Post-Op Mobilization Timing
Strong evidence suggests similar postoperative clinical and patient-reported outcomes for small to medium sized full-thickness rotator cuff tears between early mobilization and delayed mobilization up to 8 weeks for patients who have undergone arthroscopic rotator cuff repair.

Rationale

Six high quality randomized controlled trials (Cuff, D. 2012; De Roo, P. 2015; Duzgun, I. 2014; Keener, J. 2014; Koh, K. 2014; Mazzocca, A. 2017) evaluated post-operative mobilization paradigms following rotator cuff repair. All 6 studies compared the outcomes of patients who began mobilization exercises of their shoulder within 0-2 weeks post-operatively against patients who delayed mobilization exercises for between 4-8 weeks post-operatively.   In each of the reviewed studies, patients were immobilized in a sling for an equivalent length of time irrespective of group assignment. The consistency of sling use between groups allows our analysis to focus on “mobilization” as defined by thetiming the first visit of supervised physical therapy. For nearly all measures, including post-operative rotator cuff healing, patient reported outcome measures, and post-operative medication use, early and delayed moblizationparadigms yield similar outcomes.

Early mobilization favors improved range of motion (Cuff et. al. 2012; Duzgun et. al.2014, Keener et. al. 2014; Mazzocca et al. 2017) and quality of life patient reported outcome measures (Mazzocca et al.) when compared to  patients who delayedmobilization, but these differences become negligible by 6 months post-operatively.

Delayed mobilizationuntil 4-8 weeks post-operatively is associated with higher rates of post-operative healing. However, these differences do not reach statistical significance in the 5 best available evidence studies which analyzed rotator cuff integrity (Cuff et. al. 2012 , DeRoo et. al.2015, Keener et al.2014, Koh et. al. 2014, Mazzocca et. al.2017).  Post-operative healing was analyzed by US and/ or MRI from 7 days (Mazzocca et. al. 2017) through up to 2 years post-operatively (Keener et. al. 2014, Koh et. al. 2014).

In summary, early (0-2 weeks) or delayed (4-8 weeks) mobilizationyields similar outcomes in rotator cuff healing, range of motion, and patient reported outcome scores.   Early mobilization tends to favor improved range of motion through the first 6 months post-operatively while delaying mobilization exercises is associated with higher rates of post-operative healing particularly for tears of larger size.

Risks and Harms of Implementing this Recommendation
Because the early and delayed mobilization protocols yield similar results there is no known harm from implementing this recommendation.

Future Research
This question centers on the timing of post-operative mobilization exercises, defined in the 6 studies reviewed here, as the initiation of supervised physical therapy.  Although easy to quantify, a physical therapy visit may not be the measure most indicative of stress on the healing repair.  Absolute load and cyclic loading have been identified as factors affecting suture durability in biomechanical studies. 

Counting the number of physical therapy visits assumes that the amount of load and the cycles across the tendon-suture-bone interface are consistent across rehabilitation protocols.  Perhaps it is not surprising that there are few differences between early and delayed rehabilitation protocols when the measure of dosing is a physical therapy visit. If researchers want to further elucidate the differential impacts of loading a rotator cuff repair either a more finite measure of dosing should be used (number of total cycles), the study period should be shorter (12 weeks), or the rehabilitation protocols need to be more disparate.  At minimum, future research should examine the dose and load of exercise (as measured by consistent attendance at supervised physical therapy visits and consistent completion of a home exercise program) over the course of post-operative care. Finally, , more patient centric outcome measures such as the WORC quality of life score (Mazzocca et. al.) should be routinely incorporated to determine the direct impact on the patient of differing rehabilitation protocols.