Glenohumeral articular contact areas and pressures following labral and osseous injury to the anteroinferior quadrant of the glenoid

Surgical considerations for glenoid bone loss in anterior glenohumeral instability: a narrative review

PURPOSE

Treatment algorithms may consider many factors like glenoid and humeral bone loss, or scores such as the instability severity index score (ISIS). As most studies only evaluate a part of these factors, there is still no evidence-based consensus estalished. Our study aims to summarize the surgical options for treatment of glenoid bone loss (GBL) in anterior shoulder instability.

METHODS

Based on the current available literature, surgical options including Bankart repair and glenoid bone augmentation should be considered while taking into consideration the degree of bone loss which has been divided into < 10%, 10-20% and > 20%.

RESULTS

There are many new techniques evolving including arthroscopic anatomic glenoid reconstruction with bone blocks.

CONCLUSION

Future long-term outcome studies and randomized controlled trials comparing established techniques will be needed for new evidence-based treatment algorithms.

Reconstruction of recurrent shoulder dislocation with glenoid bone defect with 3D-printed titanium alloy pad: outcomes at 2-year minimum follow-up

BACKGROUND

To evaluate the outcome of shoulder arthroscopy-assisted implantation of three-dimensional (3D)-printed titanium pads for recurrent shoulder dislocation with glenoid bone defects.

METHODS

From June 2019 to May 2020, the clinical efficacy of 3D printed titanium pad implantation assisted by shoulder arthroscopy, for the treatment of recurrent shoulder dislocations with shoulder glenoid defects was retrospectively analyzed. The American Shoulder and Elbow Surgeons (ASES) shoulder, Rowe, and Constant scores were recorded before surgery and at 3 months, 6 months, 1 year, and 2 years after surgery. 3D computed tomography (CT) and magnetic resonance imaging were used to evaluate the location of the glenoid pad, bone ingrowth, joint degeneration, and osteochondral damage.

RESULTS

The mean age of the 12 patients was 21.4 (19-24) years and the mean follow-up time was 27.6 (24-35) months. The Visual Analog Scale score significantly improved from 5.67 ± 1.98 preoperatively to 0.83 ± 0.58 postoperatively (p = 0.012). The postoperative ASES score was significantly increased to 87.91 ± 3.47 compared with preoperative ASES score (46.79 ± 6.45) (p < 0.01). Rowe and Constant scores also improved from 22.5 ± 12.34 and 56.58 ± 7.59 preoperatively to 90.83 ± 4.69 and 90.17 ± 1.89 at 2 years postoperatively, respectively. CT performed 2 years after surgery showed that the pad perfectly replenished the bone-defective part of the shoulder glenoid and restored the articular surface curvature of the shoulder glenoid in the anterior-posterior direction, and the bone around the central riser of the pad was tightly united. Magnetic resonance imaging 2 years after surgery showed that the humeral head osteochondral bone was intact, and there was no obvious osteochondral damage.

CONCLUSIONS

3D printed titanium pads are a reliable, safe, and effective surgical procedure for treating recurrent shoulder dislocations with glenoid bone defects.

Arthroscopic Bankart repair with peeling osteotomy of the anterior glenoid rim preserves glenoid morphology

BACKGROUND

A decrease in the glenoid size after arthroscopic Bankart repair (ABR) was common in shoulders without osseous fragments compared with those with osseous fragments. For cases of chronic recurrent traumatic anterior glenohumeral instability without osseous fragments, we have performed ABR with peeling osteotomy of the anterior glenoid rim (ABRPO) to make an intentional osseous Bankart lesion. The aim of this study was to compare the glenoid morphology after ABRPO with it after simple ABR.

METHODS

The medical records of patients who underwent arthroscopic stabilization for chronic recurrent traumatic anterior glenohumeral instability were retrospectively reviewed. Patients with an osseous fragment, with revision surgery and without complete data were excluded. Patients were assigned to 1 of 2 groups: Group A, ABR without peeling osteotomy procedure or Group B, with ABRPO procedure. Computed tomography was performed preoperatively and 1 year after surgery. The size of the glenoid bone loss was investigated by the assumed circle method. The following formula was used to calculate the decreased size of the glenoid: (Δ) = (postoperative size of the glenoid bone loss) - (preoperative size of the glenoid bone loss). The size of the glenoid 1 year after surgery was assessed to determine if it had decreased (Δ > 0%) or not decreased (Δ ≤ 0%) relative to the preoperative size.

RESULTS

This study evaluated 39 shoulders divided into 2 groups: 27 shoulders in Group A and 12 shoulders in Group B. In Group A, postoperative glenoid bone loss was significantly greater than preoperative glenoid bone loss (7.8 ± 6.2 vs. 5.5 ± 5.3, respectively, P = .02). In Group B, postoperative glenoid bone loss was significantly lower than preoperative glenoid bone loss (5.6 ± 5.4 vs. 8.7 ± 4.0, respectively, P = .02). The P value for the interaction of group (A or B) × time (preoperative or postoperative) was 0.001. The decreased size of the glenoid was significantly larger in Group A than in Group B (2.1 ± 4.2 vs. -3.1 ± 4.5, respectively, P = .001). The rate of shoulders in which the size of the glenoid decreased 1 year after surgery relative to the preoperative size was significantly higher in Group A than in Group B (63% [17/27] vs. 25% [3/2], respectively, P = .04).

CONCLUSIONS

The study showed that ABRPO preserved the glenoid size better than simple ABR without a peeling osteotomy procedure.

Incidence of bony Bankart lesions in Sweden: a study of 790 cases from the Swedish fracture register

BACKGROUND

A bony Bankart lesion directly affects the stability of the shoulder by reducing the glenoid joint-contact area. The aim of this study was to report on the epidemiological data relating to bony Bankart lesions in Sweden using the Swedish fracture register. The purpose is to evaluate age and sex distribution in the population with bony Bankart lesions, its impact on treatment strategy and further to analyse patient-reported outcomes.

METHODS

This was an epidemiological descriptive study. The inclusion criteria were all patients with a unilateral bony Bankart lesion registered between April 2012 and April 2019. The patients' specific data (age, sex, type and time of injury, treatment option and patient-reported outcomes) were extracted from the Swedish fracture register database.

RESULTS

A total of 790 unilateral bony Bankart fractures were identified. The majority of the patients were male (58.7%). The median age for all patients at the time of injury was 57 years. Females had a higher median age of 66 years, compared with males, 51 years. Most of the bony Bankart lesions, 662 (91.8%), were registered as a low-energy trauma. More than two-thirds of all treatment registered cases, 509/734 patients (69.3%), were treated non-surgically, 225 (30.7%) were treated surgically, while, in 17 patients (7.5% of all surgically treated patients), the treatment was changed from non-surgical to surgical due to recurrent instability. Surgical treatment was chosen for 149 (35%) of the males and for 76 (25%) of the females. Patient quality of life decreased slightly in both surgically and non-surgically treated groups 1 year after bony Bankart injury.

CONCLUSION

This national register-based study provides detailed information on the epidemiology, choice of treatment and patient-reported outcomes in a large cohort of bony Bankart lesions. Most bony Bankart lesions affected males between 40 and 75 years after low-energy falls and non-surgical treatment dominated.

Arthroscopic Bankart Repair for Adolescent Anterior Shoulder Instability: Clinical and Imaging Predictors of Revision Surgery and Recurrent Subjective Instability

BACKGROUND

Multiple clinical and radiologic risk factors for recurrent instability after arthroscopic Bankart repair have been described. Humeral bone loss has gained more recent attention, particularly with respect to "off-track" lesions and increased rates of recurrent instability and revision surgery.

PURPOSE

To evaluate clinical and radiologic predictors of failure after arthroscopic Bankart repair in adolescents.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A single-institution retrospective study was performed in patients <19 years of age treated with arthroscopic Bankart repair from 2011 to 2017. Magnetic resonance imaging measurements of glenoid and humeral bone loss, the glenoid track, and the presence of off-track Hill-Sachs (HS) lesions were assessed. All patients had a minimum follow-up of 24 months and completed patient-reported outcome scores. Failure was defined as revision surgery or postoperative subjective instability.

RESULTS

A total of 59 patients (46 male, 13 female) with a median age of 16 years (range, 12-18 years) were included. Ten patients (17%) had revision surgery and 8 patients (14%) had subjective instability without revision surgery. No clinical or radiologic factors were significantly different between the failure cohort and the nonfailure cohort. Four patients (7%) measured off-track, and 2 of these patients experienced failure. A total of 38 patients (64%) were identified to have an HS defect. Subgroup analysis of these patients identified a greater HS interval (HSI) in patients who underwent revision surgery as compared with those patients who did not have revision surgery. Among patients with GT ratio ≥15 mm, there was a 50% rate of revision surgery. The Pediatric/Adolescent Shoulder Survey (PASS) and Single Assessment Numeric Evaluation (SANE) scores at the final follow-up were not significantly different among patients with or without revision surgery. However, those with subjective instability who had not undergone revision surgery had significantly lower PASS and SANE scores as compared with the remainder of the cohort.

CONCLUSION

Of the adolescents in this cohort, 31% either had revision surgery (17%) or reported subjective feelings of instability (14%) after arthroscopic Bankart repair. Off-track instability was identified in 7% of the cohort but was not predictive of failure. Among the subgroup of patients with an HS defect, those who underwent revision surgery had a significantly larger HSI.

Functional biomechanical comparison of Latarjet vs. distal tibial osteochondral allograft for anterior glenoid defect reconstruction

INTRODUCTION

Glenoid reconstruction is indicated for recurrent glenohumeral instability with significant glenoid bone deficiency. Coracoid autograft (Latarjet) and distal tibial osteochondral allograft (DTA) reconstructions have been used to successfully restore glenohumeral stability. Relative advantages and disadvantages associated with each reconstruction technique have been described. However, direct comparisons of functional glenohumeral biomechanics associated with Latarjet vs. DTA reconstruction are lacking. This study was designed to compare these 2 glenoid reconstruction techniques with respect to joint kinematics and cartilage pressure mapping using a robotic testing system.

METHODS

In accordance with institutional review board policies, human cadaveric shoulders (n = 8) were cyclically tested in the neutral position and 90° of external rotation with 60° and 90° of abduction under a 45-N joint-compression load to measure clinically relevant translations, loads, and torques. Joint contact pressure maps were obtained under a 120-N joint-compression load using pressure mapping sensors. After confirming that a 25% anterior glenoid defect resulted in glenohumeral dislocation, testing was performed to compare 3 conditions: native intact glenoid, 25% anterior glenoid defect with Latarjet reconstruction, and 25% anterior glenoid defect with DTA reconstruction. Analyses of variance and t tests were used to analyze data with statistical significance set at P < .05.

RESULTS

Significant differences in anterior translation, inferior drawer, anterior drawer, compression loads, horizontal abduction, negative elevation (adduction), and external rotation torques during cyclical testing in 90° of external rotation with 60° and/or 90° of abduction were noted when comparing the 2 different glenoid bone reconstruction techniques to native, intact shoulders. The only significant difference between Latarjet and DTA reconstructions for measured translations, loads, and torques was a significantly higher absolute maximum compressive load for Latarjet compared to DTA at 60° of abduction.

CONCLUSION

Latarjet coracoid osseous autograft and distal tibial osteochondral allograft reconstructions of large (25%) glenoid bone defects prevent failure (dislocation) and are associated with significant glenohumeral kinematic differences that largely confer less translation, load, and torque on the joint in abduction when compared to the native state. These findings suggest that these 2 surgical techniques exhibit similar glenohumeral kinematics such that each provides adequate functional stability following anterior glenoid bone reconstruction. Joint compression load and articular contact pressure distribution may favor distal tibial osteochondral allograft reconstruction for treatment of large (25%) anterior glenoid bone defects associated with shoulder instability.

Mechanistic insights into glenohumeral kinematics derived from positional relationship between the contact path and humeral tuberosity

Although three-dimensional (3D) glenohumeral (GH) motion has generally been expressed only by rotational elements, its mechanistic details, including GH rotations, remain unknown owing to a lack of geometric investigations. This study aims to investigate the positional relationship between the contact path and humeral tuberosities at the GH joint during arm elevation and to consider the mechanism of GH kinematics. Shoulder kinematics were captured using two-dimensional and 3D single-plane image registration techniques in 15 young healthy subjects during flexion, scaption, and abduction. The glenoid movement relative to the humeral head was calculated to describe the contact path on the humeral head. From the start to 45° of flexion, scaption, and abduction, the glenoid center moved from the anteromedial to the anterior, central, and posterior portions of the humeral head, respectively, as the GH joint rotated externally. From 45° to the maximal elevation for all elevation planes, the glenoid center moved upward to the humeral head and came close to the bicipital groove (BG) at maximal elevation, while the glenoid maintained a constant inclination at 20°-40° relative to the humerus. To investigate this mechanism, the position of humeral tuberosities relative to the glenoid was calculated, and the BG was found to face the supraglenoid tubercle, the attachment site of the long head of biceps (LHB). GH external rotation mainly occurred depending on the elevation planes in the early phase of elevation, and it might be kept constant by the LHB and rotator cuff in the mid- to end range of elevation.

Surgeon variation in glenoid bone reconstruction procedures for shoulder instability

BACKGROUND

Advances in the understanding and management of glenoid bone loss in shoulder instability have led to the development of alternative bony reconstruction techniques to the Latarjet using free bone grafts, but little is known about surgeon adoption of these procedures. This study sought to characterize surgeon variation in the use of glenoid bone reconstruction procedures for shoulder instability and ascertain reasons underlying procedure choice.

METHODS

A 9-question survey was created and distributed to 160 shoulder surgeons members of the PacWest Shoulder and Elbow Society, of whom 65 (41%) responded. The survey asked questions regarding fellowship training, years in practice, surgical volume, preferred methods of glenoid bone reconstruction, and reasons underlying treatment choice.

RESULTS

All surgeons completed a fellowship, with an equal number of sports medicine fellowship-trained (46%) and shoulder and elbow fellowship-trained (46%) physicians. The majority had been in practice for at least 6 years (6-10 years: 25%; >10 years: 59%). Most (78%) performed ≤10 glenoid bony reconstructions per year, and 66% indicated that bony procedures represented <10% of their total annual shoulder instability case volume. The open Latarjet was the preferred primary reconstruction method (69%), followed by open free bone block (FBB) (22%), arthroscopic FBB (8%), and arthroscopic Latarjet (1%). Distal tibia allograft (DTA) was the preferred graft (74%) when performing an FBB procedure, followed by iliac crest autograft (18%), and distal clavicle autograft (6%). The top 5 reasons for preferring Latarjet over FBB were the sling effect (57%), the autologous nature of the graft (37%), its robust clinical evidence (22%), low cost (17%), and availability (11%). The top 5 reasons for choosing an FBB procedure were less anatomic disruption (58%), lower complication rate (21%), restoration of articular cartilage interface (16%), graft versatility (11%), and technical ease (11%). Only 20% of surgeons indicated always performing a bony glenoid reconstruction procedure in the noncontact athlete with less than 20% glenoid bone loss. However, that percentage rose to 62% when considering a contact athlete with the same amount of bone loss.

CONCLUSIONS

Although open Latarjet continues to be the most popular glenoid bony primary reconstruction procedure in shoulder instability, nearly 30% of shoulder surgeons in the western United States have adopted FBB techniques as their preferred treatment modality--with DTA being the most frequently used graft. High-quality comparative clinical effectiveness research is needed to reduce decisional conflict and refine current evidence-based treatment algorithms.

A stabilizing role of the glenoid labrum: the suction cup effect

BACKGROUND

The glenoid labrum acts as a bumper, deepening glenoid concavity and amplifying the concavity-compression mechanism, and serves as the scapular attachment for glenohumeral ligaments. The role of the posterosuperior labrum in anteroinferior glenohumeral stability, and the role of the anterior labrum in posterior stability has been debated. The purpose of this study was to quantify the contribution of anteroinferior and posterosuperior labral tears to loss of glenohumeral stability in multiple directions.

METHODS

Fourteen fresh-frozen cadaveric shoulders were tested on a custom stability ratio measurement apparatus. The peak force that was required to translate the humeral head in anterior, anteroinferior, posterior, and posteroinferior directions was measured under 5 conditions: intact labrum (n = 14), anteroinferior labral tear (n = 7), posterosuperior labral tear (n = 7), combined labral tear (n = 14), and no labrum (n = 14). The stability ratio was defined as the peak translational force divided by the compressive force. Within force-translation curves, we defined the suction cup effect as the force required to release the negative pressure created by an intact labrum.

RESULTS

The suction cup effect was usually present with the intact labrum and always disappeared after removal of the labrum for anterior (100% vs. 0%) and posterior (86% vs. 0%) translations (P < .001). After creation of an anteroinferior labral tear, the stability ratio for posterior direction decreased (P < .001) and the suction cup effect disappeared (P < .001). After creation of a posterosuperior labral tear, stability ratios in the anterior and anteroinferior directions decreased (P ≤ .006) and the suction cup effect disappeared (P ≤ .015). The stability ratio for anterior and anteroinferior testing was more diminished by posterosuperior labral tears than anteroinferior labral tears, and the stability ratio for posterior testing was more diminished by anteroinferior labral tears than posterosuperior labral tears.

CONCLUSION

Anteroinferior labral tears decreased posterior stability and posterosuperior labral tears decreased anterior and anteroinferior stability, largely because of loss of the suction cup effect.

Comparison of computed tomography and 3D magnetic resonance imaging in evaluating glenohumeral instability bone loss

BACKGROUND

To determine whether the addition of 3-dimensional (3D) magnetic resonance imaging (MRI) to standard MRI sequences is comparable to 3D computed tomographic (CT) scan evaluation of glenoid and humeral bone loss in glenohumeral instability.

METHODS

Eighteen patients who presented with glenohumeral instability were prospectively enrolled and received both MRI and CT within 1 week of each other. The MRI included an additional sequence (volumetric interpolated breath-hold examination [VIBE]) that underwent postprocessing for reformations. The addition of a VIBE protocol, on average, is an additional 4-4.5 minutes in the scanner. CT data also underwent 3D postprocessing, and therefore each patient had 4 imaging modalities (2D CT, 2D MRI, 3D CT reformats, and 3D MRI reformats). Each sequence underwent the following measurements from 2 separate reviewers: glenoid defect, glenoid defect percentage, humeral defect, humeral defect percentage, and evaluation of glenoid track and version. Paired t tests were used to assess differences between imaging modalities and χ² for glenoid track. Intra- and interobserver reliability were evaluated. Bland-Altman tests were also performed to assess the agreement between CT and MRI. In addition, we determined the cost of each imaging modality at our institution.

RESULTS

3D MRI measurements for glenoid and humeral bone loss measurements were comparable to 3D CT (Table 1). There were no significant differences for glenoid defect size and percentage, or humeral defect size and percentage (P > .05) (Table 2). Bland-Altman analysis demonstrated strong agreement, with small measurement errors for 3D CT and 3D MRI percentage glenoid bone loss. There was also no difference in evaluation for determining on vs. off track between any of the imaging modalities. Inter- and intrarater reliability was good to excellent for all CT and MRI measurements (r ≥ 0.7).

CONCLUSION

3D MRI measurements for bone loss in glenohumeral instability through use of VIBE sequence were equivalent to 3D CT. At our institution, undergoing MRI with 3D reconstruction was 1.67 times cheaper than MRI and CT with 3D reconstructions. 3D MRI may be a useful adjuvant to standard MRI sequences to allow concurrent soft tissue and accurate assessment of glenoid and humeral bone loss in glenohumeral instability.

Dislocation Arthropathy of the Shoulder

Glenohumeral osteoarthrosis (OA) may develop after primary, recurrent shoulder dislocation or instability surgery. The incidence is reported from 12 to 62%, depending on different risk factors. The risk of severe OA of the shoulder following dislocation is 10 to 20 times greater than the average population. Risk factors include the patient’s age at the first episode of instability or instability surgery, bony lesions, and rotator cuff tears. For mild stages of OA, arthroscopic removal of intraarticular material, arthroscopic debridement, or arthroscopic arthrolysis of an internal rotation contracture might be sufficient. For severe stages, mobilization of the internal rotation contracture and arthroplasty is indicated. With an intact rotator cuff and without a bone graft, results for anatomical shoulder arthroplasty are comparable to those following primary OA. With a bone graft at the glenoidal side, the risk for implant loosening is ten times greater. For the functional outcome, the quality of the rotator cuff is more predictive than the type of the previous surgery or the preoperative external rotation contracture. Reverse shoulder arthroplasty could be justified due to the higher rate of complications and revisions of non-constrained anatomic shoulder arthroplasties reported. Satisfactory clinical and radiological results have been published with mid to long term data now available.

Anatomical, functional and biomechanical review of the glenoid labrum

The glenohumeral joint is the most mobile joint in the human skeleton, supported by both active and passive stabilisers. As one of the passive stabilisers, the glenoid labrum has increasingly been recognised to play an important role in stability of the glenohumeral joint, acting to maintain intraarticular pressure, centralise the humeral head and contribute to concavity-compression stability. Several studies have investigated the macro- and micro-anatomical features of the labrum as well as its biomechanical function. However, in order to better understand the role of the labrum and its mechanics, a comprehensive anatomical, functional and biomechanical review of these studies is needed. Therefore, this article reviews the current literature detailing anatomical descriptions of the glenoid labrum, with an emphasis on its function(s) and biomechanics, as well as its interaction with neighbouring structures. The intimate relationship between the labrum and the surrounding structures was found to be important in glenohumeral stability, which owes further investigation into the microanatomy of labrum to better understand this relationship.

Four-dimensional computed tomography evaluation of shoulder joint motion in collegiate baseball pitchers

The purpose of this study is to evaluate the glenohumeral contact area, center of glenohumeral contact area, and center of humeral head during simulated pitching motion in collegiate baseball pitchers using four-dimensional computed tomography (4D CT). We obtained 4D CT data from the dominant and non-dominant shoulders of eight collegiate baseball pitchers during the cocking motion. CT image data of each joint were reconstructed using a 3D reconstruction software package. The glenohumeral contact area, center of glenohumeral contact area, center of humeral head, and oblateness of humeral head were calculated from 3D bone models using customized software. The center of glenohumeral contact area translated from anterior to posterior during maximum external rotation to maximum internal rotation (0.58 ± 0.63 mm on the dominant side and 0.99 ± 0.82 mm on the non-dominant side). The center of humeral head translated from posterior to anterior during maximum external rotation to maximum internal rotation (0.76 ± 0.75 mm on the dominant side and 1.21 ± 0.78 mm on the non-dominant side). The increase in anterior translation of the center of glenohumeral contact area was associated with the increase in posterior translation of the center of humeral head. Also, the increase in translation of the center of humeral head and glenohumeral contact area were associated with the increase in oblateness of the humeral head. 4D CT analyses demonstrated that the center of humeral head translated in the opposite direction to that of the center of glenohumeral contact area during external rotation to internal rotation in abduction in the dominant and non-dominant shoulders. The oblateness of the humeral head may cause this diametric translation. 4D CT scanning and the software for bone surface modeling of the glenohumeral joint enabled quantitative assessment of glenohumeral micromotion and be used for kinematic evaluation of throwing athletes.

Arthroscopy Limits on Anterior Shoulder Instability

Much is discussed about the limits of the treatment of anterior shoulder instability by arthroscopy. The advance in understanding the biomechanical repercussions of bipolar lesions on shoulder stability, as well as in the identification of factors related to the higher risk of recurrence have helped us to define, more accurately, the limits of arthroscopic repair. We emphasize the importance of differentiation between glenoid bone loss due to erosion (GBLE) and glenoid edge fractures, because the prognosis of treatment differs between these forms of glenoid bone failure. In this context, we understand that there are three types of bone failure: a) bone Bankart (fracture); b) combined; and c) glenoid bone loss due to anterior erosion (GBLE), and we will address the suggested treatment options in each situation. Until recently, the choice of surgical method was basically made by the degree of bone involvement. With the evolution of knowledge, the biomechanics of bipolar lesions and the concept of glenoid track , the cutoff point of critical injury, has been altered with a downward trend. In addition to bone failures or losses, other variables were added and made the decision more complex, but a little more objective. The present update article aims to make a brief review of the anatomy with the main lesions found in instability; to address important details in arthroscopic surgical technique, especially in complex cases, and to bring current evidence on the issues of greatest divergence, seeking to guide the surgeon in decision making.

Chondral Damage After Arthroscopic Repair Techniques for Acute Bony Bankart Lesions: A Biomechanical Study

BACKGROUND

Bony Bankart lesions can be encountered during treatment of shoulder instability. Current arthroscopic bony Bankart repair techniques involve intra-articular suture placement, but the effect of these repair techniques on the integrity of the humeral head articular surface warrants further investigation.

PURPOSE

To quantify the degree of humeral head articular cartilage damage secondary to current arthroscopic bony Bankart repair techniques in a cadaveric model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Testing was performed in 13 matched pairs of cadaveric glenoids with simulated bony Bankart fractures, with a defect width of 25% of the glenoid diameter. Half of the fractures were repaired with a double-row technique, while the contralateral glenoids were repaired with a single-row technique. Samples were subjected to 20,000 cycles of internal-external rotation across a 90° arc at 2 Hz after a compressive load of 750 N, or 90% body weight (whichever was less) was applied to simulate wear. Cartilage defects on the humeral head were quantified through a custom MATLAB script. Mean cartilage cutout differences were analyzed by the Wilcoxon rank-sum test.

RESULTS

Both single- and double-row repairs showed macroscopic damage. The histomorphometric analysis demonstrated that the double-row technique resulted in a significantly (P = .036) more chondral damage (mean, 57,489.1 µm²; SD, 61,262.2 µm²) than the single-row repair (mean, 28,763.5 µm²; SD, 24,4990.2 µm²).

CONCLUSION

Both single-row and double-row arthroscopic bony Bankart fixation techniques resulted in damage to the humeral head articular cartilage in the concavity-compression model utilized in this study. The double-row fixation technique resulted in a significantly increased cutout to the humeral head cartilage after simulated wear in this cadaveric model.

CLINICAL RELEVANCE

This study provides data demonstrating that placement of intra-articular suture during arthroscopic bony Bankart repair techniques may harm the humeral head cartilage. While the double-row repair of bony Bankart lesions is more stable, it results in increased cartilage damage. These findings suggest that alternative, cartilage-sparing arthroscopic techniques for bony Bankart repair should be investigated.

Early postoperative complications after Latarjet procedure: a single-institution experience over 10 years

BACKGROUND

The Latarjet procedure is an effective procedure for the treatment of anterior glenohumeral joint instability; however, the complications are concerning. The purpose of this study was to review a single institution's experience with the Latarjet procedure for recurrent anterior glenohumeral instability specifically focusing on early complications.

METHODS

This was a retrospective review of all Latarjet procedures performed at a single institution from August 2008 to July 2018. The 90-day complication rate and associated risk factors for all complications and graft failure were recorded. Postoperative radiographs were reviewed for coracoid graft position and screw divergence.

RESULTS

During the study period, 190 Latarjet procedures were performed with 90-day follow-up. The average age was 28.7 ± 11.3 years, male patients comprised 84.2% of the population, and 62.6% of patients had undergone a prior stabilization procedure. We observed 15 complications, for a 90-day complication rate of 9.0%; of the patients, 8 (4.2%) underwent reoperations. Graft or hardware failure occurred in 9 patients (4.7%) with loosened or broken screws, and 6 required reoperations (revision Latarjet procedure in 4, distal tibia allograft in 1, and iliac crest autograft in 1). Fixation with only 1 screw (P < .001) and an increased screw divergence angle (37° ± 8° vs. 24° ± 11°, P = .0257) were statistically associated with graft failure, whereas the use of cannulated screws (P = .487) was not. There were 6 nerve injuries (3.2%), including 2 combined axillary and suprascapular nerve injuries, 1 musculocutaneous nerve injury, 1 brachial plexopathy, 1 peripheral sensory nerve deficit (likely axillary), and 1 sensory plexopathy. Suprascapular nerve injury at the spinoglenoid notch was associated with a longer superior screw (41.0 ± 1.4 mm vs. 33.5 ± 3.5 mm, P = .035) and increased screw divergence angle (40° ± 6° vs. 24° ± 11°, P = .0197). The coracoid graft was correctly positioned in the axial plane in 71% of cases and in the coronal plane in 73% of cases.

CONCLUSION

The Latarjet procedure is a procedure that can reliably restore shoulder stability; however, graft- and nerve-related complications are relatively common. Two-thirds of the graft failures required reoperations, and half of the nerve injuries in this study led to residual symptoms. Fixation with only 1 screw and an increased screw divergence angle were significant predictors of graft failure. Suprascapular nerve injury at the spinoglenoid notch was associated with an increased screw divergence angle and longer superior screw.

A Biomechanical, Cadaveric Evaluation of Single- Versus Double-Row Repair Techniques on Stability of Bony Bankart Lesions

BACKGROUND

Previous studies comparing stability between single- and double-row arthroscopic bony Bankart repair techniques focused only on the measurements of tensile forces on the bony fragment without re-creating a more physiologic testing environment.

PURPOSE

To compare dynamic stability and displacement between single- and double-row arthroscopic repair techniques for acute bony Bankart lesions in a concavity-compression cadaveric model simulating physiologic conditions.

STUDY DESIGN

Controlled laboratory study.

METHODS

Testing was performed on 13 matched pairs of cadaveric glenoids with simulated bony Bankart fractures with a defect width of 25% of the inferior glenoid diameter. Half of the fractures were repaired with a double-row technique, and the contralateral glenoids were repaired with a single-row technique. To determine dynamic biomechanical stability and ultimate step-off of the repairs, a 150-N load and 2000 cycles of internal-external rotation at 1 Hz were applied to specimens to simulate early rehabilitation. Toggle was quantified throughout cycling with a coordinate measuring machine. Three-dimensional spatial measurements were calculated. After cyclic loading, the fracture displacement was measured.

RESULTS

The bony Bankart fragment-glenoid initial step-off was found to be significantly greater (P < .001) for the single-row technique (mean, 896 µm; SD, 282 µm) compared with the double-row technique (mean, 436 µm; SD, 313 µm). The motion toggle was found to be significantly greater (P = .017) for the single-row technique (mean, 994 µm; SD, 711 µm) compared with the double-row technique (mean, 408 µm; SD, 384 µm). The ultimate interface displacement was found to be significantly greater (P = .029) for the single-row technique (mean, 1265 µm; SD, 606 µm) compared with the double-row technique (mean, 795 µm; SD, 398 µm).

CONCLUSION

Using a concavity-compression glenohumeral cadaveric model, we found that the double-row arthroscopic fixation technique for bony Bankart repair resulted in superior stability and decreased displacement during simulated rehabilitation when compared with the single-row repair technique.

CLINICAL RELEVANCE

The findings from this study may help guide surgical decision-making by demonstrating superior biomechanical properties (improved initial step-off, motion toggle, and interface displacement) of the double-row bony Bankart repair technique when compared with single-row fixation. The double-row repair construct demonstrated increased stability of the bony Bankart fragment, which may improve bony Bankart healing.

Shoulder biomechanics in normal and selected pathological conditions

The stability of the glenohumeral joint depends on soft tissue stabilizers, bone morphology and dynamic stabilizers such as the rotator cuff and long head of the biceps tendon. Shoulder stabilization techniques include anatomic procedures such as repair of the labrum or restoration of bone loss, but also non-anatomic options such as remplissage or tendon transfers.

Rotator cuff repair should restore the cuff anatomy, reattach the rotator cable and respect the coracoacromial arch whenever possible. Tendon transfer, superior capsular reconstruction or balloon implantation have been proposed for irreparable lesions.

Shoulder rehabilitation should focus on restoring balanced glenohumeral and scapular force couples in order to avoid an upward migration of the humeral head and secondary cuff impingement. The primary goal of cuff repair is to be as anatomic as possible and to create a biomechanically favourable environment for tendon healing.

Cite this article: EFORT Open Rev 2020;5:508-518. DOI: 10.1302/2058-5241.5.200006

Maximum Bridging Suture Tension Provides Better Clinical Outcomes in Transosseous-Equivalent Rotator Cuff Repair: A Clinical, Prospective Randomized Comparative Study

BACKGROUND

Some studies reporting clinical outcomes after transosseous-equivalent (TOE) repair have attributed type II rotator cuff failure to excessive bridging suture tension, as it can cause overloading on the medial row. In a previous biomechanical cadaveric study, increasing bridging suture tension over 90 N did not improve the contact area and ultimate failure load of the TOE construct, despite increasing the contact force and contact pressure.

PURPOSE

To compare the clinical outcomes of different bridging suture tensions after TOE rotator cuff repair based on the results of a previous biomechanical study.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

A total of 78 patients who underwent arthroscopic rotator cuff repair for medium- to large-sized tears were prospectively enrolled and randomly divided into 2 groups according to the applied bridging suture tension: optimum tension group (96.3 ± 4.9 N) and maximum tension group (199.0 ± 20.3 N). Bridging suture tension was measured with a customized tensiometer, as used in the previous biomechanical study. The functional outcome was measured at the final follow-up (27.4 ± 5.9 months [range, 24-45 months]) using the visual analog scale for pain, American Shoulder and Elbow Surgeons score, Simple Shoulder Test, and Constant score, and the anatomic outcome was evaluated using magnetic resonance imaging or ultrasonography at least 12 months after surgery.

RESULTS

Overall, 64 patients (32 in each group) were analyzed. The functional outcomes improved significantly compared with preoperative values (all P < .05) but did not show significant differences between the 2 groups (all P > .05). Regarding the anatomic outcomes, the maximum tension group (n = 1; 3.1%) had a significantly lower healing failure rate than the optimum tension group (n = 9; 28.1%) (P = .013). One patient in the maximum tension group had a type II failure.

CONCLUSION

Maximum bridging suture tension in TOE repair for medium- to large-sized rotator cuff tears provided better anatomic healing with less risk of medial rotator cuff failure, which differs from the results of a previous time-zero biomechanical study.

Revision anterior glenohumeral instability: is arthroscopic treatment an option?

Background

The purpose of this study was to determine the short-term outcomes for patients who underwent revision surgery for shoulder instability, including both revision arthroscopic repair and Latarjet.

Methods

This study included patients who underwent revision of a prior arthroscopic labral repair to arthroscopic labral repair or Latarjet at our institution from 2012 to 2017. After collection of preoperative demographic data, preoperative 3-dimensional imaging was reviewed to determine percent glenoid bone loss (%GBL) and to determine whether each shoulder was on-track or off-track. Patients were contacted to obtain postoperative patient-reported outcome metrics including visual analog scale pain, Simple Shoulder Test, American Shoulder and Elbow Surgeons scores, and instability recurrence (full dislocation, subluxation, or subjective apprehension) data at a minimum of 2 years postoperatively.

Results

Of 62 patients who met criteria, 45 patients were able to be contacted. Of them, 21 underwent revision arthroscopy and 24 underwent a Latarjet procedure. In the revision arthroscopy group, 5 of 15 had %GBL >20% and 4 of 21 were contact athletes. In the Latarjet group, 11 of 22 had %GBL >20% and 5 of 24 were contact athletes. Of 21 revision arthroscopy patients, 8 underwent concomitant remplissage. Eight of 21 patients in the revision arthroscopy group and 7 of 21 patients in the Latarjet group reported instability postoperatively. Three of 21 patients in the revision arthroscopy group and 2 of 21 patients in the Latarjet group reported full dislocations postoperatively. Zero patients in the revision arthroscopy group and 1 of 21 patients in the Latarjet group underwent reoperation.

Conclusion

Our results suggest that both revision Latarjet and arthroscopic stabilization can be of benefit in select circumstances. However, in revision settings, postoperative instability symptoms are common with both procedures.

[Current concepts of diagnostic techniques and measurement methods for bone defect in patient with anterior shoulder instability]

Objective

To summarize the diagnosis and measurement methods of bone defect in anterior shoulder instability (glenoid bone defect and Hill-Sachs lesion).

Methods

The related literature on the diagnosis and measurement of the bone defect in anterior shoulder instability was reviewed and summarized.

Results

The commonly used techniques for the diagnosis of anterior glenoid bone defect and Hill-Sachs lesion of humeral head include X-ray, CT, MRI, arthroscopy, arthrography. The methods for measuring the degree of anterior glenoid bone defect include Griffith method, glenoid index method, Pico method, and best-fit circle method. The indexes for measuring the Hill-Sachs lesion include the length, width, depth, and volume. X-ray is mainly used for primary screening. Best-fit circle method on three-dimensional (3D) CT reconstruction is commonly used to measure the glenoid bone defect currently. Glenoid track theory on 3D CT reconstruction is popular in recent years. Reliability of measuring the glenoid bone defect and Hill-Sachs lesion with MRI and arthroscopy is still debatable. Arthrography is more and more used in the diagnosis of shoulder joint instability of bone defect and concomitant soft tissue injury.

Conclusion

How to improve the accuracy of evaluating glenoid bone defect and Hill-Sachs lesion before surgery still need further study.

Arthroscopic Knotless Remplissage for the Treatment of Hill-Sachs Lesions Using the PASTA Bridge Configuration

Recurrent glenohumeral dislocations can produce Hill-Sachs lesions-bony defects on the humeral head resulting from the humerus hitting the glenoid during dislocations. Some of these lesions can engage on the glenoid during motion, producing instability and potentially affecting the success of a labral repair. The remplissage was developed to address these Hill-Sachs lesions and improve stability. French for "filling," the goal of the remplissage is to fill the Hill-Sachs lesion with the infraspinatus tendon, preventing the margins of the lesion from engaging with the glenoid. Analogous to restoring the rotator cuff footprint during repair, a primary goal of the remplissage is to have the infraspinatus cover the Hill-Sachs lesion. The partial articular supraspinatus tendon avulsion (PASTA) bridge was originally developed for partial-thickness rotator cuff repair in situ, but additional uses have been found in other settings. The PASTA bridge uses a medial row horizontal mattress with a lateral anchor to create a linked construct to effectively distribute force and provide adequate coverage of the lesion. Knotless anchor technology used in this procedure prevents the need for arthroscopic knot tying and potentially damaging knot stacks. This Technical Note describes a remplissage technique using the PASTA bridge configuration to address Hill-Sachs lesions associated with recurrent glenohumeral instability.

The arthroscopic Bankart repair procedure enables complete quantitative labrum restoration in long-term assessments

PURPOSE

The restoration of the labrum complex and the influence on secondary osteoarthritis after arthroscopic Bankart repair on magnetic resonance imaging (MRI) remain unclear.

METHODS

Twenty-one patients were retrospectively followed after unilateral primary arthroscopic Bankart repair with knot-tying suture anchors (8.8 ± 2.5 years after surgery, age 25.3 ± 6.3 years). Bilateral structural MRI was performed to assess labrum-glenoid restoration by measurements of the labrum slope angle, height index, and labrum interior morphology according to the Randelli classification. Osteoarthritic status was bilaterally assessed by a modified assessment based on the Samilson-Prieto classification.

RESULTS

MRI assessment revealed full labrum-glenoid complex restoration with equivalent parameters for anterior slope angle (mean ± SD: 21.3° ± 2.6° after Bankart repair vs. 21.9° ± 2.6° control) and height index (2.34 ± 0.4 vs. 2.44 ± 0.4), as well as the inferior slope angle (23.1° ± 2.9° vs. 23.3° ± 2.1°) and height index (2.21 ± 0.3 vs. 2.21 ± 0.3) (all n.s.). The labrum morphology showed only for the anterior labrum significant alterations (1.4 ± 0.9 vs. 0.6 ± 0.7, p < 0.05), the inferior labrum occurred similarly (1.3 ± 0.8 vs. 0.8 ± 0.5, n.s.). Osteoarthritic changes were significantly increased after Bankart repair compared to the uninjured shoulder (4.8 ± 5.1 mm vs. 2.5 ± 1.0 mm; p < 0.05), with a significant correlation of osteoarthritis status between both shoulders (p < 0.05). Scores generally decreased after Bankart repair (constant 84.6 ± 9.5 vs. 94.5 ± 4.9 control, p < 0.05; Rowe 84.5 ± 6.5 vs. 96.2 ± 4.2, p < 0.05; Walch-Duplay 82.4 ± 7.0 vs. 94.3 ± 4.0, p < 0.05) with a strong correlation with osteoarthritis status (p < 0.05).

CONCLUSIONS

Arthroscopic Bankart repair enabled good clinical outcomes and complete quantitative labrum restoration parameters. Next to several well-known parameters, secondary osteoarthritis after arthroscopic Bankart repair significantly correlated with osteoarthritic status of the uninjured contralateral shoulder but was not influenced by quantitative labrum restoration. The recommendation for arthroscopic Bankart repair should be based on clinical parameters and not on prevention of secondary osteoarthritis.

STUDY DESIGN

Case series.

LEVEL OF EVIDENCE

IV.

ARTHROSCOPIC LATARJET TECHNIQUE COMBINED WITH ENDOBUTTONS: FUNCTIONAL OUTCOMES IN 26 CASES

Objective

The cause of anterior shoulder instability is not fully understood and surgical management remains controversial. The objective of this study was to evaluate the results of patients undergoing arthroscopic Latarjet procedure with endobuttons.

Methods

A retrospective study of 26 patients undergoing arthroscopic Latarjet procedure with endobuttons to treat anterior shoulder instability. Patients with previous glenohumeral instability, failure of Bankart procedure or Instability Severity Index Score (ISIS) greater than or equal to 6, were included. Patients were assessed by: DASH, UCLA, Rowe, Visual Analog Scale (VAS) of pain and Short-Form 36 (SF36) scores. Correct position and consolidation of the graft were evaluated.

Results

Mean age was 31.5 years (16 to 46). Preoperative duration of symptoms was 1.7 years (1 month to 10 years). Mean follow-up was 14.3 (6 to 24) months. Mean postoperative scores were: 10 points in DASH; 1.6 in VAS, where 23 (88%) patients experienced mild pain and 3 (12%) moderate pain; 89 in Rowe; 32 in UCLA and 78 in SF-36. Positioning of the graft was correct in 25 (96%) cases, and was consolidated in 23 (88%). We had two cases of graft fracture (7%) and postoperative migration (7%).

Conclusion

Surgical treatment using arthroscopic Latarjet with endobuttons is safe and effective, producing good functional outcomes in patients. Level of Evidence IV, Case Series.

Effects of Bone Incorporation After Arthroscopic Stabilization Surgery for Bony Bankart Lesion Based on Preoperative Glenoid Defect Size

BACKGROUND

Recurrent shoulder instability occurs more frequently after soft tissue surgery when the glenoid defect is greater than 20%. However, for lesions less than 20%, no scientific guidance is available regarding what size of bone fragments may affect shoulder functional restoration after bone incorporation. Purpose/Hypothesis: The purpose was to analyze how preoperative glenoid defect size and bone fragment incorporation alter postoperative clinical outcomes, we compared the functional outcomes of shoulders with and without bony Bankart lesion. It was hypothesized that differences in postoperative clinical outcomes between patients with and without bony fragments would be found only in patients with a larger glenoid defect.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 223 patients who underwent arthroscopic stabilization surgery for recurrent anterior shoulder instability were divided into two groups based on the presence of anterior glenoid bone fragments. In each group, postoperative shoulder functional outcomes, sports activity level, and recurrence rates were evaluated according to preoperative glenoid defect size (small, <10%; medium, 10%-15% and 15%-20%; large, >20%).

RESULTS

In patients with small or medium defects, no significant differences were found in postoperative clinical outcomes and sports activity levels between the two groups. However, in patients with a large defect, the patients with bone fragments (mean ± SD American Shoulder and Elbow Surgeons [ASES] score, 92.3 ± 2.7; Rowe score, 90.9 ± 5.4) showed significantly superior clinical outcomes compared with patients who did not have fragments (ASES score, 87.3 ± 6.2, P = .02; Rowe score, 84.8 ± 7.3, P = .04). Among patients without bone fragments, recurrence increased significantly with increasing preoperative glenoid defect size (recurrence rates: 0% in small defects, 7.4% in medium defects, 22.2% in large defects), whereas patients with bone fragments showed no tendency for increasing or decreasing recurrence rates (0% in small defects, 7.9% in medium defects, 5.9% in large defects).

CONCLUSION

In the treatment of bony Bankart lesion, the effect of bone fragment incorporation was different according to preoperative glenoid defect size. In patients with preoperative glenoid defects less than 20% of the glenoid width, bone fragment incorporation after arthroscopic bony Bankart repair did not alter clinical outcomes, sports activity levels, or recurrence rates, whereas in patients with defects greater than 20% of the glenoid width, bone fragment incorporation improved clinical outcomes and recurrence rates.

Does the Arthroscopic Latarjet Procedure Effectively Correct "Off-Track" Hill-Sachs Lesions?

BACKGROUND

The glenoid track concept describes the dynamic interaction of bipolar bone loss in anterior glenohumeral instability. Initial studies have successfully demonstrated this concept's application in clinical populations. In clinical practice, the Latarjet procedure is commonly the preferred treatment in addressing "off-track" Hill-Sachs lesions. The effectiveness of this procedure in restoring such lesions to an "on-track" state, however, has not yet been evaluated or described in the literature.

HYPOTHESIS

The Latarjet procedure would transform "off-track" Hill-Sachs lesions to "on-track" lesions. Lesions would remain "on-track" during follow-up, despite glenoid remodeling.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients with "off-track" Hill-Sachs lesions treated with the arthroscopic Latarjet procedure between March 2013 and May 2014 were included. Glenoid track and coracoid graft contact surface area measurements using 3-dimensional computed tomography (3D-CT) were performed preoperatively and at 6-week, 6-month, and at least 12-month (final) follow-up. The mean final follow-up was 23 months. The glenoid diameter, as a percentage of the native glenoid, was also calculated from this imaging.

RESULTS

Twenty-six patients met the inclusion criteria. 3D-CT scans were available for all patients preoperatively and postoperatively, with 21 patients (81%) undergoing 6-month follow-up CT and 19 patients (73%) undergoing final follow-up CT. Hill-Sachs lesions remained "on-track" at all follow-up time points. The mean glenoid diameter changed significantly from 84.6% preoperatively to 122.8% at 6 weeks ( P < .001) and from 120.5% at 6 months to 113.9% at final follow-up ( P = .005). This was also reflected in significant remodeling seen in the coracoid graft articular contact area (6 weeks to 6 months, P = .024; 6 months to final follow-up, P = .002). This persisting glenoid arc enlargement at final follow-up avoided "off-track" Hill-Sachs lesions in 6 of 19 patients (32%), which would otherwise have occurred had the coracoid graft remodeled to native glenoid dimensions.

CONCLUSION

The Latarjet procedure provides an effective treatment for "off-track" engaging Hill-Sachs lesions, despite an evident glenoid remodeling process. At a mean of 23 months postoperatively, a mean persisting enlargement of the glenoid arc of 14% beyond native dimensions remained, avoiding a recurrent "off-track" lesion in 32% of patients, which would otherwise have occurred with complete remodeling.

The glenoid track: a review of the clinical relevance, method of calculation and current evidence behind this method

In the setting of bipolar bone injury, orthopedic surgeons are currently making use of the glenoid track method to guide surgical management. Using preoperative CT or MR imaging, this method allows the identification of patients who are more likely to fail a primary capsuloligamentous Bankart repair. As the glenoid track method becomes increasingly used in preoperative planning, it is important for the radiologist to become familiar with its concept and method of calculation. This review article aims to concisely summarize the current literature and the clinical implications of the glenoid track method.

Traumatic anterior instability of the shoulder

The shoulder is the most unstable joint in the human body. Traumatic anterior instability of the shoulder is a common condition, which, especially in young patients, is associated with high recurrence rates. The effectiveness of non-surgical treatments when compared to surgical ones is still controversial. The purpose of this study was to review the literature for current concepts and updates regarding the treatment of this condition.

Biomechanical Evaluation of Glenoid Reconstruction With an Implant-Free J-Bone Graft for Anterior Glenoid Bone Loss

BACKGROUND

The anatomic restoration of glenoid morphology with an implant-free J-shaped iliac crest bone graft offers an alternative to currently widely used glenoid reconstruction techniques. No biomechanical data on the J-bone grafting technique are currently available.

PURPOSE

To evaluate (1) glenohumeral contact patterns, (2) graft fixation under cyclic loading, and (3) the initial stabilizing effect of anatomic glenoid reconstruction with the implant-free J-bone grafting technique.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight fresh-frozen cadaveric shoulders and J-shaped iliac crest bone grafts were used for this study. J-bone grafts were harvested, prepared, and implanted according to a previously described, clinically used technique. Glenohumeral contact patterns were measured using dynamic pressure-sensitive sensors under a compressive load of 440 N with the humerus in (a) 30° of abduction, (b) 30° of abduction and 60° of external rotation, (c) 60° of abduction, and (d) 60° of abduction and 60° of external rotation. Using a custom shoulder-testing system allowing positioning with 6 degrees of freedom, a compressive load of 50 N was applied, and the peak force needed to translate the humeral head 10 mm anteriorly at a rate of 2.0 mm/s was recorded. All tests were performed (1) for the intact glenoid, (2) after the creation of a 30% anterior osseous glenoid defect parallel to the longitudinal axis of the glenoid, and (3) after anatomic glenoid reconstruction with an implant-free J-bone graft. Furthermore, after glenoid reconstruction, each specimen was translated anteriorly for 5 mm at a rate of 4.0 mm/s for a total of 3000 cycles while logging graft protrusion and mediolateral bending motions. Graft micromovements were recorded using 2 high-resolution, linear differential variable reluctance transducer strain gauges placed in line with the long leg of the graft and the mediolateral direction, respectively.

RESULTS

The creation of a 30% glenoid defect significantly decreased glenohumeral contact areas ( P < .05) but significantly increased contact pressures at all abduction and rotation positions ( P < .05). Glenoid reconstruction restored the contact area and contact pressure back to levels of the native glenohumeral joint in all tested positions. The mean (±SD) force to translate the humeral head anteriorly for 10 mm (60° of abduction: 31.7 ± 12.6 N; 60° of abduction and 60° of external rotation: 28.6 ± 7.6 N) was significantly reduced after the creation of a 30% anterior bone glenoid defect (60° of abduction: 12.2 ± 6.8 N; 60° of abduction and 60° of external rotation: 11.4 ± 5.4 N; P < .001). After glenoid reconstruction with a J-bone graft, the mean peak translational force significantly increased (60° of abduction: 85.0 ± 8.2 N; 60° of abduction and 60° of external rotation: 73.6 ± 4.5 N; P < .001) compared with the defect state and baseline. The mean total graft protrusion under cyclical translation of the humeral head over 3000 cycles was 138.3 ± 169.8 µm, whereas the mean maximal mediolateral graft deflection was 320.1 ± 475.7 µm.

CONCLUSION

Implant-free anatomic glenoid reconstruction with the J-bone grafting technique restored near-native glenohumeral contact areas and pressures, provided secure initial graft fixation, and demonstrated excellent osseous glenohumeral stability at time zero.

CLINICAL RELEVANCE

The implant-free J-bone graft is a viable alternative to commonly used glenoid reconstruction techniques, providing excellent graft fixation and glenohumeral stability immediately postoperatively. The normalization of glenohumeral contact patterns after reconstruction could potentially avoid the progression of dislocation arthropathy.

Radiographic Evaluation of Patients with Anterior Shoulder Instability

PURPOSE OF REVIEW

Injuries to the labrum, joint capsule (in particular the inferior glenohumeral ligament), cartilage, and glenoid periosteum are associated with anterior shoulder instability. The goal of this review is to provide common radiographic images and findings in patients with anterior shoulder instability. Furthermore, we will demonstrate the best methods for measuring anterior glenoid bone loss.

RECENT FINDINGS

Magnetic resonance (MR) imaging is highly relied upon for evaluating anterior shoulder instability and can diagnose soft tissue injuries with high sensitivity. While 3D computed tomography (CT) scan has been considered the optimal tool for evaluating osseous defects, certain MR imaging sequences have been shown to have similar diagnostic accuracy. Repair of Bankart lesions is critical to stabilizing the shoulder, and in the recent years, there has been an increasing focus on imaging to accurately characterize and measure glenoid bone loss to properly indicate patients for either arthroscopic repair or anterior bony reconstruction. Furthermore, Hill-Sachs lesions are commonly seen with shoulder instability, and importance must be placed on measuring the size and depth of these lesions along with possible engagement, as these factors will dictate management. The labral-ligamentous complex and rotator cuff are primary stabilizers of the shoulder. With anterior shoulder instability, the labrum is frequently injured. MRI with an arthrogram or provocative maneuvers is the gold standard for diagnosis. Various imaging modalities and methods can be performed to identify and measure Bankart and Hill-Sachs lesions, which can then be used for surgical planning and treating shoulder instability.

Critical Value of Anterior Glenoid Bone Loss That Leads to Recurrent Glenohumeral Instability After Arthroscopic Bankart Repair

BACKGROUND

Generally, a glenoid bone loss greater than 20% to 25% is considered critical for poor surgical outcomes after a soft tissue repair. However, recent studies have suggested that the critical value should be lower.

PURPOSE

To determine the critical value of anterior glenoid bone loss that led to surgical failure in patients with anterior shoulder instability.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The study included 169 patients with anterior glenoid erosion. The percentage of glenoid erosion was calculated as the ratio of the glenoid loss width and the glenoid width to the diameter of the outer-fitting circle based on the inferior portion of the glenoid contour. The critical value of the glenoid bone loss was analyzed by means of receiver operating characteristic (ROC) curve analysis. Patients were divided into 2 groups based on the amount of glenoid bone loss: group A (less than the critical value) and group B (more than the critical value). Patients evaluated their shoulder function as a percentage of their preinjury level using the Single Assessment Numeric Evaluation (SANE) score, and postoperative clinical outcomes were assessed with the American Shoulder and Elbow Surgeons (ASES) score and Rowe score. Surgical failure was defined as the need for revision surgery or the presence of subjective symptoms of instability.

RESULTS

The optimal critical value of glenoid bone loss was 17.3% (area under the curve = 0.82; 95% confidence interval, 0.73-0.91; P < .001; sensitivity 75%; specificity 86.6%). Group A and B contained 134 and 35 patients, respectively. Shoulder functional scores were significantly lower in group B than in group A ( P < .001). Five patients (3.7%) in group A and 15 (42.9%) in group B had surgical failure ( P < .001). The SANE score was significantly lower in group B (83.8 ± 12.1) than in group A (92.9 ± 4.7, P = .001).

CONCLUSION

An anterior glenoid bone loss of 17.3% or more with respect to the longest anteroposterior glenoid width should be considered as the critical amount of bone loss that may result in recurrent glenohumeral instability after arthroscopic Bankart repair.

Editorial Commentary: Distal Tibia Allograft as an Option for Glenoid Reconstruction in Recurrent Shoulder Instability-It's All About the Bone?

Bony defects in recurrent shoulder instability can lead to the failure of soft tissue reconstruction. Many techniques have been developed to address glenoid defects in an attempt to prevent recurrent instability. However, the high complication rates with the Latarjet procedure have led surgeons to identify other sources of bone graft, including the distal tibia allograft (DTA). The DTA appears to be a suitable option for anterior glenoid reconstruction, highlighting the importance of reconstructing all bony defects and the versatility and efficacy of allograft bone blocks.

3D-MR vs. 3D-CT of the shoulder in patients with glenohumeral instability

OBJECTIVE

To determine whether 3D-MR osseous reformats of the shoulder are equivalent to 3D-CT osseous reformats in patients with glenohumeral instability.

MATERIALS AND METHODS

Patients with glenohumeral instability, who were to be imaged with both CT and MRI, were prospectively selected. CT and MR were performed within 24 h of one another on 12 shoulders. Each MR study included an axial 3D isotropic VIBE sequence. The image data from the isotropic VIBE sequence were post-processed using subtraction and 3D software. CT data were post-processed using 3D software. The following measurements were obtained for both 3D-CT and 3D-MR post-processed images: height and width of the humeral head and glenoid, Hill-Sachs size and percent humeral head loss (if present), size of glenoid bone loss and percent glenoid bone loss (if present). Paired t-tests and two one-sided tests for equivalence were used to assess the differences between imaging modalities and equivalence.

RESULTS

The measurement differences from the 3D-CT and 3D-MR post-processed images were not statistically significant. The measurement differences for humeral height, glenoid height and glenoid width were borderline statistically significant; however, using any adjustment for multiple comparisons, this failed to be significant. Using an equivalence margin of 1 mm for measurements and 1.5% for percent bone loss, the 3D-MR and 3D-CT post-processed images were equivalent.

CONCLUSION

Three-dimensional-MR osseous models of the shoulder using a 3D isotropic VIBE sequence were equivalent to 3D-CT osseous models, and the differences between modalities were not statistically significant.

Classification and Analysis of Attritional Glenoid Bone Loss in Recurrent Anterior Shoulder Instability

BACKGROUND

Recognition and proper treatment of glenoid bone loss (GBL) are important for successful management of anterior shoulder instability. Although GBL has been described as the amount of bony loss from the front of the glenoid, there is also a fragment of bone that is usually displaced and often undergoes attrition. Thus, due to attritional bone loss (ABL) of the fragment, insufficient bone is left to fully reconstruct the glenoid.

PURPOSE

To (1) evaluate ABL of the glenoid fragment in recurrent anterior shoulder instability and (2) correlate ABL with clinical history, fragment size, and radiographic findings.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

GBL was evaluated on 3-dimensional computed tomography (3D CT) en-face view and was measured as percentage loss. The bone fragment size was measured, and attrition of the fragment was determined by evaluation of the amount remaining relative to the initial defect; patients were stratified into minimal (<34%), moderate (34% to <67%), and severe (≥67%) attritional loss groups. Clinical history and demographics were correlated to ABL, and GBL and ABL were compared.

RESULTS

The overall median percentage GBL was 15.3% (interquartile range [IQR], 9.9%-20.0%), with a mean (±SD) percentage GBL of 16.5% ± 9.0%. Study participants had a corresponding median percentage ABL of 75.8% (IQR, 53.8%-95.7%) and a mean percentage ABL of 72.0% ± 24.4%. A total of 61.2% of patients (n = 85) exhibited severe ABL, while 30.2% had moderate ABL and 8.6% had minimal ABL. The total time of instability was significantly associated with percentage of attritional bone loss ( P < .05). In addition, the time of instability was greatest in patients in the third tertile of ABL (≥87.5%; P = .08). A significant difference was found in total time of instability among patients in the highest tertile of ABL (38.6 months) versus both the middle (26.7 months) and lowest (32.8 months) tertiles ( P < .05).

CONCLUSION

The study results indicate that in the majority of patients with recurrent anterior instability, GBL presents with extensive attrition of the bone fragment independent of initial glenoid bone loss; therefore, surgeons should be cognizant that the remaining bone fragment is unable to reconstitute glenoid bone stock. In addition, the results showed more attritional bone loss in patients with a longer duration of instability symptoms, indicating a role for incorporating symptom duration in determining proper management.

The Glenoid Labrum

The glenoid labrum is a critical structure within the gleno-humeral joint and commonly requires treatment by the shoulder surgeon. This review presents a concise summary of the embryology, anatomy, microscopy, biomechanical properties and clinical lesions involving the glenoid labrum. This knowledge will aid the clinician in understanding its function and pathology.

Clinical Validation of the Glenoid Track Concept in Anterior Glenohumeral Instability

BACKGROUND

Glenoid and humeral bone loss are well-described risk factors for failure of arthroscopic shoulder stabilization. Recently, consideration of the interactions of these types of bone loss (bipolar bone loss) has been used to determine if a lesion is "on-track" or "off-track." The purpose of this study was to study the relationship of the glenoid track to the outcomes of arthroscopic Bankart reconstructions.

METHODS

Over a 2-year period, 57 shoulders that were treated with an isolated, primary arthroscopic Bankart reconstruction performed at a single facility were included in this study. The mean patient age was 25.5 years (range, 20 to 42 years) at the time of the surgical procedure, and the mean follow-up was 48.3 months (range, 23 to 58 months). Preoperative magnetic resonance imaging was used to determine glenoid bone loss and Hill-Sachs lesion size and location and to measure the glenoid track to classify the shoulders as on-track or off-track. Outcomes were assessed according to shoulder stability on examination and subjective outcome.

RESULTS

There were 10 recurrences (18%). Of the 49 on-track patients, 4 (8%) had treatment that failed compared with 6 (75%) of 8 off-track patients (p = 0.0001). Six (60%) of 10 patients with recurrence of instability were off-track compared with 2 (4%) of 47 patients in the stable group (p = 0.0001). The positive predictive value of an off-track measurement was 75% compared with 44% for the predictive value of glenoid bone loss of >20%.

CONCLUSIONS

The application of the glenoid track concept to our cohort was superior to using glenoid bone loss alone with regard to predicting postoperative stability. This method of assessment is encouraged as a routine part of the preoperative evaluation of all patients under consideration for arthroscopic anterior stabilization.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Osteochondral Allografts in Shoulder Surgical Procedures

The use of fresh osteochondral allografts has become popular in many joint-preserving orthopaedic procedures and shows early promising results within the shoulder. Distal tibial allograft contains a stout cartilaginous layer that appears to have highly congruent curvature and concavity to the glenoid, which makes for an optimal allograft option for instability. In the setting of large Hill-Sachs lesions, the use of a humeral-head osteochondral allograft is essential to restore geometry, stability, and mechanics of the native glenohumeral joint. One must be cautious with the treatment of glenoid chondral lesions with osteoarticular grafting procedures because of the depth of the glenoid compared with the depth of subchondral bone on the graft necessary to achieve a press fit, and advanced imaging is recommended when planning an operative intervention. Optimizing joint-preservation treatment with osteochondral allografts will rely on the long-term results of these procedures, and careful patient selection, preoperative discussion, and realistic expectations are necessary.

What Is the Critical Value of Glenoid Bone Loss at Which Soft Tissue Bankart Repair Does Not Restore Glenohumeral Translation, Restricts Range of Motion, and Leads to Abnormal Humeral Head Position?

BACKGROUND

A general consensus has been formed that glenoid bone loss greater than 20% to 25% is the critical amount at which bony augmentation procedures are needed; however, recent clinical results suggest that the critical levels must be reconsidered to lower values.

PURPOSE

This study aimed to find the critical value of anterior glenoid bone loss when a soft tissue repair is not adequate to restore anterior-inferior glenohumeral translation, rotational range of motion, or humeral head position using a biomechanical anterior shoulder instability model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight cadaveric shoulders were tested with a customized shoulder testing system. Range of motion, translation, and humeral head position were measured at 60° of glenohumeral abduction in the scapular plane under a total of 40-N rotator cuff muscle loading in the following 11 conditions: intact; soft tissue Bankart lesion and repair; Bankart lesion with 10%, 15%, 20%, and 25% glenoid bone defects based on the largest anteroposterior width of the glenoid; and soft tissue Bankart repair for each respective glenoid defect. Serial osteotomies for each percentage of bone loss were made parallel to the long axis of the glenoid.

RESULTS

There was significantly decreased external rotation (121.2° ± 2.8° to 113.5° ± 3.3°; P = .004), increased anteroinferior translation with an externally applied load (3.0 ± 1.2 mm to 7.5 ± 1.1 mm at 20 N; P = .008), and increased posterior (0.2 ± 0.6 mm to 2.7 ± 0.8 mm; P = .049) and inferior shift (2.9 ± 0.7 mm to 6.6 ± 1.1 mm; P = .018) of the humeral head apex in the position of maximum external rotation after soft tissue Bankart repair of a 15% glenoid defect compared with the repair of a Bankart lesion without a glenoid defect, respectively.

CONCLUSION

Glenoid defects of 15% or more of the largest anteroposterior glenoid width should be considered the critical bone loss amount at which soft tissue repair cannot restore glenohumeral translation, restricts rotational range of motion, and leads to abnormal humeral head position.

CLINICAL RELEVANCE

The critical level of anterior glenoid bone loss at which bony restorations should be considered is closer to 15% of the largest anteroposterior width of glenoid for defects perpendicular to the superoinferior glenoid axis, which is lower than the commonly accepted threshold of 20% to 25%.

Autologous distal clavicle versus autologous coracoid bone grafts for restoration of anterior-inferior glenoid bone loss: a biomechanical comparison

BACKGROUND

Treating anterior glenoid bone loss in patients with recurrent shoulder instability is challenging. Coracoid transfer techniques are associated with neurologic complications and neuroanatomic alterations. The purpose of our study was to compare the contact area and pressures of a distal clavicle autograft with a coracoid bone graft for the restoration of anterior glenoid bone loss. We hypothesized that a distal clavicle autograft would be as effective as a coracoid graft.

METHODS

In 13 fresh-frozen cadaveric shoulder specimens, we harvested the distal 1.0 cm of each clavicle and the coracoid bone resection required for a Latarjet procedure. A compressive load of 440 N was applied across the glenohumeral joint at 30° and 60° of abduction, as well as 60° of abduction with 90° of external rotation. Pressure-sensitive film was used to determine normal glenohumeral contact area and pressures. In each specimen, we created a vertical, 25% anterior bone defect, reconstructed with distal clavicle (articular surface and undersurface) and coracoid bone grafts, and determined the glenohumeral contact area and pressures. We used analysis of variance for group comparisons and a Tukey post hoc test for individual comparisons (with P <.05 indicating a significant difference).

RESULTS

The articular distal clavicle bone graft provided the lowest mean pressure in all testing positions. The coracoid bone graft provided the greatest contact area in all humeral positions, but the difference was not significant.

CONCLUSION

An articular distal clavicle bone graft is comparable in glenohumeral contact area and pressures to an optimally placed coracoid bone graft for restoring glenoid bone loss.

LEVEL OF EVIDENCE

Basic Science Study; Biomechanics.

The effect of defect orientation and size on glenohumeral instability: a biomechanical analysis

PURPOSE

The purpose of this study was to determine the relationship between bony stability and percentage of anterior glenoid bone loss and the effect of bone loss orientation.

METHODS

Twelve cadaveric shoulders were studied. Glenoid bone defects were simulated in two different osteotomy angles: 0° and 45° to the superoinferior (SI) axis of the glenoid. The force and displacement required for dislocation were measured under two compressive forces of 40 and 60N. Testing was performed for the intact glenoid and glenoid defects of 2, 4, 6, 8, and 10 mm from the anterior margin.

RESULTS

The maximum force for dislocation with the 2-mm glenoid defect was significantly decreased compared with intact glenoid (p = 0.01), and this force also significantly decreased with each increase in defect size (p < 0.05). The dislocation force for 45° osteotomy was significantly higher than that for 0° osteotomy for all defect widths up to 8 mm with 40N compression and 6 mm with 60N compression (p < 0.001). The displacement at dislocation did not significantly decrease until the 8-mm defect with the 45° osteotomy but significantly decreased with the 4-mm defect with the 0° osteotomy. The required force for dislocation with 60N compression was significantly higher than that with 40N compression for all osteotomy sizes and orientations.

CONCLUSIONS

The decrease in stability even with glenoid bone loss as small as 2 mm or 7.5 % of the glenoid width suggests that bony restoration is recommended whenever any bone loss exists. Bone defects parallel to SI axis may be more susceptible to recurrent instability, and shoulder muscle strengthening exercises may increase glenohumeral compressive force and thus improve glenohumeral stability. Bony restoration is recommended whenever bone loss exists even with small bone fragments particularly those in line with the superior-inferior axis of the glenoid.

Moberg Osteotomy Shifts Contact Pressure Plantarly in the First Metatarsophalangeal Joint in a Biomechanical Model

BACKGROUND

A proximal phalangeal dorsiflexion osteotomy (Moberg osteotomy) is commonly used to treat hallux rigidus, but the mechanical explanation for its effectiveness is unclear. The purpose of our study was to test the effect of a Moberg osteotomy on first metatarsophalangeal joint contact mechanics.

METHODS

Ten cadaveric first ray specimens were dissected, with the medial band of the plantar aponeurosis preserved at its origin, and placed in a custom testing apparatus. Forefoot loads during mid-stance with the first metatarsal positioned at 10 degrees were simulated using a custom-made loading jig while contact mechanics were acquired with a thin pressure-sensitive sensor. A Moberg osteotomy was performed starting 9 mm distal to the proximal phalanx with excision of a 3-mm wedge of bone and fixated with a 2-mm Kirschner wire. The effect of the Moberg osteotomy was tested by reapplying the forefoot loads and acquiring the joint pressures. The center of pressure, peak pressure, and contact area were calculated. Paired t tests were performed to determine if the Moberg osteotomy affected joint contact mechanics.

RESULTS

The Moberg osteotomy shifted the center of contact pressure on the proximal phalanx surface more plantarly (P < .01). However, the Moberg osteotomy did not affect the peak pressure (P = .62) or the joint contact area (P = .96).

CONCLUSIONS

There were no differences in peak pressure or first MTPJ contact area, but a plantar shift in the center of pressure occurred after the Moberg osteotomy.

CLINICAL RELEVANCE

The plantar cartilage, which is often spared from arthritic changes, may be preferentially loaded and the potential edge loading following cheilectomy may be avoided with the Moberg osteotomy secondary to the plantar shift of center of pressure.

Glenohumeral kinematics after soft tissue interposition graft and glenoid reaming: A cadaveric study

BACKGROUND

The management of young patients with glenohumeral arthritis is controversial. Resurfacing of the glenoid with biologic interposition and reaming of the glenoid have been suggested as potential treatment options. The goal of this study was to determine the change in glenohumeral contact pressures in interposition arthroplasty, as well as glenoid reaming in an arthritis model. We hypothesized that interposition with meniscal allograft will lead to the best normalization of contact pressure throughout the glenohumeral range of motion.

MATERIALS AND METHODS

Eight fresh-frozen cadaveric shoulders were tested in static positions of humeral abduction with a compressive load. Glenohumeral contact area, contact pressure, and peak force were determined sequentially for (1) intact glenoid (2) glenoid with cartilage removed (arthritis model) (3) placement of lateral meniscus allograft (4) placement of Achilles allograft (5) arthritis model with reamed glenoid.

RESULTS

The arthritis model demonstrated statistically higher peak pressures than intact glenoid and glenoid with interpositional allograft. Meniscal and Achilles allograft lowered mean contact pressure and increased contact area to a level equal to or more favorable than the control state. In contrast, the reamed glenoid did not show any statistical difference from the arthritis model for any of the recorded measures.

CONCLUSION

Glenohumeral contact pressure is significantly improved with interposition of allograft at time zero compared to an arthritic state. Our findings suggest that concentric reaming did not differ from the arthritic model when compared to normal. These findings favor the use of allograft for interposition as a potential treatment option in patients with glenoid wear.

Arthroscopic Suture Anchor Fixation of Bony Bankart Lesions: Clinical Outcome, Magnetic Resonance Imaging Results, and Return to Sports

PURPOSE

The purpose of this study was to evaluate the outcome, return to sporting activity, and postoperative articular cartilage and bony morphology of shoulders that underwent arthroscopic suture anchor repair of bony Bankart lesions.

METHODS

The inclusion criteria for this retrospective study were anterior glenoid rim fractures after traumatic shoulder instability that were treated with arthroscopic suture anchor repair. Patients were surveyed by a questionnaire including sport-specific outcome, Rowe score, Western Ontario Shoulder Instability Index, and Oxford Instability Score. Three-tesla magnetic resonance imaging could be performed in 30 patients to assess osseous integration, glenoid reconstruction, and signs of osteoarthritis.

RESULTS

From November 1999 to April 2010, 81 patients underwent an anterior bony Bankart repair in our department (50 arthroscopic suture anchor repairs, 5 arthroscopic screw fixations, and 26 open repairs). The 55 arthroscopic repairs comprised a consecutive cohort of patients treated by a single surgeon. Of the 50 patients in the suture anchor group, 45 (90%) were available for evaluation. At 82 ± 31 months postoperatively, the mean Rowe score was 85.9 ± 20.5 points, the mean Western Ontario Shoulder Instability Index score was 89.4% ± 14.7%, and the mean Oxford Instability Score was 13.6 ± 5.4 points. Compared with the contralateral shoulder, all scores showed a significantly reduced outcome (P < .001, P < .001, and P < .001, respectively). A redislocation occurred in 3 patients (6.6%). Regarding satisfaction, 35 patients (78%) were very satisfied, 9 (20%) were satisfied, and 1 was partly satisfied. Overall, 95% of patients returned to any sporting activity after surgery. The number of sports disciplines (P < .001), duration (P = .005), level (P = .02), and risk category (P = .013) showed a significant reduction compared with the pretrauma condition. However, only 19% of patients reported that shoulder complaints were the reason for the reduction in activity. Nonunion occurred in 16.6%, with a higher frequency in patients with chronic lesions (P = .031). Anatomic reduction was achieved in 72%, the medial step-off in patients with nonanatomic reduction averaged 1.8 ± 0.9 mm, and the remaining glenoid defect size averaged 6.8% ± 7.3%. Full-thickness cartilage defects of the anterior glenoid were detected in 70% of patients.

CONCLUSIONS

Arthroscopic suture anchor repair may enable an anatomic reduction of bony Bankart lesions with no or only minimal articular steps and provides successful midterm outcomes concerning clinical scores, recurrence, and patient satisfaction. The return to activity is limited for various, mostly non-shoulder-related causes. Chronic lesions may have an inferior healing potential; therefore early surgical stabilization of acute Bankart fragments is suggested to avoid possible nonunion.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Effect of bone loss in anterior shoulder instability

Anterior shoulder instability with bone loss can be a difficult problem to treat. It usually involves a component of either glenoid deficiency or a Hill-Sachs lesion. Recent data shows that soft tissue procedures alone are typically not adequate to provide stability to the shoulder. As such, numerous surgical procedures have been described to directly address these bony deficits. For glenoid defects, coracoid transfer and iliac crest bone block procedures are popular and effective. For humeral head defects, both remplissage and osteochondral allografts have decreased the rates of recurrent instability. Our review provides an overview of current literature addressing these treatment options and others for addressing bone loss complicating anterior glenohumeral instability.

The ability of massive osteochondral allografts from the medial tibial plateau to reproduce normal joint contact pressures after glenoid resurfacing: the effect of computed tomography matching

BACKGROUND

Current techniques for resurfacing of the glenoid in the treatment of arthritis are unpredictable. Computed tomography (CT) studies have demonstrated that the medial tibial plateau has close similarity to the glenoid. The purpose of this study was to assess contact pressures of transplanted massive tibial osteochondral allografts to resurface the glenoid without and with CT matching.

METHODS

Ten unmatched cadaveric tibiae were used to resurface 10 cadaveric glenoids with osteochondral allografts. Five cadaveric tibiae and glenoids were CT matched and studied. An internal control group of 4 matched pairs of glenoids, with the contralateral glenoid transplanted to the opposite glenoid, was also included as a best-case scenario to measure the effects of the surgical technique. All glenoids were tested before and after grafting at different abduction and rotation angles, with recording of peak contact pressures.

RESULTS

Peak contact pressures were not different from the intact state in the autografted group but were increased in both allografted groups. CT-matched tibial grafts had lower peak pressures than unmatched grafts. Peak pressures were on average 24.8% (range [18.3%, 29.6%]) greater than in the native glenoids for unmatched allografts, 21.8% ([17.0%, 25.5%]) greater for the matched allografts, and 4.9% ([3.8%, 5.5%]) greater for matched autografts.

CONCLUSION

Osteochondral grafting from the medial tibial plateau to the glenoid is feasible but results in increased peak contact pressures. The technique is reproducible as defined by the autografted group. Contact pressures between native and allografted glenoids were significantly different. The clinical significance remains unknown. Peak pressures experienced by the glenoid seem highly sensitive to deviations from the native glenoid shape.