1. Non-Operative Treatment
Given a failure rate of up to 70% after
rotator cuff repair (RCR
) of chronic and massive tears
[15][1] and acknowledging that pain relief and functional improvement do not necessarily correlate with successful structural healing of the tendon
[16][2], non-operative treatment has been proposed as the treatment of choice for atraumatic RCT
[17][3]. In the setting of irreparable
rotator cuff tears (RCTs
), a special physiotherapy concept termed “anterior deltoid re-education” (ADR) has been proposed, which consists of an exercise regimen to rehabilitate the deltoid muscle to compensate for the deficient rotator cuff. This concept has been shown to result in acceptable outcomes in a group of comorbid, elderly patients in combination with subacromial injections of local anesthetics and steroids as well as an oral therapy with non-steroidal anti-inflammatory drugs
[18][4]. More specifically, in a collective of 17 patients (mean age: 80 years), there was a statistically significant improvement in the mean Constant Score, a score combining patient subjective criteria as well as objective functional assessments
[19][5], from 26 points prior to treatment (range, 8–41 points) to 60 points (range, 43–77 points) at a mean follow-up of nine months (
p < 0.05). The range of motion in forward elevation improved from a mean of 40° (range 30–60°) prior to treatment to a mean of 160° (range 150–180°)
[18][4]. However, a recent study investigating patient-reported outcomes after the same concept of ADR in 30 patients with a mean age of 74 years (range 55–89 years) has shown that only 12 patients improved by more than 20 points in the American Shoulder and Elbow Surgeons (ASES) Score, the threshold that is considered a successful non-operative treatment
[20][6]. Persisting pain and kinematic dysfunction of the glenohumeral joint were the most common reasons for failure. In summary, careful patient selection is necessary when non-operative treatment for irreparable RCT is administered, as patients should be willing to accept discomfort and functional deficits of their shoulder in exchange for avoiding the risks of surgery. Non-operative treatment in the management of irreparable RCT is considered to yield the best outcomes in elderly patients with low functional demands or in patients for whom surgical treatment is contraindicated.
2. Arthroscopic Debridement, Tenotomy/Tenodesis of the Long Head of the Biceps Tendon and (Reversed) Subacromial Decompression
Irreparable RCT may also be treated by an arthroscopic debridement of the remaining rotator cuff in combination with a (reversed) subacromial decompression (SAD) and a tenotomy or tenodesis of the
long head of the biceps tendon (LHBT
[21,22,23]) [7][8][9]. While lesions of the LHBT have been identified as a source of persistent pain that can be resolved with LHBT tenotomy, the purpose of arthroscopic SAD is to create a smooth, non-impinging acromiohumeral articulation by creating space, removing osteophytes and bony irregularities. A “reverse SAD”, also known as tuberoplasty, has been introduced in order to protect the coracoacromial ligament—a structure at risk in regular SAD—to prevent an antero-superior escape of the humeral head, while equally ensuring a smooth acromiohumeral articulation
[24,25][10][11]. Debridement combined with (reverse) SAD has been shown to result in decreased pain levels while maintaining residual rotator cuff strength (i.e., no improvement in shoulder strength). Low physical demand, sufficient residual shoulder function, older patient age and pain as the chief complaint are the main indications for arthroscopic debridement combined with (reverse) SAD and LHBT tenotomy/tenodesis. As such, a contemporary study in 19 patients (mean age 68 years) with symptomatic massive RCT reports significant improvements in functional outcomes, with an improvement in ASES Score of more than 30 points and a significant pain relief after arthroscopic debridement with SAD and the tenotomy of the LHBT after a minimum 10-year follow-up
[23][9]. However, in this cohort 26% of patients failed and underwent RTSA during follow-up, emphasizing the importance of careful patient selection and preoperative counseling
[23][9].
3. Partial Rotator Cuff Repair
Even if a complete anatomical repair is impossible, a partial repair of an irreparable RCT is an option to restore the rotator cuff’s force couple, which is created by the subscapularis muscle anteriorly and the infraspinatus and teres minor muscles posteriorly. Even in cases of a torn supraspinatus tendon, a sufficient concavity compression of the humeral head into the glenoid can be obtained by a balanced force couple and thus prevent the superior migration of the humeral head
[26][12]. Several authors have published their short- and mid-term clinical outcomes following partial repairs of massive RCTs. Shon et al.
[27][13] reported patient-reported outcomes after partial repairs of irreparable posterosuperior RCTs combined with or without subscapularis tendon repair in 31 patients preoperatively and at 1 and 2 years after surgery. Despite significant improvements from preoperatively to postoperatively, a slight deterioration was found from 1 to 2 years postoperatively (ASES 76 vs. 74, SST 6.6 vs. 6.1, VAS 2.1 vs. 3.2). In addition, even when considering the initial improvement, subjective patient-reported satisfaction was reported as “rather the same” or “dissatisfied” in 15 patients (48%). Teres minor fatty infiltration was identified as an independent factor affecting patient-reported satisfaction. Slightly better mid-term results were reported by Cuff et al. in 28 patients who underwent partial repairs and LHBT tenotomy at a minimum 5-year follow-up with a satisfaction rate of 75%
[28][14]. Despite significant improvements in ASES Score (47 to 79), SST (5.7 to 9.1) and VAS for pain (6.9 to 1.9) at final follow-up compared to preoperatively, the failure rate was as high as 29%. Of note, failure was defined as an ASES score of <70 points, loss of active elevation over 90° or revision arthroplasty surgery. Summarizing these findings, initial favorable clinical results can be expected in patients whose primary complaints are pain and weakness in the setting of good preoperative shoulder function without prior osteoarthritic changes. However, patients should be counseled that clinical outcomes may deteriorate over time.
4. Tendon Transfers
4.1. Latissimus Dorsi Tendon Transfer
In its physiologic function, the latissimus dorsi muscle-tendon unit acts to adduct, internally rotate and extend the humerus. Its large muscle excursion makes the latissimus dorsi feasible for a muscle transfer procedure
[30][15]. Transferring the muscle-tendon unit from its native anterior insertion at the mid-bicipital groove to posterosuperiorly to the greater tuberosity allows the tendon to close the rotator cuff defect. Furthermore, in this setting, the latissimus acts as an external rotator and a depressor of the humeral head
[31][16], which restores the coronal force couple by taking over the biomechanical function of the posterosuperior rotator cuff tendons and improves glenohumeral function. However, the postoperative results reported after this procedure are variable
[30,32,33,34,35,36,37,38,39,40,41,42][15][17][18][19][20][21][22][23][24][25][26][27]. Most studies evaluating clinical outcomes after LDTTs have reported a significant reduction in pain and an improvement in shoulder function. A systematic review by Namdari et al.
[43][28] analyzed 10 studies between 1992 and 2010 to determine the expected outcomes, outcome predictors and complications of LDTTs. Patients had a frequency-weighted mean adjusted Constant Score of 45.9 preoperatively compared with 73.2 postoperatively (
p < 0.001). Additionally, the frequency-weighted mean active forward elevation improved from 101.9° preoperatively to 137.4° postoperatively (
p < 0.001), while the external rotation improved from 16.8° to 26.7° (
p < 0.001). The overall reported complication rate was 9.5%, including surgical site infection, neurapraxia, hematomas, wound dehiscence and tears of the transferred tendon. Predictors of favorable outcomes included a lower degree of teres minor fatty infiltration, an LDTT as a primary procedure and the presence of an intact subscapularis tendon
[43][28].
4.2. Combined Latissimus Dorsi and Teres Major Tendon Transfer (L’Episcopo Technique)
In 1934, L’Episcopo introduced the combined latissimus dorsi and teres major tendon transfer to regain external rotation in pediatric patients with plexus paralysis. Comparable to isolated LDTT, the transfer of both tendons allows the closing of the rotator cuff defect and allows them act as an external rotator and a humeral head depressor. Especially in patients where the teres minor muscle is already degenerated, the combined teres major and latissimus dorsi tendon transfer might be beneficial to balance the rotator cuff’s compromised force couple
[33][18]. Lichtenberg et al.
[44][29] compared clinical outcomes between isolated LDTT and combined teres major and latissimus dorsi tendon transfer at a mean follow-up of 6 years. Significant improvements in Constant Score and active range of motion were found in 17 patients in each group. However, group comparison showed significantly better active flexion and abduction for patients undergoing isolated LDTT compared to patients undergoing combined teres major and latissimus dorsi tendon transfer. In addition, there was no progression in the degree of rotator cuff arthropathy in patients who underwent isolated LDTT
[44][29]. Combined, these findings suggest it is preferable to rely on the isolated LDTT technique rather than a combined LDTT and teres major tendon transfer as the default technique.
4.3. Lower Trapezius Tendon Transfer (LTTT)
The theoretical advantage of the lower trapezius tendon transfer (LTTT) compared to the LDTT is the synergistic function of the lower trapezius muscle and the infraspinatus muscle, sharing a similar force vector trajectory. Accordingly, both muscles contribute to scapular retraction and glenohumeral external rotation
[45][30]. Compared to the LDTT, the LTTT is considered to be more anatomic, which reduces the need for intensive retraining during the postoperative recovery period. However, as the lower trapezius tendon has a short excursion, an additional tendon graft such as the semitendinosus tendon is required to cover the distance between its native insertion site at the scapular spine and the footprint of the torn rotator cuff at the greater tuberosity
[46][31]. Recently, three studies assessed clinical outcomes of an LTTT as treatment for irreparable posterosuperior RCT
[46,47,48][31][32][33]. In 2016, Elhassan et al.
[48][33] reported the outcomes of 33 patients with an average age of 53 years following LTTT prolonged by Achilles tendon allograft. At an average follow-up of 47 months, 32 patients showed significant improvements in the Subjective Shoulder Value (SSV; 54% preoperatively, 78% postoperatively;
p < 0.01) and Disabilities of Arm, Shoulder and Hand (DASH) Score (52 ± 19 preoperatively, 18 ± 10 postoperatively;
p < 0.01). One patient failed and required shoulder fusion subsequently. All successfully treated patients improved their ability for glenohumeral external rotation. Interestingly, patients with more than 60° of preoperative flexion had more improvement in range of motion than patients with less than 60° of glenohumeral flexion
[48][33]. A more recent study showed similar results in 41 patients undergoing arthroscopically assisted LTTT augmented with an Achilles tendon allograft
[47][32]. At a mean follow-up of 14 months, about 90% of the patients reported significant improvement in all outcome measures, including pain, shoulder motion and patient reported outcomes. Of note, the authors reported eight early complications with four of them being peripheral nerve symptoms due to immobilization in a custom external rotation brace for a total of 6–8 weeks postoperatively. All symptoms resolved spontaneously over a 1–3-month period after removing the brace
[47][32]. Valenti and Werthel
[46][31] investigated 14 patients with a mean age of 62 years undergoing LTTT with semitendinosus tendon augmentation to reconstruct irreparable posterosuperior RCTs. At a minimum 18-month follow-up, all clinical scores improved significantly with the mean Constant Score improving from 35 ± 15 to 60 ± 9 points, mean VAS for pain decreasing from 7 to 2 points and mean SSV improving from 40% to 70%. Two of the 14 patients suffered from minor early complications (hematoma and surgical site infection) requiring revision surgery
[46][31]. Compared to the reconstruction of passive stability by the means of an
superior capsular SCRreconstruction (SCR), the LTTT was superior in terms of functional improvement (ASES score of 84.8 ± 7.6 vs. 76.8 ± 20.3, respectively;
p = 0.045), patient satisfaction, progression of arthritis (SCR: 22.7% vs. with LTTT: 2.8%) and graft integrity (retear rate: SCR 63.6% vs. LTTT: 8.3%) at minimum 2 years follow-up
[49][34].
5. Superior Capsular Reconstruction (SCR)
The SCR has recently been introduced as an alternative treatment for irreparable posterosuperior RCT that is less invasive compared to tendon transfer surgery. Biomechanically, the superior capsule of the glenohumeral joint contributes to static stabilization and is commonly disrupted when the supraspinatus and infraspinatus tendons are injured
[50][35]. The technique of SCR in its current form was developed in Japan by Mihata et al.
[51][36], who used a fascia lata autograft to reconstruct the superior capsule as treatment for an irreparable RCT. Today, a variety of allografts, including human acellular dermal allografts, are available
[52,53][37][38]. In general, the graft prevents the superior migration of the humeral head, thereby maintaining the glenohumeral fulcrum if the force couple is still intact. Commonly accepted contraindications include high-grade glenohumeral OA (Hamada > 2), deltoid weakness, and irreparable subscapularis tears
[54,55][39][40]. The main indications for an SCR include pseudoparesis (defined as active scapular plane abduction of more than 45° and less than 90°), an intact subscapularis tendon or reparable subscapularis tendon tear, and the absence of an external rotation lag sign
[56,57][41][42].
6. Subacromial Biodegradable Spacer
The
subacromial biodegradable spacer (SBS
), also known as the balloon system, is a preshaped spacer made of a copolymer of poly-L-lactide, which biodegrades over approximately 12 months
[63][43]. SBSs are arthroscopically inserted into the subacromial space and filled with saline solution, which subsequently depresses the humeral head. The biomechanical rationale behind performing this procedure in the setting of an irreparable RCT is to improve shoulder function by depressing the humeral head to a more central position on the glenoid, thus restoring the force couple and increasing deltoid load to improve the deltoid lever arm
[11,63,64][43][44][45]. A recent biomechanical study confirmed these assumptions in a cadaveric model of an irreparable supraspinatus tear, showing that a balloon spacer restores intact-state glenohumeral contact pressures at most abduction angles, while also depressing the humeral head and increasing the deltoid load at time zero
[11][44]. Moon et al.
[65][46] summarized existing clinical results in a systematic review of seven outcome studies including 204 shoulders from 200 patients following subacromial spacer implantation due to irreparable posterosuperior RCT with Goutallier stage 3 and 4 fatty infiltration based on magnetic resonance imaging. Contraindications included cuff arthropathy stage Hamada 3 or higher, irreparable subscapularis tears, and pseudoparesis
[66,67,68][47][48][49]. The mean age of patients was 68 years with a mean follow-up time of 19 months. All studies reported consistent and significant improvement in the total Constant Score or ASES Score over the duration of short-term follow-up with mean postoperative scores ranging between 60 and 70 points for the Constant Score and 70 and 80 points for the ASES Score. In a multi-center single-blinded, randomized controlled trial, Verma et al. reported comparable clinical outcomes between partial repairs, yet significantly greater forward elevation during early recovery as well as significantly shorter operating times
[31][16]. However, another recent double-blinded randomized controlled trial comparing the arthroscopic debridement of the subacromial space with biceps tenotomy to an additional insertion of the subacromial balloon favored the group that received debridement and tenotomy only, as this group showed even slightly better outcomes after a 12-month follow-up
[47][32]. Equally critical results were published by Garríguez-Pérez et al. at a comparable follow-up, reporting poor functional and satisfaction rates in a case series of 16 patients
[9][50]. While a failure rate of only 3–13% had been reported at short-term follow-up
[69][51], there are concerns regarding the effect beyond the biodegradation period of the spacer in the absence of mid- to long-term results in the literature to date
[38][23]. This is reflected in single, low volume studies that report a preservation of a clinically relevant improvement in the postoperative outcome in only ~60% of the patients at a mid-term FU of 5 years
[70][52]. In addition, an examination of reported adverse events such as foreign body reactions
[71][53] and the risk of dislocations and more prospective data are needed to examine patient- and RCT-related factors predictive of the success of the procedure, providing more clarity regarding the perceived inconsistency in postoperative outcomes following the implantation of a balloon system in the contemporary literature
[65,72,73][46][54][55].