Rotator cuff repair has undergone important development during the past century, transitioning from open surgical techniques to minimally invasive arthroscopic methods. Initial treatments for rotator cuff tears focused on nonoperative methods, primarily physical therapy and pain management. In 1934, Codman first described rotator cuff pathology and introduced surgical repair as a treatment option, laying the groundwork for advances in shoulder surgery [1]. During the 1960s and 1970s, Neer identified the role of subacromial impingement in rotator cuff disease, leading to the development of open subacromial decompression as a standard surgical intervention [2]. Open rotator cuff repairs, though effective, require large incisions and are associated with prolonged recovery periods and high complication rates. The 1980s saw the advent of arthroscopic techniques. Pioneers such as Burkhart and Snyder standardized these minimally invasive methods that offered reduced postoperative pain, faster recovery times, and improved cosmetic outcomes compared with the open technique [3,4]. Arthroscopic repair techniques became increasingly popular, establishing a foundation for further innovations.

The single-row and double-row arthroscopic repair techniques were introduced in the 1990s, and focus on optimizing biomechanical strength and healing outcomes. Single-row repairs were initially favored for their simplicity, but double-row repairs demonstrated superior footprint restoration and biomechanical stability in many cases [5]. Advances in suture anchors and materials in the early 2000s further enhanced repair strength and reduced retear rates.

In recent years, biological augmentation has emerged as a promising adjunct to surgical repair. Techniques such as platelet-rich plasma (PRP) injections and stem cell therapies have been explored to enhance tissue healing, particularly in cases of large or complex tears. These developments represent a shift toward improving both structural integrity and biological healing in rotator cuff repair [6]. Challenges such as high retear rates, uncertain rehabilitation protocols, and management of massive or irreparable tears are areas of ongoing research and innovation.

Rotator cuff repair encompasses a wide range of techniques, enabling personalized treatment tailored to patient pathology and surgeon preferences. Over time, these techniques have been developed from simple approaches to advanced methods that incorporate both biomechanical and biological considerations. Single-row repair is one of the most established techniques, involving the arrangement of sutures in a single horizontal row to restore the footprint of the rotator cuff. This method is relatively simple, time-efficient, and cost-effective. However, single-row repair does not fully restore the native footprint and can lead to stress concentration at the repair site [7].

Therefore, double-row repair was developed to address the limitations of single-row repair. Using two rows of sutures, this technique effectively restores the footprint and distributes stress more evenly, enhancing biomechanical stability. Double-row repair is especially advantageous for medium to large tears, with studies demonstrating improved long-term outcomes compared with single-row repair. However, it is more technically demanding, time-consuming, and expensive than the simpler single-row technique [8].

The transosseous-equivalent technique (TOE), also known as bridge repair, is a modern approach that further reduces stress on the repair site compared to standard double-row repair by adjusting the spacing of the sutures, maximizing healing of rotator cuff tissue [9]. Partial-thickness rotator cuff tears (PTRCTs) can be addressed using techniques such as margin convergence and medialized repair. Margin convergence involves approximating the free tendon edges to reduce the tear size and tension, facilitating anatomical repair. This method has demonstrated excellent clinical outcomes and healing rates [10]. Medialized repair shifts the tendon attachment medially to decrease tension at the repair site, which can be beneficial in cases with significant retraction or poor tissue quality. This approach has shown favorable mid-term outcomes in repairing large-to-massive rotator cuff tears [11].

To enhance biomechanical stability and promote biological healing, patch augmentation techniques are used. Materials such as acellular dermal matrix patches can reinforce the repair and support tissue regeneration. Clinical studies have reported significant improvements in patient-reported outcomes and increased tendon thickness with the use of bio-inductive collagen patches [12]. Modern repair techniques focus on improving mechanical strength and individualizing treatment strategies to optimize the outcomes of each patient.

The single-row and double-row suture techniques are most commonly used for rotator cuff repair, and they have distinct advantages and limitations. The choice of repair technique depends on the specific characteristics of the tear and the surgeon's preferences, and numerous studies have compared these methods in terms of biomechanical stability and clinical outcomes.

Single-row repair is a simpler technique with shorter operative times and lower technical demands than double-row repair. Sutures are arranged in a single horizontal row, and this method is suitable for small tears or cases with good tissue quality [13]. Using this technique, basic stitches such as simple sutures or mattress sutures are often outperformed biomechanically by advanced constructs such as anterior-posterior stitches or medial-lateral stitches. The rip-stop, lasso loop, modified Mason-Allen, and massive cuff stitch techniques have shown performance superior to that of simple or mattress repair constructs in resisting failure [14].

Double-row repair was developed to address the limitations of single-row repair. Double-row techniques use two rows of sutures to more effectively restore the rotator cuff footprint, enhance tendon-to-bone contact, and distribute mechanical stress evenly across the repair site. This approach has demonstrated biomechanical stability superior to that of single-row repair, particularly in terms of initial fixation strength and load-sharing properties [15].

Numerous studies have compared the clinical outcomes of single-row and double-row rotator cuff repairs, primarily focusing on healing rates and retear rates as assessed through imaging, as well as functional outcomes measured using scales such as the American Shoulder and Elbow Surgeons (ASES) score, the Constant-Murley score, the Shoulder Strength Index (SSI), and the University of California Los Angeles (UCLA) score (Table 1).

Several studies have demonstrated that double-row repair offers significantly better healing rates and retear rates than single-row repair [16-18]. However, some studies reported no significant differences between the two techniques [19-21]. When Lapner et al. [22] compared their intact and retear groups at the final follow-up, they found that smaller tears and double-row sutures were associated with higher healing rates than larger tears and single-row sutures. Similarly, Plachel et al. [23] reported that, even after more than 10 years of follow-up, double-row repair showed lower retear rates and slightly superior tendon integrity than single-row repairs. Núñez et al. [24] performed a meta-analysis of randomized controlled trials and also concluded that double-row repairs offered higher healing rates and lower retear rates than single-row repairs.

Functional outcomes were compared using ASES, Constant-Murley, SSI, and UCLA scores. Interestingly, most studies found no significant differences in functional outcomes, irrespective of the healing and retear rates (Table 1). However, studies by Park et al. [18] and Ma et al. [21] reported better functional outcomes with double-row repair for large tears (>3 cm). Núñez’s meta-analysis [24] also found no significant differences in ASES and Constant-Murley scales but reported superior UCLA score for double-row repairs.

Several studies have evaluated the clinical outcomes of various double-row repair techniques. Rhee et al. [25] compared the outcomes of knotless TOE (suture bridge) repairs incorporating a medial-row Mason-Allen equivalent with those of knotted medial-row TOE repairs. They found that the knotless technique had a significantly lower retear rate of 6%, compared with 19% in the knotted group. Similarly, Ryu et al. [26] investigated the effects of adding lateral-row stitches to a standard suture bridge repair to address dog ears. This modification was shown to enhance healing rates compared with the conventional suture bridge construct. In contrast, Kim et al. [27] observed no significant differences in retear rates or clinical outcomes between the standard double-row and TOE techniques, indicating that the approaches offer comparable efficacy in certain contexts.

Early suture anchors were primarily made of metal, with titanium and stainless steel being the most common. Titanium is strong and lightweight and forms a calcium-phosphate surface layer that enhances osseointegration with minimal inflammatory response. Conversely, stainless steel anchors often cause fibrous encapsulation and inflammatory cell infiltration. Despite their rigidity and long-term use, metal anchors are associated with complications such as migration, joint cavity incarceration, cartilage damage, and imaging interference and can release metal ions into surrounding tissues [28].

Therefore, biodegradable anchors composed of materials such as poly-L-lactic acid and copolymers such as poly-lactic-co-glycolic acid have been introduced and offer better imaging compatibility and reduced need for removal. However, early biodegradable anchors, particularly those of polyglycolic acid, degraded too quickly, leading to inflammatory reactions. Modern biocomposite anchors incorporate materials such as beta-tricalcium phosphate to enhance osteoconductivity while maintaining controlled degradation. These advances allow better bone integration than was possible with metal anchors and minimize complications such as osteolysis or cyst formation while still ensuring adequate fixation during the healing process [29].

Advances in suture materials have significantly enhanced the efficacy of rotator cuff and other shoulder surgeries. Traditional monofilament sutures, such as nylon and polyester, often exhibited limitations in tensile strength and knot security that could compromise surgical outcomes. Therefore, modern sutures are made from ultra-high-molecular-weight polyethylene fibers. These sutures offer superior tensile strength and improved handling characteristics compared with earlier materials, facilitating easier knot tying and reducing tissue damage during surgery [30].

Restoring the anatomical footprint is a cornerstone of rotator cuff repair. The goal is to re-establish tendon-to-bone contact while ensuring uniform pressure distribution for optimal healing. Compared with single-row repair, double-row repair more closely restores the anatomy of the repair site, enhancing tendon-to-bone healing. According to Kim et al. [7], double-row repair significantly improves the initial strength of the repair and reduces gap formation compared with single-row repair. Similarly, Park et al. [31] demonstrated that the transosseous tunnel rotator cuff repair technique generates significantly larger contact area and greater pressure distribution across the footprint than suture anchor techniques, suggesting that it might facilitate stronger and faster rotator cuff healing. However, although increased contact area can enhance biological healing, some studies indicate that footprint restoration alone does not guarantee superior functional outcomes [16,18].

Stress concentration is particularly pronounced at the tendon–bone interface and the suture–tendon junction, areas commonly associated with repair failures. Biomechanical analyses have shown that the single-row and double-row suture anchor techniques often generate high stress within the tendon, especially around the places where sutures pass through the tissue [32]. This stress concentration can weaken the already compromised biomechanical properties of degenerated tendons, increasing the likelihood of failure during the healing process. For instance, Cummins and Murrell [33] reported that most revision rotator cuff repairs using suture anchors failed at the tendon–suture interface, highlighting it as a critical weak point in rotator cuff repair.

Interestingly, the transosseous technique displayed a distinct stress distribution pattern [32]. Unlike suture anchors, which concentrate stress along the tendon–bursal surface, transosseous fixation localizes stress at the site where the suture passes through the bony trough. Although that suggests a lower risk of tendon–suture failure, it also indicates that the suture thread itself could be a potential weak point in this technique.

Re-tear after rotator cuff repair is a commonly reported complication, with incidence rates ranging from 13% to 94% [34]. Various risk factors contribute to retear rates, both patient factors such as age, systemic diseases, tear size, and tissue quality and the chosen surgical techniques and rehabilitation protocols. Increasing age in rotator cuff tear patients is associated with higher retear rates following rotator cuff repair. Diebold et al. [35] analyzed retear rates in 1,600 patients based on age and reported retear rates of 5% in patients younger than 50 years and 34% in patients older than 80 years.

Systemic diseases such as diabetes and hyperlipidemia also influence retear rates. In a meta-analysis of seven studies, Zhao et al. [36] reported that diabetes is a significant risk factor for retear following arthroscopic rotator cuff repair. Similarly, in a retrospective study of 85 patients, Garcia et al. [37] observed a significantly higher retear rate in patients with hyperlipidemia. In a study by Chung et al. [38], patients with osteoporosis (bone mineral density T-score <–2.5) exhibited a 7.25-fold higher rate of failure of rotator cuff repair compared with normal controls, and those with osteopenia showed a 4.38-fold higher failure rate.

Tear size and fatty infiltration also affect surgical outcomes after repair. Park et al. [39] reported 339 patients undergoing arthroscopic repair of small- to medium-sized tears and found a healing rate of 89% for tears <2 cm, whereas tears ≥2 cm had a healing rate of only 65%. Fatty infiltration of the muscle belly is an irreversible change, and grade 2 or higher fatty infiltration of the infraspinatus muscle has been associated with high retear rates.

To mitigate this risk, several technical, biological, and rehabilitation strategies have been developed. Rotator cuff healing relies on adequate mechanical stability at the repair site until the tendon-to-bone healing is complete. Double-row and TOE repairs offer biomechanical performance superior to that of single-row techniques [40]. Biomechanical studies have consistently demonstrated that double-row and TOE techniques provide greater tensile strength, load to failure, increased footprint contact area, and higher footprint pressure, as well as improved resistance to gap formation compared to single-row techniques [31]. These advantages contribute to better tendon compression and reduced stress concentration at the tendon–bone interface. The TOE repair technique was specifically developed to address issues such as tendon strangulation, impaired vascularity, and uneven load distribution between anchors. In a systematic review of 2,048 repairs, Hein et al. found significantly lower retear rates with the double-row and TOE techniques compared with single-row repairs across small (1–3 cm), medium (<3 cm), large (>3 cm), and massive (>5 cm) tears [40].

Biological approaches are intended to optimize the healing environment at the repair site and complement mechanical stability. PRP and growth factors such as bone morphogenetic proteins have been shown to promote cellular proliferation, angiogenesis, and tissue regeneration and enhance the tendon-to-bone healing process. Jo et al. [41] conducted a randomized controlled trial to evaluate the effect of PRP on retear rates following arthroscopic repair of large to massive rotator cuff tears. At a minimum follow-up of 9 months, the retear rate in the PRP group (20%) was significantly lower than that in the conventional group (55.6%). Additionally, mesenchymal stem cells (MSCs) have demonstrated potential in improving tendon integrity by facilitating tenocyte differentiation and matrix synthesis [42]. Hernigou et al. [42] studied the effects of bone marrow–derived MSCs used as a biological augmentation in rotator cuff repair. The group that received the MSCs demonstrated better healing rates and lower retear rates than the control group.

The timing of rehabilitation, particularly the initiation of motion, remains a topic of discussion. A systematic review by Saltzman et al. found no significant difference in retear rates between early and delayed motion groups following rotator cuff repair [43]. Early motion was defined as active motion within 6 weeks or passive motion within 3 weeks postoperatively, and delayed motion began no earlier than 3 weeks after surgery. However, subgroup analyses suggested that early motion might lead to significantly higher retear rates in patients with large tears (>3 cm). To balance healing and functional recovery, a 2–4-week period of immobilization, depending on tear size and tissue quality, is generally recommended [5]. Passive motion initiated within the first 6 weeks can help prevent adhesions and stiffness, and then active motion and strengthening exercises are introduced gradually, starting at 6–8 weeks.

Partial and massive rotator cuff tears pose distinct challenges and require tailored surgical strategies. Advances in arthroscopic techniques and biological augmentation have expanded the therapeutic options for these types of tears, allowing improved functional outcomes and healing rates.

Postoperative rehabilitation is a critical component in optimizing the outcomes of rotator cuff repair. Effective rehabilitation aims to protect the repair, minimize complications, and progressively restore shoulder function while respecting the healing process of the repaired tendon. A criterion-based, individualized approach that integrates evidence-based strategies is essential to ensure a balance between tissue protection and functional recovery. Rehabilitation is typically divided into three phases, progressing from protection to mobility and finally strengthening.

Arthroscopic rotator cuff repair has advanced significantly, driven by innovations in surgical techniques, biomaterials, and biomechanics. Strategies to address specific challenges, such as retears, partial-thickness tears, and massive tears, have developed significantly. Although current techniques demonstrate promising results, further research into long-term outcomes, patient-specific approaches, and emerging technologies is crucial to refine treatment strategies, optimize functional recovery, and enhance patient satisfaction.