Graft healing does not influence subjective outcomes and shoulder kinematics after superior capsule reconstruction: a prospective in vivo kinematic study

Background: A viable treatment option for young patients with massive, irreparable rotator cuff tears is arthroscopic superior capsule reconstruction (SCR). SCR theoretically improves shoulder stability and function and decreases pain. However, no prospective studies to date have correlated magnetic resonance imaging (MRI) healing with in vivo kinematic data. The purpose of this study was to evaluate the association between graft healing and in vivo kinematics, range of motion (ROM), strength, and patient-reported outcomes (PROs).

Methods: Ten patients (8 men and 2 women; mean age, 63 ± 7 years) with irreparable rotator cuff tears underwent arthroscopic SCR with dermal allograft. Strength was measured with isometric internal rotation and external rotation (ER) at 0° of abduction, ER at 90° of abduction, and scapular-plane abduction, whereas ROM was measured during shoulder flexion, abduction, and ER and internal rotation at 90° of abduction both before and 1 year after SCR. PROs included American Shoulder and Elbow Surgeons, Western Ontario Rotator Cuff Index, and Disabilities of the Arm, Shoulder and Hand surveys that were collected before and 1 year after SCR. Synchronized biplane radiographs were collected at 50 images/s before and 1 year after SCR while patients performed 3 trials of scapular-plane abduction. A validated volumetric tracking technique with submillimeter accuracy determined 6-df glenohumeral and scapular kinematics. The acromiohumeral distance (AHD), humeral head translation, and scapulohumeral rhythm (SHR) were calculated from the in vivo kinematics. Healing at 5 locations was evaluated on 1-year postoperative MRI scans: anterior and posterior glenoid, anterior and posterior humerus, and posteriorly along the infraspinatus. Each subject was given a score from 0 to 5 based on number of sites healed.

Results: Of the 10 patients, 9 (90%) had complete (n = 4) or partial (n = 5) healing of the graft whereas 1 (10%) had complete failure at the glenoid. No correlation existed between MRI healing and the AHD, SHR, strength, ROM, or PROs. American Shoulder and Elbow Surgeons, Western Ontario Rotator Cuff Index, and Disabilities of the Arm, Shoulder and Hand scores all significantly improved from before to 1 year after SCR regardless of graft healing.

Conclusions: The rate of complete or partial graft healing on MRI mimics findings of prior reports in the literature. MRI healing was correlated with humeral head anterior-posterior translation but not with the static and dynamic AHDs, SHR, humeral head superior-inferior translation, ROM, strength, or PROs 1 year after SCR. All PROs improved significantly from before to 1 year after SCR regardless of graft status on MRI. In vivo kinematic changes were small after SCR and not clinically significant, and the data suggest that improvements in clinical and functional outcomes may occur in the absence of full graft healing.