Charles Chan, MD

Abstract

Background and Purpose: Lower extremity athletic injuries result in impairments in balance, power, and jump-landing mechanics. Unilateral injury has bilateral effects and the literature supports that it is important to assess neuromuscular impairments such as balance, power, and jumping mechanics following injury and for safe return to sport after injury rehabilitation. Currently, individual tests are established in the literature, but no combined approach or clinical tool exists for this purpose. The purpose of this study is to describe and provide the initial data for the Lower Extremity Grading System (LEGS), comprised of three neuromuscular components for use as a baseline pre-season assessment for high school athletes to assess lower extremity performance. Furthermore, this study focuses on the differences in baseline lower extremity performance outcomes between male and female soccer and basketball athletes.Methods: One hundred and eighty-five high school basketball, and soccer athletes (94 female, 91 male; mean age = 15.64.4) participated. The participants were administered the LEGS assessment during the preseason for their respective sports, which includes three component tests: (1) Y-balance test, (2) drop vertical jump test, (3) triple-crossover-hop-for-distance test. Participants' scores on each test were recorded, and then totaled to present an overall LEGS composite score. Participants' baseline LEGS scores were then analyzed according to sex and sport, and standard normal distribution was calculated for all scores to enable percentile rankings to be established.Results: Mean scores and standard deviation for each functional performance test are presented. Furthermore, a LEGS composite score combining the test scores was established and presented as a normal distribution curve allowing for further comparison and analysis. The mean LEGS composite score for males was 700.3 (76.6), while the mean LEGS composite score for females was 587.4 (51.6). Statistically different LEGS composite scores were found between males and females.Conclusion: The current findings present descriptive data for the utility of the LEGS as a neuromuscular baseline assessment before high school sports participation and/or as a tool for assessing return to sports after injury rehabilitation. The LEGS may augment current assessment tools and may serve as a composite score and combined approach to the assessment of lower extremity risk of injury and readiness to return to sports.Level of evidence: 3.

View details for PubMedID 30038826

View details for DOI 10.26603/ijspt20180401

View details for Web of Science ID 000442339400005

View details for PubMedID 29557795

Abstract

There appears a linear relationship between small increases in running speed and cardiovascular health benefits. Encouraging or coaching recreational runners to increase their running speed to derive these health benefits might be more effective if their joint level kinematic and kinetic strategy was understood. The aim of this investigation was to compare the peak sagittal plane motions, moments, and powers of the hip, knee and ankle at 85%, 100%, 115% and 130% of self-selected running speed. Overground running data were collected in 12 recreational runners (6 women, 6 men) with a full body marker set using a 12-camera Vicon MX system with an AMTI force plate. Kinematics and kinetics were analyzed with Vicon Nexus software. Participants chose to run at 2.60.5m/s (85%); 3.00.5m/s (100%); 3.30.5m/s (115%); and 3.70.5m/s (130%); these four speeds approximately correspond to 6:24-, 5:33-, 5:03-, and 4:30-min kilometer running paces. Running speed had a significant effect (P<0.05) on peak kinematic and kinetic variables of the hips, knees and ankles, with peak sagittal hip moments invariant (P>0.54) and the peak sagittal ankle power generation (P<0.0001) the most highly responsive variable. The timing of the peak sagittal extensor moments and powers at the hip, knee and ankle were distributed across stance in a sequential manner. This study shows that running speed affects lower limb joint kinematics and kinetics and suggests that specific intersegmental kinetic strategies might exist across the narrow range of running speeds.

View details for PubMedID 29472010

Abstract

This review will focus on the evaluation and management of patellar instability in the developing patient.A large number of surgical techniques have been described to prevent recurrent patellofemoral instability in the pediatric population, including both proximal and distal realignment procedures. The wide variety of treatment options highlights the lack of agreement as to the best surgical approach. However, when a comprehensive exam and workup are paired with a surgical plan to address each of the identified abnormalities, outcomes are predictably good. Patellar instability is a common knee disorder in the skeletally immature patient that presents a unique set of challenges. Rates of re-dislocation in pediatric and adolescent patients are higher than in their adult counterparts. Careful consideration of the physeal and apophyseal anatomy is essential in these patients. While the majority of primary patellar instability events can be treated conservatively, multiple events often require surgical intervention.

View details for PubMedID 29682681

Abstract

Ipsilateral femoral neck fractures occur in 1% to 9% of adult trauma patients with femoral shaft fractures making dedicated imaging important. This is not as clear in children. Our purpose is to establish the incidence of ipsilateral femoral neck fractures in children with femoral shaft fractures and to provide recommendations regarding diagnostic imaging protocols.A retrospective analysis of medical records was performed for pediatric patients (below 18 y) with femoral shaft fractures seen at our trauma center over a 10-year period. Mechanism of injury, associated injuries, procedures, and follow-up data were collected, and all radiographs reviewed. Exclusion criteria included peri-implant fractures or evidence of pathologic fracture. A similar retrospective analysis was performed in a cohort of adult patients.Of 267 pediatric patients with femoral shaft fractures, 2 patients (0.7%) had ipsilateral femoral neck fractures. One femoral neck fracture was detected on initial plain radiographs and the other on a pelvic computed tomography (CT) scan. Both of these fractures resulted from high-energy trauma, which accounted for 92 (42%) of pediatric femoral shaft fractures. The cohort of 100 adults aged 18 to 89 years with femoral shaft fractures revealed 6 adult patients (6%) with ipsilateral femoral neck fractures, all from high-energy trauma. High-energy trauma accounted for 85% of the adult femoral shaft fractures, and was more common than in the pediatric population (P<0.005). The difference in incidence of ipsilateral femoral neck fracture between the pediatric (0.7%) and the adult group (6%) was significant (P=0.007). No missed or delayed diagnoses were identified.The incidence of associated ipsilateral femoral neck fracture in pediatric patients with femoral shaft fracture is very low (0.7%). Most (58%) pediatric femur fractures are caused by low-energy trauma. We were unable to demonstrate a need for routine CT scanning of the femoral neck in children with femoral shaft fractures. Given the increased risks of radiation exposure with younger and smaller patients, it does not appear that routine CT scanning low-energy pediatric femoral shaft fractures to evaluate for femoral neck fractures is justified unless there is a high level of clinical suspicion.Level II.

View details for DOI 10.1097/BPO.0000000000000800

View details for Web of Science ID 000395941800004

Abstract

To study the degree of surface congruency between the talar dome and humeral head, to determine the size of graft harvestable from the talar dome, and to determine if there are surrogate markers that correspond to a higher degree of surface congruency.Computer models of 7 nonmatched humeral heads and 7 talar domes were generated by digital segmentation of magnetic resonance (MR) images. Modeled defect regions of each humeral head were then aligned with medial and lateral surfaces of each talar dome using software to maximally limit surface mismatch. Modeled defect sizes ranging from 24 10mm to 30 10mm were tested. Congruence match of <1mm separation was then measured.The average surface match between randomly selected talar domes to humeral head surfaces was 87.2% when 1mm was selected as the maximal acceptable congruence difference. Congruence match was not affected by graft size or laterality of talar dome as source of graft. Matching radius of curvature of talar dome to humeral head and height of donor to recipient correlated with improved congruence match. Under best match conditions, a maximal congruence match of 95.2% was achieved.The present study indicates that the talar dome can be a potential source of osteochondral allograft for Hill-Sachs lesions with a maximal defect size of 30 10mm for a single graft. Larger graft sizes resulted in decreased success of actual graft harvest as a result of dimensional constraints of the talar dome. Additional studies are required to determine the biomechanical compatibility of this graft.The talar dome has a high degree of surface congruency in comparison with the humeral head though the maximal graft size harvestable limits its clinical applicability.

View details for DOI 10.1016/j.arthro.2016.03.021

View details for PubMedID 27177437

Abstract

Ipsilateral femoral neck fractures occur in 1% to 9% of adult trauma patients with femoral shaft fractures making dedicated imaging important. This is not as clear in children. Our purpose is to establish the incidence of ipsilateral femoral neck fractures in children with femoral shaft fractures and to provide recommendations regarding diagnostic imaging protocols.A retrospective analysis of medical records was performed for pediatric patients (below 18 y) with femoral shaft fractures seen at our trauma center over a 10-year period. Mechanism of injury, associated injuries, procedures, and follow-up data were collected, and all radiographs reviewed. Exclusion criteria included peri-implant fractures or evidence of pathologic fracture. A similar retrospective analysis was performed in a cohort of adult patients.Of 267 pediatric patients with femoral shaft fractures, 2 patients (0.7%) had ipsilateral femoral neck fractures. One femoral neck fracture was detected on initial plain radiographs and the other on a pelvic computed tomography (CT) scan. Both of these fractures resulted from high-energy trauma, which accounted for 92 (42%) of pediatric femoral shaft fractures. The cohort of 100 adults aged 18 to 89 years with femoral shaft fractures revealed 6 adult patients (6%) with ipsilateral femoral neck fractures, all from high-energy trauma. High-energy trauma accounted for 85% of the adult femoral shaft fractures, and was more common than in the pediatric population (P<0.005). The difference in incidence of ipsilateral femoral neck fracture between the pediatric (0.7%) and the adult group (6%) was significant (P=0.007). No missed or delayed diagnoses were identified.The incidence of associated ipsilateral femoral neck fracture in pediatric patients with femoral shaft fracture is very low (0.7%). Most (58%) pediatric femur fractures are caused by low-energy trauma. We were unable to demonstrate a need for routine CT scanning of the femoral neck in children with femoral shaft fractures. Given the increased risks of radiation exposure with younger and smaller patients, it does not appear that routine CT scanning low-energy pediatric femoral shaft fractures to evaluate for femoral neck fractures is justified unless there is a high level of clinical suspicion.Level II.

View details for PubMedID 27261972

Abstract

This study determines the rate of change in the scoliosis surgery plan in cases presented in preoperative indications conference.To determine the effect of preoperative indications conference on the plan of surgery and to identify characteristics that increased the likelihood of change.Preoperative indications conferences are used as a teaching and planning tool. Levels of fusion, construct options, and necessity for osteotomies are often debated in the planning of scoliosis surgery.Scoliosis surgeries were presented at preoperative indications conference with four attending pediatric orthopedic surgeons present. The operative surgeon committed to a surgical plan before conference. A consensus-based plan was made without knowledge of the operative surgeon's preconference plan. Changes of plan were classified as major, minor, or no change.Of the 107 surgical plans, 50 were index surgeries, 13 were revisions, and 44 were scheduled growing rod lengthenings. There were two major changes, including a change to a growing construct from planned fusion, and a change in fusion levels in an adolescent idiopathic scoliosis (AIS) patient. There were 13 minor changes, which included changes in fusion levels (1 to 3; mean = 1.23) and the addition of an osteotomy. The rate of change was 28% for index surgeries and 7.69% for revisions. Of the 14 changes in the 50 index surgeries, there were 8 AIS, 3 cerebral palsy, 1 congenital scoliosis, 1 Ehlers-Danlos, and 1 patient with an undetermined neuromuscular condition. There was 1 change in 13 revision surgeries. There were no changes for growing rod lengthenings and no cancellations as a result of indications conference.Although revision scoliosis surgery is complex, index AIS/JIS surgery was most subject to the influence of indications conference. This likely reflects controversy around choosing levels of fusion.IV.

View details for DOI 10.1016/j.jspd.2015.05.003

View details for PubMedID 27852496

Abstract

The purpose of this study was to examine the location of biceps tenotomy and the integrity of the superior labrum as they relate to superior glenohumeral joint stability in a cadaveric concavity-compression model.Eight cadaveric glenoid labrums were mounted individually onto a load cell with the corresponding humerus fixed to the loading arm in the hanging-arm position. All surrounding soft tissue was removed except the labrum and proximal stump of the long head of the biceps (LHB) tendon, simulating a biceps tenotomy. A compressive load of 22N was applied across the glenohumeral joint. The humerus was then translated superiorly until it subluxated over the glenoid labrum. The force resisting superior translation was characterized for each of 50 cycles. Each specimen was tested under the following conditions: (1) with a 4 cm biceps stump after tenotomy, (2) with a 0 cm biceps stump, (3) after full detachment of the superior labrum, and (4) after repair of the labrum.Biceps tenotomy performed at the biceps-labral junction resulted in an average decrease in force required to superiorly subluxate the humeral head by 8.6% (P= .01) when compared with leaving 4cm of biceps stump. Resection of the entire superior labrum resulted in a future decrease to 15.2% (P < .001) from baseline. Repair of the labrum resulted in restoration of stability with a mean of 101.1% (P= .82) and was not statistically different from baseline. The kinematics of the glenohumeral joint was affected by labral repair, with an earlier upslope on the force-to-displacement curve and alteration in the total energy required to cause subluxation of the humeral head noted.In this study, location of the biceps tenotomy and integrity of the superior labrum affected glenohumeral stability during axial loading in the hanging-arm position. Repair of the labrum restored stability for superior subluxation but also changed the kinematics of the subluxation event.Preservation of superior labrum after biceps tenotomy provides increased resistive force to superior translation in a unidirectional biomechanical model.

View details for DOI 10.1016/j.arthro.2014.06.012

View details for Web of Science ID 000345855700007

View details for PubMedID 25129863

Abstract

The review of multicenter national pediatric scoliosis database.The purpose of this study was to compare the radiographic outcomes of patients who underwent scoliosis surgery utilizing different rod diameter constructs by the posterior approach.Little attention has specifically been focused on the effect of rod diameter on correction of spinal deformity after posterior spinal instrumentation and fusion in children with adolescent idiopathic scoliosis (AIS).The review of national database comprised of 1125 patients, of which 352 patients had a minimum follow-up of 2 years. Of these, 163 patients received 5.5 mm and 189 patients received 6.35 mm diameter rods for posterior spinal instrumentation.The 6.35 mm rods were used more often for patients who were male, taller, heavier, with larger coronal curves, and more flexible curves. Larger diameter rods were also more likely to be stainless steel, implanted with an increased number of implants per level, and an increased number of pedicle screws used on the concavity of the curve. Univariate analysis of coronal curve showed a significant difference between 5.5 and 6.35 mm rods in correction (67.0% vs. 57.3%) at 2 years. Multivariate analysis revealed that the most significant factors affecting coronal curve correction at 2 years were rod diameter, the patient's preoperative coronal major curve and flexibility, and the implant density. In the sagittal plane, preoperative sagittal curve and rod diameter are the predictors of sagittal correction at 2 years.The study did not support our hypothesis that larger rods would be associated with a greater correction of frontal and sagittal plane in patients with AIS. In addition to rod diameter, implant density and the inherent flexibility and deformity of the patient were found to be influential factors contributing for the correction and maintenance of coronal and sagittal curves in AIS.

View details for DOI 10.1097/BPO.0b013e318288b3c1

View details for PubMedID 23863413

Abstract

Four normal variants of meniscomeniscal ligaments have been previously reported in the anatomy, arthroscopy, and radiology literature. The anterior and posterior transverse meniscal ligaments are the 2 most commonly observed, with a reported frequency of 58% and 1% to 4%, respectively. The last 2 variants include the medial and lateral oblique meniscomeniscal ligaments and account for a combined frequency of 1% to 4%.This article describes 2 patients with unilateral meniscomeniscal ligaments observed on magnetic resonance imaging. One patient had a unilateral lateral meniscomeniscal ligament extending from the anterior horn of the lateral meniscus to the posterior horn of the lateral meniscus and underwent conservative management. The second patient had a unilateral medial meniscomeniscal ligament with a concomitant medial meniscus tear and underwent arthroscopic intervention. The ligament was stable intraoperatively and, therefore, was not resected. Both patients had resolution of their symptoms.These 2 variants are additions to the previously described 4 normal intermeniscal ligament variants. The functions of the 2 new variants described in this article are poorly understood but are thought to involve meniscal stability. Accurate descriptions of normal variants can lead to the proper management of anomalous rare structures and prevent false imaging interpretations because these structures can closely mimic a double posterior cruciate ligament sign. Furthermore, an understanding of the various normal variants of intermeniscal ligaments can prevent unnecessary surgery that could result in further iatrogenic meniscus injury.

View details for DOI 10.3928/01477447-20121120-31

View details for PubMedID 23218643

View details for DOI 10.2106/JBJS.CC.K.00153

Abstract

Musashi1 is a highly conserved protein found in neural progenitor cells. We examined the expression dynamics of Musashi1 in conjunction with other representative neural progenitor antigenic determinants (Ki-67 and nestin) during 8 different stages of the developing human fetal germinal matrix. Our results indicate that Musashi1 is a useful marker for immature cells in periventricular areas inhabited by stem cells, progenitor cells, and differentiating cells.

View details for DOI 10.1016/j.expneurol.2006.04.023

View details for Web of Science ID 000241393900025

View details for PubMedID 16777095