Increased Lateral Tibial Plateau Slope Predisposes Male College Football Players to Anterior Cruciate Ligament Injury.

BACKGROUND: There are conflicting reports regarding the role of osseous morphologic characteristics such as an increased tibial slope as associated with an anterior cruciate ligament (ACL) injury. Few studies have analyzed the role of a combination of osseous morphologic characteristics in matched case control studies. The aim of this study was to determine if there is an association between osseous morphologic characteristics and ACL injury in male college American-football players. METHODS: Ninety male U.S. National Collegiate Athletic Association (NCAA) Division-I college football players who underwent magnetic resonance imaging (MRI) for a knee injury between 2005 and 2014 were included. Subjects with an ACL injury (ACL-injured group) were matched for age, height, weight, and body mass index to subjects without an ACL injury (control group). Several osseous morphologic characteristics including medial and lateral condylar width, medial and lateral plateau width, notch width, bicondylar width, notch width index, and medial and lateral tibial slopes were measured and were compared between groups. Conditional logistic regression was used to analyze the data. Significance was set at p < 0.05. RESULTS: According to univariable analysis, a narrower lateral femoral condyle (odds ratio, 0.82 [95% confidence interval (95% CI), 0.68 to 0.97]), increased medial tibial plateau slope (odds ratio, 1.42 [95% CI, 1.09 to 1.85]), and increased lateral tibial plateau slope (odds ratio, 1.43 [95% CI, 1.15 to 1.78]) were significantly associated with ACL injury. Multivariable analysis revealed that increased lateral tibial slope (odds ratio, 1.32 [95% CI, 1.03 to 1.70]) was the sole independent predictor of ACL injury. CONCLUSIONS: Based on this study, osseous morphology, specifically increased lateral tibial slope, is associated with ACL injury in male college football players. These data might help to improve prevention strategies to lower ACL injury. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

The Effect of the Epitendinous Suture on Gliding in a Cadaveric Model of Zone II Flexor Tendon Repair.

PURPOSE: We hypothesized that increasing core sutures (4-6) may be preferable in terms of gliding coefficient (GC) measurements when compared with adding an epitendinous suture to zone II flexor tendon repairs. We hypothesized that the inclusion of epitendinous suture in 2 standard repairs would contribute negatively to the GC of the repaired tendon. METHODS: Nineteen fresh-frozen cadaveric fingers were used for testing. We compared a control group (dissected digits without repair) and 4-strand or 6-strand core tendon repairs with and without epitendinous suture. Arc of motion was driven by direct loading, and digital images were acquired and analyzed. Outcomes were defined as the difference in GC between the native uninjured and the repaired state at each load. A linear mixed-model analysis was performed with comparisons between repairs to evaluate the statistically relevant differences between groups. RESULTS: The test of fixed effects in the linear model revealed that repair type and the use of epitendinous suture significantly affected the change in GC. The addition of an epitendinous suture produced a significant decrement in gliding regardless of repair type. CONCLUSIONS: There was significant improvement in GC with the omission of the epitendinous suture in both repair types (4- or 6-strand). CLINICAL RELEVANCE: The epitendinous suture used in this model resulted in poorer gliding of the repair, which may correspond with an expected increase in catching or triggering.

Flexor digitorum superficialis repair outside the A2 pulley after zone II laceration: gliding and bowstringing.

PURPOSE: To evaluate the changes in maximum flexion angle, gliding coefficient, and bowstringing after a combined repair of both flexor tendons with the flexor digitorum superficialis (FDS) rerouted outside the A2 pulley in cadaveric hands. METHODS: We performed 4 different repairs on cadaveric hands, with each repair tested on 9 unique digits. In total, 12 cadaveric hands and 36 digits were used. The thumb and little finger were removed from each hand and excluded from testing. Group 1 was sham surgery. Group 2 combined flexor digitorum profundus (FDP) and FDS laceration and repair with both slips of the FDS repaired inside the A2 pulley. Group 3 was FDP repair with one slip of the FDS repaired inside A2 and the other slip left unrepaired. Group 4 was FDP repair with both slips of the FDS rerouted and repaired outside the A2 pulley. Maximum flexion angle, gliding coefficient, and bowstringing were measured in simulated active digital motion for each group. RESULTS: Rerouting and repairing the FDS outside the A2 pulley (group 4) significantly lowered gliding coefficient compared with repairs with both slips inside A2, with values similar to sham surgery. We observed no significant differences in maximum flexion angle among the 4 groups. Increased bowstringing was observed with both slips of the FDS repaired and rerouted outside the A2 pulley. CONCLUSIONS: In this cadaveric model, repair of both slips of the FDS outside the A2 pulley improved the gliding coefficient relative to repair within the A2 pulley, which suggests decreased resistance to finger flexion. Repair of the FDS outside the A2 pulley led to a slight increase in bowstringing of the FDS tendon. CLINICAL RELEVANCE: We describe a technique for managing combined laceration of the FDP and FDS tendons that improves gliding function and merits consideration.

The Effect of Pulley Reconstruction on Maximum Flexion, Bowstringing, and Gliding Coefficient in the Setting of Zone II Repair of FDS and FDP: a Cadaveric Investigation.

PURPOSE: The purpose of this experiment was to determine the effect of A2 pulley reconstruction on gliding coefficient (GC), bowstringing, and proximal interphalangeal (PIP) joint maximum flexion angle after zone II repair of flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) lacerations. METHODS: Fresh frozen cadaver forearms were mounted, and the wrist and MCP joints fixed. FDS and FDP tendons were dissected free, and sequential loads were applied while digital images were captured. The dissected digit with intact native A2 pulley, FDS, and FDP tendons was used as the control (group 1). Zone II lacerations followed by four-stranded repair of FDP plus epitendinous suture and repair of FDS were then performed, and the data recorded (group 2). A2 pulley excision and reconstruction with a loop of palmaris longus autograft was then completed and the specimens sequentially loaded and photographed (group 3). Using the digital images, GC, bowstringing, and maximum flexion angle were calculated. RESULTS: No difference in maximum flexion angle was observed across the three testing conditions. Zone II laceration and subsequent FDS and FDP tendon repair significantly increased the GC for group 2 specimens; however, pulley reconstruction alleviated some of this increase for group 3. Bowstringing was significantly greater after pulley reconstruction, with a mean increase of 1.9 mm at maximum flexion for group 3 specimens relative to group 1 controls. DISCUSSION: Strong flexor tendon repairs are needed to prevent gap formation and subsequent triggering; however, the increased bulk from these large repairs can itself produce deleterious triggering, as well as tendon abrasion. Pulley reconstruction, in the setting FDP and FDS repair (group 3), significantly reduced the GC relative to tendon repair alone (group 2). While bowstringing was significantly greater after pulley reconstruction (group 3), it averaged only 1.9 mm over group 1 specimens and did not compromise maximum flexion angle compared to the uninjured controls (group 1) or the isolated tendon repair digits (group 2).

Addition of a suture anchor for coracoclavicular fixation to a superior locking plate improves stability of type IIB distal clavicle fractures.

PURPOSE: The purpose of this study was to determine the effect of coracoclavicular (CC) fixation on biomechanical stability in type IIB distal clavicle fractures fixed with plate and screws. METHODS: Twelve fresh-frozen matched cadaveric specimens were used to create type IIB distal clavicle fractures. Dual-energy x-ray absorptiometry (DEXA) scans ensured similar bone quality. Group 1 (6 specimens) was stabilized with a superior precontoured distal clavicle locking plate and supplemental suture anchor CC fixation. Group 2 (6 specimens) followed the same construct without CC fixation. Each specimen was cyclically loaded in the coronal plane at 40 to 80 N for 17,500 cycles. Load-to-failure testing was performed on the specimens that did not fail cyclic loading. Outcome measures included mode of failure and the number of cycles or load required to create 10 mm of displacement in the construct. RESULTS: All specimens (12 of 12) completed cyclic testing without failure and underwent load-to-failure testing. Group 1 specimens failed at a mean of 808.5 N (range, 635.4 to 952.3 N), whereas group 2 specimens failed at a mean of 401.3 N (range, 283.6 to 656.0 N) (P = .005). Group 1 specimens failed by anchor pullout without coracoid fracture (4 of 6) and distal clavicle fracture fragment fragmentation (1 of 6); one specimen did not fail at the maximal load the materials testing machine was capable of exerting (1,000 N). Group 2 specimens failed by distal clavicle fracture fragment fragmentation (3 of 6) and acromioclavicular (AC) joint displacement (1 of 6); 2 specimens did not fail at the maximal load of the materials testing machine. CONCLUSIONS: During cyclic loading, type IIB distal clavicle fractures with and without CC fixation remain stable. CC fixation adds stability to type IIB distal clavicle fractures fixed with plate and screws when loaded to failure. CLINICAL RELEVANCE: CC fixation for distal clavicle fractures is a useful adjunct to plate-and-screw fixation to augment stability of the fracture.

Relevant anatomic landmarks and measurements for biceps tenodesis.

BACKGROUND: Biceps tenodesis around the pectoralis major insertion may alter resting tension on the biceps, leading to unfavorable clinical outcomes. HYPOTHESIS: The anatomic relationship between the musculotendinous junction (MTJ) of the biceps and the pectoralis major tendon will provide guidelines for anatomic location to perform biceps tenodesis with the goal of re-establishing biceps tension. STUDY DESIGN: Descriptive laboratory study. METHODS: Cadaveric dissections were performed that reflected the pectoralis major tendon and exposed the long head of the biceps tendon (LHBT). Calipers were used to measure the longitudinal width of the pectoralis major tendon at the humerus, 2 cm away from the humerus, and at its proximal expansion on the humerus. The distance from the proximal extent of the pectoralis major tendon footprint to the beginning of the MTJ of the biceps and the length of the MTJ of the biceps were recorded. The location of the distal end of the MTJ of the biceps relevant to the inferior border of the pectoralis major tendon was calculated. RESULTS: The average longitudinal width of the pectoralis major tendon at its humeral insertion was 76.8 mm, the width 2 cm away from the humerus averaged 37.3 mm, and the proximal expansion averaged 13.3 mm. The MTJ of the biceps began an average of 32.4 mm distal from the proximal aspect of the pectoralis major footprint and extended for an average of 78.1 mm. The MTJ of the LHBT was calculated to extend 3.3 cm distal to the inferior border of the pectoralis major footprint. CONCLUSION: The MTJ of the biceps begins further proximal than may be appreciated intraoperatively. Knowledge of the anatomic relationships between the LHBT, its MTJ, and the pectoralis major tendon provides helpful guidelines for the biceps tenodesis site. The final resting spot of the most distal aspect of the MTJ of the LHBT after tenodesis should be approximately 3 cm distal to the inferior edge of the pectoralis major tendon footprint on the humerus.

Murine model of oligotrophic tibial nonunion.

OBJECTIVES: This study aimed to use modified distraction osteogenesis techniques to develop a reliable mouse fracture nonunion model with an oligotrophic phenotype. METHODS: Twenty-six 10- to 14-week-old C57BL/6 male mice underwent a proximal diaphyseal tibial osteotomy with a 2-mm bone resection. An external fixation device was applied to the tibia using cerclage wires. A total of 2.25 mm of distraction was applied over 3 days, resulting in an average distraction gap of 4.28 mm. Plain radiographs were taken at regular intervals until euthanasia at 7 (n = 9), 10 (n = 13), or 12 (n = 4) weeks. After euthanasia, all samples were fixed in formalin, scanned with microcomputed tomography, decalcified in formic acid, prepared in paraffin, and stained with Alcian blue/Mayer's hematoxylin. RESULTS: In the distraction groups, five mice were prematurely euthanized as a result of wound complications stemming from loss of distal fixation. Of the remaining 21, two healed, resulting in a 90% nonunion rate. These nonunions radiographically resembled clinical nonunions with tapered, cone-like fracture ends and histologically demonstrated evidence of attempted healing as seen with cartilage capping. Additionally, the plain radiographic appearance of those nonunions from mice euthanized at 10 and 12 weeks did not change over the final 4 to 6 weeks. CONCLUSIONS: The use of 2-mm tibial resection osteotomy with 2-mm distraction provides a predictable model for fracture nonunion in mice with the oligotrophic phenotype closely resembling the clinical correlate. This model offers a promising means for characterization of the molecular events that occur during the development of fracture nonunion and for evaluation of noninvasive methods of nonunion rescue.

Individual finger sensibility in carpal tunnel syndrome.

PURPOSE: Sensibility testing plays a role in the diagnosis of carpal tunnel syndrome (CTS). No single physical examination test has proven to be of critical value in the diagnosis, especially when compared with electrodiagnostic testing (EDX). The purpose of this study was to define which digits are most affected by CTS, both subjectively and with objective sensibility testing. METHODS: A prospective series of 35 patients (40 hands) with EDX-positive, isolated CTS were evaluated preoperatively using 2 objective sensibility tests: static 2-point discrimination (2PD) and abbreviated Semmes-Weinstein monofilament (SWMF) testing. Detailed surveys of subjective symptoms were also collected. RESULTS: Patients identified the middle finger as the most symptomatic over all others (51%). Objective 2PD results of each digit mirrored the subjective data, with higher values for the middle finger (mean 6.07 mm, (p < .0001). Values for the index finger failed to show a significant difference from the ulnar-innervated small finger. The most symptomatic finger matched 2PD results in over two thirds of patients. The SWMF testing showed similar, statistically significant results (middle > thumb > index > small). Correlations failed between EDX, symptoms, and SWMF results or 2PD in the index finger. Positive but weak correlation (p = .002, r = .42) was found between EDX and 2PD only in the middle fingers. CONCLUSIONS: The middle finger is the most likely to show changes in 2PD in patients with positive EDX findings for CTS. Middle finger 2PD is best able to correlate with EDX when compared with 2PD of other digits. The SWMF testing also shows the middle digit testing as more sensitive, but this finding may be difficult to use clinically. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic I.

Enduring representational plasticity after somatosensory stimulation.

Somatosensory stimulation (SS), leading to increases in motor cortical excitability, influences motor performance in patients with brain lesions like stroke. The mechanisms by which SS modulates motor function are incompletely understood. Here, we used functional magnetic resonance imaging (fMRI, blood-oxygenation-level-dependent (BOLD), and perfusion imagings simultaneously acquired in a 3 T magnet) to assess the effects of SS on thumb-movement-related activation in three regions of interest (ROI) in the motor network: primary motor cortex (M1), primary somatosensory cortex (S1), and dorsal premotor cortex (PMd) in healthy volunteers. Scans were obtained in different sessions before and after 2-h electrical stimulation applied to the median nerve at the wrist (MNS), to the skin overlying the shoulder deltoid muscle (DMS), and in the absence of stimulation (NOSTIM) in a counterbalanced design. We found that baseline perfusion intensity was comparable within and across sessions. MNS but not DMS nor NOSTIM led to an increase in signal intensity and number of voxels activated by performance of median nerve-innervated thumb movements in M1, S1, and PMd for up to 60 min. Task-related fMRI activation changes were most prominent in M1 followed by S1 and to a lesser extent in PMd. MNS elicited a displacement of the center of gravity for the thumb movement representation towards the other finger representations within S1. These results indicate that MNS leads to an expansion of the thumb representation towards other finger representations within S1, a form of plasticity that may underlie the influence of SS on motor cortical function, possibly supporting beneficial effects on motor control.

Age-dependent changes in the ability to encode a novel elementary motor memory.

In healthy individuals, motor training elicits cortical plasticity that encodes the kinematic details of the practiced movements and is thought to underlie recovery of function after stroke. The influence of age on this form of plasticity is incompletely understood. We studied 55 healthy subjects and identified a substantial decrease in training-dependent plasticity as a function of age in the absence of differences in training kinematics. These results suggest that the ability of the healthy aging motor cortex to reorganize in response to training decreases with age.