Although recent clinical results of arthroscopic rotator cuff repair (RCR) have been encouraging, achieving anatomical healing of full-thickness rotator cuff tears remains a challenge.1-4 Several factors influence rotator cuff healing after repair.1,3-8 Patient-related factors include advanced patient age, tear size, tear chronicity, and amount of fatty infiltration.1,3,5,6,8-10 Tension applied to the repair construct is a significant factor as well.11,12
In the literature, limited consideration has been given to repair tension.13 The majority of studies have focused on other factors, mainly repair technique. Some surgeons advocate use of a double-row repair construct in which the rotator cuff tendon is pulled to the lateral margin of the footprint.14-19 Double-row techniques, which include the transosseous-equivalent (TOE) construct, are biomechanically superior to other repairs.20-26 Another purported benefit of double-row repair is more complete restoration and pressurization of the rotator cuff footprint.21,24,27,28
Rotator cuff tears typically occur near the dysvascular region of the diseased musculotendinous unit, often leaving a stump of tissue attached to the tuberosity and ultimately a shortened tendon.29 In addition, full-thickness tears often retract over time. Meyer and colleagues29 recently demonstrated that this shortening is irreversible. Snyder30 and Sostak and colleagues31 suggested that pulling a shortened, degenerative rotator cuff tendon to the lateral margin of the footprint results in increased tissue tension compared with that produced with a more medially based repair just off the articular margin. In our opinion, the possible increase in tension during a laterally based repair, whether single- or double-row, may place excessive strain on the diseased tissue as well as the surgical construct, potentially contributing to repair failure.
We conducted a study to evaluate the difference, if any, in tension applied to the rotator cuff tendon positioned at the medial versus lateral margin of the footprint during arthroscopic RCR. We hypothesized significantly more tension would be placed on the rotator cuff tendon when positioned at the lateral versus medial footprint.
Methods
After obtaining Institutional Review Board approval for this study, we collected data on a consecutive series of patients who underwent arthroscopic RCR performed by Dr. Getelman at a single institution. Only patients with primary full-thickness tears of the supraspinatus and/or infraspinatus were included. Exclusion criteria included revision rotator cuff surgeries, partial-thickness tears, concurrent subscapularis tears requiring anchor fixation, and any tears that could not be mobilized to the lateral footprint without interval slides or margin convergence. The 20 identified patients constituted the study group.
Demographic factors, including age and preoperative length of symptoms, were recorded after chart review. Magnetic resonance imaging (MRI) was performed for all patients before surgery and was retrospectively reviewed. Dr. Getelman assigned each patient a modified Goutallier score, based on MRI, to assess for fatty infiltration/atrophy.32 Each patient was placed in the lateral decubitus position with the operative arm in balanced suspension at 70° of abduction. Standard glenohumeral and subacromial diagnostic arthroscopy was performed. The rotator cuff tear was gently debrided back to a healthy-appearing margin in preparation for repair. The tear was then measured in the anterior-posterior (A-P) and medial-lateral (M-L) planes using a premeasured, marked suture, as previously described.33 Complete bursal and articular-sided releases were performed to allow for appropriate mobilization of the tendon. The tear was classified as crescent-shaped, U-shaped, or L-shaped.
Viewing from the posterior portal, the surgeon inserted a tissue grasper through the lateral portal. The tendon was grasped at multiple points along its edge, anterior to posterior, and was translated laterally to assess its reducibility; the apex of the tear correlated with the point of maximal excursion and coverage of the footprint. Once confirmed, the rotator cuff tear apex was clamped with a tissue grasper. After placement in a sterile arthroscopic camera sleeve (DeRoyal camera drape with perforated tip), a calibrated digital weigh scale (American Weigh Scales model H22 portable electronic hanging scale, with accuracy of 0.01 lb) was attached to the tissue grasper with an S-hook (Figure 1). The tendon edge was first translated about 3 mm lateral to the articular margin (the medial footprint position), and tension was recorded (Figures 2A, 2B). After a 1-minute relaxation period, the tendon edge was translated to the lateral edge of the rotator cuff footprint (the lateral footprint position), and tension was recorded again (Figures 2C, 2D). A medially based single-row RCR with triple-loaded sutures and bone marrow vents placed in the lateral tuberosity was then completed, regardless of tension, tear size, or tear morphology.31 Typically, 1 anchor was used for every 10 to 15 mm of A-P tear length.
SAS software was used for statistical analysis, the Wilcoxon signed rank test for continuous or ordinal data comparisons between paired groups, and the Mann-Whitney test for continuous or ordinal data comparisons between independent, unmatched groups. One-way analysis of variance (ANOVA) was used to compare means among the 3 groups of morphology subtypes. Linear regression was performed to assess the simultaneous relationship between potential predictors (age, sex, length of symptoms, Goutallier score, tear size) and medial or lateral tension, where medial tension was included as an additional potential predictor for lateral tension. Restricted cubic splines were fit to assess linearity. Predictors were retained in multivariate regression using backward variable retention. Because of inadequate sample size, additivity was assumed except for sex. Statistical significance was set at P < .05.