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Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_13 | Pages 142 - 142
1 Nov 2021
Negri S Wang Y Lee S Qin Q Cherief M Hsu GC Xu J Tower RJ Levi B Levin A James A
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Introduction and Objective

Heterotopic ossification is the formation of extraskeletal mineralized tissue commonly associated with either trauma or surgery. While several mouse models have been developed to better characterize the pathologic progression of HO, no model currently exists to study HO of the hip, the most common location of acquired HO in patients. Owing to the unique biological mechanisms underpinning the formation of HO in different tissues, we sought to develop a model to study the post-surgical HO of the hip.

Materials and Methods

Wild-type mice C57BL/6J mice were used to study the procedure outcomes, while Pdgfra-CreERT2;mT/mG and Scx-GFP reporter animals were used for the lineage tracing experiments (total n=16 animals, male, 12 weeks old). An anterolateral approach to the hip was performed. Briefly, a 2 cm incision was made centered on the great trochanter and directed proximal to the iliac crest and distally over the lateral shaft of the femur. The joint was then reached following the intermuscular plane between the rectus femoris and gluteus medius muscles. After the joint was exposed, the articular cartilage was removed using a micropower drill with a 1.2 mm reamer. The medius gluteus and superficial fascia were then re-approximated with Vicryl 5-0 suture (Ethicon Inc, Somerville, NJ) and skin was then closed with Ethilon 5-0 suture (Ethicon Inc). Live high resolution XR imaging was performed every 2 wks to assess the skeletal tissues (Faxitron Bioptics, Tucson, AZ). The images were then scored using the Brooker classification. Ex-vivo microCT was conducted using a Skyscan 1275 scanner (Bruker-MicroCT, Kontich, Belgium). 3D reconstruction and analysis was performed using Dragonfly (ORS Inc., Montreal, Canada). For the histological analysis of specimens, Hematoxylin and Eosin (H&E), modified Goldner's Trichrome (GMT) stainings were performed. Reporter activity was assessed using fluorescent imaging.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_5 | Pages 15 - 15
1 Mar 2017
Mihalko W Braman M Lowell J Dopico P Zucker-Levin A
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Introduction

Early hip OA may be attributed to smaller coverage of the femoral head leading to higher loads per unit area. We hypothesize that tight hamstrings may contribute to increased loads per unit area on the femoral head during gait. When a patient has tight hamstrings they cannot flex their pelvis in a normal fashion which may result in smaller coverage of the femoral head (Figure 1). This study aimed to determine if subjects with tight hamstrings can improve femoral head coverage during gait after a stretching intervention.

Methods

Nine healthy subjects with tight hamstrings (popliteal angle>25°) were recruited and consented for this IRB approved study. Gait analysis with 58 reflective markers were placed by palpation on anatomical landmarks of the torso and lower extremities. Ten optoelectronic cameras (Qualisys, Gothenburg, Sweden) and three force plates (AMTI, Watertown, MA) were used to track marker position and measure foot strike forces. Subjects walked at a self-selected speed across the force plates until ten clean trials were performed and then were scanned with the reflective markers on the spine using an EOS (EOS Imaging, France) bi-planar x-ray system. Following testing participants completed a six week stretching program to increase hamstring length. Pelvic tilt (PT) was measured at heel strike for each trial and averaged.

Using EOS scans the femoral head radius was measured using three points that best fit the load bearing surface on the sagittal view from the anterior acetabular rim to a point on the posterior acetabulum 45 degrees from vertical. The radius of femoral head and angle of acetabular coverage were used to calculate the load bearing surface area of femoral head. Load on the femur was calculated using an Anybody lower body model (Anybody Technology, Aalborg, Denmark) and load per unit area change was compared.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_4 | Pages 128 - 128
1 Jan 2016
Sanford B Williams J Huffman K Zucker-Levin A Mihalko W
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Introduction

The sit-to-stand (STS) movement is a physically demanding activity of daily living and is performed more than 50 times per day in healthy adults. Several studies have shown that the normal ‘screw-home’ mechanism is altered after total knee arthroplasty (TKA). However, these studies have been criticized due to their limitations of the movement being non-weight-bearing or atypical daily activity (lunge maneuver). We analyzed TKA subjects during a STS activity to determine if the internal-external rotation of their TKA knees differed from the knees of control subjects.

Materials and Methods

Six TKA subjects (3 M, 3 F) participated following institutional review board approval and informed consent. One subject had bilateral knee replacement. Surgery was performed by the same surgeon using the same type of implant (6 posterior-stabilized, 1 cruciate-retaining). The control group included eight healthy subjects (6 M, 2 F).

Retro-reflective markers were placed over bony landmarks of the torso, pelvis, and lower extremities, and arrays of four markers were attached to the thighs and shanks using elastic wrap. A digitizing pointer was used to create virtual markers at the anterior superior iliac spines. A nine camera video-based opto-electronic system (Qualisys) was used for 3D motion capture. Subjects were barefoot and seated on a 46 cm armless bench with one foot on each force plate (AMTI). Subjects rose from their seated position, paused, and returned to the seated position at a self-selected pace repeatedly for 30 seconds. Subjects did not use their arms to push off the bench. Only the STS portion of the task was analyzed. The start of the STS cycle was defined when the C7 marker began to move forward in the sagittal plane and ended at the point of maximum knee extension. Only the right leg of the control subjects was used for analysis.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_4 | Pages 129 - 129
1 Jan 2016
Sanford B Williams J Zucker-Levin A Mihalko W
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Introduction

In a previous study of subjects with no history of lower extremity injury or disease we found a linear relationship between body weight and peak hip, knee, and ankle joint forces during the stance phase of gait. To investigate the effect of total knee arthroplasty (TKA) on forces in the operated joints as well as the other joints of the lower extremities, we tested TKA subjects during gait and performed inverse dynamics analyses of the results.

Materials and Methods

TKA subjects (3 M, 1 F; 58 ± 5 years; body mass index range (BMI): 26–36 kg/m2) participated in this investigation following institutional review board approval and informed consent. One subject had bilateral knee replacement. Each patient received the same implant design (4 PS, 1 CR). Data from previously tested control subjects (8 M, 4 F; 26 ± 4 years; BMI: 20–36 kg/m2) were used for comparison.

Retro-reflective markers were placed over bony landmarks of each subject. A nine-camera video-based opto-electronic system was used for 3D motion capture as subjects walked barefoot at a self-selected speed on a 10 meter walkway instrumented with three force plates. Data were imported into a 12-body segment multibody dynamics model (AnyBody Technology) to calculate joint forces. Each leg contained 56 muscles whose mechanical effect was modeled by 159 simple muscle slips, each consisting of a contractile element. The models were scaled to match each subject's anthropometry and BMI. For the control subjects, only one limb was used in determining the relationship between body mass and peak joint force at the hip, knee, and ankle. For the TKA subjects, the peak joint forces were calculated for both the TKA limb and the contralateral limb.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_III | Pages 315 - 316
1 Sep 2005
Paley D Paley J Levin A Talor J Herzenberg J
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Introduction and Aims: We propose a new, simple, and universal method to predict adult height: the Height Multiplier Method. Our aim was to calculate height multipliers from various databases and validate their use for height prediction.

Method: Standard growth charts, based on a diverse population, were published by the Centres for Disease Control and Prevention (CDC) in 2000. Height multipliers (M) for boys and girls were calculated by dividing the height at skeletal maturity (Htm) by the present height (Ht) (M = Htm/Ht) for each age, gender, and height percentile using CDC data. These multipliers were compared with multipliers derived from various height databases of 28 boys and 24 girls. The accuracy of the multipliers was tested on individual longitudinal data sets from 52 normal children.

Results: The average CDC-derived multipliers were significantly different at each age for boys and girls, but within gender, different percentiles at each age were very similar. These multipliers were very similar to multipliers derived from each of the databases. For predictions based on individual data sets from 52 children, the median, 90%, and standard deviation of absolute error prediction (AEP) were calculated. Boys’ median AEP ranged from 1.4–4.3cm; 90% AEP ranged from 1.8–8.3cm. Girls’ median AEP ranged from 0.68–4.38cm; 90% AEP ranged from 1.5–10.6cm.

Conclusion: The Height Multiplier Method of stature prediction is as accurate as CDC growth charts when based on single-height measurements and is similar in accuracy to other methods. The Height Multiplier Method has the advantage of percentile, race, nationality, and generation independence. Growth charts have the advantage of showing trends over time.