Publications by authors named "Shota Hoshika"

22 Publications

  • Page 1 of 1

Three-dimensional kinematics of reverse shoulder arthroplasty: a comparison between shoulders with good or poor elevation.

JSES Int 2021 May 31;5(3):353-359. Epub 2021 Mar 31.

Department of Mechanical & Aerospace Engineering, University of Florida, Gainesville, FL, USA.

Background: Various factors may be related to outcomes of reverse shoulder arthroplasty (RSA) including patient and surgical factors. Differences in shoulder kinematics might be associated with poor function after RSA; however, kinematic differences between shoulders with good or poor elevation have not been elucidated. The purpose of this study was to compare RSA kinematics between shoulders with good or poor elevation.

Methods: The study included 28 shoulders with a minimum 6-month follow-up after RSA using Grammont-type prostheses. Subjects comprised 17 men and 11 women with the mean age of 75 years (range, 63-91). Subjects underwent fluoroscopy during active scapular plane abduction. Computed tomography of their shoulders was performed to create 3-dimensional scapular implant models. Using model-image registration techniques, poses of 3-dimensional implant models were iteratively adjusted to match their silhouettes with the silhouettes in the fluoroscopic images, and 3-dimensional kinematics of implants were computed. Kinematics and glenosphere orientation were compared between shoulders with good (>90 degree) or poor (<90 degree) scapular plane abduction.

Results: Nineteen and 9 shoulders were assigned to the good- and poor-elevation groups, respectively. There were no significant differences between the groups in age, sex, height, weight, preoperative range of motion, or Constant score, but body mass index in the poor elevation shoulders was significantly larger than that in the good elevation shoulders. There were no significant differences in glenosphere (upward/downward rotation, anterior/posterior tilt, internal/external rotation) or glenohumeral (internal/external rotation, abduction/adduction) kinematics between the good and poor elevation shoulders. Scapulohumeral rhythm was significantly higher in the good elevation shoulders than the poor elevation shoulders ( = .04). Glenosphere superior tilt was 2.3° ± 4.2° in the good-elevation group and 8.1° ± 8.9° in the poor-elevation group, and the difference was statistically significant ( = .03).

Discussion: Shoulders with good elevation after RSA demonstrated better scapulohumeral rhythm than those with poor elevation, though there were no significant differences in glenosphere and glenohumeral kinematics. It may be important for better elevation to achieve good glenohumeral motion in shoulders with RSA. Glenosphere orientations may affect postoperative shoulder function.
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http://dx.doi.org/10.1016/j.jseint.2021.02.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8178639PMC
May 2021

Arthroscopic Soft Tissue Stabilization With Selective Augmentations for Traumatic Anterior Shoulder Instability in Competitive Collision Athletes.

Am J Sports Med 2021 05 12;49(6):1604-1611. Epub 2021 Apr 12.

Shoulder and Elbow Service, Funabashi Orthopaedic Sports Medicine and Joint Center, Funabashi, Japan.

Background: Many surgeons prefer bony stabilization including Bristow or Latarjet procedures for shoulder instability in collision athletes, even though several potential complications have been reported. There has been a limited number of studies on the midterm outcomes of arthroscopic soft tissue stabilization for anterior shoulder instability in competitive collision athletes.

Purpose: To assess the outcomes of arthroscopic soft tissue stabilization in combination with selective augmentation procedures for collision athletes with traumatic anterior shoulder instability.

Study Design: Case series; Level of evidence, 4.

Methods: We retrospectively assessed rugby or American football players (<40 years old) who underwent arthroscopic Bankart or bony Bankart repair with selective augmentations (rotator interval closure and/or Hill-Sachs remplissage) for traumatic anterior shoulder instability between January 2012 and March 2017. Shoulders that required other bony procedures were excluded. Recurrence, complications, return to sport, and functional scores (Rowe score and Subjective Shoulder Value sports score) were investigated.

Results: This study included 113 shoulders in 100 patients with a mean age of 20 years (range, 15-36 years) at surgery. Rotator interval closure was performed on 36 shoulders in addition to Bankart repair, and rotator interval closure and Hill-Sachs remplissage were performed on 77 shoulders. The mean follow-up period was 44 months (range, 24-72 months). Of the 113 shoulders, 4 (3.5%) experienced postoperative dislocation, but there were no complications. A total of 93 athletes (93%) attained complete or near complete preinjury sports activity levels. The mean Rowe score significantly improved from 36 (range, 10-75) at presurgery to 96 (range, 35-100; = .003) at postsurgery. The mean Subjective Shoulder Value sports score significantly improved after surgery, from a mean preoperative score of 22 (range, 0-50) to a postoperative score of 92 (range, 64-100; = .002).

Conclusion: Our treatment strategy, where arthroscopic soft tissue stabilization was combined with selected augmentations, provided good clinical outcomes for competitive collision athletes in terms of low rates of recurrence and complication, a high rate of return to sports, and good shoulder function.
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http://dx.doi.org/10.1177/03635465211003091DOI Listing
May 2021

In vivo measurement of distance between scapular neck and polyethylene insert during active external rotation in shoulders with Grammont type reverse prosthesis.

Clin Biomech (Bristol, Avon) 2021 Apr 26;84:105341. Epub 2021 Mar 26.

Department of Mechanical & Aerospace Engineering, University of Florida, 330 MAE-A P.O. Box 116250, Gainesville, FL 32611-6250, USA.

Background: Scapular notching is a frequently observed complication after reverse shoulder arthroplasty. Impingement of the humeral plastic insert against the scapular neck is believed to be the cause of notching. There have been no in vivo studies that analyzed the positional relationship between the scapular neck and humeral insert. The purpose of this study was to measure the distance between the scapular neck and insert in shoulders with Grammont-type prostheses during active external rotation at the side.

Methods: Eighteen shoulders with Grammont-type prostheses were enrolled in this study. There were 13 males and 5 females, and the mean age at surgery was 74 years (range, 63-91). Fluoroscopic images were recorded during active external rotation at the side from maximum internal to external rotation at an average of 14 months (range, 7-24) after surgery. Implant kinematics were determined with three-dimensional models of the implants and fluoroscopic images using model-image registration techniques. Based on the implant kinematics, the closest distance between the scapular neck and insert was computed at each 5° increment of glenohumeral internal/external rotation.

Results: Mean glenohumeral abduction during rotation was 17°-22°. The mean distance between the neck and insert was approximately 1 mm throughout the activity. The separation distance tended to narrow with arm external rotation, but the change was not significant.

Interpretation: The small distance between the scapular neck and insert in early post-operative reverse shoulder arthroplasty patients may be associated with the high incidence of scapular notching in Grammont-type prostheses.
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http://dx.doi.org/10.1016/j.clinbiomech.2021.105341DOI Listing
April 2021

Arthroscopic Iliac Bone Grafting for Traumatic Anterior Shoulder Instability with Significant Glenoid Bone Loss Yields Low Recurrence and Good Outcome at a Minimum of Five-year Follow-Up.

Arthroscopy 2021 Mar 24. Epub 2021 Mar 24.

Funabashi Orthopaedic Sports Medicine and Joint Center, Funabashi, Chiba.

Purpose: The purpose of this study was to investigate the clinical and radiographic outcomes of arthroscopic iliac bone grafting with capsulolabral reconstruction for severe glenoid bone loss with a minimum of 5 years' follow-up.

Methods: The inclusion criterion was shoulders that underwent arthroscopic iliac bone grafting for >20%-25% glenoid defect between January 2007 and April 2014, and the exclusion criterion was <5 years' follow-up. Iliac crest bone grafts of approximately 2.0 cm length and 0.8 cm height were arthroscopically fixed to the anterior glenoid using 2 cannulated screws followed by capsulolabral repair. Rowe score, Western Ontario Shoulder Instability Index (WOSI), and passive range of motion were evaluated. Radiographic findings including the Kellgren and Lawrence osteoarthritis grade and graft integration on 3-dimensional computed tomography at the final follow-up were also evaluated.

Results: Forty-eight shoulders met the inclusion criteria, and 24 shoulders with ≥5 years' follow-up were included (1 died; 23 were lost follow-up): 22 males, 2 females; a mean age at surgery, 30 years (range, 18-52 years); a mean follow-up of 8 years (range, 5-11 years). The mean preoperative glenoid bone defect was 22% (range, 20%-28%). All shoulders had a Hill-Sachs lesion including 4 on-track lesions. One shoulder experienced traumatic redislocation at 5 years after surgery. The scores significantly improved: Rowe score, 19 ± 8 to 94 ± 8 (P < .001); WOSI, 1547 ± 241 to 439 ± 318 (P < .001). Postoperative flexion showed significant improvement from 158 ± 18 to 169 ± 11 (P = .008), whereas internal rotation deteriorated from T8 ± 3 to T10 ± 3 (P = .005). Graft integration showed remodeling in 54% and excessive absorption in 13%. Osteoarthritis grades progressed significantly (P < .001), but only grade 1 osteoarthritic changes were seen, except for 4 shoulders with grade 2 osteoarthritis.

Conclusions: Arthroscopic iliac bone grafting for traumatic anterior shoulder instability with severe glenoid bone loss yielded satisfactory outcomes with mid-term follow-up. Arthritic changes progressed in half of the shoulders; however, most shoulders only demonstrated grade 1 osteoarthritis.

Level Of Evidence: Level IV, therapeutic case series.
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http://dx.doi.org/10.1016/j.arthro.2021.03.028DOI Listing
March 2021

Comparison Between Osteochondral Autograft Transplantation and Arthroscopic Fragment Resection for Large Capitellar Osteochondritis Dissecans in Adolescent Athletes: A Minimum 5 Years' Follow-up.

Am J Sports Med 2021 04 11;49(5):1145-1151. Epub 2021 Mar 11.

Funabashi Orthopaedic Sports Medicine and Joint Center, Funabashi, Chiba, Japan.

Background: The choice of surgical option for unstable large capitellar osteochondritis dissecans (OCD) lesions in skeletally immature athletes remains controversial.

Purpose/hypothesis: The purpose was to investigate functional and radiographic outcomes after arthroscopic fragment resection and osteochondral autograft transplantation (OAT) for unstable large capitellar OCD lesions in skeletally immature athletes with a minimum 5 years' follow-up. We hypothesized that the outcomes after OAT for large capitellar OCD lesions would be superior to those after arthroscopic fragment resection.

Study Design: Cohort study; Level of evidence, 3.

Methods: A total of 19 elbows in 19 patients (17 male and 2 females) who underwent arthroscopic resection were assigned to group 1 (mean age, 14 years [range, 13-15 years]), whereas 29 elbows in 29 patients (29 male) who underwent OAT were assigned to group 2 (mean age, 14 years [range, 13-15 years]), with the mean follow-up of 8 (range, 5-11 years) and 7 (range, 5-13 years) years, respectively. All OCD lesions were larger than one-half of the radial head diameter. Functional scores, patient satisfaction, and range of motion were compared between the groups. Radiographic changes, including superior migration, radial head enlargement, and osteoarthritis (OA) grade, were examined.

Results: All patients returned to sports activity. Functional scores, patient satisfaction, and flexion at the final follow-up were significantly improved in both groups compared with preoperative values, and differences were not significant between groups at the final follow-up. Extension showed a significant improvement in both groups (group 1: -17° to 0°; group 2: -18° to -6°; < .001). Extension in group 1 was significantly better than that in group 2 at the final follow-up ( = .045). No elbows developed postoperative severe OA in group 1, whereas 3 elbows in group 2 had grade 3 OA; these 3 elbows had preoperative superior migration and radial head enlargement.

Conclusion: No differences were observed in clinical and radiographic outcomes between patients undergoing arthroscopic fragment resection and OAT, except for elbow extension, at a minimum 5 years' follow-up. We believe that for adolescents with large capitellar OCD lesion, OAT is a good option for skeletally immature elbows and that arthroscopic fragment resection is a reliable and less invasive surgical option for relatively mature elbows.
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http://dx.doi.org/10.1177/0363546521994558DOI Listing
April 2021

Three-dimensional measurement of proximal radioulnar space during active forearm pronation.

J Biomech 2020 12 9;113:110120. Epub 2020 Nov 9.

Department of Mechanical & Aerospace Engineering, University of Florida, 330 MAE-A P.O. Box 116250, Gainesville, FL 32611-6250, USA.

Distal biceps tendon ruptures have been reported to be associated with narrowing of the proximal radioulnar space. There have been no studies that three-dimensionally measured the distance between the bicipital tuberosity and the proximal ulna during active motion. The purpose of this study was to three-dimensionally measure the proximal radioulnar space during active forearm pronation in healthy subjects. Five healthy volunteers (10 forearms) were recruited for this study. They consisted of all males with a mean age of 37 years (range, 34-46 years). Lateral fluoroscopy of forearm rotation from maximum supination to maximum pronation was recorded for both forearms. Three-dimensional forearm kinematics were determined using model-image registration techniques with fluoroscopic images and CT-derived bone models, and the closest distance between the bicipital tuberosity and the proximal ulna was computed at each 30° increment of radial axial rotation relative to the distal humerus. The distance between the bicipital tuberosity and the proximal ulna decreased with pronation, reaching a minimum value at 90° of radial rotation (average 4.6 ± 1.3 mm), then increased with further rotation to maximum pronation (P = 0.004). The clearance between the proximal radioulnar space and the distal biceps tendon is very small (<1mm). Hypertrophy of the bicipital tuberosity or tendon can induce impingement and lead to tendon rupture.
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http://dx.doi.org/10.1016/j.jbiomech.2020.110120DOI Listing
December 2020

Superior Labral Injuries in Elite Gymnasts: Symptoms, Pathology, and Outcomes After Surgical Repair.

Orthop J Sports Med 2020 Jul 14;8(7):2325967120935001. Epub 2020 Jul 14.

Funabashi Orthopaedic Sports Medicine and Joint Center, Funabashi, Chiba, Japan.

Background: Superior labral anterior-posterior (SLAP) lesions are common among elite gymnasts and throwing athletes. Although SLAP lesions in throwers are well-described in the literature, no study has described the characteristics of SLAP lesions in gymnasts. We aimed to reveal the characteristics of SLAP lesions in gymnasts by comparing the location and extension of these lesions between gymnasts and throwers.

Hypothesis: The location and arc of SLAP lesions in gymnasts will be different from those in throwing athletes.

Study Design: Case series; Level of evidence, 4.

Methods: This study included 27 shoulders in 20 males and 3 females with a mean ± SD age of 20 ± 2.5 years (range, 16-25 years). We performed debridement alone for shoulders with a stable lesion. Anterior and/or posterior labral repair was added for unstable SLAP lesions depending on the extension and stability of the lesions. We investigated symptoms, onset, return to sport (based on patient records), and subjective shoulder values. SLAP lesions were evaluated through use of the Snyder classification. The location and arc of SLAP lesions were determined from surgical records and videos and described by use of the right shoulder clockface method. During the same period, 65 baseball players (65 shoulders; all males; mean age, 23 ± 7.0 years; range, 16-44 years) underwent arthroscopic SLAP surgery. We compared the location and arc of SLAP lesions between gymnasts and baseball players.

Results: Symptoms during gymnastics included pain (100%), apprehension (48%), or catching (11%). We found that 20 shoulders had symptom onset during gymnastics, most commonly during rings events. Type II SLAP lesions were found in 17 shoulders, type III in 2 shoulders, and type IV in 8 shoulders. The mean center of SLAP lesions was at the 11:40 clockface position in 27 gymnasts and 10:40 clockface position in 65 baseball players, and the difference was statistically significant ( < .001). The mean arc of SLAP lesions was 125° in gymnasts and 140° in baseball players, and the difference was not significant. We performed debridement in 2 shoulders (7%) and labral repair in 25 shoulders (93%). After surgery, all patients returned to gymnastics. The mean subjective shoulder value was 35 (range, 10-90) preoperatively and 76 (range, 40-100) postoperatively.

Conclusion: SLAP lesions in gymnasts were significantly located anteriorly compared with those in baseball players. All patients returned to gymnastics after arthroscopic surgery. Secure repair of SLAP lesions may be important for good surgical outcomes, because 50% of patients experienced preoperative shoulder apprehension.
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http://dx.doi.org/10.1177/2325967120935001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7361489PMC
July 2020

Repair Integrity and Retear Pattern After Arthroscopic Medial Knot-Tying After Suture-Bridge Lateral Row Rotator Cuff Repair.

Am J Sports Med 2020 08 14;48(10):2510-2517. Epub 2020 Jul 14.

Funabashi Orthopaedic Sports Medicine and Joint Center, Funabashi, Chiba, Japan.

Background: Type 2 failure is a big issue after suture-bridge rotator cuff repair, which may be because of stress concentration at the medial row stitches. We have been performing medial knot-tying after suture-bridge lateral row repair to avoid the stress concentration. This study aimed to evaluate clinical and radiological outcomes after arthroscopic rotator cuff repair using this technique.

Hypothesis: This technique would yield better radiological outcomes with a reduced type 2 failure rate compared with reported outcomes after conventional suture-bridge repair.

Study Design: Case series; Level of evidence, 4.

Methods: The inclusion criteria of this study were (1) full-thickness tears, (2) primary surgery, and (3) minimum 2-year follow-up with pre- and postoperative magnetic resonance imaging (MRI). We investigated active ranges of motion (forward elevation and external rotation), as well as the Japanese Orthopaedic Association (JOA) and University of California, Los Angeles (UCLA), scores preoperatively and at the final follow-up.

Results: This study included 384 shoulders in 373 patients (205 men and 168 women) with a mean age of 65 years (range, 24-89 years) at the time of surgery. The mean follow-up was 29 months (range, 24-60 months). There were 91 small, 137 medium, 121 large, and 35 massive tears. Postoperative MRI scans demonstrated successful repair in 324 shoulders (84.4%, group S) and retear in 60 shoulders (15.6%). Among 60 retears, 40 shoulders (67%) had type 1 failure (group F1) and 20 shoulders (33%) had type 2 failure (group F2). Forward elevation and external rotation significantly improved after surgery ( < .001 for both). Postoperative JOA and UCLA scores in group F2 were significantly lower than those in the other groups.

Conclusion: The medial knot-tying after suture-bridge lateral row repair demonstrated excellent functional and radiological outcomes after surgery, with a retear rate of 15.6%. The type 2 failure showed significantly inferior functional outcomes; however, the rate of type 2 failure was less relative to previous studies using conventional suture-bridge techniques. Our technique could be a good alternative to conventional suture-bridging rotator cuff repair because it may reduce the rate of postoperative type 2 failure.
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http://dx.doi.org/10.1177/0363546520934786DOI Listing
August 2020

Return to Sport After Arthroscopic Rotator Cuff Repair in Middle-Aged and Elderly Swimmers.

Orthop J Sports Med 2020 Jun 17;8(6):2325967120922203. Epub 2020 Jun 17.

Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.

Background: No reports have been published on the clinical outcomes, including return to sport, after rotator cuff repair in middle-aged and elderly swimmers with rotator cuff tears.

Purpose: To retrospectively investigate clinical outcomes and return to sport after arthroscopic rotator cuff repair in middle-aged and elderly swimmers.

Study Design: Case series; Level of evidence, 4.

Methods: Patients who underwent arthroscopic rotator cuff repair and met the following criteria were included: (1) age older than 45 years, (2) rotator cuff tears confirmed during surgery, (3) arthroscopic suture bridge rotator cuff repair, (4) primary surgery, and (5) swam more than once a week before surgery. The exclusion criteria were as follows: (1) irreparable large and massive tears, (2) shoulder instability, (3) arthritis or rheumatic disorders, or (4) less than 2-year follow-up. We investigated functional outcomes including range of motion; the University of California, Los Angeles (UCLA) score; the American Shoulder and Elbow Surgeons (ASES) score; return to swimming; and the return rates for each style of swimming. In addition, the functional outcomes and findings of magnetic resonance imaging were compared between the group with complete return and the group with incomplete or failed return.

Results: A total of 32 shoulders in 31 middle-aged and elderly swimmers (5 males, 26 females) were included. The mean age was 65 years (range, 47-78 years), and the mean follow-up was 47 months (range, 24-86 months). Return to swimming was achieved in 31 (97%) shoulders at a mean of 8 months (range, 3-24 months), and complete return was achieved in 18 (56%) shoulders at a mean of 12 months (range, 3-24 months). The return rate was 97% for freestyle, 83% for breaststroke, 74% for backstroke, and 44% for butterfly stroke. Postoperative UCLA and ASES scores were significantly higher in the group with complete return than in the group with incomplete or failed return ( = .001 and .01, respectively). Postoperative forward elevation was significantly better in the complete return group ( = .01).

Conclusion: This study demonstrated that 97% of elderly swimmers who underwent arthroscopic rotator cuff repair could return to swimming. The complete return rate was 56%; however, the group with incomplete or failed return showed poorer active forward elevation. Freestyle had the highest complete return rate, whereas the butterfly stroke had the lowest return rate. It may be important to achieve good active forward elevation postoperatively to return to swimming.
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http://dx.doi.org/10.1177/2325967120922203DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7301663PMC
June 2020

Valgus stability is enhanced by flexor digitorum superficialis muscle contraction of the index and middle fingers.

J Orthop Surg Res 2020 Mar 30;15(1):121. Epub 2020 Mar 30.

Department of Clinical Anatomy, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University, Tokyo, Japan.

Background: Flexor digitorum superficialis (FDS) muscle provides dynamic stabilization and medial elbow support for ulnar collateral ligament (UCL). The FDS contraction significantly affects the medial joint distance (MJD) through grip contraction. However, it remains unclear whether FDS activity alone contributes to medial elbow stability, or together with the activation of the flexor digitorum profundus during grip contraction, and which finger's FDS is the main contributor to elbow stability. We investigated the resistive effects of isolated FDS contraction in individual fingers against valgus stress in the elbow joint using stress ultrasonography (US).

Methods: We investigated 17 healthy males (mean age, 27 ± 5 years). Valgus stress US was performed using the Telos device, with the elbow at 30° flexion. MJD was measured for each arm during 3 separate conditions: at rest (unloaded), under valgus load (50 N) (loaded), and under valgus load with FDS contracted in individual fingers (loaded-contracted).

Results: MJD was significantly longer when loaded (5.4 ± 0.4 mm) than unloaded (4.1 ± 0.2 mm, P = 0.007) or loaded-contracted (4.6 ± 0.3 mm, P = 0.003) for each finger. When loaded-contracted, MJD differed statistically between the index and ring fingers (P = 0.03) and between the middle and ring fingers (P = 0.04). However, the difference between the index and middle fingers was not statistically significant (P = 0.08).

Conclusions: Individual FDS contraction, particularly of the index and middle fingers, contributes most to stabilization against valgus stress. Thus, injury care programs should incorporate FDS exercises of these fingers.
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http://dx.doi.org/10.1186/s13018-020-01640-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7110663PMC
March 2020

Incidence of Axillary Nerve Injury After Arthroscopic Shoulder Stabilization.

Arthroscopy 2020 06 26;36(6):1555-1564. Epub 2020 Feb 26.

Nagareyama Central Hospital, Nagareyama, Japan.

Purpose: To investigate the incidence of axillary nerve palsy after arthroscopic shoulder stabilization and to measure the distance between the nerve and capsule in shoulders with a capsular lesion.

Methods: This retrospective study included 2,027 shoulders (1,909 patients; 1,433 male and 476 female patients; mean age, 32 years [age range, 13-81 years]) subjected to arthroscopic soft-tissue stabilization for recurrent shoulder instability from 2005 to 2017. The exclusion criteria were bone grafting or transfer and preoperative axillary nerve symptoms. We retrospectively reviewed patient records and investigated the incidence and clinical features of axillary nerve palsy. We measured the closest distance between the axillary nerve and capsule on preoperative magnetic resonance images.

Results: Postoperative axillary nerve palsy occurred in 4 shoulders (0.2% of all arthroscopic stabilizations). Capsular repair was performed in 2 shoulders (1.2% of 160 capsular repairs); humeral avulsion of the glenohumeral ligament (HAGL) repair, 1 shoulder (2% of 47 HAGL repairs); and isolated Bankart repair, 1 shoulder (0.05% of 1,941 Bankart repairs). The closest distance between the nerve and capsule was 3.4 ± 3.2 mm in shoulders with capsular or HAGL lesions and less than 1 mm in the 3 shoulders with palsy. The common symptoms in axillary nerve palsy cases were shoulder discomfort, delayed recovery of range of motion, and deltoid weakness and atrophy. A definitive diagnosis was made with electromyography in all cases. Nerve injury by a suture was confirmed during revision surgery in 3 shoulders subjected to capsular or HAGL repair during the initial operation. The palsy was transient and fully recovered in 1 shoulder with isolated Bankart repair.

Conclusions: The incidence of axillary nerve palsy after arthroscopic soft-tissue shoulder stabilization was low but higher in shoulders subjected to capsular or HAGL repair. We should always consider the possibility of axillary nerve palsy in shoulders that require capsular or HAGL repair.

Level Of Evidence: Level IV, therapeutic case series.
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http://dx.doi.org/10.1016/j.arthro.2020.02.016DOI Listing
June 2020

Relationship between postoperative retear and preoperative fatty degeneration in large and massive rotator cuff tears: quantitative analysis using T2 mapping.

J Shoulder Elbow Surg 2019 Aug;28(8):1562-1567

Department of Orthopaedic Surgery, Eastern Chiba Medical Center, Togane, Chiba, Japan.

Background: Fatty degeneration of the rotator cuff muscles is reported to be associated with retear after rotator cuff repair. The purpose of this study was to assess the relationship between retear and preoperative fatty degeneration, as quantified by T2 mapping.

Methods: This prospective cohort study included 83 large and 24 massive rotator cuff tears (average age, 67 years; range, 46-82 years). All patients preoperatively underwent T2 mapping magnetic resonance imaging, and T2 values of the supraspinatus and infraspinatus muscles were quantified. Cuff integrity was evaluated with magnetic resonance imaging 1 year postoperatively. Preoperative T2 values were compared between the retear and intact groups. The preoperative Goutallier stage, Constant score, and the shoulder score of the University of California at Los Angeles were also compared between the 2 groups.

Results: Retear was found in 32 shoulders (30%). Postoperative Constant and University of California at Los Angeles scores were significantly higher in intact shoulders than in retear shoulders (P < .001 for both). Mean preoperative T2 values of supraspinatus and infraspinatus were 77.4 ± 13.2 ms and 73.2 ± 15.3 ms in retear shoulders and 66.5 ± 11.1 ms and 58.6 ± 11.7 ms in intact shoulders, respectively; the differences were significant in both muscles (P < .001). Cutoff values for prediction of retear were 71.8 ms in supraspinatus and 63.1 ms in infraspinatus. There were no significant differences in the preoperative Goutallier stages of supraspinatus and infraspinatus between the 2 groups.

Conclusions: Retear shoulders demonstrated significantly higher preoperative T2 values than intact shoulders. T2 mapping can be a useful tool for predicting postoperative retears.
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http://dx.doi.org/10.1016/j.jse.2019.04.036DOI Listing
August 2019

Prevalence and Site of Rotator Cuff Lesions in Shoulders With Recurrent Anterior Instability in a Young Population.

Orthop J Sports Med 2019 Jun 4;7(6):2325967119849876. Epub 2019 Jun 4.

Funabashi Orthopaedic Sports Medicine and Joint Center, Funabashi, Chiba, Japan.

Background: Partial articular supraspinatus tendon avulsion (PASTA) lesions are often seen in shoulders of throwing athletes. PASTA lesions in anterior instability are also found in recurrent anterior glenohumeral instability.

Purpose: To investigate the prevalence and location of rotator cuff tears (RCTs), including PASTA lesions, in shoulders with recurrent anterior instability.

Study Design: Case series; Level of evidence, 4.

Methods: A total of 842 shoulders in 801 patients with recurrent anterior instability (647 men, 154 women; mean age, 24 years; age range, 13-40 years) who underwent arthroscopic surgery at the age of 40 years or younger were enrolled. During surgery, the thickness and the sites of RCTs as well as patient factors associated with RCTs were examined.

Results: RCTs were found in 57 shoulders (7%) in 56 patients. There were 4 shoulders with full-thickness RCTs and 54 shoulders with PASTA lesions. All lesions but 1 involved the anterior border of the supraspinatus (SSP). Participation in high-level athletics and older age at injury were associated with RCTs.

Conclusion: The incidence of RCTs was 7% in shoulders with recurrent anterior instability at age 40 years or younger. Most RCTs were PASTA lesions that involved the anterior border of the SSP.
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http://dx.doi.org/10.1177/2325967119849876DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6552367PMC
June 2019

Three-dimensional measurement of glenoid dimensions and orientations.

J Orthop Sci 2019 Jul 20;24(4):624-630. Epub 2018 Dec 20.

Department of Mechanical and Aerospace Engineering, University of Florida, 330 MAE-A P.O. Box 116250, Gainesville, FL 32611-6250, USA.

Background: Asians generally have smaller stature than Europeans and Americans, and currently available implants used in reverse shoulder arthroplasty might not fit smaller bony anatomies. However, few articles have reported glenoid geometry in the Asian population. The purpose of this study was to measure the dimensions and orientations of the glenoid from three-dimensional computed tomography reconstructions of elderly Japanese subjects.

Methods: This study included 100 shoulders (50 males and 50 females with >50 years of age). The mean age was 67 ± 7 years for both sexes, and the mean height was 167 ± 7 cm for males and 154 ± 6 cm for females. Three-dimensional scapular models were created from computed tomographic images, and the glenoid height, glenoid width, glenoid version, glenoid inclination, vault depth, and vault width were measured.

Results: The mean glenoid height and width were 38.6 and 29.4 mm for males and 33.1 and 24.4 mm for females, respectively. Both retroversion and superior inclination were approximately 3° in both sexes. The glenoid vault was deeper in the posterior region with the maximum depth of 26.1 and 23.6 mm in males and females. The vault width was narrower in the anterior region with the anterior width of 2.5 mm at 15 mm medial from the glenoid face in females.

Conclusion: Glenoids of Japanese females are small compared to currently available baseplates for reverse shoulder arthroplasty. These results may be helpful to aid design in smaller baseplates that better fit the anatomic geometry of the Asian glenoid.
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http://dx.doi.org/10.1016/j.jos.2018.11.019DOI Listing
July 2019

Medial elbow anatomy: A paradigm shift for UCL injury prevention and management.

Clin Anat 2019 Apr 9;32(3):379-389. Epub 2019 Jan 9.

Department of Clinical Anatomy, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University, Tokyo, Japan.

To improve the management outcomes and diagnostic accuracy of the ulnar collateral ligament (UCL) injury, the anatomy of the medial side of the elbow joint is necessary to be understood in terms of the periarticular surroundings rather than the specific ligaments. The aim of this study was to anatomically clarify the medial side of the elbow joint in terms of the tendinous structures and joint capsule. We conducted a descriptive anatomical study of 23 embalmed cadaveric elbows. We macroscopically analyzed the relationship between the flexor pronator muscles (FPMs) and the joint capsule in 10 elbows, histologically analyzed in 6 elbows, and observed the bone morphology through micro computed tomography in 7 elbows. The two tendinous septa (TS) were found: between the pronator teres (PT) and flexor digitorum superficial (FDS) muscles, and between the FDS and flexor carpi ulnaris (FCU) muscles. These two TS are connected to the medial part of the brachialis tendon, deep aponeurosis of the FDS, and FCU to form the tendinous complex, which linked the humeroulnar joint and could not be histologically separated from each other. Moreover, the capsule of the humeroulnar joint under the tendinous complex had attachment on the ST of 7 mm width. The two TS, the brachialis tendon, the deep FDS and FCU aponeuroses, and the joint capsule linked the humeroulnar joint. These anatomical findings could lead to a paradigm shift in the prevention, diagnosis, and treatment of UCL injuries in baseball players. Clin. Anat. 32:379-389, 2019. © 2018 The Authors. Clinical Anatomy published by Wiley Periodicals, Inc. on behalf of American Association of Clinical Anatomists.
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http://dx.doi.org/10.1002/ca.23322DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6850211PMC
April 2019

Scaption kinematics of reverse shoulder arthroplasty do not change after the sixth postoperative month.

Clin Biomech (Bristol, Avon) 2018 10 5;58:1-6. Epub 2018 Jul 5.

Department of Mechanical and Aerospace Engineering, University of Florida, 330 MAE-A, P.O. Box 116250, Gainesville, FL 32611-6250, USA.

Background: Changes over time in shoulder kinematics and function after reverse shoulder arthroplasty have not been reported. The purpose of this study was to compare shoulder kinematics and function at 6 months and 1 year after reverse shoulder arthroplasty.

Methods: Twenty patients with a mean age of 74 years (range, 63-91 years) were enrolled in this study. Fluoroscopic images during scapular plane elevation were recorded at the mean of 6 months (range, 5-8 months) and 14 months (range, 11-21 months). CT-derived glenosphere models and computer-aided design humeral implant models were matched with the silhouette of the implants in the fluoroscopic images using model-image registration techniques. Glenosphere and humeral implant kinematics during scaption were compared between the two time points. Patients were also clinically examined with active range of motion and Constant score, and postoperative improvement in shoulder function were assessed.

Results: Active flexion and Constant score improved after surgery (p < 0.001 for both), but there was no significant improvement after six months. There was no significant improvement in active external rotation at either postoperative exam. There were no significant differences in glenosphere or humeral kinematics between six months and one year.

Interpretation: There was no significant additional improvement in either shoulder kinematics during scapular plane elevation or function between the sixth and twelfth postoperative months. We can assess kinematics at six months after reverse shoulder arthroplasty to determine how the shoulder will move. Clinically, treatment in the first six postoperative months should be emphasized to achieve better surgical outcomes.
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http://dx.doi.org/10.1016/j.clinbiomech.2018.07.005DOI Listing
October 2018

Arthroscopic Fragment Resection for Capitellar Osteochondritis Dissecans in Adolescent Athletes: 5- to 12-Year Follow-up.

Orthop J Sports Med 2017 Dec 15;5(12):2325967117744537. Epub 2017 Dec 15.

Sports Medicine and Joint Center, Funabashi Orthopaedic Hospital, Funabashi, Japan.

Background: Capitellar osteochondritis dissecans (OCD) in skeletally immature athletes has often been seen in baseball players and gymnasts. The choice of surgical procedure for unstable lesions in skeletally immature athletes remains controversial.

Purpose: To investigate functional outcomes and radiographic changes in the midterm to long-term postoperative period after arthroscopic (AS) resection for small to large capitellar OCD lesions in skeletally immature athletes.

Study Design: Case series; Level of evidence, 4.

Methods: A total of 38 elbows in 38 patients (33 boys, 5 girls; mean age, 14 years [range, 13-15 years]) with skeletally immature elbows underwent AS resection for capitellar OCD. Patients were observed for at least 5 years (mean, 8 years [range, 5-12 years]). Elbows with a lesion width that did not exceed one-half of the radial head diameter were assigned to group 1 (n = 17 elbows), and larger lesions were assigned to group 2 (n = 21 elbows). Functional scores, patient satisfaction, range of motion (ROM), and osteoarthritis (OA) grades were evaluated between the groups.

Results: All patients returned to sports activity. Functional scores at the final follow-up were not significantly different between the groups. Patient satisfaction scores were significantly higher in group 1 than in group 2. There was significant improvement in flexion ROM at the final follow-up compared with preoperative values in group 1 ( = .017), and there was a significant between-group difference (group 1: 141°; group 2: 133°; = .002). Extension ROM showed significant improvement in both groups (group 1: from -8° to 3°; group 2: from -17° to -1°; < .001 for both). Group 1 tended to have better extension than group 2, but the difference was not significant. There were no elbows with severe OA in either group, but the OA grade progressed in 5 elbows (29%) in group 1 and 9 elbows (43%) in group 2, and this rate of OA progression was statistically significant between groups ( = .005).

Conclusion: Both functional outcomes and radiological findings after AS fragment resection were excellent in elbows with small lesions. Although overall outcomes were acceptable in elbows with larger lesions, flexion ROM and patient satisfaction scores were significantly inferior to those in elbows with smaller lesions.
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http://dx.doi.org/10.1177/2325967117744537DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5734470PMC
December 2017

Geometric Analysis of the Proximal Humerus in Elderly Japanese Patients: Implications for Implant Selection in Reverse Shoulder Arthroplasty.

Orthopedics 2017 May 15;40(3):e485-e490. Epub 2017 Mar 15.

The implants used in reverse shoulder arthroplasty were originally designed for white patients; thus, they might not be optimal for smaller Asian patients. The selection of reverse shoulder arthroplasty systems is limited in Japan. The purpose of this study was to measure the geometry of the proximal humerus in elderly Japanese patients to inform implant selection according to humerus size. This study included 155 shoulders from 148 patients 50 years or older who underwent computed tomography for shoulder disorders other than arthritis and trauma. There were 67 male and 81 female patients with mean ages of 68 and 66 years, respectively. The humeral head diameter, head height, neck-shaft angle, neck diameters, and osteotomy diameters for 155° inclination implants were measured using surface models created from computed tomography scans. The mean diameter of head curvature, humeral head height, and neck-shaft angle were 48.2 mm, 19.8 mm, and 136° for male patients and 42.4 mm, 17.1 mm, and 136° for female patients, respectively. The mean mediolateral and anteroposterior neck diameters were 46.9 mm and 43.7 mm for men and 41.6 mm and 38.4 mm for women, respectively. The mean mediolateral and anteroposterior osteotomy diameters were 42.2 mm and 41.2 mm for male patients and 38.6 mm and 36.7 mm for female patients, respectively. There were significant differences between the sexes in all measurements except neck-shaft angle. Humeral implants with 155° inclination will not fit the humerus of smaller Japanese women. Thus, implants with anatomical inclination and an onlay humeral tray may be a better choice for smaller patients. [Orthopedics. 2017; 40(3):e485-e490.].
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http://dx.doi.org/10.3928/01477447-20170308-03DOI Listing
May 2017

Differences in fatty degeneration of rotator cuff muscles at different sites, as quantified by T2 mapping.

J Orthop Sci 2017 Mar 10;22(2):281-284. Epub 2016 Dec 10.

Department of Orthopaedic Surgery, Eastern Chiba Medical Center, 3-6-2 Okayamadai, Togane, Chiba, 2838686, Japan.

Background: Fatty degeneration of the cuff muscles is usually evaluated at the Y-view in oblique sagittal images. It was recently proposed that muscle shift after repair may influence the fatty degeneration values, and the evaluation of the muscles at a more medial site was recommended. However, the differences in muscle quality in accord with measurement sites have been unclear. Here we evaluated differences in fatty degeneration of the rotator cuff muscles measured quantitatively at different sites, using T2 mapping.

Methods: We assessed 702 shoulders of 675 patients (335 males, 340 females; mean age, 62 years) who underwent MRI including T2 mapping. There were 345 shoulders without rotator cuff tears and 357 shoulders with tears: partial tear = 103 shoulders; small = 63; medium = 94; large = 71; massive = 26. T2 values of the supraspinatus and infraspinatus muscles were measured on the Y-view and on the image that was 15 mm medial to the Y-view.

Results: The T2 values at the medial site increased with the tear extent, as did those on the Y-view. There were no significant differences in supraspinatus T2 values between those on the Y-view and at the medial site in all tear size groups except medium and large tears (p = 0.008 and p < 0.001, respectively). There were also no significant differences in infraspinatus T2 values between the two sites in all tear size groups except large tears (p = 0.002). However, the differences were relatively small (2.4-5.6 ms), which were within the standard deviations of the measurements.

Conclusions: The T2 values of the supraspinatus and infraspinatus muscles on the Y-view and at 15 mm medial to it were almost identical, with the exception of small differences in the case of larger tears.
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http://dx.doi.org/10.1016/j.jos.2016.11.016DOI Listing
March 2017

Progression of degenerative changes of the biceps tendon after successful rotator cuff repair.

J Shoulder Elbow Surg 2017 Mar 30;26(3):424-429. Epub 2016 Nov 30.

Shoulder and Elbow Center, Funabashi Orthopaedic Hospital, Funabashi, Japan.

Background: This study investigated the morphologic changes in the biceps tendon using ultrasonography before and after successful arthroscopic posterosuperior rotator cuff repair.

Methods: Forty-four patients (44 shoulders) underwent arthroscopic posterosuperior rotator cuff repair with 1-year postoperative magnetic resonance imaging (MRI) follow-up. The patients comprised 22 men and 22 women with an average age of 61 years. The cross-sectional area (CSA) of the biceps tendon in the bicipital groove was measured, and the vascularity in the bicipital groove was graded as 0 to 3, based on the signal density of the anterior circumflex artery, using power Doppler ultrasonography. The preoperative and postoperative CSA and vascularity grades were compared. The pain score on the University of California, Los Angeles Shoulder Rating Scale was used to analyze the correlation between vascularity and postoperative pain.

Results: The average preoperative and postoperative CSA of the biceps tendon was 15.4 ± 6.5 and 17.9 ± 7.5 mm, respectively. The postoperative CSA was significantly larger than the preoperative CSA (P < .01). Although no significant difference in the vascularity of the bicipital groove was observed between preoperative and postoperative grading, a negative correlation was observed between the vascularity and postoperative pain score on the University of California, Los Angeles scale (r = -0.369).

Conclusions: The biceps tendon in the bicipital groove becomes thicker over time, even after successful posterosuperior rotator cuff repair. In addition, an increase in the vascularity around the biceps tendon in the groove is correlated with pain symptoms after successful repair.
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http://dx.doi.org/10.1016/j.jse.2016.09.052DOI Listing
March 2017

Clinical Outcome and Glenoid Morphology After Arthroscopic Repair of Chronic Osseous Bankart Lesions: A Five to Eight-Year Follow-up Study.

J Bone Joint Surg Am 2015 Nov;97(22):1833-43

Ichikawa Clinic, Funabashi Orthopaedic Hospital, 1-10-1-206 Ichikawa-minami, Ichikawa 2720033, Japan. E-mail address:

Background: Arthroscopic osseous Bankart repair for shoulders with chronic recurrent anterior instability has been reported as an effective procedure with promising short-term outcomes. However, to date, we know of no report describing longer-term outcomes and glenoid morphologic change. The purpose of the present study was to report intermediate to long-term outcomes and glenoid morphologic change after arthroscopic osseous Bankart repair in patients with substantial glenoid bone loss.

Methods: A consecutive series of eighty-five patients with traumatic anterior glenohumeral instability associated with a chronic osseous Bankart lesion underwent arthroscopic repair from January 2005 through December 2006. Forty-six patients with bone loss of >15% of the inferior glenoid diameter relative to the assumed inferior circle regardless of the fragment size were selected as candidates for this study. Thirty-eight patients (83%), including thirty-four male and four female patients, with a mean age of 23.4 years (range, fifteen to thirty-six years) at the time of surgery, were available for final follow-up at a mean of 6.2 years (range, 5.0 to 8.1 years) after surgery.

Results: One patient had a redislocation during a traffic accident five months after surgery before obtaining an osseous union. The mean Rowe score and the mean Western Ontario Shoulder Instability Index improved significantly from 30.7 points preoperatively to 95.4 points postoperatively and from 26.5% to 81.5%, respectively. Although the mean preoperative fragment size was measured as only 4.7%, the mean glenoid bone loss improved from 20.4% preoperatively to -1.1% postoperatively.

Conclusions: Arthroscopic osseous Bankart repair is an effective primary treatment for shoulders with substantial glenoid bone loss as it provides successful outcomes without recurrence of instability once osseous union is obtained. Glenoid morphology can be normalized during the intermediate to long-term postoperative period, even in shoulders with a smaller fragment.
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http://dx.doi.org/10.2106/JBJS.N.01033DOI Listing
November 2015

Rotator Cuff Lesions in Patients with Stiff Shoulders: A Prospective Analysis of 379 Shoulders.

J Bone Joint Surg Am 2015 Aug;97(15):1233-7

Shoulder & Elbow Center, Funabashi Orthopaedic Hospital, 1-833 Hazama, Funabashi, Chiba 2740822, Japan. E-mail address for H. Sugaya:

Background: Idiopathic adhesive capsulitis is defined as a frozen shoulder with severe and global range-of-motion loss of unknown etiology. The purpose of our study was to clarify the prevalence of rotator cuff lesions according to patterns and severity of range-of-motion loss in a large cohort of patients with stiff shoulders.

Methods: Rotator cuff pathology was prospectively investigated with use of magnetic resonance imaging (MRI) or ultrasonography in a series of 379 stiff shoulders; patients with traumatic etiology, diabetes, or radiographic abnormalities were excluded. Eighty-nine shoulders demonstrated severe and global loss of passive motion (≤100° of forward flexion, ≤10° of external rotation with the arm at the side, and internal rotation not more cephalad than the L5 level) and were classified as having severe and global loss of motion (Group 1). The remaining 290 shoulders were divided into two groups: those with severe but not global loss (Group 2; 111 shoulders) and mild to moderate limitation (Group 3; 179 shoulders).

Results: Among all shoulders, imaging demonstrated an intact rotator cuff in 51%, a full-thickness tear in 35%, and a partial-thickness tear in 15%. In Group 1, 91% had an intact rotator cuff and 9% had a partial-thickness rotator cuff tear. No patient in this group demonstrated a full-thickness tear. In Group 2 and Group 3, respectively, 44% and 35% of the shoulders were intact, 17% and 16% had a partial-thickness tear, and 39% and 50% had a full-thickness tear.

Conclusions: Shoulder stiffness with severe and global loss of passive range of motion is not associated with full-thickness rotator cuff tears, although some patients may have a partial-thickness tear. Shoulders with severe and global loss of range of motion at a first visit are likely to be cases of idiopathic adhesive capsulitis and may not require further imaging studies.
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http://dx.doi.org/10.2106/JBJS.N.00910DOI Listing
August 2015