The Visual Analogue Scale (VAS) pain score, the grip strength, and success rates were assessed at baseline and at 1, 3, 6, and 12 months after treatment. The Nirschl tennis elbow score was evaluated at baseline and at 6 and 12 months after the needling procedure. The mean VAS pain score and grip strength at 3, 6, and 12 months significantly improved compared to the baseline values. At 6 and 12 months, the success rates had significantly increased compared to the rates at 1 month. The mean Nirschl scores at 6 and 12 months were significantly better than the baseline value. No severe complications were observed during the study period. Percutaneous tendon needling without ultrasonography is a simple and safe technique. The procedure is effective for lateral epicondylitis that is unresponsive to conventional conservative treatments.

Journal of Shoulder and Elbow Surgery

The Journal of Hand Surgery

Journal of Shoulder and Elbow Surgery

Scientific reports, Jan 31, 2017

Fatty infiltration in muscle is often observed in patients with sizable rotator cuff tear (RCT) a... more Fatty infiltration in muscle is often observed in patients with sizable rotator cuff tear (RCT) and is thought to be an irreversible event that significantly compromises muscle plasticity and contraction strength. These changes in the mechanical properties of the affected muscle render surgical repair of RCT highly formidable. Therefore, it is important to learn more about the pathology of fatty infiltration to prevent this undesired condition. In the present study, we aimed to generate a mouse model that can reliably recapitulate some of the important characteristics of muscular fatty infiltration after RCT in humans. We found that fatty infiltration can be efficiently induced by a combination of the following procedures: denervation of the suprascapular nerve, transection of the rotator cuff tendon, and resection of the humeral head. Using this model, we found that platelet-derived growth factor receptor-α (PDGFRα)-positive mesenchymal stem cells are induced after this interventio...

Journal of Medical Cases, 2017

We here present two very rare cases of high median nerve palsy caused by pseudoaneurysm after bra... more We here present two very rare cases of high median nerve palsy caused by pseudoaneurysm after brachial catheterization. A 71-yearold woman developed high median nerve palsy 2 weeks after brachial catheterization. She underwent pseudoaneurysm resection together with neurolysis 4 months after the onset of palsy. Surgical findings suggested that her palsy was caused by both severe compression by pseudoaneurysm and adhesion following hematoma after catheterization. Five months after the surgery, she only had slight sensory disturbance. A 48-year-old lady developed high median nerve palsy 1 week after the catheterization. Simple pseudoaneurysm resection was performed 2 weeks after the catheterization. Neurolysis was not performed. Seven months after the surgery, she still had severe sensory disturbance. Our cases suggested importance of secured astriction after catheterization, and recommended surgical procedure for this condition is combination of pseudoaneurysm resection and neurolysis by hand surgeons.

Modern rheumatology / the Japan Rheumatism Association, Jan 12, 2016

We examined the clinical features and functional outcomes of surgically repaired subcutaneous fle... more We examined the clinical features and functional outcomes of surgically repaired subcutaneous flexor tendon ruptures in patients with rheumatoid arthritis (RA). This retrospective study included 41 fingers of 24 RA patients who underwent surgical treatment for flexor tendon ruptures. Evaluations performed at the time of presentation following rupture were C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and disease activity score in 28 joints (DAS28)-ESR, as well as Larsen grading for carpal bone destruction. The ruptured tendon and postoperative active range of motion (ROM) of digits were also examined. The mean CRP was 2.4 mg/dl, ESR was 52 mm/h, and the DAS28-ESR was 4.5. Carpal bone destruction according to Larsen grade IV-V was observed in 18/24 patients. Affected digits were most commonly the thumb (12) and the ring and little fingers (9 each). Tendon ruptures were most common in the carpal tunnel in zone IV. The mean postoperative finger ROM (flexion/extension)...

Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.], Jan 16, 2015

An understanding of normal glenohumeral geometry is important for anatomical reconstruction in sh... more An understanding of normal glenohumeral geometry is important for anatomical reconstruction in shoulder arthroplasty. Unfortunately, the details of the glenohumeral joint in Asian populations have not been sufficiently evaluated. The purpose of this study was to evaluate the 3-dimensional geometry of the glenohumeral joint in the normal Japanese population and to clarify its morphologic features. Anthropometric analysis of the glenohumeral joint was performed using computed tomography scans of 160 normal shoulders from healthy Japanese volunteers. The glenohumeral dimensions and orientation were analyzed 3-dimensionally. Sex differences and correlations between sides and among the respective parameters in the glenohumeral dimensions were evaluated. The normal Japanese humeral head has an average width of 41.4 mm, thickness of 13.2 mm, diameter of 42.9 mm, retroversion of 32°, and inclination of 135°. The glenoid has an average height of 31.5 mm, width of 23.1 mm, diameter of 62.0 mm...

Modern rheumatology / the Japan Rheumatism Association, Jan 3, 2015

This retrospective study was designed to evaluate the outcomes of four different surgical reconst... more This retrospective study was designed to evaluate the outcomes of four different surgical reconstructions for extensor tendon ruptures in ulnar three fingers in 48 patients with rheumatoid arthritis. The following four techniques were performed; palmaris longus tendon grafting (PL group; n = 9), extensor indicis proprius (EIP) tendon transfers (EIP group; n = 8), end-to-side transfers with tension-reduced early mobilization (End-to-side group; n = 16), and a combination of end-to-side and EIP transfers (Combination group; n = 15). Loss of extension was evaluated to determine the mean postoperative range of motion of the metacarpophalangeal (MP) joint and clinical outcomes were categorized using modified Geldmacher criteria. Combination group demonstrated the best mean MP joint extension (- 3°), followed by End-to-side group (- 12°), EIP group (- 16°), and PL group (- 21°). Combination group yielded the best clinical outcomes with all cases showing good results. The combination of en...

Journal of orthopaedic research : official publication of the Orthopaedic Research Society, Jan 25, 2015

Frozen shoulder is a relatively common disorder that leads to severe pain and stiffness in the sh... more Frozen shoulder is a relatively common disorder that leads to severe pain and stiffness in the shoulder joint. Although this disorder is self-limiting in nature, the symptoms often persist for years, resulting in severe disability. Recent studies using human specimens and animal models have shown distinct changes in the gene expression patterns in frozen shoulder tissue, indicating that novel therapeutic intervention could be achieved by controlling the genes that are potentially involved in the development of frozen shoulder. To achieve this goal, it is imperative to develop a reliable animal joint contracture model in which gene expression can be manipulated by gene targeting and transgenic technologies. Here, we describe a novel shoulder contracture mouse model. We found that this model mimics the clinical presentation of human frozen shoulder and recapitulates the changes in the gene expression pattern and the histology of frozen shoulder and joint contracture in humans and othe...

Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.], 2014

The morphologic features and clinical significance of version of the humeral head and glenoid rem... more The morphologic features and clinical significance of version of the humeral head and glenoid remain unclear. The purpose of this study was to evaluate the normal values of humeral head version and glenoid version on computed tomography scans and to clarify their features in the normal glenohumeral joint. Images for analysis were computed tomography scans of 410 normal shoulders from healthy volunteers. Values of humeral head and glenoid version were measured. In glenoid version measurement, 3-dimensionally corrected slices were reconstructed to eliminate scapular inclination. Differences in humeral head version and glenoid version were assessed between dominant and nondominant shoulders and between men and women. Correlation analyses were also performed in the values of version between dominant and nondominant shoulders and between humeral head version and glenoid version. The values of humeral head retroversion were widely distributed from -2° to 60°, with an average of 26° ± 11°....

Journal of wrist surgery, 2014

Background As the triangular fibrocartilage complex (TFCC) anchors the distal radius to the ulna ... more Background As the triangular fibrocartilage complex (TFCC) anchors the distal radius to the ulna via the radioulnar ligament (RUL), a severely displaced distal fragment of the radius may be associated with a foveal avulsion of the TFCC. The purpose of this retrospective study was to assess, radiographically and arthroscopically, the relationship between displacement of the radius, the ulnar styloid, and avulsion of the RUL resulting in distal radioulnar joint (DRUJ) instability. Materials and Methods Twenty-nine wrists of 29 patients with intra- and extra-articular distal radius fractures/malunion who underwent reduction or a corrective osteotomy of the displaced/malunited fracture, and/or wrist arthroscopy, were assessed radiographically and arthroscopically. Radial translation, radial inclination, radial shortening, volar or dorsal tilt, and the presence of an ulnar styloid fracture with more than 4 mm of displacement were measured from the initial films. Radiocarpal arthroscopy w...

Modern Rheumatology, 2014

Ulnar deviation is a common complication in patients with rheumatoid arthritis (RA). We report a ... more Ulnar deviation is a common complication in patients with rheumatoid arthritis (RA). We report a case of an unusual radial deviation of the middle finger caused by an occult intramuscular ganglion of the second interosseous muscle (IOM) in a patient with RA. The resection of the ganglion did not resolve the problem, and the full range of motion of the metacarpophalangeal (MP) joint was achieved through dissection of the tendon of the second dorsal IOM.

Journal of Vascular and Interventional Radiology, 2013

Purpose: To evaluate the feasibility and effects of transcatheter arterial embolization with imip... more Purpose: To evaluate the feasibility and effects of transcatheter arterial embolization with imipenem/cilastatin sodium (CS) to treat tendinopathy and enthesopathy that are refractory to traditional nonsurgical management. Materials and Methods: Transcatheter arterial embolization with imipenem/CS as an embolic agent was performed in seven patients (five men; mean age, 51.7 y) with tendinopathy and enthesopathy (patellar tendinopathy, n ¼ 1; rotator cuff tendinopathy, n ¼ 2; plantar fasciitis, n ¼ 1; lateral epicondylitis, n ¼ 1; iliotibial band syndrome, n ¼ 1; and Achilles insertion tendinopathy, n ¼ 1). All patients had unrelenting pain at the site of tendinopathy and enthesopathy before the procedure. Technical success, adverse events, and changes in visual analog scale (VAS) scores were assessed. Results: All procedures were technically successful, and no major adverse events developed. Compared with before the procedure, mean VAS scores were significantly decreased at 1 day, 1 week, and 1 and 4 months after the procedure (72.7 mm Ϯ 9.9 vs 17.4

Journal of Shoulder and Elbow Surgery, 2013

Hypothesis: We hypothesized that the clavicle overrides the acromion during certain shoulder moti... more Hypothesis: We hypothesized that the clavicle overrides the acromion during certain shoulder motions for individuals with acromioclavicular (AC) joint separation producing clinical symptoms. We measured 3dimensional clavicular and scapular motions in AC joint separation models during humerothoracic motions, which should be impacted by the loss of AC joint continuity. Materials and methods: Ten shoulders from 6 whole cadavers were used. The scapular and clavicular motions were measured in intact and AC joint separation models using an electromagnetic tracking device. The measurement was performed during shoulder abduction with humerothoracic neutral rotation. It was also measured during shoulder abduction with humerothoracic internal rotation, which could cause clavicular overriding. The kinematic changes caused by ligament sectioning were evaluated in these 2 arm motions. Results: The clavicle completely overrode the acromion in all AC separation models during abduction with internal rotation, but not in any shoulders during abduction with neutral rotation. Upward clavicular rotation increased, posterior clavicular rotation decreased, and external scapular rotation decreased with ligament sectioning. These kinematic changes were common for both of the measured arm motions. Scapular upward rotation and posterior tilt did not change because of ligament sectioning during abduction with neutral rotation. However, these scapular rotations significantly decreased with ligament sectioning during shoulder abduction with internal rotation. Conclusion: Scapular and clavicular kinematics were affected in AC separation models. Abduction with humeral internal rotation resulted in a decrease in scapular posterior tilt and upward rotation in AC separation models, and thereby could lead to AC joint articulation dysfunction.

Modern Rheumatology Case Reports

The Keio Journal of Medicine

Percutaneous ultrasonic tendon needling has been used to treat persistent lateral epicondylitis, ... more Percutaneous ultrasonic tendon needling has been used to treat persistent lateral epicondylitis, and its efficacy has been demonstrated. However, whether ultrasonography is necessary remains unclear. The purpose of this retrospective study was to evaluate the efficacy of percutaneous tendon needling without ultrasonography for lateral epicondylitis. A total of 36 patients who underwent tendon needling without ultrasonography for lateral epicondylitis were retrospectively included in the study. The tendinotic lesion was needled by fenestration approximately 20-30 times without sonographic assistance. The Visual Analogue Scale (VAS) pain score, the grip strength, and success rates were assessed at baseline and at 1, 3, 6, and 12 months after treatment. The Nirschl tennis elbow score was evaluated at baseline and at 6 and 12 months after the needling procedure. The mean VAS pain score and grip strength at 3, 6, and 12 months significantly improved compared to the baseline values. At 6 and 12 months, the success rates had significantly increased compared to the rates at 1 month. The mean Nirschl scores at 6 and 12 months were significantly better than the baseline value. No severe complications were observed during the study period. Percutaneous tendon needling without ultrasonography is a simple and safe technique. The procedure is effective for lateral epicondylitis that is unresponsive to conventional conservative treatments.

Journal of Shoulder and Elbow Surgery

The Journal of Hand Surgery

Journal of Shoulder and Elbow Surgery

Scientific reports, Jan 31, 2017

Fatty infiltration in muscle is often observed in patients with sizable rotator cuff tear (RCT) a... more Fatty infiltration in muscle is often observed in patients with sizable rotator cuff tear (RCT) and is thought to be an irreversible event that significantly compromises muscle plasticity and contraction strength. These changes in the mechanical properties of the affected muscle render surgical repair of RCT highly formidable. Therefore, it is important to learn more about the pathology of fatty infiltration to prevent this undesired condition. In the present study, we aimed to generate a mouse model that can reliably recapitulate some of the important characteristics of muscular fatty infiltration after RCT in humans. We found that fatty infiltration can be efficiently induced by a combination of the following procedures: denervation of the suprascapular nerve, transection of the rotator cuff tendon, and resection of the humeral head. Using this model, we found that platelet-derived growth factor receptor-α (PDGFRα)-positive mesenchymal stem cells are induced after this interventio...

Journal of Medical Cases, 2017

We here present two very rare cases of high median nerve palsy caused by pseudoaneurysm after bra... more We here present two very rare cases of high median nerve palsy caused by pseudoaneurysm after brachial catheterization. A 71-yearold woman developed high median nerve palsy 2 weeks after brachial catheterization. She underwent pseudoaneurysm resection together with neurolysis 4 months after the onset of palsy. Surgical findings suggested that her palsy was caused by both severe compression by pseudoaneurysm and adhesion following hematoma after catheterization. Five months after the surgery, she only had slight sensory disturbance. A 48-year-old lady developed high median nerve palsy 1 week after the catheterization. Simple pseudoaneurysm resection was performed 2 weeks after the catheterization. Neurolysis was not performed. Seven months after the surgery, she still had severe sensory disturbance. Our cases suggested importance of secured astriction after catheterization, and recommended surgical procedure for this condition is combination of pseudoaneurysm resection and neurolysis by hand surgeons.

Modern rheumatology / the Japan Rheumatism Association, Jan 12, 2016

We examined the clinical features and functional outcomes of surgically repaired subcutaneous fle... more We examined the clinical features and functional outcomes of surgically repaired subcutaneous flexor tendon ruptures in patients with rheumatoid arthritis (RA). This retrospective study included 41 fingers of 24 RA patients who underwent surgical treatment for flexor tendon ruptures. Evaluations performed at the time of presentation following rupture were C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and disease activity score in 28 joints (DAS28)-ESR, as well as Larsen grading for carpal bone destruction. The ruptured tendon and postoperative active range of motion (ROM) of digits were also examined. The mean CRP was 2.4 mg/dl, ESR was 52 mm/h, and the DAS28-ESR was 4.5. Carpal bone destruction according to Larsen grade IV-V was observed in 18/24 patients. Affected digits were most commonly the thumb (12) and the ring and little fingers (9 each). Tendon ruptures were most common in the carpal tunnel in zone IV. The mean postoperative finger ROM (flexion/extension)...

Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.], Jan 16, 2015

An understanding of normal glenohumeral geometry is important for anatomical reconstruction in sh... more An understanding of normal glenohumeral geometry is important for anatomical reconstruction in shoulder arthroplasty. Unfortunately, the details of the glenohumeral joint in Asian populations have not been sufficiently evaluated. The purpose of this study was to evaluate the 3-dimensional geometry of the glenohumeral joint in the normal Japanese population and to clarify its morphologic features. Anthropometric analysis of the glenohumeral joint was performed using computed tomography scans of 160 normal shoulders from healthy Japanese volunteers. The glenohumeral dimensions and orientation were analyzed 3-dimensionally. Sex differences and correlations between sides and among the respective parameters in the glenohumeral dimensions were evaluated. The normal Japanese humeral head has an average width of 41.4 mm, thickness of 13.2 mm, diameter of 42.9 mm, retroversion of 32°, and inclination of 135°. The glenoid has an average height of 31.5 mm, width of 23.1 mm, diameter of 62.0 mm...

Modern rheumatology / the Japan Rheumatism Association, Jan 3, 2015

This retrospective study was designed to evaluate the outcomes of four different surgical reconst... more This retrospective study was designed to evaluate the outcomes of four different surgical reconstructions for extensor tendon ruptures in ulnar three fingers in 48 patients with rheumatoid arthritis. The following four techniques were performed; palmaris longus tendon grafting (PL group; n = 9), extensor indicis proprius (EIP) tendon transfers (EIP group; n = 8), end-to-side transfers with tension-reduced early mobilization (End-to-side group; n = 16), and a combination of end-to-side and EIP transfers (Combination group; n = 15). Loss of extension was evaluated to determine the mean postoperative range of motion of the metacarpophalangeal (MP) joint and clinical outcomes were categorized using modified Geldmacher criteria. Combination group demonstrated the best mean MP joint extension (- 3°), followed by End-to-side group (- 12°), EIP group (- 16°), and PL group (- 21°). Combination group yielded the best clinical outcomes with all cases showing good results. The combination of en...

Journal of orthopaedic research : official publication of the Orthopaedic Research Society, Jan 25, 2015

Frozen shoulder is a relatively common disorder that leads to severe pain and stiffness in the sh... more Frozen shoulder is a relatively common disorder that leads to severe pain and stiffness in the shoulder joint. Although this disorder is self-limiting in nature, the symptoms often persist for years, resulting in severe disability. Recent studies using human specimens and animal models have shown distinct changes in the gene expression patterns in frozen shoulder tissue, indicating that novel therapeutic intervention could be achieved by controlling the genes that are potentially involved in the development of frozen shoulder. To achieve this goal, it is imperative to develop a reliable animal joint contracture model in which gene expression can be manipulated by gene targeting and transgenic technologies. Here, we describe a novel shoulder contracture mouse model. We found that this model mimics the clinical presentation of human frozen shoulder and recapitulates the changes in the gene expression pattern and the histology of frozen shoulder and joint contracture in humans and othe...

Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.], 2014

The morphologic features and clinical significance of version of the humeral head and glenoid rem... more The morphologic features and clinical significance of version of the humeral head and glenoid remain unclear. The purpose of this study was to evaluate the normal values of humeral head version and glenoid version on computed tomography scans and to clarify their features in the normal glenohumeral joint. Images for analysis were computed tomography scans of 410 normal shoulders from healthy volunteers. Values of humeral head and glenoid version were measured. In glenoid version measurement, 3-dimensionally corrected slices were reconstructed to eliminate scapular inclination. Differences in humeral head version and glenoid version were assessed between dominant and nondominant shoulders and between men and women. Correlation analyses were also performed in the values of version between dominant and nondominant shoulders and between humeral head version and glenoid version. The values of humeral head retroversion were widely distributed from -2° to 60°, with an average of 26° ± 11°....

Journal of wrist surgery, 2014

Background As the triangular fibrocartilage complex (TFCC) anchors the distal radius to the ulna ... more Background As the triangular fibrocartilage complex (TFCC) anchors the distal radius to the ulna via the radioulnar ligament (RUL), a severely displaced distal fragment of the radius may be associated with a foveal avulsion of the TFCC. The purpose of this retrospective study was to assess, radiographically and arthroscopically, the relationship between displacement of the radius, the ulnar styloid, and avulsion of the RUL resulting in distal radioulnar joint (DRUJ) instability. Materials and Methods Twenty-nine wrists of 29 patients with intra- and extra-articular distal radius fractures/malunion who underwent reduction or a corrective osteotomy of the displaced/malunited fracture, and/or wrist arthroscopy, were assessed radiographically and arthroscopically. Radial translation, radial inclination, radial shortening, volar or dorsal tilt, and the presence of an ulnar styloid fracture with more than 4 mm of displacement were measured from the initial films. Radiocarpal arthroscopy w...

Modern Rheumatology, 2014

Ulnar deviation is a common complication in patients with rheumatoid arthritis (RA). We report a ... more Ulnar deviation is a common complication in patients with rheumatoid arthritis (RA). We report a case of an unusual radial deviation of the middle finger caused by an occult intramuscular ganglion of the second interosseous muscle (IOM) in a patient with RA. The resection of the ganglion did not resolve the problem, and the full range of motion of the metacarpophalangeal (MP) joint was achieved through dissection of the tendon of the second dorsal IOM.

Journal of Vascular and Interventional Radiology, 2013

Purpose: To evaluate the feasibility and effects of transcatheter arterial embolization with imip... more Purpose: To evaluate the feasibility and effects of transcatheter arterial embolization with imipenem/cilastatin sodium (CS) to treat tendinopathy and enthesopathy that are refractory to traditional nonsurgical management. Materials and Methods: Transcatheter arterial embolization with imipenem/CS as an embolic agent was performed in seven patients (five men; mean age, 51.7 y) with tendinopathy and enthesopathy (patellar tendinopathy, n ¼ 1; rotator cuff tendinopathy, n ¼ 2; plantar fasciitis, n ¼ 1; lateral epicondylitis, n ¼ 1; iliotibial band syndrome, n ¼ 1; and Achilles insertion tendinopathy, n ¼ 1). All patients had unrelenting pain at the site of tendinopathy and enthesopathy before the procedure. Technical success, adverse events, and changes in visual analog scale (VAS) scores were assessed. Results: All procedures were technically successful, and no major adverse events developed. Compared with before the procedure, mean VAS scores were significantly decreased at 1 day, 1 week, and 1 and 4 months after the procedure (72.7 mm Ϯ 9.9 vs 17.4

Journal of Shoulder and Elbow Surgery, 2013

Hypothesis: We hypothesized that the clavicle overrides the acromion during certain shoulder moti... more Hypothesis: We hypothesized that the clavicle overrides the acromion during certain shoulder motions for individuals with acromioclavicular (AC) joint separation producing clinical symptoms. We measured 3dimensional clavicular and scapular motions in AC joint separation models during humerothoracic motions, which should be impacted by the loss of AC joint continuity. Materials and methods: Ten shoulders from 6 whole cadavers were used. The scapular and clavicular motions were measured in intact and AC joint separation models using an electromagnetic tracking device. The measurement was performed during shoulder abduction with humerothoracic neutral rotation. It was also measured during shoulder abduction with humerothoracic internal rotation, which could cause clavicular overriding. The kinematic changes caused by ligament sectioning were evaluated in these 2 arm motions. Results: The clavicle completely overrode the acromion in all AC separation models during abduction with internal rotation, but not in any shoulders during abduction with neutral rotation. Upward clavicular rotation increased, posterior clavicular rotation decreased, and external scapular rotation decreased with ligament sectioning. These kinematic changes were common for both of the measured arm motions. Scapular upward rotation and posterior tilt did not change because of ligament sectioning during abduction with neutral rotation. However, these scapular rotations significantly decreased with ligament sectioning during shoulder abduction with internal rotation. Conclusion: Scapular and clavicular kinematics were affected in AC separation models. Abduction with humeral internal rotation resulted in a decrease in scapular posterior tilt and upward rotation in AC separation models, and thereby could lead to AC joint articulation dysfunction.