A retrospective review of data from patients who underwent aLDTM tendon transfer between June 2016 and February 2022 was conducted. The study included patients who underwent aLDTM for ASIRCTs with a minimum follow-up period of 2 years. Indications for aLDTM tendon transfer in ASIRCT included persistent pain and/or loss of shoulder function, minimal to no glenohumeral arthritis (Hamada [16] classification grade ≤2) (Fig. 1A), preoperatively confirmed IRCTs involving both the subscapularis and supraspinatus tendons (Goutallier [17] fatty infiltration grade ≥3 on MRI) (Fig. 1B and C), and intraoperatively confirmed presence of intact infraspinatus and teres minor tendons. Exclusion criteria included patients with unavailability for clinical assessment both preoperatively and at final follow-up, less than the minimum follow-up period of 2 years, and loss of follow-up. The patients who met these conditions were then categorized into three groups: group total (all ages), group old (aged 70 years and above), and group young (aged 60 years and below) (Fig. 2).

All surgeries were performed by a single senior surgeon (CHB) and followed the technique described by Baek et al. [18]. The patient underwent general anesthesia, and the procedure was performed in a beach chair. The procedure involved an incision extending from the coracoid process to the inferior border of the PM tendon. Following the standard deltopectoral approach, the reparability of the subscapularis was evaluated. The torn subscapularis was deemed “irreparable” and the transfer procedure began when the subscapularis could not be reduced to its original footprint on the lesser tuberosity. For the long head of the biceps tendon, soft tissue tenodesis was performed. After meticulous dissection of the upper and lower border of the PM muscle, the PM muscle was retracted with a Kolbel retractor to expose the insertion site of the LDTM tendon on the humerus. The LDTM tendon was detached as a single unit without separating the LD and TM tendons (Fig. 3A), and the edges were sutured using non-absorbable sutures in a Krakow fashion (Fig. 3B). After harvesting the LDTM tendon, surrounding adhesions were gently and carefully released using sterile gauze to prevent iatrogenic injury to the radial nerve. During this step, the surgeon carefully avoided forceful medial retraction to prevent iatrogenic injury to the radial nerve passing through the anteroinferior surface of the LDTM muscle. Additionally, sufficient release of the harvested LDTM tendon was performed to enhance tendon mobility and excursion, thereby preventing potential impingement of the axillary nerve due to the bulky volume of the combined LDTM muscle. Harvested LDTM tendon was then passed beneath the PM muscle and pulled towards the greater tuberosity (GT) of the humerus (Fig. 3C). To ensure proper tensioning, the arm was positioned in full internal rotation (IR) at a 45° abduction (ABD). The LDTM tendon was placed approximately 2 cm distal to the GT and lateral to the bicipital groove with a 4.75-mm knotless anchor (Swivelock anchor, Arthrex Inc.). For reinforcement of the attachment of the harvested LDTM tendon to the humerus, a 4.5-mm triple-loaded medial suture anchor (PEEK Corkscrew FT, Arthrex Inc.) was inserted beneath the LDTM tendon along the line of the bicipital groove. These sutures were loaded into two additional 4.75-mm knotless anchors (Swivelock anchor) that were then placed over the harvested LDTM tendon to compress this tendon against the bone. The two knotless anchors were positioned, one medial and the other lateral to the bicipital groove (Fig. 3D). In patients with osteoporotic bones, medial anchor sutures were threaded through the harvested LDTM tendon and fixed with two knotless anchors in the same fashion. A thorough assessment was performed to ensure no impingement was encountered by rotating the humerus.

During the initial 4 weeks post-surgery, patients wore an ABD brace while maintaining an IR posture to aid in proper alignment and stability during the early healing stages. Patients were allowed intermittent movement of the elbow, wrist, and fingers while wearing the brace for daily activities. The use of the brace was discontinued after this initial 4 weeks, and patients began active-assisted range of motion (ROM) exercises to regain motion. At 3 months postoperatively, patients progressed to strengthening exercises encompassing all movement directions. However, engagement in active physical labor and sports activities was restricted until 6 months post-surgery.

We gathered data on age, sex, body mass index (BMI), medical comorbidities, smoking status, duration of symptoms, and follow-up. Clinical assessments included pain measurement using a visual analog scale (VAS) ranging from 0 to 10, shoulder function assessment using the American Shoulder and Elbow Surgeons (ASES) score, and patient satisfaction using the Single Assessment Numeric Evaluation (SANE) score. Shoulder aROM was measured using a goniometer, and any documented complications were recorded. Shoulder strength was assessed using a handheld dynamometer (Hoggan Health Industries) both preoperatively and postoperatively.

Radiological assessments included the acromiohumeral distance (AHD) and the Hamada [16] classification system score to evaluate presence of glenohumeral joint arthritis. MRI scans were used to assess the quality of the rotator cuff muscles using the Goutallier [17] grading system. The integrity of the transferred tendon was evaluated through MRI scans (Fig. 4), with a discontinuity indicating retear, according to the criteria established by Sugaya et al. [19] in which types IV and V were considered retear due to the loss of continuity of the transferred tendon. An independent musculoskeletal radiologist, unaware of the clinical results, analyzed the MRI findings.

Comparisons within groups for preoperative and postoperative results were performed using paired t-tests and Wilcoxon signed-rank tests for continuous data. Chi-square and Fisher's exact test were used for categorical data assessments. Statistical analyses were conducted using SPSS version 20.0 (IBM Corp.). The intraclass correlation coefficient (ICC) was calculated to assess the reliability of AHD and Hamada grade between two independent examiners. Mean and standard deviation values were reported for the data, and statistical significance level was set at P<0.05.

Fourteen patients were excluded due to unavailable data (n=8) and loss of follow-up (n=6), resulting in a final enrollment of 123 patients in the Group Total. Thirty-nine patients were in the group young (age ≤60 years), and 27 patients were in the group old (age ≥ 70 years). Table 1 presents the demographic and clinical characteristics of the group young and group old patients. The mean ages for these groups were 56.6±4.9 years (range, 36–60) and 73.6±2.3 years (range, 71–81), respectively. The mean follow-up durations for the two groups were not statistically different, 42.1±15.6 months (range, 24–73) and 43.9±19.8 months (range, 24–76), respectively. There were no significant differences in preoperative demographic factors between the groups, including BMI, sex, medical history, smoking status, and degree of fatty infiltration of each rotator cuff.

Table 2 illustrates the clinical outcomes for the group young and group old patients and the comparison between the groups. Upon comparing preoperative and postoperative clinical outcomes for each group, both demonstrated significant improvements in all clinical scores, including VAS, ASES, and SANE scores, with all P-values <0.001. Regarding aROM, both groups showed significant improvements in forward elevation (FE), ABD, and IR at the back. However, there was no significant improvement in external rotation (ER) at the side observed in either group. When assessing radiological parameters, excellent ICCs were found for AHD and Hamada classification (ICC: preoperative AHD, 0.977; final AHD, 0.977; preoperative Hamada, 0.718; and final Hamada, 0.791). Both groups showed no significant progression of arthritis. When comparing group young and group old, no significant differences were observed in VAS, ASES, and SANE scores. Similarly, there were no significant differences in aROM and radiological parameters between the groups.

Table 3 presents the strength data for group young and group old and the comparison between the groups. Preoperative and postoperative strength showed significant improvements in FE, ABD, and IR at the side for both groups. Strength for ER at the side slightly improved, but the degree of improvement did not reach significance for either group. When comparing between the groups, preoperative strengths for all directions except for ER at the side were significantly higher in the group young than in the group old, with all P-values <0.001. Similarly, postoperative strengths were significantly higher in the group young than in the group old in all directions except for ER at the side. However, the comparison of the delta values, the difference between the preoperative and postoperative values, for each direction between the groups showed no significant differences (FE, P=0.222; ABD, P=0.285; ER at the side, P=0.861; and IR at the side, P=0.060).

Table 4 presents the comparisons between group total and group young and between group total and group old. No significant differences in demographic information were observed except for the age difference. When comparing group young and group old to the entire cohort, both exhibited comparable results. No significant differences were observed in VAS, ASES, and SANE scores. For both group young and group old, aROM showed no significant difference when compared to the entire cohort. Also, radiological assessments, including AHD and Hamada classification, were similar between group young and group old and the entire cohort.

Table 5 shows rates of complications in all three groups. Re-tear and postoperative infection rates were similar in all three groups. Both group young and group old had one patient requiring revision LDTM surgery due to retear of the transferred tendon. One patient in group young and two patients in group old required conversion to RTSA due to advanced osteoarthritis and retear.