Crossing the Cervicothoracic Junction: A Biomechanical Investigation of C7 vs T1 Caudal Selection's Effect on Adjacent Segment Motion in Posterior Cervical Fusion.

Study Design: Biomechanical Study.

Objective: This study aims to evaluate the biomechanical adjacent segment effects of multi-level posterior cervical fusion constructs that terminate at C7 compared to those that terminate at T1 in cadaveric specimens.

Background: The cervicothoracic junction poses unique challenges for spine surgeons.

The Three-Dimensional Relationship of the Axes of the Capitate and Third Metacarpal.

Purpose: We quantified the morphology and angulation of the third metacarpal (MC3) relative to the capitate using three-dimensional computed tomography data to inform surgical procedures such as total wrist arthroplasty and wrist arthrodesis. Specifically, we report the three-dimensional location of the intersections of the long axis of MC3 axis with the capitate cortical surface, the sagittal and coronal angles between the MC3 and capitate axes, and the MC3 shaft angle in the sagittal plane. We tested the hypothesis that these metrics did not differ between women and men.

Development of an implantable trapezium carpal bone replacement for measuring in vivo loads at the base of the thumb.

Understanding the loads that occur across musculoskeletal joints is critical to advancing our understanding of joint function and pathology, implant design and testing, as well as model verification. Substantial work in these areas has occurred in the hip and knee but has not yet been undertaken in smaller joints, such as those in the wrist. The thumb carpometacarpal (CMC) joint is a uniquely human articulation that is also a common site of osteoarthritis with unknown etiology.

Bone morphological changes of the trapezium and first metacarpal with early thumb osteoarthritis progression.

Background: Thumb carpometacarpal osteoarthritis is characterized by osteophyte growth and changes in the curvature of the articular surfaces of the trapezium and first metacarpal. The aim of this longitudinal study was to quantify in-vivo bone morphology changes with osteoarthritis progression.

Methods: The study analyzed an observational dataset of 86 subjects with early thumb osteoarthritis and 22 age-matched asymptomatic controls.

Evaluation of the PROMIS Upper Extremity Against Validated Patient-Reported Outcomes in Patients With Early Carpometacarpal Osteoarthritis.

Purpose: Internal consistency, construct, and criterion validity of the Patient-Reported Outcomes Measurement Information System (PROMIS) upper extremity (UE) v1.2 were evaluated in patients with early-stage carpometacarpal (CMC) osteoarthritis (OA). We hypothesized that in patients with early CMC OA, PROMIS UE scores would: (1) be lower than those in asymptomatic controls; (2) correlate with established patient-reported outcomes; (3) correlate with pinch and grip strengths; and (4) not correlate with radiographic disease progression.

Head Impact Exposure in Youth and Collegiate American Football.

The relationship between head impact and subsequent brain injury for American football players is not well-defined, especially for youth. The objective of this study is to quantify and assess Head Impact Exposure (HIE) metrics among youth and collegiate football players. This multi-season study enrolled 639 unique athletes (354 collegiate; 285 youth, ages 9-14), recording 476,209 head impacts (367,337 collegiate; 108,872 youth) over 971 sessions (480 collegiate; 491 youth).

Uncemented Collared Femoral Stems in Total Hip Arthroplasty.

The procedure of total hip arthroplasty (THA) is rapidly evolving. Patients undergoing THA are younger and more active, and they demand an earlier return to their daily activities. All of these factors increase both the early forces on uncemented femoral stems and the risk for complications.

Total Wrist Arthroplasty Alignment and Its Potential Association with Clinical Outcomes.

 There is a lack of quantitative research that describes the alignment and, more importantly, the effects of malalignment on total wrist arthroplasty (TWA). The main goal of this pilot study was to assess the alignment of TWA components in radiographic images and compare them with measures computed by three-dimensional analysis. Using these measures, we then determined if malalignment is associated with range of motion (ROM) or clinical outcomes (PRWHE, PROMIS, QuickDash, and grip strength).

The role of scapholunate interosseous, dorsal intercarpal, and radiolunate ligaments in wrist biomechanics.

Rupture to wrist ligaments predisposes the joint to degenerative changes. Scapholunate interosseous ligament (SLIL) rupture, especially when compounded by dorsal intercarpal ligament (DIC) and long radiolunate ligament (LRL) disruption, can cause carpal bone kinematic abnormalities. It is essential to delineate the role of these ligaments and their constraints on wrist range-of-motion (ROM) and center of rotation (COR).

Biomechanics of the Distal Radioulnar Joint During In Vivo Forearm Pronosupination.

 Ulnar variance (UV) and center of rotation (COR) location at the level of the distal radioulnar joint (DRUJ) change with forearm rotation. Nevertheless, these parameters have not been assessed dynamically during active in vivo pronosupination. This assessment could help us to improve our diagnosis and treatment strategies.

In vivo articular contact pattern of a total wrist arthroplasty design.

Total wrist arthroplasty (TWA) designs suffer from relatively high complication rates when compared to other arthroplasties. Understanding the contact pattern of hip and knee replacement has improved their design and function; however, the in vivo contact pattern of TWA has not yet been examined and is thus the aim of this study. We hypothesized that the center of contact (CoC) is located at the geometric centers of the carpal component and radial component in the neutral posture and that the CoC moves along the principal arcs of curvature throughout primary anatomical motions.

"Stress taper" fixation increases torsional failure strength in a cadaveric femur model.

Background: To potentially limit peri-implant fractures our institution commonly implements a "stress-taper" fixation construct in which the screw lengths towards the proximal end of a construct are incrementally decreased, in order to avoid a focal stress-riser when loaded. To assess this construct, we asked: 1) Does the stress taper strategy increase torsional strength than the bicortical locking construct when biomechanically tested in a cadaveric femur model? 2) Does it fail in a less comminuted fracture pattern?

Methods: Seven matched pairs of cadaveric femora were randomly assigned to one of two distal femur fixation groups: plating with stress taper strategy or bicortical fixation. Specimens were first cyclically loaded, then axially rotated to failure under 800 N of compression.

Optical motion capture accuracy is task-dependent in assessing wrist motion.

Optical motion capture (OMC) systems are commonly used to capture in-vivo three-dimensional joint kinematics. However, the skin-based markers may not reflect the underlying bone movement, a source of error known as soft tissue artifact (STA). This study examined STA during wrist motion by evaluating the agreement between OMC and biplanar videoradiography (BVR).

Biplanar Videoradiography to Study the Wrist and Distal Radioulnar Joints.

Accurate measurement of skeletal kinematics in vivo is essential for understanding normal joint function, the influence of pathology, disease progression, and the effects of treatments. Measurement systems that use skin surface markers to infer skeletal motion have provided important insight into normal and pathological kinematics, however, accurate arthrokinematics cannot be attained using these systems, especially during dynamic activities. In the past two decades, biplanar videoradiography (BVR) systems have enabled many researchers to directly study the skeletal kinematics of the joints during activities of daily living.

An Anatomical Evaluation of the Trapezium and Its Relationship to Basilar Joint Osteophytic Change.

Background: To perform a comprehensive osteologic investigation into trapezium anatomy and investigate the relationship between anatomical factors and osteophyte formation, focusing on sex-specific differences.

Methods: This was a cadaveric study involving 1233 trapezia and first metacarpals. Two subgroups ("Control" and "Main Study") were established.

The Association of AUSCAN and PRWHE Patient-reported Outcome Measures With Radiographic Progression of Early Thumb Carpometacarpal Arthritis at 36-Month Follow-up Is Limited to Subtle Changes in the Pain Subscale.

Background: There is a paucity of literature that examines how patient-reported outcomes correspond to early radiographic progression of thumb carpometacarpal (CMC) osteoarthritis (OA). This study examines how Australian/Canadian Osteoarthritis Hand Index (AUSCAN) and Patient-Rated Hand and Wrist Evaluation (PRWHE) scores change over 36 months in subjects with early CMC OA.

Methods: Ninety-one subjects with symptomatic early thumb CMC OA were enrolled.

Neuropsychological Change After a Single Season of Head Impact Exposure in Youth Football.

Objectives: Head impact exposure (HIE) in youth football is a public health concern. The objective of this study was to determine if one season of HIE in youth football was related to cognitive changes.

Method: Over 200 participants (ages 9-13) wore instrumented helmets for practices and games to measure the amount of HIE sustained over one season.

Proximal-distal shift of the center of rotation in a total wrist arthroplasty is more than twice of the healthy wrist.

Reproduction of healthy wrist biomechanics should minimize the abnormal joint forces that could potentially result in the failure of a total wrist arthroplasty (TWA). To date, the in vivo kinematics of TWA have not been measured and it is unknown if TWA preserves healthy wrist kinematics. Therefore, the purpose of this in vivo study was to determine the center of rotation (COR) for a current TWA design and to compare its location to the healthy wrist.