Congruent Arc Research Articles

Bone block options for treating glenoid bone loss and glenohumeral instability: A systematic review.

To systematically review the literature assessing glenoid bone loss restoration by different bone block options and compare their dimensions. Systematic examination of articles in PubMed and EMBASE databases was performed per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to find studies of bone grafts for treating anterior glenohumeral instability. Statistical analyses were conducted via Review Manager, and a p-value of <0.05 was statistically significant. Our review included 25 studies evaluating 870 shoulders. Traditional arc Latarjet (TL) had more depth than congruent arc Latarjet (CAL; p = 0.003). The coronal radii of curvature of TL, CAL, distal tibia, and iliac crest bone blocks were similar to native glenoid (p = 0.400, 0.817, 0.467, 0.216, respectively). CAL coracoid bone blocks restored significantly more glenoid surface area (30.3%) than TL bone blocks (p = 0.012). The glenoid width and surface area restoration by distal clavicle bone blocks were equivalent to TL (p = 0.058 and p = 0.103, respectively). The CAL technique restored higher percentages of glenoid surface area than TL but has less depth, which may increase fracture risk during screw insertion. The distal clavicle bone block is a suitable substitute to TL as it was equivalent regarding glenoid width and surface area restoration.

Surgical Variations of the Modified Latarjet Procedure: A Literature Review and Video-Illustrated Surgical Technique.

The modified Latarjet procedure, otherwise known as the Walch-Boileau procedure, is a very successful management procedure for recurrent shoulder dislocation especially in patients with glenoid bone loss of less than 30 percent. Multiple variations of the surgical technique have been proposed over the years, some of which are still controversial. These variations include arthroscopic vs open technique, traditional versus congruent arc Latarjet procedure, subscapularis split versus L-shaped tenotomy, intra-articular versus extra-articular coracoid placement, capsular repair versus no repair, and the various modalities of coracoid fixation.The current evidence is based on a group of low-evidence heterogenous studiessince some of these variations lack strong clinical comparative studies that controlother variables. In this literature review, we present the evidence available for each of the above major variations. Furthermore, we present a video illustration of the surgical procedure done in our tertiary care center.

Application of LU-tarjet congruent-arc technique in treatment of recurrent shoulder dislocation with huge glenoid defect

To investigate the early effectiveness of the limited unique coracoid osteotomy suture button fixation Latarjet (LU-tarjet)-congruent-arc (CA) technique (LU-tarjet-CA) in treating recurrent shoulder dislocations with huge glenoid defect. The clinical data of 12 patients with recurrent shoulder dislocation and huge glenoid defect who met the selection criteria and treated with arthroscopic LU-tarjet-CA between January 2021 and December 2023 were retrospectively analyzed. The cohort included 8 males and 4 females, aged 20-40 years with an average age of 30.4 years. The range of glenoid bone loss was 30%-40%, with an average of 35.5%. The time from symptom onset to hospital admission ranged from 1 to 36 months, with an average of 18.5 months. The University of California Los Angeles (UCLA) score, American Association for Shoulder and Elbow Surgery (ASES) score, Walch-Duplay score, and Rowe score were used to evaluate shoulder function preoperatively and at 3, 6, and 12 months postoperatively. CT three-dimensional (3D) reconstruction was used to assess coracoid healing and plasticity at 3, 6, and 12 months postoperatively. Subjective satisfaction of patient was recorded at last follow-up. All incisions healed by first intention, with no incision infection or nerve injury. All 12 patients were followed up 12 months. One patient developed Propionibacterium acnes infection within the joint postoperatively and recovered after initial arthroscopic debridement and anti-inflammatory treatment. At 3 months after operation, CT 3D-reconstruction showed 1 case of complete coracoid absorption; neither of these two patients experienced redislocation. The remaining patients exhibited partial coracoid absorption but displayed local reshaping, filling the preoperative defect area, and bony fusion between the coracoid and the glenoid. At last follow-up, 9 patients (75%) were very satisfied with the outcome, and 3 patients (25%) were satisfied; the satisfied patients experienced postoperative shoulder stiffness caused by suboptimal functional exercise but did not have impaired daily life activities. The UCLA score, ASES score, Walch-Duplay score, and Rowe score at 3, 6, and 12 months postoperatively were significantly better than preoperative scores, and each score improved further over time postoperatively, with significant differences between different time points ( P<0.05). The arthroscopic LU-tarjet-CA technique for treating recurrent shoulder dislocations with huge glenoid defect can achieve the surgical objective of bony blockade and filling bone defects to prevent shoulder dislocation, thereby improving patients' quality of life and shoulder joint function and stability.

Outcome of Modified Open Latarjet Operation in the Treatment of the Recurrent Anterior Shoulder Dislocation: A Cohort Study

Introduction: Shoulder instability is defined as a symptomatic translation of the humeral head about the glenoid fossa during active shoulder motion. Anteroinferior glenoid bone loss or labrum avulsion is most often a consistent finding in recurrent dislocation. The modified open Latarjet procedure is one of the most effective methods of treatment for patients with recurrent shoulder instability with glenoid bone loss. Aim: To determine the functional outcome of the congruent arc modification of the open Latarjet procedure. Materials and Methods: This prospective cohort study was conducted at a tertiary healthcare centre in Bhopal, Madhya Pradesh, India between January 2018 and December 2020. A total of 25 patients with recurrent anterior shoulder dislocation underwent treatment using the modified open Latarjet procedure. Two patients were lost to follow-up, resulting in the evaluation of 23 patients. All patients underwent a 3D Computed Tomography (CT) scan to document glenoid bone loss. The intensity of pain, activity level, strength of abduction, and Range of Motion (ROM) were assessed to calculate the Constant Shoulder Score for pre- and postoperative evaluation of functional outcomes. Follow-ups were conducted at 3 months, 6 months, 1 year, and 2 years after surgery. The data was analysed using the Wilcoxon’s signed-rank test, and Spearman’s correlation coefficient was used to identify associations between various variables. Results: A total of 23 male patients aged between 18 and 63 years were included. The average age of patients was 30.35±11.27 years. Preoperatively, only 3 patients (13.04%) had good to excellent Constant Shoulder Scores. However, no statistically significant variation in Constant Score was observed three months after surgery. Six months post-surgery, 17 patients (73.92%) showed good to excellent scores. Nearly one year after surgery, 21 patients (91.3%) had good to excellent outcomes. At the final follow-up, 22 patients (95.65%) demonstrated good to excellent outcomes. A statistically significant improvement in good to excellent scores was noted six months postoperatively (p-value &lt;0.001). A total of 20 patients (86.96%) achieved full ROM, with only 3 patients (13.04%) reporting mild to moderate limitations in shoulder ROM. None of the patients experienced redislocation, and the apprehension test was positive in only one patient. Conclusion: The modified open Latarjet procedure is a reliable method for providing stability and Self confidence to patients with recurrent shoulder instability and glenoid bone loss.

The Radius of Curvature of the Inferior Distal Clavicle Is Similar to That of the Glenoid in Both the Axial and Coronal Planes and Similar to the Inferior Coracoid

The purposes of this study were to use computed tomography (CT) scans to compare the radius of curvature (ROC) of the inferior concave surface of the distal clavicle to the glenoid, determine graft dimensions, and compare the ROC of the congruent-arc distal clavicle autograft (DCA) to the congruent-arc Latarjet graft. Patients who underwent bony glenoid reconstruction via a Laterjet procedure between January 2018 and January 2023 at a single institution were retrospectively identified. CT scans were used to measure the ROC of the glenoid on the axial and coronal sequences, measure the ROC of the distal clavicle on the sagittal oblique sequences, and determine the dimensions of the distal clavicle and coracoid graft. A total of 42 patients were included (Latarjet, n= 22; control, n= 20). Themean ROC of the inferior surface of the distal clavicle was not significantly different from the ROC of the glenoid in the coronal (P= .15) or axial planes (P= .65). The ROC of the coracoid when measured in the sagittal plane was not significantly different from the ROC of the distal clavicle (P= .25). The length, depth, and surface area of the coracoid in the congruent arc orientation were significantly larger than the distal clavicle (P < .005). Patients in the control group tended to have both a larger inferior clavicle ROC and a larger coracoid ROC compared to the Latarjet group (32.8 mm vs 29.6 mm, P < .0001; 31.8 mm vs 30.9 mm, P= .02). The ROC of the inferior distal clavicle is similar to that of the glenoid in both the axial and coronal planes and similar to the inferior coracoid. CT analysis reveals that the congruent-arc DCA technique provides a robust graft with dimensions that are suitable for reconstruction of the anterior glenoid.

Poster 166: Distal Clavicle versus Traditional and Congruent Arc Latarjet: Comparison of Surface Area and Glenoid Apposition with 3-Dimensional CT and MRI

Objectives: Limited studies have compared graft-glenoid apposition and glenoid augmentation area between the latarjet and distal clavicle grafts in glenohumeral stabilization. Additionally, pre-operative planning is typically performed using computerized tomography (CT), and few studies have used 3- dimensional magnetic resonance imaging (3D-MRI) reformations to assess graft dimensions. The purpose of the study was two-fold: 1) compare bony apposition, glenoid augmentation, and graft width among coracoid and distal clavicle bone augmentation techniques and 2) to determine the viability of 3D-MRI to assess bone graft dimensions. Methods: Twenty-four patients with recurrent glenohumeral instability and bone loss were included in this study. 3D-CT and 3D-MRI reformations were utilized to measure pertinent dimensions for five orientations of coracoid and distal clavicle autografts: (1) standard Latarjet (SLJ), (2) congruent arc Latarjet (CLJ), and (3) distal clavicle attached by its posterior surface, (DCP) and (4) inferior surface (DCI), and (5) resected end (DCR). Glenoid augment area was defined as the graft surface area contributing to the glenoid. Bone-on-bone apposition was defined as the graft-glenoid contact area for bone healing potential, and graft width was pertinent for fixation technique. Paired t-tests were performed to compare graft sizes between patients and compare 3D-CT vs 3D-MRI measurements. Results: CLJ had the largest glenoid augmentation area (mean: 318mm2, sd: 74) while SLJ displayed the most apposition (mean: 318mm2, sd: 74). DCI had the largest graft width (mean: 21mm, sd: 4). Paired t- tests revealed no significant differences between Latarjet methods, whereas distal clavicle grafts varied significantly with orientation. All 3D-CT and 3D-MRI measurements were within 1mm of each other, and only two demonstrated statistically significant difference (coracoid width: 13.03 vs 13.98mm, p=0.010; distal clavicle thickness: 9.69 vs 10.77, p=0.002). 3D-CT and 3D-MRI measurements demonstrated strong positive correlation (r&gt;0.6 and p&lt;0.001 for all dimensions). Conclusions: Glenoid augmentation, bony apposition, and graft width can vary with coracoid or distal clavicle graft type and orientation. Differences between 3D-CT and 3D-MRI were small and likely not clinically significant.

Arthroscopic Distal Clavicle Bone Block Technique for Anteroinferior Instability With Critical Bone Loss

Arthroscopic distal clavicle autograft represents a locally available source of autograft for bone block augmentation in patients with anterior shoulder instability with glenoid bone loss. Anatomic and biomechanical studies have supported distal clavicle autograft use as comparable to coracoid graft with regard to restoration of glenoid articular surface, with the theoretical advantage of minimizing complications associated with coracoid transfer procedures, such as neurologic injury and coracoid fracture. The current technique describes a modification of those previously described, including a mini-open approach for distal clavicle autograft harvest, orientation of the distal clavicle with the medial clavicle graft against the glenoid (congruent arc), an all-arthroscopic technique of graft passage, and graft placement and fixation using specialized drill guides and four suture buttons to reproducibly place and secure the graft with final capsulolabral advancement over the graft to render it extra-articular.

Distal Clavicle Autograft Versus Traditional and Congruent Arc Latarjet Procedures: A Comparison of Surface Area and Glenoid Apposition With 3-Dimensional Computed Tomography and 3-Dimensional Magnetic Resonance Imaging

Background: Limited studies have compared graft-glenoid apposition and glenoid augmentation area between the Latarjet procedure and distal clavicle graft in glenohumeral stabilization. Additionally, preoperative planning is typically performed using computed tomography (CT), and few studies have used 3-dimensional (3D) magnetic resonance imaging (MRI) reformations to assess graft dimensions. Purpose: The purpose of this study was 2-fold: (1) to compare bony apposition, glenoid augmentation, and graft width among coracoid and distal clavicle bony augmentation techniques and (2) to determine the viability of 3D MRI to assess bone graft dimensions. Study Design: Controlled laboratory study. Methods: A total of 24 patients with recurrent glenohumeral instability and bone loss were included in this study. 3D CT and 3D MRI reformations were utilized to measure pertinent dimensions for 5 orientations of coracoid and distal clavicle autografts: (1) standard Latarjet procedure (SLJ), (2) congruent arc Latarjet procedure (CLJ), (3) distal clavicle attached by its posterior surface (DCP), (4) distal clavicle attached by its inferior surface (DCI), and (5) distal clavicle attached by its resected end (DCR). Glenoid augmentation was defined as the graft surface area contributing to the glenoid. Bone-on-bone apposition was defined as the graft-glenoid contact area for bone healing potential, and graft width was pertinent for fixation technique. Glenoid bone loss ranged from 0% to 34%. Paired t tests were used to compare graft sizes between patients and compare 3D CT versus 3D MRI measurements. Results: The CLJ had the largest graft surface area (mean, 318.41 ± 74.44 mm2), while the SLJ displayed the most bone-on-bone apposition (mean, 318.41 ± 74.44 mm2). The DCI had the largest graft width (mean, 20.62 ± 3.93 mm). Paired t tests revealed no significant differences between the Latarjet techniques, whereas distal clavicle grafts varied significantly with orientation. All 3D CT and 3D MRI measurements were within 1 mm of each other, and only 2 demonstrated a statistically significant difference (coracoid width: 13.03 vs 13.98 mm, respectively [P = .010]; distal clavicle thickness: 9.69 vs 10.77 mm, respectively [P = .002]). 3D CT and 3D MRI measurements demonstrated a strong positive correlation (r > 0.6 and P < .001 for all dimensions). Conclusion: Glenoid augmentation, bony apposition, and graft width varied with coracoid or distal clavicle graft type and orientation. Differences between 3D CT and 3D MRI were small and likely not clinically significant. Clinical Relevance: 3D MRI is a viable method for preoperative planning and graft selection in glenoid bone loss.

The congruent arc latarjet procedure – Its functional outcomes in recurrent anterior shoulder dislocation with critical glenoid bone loss

Background: Recurrent shoulder dislocation leading to shoulder instability is a cumbersome clinical problem for patients and orthopedicians. Due to a lack of knowledge in young patients of developing countries, there is a delay in presentation from the first time of dislocation. The aim of this retrospective study was to evaluate the functional and radiographic outcomes of patients with shoulder instability after the Congruent Arc Latarjet procedure. Methods: From January 2018 to November 2021, 20 patients with history of recurrent shoulder dislocation having glenohumeral instability were treated surgically in our institute. Open Congruent Arc Latarjet procedure was performed in 20 patients. Functional outcomes were assessed preoperatively and postoperatively based on American Shoulder and Elbow Surgeons (ASES) score, the visual analog scale (VAS) for pain, ROWE score, and Active range of motion in the diseased shoulder. Results: Twenty shoulders of 20 patients were evaluated for a mean period of 24 months postoperatively. At the time of the latest consultation, the range of motion and the shoulder functional evaluations based on ROWE score which was 89.64 ± 5.71 (range 80–95) improved from 20.36 ± 8.87 (range 10–30), p = 0.001. The mean preoperative ASES score was 22.60 ± 1.09 (range 20.6–25) which improved to 72.50 ± 7.33 (range 52.8–77.2), p = 0.001, which is definitely improved. The overall re-dislocation rate was 0% (0 of 20). In our study, 60% had excellent outcomes, 30% had good outcomes, and 10% had fair outcomes. Conclusion: The Congruent Arc Latarjet procedure for the treatment of recurrent shoulder dislocation with glenoid bone loss of &gt;20% is a successful and efficient method with better outcomes in daily work profile and no further episode of redislocation.

Comparison of the Coracoid, Distal Clavicle, and Scapular Spine for Autograft Augmentation of Glenoid Bone Loss: A Radiologic and Cadaveric Assessment

Background: Glenohumeral instability caused by bone loss requires adequate bony restoration for successful surgical stabilization. Coracoid transfer has been the gold standard bone graft; however, it has high complication rates. Alternative autologous free bone grafts, which include the distal clavicle and scapular spine, have been suggested. Study Design: Controlled laboratory study. Purpose: The purpose of this study was to determine the percentage of glenoid bone loss (GBL) restored via coracoid, distal clavicle, and scapular spine bone grafts using a patient cohort and a cadaveric evaluation. Methods: Autologous bone graft dimensions from a traditional Latarjet, congruent arc Latarjet, distal clavicle, and scapular spine were measured in a 2-part study using 52 computed tomography (CT) scans and 10 unmatched cadaveric specimens. The amount of GBL restored using each graft was calculated by comparing the graft thickness with the glenoid diameter. Results: Using CT measurements, we found the mean percentage of glenoid restoration for each graft was 49.5% ± 6.7% (traditional Latarjet), 45.1% ± 4.9% (congruent arc Latarjet), 42.2% ± 7.7% (distal clavicle), and 26.2% ± 8.1% (scapular spine). Using cadaveric measurements, we found the mean percentage of glenoid restoration for each graft was 40.2% ± 5.0% (traditional Latarjet), 53.4% ± 4.7% (congruent arc Latarjet), 45.6% ± 8.4% (distal clavicle), and 28.2% ± 7.7% (scapular spine). With 10% GBL, 100% of the coracoid and distal clavicle grafts, as well as 88% of scapular spine grafts, could restore the defect (P < .001). With 20% GBL, 100% of the coracoid and distal clavicle grafts but only 66% of scapular spine grafts could restore the defect (P < .001). With 30% GBL, 100% of coracoid grafts, 98% of distal clavicle grafts, and 28% of scapular spine grafts could restore the defect (P < .001). With 40% GBL, a significant difference was identified (P = .001), as most coracoid grafts still provided adequate restoration (congruent arc Latarjet, 82.7%; traditional Latarjet, 76.9%), but distal clavicle grafts were markedly reduced, with only 51.9% of grafts maintaining sufficient dimensions. Conclusions: The coracoid and distal clavicle grafts reliably restored up to 30% GBL in nearly all patients. The coracoid was the only graft that could reliably restore up to 40% GBL. Clinical Relevance: With “subcritical” GBL (>13.5%), all autologous bone grafts can be used to adequately restore the bony defect. However, with “critical” GBL (≥20%), only the coracoid and distal clavicle can reliably restore the bony defect.

Designing an outer toothed gear whose wheel teeth are outlined by the logarithmic spiral arcs

Toothed gears are the most common mechanical gears in machine building, which are characterized by high reliability and durability, a constant transfer number, and which can transmit high torque. During toothed gear operation, the surfaces of the teeth slide, which gives rise to friction forces and wears their working surfaces. To prevent this, the surfaces of the teeth need constant lubrication. This paper considers the design of a gear tooth engagement, which does not have friction between the surfaces of the teeth since they roll over each other without slipping. The profile of the tooth of such a gear is outlined by congruent arcs, symmetrical relative to the line that connects the center of rotation of the toothed wheel with the top of the tooth. These symmetrical curves at the top of the tooth intersect at the predefined angle. In the depressions of the wheel, adjacent teeth also intersect at the same angle. Such a condition can be ensured by a curve that at all its points crosses the radius-vector emanating from the coordinate origin, also at a stable angle equal to half of the given one. This curve is a logarithmic spiral. If the number of teeth of the drive and driven wheels is the same, then their teeth are congruent. Otherwise, the profiles of the teeth would differ but they could be outlined by congruent arcs of the same logarithmic spiral of the same length taken from different areas of the curve. The minimum possible angle at the top of the teeth is straight. At acute angle, the toothed gear operation is impossible. To build gear wheels with a right angle at the top of the tooth, it would suffice to set the number of teeth of the drive and driven wheels. The center-to-center distance is calculated using the derived formula. The transfer number of such a gear is variable but, with an increase in the number of teeth, the range of its change decreases. The algorithm of wheel construction is given.

Arthroscopic Distal Clavicular Autograft for Congruent Glenoid Reconstruction

Arthroscopic distal clavicular autograft (DCA) is effective in shoulder instability with glenoid bone loss. The original technique uses an osteochondral autograft, fixed with screws or suture anchors. We developed a modified procedure called “congruent arc DCA” characterized by (1) use of drilling guides to optimize graft positioning and make the all-arthroscopic procedure safer and reproducible; (2) rotation of the DCA of 90° to reach a congruent arc with its undersurface; (3) fixation of the graft with cortical buttons to simplify its intra-articular passage, avoid hardware problems, and facilitate possible revision surgery; and (4) intraoperative use of a suture tensioner to achieve satisfactory compression of the graft and increase its consolidation.

Clinical Outcomes of the Traditional Latarjet Versus the Congruent Arc Modification for the Treatment of Recurrent Anterior Shoulder Instability: A Meta-analysis.

Background:Few studies have compared clinical outcomes between the traditional Latarjet procedure for anterior shoulder instability and the congruent arc modification to the Latarjet procedure.Purpose:To systematically evaluate the literature for the incidence of recurrent instability, clinical outcomes, radiographic findings, and complications for the traditional Latarjet procedure and the congruent arc modification and to compare results of each search.Study Design:Systematic review; Level of evidence, 4.Methods:A systematic review and meta-analysis was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We included studies published between January 1990 and October 2020 that described clinical outcomes of the traditional Latarjet and the congruent arc modification with a follow-up range of 2 to 10 years. The difference in surgical technique was analyzed using a chi-square test for categorical variables, while continuous variables were evaluated using a Student t test.Results:In total, 26 studies met the inclusion criteria: 20 studies describing the traditional Latarjet procedure in 1412 shoulders, and 6 studies describing the congruent arc modification in 289 shoulders. No difference between procedures was found regarding patient age at surgery, follow-up time, Rowe or postoperative visual analog scores, early or late complications, return-to-sport timing, or incidence of improper graft placement or graft fracture. A significantly greater proportion of male patients underwent glenoid augmentation using the congruent arc modification versus traditional Latarjet (P < .001). When comparing outcomes, the traditional Latarjet procedure demonstrated a lower incidence of fibrous union or nonunion (P = .047) and broken, loose, or improperly placed screws (P < .001), and the congruent arc modification demonstrated improved outcomes with regard to overall return to sport (P < .001), return to sport at the same level (P < .001), incidence of subluxation (P = .003) or positive apprehension (P = .002), and revision surgery for recurrent instability (P = .027).Conclusion:Outcomes after the congruent arc modification proved at least equivalent to the traditional Latarjet procedure in terms of recurrent instability and return to sport, although early and late complications were equivalent. The congruent arc procedure may be an acceptable alternative to traditional Latarjet for the treatment of anterior shoulder instability with glenoid bone loss; however, long-term outcomes of this procedure are needed.

Glenoid "Pear Restoration" with the Traditional Latarjet versus Congruent Arc Modification: CT Assessment of Coracoid Morphology for Preoperative Planning

Glenoid "Pear Restoration" with the Traditional Latarjet versus Congruent Arc Modification: CT Assessment of Coracoid Morphology for Preoperative Planning

Computed Tomography–Based Preoperative Planning Provides a Pathology and Morphology-Specific Approach to Glenohumeral Instability With Bone Loss

To use computed tomography (CT) to determine a reproducible method of coracoid measurement to compare the ability of the classic Latarjet technique and the congruent arc modification (CAM) to restore native glenoid diameter and to develop a preoperative planning algorithm for glenoid restoration with a goal of achieving an on-track shoulder. Coracoid dimensions were measured on multiplanar reconstructed shoulder CT scans of patients aged 18 to 45 years obtained between December 1, 2019, and March 13, 2020. Patients were excluded if CT demonstrated osteophyte formation, glenoid dysplasia, coracoid fracture, or tumor. The proportion of glenoid diameter able to be restored using classic Latarjet technique and CAM were calculated. A treatment algorithm was proposed considering the amount of bone loss present and coracoid dimensions. Coracoid dimensions of 117 consecutive patients were measured and varied considerably (length: 17.5-31.8 mm, width: 9.1-20.5 mm, thickness: 6.1-15.7 mm). While most patients had harvestable coracoid length ≥20 mm (male: 96.3% vs female: 94.4%, P= .65), only 27.8% of female patients had coracoid thickness ≥10 mm. When comparing Latarjet techniques, there was no difference in the proportion of patients in whom 30% glenoid diameter could be fully restored, but CAM was able to restore at least 35% in more male and female patients (98.8% vs 79.0% and 100% vs 61.1%, respectively, P= .00001). Intra- and inter-rater reliability was excellent ( intraclass correlation coefficient ≥0.950 for all dimensions). We describe a reliable method of measuring coracoid dimensions for preoperative planning of glenoid restoration. The classic Latarjet technique reliably restores the glenoid anteroposterior diameter with bone loss of up to 30%. The majority of female patients have coracoid thickness <10 mm, which may increase the risk of graft fracture when using CAM. The decision to use the classic Latarjet technique or CAM considers each individual's glenoid and coracoid dimensions with a goal of achieving an on-track shoulder. Our reliable method of coracoid measurement demonstrated the differing abilities of the classic Latarjet and CAM to restore the native glenoid diameter. An evidence-based algorithm using these measurements was developed to assist in preoperative planning for glenohumeral instability in the setting of bone loss, with a goal of achieving an on-track shoulder. Alternative techniques may be considered if an on-track shoulder cannot be achieved with Latarjet.

Congruent Arc Latarjet with Subscapularis Split in Patients with Shoulder Instability and Hill Sachs Lesions: Functional Outcome at 2-Year Follow-Up

Introduction: Shoulder dislocations are the most frequent of all dislocations in the body. Recurrence of shoulder dislocations is common in the younger age group with associated Bankart or Hill Sach’s lesions. Over 200 procedures have been described in the literature for the treatment of recurrent anterior dislocation of shoulder.

Моделювання центроїд некруглих коліс із внутрішнім і зовнішнім коченням із дуг симетричних кривих

The article considers the design of noncircular wheels, which serve as centroids in the design of gears. Centroids consist of congruent arcs of a given symmetric curve. The number of these arcs, that is the elements of the centroid, is determined by the type of gearing (internal or external). In external gearing, the number of elements of both centroids can be arbitrary, starting with one element. In the case of internal gearing, the number of elements of the internal centroid must be one less than the number of elements of the external centroid. If the number of elements is the same, then the centroids coincide. Rolling centroids one by one occurs in the absence of sliding. This is possible provided that the lengths of the arcs of the individual elements of both centroids are equal to each other. The construction of a centroid is carried out in a polar coordinate system. Both centroids are formed by rotating its element, that is the arc of the curve, at a given angle around the pole. The magnitude of the angle depends on the number of elements of the centroid. When rolling one centroid on the other, the pole of the moving centroid must describe the circle. In this case, the rolling of a moving centroid on a stationary one can be replaced by the rotational motion of both centroids around the fixed centers (poles). The point of contact of the centroids during their rotation is on the segment connecting the centers of rotation and which is called the center-to-center distance. This point for non-circular wheels when they rotate makes a certain movement along the specified segment, and for round wheels remains stationary. The length of the arc of an element of one centroid is determined by the magnitude of the central angle on which it rests. The same applies to the element of the second centroid. If the lengths of the arcs of the elements of the centroid are equal, then the values of the corresponding angles are not equal and are in a certain functional dependence. Finding this dependence is reduced to the integration of the expression obtained on the basis of the equality of the differentials of the arcs of the corresponding centroid elements. This expression may not be integrated for all curves from which the arcs of the original or leading centroid are formed. If the expression cannot be integrated, then the construction of the driven centroid must be carried out by numerical methods. The article considers a curve based on the hyperbolic cosine, for which the obtained expression is integrated. The parametric equations of the curves of which the arcs of both the leading and the driven centroids consist are given. It is shown that for a centroid with a given ratio of elements the intercenter distance is determined unambiguously. Centroid drawings with different number of elements for internal and external gearing are constructed.

A cadaveric morphometric analysis of coracoid process with reference to the Latarjet procedure using the "congruent arc technique".

Congruent arc Latarjet procedure involves rotating the coracoid process so that its inferior surface is flush with the glenoid face, owing to their matching radius of curvature (ROC). However, there has been no cadaveric study to actually measure and compare the ROC of coracoid with glenoid, especially in Indian population. 44 shoulders were dissected in 24 cadavers to measure usable length of coracoid process, width, height, ROC of coracoid and glenoid as well as ulnar length (as proxy of cadaver height). Critical coracoid height and length were estimated based on screw sizes of 2.7mm, 3.5mm, 4mm and 4.5mm, and pair concordance between height and length calculated. ROC of coracoid and glenoid were compared to measure extent of congruency. The mean usable length of coracoid process, width and height at mid-point were 21.8mm, 13.7mm and 8.6mm, respectively. Out of the different screw sizes, 2.7mm screws were found safe in 82% shoulders. 24 coracoid-glenoid pairs fulfilled the operational definition (≤ 5mm) of congruency while rest 20 were seemingly incongruent chiefly due to coracoid variations, with mean ROC difference 4.13mm (95% CI 1.51-6.74mm). The ulnar length was significantly smaller in the incongruent ROC group (p = 0.0002). The available length as well as height of the transferred coracoid must be considered when deciding optimum diameter fixation screws in Latarjet procedure. Owing to smaller anatomic dimensions of coracoid in Indian population, 2.7-mm screws provide the safest fixation option. Also, the ROC of coracoid and glenoid does not match in substantial proportion of the cadavers. Pre-operative planning should include a CT-based assessment of glenoid and coracoid dimensions to decide the technique of Latarjet procedure and the optimum diameter fixation screws required.

Are the Classic and the Congruent Arc Latarjet Procedures Equally Effective for the Treatment of Recurrent Shoulder Instability in Athletes?

Background: There is a lack of evidence in the literature comparing outcomes between the classic and the congruent arc Latarjet procedures in athletes. Purpose: To compare return to sports, functional outcomes, and complications between the classic and the congruent arc Latarjet procedures in athletes with recurrent glenohumeral instability. Study Design: Cohort study; Level of evidence, 3. Methods: Between June 2009 and June 2017, 145 athletes with recurrent anterior glenohumeral instability underwent surgery with the Latarjet as a primary procedure in our institution. The classic procedure was used in 66 patients, and the congruent arc method was used in 79 patients. Return to sports, range of motion (ROM), the Rowe score, a visual analog scale (VAS) for pain in sports activity, and the Athletic Shoulder Outcome Scoring System (ASOSS) were used to assess functional outcomes. Recurrences were also evaluated. The postoperative bone block position and consolidation were assessed with computed tomography. Results: In the total population, the mean follow-up was 41.3 months (range, 24-90 months) and the mean age was 25.3 years (range, 18-45 years). In total, 90% of patients were able to return to sports; of these, 91% returned at their preinjury level of play. No significant difference in shoulder ROM was found between preoperative and postoperative results. The Rowe, VAS, and ASOSS scores showed statistical improvement after operation (P < .001). The Rowe score increased from a preoperative mean of 42.8 points to a postoperative mean of 95.2 points (P < .01). Subjective pain during sports improved from 3.2 points preoperatively to 0.7 points at last follow-up (P < .01). The ASOSS score improved significantly from a preoperative mean of 46.4 points to a postoperative mean of 88.4 points (P < .01). No significant differences in shoulder ROM and functional scores were found between patients who received the classic vs congruent arc procedures. There were 5 recurrences (3.5%): 3 dislocations (2%) and 2 subluxations (1%). No significant difference in the recurrence rate was noted between groups. The bone block healed in 134 cases (92%). Conclusion: In athletes with recurrent anterior glenohumeral instability, the Latarjet procedure produced excellent functional outcomes. Most athletes returned to sports at their preinjury level, and the rate of recurrence was very low, regardless of whether the patients received surgery with the classic or congruent arc technique.

Similar Results in Return to Sports, Recurrences, and Healing Rates Between the Classic and Congruent-Arc Latarjet for Athletes With Recurrent Glenohumeral Instability and a Failed Stabilization

To compare the return-to-sport rate, functional outcomes, and complications of the "classic Latarjet" surgery with those of the "congruent arc Latarjet" surgery in athletes with recurrent glenohumeral instability and failed previous stabilization procedures. All the included patients were operated between May 2009 and April 2017. The inclusion criteria were athletes with recurrent anterior glenohumeral instability, a glenoid bone defect greater than 20%, at least 1 previous failed stabilization surgery operated with the classic or the congruent-arc Latarjet procedures, and a minimum 2 years of follow-up. Return to sports, range of motion (ROM), the Rowe score, a visual analog scale for pain, and the Athletic Shoulder Outcome Scoring System score were used to assess functional outcomes. Complications were also evaluated. A total of 135 athletes were included in the study (55 patients were operated with the classic technique and 80 with the congruent arc technique). The mean follow-up was 40.3 months (range, 24-88 months) and the mean age was 26.5 years (range, 18-45 years). Overall, 87% were able to return to sports and 92% returned at the same level. No significant difference regarding return to sports was found between the groups. No significant difference in shoulder ROM was found between preoperative and postoperative results. The Rowe, visual analog scale, and Athletic Shoulder Outcome Scoring System scores showed statistical improvement after operation (P < .001). No significant difference in shoulder ROM and functional scores was found between patients operated with the classic and congruent arc procedures. There were 6 recurrences (4%). There was no significant difference in the recurrence rate between groups. The bone block healed in 92% of the cases. In athletes with recurrent anterior glenohumeral instability and a failed previous operative repair, the Latarjet procedure produced excellent functional outcomes and most athletes returned to sport at their preinjury level with a very low rate of recurrences, regardless of whether the Latarjet was performed with the classic or with the congruent arc technique. Retrospective comparative study; Level of evidence,3.