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ABSTRACT: PURPOSE: The purpose of this biomechanical study was to compare the classic Latarjet technique and congruent-arc modification with respect to glenohumeral stability, joint stiffness, translation, and range of motion. METHODS: Eight cadaveric forequarters were tested on a shoulder simulator that applied loads independently to the conjoint tendon, long head of biceps, rotator cuff, and deltoid. The test conditions included: intact, 30% glenoid defect, and reconstruction of the defect with the classic and congruent Latarjets. The Latarjet techniques were randomly ordered, with the outcome variables being anterior dislocation, glenohumeral translation, rotational range of motion, and joint stiffness. RESULTS: All 8 specimens dislocated after creation of a 30% glenoid defect. The classic Latarjet stabilized 7 of 8 specimens, whereas the congruent-arc modification stabilized all specimens (8/8). In abduction neutral rotation, there was no difference in joint translation between techniques (P = .613). In abduction external rotation, there was significantly greater anterior humeral head translation after the congruent technique than after the classic (9.9 and 6.5 mm, respectively, P = .013). Rotational range of motion was significantly reduced after classic (-25.8°) and congruent (-22.2°) transfers as compared with the 30% defect (P ≤ .041). Joint stiffness in the abducted, externally rotated position was significantly reduced in the 30% defect as compared with intact (P = .012), congruent (P = .015), and classic (P < .001) conditions. In all abduction positions, the intact was not significantly different from the Latarjet techniques, and the techniques did not significantly differ from each other (P ≥ .102). CONCLUSIONS: The classic and congruent-arc Latarjet techniques restore shoulder stability and motion in cases of considerable bone loss. The techniques do not substantially differ in rotational range of motion or joint stiffness. The congruent-arc technique, however, does result in significantly greater anterior humeral head translation, as compared with the classic technique, before reaching a stable non-dislocated endpoint. CLINICAL RELEVANCE: On the basis of this biomechanical model, both the classic and congruent-arc Latarjet techniques can be used to stabilize a shoulder with substantial glenoid bone loss. Further clinical and biomechanical studies are required to determine if particular clinical circumstances exist where 1 technique has an advantage over the other.
Arthroscopy The Journal of Arthroscopic and Related Surgery 01/2013; · 3.02 Impact Factor
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ABSTRACT: BACKGROUND: This biomechanical study evaluated the effects of 3 remplissage techniques on shoulder stability and motion in a Hill-Sachs (HS) instability model. MATERIALS AND METHODS: Cadaveric forequarters were tested on an active shoulder simulator. Three remplissage techniques were performed for 15% and 30% HS defects. Testing conditions included intact and 15% and 30% HS defects, and the 3 remplissage techniques: T1, anchors in the defect valley; T2, anchors in humeral head rim; and T3, anchors in valley with medial suture placement. Outcomes included stability, internal-external rotation range of motion (IE-ROM), and joint stiffness. RESULTS: All remplissage techniques improved shoulder stability. In 15% HS defects tested in adduction, T3 significantly reduced IE-ROM (P = .037), whereas T1 and T2 did also (mean IE-ROM reductions: T1, 14°; T2, 11°; T3, 21°), but not to significance (P ≥ .088). In abduction, no significant reductions in IE-ROM occurred (P ≥ .060). In 30% HS defects tested in adduction (mean reduction IE-ROM: T1, 11°; T2, 19°; T3, 28°) and abduction (mean reduction: T1, 9°; T2, 15°; T3, 21°), all techniques significantly reduced IE-ROM (P ≤ .046). All techniques increased joint stiffness from 100% to 320% beyond the Bankart repair alone. A significant increase in joint stiffness was observed for T3 compared with the 30% HS group (P = .004), whereas T2 trended toward an increase (P = .078). There was no significant increase in joint stiffness with T1 (P = .249). CONCLUSIONS: All remplissage techniques enhanced shoulder stability, restricted ROM, and increased joint stiffness. No significant differences were found between anchors placed in the valley (T1) vs those placed in the humeral head rim (T2). Medial suture placement (T3) resulted in the greatest joint stiffness values and mean restriction in motion.
Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 10/2012; · 1.93 Impact Factor
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ABSTRACT: BACKGROUND:The Latarjet procedure has been described as a reconstructive option for instability associated with substantial glenoid bone defects. A modification, termed the Congruent-Arc, is thought to improve glenoid reconstruction through better articular congruency and greater bone reconstitution. The strengths of these techniques, however, have not been reported.Purpose/ HYPOTHESIS:To compare the fixation stability, strength, glenoid vault load transfer, and joint contact between the Classic and Congruent-Arc techniques. The authors hypothesized that the Classic Latarjet would exhibit inferior joint contact characteristics while having greater stability and strength and more normal glenoid vault strain. STUDY DESIGN:Controlled laboratory study. METHODS:Sixteen shoulder specimens (8 pairs) were tested by loading the glenohumeral joint with the glenoid intact, following creation of a 25% anterior bone defect, and after random assignment to the Classic or Congruent-Arc Latarjet techniques. Specimens were mounted to a testing apparatus that allowed concentric, centralized loading and loading 30° anterior on the glenoid rim. Cyclic loading (100 cycles at 1 Hz) was applied with a staircase protocol (50, 100, 150, and 200 N). Graft interface displacement and glenoid load transfer, quantified in terms of strain, were recorded during loading. Contact was quantified during 50-N loading using a thin pressure sensor. After cyclic loading, specimens were loaded to failure, defined as 5 mm of graft interface displacement. RESULTS:The 30° loading ≥100 N resulted in significantly greater graft displacement (P < .004) in the Congruent-Arc group as compared with the Classic (mean displacement range, 0.9-2.6 vs 0.1-0.5 mm, respectively). Failure testing yielded a significantly (P = .010) greater ultimate strength for the Classic (557 N) as compared with the Congruent-Arc (392 N). Load-transfer measurements demonstrated that neither technique's glenoid vault strain values significantly differed from intact (P ≥ .076). Both techniques resulted in contact areas significantly less than intact (P < .035); however, the Congruent-Arc trended toward better contact characteristics (P = .074). CONCLUSION:The Congruent-Arc results in significantly poorer fixation stability as compared with the Classic technique but did more closely reproduce intact joint contact, which may yield more favorable long-term outcomes. CLINICAL RELEVANCE:Care must be taken in balancing the consideration of initial fixation stability and joint contact for the Congruent-Arc and Classic Latarjet, as these factors have opposing implications for each of the 2 reconstructions' outcomes.
The American journal of sports medicine 09/2012; · 3.61 Impact Factor
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ABSTRACT: INTRODUCTION: Glenohumeral instability with glenoid bone loss is commonly treated with the Latarjet procedure. The procedure involves transfer of the coracoid and conjoint tendon, which is thought to provide a stabilizing sling effect; however, its significance is unknown. This study evaluated the effects of the Latarjet procedure, with and without conjoint tendon loading, on shoulder stability and range of motion (ROM). MATERIALS AND METHODS: A custom simulator was used to evaluate anterior shoulder stability and ROM in 8 cadaveric shoulders. Testing conditions included intact, 30% glenoid defect, and Latarjet with and without conjoint loading. Unloaded and 10-N loaded states were tested in adduction and 90° abduction. Outcome variables included dislocation, stiffness (neutral and 60° external rotation), and internal-external rotational ROM. RESULTS: All 30% defects dislocated in abduction external rotation. The loaded Latarjet prevented dislocation in all specimens, whereas the unloaded Latarjet stabilized 6 of 8 specimens. In abduction external rotation, there were no significant differences in stiffness between loaded and unloaded transfers (P = .176). In adduction, there were no significant differences between the intact and the loaded Latarjet (P ≥ .228); however, in neutral rotation, the unloaded Latarjet (P = .015) and the 30% defects (P = .011) were significantly less stiff. Rotational ROM in abduction was significantly reduced with the loaded Latarjet (P = .014) compared with unloaded Latarjet, and no differences were found in adduction. CONCLUSIONS: These findings indicate that glenohumeral stability is improved, but not fully restored to intact, with conjoint tendon loading. The results support the existence of the sling effect and its importance in augmenting stability provided by the transferred coracoid.
Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 09/2012; · 1.93 Impact Factor
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ABSTRACT: The remplissage procedure may be performed as an adjunct to Bankart repair to treat recurrent glenohumeral dislocation associated with an engaging Hill-Sachs humeral head defect. The purpose of this in vitro biomechanical study was to examine the effects of the remplissage procedure on glenohumeral joint motion and stability.
Cadaveric shoulders (n = 8) were mounted on a biomechanical testing apparatus that applies simulated loads to the rotator cuff and the anterior, middle, and posterior heads of the deltoid muscle. Testing was performed with the shoulder intact, after creation of the Bankart lesion, and after repair of the Bankart lesion. In addition, testing was performed after Bankart repair with and without remplissage in shoulders with 15% and 30% Hill-Sachs defects. Shoulder motion and glenohumeral translation were recorded with an optical tracking system. Outcomes measured included stability (joint stiffness and defect engagement) and internal-external glenohumeral rotational motion in adduction and in 90° of composite shoulder abduction.
In specimens with a 15% Hill-Sachs defect, Bankart repair combined with remplissage resulted in a significant reduction in internal-external range of motion in adduction (15.1° ± 11.1°, p = 0.039), but not in abduction (7.7° ± 9.9, p = 0.38), compared with the intact condition. In specimens with a 30% Hill-Sachs defect, repair that included remplissage also significantly reduced internal-external range of motion in adduction (14.5° ± 11.3°, p = 0.049) but not in abduction (6.2° ± 9.3°, p = 0.60). In specimens with a 15% Hill-Sachs defect, addition of remplissage significantly increased joint stiffness compared with isolated Bankart repair (p = 0.038), with the stiffness trending toward surpassing the level in the intact condition (p = 0.060). In specimens with a 30% Hill-Sachs defect, addition of remplissage restored joint stiffness to approximately normal (p = 0.41 compared with the intact condition). All of the specimens with a 30% Hill-Sachs defect engaged and dislocated after Bankart repair alone. The addition of remplissage was effective in preventing engagement and dislocation in all specimens. None of the specimens with a 15% Hill-Sachs defect engaged or dislocated after Bankart repair.
In this experimental model, addition of remplissage provided little additional benefit to a Bankart repair in specimens with a 15% Hill-Sachs defect, and it also reduced specific shoulder motions. However, Bankart repair alone was ineffective in preventing engagement and recurrent dislocation in specimens with a 30% Hill-Sachs defect. The addition of remplissage to the Bankart repair in these specimens prevented engagement and enhanced stability, although at the expense of some reduction in shoulder motion.
The Journal of Bone and Joint Surgery 06/2012; 94(11):1003-12. · 3.27 Impact Factor
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ABSTRACT: The management of engaging Hill-Sachs defects (HSD) is controversial. The purpose of this study was to biomechanically compare 3 treatment strategies.
Eight specimens were tested on a shoulder simulator. The protocol involved testing 2 unrepaired HSD (30% and 45%), which were then treated with remplissage, humeral head allograft (HHA), and partial resurfacing arthroplasty (PRA). Stability (defect engagement and glenohumeral stiffness) and range of motion (ROM) were measured.
All 30% and 45% HSDs engaged and dislocated. Remplissage and HHA effectively prevented engagement in all specimens; however, 62% of PRA engaged. No repair exhibited stiffness significantly greater than intact, but 30% and 45% remplissage produced a 74% and 207% increase, respectively, and were significantly greater than the unrepaired states (P ≤ .047). Stiffness results for HHA and PRA closely matched those of intact. In adduction, remplissage reduced internal-external ROM compared with both defects (P ≤ .01), but only 30% remplissage caused a significant decrease compared with intact (P = .049). In abduction, all repairs reduced ROM compared with HSD (P ≤ .04), but none compared with intact (P ≥ 0.05). In extension, remplissage had significantly less ROM than either HHA or PRA (P ≤ .02).
All procedures improved stability; however, unlike remplissage, results from HHA and PRA closely resembled intact. Remplissage (30% and 45%) improved stability and eliminated engagement but caused reductions in ROM. HHA and PRA re-established intact ROM, but PRA could not fully prevent engagement. The effects of each technique are not equivalent and further studies are required.
Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 10/2011; 21(9):1142-51. · 1.93 Impact Factor
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ABSTRACT: The purpose of this study was to determine the dimensions of the coracoid and to compare the radius of curvature (ROC) of the intact glenoid to the ROC of the coracoid undersurface, as oriented in the congruent-arc Latarjet procedure. The ROC of the coracoid undersurface was also compared with various glenoid bone loss scenarios.
Thirty-four computed tomography-based 3-dimensional models of the shoulder were examined by use of commercially available software. The mean dimensions of the coracoid were determined, and the ROC was calculated for the coracoid undersurface, the intact glenoid, and 20%, 35%, and 50% anterior glenoid bone loss scenarios. Intra-rater and inter-rater statistics were calculated.
The mean length, width, and thickness of the coracoid were 16.8 mm (SD, 2.5 mm), 15.0 mm (SD, 2.2 mm), and 10.5 mm (SD, 1.7 mm), respectively. The mean ROC values were 13.6 mm (SD, 3.4 mm) for the coracoid, 13.8 mm (SD, 2.1 mm) for the intact glenoid, 27.6 mm (SD, 5.3 mm) for 20% anterior glenoid bone loss, 30.5 mm (SD, 5.2 mm) for 35% bone loss, and 33.3 mm (SD, 5.2 mm) for 50% bone loss. The coracoid ROC was not significantly different from the intact glenoid (P = .75); however, it was significantly less (P < .01) when compared with all glenoid bone loss scenarios. Intra-rater reliability and inter-rater reliability were good or excellent. A coracoid oriented in the congruent-arc manner can reconstitute a significantly greater glenoid bone defect than a coracoid oriented in the classic manner (P < .001).
This image-based anatomic study found that the ROC of the coracoid undersurface matches the ROC of the intact anterior glenoid articular margin. In conditions with anterior glenoid bony deficiency, the radii of curvature differ significantly at the graft-native glenoid interface; however, the coracoid graft placed in the congruent-arc manner reconstitutes the ROC of the missing anterior glenoid rim. In addition, orienting the coracoid in the congruent-arc manner can reconstitute a greater glenoid bone defect than a coracoid placed in the original manner as described by Latarjet.
The congruent-arc Latarjet procedure, a modification of the original procedure, is truly congruent in relation to the intact anterior glenoid rim. In addition, the congruent-arc modification can reconstitute a greater glenoid bone defect when compared with the original Latarjet procedure.
Arthroscopy The Journal of Arthroscopic and Related Surgery 09/2011; 27(11):1485-9. · 3.02 Impact Factor
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ABSTRACT: The kinematics and stability of the shoulder during in-vitro simulation are affected by the muscles chosen for simulation and their loads. Existing simulators have commonly actuated the rotator cuff and deltoids; however, the contribution of secondary muscles, such as those which form the conjoined tendon, are not well understood. The conjoined tendon consists of the origins of the short head of the biceps and coracobrachialis (SH&C), and is thought to produce an anterior stabilizing effect. This study investigated the effect of SH&C tension at four loading levels: 0, 5, 10, 15N. Our primary outcome variable was glenohumeral stiffness for anterior loading but internal/external rotation and extension ranges of motion were also measured. Four joint configurations were tested: adduction and 90° combined abduction, each in neutral and maximal external rotation. Increasing SH&C load resulted in a significant trend of increased glenohumeral stiffness across the average of all joint configurations (p=0.008). In abduction, neutral rotation differences were found between the stiffness at 10 and 15N compared to 0N (p=0.038 and 0.043, respectively); however, no differences were found for the three other joint configurations. There was a tendency for a decrease in the range of shoulder extension with increasing SH&C load, but this did not achieve significance (p=0.065). These findings demonstrate that the SH&C provides a stabilizing barrier effect, but only in configurations when it wraps directly anterior to the humeral head. Thus SH&C loading is likely critical to in-vitro simulation due to its effect on joint stability and kinematics.
Journal of biomechanics 03/2011; 44(6):1192-5. · 2.66 Impact Factor
