Background:Repair techniques for complete subscapularis (SSC) tendon tears have not been evaluated and compared in detail. The purpose of this study was to evaluate the biomechanical performance of different repair techniques for complete SSC tendon tears. Purpose:To evaluate the biomechanical performance of different repair techniques for complete SSC tendon tears. Methods:In a total of eighteen fresh-frozen shoulders with an intact rotator cuff, complete SSC tendon tears were created. Six shoulders matched by age and gender were allocated to each of the three repair technique groups: (1) knotted mattress single-row repair (group SR), (2) knotted mattress double-row repair (group DR), and (3) knotless tape single-row repair (group SRT). The quality of reconstruction was evaluated by measuring the SSC tendon footprint coverage (% of pre-operative footprint), repair stiffness (N/mm), cyclic displacement (mm), and the ultimate load to failure (N). Results:DR repair showed a significantly higher relative repair area compared to SR repair techniques (DR = 73.6% vs. SR = 45.6%, P = .009 vs. SRT = 49.4%, P = .006). Stiffness and cyclic displacement were comparable among all three groups (P = .292; P = .215). Ultimate failure load was greatest in the DR group at 305 N ±12 and showed a trend toward higher ultimate failure load compared to the SRT group (170 N ±42; P = .061). There was no significant difference between DR and SR groups (246 N ±71.4; P = .883). Conclusion:DR repair technique for complete SSC tendon tears achieves a significantly greater footprint coverage and the highest load to ultimate failure of the repair compared to SR repair techniques.

Background:Splitting the subscapularis in the Latarjet procedure is known to influence subscapularis muscle mechanics postoperatively; however, the influence of split level on postoperative muscle and joint function remains poorly understood. Purpose:To assess the effects of midlevel, lower-third, and upper-third subscapularis split levels in the Latarjet procedure on subscapularis lines of action and moment arms in the shoulder abduction, abduction and external rotation (ABER), and apprehension positions. Study Design:Controlled laboratory study. Methods:The Latarjet procedure was performed on 8 fresh-frozen human cadaveric upper extremities with a simulated 20% anteroinferior glenoid bone defect. A midwidth subscapularis muscle belly split was first performed on all specimens in which the conjoint tendon was routed. Lines of action and moment arms of 4 subregions of the subscapularis muscle (superior, mid-superior, mid-inferior, and inferior) were quantified radiographically with the conjoint tendon unloaded and loaded and the glenohumeral joint positioned in (1) 0° of abduction, (2) 90° of abduction, (3) 90° of abduction and full external rotation (ABER), and (4) the apprehension position, defined as ABER with 30° of horizontal extension. Testing was then repeated in random order after rerouting the conjoint tendon through both an upper- and then lower-third subscapularis split. Utmost care was taken to ensure that the subscapularis muscle integrity was not disrupted during the rerouting process. Results:Subscapularis splitting in Latarjet surgery deformed the muscle fibers below the split level, significantly increasing the inferior inclination of subscapularis muscle lines of action, but only for the midlevel and lower-third subscapularis split levels (P < .001). This increased inferior inclination was significantly greater in the ABER and apprehension positions compared with those at 0° and 90° of abduction (P < .05). In the ABER and apprehension positions, the adduction moment arms of the mid-superior subscapularis muscle subregion were also significantly larger for the midlevel split compared with the lower-third and upper-third split (P < .05), indicating greater depressor capacity. Conclusion:Latarjet surgery deforms subscapularis muscle fibers below the level of the split, changing subscapularis leverage and line of force. The midlevel subscapularis muscle split in the Latarjet procedure confers greater mechanical advantage in terms of shoulder depressor function and stabilizing potential than that associated with an upper-third or lower-third split, particularly in the ABER and apprehension positions. Clinical Relevance:Subscapularis muscle leverage and force potential are significantly influenced by split location in Latarjet surgery. A midlevel subscapularis split is likely to provide the greatest mechanical stability, particularly in positions of shoulder instability.

BACKGROUND:Recurrent instability continues to be a common complication following reverse total shoulder arthroplasty (rTSA); however, the influence of implant size and offset on joint compression and resistance to subluxation is poorly understood. The purpose of this study was to investigate the effect of glenosphere size, glenoid lateralization, and inferior offset on joint stability following rTSA using the Zimmer Trabecular Metal Reverse Plus shoulder system. METHODS:rTSA was performed on 8 fresh-frozen human cadaveric scapulae with the subscapularis tendon transected at its humeral insertion. Specimens were mounted onto a custom testing rig and physiological joint loading, which was computed using specimen-specific musculoskeletal models, was applied in 45° of scapular plane abduction with (1) neutral rotation and (2) 90° internal rotation. At each joint position, glenosphere lateralization (+0, +3, and +5 mm) was varied for each glenosphere size (36 and 40 mm). Eccentric (inferior offset) glenoid positioning was also investigated in each glenosphere size. For each configuration, the shear force required to dislocate the rTSA anteriorly was quantified. RESULTS:In the abducted and internally rotated shoulder, significantly more force was required to dislocate the shoulder anteriorly with the larger neutral-offset glenosphere compared to that in the smaller, neutral-offset glenosphere (mean difference: 6.2% body weight, P = .048). However, the use of a smaller, + 3 mm or +5 mm offset glenosphere resulted in equivalent anterior shoulder dislocation force to that in the larger, neutral-offset glenosphere (P > .05). In the abducted and internally rotated shoulder, lateralization of the larger glenosphere had no significant effect on shoulder dislocation force (P > .05). The inferior offset larger eccentric glenosphere produced only minor increases in stability when the arm was positioned in abduction and internal rotation (P > .05). CONCLUSION:In a position of rTSA instability (combined abduction and internal rotation), use of a larger glenosphere results in greater joint stability than that of a smaller glenosphere; however, lateralization of a smaller glenosphere increases joint stability to equivalent levels of that associated with the neutral-offset larger glenosphere. The isolated effect of increasing glenosphere eccentricity on shoulder stability following rTSA appears negligible in the position of instability.

BACKGROUND:In reverse total shoulder arthroplasty (rTSA), proximal humeral bone loss (PHBL) is associated with higher complication rates and inferior functional results, particularly loss of active external rotation (ER). Traditionally, adjunct tendon transfers such as the latissimus dorsi transfer or the modified l'Episcopo procedure have been employed to address this. Recently, in native shoulders, lower trapezius transfer (LTT) has gained popularity as an alternative method to restore ER. To date, almost no literature exists on its use in rTSA. The purpose of this study was to evaluate the biomechanical effectiveness of a novel, modified lower trapezius transfer with tendon-bone allograft (LTT+) that aims to reconstruct the greater tuberosity in situations of PHBL and to compare it with the modified l'Episcopo procedure. It was the hypothesis of this study that LTT+ would provide comparatively higher ER and lower adduction (ADD) moments. METHODS:Ten right, cadaveric upper limbs were prepared by resecting the proximal humerus, creating moderate PHBL (4 cm). rTSA was performed, and both an LTT+ and an l'Episcopo tendon transfer were added. The specimens were mounted on a custom-built testing apparatus, and an optical motion analysis system was employed to record joint kinematics and tendon excursions. During passive rotational and abduction-ADD motion cycles, the ER and ADD moment arms were computed using the tendon-excursion method. RESULTS:Both LTT+ and l'Episcopo are biomechanically effective in generating shoulder ER in rTSA with PHBL. LTT+ moment arms were higher; significance being reached after a minimum of 45° to 55° of ER had been achieved, depending on the angle of abduction. For pooled internal rotation (-20° to 0° rotation), low (0° to 45° rotation), and high ER (45° to 70° rotation), the mean differences of the ER moment arms were significant in all abduction positions (P < .0001 for all 3 groups). The ADD moment arms of LTT+ were significantly lower than l'Episcopo's (P < .0001), measured in neutral rotation in the scapular plant between 40° and 70° abduction. The differences were most relevant in lower degrees of abduction. CONCLUSION:Biomechanically, both LTT+ and the modified l'Episcopo procedure demonstrated effective shoulder ER capacity. LTT+ provided significantly higher ER moment arms in high degrees of ER, and, additionally, lower ADD moment arms, thereby potentially avoiding interference with the deltoid during abduction and elevation. These effects may strongly depend on the transfers' insertion site and technique.

BACKGROUND:The extent to which excessive glenoid retroversion leads to increased glenohumeral contact pressures and whether these increases can be mitigated surgically is unknown. PURPOSE:To evaluate the effect of excessive glenoid retroversion and posterior iliac crest bone grafting (ICBG) with or without glenoid osteotomy on glenohumeral contact patterns. STUDY DESIGN:Controlled laboratory study. METHODS:Six fresh-frozen shoulders had a posterior open-wedge glenoid osteotomy allowing glenoid retroversion to be set at 0°, 10°, and 20°. Four conditions were simulated consecutively on the same specimen at each retroversion angle: intact glenohumeral joint, posterior Bankart lesion, 20% posterior glenoid deficiency, and posterior ICBG (at 20° of retroversion; corrected to 10° and 0° of retroversion). The contact pattern for each specimen was evaluated in the jerk position (60° of glenohumeral anteflexion, 60° of internal rotation) by measuring mean and peak contact pressures (megapascals), peak contact pressure distance (millimeters), and mean contact area (square millimeters). RESULTS:In the intact condition, retroversion of 20° resulted in a significant decrease in contact area but did not significantly affect contact pressure. Creating a posterior Bankart lesion and/or posterior glenoid deficiency showed a significant increase in mean and peak contact pressure at all 3 retroversion angles (P < .05). Correcting glenoid retroversion to 0° in combination with ICBG resulted in comparable contact area and mean and peak contact pressure of the intact condition (P > .05). At 10° and 20° of glenoid retroversion, ICBG resulted in significantly higher peak and mean contact pressure (mean not significantly different at 10°) and significantly lower contact area as compared with the intact condition (P < .05). CONCLUSION:Glenohumeral contact patterns highly depend on the amount of glenoid retroversion and posterior labral and/or bony glenoid integrity. Only the combination of ICBG and glenoid osteotomy to correct glenoid retroversion to 0° resulted in glenohumeral contact patterns comparable to the native condition with 0° of retroversion. CLINICAL RELEVANCE:The combined effect of posterior glenoid bone grafting and correcting excessive glenoid retroversion (20°) may correct abnormal glenohumeral contact patterns.

BACKGROUND:The ligamentum teres is known to contribute to hip joint stability; however, the effect of surgical reconstruction of ligamentum teres tears on hip joint function is poorly understood. This study aimed to employ a cadaver model to quantify peak pressure, average pressure, contact force, and contact area between the femoral head and acetabulum in native, ligamentum teres deficient and reconstructed hips. METHODS:Nine fresh-frozen human cadaveric hips were dissected and mounted to a multi-axis Materials Test System. Digital pressure sensors were placed on anterior, posterior, and superior regions of the acetabulum. Joint loading was simulated in 20deg flexion, neutral position, and 10deg extension. Peak pressure, average pressure, contact force, and contact area were measured. FINDINGS:Ligamentum teres deficiency caused a significant increase in average pressure (mean difference: 161.6 kPa, p = 0.002) in the superior acetabulum of the neutral hip relative to the ligament intact hip and in peak pressure (mean difference: 1462.5 kPa, p = 0.023) in the anterior acetabulum of the extended hip compared to the intact hip. Ligamentum teres reconstruction subsequently restored average and peak pressure to levels not significantly different from those in the intact state (p > 0.05). Reconstruction also led to a significant decrease in average pressure (mean difference 241.0 kPa, p = 0.047) and contact force (mean difference: 124.5 N, p = 0.039) in the posterior acetabulum of the flexed hip relative to the intact hip. INTERPRETATION:Ligamentum teres reconstruction may help to prevent excessive contact that occurs in the ligamentum teres deficient hip and may mitigate or slow the onset of degenerative changes associated with ligamentum teres deficiency.

BACKGROUND:A high and flat acromion seems to be a risk factor for posterior shoulder instability. Biomechanically, the surgical correction of acromial malalignment can restore glenohumeral joint stability. PURPOSE/HYPOTHESIS:The purpose was to assess (1) the stabilizing effect of a posterior acromial bone graft (PABG) in moderate and severe acromial malalignment (high and flat) and (2) contact patterns under posterior humeral head displacement. It was hypothesized that a PABG would significantly (1) increase resistance to posterior humeral head displacement, (2) restore stability, and (3) increase acromiohumeral contact pressure. STUDY DESIGN:Controlled laboratory study. METHODS:A total of 8 fresh-frozen human cadaveric shoulders, with normal glenoid anatomy, were examined in a shoulder simulator in the load and shift and jerk test positions. Each specimen underwent 5 testing conditions using 3-dimensional printed cutting and reduction guides, with the joint left intact for each condition: (1) severe acromial malalignment, (2) severe acromial malalignment + PABG, (3) moderate acromial malalignment, (4) moderate acromial malalignment + PABG, and (5) corrected acromial alignment. The humeral head was translated posteriorly until reaching either a peak force of 150 N or a maximum posterior displacement of 50% of the glenoid width. Force, displacement, and acromiohumeral contact pressure were recorded. RESULTS:At 30° of flexion, the force needed to displace the humeral head 50% increased by 659% when a PABG was added to a moderately malaligned acromion and by 1249% when a PABG was added to a severely malaligned acromion. At 60° of flexion, it increased by 293% and 348%, respectively. This stabilizing effect increased progressively with increasing displacement (P < .05 for all comparisons after ≥5% of displacement). Compared with acromial correction, a PABG allowed comparable posterior displacement but required different amounts of force, depending on the scenario. At 30° of flexion after 30% of displacement, a PABG provided significantly greater stability (P < .05 for all comparisons). Mean contact pressure was significantly reduced on the rotator cuff and significantly increased on the acromial undersurface in moderate and severe acromial malalignment, whereas a PABG restored acromiohumeral contact pressure comparable with corrective osteotomy, particularly at 30° of flexion. CONCLUSION:The study provides quantitative evidence showing that a PABG significantly enhanced resistance to displacement and compensated for deficient posterolateral acromial coverage by extending the natural mechanical buttress. CLINICAL RELEVANCE:Experimentally, a PABG provided comparable or superior stability to that after surgical acromial reorientation while representing a technically simpler and potentially less invasive approach.

Background Failure rates in the management of recurrent posterior shoulder instability remain a concern. Cadaveric studies have established that posterior capsulolabral tears, glenoid retroversion, and posterior glenoid bone loss result in increased posterior humeral head translation in the setting of a posteriorly directed force. A high and flat acromion has recently been associated with posterior instability. Therefore, the purpose of this study was to evaluate a potential stabilizing effect of the acromion against posterior humeral head displacement. Methods Eight fresh-frozen human cadaveric shoulders were biomechanically tested in a shoulder simulator in the load-and-shift and Jerk test positions. Prior to testing, computed tomography scans were performed to measure native glenoid width, glenoid retroversion, posterior acromial coverage (PAC), sagittal acromial tilt (SAT), and posterior acromial height (PAH). Each specimen underwent 4 testing conditions using preplanned and 3D printed cutting and reduction guides: (1) Intact joint, native acromion; (2) Intact joint, severe acromial malalignment (SAT 69 degrees, PAC 47 degrees, PAH 26 mm); (3) Intact joint, moderate acromial malalignment (SAT 59 degrees, PAC 57 degrees, PAH 20 mm); (4) Intact joint, corrected acromial alignment (SAT 48 degrees, PAC 70 degrees, PAH 11 mm). The degree of acromial malalignment and acromial reorientation was chosen based on a previous study that defined acromial anatomy in patients with posterior instability. The humeral head was translated posteriorly until reaching either (1) a peak force of 150N or (2) a maximum posterior displacement of 50% of the glenoid width. Forces (N), displacement (mm), and acromiohumeral contact pressures (kPA) were simultaneously recorded. Results The force needed to displace the humeral head by 50% of the glenoid width decreased between 23% and 60% in moderate to severe acromial malalignment (high and flat acromion) and increased up to 122% following surgical correction of acromial alignment (low and steep acromion) when compared to the native condition. Correction of acromial alignment significantly increased stability compared to all other scenarios after >= 5% of displacement (P < .05 for all comparisons). Furthermore, it increased acromiohumeral contact pressures compared with severe malalignment in 30 degrees flexion and with moderate and severe acromial malalignment in 60 degrees flexion (P < .05 for all comparisons). Conclusion The acromion acts as a mechanical buttress to posterior humeral head displacement. Surgical correction of acromial malalignment cannot only effectively restore but increase glenohumeral joint stability. Future studies are needed to define the quantitative relevance of the different factors contributing to posterior shoulder instability and assist in defining the optimal amount of correction needed in an individual situation. Level of evidence Basic Science Study; Biomechanics (c) 2024 The Author(s). This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Background:There are concerns that the Latarjet procedure for subcritical glenoid bone loss results in significant graft resorption and increased complications. Purpose:To (1) analyze the long-term results of the primary open Latarjet procedure in patients with subcritical preoperative glenoid bone loss and (2) find whether graft resorption influences these results. Study Design:Case series, Level of evidence, 4. Methods:A total of 50 shoulders (n = 48 patients) underwent the primary open Latarjet procedure at a mean age of 27 years (range, 19-37 years) for recurrent anterior shoulder instability with subcritical glenoid bone loss (<15%). After a mean of 8.5 years (range, 6-13 years), signs of recurrent instability, shoulder function, and patient-reported outcome measures-including the West Ontario Shoulder Instability Index (WOSI); the American Shoulder and Elbow Surgeon (ASES) score; the subjective shoulder value (SSV)-were assessed. Computed tomography-morphometric analysis of graft resorption was conducted to define the pattern and volume of resorption, and its influence on clinical outcomes. Results:At the final follow-up, a significant increase in the SSV (65% to 84%; P < .001), with a relative WOSI score of 19% ± 17% and an ASES score of 91 ± 9, was observed. One shoulder (2%) sustained a recurrent traumatic shoulder dislocation after 6.75 years but did not require revision surgery. Five shoulders (10%) experienced a subluxation, and 6 shoulders (12%) had positive anterior apprehension. Significant (P < .001) graft resorption (mean, 24% of the total graft volume) was observed at the long-term follow-up, although no patient underwent revision surgery. Resorption was concentrated in the superior segment of the graft (75%; P < .001). Overall, graft resorption had no significant influence on any clinical outcome measure-including complications, pain, or signs of postoperative instability (P > .05). Conclusion:The primary open Latarjet procedure for subcritical glenoid bone loss (<15%) results in an excellent clinical outcome. Although significant graft resorption (ie, concentrated around the superior screw) can be expected at the long-term follow-up, it does not result in adverse clinical outcomes, with complication and recurrence rates comparable to results of the Latarjet procedure for larger glenoid bone loss.

Background:Sleep disturbance secondary to shoulder pathology is a common complaint. Previous studies have shown improvement in sleep quality after common shoulder procedures. The purpose of this study was to assess sleep quality response after arthroscopic rotator cuff repair (aRCR), anatomic total shoulder arthroplasty (aTSA), and reverse total shoulder arthroplasty (rTSA). Our hypothesis was that sleep disturbance is greater in degree and longer lasting in postoperative recovery after aRCR compared to shoulder arthroplasty. Methods:The Pittsburgh Sleep Quality Index and Visual Analog Scale-Quality of Sleep were prospectively collected in consecutive patients undergoing aRCR, aTSA, and rTSA between 2018 and 2020. Sleep quality and patient reported outcome measures, including the American Shoulder and Elbow Surgeons shoulder score, Single Assessment Numeric Evaluation (SANE) score, and visual analog scale pain score, were measured preoperatively and at 2 weeks, 6 weeks, 3 months, and 6 months postoperatively. Patient demographics, preoperative diagnosis, and comorbidities were recorded. Univariate and multivariate analyses were performed. Correlations between sleep quality metrics and patient reported outcome measures were assessed. Results:One hundred forty-one patients who underwent shoulder surgery participated in this study (aRCR: n = 34, aTSA: n = 58, rTSA: n = 49). With all shoulder surgeries pooled together, there were significant improvements in sleep quality as measured by Pittsburgh Sleep Quality Index and Visual Analog Scale-Quality of Sleep from preoperative to final follow-up (8.8 vs. 6.0, 55.4 vs. 75.2, P < .01 for both, respectively). The rate and magnitude of sleep quality improvement varied by surgical intervention. Sleep quality after aTSA and rTSA showed statistical improvement by 6 weeks postoperatively, which was durable through final follow-up. In contrast, after aRCR patients demonstrated a trend toward worsening sleep quality at 2 weeks with improvement by 3 months postoperatively. In multivariable regression analyses, only the type of surgical intervention, and not preoperative diagnosis or comorbidities, was associated with sleep quality at the final follow-up. Quality of sleep strongly correlated with the SANE score (r = 0.45, P < .01). Conclusion:Sleep quality improves after shoulder surgery, although the rate of recovery varies by surgical intervention. Sleep quality improves more rapidly after shoulder arthroplasty when compared to aRCR. The SANE score may be a useful surrogate metric in assessing sleep quality.

Background:Treatment of displaced distal clavicle fractures with bony avulsion of the coracoclavicular (CC) ligaments often warrants surgical fixation, yet a gold standard surgical technique is to be defined. The purpose of this study was to compare the biomechanical fixation strength of a new fixation technique, the CC stand-alone cow-hitch suture reconstruction, and to compare this technique with a clavicle hook plate and a lateral locking plate with CC suture reconstruction.Methods:Simulated Neer type V distal clavicle fractures of the clavicle were created in 18 cadaveric shoulders, which were matched by age and gender in 3 groups: (1) clavicle hook plate (group HP), (2) lateral locking plate fixation with CC suture reconstruction (group LPCC), and (3) CC stand-alone suture reconstruction using the cow-hitch technique (group CH). After preconditioning with 25 N for 10 cycles, the specimens were cycled in the coronal plane for 500 cycles from 10N to 70N. Displacement and ultimate load to failure were documented and analyzed with the data acquisition system.Results:There was a significant difference in the fracture displacement during cyclic loading between the LPCC group and the HP group (0.6 vs. 1.7 mm; P = .02) and between the CH and HP groups (0.5 vs. 1.7 mm; P = .004). Fracture displacement was not different between the LPCC and the CH groups (P = .544). The CH group and the LPCC group showed a significantly higher stiffness compared to the HP group (P < .001 and P = .003, respectively). The CH group showed a significantly higher ultimate load to failure compared with the HP group (429 vs. 172 N; P = .005) and showed a tendency toward higher ultimate load to failure when compared with the LPCC group (429 vs. 258 N; P = .071).Conclusion:The CC stand-alone cow-hitch suture reconstruction and the locking plate with CC reconstruction showed higher fixation strength compared with the hook plate for simulated Neer type V distal clavicle fractures. There was a tendency of higher ultimate load to failure with the cow-hitch technique compared with the lateral locking plate with CC suture reconstruction, and given the potential advantages of less soft tissue stripping, metal-free fixation, low costs, and simple surgical technique, clinical application of the all-suture CC reconstruction using the cow-hitch for Neer type V distal clavicle fractures appears warranted.

Background: The suction seal of the hip plays an important role in maintaining hip stability; however, the function of the ligamentum teres in maintaining this seal remains poorly understood. This study aimed to evaluate the effectiveness of the hip suction seal in ligamentum teres deficient hips for joint positions occurring during gait. Methods: Six fresh -frozen human cadaveric hips were dissected and mounted to an Instron materials test system. Each specimen was analyzed for average peak distraction force, stiffness, and total energy during hip displacement. Testing was performed in the native intact ligamentum teres state and the deficient ligamentum teres state. Specimens were examined in 20 of flexion, neutral, and 10 of extension. Findings: In the neutral position, the ligamentum teres deficient state displayed a significant decrease in peak distraction force (mean difference: 33.2 N, p < 0.001), average stiffness (mean difference: 63.7 N/mm, p = 0.016), and total energy (mean difference: 82.3 mJ, p = 0.022) compared to the intact controls. In extension, the deficient state exhibited a significant decrease in peak distraction force (mean difference: 42.8 N, p < 0.001) and total energy (mean difference: 72.9 mJ, p = 0.007). In flexion, the deficient state displayed a significant decrease in peak distraction force relative to contols (mean difference: 7.1 N, p = 0.003). Interpretation: The ligamentum teres plays a significant role in maintaining the suction seal of the hip, with its effect being most prominent when the hip is in neural alignment or in extension. The findings suggest that ligamentum teres deficiency may be a relevant treatment target in the clinical setting.

Background: Hemiarthroplasty (HA) is a treatment option for complex proximal humeral fractures not suitable for conservative treatment or open reduction-internal fixation. Long-term outcomes using a large-metaphyseal volume prosthesis in the management of proximal humeral fractures have not been reported thus far. Methods: Between 2006 and 2010, 41 patients with proximal humeral fractures were treated with HA at our institution (average age, 62 years; age range, 38-85 years). Nine patients underwent revision surgery, 3 were lost to follow-up, and 7 died unrelated to the index surgical procedure. Twenty-two patients were reviewed clinically and radiographically after a mean period of 10.4 years (range, 9-13 years). Results: Of the 9 HA failures, 7 occurred within the first 2 postoperative years: 2 patients had infections and 5 had greater tuberosity nonunions or malunions. The other 2 patients underwent revision for rotator cuff deficiency >5 years after initial surgery. Among the patients available for final follow-up, the implant survival rate was 71% (22 of 31 patients). At final follow-up, these patients showed a mean relative Constant score of 76% (range, 49%-96%), mean active elevation of 116(degrees)(range, 60(degrees)-170(degrees)), and mean external rotation of 28 degrees (range, 0(degrees)-55(degrees)). The majority had good or excellent internal rotation, with internal rotation to the 12th thoracic vertebra in 13 patients (59%) and to the eighth thoracic vertebra in 7 (31%). The mean Subjective Shoulder Value was 76% (range, 40%-100%). Clinical outcomes did not significantly deteriorate over a period of 10 years, except for flexion (P < .001) and internal rotation (P = .002). On analysis of greater tuberosity healing, 1 patient had a nonunion and 10 patients (45%) had a malunion, whereas the greater tuberosity had healed in an anatomic position in 12 patients (55%). Patients with a displaced malunion of the greater tuberosity did not have inferior clinical results at last follow-up. Only 2 patients showed glenoid erosion, and in no patients could stem loosening be identified at final follow-up. Conclusion: The revision rate following large-metaphyseal volume HA to treat a proximal humeral fracture was 29% after 10 years postoperatively, with failure within 2 years largely related to greater tuberosity nonunion or malunion and failure later related to rotator cuff insufficiency. Patients with a retained implant showed good clinical and radiographic long-term results, without relevant deterioration over time even when the greater tuberosity healed in a nonanatomic position. Level of evidence: Level IV; Case Series; Treatment Study (c) 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.

The Latarjet procedure is an established surgical treatment for recurrent glenohumeral joint instability with glenoid bone loss. Intraoperatively, the conjoint tendon and its attachement on the coracoid bone graft is routed through a split in subscapularis where the graft is fixed to and augments the anteroinferior glenoid. The objective of this in vitro study was to quantify the influence of glenohumeral joint position and conjoint tendon force on the lines of action and moment arms of subscapularis muscle sub-regions after Latarjet surgery. Eight fresh-frozen, entire upper extremities were mounted onto a testing apparatus, and a cable-pulley system was used to apply physiological muscle loading to the major shoulder muscles. The lines of action and moment arms of four subregions of subscapularis (superior, mid-superior, mid-inferior, and inferior) were quantified radiographically with the conjoint tendon unloaded and loaded while the shoulder was in (i) 0 degrees abduction (ii) 90 degrees abduction (iii) 90 degrees abduction and full external rotation (ABER), and (iv) the apprehension position, defined as ABER with 30 degrees horizontal extension. Conjoint tendon loading after Latarjet surgery significantly increased the inferior inclination of the lines of action of the mid-inferior and inferior subregions of subscapularis in the scapular plane in ABER and apprehension positions (p < 0.001), as well as decreased the horizontal flexion moment arm of the inferior subscapularis (p = 0.040). Increased subscapularis inferior inclination may ultimately increase inferior joint shear potential, while smaller horizontal flexion leverage may reduce joint flexion capacity. The findings have implications for Latarjet surgical planning and postoperative rehabilitation prescription.

BACKGROUND:Manual compartment palpation is used as a component of the clinical diagnosis of acute compartment syndrome (ACS), particularly in obtunded patients. However, its utility and accuracy in the upper limb are unknown. The purposes of this study were to assess the accuracy of manual compartment palpation of ACS in the forearm in a cadaveric model and to assess the role of clinician experience in this setting. METHODS:Reproducible, sustained elevation of intracompartmental pressure was established in 8 fresh upper-limb cadaveric specimens. The 3 forearm compartments (volar, dorsal, and mobile wad) were randomized to pressures of 20 and 40 mm Hg (negative controls) and 60 and 80 mm Hg (ACS). This was achieved by using fluid infusion and a pressure monitoring system. Orthopaedic clinicians with varying experience (residents, registrars, and consultants) used palpation to assess forearm compartments with known intracompartmental pressures. The examiners were blinded to the compartment pressures and the other examiners' responses. After the examination, the following 3 questions were answered: (1) Was compartment syndrome present? (2) In which compartment(s) was the pressure elevated? (3) What would be the next management step (fasciotomy or observation)? RESULTS:Manual palpation of compartment pressure had an overall sensitivity of 70%, a specificity of 56%, a positive predictive value of 24%, a negative predictive value of 90%, and a likelihood ratio (LR) of 20.3 (p < 0.001). The sensitivity was similar in detecting ACS in the volar and dorsal compartments (70% and 69%, respectively). The sensitivity and specificity of combined volar and dorsal compartment palpation were 81% and 64% (LR, 16.6; p < 0.001) when performed by residents, 72% and 46% (LR, 4.2; p = 0.040) when performed by registrars, and 58% and 63% (LR, 3.6; p = 0.057) when performed by consultants. All of the compartments that were deemed positive for ACS were recommended for fasciotomy. CONCLUSIONS:In our study, manual palpation of compartment pressure had a low accuracy in the diagnosis of ACS of the forearm and was not improved by clinician experience. CLINICAL RELEVANCE:We recommend against the use of manual palpation of compartment pressure in the diagnosis of forearm ACS in an obtunded patient.

Background: Excessive glenoid retroversion is a known risk factor for posterior shoulder instability and failure after soft tissue stabilization procedures. Whether excessive glenoid retroversion is a risk factor for failure after posterior glenoid bone grafting is unknown. Purpose: To evaluate the biomechanical effectiveness of posterior iliac crest bone grafting (ICBG) for posterior shoulder instability with increasing glenoid retroversion. Study Design: Controlled laboratory study. Methods: Six fresh-frozen cadaveric shoulders had a posterior glenoid osteotomy allowing the glenoid retroversion to be set at 0°, 10°, and 20°. At these 3 preset angles, 4 conditions were simulated consecutively on the same specimen: (1) intact glenohumeral joint, (2) posterior Bankart lesion, (3) 20% posterior glenoid bone defect, and (4) posterior ICBG. Stability was evaluated in the jerk position (60° of glenohumeral anteflexion, 60° of internal rotation) by measuring (A) posterior humeral head (HH) translation (in mm) and (B) peak translational force (in N) necessary for translation of the HH over 25% of glenoid width. Results: At 0° of retroversion, the ICBG restored posterior HH translation and peak translational force to values comparable with those of the intact condition ( P = .649 and P = .979, respectively). At 10° of retroversion, the ICBG restored the peak translational force to a value comparable with that of the intact condition (22.3 vs 24.7 N, respectively; P = .418) but showed a significant difference in posterior HH translation in comparison to the intact condition (4.5 vs 2.0 mm, respectively; P = .026). There was a significant increase in posterior HH translation and significant decrease in peak translational force with the ICBG at 20° of glenoid retroversion compared with the intact condition (posterior HH translation: 7.9 vs 2.0 mm, respectively; P < .006; peak translational force: 15.3 vs 24.7 N, respectively; P = .014). Conclusion: In this cadaveric study, posterior ICBG was able to restore stability to a level comparable to that of the native condition at 0° and to some extent at 10° of retroversion. However, posterior ICBG was not able to provide adequate stability at 20° of glenoid retroversion. Clinical Relevance: Posterior glenoid bone grafting with ICBG should be used with caution when performed in isolation in the setting of posterior instability associated with glenoid bone loss and combined glenoid retroversion of >10°.

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