The deltoid ligament can tear in association with an ankle fracture or a syndesmotic injury or independently. Previous biomechanical research has shown that the optimal surgical treatment method for an anterior deltoid tear is repair with tibiocalcaneal augmentation. However, tibiocalcaneal augmentation is technically challenging to perform, as there is a risk of damage to neurovascular structures in the medial ankle. To determine if tibiotalar augmentation is sufficient to stabilize the ankle in the setting of a deltoid tear. Controlled laboratory study. A total of 10 cadaveric ankles were mounted to a 6 degrees of freedom robotic arm. Each specimen underwent biomechanical testing in 9 states: (1) intact, (2) anterior deltoid cut, (3) anterior deltoid repair, (4) anterior deltoid repair + tibiotalar augmentation, (5) anterior deltoid repair + tibiotalar augmentation + tibiocalcaneal augmentation, (6) posterior deltoid cut, (7) removal of tibiocalcaneal augmentation, (8) removal of tibiotalar augmentation, and (9) removal of anterior deltoid repair. Additionally, 6 tests were run under a 5-N·m load: (1) eversion at neutral, (2) eversion at 25° of plantarflexion, (3) external rotation at neutral, (4) external rotation at 25° of plantarflexion, (5) plantarflexion, and (6) dorsiflexion. Anterior and complete tears significantly increased ankle laxity compared with the intact state on all tests (+5.6° and +12.0° in eversion at 25° of plantarflexion, respectively; P < .0001). Anterior repair restored external rotation to the intact state for both anterior and complete tears, but it remained significantly more lax in eversion at 25° of plantarflexion (+2.9° [P = .0007] and +5.0° [P < .001], respectively). Tibiotalar augmentation showed no significant improvement, while tibiocalcaneal augmentation restored eversion stability to the intact state. No significant reductions in range of motion were found for any surgical state compared with the intact state. Tibiotalar augmentation did not restore eversion stability to the intact state, but tibiocalcaneal augmentation restored eversion stability to the intact state for both anterior and complete tears. While this surgical technique may be technically challenging, it has a strong stabilizing effect on the ankle joint. Future research is necessary to further improve the safety and simplicity of this technique. Clinicians may consider adding tibiocalcaneal suture tape augmentation to deltoid ligament repair to improve eversion stability.

Objectives: Posterolateral corner (PLC) injuries intricately damage vital knee stabilizers. Both fibular and tibial-based reconstruction techniques are used and are classically described with use of interference screw fixation of the graft at the femur. However, adjustable loop buttons may conserve more bone stock, reduce the risk of tunnel convergence in the setting of multiligament reconstruction, and provide more versatile and reproducible tensioning ability compared to interference screws. Further, tape-reinforced graft suturing has been shown to have favorable biomechanical properties over traditional graft suturing techniques. There is no study comparing interference screw fixation to adjustable loop buttons in the context of tape-reinforced grafts in PLC reconstruction. Therefore, the purpose of this study is to biomechanically compare adjustable loop button fixation with interference screws for fibular collateral ligament and popliteal tendon fixation to the femur for PLC reconstruction. We hypothesize there will be no difference in varus or external rotation laxity between the two methods of fixation. Methods: The biomechanical study was conducted on 10 cadaveric knee specimens in a non-destructive repeated measures sequence using a 6-degree of freedom robotic arm (Fig. 1), under four conditions: (1) Native (2) PLC reconstruction with adjustable-loop suspensory button fixation, (3) PLC reconstruction interference screw fixation, and (4) PLC injured state. Reconstruction was performed using a fibular based technique as described by Arciero et al. FCL and popliteal tendon limbs were tensioned independently with 100N of force. The FCL was tensioned with the knee at 30° of flexion and 3 N∙m of valgus torque in neutral rotation. The popliteal tendon limb was tensioned at 60° of knee flexion with neutral rotation. Biomechanical evaluation consisted of a 5-N∙m external rotation test and a 10-N∙m varus test, performed at 0°, 30°, 60° and 90° of flexion. Results: All differences are presented in the order of 0°, 30°, 60° and 90° of flexion. Cutting the PLC significantly increased external rotation laxity (Fig. 2) (+3.8°, +9.7°, +9.9°, +7.6, all P<0.001) and varus laxity (Fig. 3) (+1.7°, +4.5°, +3.7°, all p<0.001, no significant difference at 90° of flexion) with respect to native. PLC reconstruction with suspensory fixation significantly over constrained external rotation (Fig. 2) (-3.5° P=0.002, -4.3° P<0.001, -4.1° P=0.002, -3.1° P=0.039) and varus (Fig. 3) (-1.5°, -2.1°, -2.4°, -2.1°, all P<0.001). PLC Reconstruction with interference screws similarly over constrained external rotation (Fig. 2) (-4.3°, -5.5°, -5.4°, -4.5°, all P<0.001) and varus (Fig. 3) (-1.8°, -2.5°, -2.9°, -2.8°, all P<0.001). There was no significant difference found between the suspensory fixation and the interference screw fixation in any test. Conclusions: Both reconstruction techniques restored the stability in external rotation and varus stress. No significant differences were found between the two fixation methods, validating both adjustable-loop suspensory buttons and interference screws as viable options for femoral fixation in the setting of PLC reconstruction. However, both methods over-constrained the knee in ER and Varus. This may be due to the increased stiffness of the tape-reinforced graft suturing, or over-tensioning of the grafts during fixation. The study tests a physiologic load but is limited since the specimen is not cyclically loaded or loaded to failure. This study evaluates and compares two PLC reconstruction techniques and their impact on knee stability. These findings provide quantifiable data to aid surgeons in making evidence-based, patient-specific decisions regarding appropriate PLCR technique. Biomechanically, the adjustable-loop suspensory fixation and the interference screw behave very similarly at time zero. Given this, surgeons may select an implant based on their comfort, training and/or patient specific needs. Further research is necessary to determine which implant performs the best in a clinical setting.

Background: A labral injury contributes to glenohumeral instability. The Anterior Labral Circumferential Onlay Technique (ALCOT) reconstructs the labrum using the long head of the biceps tendon. Hypothesis: The ALCOT would restore glenohumeral joint stability in a cadaveric model without glenoid bone loss (1) comparable to the native state and (2) comparable to the Latarjet procedure. Study Design: Controlled laboratory study. Methods: A total of 10 fresh-frozen cadaveric shoulders were tested using a 6 degrees of freedom robotic arm in 5 consecutive states: (1) native, (2) capsular repair, (3) labral tear, (4) ALCOT, and (5) Latarjet procedure. Biomechanical testing consisted of 80 N of anteroinferior force and 50 N of compression in 90° of humerothoracic abduction. Lateral displacement of the humeral head and the force ratio during a dislocation were measured. Results: The mean lateral translation of the humeral head during a dislocation in the native state was 6.5 ± 2.2 mm and decreased to 5.4 ± 2.4 mm in the labral tear state ( P < .001). The mean lateral translation of the humeral head was restored to 6.4 ± 2.2 mm ( P > .99) with the ALCOT, showing no difference from the native state. The Latarjet procedure restored the mean force ratio during a dislocation to 1.3 ± 0.6 but failed to restore lateral translation, with a value of 5.6 ± 2.8 mm ( P = .003 vs native; P = .94 vs labral tear). The mean force ratio was 1.8 ± 0.1 in the native state, decreased to 1.1 ± 0.4 in the labral tear state, and was 1.4 ± 0.4 ( P < .27) with the ALCOT, showing no difference from the native state. Conclusion: The ALCOT is a novel technique for labral reconstruction that may have a role in the treatment of anterior glenohumeral instability in the setting of a deficient labrum without bone loss. In this study, the ALCOT restored the force ratio and lateral translation of the humeral head compared to the native state. The Latarjet procedure restored the force ratio but not lateral translation of the humeral head compared to the native state. Clinical Relevance: This study proposes and biomechanically validates the ALCOT as a surgical technique for labral reconstruction that may have a role in treating patients with chronic anterior shoulder instability in the setting of a deficient labrum.

Objectives: The deltoid ligament can tear in association with ankle fractures, syndesmotic injuries, or independently. In previous biomechanical research. the optimal surgical treatment for an anterior deltoid tear has been shown to be a repair with a tibiocalcaneal augmentation, with no additional benefit of a tibiotalar augmentation. However, tibiocalcaneal augmentation is technically challenging to perform as there is a risk of damage to neurovascular structures in the medial ankle. Therefore, by testing tibiotalar augmentation first, the purpose of this study is to determine if this simpler surgery is sufficient to stabilize the ankle in the setting of an anterior and complete deltoid tear. Additionally, concerns over loss of range of motion due to overconstraint in plantarflexion and dorsiflexion have been raised with ligament augmentation surgery. The secondary purpose of this study is to determine if these concerns are warranted. We hypothesize that sectioning the deltoid ligaments will substantially heighten ankle laxity in eversion and external rotation, anterior deltoid repair will mitigate laxity but not restore native stability, and incorporation of tibiotalar and tibiocalcaneal augmentations will further improve stability. We hypothesize that none of the surgical treatments will introduce loss of range of motion due to overconstraint. Methods: Ten cadaveric ankles were mounted on a 6° of freedom robotic arm. Each specimen underwent biomechanical testing in 9 successive states: 1) Intact, 2) Anterior deltoid cut, 3) Anterior deltoid repair, 4) Repair + tibiotalar augmentation, 5) Repair + tibiotalar + tibiocalcaneal augmentation, 6) Posterior deltoid cut, leaving anterior repair and augmentations intact, 7) Removal of the tibiocalcaneal augmentation, 8) Removal of the tibiotalar augmentation, and 9) Removal of the anterior repair (complete cut state). This study design allowed the comparison of the 3 treatment options separately in the setting of an anterior tear and a complete tear. Testing consisted of 6 range of motion tests, measuring how much rotation occurred under a 5-Nm load: 1) Eversion at neutral, 2) Eversion at 25° plantarflexion, 3) External rotation at neutral, 4) External rotation at 25° plantarflexion, 5) Plantarflexion, and 6) Dorsiflexion. One-factor random intercepts linear mixed effects statistical models were created to run an analysis of variance followed by post-hoc pairwise comparisons between testing states in the setting of an anterior tear and a complete tear. Results: The results from the anterior cut analysis are shown in Figures 1 and 2, and the results from the complete cut analysis are shown in Figures 3 and 4. The anterior tear significantly increased ankle laxity compared to native in all tests: external rotation at neutral (+2.8°, p<0.0001), at 25° (+2.4°, p=0.0002), eversion at neutral (+2.1°, p=0.0019), at 25° (+5.6°, p<0.0001). The complete tear significantly increased ankle laxity compared to native in all tests (all p<0.0001): external rotation at neutral (+6.9°), at 25° (+7.2°), eversion at neutral (11.6°), at 25° (+12.0°). In the setting of the anterior tear, an anterior repair restored native ER at neutral and 25° and eversion at neutral but remained significantly more lax at 25° plantarflexion (+2.9°, p=0.0007). In the setting of a complete tear, the anterior repair failed to restore native stability in any test. The tibiotalar augmentation showed no significant differences from the anterior repair in any test either in the setting of an anterior or complete deltoid tear. The addition of the tibiocalcaneal augmentation restored native external rotation and eversion stability at neutral and 25° plantarflexion, both in the setting of an anterior tear and a complete tear, showing significant improvements over the tibiotalar augmentation. No significant reductions in range of motion were found for any surgical state in any test compared to native. Conclusions: The tibiotalar augmentation showed no significant improvement over a suture repair in the setting of an anterior or complete deltoid tear. The addition of a tibiocalcaneal augmentation showed significant improvement over the tibiotalar augmentation, restoring native stability in eversion and external rotation in the anterior tear and complete tear models. When these augmentations were tested in the reverse order, previous research showed that the tibiocalcaneal augmentation demonstrated significant improvement over the anterior repair, and the addition of tibiotalar augmentation demonstrated no significant change. Therefore, the optimal treatment in the setting of an anterior or complete deltoid tear was a suture repair plus a tibiocalcaneal augmentation. While this surgery may be technically challenging, it has a strong stabilizing effect on the ankle joint, and future research is necessary to further improve the safety and simplicity of this technique. Nonoperative management of deltoid ligament tears may lead to persistent changes in ankle biomechanics and poor patient outcomes. Deltoid ligament repair with augmentation might hasten rehabilitation, reduce stiffness, and facilitate earlier resumption of preinjury activity. Figure 1 Figure 2 Figure 3 Figure 4

Background. Irreparable supraspinatus (SSP) tears represent a persistent clinical challenge. The middle trapezius transfer (MTT) offers a novel dynamic option but current biomechanical evidence regarding its efficacy remains limited. Purpose. This study aimed to assess the effects of MTT on superior humeral head translation and subacromial pressure in the setting of irreparable SSP tears. Methods. In this study 10 cadaveric shoulders underwent biomechanical testing using a 6-degrees of freedom robotic arm and 3 conditions were evaluated: intact, irreparable SSP tear and MTT. Results. The MTT significantly reduced superior humeral head translation and subacromial pressure compared to the irreparable tear state although native conditions were not fully restored. Discussion. The biomechanical findings suggest that MTT has the potential to partially restore physiological shoulder kinematics, indicating its promise as a clinically relevant treatment option for irreparable SSP tears.

Background:The posterior oblique ligament (POL) is the largest structure of the posteromedial knee that is at risk of injury in conjunction with the medial collateral ligament (MCL). Its quantitative anatomy, biomechanical strength, and radiographic location have not been assessed in a single investigation. Purpose:To evaluate the 3-dimensional and radiographic anatomy of the posteromedial knee and the biomechanical strength of the POL. Study Design:Descriptive laboratory study. Methods:Ten nonpaired fresh-frozen cadaveric knees were dissected and medial structures were elevated off bone, leaving the POL. The anatomic locations of the related structures were recorded with a 3-dimensional coordinate measuring machine. Anteroposterior and lateral radiographs were taken with radiopaque pins inserted into the pertinent landmarks, and the distances between the collected structures were calculated. Each knee was then mounted to a dynamic tensile testing machine, and pull-to-failure testing was performed to record the ultimate tensile strength, stiffness, and failure mechanism. Results:The POL femoral attachment was a mean of 15.4 mm (95% CI, 13.9-16.8 mm) posterior and 6.6 mm (95% CI, 4.4-8.8 mm) proximal to the medial epicondyle. The tibial POL attachment center was a mean of 21.4 mm (95% CI, 18.1-24.6 mm) posterior and 2.2 mm (95% CI, 0.8-3.6 mm) distal to the center of the deep MCL tibial attachment and a mean of 28.6 mm (95% CI, 24.4-32.8 mm) posterior and 41.9 mm (95% CI, 36.8-47.0 mm) proximal to the center of the superficial MCL tibial attachment. On lateral radiographs, the femoral POL was a mean of 17.56 mm (95% CI, 14.83-21.95 mm) distal to the adductor tubercle and 17.32 mm (95% CI, 14.6-21.7 mm) posterosuperior to the medial epicondyle. On the tibial side, the center of the POL attachment was a mean of 4.97 mm (95% CI, 3.85-6.79 mm) distal to the joint line on anteroposterior radiographs and 6.34 mm (95% CI, 5.01-8.48 mm) distal to the tibial joint line on lateral radiographs, at the far posterior tibial aspect. The biomechanical pull-to-failure demonstrated a mean ultimate tensile strength of 225.2 ± 71.0 N and a mean stiffness of 32.2 ± 13.1 N. Conclusion:The anatomic and radiographic locations of the POL and its biomechanical properties were successfully recorded. Clinical Relevance:This information is useful to better understand POL anatomy and biomechanical properties as well as to clinically address an injury with repair or reconstruction.

Objectives: The standard of care for treating anterior shoulder instability caused by a labral detachment is the Bankart repair. In the case of a deficient labrum with significant antero-inferior glenoid bone loss, the latarjet technique can be used instead. However, when the labrum is deficient and the bone loss is minimal, labral reconstruction has been recently proposed as an alternative. A new technique called Anterior Labral Circumferential Onlay Technique (ALCOT) was developed, which reconstructs the labrum using the long head of the biceps tendon. The purpose of this study was to biomechanically evaluate the efficacy of the ALCOT to stabilize the shoulder joint against anterior dislocation in the setting of a deficient labrum with no glenoid bone loss. Methods: Ten fresh-frozen cadaveric shoulders were tested in 5 consecutive states using a 6-degrees-of-freedom robotic arm: (1) Native, (2) Capsular Repair, (3) Labral Tear (4) ALCOT (5) Latarjet. The capsule repair state used as a control because the joint capsule needed to be opened and repaired to perform the other states. This state ensured that any differences were due to the surgical procedure being tested, and not because of any iatrogenic damage to the capsule. The Labral Tear was performed by detaching the labrum from the glenoid between 3-6 o’clock and removing it from the joint. For the ALCOT, the biceps tendon was shortened at the distal portion and pulled into the joint. Three knotless all suture anchors were placed at 3, 4:30 and 6 o’clock position on the glenoid rim, and the biceps tendon was secured to the suture anchors using mattress stitches. For the latarjet, a coracoid autograft was cut 25 mm from the tip, keeping the conjoint tendons intact, and secured to the glenoid using two screws. In the native state, each specimen underwent an initial test to determine the appropriate amount of anterior and inferior displacement for future tests. In this test, a 50N compressive load was maintained while an 80N force was applied in the sagittal plane at a 45° angle between the anterior and inferior axes. The corresponding anterior and inferior displacements were recorded. Then, in each state including native, a dislocation test was performed. In this test, a 50N compressive load was maintained while the joint was driven in position control to the previously recorded positions on the anterior and inferior axes. The amount of force needed to displace the shoulder and the lateral displacement of the humeral head were recorded throughout the motion. Higher lateral translation was considered more stable, because it corresponded to a larger obstacle to overcome during the dislocation. To account for variation in the amount of compressive load during the test, antero-inferior dislocation load was normalized by compressive load to create a force ratio. This metric accounts for the fact that the amount of force required to dislocate depends on the amount of stabilizing compressive load provided by the robot in vitro, and by muscle tension in vivo. Results: No significant differences were found between the native and capsular repair states. Compared to native, the labral tear significantly decreased the lateral translation of the humeral head during dislocation from 6.5mm to 5.4mm (p<0.001) and decreased the force ratio from 1.8 to 1.1 (p=0.002), corresponding to a decrease from 90N to 55N at 50N of compressive load. The ALCOT restored these values to 6.4 mm and 1.4, respectively, showing no significant difference from native. The latarjet restored the force ratio to 1.3 (not significant from native) but failed to restore lateral translation with a value of 5.6 mm (p=0.003 from Native, not significantly different from the labral tear). The force ratio is shown on figure 1 and the lateral translation is shown on figure 2. Conclusions: The ALCOT is a novel technique for labral reconstruction that can be considered as a treatment option for anterior instability in the setting of a deficient labrum. Compared to the latarjet technique, the ALCOT involves less morbidity and represents a more anatomic glenoid surface by replacing the labrum without changing the bony morphology. In this study, the ALCOT also showed superior stabilization by restoring native force ratio and lateral humerus translation. Further research is necessary to clinically validate this technique, and possibly to expand indications to small degrees of glenoid bone loss.

Background: Transsyndesmotic fixation with suture buttons (SBs), posterior malleolar fixation with screws, and anterior inferior tibiofibular ligament (AITFL) augmentation using suture tape (ST) have all been suggested as potential treatments in the setting of a posterior malleolar fracture (PMF). However, there is no consensus on the optimal treatment for PMFs. Purpose: To determine which combination of (1) transsyndesmotic SBs, (2) posterior malleolar screws, and (3) AITFL augmentation using ST best restored native tibiofibular and ankle joint kinematics after 25% and 50% PMF. Study Design: Controlled laboratory study. Methods: Twenty cadaveric lower-leg specimens were divided into 2 groups (25% or 50% PMF) and underwent biomechanical testing using a 6 degrees of freedom robotic arm in 7 states: intact, syndesmosis injury with PMF, transsyndesmotic SBs, transsyndesmotic SBs + AITFL augmentation, transsyndesmotic SBs + AITFL augmentation + posterior malleolar screws, posterior malleolar screws + AITFL augmentation, and posterior malleolar screws. Four biomechanical tests were performed at neutral and 30° of plantarflexion: external rotation, internal rotation, posterior drawer, and lateral drawer. The position of the tibia, fibula, and talus were recorded using a 5-camera motion capture system. Results: With external rotation, posterior malleolar screws with AITFL augmentation resulted in best stability of the fibula and ankle joint. With internal rotation, all repairs that included posterior malleolar screws stabilized the fibula and ankle joint. Posterior and lateral drawer resulted in only small differences between the intact and injured states. No differences were found in the efficacy of treatments between 25% and 50% PMFs. Conclusion: Posterior malleolar screws resulted in higher syndesmotic stability when compared with transsyndesmotic SBs. AITFL augmentation provided additional external rotational stability when combined with posterior malleolar screws. Transsyndesmotic SBs did not provide any additional stability and tended to translate the fibula medially. Clinical Relevance: Posterior malleolar fixation with AITFL augmentation using ST may be the preferred surgical method when treating patients with acute ankle injury involving an unstable syndesmosis and a PMF ≥25%.

The purpose of this study was to compare the biomechanical effect of in-situ repair of posterior lateral meniscal root (PLMR) tear with segmental meniscal loss, with and without meniscofemoral ligament (MFL) imbrication, on anterior cruciate ligament (ACL) graft force and knee joint kinematics. Ten fresh-frozen cadaveric knee specimens underwent kinematic evaluation in five states: 1) Native, 2) ACLR, 3) Segmental PLMR loss, 4) In-situ PLMR repair, and 5) MFL augmentation. Kinematic evaluation consisted of five tests, each performed at full extension and at 30° of flexion: 1) Anterior drawer, 2) Internal Rotation, 3) External Rotation, 4) Varus, and 5) Valgus. Additionally, a simulated pivot shift test was performed. Knee kinematics and ACL graft force were measured. PLMR tear did not significantly increase ACL graft force in any test. However, PLMR repair significantly reduced ACL graft force compared to the ACLR alone (over constraint -26.6 N, p = 0.001). PLMR tear significantly increased ATT during the pivot shift test (+ 2.7 mm, p = 0.0001), and PLMR repair restored native laxity. MFL augmentation did not improve the mechanics. In-situ PLMR repair eliminated pivot shift laxity through ATT and reduced force on the ACL graft, indicating that this procedure may be ACL graft-protective. MFL augmentation was not shown to have any effect on graft force or knee kinematics and untreated PLMR tears may place an ACL graft at higher risk. This study suggests concomitant repair to minimize additional forces on the ACL graft.

BACKGROUND:Deltoid ligament injuries occur in isolation as well as with ankle fractures and other ligament injuries. Both operative treatment and nonoperative treatment are used, but debate on optimal treatment continues. Likewise, the best method of surgical repair of the deltoid ligament remains unclear.PURPOSE:To determine the biomechanical role of native anterior and posterior components of the deltoid ligament in ankle stability and to determine the efficacy of simple suture versus augmented repair.STUDY DESIGN:Controlled laboratory study.METHODS:Ten cadaveric ankles (mean age, 51 years; age range, 34-64 years; all male specimens) were mounted on a 6 degrees of freedom robotic arm. Each specimen underwent biomechanical testing in 8 states: (1) intact, (2) anterior deltoid cut, (3) anterior repair, (4) tibiocalcaneal augmentation, (5) deep anterior tibiotalar augmentation, (6) posterior deltoid cut, (7) posterior repair, and (8) complete deltoid cut. Testing consisted of anterior drawer, eversion, and external rotation (ER), each performed at neutral and 25° of plantarflexion. A 1-factor, random-intercepts, linear mixed-effect model was created, and all pairwise comparisons were made between testing states.RESULTS:Cutting the anterior deltoid introduced ER (+2.1°; P = .009) and eversion laxity (+6.2° of eversion; P < .001) at 25 degrees of plantarflexion. Anterior deltoid repair restored native ER but not eversion. Tibiocalcaneal augmentation reduced eversion laxity, but tibiotalar augmentation provided no additional benefit. The posterior deltoid tear showed no increase in laxity. Complete tear introduced significant anterior translation, ER, and eversion laxity (+7.6 mm of anterior translation, +13.8° ER and +33.6° of eversion; P < .001).CONCLUSION:A complete deltoid tear caused severe instability of the ankle joint. Augmented anterior repair was sufficient to stabilize the complete tear, and no additional benefit was provided by posterior repair. For isolated anterior tear, repair with tibiocalcaneal augmentation was the optimal treatment.CLINICAL RELEVANCE:Deltoid repair with augmentation may reduce or avoid the need for prolonged postoperative immobilization and encourage accelerated rehabilitation, preventing stiffness and promoting earlier return to preinjury activity.

Background: In the Latarjet procedure, the ideal placement of the coracoid graft in the medial-lateral position is flush with the anterior glenoid rim. However, the ideal position of the graft in the superior-inferior position (sagittal plane) for restoring glenohumeral joint stability is still controversial. Purpose: To compare coracoid graft clockface positions between the traditional 3 to 5 o'clock and a more inferior (for the right shoulder) 4 to 6 o'clock with regard to glenohumeral joint stability in the Latarjet procedure. Study Design: Controlled laboratory study. Methods: A total of 10 fresh-frozen cadaveric shoulders were tested in a dynamic, custom-built robotic shoulder model. Each shoulder was loaded with a 50-N compressive load while an 80-N force was applied in the anteroinferior axes at 90° of abduction and 60° of shoulder external rotation. Four conditions were tested: (1) intact, (2) 6-mm glenoid bone loss (GBL), (3) Latarjet procedure fixed at 3- to 5-o’clock position, and (4) Latarjet procedure fixed at 4- to 6-o’clock position. The stability ratio (SR) and degree of lateral humeral displacement (LHD) were recorded. A 1-factor random-intercepts linear mixed-effects model and Tukey method were used for statistical analysis. Results: Compared with the intact state (1.77 ± 0.11), the SR was significantly lower after creating a 6-mm GBL (1.14 ± 0.61, P = .009), with no significant difference in SR after Latarjet 3 to 5 o'clock (1.51 ± 0.70, P = .51) or 4 to 6 o'clock (1.55 ± 0.68, P = .52). Compared with the intact state (6.48 ± 2.24 mm), LHD decreased significantly after GBL (3.16 ± 1.56 mm, P < .001) and Latarjet 4 to 6 o'clock (5.48 ± 3.39 mm, P < .001). Displacement decreased significantly after Latarjet 3 to 5 o'clock (4.78 ± 2.50 mm, P = .04) compared with the intact state but not after Latarjet 4 to 6 o'clock ( P = .71). Conclusion: The Latarjet procedure in both coracoid graft positions (3-5 and 4-6 o’clock) restored the SR to the values measured in the intact state. A more inferior graft position (fixed at 4-6 o’clock) may improve shoulder biomechanics, but additional work is needed to establish clinical relevance. Clinical Relevance: An inferior coracoid graft fixation, the 4- to 6-o’clock position, may benefit in restoring normal shoulder biomechanics after the Latarjet procedure.

Objectives: The structures of the posteromedial knee are important for coronal and rotational stability. These can be injured along with the medial collateral ligament (MCL) during traumatic or sporting activities. The posterior oblique ligament (POL) is largest and best-known structure at the posteromedial knee at risk of injury. When surgical reconstruction is needed, the location and positioning of this reconstruction is often grouped together with the medial collateral ligament, despite the specific biomechanical role of and the much larger anatomic area covered by the various structures of the posteromedial knee. The POL provides a complex load sharing interplay with the MCL, such that these ligaments both contribute to resist the combination of valgus and rotational strains. As such, the POL is an important structure that contributes to the stability of the medial knee, and severe injuries may benefit from a separate procedure to directly address the ligament. The purpose of this study was to evaluate the anatomy of the posteromedial knee as well as the radiographic locations and biomechanical strengths of the POL. Methods: 10 nonpaired fresh cadaveric knees were dissected and the medial structures were elevated off bone, except for the POL. The anatomic locations were noted and recorded with a robotic coordinate measuring device to establish structure location, distances, and attachment areas for the superficial MCL, adductor tubercle, medial epicondyle, meniscofemoral ligament, tibiofemoral ligament, semimembranosus and the POL. For the radiographic analysis, radiopaque T-pins were placed in the POL attachment sites, as well as other clinically relevant and bony landmarks. True anteroposterior (AP) and lateral radiographs were taken with fluoroscopy. Digital software was utilized to measure the distances from these anatomic points to the center of the attachment of the POL. Biomechanically, the specimens were loaded onto a computerized actuator, and all soft tissues connecting the tibia and the femur were resected except for the POL. A pull-to-failure test was completed and the ultimate tensile strength and location of the failure was recorded. Results: On average, the POL attachment on the femur is 15.4mm posterior and 6.6mm superior to the medial epicondyle. On the tibia, the POL attachment center is 21.4mm posterior and 2.2mm inferior to the center of the meniscotibial ligament, and 28.6mm posterior and 41.9mm superior to the center of the superficial MCL tibial attachment. On radiographic exam, the femoral POL was 17.6mm distal to the adductor tubercle, and 17.3mm posterosuperior to the medial epicondyle on the lateral radiograph. On the tibial side, the center of the POL attachment is 5.0mm distal to the joint line on the AP radiograph and 6.3mm distal to the tibial joint line on the lateral, at the far posterior aspect of the tibia. The biomechanical pull-to-failure demonstrated an average ultimate tensile strength of 225.2N ± 71.0N. Conclusions: This study successfully localized the medial and posteromedial knee structures, establishing their anatomic location, the radiographic location of the POL relative to clinically relevant structures, and established the pull-to-failure ultimate tensile strength. This provides good clinical information for location and type of graft that can help anatomically reconstruct the central arm of the POL.

Objectives: Lateral extra-articular tenodesis (LET) is being performed more frequently with anterior cruciate ligament reconstruction (ACLR) to decrease graft failure rates. Posterior tibial slope (PTS) affects ACL graft failure rates.2 The impact of LET plus ACLR on tibial motion and graft forces with increasing PTS has not been elucidated. We hypothesized LET will decrease anterior tibial translation (ATT), tibial rotation, and ACL graft force versus ACLR alone with increasing tibial slope throughout knee range of motion. Methods: Twelve cadaveric knees (40.5 mean age, all female) were tested in four conditions (intact, ACL cut, ACLR, ACLR + LET) with varying PTS (5°, 10°, 15°, 20°) at three flexion angles (0°, 30°, 60°). Specimens were mounted to a load frame which applied a 500-N axial load with 1 Nm of internal rotation (IR) torque (Figure 1). The amount of tibial translation, IR, and graft forces were measured. Results: Increasing PTS revealed a linear and statistically significant increase in graft force at all flexion angles. LET reduced graft force by 8.3% (6N) compared to ACLR alone at 30° of flexion. At the same position, slope-correcting osteotomy reduced graft force by 17-22% per 5° of slope correction, with a 46% reduction seen from 20° to 5°slope correction. For ATT, ACLR returned tibial translation to pre-injury levels, as did ACLR + LET at all flexion angles, except full extension where ACLR + LET over-reduced ATT by 2.47mm (p<0.05). Conclusions: Increased PTS was confirmed to increase graft forces linearly. Additionally, while the ACLR + LET reduced graft force compared to ACLR alone, slope correcting osteotomies are a more powerful method to minimize graft force. No other clinically significant differences were noted between ACLR with or without LET in regards to graft force, ATT, or IR. Many authors have proposed LET in the setting of ACLR, revision surgery, hyperlaxity, high grade pivot shift and elevated PTS, but the indications remain unclear. The biomechanical performance of LET plus ACLR at varying PTSs may impact daily practice and provide clarity on these indications.

Background: Existing biomechanical studies of posterior glenoid bone loss and labral pathology are limited by their use of anterior instability models, which differ in both orientation and morphology and have been performed in only a single, neutral arm position. Purpose: To evaluate the biomechanical effectiveness of a posterior labral repair in the setting of a clinically relevant posterior bone loss model in various at-risk arm positions. Study Design: Controlled laboratory study. Methods: Ten fresh-frozen cadaveric shoulders were tested in 7 consecutive states using a 6 degrees of freedom robotic arm: (1) native, (2) posterior labral tear (6-9 o’clock), (3) posterior labral repair, (4) mean posterior glenoid bone loss (7%) with labral tear, (5) mean posterior glenoid bone loss with labral repair, (6) large posterior glenoid bone loss (28%) with labral tear, and (7) large posterior glenoid bone loss with labral repair. Bone loss was created using 3-dimensional printed computed tomography model templates. Biomechanical testing consisted of 75 N of posterior-inferior force and 75 N of compression at 60° and 90° of flexion and scaption. Posterior-inferior translation, lateral translation, and peak dislocation force were measured for each condition. Results: Labral repair significantly increased dislocation force independent of bone loss state between 10.1 and 14.8 N depending on arm position. Dislocation force significantly decreased between no bone loss and small bone loss (11.9-13.5 N), small bone loss and large bone loss (9.4-14.3 N), and no bone loss and large bone loss (21.2-26.5 N). Labral repair significantly decreased posterior-inferior translation compared with labral tear states by a range of 1.0 to 2.3 mm. In the native state, the shoulder was most unstable in 60° of scaption, with 29.9 ± 6.1-mm posterior-inferior translation. Conclusion: Posterior labral repair improved stability of the glenohumeral joint, and even in smaller to medium amounts of posterior glenoid bone loss the glenohumeral stability was maintained with labral repair in this cadaveric model. However, a labral repair with large bone loss could not improve stability to the native state. Clinical Relevance: This study shows that larger amounts of posterior glenoid bone loss (>25%) may require bony augmentation for adequate stability.

Background: The most reliable suture technique for capsular closure after a capsulotomy remains unknown. Purpose: To determine which suture technique best restores native stability after a 5-cm interportal capsulotomy. Study Design: Controlled laboratory study. Methods: Ten human cadaveric hip specimens were tested using a 6-degrees-of-freedom robotic arm in 7 states: intact, capsular laxity, 5-cm capsulotomy, standard suture, shoelace, double shoelace, and Quebec City slider (QCS). Rotational range of motion (ROM) was measured across 9 tests: flexion, extension, abduction, abduction at 45° of flexion, adduction, external rotation, internal rotation, anterior impingement, and log roll. Distraction (ie, femoral head translation [FHT]) was measured across a range of flexion and abduction angles. Results: When compared with the native state, the 5-cm capsulotomy state showed the largest laxity increases on all tests, specifically in external rotation ROM (+13.4°), extension ROM (+11.5°), and distraction FHT (+4.5 mm) ( P < .001 for all). The standard suture technique was not significantly different from the 5-cm capsulotomy on any test and demonstrated significantly more flexion ROM than the double shoelace suture (+1.41°; P = .049) and more extension ROM (+5.51°; P = .014) and external rotation ROM (+6.03°; P = .021) than the QCS. The standard suture also resulted in significantly higher distraction FHT as compared with the shoelace suture (+1.0 mm; P = .005), double shoelace suture (+1.4 mm; P < .001), and QCS (+1.1 mm; P = .003). The shoelace, double shoelace, and QCS techniques significantly reduced hip laxity when compared with the 5-cm capsulotomy state, specifically in external rotation ROM (respectively, –8.1°, –7.8°, and –10.2°), extension ROM (–6.3°, –7.3°, and –8.1°), and distraction FHT (–1.8, –2.2, and –1.9 mm) ( P ≤ .003 for all). These 3 techniques restored native stability (no significant difference from intact) on some but not all tests, and no significant differences were observed among them on any test. Conclusion: Hip capsule closure with the standard suture technique did not prevent postoperative hip instability after a 5-cm capsulotomy, and 3 suture techniques were found to be preferable; however, none perfectly restored native stability at time zero. Clinical Relevance: The shoelace, double shoelace, and QCS suture techniques are recommended when closing the hip capsule.

Background: Although the risk of tibial tunnel convergence in the setting of multiligamentous reconstruction has been reported in the literature, the risk of tunnel convergence in the setting of posterior cruciate ligament (PCL), anterior cruciate ligament (ACL) reconstruction and medial and lateral meniscus root repair has not been defined. Purpose: To examine the risk of tunnel convergence and to determine optimal tunnel placement for ACL and PCL reconstruction performed in conjunction with posterior medial and lateral meniscus root repairs on the anteromedial proximal tibia. Study Design: Descriptive laboratory study. Methods: Three-dimensional (3D) tibial models were created using computed tomography scans of 20 cadaveric specimens. After determining optimal tunnel entry and exit points for ACL and PCL reconstructions, and medial and lateral meniscus root reattachment to the anatomic footprints, we used image processing software to create root tunnels over the anteromedial tibia on the tibial models. ACL and PCL tunnels were kept constant. The meniscus root repair tunnels were then reoriented to match the angle of the ACL tunnel, making both tunnels parallel in the sagittal plane. Tunnel convergence risk was analyzed by identifying the shortest 3D distance between tunnel axes and subtracting the radius of each tunnel from this distance for single- and double-tunnel repair techniques in both case scenarios. Results: All specimens demonstrated convergence between the ACL and lateral meniscus root tunnels when the root tunnel’s entry was created proximal to the ACL tunnel’s entry for single- and double-tunnel techniques, but no convergence was seen between these tunnels using the parallel orientation in the sagittal plane. There were no cases of convergence between the ACL and medial meniscus root tunnels in any of the configurations. The greatest distance between the ACL and medial meniscus root tunnels was achieved using the single-tunnel technique in parallel orientation (12.1 ± 2.8 mm). There were no cases of convergence between the PCL and medial meniscus root tunnels in the original orientation; however, 2 of 20 specimens demonstrated convergence using the parallel orientation with the double-tunnel technique, and there were no cases of convergence using the single-tunnel technique. The PCL and lateral meniscus root tunnels did not demonstrate convergence in any configuration. Conclusion: There was a high risk of convergence between ACL and posterior meniscus root tunnels when all the tunnels were created on the anteromedial tibia. Reorienting meniscus root tunnels parallel to ACL tunnels may help reduce this risk. There is increased risk of tunnel convergence with root repairs in cases of bicruciate reconstructions, and therefore a double-tunnel root repair technique should be used with caution. Clinical Relevance: To avoid tibial tunnel convergence when performing ACL and PCL reconstruction with medial and lateral meniscus root repair, surgeons should reorient the meniscus root repair tunnels to be parallel on the sagittal plane to the ACL tunnel to decrease the risk of convergence. In cases of bicruciate ligament reconstruction, use of the double-tunnel technique requires caution to avoid convergence risk with the PCL tunnel.

Objectives: Trans-syndesmotic fixation with suture buttons, posterior malleolar fixation (PMF) with screws and anterior inferior tibiofibular ligament (AITFL) augmentation with suture tape have all been suggested as potential treatments in the setting of a malleolar fracture. However, there is no consensus on the optimal treatment for small vs. large malleolar fractures. The purpose of this study was to determine which combination of: 1) posterior malleolar screw fixation, 2) syndesmotic fixation with suture button (SB), and 3) AITFL augmentation with suture tape (ST) best restored native tibio-fibular and ankle joint kinematics following a small and large posterior malleolar fracture. Methods: Twenty fresh frozen cadaveric lower leg specimens were divided into two groups and underwent biomechanical testing using a 6-degrees-of-freedom robotic arm in 7 states: 1) Native, 2) Syndesmosis Injury + Malleolar Fracture (Group 1: small fracture, Group 2: large fracture) 3) Screw fixation, 4) Screw + Suture Tape Augmentation, 5) Screw + Suture Tape Augmentation + Suture Button, 6) Suture Button + Suture Tape Augmentation, 7) Suture Button. Four biomechanical tests were performed at neutral and at 30 degrees of plantarflexion: 1) Internal Rotation, 2) External Rotation, 3) Lateral Drawer, 4) Posterior Drawer. The position of the tibia, fibula and talus were continuously recorded using a 5-camera motion capture system. Results: No differences were found in the efficacy of treatments between the small fracture and large fracture groups. In the external rotation test, screws with ST augmentation resulted in best stability of the fibula and ankle joint. In the internal rotation test, all repairs that included posterior malleolar screws stabilized the fibula and ankle. Posterior and lateral drawer of the foot resulted in only small differences between the intact and malleolar fracture states. Conclusions: Posterior malleolar fixation resulted in higher syndesmotic stability compared to trans-syndesmotic fixation with SBs. AITFL augmentation with ST provided additional external rotation stability when combined with screw fixation. Posterior malleolar screw fixation with AITFL augmentation using ST may be the preferred surgical method when treating patients with acute ankle injury involving an unstable syndesmosis injury and a posterior malleolar fragment. Figure 1. Sample of Syndesmosis Injury With Repair. Figure 2. Experimental Specimen Set-Up With the 6 D.O.F.Robotic Arm.

Background and Objectives: Intraoperative fluoroscopy can be used to increase the accuracy of the acetabular component positioning during total hip arthroplasty. However, given the three-dimensional nature of cup positioning, it can be difficult to accurately assess inclination and anteversion angles based on two-dimensional imaging. The purpose of this study is to validate a novel method for calculating the 3D orientation of the acetabular cup from 2D fluoroscopic imaging. Materials and Methods: An acetabular cup was implanted into a radio-opaque pelvis model in nine positions sequentially, and the inclination and anteversion angles were collected in each position using two methods: (1) a coordinate measurement machine (CMM) was used to establish a digitalized anatomical coordinate frame based on pelvic landmarks of the cadaveric specimen, and the 3D position of the cup was then expressed with respect to the anatomical planes; (2) AP radiographic images were collected, and a mathematical formula was utilized to calculate the 3D inclination and anteversion based on the 2D images. The results of each method were compared, and interrater and intrarater reliably of the 2D method were calculated. Results: Interrater reliability was excellent, with an interclass correlation coefficient (ICC) of 0.988 (95% CI 0.975–0.994) for anteversion and 0.997 (95% CI 0.991–0.999) for inclination, as was intrarater reliability, with an ICC of 0.995 (95% CI 0.985–0.998) for anteversion and 0.998 (95% CI 0.994–0.999) for inclination. Intermethod accuracy was excellent with an ICC of 0.986 (95% CI: 0.972–0.993) for anteversion and 0.993 (95% CI: 0.989–0.995) for inclination. The Bland–Altman limit of agreement, which represents the error between the 2D and 3D methods, was found to range between 2 to 5 degrees. Conclusions: This data validates the proposed methodology to calculate 3D anteversion and inclination angles based on 2D fluoroscopic images to within five degrees. This method can be utilized to improve acetabular component placing intraoperatively and to check component placement postoperatively.