Geographic Trends in the Orthopedic Surgery Residency Match.

BACKGROUND: Residency program location may be an important factor for orthopedic surgery residency applicants. More than half of residents locate their practice near the site of their training, and surgical specialties (eg, otolaryngology, plastic surgery, and general surgery) have shown geographic patterns in their residency matches. OBJECTIVE: We analyzed geographic trends in the orthopedic surgery Match. METHODS: Hometown, undergraduate institution, and medical school "preresidency locations" of all allopathic, nonmilitary, orthopedic surgery residents were recorded from program websites for the 2015-2016 academic year. Program and preresidency locations were coded according to state and US census division. Statistical analysis was used to investigate associations between residency program locations and preresidency locations. RESULTS: Of 2662 residents in the study, 1220 of 2614 (47%), 536 of 1329 (40%), and 308 of 744 (41%) matched into the same division as their medical school, undergraduate institution, and hometown, respectively. There were significant differences among divisions (P < .001). Also, 817 of 2662 (31%), 319 of 1329 (24%), and 200 of 770 (26%) residents matched in the same state as their medical school, undergraduate institution, and hometown, respectively, with significant differences between states for medical school (P < .0001) and undergraduate institution (P < .0001), but not hometown (P = .22). Overall, 21% of residents (538 of 2612) matched at the program affiliated with their medical school. CONCLUSIONS: There is an association among hometown, undergraduate institution, and medical school for the training program location in which orthopedic surgery residents match, with variability in locations matched at state and census division levels.

An Anatomic Evaluation of Arthroscopic Access to the Radial Head.

PURPOSE: To determine the area of the radial head accessible for visualization and screw placement from the standard anteromedial and anterolateral portals used in elbow arthroscopy. METHODS: Five cadaveric elbows were arthroscopically evaluated using standard anteromedial and anterolateral portals. Markers (pins) were placed into the accessible portions of the radial head at maximal pronation and supination. Specimens were then evaluated by computed tomography, and the arc of the radial head accessible from each portal was determined. RESULTS: A continuous 220.04° ± 37.58° arc of the radial head was accessible from the combination of the anterolateral and anteromedial portals. From the anteromedial portal, the arc obtained measured 147.96° ± 21.81°, and from the anterolateral portal, the arc obtained measured 156.02° ± 33.32°. Using the radial styloid as a marker for 0°, the mean total arc ranged from 92.3° ± 34.06° dorsal to 127.74° ± 23.65° volar relative to the radial styloid. CONCLUSIONS: Standard anteromedial and anterolateral portals used for elbow arthroscopy allow access to an average 220° area of the radial head. CLINICAL RELEVANCE: This study defines the area of the radial head that can be contacted using commonly used, safe, and simple portals.

Biomechanical and Computed Tomography Analysis of Adjustable Femoral Cortical Fixation Devices for Anterior Cruciate Ligament Reconstruction in a Cadaveric Human Knee Model.

PURPOSE: To evaluate and compare two adjustable femoral cortical suspensory fixation devices used for anterior cruciate ligament reconstruction through a novel, direct computed tomography (CT) analysis metric and biomechanical laxity testing in a matched cadaveric human knee study. METHODS: Anterior cruciate ligament reconstructions with bovine tendon grafts were performed using two adjustable femoral cortical suspensory fixation devices (RigidLoop Adjustable [DePuy Synthes Mitek, Raynham, MA] and TightRope [Arthrex, Naples, FL]) in 12 knees (6 matched pairs). A mechanical testing series was used to determine each knee's laxity in the intact condition. After reconstruction, each specimen was again tested for laxity and also imaged with CT. The laxity testing and CT imaging were then repeated after 1,000 cycles of anteroposterior loading on each knee to compare changes in laxity for the two fixation devices and to visualize changes in button-to-graft distance migration through a three-dimensional CT imaging method. RESULTS: No significant differences were found between the two fixation groups' laxity measures after reconstruction (all P values ≥ .620) or after cycling (all P values ≥ .211) at any flexion angle. In addition, no significant differences were found between the two groups regarding button-to-graft distance migration (P = .773; mean, 0.61 ± 0.6 mm [95% confidence interval, -0.1 to 1.3 mm] in RigidLoop Adjustable group and 0.53 ± 0.6 mm [95% confidence interval, -0.1 to 1.2 mm] in TightRope group). CONCLUSIONS: There were no significant differences between the two femoral cortical suspensory adjustable-loop devices regarding laxity outcomes or loop displacement as measured by button-to-graft distance migration. CLINICAL RELEVANCE: Use of either of the adjustable-loop cortical suspensory devices in our analysis would appear to produce similar, acceptable laxity outcomes and minimal effects in terms of device-related loop displacement.

T2* relaxometry and volume predict semi-quantitative histological scoring of an ACL bridge-enhanced primary repair in a porcine model.

Magnetic resonance imaging (MRI) variables, such as T2* and volume, can predict the healing ligament structural properties. How these MR variables relate to semi-quantitative histology of the healing ACL is yet unknown. We hypothesized that T2* and volume would predict the histological scoring of a healing ACL. Yucatan minipigs underwent ACL transection and received bridge-enhanced ACL repair or no treatment. The surgical legs were harvested after 52 weeks and imaged using a high resolution 2-echo sequence. For each ligament, the volume and median T2* values were determined. The ACL specimens were then histologically analyzed using the advanced Ligament Maturity Index (LMI). The T2* of the healing ligaments significantly predicted the total LMI score as well as the cell, collagen and vessel sub-scores; R(2) = 0.78, 0.67, 0.65, and 0.60, respectively (p ≤ 0.001). The ligament volume also predicted the total LMI score, cell, and collagen sub-scores; R(2) = 0.39, 0.33, 0.37, and 0.60, respectively (p ≤ 0.001). A lower ligament T2* or a higher volume was associated with higher histological scores of the healing ligaments. This study provides a critical step in the development of a non-invasive method to evaluate ligament healing on a microscopic scale.

MRI volume and signal intensity of ACL graft predict clinical, functional, and patient-oriented outcome measures after ACL reconstruction.

BACKGROUND: Clinical, functional, and patient-oriented outcomes are commonly used to evaluate the efficacy of treatments after anterior cruciate ligament (ACL) injury; however, these evaluation techniques do not directly measure the biomechanical changes that occur with healing. PURPOSE: To determine if the magnetic resonance (MR) image-derived parameters of graft volume and signal intensity (SI), which have been used to predict the biomechanical (ie, structural) properties of the graft in animal models, correlate with commonly used clinical (anteroposterior [AP] knee laxity), functional (1-legged hop), and patient-oriented outcome measures (Knee Injury and Osteoarthritis Outcome Score [KOOS]) in patients 3 and 5 years after ACL reconstruction. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: Based on a subset of participants enrolled in an ongoing ACL reconstruction clinical trial, AP knee laxity, 1-legged hop test, and KOOS were assessed at 3- and 5-year follow-up. Three-dimensional, T1-weighted MR images were collected at each visit. Both the volume and median SI of the healing graft were determined and used as predictors in a multiple regression linear model to predict the traditional outcome measures. RESULTS: Graft volume combined with median SI in a multiple linear regression model predicted 1-legged hop test at both the 3- and 5-year follow-up visits (R(2) = 0.40, P = .008 and R(2) = 0.62, P = .003, respectively). Similar results were found at the 5-year follow-up for the KOOS quality of life (R(2) = 0.49, P = .012), sport/function (R(2) = 0.37, P = .048), pain (R(2) = 0.46, P = .017), and symptoms (R(2) = 0.45, P = .021) subscores, although these variables were not significant at 3 years. The multiple linear regression model for AP knee laxity at 5-year follow-up approached significance (R(2) = 0.36, P = .088). CONCLUSION: The MR parameters (volume and median SI) used to predict ex vivo biomechanical properties of the graft in an animal model have the ability to predict clinical or in vivo outcome measures in patients at 3- and 5-year follow-up. CLINICAL RELEVANCE: Results from this study may enhance clinical evaluation of graft health by relating the MR parameters of volume and median SI to traditional outcome measures and could potentially aid researchers in determining the appropriate timing for athletes to return to sport.

T2 * MR relaxometry and ligament volume are associated with the structural properties of the healing ACL.

Our objective was to develop a non-invasive magnetic resonance (MR) method to predict the structural properties of a healing anterior cruciate ligament (ACL) using volume and T2 * relaxation time. We also compared our T2 *-based structural property prediction model to a previous model utilizing signal intensity, an acquisition-dependent variable. Surgical ACL transection followed by no treatment (i.e., natural healing) or bio-enhanced ACL repair was performed in a porcine model. After 52 weeks of healing, high-resolution MR images of the ACL tissue were collected. From these images, ligament volumes and T2 * maps were established. The structural properties of the ligaments were determined via tensile testing. Using the T2 * histogram profile, each ligament voxel was binned based on its T2 * value into four discrete tissue sub-volumes defined by specific T2 * intervals. The linear combination of the ligament sub-volumes binned by T2 * value significantly predicted maximum load, yield load, and linear stiffness (R(2) = 0.92, 0.82, 0.88; p < 0.001) and were similar to the previous signal intensity based method. In conclusion, the T2 * technique offers a highly predictive methodology that is a first step towards the development of a method that can be used to assess ligament healing across scanners, studies, and institutions.

Effect of insertion of a single interference screw on the mechanical properties of porcine anterior cruciate ligament reconstruction grafts.

The objective of this study was to evaluate the mechanical properties of soft-tissue grafts following a single interference screw insertion of 4 different commercially available bioabsorbable interference screws. Twenty-four bovine proximal tibiae (12 matched pairs) were prepared and sagittally split to make 48 bone samples for testing. Tibiae were prepared for a 9 mm porcine tendon graft and were instrumented with 1 of 4 commercially available 10 x 35 mm composite screws, each with a different thread design. The samples were tensile loaded to failure at 200 mm/min and values for yield load, maximum load, and stiffness were recorded to quantify any differences on the function of the grafts. No graft showed macroscopic evidence of laceration following screw insertion and there were no statistically significant differences for yield load (P = .41), maximum load (P = .35), or stiffness (P = .68) among the different screw types. There is no significant difference in the mechanical properties of an anterior cruciate ligament graft following insertion of the 4 bioabsorbable screws tested in this study, in terms of yield load, stiffness, or failure load.

In Situ, noninvasive, T2*-weighted MRI-derived parameters predict ex vivo structural properties of an anterior cruciate ligament reconstruction or bioenhanced primary repair in a porcine model.

BACKGROUND: Magnetic resonance imaging (MRI) is a noninvasive technology that can quantitatively assess anterior cruciate ligament (ACL) graft size and signal intensity. However, how those properties relate to reconstructed or repaired ligament strength during the healing process is yet unknown. HYPOTHESIS: Magnetic resonance imaging-derived measures of graft volume and signal intensity are significant predictors of the structural properties of an ACL or ACL graft after 15 weeks and 52 weeks of healing. STUDY DESIGN: Controlled laboratory study. METHODS: The current data were gathered from 2 experiments evaluating ACL reconstruction and repair techniques. In the first experiment, pigs underwent unilateral ACL transection and received (1) ACL reconstruction, (2) ACL reconstruction with collagen-platelet composite (CPC), or (3) no treatment. The surgical legs were harvested after 15 weeks of healing. In the second experiment, pigs underwent ACL transection and received (1) ACL reconstruction, (2) ACL reconstruction with CPC, (3) bioenhanced ACL primary repair with CPC, or (4) no treatment. The surgical legs were harvested after 52 weeks. The harvested knees were imaged using a T2*-weighted 3-dimensional constructive interference in steady state (CISS) sequence. Each ligament was segmented from the scans, and the intra-articular volume and the median grayscale values were determined. Mechanical testing was performed to establish the ligament structural properties. RESULTS: Volume significantly predicted the structural properties (maximum load, yield load, and linear stiffness) of the ligaments and grafts (R (2) = 0.56, 0.56, and 0.49, respectively; P ≤ .001). Likewise, the median grayscale values (ie, signal intensity) significantly predicted the structural properties of the ligaments and grafts (R (2) = 0.42, 0.37, and 0.40, respectively; P < .001). The combination of these 2 parameters in a multiple regression model improved the predictions (R (2) = 0.73, 0.72, and 0.68, respectively; P ≤ .001). CONCLUSION: Volume and grayscale values from high-resolution T2*-weighted MRI scans are predictive of structural properties of the healing ligament or graft in a porcine model. CLINICAL RELEVANCE: This study provides a critical step in the development of a noninvasive method to predict the structural properties of the healing ACL graft or repair. This technique may prove beneficial as a surrogate outcome measure in preclinical animal and clinical studies.

Biomechanical comparison of parallel versus 90-90 plating of bicolumn distal humerus fractures with intra-articular comminution.

PURPOSE: To compare the biomechanical properties of 90-90 versus mediolateral parallel plating of C-3 bicolumn distal humerus fractures. METHODS: We created intra-articular AO/Orthopaedic Trauma Association C-3 bicolumn fractures in 10 fresh-frozen matched pairs of cadaveric elbows. We determined bone mineral density of the metaphyseal region with dual-energy x-ray absorptiometry. The matched pairs of elbows were randomly assigned to either 90-90 or parallel plate fixation. We tested anteroposterior displacement at a rate of 0.5 mm/s to a maximum load of ± 100 N for both the articular and entire distal humerus segments. We tested torsional stability at a displacement rate of 0.1 Hz to a maximum torque of ± 2.5 Nm. After cyclical testing, we loaded the specimens in torsion to failure. RESULTS: There was no significant difference in the bone density of the paired specimens. Compared with parallel fixation, 90-90 plate fixation had significantly greater torque to failure load. Both plating constructs were equally sensitive to bone density. Both techniques had the same mode of failure in torsion, a spiral fracture extending from the medial plate at the metaphyseal-diaphyseal junction. There was no significant difference in the stiffness of fixation of the articular fragment or the entire distal segment in anteroposterior loading. CONCLUSIONS: This study demonstrated that 90-90 and parallel plating had comparable biomechanical properties for fixation of comminuted intra-articular distal humerus fractures, and that 90-90 plating had greater resistance to torsional loading.

Examination of cervical spine kinematics in complex, multiplanar motions after anterior cervical discectomy and fusion and total disc replacement.

BACKGROUND: The biomechanical behavior of total disc replacement (TDR) and anterior cervical discectomy and fusion (ACDF) incomplex multiplanar motion is incompletely understood. The purpose of this study was to determine whether ACDF or TDR significantly affects in vitro kinematics through a range of complex, multiplanar motions. METHODS: Seven human cervical spines from C4-7 were used for this study. Intact cervical motion segments with and without implanted TDR and ACDF were tested by use of unconstrained pure bending moment testing fixtures in 7 mechanical modes: axial rotation (AR); flexion/extension (FE); lateral bending (LB); combined FE and LB; combined FE and AR; combined LB and AR; and combined FE, LB, and AR. Statistical testing was performed to determine whether differences existed in range of motion (ROM) and stiffness among spinal segments and treatment groups for each mechanical test mode. RESULTS: ACDF specimens showed increased stiffness compared with the intact and TDR specimens (P < .001); stiffness was not found to be different between TDR and intact specimens. ACDF specimens showed decreased ROM in all directions compared with TDR and intact specimens at the treated level. For the coupled motion test, including AR, LB, and FE, the cranial adjacent level (C4/C5) for the intact specimens (2.7°) showed significantly less motion compared with both the TDR (6.1°, P = .009) and ACDF (6.8°, P = .002) treatment groups about the LB axis. Testing of the C4/C5 and C6/C7 levels in all other test modes yielded no significant differences in ROM comparisons, although a trend toward increasing ROM in adjacent levels in ACDF specimens compared with intact and TDR specimens was observed. CONCLUSIONS: This study compared multiplanar motion under load-displacement testing of subaxial cervical motion segments with and without implanted TDR and ACDF. We found a trend toward increased motion in adjacent levels in ACDF specimens compared with TDR specimens. Biomechanical multiplanar motion testing will be useful in the ongoing development and evaluation of spinal motion-preserving implants.