Factors affecting stress shielding and osteolysis after reverse shoulder arthroplasty: A multicenter study in a Japanese population.

BACKGROUND: Stress shielding and osteolysis around the humeral stem after reverse shoulder arthroplasty causes loosening and periprosthetic fractures and reduces bone stock during revision surgery. In Japanese patients, who have relatively small bodies, different characteristics may exist regarding the occurrence of these changes compared with the characteristics of Westerners, who have relatively larger frames. The purpose of this multicenter study was to investigate the incidence and clarify the predictors of stress shielding and osteolysis in Japanese individuals who underwent reverse shoulder arthroplasty. METHODS: The occurrence of stress shielding and osteolysis was investigated in 135 shoulders that had undergone reverse shoulder arthroplasty at least 2 years prior in five Japanese hospitals. During post-surgical follow-up, which was conducted every 3 months, the locations of the stress shielding occurrences, such as cortical thinning and osteopenia (which primarily occurred in zones 1, 2, and 7, where 1 is the greater tuberosity and 7 is the calcar part), spot weld, and condensation lines, were recorded. Cases without any abnormal findings on radiographs obtained up to ≥2 years after surgery were regarded as having no abnormalities. Finally, the predictors of cortical thinning and proximal humeral osteolysis were assessed using univariate and multivariate regression analyses. RESULTS: Cortical thinning and osteopenia occurred in 68 shoulders, a condensation line occurred in 37 shoulders, and spot weld occurred in 23 shoulders. In particular, greater tuberosity and calcar osteolysis occurred in 40 and 47 shoulders, respectively. Long stem, cementless stem, and a larger proximal filling ratio were independent predictors of cortical thinning and osteopenia, whereas a cementless stem, larger metaphysis diameter, and a larger proximal filling ratio were associated with proximal humeral osteolysis. CONCLUSIONS: The predictors of stress shielding and osteolysis included the use of long stems, cementless stems, larger proximal filling ratios, and larger metaphysis diameters. LEVEL OF EVIDENCE: retrospective comparative study (Level III).

Long-term conservative treatment outcomes for midshaft clavicle fractures: a 10-to-30-year follow-up.

BACKGROUND: Few reports exist on the long-term outcomes of midshaft clavicle fracture conservative treatments. Therefore, this study investigated the long-term outcome of this treatment in patients with midshaft clavicle fractures. METHODS: Patients were treated conservatively for midshaft clavicle fractures with a figure-of-eight bandage between 10 and 30 years ago. Subsequently, a telephone survey was used to follow-up these patients, and 38 were successfully evaluated. The mean term after trauma was 17.0 years. Afterward, the American Shoulder and Elbow Surgeons Shoulder (ASES) score and Shoulder pain and disability index (SPADI) on the affected and unaffected sides were calculated based on the filled questionnaires. We defined patients whose ASES and SPADI on the affected side were worse than the unaffected side as the symptomatic group. Furthermore, plain radiographs measured proportional changes in clavicular length and displacement. RESULTS: The ASES scores of the affected side were significantly lower than those of the unaffected side, and the SPADI of the affected side was significantly higher than that of the unaffected side. Furthermore, the symptomatic group's proportional changes in clavicular length and displacement were significantly larger than the asymptomatic group. CONCLUSION: The affected shoulder side was more symptomatic than the unaffected side 10 to 30 years after the trauma when midshaft clavicle fractures were treated conservatively. Moreover, several patients became symptomatic for fractures with a larger proportional change in clavicular length or displacement.

Return to sports after arthroscopic Bankart repair in teenage athletes: a retrospective cohort study.

BACKGROUND: Anterior shoulder instability is frequent among young athletes. Surgical treatment for this injury aims to facilitate an early return to sports (RTS). However, the rate of recurrent instability after surgery is reportedly high among young patients, and it is unclear whether surgery ensures satisfactory RTS. The purpose of this study was to verify the clinical outcomes and RTS after arthroscopic Bankart repair in competitive teenage athletes without critical bone loss in the glenoid. METHODS: We retrospectively reviewed competitive teenage athletes who underwent arthroscopic Bankart repair. Patients with large bony defects in the glenoid, larger than 20% of the healthy side, were excluded. Clinical outcomes, recurrent instability, the final level of RTS, and the time needed for RTS were analyzed. RESULTS: In total, 50 patients with a mean follow-up period of 44.5 ± 19.6 (range, 24-85 months) months were included. The mean age at surgery was 16.8 ± 1.7 (range, 13-19 years) years. Two patients (4.0%) experienced recurrent instability. All patients returned to sports, 96% of patients participated competitively, and 76% achieved a complete return to the pre-injury level without any complaints. The time for RTS was 6.6 ± 2.7 months (range, 3-18 months), to competitions was 9.3 ± 4.0 (range, 6-24 months) months, and to complete return was 10.6 ± 4.3 (range, 8-24 months) months. The complete return rates varied by sports type, with 82% in contact athletes, 59% in dominant-hand overhead athletes, and 100% in other athletes (P = 0.026). Other preoperative factors or concomitant lesion such as bony Bankart, superior labrum tear, or humeral avulsion of glenohumeral ligament lesion did not affect the complete RTS. CONCLUSION: Arthroscopic Bankart repair is an effective surgical procedure for anterior shoulder instability, even among competitive teenage athletes. Sports type was the only factor associated with complete RTS after surgery.

Clinical outcomes and tendon lengthening after arthroscopic rotator cuff repair.

BACKGROUND: There is a phenomenon in which the tendon appears to increase the length after rotator cuff repair. However, it is unclear in which cases tendon lengthening occurs and how the degree of lengthening affects the surgical outcome. This study aimed to evaluate preoperative and postoperative musculotendinous junction (MTJ) and tendon length on magnetic resonance imaging and assess the postoperative tendon lengthening and its impact on postoperative outcomes. METHODS: We reviewed 109 patients with good repair integrity after arthroscopic rotator cuff repair. Patients whose supraspinatus tendons were simply pulled out laterally without any additional procedures were included. They underwent serial magnetic resonance imaging before surgery and at 3, 6, and 24 months after surgery. The location of the MTJ in relation to the line of the glenoid fossa and the supraspinatus tendon length were measured. Clinical evaluation was conducted 2 years after surgery, including the range of shoulder motion, shoulder strength index (affected/unaffected strength), Constant score, University of California, Los Angeles score, and pain numeric rating scale. The characteristics of the preoperative tendon, change in tendon length over time, amount of the lateral shift of MTJ location and tendon length, and impact of tendon lengthening on postoperative clinical outcomes were analyzed. RESULTS: The preoperative tendon retraction significantly correlated with the MTJ location (r = -0.75; P < .0001) and preoperative tendon length (r = -0.46; P < .0001). The tendon length at 3, 6, and 24 months after surgery was significantly longer than those before surgery (26.7 ± 5.8 mm, 27.9 ± 6.6 mm, 28.5 ± 5.6 mm, and 21.5 ± 5.1 mm, respectively). From before surgery to 24 months after surgery, the MTJ location moved 8.4 ± 8.6 mm laterally and the tendon length increased 7.0 ± 6.1 mm. A significant and weak negative correlation was found between tendon lengthening and the abduction strength index (r = -0.22; P = .03); however, no significant correlation with pain, range of shoulder motion, external rotation strength index, Constant score, and University of California, Los Angeles score was found. Multiple linear regression analysis also showed that tendon lengthening was only associated with the abduction strength index (standardized coefficient = -0.20, P = .03). CONCLUSIONS: Tendon lengthening and lateral shift of MTJ location were observed after arthroscopic rotator cuff repair, and they correlated with preoperative tendon retraction. Although the amount of tendon lengthening had negative weak correlation with abduction strength index, it did not affect other postoperative outcomes.

Range of Motion and Muscle Strength Changes in Japanese Professional Pitchers During the Baseball Season.

BACKGROUND: There are no studies examining changes in the physical function throughout the baseball season in Japanese professional players. We examined the range of motion (ROM) and muscle strength changes in professional baseball pitchers as the season progresses. MATERIALS AND METHODS: Five professional baseball pitchers were included. ROM, flexibility, and muscle strength of the trunk and shoulder, elbow, hip, knee, and ankle joints were measured pre-season (PRE), mid-season (MID), and post-season (POST). RESULTS: The total shoulder arc ROM of the dominant sides significantly decreased compared to that of the nondominant sides at MID and POST. Shoulder abduction muscle strength of the dominant sides significantly decreased at POST compared to that at PRE. In the trunk, lateral flexion ROM of bilateral sides significantly decreased at MID and POST compared to that at PRE, and the duration time of the side bridge test of the dominant sides significantly decreased at POST to that at PRE. Hip extension ROM and muscle strength and internal rotation ROM of the push-off leg significantly decreased at POST compared to that at PRE. CONCLUSION: The total shoulder arc ROM and shoulder abductor muscle strength of the dominant sides, trunk lateral flexion ROM and muscle strength, push-off leg hip joint extension muscle strength and ROM, and internal rotation ROM were more susceptible to changes as the season progressed. In order to maintain performance and prevent a throwing disorder, it is necessary to focus on these movements during the season and to appropriately train and condition these muscle groups.

Prevalence of Rotator Cuff Tears Among Older Tennis Players and Its Impact on Clinical Findings and Shoulder Function.

CONTEXT: Tennis is a noncontact sport playable at an individual's own pace. Thus, it is popular among the older adults. It is known that older adults often suffer from rotator cuff tears (RCTs), which may affect tennis activity. However, the prevalence and influence of RCTs on tennis play among older players are not well-known. This study aimed to evaluate the prevalence of RCTs in older tennis players and its impact on physical findings and shoulder function. DESIGN: A cross-sectional study. METHODS: Fifty-three tennis players (mean age: 70.7 y; range: 60-83 y) participating in a recreational-level tennis tournament were examined in this study. An ultrasonographic examination of both shoulders was performed to detect RCTs. Relationships between RCTs of the dominant shoulder and clinical findings, shoulder pain, and shoulder function including range of motion, shoulder strength, and Single Assessment Numeric Evaluation score, and Disability of the Arm, Shoulder and Hand-Sports Module score were assessed. RESULTS: RCTs were detected in 19 (36%) dominant shoulders and 6 (11%) nondominant shoulders. Asymptomatic RCTs were detected in 11 (58%) dominant shoulders and 5 (83%) nondominant shoulders. Increased crepitus and more positive results in the empty can test, and infraspinatus test were observed in the dominant shoulders with RCTs than in those without; however, there was no difference in shoulder pain, range of motion; strength; Single Assessment Numeric Evaluation score; and Disability of the Arm, Shoulder and Hand-Sports Module score between the players with and without RCTs. CONCLUSIONS: One-third of the older tennis players in this study had RCTs in the dominant shoulder with some positive physical sign of an RCT. However, shoulder pain and shoulder function did not differ between the players with and without RCTs, suggesting that RCTs had a minor impact on the tennis performance in the participants of this study.

Evaluation of subscapularis tendon tears of the anterosuperior aspect using radial-sequence magnetic resonance imaging.

BACKGROUND: Magnetic resonance imaging (MRI) is widely used to diagnose subscapularis tendon tears; however, it is difficult to assess the anterosuperior aspect of these tears. Radial-sequence MRI can reveal the fiber components of the anterosuperior aspect, from perpendicular, by overcoming the partial volume effect. We aimed to classify the insertion of subscapularis tendon tears on radial-sequence MRI and determine the effectiveness of radial-sequence MRI for subscapularis tendon tear assessments. METHODS: We retrospectively investigated 196 patients (mean age, 66.7 ± 9.0 years; 118 men, 78 women) who underwent 1.5 T MRI before arthroscopic rotator cuff repair. Radial-sequence MRI findings of the anterosuperior aspect insertion of the subscapularis tendon were classified into five grades, and intraoperative findings compared with preoperative conventional MRI and radial-sequence MRI. We calculated sensitivity, specificity, accuracy, and positive and negative predictive values. Interobserver and intraobserver reliability for radial-sequence MRI classification was calculated using kappa (κ). RESULTS: Conventional MRI sensitivity of subscapularis tendon tears was 45.3%; specificity, 95.8%; accuracy, 82.1%; positive predictive value, 80.0%; and negative predictive value, 82.5%. Radial-sequence MRI sensitivity was 92.5%; specificity, 88.1%; accuracy, 89.3%; positive predictive value, 74.2%; and negative predictive value, 96.9%. Sensitivity (P < .001), accuracy (P = .04), specificity (P = .02), and negative predictive values (P < .001) in radial-sequence MRI were significantly higher than those in conventional MRI. Intraobserver and interobserver reliabilities for radial-sequence MRI classification were κ = 0.78 and 0.65, respectively, corresponding to high reproducibility, and defined as good. CONCLUSION: We provide evidence that radial-sequence MRI is an effective tool to evaluate subscapularis tendon tears, especially before surgery.

Return to sports after arthroscopic bankart repair on the dominant shoulder in overhead athletes.

BACKGROUND: Arthroscopic Bankart repair (ABR) yields good results in young athletes with anterior shoulder instability. However, the treatment for overhead athletes is challenging because recovery of range of motion is necessary for return to play and repeated shoulder motion may lead to recurrent instability. The aim of this study was to investigate the clinical outcomes and return to sports after ABR on the dominant shoulder in overhead athletes. METHODS: This study included 24 competitive level overhead athletes who underwent ABR on their dominant shoulders. The mean age at surgery was 17.6 years, and the mean follow-up was 39.7 months. The range of bilateral shoulder motion, the Rowe score, the Japanese Shoulder Society Shoulder Instability Score (JSS-SIS), and the Japanese Shoulder Society Shoulder Sports Score (JSS-SSS) were evaluated before the surgery and at the final visit. Recurrent instability, the final level of return to sports, and the duration before returning to sports were confirmed, as well as the pre-, intra- and postoperative factors, which prohibited complete return to play. RESULTS: There were no cases of recurrent instability. The Rowe score, JSS-SIS, JSS-SSS, and the range of flexion, abduction, internal rotation significantly improved postoperatively. Fifteen athletes (62.5%) returned to the same or superior levels without any complaint in their shoulders. The mean duration needed for a complete return was 13.3 months. The postoperative external rotation deficit in abduction was larger in the athletes who returned incompletely than those who returned completely, 7.8° and 2.3°, respectively. CONCLUSIONS: ABR is a reliable surgery for preventing recurrent instability in overhead athletes, however the rate of a complete return to preinjury level was low and a long duration was needed for complete return to play. The postoperative external rotation may be necessary for a complete return to overhead sports. LEVEL OF EVIDENCE: Level IV: Retrospective Case Series.

Shoulder ranges of motion and humeral torsions of injured baseball players have different characteristics depending on their pitching sides.

BACKGROUND: Right- and left-side throwers in baseball may have different shoulder conditions and throwing biomechanics. This study aimed to compare the passive range of motion, humeral torsion, and clinical findings between right- and left-handed throwers who sustained throwing shoulder injuries and confirm the differences in the characteristics between throwing sides. METHODS: A total of 52 pitchers diagnosed with throwing shoulder injuries were included in this study: 27 patients were right-side throwers (R group), and 25 were left-side throwers (L group). We measured the bilateral passive external and internal rotation angles in abduction position (ABIR) and total arc at their first visit. To assess posterior shoulder tightness, the internal rotation angles in forward flexion (FIR), and the abduction angle (AA) and horizontal flexion angle (HFA) without scapula motion were measured. The bilateral humeral torsion angles were also measured using ultrasonography. These values were compared between the participants' throwing and non-throwing sides and between the R and L groups' throwing sides. Furthermore, several physical findings in the shoulders were assessed, and the positive ratio was compared between the R and L groups. RESULTS: On comparing the throwing and non-throwing sides, the R group had significantly greater external rotation angles in the abduction position and humeral torsion angle, and smaller ABIR, total arc, FIR, AA, and HFA in the throwing side, while the L group showed no significant differences, except for a smaller ABIR and larger HFA in the throwing side. On comparing the throwing side between the R and L groups, the R group had a smaller FIR, AA, and FHA than the L group. Regarding the physical findings, the posterior jerk test, Kim test, anterior and posterior drawer sign, sulcus sign, and scapular winging in the L group were significantly more positive than in the R group. CONCLUSION: The range of motion and humeral torsions differed between the left- and right-side throwers, as did the pathology between their throwing sides. Clinicians should consider the possibility that the pathological condition differs between left- and right-side throwers.

Effectiveness of measuring tension during arthroscopic rotator cuff repair.

PURPOSE: Arthroscopic rotator cuff repair (ARCR) for relatively small rotator cuff tears (RCTs) has shown promising results; however, such surgery for larger tears often results in failure and poor clinical outcomes. One cause of failure is over-tension at the repair site that will be covered with the tendon stump. Reports on the clinical outcomes using ARCR with tension ≤ 30 N are lacking. This study aimed to evaluate ARCR outcomes and failure rates using less tension (30 N) and to assess the prognostic factors for failure. METHODS: Our study group comprised of 118 patients who underwent ARCR for full-thickness RCTs with full tendon stump coverage of the footprint with a tension of ≤ 30 N, measured using a tension meter; no additional procedures, such as margin convergence or footprint medialisation, were performed. The failure rate was calculated, and the prognostic factor for failure was assessed using multivariate regression analyses. RESULTS: There were seven cases of failure in the study group. Postoperatively, flexion and internal rotation ranges of motion, acromiohumeral interval, muscle strength, and clinical results improved significantly. Using multivariate regression analyses, intraoperative concomitant subscapularis tendon lesion and pre-operative infraspinatus tendon retraction, assessed using radial-sequence magnetic resonance imaging, were significantly correlated with post-ARCR failure using less tension (p = 0.030 and p = 0.031, respectively). CONCLUSION: ARCR is likely to succeed for RCTs that can be extracted using tension ≤ 30 N. However, cases with more severe subscapularis tendon lesions and those with high infraspinatus tendon retraction may show surgical failure. LEVEL OF EVIDENCE: LEVEL IV Retrospective case series.

Arthroscopic Rotator Cuff Repair With Muscle Advancement and Artificial Biodegradable Sheet Reinforcement for Massive Rotator Cuff Tears.

BACKGROUND: Because high failure rates have frequently been reported after arthroscopic rotator cuff repair (ARCR) of massive rotator cuff tears (mRCTs), we introduced the technique of ARCR with supraspinatus and infraspinatus muscle advancement (MA). However, for cases where the original footprint cannot be completely covered, additional surgery using an approved artificial biomaterial is performed. PURPOSE: To investigate the postoperative clinical outcomes and failure rate after MA-ARCR, with and without our reinforcement technique. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 74 patients (mean ± SD age, 68.7 ± 7.7 years) diagnosed with mRCT with a minimum postoperative follow-up of 2 years were included in the current study. Of these patients, 47 underwent MA-ARCR with polyglycolic acid (PGA) sheet reinforcement (study group), and 27 patients underwent MA-ARCR alone (control group). PGA reinforcement was performed when full coverage of the footprint could not be achieved by MA alone, but where the latter was possible, reinforcement was not required. Thus, the study group had significantly worse muscle quality than the control group (P < .05). The pre- and postoperative range of motion (ROM), isometric muscle strength, acromiohumeral interval, and clinical outcomes were evaluated and compared between these 2 groups. Cuff integrity during the last follow-up period was assessed with magnetic resonance imaging, and the failure rate was calculated. In addition, the postoperative foreign body reaction was investigated in the study group. RESULTS: In both groups, significant postoperative improvements were seen in acromiohumeral interval, clinical scores, ROM in anterior flexion, and isometric muscle strength in abduction, external rotation, and internal rotation (P < .001 for all). The failure rate of the study group was 12.8% (6 patients) and that of the control group was 25.9% (7 patients). No significant differences were noted between the 2 groups on any of the data findings, even regarding the failure rate. Foreign body reactions in the early period were found in 3 patients, although these spontaneously disappeared within 3 months. CONCLUSION: Patients who underwent PGA patch reinforcement for MA-ARCR when the footprint could not be completely covered had clinical results similar to isolated MA-ARCR when the footprint could be covered. Both procedures resulted in significant improvement in symptoms and function compared with preoperatively.

Factors associated with pain in nonsurgically treated rotator cuff tears -A study with magnetic resonance imaging.

BACKGROUND: In rotator cuff tears, some cases become asymptomatic with nonsurgical treatment, others remain symptomatic. The purpose of this study was to identify factors associated with pain in nonsurgically treated rotator cuff tears using magnetic resonance imaging (MRI). METHODS: In total, 108 shoulders diagnosed with supraspinatus (SSP) tendon tears using MRI were nonsurgically treated, and MRI was repeated after more than a year. The patients were divided into pain or improvement group according to whether the pain persisted or disappeared. Bursal fluid accumulation; SSP tendon retraction; subscapularis (SSC) tendon tears; infraspinatus (ISP) tendon tears; and Goutallier classification into SSC, SSP, and ISP were included as evaluation factors. Predictive factors for persistent pain on initial MRI and factors associated with persisting pain after nonsurgical treatment on repeat MRI were statistically analyzed using multivariate logistic regression analysis. RESULTS: The improvement group showed a significant decrease in bursal fluid accumulation compared with the pain group (p < 0.01). SSC tendon tears (OR, 4.42; 95% CI, 1.16-16.9; P = 0.03) on initial MRI were significantly associated with persistent pain. Bursal fluid accumulation (OR, 2.44; 95% CI, 1.18-5.07; P = 0.02) and SSC tendon tears (OR, 2.25; 95% CI, 1.15-4.39; P = 0.02) on repeat MRI were significantly associated with persistent pain. CONCLUSIONS: Bursal fluid accumulation decreased when pain improved. The involvement of SSC tendon tears can serve as a predictive factor for persistent pain. Pain may persist although patients with rotator cuff tears including SSC tendon tears are nonsurgically treated. LEVEL OF EVIDENCE: Level IV case-control study.

Outcomes of arthroscopic rotator cuff repair with muscle advancement for massive rotator cuff tears.

BACKGROUND: We performed arthroscopic rotator cuff repair (ARCR) combined with miniopen supraspinatus and infraspinatus muscle advancement for massive rotator cuff tears (RCTs) to decrease tension at the repair site with the goal of reduction of the failure rate. We evaluated the clinical outcomes and failure rate after this procedure. METHODS: This study included 47 patients diagnosed with chronic massive RCTs between October 2010 and March 2015. Of these patients, 21 underwent transosseous equivalent (TOE) ARCR only (control group), and 26 underwent TOE ARCR with muscle advancement (study group). We evaluated shoulder clinical outcomes at preoperative and postoperative assessments and also measured muscle strength and the acromiohumeral interval (AHI) at the same time in both groups. Failure rates were calculated in both groups by evaluating the cuff integrity with postoperative magnetic resonance imaging. RESULTS: Although there was statistically significant improvement for the mean clinical scores in the both groups, there were no significant differences between the 2 groups. The postoperative abduction muscle strength and AHI were significantly higher in the study group (46.3 ± 20.6 N and 9.4 ± 2.9 mm; P = .04) than in the control group (34.6 ± 20.0 N and 7.7 ± 3.0 mm; P = .04). The failure rates were significantly lower in the study group than in the control group (23.1% and 52.4%; P = .03). CONCLUSION: The TOE ARCR with muscle advancement can achieve significantly better abduction muscle strength, wider AHI, and lower failure rates for massive RCTs than the normal TOE ARCR.

Bone mineralization changes of the glenoid in shoulders with symptomatic rotator cuff tear.

PURPOSE: Computed tomography osteoabsorptiometry (CTO) is a method to analyze the stress distribution in joints by measuring the subchondral bone density. The purpose of this study was to evaluate the bone mineralization changes of the glenoid in shoulders with rotator cuff tears by CTO and to evaluate whether rotator cuff tears are associated with stress changes in the glenoid. METHODS: In total, 32 patients, who were diagnosed with unilateral rotator cuff tears and underwent arthroscopic rotator cuff repair, were enrolled in this study. They underwent CT scanning of both shoulders pre-operatively and the glenoid was evaluated using CTO. Hounsfield units (HU) in seven areas of the glenoid were compared between the affected and unaffected sides. RESULTS: The central area of the glenoid on the affected side had significantly lower HU than on the unaffected side among all patients. Focusing on the rotator cuff tear size and the subscapularis tendon, only patients with larger cuff tears or with subscapularis tendon tears showed significantly lower HU in the central area of the affected side. CONCLUSIONS: This study showed a decrease in bone mineralization density in the central glenoid in shoulders with rotator cuff tear. This change was observed in the case of larger cuff tears and subscapularis tendon tears. Our results help clarify the changes in stress distribution in the shoulder joint caused by symptomatic rotator cuff tears.

The prospective evaluation of changes in fatty infiltration and shoulder strength in nonsurgically treated rotator cuff tears.

BACKGROUND: The purpose of this study was to evaluate the relationship of fatty infiltration in rotator cuff muscles and shoulder strength in rotator cuff tears and these changes during nonsurgical treatment. METHODS: Fifty-three shoulders from 47 patients (mean age: 69.9 years) diagnosed with rotator cuff tears by magnetic resonance imaging (MRI) were treated nonsurgically. The degrees of fatty infiltration in supraspinatus (SSP) and infraspinatus (ISP) muscles were graded by the modified Goutallier classification (grade 0-1, grade 2-3, or grade 4). The isometric strength of the abductors (Abd) and external rotators (ER) were examined with a hand dynamometer. We analyzed the correlation of the modified Goutallier classification in SSP and ISP muscles with the strength of Abd and ER at initial visit. In addition, MRI and strength tests were repeated after 24 ± 6 months, and changes in fatty infiltration and strength were examined. RESULTS: Fatty infiltration of SSP and ISP muscles had a negative correlation with the strengths of Abd and ER at initial visit, respectively. Six of 45 shoulders (SSP grade: 0-3) and 7 of 43 shoulders (ISP grade: 0-3) had progression of fatty infiltration. Predictive factor of a progression of fatty infiltration during follow-up was decreased initial strength of Abd. There was no significant change in the strength of Abd, and the strength of ER showed significant improvement between the initial and post-treatment measurements. Even in the subgroup that had progression of fatty infiltration at follow-up, the strength of Abd and ER did not decrease significantly. CONCLUSIONS: Although fatty infiltration of the rotator cuff muscles exhibited a negative correlation with muscle strength, fatty infiltration and muscle weakness did not progress at the same rate.

Monitoring of progression of nonsurgically treated rotator cuff tears by magnetic resonance imaging.

BACKGROUND: Nonsurgically treated rotator cuff tears sometimes become irreparable in the lead up to surgical repair. The purposes of our study were to identify predictive factors in the progression of tear size, and determine the changes in tear location. METHODS: Eighty shoulders from 71 patients (mean age 69.4 years) diagnosed with rotator cuff tears by MRI were treated nonsurgically. MRI was repeated after more than 1 year of initial diagnosis. Tear size was measured from the edge of the tear to the lateral aspect of the greater tuberosity. Tears were classified into 5 groups based on tear size and 4 groups based on tear location. Changes in tear size and location were examined. RESULTS: The mean follow-up period was 22.3 months. The average progression of tear size was 5 mm during follow-up, averaging 3 mm per year. Tears that were initially <1 or ≥4 cm were unlikely to progress in tear size. On the other hand, 1- to 2-cm tears on the initial MRI exhibited the greatest progression in tear size, followed by 2- to 3-cm tears. Furthermore, 62.5 % of localized tears in the posterior of the superior facet spread anteriorly, whereas 88.9 % of localized tears in the anterior of the superior facet did not change. CONCLUSIONS: Medium-sized tears are at high risk of tear progression. In contrast, there is little risk of early development of irreparable damage in partial tear or small full-thickness tears. In addition, typical tears may start in the posterior of the superior facet, and subsequently spread anteriorly. Our present findings may serve as a useful reference in determining the treatment course for rotator cuff tears. LEVEL OF EVIDENCE: Level IV, Case Series, Prognosis Study.

Rotator cuff regeneration using a bioabsorbable material with bone marrow-derived mesenchymal stem cells in a rabbit model.

BACKGROUND: Rotator cuff regeneration using tissue engineering techniques is a challenging treatment in elderly patients with irreparable rotator cuff tears. HYPOTHESIS: A polyglycolic acid sheet scaffold with seeded mesenchymal stem cells (MSCs) may enhance the expression of type I collagen products and increase the mechanical strength of the regenerated tendon in vivo. STUDY DESIGN: Controlled laboratory study. METHODS: A surgically created defect of infraspinatus tendons of rabbits was reconstructed with 2 different materials, a polyglycolic acid (PGA) sheet alone (PGA group) (n = 34) and a PGA sheet seeded with autologously cultured MSCs (MSC group) (n = 34). The authors created a tendon defect model without embedding any graft as the control model (control group) (n = 34). The rabbits were sacrificed at 4, 8, and 16 weeks after the operation and then were histologically evaluated. The rabbits were also biomechanically evaluated by measuring the ultimate failure loads and Young's modulus at 4 and 16 weeks following implantation. RESULTS: In the MSC group, the fibrocartilage layers and Sharpey fibers were found regularly in the insertion site at 8 weeks compared with the PGA group. In control group, thin membranes with many fibroblasts arranged in an irregular pattern linked the end of the torn cuff to the bone without any Sharpey fibers and type I collagen. A large volume of type I collagen was found in comparison with type III collagen at 16 weeks in the MSC group, whereas type III collagen was more prevalent than type I in the PGA group. The tendon maturing score in the MSC group had higher values than the PGA and control groups at 8 and 16 weeks (mean values were 21.0 ± 0.89, 24.0 ± 2.53 in the MSC group; 16.7 ± 2.25, 21.3 ± 2.42 in the PGA group; and 10.2 ± 0.98, 12.2 ± 1.72 in the control group, respectively) (P < .05). The results of the mechanical analysis revealed that the regenerated tendons in the MSC group had better tensile strength than in the PGA and control groups at 16 weeks (mean values were 3.04 ± 0.54 in the MSC group, 2.38 ± 0.63 in the PGA group, and 1.58 ± 0.13 in the control group) (P < .05). CONCLUSION: Bone marrow-derived MSCs were able to regenerate tendon-bone insertions and the tendon belly, including the production of type I collagen, and increased the mechanical strength of the regenerated rotator cuff tendon. CLINICAL RELEVANCE: Rotator cuff regeneration using MSCs is a promising treatment for massive rotator cuff defects.

Tendon-bone insertion repair and regeneration using polyglycolic acid sheet in the rabbit rotator cuff injury model.

BACKGROUND: The quality of tendons has considerable limitations regarding torn rotator cuff tendons. Tissue-engineering techniques using a biodegradable scaffold offer potential alternatives for recreating a valid tendon-to-bone interface. HYPOTHESIS: A polyglycolic acid (PGA) sheet could facilitate the regeneration of the rotator cuff tendon insertion in vivo. STUDY DESIGN: Controlled laboratory study. METHODS: An implant consisting of a PGA sheet, a rapidly absorbable material, was used to replace a completely resected infra-spinatus tendon insertion in 33 adult Japanese white rabbits. The contralateral infraspinatus tendon was replaced by poly-L-lactate-epsilon-caprolactone (PLC), a slowly absorbable material, by the same methods based on the results of the pilot study. Histological comparisons were made at 4, 8, and 16 weeks, and mechanical evaluations were performed at 4 and 16 weeks in both groups. Unrepaired defects were created in a control group. RESULTS: In the control group, the rotator cuff defects were covered with thin fibrous membranes with many fibroblasts arranged in an irregular pattern. In the PLC group, some chondrocytes were seen in the tendon insertion; however, these were not arranged along the long axis for a 16-week period. In the PGA group, a well-arranged fibrocartilage layer could be found in the regenerated tendon insertions; however, these tendon insertions were mainly regenerated by type III collagen. In mechanical examinations, the PGA group had significantly higher values in the maximum failure load, tensile strength, and Young's modulus for the 4-week and 16-week periods. These 3 categories statistically improved from 4 to 16 weeks postoperatively in both groups except for the Young's modulus in the PGA group (E = 5.66 at 4 weeks to 5.53 at 16 weeks). CONCLUSION: The PGA sheet scaffold material allows for tendon insertion regeneration with a fibrocartilage layer but displays mechanical properties inferior to those of the normal tendon in an animal model. CLINICAL RELEVANCE: The PGA sheet represent a possible alternative scaffold material for tendon regeneration in rotator cuff repair.

Arthroscopic autologous bone graft with arthroscopic Bankart repair for a large bony defect lesion caused by recurrent shoulder dislocation.

Many clinicians believe that a large bony defect of the glenoid must be treated with bone grafting when a Bankart procedure is performed. Various types of bone graft, such as open bone graft, Eden-Hybinnette, J-bone graft, coracoid transfer, and Latarjet, have been used. These require open procedures that are difficult to perform arthroscopically. We performed an arthroscopic autologous bone graft and an arthroscopic Bankart repair at the same time to treat a patient with recurrent dislocation of the shoulder joint and a large bony Bankart lesion. We harvested from the lateral site of the acromion 2 bones that were 2.7 mm in cylindrical diameter. We transplanted these bones to the large bony defect of the anteroinferior area of the glenoid and placed anchors between the 2 plugs. During the 30 months since the surgery was performed, the patient has not experienced dislocation or apprehension about the shoulder. A 3-dimensional computed tomography scan showed enlargement of the glenoid surface. Our surgical procedure offers promise for treatment of patients with recurrent dislocation of the shoulder joint and a large bony Bankart lesion because it allows the surgeon to alter the size and the grafted site of the cylindrical bone according to the size of the defect.

Augmentation of tendon attachment to porous ceramics by bone marrow stromal cells in a rabbit model.

Tendon attachment to interconnected porous calcium hydroxyapatite ceramics (IP-CHA) with cultured bone marrow stromal cells (BMSC) was analysed. The purpose of this study was to evaluate whether BMSC in IP-CHA could augment the tendon attachment to IP-CHA histologically and biomechanically. Eighteen Japanese white rabbits were used. Cultured BMSCs were subcultured in IP-CHA. The grafted tendon and IP-CHA with BMSC complex were implanted in a bone defect of the knee [BMSC(+) group]. In the contralateral knee, a tendon and IP-CHA without BMSC complex were implanted [BMSC(-) group]. Histological findings of the interface between the tendon and IP-CHA were similar in the two groups 3 weeks after the operation. However, 6 weeks after the operation, more abundant bone formation around the tendon was observed in the BMSC(+) group. The direct apposition of the tendon to bone in pores and collagen fibre continuity between the tendon and fibrous tissue in pores were observed. In biomechanical evaluation, the maximum pull-out load of the tendon from the IP-CHA in the BMSC(+) group was significantly higher than that in the BMSC(-) group 6 weeks after the operation. BMSCs cultured in IP-CHA could augment tendon attachment to IP-CHA.