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Latarjet procedure

The Latarjet procedure is a surgical designed to treat recurrent anterior instability by transferring the , along with its attached conjoined tendon, to the anterior glenoid rim, thereby augmenting glenoid bone stock and providing a dynamic stabilizing "sling effect" from the transferred musculotendinous unit. This procedure addresses the "triple effect" of bone augmentation, soft tissue reinforcement, and subscapularis support to prevent further dislocations, particularly in cases with significant glenoid bone loss exceeding 20-25% of the inferior glenoid diameter. First described by French surgeon Michel Latarjet in 1954 as a bone block transfer to reconstruct the deficient glenoid bumper observed in patients with recurrent dislocations, the procedure was inspired by earlier techniques like those of Eden-Hybinette and involved osteotomizing the coracoid base, positioning it flush against the glenoid neck, and securing it with a single screw while repairing the subscapularis around the graft. Initially performed via an open approach, it has evolved with the advent of arthroscopic methods first reported in 2007, which use multiple portals for coracoid preparation, glenoid drilling, and graft fixation with screws or cortical buttons, offering potentially reduced morbidity while maintaining comparable stability. Indications primarily include anterior instability with substantial bone deficiency, hyperlaxity, or failed prior repairs like Bankart lesions, especially in contact athletes or young patients at high risk for recurrence. Clinical outcomes demonstrate high success rates, with recurrence of below 5% at long-term follow-up (up to 20 years) and graft union in 95-98% of cases, often yielding excellent functional scores such as Rowe scores exceeding 90 points and return to sport in over 90% of athletes. However, complications occur in approximately 6-16% of procedures, including graft (1-2%), (1%), neurovascular injury (e.g., , <1%), and postoperative arthritis (up to 20% at 20 years), with arthroscopic variants showing slightly higher intraoperative risks but lower overall reoperation rates (around 2.6%). Despite these risks, the Latarjet remains a reliable salvage option, supported by preoperative imaging like CT for precise bone loss assessment to optimize results.

Background

History and Development

The Latarjet procedure was originally described by French surgeon in 1954 as a coracoid bone block transfer to address recurrent anterior shoulder dislocations, involving the transplantation of the coracoid process to the anterior glenoid neck to restore stability. This technique, detailed in Latarjet's seminal publication in Lyon Chirurgical, marked a significant advancement over prior methods like the by incorporating the coracoacromial ligament to enhance the "sling effect." Early adoption occurred primarily in Europe during the 1960s and 1970s, with initial clinical reports from French surgeons demonstrating low recurrence rates in small cohorts of patients with chronic instability. Key figures such as contributed foundational studies in the 1980s, refining the procedure's indications and mechanisms through long-term follow-up in European centers, which solidified its role in treating anterior instability with bone deficiency. These French investigations, including Patte's work on the dual bony and soft-tissue stabilization effects, established the procedure as a reliable open technique before its broader dissemination. The procedure evolved toward minimally invasive approaches in the 2000s, with the first all-arthroscopic Latarjet described by Laurent Lafosse in 2007, enabling coracoid transfer via endoscopic portals while preserving the original bone augmentation principles. By 2010, Lafosse's group reported favorable short-term outcomes, spurring global interest and technical modifications. Adoption expanded to North American practices in the subsequent decade, supported by multicenter studies validating its efficacy in high-demand athletes. Recent refinements from 2020 to 2025 have focused on fixation innovations, such as suture-button systems over traditional screws, to reduce hardware-related complications and improve graft integration. Usage has surged, with a 250% increase in Latarjet procedures from 2008 to 2019, reflecting its shift from a niche European intervention to a standard for complex instability cases worldwide.

Indications and Contraindications

The Latarjet procedure is primarily indicated for the treatment of recurrent anterior shoulder instability, particularly in cases involving significant glenoid bone loss exceeding 20-25% of the glenoid surface area. It is also recommended for patients with engaging on the humeral head, where the lesion risks engagement with the glenoid rim during shoulder motion. Additionally, the procedure serves as a revision option following failed prior soft-tissue repairs, such as , especially when capsulolabral tissue quality is poor or recurrence has occurred. Contraindications include active infection at the surgical site, which precludes elective bone transfer procedures due to the risk of graft failure and systemic spread. Severe glenohumeral osteoarthritis is also contraindicated, as the procedure does not address articular degeneration and may exacerbate joint symptoms. The Latarjet is avoided in cases of dominant posterior shoulder instability, irreparable subscapularis tendon tears, or anterior glenoid fractures exceeding 30% involvement, where alternative reconstructions like iliac crest grafting are preferred. Insufficient coracoid bone stock, such as in glenoid defects greater than 35% that cannot be adequately filled by the coracoid graft, represents a relative contraindication, as it compromises graft integration and stability. Other absolute contraindications encompass voluntary dislocations, uncontrolled epilepsy, and massive irreparable rotator cuff tears in patients over 50 years, due to heightened risks of nonunion, subluxation, or poor outcomes. Preoperative assessment involves detailed clinical history to identify patterns of instability, such as multiple dislocation episodes, and physical examination including apprehension and relocation tests to evaluate laxity. Imaging is critical, with three-dimensional computed tomography (CT) scans used to quantify glenoid bone loss via methods like the Sugaya technique and assess coracoid morphology for graft suitability. Magnetic resonance imaging (MRI) or CT arthrography may be employed to evaluate soft-tissue structures, including the rotator cuff and labrum, ensuring no contraindications like irreparable tears. In high-demand patients, such as contact or collision sport athletes, the Latarjet procedure is preferred over soft-tissue repairs like Bankart due to lower recurrence rates in bone-deficient shoulders.

Anatomy and Pathophysiology

Relevant Shoulder Anatomy

The glenohumeral joint is a ball-and-socket synovial joint formed by the articulation of the convex humeral head with the concave glenoid fossa of the scapula. The humeral head is a large, spherical structure that occupies approximately one-third of its surface within the joint at rest, allowing for extensive multiplanar motion including flexion-extension, abduction-adduction, and internal-external rotation. The glenoid fossa is pear-shaped and shallow, with an average bony depth of 5 mm in the superior-inferior direction and 3 mm in the anteroposterior plane, which contributes to the joint's inherent instability but enables wide range of motion. The glenoid labrum is a fibrocartilaginous ring attached circumferentially to the glenoid rim, serving to deepen the fossa by 50% (resulting in an effective depth of approximately 5-7 mm) and expand the articular surface area for better conformity with the humeral head, thereby enhancing joint stability through increased concavity compression. The joint capsule is a loose, fibrous envelope that encloses the glenohumeral articulation, extending from the anatomical neck of the humerus to the glenoid rim and labrum; it is reinforced anteriorly, inferiorly, and posteriorly by the glenohumeral ligaments, which provide passive restraint against dislocation. The coracoid process is a hook-shaped bony projection arising anterolaterally from the superior aspect of the scapular neck, typically measuring 2-3 cm in length and serving as a key attachment site for shoulder stabilizers. It gives origin to the , a conjoined structure comprising the tendons of the and the short head of the , which insert distally on the medial humerus to facilitate arm flexion and adduction. The coracoid's vascular supply arises primarily from branches of the to its vertical portion and from the (including ) to its horizontal portion, ensuring robust perfusion that supports its role as a vascularized bone graft in surgical transfers. Surrounding the coracoid process are critical neurovascular structures, including the subscapularis muscle, which originates from the subscapular fossa on the anterior scapula and inserts on the lesser tubercle of the humerus, forming part of the anterior rotator cuff and providing dynamic anterior stability to the glenohumeral joint. The brachial plexus cords course inferomedially to the coracoid base, in close proximity to the axillary artery and vein, while the axillary nerve emerges from the posterior cord of the plexus, traveling through the axilla anterior to the subscapularis and posterior to the axillary artery before exiting via the quadrangular space to innervate the deltoid and teres minor muscles. Biomechanically, the coracoid acts as a prominent lever arm for muscle attachments, and its transfer exploits its size and vascularity to augment glenoid bony architecture for enhanced shoulder stability.

Anterior Shoulder Instability

Anterior shoulder instability refers to the loss of glenohumeral joint stability where the humeral head displaces anteriorly relative to the glenoid fossa, often resulting from trauma that disrupts the static and dynamic stabilizers of the shoulder. This condition is the most prevalent form of shoulder instability, accounting for approximately 95% of all instability cases. The primary etiology involves traumatic anterior dislocations, which lead to characteristic injuries such as Bankart lesions—an avulsion of the anteroinferior labrum and capsule from the glenoid rim—and engaging Hill-Sachs lesions, which are cortical impressions on the posterosuperolateral humeral head caused by impact against the glenoid rim during dislocation. These events frequently progress to bony Bankart lesions, where a fracture of the anteroinferior glenoid rim accompanies the soft-tissue detachment, and subsequent recurrent dislocations can cause progressive glenoid bone loss through erosion or resorption. Pathophysiologically, these injuries compromise the glenoid's concavity, which normally contributes to joint stability by deepening the articular surface and facilitating the concavity-compression mechanism; bone loss exceeding 20-25% of the glenoid width (traditional threshold) significantly diminishes this stabilizing effect, elevating shear forces across the joint and substantially increasing the risk of recurrent instability, with failure rates reaching up to 67% following soft-tissue repairs in such cases; however, recent studies (as of 2024) suggest critical bone loss may be as low as 13.5%, with higher failure risks even at subcritical levels. The presence of an engaging further exacerbates instability by allowing the humeral defect to override the anterior glenoid rim during arm abduction and external rotation. Key risk factors for developing anterior shoulder instability include young age (particularly under 20 years), male sex, participation in contact or overhead sports, shoulder hyperlaxity, and a history of seizures, all of which predispose individuals to initial and recurrent dislocations due to increased mechanical demands or involuntary contractions. Classification of anterior shoulder instability distinguishes between acute presentations, typically following a single high-energy traumatic event with minimal prior symptoms, and chronic forms characterized by recurrent subluxations or dislocations after multiple episodes. Cases are further categorized by the presence or absence of bone deficiency, where significant glenoid or humeral bone loss (>20%, though recent thresholds as low as 13.5%) indicates a more severe, pathology that alters the joint's biomechanical equilibrium, as opposed to isolated soft-tissue disruptions.

Surgical Technique

Open Latarjet Procedure

The open Latarjet procedure is performed under general anesthesia, often supplemented with an interscalene for postoperative pain control. The patient is positioned in the beach-chair configuration or lateral decubitus to allow access to the anterior , with the affected arm supported to maintain neutral rotation and facilitate fluoroscopic imaging. A deltopectoral incision, measuring 8-10 cm, is made starting from the tip and extending distally toward the axillary crease to expose the deltopectoral interval. The is identified and retracted laterally to preserve it, followed by dissection through the deltopectoral interval using retractors to expose the and . The is mobilized by performing an at its base to harvest a graft approximately 20-25 mm in length from the tip, typically using a 90° oscillating saw or osteotome, while protecting the coracoacromial superiorly and dissecting the inferiorly. The coracoid fragment is then prepared by decorticating its deep surface and two holes approximately 10 mm apart for screw passage. The subscapularis is split horizontally at the junction of its superior two-thirds and inferior one-third to access the glenoid neck, followed by a vertical capsulotomy to expose the anterior glenoid rim. The glenoid bed is decorticated to promote bony union, and the coracoid graft is transferred flush to the glenoid equator, secured with two 4.0-4.5 mm cortical screws directed from anterior to posterior, with fluoroscopy confirming positioning and avoiding intra-articular penetration. Finally, capsulorrhaphy is completed by suturing the capsule to the coracoacromial ligament, and the subscapularis is repaired over the graft. Instrumentation includes osteotomes or oscillating saws for the coracoid osteotomy, 3.2-3.5 mm drill bits with guides for hole preparation, self-retaining and Hohmann retractors for exposure, and for real-time guidance. The procedure typically lasts 60-90 minutes, with average intraoperative blood loss under 100 mL.

Arthroscopic Latarjet Procedure

The arthroscopic Latarjet procedure is a minimally invasive of the classic bone block transfer for anterior shoulder instability, employing endoscopic visualization to enhance while reducing disruption. Performed in a modified beach chair position with the upper body elevated 30° to 45°, the setup utilizes multiple without fixed cannulas for flexible instrument access: a posterior portal for the initial arthroscope insertion, an anterosuperior portal for glenohumeral joint entry, a subscapularis portal for splitting, and an anterolateral portal for exposure and preparation. This configuration allows comprehensive intra- and extra-articular work, with the surgical field draped to expose the sternal center for orientation. Key surgical steps commence with intra-articular glenoid preparation, where the arthroscope is advanced through the posterior portal to identify and freshen the anteroinferior glenoid neck using a burr via the anterior portal, creating a congruent, bleeding bony surface for graft integration. Extra-articular coracoid harvest follows, accessed laterally; the coracoclavicular ligaments are released, the process decorticated, and the coracoid is mobilized by performing an osteotomy at its base (typically 20-25 mm from the tip) using an osteotome, informed by preoperative 3D computed tomography for accurate sizing. The graft is then further prepared with a guide positioned approximately 7 mm inward from the lateral surface of the coracoid for drilling. The mobilized coracoid graft is then transferred through a 360° subscapularis split facilitated by double cannulas or retractors, positioned flush against the glenoid rim under direct visualization, and secured with two 3.5-mm cannulated screws or equivalent hardware, verified for parallelism and depth via fluoroscopy through the lateral portal. This approach offers advantages such as smaller incisions leading to reduced scarring and postoperative , alongside faster functional , with equivalent outcomes to open methods in high-risk cases. Challenges include a steep , often requiring 25 to 30 procedures for proficiency in portal navigation and graft handling, and extended operative times averaging 90 to 120 minutes due to the technical demands of arthroscopic manipulation. From 2020 to 2025, advancements have emphasized fixation innovations to address hardware issues, including suture-button systems with anti-rotation anchors and metal-free options like FiberTape cerclage, which provide comparable biomechanical stability to screws while achieving union rates up to 98% and reducing complications such as osteolysis or imaging artifacts. These techniques, often guided by patient-specific , further refine graft positioning and long-term in arthroscopic settings.

Mechanism of Action

Bone Block Augmentation

The bone block augmentation in the Latarjet procedure involves transferring a segment of the as a vascularized autograft to the anterior-inferior glenoid rim, reconstructing osseous defects and restoring the to prevent engagement between the humeral head and the deficient glenoid edge. The coracoid graft typically measures about 7.6 mm in anteroposterior thickness, providing sufficient stock to extend the glenoid articular surface and achieve near-complete restoration of the native glenoid diameter, with mean filling rates of 102% reported in postoperative assessments. This augmentation is particularly effective for "off-" lesions, where the added bone width realigns the glenoid , reducing the risk of humeral head during motion. The incorporation of the coracoid graft into the glenoid occurs through progressive osseous remodeling and bony , facilitated by the graft's vascular supply from the . Clinical studies report a rate of 96.7% at 3 months postoperatively in arthroscopic techniques and 92-94% at 6 months or overall with optimized fixation methods like suture-buttons, indicating robust healing in the majority of cases. Cadaveric biomechanical evaluations confirm that the bone block markedly enhances glenohumeral stability by increasing resistance to anterior humeral head translation. In models simulating 20% glenoid bone loss, the Latarjet reconstruction reduces anteroinferior translation to levels comparable to the intact , outperforming soft-tissue repairs alone by limiting displacement under load. Optimal graft positioning flush with the glenoid face further maximizes this effect, as medialization can diminish the stabilizing bone buttress. Long-term follow-up reveals potential graft resorption or osteolysis, attributed to stress shielding or biological remodeling, occurring in up to 60% of cases after open procedures. While partial or complete osteolysis affects graft volume over time, it rarely compromises overall , with associated recurrence rates remaining below 2%.

Sling Effect

The sling effect represents a key dynamic component of the Latarjet procedure's stabilizing mechanism, primarily involving the transferred of the . Positioned anterior to the subscapularis tendon after transfer, the functions as a muscular sling that contracts during shoulder and external —the positions most prone to anterior —thereby tensioning the anteroinferior capsule and reinforcing the subscapularis to resist humeral head . This dynamic restraint is most effective when the arm is in vulnerable postures, providing compressive force across the glenohumeral joint to enhance anterior without relying solely on static bony support. The sling effect contributes significantly to the procedure's overall efficacy as part of the "triple effect" described by Patte, which integrates the conjoint tendon's dynamic with the bone block for glenoid augmentation and repair of the anterior capsule to achieve comprehensive joint stabilization. Biomechanical evaluations, including those simulating muscle loading, confirm that the sling effect accounts for the majority of gains, providing 76-77% of the restraining at end-range abduction-external and 51-62% at mid-range positions, thereby markedly reducing anterior humeral translation compared to isolated bone block placement. Electromyographic assessments post-procedure indicate preserved and functionally enhanced subscapularis activity, particularly at 90° , which supports the sling's role in dynamic control and further diminishes anterior translation through coordinated muscle tension. A 2025 confirmed the sling effect's role in enhancing stability through biomechanical and clinical evidence. While the sling effect bolsters joint congruence and overall stability, it may impose a mild trade-off in , with clinical studies reporting an average loss of 10-20° in external rotation at the side, though this does not typically impair daily or athletic performance and is offset by improved joint centering. This limitation arises from the tendon's positioning, which subtly alters subscapularis mechanics, but long-term outcomes demonstrate sustained stability without progressive motion deficits.

Postoperative Management

Immediate Postoperative Care

Following the Latarjet procedure, patients are typically discharged from the hospital within 1 to 2 days, often on the same day for arthroscopic approaches or after an overnight stay to monitor initial recovery and ensure stable . The is immediately immobilized in a or abduction brace to protect the graft and capsular repair. While traditional protocols recommend continuous wear for 4 to 6 weeks except during or prescribed exercises, recent studies (as of 2023) suggest that may be optional in select cases, with no increased risk of complications and comparable functional outcomes. Pain management employs a approach to minimize use, beginning with interscalene nerve blocks that provide analgesia for 8 to 12 hours postoperatively, followed by short-term oral narcotics (e.g., ) taken every 4 hours for the first 1 to 2 days, transitioned to non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen once osseous healing is underway, typically after the initial week to avoid interfering with integration. via ice packs or continuous cold therapy units is applied for 20 to 45 minutes every 2 hours in the first week to reduce swelling and discomfort, with precautions to prevent skin injury. Close monitoring is essential during the initial 0 to 6 weeks to detect complications, including daily wound inspections for signs of such as fever above 101°F, excessive redness, swelling, , or uncontrolled , as well as neurovascular assessments for numbness, weakness, or circulatory issues in the operative arm. Patients are advised to avoid driving or prolonged sitting for the first 2 weeks and to attend a follow-up within 7 to 14 days for suture removal and radiographic evaluation. Activity restrictions emphasize protection of the repair, prohibiting active motion, lifting, supporting body weight with the operative arm, or excessive external stretching throughout the period. Passive is limited to 90 degrees of and external in the first 2 weeks, progressing to 120 degrees flexion by weeks 3 to 4 under supervision, while , , and hand exercises are encouraged daily to prevent stiffness. Daily aspirin is often prescribed for 2 weeks to mitigate thromboembolic risk without increasing bleeding at the surgical site.

Rehabilitation Protocol

The rehabilitation protocol for the Latarjet procedure emphasizes a phased, criterion-based approach beginning around 6 weeks post-operatively to restore , prevent , and ensure graft while minimizing re-instability risks. This progression prioritizes gradual advancement from passive and assisted (ROM) exercises to active strengthening and sport-specific activities, typically spanning 6 weeks to 6 months, with adjustments based on individual and patient compliance. Phase 1 (6-12 weeks): During this initial progressive phase, the focus shifts to achieving full passive transitioning to active-assisted , with goals of pain-free motion and stability to support the graft integration. Exercises include swings for gentle mobilization, passive forward to 160 degrees, and active-assisted external (ER) using sticks or pulleys, limited to 30-45 degrees to protect the subscapularis repair. stabilization begins with holds and low-load rhythmic stabilization drills in supported positions, such as quadruped or wall slides, to enhance neuromuscular control without stressing the anterior structures. Progression criteria include pain-free active exceeding 90% of the contralateral side, no apprehension with end-range testing, and symmetry during dynamic tasks. Phase 2 (3-4 months): Strengthening intensifies with isometric exercises progressing to light resistance using bands or 1-2 pound weights, targeting and periscapular muscles while avoiding contact or high-load activities to allow bone block consolidation. Key interventions include sidelying ER, prone horizontal , and scapular retraction with TheraBand resistance, performed in 3 sets of 10-15 repetitions, alongside proprioceptive neuromuscular facilitation (PNF) patterns for dynamic . Internal rotation strengthening at 90 degrees is introduced cautiously to respect the sling effect mechanism's role in anterior . Criteria for advancement encompass greater than 80% limb symmetry index (LSI) in strength testing for ER, internal rotation (IR), and , full non-painful ROM, and tolerance of closed-chain exercises like wall push-ups without substitution patterns. Phase 3 (4-6 months): Full recovery is targeted through advanced strengthening and introduction of sport-specific drills, enabling return to non-contact activities around 4-6 months. Exercises progress to such as throws at 90/90 positions, resisted PNF diagonals, and closed-kinetic-chain upper extremity stability tests (CKCUEST), with overhead athletes incorporating interval throwing programs starting at light velocities. via higher-repetition sets (15-20) and power development with 80-100% lifts in functional patterns, like variations, are emphasized to achieve symmetric performance. Progression to unrestricted activities requires pain-free full , LSI greater than 90% across all planes, successful completion of sport-specific tests (e.g., Y-Balance or 90/90 wall dribble at 165 for 60 seconds), and psychological readiness assessment. For athletes, accelerated protocols may be employed in low-risk cases, such as those with split subscapularis repairs, allowing earlier active and strengthening initiation under close supervision to facilitate return to non-contact sports by 4-6 months, though contact activities are deferred until 6 months minimum to ensure graft . Overall criteria for phase transitions prioritize pain-free motion, strength symmetry exceeding 90%, and absence of , with regular imaging or clinical reassessment to guide modifications.

Outcomes and Complications

Clinical Effectiveness

The Latarjet procedure demonstrates high clinical effectiveness in preventing recurrent anterior shoulder instability, particularly in high-risk patients such as those with significant glenoid bone loss. Meta-analyses of prospective trials indicate overall recurrence rates of 1-6%, corresponding to success rates of 94-99%, with low risk of bias in the included studies. In comparison, arthroscopic exhibits substantially higher failure rates in cases with glenoid bone loss exceeding 20%, reaching up to 67% recurrence. Long-term outcomes from studies conducted between 2020 and 2025 further support the procedure's durability, especially in North American cohorts. In a multicenter survey with mean follow-up exceeding 10 years, 94% of patients required no further surgery, 95% reported no dislocations, and satisfaction rates ranged from 80-90%. These results align with European long-term data showing sustained stability over 20 years. Postoperative functional improvements are robust, with mean Rowe scores exceeding 85 and American Shoulder and Elbow Surgeons (ASES) scores surpassing 80 at final follow-up. Return to sport occurs in 85-90% of patients by 6 months, enabling most athletes to resume pre-injury activity levels. Comparisons between variants reveal equivalent efficacy between arthroscopic and open Latarjet procedures in terms of recurrence prevention and functional outcomes, though the arthroscopic approach facilitates faster recovery and earlier return to daily activities.

Risks and Complications

The Latarjet procedure, while effective for anterior , carries an overall complication rate of 15-30%, with systematic reviews reporting rates around 16.1% across 2560 procedures. This rate is higher in open approaches (up to 35%) compared to arthroscopic techniques (7-25%), primarily due to differences in intraoperative complications (5.0% arthroscopic vs. 2.9% open) and instability-related issues (3.1% arthroscopic vs. 7.2% open). Common complications include , occurring in 1-2% of cases, typically managed with antibiotics for superficial cases or for deeper infections. Nerve injuries, particularly to the axillary or musculocutaneous nerves, affect 1.9-10% of patients, often resolving with expectant management but sometimes requiring for persistent deficits. Hardware failure, such as screw migration or loosening, is reported in approximately 5% of procedures, leading to pain and necessitating removal in symptomatic cases. Graft osteolysis occurs in 10-20% long-term, though often asymptomatic and not requiring intervention. Recent studies from 2020-2025 highlight increased recognition of rates at 2-5%, fractures at 1%, and revision surgery needs at 5-10% for persistent , with reoperation rates overall at 2.6-11.1%. A 2024 of athletes reported an overall complication rate of 9.4%, including 1.1% recurrence and low rates of and neuropraxia, most managed conservatively. Prevention strategies include intraoperative to ensure proper graft positioning and prophylaxis to reduce risk. Management of failures often involves revision surgery, such as the Eden-Hybinette procedure for recurrent or hardware removal for symptomatic issues. Risk factors for complications encompass , which increases 30-day complication odds by 2.19 times due to impaired healing; poor bone quality, complicating fixation; and technical errors like graft malpositioning or inadequate preparation.