An Improved Continuous Suturing Technique Using a Suture Hook for Subscapularis Repair

Summary

Subscapularis tendon tears remain challenging in orthopedic surgery. Conventional sutures cause uneven load distribution, while advanced methods improve outcomes but complicate procedures. A unique hybrid technique using a sewing machine-style suture with a single-portal approach is introduced here, offering stronger fixation, reduced trauma, enhanced outcomes, and improved convenience for effective subscapularis repair.

Abstract

Subscapularis tendon injuries often pose substantial challenges in arthroscopic repair, with traditional techniques frequently limited by prolonged surgical time, uneven tension distribution, and increased complication risk. Although advanced suture-passing and suturing methods can improve biomechanical outcomes, they generally require complex instrumentation. A hybrid approach is presented here that integrates a continuous sewing machine-like suture technique with a single-portal spinal needle method for subscapularis repair. The sewing machine-like technique facilitates efficient loop formation, which ensures even tension distribution and allows precise suture placement through flexible puncture points. The single-portal approach minimizes invasiveness, reduces tissue trauma, and streamlines the surgical process. Collectively, these techniques enhance the biomechanical strength, shorten operative time, and align with the principles of modern minimally invasive surgery. This improved and innovative strategy represents a promising alternative to conventional methods, with the potential to improve clinical outcomes. Further clinical validation and long-term follow-up are required to confirm its efficacy.

Introduction

Rotator cuff injuries involving the subscapularis tendon pose significant challenges due to the tendon's unique anatomical position, limited surgical exposure, and critical role in maintaining shoulder stability and function¹. These tears often cause severe pain, functional impairment, and reduced quality of life². Current arthroscopic repair techniques aim to address these challenges but are limited by complex instrumentation, lengthy operative times, and suboptimal biomechanical outcomes. Despite advancements in suture technology and minimally invasive methods, repair of subscapularis tendon tears remains technically demanding.

Traditional suture methods, including interrupted and mattress techniques, have been widely used in arthroscopic rotator cuff repair. While effective in achieving basic tendon fixation, these methods often require multiple portals and extensive tissue manipulation, resulting in prolonged operative times and higher complication risks. Burkhart et al. reported the complexity of dual-portal approaches, highlighting the increased risk of soft tissue damage and longer recovery times associated with these techniques³. Anchor-based techniques, commonly used for their fixation strength, also have limitations such as anchor failure and inability to achieve uniform tension across the tendon, potentially leading to suboptimal healing.

Advanced methods such as the transosseous equivalent suture-bridge technique provide improved footprint coverage and enhanced biomechanical stability⁴. However, this approach often increases technical complexity and risks of overtightening, which may compromise vascular supply and healing potential. These challenges highlight the need for innovative strategies that combine precision, efficiency, and minimal invasiveness.

Prior research introduced the continuous sewing machine-like suture technique, inspired by the mechanical precision and efficiency of sewing machines⁵. This method enables continuous suturing with a loop structure, ensuring even tension distribution and reducing knot-related failures. The technique simplifies the suturing process, improves biomechanical stability, and significantly decreases surgical time and costs. Its application in meniscal repair has demonstrated potential for enhancing clinical outcomes, suggesting utility in rotator cuff repair as well.

Studies on the single-portal approach for subscapularis repair utilizing a spinal needle as a suture passer have highlighted advantages in reducing invasiveness and improving surgical precision⁶. By employing a single anterior portal for visualization and instrumentation, this technique minimizes soft tissue trauma, lowers the risk of neurovascular complications, and streamlines the procedure. Such an approach is particularly advantageous for addressing subscapularis tears, where surgical space is inherently limited.

Although each of these techniques has demonstrated considerable benefits independently, their integration offers a promising solution to the challenges of subscapularis tendon repair. The sewing machine-like suture technique provides robust, efficient, and precise suture placement, while the single-portal approach emphasizes minimal invasiveness and surgical simplicity. Combined, these methodologies create a synergistic effect that enhances biomechanical strength, shortens operative time, and reduces postoperative complications.

Building on previous findings, this study develops and evaluates a surgical protocol that combines the continuous sewing machine-like suture technique with the single-portal approach. The protocol is designed to enhance surgical efficiency, minimize invasiveness, and achieve superior biomechanical outcomes compared with traditional methods. By addressing current limitations in subscapularis repair, this approach aims to establish a new standard for the treatment of subscapularis injuries.

Protocol

All procedures involving human participants were conducted in accordance with the ethical standards of the institutional and/or national research committee and with the principles outlined in the Declaration of Helsinki. Institutional Review Board (IRB) approval was obtained prior to initiation of the study, and written informed consent was obtained from all participants before enrollment. Patient confidentiality and privacy were strictly maintained throughout the study.

1. Preoperative preparation

1. MRI examination: Perform an MRI of the affected shoulder preoperatively to assess the extent of rotator cuff damage.
2. Additional imaging: Perform a CT scan and X-ray of the shoulder joint to identify microfractures, dislocations, or other pathological changes.
3. Patient medical history: Evaluate age and underlying conditions, such as hypertension or diabetes, during the preoperative assessment to guide postoperative rehabilitation planning and expected outcomes.

2. Anesthesia

1. Perform the procedure under general anesthesia combined with a brachial plexus block (interscalene block) (following institutionally approved protocols).
2. Use general anesthesia as the preferred choice, unless contraindicated, since it provides better muscle relaxation during the procedure.

3. Medication and intraoperative measures

1. Antibiotic prophylaxis: Administer prophylactic antibiotics, such as cefazolin sodium (1 g), 30 min before surgery to prevent infection.
2. Nutritional support: Provide nutritional support preoperatively if necessary.
3. Arterial and central venous lines: Assess the need for arterial and central venous line placement based on condition and expected surgical duration.

4. Patient positioning

1. Position the patient in the lateral decubitus position with the affected arm in traction.
2. Hang a 5 kg weight on the arm and place the shoulder at 50° abduction and 15° forward flexion.

5. Surgical portal setup

1. Disinfect and drape the surgical area. Establish a posterior portal for observation and insert a 30° arthroscope to visualize the glenohumeral joint.
2. Create an anterior portal for the operative approach. Use a radiofrequency (RF) device through the anterior portal to clean the rotator cuff interval and clearly expose the torn tendon.

6. Surgical procedure

1. Tear assessment
   1. Use the posterior portal to evaluate the extent of the rotator cuff tear. Freshen the bone bed at the tendon attachment site with a bone planer to prepare a healthy bone surface and remove damaged tissue.
2. Suture hook preparation and first set of continuous sutures
   1. Refer to the representative results for an illustration of the suture process. Prepare the suture hook, load high-strength suture through the hook's eye, and leave a portion of the suture at the hook's head to form a loop structure. Insert the suture hook through the anterior portal and guide it to the tear site. Perform the first pass through the tendon tissue.
   2. Introduce a clamp through the anterior portal to grasp the suture loop, then pull the free end of the suture out of the hook. Create a small lateral incision if necessary to facilitate clamp operation. Withdraw the suture hook slowly while maintaining the suture inside the hook, and perform a second pass through the tendon.
   3. Hold the suture loop with the clamp, then pass the free end of the suture through the loop. Continue suturing as needed, ensuring multiple passes to stabilize the tendon with an enhanced suture structure.
3. Second set of continuous sutures or additional sutures
   1. Place a second set of sutures to achieve parachute fixation of the rotator cuff. Select an appropriate location for the second set and repeat the same process as the first set, adjusting the number of passes based on tissue condition and repair requirements.
4. Suture fixation
   1. Gather all free ends of the sutures and fix them with anchor devices. Place anchors before completing the sutures and tie knots after sutures are placed to ensure secure fixation.
5. Final arthroscopic evaluation
   1. Use the arthroscope to confirm the quality of the repair. Verify that sutures are evenly distributed, knots are secure, and there is no suture slippage or interference.

7. Postoperative care, rehabilitation recommendations, and follow-up

1. Skin closure: Close skin incisions in layers and dress the surgical area with pressure bandages.
2. Rehabilitation: Design the postoperative rehabilitation plan according to the condition. Instruct wearing of a shoulder immobilizer for 4-6 weeks. Progress rehabilitation gradually: begin with fist clenching, wrist flexion and extension, and elbow flexion and extension, followed by progressive shoulder joint functional exercises to restore function.
3. Follow-up: Schedule a follow-up visit one month postoperatively for clinical examination and functional assessment. Perform an MRI to assess rotator cuff healing.

Results

Preoperative imaging and diagnosis

A preoperative MRI examination of the patient revealed a tear in the superior 1/3 of the subscapular tendon and a tear in the supraspinatus tendon. These findings were critical in guiding the surgical approach and determining the extent of the tendon damage (Figure 1).

Arthroscopic confirmation and portal setup

Arthroscopic examination confirmed the supraspinatus tendon tear requiring surgical repair. The posterior portal serves as the observation portal, while the anterior portal is the operative portal. The red arrow indicates the damaged area of the supraspinatus tendon, which was identified during the arthroscopic procedure (Figure 2).

Bone bed freshening

The planner is used to freshen the bone bed and remove damaged soft tissue in preparation for tendon reattachment. The red arrows indicate the freshening process of the bone bed. This step is crucial for preparing a stable surface for tendon fixation (Figure 3).

First set of sutures - continuous suturing technique

The process of performing the first set of continuous sutures, involving three punctures: (1) The suture hook, loaded with high-strength sutures (orange arrows), is inserted through the anterior portal to prepare for tendon repair (blue arrows indicate the torn tendon); (2) The suture hook passes through the tendon for the first puncture. The clamp (yellow arrow) is used to secure the suture loop; (3) The clamp pulls the free end of the suture loop out from the suture hook. The high-strength suture inside the suture hook remains in place. The suture hook is slowly withdrawn; (4) A second puncture is made at a different location to anchor the suture properly; (5) The clamp holds the suture loop at the hook's head, and the high-strength suture from the first puncture is passed through the loop; (6) The high-strength suture inside the hook remains in place. The red arrows indicate the suture loop structure; (7) The suture is tightened, and the sutures form a secure repair; (8) The third puncture is made, and the points of entry from all three punctures form a stable triangular structure (Figure 4 and Figure 5).

Second set of sutures

The second set of sutures is placed to provide additional support and secure the tendon repair. The location for the second set of sutures is selected adjacent to the first set of sutures, indicated by the blue box. The first puncture of the second suture set is performed, and the clamp (green arrow) grabs the free end of the suture (red arrow). After the second puncture, the clamp pulls the other end of the high-strength suture from the suture hook. After both sets of sutures are placed, the tendon is securely held in place, and the repair is ready for fixation (Figure 6).

Fixation with anchors

The sutures are fixed in place using anchors to ensure the tendon remains securely attached. The green box highlights the two sets of high-strength sutures that are used for the repair. The orange arrow indicates the supraspinatus tendon, which has been securely reattached using the anchors (Figure 7).

Postoperative MRI follow-up

One month after surgery, the patient underwent a follow-up MRI, which showed satisfactory healing of the supraspinatus tendon repair. The MRI images confirmed the tendon was well-healed with no signs of re-tearing or complications at the surgical site (Figure 8).

Figure 1: Preoperative MRI examination. MRI showing a tear of the superior one-third of the subscapularis tendon and a tear of the supraspinatus tendon. Please click here to view a larger version of this figure.

Figure 2: Arthroscopic examination. Confirmation of supraspinatus tendon tear requiring surgical repair. The posterior portal served as the observation portal, while the anterior portal served as the operative portal. The red arrow indicates the damaged area of the supraspinatus tendon. Please click here to view a larger version of this figure.

Figure 3: Preparation of the bone bed. Planning and freshening of the bone bed with removal of damaged soft tissue. Red arrows indicate the bone bed freshening process. Please click here to view a larger version of this figure.

Figure 4: First set of sutures. Continuous suturing with three punctures. (A) A suture hook, loaded with high-strength sutures (orange arrows), inserted through the anterior portal into the shoulder joint to prepare for tendon repair (blue arrows indicate the torn tendon). (B) Passage of the suture hook through the tendon for the first puncture. A clamp (yellow arrow) grasps the suture loop. (C) The clamp pulls the free end of the suture loop from the hook, while the high-strength suture inside the hook remains in place; the hook is slowly withdrawn. The blue box represents the free end of the suture outside the hook. (D) Second puncture made at a different site. (E,F) The clamp holds the suture loop at the hook head, and the high-strength suture from the first puncture passes through the loop. The retained high-strength suture is shown, with red arrows indicating the loop structure. (G) Effect after tightening the suture. (H) Third puncture performed, with all three puncture sites forming a stable triangular configuration. Please click here to view a larger version of this figure.

Figure 5: Outcome after the first set of sutures. Result of the first continuous suture set, showing secure reattachment of the tendon. Sutures are evenly distributed, providing stable fixation and reinforcement for a strong repair. Please click here to view a larger version of this figure.

Figure 6: Second set of sutures. (A) Placement of the second suture set adjacent to the first (blue box indicates the location of the first set). (B,C) First puncture of the second set, with a clamp (green arrow) used to pull the free end of the suture from the hook (red arrow). (D) After the second puncture, the clamp pulls the opposite end of the high-strength suture from the hook. (E) Final result after both sets of sutures are in place, showing secure tendon fixation supported by both suture sets. Please click here to view a larger version of this figure.

Figure 7: Fixation with anchors. Anchors used to secure the sutures. The green box shows the two sets of high-strength sutures. The orange arrow points to the supraspinatus tendon, which is firmly reattached and stabilized by the anchors. Please click here to view a larger version of this figure.

Figure 8: Postoperative MRI follow-up at one month. MRI obtained one month postoperatively showing satisfactory healing of the supraspinatus tendon. The tendon appears well-repaired, without evidence of re-tearing or complications. The joint remains stable, confirming surgical success. Please click here to view a larger version of this figure.

Discussion

The repair of subscapularis tendon tears remains a technically challenging endeavor due to the tendon's deep-seated anatomical position and critical biomechanical role. While traditional suture techniques provide satisfactory outcomes in many cases, their limitations highlight the need for innovation in this domain. The improved technique, combining the continuous sewing machine-like suture method with a single-portal approach, offers a promising alternative that addresses some of the key limitations associated with existing methods.

The continuous sewing machine-like suture technique is designed to enhance biomechanical stability by creating evenly distributed tension across the tendon repair site. The sewing machine-like suture method simplifies the suturing process by enabling continuous stitching, which reduces the number of knots and minimizes potential weak points. This approach not only enhances the repair's mechanical integrity but also reduces the time required for knot tying, addressing one of the key limitations of conventional double-row and transosseous equivalent techniques. Meanwhile, the single-portal approach, which utilizes a spinal needle as a suture passer, significantly reduces invasiveness compared to dual-portal and transosseous techniques. Dual-portal approaches, while effective, often require extensive tissue manipulation and carry a higher risk of complications such as soft tissue trauma and neurovascular injury. In the previous report, the method of suturing with a spinal needle through a single portal, although it achieved a smaller incision, was not able to achieve free continuous suturing due to the lack of angle in the spinal needle. Previous reports of repairing the meniscus or rotator cuff with a spinal needle were limited to specific types of tears^7,8,9,10. The improved technique presented in this study combines the strengths of these advanced methods while addressing their limitations.

By integrating the biomechanical advantages of continuous suturing with the precision and minimal invasiveness of the single-portal approach, this method provides robust fixation with reduced operative time and material use. Unlike the suture bridge technique, which requires multiple portals and extensive anchor use, the improved method achieves comparable biomechanical strength with a simpler and more cost-effective approach. The integration of these two advanced techniques into a single improved approach represents a significant step forward in subscapularis repair. By addressing some of the inherent limitations of existing methods, this technique aligns with the broader trend toward minimally invasive surgery and precision medicine. Its potential to reduce operative time, enhance biomechanical outcomes, and minimize patient recovery time makes it a valuable addition to the orthopedic surgeon's repertoire.

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
30° Arthroscope	Arthrex	https://www.arthrex.com	Used for arthroscopic visualization of the shoulder joint
Anchor devices	Arthrex	https://www.arthrex.com	Anchors for securing sutures to bone
CT scanner	Siemens	https://www.siemens-healthineers.com	Computed tomography scanner for preoperative bone quality assessment
High-strength sutures (e.g., FiberWire, Ethibond)	Arthrex	https://www.arthrex.com	High-strength sutures for tendon fixation
MRI scanner	Siemens	https://www.siemens-healthineers.com/magnetic-resonance-imaging	Magnetic resonance imaging scanner for preoperative and follow-up evaluation
Radiofrequency (RF) device	Arthrex	https://www.arthrex.com	Used for clearing the rotator cuff interval and soft tissue debridement
Shoulder traction system	Smith & Nephew	https://www.smith-nephew.com	Used for patient positioning and shoulder traction during surgery
Surgical clamps	Medtronic	https://www.medtronic.com/	Used for clamping and assisting with suture handling
Suture hook	Arthrex	https://www.arthrex.com	Used for continuous suture passing during tendon repair