Humeral Head Defects Research Articles

Hill-Sachs Remplissage Procedure Based on Posterosuperior Capsulomuscular Anatomy

The remplissage technique is a procedure designed to fill a posterosuperior humeral head defect with the infraspinatus tendon and posterior-superior capsule in patients with engaging Hill-Sachs lesions. We describe a remplissage technique using 2 posterior working portals that respects the anatomy of the posterior-superior area of the glenohumeral joint without compromising the vascularization.

Remplissage: Expand the Arthroscopic Repair Spectrum

Humeral head defects (Hill-Sachs lesions) are common sequelae of glenohumeral instability and potentiate recurrence. Engaging Hill-Sachs lesions clearly increase risk of recurrent instability when not addressed surgically. Arthroscopic remplissage, in conjunction with Bankart repair, has proven to be a safe and effective means to treat anterior gelnohumeral instability. Remplissage, when executed properly, favorably alters the “glenoid track” and thus lessens the risk of glenohumeral engagement in abduction external rotation. Remplissage is a biologic tissue transfer that confers much less morbidity than glenoid bone grafting procedures (Latarjet), while demonstrating comparable efficacy.

Resurfacing hemiarthroplasty of the shoulder for patients with juvenile idiopathic arthritis

This study reports the outcome of resurfacing hemiarthroplasty (RHA) in a cohort of patients with juvenile idiopathic arthritis (JIA) affecting the shoulder joint METHODS: Fourteen uncemented RHA procedures were performed for 11 consecutive patients who required surgery because of JIA. Mean age at surgery was 36.4 years. Mean clinical follow-up was 10.4 years (range, 5.8-13.9 years). A significant humeral head defect (up to 40% surface area) was found in 5 shoulders and filled with autograft from the distal clavicle or femoral head allograft. At latest follow-up, no patient required revision. There was excellent relief from pain. The mean Oxford Shoulder Score and Constant-Murley Score improved significantly. No shoulder had a poor outcome, and 6 had a very good or excellent outcome. Worse outcome was associated with an intraoperative finding of significant humeral head erosion. Two shoulders required early arthroscopic subacromial decompression, but there were no other reoperations. There were no instances of radiographic implant loosening or proximal migration. Painless glenoid erosion was seen in 5 shoulders but was not associated with worse outcome. The midterm results of RHA for JIA are at least comparable to those for stemmed hemiarthroplasty, with the added benefit of bone conservation.

Long-term Clinical Outcomes After Microfracture of the Glenohumeral Joint: Average 10-Year Follow-up

Background: Microfracture is an effective surgical treatment for full-thickness cartilage defects of the knee; however, little is known regarding long-term outcomes after microfracture in the shoulder. Purpose: To present long-term clinical outcomes of patients undergoing microfracture of full-thickness articular cartilage defects of the glenohumeral joint. Study Design: Case series; Level of evidence, 4. Methods: Sixteen consecutive patients (17 shoulders) were retrospectively reviewed who underwent arthroscopic microfracture of the humeral head and/or glenoid surface, with or without additional procedures between 2001 and 2008 and with a minimum follow-up of 8.5 years. All patients completed pre- and postoperative surveys containing the visual analog scale, American Shoulder and Elbow Surgeons form, and Simple Shoulder Test. Complications and reoperations were analyzed. Failure was defined by biological resurfacing or conversion to arthroplasty. Results: Of the original 16 patients (17 shoulders), 13 patients (14 shoulders) were available for mean follow-up at 10.2 ± 1.8 years after microfracture (range, 8.5-15.8 years), for an overall clinical follow-up rate of 82%. The patients (6 men, 7 women) were 36.1 ± 12.9 years old at time of microfracture. The average size of humeral head defects was 5.20 cm2 (range, 4.0-7.84 cm2), and the average size of glenoid defects was 1.53 cm2 (range, 1.0-3.75 cm2). Four patients (4 shoulders) underwent at least 1 reoperation, and 3 were considered to have structural failures. The average time to failure was 3.7 years after microfracture (range, 0.2-9.6 years). The overall survival rate was 76.6% at 9.6 years. For these patients, there were statistically significant improvements in visual analog scale, Simple Shoulder Test, and American Shoulder and Elbow Surgeons scores as compared with preoperative values at long-term follow-up (P < .05 for all), without any significant change from short-term (mean, 2.3 years) to long-term (mean, 10.2 years) follow-up. There was no significant difference in Single Assessment Numeric Evaluation or Short Form–12 Physical or Mental scores between short- and long-term follow-up. When compared with short-term follow-up, in which 2 patients had already failed, 1 additional patient progressed to failure at 9.6 years after the original microfracture. Two patients (2 shoulders) were considered to have clinical failure. Owing to the overall number of failures (3 structural failure and 2 clinical failure), the total long-term success rate of glenohumeral microfracture is 66.7% in the current study. Conclusion: Treating full-thickness symptomatic chondral defects of the glenohumeral joint with microfracture can result in long-term improved function and reduced pain for some patients. However, in this case series, 21.4% of patients required conversion to arthroplasty <10 years after the index microfracture procedure, and 33% to 42% of patients were considered to have potential clinical failure. Additional studies with larger patient cohorts are needed.

Arthroscopic remplissage: Is it still an option?

Posterolateral humeral head defects can be large and engage on the anterior glenoid, and they usually contribute to anterior shoulder instability in 40% to 90% of cases.The purpose of this study is to evaluate the results of the largest series of patients who underwent arthroscopic remplissage with Bankart repair for recurrent anterior shoulder instability due to associated Bankart lesions, with large and engaging (> 25% involvement) humeral Hill-Sachs defects (HSDs).A total of 51 patients underwent arthroscopic Bankart repair with remplissage technique for the treatment of recurrent anterior glenohumeral instability with large and medial HSDs. Pre-operative imaging in all patients identified a Bankart lesion with an associated HSD that involved > 25% of the humeral head. The Rowe score was used to assess the patients clinically.A total of 46 patients were male. The mean age of the patients was 28.7 years (18 to 43). The mean follow-up period was 31 months (20 to 39). At the final follow-up, three patients reported recurrence of instability (two dislocations and one subluxation). The mean Rowe score improved to 95.4 points (function, 45.5 of 50; stability, 26.4 of 30; motion, 8 of 10; pain, 8 of 10).The arthroscopic remplissage technique with Bankart repair gave satisfactory results and is still considered to be an effective, safe and reliable procedure for treatment of glenohumeral instability in cases with large and medial HSDs.Cite this article: EFORT Open Rev 2017;2:478–483. DOI: 10.1302/2058-5241.2.160070

Understanding the Hill-Sachs Lesion in Its Role in Patients with Recurrent Anterior Shoulder Instability.

The purpose of this study is to provide an update to the orthopedic field in regard to treatment of the Hill-Sachs lesion and anterior shoulder instability. The review highlights the most current knowledge of epidemiology, clinical evaluation, and surgical methods used to treat Hill-Sachs lesions. It also details the relevant clinical and surgical findings that have been made throughout the literature in the past couple of years. The most recent literature covering the Hill-Sachs lesion has focused on the relatively new and unexplored topic of the importance of concomitant injuries while treating a humeral head defect. The glenoid track concept has been clinically validated as a method to predict engagement. 3D-CT has become the "gold standard" for Hill-Sachs imaging; however, it has been noted that 3D-MRI produces results that are not significantly different from CT. Also, it has been found that when the arm is in a position of abduction during the primary injury, there is a higher risk of engagement and subsequent dislocation. Recent studies have demonstrated successful results stemming from purely arthroscopic procedures in treating Hill-Sachs lesions. Anterior shoulder instability, specifically the Hill-Sachs lesion, is an area of orthopedic study that is highly active and constantly producing new studies in an attempt of gaining the best outcomes for patients. The past few years have yielded many excellent discoveries, but there is still much more work to be done in order to fully understand the role of the Hill-Sachs lesion in anterior shoulder instability.

Remplissage—when and how to fill in the defect

Hill-Sachs lesions can be seen in 65–80% of initial glenohumeral dislocations, and up to 100% of recurrent instability episodes. Engaging Hills-Sachs lesions have been described as those that occur when the long axis of the humeral head defect is parallel to the anterior glenoid rim, allowing the humeral head defect to fall off of the glenoid fossa in essence becoming levered anteroinferiorly to the glenoid fossa. More recently, an arthroscopic technique, which involves soft tissue interposition into the humeral defect, known as remplissage (French: to fill in) procedure, has been developed to prevent Hill-Sachs lesion engagement on the glenoid rim. The purpose of this paper is to review the current literature surrounding the technique, indications, outcomes, and complications of this procedure.

Partial Resurfacing for Humeral Head Defects Associated With Recurrent Shoulder Instability.

Recurrent traumatic shoulder instability is a complex clinical entity that commonly affects young, active patients. Humeral head defects are frequently associated with this condition, but specific treatment to stabilize the shoulder is rarely needed. Management options for defects of the humeral head that do necessitate treatment carry various risks and disadvantages, including the need for bone or soft tissue healing, complications related to hardware, and loss of motion. Partial prosthetic resurfacing has been reported as a treatment option. The current study retrospectively reviewed a cohort of patients with recurrent or locked anterior and posterior instability who underwent partial prosthetic humeral head resurfacing for significant Hill-Sachs and reverse Hill-Sachs lesions. At an average of 36.4 months after the index procedure, 16 patients were contacted by mail and telephone. Of the study group, 13 patients underwent partial resurfacing for anterior instability and 3 patients underwent partial re-surfacing for posterior instability. No patient had a repeat dislocation. In addition, 77% of patients in the anterior instability cohort and all of the patients in the posterior instability cohort returned to their full preinjury activity level. For the anterior instability cohort, significant improvements from preoperatively to final follow-up occurred for mean Musculoskeletal Review of System score (4.54, P<.0001) and Short Form-12 physical component score (9.52, P=.002). For the combined cohort, the Penn Shoulder Score improved by 36.4 points (P=.059). This study showed the effectiveness of partial humeral head resurfacing for preventing redislocation for patients with significant Hill-Sachs and reverse Hill-Sachs lesions. [Orthopedics. 2017; 40(6):e996-e1003.].

Arthroscopic Repair of Posterior Bony Bankart Lesion and Subscapularis Remplissage

Posterior shoulder instability with glenoid bone loss has only a fraction of the prevalence of anterior instability. Unlike the latter, there is a paucity of literature regarding the treatment of posterior bony Bankart lesions and even less with concomitant reverse Hill-Sachs lesions. This combination of pathology leads to a difficult situation regarding treatment options. We present our technique for arthroscopic repair of a posterior bony Bankart lesion and reverse Hill-Sachs lesion. The importance of proper portal placement cannot be overstated. By use of the lateral position and strategically placed portals, the posterior bony Bankart lesion and attached labral complex were appropriately mobilized. We reduced the glenoid bone, with the attached capsulolabral complex, to the glenoid rim and performed fixation using a knotless suture anchor. We then placed 2 double-loaded suture anchors into the reverse Hill-Sachs lesion. The sutures were passed creating horizontal mattress configurations that were tied at the end of the procedure, effectively externalizing the humeral head defect. Our technique results in satisfactory fragment reduction, as well as appropriate capsular tension, and effectively prevents the reverse Hill-Sachs lesion from engaging.

Three-dimensional quantitative analysis of humeral head and glenoid bone defects with recurrent glenohumeral instability

Although bone defects of the humeral head and glenoid could affect glenohumeral instability, bone loss has not been sufficiently evaluated. The purpose of this study was to quantify bone defects 3-dimensionally in cases with glenohumeral instability. Three-dimensional surface models of bilateral proximal humeri and glenoids were reconstructed from computed tomography scans of 90 patients with symptomatic, unilateral, recurrent glenohumeral instability. The left-side models were mirrored, and intact bone areas were matched to those of the right-side models. The volume, length, width, and depth of identified bone defects were assessed. After the values were corrected by patient height, the characteristics of the bone defects were evaluated. Bone defects were present in 97.8% of the humeral heads and 96.7% of the glenoids, and women had significantly smaller bone defects than men did. The volume of humeral head defects had a mild correlation with that of glenoid defects. The number of traumatic episodes was not correlated with humeral head bone defects, but it was positively correlated with glenoid bone defects. Patients with recurrent dislocations had significantly deeper and larger Hill-Sachs lesions than the other cases. Bone defects of the humeral head and the glenoid in cases with symptomatic traumatic glenohumeral instability were quantified 3-dimensionally using a computed tomography surface-matching technique. Almost all cases showed bone defects in the humeral head and glenoid compared with the intact shoulder, and such bone defects may be more common than previously reported. This study suggested that bipolar bone lesions are not always created by the same mechanism.

Current Concepts in the Diagnosis and Management of Traumatic, Anterior Glenohumeral Subluxations.

Traumatic anterior glenohumeral subluxations comprise the majority of glenohumeral instability events and are endemic in young athletes. Unlike the definitive complete dislocation event, subluxation events may often be more subtle in presentation and, therefore, may be overlooked by clinicians. Glenohumeral subluxation events are associated with a high rate of labral tears as well as humeral head defects. While less is known of the natural history of these injuries, young athletes are at risk for recurrent instability events if not properly diagnosed and treated. While reports of surgical treatment outcomes isolated to subluxation events are limited, arthroscopic and open Bankart repair have been shown to result in excellent outcomes. The purpose of this paper is to review the etiology and pathoanatomy of traumatic anterior glenohumeral subluxations as well as to review the appropriate evaluation and management of patients with this injury.

Arthroscopic Reduction and Balloon Humeroplasty in the Treatment of Acute Hill-Sachs Lesions

Shoulder instability is often associated with an impaction fracture of the humeral head, commonly referred to as a “Hill-Sachs lesion.” This lesion is present in both anterior and posterior instability. Forty percent to 90% of anterior shoulder dislocations have associated Hill-Sachs lesions, whereas 29% to 86% of posterior shoulder dislocations have reverse Hill-Sachs lesions. Both of these lesions can contribute to recurrent instability of the shoulder and require surgery to be treated. Currently, the most common procedures to address Hill-Sachs lesions are the remplissage procedure (transfer of the infraspinatus into the posterior humeral head defect), capsular shift, disimpaction technique, humeral head resurfacing, bone block transfer, or shoulder arthroplasty. Reverse Hill-Sachs lesions are managed with similar procedures, such as the remplissage-equivalent technique described by McLaughlin, which involves transfer of the subscapularis tendon to fill the humeral head defect. The procedure has the advantage of “exteriorizing” the humeral head defect, but in the case of large lesions, it can result in significant loss of the articulating articular surface. The purpose of this article is to describe an arthroscopically assisted disimpaction technique with supplemental grafting using a balloon osteoplasty technique for a reverse Hill-Sachs lesion with bone cement to support and maintain the reduction.

Shoulder instability: State of the Art

The mobility of the glenohumeral joint in multiple anatomic planes is not without consequence as recurrent instability is common, particularly among young, active individuals. Throughout midranges of shoulder motion, stability is conferred primarily by the compression-cavity effect of the rotator cuff as muscular contractions maintain the humeral head centred in the glenoid cavity. At extremes of shoulder motion (flexion and abduction), derangements of capsule-ligamentous complex, glenoid and glenoid labrum drive a pathophysiological cascade that manifests clinically as recurrent anterior, unidirectional instability. In the setting of bone loss <25% of the inferior glenoid diameter, arthroscopic Bankart repair using proper technique yields reliable clinical results. Additionally, much is now known about the extent to which attritional glenoid bone loss, related commonly to repeated dislocation events, affects the predicted success of certain treatment approaches. The preponderance of existing literature supports performing a bone grafting procedure for cases in which the osseous defect comprises >25% of the glenoid width, with the Latarjet procedure being favoured among recent authors. A growing body of evidence has elucidated the consequence of humeral head defects (the Hill-Sachs lesion) as a predictor of recurrent instability. Thus, the concept of ‘bipolar bone loss’ has emerged as a critical concept in the surgical treatment of recurrent shoulder instability. Surgeons should adopt a treatment paradigm that focuses on the relationship between both osseous defects—glenoid and humeral head—and incorporates a surgical tactic to appropriately address each lesion.

A Simple Population-Based Finite Element Model Eliminates the Need for Patient-Specific Models to Predict Instability of the Shoulder

Objectives:Recurrent shoulder instability can significantly increase in the presence of bony Bankart and Hill-Sachs lesions. Therefore, it is important to understand the changes in shoulder biomechanics due to bony defects. Limitations of using cadaveric model to investigate the effects of combined bony defects on shoulder instability is inability to test all combination in a single specimen. Utilizing the flexibility of computational methodology like finite element (FE) model provides the advantage of testing all combinations at multiple arm positions. The aim of this study was to develop a simple FE model of combined bony lesions and its effect on anterior shoulder instability. In addition, we wanted to determine the need for patient (specimen) specific modeling. We hypothesized that the shoulder instability would be similar for all three models (population-based model, specimen-specific model, and cadaveric model).Methods:Three specimens were randomly selected from specimens tested in our previous study and Computed Tomography (CT) arthrogram images were taken before and after experimentation to develop FE models. We also developed a simple population-based model representing a spherical humeral head, which was developed using the radii values for cartilage and bone from literature. The sizes of humeral head lesions chosen were: 6%, 19%, 31%, and 44% of humeral head diameter and glenoid defect sizes were 10%, 20% and 30% of the glenoid width. All simulations were performed at glenohumeral abduction angles (ABD) of 20°, 40°, and 60° and external rotation of 0°, 40°, and 80°. Each simulation comprised of translating the humeral head leading to an anterior dislocation under a constant 50 N medial load. This compressive load simulated the static load of soft tissue. The percent intact translation (%IT) was computed by normalizing the distance to dislocation value for each defect condition w.r.t intact condition of each specimen. Stability Ratio (SR) was computed as a ratio of horizontal reaction force to the compressive load.Results:The individual specimen-specific model results comparison to the experimental data for %IT had a good agreement as the values were similar for defect created. However, results for SR were over predicted by the FE model, but they had similar linear decreasing trends for both specimen-specific and cadaveric model. In addition, the humeral head defect size of 44% reduced the %IT from 100% to nearly 0% for all three models. The results for the comparison of all three models with increasing size of humeral defect with a 20% glenoid defect are shown in Figure 1 at three arm position.Conclusion:This study proposed a simple population-based model that can be used to estimate the loss in stability due to combined defects to determine a threshold for defect augmentation in clinical practice. It was demonstrated that a smaller glenoid defect size of 10% combined with a 19% humeral head defect can cause significant instability. Similar to past studies, it was also shown that a glenoid defect would lead to loss of translation and a humeral head defect would lead to instability at a functional arm position of increased abduction and external rotation [5-6]. All three models predicted similar results during validation, which shows that the population based model can be utilized to estimate the stability, instead of needing patient-specific FE models. The limitation of the study is the absence of soft tissue restraints.

Paper #7 - The effects of latarjet reconstruction on glenohumeral instability in the presence of combined bony defects: a cadaveric model

Introduction: Recurrent glenohumeral instability often results from underlying bony defects in the glenoid and/or humeral head. Anterior glenoid augmentation with a bone block (i.e. Latarjet) has been recommended for glenoid bone loss in the face of recurrent instability. However, no study has investigated the effect of Latarjet augmentation in the setting of both glenoid and humeral head defects (Hill-Sachs Defects (HSD)). The purpose of this study was to evaluate the stability achieved through a Latarjet procedure in the presence of combined bony defects. Methods: Eighteen fresh-frozen cadaveric specimens were tested at all combinations of glenohumeral abduction (ABD) angles of 20°, 40°, and 60° and three external rotation (ER) levels (0°, 40°, and 80°). Each experiment comprised of anterior dislocation by translating the glenoid under a 50N medial load applied on the humerus, simulating the static load of soft tissues. Translational distance and medial-lateral displacement of the humeral head, along with horizontal reaction forces were recorded for every trial. Specimens were tested in an intact condition (no defect), different combinations of defects, and with Latarjet augmentation. The Latarjet was performed for 20% and 30% glenoid defects by transferring the specimen's coracoid process anterior to the glenoid flush with the articulating surface. Four different humeral head defects (sizes 6%, 19%, 31%, and 44% of humeral head diameter) were created. Repeated measures analysis of variance (ANOVA) was performed with statistical significance set at P < .05. Results: Results are summarized in Figure 1. The vertical axis represents the normalized distance to dislocation with respect to the values of the intact joint. The horizontal axis represents the varying sizes and combinations of bony defects. At 20° ABD and 0°ER, increasing HSD size did not affect percentage of intact translation with a constant glenoid defect of 20% before and after Latarjet augmentation (Fig. 1A). However, at an arm position of 60° ABD and 80° ER increasing HSD size led to a decrease in stability for both the defect state and post-Latarjet trials (Fig. 1C). Nevertheless, Latarjet augmentation helped in regaining stability for every combination of bony defects. With a HSD size of 44% the defect state had 0% intact translation for all 18 specimens. Conclusions: Clinically, these results demonstrate that some degree of stability can be regained for combined bony Bankart and Hill-Sachs defects with a Latarjet procedure. However, for humeral defects larger than 31%, the rotational effect of the HSD led to persistent instability. Thus, directly addressing the humeral defect to restore the articular surface should be considered in these cases.

Hill-Sachs lesion is not a significant prognostic factor for recurrence of shoulder redislocation after arthroscopic Bankart repair

ImportanceHumeral head defects are a common finding after acute and recurrent shoulder dislocations. Different hypotheses exist on the real significance of these defects and on their relevance in predicting dislocations after surgical repair.ObjectiveThis review study was designed to evaluate if humeral head defects are a negative prognostic factor for recurrence after arthroscopic Bankart repair.Evidence reviewA systematic review of the available literature (1980–2015) was performed using EMBASE and MEDLINE databases. The reference lists of reviewed articles were also scrutinised to ensure relevant information was included.FindingsA meta-analysis on instability recurrence risk after arthroscopic Bankart repair and recurrence rate stratification for time from intervention were not possible for lack of data. 23 studies were eligible for inclusion. The ratio between recurrence cases and total cases was 0.1254. This ratio rose to 0.1314 in the group with Hill-Sachs lesions and dropped to 0.1044 in the group without. 10 patients reported the dimension of the Hill-Sachs encountered and 6 reported precisely the time to instability recurrence in presence or absence of Hill-Sachs lesions.Conclusions and relevanceA Hill-Sachs lesion could not be confirmed as a statistically significant negative prognostic factor after arthroscopic Bankart repair. With increased follow-up length, a slight tendency to higher redislocation rates was observed in presence of a Hill-Sachs lesion. Higher quality studies with repair survival analysis are needed to assess recurrence risk after arthroscopic Bankart repair and evaluate the prognostic relevance of the presence of a Hill-Sachs lesion.

The Effects of Latarjet Reconstruction on Glenohumeral Kinematics in the Presence of Combined Bony Defects

Background: Recurrent glenohumeral instability is often a result of underlying bony defects in the glenoid and/or humeral head. Anterior glenoid augmentation with a coracoid bone block (ie, Latarjet procedure) has been recommended for glenoid bone loss in the face of recurrent instability. However, no study has investigated the effect of Latarjet augmentation in the setting of both glenoid and humeral head defects (Hill-Sachs defects). Purpose: To evaluate the glenohumeral kinematics of the Latarjet procedure in the presence of combined bony defects. Study Design: Controlled laboratory study. Methods: Eighteen fresh-frozen cadaveric specimens void of all surrounding soft tissue were tested at all combinations of glenohumeral abduction (ABD) angles of 20°, 40°, and 60° and 3 external rotation (ER) levels of 0°, 40°, and 80°. Each experiment comprised anterior dislocation by translating the glenoid under a 50-N medial load applied on the humerus, simulating the static load of soft tissue. The primary outcome measurement was defined as the percentage of intact translation (normalized distance to dislocation). Specimens were tested in an intact condition (no defect), with different combinations of defects, and with Latarjet augmentation. The Latarjet procedure was performed for 20% and 30% glenoid defects by transferring the specimen′s coracoid process anterior to the glenoid so that it was flush with the articulating surface. Results: Results depended on the position of the arm. At 20° of ABD and 0° of ER, a 20% glenoid defect decreased the percentage of intact translation regardless of the humeral head defect size (P ≤ .0001). In this same setting, Latarjet reconstruction restored translation to dislocation greater than the native intact joint for all sizes of humeral head defects. At 60° of ABD and 80° of ER, a 20% glenoid defect led to an overall decrease in translation to dislocation with increasing humeral head defects. While Latarjet augmentation resulted in increased translation to dislocation for all humeral head defect sizes, it was not able to restore translation greater than the native intact joint for large humeral head defects (31% and 44%); the normalized percentages of intact translation to dislocation were 65% and 30%, respectively. Conclusion: These results demonstrate that some degree of translation can be regained for combined bony glenoid and humeral head defects with the Latarjet procedure. However, for humeral defects larger than 31%, the rotational effect of the humeral head defect led to persistent decreased translation and to dislocation despite glenoid augmentation. Thus, directly addressing the humeral defect to restore the articular surface should be considered in these cases. Clinical Relevance: This study provides a critical value limit for combined anterior glenoid bone loss and humeral head defects. While this is a biomechanical study, the results indicate that in patients with humeral head defects greater than 31%, additional humeral-sided surgery may be needed.

Influence of Bony Defects on Preoperative Shoulder Function in Recurrent Anteroinferior Shoulder Instability

Background: Recurrent anteroinferior shoulder dislocations are often associated with bony glenoid and humeral defects. The influence of those bony lesions on the postoperative outcomes after arthroscopic shoulder stabilization procedures has been the subject of many studies. Little is known about the influence of those lesions on preoperative function. Purpose: To evaluate the influence of glenoid and humeral bony defects on preoperative shoulder function in recurrent anteroinferior shoulder instability. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Included in the study were 90 patients (70 men, 20 women; mean age, 27.1 years; 24 patients with prior failed stabilization) with posttraumatic recurrent anteroinferior shoulder instability who underwent preoperative computed tomography (CT) of both shoulders. The glenoid index was used to measure glenoid defect on a 3-dimensional CT. Humeral head defect was measured on a 2-dimensional CT with evaluation of the Hill-Sachs quotient, product, sum, and difference. Preoperative evaluation also included the Rowe score, Constant score, Walch-Duplay score, Melbourne Instability Shoulder Score (MISS), Western Ontario Shoulder Instability Index (WOSI), and Subjective Shoulder Value (SSV). Results: There was a weak but significant correlation of the Hill-Sachs quotient and the glenoid index with the Rowe score (P = .03, r = −0.22 and P = .03, r = 0.23, respectively). Furthermore, the Hill-Sachs product significantly correlated with the WOSI (P = .02); in particular, the physical symptoms subscore showed a significant correlation (P = .04). The glenoid index showed a significant correlation with the SSV (P < .01). No significant correlation was found between the Walch-Duplay score, Constant score, or MISS and bony defects. Conclusion: The results of this study show that objective and subjective scoring systems correlate significantly with the clinical condition of patients with recurrent shoulder instability and associated bony defects. It is recommended that clinicians use the Rowe score, WOSI, and SSV for the clinical evaluation of patients with recurrent anteroinferior shoulder instability and associated bony defects. These evaluation systems may provide an early clinical indication of bony defects. Furthermore, very poor results on these evaluations could underline the necessity of a CT scan for the diagnosis of bony defects in recurrent shoulder instability and might be helpful for decision making concerning the indication of a CT.

Stability of the Glenohumeral Joint With Combined Humeral Head and Glenoid Defects

Background: Shoulders with recurrent anterior instability often have combined bony defects of the humeral head and glenoid. Previous studies have looked at only isolated humeral head or glenoid defects. Purpose/Hypothesis: The aim of this study was to define the relationship of combined humeral head and glenoid defects on anterior shoulder instability. Combined bony defects will lead to increased instability compared with an isolated defect, and the “critical” size of humeral head and glenoid defects that need to be addressed to restore stability will be smaller when combined rather than isolated. Study Design: Controlled laboratory study. Methods: Eighteen shoulder specimens were tested at 60° of glenohumeral abduction and 80° of glenohumeral external rotation. Humeral head defect sizes included 6%, 19%, 31%, and 44% of the humeral head diameter. Glenoid defect sizes included 10%, 20%, and 30% of the glenoid width. Outcome measures included percentage of intact stability ratio (%ISR; the stability ratio for a given trial divided by the stability ratio in the intact state for that specimen) and percentage of intact translation (%IT; the distance to dislocation for a given trial divided by the distance to dislocation in the intact state for that specimen). Results: The decrease in %ISR reached statistical significance for humeral head defects of 44%, for glenoid defects of 30%, and for a combined 19% humeral head defect with a 20% glenoid defect (65% mean %ISR). The decrease in %IT reached statistical significance for humeral head defects ≥31%, for glenoid defects ≥20%, and for a combined 19% humeral head defect with a 10% glenoid defect (69% mean %IT). Conclusion: In shoulders with combined humeral head and glenoid defects, bony reconstruction may be indicated for humeral head defects as small as 19% of the humeral head diameter and glenoid defects as small as 10% to 20% of the glenoid width, especially if the glenoid defect produces a significant loss of glenoid concavity depth. Clinical Relevance: In shoulders with combined humeral head and glenoid defects, bony reconstruction may be indicated for defect sizes smaller than would be indicated for either defect found in isolation.

The Reduction in Stability From Combined Humeral Head and Glenoid Bony Defects Is Influenced by Arm Position

Background: Combined defects of the glenoid and humeral head are often a cause for recurrent shoulder instability. Purpose/Hypothesis: The aim of this study was to evaluate the influence of combined bony lesions on shoulder instability through varying glenohumeral positions. The hypothesis was that instability due to combined defects would be magnified with increasing abduction and external rotation. Study Design: Controlled laboratory study. Methods: Eighteen cadaveric shoulders were tested. Experiments were performed at combinations of glenohumeral abduction angles of 20°, 40°, and 60° and external rotations of 0°, 40°, and 80°. The various glenoid defect sizes created were 10%, 20%, and 30% of the glenoid width. Four humeral head defects were created based on humeral head diameter (6%, 19%, 31%, and 44%). Each experiment consisted of translating the glenoid in a posterior direction to simulate an anterior dislocation under a 50-N load. The instability was measured as a percentage of intact translation (ie, loss in translational distance normalized to the no-defect condition). Results: At 20° of abduction, instability increased from 100% to 85%, 70%, and 43% with increasing glenoid defect sizes of 10%, 20% and 30%, respectively, with a 6% humeral head defect. However, at a functional arm position of apprehension, these values were significantly decreased (P < .05) for humeral head defect sizes of 19%, 31%, and 44%, with translation values of 49%, 27%, and 2%, respectively. Conclusion: A humeral defect leads to rotational instability with the arm rotated into a functional position rather than a resting position. However, a significant glenoid defect can lead to loss of translation independent of changes in arm position. Combined defects as large as 44% of humeral head and 20% glenoid did not show instability at 20° of abduction and neutral position; however, defects as small as 19% humeral defect and 10% glenoid defect led to significant instability in the position of apprehension. Clinical Relevance: Instability at lower levels of abduction and external rotation clinically indicates larger bony defects and may need to be directly addressed, depending on the patient’s age and function.