Assessing Fatty Infiltration in Rotator Cuff Tears: MRI vs Ultrasound
In the setting of rotator cuff injuries, higher degrees of fatty infiltration into cuff muscles are positively correlated with higher repair failure rates and worse clinical outcomes. MRI continues to be the gold standard imaging modality for evaluating fatty infiltration of the rotator cuff, but ultrasound represents another viable modality for that assessment—at considerably lower cost. Such is the conclusion of Tenbrunsel et al. in a recent issue of JBJS Reviews.
The authors reviewed 32 studies that investigated imaging modalities used to assess fatty infiltration and fatty atrophy. They found that grading fatty infiltration using ultrasound correlated well with grading using MRI. However, the authors identified difficulties distinguishing severe from moderate fatty infiltration on ultrasound, but they added that discerning mild from moderate fatty infiltration is more important clinically. Tenbrunsel et al. also mention sonoelastography, which measures tissue elasticity and can also be used to help determine the severity of fatty atrophy of the rotator cuff.
Overall, the trade-off between MRI and ultrasound comes down to higher precision with the former and lower cost with the latter.
For more information about JBJS Reviews, watch this video featuring JBJS Editor-in-Chief Dr. Marc Swiontkowski.
What’s New in Shoulder and Elbow Surgery 2018
Every month, JBJS publishes a Specialty Update—a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all OrthoBuzz Specialty Update summaries.
This month, Robert Tashjian, MD, co-author of the October 17, 2018 Specialty Update on shoulder and elbow surgery, selected the most clinically compelling findings from among the 36 studies summarized in the Specialty Update.
Progression of Primary Osteoarthritis
–A study evaluating the relationship between glenoid erosion patterns and rotator cuff muscle fatty infiltration found that fatty infiltration was associated with B3 glenoids, increased pathologic glenoid retroversion, and increased joint-line medialization. The authors recommend close observation of patients with B-type glenoids, as the progression of glenoid erosion is more likely in B-type than A-type glenoids.
Perioperative Pain Management
–In a randomized controlled trial of perioperative pain management in patients undergoing primary shoulder arthroplasty, narcotic consumption during the first 24 postoperative hours was similar between a group that received interscalene brachial plexus blockade and a group that received intraoperative soft-tissue infiltration of liposomal bupivacaine. The interscalene group had lower VAS pain scores at 0 and 8 hours postoperatively; both groups had similar VAS pain scores at 16 hours; and the soft-tissue infiltration group had lower pain scores at 24 hours postoperatively.
Rotator Cuff
–In a reevaluation of patients with nonoperatively treated chronic, symptomatic full-thickness rotator cuff tears that had become asymptomatic at 3 months, researchers found that at a minimum of 5 years, 75% of the patients remained asymptomatic.1 The Constant scores in the group that remained asymptomatic were equivalent at 5 years to those who initially underwent surgical repair. While these findings suggest that nonoperative treatment can yield clinical success at 5 years, the authors caution that “individuals with substantial tear progression or the development of atrophy will likely have a worse clinical result.”
–A recent study of the progression of fatty muscle degeneration in asymptomatic shoulders with degenerative full-thickness rotator cuff tears found that larger tears at baseline had greater fatty degeneration, and that tears with fatty degeneration were more likely to enlarge over time. Median time from tear enlargement to fatty degeneration was 1 year. Because the rapid progression of muscle degeneration seems to occur with increasing tear size, such patients should be closely monitored if treated nonoperatively.
Shoulder Instability in Athletes
–An evaluation of outcomes among 73 athletes who had undergone Latarjet procedures found that, after a mean follow-up of 52 months, ASES scores averaged 93. However, only 49% of the athletes returned to their preoperative sport level; 14% decreased their activity level in the same sport; and 12% changed sports altogether. While the Latarjet can help stabilize shoulders in athletes, the likelihood is high that the athlete won’t return to the same level in the same sport after the procedure.
Reference
- Boorman RS, More KD, Hollinshead RM, Wiley JP, Mohtadi NG, Lo IKY, Brett KR. What happens to patients when we do not repair their cuff tears? Five-year rotator cuff quality-of-life index outcomes following nonoperative treatment of patients with full-thickness rotator cuff tears. J Shoulder Elbow Surg. 2018 Mar;27(3):444-8.
Which Pathology Comes First—Bone Loss or Fatty Infiltration of Rotator Cuff?
The relative roles of bones and muscles in joint pathologies are often difficult to tease apart. In the March 7, 2018 issue of The Journal, Donohue et al. report findings from their attempt to identify associations between preoperative fatty infiltration in rotator cuff muscles and glenoid morphology among 190 shoulders that underwent total shoulder arthroplasty (TSA) for glenohumeral osteoarthritis.
The painstaking analysis included orthogonal CT images to determine fatty infiltration, joint-line medialization assessments, direct measurements of glenoid version, and grading of glenoid morphology (from A1 through C2) using a modified Walch classification. Here’s what Donohue et al. found:
- High-grade posterior rotator cuff fatty infiltration was present in 55% of the 38 glenoids classified as B3, compared with only 8% fatty infiltration in the 39 A1-classified glenoids.
- Increasing joint-line medialization was associated with increasing fatty infiltration of all rotator cuff muscles.
- Higher fatty infiltration of the infraspinatus, teres minor, and combined posterior rotator cuff muscles was associated with increasing glenoid retroversion.
- After the authors controlled for joint-line medialization and retroversion, B3 glenoids were more likely than B2 glenoids to have fatty infiltration of the supraspinatus and infraspinatus.
The authors say these findings “support the idea that there is a causal association between rotator cuff muscle fatty infiltration and B3 glenoid morphology,” but they are quick to add that “from this study we cannot conclude [whether] these patterns of rotator cuff muscle fatty infiltration precede the progression of bone pathology, or vice versa.” Either way, these findings may inform patient-surgeon discussions about TSA, because both glenoid morphology and rotator cuff muscle quality are factors in glenoid-component longevity.
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