ABSTRACT
Walking performance and cognitive function demonstrate strong associations in older adults, with both declining with advancing age. Walking requires the use of cognitive resources, particularly in complex environments like stepping over obstacles. A commonly implemented approach for measuring the cognitive control of walking is a dual-task walking assessment, in which walking is combined with a second task. However, dual-task assessments have shortcomings, including issues with scaling the task difficulty and controlling for task prioritization. Here we present a new assessment designed to be less susceptible to these shortcomings while still challenging cognitive control of walking: the Obstructed Vision Obstacle (OBVIO) task. During the task, participants hold a lightweight tray at waist level obstructing their view of upcoming foam blocks, which are intermittently spaced along a 10 m walkway. This forces the participants to use cognitive resources (e.g., attention and working memory) to remember the exact placement of upcoming obstacles to facilitate successful crossing. The results demonstrate that adding the obstructed vision board significantly slowed walking speed by an average of 0.26 m/s and increased the number of obstacle strikes by 8-fold in healthy older adults (n = 74). Additionally, OBVIO walking performance (a score based on both speed and number of obstacle strikes) significantly correlated with computer-based assessments of visuospatial working memory, attention, and verbal working memory. These results provide initial support that the OBVIO task is a feasible walking test that demands cognitive resources. This study lays the groundwork for using the OBVIO task in future assessment and intervention studies.
Subject(s)
Gait , Walking , Humans , Aged , Cognition , Walking Speed , Attention , Task Performance and AnalysisABSTRACT
Background: Lateral meniscal deficiency with valgus malalignment increases the rate of lateral compartment osteoarthritis. Lateral meniscal allograft transplantation (LMAT) with a concomitant varus-producing opening-wedge distal femoral osteotomy (DFO) is an option yet to be evaluated biomechanically. Purpose/Hypothesis: The purpose of this study was to clarify the biomechanical effects of the realignment procedure in the setting of LMAT. We hypothesized that (1) given the dependence of the lateral compartment on the lateral meniscus, a DFO and increasing degrees of varus would be insufficient to restore lateral compartment pressures to normal from a lateral meniscus-deficient state, and that (2) LMAT would restore lateral compartment pressures to the intact state while DFO would decrease lateral compartment pressures for any given state of the meniscus. Study Design: Controlled laboratory study. Methods: Ten cadaveric knees underwent opening-wedge varus-producing DFO secured by an external fixator. Anatomic alignment was standardized to 6° of mechanical valgus, and each joint was tested in full extension. Submeniscal placement of thin film pressure sensors allowed for the recording of contact pressure, peak contact pressure, and contact area. The specimens were loaded on a biaxial dynamic testing machine with loading angles between 9° valgus and 6° varus of mechanical alignment. Conditions tested included intact meniscus, meniscal deficiency, and meniscal transplantation. Results: Isolated varus-producing DFO to 6° in the meniscus-deficient state failed to restore joint pressures and contact areas to the intact state, with significant changes in mean contact pressure (175%), mean peak contact pressure (135%), and contact area (-41%) (all P < .05 vs intact), while LMAT restored all outcome measures (all P > .05 compared with intact). After LMAT, every additional 1° of DFO correction contributed to a decrease in the mean contact pressure, peak pressure, and contact area of 5.6% (-0.0479 N/mm2), 5.9% (-0.154 N/mm2), and 1.4% (-6.99 mm2) for the lateral compartment and 7.3% (+0.034 N/mm2), 12.6% (+0.160 N/mm2), and 4.3% (+20.53 mm2) for the medial compartment, respectively. Conclusion: Isolated DFO was inadequate to restore load distribution in meniscus-deficient knees, while concomitant LMAT restored near normal forces and improved the lateral compartment biomechanical profile. Clinical Relevance: Our findings support the concomitant use of LMAT and varus-producing DFO in the setting of lateral meniscal deficiency with valgus malalignment. This study provides tools for the orthopaedic surgeon to individualize the correction for each patient.
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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.
Subject(s)
Joint Dislocations , Joint Instability , Shoulder Joint , Humans , Shoulder Joint/diagnostic imaging , Shoulder Joint/surgery , Shoulder Joint/pathology , Shoulder/pathology , Joint Instability/surgery , Joint Instability/pathology , Biomechanical Phenomena , Cadaver , Rotation , Joint Dislocations/pathologyABSTRACT
PURPOSE: To investigate the effects of combining bone marrow stimulation (BMS) with oral losartan to block transforming growth factor ß1 (TGF-ß1) on biomechanical repair strength in a rabbit chronic injury model. METHODS: Forty rabbits were randomly allocated into 4 groups (10 in each group). The supraspinatus tendon was detached and left alone for 6 weeks to establish a rabbit chronic injury model and was then repaired in a surgical procedure using a transosseous, linked, crossing repair construct. The animals were divided into the following groups: control group (group C), surgical repair only; BMS group (group B), surgical repair with BMS of the tuberosity; losartan group (group L), surgical repair plus oral losartan (TGF-ß1 blocker) for 8 weeks; and BMS-plus-losartan group (group BL), surgical repair plus BMS plus oral losartan for 8 weeks. At 8 weeks after repair, biomechanical and histologic evaluations were performed. RESULTS: The biomechanical testing results showed significantly higher ultimate load to failure in group BL than in group B (P = .029) but not compared with group C or group L. A 2 × 2 analysis-of-variance model found that the effect of losartan on ultimate load significantly depended on whether BMS was performed (interaction term F1,28 = 5.78, P = .018). No difference was found between the other groups. No difference in stiffness was found between any groups. On histologic assessment, groups B, L, and BL showed improved tendon morphology and an organized type I collagen matrix with less type III collagen compared with group C. Group BL showed the most highly organized tendon matrix with more type I collagen and less type III collagen, which indicates less fibrosis. Similar results were found at the bone-tendon interface. CONCLUSIONS: Rotator cuff repair combined with oral losartan and BMS of the greater tuberosity showed improved pullout strength and a highly organized tendon matrix in this rabbit chronic injury model. CLINICAL RELEVANCE: Tendon healing or scarring is accompanied by the formation of fibrosis, which has been shown to result in compromised biomechanical properties, and is therefore a potential limiting factor in healing after rotator cuff repair. TGF-ß1 expression has been shown to play an important role in the formation of fibrosis. Recent studies focusing on muscle healing and cartilage repair have found that the downregulation of TGF-ß1 by losartan intake can reduce fibrosis and improve tissue regeneration in animal models.
Subject(s)
Bone Marrow , Losartan , Animals , Rabbits , Losartan/pharmacology , Losartan/therapeutic use , Transforming Growth Factor beta1 , Collagen Type I , Collagen Type III , Tendons/surgery , FibrosisABSTRACT
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%.
Subject(s)
Ankle Fractures , Ankle Injuries , Joint Instability , Lateral Ligament, Ankle , Humans , Tibia/surgery , Joint Instability/surgery , Lateral Ligament, Ankle/surgery , Ankle Joint/surgery , Fibula , Ankle Fractures/surgery , Ankle Injuries/surgery , Fracture Fixation, Internal , CadaverABSTRACT
INTRODUCTION: Screw cut out and varus collapse are the most common complication of locked plate fixation of proximal humerus fractures. The purpose of this study was to compare dual plating and endosteal fibular allograft struts as augmentation strategies to prevent varus collapse. MATERIALS AND METHODS: A trapezoidal osteotomy was created at the metaphysis to create a 2-part proximal humerus model in 18 paired shoulder specimens. Each specimen was assigned to group A, B, or C and was fixed with either a lateral locking plate, a lateral locking plate and anterior one-third tubular plate in an orthogonal 90/90 configuration, or a lateral locking plate with intramedullary fibular strut, respectively. The specimens were stressed in axial compression to failure. Displacement, elastic limit, ultimate load, and stiffness were recorded and calculated. RESULTS: There was no difference in mean cyclic displacement between the three groups (0.71 mm vs 0.89 mm vs 0.61 mm for Group A, B, C, respectively). Lateral plating demonstrated the greatest absolute and relative displacement at the elastic limit (5.3 mm ± 1.5 and 4.4 mm ± 1.3) without significance. The elastic limit or yield point was greatest for fibular allograft, Group C (1223 N ± 501 vs 1048 N ± 367 for Group B and 951 N ± 249 for Group A) without significance. CONCLUSIONS: Dual plating of proximal humerus fractures in a 90-90 configuration demonstrates similar biomechanical properties as endosteal fibular strut allograft. Both strategies demonstrate superior stiffness to isolated lateral locked plating.
Subject(s)
Humeral Fractures , Shoulder Fractures , Humans , Fracture Fixation, Internal , Humerus/surgery , Shoulder Fractures/surgery , Bone Plates , Humeral Fractures/surgery , Allografts , Biomechanical PhenomenaABSTRACT
PURPOSE: The purpose of this study was to compare, using a cadaveric model, the biomechanical properties of headless compression screws (HCSs) and HCSs augmented with a buttress plate (BP) in capitellar fractures. METHODS: Twenty pairs of fresh-frozen humeri (mean age, 46.3 years; range, 33-58 years) were used. The soft tissue was removed, and a Dubberley type IA capitellar fracture was created. One specimen in each pair was randomly assigned to receive either two 2.5-mm HCSs (HCS group) or two 2.5-mm HCSs augmented with an anterior 2.4-mm BP (HCS + BP group). This resulted in a similar distribution of the left and right humeri between the groups. Cyclic loading was performed, and displacement of the capitellum at 50, 100, 250, 500, 1,000, and 2,000 cycles was assessed using a motion capture system. This was followed by load-to-failure testing, wherein the load at a displacement of 1 and 2 mm was recorded. Failure was defined as 2-mm displacement. RESULTS: During cyclic loading, there were no significant differences in the displacement between the HCS and HCS + BP groups at any of the assessed cycles. During load-to-failure testing, no significant strength differences were observed in the load at 1-mm displacement between the HCS (mean: 449.8 N, 95% CI: 283.6-616.0) and HCS + BP groups (mean: 606.2 N, 95% CI: 476.4-736.0). However, a significantly smaller load resulted in a 2-mm displacement of the fragment in the HCS group (mean: 668.8 N, 95% CI: 414.3-923.2) compared with the HCS + BP group (mean: 977.5 N, 95% CI: 794.1-1,161.0). CONCLUSIONS: Anterior, low-profile buttress plating in addition to HCSs results in a significantly higher load to failure compared with HCSs alone in a biomechanical Dubberley type IA capitellar fracture model. CLINICAL RELEVANCE: The addition of an anterior BP may be considered to improve initial stability in select cases such as osteoporotic patients or when the posterolateral column is frail.
Subject(s)
Fracture Fixation, Internal , Fractures, Bone , Humans , Middle Aged , Biomechanical Phenomena , Bone Plates , Bone Screws , Cadaver , Fracture Fixation, Internal/methods , Fractures, Bone/surgery , HumerusABSTRACT
This study investigated locomotor learning of a complex terrain walking task in older adults, when combined with two adjuvant interventions: transcutaneous spinal direct current stimulation (tsDCS) to increase lumbar spinal cord excitability, and textured shoe insoles to increase somatosensory feedback to the spinal cord. The spinal cord has a crucial contribution to control of walking, and is a novel therapeutic target for rehabilitation of older adults. The complex terrain task involved walking a 10-meter course consisting of nine obstacles and three sections of compliant (soft) walking surface. Twenty-three participants were randomly assigned to one of the following groups: sham tsDCS and smooth insoles (sham/smooth; control group), sham tsDCS and textured insoles (sham/textured), active tsDCS and smooth insoles (active/smooth), and active tsDCS and textured insoles (active/textured). The first objective was to assess the feasibility, tolerability, and safety of the interventions. The second objective was to assess preliminary efficacy for increasing locomotor learning, as defined by retention of gains in walking speed between a baseline visit of task practice, and a subsequent follow-up visit. Variability of the center of mass while walking over the course was also evaluated. The change in executive control of walking (prefrontal cortical activity) between the baseline and follow-up visits was measured with functional near infrared spectroscopy. The study results demonstrated feasibility based on enrollment and retention of participants, tolerability based on self-report, and safety based on absence of adverse events. Preliminary efficacy was supported based on trends showing larger gains in walking speed and more pronounced reductions in mediolateral center of mass variability at the follow-up visit in the groups randomized to active tsDCS or textured insoles. These data justify future larger studies to further assess dosing and efficacy of these intervention approaches. In conclusion, rehabilitation interventions that target spinal control of walking present a potential opportunity for enhancing walking function in older adults.
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PURPOSE: Despite increasing interest in utilizing quadriceps tendon (QT) grafts in anterior cruciate ligament reconstruction (ACLR), data on the optimal quadriceps graft thickness are limited. The purpose of this study was to characterize the mechanical properties for the quadriceps tendon, comparing full-thickness (FT) QT grafts with and without bone to a partial-thickness (PT) QT graft, and comparing the three QT grafts to four-stranded semitendinosus (4-SST) and bone-patellar tendon-bone (BTB) grafts and one experimental graft, the two-stranded rectus femoris (RF). METHODS: Forty-eight (n = 48) young cadaveric grafts (mean age 32 ± 6 years) were utilized for testing with N = 8 specimens in each of the following groups; (1) FT QT with bone, (2) FT QT without bone, (3) PT QT without bone, (4) BTB, (5) RF, and (6) 4-SST. Each specimen was harvested and rigidly fixed in custom clamps to a dynamic tensile testing machine for biomechanical evaluation. Graft ultimate load and stiffness were recorded. Independent groups one-factor ANOVAs and Tukey's pairwise comparisons were performed for statistical analyses. RESULTS: FT QT with bone and 4-SST grafts demonstrated similar ultimate loads to BTB grafts (both n.s), whereas PT QT demonstrate statistically significantly lower ultimate loads to BTB grafts (n.s) and 4-SST grafts (n.s). Furthermore, no statistically significant differences were observed between the ultimate loads of FT QT vs. PT QT grafts without bone (n.s) or between FT QT with vs. without bone (n.s). FT QT grafts with bone did not demonstrate statistically significantly greater ultimate loads than PT QT grafts without bone (n.s). The RF graft demonstrated statistically significantly lower ultimate loads to BTB grafts (p < 0.005) and 4-SST grafts (p < 0.014). CONCLUSIONS: Full thickness QT grafts with bone had similar material properties to BTB and a 4-SST grafts, while Partial thickness QT graft without bone had significantly lower material properties than BTB and 4-SST, in a biomechanical setting.
Subject(s)
Anterior Cruciate Ligament Injuries , Anterior Cruciate Ligament Reconstruction , Hamstring Muscles , Patellar Ligament , Adult , Anterior Cruciate Ligament Injuries/surgery , Hamstring Muscles/surgery , Humans , Patellar Ligament/surgery , Quadriceps Muscle/surgery , Tendons/transplantationABSTRACT
BACKGROUND: The percutaneous knotless repair technique for Achilles tendon ruptures utilizes a Percutaneous Achilles Repair System (PARS) device for suturing the proximal tendon and 2 suture anchors for fixing the sutures into the calcaneus. Determining the best position of the suture anchors may optimize the strength of this repair. METHODS: Twelve pairs of human ankle cadaveric specimens were randomly assigned to receive suture anchors placed at 45°, 90°, or 135° from the sagittal plane. The anchors were tensioned according to a protocol representing progressive, postoperative rehabilitation. Load, number of loading cycles, displacement, and mode of failure were recorded. RESULTS: With the anchors placed at 45°, 90°, and 135°, the ultimate failure loads were mean 265 ± 64 N, 264 ± 75 N, and 279 ± 40 N, and the total number of loading cycles were mean 459 ± 166, 466 ± 158, and 469 ± 110, respectively. The effect of anchor angle on failure load, number of loading cycles, and displacement was not statistically significant. Visually, the anchors at 45° and 90° demonstrated sutures cutting through the bone. CONCLUSION: We found no statistically significant difference in pullout strength between the 3 different anchor angles. Sutures cutting through the bone may be a concern with acute anchor angles. This suggests that a 135° anchor angle may result in a lower risk of tendon elongation with the percutaneous knotless repair technique. LEVELS OF EVIDENCE: Cadaveric laboratory study.
Subject(s)
Achilles Tendon , Achilles Tendon/surgery , Biomechanical Phenomena , Cadaver , Humans , Suture Anchors , Suture Techniques , SuturesABSTRACT
BACKGROUND: Meniscal deficiency has been reported to increase contact pressures in the affected tibiofemoral joint, possibly leading to degenerative changes. Current surgical options include meniscal allograft transplantation and insertion of segmental meniscal scaffolds. Little is known about segmental meniscal allograft transplantation. PURPOSE: To evaluate the effectiveness of segmental medial meniscal allograft transplantation in the setting of partial medial meniscectomy in restoring native knee loading characteristics. STUDY DESIGN: Controlled laboratory study. METHODS: Ten fresh-frozen human cadaveric knees underwent central midbody medial meniscectomy and subsequent segmental medial meniscal allograft transplantation. Knees were loaded in a dynamic tensile testing machine to 1000 N for 20 seconds at 0°, 30°, 60°, and 90° of flexion. Four conditions were tested: (1) intact medial meniscus, (2) deficient medial meniscus, (3) segmental medial meniscal transplant fixed with 7 meniscocapsular sutures, and (4) segmental medial meniscal transplant fixed with 7 meniscocapsular sutures and 1 suture fixed through 2 bone tunnels. Submeniscal medial and lateral pressure-mapping sensors assessed mean contact pressure, peak contact pressure, mean contact area, and pressure mapping. Two-factor random-intercepts linear mixed effects models compared pressure and contact area measurements among experimental conditions. RESULTS: The meniscal-deficient state demonstrated a significantly higher mean contact pressure than all other testing conditions (mean difference, ≥0.35 MPa; P < .001 for all comparisons) and a significantly smaller total contact area as compared with all other testing conditions (mean difference, ≤140 mm2; P < .001 for all comparisons). There were no significant differences in mean contact pressure or total contact area among the intact, transplant, or transplant-with-tunnel groups or in any outcome measure across all comparisons in the lateral compartment. No significant differences existed in center of pressure and relative pressure distribution across testing conditions. CONCLUSION: Segmental medial meniscal allograft transplantation restored the medial compartment mean contact pressure and mean contact area to values measured in the intact medial compartment. CLINICAL RELEVANCE: Segmental medial meniscal transplantation may provide an alternative to full meniscal transplantation by addressing only the deficient portion of the meniscus with transplanted tissue. Additional work is required to validate long-term fixation strength and biologic integration.
Subject(s)
Meniscectomy , Menisci, Tibial , Biomechanical Phenomena , Cadaver , Humans , Knee Joint/surgery , Menisci, Tibial/surgeryABSTRACT
PURPOSE: To compare the biomechanical properties of metallic anchor (MA) and all-suture anchor (ASA) constructs in the anatomic reattachment of the lateral ulnar collateral ligament complex to its humeral insertion. METHODS: Twenty paired male human cadaveric elbows with a mean age of 46.3 years (range: 33-58 years) were used in this study. Each pair was randomly allocated across 2 groups of either MA or ASA. A single 3.5-mm MA or 2.6-mm ASA was then inserted flush into the lateral epicondyle. A dynamic tensile testing machine was used to perform cyclic loading followed by a load to failure test. During the cyclic loading phase, the anchors were sinusoidally tensioned from 10 N to 100 N for 1,000 cycles at a frequency of 0.5 Hz. In the load to failure test, the anchors were pulled at a rate of 3 mm/s. Load at 1-mm and 2-mm displacement, as well as load to ultimate failure were assessed. Clinical failure was defined as displacement of more than 2 mm. Normality of data was assessed with the Shapiro-Wilk test. Continuous data are presented as medians and compared with the Mann-Whitney U test and categorical data was compared with the χ2 test or Fisher exact test. RESULTS: Displacement was significantly greater for the ASA group during cyclic loading starting from the tenth cycle (P < .05). Displacement of more than 5 mm within the first 100 cycles was observed in 2 anchors in the ASA group. No difference was observed in loads required to displace 1 mm (MA: 146 N [6-169] vs ASA: 144 N [2-153]; P = .53) and 2 mm (MA: 171 N [13-202] vs ASA: 161 N [9-191]; P = .97), but there was a statistically significant difference between ultimate loads in favor of ASA in the load to failure test (MA: 297 N [84-343] vs 463 N [176-620]; P < .01). CONCLUSIONS: In the cyclic test, no difference in clinical failure defined as pull-out of more than 2 mm was observed between 3.5 mm MAs and 2.6 mm ASAs. In the ultimate load to failure analysis, no difference was observed between groups in force causing 1 and 2 mm of displacement, but there was a significant difference in favor of ASA in the pull to ultimate failure test. CLINICAL RELEVANCE: Potential benefits of all-suture anchors include preservation of bone stock, reduced radiographic artifacts, and easier revisions. Although their use has been investigated thoroughly in the shoulder, there remains a paucity of literature regarding displacement and pull-out strength in the elbow.
Subject(s)
Elbow , Lateral Ligament, Ankle , Adult , Biomechanical Phenomena , Cadaver , Humans , Male , Middle Aged , Suture Anchors , Suture Techniques , SuturesABSTRACT
PURPOSE: To investigate the biomechanical influence of differential loading of suture strands (torque) on the fixation strength of knotted and knotless all-suture anchors. METHODS: The biomechanical strength of 48 all-suture anchors was evaluated for 4 conditions in polyurethane foam blocks: (1) 12 knotted all-suture anchors loaded proportionately, (2) 12 knotted all-suture anchors with 1 suture strand bearing 50% of total force (partial torque), (3) 12 knotted all-suture anchors with 1 strand fixated and the other loaded (full torque), and (4) 12 knotless all-suture anchors with the loop kept open via a fixed rod. Force for 1 mm and 2 mm of displacement and ultimate failure load were assessed. RESULTS: For 1 mm of displacement, groups 2, 3, and 4 showed significantly lower forces than group 1 (all P < .001), with no statistically significant difference between groups 2 and 3 (P = .516); for 2 mm of displacement, all groups showed significantly lower forces than group 1 (P < .001), which positively correlated with applied torque. No differences in the mean ultimate loads observed between testing groups 1, 2, and 4 were noted, with 93.3 ± 3.8 N, 91.4 ± 4.7 N, and 92.6 ± 5.6 N, respectively; however, group 3 exhibited a significantly lower mean ultimate load (62.3 ± 1.7 N) than all other groups (P < .001). CONCLUSIONS: The ultimate failure load of knotted and knotless all-suture anchor fixation was partially affected by loading differentials between strands in this validated foam block model. Differential loading of knotted all-suture anchor fixation presented greater initial displacement when compared with symmetrically loaded knotted all-suture anchors. Despite an initial increase in displacement, knotless all-suture anchors showed similar ultimate failure loads to knotted all-suture anchors with strands loaded equally. CLINICAL RELEVANCE: The role of suture strand loading imbalance on anchor fixation is variable and should be considered during placement and fixation of the repair constructs in a clinical setting.
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BACKGROUND: Dual orthogonal plating of midshaft clavicle fractures is increasingly used for osteosynthesis. The risk of refracture after hardware removal remains unknown. The purpose of this study was to compare the torsional and 3-point bending loads to failure of the clavicle following removal of single-plane, superior 3.5-mm plate fixation vs. dual orthogonal plating 2.7-mm constructs. METHODS: This study used 12 pairs of clavicles (N = 24) harvested from cadaveric specimens with a mean age at death of 56.5 years (range, 46-65 years). One clavicle from each pair was randomly assigned to either superior plating (SP, n = 12) or double plating (DP, n = 12). For SP, a superior 3.5-mm plate was used as a template to drill 3 bicortical 2.8-mm holes medial and lateral to the center of the clavicle. For DP, two 2.7-mm plates were used as a template to drill 4 bicortical 2.0-mm holes medial and lateral to the center of the clavicle. Clavicle pairs were randomly and evenly distributed to undergo either 3-point bending (n = 12) or posterior torsional loading (n = 12). Cyclic loading was performed, followed by load-to-failure testing. Stiffness, displacement at failure, load to failure, and failure mode were assessed and compared between SP and DP constructs. RESULTS: No significant differences between the SP and DP groups were observed for stiffness (768.2 ± 281.3 N/mm vs. 785.5 ± 315.0 N/mm, P = .872), displacement at failure (8.1 ± 2.8 mm vs. 5.4 ± 1.2 mm, P = .150), and ultimate load at failure (1831.0 ± 229.6 N vs. 1842.0 ± 662.4 N, P = .964) under the condition of 3-point bending. Similarly, no significant differences between the SP and DP groups were observed for torsional stiffness (1.3 ± 0.8 N · m/° vs. 1.1 ± 0.4 N · m/°, P = .844), rotation at failure (17.3° ± 4.4° vs. 14.4° ± 1.2°, P = .205), and ultimate torque at failure (14.8 ± 6.5 N · m vs. 14.7 ± 6.9 N · m, P = .103) under the condition of posterior torsional loading. The most common mode of failure for 3-point bending testing was an oblique fracture (7 of 12 clavicles, 58.3%), with no significant difference between groups (3 of 6 in SP group [50%] vs. 4 of 6 in DP group [66.7%], P > .999). The most common mode of failure with posterior torsional loading was a spiral fracture (10 of 12 clavicles, 83.3%), with no significant difference between groups (4 of 6 in SP group [66.7%] vs. 6 of 6 in DP group [100%], P = .455). CONCLUSION: Following clavicle plate removal of either DP or SP, there is no statistically significant difference in the amount of force, under the condition of 3-point bending or torsional loading, required to fracture the diaphyseal clavicle in vitro.
Subject(s)
Clavicle , Fractures, Bone , Biomechanical Phenomena , Bone Plates , Fracture Fixation, Internal , Fractures, Bone/surgery , HumansABSTRACT
This review provides a critical, multi-faceted assessment of the practical contribution tidal stream energy can make to the UK and British Channel Islands future energy mix. Evidence is presented that broadly supports the latest national-scale practical resource estimate, of 34 TWh/year, equivalent to 11% of the UK's current annual electricity demand. The size of the practical resource depends in part on the economic competitiveness of projects. In the UK, 124 MW of prospective tidal stream capacity is currently eligible to bid for subsidy support (MeyGen 1C, 80 MW; PTEC, 30 MW; and Morlais, 14 MW). It is estimated that the installation of this 124 MW would serve to drive down the levelized cost of energy (LCoE), through learning, from its current level of around 240 £ / MWh to below 150 £ / MWh , based on a mid-range technology learning rate of 17%. Doing so would make tidal stream cost competitive with technologies such as combined cycle gas turbines, biomass and anaerobic digestion. Installing this 124 MW by 2031 would put tidal stream on a trajectory to install the estimated 11.5 GW needed to generate 34 TWh/year by 2050. The cyclic, predictable nature of tidal stream power shows potential to provide additional, whole-system cost benefits. These include reductions in balancing expenditure that are not considered in conventional LCoE estimates. The practical resource is also dependent on environmental constraints. To date, no collisions between animals and turbines have been detected, and only small changes in habitat have been measured. The impacts of large arrays on stratification and predator-prey interaction are projected to be an order of magnitude less than those from climate change, highlighting opportunities for risk retirement. Ongoing field measurements will be important as arrays scale up, given the uncertainty in some environmental and ecological impact models. Based on the findings presented in this review, we recommend that an updated national-scale practical resource study is undertaken that implements high-fidelity, site-specific modelling, with improved model validation from the wide range of field measurements that are now available from the major sites. Quantifying the sensitivity of the practical resource to constraints will be important to establish opportunities for constraint retirement. Quantification of whole-system benefits is necessary to fully understand the value of tidal stream in the energy system.
ABSTRACT
BACKGROUND: It is widely accepted that transolecranon fracture-dislocations are not associated with collateral ligament disruption. The aim of the present study was to investigate the significance of the collateral ligaments in transolecranon fractures. METHODS: Twenty cadaveric elbows with a mean age of 46.3 years were used. All soft tissue was dissected to the level of the capsule, leaving the anterior band of the medial collateral ligament (MCL) and lateral collateral ligament (LCL) intact. A standardized, oblique osteotomy starting from the distal margin of the cartilage bare area of the ulna was made. The elbows were loaded with an inferiorly directed force of 5 and 10 N in the intact, MCL cut, LCL cut, and both ligaments cut states. All measurements were recorded on lateral calibrated radiographs. RESULTS: The mean inferior translation with intact ligaments (n = 20) when the humerus was loaded with 5 and 10 N was 1.52 mm (95% confidence interval [CI], 1.02-2.02) and 2.23 mm (95% CI, 1.61-2.85), respectively. When the LCL was cut first (n = 10), the inferior translation with 5 and 10 N load was 4.11 mm (95% CI, 0.95-7.26) and 4.82 mm (95% CI, 1.91-7.72), respectively. When the MCL was cut first (n = 10), the inferior translation when loaded with 5 and 10 N was 3.94 mm (95% CI, 0.796-7.08) and 5.68 mm (95% CI, 3.03-8.33), respectively. The inferior translation when loaded with 5 and 10 N and both ligaments cut was 15.65 mm (95% CI, 12.59-18.79) and 17.50 mm (95% CI, 14.86-20.13), respectively. There was a statistical difference between the intact and MCL cut first at 10 N and when both ligaments were cut at 5 and 10 N. CONCLUSIONS: The findings suggest that collateral ligament disruption is a prerequisite for a transolecranon fracture-dislocation. An inferior translation of more than 3 mm suggests that at least one of the collateral ligaments is disrupted, and more than 7.5 mm indicates that both collateral ligaments are disrupted.
Subject(s)
Collateral Ligaments , Elbow Joint , Joint Dislocations , Biomechanical Phenomena , Cadaver , Collateral Ligaments/surgery , Elbow , Elbow Joint/surgery , Humans , Middle Aged , UlnaABSTRACT
BACKGROUND: A medialized center of rotation (COR) in reverse total shoulder arthroplasty (RTSA) comes with limitations such as scapular notching and reduced range of motion. To mitigate these effects, lateralization and inferiorization of the COR are performed, but may adversely affect deltoid muscle force. The study purposes were to measure the effect of RTSA with varying glenosphere configurations on (1) the COR and (2) deltoid force compared with intact shoulders and shoulders with massive posterosuperior rotator cuff tears (PS-RCT). We hypothesized that the highest deltoid forces would occur in shoulders with PS-RCT, and that RTSA would lead to a decrease in required forces that is further minimized with lateralization and inferiorization of the COR but still higher compared with native shoulders with an intact rotator cuff. METHODS: In this study, 8 cadaveric shoulders were dissected leaving only the rotator cuff muscles and capsule intact. A custom apparatus incorporating motion capture and a dynamic tensile testing machine to measure the changes in COR and deltoid forces while simultaneously recording glenohumeral abduction was designed. Five consecutive testing states were tested: (1) intact shoulder, (2) PS-RCT, (3) RTSA with standard glenosphere, (4) RTSA with 4 mm lateralized glenosphere, and (5) RTSA with 2.5 mm inferiorized glenosphere. Statistical Parametric Mapping was used to analyze the deltoid force as a function of the abduction angle. One-way repeated-measures within-specimens analysis of variance was conducted, followed by post hoc t-tests for pairwise comparisons between the states. RESULTS: All RTSA configurations shifted the COR medially and inferiorly with respect to native (standard: 4.2 ± 2.1 mm, 19.7 ± 3.6 mm; 4 mm lateralized: 3.9 ± 1.2 mm, 16.0 ± 1.8; 2.5 mm inferiorized: 6.9 ± 0.9 mm, 18.9 ± 1.7 mm). Analysis of variance showed a significant effect of specimen state on deltoid force across all abduction angles. Of the 10 paired t-test comparisons made between states, only 3 showed significant differences: (1) intact shoulders necessitated significantly lower deltoid force than specimens with PS-RCT below 42° abduction, (2) RTSAs with standard glenospheres required significantly lower deltoid force than RTSA with 4 mm lateralized glenospheres above 34° abduction, and (3) RTSAs with 2.5 mm inferiorized glenospheres had significantly lower deltoid force than RTSA with 4 mm of glenosphere lateralization at higher abduction angles. CONCLUSIONS: RTSA with a 2.5 mm inferiorized glenosphere and no additional lateralization resulted in less deltoid force to abduct the arm compared with 4 mm lateralized glenospheres. Therefore, when aiming to mitigate downsides of a medialized COR, an inferiorized glenosphere may be preferable in terms of its effect on deltoid force.
Subject(s)
Arthroplasty, Replacement, Shoulder , Shoulder Joint , Shoulder Prosthesis , Biomechanical Phenomena , Cadaver , Deltoid Muscle/surgery , Humans , Range of Motion, Articular , Shoulder Joint/surgeryABSTRACT
PURPOSE: To compare the biomechanical performance of knotless versus knotted all-suture anchors for the repair of type II SLAP lesions with a simulated peel-back mechanism. METHODS: Twenty paired cadaveric shoulders were used. A standardized type II SLAP repair was performed using knotless (group A) or knotted (group B) all-suture anchors. The long head of the biceps (LHB) tendon was loaded in a posterior direction to simulate the peel-back mechanism. Cyclic loading was performed followed by load-to-failure testing. Stiffness, load at 1 and 2 mm of displacement, load to repair failure, load to ultimate failure, and failure modes were assessed. RESULTS: The mean load to repair failure was similar in groups A (179.99 ± 58.42 N) and B (167.83 ± 44.27 N, P = .530). The mean load to ultimate failure was 230 ± 95.93 N in group A and 229.48 ± 78.45 N in group B and did not differ significantly (P = .958). Stiffness (P = .980), as well as load at 1 mm (P = .721) and 2 mm (P = .849) of displacement, did not differ significantly between groups. In 16 of the 20 specimens (7 in group A and 9 in group B), ultimate failure occurred at the proximal LHB tendon. Failed occurred through slippage of the labrum in 1 specimen in each group and through anchor pullout in 2 specimens in group A. CONCLUSIONS: Knotless and knotted all-suture anchors displayed high initial fixation strength with no significant differences between groups in type II SLAP lesions. Ultimate failure occurred predominantly as tears of the proximal LHB tendon. CLINICAL RELEVANCE: All-suture anchors have a smaller diameter than solid anchors, can be inserted through curved guides, preserve bone stock, and facilitate postoperative imaging. There is a paucity of literature investigating the biomechanical capacities of knotless versus knotted all-suture anchors in type II SLAP repair.
Subject(s)
Shoulder Injuries , Shoulder Injuries/surgery , Shoulder Joint/surgery , Suture Anchors , Suture Techniques , Tendons/surgery , Biomechanical Phenomena , Cadaver , Humans , Male , Middle Aged , Orthopedic Procedures/instrumentation , Orthopedic Procedures/methods , Osteotomy , Scapula/surgery , Shoulder/physiopathology , Shoulder/surgery , Shoulder Injuries/physiopathology , Shoulder Joint/physiopathology , Tendons/physiopathologyABSTRACT
In this article, Tribal Maternal, Infant, and Early Childhood Home Visiting (MIECHV) grantees share strategies they have developed and adopted to address the most common barriers to effective measurement (and thus to effective evaluation) encountered in the course of implementation and evaluation of their home-visiting programs. We identify key challenges in measuring outcomes in Tribal MIECHV Programs and provide practical examples of various strategies used to address these challenges within diverse American Indian and Alaska Native cultural and contextual settings. Notably, high-quality community engagement is a consistent thread throughout these strategies and fundamental to successful measurement in these communities. These strategies and practices reflect the experiences and innovative solutions of practitioners working on the ground to deliver and evaluate intervention programs to tribal communities. They may serve as models for getting high-quality data to inform intervention while working within the constraints and requirements of program funding. The utility of these practical solutions extends beyond the Tribal MIECHV grantees and offers the potential to inform a broad array of intervention evaluation efforts in tribal and other community contexts.
Subject(s)
Child Health Services , Culturally Competent Care/methods , Health Services, Indigenous , House Calls , Maternal Health Services , Adult , Alaska , Child, Preschool , Female , Humans , Indians, North American , Infant , Infant, Newborn , Male , Needs Assessment , New Mexico , Pregnancy , Washington , Young AdultABSTRACT
BACKGROUND: Chronic obstructive pulmonary disease (COPD) affects > 3 million people in the UK. Acute exacerbations of COPD (AECOPD) are the second most common reason for emergency hospital admission in the UK. Pulmonary rehabilitation is usual care for stable COPD but there is little evidence for early pulmonary rehabilitation (EPR) following AECOPD, either in hospital or immediately post discharge. OBJECTIVE: To assess the feasibility of recruiting patients, collecting data and delivering EPR to patients with AECOPD to evaluate EPR compared with usual care. DESIGN: Parallel-group, pilot 2 × 2 factorial randomised trial with nested qualitative research and an economic analysis. SETTING: Two acute hospital NHS trusts. Recruitment was carried out from September 2015 to April 2016 and follow-up was completed in July 2016. PARTICIPANTS: Eligible patients were those aged ≥ 35 years who were admitted with AECOPD, who were non-acidotic and who maintained their blood oxygen saturation level (SpO2) within a prescribed range. Exclusions included the presence of comorbidities that affected the ability to undertake the interventions. INTERVENTIONS: (1) Hospital EPR: muscle training delivered at the patient's hospital bed using a cycle ergometer and (2) home EPR: a pulmonary rehabilitation programme delivered in the patient's home. Both interventions were delivered by trained physiotherapists. Participants were allocated on a 1 : 1 : 1 : 1 ratio to (1) hospital EPR (n = 14), (2) home EPR (n = 15), (3) hospital EPR and home EPR (n = 14) and (4) control (n = 15). Outcome assessors were blind to treatment allocation; it was not possible to blind patients. MAIN OUTCOME MEASURES: Feasibility of recruiting 76 participants in 7 months at two centres; intervention delivery; views on intervention/research acceptability; clinical outcomes including the 6-minute walk distance (6WMD); and costs. Semistructured interviews with participants (n = 27) and research health professionals (n = 11), optimisation assessments and an economic analysis were also undertaken. RESULTS: Over 7 months 449 patients were screened, of whom most were not eligible for the trial or felt too ill/declined entry. In total, 58 participants (76%) of the target 76 participants were recruited to the trial. The primary clinical outcome (6MWD) was difficult to collect (hospital EPR, n = 5; home EPR, n = 6; hospital EPR and home EPR, n = 5; control, n = 5). Hospital EPR was difficult to deliver over 5 days because of patient discharge/staff availability, with 34.1% of the scheduled sessions delivered compared with 78.3% of the home EPR sessions. Serious adverse events were experienced by 26 participants (45%), none of which was related to the interventions. Interviewed participants generally found both interventions to be acceptable. Home EPR had a higher rate of acceptability, mainly because patients felt too unwell when in hospital to undergo hospital EPR. Physiotherapists generally found the interventions to be acceptable and valued them but found delivery difficult because of staffing issues. The health economic analysis results suggest that there would be value in conducting a larger trial to assess the cost-effectiveness of the hospital EPR and hospital EPR plus home EPR trial arms and collect more information to inform the hospital cost and quality-adjusted life-year parameters, which were shown to be key drivers of the model. CONCLUSIONS: A full-scale randomised controlled trial using this protocol would not be feasible. Recruitment and delivery of the hospital EPR intervention was difficult. The data obtained can be used to design a full-scale trial of home EPR. Because of the small sample and large confidence intervals, this study should not be used to inform clinical practice. TRIAL REGISTRATION: Current Controlled Trials ISRCTN18634494. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 11. See the NIHR Journals Library website for further project information.