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Purpose: To evaluate and compare two adjustable femoral cortical suspensory fixation devices used for anterior cruciate ligament reconstruction through a novel, direct computed tomography (CT) analysis metric and biomechanical laxity testing in a matched cadaveric human knee study., Methods: Anterior cruciate ligament reconstructions with bovine tendon grafts were performed using two adjustable femoral cortical suspensory fixation devices (RigidLoop Adjustable [DePuy Synthes Mitek, Raynham, MA] and TightRope [Arthrex, Naples, FL]) in 12 knees (6 matched pairs). A mechanical testing series was used to determine each knee's laxity in the intact condition. After reconstruction, each specimen was again tested for laxity and also imaged with CT. The laxity testing and CT imaging were then repeated after 1,000 cycles of anteroposterior loading on each knee to compare changes in laxity for the two fixation devices and to visualize changes in button-to-graft distance migration through a three-dimensional CT imaging method., Results: No significant differences were found between the two fixation groups' laxity measures after reconstruction (all P values ≥ .620) or after cycling (all P values ≥ .211) at any flexion angle. In addition, no significant differences were found between the two groups regarding button-to-graft distance migration (P = .773; mean, 0.61 ± 0.6 mm [95% confidence interval, -0.1 to 1.3 mm] in RigidLoop Adjustable group and 0.53 ± 0.6 mm [95% confidence interval, -0.1 to 1.2 mm] in TightRope group)., Conclusions: There were no significant differences between the two femoral cortical suspensory adjustable-loop devices regarding laxity outcomes or loop displacement as measured by button-to-graft distance migration., Clinical Relevance: Use of either of the adjustable-loop cortical suspensory devices in our analysis would appear to produce similar, acceptable laxity outcomes and minimal effects in terms of device-related loop displacement., (Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Recent epidemiologic studies highlight lateral talar process fractures as snowboarder's fracture or snowboarder's ankle. Snowboarding is the fastest growing sport worldwide, so lateral talar process fractures are increasing in frequency and mandating a more careful assessment of injury patterns, surrounding tissue involvement, and treatment strategy. In this study, we evaluated the effects of lateral talar process fracture on the footprints of 3 lateral stabilizing ligaments of the ankle and subtalar joint-the lateral talocalcaneal ligament (LTCL), the anterior talofibular ligament (ATFL), and the posterior talofibular ligament (PTFL). The musculotendinous structures from 10 fresh cadaveric limbs were removed and the distal fibula reflected to provide visualization of the lateral talar process and ligamentous attachments. Length and width of the LTCL, ATFL, and PTFL footprints on the lateral process of the talus were measured with calipers before and after removal of a 1-cm(3) simulated fracture fragment. Relative changes in the attachment site areas for the 3 ligaments were determined. Mean pre-excision footprint areas were 80.57 mm(2) (LTCL), 224.38 mm(2) (ATFL), and 394.18 mm(2) (PTFL); mean postexcision footprint areas were 2.10 mm(2) (LTCL), 194.89 mm(2) (ATFL), and 335.18 mm(2) (PTFL); and mean decreases calculated as percentages of the original areas were 97.5% +/- 3.5% (LTCL), 11.7% +/- 13.0% (ATFL), and 14.3% +/- 12.3% (PTFL). Removal of a 1-cm(3) bony fragment from the lateral talar process involves 3 of the major lateral stabilizing ligaments: approximately 100% of LTCL and approximately 10% to 15% of ATFL and PTFL.

Background: Fractures of the lateral process of the talus have become more frequent as the sport of snowboarding has gained popularity. The anatomy of the ligamentous attachments to the process has been described, but ligament proximity to the lateral talar process has never been specified. The objective of this cadaver study was to measure the proximity of the lateral talar process to the various lateral stabilizing ligaments of the ankle and subtalar joint: the anterior talofibular ligament, lateral talocalcaneal ligament, posterior talofibular ligament, interosseous ligament, cervical ligament, and lateral root of the extensor retinaculum., Methods: After thawing, all musculotendinous structures from 10 fresh-frozen cadaver lower limbs were carefully removed and the distal fibula was reflected to enable adequate exposure of the lateral talar process and ligamentous attachments. The apex of the lateral process was defined. Subsequently, the distance from the apex to the nearest edge and center of these surrounding ligaments was independently measured by two examiners., Results: The average apex-edge distances were 9.3 mm (posterior talofibular); 8.7 mm (anterior talofibular), 3.4 mm (lateral talocalcaneal), 13.9 mm (interosseous), 19.1 mm (cervical), and 13.0 mm (lateral root of extensor retinaculum). The average apex-center distances for those ligaments found to actually insert on the lateral talar process were 18.0 mm (posterior talofibular), 15.7 mm (anterior talofibular), and 6.2 mm (lateral talocalcaneal)., Conclusions: Contrary to previous reports, our cadaver dissections identified that only three ligaments attach to the lateral process of the talus: lateral talocalcaneal, anterior talofibular, and posterior talofibular., Clinical Relevance: Familiarity with these anatomic relationships may help guide the clinical treatment of lateral talar process fractures.

Background: Recent literature reflects a substantial increase in interest surrounding lateral talar process fractures. Previous anatomic investigations discovered that excision of a 1 cm3 fracture fragment from the lateral talar process involves approximately 100% of the lateral talocalcaneal ligament origin and 10% to 15% of both the posterior and anterior talofibular ligament insertions. The objective of this study was to determine the effect that excision of this 1 cm3 fragment has on ankle and subtalar joint stability., Methods: Ten fresh-frozen cadaver lower limbs were thawed before testing and placed in a clinical stress apparatus (Model SE 20, Telos, Marburg, Germany). Radiographs were taken before and after application of a 150 N of force. Three views (lateral, anteroposterior, 30-degree Bróden) were used to asses anterior tibiotalar translation (AT), talar tilt (TT), medial talocalcaneal motion (TCM), and talocalcaneal tilt (TCT) before and after excision of the 1 cm3 fragment the lateral talar process., Results: The mean increases in AT, TT, TCM and TCT after excision of the 1 cm3 fragment were: AT=1.0 mm+/-0.94 mm (p=0.0085); TT=0.4+/-0.52 degrees (p=0.0368); TCM=1.0 mm+/-1.25 mm (p=0.0319); TCT=1.2+/-1.32 degrees (p=0.0181)., Conclusions: Since it has been generally accepted that a 3 mm increase in AT, 3-degree increase in TT, 5-mm increase in TCM, more than 5-degree increase in TCT define instability of the ankle and subtalar joints, respectively. These results suggest that excision of a 1 cm3 fragment causes neither ankle nor subtalar instability as defined by radiographic stress examination.

Background Context: While the biomechanical properties of the isolated intervertebral disc have been well studied in the three principal anatomic directions of flexion/extension, axial rotation, and lateral bending, there is little data on the properties in the more functional directions that are combinations of these principal anatomic directions., Purpose: To determine the bending flexibility, range of motion (ROM), and neutral zone (NZ) of the human lumbar disc in multiple directions and to determine if the values about the combined moment axes can be predicted from the values about principal moment axes., Study Design/setting: Three-dimensional biomechanical analysis of the elastic bending properties of human lumbar discs about principal and combined moment axes., Methods: Pure, unconstrained moments were applied about multiple axes. The bending properties (flexibility, ROM, and NZ) of isolated lumbar discs (n=4 for L2/L3 and n=3 for L4/L5) were determined in the six principal directions and in 20 combined directions. The experimental values were compared with those predicted from the linear combination of the six principal moment axes., Results: The maximum and minimum values of the biomechanical properties were found at the principal moment axes. Among combined moment axes, ROM and NZ (but not flexibility) values were predicted from the principal moment axis values., Conclusions: The principal moment axes coincide with the primary mechanical axes of the intervertebral disc and demonstrate significant differences in direction for values of flexibility, ROM, and NZ. Not all combined moment axis values can be predicted from principal moment axis values.

Object: The authors studied the biomechanical properties of a novel spinous process stabilization plate (CD HORIZON SPIRE Spinal System) and present the results in comparison with those of other posterior fixation methods., Methods: Ten functional cadaveric lumbar segments were subjected to nondestructive quasistatic loading forces in 10 different conditions: intact, destabilized (discectomy), fitted with spinous process plate (SPP) alone, with anterior-column support (ACS) alone, ACS with SPP, ACS with posterior translaminar facet screw (PTFS) fixation, ACS with unilateral pedicle screw and rod (UPSR) fixation, ACS with bilateral pedicle screw and rod (BPSR) fixation, UPSR alone, or BPSR alone. Stiffness and range of motion (ROM) data were compared using a repeated-measures, one-way analysis of variance. The construct with greatest mean limitation of flexion-extension ROM was ACS/SPP at 4.14 degrees whereas it was 5.75 degrees for ACS/UPSR fixation, 5.03 degrees for ACS/BPSR fixation, and 10.13 degrees for the intact spine. The SPIRE plate alone also provided greater flexion and extension stiffness, with less ROM than other posterior stabilization options. Fixation with BPSR with or without ACS resulted in the stiffest construct in lateral bending and axial rotation. The SPP and UPSR fixation groups were equivalent in resisting lateral bending and axial rotation forces with or without ACS., Conclusions: The SPIRE plate effectively stabilized the spine, and the test results compare favorably with other fixation techniques that are more time consuming to perform and have greater inherent risks.