Rotator cuff muscles fatty infiltration increases with age: retrospective review of 210 patients with intact cuff on computed tomography arthrography

Maximum in-vivo joint contact forces double during active compared to assisted motion in the glenohumeral joint and decline long-term due to rotator cuff pathologies

Rehabilitation programs advocate early passive and assisted motion after rotator cuff repair to induce healing und maintaining range of motion while avoiding excessive strain on the repaired tendons. In-vivo glenohumeral joint contact forces reflect the compressive forces generated by the rotator muscles. In the present study, maximum in-vivo joint contact forces (FresMax) were determined to compare active and assisted execution of a single movement and the long-term development of joint compression forces. FresMax were measured in six patients who received instrumented, telemetric modified anatomical hemi endoprostheses of the shoulder joint between 2006 and 2008. Data were gathered 23 months postoperatively (2006-2010), were analysed and compared with measurements 133 months postoperatively. Additional imaging was obtained as x-rays and ultrasound examination. Data analysis was conducted by synchronizing video tapes and measured force curves. New imaging showed a rupture of the M. supraspinatus and progressive joint degeneration. FresMax nearly doubled during active compared to assisted execution of each of the four chosen movements. Over the course of 133 months post-surgery, the studied movements showed a decrease of active compression force, probably due to a ruptured supraspinatus, resulting in a lower active/assisted ratio. A long term follow up after eleven years, eight out of ten measured movements showed a decrease of FresMax. These results support current rehabilitation protocols recommending early passive and assisted motion to limit activation of the rotator muscles generating compressive forces. Following degeneration of the rotator cuff, active joint contact forces decrease over time.Level of evidence: III.

Investigating the relationship between quantitative-based ultrasound and MRI estimations of rotator cuff fatty infiltration

INTRODUCTION

Fatty infiltration (FI) of the rotator cuff has important clinical implications. Quantitatively estimating FI using ultrasound (US) has considerable benefits for assessing FI in a non-invasive, accessible manner. This research investigated whether FI of the supraspinatus (SS) and infraspinatus (IS), estimated using US was related to intramuscular fat fractions measured from magnetic resonance images (MRI).

METHODS

Data from 12 healthy young adult participants were used for analysis. US images of the SS and IS were captured using multiple transducer placement techniques from which echogenicity of the muscle region was quantified. Shoulder MRI were captured from which SS and IS were manually segmented and intramuscular fat fractions calculated. Six upper limb strength exertions were performed, resisted by a hand dynamometer.

RESULTS

IS and SS echogenicity explained a significant amount of variance in MRI fat fractions for certain body positions and transducer techniques. Echogenicity agreement was higher for IS than SS. Significant relationships were identified between strength exertions and both echogenicity and MRI muscle volume, but not MRI fat fraction.

CONCLUSIONS

This research provides preliminary evidence showing that quantitative-based US methods can be used to estimate MRI calculated fat fractions for the rotator cuff.

Assessment of fatty infiltration of the hamstring muscles in chronic proximal hamstring ruptures and effect on clinical outcomes after surgical repair: a novel application of the Goutallier classification

INTRODUCTION

Increased time to surgery has been previously associated with poorer clinical outcomes after surgical treatment of proximal hamstring ruptures, though the etiology remains unclear. The purpose of this study was to evaluate whether degree of muscle atrophy, as assessed using the Goutallier classification system, is associated with worse outcomes following surgical treatment of chronic proximal hamstring ruptures.

MATERIALS AND METHODS

This was a retrospective case series of patients who underwent repair of proximal hamstring ruptures from 2012 to 2020 with minimum 2-year follow-up. Patients were included if they underwent primary repair of a proximal hamstring rupture ≥ 6 weeks after the date of injury and had accessible preoperative magnetic resonance imaging (MRI). Exclusion criteria were allograft reconstruction, endoscopic repair, or prior ipsilateral hip surgery. Patients were administered validated surveys: the modified Harris Hip Score (mHHS) and Perth Hamstring Assessment Tool (PHAT). Fatty atrophy on preoperative MRI was independently graded by two musculoskeletal radiologists using the Goutallier classification. Multivariate regression analysis was performed to evaluate associations of preoperative characteristics with muscle atrophy, as well as mHHS and PHAT scores.

RESULTS

Complete data sets were obtained for 27 patients. A majority of this cohort was male (63.0%), with a mean age of 51.5 ± 11.8 years and BMI of 26.3 ± 3.8. The mean follow-up time was 62.6 ± 23.1 months, and the mean time from injury-to-surgery was 20.4 ± 15.3 weeks. The Goutallier grading inter-reader weighted kappa coefficient was 0.655. Regression analysis demonstrated that atrophy was not significantly associated with PHAT (p = 0.542) or mHHS (p = 0.574) at latest follow-up. Increased age was significantly predictive of muscle atrophy (β = 0.62, p = 0.005) and was also found to be a significant predictor of poorer mHHS (β = - 0.75; p = 0.037).

CONCLUSIONS

The degree of atrophy was not found to be an independent predictor of clinical outcomes following repair of chronic proximal hamstring ruptures. Increasing age was significantly predictive of increased atrophy and poorer patient-reported outcomes.

Objective analysis of partial three-dimensional rotator cuff muscle volume and fat infiltration across ages and sex from clinical MRI scans

Objective analysis of rotator cuff (RC) atrophy and fatty infiltration (FI) from clinical MRI is limited by qualitative measures and variation in scapular coverage. The goals of this study were to: develop/evaluate a method to quantify RC muscle size, atrophy, and FI from clinical MRIs (with typical lateral only coverage) and then quantify the effects of age and sex on RC muscle. To develop the method, 47 full scapula coverage CTs with matching clinical MRIs were used to: correct for variation in scan capture, and ensure impactful information of the RC is measured. Utilizing this methodology and automated artificial intelligence, 170 healthy clinical shoulder MRIs of varying age and sex were segmented, and each RC muscle's size, relative contribution, and FI as a function of scapula location were quantified. A two-way ANOVA was used to examine the effect of age and sex on RC musculature. The analysis revealed significant (p < 0.05): decreases in size of the supraspinatus, teres minor, and subscapularis with age; decreased supraspinatus and increased infraspinatus relative contribution with age; and increased FI in the infraspinatus with age and in females. This study demonstrated that clinically obtained MRIs can be utilized for automatic 3D analysis of the RC. This method is not susceptible to coverage variation or patient size. Application of methodology in a healthy population revealed differences in RC musculature across ages and FI level between sexes. This large database can be used to reference expected muscle characteristics as a function of scapula location and could eventually be used in conjunction with the proposed methodology for analysis in patient populations.

Is stemless total shoulder arthroplasty indicated in elderly patients?

BACKGROUND AND HYPOTHESIS

Stemmed anatomic total shoulder arthroplasty has represented the gold standard for the treatment of glenohumeral osteoarthritis with an intact rotator cuff for decades. To the author's knowledge, no study has specifically examined the outcomes of stemless, modular total shoulder arthroplasty in elderly patients. The hypothesis of this study was that stemless anatomic total shoulder arthroplasty in elderly patients (age ≥70 years) would have equivalent clinical and radiographic outcomes compared with a younger population (age <70 years).

MATERIALS AND METHODS

A prospectively collected database of patients undergoing primary, modular, stemless anatomic total shoulder arthroplasty for osteoarthritis was retrospectively reviewed. Patient-determined outcomes including the Western Ontario Osteoarthritis Index (WOOS) score, American Shoulder and Elbow Surgeons (ASES) score, Single Assessment Numeric Evaluation (SANE) score, Simple Shoulder Test score, and Shoulder Activity Level score were recorded preoperatively and postoperatively at 1 year and 2 years. Preoperative and 1-year postoperative range of motion was recorded. Postoperative radiographs were examined to assess for radiographic evidence of complications.

RESULTS

Stemless arthroplasty was planned in 116 patients. Seven patients underwent conversion intraoperatively to a stemmed prosthesis. There was no difference between patients aged <70 yr and those aged ≥70 years who required intraoperative deviation from the preoperative plan to a stemmed prosthesis (5.8% vs 6.4%, P = .90). At the time of stemless arthroplasty, 64 patients were aged <70 yr and 44 patients were aged ≥70 years. Between the 2 groups, there were no clinically or statistically significant differences in WOOS, ASES, and SANE scores at baseline, 1-year follow-up, or 2-year follow-up. The changes in all scores from baseline to 2 years were similar between the group aged <70 yr and the group aged ≥70 years. There was no difference in the percentage of patients achieving the minimal clinically important difference or substantial clinical benefit in either group after shoulder arthroplasty at 2-year follow-up. There was no difference between the 2 groups in terms of final postoperative range of motion or change in range of motion for any metric examined. There was no evidence of radiographic complications in either group.

CONCLUSIONS

Age ≥70 years does not appear to be a contraindication to stemless anatomic total shoulder arthroplasty. Postoperative improvements in patient-determined outcome scores, the percentage of patients achieving clinically important outcomes for the ASES, SANE, and WOOS scores, and postoperative range of motion were similar between patients aged <70 yr and those aged ≥70 years. There was no difference between the groups regarding the patients who required intraoperative deviation from the preoperatively planned stemless prosthesis to a stemmed prosthesis. Neither age group demonstrated a radiographically apparent complication.

Natural History of Degenerative Hip Abductor Tendon Lesions

BACKGROUND

The best treatment of degenerative hip abductor tendon lesions remains largely unknown, as the natural course of the disease has not yet been reported. The aim of the present study was to investigate the natural history of symptomatic degenerative hip abductor lesions.

HYPOTHESIS

Nonoperatively treated hip abductor lesions progress over time, resulting in refractory hip pain and low functional outcomes.

STUDY DESIGN

Case series (prognosis); Level of evidence, 4.

METHODS

Consecutive patients with greater trochanteric pain syndrome and degenerative changes on magnetic resonance imaging (MRI) of the symptomatic hip were included. Bilateral hip MRI scans and a clinical examination were performed at a minimum follow-up of 36 months to study the type and location of hip abductor lesion. Progression of a lesion was defined as a more severe lesion as compared with the initial MRI results or if the lesion extended to another, initially not involved, trochanteric facet. The muscle's fatty infiltration (FI) was also described.

RESULTS

From 106 patients identified, 58 patients (64 hips) aged 66 ± 14 years (mean ± SD) agreed to return to the clinic for follow-up MRI and met the inclusion criteria. At a mean 71-month follow-up, an overall 34% (22/64) of lesions had progressed over time: from trochanteric bursitis to tendinopathy (9/64, 14%) or partial tear (5/64, 8%), from tendinopathy to partial tear (4/64, 6%), from a partial to complete tear (3/64, 4.5%), and with 1 complete tear (1/64, 1.5%) extending to another trochanteric facet. Interestingly, 90% of partial tears remained stable or transformed into a scar. Although patients with a progressive lesion experienced more trochanteric pain (visual analog scale, 4.6 vs 2.8; P = .001), the functional outcomes were comparable with patients with a stable lesion. The majority of hips with a partial tear (64%) demonstrated a progression of gluteus minimus FI from a median grade of 1 to 2, whereas only 1 hip (3%) progressed from grade 2 to 3. Only 3 hips (9%) with a partial tear had a progression of gluteus medius FI, which did not differ significantly from the contralateral unaffected side.

CONCLUSION

Nonoperative treatment might be a valid long-term option for degenerative hip abductor lesions, especially for partial tears, which demonstrated a low risk of clinically relevant progression or muscle FI and similar clinical outcomes to those reported in the literature for operatively treated hip abductor tendon lesions.

Fatty infiltration in the intact supraspinatus tendon; a normal physiological response with increasing age and female gender

Background

Fatty infiltration and muscle atrophy of supraspinatus are used as markers of chronicity in rotator cuff tears and are known to both be independently related to poorer outcomes following surgical repair.1 We hypothesized that supraspinatus muscle atrophy and fatty infiltration increases with age irrespective of whether the rotator cuff is intact and therefore cannot be used as accurate markers for chronicity.

Method

Retrospective review of 280 patients who underwent 3.0 T shoulder MRI's with either a normal scan or rotator cuff tear. Two independent observers reviewed the images. Data collected included intact rotator cuff tendons looking specifically at supraspinatus muscle height/length: suprascapular fossa ratio, tangent sign and Goutallier grade for fatty infiltration.

Results

There were 90 scans with intact rotator cuff tendons. Mean age was 51 years (range 17-86); 52 males, 38 females. On multiple regression analysis, there was a positive correlation of age with fatty infiltration and muscle atrophy on all parameters in the normal intact cuff. Females were significantly more likely than males to have a higher grade of fatty infiltration.

Conclusion

Age and female gender are risk factors for rotator cuff atrophy and fatty infiltration in patients with normal rotator cuffs. Therefore, these parameters should be used with caution by surgeons when deciding on tear chronicity and the potential to repair the torn rotator cuff.

A unique sarcopenic progression in the mouse rotator cuff

BACKGROUND

In response to chronic injury, the muscles of the rotator cuff (RC) experience a unique degeneration characterized by extensive fatty infiltration and loss of contractile function. Human studies suggest this degeneration is also a feature of RC sarcopenia and may precede RC injury. In this study, we investigated whether RC muscles exhibit a similar unique sarcopenia in the mouse.

METHODS

Male and female mice were subdivided into four age groups: 3, 9, 18, and 24 months. The supraspinatus (SS) and infraspinatus muscles of the RC and the tibialis anterior (TA) muscle of the hindlimb were assessed. Muscle mass, contractile function, fibre cross-sectional areas and numbers, fatty infiltration, and fibrosis were assessed at each time point. Targeted transcriptional analyses were performed to assess the role of metabolic and inflammatory derangement in the pathology.

RESULTS

The 24-month-aged female mice exhibited decreased mass (25% lower than at 9 and 18 months, P < 0.01) in all muscles tested. However, only RC muscles also exhibited decreased contractile tension at this time point (20% lower than at 18 months, P < 0.005). Similarly, only female RC muscles exhibited increased fatty infiltration at 24 months (20% higher than 9 months, P < 0.05) and had elevated transcriptional markers of adipogenesis (2.4-fold higher Pparg and 3.8-fold higher Adipoq expression compared with 9 months, P < 0.001). Unbiased metabolic transcriptional profiling identified up-regulation of the antigen presentation (Z scores of 2.3 and 1.9 for SS and TA, respectively) and cytokine and chemokine signalling (Z scores of 3.1 and 2.4 for SS and TA, respectively) pathways in 24 month female muscle compared with 9. Further transcriptional analysis supported increased expression of pro-adipogenic inflammatory signals (6.3-fold increase in Il6 and 5.0-fold increase in Anxa2, P < 0.01) and increased presence of fibro-adipogenic progenitors (2.5-fold) in the 24-month-aged female RC compared with 9 months that together exacerbate fatty infiltration.

CONCLUSIONS

These data indicate that female mice replicate the unique sarcopenic pathology in the ageing human RC. Furthermore, they suggest that the exacerbated fatty infiltration is due to an interaction between higher resident fibro-adipogenic progenitor numbers and an elevated systemic inflammation in aged female mice. We conclude that female mouse RC muscle is a novel system to study both human RC degeneration and the signals that regulate sarcopenic fatty infiltration in general, which is prevalent in humans but largely absent from the rodent hindlimb.

Analysis of Greater Tuberosity from the Center of the Humeral Head: Progression to Femoralization

Background

Progression of the tear size and erosion of the greater tuberosity (femoralization) in the supraspinatus tear makes it difficult to repair or increases the risk of a re-tear. This study examined the proximal articular surface and greater tuberosity of the humeral head in plain radiography.

Methods

Two-hundred forty-seven cases, whose anteroposterior (AP) radiographs were taken correctly, were included from 288 cases, in whom the status of the supraspinatus had been confirmed by surgery. After downloading the plain AP radiograph as DICOM, the radius of the circle apposed at the superior half of the articular surface of the head, and the distance between the circle and the farthest point of the greater tuberosity (‘height’ of the greater tuberosity) were calculated using the software (TechHime, Korea). MRI checked the number of torn tendons and degree of muscular atrophy.

Results

The following were encountered: 93 intact supraspinatus, 50 partial-thickness tears, and 104 full-thickness tears. In the analysis using the 93 intact cases, the average radius of the rotation center was 25.3 mm in male and 22.3 mm in female. The average height of the greater tuberosity from the circle with the same rotation center was 4.3 mm in male and 4.2 mm in female with no statistical significance. The correlation between the reparability of supraspinatus and height of the greater tuberosity, fatty infiltration, and muscular atrophy was confirmed.

Conclusions

The height of the greater tuberosity from the circle with the same rotation center was 4.3 mm in male and 4.2 mm in female. This height was strongly correlated with muscular atrophy and fatty infiltration of the supraspinatus tendon.