Clinical and structural outcome twenty years after repair of isolated supraspinatus tendon tears

A novel 3D MRI-based approach for assessing supraspinatus muscle length

Rotator cuff (RC) tears are a common source of pain and decreased shoulder strength. Muscle length is known to affect muscle strength, and therefore evaluating changes in supraspinatus muscle length associated with RC pathology, surgical repair, and post-operative recovery may provide insights into functional deficits. Our objective was to develop a reliable MRI-based approach for assessing supraspinatus muscle length. Using a new semi-automated approach for identifying 3D location of the muscle-tendon junction (MTJ), supraspinatus muscle length was calculated as the sum of MTJ distance (distance between 3D MTJ position and glenoid plane) and supraspinatus fossa length (distance between root of the scapular spine and glenoid plane). Inter- and intra-operator reliability of this technique were assessed with intraclass correlation coefficient (ICC) and found to be excellent (ICCs > 0.96). Muscle lengths of 6 patients were determined before RC repair surgery and at 3- and 12-months post-surgery. Changes in normalized muscle length (muscle length as a percentage of pre-surgical muscle length) at 3 months post-surgery varied considerably across patients (16.1 % increase to 7.0 % decrease) but decreased in all patients from 3- to 12-months post-surgery (0.3 % to 17.2 %). This study developed a novel and reliable approach for quantifying supraspinatus muscle length and provided preliminary demonstration of its utility by assessing muscle length changes associated with RC pathology and surgical repair. Future studies can use this technique to evaluate changes over time in supraspinatus muscle length in response to clinical intervention, and associations between muscle length and shoulder function.

Are Lower Passive Anterior Elevation and External Rotation at 6 Weeks Postoperatively Associated With Healing of Isolated Arthroscopic Supraspinatus Repairs?

BACKGROUND

Despite advancements in surgical technique, failure of tendon healing remains a common problem after arthroscopic rotator cuff repair (ARCR).

PURPOSE/HYPOTHESIS

The purpose of this study was to examine the relationship between range of motion (ROM) recovery and healing after ARCR. It was hypothesized that an early loss of ROM would be associated with tendon healing.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

This was a retrospective comparative study of primary ARCR of isolated full-thickness supraspinatus (SSN) tendon tears. Cases were retrieved from a prospective rotator cuff repair database and divided into 2 groups based on healing (healed/nonhealed). A standardized clinical evaluation was performed before and at 6 weeks, 3 months, and 6 months after surgery. Collected data included passive and active ROM, visual analog scale for pain, and Constant score. Healing was assessed by ultrasound at 6 months.

RESULTS

Of 1397 eligible ARCRs, 1207 were included. The healing rate was 86.7%. Age was higher in the nonhealed group (57.8 ± 7.9 years vs 61.6 ± 8.8 years; P < .001). Patients with healed repairs had a larger decrease in passive anterior elevation (AE) from the preoperative to the 6-week postoperative visit (-31°± 28° vs -18°± 26°; P < .001), followed by a more substantial increase throughout the remaining follow-up period (32°± 23° vs 18°± 21°; P < .001). At 6 months postoperatively, there was no difference in AE between groups (159°± 17° vs 161°± 14°; P > .999). External rotation elbow at side (ER1) and internal rotation hand in the back (IR1) followed similar courses of recovery. Passive and active ROM had a strong positive correlation at each follow-up. Age (odds ratio [OR], 1.79; 95% CI, 1.45-2.23; P < .001) and 6-week passive AE (OR, 1.33; 95% CI, 1.20-1.48; P < .001) and ER1 (OR, 1.15; 95% CI, 1.03-1.29; P = .017) were predictors for nonhealing.

CONCLUSION

Lower passive AE and ER1 at 6 weeks postoperatively and younger age are associated with healing after ARCR of isolated SSN tendon tears. At 6 months postoperatively, there were no differences in ROM, regardless of tendon healing.

Long-term results of revision rotator cuff repair for failed cuff repair: a minimum 10-year follow-up study

HYPOTHESIS

Rotator cuff repair remains associated with high retear rates, which range from 13% to 79%. The objective of this study was to evaluate the long-term clinical and structural results after revision rotator cuff repair at a minimum 10-year follow-up.

METHODS

We retrospectively studied the records of all patients who underwent revision rotator cuff repair in 3 different institutions between July 2001 and December 2007 with a minimum 10-year follow-up. A total of 54 patients (61% males, mean age 52 ± 6 years old) met the inclusion criteria. Outcome measures included pain (visual analog scale [VAS]), range of motion (ROM), Subjective Shoulder Value (SSV), and the Constant score. Superior migration, osteoarthritis, and acromiohumeral interval (AHI) were assessed on standard radiographs. Fatty infiltration and structural integrity of the repaired tendon were evaluated on magnetic resonance imaging or computed tomographic arthrogram.

RESULTS

At a mean 14.1 years (10.4-20.5), range of motion did not progress significantly in elevation and internal rotation between pre- and postoperation (158° [range, 100°-180°] to 164° [range, 60°-180°], P = .33, and L3 [range, sacrum-T12] to T12 [range, buttocks-T7], P = .34, respectively) and decreased in active external rotation from 45° (range, 10°-80°) to 39° (range, 10°-80°) (P = .02). However, VAS, SSV, and Constant score were all significantly improved at last follow-up (P < .001). AHI decreased significantly (P = .002) from 10 mm (7-14 mm) to 8 mm (0-12 mm). Two percent of the supraspinatus/infraspinatus tendons were Sugaya 1, 24% were Sugaya 2, 35% were Sugaya 3, 12% were Sugaya 4, and 27% were Sugaya 5. Goutallier score progressed for all muscles, but this did not reach significance and mean Goutallier remained <2 for all 4 muscles at last follow-up. Hamada score progressed from 0% >grade 2 preoperatively to 6% >grade 2 at last follow-up.

CONCLUSION

Revision rotator cuff repair provides significant pain relief and improvement in functional scores at long-term follow-up. The mild progression of fatty infiltration, AHI, and Hamada score suggests that despite high retear rates (39% of stage 4 and 5 in the Sugaya classification), revision repair could possibly have a protective role on the evolution toward cuff tear arthropathy.

Transcriptional time course after rotator cuff repair in 6 month old female rabbits

Introduction: Rotator cuff tears are prevalent in the population above the age of 60. The disease progression leads to muscle atrophy, fibrosis, and fatty infiltration, which is not improved upon with surgical repair, highlighting the need to better understand the underlying biology impairing more favorable outcomes. Methods: In this study, we collected supraspinatus muscle tissue from 6 month old female rabbits who had undergone unilateral tenotomy for 8 weeks at 1, 2, 4, or 8 weeks post-repair (n = 4/group). RNA sequencing and enrichment analyses were performed to identify a transcriptional timeline of rotator cuff muscle adaptations and related morphological sequelae. Results: There were differentially expressed (DE) genes at 1 (819 up/210 down), 2 (776/120), and 4 (63/27) weeks post-repair, with none at 8 week post-repair. Of the time points with DE genes, there were 1092 unique DE genes and 442 shared genes, highlighting that there are changing processes in the muscle at each time point. Broadly, 1-week post-repair differentially expressed genes were significantly enriched in pathways of metabolism and energetic activity, binding, and regulation. Many were also significantly enriched at 2 weeks, with the addition of NIF/NF-kappaB signaling, transcription in response to hypoxia, and mRNA stability alongside many additional pathways. There was also a shift in transcriptional activity at 4 weeks post-repair with significantly enriched pathways for lipids, hormones, apoptosis, and cytokine activity, despite an overall decrease in the number of differentially expressed genes. At 8 weeks post-repair there were no DE genes when compared to control. These transcriptional profiles were correlated with the histological findings of increased fat, degeneration, and fibrosis. Specifically, correlated gene sets were enriched for fatty acid metabolism, TGF-B-related, and other pathways. Discussion: This study identifies the timeline of transcriptional changes in muscle after RC repair, which by itself, does not induce a growth/regenerative response as desired. Instead, it is predominately related to metabolism/energetics changes at 1 week post-repair, unclear or asynchronous transcriptional diversity at 2 weeks post-repair, increased adipogenesis at 4 weeks post-repair, and a low transcriptional steady state or a dysregulated stress response at 8 weeks post-repair.

Which preoperative factors influence the patient's short-term subjective assessment after rotator cuff repair?

INTRODUCTION

To highlight the preoperative risk factors that influence postoperative patient satisfaction following Rotator Cuff Repair (RCR) and to determine whether this satisfaction was correlated with tendon healing.

HYPOTHESIS

Preoperative factors influence patient satisfaction, assessed by SSV (Subjective Shoulder Value) postoperatively, with a correlation with tendon healing.

METHODS

With a mean age of 60.6 years (40-72), 102 patients with arthroscopic RCR were included retrospectively. The preoperative SSV score was less than or equal to 50%. There was clinical and radiological follow-up with an ultrasound evaluation of tendon healing 6 months postoperatively. We divided the patients into 2 groups using a postoperative SSV of 85% as the cut-off; 55 patients in the first group (SSV>85%); and 47 patients in the second group (SSV<85%).

RESULTS

In multivariate analysis, Preoperative risk factors for poor postoperative SSV after RCR were: tobacco use [-8.41 (-13.64; -3.17) p=0.002], fatty infiltration [-3.65 (-6.24 -1.06) p=0.006] and workers compensation [-19.15 (-24.04; -14.27) p<0.001]. When patients were not in workers compensation, the lower their SSV score before surgery, the higher their postoperative SSV score. For patients in workers compensation, the higher the SSV preoperatively, the less elevated was SSV postoperatively. The Sugaya ultrasound classification did not influence the SSV score (p=0.15) CONCLUSIONS: Smoking, fatty infiltration and patients in workers compensation are factors of poorer subjective results evaluated by the SSV score. Tendon healing did not influence the SSV score and patient satisfaction.

LEVEL OF EVIDENCE

IV, cohort study.

The relationship between preoperative Goutallier stage and retear rates following posterosuperior rotator cuff repair: a systematic review

BACKGROUND

An association between higher preoperative Goutallier stage and higher retear rates following primary rotator cuff repairs has been previously reported. However, there are few reviews which have described clear retear rates for each repaired tendon classified according to preoperative Goutallier stage. The purpose of this study was therefore to systematically review the literature on the relationship between preoperative Goutallier stage and retear rates and provide predictable retear rates following primary repair of posterosuperior rotator cuff tears.

METHODS

A systematic literature review was performed in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and checklist utilizing PubMed, MEDLINE, and Cochrane Library. English-language studies of Level I through IV evidence examining the clinical results of primarily repaired posterosuperior rotator cuff tears as a function of Goutallier stage using magnetic resonance imaging were included. The primary outcome of interest was retear rates according to preoperative Goutallier stage. As a secondary outcome, rotator cuff tears were divided into 2 subgroups (Goutallier stage 0-2 and 3-4) and retear rates were assessed between the 2 subgroups. A random effects model with binomial within-study variance was used for both outcomes.

RESULTS

Nine studies (687 shoulders) satisfied all inclusion criteria and reported sufficient data for statistical analysis. In the supraspinatus muscle group, rotator cuff muscles with preoperative Goutallier stages of 0, 1, and 2 had retear rates of 19.1%, 27.8%, and 33.5%, respectively, with no significant differences between each category. In contrast, when preoperative Goutallier stage of 3 and 4 existed, significant differences compared to Goutallier 0, 1, and 2 were observed with a retear rate of 74.1% and 78.5%, respectively. In the infraspinatus muscle group, the retear rates following rotator cuff repairs were 20.0%, 32.1%, and 35.1% in Goutallier 0, 1, and 2, respectively, with no significant differences between each category. In Goutallier 3 and 4, the rate was 76.6% and 100.0%, respectively, with significant differences compared to Goutallier 0, 1, and 2.

CONCLUSION

The results of this study have clearly demonstrated that retear rates following surgical repair of the rotator cuff increased in proportion to the preoperative Goutallier stage in both the supraspinatus and infraspinatus muscles.

No difference in clinical outcome after rotator cuff repair performed within or later than 3 months after trauma: a retrospective cohort study

PURPOSE

Rotator cuff (RC) tear is one of the most common injuries of the shoulder. Patients with RC tears often report a trauma initiating shoulder pain and impaired function. The aim of this retrospective analysis of a prospectively registered cohort was to elucidate whether the time interval between the trauma and RC repair, using a cut off of 3 months, affects the functional outcome after 2 years.

METHODS

In a single orthopedic unit, 819 consecutive patients were treated with rotator cuff repair during the period from 2010 to 2014 and 733 of the patients completed the Western Ontario Rotator Cuff (WORC) index preoperatively and at 2-year follow-up. The Constant-Murley (CM) score was completed by trained physiotherapists after a clinical examination both preoperatively and at 2-year follow-up. Preoperative magnetic resonance imaging (MRI) was performed in all patients and postoperatively in 65% of the included patients. Re-tears and partial repairs were excluded, as were patients with pseudoparalysis who were given high priority and underwent surgery during the first 3 weeks after trauma.

RESULTS

Of the 733 treated patients, 437 (60%) reported having had a shoulder trauma in their medical history initiating their shoulder symptoms, and of these, 358 met the inclusion criteria. 296 patients with non-traumatic tears, 9 repairs done within 3 weeks after trauma, 25 partial repairs, 33 re-tears and 12 others were excluded. At 2-year follow-up there was no significant difference in WORC index (n.s.) or CM score (n.s.) between patients who had their RC repaired within or more than 3 months after trauma. In patients where RC repair was performed within 3 months, the WORC index improved by 42.9%, and in the group of patients operated later than 3 months, the increase was 38.7%. This difference between the groups was neither statistically significant (n.s.) nor clinically relevant. On postoperative MRI, 80% of the repairs were healed in both groups.

CONCLUSION

In this retrospective cohort study, no differences in clinical outcome were found when RC repair was performed between 3 weeks and 3 months or later than 3 months after injury in patients describing their onset of symptoms as traumatic.

LEVEL OF EVIDENCE

III.

Effect of Quality of Repair on Clinical and Structural Outcomes of Rotator Cuff Repair

BACKGROUND

Anatomic repair of a torn rotator cuff tendon on the greater tuberosity (GT) is an important surgical goal in rotator cuff repair. However, few studies have investigated whether the efforts made to maximize coverage of the GT are associated with the clinical and structural outcomes after rotator cuff repair surgery.

PURPOSE

To investigate whether the quality of repair at the time of surgery is associated with clinical and structural outcomes after surgery and to identify factors influencing the quality of repair.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data were retrospectively collected from 141 patients who underwent arthroscopic rotator cuff repair between 2008 and 2016. All repairs were classified according to the amount of postoperative GT coverage: A, complete coverage of the GT (n = 96); B, incomplete coverage, comprising more than half of GT (n = 27); C, incomplete coverage, comprising less than half of the GT (n = 16); and D, exposure of the glenohumeral joint (n = 2). All patients underwent magnetic resonance imaging 1 year after surgery. Clinical outcomes and structural integrity based on Sugaya classification were assessed 2 years and 1 year after surgery, respectively. Preoperative factors associated with the postoperative GT coverage (measured at the close of surgery) were identified using a multivariable proportional odds cumulative logit model.

RESULTS

The forward flexion strength in group A (10.3 ± 4.6 lb) was significantly greater than that in group C (6.5 ± 3.7 lb) (P = .003) 2 years after surgery. The postoperative Constant score in group A (76.6 ± 11.5) was greater than that in group C (66.7 ± 15.6) (P = .018). The number of cases that showed retearing of the repaired tendon was as follows: group A (5/96; 5.2%), group B (7/27; 25.9%), and group C (10/16; 62.5%). There was no significant difference in the changes of pain visual analog scale scores among groups 2 years after surgery (all P > .05). Also, there was no significant difference in the changes of range of motion in all directions among groups 2 years after surgery (all P > .05). Patients with preoperative GT coverage B included in the postoperative GT coverage groups through surgery were as follows: group A (23/45; 51.1%), group B (17/45; 37.8%), and group C (5/45; 11.1%). Preoperative GT coverage was the only independent factor that was associated with GT coverage in multivariable analysis.

CONCLUSION

Quality of repair, measured as the extent of postoperative GT coverage at the time of surgery, was associated with clinical and structural outcomes after rotator cuff repair surgery.

Long-term functional and structural outcome of rotator cuff repair in patients 60 years old or less

Background

The long-term outcomes of rotator cuff repair (RCR) have not been well studied. The purpose of this study was to evaluate long-term functional and structural outcomes after RCR in younger patients.

Methods

A total of 49 patients (34 [69%] male) with a mean age of 51 ± 6 years were evaluated preoperatively, and at short- and long-term follow-ups (minimum 15 years). There were 13 (27%) small, 17 (35%) medium, 14 (29%) large, and 5 (10%) massive tears. 15 (31%) had an acute repair of a traumatic tear. Long-term evaluation included physical examination, plain radiographs, ultrasound, and patient reported outcome measures (PROMs) (visual analog scale pain, Disability of Arm, Shoulder and Hand, Simple Shoulder Test, American Shoulder and Elbow Surgeons score, and Short Form-36). Statistical analysis was performed to determine associations between preoperative and intraoperative factors and long-term functional and structural outcome.

Results

There were significant improvements in the mean short- and long-term PROMs compared to preoperatively that exceeded reported minimal clinically important differences and substantial clinical benefits. There was a slight decrease in the PROMs from the short-term to long-term follow-up. Male sex and traumatic rotator cuff tears were associated with better long-term outcomes. The number of medical co-morbidities was associated with worse long-term outcomes. Smaller initial tear size was associated with better long-term outcomes. There were 15 (31%) full thickness and 9 (18%) partial thickness recurrent rotator cuff tears, 17 (35%) had rotator cuff tear arthropathy (2 Hamada grade 1, 15 Hamada grade 2), 5 (10%) had revision surgery (2 revision RCR, 2 anatomic total shoulder, and 1 reverse total shoulder), and 13 (26%) had subsequent contralateral RCR. There were weak correlations between the presence of arthropathy and DASH (r = 0.34; P = .02) and visual analog scale pain (r = 0.29; P = .049). There were no significant correlations between the structural outcomes (recurrent rotator cuff tear, recurrent full thickness tear, acromiohumeral space, and critical shoulder angle,) and the PROMs.

Discussion and Conclusion

Long-term follow-up of RCR in this relatively young patient cohort demonstrated substantial and durable patient reported functional outcome and improvement despite considerable structural deterioration. This suggests that while RCR does not arrest the progression of rotator cuff disease it may delay this progression and that patients adapt to the structural changes as they age.

The correlation between types of posterior upper rotator cuff tears and intramuscular fat infiltration based on magnetic resonance imaging: A retrospective observational study

Objective: This study investigated the correlation between types of posterior upper rotator cuff tears (RCTs) and intramuscular fat infiltration (FI) in magnetic resonance imaging (MRI).

Methods: The shoulder joints of 50 adults with a full-thickness posterior upper RCT diagnosed by MRI, from January 2019 to December 2021, were retrospectively analyzed. The patients were divided into three groups according to tear type: 1) an L-shaped tear group; 2) a crescent/U-shaped tear group; 3) a complete tear group. The correlation among age, gender, tear range, trauma history, and the duration of clinical symptoms was analyzed. The MRI images were used by two musculoskeletal imaging physicians to evaluate the type and range of tears, the Goutallier grade of the supraspinatus and infraspinatus, and the correlations and reliability were analyzed.

Results: Differences in the tear range (p < 0.001) and the Goutallier grade of the infraspinatus muscle (p = 0.036) among the L-shaped, crescent/U-shaped, and complete tear groups were statistically significant; however, differences in the Goutallier grade of the supraspinatus muscle was not statistically significant (p = 0.356). In the crescent/U-shaped tear group, age was significantly correlated with the Goutallier grade of the supraspinatus muscle (RS = 0.720, p = 0.029) and the infraspinatus muscle (RS = 0.713, p = 0.032). In the complete tear group, tear range was significantly correlated with the Goutallier grade of the supraspinatus muscle (RS = 0.801, p = 0.001) and the infraspinatus muscle (RS = 0.802, p = 0.001). The Goutallier grades of the supraspinatus muscle (kappa, 0.489) and the infraspinatus muscle (kappa, 0.424) presented with interobserver consistency.

Conclusion: The type of posterior upper RCT correlates with the degree of FI. There is a positive correlation between the FI of crescent/U-shaped full-thickness RCTs and age. Additionally, the range of complete tears in the posterior upper RC has a positive correlation with FI.

Risk factors for the development of degenerative changes among patients undergoing rotator cuff repair: A systematic review

BACKGROUND

Osteoarthritis (OA) of the glenohumeral joint results in significant pain and functional limitations. It is unclear which risk factors increase the risk of developing glenohumeral OA amongst Rotator Cuff Repair (RCR) patients. The purpose of this systematic review was to examine the risk factors which may contribute to the development of osteoarthritic changes post-operatively.

METHODS

MEDLINE, Embase, and PubMed databases were searched to identify studies reporting on demographics of patients who develop OA following RCR.

RESULTS

Seventeen articles were identified investigating a total of 1292 patients. The overall quality of evidence was low. Pooled assessment of OA incidence following RCR at minimum 5 years follow-up found 26% of patients developed OA. Patients requiring revision surgery following retears developed OA at a rate of 29%. Surgical technique and patient demographics may also contribute to degenerative changes.

DISCUSSION

This review found correlations between the aforementioned risk factors and glenohumeral joint degeneration at long-term follow-up after RCR. These findings suggest that future long-term studies should aim to identify prognostic factors that may place a patient at increased risk of developing OA. Such data can be used to counsel patients with respect to long-term outcomes following surgical intervention.

A Systematic Review of Long-term Clinical and Radiological Outcomes of Arthroscopic and Open/Mini-open Rotator Cuff Repairs

BACKGROUND

Arthroscopic rotator cuff repair (aRCR) has shown similar midterm functional results and retear rates as open/mini-open rotator cuff repair (oRCR). A pooled analysis of long-term results of both techniques is yet missing.

PURPOSE

To evaluate the long-term results of aRCR and oRCR for full-thickness rotator cuff tears.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

The systematic review followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The CENTRAL (Cochrane), MEDLINE (PubMed), and Embase databases were searched for studies that reported on long-term clinical and radiographic outcomes of full-thickness aRCR and oRCR with a minimum follow-up of 9 years.

RESULTS

Eleven studies were included: 5 studies on aRCR and 6 studies on oRCR. Studies were based on 550 shoulders (539 patients) with a mean patient age of 56.3 years (range, 25-77). After a mean follow-up of 14.0 years (range, 9-20), the mean preoperative absolute Constant score (CS) and American Shoulder and Elbow Surgeons (ASES) shoulder score were significantly improved postoperatively (CS, 44 to 78 points; ASES, 52% to 91%; both comparisons, P < .001). The retear rate was 41% (141 of 342 shoulders) without a significant difference between groups (aRCR, 43%; oRCR, 39%) (P = .364). A retear was associated with significantly reduced CS as compared with a healed repair (P = .004). No significant differences were found in postoperative functional scores, complications, and retear rates after failed cuff repairs between the arthroscopic and open/mini-open repair groups.

CONCLUSION

Pooled analysis of arthroscopic and open rotator cuff repairs demonstrated sustained improvement in long-term shoulder scores and pain with a substantial retear rate in both groups, which was associated with inferior shoulder function. There were no significant differences in long-term functional outcomes, retear rates, and complications. Both surgical techniques may be used on the basis of factors such as patient or surgeon preference and cost. Further studies using a more robust randomized controlled trial or larger cohort design are recommended to ascertain whether one surgical repair technique is superior to the other.

REGISTRATION

CRD42020180448 (PROSPERO).

Inflammatory mechanisms linking obesity and tendinopathy

Chronic tendinopathy is a debilitating tendon disorder with disappointing treatment outcomes. This review focuses on the potential roles of chronic low-grade inflammation in promoting tendinopathy in obesity. A systematic literature search was performed to identify all clinical studies supporting the actions of obesity-associated inflammatory mediators in the development of tendinopathy. The mechanisms of obesity-induced chronic inflammation in adipose tissue are firstly reviewed. Common inflammatory mediators potentially linking obesity and the development of tendinopathy, and their association with mechanical overuse, are discussed, along with pre-clinical evidences and a systematic literature search on clinical studies. The potential contribution of local adipose tissues in the promotion of inflammation, pain and tendon degeneration is then discussed. The future research directions are proposed.

Translational potential statement

Better understanding of the roles of obesity-associated inflammatory mediators on tendons will clarify the pathophysiological drivers of tendinopathy in patients with obesity and identify possible treatment targets. Further studies on the mechanisms of obesity-induced chronic inflammation on tendon are a promising direction for the treatment of tendinopathy.

Increasing incidence of rotator cuff surgery: A nationwide registry study in Chile

BACKGROUND

The rotator cuff surgery (RCS) incidence is rising rapidly in North America, Europe, Asia, and Australia. Despite this, multiple factors limit patients' access to surgery. In Latin America, barriers to orthopedic surgery have been largely ignored. The purpose of this study was to calculate the rate of RCS in Chile between 2008 and 2018, investigating possible associated factors to access such as age, sex, and the health insurance.

METHODS

An ecological study was carried out with nationwide data obtained from the Database of Hospital Discharges of the Department of Statistics. All Chilean inhabitants aged 25 years or more were included. We used the ICD-10 codes M751, M754, and S460. The annual incidence rate of surgeries and the incidence rate for the period studied per 100,000 inhabitants were calculated. Data were analyzed stratified by age, sex, year of study, and the health insurance. Negative binomial regression was used to compare rates. Statistical analyzes were performed with Stata v.14 software.

RESULTS

39,366 RCSs were performed, with a total rate for the period of 32.36 per 100,000 inhabitants. The annual rate of surgeries from 2008 to 2018 increased from 24.55 to 49.11 per 100,000/year. When adjusting for year, an annual increase in surgery rates of 8.19% (95% CI 6.7-9.6) and 101% growth between 2008 and 2018 (95% CI 90-109%, p < 0.001) was observed. When comparing the global rates according to the health insurance, the public system corresponds to 21.3 per 100,000 and the private system to 72 per 100,000, the latter being 3.4-times higher (95% CI 2.7-4.4; p < 0.001).

CONCLUSION

RCS rates are increasing in Chile concordantly with previous reports of other western countries. The most important factor associated with RCS rate found was the patients' health insurance, with higher rates observed for the private sector.

Supraspinatus muscle architecture and physiology in a rabbit model of tenotomy and repair

Chronic rotator cuff tears can cause severe functional deficits. Addressing the chronic fatty and fibrotic muscle changes is of high clinical interest; however, the architectural and physiological consequences of chronic tear and repair are poorly characterized. We present a detailed architectural and physiological analysis of chronic tear and repair (both over 8 and 16 wk) compared with age-matched control rabbit supraspinatus (SSP) muscles. Using female New Zealand White Rabbits (n = 30, n = 6/group) under 2% isoflurane anesthesia, the SSP was surgically isolated and maximum isometric force was measured at four to six muscle lengths. Architectural analysis was performed, and maximum isometric stress was computed. Whole muscle length-tension curves were generated using architectural measurements to compare experimental physiology to theoretical predictions. Architectural measures are consistent with persistent radial and longitudinal atrophy over time in tenotomy that fails to recover after repair. Maximum isometric force was significantly decreased after 16 wk tenotomy and not significantly improved after repair. Peak isometric force reported here are greater than prior reports of rabbit SSP force after tenotomy. Peak stress was not significantly different between groups and consistent with prior literature of SSP stress. Muscle strain during contraction was significantly decreased after 8 wk of tenotomy and repair, indicating effects of tear and repair on muscle function. The experimental length-tension data were overlaid with predicted curves for each experimental group (generated from structural data), exposing the altered structure-function relationship for tenotomy and repair over time. Data presented here contribute to understanding the physiological implications of disease and repair in the rotator cuff.NEW & NOTEWORTHY We utilize an established method to measure the length-tension relationship for the rabbit supraspinatus in normal, torn, and repaired muscles. We then perform architectural analysis to evaluate structural changes after tear and repair. Although peak isometric force is lower in the tear and repair groups, there are no differences in peak stresses across groups. These findings indicate persistent structural changes (both radial and longitudinal atrophy) and physiological deficiencies (decreased peak force and uncoupling structure-function relationship) after tenotomy that do not significantly recover after repair.

Transcriptional Time Course After Rotator Cuff Tear

Rotator cuff (RC) tears are prevalent in the population above the age of 60. The disease progression leads to muscle atrophy, fibrosis, and fatty infiltration in the chronic state, which is not improved with intervention or surgical repair. This highlights the need to better understand the underlying dysfunction in muscle after RC tendon tear. Contemporary studies aimed at understanding muscle pathobiology after RC tear have considered transcriptional data in mice, rats and sheep models at 2–3 time points (1 to 16 weeks post injury). However, none of these studies observed a transition or resurgence of gene expression after the initial acute time points. In this study, we collected rabbit supraspinatus muscle tissue with high temporal resolution (1, 2, 4, 8, and 16 weeks) post-tenotomy (n = 6/group), to determine if unique, time-dependent transcriptional changes occur. RNA sequencing and analyses were performed to identify a transcriptional timeline of RC muscle changes and related morphological sequelae. At 1-week post-tenotomy, the greatest number of differentially expressed genes was observed (1,069 up/873 down) which decreases through 2 (170/133), 4 (86/41), and 8 weeks (16/18), followed by a resurgence and transition of expression at 16 weeks (1,421/293), a behavior which previously has not been captured or reported. Broadly, 1-week post-tenotomy is an acute time point with expected immune system responses, catabolism, and changes in energy metabolism, which continues into 2 weeks with less intensity and greater contribution from mitochondrial effects. Expression shifts at 4 weeks post-tenotomy to fatty acid oxidation, lipolysis, and general upregulation of adipogenesis related genes. The effects of previous weeks’ transcriptional dysfunction present themselves at 8 weeks post-tenotomy with enriched DNA damage binding, aggresome activity, extracellular matrix-receptor changes, and significant expression of genes known to induce apoptosis. At 16 weeks post-tenotomy, there is a range of enriched pathways including extracellular matrix constituent binding, mitophagy, neuronal activity, immune response, and more, highlighting the chaotic nature of this time point and possibility of a chronic classification. Transcriptional activity correlated significantly with histological changes and were enriched for biologically relevant pathways such as lipid metabolism. These data provide platform for understanding the biological mechanisms of chronic muscle degeneration after RC tears.

Factors associated with the development of early- to mid-term cuff-tear arthropathy following arthroscopic rotator cuff repair

BACKGROUND

Few studies have specifically evaluated the development of cuff-tear arthropathy (CTA) after a rotator cuff repair in the postoperative early to mid-term. This study aimed to identify the factors associated with the development of CTA, to evaluate the effect of arthropathy on functional outcomes, and to evaluate the incidence of CTA 3-10 years after an arthroscopic rotator cuff repair.

METHODS

A total of 312 patients who underwent an arthroscopic repair of a large or massive full-thickness rotator cuff tear with a minimum follow-up of 3 years were retrospectively divided into 2 groups for analysis: those with postrepair CTA (arthritic glenohumeral changes due to rotator cuff insufficiency) and those without. CTA was assessed using the Seebauer and modified Hamada-Fukuda classification systems. Pre-, intra-, and postoperative patient characteristics; characteristics of the rotator cuff tear; clinical and radiological parameters; and pre- and postoperative functional scores were compared.

RESULTS

The rate of development of CTA was 11.5% (36 of 312 patients, 13 centric and 23 eccentric arthropathy). CTA was more frequently associated with the poor integrity of the supraspinatus tendon after repair (P < .001) and massive tears (P = .006). Postoperative pseudoparalysis (P < .001), symptomatic retear (P < .001), tear size (P = .026), critical shoulder angle (P = .001), preoperative acromiohumeral interval (P = .046), and the humeral head superior migration (P = .001) were found to be associated with the development of CTA. However, only postoperative pseudoparalysis was found to be an independent risk factor (P < .001, odds ratio: 2.965). Patients with postrepair CTA had significantly worse functional outcome scores.

CONCLUSION

The postoperative development of pseudoparalysis may be a marker of CTA in the future and that closer follow-up may be necessary.

Rotator Cuff Retears

» Regardless of recent advances in rotator cuff repair techniques, the rate of unhealed or recurrent rotator cuff tears remains high, with most recurrent rotator cuff tears occurring within the first 6 months after surgery. » Factors that can negatively affect tendon healing include older age, greater tear size, tendon retraction, and fatty infiltration. However, several clinical features that are often underestimated, including osteoporosis, diabetes, smoking, and hyperlipidemia, have proven to have an important influence on rotator cuff healing. » Recent meta-analyses that evaluated studies with Level-I and Level-II evidence have shown an overall increase in retear rates after single-row repair compared with double-row repair. However, to our knowledge, there are no Level-I clinical studies comparing different double-row configurations and, to date, no double-row repair technique has proven to be superior to the others. » The influence of postoperative rotator cuff healing on clinical outcomes is controversial. Although clinical differences may not be apparent in the short term, healed tendons have had better functional outcomes and greater strength in the midterm. » In general, a period of immobilization for 2 to 4 weeks, depending on tear size, is recommended. Graded supervised rehabilitation has proven to facilitate tendon healing without associated stiffness compared with early unprotected range of motion.

Relationship between fatty infiltration and gene expression in patients with medium rotator cuff tear

BACKGROUND

Fatty infiltration (FI) is a key prognostic factor that affects outcomes after rotator cuff repair and is radiologically evaluated using the Goutallier classification. The purpose of this study was to assess alterations in gene and protein expression according to the Goutallier classification in the supraspinatus muscle and any relationships among various gene expression profiles.

METHODS

Twenty-four samples of the supraspinatus muscle from 12 patients with a high FI grade (grade 3 or 4) and 12 patients with a low FI grade (grade 1 or 2) with medium-sized tears were acquired during arthroscopic surgery. Alterations in the expression of genes and proteins associated with adipogenesis, fibrosis, inflammation, and muscle atrophy were compared between the high- and low-FI groups using reverse-transcription quantitative polymerase chain reaction, Western blotting, and immunohistochemistry.

RESULTS

mRNA expression of not only the adipogenic genes (peroxisome proliferator-activated receptor γ and CCAAT/enhancer-binding protein α; P < .001 and P = .020) but also the fibrosis-related gene (α-smooth muscle actin; P < .001), inflammation-related genes (interleukin [IL]-1β and tumor necrosis factor α; P = .041 and P = .039), and muscle atrophy-related genes (atrogin 1 and myostatin; P = .006 and P < .001) was higher in the high-FI group compared with that in the low-FI group. In addition, adipogenic gene expression was significantly correlated with the expression of other categories of genes (all P < .05, except atrogin 1). A correlation of gene and protein expression was observed for IL-1β (P = .027) and myostatin (P = .029).

CONCLUSIONS

The radiologic grading of FI was associated with the expression of various genes, including adipogenic, fibrotic, inflammatory, and atrophy-related genes, and these genes were closely correlated with each other in terms of expression. This information could be helpful in patient counseling.

In vivo supraspinatus muscle contractility and architecture in rabbit

The rotator cuff (RC) muscles are crucial in moving and stabilizing the glenohumeral joint, and tears can be functionally devastating. Chronic fatty and fibrotic muscle changes, which are nonresponsive to surgical tendon repair, are a focus of contemporary research. The rabbit model recapitulates key biological features of human RC tears, but function and physiology are poorly characterized; limited force and stress data are inconsistent with literature norms in other mammalian species. Here, we present an improved method to assess the physiology of the rabbit supraspinatus muscle (SSP), and we report values for healthy SSP architecture and physiology. Using female New Zealand White Rabbits (n = 6) under 2% isoflurane anesthesia, we surgically isolated the SSP and maximum isometric force measured at 4-6 muscle lengths. Architectural analysis was performed, and maximum isometric stress was computed. Whole muscle length-tension curves were generated using architectural measurements to compare experimental physiology to theoretical predictions. Maximum isometric force (80.87 ± 5.58 N) was dramatically greater than previous reports (11.06 and 16.1 N; P < 0.05). Architectural measurement of fiber length (34.25 ± 7.18 mm), muscle mass (9.9 ± 0.93 g), pennation angle (23.67 ± 8.32°), and PCSA (2.57 ± 0.20 cm²) were consistent with prior literature. Isometric stress (30.5 ± 3.07 N/cm²) was greater than previous reports of rabbit SSP (3.10 and 4.51 N/cm²), but similar to mammalian skeletal muscles (15.7-30.13 N/cm²). Previous studies underestimated peak force by ∼90%, which has profound implications for interpreting physiological changes as a function of disease state. The data that are presented here enable understanding the physiological implications of disease and repair in the RC of the rabbit.NEW & NOTEWORTHY We introduce an improved method to assess rabbit supraspinatus muscle physiology. Maximum isometric force measured for the rabbit supraspinatus was dramatically greater than previous reports in the literature. Consequently, the isometric contractile stress reported is almost 10 times greater than previous reports of rabbit supraspinatus, but similar to available literature of other mammalian skeletal muscle. We show that previous reports of peak supraspinatus isometric force were subphysiological by ∼90.

Prospective study of tendon healing and functional gain after arthroscopic repair of isolated supraspinatus tear

INTRODUCTION

In case of failure of non-operative treatment of isolated supraspinatus tear, tendon surgery can improve shoulder function and alleviate pain. The present study hypothesis was that isolated supraspinatus repair shows good healing, with improved clinical results.

MATERIALS AND METHODS

A prospective multicentre study followed up 199 patients (mean age, 57 years) for one year. Inclusion criteria comprised: isolated full-thickness supraspinatus tear, retraction grade<3, with the same double-row arthroscopic technique. Clinical assessment used Constant score at 6 weeks and 3, 6 and 12 months. Ultrasound control checked tendon repair quality on the Sugaya criteria, types I-II-III being considered as healed.

RESULTS

At one year, mean Constant score had increased by 26 points (p<0.001). Healing rate was 94% (n=187): Sugaya type I, 46% (n=92); type II, 41% (n=81); type III, 7% (n=14). Mean Constant score was significantly higher in case of healing: 81 vs. 70 points (p=0.002). Constant score progression was identical in both healing groups throughout follow-up. Univariate analysis showed no correlation between epidemiological or tear-related factors and tendon healing.

CONCLUSION

Arthroscopic repair of isolated small supraspinatus tear provided 94% healing. Clinical results were better when healing was achieved.

LEVEL OF EVIDENCE

I, prospective cohort study.

Factors Influencing the Reparability and Healing Rates of Rotator Cuff Tears

PURPOSE OF THE REVIEW

To discuss tear- and patient-related factors that influence the healing potential of rotator cuff tears and to clarify the terminology surrounding this topic.

RECENT FINDINGS

Over the last few years, further insight has been gained regarding rotator cuff tear features that are associated with poor healing rates after rotator cuff repair. Some of these features have been incorporated in prediction models developed to accurately predict rotator cuff healing rates utilizing preoperative risk factors weighted by importance. Rotator cuff tears may be considered functionally irreparable based on their size, chronicity, absence of adequate tendon length, atrophy, and fatty infiltration. Furthermore, advanced age, use of tobacco products, diabetes, and other patient-related factors may impair tendon healing. Careful analysis and discussion of all these factors with patients is essential to determine if surgical repair of a rotator cuff tear should be recommended, or if it is best to proceed with one of the several salvage procedures reviewed in this topical collection, including augmentation of the repair, superior capsular reconstruction, tendon transfers, and other.

Current Concepts in Rotator Cuff Repair Techniques: Biomechanical, Functional, and Structural Outcomes

There is substantial evidence indicating that double-row (DR) repair restores more of the anatomic rotator cuff footprint and is biomechanically superior to single-row (SR) repair. Transosseous-equivalent (TOE) techniques have shown biomechanical advantages when compared with traditional DR, including increased contact at the rotator cuff footprint, higher pressure at the tendon-bone interface, and increased failure strength. Several meta-analyses of evidence level 1 and 2 studies have shown a lower rate of failed/incomplete healing when DR repair was compared with SR repair types. There is some limited evidence that TOE techniques improve healing rates in large and massive tears as compared with SR and DR. Overall, most level 1 and 2 studies have failed to prove a significant difference between SR and DR repairs in terms of clinical outcomes. However, most studies include only short-term follow-up, minimizing the impact that the higher rate of retears/failed healing seen with SR repairs can have in the long term. There are no high-quality clinical studies comparing different DR configurations, and there are currently not enough clinical data to determine the functional advantages of various DR technique modifications over one another. Although numerous biomechanical and clinical studies comparing different rotator cuff repair techniques have been published in the past decade, none has achieved universal acceptance. It is essential for the orthopaedic surgeon to know in detail the available literature to be able to apply the most appropriate and cost-effective technique in terms of healing and functional outcomes. This review provides a critical analysis of the comparative biomechanical and clinical studies among SR, DR, and TOE techniques reported in the literature in the past decade.