bluuebunny/crossref_metadata_2025 huggingface dataset:
Mass Screening of Youth Athletes for High Risk Landing Patterns using a Portable and Inexpensive Motion Sensor Device
Authors: Sherman Seth Lawrence , Gulbrandsen Trevor R. , Miller Scott M. , Guess Trent , Willis Bradley W. , Blecha Kyle M. , Huo Zhiyu , Skubic Marjorie , Gray Aaron D.
Published: July 2016

Objectives:

Biomechanical factors such as dynamic knee valgus predispose young athletes to lower extremity injury including tears of the anterior cruciate ligament (ACL). Identifying these risk factors may allow for targeted injury prevention strategies. Our prior work has validated the Microsoft Kinect vs. Vicon to detect knee-ankle separation ratio (KASR) during the drop vertical jump test (DVJ). Our hypothesis is that screening with the Microsoft Kinect will be safe, efficient, and provide information to help detect injury risk in youth athletes.

Methods:

A total of 180 healthy high school athletes, ages 14-18 (80 males and 100 females, age of 16.9 ± 1.31 and BMI of 22.8 ± 3.7) participated in this study. Each subject performed three successful DVJ (Fig. 1). We used an inexpensive, portable motion sensor device to measure the KASR, which captures the ratio of the horizontal distance between knees to the horizontal distance between ankles. From previous studies, a KASR value <1 indicates dynamic valgus, while being below 0.6 is considered severe risk. Demographic information and measurements for KASR on initial contact and peak flexion were analyzed statistically.

Results:

Using two motion sensor device stations, it took 1.5 minutes to screen and test each subject. There were no injuries that occurred during the screening process. Our results showed a statistically significant difference between male and female KASR for both initial contact (p<0.001) and peak flexion (p<0.001). Sixty out of the 100 female subjects (60%) tested positive for valgus (9 initial contact KASR, 1 peak flexion KASR, 50 both initial contact and peak flexion KASR) with two subjects screening for severe risk (KASR<0.6). The average KASR for females was 1.01 (peak flexion) and 0.967 (initial contact). Eighteen out of the 80 male subjects (22.5%) tested positive for valgus (6 initial contact KASR, 2 peak flexion KASR, 10 both initial contact and peak flexion KASR) with no male subjects screening positive for severe risk. The average KASR for males was 1.26 (peak flexion) and 1.13 (initial contact). Comparing males and females that screened positive for KASR, there was a significant gender difference between the KASR at initial contact with females exhibiting more valgus than males (p<0.001) (Table 1).

Conclusion:

Our findings suggest that a portable and inexpensive motion analysis device can detect dynamic valgus during the DVJ in youth athletes. Large scale screening for dynamic valgus was safe and efficient. Known gender disparities between male and females for neuromuscular imbalances were identified. Potential use of this information for targeted injury prevention is appealing and requires further investigation.
Responsiveness Comparison of the EQ-5D, PROMIS Global Health, And VR-12 Questionnaires In Knee Arthroscopy
Authors: Oak Sameer , Strnad Greg , Bena James , Farrow Lutul D. , Parker Richard D. , Jones Morgan H. , Spindler Kurt P.
Published: July 2016

Objectives:

The EQ-5D, PROMIS 10 Global Health, and VR-12 are generic patient reported outcome (PRO) questionnaires that assess and report patient general health and wellbeing. In choosing a PRO to track patient general health status, it is necessary to consider which measure will be the most responsive to change after treatment. To date, no studies exist comparing the responsiveness among the EQ-5D, PROMIS 10 Global Health, and VR-12. We sought to determine which of the generic PROs were most responsive internally and externally in the setting of knee arthroscopy.

Methods:

50 patients undergoing knee arthroscopy were surveyed with a PRO questionnaire pre-operatively and at least 3 months post-operatively. PROs included the EQ-5D, EQ-5D visual analog scale, PROMIS 10 Global Health (PROMIS 10) Physical and Mental components, VR-12 Physical and Mental components, and the Knee injury and Osteoarthritis Outcome Score (KOOS) Pain scale. Internal responsiveness was evaluated by performing paired t-tests on the changes in measures and calculation of two measures of effect size: Cohen’s D and standardized response mean (SRM). External responsiveness was evaluated by calculating and comparing Pearson correlation measures between the disease specific reference KOOS Pain and the general PROs EQ-5D, PROMIS 10, and VR-12 changes. General PRO responsiveness measures were compared head to head with the cocor package in R software.

Results:

Patients were surveyed pre-operatively and a mean of 3.6 months post-operatively with 90% follow-up. For internal responsiveness, the EQ-5D, VR-12 Physical, and PROMIS 10 Physical scales showed a statistically significant improvement in score after treatment and effect size statistics with moderate change (Cohen’s D and SRM between 0.5-0.8). Assessing external responsiveness, the EQ-5D, VR-12 Physical, and PROMIS 10 Physical instruments showed the highest correlation with the disease specific reference measure, KOOS Pain (Table 1). For both internal and external responsiveness, the EQ-5D, VR-12 Physical, and PROMIS 10 Physical instruments showed significantly higher responsiveness compared to the other general PRO measures, but no statistical differences among themselves.

Conclusion:

There is no statistical difference between the EQ-5D, VR-12 Physical, and PROMIS 10 Physical instruments in terms of internal or external responsiveness to change. In tracking longitudinal patient health, researchers and administrators have the flexibility to choose any of the general PROs among the EQ-5D, VR-12 Physical, and PROMIS 10 Physical instruments. We recommend that any study tracking PROs in knee arthroscopy include one of these generic instruments.
Dynamic Loading Assessment at the Fifth Metatarsal in Elite Athletes with a history of Jones Fracture
Authors: Hunt Kenneth , Goeb Yannick
Published: July 2016

Objectives:

Fractures of the proximal metaphysis of the fifth metatarsal (i.e., Jones fractures) are common in the athletic population and frequently require surgical fixation to optimize healing rates and return to sport. Subtle hindfoot varus alignment, which likely results in greater forces at the fifth metatarsal, has been associated with increased risk of Jones fractures due to presumed increase in forces on the lateral foot. The goal of the present study was to dynamically assess plantar pressure loads at the fifth metatarsal in elite athletes with a history of Jones fracture. We hypothesize that athletes who have suffered Jones fractures will apply significantly higher loads at the fifth metatarsal base during athletic activities compared to matched uninjured athletes.

Methods:

Sixteen elite, competitive athletes were recruited to participate. Eight athletes had a history of Jones fracture and eight age, gender and position-matched athletes without a history of foot injury were recruited as controls. While wearing calibrated, wireless pressure mapping insoles, all athletes performed a standardized series of athletic movements including walking, running and cutting. Tests were repeated with the patient’s standard corrective insole. Peak pressure, mean pressure, maximum force, and force-time integral (i.e., impulse) were recorded for each activity. Comparison between groups was performed using a paired Wilcoxon Sign Rank test.

Results:

Athletes with a history of Jones fracture showed a significantly increased peak pressure (183 ±23 kPA vs. 138±7 kPA), mean pressure (124±14 kPA vs. 95±4 kPA), and maximum force (15±1.2%BW vs. 12±1.2%BW) at the fifth metatarsal base during walking and running compared to uninjured matched controls (all P<0.05). Use of the corrective orthotic insole did not significantly reduce peak or mean pressure, maximum force, or impulse at the fifth metatarsal base during running or cutting.

Conclusion:

Athletes with a history of Jones fracture exert significantly increased peak and mean forces at the base of the fifth metatarsal during common athletic activities. Standard corrective orthoses do not appear to offload this region in all cases. These increased loads may contribute to the development of stress injury to the fifth metatarsal during repetitive loading, and ultimately fracture of the bone. Identifying patients at risk for Jones fracture using dynamic loading assessment may facilitate an injury prevention program. Further study of orthotic devices, training programs, shoe wear, and devices designed to offload the fifth metatarsal is necessary.
Physeal Disruption During ACL Reconstruction in Skeletally Immature Patients
Authors: Cruz Aristides Ignacio , Lakomkin Nikita , Fabricant Peter D. , Lawrence John Todd R.
Published: July 2016

Objectives:

The purpose of this study was to radiographically assess differences in distal femoral physeal disruption between transtibial and independent femoral tunnel drilling techniques following ACL reconstruction in skeletally immature patients.

Methods:

A retrospective, matched comparative cohort study was performed of skeletally immature patients who underwent transphyseal ACL reconstruction between January 1, 2008 and March 31, 2011. All skeletally immature patients between ten and fifteen years old who underwent independent femoral tunnel drilling and had adequate baseline and post-operative radiographs were analyzed. These patients were matched with a transtibial technique cohort based on age and sex. Demographic characteristics and peri-operative metrics were collected. Radiographic measurements were recorded from pre-operative MRI and post-operative plain radiographs.

Results:

Twenty patients were analyzed. Between groups, there were significant differences between independent tunnel drilling and transtibial tunnel drilling in the estimated area of physeal disruption (1.64 cm2 vs. 0.74 cm2, P<0.001), femoral (32.1º vs. 72.8º, P<0.001) and tibial (50.1º vs. 60.5º, P=0.003) tunnel angles, medial/lateral location of the femoral tunnel (24.2 mm vs. 36.1 mm from lateral cortex, P=0.001), and distance from the lateral aspect of the distal femoral physis and the femoral tunnel exit (4.7 mm vs. 26.7 mm from the perichondrial ring, P<0.001), respectively. All patients who underwent femoral tunnel drilling at an angle of less than 25º from the transverse axis experienced a greater than 6% disruption of physeal area. There was a significant inverse correlation between femoral tunnel angle and estimated area of femoral physeal involvement (r=-0.8255, P=0.003).

Conclusion:

With femoral tunnel drilling techniques that create more oblique tunnels, the area of distal femoral physeal damage is larger, more eccentric and closer to the perichondrial ring. Since most studies noting the safety of transphyseal ACL reconstruction have utilized a vertical femoral tunnel, surgeons should be aware that if an independent femoral tunnel drilling technique is utilized during transphyseal ACL reconstruction, the physis is at greater risk when drilling at more horizontal angles. Angles greater than 25º from the transverse axis may safely create <6% physeal area damage.
Subsequent Surgery after Revision Anterior Cruciate Ligament Reconstruction
Authors: Ding David , Group Mars
Published: July 2016

Objectives:

Failure or reinjury after anterior cruciate ligament (ACL) reconstruction can lead to recurrent instability and concomitant intra-articular injuries. While revision ACL reconstruction (rACLR) can be performed to restore knee stability and improve patient activity level, outcomes after these surgeries are reported to be inferior to primary ACL reconstruction. Further reoperation after rACLR can have an even more profound effect on patient satisfaction and outcome. Yet, there is a current lack of information regarding the rate and risk factors for subsequent surgery after rACLR.

Methods:

1205 patients who underwent rACLR were enrolled between 2006 and 2011, comprising the prospective cohort. Two-year questionnaire follow-up was obtained on 989 (82%), while telephone follow-up was obtained on 1112 (92%). If a patient reported having a subsequent surgery, operative reports detailing the subsequent procedure(s) were obtained and categoriezed. A repeated meaures ANOVA was used to reveal significatnt differences in patient reported outcomes. Multivariate regression analysis was performed to determine independent risk factors for reoperation.

Results:

One hundred and twenty-two patients (10.1%) underwent a total of 172 subsequent procedures on the ipsilateral knee at 2-year follow-up. Of the reoperation procedures, 26.7% were meniscus procedures (69% meniscectomy, 26% repair), 18.6% were subsequent rACLR, 17.4% were cartilage procedures (61% chondroplasty, 17% microfracture, and 13% mosaicplasty), 10% hardware removal, and 9.3% were procedures for arthrofibrosis such has lysis of adhesions and synovectomy. Patients who had reoperations had significantly lower IKDC, KOOS symptoms and pain scores, and WOMAC stiffness scores at two-year follow up. Multivariate analysis revealed that patients under 20 years old were 2.1 times more likely than patients aged 20-29 to have a reoperation. Use of allograft at the time of rACLR and staged revision (bone grafting of tunnels before rACLR) were also significant predictors for need for reoperation within 2 years. Patients with grade IV cartilage damage seen during rACLR were 47% less likely to undergo subsequent operations within 2 years. Gender, BMI, smoking history, Marx activity score, technique for femoral tunnel placement and meniscal tear or meniscal treatment at the time of rACLR showed no significant effect on reoperation rate.

Conclusion:

There is a significant reoperation rate following rACLR at two years (10.1%). The most prevalent reoperations involved meniscal procedures. Independent risk factors for subsequent surgery on the ipsilateral knee include age<20 years old, a staged revision and use of allograft tissue at the time of rACLR.
Predictors of Outcomes after Arthroscopic Double-row Rotator Cuff Repair in 155 Cases
Authors: Katthagen Jan Christoph , Millett Peter J. , Espinoza-Ervin Christopher , Horan Marilee P. , Ho Charles P. , Warth Ryan J. , Dornan Grant
Published: July 2016

Objectives:

The purpose of this study was to analyze predictors of clinical outcomes of knotted versus knotless double-row self-reinforcing rotator cuff repairs of full-thickness rotator cuff tears with propensity score matching.

Methods:

Patients with arthroscopic repair of full-thickness rotator cuff tears involving the supraspinatus tendon using either a knotted or knotless linked, self-reinforcing double-row technique were included in the study. Preoperative subjective evaluation was performed using the ASES and SF-12 PCS scores. After a minimum two-year follow-up period, ASES and SF-12 PCS scores were collected again along with the SANE score, the QuickDASH score, and patient satisfaction. All data were collected prospectively and retrospectively reviewed. Postoperative ASES and SF-12 PCS scores were then modeled using inverse propensity score weighting in a multiple linear regression model (MLR) with multiple imputations. Age, sex, baseline ASES score, length of follow-up, number of anchors, worker’s compensation, previous cuff repair, and double-row repair technique (knotted or knotless) were the covariates used in this model.

Results:

155 shoulders in 151 patients (109 men, 42 women; mean age at time of surgery 59±10 years) were eligible for inclusion. Outcomes data were available for 130 of 148 shoulders (87.8%) after exclusion of seven shoulders (4.5%) that underwent revision rotator cuff repair before final follow up (n=33/39 in the knotted group [84.6%]; n=97/109 [88.9%] in the knotless group).The mean follow-up was 2.9 years (range, 2.0-5.4 years). Overall, postoperative outcomes scores were significantly improved when compared to preoperative baselines (p<0.05), with a median postoperative ASES score of 97 for the entire cohort. Our model showed that previous rotator cuff repair had a significant negative effect on postoperative ASES (β = -12.7, p<0.001) and SF-12 PCS scores (β = -5.0, p = 0.036). A workers’ compensation claim (β = -10.6, p = 0.007) also had a significant negative effect on postoperative ASES scores. Higher baseline ASES score (β = +0.14, p = 0.025) positively influenced ASES outcomes. Use of a knotless technique also had a positive effect on postoperative scores (β = +2.5, p = 0.235). Age, gender, the length of follow-up and the numbers of anchors did not influence the outcomes (Table 1).

Conclusion:

Excellent clinical outcomes can be achieved a minimum of two years following arthroscopic repair of full-thickness rotator cuff tears using either the knotted or knotless linked double-row technique. Negative predictors of outcome include low preoperative ASES score, previous rotator cuff repair, and a workers’ compensation claim. Knotless double-row rotator cuff repair had a non-significantly positive effect on the postoperative ASES score compared to the knotted double-row suture bridge technique.
Pharmacological Inhibition of Myostatin Protects Against Atrophy and Weakness after ACL Tear
Authors: Wolfe Caroline Nicole , Gumucio Jonathan P. , Grekin Jeremy , Khouri Roger Karl , Bedi Asheesh , Mendias Christopher
Published: July 2016

Objectives:

Many patients who suffer ACL tears have persistent atrophy and weakness even after rehabilitation. Myostatin is a cytokine that directly induces muscle atrophy, and previous studies using rodent models and patients have demonstrated an up regulation of myostatin after ACL tear. Using a preclinical rat model, our objective was to determine if the use of a bioneutralizing antibody against myostatin could prevent muscle atrophy and weakness after ACL tear.

Methods:

This study was approved by our IACUC. The left ACL and was transected in 3mo-old male F344 rats. At the time of surgery rats received a single IP injection of either a bioneutralizing antibody against myostatin (10B3, GlaxoSmithKline) or a sham IgG (E1-82.15, GlaxoSmithKline) at a dose of 10mg/kg. Rats (N=8 per group) were sacrificed and tissue was harvested 7 days or 21 days after tear. Contractile force measurements of the extensor digitorum longus (EDL) were performed. The size of muscle fibers in histological sections from the EDL and distal vastus lateralis were also measured. RNA was isolated from the distal rectus femoris and gene expression analysis was performed with RT-qPCR. The expression of each gene was normalized to b actin, and further normalized to the expression of muscles from control, uninjured rats. A two-way ANOVA (alpha=0.05) followed by Holm Sidak post hoc sorting was used to evaluate the effect of time and treatment on measured parameters.

Results:

Inhibition of myostatin resulted in an increase in muscle fiber size at the 21D time point compared to all other groups (Table 1). While both the sham antibody and myostatin antibody groups increased maximum isometric force production from 7D to 21D, the myostatin antibody group at 21D had a further increase in force compared to the 21D sham group. The muscle E3 ubiquitin ligases atrogin-1 and muscle ring finger 1 (MuRF-1) are the major rate limiting enzymes in muscle protein degradation, and inhibition of myostatin resulted in decreases in the expression of these genes at 7D (Figure 1A). Additionally, IGF-1Ea and IGF-1Eb which are important growth factors that induce muscle protein synthesis, were elevated in the myostatin antibody groups at the 21D time point. For genes related to fibrosis (Figure 1B), although there was no significant difference in MMP-2, there was a significant decrease of MMP-8 expression in the 21D MSTN group when compared to the 21D sham. There were also increases in the expression of TIMP-1 and 2 in the 21D MSTN group.

Conclusion:

In a preclinical rat model, the targeted inhibition of myostatin protected leg muscles from muscle atrophy and improved force production after ACL tear. While the mechanism of action is not entirely clear, it is possible that the inhibition of myostatin preserves strength by limiting the expression of proteolytic enzymes in the post-acute atrophy phase and increasing protein synthesis in later phases.
Biomarker Changes in ACL Deficient Knees Compared with Contralaterals
Authors: Strauss Eric Jason , Kaplan Daniel James , Jazrawi Laith M.
Published: July 2016

Objectives:

Introduction: Though outcomes following ACL reconstruction are largely positive, patients’ post-operative recovery is highly variable, and is typically based off generalized timetables derived from population data. In an attempt to individualize prognostic estimates and establish how biomarker concentrations may change with injury, we sampled knee joint synovial fluid from patients with ACL tears with and without associated cartilage injuries and compared biomarker concentrations to samples obtained from the contralateral non-injured knee.

Methods:

480 patients indicated for knee arthroscopy had samples drawn to form a synovial fluid database. If no injury history or symptoms were present in the contralateral knee, samples were drawn as well. For the current study, only patients that had confirmed ACL injury at the time of arthroscopy were included. Associated cartilage injury location, size and depth was documented. Synovial fluid samples were centrifuged, and the concentrations of 20 biomarkers were determined using a multiplex magnetic bead immunoassay. Concentrations were then compared between the three study groups (ACL tear with cartilage injury, ACL tears without cartilage injury, and healthy contralateral knees) using a Welch ANOVA test with pairwise comparisons.

Results:

The study included samples from 132 knees: 34 ACL tears without cartilage injury (mean age 34.0 years); 28 ACL tears with cartilage injury (mean age 36.3 years), and 72 contralateral knees (41.1 years). ANOVA testing demonstrated significant differences among groups for: MMP-3 (p>001); TIMP-1 (p=.001); TIMP-2 (p=.015); FGF-2 (p=.011); IL-6 (p=.001); and MIP-1b (p=.001). Pairwise comparisons demonstrated no significant differences between ACL tears with, and without cartilage damage, but did show both types of ACL tears had significantly higher concentrations of MMP-3, TIMP-1, IL-6, and MIP-1b than contralaterals. ACL tears without cartilage damage had significantly lower concentrations of TIMP-2 and FGF-2 (13) than contralaterals (Table 1).

Conclusion:

The course from surgery to symptomatic relief and functional improvement following ACL reconstruction is highly variable. Data from the current study demonstrated that cytokine concentrations are significantly different between ACL tears (+/- cartilage damage) and healthy knees. These validated differences can help establish synovial fluid biomarker analysis as a method for injury stratification ultimately providing patient-specific prognostic data.
Engaging Hill-Sachs Defects
Authors: Burns David , Chahal Jaskarndip , Shahrokhi Shahram , Henry Patrick , Wasserstein David , Whyne Cari , Theodoropoulos John S. , Ogilvie-Harris Darrell , Dwyer Tim
Published: July 2016

Objectives:

Anatomic studies have demonstrated that bipolar glenoid and humeral bone loss have a cumulative impact on shoulder instability, and that these defects may engage in functional positions depending on their size, location, and orientation, potentially resulting in failure of stabilization procedures. Determining which lesions pose a risk for engagement remains a challenge, with arthroscopic assessment and Itoi’s 3DCT based glenoid track method being the accepted approaches at this time. The purpose of this study was to investigate the interaction of humeral and glenoid bone defects on shoulder engagement in a cadaveric model. Two alternative approaches to predicting engagement were evaluated; 1) CT scanning the shoulder in abduction and external rotation 2) measurement of Bankart lesion width and a novel parameter, the intact anterior articular angle (IAAA), on conventional 2D multi-plane reformats. The results of these two approaches were compared to the results obtained using Itoi’s glenoid track method for predicting engagement.

Methods:

Hill-Sachs and Bony Bankart defects of varying size were created in 12 cadaveric upper limbs, producing 45 bipolar defect combinations. The shoulders were assessed for engagement using cone beam CT in various positions of function, from 30 to 90 degrees of both abduction and external rotation. The humeral and glenoid defects were characterized by measurement of their size, location, and orientation. Diagnostic performance measures for predicting engagement were calculated for both the abduction external rotation scan and 2D IAAA approaches using the glenoid track method as reference standard.

Results:

Engagement was predicted by Itoi’s glenoid track method in 24 of 45 specimens (53%). The abduction external rotation CT scan performed at 60 degrees of glenohumeral abduction (corresponding to 90 degrees of abduction relative to the trunk) and 90 degrees of external rotation predicted engagement accurately in 43 of 45 specimens (96%), with sensitivity and specificity of 92% and 100% respectively. A logistic model based on Bankart width and IAAA provided a prediction accuracy of 89% with sensitivity and specificity of 91% and 87%. Inter-rater agreement was excellent (Kappa = 1) for classification of engagement on the abduction external rotation CT, and good (intraclass correlation = 0.73) for measurement of IAAA.

Conclusion:

Bipolar lesions at risk for engagement can be identified using an abduction external rotation CT scan at 60 degrees of glenohumeral abduction and 90 degrees of external rotation, or by performing 2D measurements of Bankart width and IAAA on conventional CT multi-plane reformats. This information will be useful for decision making in the setting of bipolar bone defects prior to shoulder stabilization.
MRI Abnormalities Are Common In Little League Player’s Elbows
Authors: Pennock Andrew T. , Roocroft Joanna Helena , Bastrom Tracey P. , Kruk Peter
Published: July 2016

Objectives:

Youth baseball is extremely popular, but it has been associated with elbow pain and pathology. The purpose of this study was to examine pre- and post-season Magnetic Resonance Imaging (MRI) changes in Little League baseball players and correlate these findings with the players’ throwing history and physical exams.

Methods:

A prospective study of Little League players age 10 -13 years was performed. Players were recruited prior to the start of the season and underwent bilateral elbow MRI. All players underwent a physical exam and responded to a questionnaire addressing their playing history and arm pain. At the end of the season, the players underwent repeat physical exam and MRI of their throwing arm. MRIs were read by two blinded radiologists. During the season, player statistics including innings played and pitch counts were recorded. Physical exam findings and players statistics were compared between subjects with and without MRI changes utilizing chi-square and ANOVA techniques.

Results:

Twenty-six players were enrolled. On pre-season MRI, nine players (35%) had 12 positive MRI findings; edema of the medial epicondyle (ME) apophysis (7), fragmentation of ME (2), and edema of the sublime tubercle (3). The two factors associated with a positive MRI were year round play (47% vs 11%, p<0.01) and working with a private coach (71% vs 21%, p=0.02). A history of pain was also associated with year round play and a private coach (p<0.05). Loss of internal rotation was associated with an abnormal MRI (p = 0.04). Post-season, 25 players returned for follow-up. Ten players (40%) had an abnormal MRI of which 8 (32%) had new/worsening findings. There was a significant difference in distal humeral physeal width measured pre- to post-season (1.54 mm vs 2.31 mm p<0.001). There was a significant decrease in internal rotation measured pre- to post-season of the shoulder in all patients regardless of MRI findings (62° vs 43°, p=0.001). Pitch counts, player position, and throwing curve balls/sliders were not significantly associated with pain or MRI abnormality post season (p >0.10). Descriptively, 60% of self-reported pitchers/catchers had post season MRI findings versus 40% of other field positions (p=0.3).

Conclusion:

Pre-season and post-season MRI abnormalities of the medial elbow are common in Little League baseball players. While Little League pitching guidelines are intended to decrease overuse injuries, our data indicate that further refinement of these guidelines addressing year round play, pain and private coaching should be considered.
3-D Computed Tomography (CT) Comparison Of The Pre-injury And Post-repair Syndesmosis To Assess Anatomic Reduction
Authors: Turnbull Travis L. , Schon Jason , Williams Brady T. , Venderley Melanie , Dornan Grant , Backus Jonathon D. , LaPrade Robert F. , Clanton Thomas O.
Published: July 2016

Objectives:

Historically, unstable injuries to the distal tibiofibular syndesmosis have been repaired with syndesmotic screws. However, newer repair techniques with inherently flexible implants, including suture-button constructs, may be less susceptible to malreduction and more reliably restore the native anatomy. The purpose of this study was to compare the anatomic accuracy of reduction between a syndesmotic screw and suture-button constructs for syndesmosis repair using a pre-injury and postoperative 3-D model assessment. We hypothesized significant differences would be observed among repair techniques and suture-button constructs would most accurately restore the pre-injury syndesmotic volume.

Methods:

Twelve matched pairs of cadaveric specimens were dissected to identify the syndesmotic ligaments. Specimens were imaged with CT prior to the creation of a complete syndesmosis injury. The disrupted syndesmosis of each specimen was subsequently reduced using one of three randomly assigned repair techniques: (1) tri-cortical syndesmosis screw (3.5 x 50 mm), (2) one suture-button construct and (3) two suture-button constructs. Specimens were imaged postoperatively with CT. 3-D models of all scans and tibiofibular joint space volumes were created to assess restoration of the native syndesmosis (Figure 1). Volumetric joint space measurements were made starting at the distal aspect of the tibiofibular articulation and extended proximally with four 1 cm sections measured separately.

Results:

For each of the three fixation methods, the adjusted least squares means for total post-operative volumes of the syndesmosis were significantly decreased relative to the intact state. Total overall decreases in volume compared to the intact state for the one suture-button construct, two suture-button constructs, and syndesmotic screw were -561mm3, -964mm3, and -377mm3, respectively. Fixation with one suture-button construct was not significantly different from screw or two suture-button fixations. However, the total decrease in volume was significantly greater with the two suture-button repair compared to screw fixation ( p < .05).

Conclusion:

The most important finding of this study was that fixation with one suture-button construct was not significantly different from screw or two suture-button fixations. All repairs significantly reduced the volume of the syndesmosis postoperatively compared to the intact state. Fixation with two suture-buttons resulted in significantly greater decreased volume than screw fixation. The data from the present study suggests that syndesmotic over-compression at time zero, particularly when using multiple suture-button implants, may be another potential factor contributing to malreduction of syndesmosis injuries that deserves further investigation.
Differences in Acetabular Rim Thickness in Patients with Unilateral Symptomatic Pincer-Type Femoroacetabular Impingement
Authors: Weber Alexander E. , Kuhns Benjamin , Cvetanovich Gregory , Inoue Nozomu , Nho Shane Jay
Published: July 2016

Objectives:

The objective of this study was to identify the location and magnitude of difference in acetabular rim morphology between the symptomatic and asymptomatic acetabula in a cohort of patients with symptomatic unilateral pincer-type FAI.

Methods:

After IRB approval, computed tomography (CT) scans of 43 patients (22 males, 21 females) diagnosed with unilateral pincer-type FAI were obtained. CT images of both hips were imported in DICOM format and segmented into 3-dimensional (3D) hemi-pelvises using 3D reconstruction software (Mimics, Materialise, Leuven, Belgium). The point-cloud data of the asymptomatic hemi-pelvis was mirrored onto the symptomatic side. Protrusion of the symptomatic side was recorded as a positive value and appeared as red on the color map (Figure 1). Data was collected in 3° intervals and analyzed by quadrant using the clock face method; reflecting the 12-3, 3-6, 6-9, and 9-12 o’clock positions.

Results:

The symptomatic acetabular rim was on average 0.39 ± 0.36 mm thicker than the corresponding location on the asymptomatic rim. When the acetabular clock face was broken up into quadrants, reflecting the 12-3, 3-6, 6-9, and 9-12 o’clock positions, the 12-3 o’clock position demonstrated the greatest difference between symptomatic and asymptomatic sides (Table 1). The 12-3 o’clock quadrant demonstrated significantly greater difference between symptomatic and asymptomatic sides (0.53±0.22 mm) as compared to the 3-6 o’clock position (0.39±0.27 mm; p=0.006), the 6-9 o’clock position (0.34±0.05 mm; p<0.001), and the 9-12 o’clock position (0.33±0.03; p<0.001). There was no correlation between gender and magnitude of difference at any location.

Conclusion:

Small changes in acetabular rim morphology, on the order of 0.5 mm or less can be the difference between symptomatic pincer-type FAI and the asymptomatic state. Knowledge of the healthy, unaffected side in unilateral FAI may provide a better template for rim recession rather than broadly applying previously described anterior or lateral center-edge angle parameters.
The Effect of Purified Multi-potent Human Bone-marrow Derived Mesenchymal Stem Cells on Rotator Cuff Tendon Healing in an Athymic Rat
Authors: Degen Ryan , Carbone Andrew , Carballo Camilia , Zong Jianchun , Chen Tony , Ying Lilly , Lebaschi Amir , Deng Xiang-Hua , Rodeo Scott A.
Published: July 2016

Objectives:

Bone marrow concentrates are being used to augment soft tissue healing. However, only 0.01% of these cells meet the criteria of a mesenchymal stem cell (MSC), which likely accounts for the variability in reported results. Previous studies using an established rat rotator cuff repair model have demonstrated that bone marrow-derived MSCs had no effect on healing. In this study we evaluated the effect of purified human MSCs on rotator cuff healing in an athymic rat model. Our hypothesis is that purified human MSCs added to the repair site will improve biomechanical strength and fibrocartilage formation of the healing tendon.

Methods:

Fifty-two athymic rats underwent unilateral detachment and repair of the supraspinatus tendon with either fibrin glue (control) or fibrin glue with 106 hMSCs (experimental) applied at the repair site. Flow cytometry verified the stem cell phenotype of the cells as CD73+, CD90+, CD105+, CD 14-, CD34- and CD45-. Rats were sacrificed at 2 and 4 weeks, with 10 used for biomechanical testing and 3 for histologic analysis from each group.

Results:

Biomechanical testing revealed a significant increase in failure load (11.5±2.4 N vs. 8.5±2.4 N, p=0.002) and stiffness (7.1±1.2 N/mm vs. 5.7±2.1 N/mm, p>0.17).Biomechanical testing revealed a significant increase in failure load (11.5±2.4 N vs. 8.5±2.4 N, p=0.002) and stiffness (7.1±1.2 N/mm vs. 5.7±2.1 N/mm, p<0.001) in the experimental group compared with the control group at 2 weeks. Similarly, safranin-O staining identified increased fibrocartilage formation at the repair site at 2 weeks in the hMSC group (18.6±2.9% vs. 9.1±1.6%, p=0.026). These effects dissipated by 4 weeks, with no significant biomechanical or histologic differences between groups (p>0.17).

Conclusion:

These data demonstrate the potential for stem cells to augment tendon healing. This is the first study to use purified stem cells, rather than simple bone marrow concentrate. In the future, cell sorting techniques and culture expansion could be used to select and expand the small population of true stem cells in bone marrow. Furthermore, healing could potentially be improved with repeat cell injection at an additional post-operative time point. Application of hMSCs represents a potential solution for improving rotator cuff healing following repair. Further study is necessary to determine the clinical applicability of these results.
Biomechanical Comparison of Acute Hill-Sachs Reduction and Remplissage to Treat Complex Anterior Instability
Authors: Dines Joshua S. , Garcia Grant , McGarry Michelle H. , Lee Thay Q. , Degen Ryan
Published: July 2016

Objectives:

Acute Hill-Sachs (HS) reduction represents a potential alternative method to remplissage for the treatment of an engaging HS lesion. The purpose of this study is to biomechanically compare the stabilizing effects of an acute HS reduction technique and remplissage in a complex instability model.

Methods:

This was a comparative cadaveric study of 6 shoulders. For the acute HS lesion, a unique model was used to create a 30% defect, compressing the subchondral bone while preserving the articular surface in a more anatomic fashion. In addition, a 15% glenoid defect was made in all specimens. The HS lesion was reduced through a lateral cortical window with a bone tamp, and the subchondral void was filled with Quickset (Arthrex) bone cement to prevent plastic deformation. Five scenarios were tested; intact specimen, bipolar lesion, Bankart repair, remplissage with Bankart repair and HS reduction technique with Bankart repair. Translation, kinematics and dislocation events were recorded.

Results:

For all 6 specimens no dislocations occurred after either remplissage or the reduction technique. At 90 degrees of abduction and external rotation (ABER), anterior-inferior translation was 11.1 mm (SD 0.9) for the bipolar lesion. This was significantly reduced following both remplissage (5.1±0.7 mm; p<0.001) and HS reduction (4.4 ±0.3 mm; p<0.001). For anterior-inferior translation there was no significant difference in translation between the reduction technique and remplissage (p=0.91). At 90 degrees of ABER, the intact specimens average joint stiffness was 7.0 ±1.0N/mm, which was not significantly different from the remplissage (7.8±0.9 N/mm; p=0.9) and reduction technique (9.1±0.6 N/mm; p=0.50). Compared with an isolated Bankart repair, the average external rotation loss after also performing a remplissage procedure was 4.3 ±3.5 deg (p=0.65), while average ER loss following HS reduction was 1.1 ±3.3 deg (p=0.99). There was no significant difference in external rotation between remplissage and the reduction technique (p=0.83).

Conclusion:

Similar joint stability was conferred following both procedures, though remplissage had 3.2-degree loss of ER in comparison. While not statistically significant, even slight ER loss may be clinically detrimental in overhead athletes. Overall, the acute reduction technique is a more anatomic alternative to the remplissage procedure with similar ability to prevent dislocation in a biomechanical model, making it a viable treatment option for engaging Hill-Sachs lesions.
Outcomes of The Remplissage Procedure and Its Effects on Return to Sports
Authors: Liu Joseph N. , Garcia Grant , Wu Hao-Hua , Huffman G. Russell , Kelly John D.
Published: July 2016

Objectives:

Short-term outcomes for remplissage patients with large engaging Hill-Sachs lesions have demonstrated good results. However, limited data is available for longer-term outcomes. The purpose of this study was to evaluate long-term outcomes of the remplissage and determine the long-term rate of return to specific sports postoperatively.

Methods:

This was a retrospective review of patients treated with the remplissage procedure from 2007-2013. All had preoperative MRIs demonstrating large Hill-Sachs lesions by Rowe criteria and glenoid bone loss less than 20%. All Hill-Sachs lesions were “off track” by arthroscopic examination and preoperative imaging. At final follow up, patients had a ROM evaluation and were administered a detailed outcomes survey, which included WOSI and ASES as well as questions regarding sports, employment, physical activities and dislocation events.

Results:

Fifty-one shoulders (50 patients) were included. Average age at surgery was 29.8 years (15.0-72.4 years) and average follow up was 60.7 months (25.5-97.6 months). 20% of patients had previous surgery on their shoulder. Average postoperative WOSI scores were 79.5% and average ASES scores were 89.3. Six shoulders had dislocation events (11.7%) postoperatively: three were traumatic, and three atraumatic. Increasing number of preoperative dislocations increased the risk of a postoperative dislocation (p<0.001). There was also a trend towards higher postoperative dislocation rates in revision patients (p=0.062). Average loss of external rotation was 5.2 degrees (p=0.13). 95.5% of patients returned to one or more sports postoperatively at an average of 7.0 months. 81.0% returned to their previous intensity and level of sport. 65.5% (19) of patients who played a throwing sport stated they had problems throwing. 58.6% (17) felt they could not normally wind up throwing a ball. Direct rates of return for overhead sports were volleyball 100%, basketball 69%, baseball 50% and football 50%.

Conclusion:

Remplissage’s re-dislocation rate was 11.7% at an average of five years, with 96% of patients returning to full sports at an average of 7 months. For throwing sports, 65.5% complain of decreased range of motion during throwing. The results should be considered preoperatively in remplissage candidates who are engaged in throwing sports.
Factors Affecting Return to Baseline Function at 6 months Following Anterior Shoulder Instability Surgery
Authors: Hettrich Carolyn M. , Buckwalter Joseph , Wolf Brian R. , Bollier Matthew , MOON Shoulder Group , Glass Natalie
Published: July 2016

Objectives:

Pre-operative and surgical factors related to early return to baseline function after anterior shoulder instability surgery are not clear. This study was designed to determine the pre-operative and operative factors affecting return to baseline function at 6 months following anterior shoulder instability surgery. Identifying these factors will help surgeons establish expectations for functional return post-operatively.

Methods:

The Multicenter Orthopaedic Outcomes Network (MOON) shoulder group enrolled patients undergoing surgery for shoulder instability from 16 sites throughout the United States. Initial demographic data and validated, patient-oriented outcomes questionnaires were collected along with the physicians documented initial physical exam, treatment, surgical findings and surgical techniques used at the time of surgery. At the 6-month follow up visit, range of motion (ROM) and strength measurement of the operative shoulder were collected and compared to pre-operative measurement. Return to baseline was defined as return to within -10° ROM and full strength at the 6 month physical exam. Continuous and categorical data were analyzed using student t-tests and chi-square tests, respectively. The Kruskal-Wallis/Wilcoxin tests were used to compare groups that were not normally distributed. Factors reaching significance in a univariate analysis were then applied in a multivariable model. Significance was set a p<0.05.

Results:

A total of 338 patients with history of surgical intervention for anterior instability of the shoulder were identified. 278 patients had complete pre- and post-surgical range of motion and strength measurements. 138 (50%) patients (139 shoulders) returned to baseline and 133 (50%) patients did not return to baseline. Univariate analysis identified age (p=0.0013), Beighton score (p=0.0004), SF-36 general health (p=0.0017), WOSI (p=0.0250), and duration of symptoms (p=0.0046) as significant factors. When these factors were placed into a multivariate model, significant differences were identified in age (p=0.0316), SF-36 General health (p=0.0118), and Beighton score (p=0.0016).

Conclusion:

Older age, perception of general health and generalized joint laxity are associated with failure to return to baseline function at 6 months after anterior shoulder instability surgery. Duration of symptoms and number of dislocation events did not reach significance in the multivariate model, but trended toward likelihood of failure to return to baseline findings. Moreover, open vs. arthroscopic surgery and number of suture anchors were not significant, suggesting that pre-operative condition and not surgical factors predict return to baseline in the short-term.
Anisometry of Medial Patellofemoral Ligament Reconstruction in the Setting of Patella Alta and Increased Tibial Tubercle-Trochlear Groove (TT-TG) Distance
Authors: Redler Lauren H. , Meyers Kathleen N. , Munch Jacqueline , Dennis Elizabeth R. , Nguyen Joseph , Stein Beth E. Shubin
Published: July 2016

Objectives:

Medial patellofemoral ligament (MPFL) reconstruction is a common procedure to treat recurrent patellofemoral instability. However, the effects of an elevated tibial tubercle-trochlear groove (TT-TG) distance and patella alta, as measured by the Caton-Deschamps (C/D) ratio, on MPFL isometry remain unclear. We hypothesized that increased lateralization and proximalization of the tibial tubercle (TT) will have increasingly adverse effects on the isometry of the MPFL.

Methods:

Ten fresh-frozen cadaveric knees were placed on a custom testing fixture, with a fixed femur and tibia mobile through 120 degrees of flexion. The quadriceps tendon was loaded with 10.8 N in an anatomic direction using a weighted pulley system. A 0.2 N patellar lateral displacement load was used to simulate an intact lateral retinaculum to avoid over-medializing the patella. A tunnel was drilled under fluoroscopic guidance from Schottle’s point on the medial distal femur through the lateral cortex. A suture anchor was placed at the upper 66% of the medial border of the patella and the sutures were shuttled through to the lateral side and attached to a pulley with a 1 N weight. Retroreflective markers were attached to the femur, tibia, patella, and suture. MPFL length change, as measured by suture marker motion, was assessed using a 3D motion capture system through a range of motion between 0 deg and 110 deg with the native TT anatomy. Recordings were repeated after a flat TT osteotomy and transfer to a TT-TG of 20 mm and 25 mm and a C/D ratio of 1.2 and 1.4, including all combinations. Generalized estimating equation (GEE) modeling technique was used to analyze and control for the clustered nature of the data. SAS version 9.3 (SAS Inc., Cary, NC) was used for all data analyses.

Results:

Analysis was performed on 9 specimens secondary to significant deviations in the baseline normative data. Intact knees showed MPFL isometry through 20-70 degrees range of motion. Tibial tubercle lateralization significantly altered MPFL isometry with a threshold TT-TG of 25 mm (p=0.045) (Figure 1). Patella alta significantly altered MPFL isometry with a threshold C/D of 1.4 (p=0.025) (Figure 2). The effect of TT lateralization combined with patella alta compounded the anisometry, lowering the threshold for patella alta to a C/D of 1.2 when combined with a TT-TG of 25 mm (P<0.001) (Figure 3).

Conclusion:

Increased TT lateralization and proximalization significantly alter MPFL isometry. Tibial tubercle transfer should be considered when performing an MPFL reconstruction for recurrent patellofemoral instability in the setting of significant patella alta, elevated TT-TG and especially when both are present as an isolated MPFL reconstruction may be prone to failure given the anisometry demonstrated.