Creator: Dr. Mohammed hutaif
Published: 2026-04-12T14:22:05.964970+00:00

Key Takeaway

Examination under anesthesia and diagnostic arthroscopy are critical for evaluating anterior shoulder instability. Surgical management requires a tailored approach based on the Instability Severity Index Score (ISIS) and precise anatomical reconstruction. The modified Bankart procedure, utilizing a subscapularis split, provides excellent exposure while protecting the axillary nerve, ensuring optimal capsulolabral repair and restoration of glenohumeral stability.

EXAMINATION USING ANESTHETIC AND ARTHROSCOPY

The evaluation of the unstable shoulder is a complex diagnostic challenge that requires a meticulous synthesis of clinical history, physical examination, and advanced imaging. However, the true extent of capsuloligamentous laxity is often masked by involuntary muscle guarding in the awake patient. Examination under anesthesia (EUA) combined with diagnostic arthroscopy remains the gold standard for confirming the clinical diagnosis and uncovering unsuspected planes of instability, particularly in patients with multidirectional instability patterns.

Biomechanics of Examination Under Anesthesia

During EUA, the elimination of dynamic muscular stabilizers allows the surgeon to isolate and assess the static restraints of the glenohumeral joint.

For the assessment of anterior instability, the patient's arm is abducted, and precise anterior and posterior stress is applied while the scapula is firmly stabilized. In a normal shoulder, minimal anterior translation of the humeral head occurs. The most significant and reliable findings of anterior instability are demonstrable when the arm is placed at 40 degrees and 80 degrees of external rotation. At these positions, the inferior glenohumeral ligament (IGHL) complex is tensioned; failure of this complex allows abnormal translation.

Clinical Pearl: A translation of two grades more than the opposite, uninvolved side yields a 93% sensitivity and a 100% specificity for clinically significant instability. Always compare the affected shoulder to the contralateral side to establish the patient's baseline physiological laxity.

For the assessment of posterior instability, the arm is flexed, adducted, and pushed posteriorly. It is critical to recognize that normal shoulders may permit posterior displacement of up to 50% of the diameter of the glenoid without representing pathological instability. Pathological posterior instability is diagnosed when translation exceeds this physiological norm, particularly if it reproduces a palpable clunk or remains unreduced upon release of the posterior force.

The Role of Diagnostic Arthroscopy

Arthroscopy is seamlessly combined with the EUA and serves as an unparalleled technique for confirming the presence, direction, and severity of shoulder instabilities. The examiner should systematically grade the instability in all planes, remembering that the EUA and arthroscopy are utilized to support—not replace—the clinical history and awake examination.

While some authors advocate for the use of intraoperative fluoroscopy to evaluate the exact amount and direction of displacement, routine fluoroscopy is generally unnecessary for an experienced shoulder surgeon. Arthroscopy should be performed comprehensively to identify all intraarticular pathology, including labral tears, capsular stretching, chondral defects, and loose bodies, so that treatment may be rendered accordingly.

Surgical Warning: Arthroscopy portals and total operative time must be strictly limited during the diagnostic phase. Excessive fluid extravasation into the periarticular soft tissues can severely distort tissue planes, making subsequent open surgical exposure exponentially more difficult and increasing the risk of neurovascular traction injuries.

Advanced Imaging and Pathoanatomy

Preoperative magnetic resonance imaging (MRI) or MR arthrography is essential for identifying specific capsuloligamentous injuries. One such critical finding is the Humeral Avulsion of the Glenohumeral Ligament (HAGL) lesion, which can be easily missed if not specifically sought.

Figure 47-32 (A, B, C): MR angiograms demonstrating a HAGL lesion. Note the characteristic J-sign indicating the avulsion of the inferior glenohumeral ligament from its humeral attachment.

ANTERIOR INSTABILITY OF THE SHOULDER

Principles of Surgical Treatment

More than 150 operations and countless modifications have been devised to treat traumatic recurrent anterior instability of the shoulder. There is no single "best" procedure; rather, the optimal operation is the one that addresses the specific pathoanatomy of the individual patient.

Factors that have been universally stressed as critical in achieving a successful result are adequate surgical exposure and meticulous, accurate surgical technique. The pathological condition must be precisely defined, and a procedure must be selected that corrects this condition as anatomically as possible.

Ideally, the chosen procedure for recurrent instability should fulfill the following criteria:
1. Has a low recurrence rate.
2. Has a low complication rate.
3. Has a low reoperation rate.
4. Does no harm (specifically, avoids over-constraining the joint which leads to secondary osteoarthritis).
5. Maintains physiological range of motion, particularly external rotation.
6. Is applicable in the vast majority of cases.
7. Allows direct observation of the joint pathology.
8. Corrects the specific anatomical defect.
9. Is technically reproducible.

Operative procedures can be performed open or arthroscopically with comparable long-term results, provided patient selection is appropriate. When the appropriate procedure is accomplished to restore the anatomy, outcomes of Bankart repairs are heavily influenced by preoperative risk factors.

The Instability Severity Index Score (ISIS)

To guide surgical decision-making between arthroscopic and open stabilization, Balg and Boileau developed the Instability Severity Index Score (ISIS). This scoring system evaluates preoperative prognostic factors to predict the risk of recurrence following an arthroscopic Bankart repair.

Table 47-6: Instability Severity Index Score (ISIS)
* Age at surgery (yr): < 20 years (2 points) | > 20 years (0 points)
* Degree of sport participation: Competitive (2 points) | Recreational or none (0 points)
* Type of sport: Contact or forced overhead (1 point) | Other (0 points)
* Shoulder hyperlaxity: Anterior or inferior hyperlaxity present (1 point) | Normal laxity (0 points)
* Hill-Sachs lesion (AP radiograph): Visible in external rotation (2 points) | Not visible in external rotation (0 points)
* Glenoid loss of contour (AP radiograph): Loss of contour present (2 points) | No lesion (0 points)
* Total Maximum Score: 10 points

Clinical Application: A score of over 3 to 6 points suggests a higher risk of recurrence with isolated arthroscopic soft-tissue repair, often prompting the surgeon to consider an open procedure or a bone-block augmentation (e.g., Latarjet).

Algorithm for Preferred Surgical Treatment

At present, the preferred surgical procedures for isolated soft-tissue injuries without significant bone loss are arthroscopic Bankart repairs or capsular plication procedures. When an open procedure is indicated, the Jobe capsulolabral reconstruction or Neer capsular shift is preferred for anterior instability, and a glenoid-based shift is utilized for posterior instability.

Table 47-7: Preferred Surgical Treatment Algorithm
* Traumatic Bankart: Jobe capsulolabral reconstruction.
* Acute Bony Bankart: Screw or anchor fixation.
* Hyperlaxity: Rotator interval closure.
* HAGL Lesion: Suture anchor repair (open or arthroscopic).
* Multidirectional Instability: Repair Bankart/Kim lesions; Anterior-inferior prominent requires a Neer capsular shift (humeral side); Posterior prominent requires a glenoid side shift.
* Glenoid Bone Loss:
* Erosional bone loss > 25%: Latarjet procedure.
* Erosional bone loss > 40%: Eden-Hybinette procedure (iliac crest bone graft).
* Humeral Head Bone Loss (Hill-Sachs):
* 20% + glenoid defect or hyperlaxity: Jobe capsular reconstruction + capsular shift + interval closure to decrease rotation, or arthroscopic remplissage.
* 25% (approx. 6 mm deep): Arthroscopic Remplissage.
* 40%: Latarjet procedure to indirectly treat the defect by increasing the glenoid rotational arc.
* Anterior humeral head > 30%: McLaughlin procedure.
* Capsular Deficiency: Achilles tendon allograft capsular reinforcement.

THE BANKART OPERATION

Historical Context and Original Technique

In the original Bankart operation, the subscapularis tendon and the underlying shoulder capsule are opened vertically. The lateral leaf of the capsule is reattached directly to the anterior glenoid rim. A medial leaf of the capsule is then imbricated over the lateral leaf, and the subscapularis is approximated.

The Bankart operation is strictly indicated when the labrum and the capsule are separated from the glenoid rim (the classic Bankart lesion) or if the anterior capsule is pathologically thin and redundant. The primary advantage of this historical procedure is that it corrects the labral defect and imbricates the capsule without requiring any metallic internal fixation devices, which were prone to catastrophic complications in the past. The main disadvantage of the original procedure is its significant technical difficulty and the morbidity associated with complete subscapularis detachment.

Modern Modifications and the Subscapularis Split

Since the original description of the Bankart procedure, numerous modifications have allowed the operation to be performed with greater ease, enhanced anatomical precision, and significantly less surgical trauma.

To minimize morbidity, the procedure can be performed through a subscapularis split rather than a complete tenotomy. In larger, more muscular individuals where a simple split provides inadequate exposure, the subscapularis split can be extended superiorly approximately 1 cm medial to the biceps tendon, releasing the subscapularis muscle in an L-shaped fashion.

This L-type release provides excellent, wide exposure of the rotator interval. The inferior third of the subscapular muscle can be safely retracted inferiorly to expose the inferior capsule, while simultaneously protecting the axillary nerve and the anterior humeral circumflex vessels (the "three sisters").

Surgical Pearl: The subscapularis split approach preserves the neuromuscular integrity of the subscapularis and virtually eliminates the possibility of postoperative tendon detachment or catastrophic subscapularis failure—a known complication of traditional vertical tenotomies.

Figure 47-33 (A): Division of the subscapularis tendon. The lower fourth of the subscapularis tendon is left intact to protect the anterior humeral circumflex artery and the axillary nerve.

Figure 47-33 (B): The subscapularis muscle is split horizontally in line with its fibers and retracted superiorly and inferiorly to expose the underlying redundant joint capsule.

The Modified Open Bankart Procedure (Montgomery and Jobe)

A procedure similar to that described by Montgomery and Jobe has been utilized with high success rates for more than a decade. It is highly effective for both recurrent traumatic dislocations and recurrent microtraumatic subluxations presenting with anterior and inferior instability. Notably, it is rarely necessary to osteotomize the coracoid process to obtain adequate exposure when utilizing this modified approach.

Keys to Surgical Success:
1. Maximizing Healing Potential: The anterior scapular neck must be meticulously decorticated and abraded to a bleeding bone bed to promote robust soft-tissue-to-bone healing.
2. Restoring Glenoid Concavity: The labral bumper must be recreated to restore the concavity-compression mechanism of the glenohumeral joint.
3. Anatomical Capsular Fixation: The capsule must be secured exactly at the articular margin of the anterior glenoid rim. Medialization of the repair on the scapular neck will result in persistent laxity and recurrent instability.
4. Re-creating Physiological Capsular Tension: This is achieved through precise superior and inferior capsular advancement and imbrication (a capsular shift), eliminating the redundant inferior pouch.
5. Supervised Goal-Oriented Rehabilitation: Surgery is only half the treatment. A strict, phased postoperative rehabilitation protocol is mandatory to protect the repair while gradually restoring functional range of motion and dynamic muscular control.

Postoperative Protocol

Following an open capsulolabral reconstruction, the patient is placed in a sling with the arm in internal rotation.
* Phase I (0-4 weeks): Absolute protection of the repair. Passive forward flexion is allowed up to 90 degrees, but external rotation is strictly limited to neutral (0 degrees) to prevent tension on the anterior capsular repair and the subscapularis split.
* Phase II (4-8 weeks): The sling is discontinued. Active-assisted and active range of motion begins. External rotation is gradually progressed by 10-15 degrees per week.
* Phase III (8-12 weeks): Strengthening of the rotator cuff and periscapular stabilizers is initiated.
* Phase IV (3-6 months): Return to sport-specific activities is permitted only when full, painless range of motion is achieved, and dynamic strength is at least 90% of the contralateral shoulder. Contact athletes may require 6 months before returning to unrestricted play.

Authoritative Medical Review

This academic synthesis is based on established protocols from Hutaifortho's Operative Orthopaedics and has been medically reviewed by Prof. Dr. Mohammed Hutaif, Consultant Orthopedic & Spine Surgeon. It is designed to assist orthopedic residents, fellows, and practicing surgeons in surgical preparation and board reviews (AAOS, FRCS, Arab Board).

Clinical Disclaimer: The surgical techniques, indications, and medical guidance detailed herein are for advanced educational purposes only. They do not supersede institutional guidelines or independent surgical judgment.

📚 Medical References

Medically Verified Content

Prof. Dr. Mohammed Hutaif

Consultant Orthopedic & Spine Surgeon

Comprehensive Surgical Management of Anterior Shoulder Instability