Sports Medicine Research: In the Lab & In the Field: Fatty Infiltration and Acromiohumeral Distance Affect Healing and Function Following Cuff Repair (Sports Med Res)
Friday, May 31, 2013

Fatty Infiltration and Acromiohumeral Distance Affect Healing and Function Following Cuff Repair

Arthroscopic Repair of Massive Rotator Cuff Tears: Outcome and Analysis of Factors Associated with Healing Failure or Poor Postoperative Function

Chung SW, Kim JY, Kim MH, Kim SH, Oh JH.Am J Sports Med. 2013 Apr 30. [Epub ahead of print]

Take Home Message: Following repair of massive rotator cuff tears, pre-operative fatty infiltration of the infraspinatus and post-operative reduced acromiohumeral distance negatively affects healing and functional outcomes, respectively. Each of these factors should be considered when determining prognosis and prescribing treatment strategies.

Massive rotator cuff tears are a common cause of shoulder pain and dysfunction.  Unfortunately, surgical repair of massive cuff tears is often unsuccessful (failure rate up to 94%).  Interestingly, many patients are able to achieve functional improvement even with an unhealed cuff after repair.  However, the factors which affect function after massive cuff tear, particularly after failed repair, are unclear.  Therefore, the purpose of this study was to evaluate outcomes after repair of massive cuff tears, to identify prognostic factors that affect cuff healing, and ultimately to determine the factors influencing functional outcome in failed rotator cuff healing.  The authors included a total of 108 patients with an average age of 64 years and evaluated functional outcomes pre-operatively and a minimum of 1 year post-operatively. They also assessed cuff integrity post-operatively and numerous key factors that can affect the outcome of arthroscopic repair: age, sex, symptom duration, preoperative pain intensity, comorbidities, hand dominance, bone and tissue quality (bone mineral density and fatty infiltration [FI]), preoperative stiffness and pseudoparalysis, tear size and location, acromiohumeral distance (AHD), repair technique, and concomitant surgical procedures (distal clavicle resection and biceps procedures).  The authors evaluated differences according to cuff healing and functional outcome.  Almost 40% of patients had anatomic failure of the repair while functional status improved regardless of cuff healing.  Many factors associated with failure of cuff healing; however, pre-operative FI of the infraspinatus was a key determinant of healing failure.  Additionally, among patients with failed cuff healing, only reduced post-operative AHD was related to poor functional outcome while no preoperative factors were identified.

This study identified the single most influential factor that negatively affected cuff healing (higher FI) and another for functional outcome (reduced postoperative AHD).  Failed rotator cuff healing has previously been attributed to poor tissue quality (high FI). Despite various combinations of involved tendons, FI of the infraspinatus was the most influential predictor of failed cuff healing.  The infraspinatus plays an important role in providing compression of the humeral head on the glenoid through the anterior-posterior “force couple” provided by the subscapularis anteriorly and infraspinatus posteriorly.  FI of the infraspinatus may disrupt this “force couple”, alter glenohumeral joint mechanics, and ultimately impair healing in the remaining repaired tendons.  Additionally, functional outcomes after repair have previously been related to AHD; however, controversy still exists regarding its effect.  Findings from this study suggest that post-operative AHD may be an indicator of rotator cuff function. Monitoring of AHD during the post-operative period may help determine patient prognosis and assist in development of treatment strategies.  Specifically, clinicians may want to address reduced AHD via non-operative interventions such as physical therapy to improve functional outcomes following massive cuff repair.

Questions for Discussion: How do you think the results of this study will affect clinical practice?  Should reduction of the AHD in patients with massive cuff tears be the goal of post-operative rehabilitation?

Written by: Katie Reuther
Reviewed by:  Jeffrey Driban

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Chung SW, Kim JY, Kim MH, Kim SH, & Oh JH (2013). Arthroscopic Repair of Massive Rotator Cuff Tears: Outcome and Analysis of Factors Associated With Healing Failure or Poor Postoperative Function. The American Journal of Sports Medicine PMID: 23631883

1 comments:

Stephen Thomas, PhD, ATC said...

Katie nice post! Your last question is interesting but something that I don't think we are clear on. First without an ultrasound we cant measure this in the clinic. Second I don't think we know how to increase AHD through therapeutic exercises. I think trying to train the rotator cuff to function dynamically to center the humeral is key and as you point out if the infraspinatus doesn't heal then we lost the anterior-posterior force couple. However we also dont know if that anterior-posterior force couple prevents superior migration of the humeral head. There are also other factors that may decrease the AHD like glenoid inclination. Some have described the subscap as a humeral head depressor so should we be targeting that muscle in our rehab. These are questions that I know cant be answered I just wanted to raise them to get people thinking and show that there is still a lot of work to be done! Thanks for the post.

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