Managing Anterior Shoulder Instability: Rehab, Soft Tissue Repair, and Bone Blocks

A Practical Framework for Deciding Between Nonoperative Management, Arthroscopic Bankart Repair and Bone Block Procedures

Anterior shoulder instability is one of the most common problems I see in young, active patients, and is perhaps also one of the most nuanced to treat. The decision between physical therapy, a soft tissue repair, and a bone block procedure is not one-size-fits-all.

This post walks through the framework I use to make that call, organized around three questions: when is rehab enough, when does a soft tissue repair suffice, and when do you need to augment with bone.

Why this decision matters

The shoulder dislocates more than any other joint in the body, with an incidence of roughly 24–27 per 100,000 person-years. The injury is concentrated in a specific population: young males under 23, contact and collision athletes. In that group, the natural history without surgery is not favorable.

The Critical Variable: Bone Loss

Before anything else, you need to know how much bone has been lost on the glenoid side, how much has been lost on the humeral head side, and how those two defects interact.

Glenoid Bone Loss

Glenoid bone loss is the single variable most closely tied to recurrence after soft tissue repair. The traditional threshold has been >20–25% glenoid surface area, above which an arthroscopic Bankart repair is likely to fail. More recent data has pushed that threshold lower. Studies have identified failure thresholds as low as 13.5% and even 7.5% in higher-risk populations.

The implication is not that every patient with 8% glenoid bone loss needs a Latarjet. It means the threshold is not fixed. There is an interaction between this variable with patient age, sport type, number of prior dislocations, and humeral head bone loss.

Measurement is done on CT, specifically 3D reconstructions with the humerus subtracted. The perfect circle technique can be effective: fit a circle to the inferior glenoid, measure what percentage of the anterior margin is missing.

The Hill-Sachs Lesion

The Hill-Sachs lesion is a compression fracture of the posterolateral humeral head that occurs when the head dislocates anteriorly and impacts the anterior glenoid rim. It is present in 50–90% of first-time dislocators and approaches 100% in recurrent instability. It grows with each subsequent event, and patients with more than six dislocations average roughly 25% of the humeral head surface area involved.

The question is not whether a Hill-Sachs lesion is present. The question is whether it will engage the anterior glenoid rim during functional range of motion. An engaging Hill-Sachs in the context of glenoid bone loss creates a bipolar defect that dramatically increases failure risk after soft tissue repair alone.

The Glenoid Track Concept

The glenoid track, described by Yamamoto and colleagues, provides a model for predicting engagement. In abduction and external rotation, the humeral head rotates such that the medial margin of the rotator cuff footprint moves across the glenoid surface (this contact zone is the glenoid track). If the Hill-Sachs lesion falls within that track when the arm is in the provocative position, it is on-track and unlikely to engage. If it extends medial to the track, it is off-track and will engage the anterior glenoid rim during functional motion.

The formula: Glenoid Track = (0.83 × Glenoid Diameter) − d, where d is the distance of glenoid bone loss from the medial edge of the glenoid. The Hill-Sachs interval (the width of the Hill-Sachs defect plus the medial intact bone bridge) is then compared to the glenoid track width.

Lin and colleagues refined this further with the distance-to-dislocation (DTD) metric, which is defined as Glenoid Track minus Hill-Sachs Interval. A DTD below 8mm defines a "near-track" lesion, which carries significantly higher failure rates after arthroscopic Bankart repair. DTD is age-dependent: younger patients tolerate a smaller safety margin before failure risk becomes unacceptable.

When Is Nonoperative Management Appropriate?

Not every shoulder dislocation requires surgery. A large meta-analysis of five randomized controlled trials in young active males showed a 46.6% recurrence rate with nonoperative management versus 6.3% with arthroscopic Bankart repair. That is a substantial difference but it also means that roughly half of nonoperatively managed first-time dislocators do not go on to redislocate.

The profile of the patient who does well without surgery:

Candidates for Nonoperative Management

• Older patient (above 30–35 years)

• Low-demand lifestyle or non-contact sport

• First-time dislocation with no glenoid bone loss on imaging

• No engaging Hill-Sachs lesion on imaging or exam

• Willing to accept recurrence risk and modify activity accordingly

Age matters substantially. Population-based data show that each year younger at the time of first dislocation increases recurrence risk by 4.1% and surgery risk by 2.8%. A 19-year-old football player and a 45-year-old recreational swimmer face fundamentally different natural histories.

The number of prior instability events also matters independently. Having two or more prior subluxations or dislocations at initial presentation is among the strongest predictors of eventual surgical intervention. Waiting for a second dislocation in a high-risk patient accumulates additional bone loss with each event, and this glenoid does not regenerate.

The In-Season Athlete

Managing a contact athlete who dislocates mid-season is a specific scenario without a clean protocol. The general approach is brief immobilization followed by 1–4 weeks of rehab with goals of restoring full, symmetric, pain-free range of motion and sport-specific function. Return to play is reasonable once those criteria are met, with appropriate protective equipment where possible.

Indications to move to in-season surgery include failure to progress range of motion, recurrent instability on return to play, or imaging that reveals significant bone loss. The cost of delaying surgery until the off-season is the risk of additional injury, and that tradeoff should be explicit and patient-driven.

When Is Soft Tissue Repair Enough?

Arthroscopic Bankart repair addresses the essential lesion in anterior shoulder instability: detachment of the inferior glenohumeral ligament-labrum complex from the anterior glenoid rim. In the right patient, it is highly effective with recurrence rates below 10% in appropriately selected cases.

The two core requirements for soft tissue repair to be sufficient:

Conditions for Isolated Bankart Repair

• Minimal glenoid bone loss — below the threshold that matters for the specific patient's risk profile

• On-track Hill-Sachs lesion, or no significant Hill-Sachs lesion present

Risk Stratification Tools

Several scoring systems attempt to operationalize the decision. The Instability Severity Index Score (ISIS) incorporates age, sport type, competition level, hyperlaxity, and imaging findings. This was one of the original tools for risk stratification. An ISIS ≥ 6 historically indicated Latarjet over Bankart. However, subsequent data showed that ISIS over-recommended Latarjet compared to glenoid track-based decision making, and showed limited correlation with actual Bankart failure rates.

The Glenoid Track Instability Management Score (GTIMS) incorporates on-track versus off-track status and produces better-calibrated recommendations. GTIMS-guided selection has been shown to produce lower Bankart failure rates compared to ISIS-guided selection. Below a GTIMS score of 4, isolated Bankart repair — with or without remplissage depending on Hill-Sachs characteristics — is appropriate.

The Pittsburgh Instability Tool (PIT) identifies independent risk factors including near-track lesion (DTD <10mm), hyperlaxity, younger age, two or more prior events, contact sport, and increasing glenoid bone loss, and stratifies patients into low-risk (2.2% recurrence), moderate-risk (8.1%), high-risk (18.4%), and extreme-risk (51.3%) categories. The PIT score provides a probability-based framework rather than a binary threshold.

Remplissage: Addressing the Hill-Sachs

When the Hill-Sachs lesion is off-track, extends below the equator of the humeral head, or engages intraoperatively, remplissage is added to the Bankart repair. The technique involves a posterior capsulo-tenodesis of the infraspinatus and posterior capsule into the Hill-Sachs defect, rendering it extra-articular and preventing engagement with the glenoid rim.

The concern that remplissage significantly restricts external rotation has not been borne out in the long-term data. Prospective studies show modest and often clinically inconsequential reduction in external rotation, with outcomes in overhead athletes remaining acceptable when patient selection is appropriate.

Critically, a well-conducted comparative study showed no difference in recurrent instability or reoperation rates between arthroscopic Bankart plus remplissage and open Latarjet in patients with subcritical glenoid bone loss (≤20%), in both primary and revision settings. This supports remplissage as a legitimate alternative to bone block in selected patients rather than a procedure reserved for cases where Latarjet is not feasible.

When Is Bone Block Required?

Bone block procedures restore anterior glenoid width directly and, in the case of the Latarjet, provide additional stability through the sling effect of the conjoined tendon at the inferior subscapularis split. They are the right choice when soft tissue repair — even augmented with remplissage — is inadequate to address the underlying structural deficit.

The Latarjet Procedure

The Latarjet transfers the coracoid process with the attached conjoined tendon to the anterior glenoid rim, providing three mechanisms of stability: bony augmentation of the glenoid arc, a dynamic sling effect of the conjoined tendon in abduction-external rotation, and reinforcement of the anterior capsule.

Primary indications:

Latarjet Indications

• Recurrent instability with significant bone loss (>15–20% glenoid)

• Off-track Hill-Sachs lesion, especially combined with glenoid bone loss

• Failed prior soft tissue stabilization

• High-risk patients: contact or collision athletes with GTIMS ≥ 4

  
  

The procedure is increasingly performed in the United States with coracoid transfers now exceeding open capsulolabral repair and open capsular shift in annual volume. Both open and arthroscopic techniques are used, with comparable outcomes in experienced hands.

The Latarjet is not without downsides. Complication rates in large series approach 21%, with the most common being subjective apprehension (9%), recurrent instability (6%), and reoperation (9%).

An important limitation of the Latarjet is that it addresses glenoid bone loss but does not inherently address a large humeral-side defect. Patients with off-track lesions after Latarjet are four times more likely to have postoperative instability because the humeral defect is large enough to still engage even after bony augmentation. This requires either concurrent remplissage or humeral head bone grafting in cases of severe bipolar loss.

Allograft Bone Block

When glenoid bone loss is substantial, when the coracoid is unsuitable or has already been used in a prior Latarjet, or when salvage after a failed bone block procedure is needed, allograft bone grafting is the option. Distal tibial allograft is the most commonly used, offering a large articular surface that closely matches glenoid curvature and the capacity to restore both bone stock and articular continuity.

Systematic reviews comparing allograft bone block to Latarjet show similar recurrence rates, complication profiles, osteoarthritis progression, functional outcomes, and return-to-sport rates. Surgeon preference and case-specific anatomy drive the choice between them.

A Decision Framework

Pulling all of this together, the GTIMS-based algorithm provides a structured approach for active patients:

Scenario	Recommended Approach
Low risk (GTIMS <4), on-track lesion, minimal bone loss	Arthroscopic Bankart repair ± remplissage for near-track lesions
Low risk (GTIMS <4), subcritical bone loss (<20%)	Bankart + remplissage; consider bone block if glenoid loss is predominant
High risk (GTIMS ≥4), on-track, GBL <10%	Bankart ± remplissage; open Bankart in highest-risk cases
High risk (GTIMS ≥4), on-track, GBL 10–20%	Bankart + remplissage (humeral loss predominant) or Latarjet (glenoid loss predominant)
High risk (GTIMS ≥4), off-track lesion	Latarjet ± Hill-Sachs treatment; consider larger allograft if HSI > glenoid track
Critical glenoid bone loss (>20–25%)	Latarjet or allograft bone block depending on magnitude of bone loss

This framework serves as a guide rather than a protocol. Two patients with identical imaging can warrant different decisions based on age, sport, competition level, and laxity. The goal is to match the procedure to the structural problem and the patient's risk profile and to avoid both under-treating a high-risk patient with a soft tissue repair that will fail, and over-treating a low-risk patient with a bone block procedure carrying non-trivial complication rates.

The Bottom Line

Anterior shoulder instability management is a spectrum. Rehab may be appropriate for the older, low-demand first-time dislocator with no bone loss. Arthroscopic Bankart repair (with or without remplissage) is appropriate for the majority of patients who require surgery and have subcritical bone loss with on-track or manageable Hill-Sachs pathology. Bone block procedures are indicated when bone loss is critical, lesions are off-track, prior soft tissue repair has failed, or the patient's risk profile makes soft tissue repair an inadequate solution.

The critical input to all of this is accurate bone loss quantification on 3D CT. Without it, you are making a high-stakes decision with incomplete data.

Call to book an appointment to see if PRP might be a good choice for your shoulder or elbow condition:

646-665-6784

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About the Author

C. Lucas Myerson, MD – Orthopedic surgeon specializing in shoulder and elbow surgery.

Disclaimer

This article is for educational purposes only. It is not a substitute for medical advice. Always talk to your doctor before starting or changing treatment.

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