A Cadaveric Comparison of the Kinematic and Anatomical Axes and Arthrokinematics of the Metatarsosesamoidal and First Metatarsophalangeal Joints.

Presently, developments in weightbearing computed tomography and biplanar fluoroscopy technologies offer exciting avenues for investigating normative and pathologic foot function with increasing precision. Still, data quantifying sesamoid bone and proximal phalange motion are currently sparse. To express joint kinematics and compare various clinical cohorts, future studies of first ray motion will necessitate robust coordinate frames that respect the variations in underlying anatomy while also aligning closely with the functional, physiological axes of motion.

Displacement of the Metatarsal Sesamoids in Relation to First Metatarsophalangeal Joint Extension.

Background: Quantifying normal sesamoid movement in relation to first metatarsophalangeal joint (MTPJ1) motion is essential to identifying aberrant kinematics and understanding how they may contribute to forefoot pain and dysfunction. The present study aims to report sesamoid displacement in relation to MTPJ1 extension and to compare sesamoid displacement with MTPJ1 range of motion (ROM) from several imaging modalities.

Methods: Using 10 fresh frozen cadaveric feet, sesamoid displacement was evaluated during simulated MTPJ1 extension.

Foot radiographic angle variation as a function of weightbearing magnitude.

Weightbearing radiographs are widely used to investigate foot disorders. However, it is unclear how imaging during partial weightbearing affects foot alignment measurements. This study aimed to determine a partial weightbearing threshold that yields consistent measurements of various radiographic angles.

Evaluation of the Foot Arch in Partial Weightbearing Conditions.

Background: Weightbearing plain radiography or computed tomography (CT) is used for diagnosis or treatment selection in foot disorders. This study compared foot alignment between full weightbearing (50% body weight [BW] per foot) plain radiography and nonweightbearing (0% BW) or partial weightbearing (10% BW per foot) CT scans.

Methods: Subjects had both full (50% BW per foot) weightbearing plain radiographs and either a nonweightbearing (0% BW) or a partial weightbearing (20% BW or 10% BW per foot) CT scan.

Neuropathy, claw toes, intrinsic muscle volume, and plantar aponeurosis thickness in diabetic feet.

Background: The objective of this study was to explore the relationships between claw toe deformity, peripheral neuropathy, intrinsic muscle volume, and plantar aponeurosis thickness using computed tomography (CT) images of diabetic feet in a cross-sectional analysis.

Methods: Forty randomly-selected subjects with type 2 diabetes were selected for each of the following four groups (n = 10 per group): 1) peripheral neuropathy with claw toes, 2) peripheral neuropathy without claw toes, 3) non-neuropathic with claw toes, and 4) non-neuropathic without claw toes. The intrinsic muscles of the foot were segmented from processed CT images.

Tibiofemoral Cartilage Contact Differences Between Level Walking and Downhill Running.

Background: Some studies have suggested that altered tibiofemoral cartilage contact behavior (arthrokinematics) may contribute to long-term cartilage degeneration, potentially leading to tibiofemoral osteoarthritis. However, few studies have assessed normal tibiofemoral arthrokinematics during dynamic activities.

Purpose: To characterize tibiofemoral arthrokinematics during the impact phase of level walking and downhill running.

Alteration of Knee Kinematics After Anatomic Anterior Cruciate Ligament Reconstruction Is Dependent on Associated Meniscal Injury.

Background: Limited in vivo kinematic information exists on managing meniscal injury during anterior cruciate ligament reconstruction (ACLR).

Hypothesis: Isolated anatomic ACLR restores knee kinematics, whereas ACLR in the presence of medial meniscal injury is associated with altered long-term knee kinematics.

Study Design: Cohort study; Level of evidence, 3.

In vivo tibiofemoral skeletal kinematics and cartilage contact arthrokinematics during decline walking after isolated meniscectomy.

We investigated the effects of isolated meniscectomy on tibiofemoral skeletal kinematics and cartilage contact arthrokinematics in vivo. We recruited nine patients who had undergone isolated medial or lateral meniscectomy, and used a dynamic stereo-radiography (DSX) system to image the patients' knee motion during decline walking. A volumetric model-based tracking process determined 3D tibiofemoral kinematics from the recorded DSX images.

Three-dimensional isotropic magnetic resonance imaging can provide a reliable estimate of the native anterior cruciate ligament insertion site anatomy.

Purpose: This study quantified the error in anterior cruciate ligament (ACL) insertion site location and area estimated from three-dimensional (3D) isotropic magnetic resonance imaging (MRI) by comparing to native insertion sites determined via 3D laser scanning.

Methods: Isotropic 3D DESS MRI was acquired from twelve fresh-frozen, ACL-intact cadaver knees. ACL insertion sites were manually outlined in each MRI slice, and the resulting contours combined to determine the 3D insertion site shape.

In Vivo Analysis of Dynamic Graft Bending Angle in Anterior Cruciate Ligament-Reconstructed Knees During Downward Running and Level Walking: Comparison of Flexible and Rigid Drills for Transportal Technique.

Purpose: To determine the in vivo dynamic graft bending angle (GBA) in anterior cruciate ligament (ACL)-reconstructed knees, correlate the angle to tunnel positions and tunnel widening, and evaluate the effects of 2 femoral tunnel drilling techniques on GBA.

Methods: Patients with an isolated ACL injury undergoing reconstruction from 2011 to 2012 were included. Transportal techniques were used to create femoral tunnels.

Is There a Difference in Graft Motion for Bone-Tendon-Bone and Hamstring Autograft ACL Reconstruction at 6 Weeks and 1 Year?

Background: Bone-patellar tendon-bone (BTB) grafts are generally believed to heal more quickly than soft tissue grafts after anterior cruciate ligament (ACL) reconstruction, but little is known about the time course of healing or motion of the grafts within the bone tunnels.

Hypothesis: Graft-tunnel motion will be greater in hamstring (HS) grafts compared with BTB grafts and will be less at 1 year than at 6 weeks.

Study Design: Controlled laboratory study.

In vivo posterior cruciate ligament elongation in running activity after anatomic and non-anatomic anterior cruciate ligament reconstruction.

Purpose: The goals of this study were to (1) investigate the in vivo elongation behaviour of the posterior cruciate ligament (PCL) during running in the uninjured knee and (2) evaluate changes in PCL elongation during running after anatomic or non-anatomic anterior cruciate ligament (ACL) reconstruction.

Methods: Seventeen unilateral ACL-injured subjects were recruited after undergoing anatomic (n = 9) or non-anatomic (n = 8) ACL reconstruction. Bilateral high-resolution CT scans were obtained to produce 3D models.

The Effects of Anterior Cruciate Ligament Deficiency on the Meniscus and Articular Cartilage: A Novel Dynamic In Vitro Pilot Study.

Background: Anterior cruciate ligament (ACL) injury increases the risk of meniscus and articular cartilage damage, but the causes are not well understood. Previous in vitro studies were static, required extensive knee dissection, and likely altered meniscal and cartilage contact due to the insertion of pressure sensing devices.

Hypothesis: ACL deficiency will lead to increased translation of the lateral meniscus and increased deformation of the medial meniscus as well as alter cartilage contact location, strain, and area.

Variation in the shape of the tibial insertion site of the anterior cruciate ligament: classification is required.

Purpose: To propose a classification system for the shape of the tibial insertion site (TIS) of the anterior cruciate ligament (ACL) and to demonstrate the intra- and inter-rater agreement of this system. Due to variation in shape and size, different surgical approaches may be feasible to improve reconstruction of the TIS.

Methods: One hundred patients with a mean age of 26 ± 11 years were included.

Quantitative In Situ Analysis of the Anterior Cruciate Ligament: Length, Midsubstance Cross-sectional Area, and Insertion Site Areas.

Background: Quantification of the cross-sectional area (CSA) of the anterior cruciate ligament (ACL) in different loading conditions is important for understanding the native anatomy and thus achieving anatomic reconstruction. The ACL insertion sites are larger than the ACL midsubstance, and the isthmus (region of the smallest CSA) location may vary with the load or flexion angle.

Purpose: To (1) quantify the CSA along the entire ACL, (2) describe the location of the ACL isthmus, (3) explore the relationship between ACL length and CSA, and (4) validate magnetic resonance imaging (MRI) for assessing the CSA of the midsubstance ACL.

Validation of a method for combining biplanar radiography and magnetic resonance imaging to estimate knee cartilage contact.

Combining accurate bone kinematics data from biplane radiography with cartilage models from magnetic resonance imaging, it is possible to estimate tibiofemoral cartilage contact area and centroid location. Proper validation of such estimates, however, has not been performed under loading conditions approximating functional tasks, such as gait, squatting, and stair descent. The goal of this study was to perform an in vitro validation to resolve the accuracy of cartilage contact estimations in comparison to a laser scanning gold standard.

Altered tibiofemoral kinematics in the affected knee and compensatory changes in the contralateral knee after anterior cruciate ligament reconstruction.

Background: Previous studies of knee kinematics after anterior cruciate ligament (ACL) reconstruction have generally employed low-effort tasks and typically not assessed changes in kinematics over time.

Hypotheses: (1) During single-legged hop landing, ACL-reconstructed limbs will have altered kinematics compared with contralateral (ACL-intact) limbs 5 months after surgery. (2) Kinematic differences between limbs will decrease over time because of changes in both ACL-reconstructed and ACL-intact limbs.

Knee rotation influences the femoral tunnel angle measurement after anterior cruciate ligament reconstruction: a 3-dimensional computed tomography model study.

Purpose: Femoral tunnel angle (FTA) has been proposed as a metric for evaluating whether ACL reconstruction was performed anatomically. In clinic, radiographic images are typically acquired with an uncertain amount of internal/external knee rotation. The extent to which knee rotation will influence FTA measurement is unclear.

Medial portal drilling: effects on the femoral tunnel aperture morphology during anterior cruciate ligament reconstruction.

Background: A goal of anatomic anterior cruciate ligament (ACL) reconstruction should be to create a femoral tunnel aperture that resembles the native attachment site in terms of size and orientation. Aperture morphology varies as a function of the drill-bit diameter, the angle in the horizontal plane at which the drilled tunnel intersects the lateral notch wall (transverse drill angle), and the angle of knee flexion in the vertical plane during drilling.

Methods: A literature search was conducted to determine population-based dimensions of the femoral ACL footprint.

Cervical spine bone mineral density as a function of vertebral level and anatomic location.

Background Context: Bone mineral density (BMD) measurements acquired from quantitative computed tomography scans have been shown to correlate with bone mechanical properties such as strength, stiffness, and yield load. There are currently no reports of BMD as a function of anatomic location within each vertebra.

Purpose: The overall objective of this study was to characterize BMD in the cervical spine as a function of level and anatomic location.