The estimated prevalence of rotator cuff tears in the US is between 10.9 million and 36 million1, and of these, more than 250,000 require surgical intervention every year2,3. Much attention of the scientific and clinical community has focused on the development of techniques and therapies for the repair of chronic, full-thickness, large to massive rotator cuff (RC) tears, as the incidence of retear and reoperation rate in these cases has been shown to be 27%–40%4,5, and 3%–16%6,7, respectively. However, partial–thickness rotator cuff tears (PTRCTs) affect between 13%–32% of the population8 and may be nearly twice as common as full-thickness RC tears9. PTRCTs can manifest intratendinously or at the articular and/or bursal surfaces and are positively associated with increasing age10,11,12. While PTRCTs often have an asymptomatic, indiscriminate onset, they can progress to causing pain, crepitus, decreased range of motion, and ultimately the development of full-thickness tears13,14. More specifically, Yamanaka and Matsumoto reported that 28% of PTRCTs progressed to full-thickness tears and 80% of tears increased in size over a mean of 1.1 years postoperatively15. Multiple clinical imaging and histological studies reviewed by Matthewson et al. demonstrated that healing of PTRCTs over time is rare14. Taken together, the prevalence and clinical impact of PTRCTs motivate the development of clinical approaches that can reduce pain, disability, and help to attenuate tear propagation in symptomatic patients. The etiology of PTRCTs, propagation, and lack of healing is hypothesized to be due to multiple factors, including both extrinsic (i.e., mechanical) and intrinsic (i.e., tendon biology) influences11. Extrinsic factors can include subacromial impingement and glenohumeral joint instability16,17, as well as repetitive traumatic (i.e., tendon overloading) events18. Intrinsic factors include the relative hypocellularity and avascular nature of the RC tendons19, and the presence of inflammation, which can decrease tendon extracellular matrix (ECM) production concomitant with an increase in the presence of proteases (i.e., matrix metalloproteinases [MMPs]) produced by resident tenocytes that lead to tissue breakdown20. Ultimately, tendon degeneration/tendinopathy can progress, resulting in tissue that does not have the capacity for endogenous repair, eventuating in inferior tendon tissue quality and the potential for tear propagation.
While arthroscopic operative techniques, including debridement, subacromial decompression/acromioplasty, and repair, are used to address extrinsic factors contributing to PTRCTs14, these approaches do not address compromised tendon biology. Thus, augmentation of RC repairs has been of significant clinical interest. The efficacy of autologous blood products, including platelet-rich plasma and bone marrow aspirate concentrate, growth factors, and/or autologous point-of-care cell-based approaches, has been explored to aid in the repair of chronic, large-to-massive RC tears21,22; however, these adjuncts have not been widely investigated for PTRCTs. Reports suggest that the use of augmentation can result in both positive and inconsequential clinical impacts. These conflicting findings may result from several factors, including that autologous product composition and potency depend on the general health and age of the patient from whom they are derived, as well as the inability to target or sequester these therapies at the tendon tear repair site. Taken together, alternative augmentation strategies should be explored that may positively impact tendon biology and healing at the site of PTRCTs, with the goal of improving patient outcomes.
An alternative and underexplored approach to augmenting RC tears is the use of dehydrated human perinatal tissue membrane allografts. Derived from donated placental tissue membranes (i.e., the amnion and chorion) following the birth of full–term healthy babies, these membranes are aseptically cleaned, dehydrated, and cut into sheets of various sizes prior to packaging and undergoing terminal sterilization to achieve a sterility assurance level of 10-6. Perinatal tissue membranes have been used clinically for over 100 years as protective coverings/onlays for a variety of tissue wounds. These membranes, although often devoid of viable cells, contain ECM proteins, growth factors, and cytokines that have been deposited by cells throughout the 9-month gestation period. Basic science research has shown that the composition of these membranes endows the tissue with antiinflammatory, antifibrotic, antimicrobial, proangiogenic, and pro–regenerative properties, while also possessing immune-privileged characteristics23. These membranes and their derivatives have been explored for use in a variety of orthopedic applications24,25. In the context of tendon repair, preclinical studies have demonstrated that perinatal membranes can promote tenocyte migration, proliferation, and ECM production while attenuating the impacts of inflammation and enhanced protease activity26,27,28,29,30. Clinically, perinatal membranes have been used to wrap tendon repair sites, including the Achilles and peroneus tendons31,32; however, clinical reports evaluating the use of these membranes in arthroscopic rotator cuff repair are limited33. The lack of utilization of the perinatal membranes as a matrix to augment arthroscopic RC repair is due in part to the challenges associated with the delivery and securement of these allografts. Despite their therapeutic potential, dehydrated perinatal tissue membrane allografts can be thin and fragile, may not hold suture, and once hydrated can be exceedingly difficult to manipulate and maneuver within the shoulder, particularly during arthroscopic procedures in the presence of fluid.
MLG-COMPLETE is a dehydrated, full-thickness perinatal tissue membrane allograft that contains a continuous and intact amnion, intermediate layer, and chorion that has been designed for use in challenging surgical applications, including robotic, arthroscopic, and minimally invasive procedures34. Its use as a covering/onlay matrix augment for arthroscopic repair has yet to be explored. Thus, the primary objective of this case study was to evaluate the feasibility of arthroscopically delivering and securing the perinatal tissue allograft in patients with PTRCTs.
Case Presentation:
Between April and June 2024, two patients underwent RCR with perinatal tissue membrane allograft matrix augmentation (PTAMA) for bursal-sided, high-grade partial thickness rotator cuff tears (Ellman classification Grade 3 with an estimated involvement between 50%–75% tendon thickness) (Table 1). No near full-thickness or full-thickness tear areas were observed, and thus a full take-down of the partially torn tendons and conventional repair with suture anchors was not deemed necessary by the operating surgeon. Both patients had intact rotator cuff cable, and the tears involved the crescentic portion of the posterior supraspinatus and anterior infraspinatus. This segmental tendon involvement measured approximately 2 cm medial to lateral as well as anterior to posterior.
Surgical intervention was considered reasonable for both patients, as they had attempted a minimum of 6 months of conservative care, including a minimum of two corticosteroid injections in the subacromial space and a supervised physical therapy program for at least 6 weeks. The patients were considered for PTAMA due to persistent symptoms and the inability to return to work (which required occupational overhead reaching and lifting), the presence of a high-grade, bursal-sided partial thickness tear of the supraspinatus and infraspinatus on preoperative MRI (Figure 1), and confirmation of the partial rotator cuff tearing at the time of arthroscopy (Figure 2). Preoperative and postoperative range of motion (ROM), American shoulder and elbow surgeons (ASES) score, visual analogue score (VAS) for pain, and single assessment numeric evaluation (SANE) scores were obtained.
Diagnosis, Assessment, and Plan:
Patient 1 was a 60-year-old male who presented with a high-grade partial tear of the supraspinatus and infraspinatus tendons. Patient 1’s past medical history was notable for hypertension and hypercholesterolemia. The patient was a nonsmoker and was employed as a lineman, a job that required extensive work in an overhead position. The patient’s exam revealed normal active and passive range of motion in the involved shoulder; pain and weakness were noted in an overhead position. More specifically, the preoperative range of motion included forward elevation of 100°, limited by pain, 40° external rotation, and internal rotation to the sacrum. While a normal passive motion was observed, positive impingement signs were noted. Patient 1 underwent 8 months of conservative care, which included two subacromial corticosteroid injections that relieved the pain for approximately 1 month, and 8 weeks of formal physical therapy. Due to recurring pain and inability to perform his job duties, he elected to undergo surgical intervention.
Patient 2 was a 39-year-old otherwise healthy male who presented with a worker’s compensation injury of high-grade partial tears of the supraspinatus and infraspinatus tendons related to repetitive work as an electrician. The patient had pain and weakness with empty can testing but preserved range of motion. More specifically, preoperative range of motion included forward elevation of 120°, limited by pain, 50° external rotation, and internal rotation to the lumbosacral junction. While a normal passive motion was observed, positive impingement signs were noted. The patient underwent 6 months of nonsurgical treatments and light-duty work. Specifically, he had two rounds of subacromial corticosteroid injection with formal physical therapy. The physical therapist reported very little progress in therapy, with continued pain in the overhead position and decreased strength compared to the contralateral side. He elected to have surgery due to an inability to achieve his prior level of work duty.