Independent Suture Tape Reinforcement of Tripled Smaller-Diameter and Quadrupled Grafts for Anterior Cruciate Ligament Reconstruction With Tibial Screw Fixation: A Biomechanical Full Construct Model.

PURPOSE: To compare the effect of independent suture tape reinforcement on the dynamic elongation and stiffness behavior as well as ultimate strength of tripled smaller-diameter and quadrupled soft-tissue grafts for anterior cruciate ligament reconstruction (ACLR) with tibial screw fixation in a biomechanical in vitro study. METHODS: Tripled smaller-diameter (8 mm) and quadrupled (9 mm) bovine tendon grafts with and without suture tape reinforcement (n = 8 in each group) were tested using femoral suspensory and tibial interference screw fixation. The suture tape was femoral sided and fixed independent from the graft by passing it through the suspensory button and securing the 2 open tibial strands with a secondary interference screw. Dynamic testing was performed in position and force control at 250 N and 400 N, followed by pull to failure with the mode of failure noted. Dynamic elongation, stiffness, and ultimate strength were analyzed. RESULTS: Tripled constructs showed a significantly worse structural performance than quadrupled constructs at higher loads. Reinforcement of tripled and quadrupled grafts substantially decreased total elongation by 56% (4.54 ± 0.75 mm vs 2.01 ± 0.50 mm, P < .001) and 39% (3.25 ± 0.49 mm vs 1.98 ± 0.51 mm, P < .001), respectively, by significantly increasing dynamic stiffness. No statistical significance was found between the reinforced groups. Failure loads of reinforced tripled (1,074 ± 148 N vs 829 ± 100 N, P = .003) and quadrupled (1,125 ± 157 N vs 939 ± 76 N, P = .023) grafts were also significantly improved. CONCLUSIONS: Independent reinforcement of soft-tissue grafts with suture tape strengthened the performance especially of tripled smaller-diameter grafts for ACLR with tibial screw fixation by significantly improving dynamic elongation at increased stiffness and ultimate strength. Quadrupled reinforced grafts showed no over-constraining and structurally behaved similarly to tripled grafts with reinforcement. CLINICAL RELEVANCE: Independent reinforcement for ACLR may provide an option for protecting autografts or allografts against irreversible lengthening during the maturation and remodeling phases of healing.

Intraoperative Preconditioning of Fixed and Adjustable Loop Suspensory Anterior Cruciate Ligament Reconstruction With Tibial Screw Fixation-An In Vitro Biomechanical Evaluation Using a Porcine Model.

PURPOSE: To evaluate the effect of preconditioning according to intraoperative workflow on initial tension and elongation behavior for femoral adjustable loop devices (ALDs) and closed loop devices (CLDs) in suspensory anterior cruciate ligament reconstruction (ACLR) with tibial screw fixation in a biomechanical in vitro study. METHODS: Three ACLR groups with tibial screw fixation were biomechanically tested in a full-construct setup using porcine tibias. Groups (n = 8 per group) varied by femoral fixation method and consisted of a CLD (group 3) and ALD fixation with (group 2) and without simulated intraoperative preconditioning (group 1). The change in tension after screw insertion and the displacement to restore the initial loading situation were measured. Grafts underwent dynamic cycling (1,000 cycles at 0.75 Hz) using both a position and a force control mode. RESULTS: Data are presented as mean [standard deviation]. Placement of an interference screw induced a graft tension loss of 62% (49.4 [0.4] N vs 19.0 [10.0] N, P < .001) by introducing a laxity of 0.53 [0.26] mm. Intraoperative preconditioning led to a higher initial load level (228.3 [19.8] N) compared with unconditioned ALD (156.1 [25.5] N, P < .001) and CLD groups (156.6 [12.8] N, P < .001) with less force decrease over position-controlled cyclic loading. Furthermore, initial (-0.22 [0.16] mm) and dynamic elongation (0.88 [0.23] mm) were reduced compared with the unconditioned ALD (0.65 [0.35] mm, P < .001; and 1.56 [0.19] mm, P < .001) and CLD groups (0.16 [0.26] mm, P < .001; and 1.64 [0.24] mm, P < .001). CONCLUSIONS: ACLR with femoral ALD fixation and intraoperative preconditioning allows for restoration of time-zero screw-imparted slack and leads to significantly reduced cyclic elongation in accordance with native ACL function. Both ALD and CLD control groups behaved similarly, with total elongation less than 3 mm including time-zero slack. CLINICAL RELEVANCE: Although the clinical relevance of time-zero graft tension loss is uncertain, the use of an ALD in concert with tibial screw fixation may be favorable to allow for tension optimization.

Evaluation of Skating Top Speed, Acceleration, and Multiple Repeated Sprint Speed Ice Hockey Performance Tests.

Bond, CW, Bennett, TW, and Noonan, BC. Evaluation of skating top speed, acceleration, and multiple repeated sprint speed ice hockey performance tests. J Strength Cond Res 32(8): 2273-2283, 2018-Skating speed, acceleration (ACC), and economy are important attributes related to ice hockey success and should ideally be tested on the ice in a reliable and time efficient manner that is accessible to coaches at all levels of the sport. The purpose of this study was to determine the reliability of certain on-ice tests and further, to use these results to evaluate changes in performance across a season. It was hypothesized that the tests' reliability would be excellent and that players would demonstrate improvements in performance associated with enhanced physiological conditioning. Forty male ice hockey players (16.2 ± 0.8 years, 1.76 ± 0.06 m, 73.7 ± 9.8 kg) completed top speed (TS), ACC, and multiple repeated sprint time (MRST) tests twice in the preseason (PRE 1 and 2) 1 week apart to examine reliability and once postseason (POST) to examine changes across the season. A high-speed video camera was used to time each test. The TS, ACC, and MRST demonstrated excellent within- and between-day reliability (interclass correlation coefficient [ICC] ≥ 0.83, typical error [TE] ≤ 2.6%) as well as within- and between-rater reliability (ICC ≥ 0.86, TE ≤ 0.5%). The team's TS and ACC were similar at all 3 assessments (p > 0.05), whereas MRST was faster at POST than at PRE 1 (p < 0.05). This test battery is reliable, time efficient, and inexpensive. All 3 tests may be used in team selection and identification of fatigue or overtraining. The MRST may be the most sensitive to short-term improvements related to ice hockey conditioning.

Comparison of Three Timing Systems: Reliability and Best Practice Recommendations in Timing Short-Duration Sprints.

Bond, CW, Willaert, EM, and Noonan, BC. Comparison of three timing systems: reliability and best practice recommendations in timing short-duration sprints. J Strength Cond Res 31(4): 1062-1071, 2017-With the importance placed on athletic speed, it is important to use a valid and reliable timing system, particularly in sprints of short duration. Unfortunately, many of the commonly used timing systems have not been rigorously evaluated. This study aimed to compare results from a single-beam infrared photocell (PC), single-beam laser with a microprocessor (LA), and a previously validated video camera (VC) sacrum-based timing system; and in doing so, determine these systems' reliabilities, and establish best practices for increasing reliability. It was hypothesized that PC and LA times would be different from VC times and show reduced reliability compared with VC. Fifteen athletes performed 5 repetitions of a 60-foot maximal effort sprint with split times recorded for the first and second half. Photocell and LA full-time and first-half split times were significantly slower than VC (p < 0.001), but almost identical for the second half split (p = 0.08). Repeated sprint analysis showed that VC tended to have smaller SD compared with PC and LA for first-half split (0.05 vs. 0.08 vs. 0.09 seconds, respectively) and total time (0.09 vs. 0.10 vs. 0.11 seconds, respectively). Time differences were more dependent on initial forward lean and varying body segments triggering the beam, than on a systematic instrument error. The increased variability of PC and LA systems dampen the ability to determine whether meaningful change has occurred. The VC system allows for very valid and reliable measurements of an athlete's sprint time, especially in distances <30 feet.

Reliability of Three Timing Systems Used to Time Short on Ice-Skating Sprints in Ice Hockey Players.

Bond, CW, Willaert, EM, Rudningen, KE, and Noonan, BC. Reliability of three timing systems used to time short on ice-skating sprints in ice hockey players. J Strength Cond Res 31(12): 3279-3286, 2017-Speed and acceleration are highly valued in ice hockey and frequently assessed using timing systems. Coaches must use reliable timing systems to assess these attributes, but many systems have not been thoroughly evaluated and the required number of sprint repetitions to obtain the coach's desired degree of reliability for a system may be impractical. This study aimed to compare the reliability of a single photocell (PC), a single laser with a microprocessor (LA), and a digital video camera (VC); and in doing so, evaluate the influence of completing additional sprint repetitions on each systems' reliability. We hypothesized that PC and LA would yield different times, have inferior reliability, and require a larger number of sprint repetitions to obtain the same degree of reliability compared with VC. Seventeen male ice hockey players completed 5 repetitions of a 9.15 m on ice-skating sprint timed simultaneously by PC, LA, and VC. The times obtained from VC were narrowly distributed around the mean compared with PC and LA and resulted in a mean sprint time approximately 0.05 and 0.07 second faster than PC and LA, respectively {PC: 1.74 second (95% confidence interval [1.72-1.76]); LA: 1.76 second [1.74-1.78]; VC: 1.69 second [1.67-1.70]}. When 2 sprint repetitions were completed, PC and LA typical error (TE) and smallest worthwhile difference (SWD) were 2.8- and 4.3-fold greater than VC, respectively. As more repetitions were completed, TE and SWD for PC and LA improved but remained approximately 2-fold greater than VC even when 5 repetitions were completed. With a smaller TE and SWD, VC was able to detect smaller "real" changes in a player's sprint performance over time compared with PC and LA.

The Hip in Ice Hockey: A Current Concepts Review.

Ice hockey is a fast, physical sport with unique associated biomechanical demands often placing the hip in forced and repetitive supraphysiological ranges of motion. Ice hockey players commonly endure and are sidelined by nebulous groin injury or hip pain. Underlying causes can be chronic or acute and extra-articular, intra-articular, or "hip-mimicking." This article serves to review common hip-related injuries in ice hockey. For each, we define the particular condition; comment on risk factors and preventive strategies; discuss key historical, physical examination, and imaging findings; and finally, suggest nonoperative and/or operative treatment plans.

Biomechanical Evaluation of an Adjustable Loop Suspensory Anterior Cruciate Ligament Reconstruction Fixation Device: The Value of Retensioning and Knot Tying.

PURPOSE: To evaluate the effects of retensioning and knot tying on the biomechanical properties of an adjustable loop anterior cruciate ligament (ACL) reconstruction device. METHODS: Testing consisted of 3 phases, which used both adjustable loop devices (ALD) and closed loop devices (CLD) tested under cyclic loading to 4,500 cycles. Phase 1 consisted of implant-only testing using cyclic loading from 50 to 250 N. Phase 2 used relatively unloaded cyclic loading of 10 to 250 N. Phase 3 used a tendon/bone/implant model. Subsets of the ALD implants were subjected to isolated retensioning, isolated knot tying, or a combination of both to allow for independent examination of these interventions. RESULTS: In phase 1, retensioning and knot tying reduced final ALD elongation by 60% (0.38 v 0.96 mm; P = .00004). In phase 2, retensioning and knot tying reduced final ALD elongation by 88% (0.51 v 4.22 mm, P = .014). In phase 3, retensioning and knot tying reduced final ALD elongation by 45% (1.5 v 2.7 mm; P = .001), which was half of the elongation of the CLD (3.0 mm; P = .0007). CONCLUSIONS: The ALD did demonstrate an increase in cyclic elongation as compared with the CLD during both extended loading conditions. The phase 1 ALD elongation (0.96 mm), while statistically greater than the CLD (0.52 mm), was likely not of clinical importance. However, the ALD elongation in phase 2 (4.22 mm) could be of clinical concern. Both of these increased elongations were eliminated by retensioning and knot tying. Furthermore, when evaluating in a graft-femur construct, retensioning and knot tying of the ALD reduced final cyclic elongation by 50% when compared with CLD. CLINICAL RELEVANCE: Retensioning and knot tying after initial reduction of the tendon graft with an adjustable loop ACL fixation device may help to further reduce concerns of loop slippage and displacement with cyclic loading during postoperative rehabilitation.

A simple video-based timing system for on-ice team testing in ice hockey: a technical report.

The purpose of this study was to describe and evaluate a newly developed on-ice timing system for team evaluation in the sport of ice hockey. We hypothesized that this new, simple, inexpensive, timing system would prove to be highly accurate and reliable. Six adult subjects (age 30.4 ± 6.2 years) performed on ice tests of acceleration and conditioning. The performance times of the subjects were recorded using a handheld stopwatch, photocell, and high-speed (240 frames per second) video. These results were then compared to allow for accuracy calculations of the stopwatch and video as compared with filtered photocell timing that was used as the "gold standard." Accuracy was evaluated using maximal differences, typical error/coefficient of variation (CV), and intraclass correlation coefficients (ICCs) between the timing methods. The reliability of the video method was evaluated using the same variables in a test-retest analysis both within and between evaluators. The video timing method proved to be both highly accurate (ICC: 0.96-0.99 and CV: 0.1-0.6% as compared with the photocell method) and reliable (ICC and CV within and between evaluators: 0.99 and 0.08%, respectively). This video-based timing method provides a very rapid means of collecting a high volume of very accurate and reliable on-ice measures of skating speed and conditioning, and can easily be adapted to other testing surfaces and parameters.

Arthroscopic Repair of the Acetabular Labrum Using an Anchor-First Modified Toggle Suture Technique.

The goal of acetabular labral repair is to restore stable contact between the labrum and acetabular rim while maintaining the anatomic suction seal. One of the challenges of labral repair is achieving proper in-round repair, so that the labrum contacts the femoral head in the native position. This technique article presents a repair method that allows for enhanced inversion of the labrum to assist with anatomic repair. Our modified toggle suture technique utilizes an anchor-first method and has various distinct technical advantages. We present an efficient and vendor-agnostic technique that allows for straight or curved guides. Similarly, the anchors may be all-suture or hard-anchor designs that accommodate suture sliding. This technique also utilizes a self-retaining hand-tied knot construct to facilitate preventing knots from migrating toward the femoral head or joint space.

THE EFFECT OF TIME AND SEX ON POST-ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION PSYCHOLOGICAL PATIENT REPORTED OUTCOME MEASURE SCORES.

CONTEXT: Low scores on psychological patient reported outcomes measures (PROMs), including the anterior cruciate ligament-return to sport after injury (ACL-RSI) and injury-psychological readiness to return to sport (I-PRRS), after anterior cruciate ligament (ACL) reconstruction (ACLR) have been associated with a maladaptive psychological response to injury and poor prognosis. OBJECTIVE: The purpose of this study was to assess the effect of time post-ACLR and sex on ACL-RSI and I-PRRS scores and generate normative reference curves. It was hypothesized that males would demonstrate higher ACL-RSI and I-PRRS scores than females in the first 1-year post-ACLR. DESIGN: Case series. SETTING: Outpatient sports medicine and orthopedic clinic. PATIENTS: 507 patients post-primary ACLR 12-to-30-years-old with 796 ACL-RSI or I-PRRS scores one or more times between 0- and 1-year post-ACLR (age at ACLR: 17.9 ± 3.0 y). MAIN OUTCOME MEASURES: An honest broker provided anonymous data from our institution's knee injury clinical database. Generalized additive models for location, scale, and shape and generalized least squares analyses were used to assess the effect of time post-ACLR and sex on ACL-RSI and I-PRRS scores. RESULTS: ACL-RSI and I-PRRS scores increased over time post-ACLR, and males had higher scores compared to females up until approximately five months post-ACLR with scores converging thereafter. CONCLUSIONS: Males report higher ACL-RSI and I-PRRS scores compared to females in the initial stages of rehabilitation, but scores converge between sexes at times associated with return to play following ACLR. Normative reference curves can be used to objectively appraise patients' ACL-RSI and I-PRRS scores at any time point post-ACLR. This may lead to timely identification of patients with scores or changes in scores over time post-ACLR associated with a maladaptive psychological response to injury and a poor prognosis and optimized ACLR outcomes.

Retrospective Longitudinal Evaluation of Male Firefighter's Body Composition and Cardiovascular Health.

OBJECTIVE: Describe firefighter body composition and cardiovascular health as a function of age. METHODS: 217 male firefighters with 1922 distinct evaluations over 23-years were included in this retrospective analysis. The firefighters had their height, mass, six-site skin-fold, blood pressure, and resting heart rate measured annually. Linear mixed models were used to analyze the effect of age. Significance was set to P < 0.05. RESULTS: With each 1-year increase in age, mass (0.42 kg, P < 0.001), body mass index (0.13 kg m-2, P < 0.001), body fat percentage (0.18%, P < 0.001), fat mass (0.25 kg, P < 0.001), and fat free mass (0.15 kg, P < 0.001) increased. Systolic blood pressure (-0.09 mm Hg, P = 0.263), diastolic blood pressure (0.05 mm Hg, P = 0.308), and resting heart rate (0.07 beats min-1, P = 0.291) did not change. CONCLUSIONS: Interventions to maintain healthy body composition are critical to reduce sudden cardiovascular related death risk.

Limb occlusion pressure for blood flow restricted exercise: Variability and relations with participant characteristics.

OBJECTIVE: Assess lower-extremity blood flow restricted exercise (BFR) limb occlusion pressure (LOP) variability and identify related intrinsic characteristics using a portable Delphi BFR system. DESIGN: Repeated measures. SETTING: Laboratory. PARTICIPANTS: Forty-two healthy males (n = 25) and females (n = 17) (25.8 ± 5.2 y, 1.76 ±0 .09 m, 78.9 ± 14.9 kg) completed two visits. Brachial artery blood pressure, thigh circumferences (TC), and LOP were measured supine. MAIN OUTCOME MEASURES: Linear mixed-effects models (LMM) and generalizability theory were used to evaluate LOP between legs and days, determine intrinsic characteristic relations, and assess random variance components. RESULTS: LOP was not different between legs (p = .730) or days (p = .916; grand mean = 183.7 mmHg [178.4, 189.1]). LOP varied significantly between participants (p = .011, standard error = 47.3 mmHg). 47% of LOP variance was between participants, 18% and 6% was within participants between days and legs, respectively, and 28% was associated with random error. The relative error variance was 14.4 mmHg. Pulse pressure (PP) (p = .005) and TC (p = .040) were positively associated with LOP. A LMM including PP and TC predicted LOP with a mean absolute difference of 11.1 mmHg [9.7, 12.6] compared to measured LOP. CONCLUSIONS: The relative error variance suggests that clinicians should measure LOP consistently for each patient to ensure BFR safety and effectiveness.

Repair results of 2-tendon rotator cuff tears utilizing the transosseous equivalent technique.

BACKGROUND: The purpose of this study was to examine the healing rate of 2-tendon rotator cuff tears repaired by the use of a transosseous-equivalent (TOE) suture bridge technique. MATERIALS AND METHODS: Forty-three patients with combined supraspinatus and infraspinatus tendon tears underwent arthroscopic repair using TOE technique. Forty of these patients were then evaluated by MRI and clinical exam at a minimum of 1-year follow-up to determine the rate of healing of the repair and clinical outcomes associated with healing. RESULTS: Eighty-three percent of the repairs demonstrated intact rotator cuff repairs at a mean of 16 months post-op. Larger tears (3.5 vs 2.8 cm) were associated with failure (P = .01), as was more advanced fatty infiltration (Goutallier 1.3 vs 0.3, P = .01). Age was not different between intact and nonintact tendons. Strength was the only clinical finding that differed between intact and nonintact tendons. CONCLUSION: Two-tendon tears of the rotator cuff can heal at a high rate with the use of TOE suture bridge repair technique. Furthermore, tear size and Goutallier grading were negatively correlated with postoperative healing. The incremental improvement in the rate of observed rotator cuff healing still does not translate to statistical differences in the objective shoulder scoring systems.

Intragame blood-lactate values during ice hockey and their relationships to commonly used hockey testing protocols.

This study evaluated the on ice blood-lactate values during a division 1 ice hockey game in an attempt to demonstrate the highly variable nature of the game. Our hypothesis was that intragame blood-lactate (BLa) values would be highly variable and related to shift length. Six men (age = 20.4 + 1.8 years, body mass 81.3 +8.7 kg) agreed to have fingerstick BLa samples taken at the completion of selected shifts (n = 35 samples) during the first and third periods of a division 1 ice hockey game. Shift length including work and rest intervals were also recorded for each of these shifts. Blood-lactate values ranged from 4.4 to 13.7 mmol.L with a mean value of 8.15 (+2.72) mmol.L. Shift length ranged from 55 to 145 seconds with individual work intervals within the shifts ranging from 29 to 102 seconds in length. Most shifts had either 1 or no play stoppages and rest to work intervals ranged from 0-1.66 (+0.53). These results further support the intense and variable nature of ice hockey and should help coaches develop more specific training and testing regimens to prepare for these demands. They also highlight the need for a validated and reliable test of repeated sprint ability for ice hockey players.

Effect of Jump Direction and External Load on Single-Legged Jump-Landing Biomechanics.

External load may increase an individual's risk of non-contact anterior cruciate ligament (ACL) injury during single-legged jump-landing (SLJL). This study evaluated the effects of jump direction and external load on hip and knee joint motion and time to stabilization (TTS) during SLJL. Seventeen active males (n = 8) and females (22.2 ± 3.0 y, 1.75 ± 0.08 m, 73.4 ± 12.0 kg) participated in this randomized, crossover designed study. Single-legged jump-landings performed in two conditions, including without external load (BW) and with a torso-worn weight vest equal to 10% of the participant's body weight (BW+10%), from backward, forward, medial, and lateral SLJL directions. Two-way repeated measures ANOVA did not identify any significant interactions (P > .01, η2: < .001 - .037), but some main effects for condition with small effect sizes were identified (P < .01, η2: .009 - .039). Several main effects for SLJL direction were identified with larger effect sizes (P < .01, η2: .010 - .574). This suggests SLJL direction may challenge different components of SLJL biomechanics, and that recreationally active, college-aged individuals may possess effective compensatory mechanisms that can mitigate the effect of BW+10%.

Biomechanical Evaluation of the Accuracy in Radiographic Assessment of Femoral Component Migration Measurement after Total Hip Arthroplasty.

INTRODUCTION: Implant subsidence is one criteria utilized to monitor for prosthesis loosening after total hip arthroplasty (THA) with initial implant subsidence assessment often done utilizing plain radiographs. The specific aim of this study was to identify the most reliable references when using plain radiographs to establish an image magnification with the goals being easy to use, inexpensive, reliable, and accurate. METHODS: Two femoral stem implants (stem lengths: 127 mm, 207 mm) were utilized to simulate hemiarthroplasty of the hip with composite femurs. Different combinations of femoral stem distances from the radiographic film (ODD), source-detector differences (SDD), hip rotation, and hip flexion were elected. Standardized anterior-posterior pelvis for each parameter combination setup were taken. Radiographic measurements (head diameter, stem length, stem seating length) were undertaken five times by three examiners. Radiographic image magnification factors were generated from two references (head diameter and stem length). Radiograph measurement reproducibility and stem seating length errors using these magnification factors were evaluated. RESULTS: High level of repeated measurements reliability was found for head diameter (99 ± 0%) and stem length (90 ± 7%) measurements, whereas seating length measurements were less reliable (76 ± 6%). Stem length error using the femoral head magnification factor yielded 11% accuracy. Stem seating length error using both magnification factors were not reliable (< 7% accuracy). All parameters, except SDD, showed significant effect on calibrated measurement error. CONCLUSION: Current methods of assessing the implant subsidence after THA are inaccurate and unreliable. Clinicians should recognize these limitations and be cautious when diagnosing implant stability using plain radiographs alone.

Is Plain Anterior-Posterior Radiograph of the Pelvis Adequate for Assessment of Radiographic Implant Migration Evaluation in Total Hip Arthroplasty?

Introduction: A commonly utilized method of measuring femoral stem migration in total hip arthroplasty (THA) on plain anteroposterior (AP) pelvis radiograph with referenced image magnification has not been rigorously evaluated. This study aims to validate the reproducibility of the methods used in this technique. Methods: A retrospective study of the standardized AP pelvis radiographs of patients who had undergone THA utilizing a Corail® femoral stem was performed from June 2012 through December 2017. Radiological evaluation (head diameter, stem length, and stem seating length) were undertaken at three clinical follow-up times. Each radiographic measurement of each radiograph was repeated five times. Outcomes investigated included inter- and intra-radiograph reproducibility evaluation and radiographic image magnification. The stem length error and stem subsidence were also evaluated. Results: Two hundred THA patients met the inclusion/ exclusion criteria. The intra-radiograph reproducibility of the stem length and head diameter measurements have at least "good" reproducibility with repeated measurements falling within 0.5 mm for both measurements. The reliability for femoral stem seating length measurements has "questionable/poor" reproducibility. The inter-radiograph reproducibility was, however, substantially lower. High level of unreliable measurements with values less than 0.0 mm for both femoral stem length errors (55%) and femoral stem subsidence (32%) measurements. Less than 45% accuracy (femoral stem length error: 33%; femoral stem subsidence: 44%) to within 3 mm error. Conclusions: This study demonstrates that the assessment of radiographic implant migration after THA made on a sequence of plain AP pelvis radiograph have poor reproducibility.Level of Evidence: III.

Comparing the Influence of Different Overhand/Underhand Stacking Combinations of Reversing Half-Hitches on Alternating Posts on Arthroscopic Knot Security.

INTRODUCTION: Previous literature demonstrated the importance of stacking at least three reversing half-hitches on alternating posts (RHAPs) following arthroscopic knot placement. However, RHAPs construction involves looping the suture in either an "overhand" or an "underhand" manner as it relates to the post, which may affect knot security. This study investigated the presently unidentified influence of different stacking combinations of three RHAPs and suture material on arthroscopic knot security. METHODS: Four different RHAPs stacking combinations were tied with three different suture materials. Ten knots of each configuration were tied using each suture material, resulting in 120 evaluated knots. A single load-to-failure test was performed. The mode of failure and mean ultimate clinical failure load were recorded. RESULTS: Different overhand/underhand stacking combinations of three RHAPs had a statistically significant effect on arthroscopic knot strength and security; however, all combinations surpassed the minimum ultimate clinical failure threshold. Knots constructed with either Force Fiber® or braided fishing line had mean ultimate clinical failure loads of greater than 200 N and most commonly failed due to suture material breakage (100%, 60 - 80% respectively). Conversely, FiberWire® demonstrated lower mean ultimate clinical failure loads and had a higher incidence of elongated but intact failure (60 - 90%). CONCLUSION: Different overhand/underhand stacking combinations of three RHAPs yielded an arthroscopic knot capable of secure tissue fixation. A significant effect was observed for suture materials on the knot strength. This study increases our understanding of suitable RHAPs construction following arthroscopic knot placement that can lead to improving the ultimate clinical failure loads of constructed arthroscopic knots observed between orthopedic surgeons.

Blood Flow Restriction Resistance Exercise as a Rehabilitation Modality Following Orthopaedic Surgery: A Review of Venous Thromboembolism Risk.

Synopsis Restoration of skeletal muscle mass and strength is critical to successful outcomes following orthopaedic surgery. Blood flow restriction (BFR) resistance exercise has emerged as a promising means of augmenting traditional low-intensity physical rehabilitation exercise and has yielded successful outcomes in a wide range of applications. Though BFR is well tolerated and safe for most individuals, patients who have undergone orthopaedic surgery may be an exception, due to their heightened risk for venous thromboembolism (VTE). While the pathogenesis of VTE is multifactorial and specific to the individual, it is commonly described as a combination of blood stasis, endothelial injury, and alterations in the constituents of the blood leading to hypercoagulability. The collective literature suggests that, given the pathogenic mechanisms of VTE, limited use of a wide, partially occluding cuff during resistance exercise should be low risk, and the likelihood that BFR would directly cause a VTE event is remote. Alternatively, it is plausible that BFR may enhance blood flow and promote fibrinolysis. Of greater concern is the individual with pre-existing asymptomatic VTE, which could be dislodged during BFR. However, it is unknown whether the direct risk associated with BFR is greater than the risk accompanying traditional exercise alone. Presently, there are no universally agreed-upon standards indicating which postsurgical orthopaedic patients may perform BFR safely. While excluding all these patients from BFR may be overly cautious, clinicians need to thoroughly screen for VTE signs and symptoms, be cognizant of each patient's risk factors, and use proper equipment and prescription methods prior to initiating BFR. J Orthop Sports Phys Ther 2019;49(1):17-27. Epub 12 Sep 2018. doi:10.2519/jospt.2019.8375.