"Surviving the dip" after subacromial balloon spacer implantation for massive rotator cuff tear treatment: a retrospective case series.

Background: Subacromial balloon spacer implantation (SBSI) attempts to decrease glenohumeral joint (GHJ) pain and improve function in patients with an irreparable rotator cuff tear (RCT) and minimal osteoarthritis. Between 12 and 26 weeks post-SBSI, gradual implant resorption may create a "balloon dip" that decreases GHJ function and increases pain. This retrospective cohort study attempted to delineate shoulder function, active mobility, strength, pain, and functional task impairment during the "balloon dip" period.

Materials and methods: Sixty-five consecutive patients (55.9 ± 7 years of age, 42 men) with an irreparable RCT treated by the same fellowship-trained shoulder surgeon participated in this study. Outcome measurements pre-SBSI, during Phase I (early pain control ≤ 3 weeks post-SBSI), Phase II (early rehabilitation > 3-11 weeks post-SBSI), Phase III (advanced rehabilitation-early balloon resorption > 11-16 weeks post-SBSI), Phase IV (early strength training > 16-24 weeks post-SBSI), and Phase V (advanced strength training > 24 weeks post-SBSI) included the American Shoulder and Elbow Society (ASES) score for perceived bilateral shoulder function, visual analog scale (VAS) surgical shoulder pain score, active mobility, and shoulder manual muscle strength testing (p ≤ 0.05).

Results: The mean final follow-up time was 40 weeks (range = 24.1-89.7 weeks). The surgical shoulder had higher ASES scores at Phase V than pre-SBSI. Surgical shoulder pain was less during Phase V than pre-SBSI. The surgical shoulder had greater flexion during Phase V than at Phase II or pre-SBSI, and greater external rotation (adducted) during Phases V-III than pre-SBSI. Peak shoulder internal rotation to level 12 (thoracic spinous process #10) occurred during Phase V. Peak shoulder flexor, external rotator, and internal rotator strength occurred during Phase V. During Phase I, most subjects were unable to sleep on their surgical shoulder, wash their back/do up their bra, reach a high shelf, or lift 10-lbs overhead. Tasks that were impaired during the "balloon dip" (between Phase III and V) were lifting 10-lbs overhead, reaching a high shelf, and doing normal work. By the end of Phase V, however, most subjects could perform each task with minimal or no difficulty.

Conclusion: Surgical shoulder function improved and pain decreased, however, specific perceived functional task impairments remained. During the "balloon dip" phase, the perceived ability to lift 10 lbs above shoulder level, to reach a high shelf, and to do usual work activities were the most impaired tasks.