Monday, October 12, 2020

Large to massive rotator cuff tears; how well do they heal?

An Update on SurgicalManagement of the Repairable Large-to-Massive Rotator Cuff Tear


The bullet points for this current concept review are:

1) Despite an evolving array of surgical options and technologies available to perform rotator cuff repair, as well as advances in postoperative rehabilitation strategies, reported failure rates remain high, with large-to-massive rotator cuff tears showing higher failure rates than small-to-medium-sized tears.


2) Preoperative magnetic resonance imaging is critical for judging the potential repairability of a large-to-massive rotator cuff tear based on imaging characteristics, including tear size and retraction, length and attenuation of the tendon stump, and fatty infiltration or atrophy in the rotator cuff muscle bellies.

 

3) Advanced fatty infiltration and atrophy in the rotator cuff muscles have been found to be independent predictors of retear following repair of large-to-massive tears.


4) While there is some evidence that double-row rotator cuff repairs have lower failure rates for larger tears, a double row repair may not always be possible in some chronic, retracted large-to-massive rotator cuff tears that cannot be completely mobilized and have tendon loss.


5) Strategies to augment rotator cuff repairs are based on the desire to improve the mechanical integrity and biologic healing environment of the repair, and they have shown promise in improving healing rates following repair of large-to-massive tears.


6) While most patients report pain relief and have increased patient-reported outcomes scores after surgery, studies have shown that patients with an intact repair have better functional scores, range of motion, and strength, and less fatty degeneration compared with patients with a failed repair.


These authors point out that the majority of patients undergoing rotator cuff repair report pain relief and have improved PROMs regardless of healing status, at least in the short term, patients with intact repairs have better functional scores, range of motion and strength, and less fatty degeneration compared with patients with failed repairs. 


The best indication for repair of a large-to-massive tear is an active patient who desires a return to premorbid function, with no substantial glenohumeral joint degenerative changes, little or no fatty infiltration and muscle atrophy in the rotator cuff muscles, and surgeon expectation of a repairable tendon,


Surgical failure rates following repair of large-to-massive tears remain high.

Here are their summary recommendations:





These authors have introduced the important concept of failure with continuity,in which "elongation at the repair site" occurs without a recurrent full-thickness defect.


In prior studies (see this link), radiostereometric analysis was used to evaluate tendon retraction based on metal sutures placed at the repair site, and ultrasound was used to evaluate structural integrity. One year postoperatively, 9 of 10 repairs had retracted an average of 7 mm and 5 of 10 repairs showed a recurrent defect.





In another prospective study of repair retraction of 1 to 4-cm tears after arthroscopic double-row repair in 13 patients (see this link), authors measured the retraction of tantalum beads affixed to the repaired tendon with

computed tomography and evaluated structural healing with MRI. All repairs retracted, while the retear rate was 30% at the 1-year follow-up evaluation. Retraction was similar for healed (15-mm) and failed (18-mm) repairs. 





In both studies, most tendon retraction was seen during the first 3 months postoperatively.




It is worth pondering why this retraction might occur. When we look a chronic cuff defect, such as the one below, there is loss of some of the length of the torn tendon due to resorption and retraction. Thus  in order to approximate the torn edge to the footprint at the tuberosity, we place the repaired tendon under greater tension than the intact tendon on either side of it. Therefore, with either static or dynamic loading the pull of the cuff muscles is preferentially applied to the repaired tendon. This would tend to accentuate the problem of suture tension overload encountered during recovery. Perhaps if the resulting creep of the tendon away from the repair site took place at a slow rate, it would allow the body to 'backfill' the resulting gap resulting in 'failure with continuity'.


On reflection of all of the above, it seems that the stress relaxation hypothesis may be consistent with the observations.

Consider this diagram of a cuff tear where the orange part of the cuff has pulled away from the blue tuberosity leaving the red portions of the cuff intact.



The surgeon repairs the torn (orange) part of the cuff to the tuberosity, but in doing so, takes the normal tension off of the intact (red) portions of the cuff and causing the repaired portion to support the load applied by the cuff musculature.


Stress relaxation must occur so that the normal portions of the cuff are under physiologic load. This can happen by recurrence of the cuff defect, as diagrammed below (this may be the situation in older individuals with larger cuff defects)


or by 'failure in continuity' in which the torn (orange) and intact (red) portions of the cuff progressively return to their original position, but that new regenerative tissue (green) tissue forms as the edge of the torn tendon pulls away from the footprint.


We can be grateful to these authors for clarifying both that many large to massive cuff tears do not heal after a repair attempt and also that even when a post operative MRI shows tissue in the area of the cuff tendon (see the MRI above) it does not mean that the tendon has directly healed to the site to which it was repaired.
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