Zaneb Yaseen

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.

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.

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.

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.

Investigation of the peak action wavelength of light-activated gene transduction.

Light-activated gene transduction (LAGT) is an approach to localize gene therapy via preactivation of cells with UV light, which facilitates transduction by recombinant adeno-associated virus vectors. Previous studies demonstrated that UVC induces LAGT secondary to pyrimidine dimer formation, whereas UVA induces LAGT secondary to reactive-oxygen species (ROS) generation. However, the empirical UVB boundary of these UV effects is unknown. Thus, we aimed to define the action spectra for UV-induced LAGT independent of DNA damage and determine an optimal wavelength to maximize safety and efficacy. UV at 288, 311 and 320 nm produced significant dose-dependent LAGT effects, of which the maximum (800-fold) was observed with 4 kJ m−2 at 311 nm. Consistent with its robust cytotoxicity, 288 nm produced significantly high levels of DNA damage at all doses tested, whereas 311, 320 and 330 nm did not generate pyrimidine dimers and produced low levels of DNA damage detected by comet assay. Although 288 nm failed to induce ROS, the other wavelengths were effective, with the maximum (10-fold) effect observed with 30 kJ m−2 at 311 nm. An in vivo pilot study assessing 311 nm-induced LAGT of rabbit articular chondrocytes demonstrated a significant 6.6-fold (P<0.05) increase in transduction with insignificant cytotoxicity. In conclusion, 311 nm was found to be the optimal wavelength for LAGT on the basis of its superior efficacy at the peak dose and its broad safety range that is remarkably wider than the other UV wavelengths tested.

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 Coracoclavicular Fixation on the Stability of Type Iib Distal Clavicle Fractures Fixed with a Superior Locking Plate and Screws

DATA Purpose: Surgical treatment of distal clavicle fractures is controversial. The role of coracoclavicular (CC) fixation on biomechanical stability in fractures fixed with plate and screws is not known. Our hypothesis is that coracoclavicular fixation will add stability to type IIB distal clavicle fractures treated with a superior locking plate and screws by neutral- izing supero-inferior translational forces in the coronal plane. Materials and Methods: Twelve fresh frozen cadaveric specimens were used to create type IIB distal clavicle fractures in consistent manner. Matched pairs and DEXA scans were used to ensure similar bone quality. Group I (6 specimens) consisted of specimens stabilized with a supe- rior precontoured distal clavicle locking plate, screws and supplemental coracoclavicular fixation using a suture anchor device. Group II (6 matched contralateral speci- mens) was the same construct without coracoclavicular fixation. Each specimen was cyclically loaded in the coronal plane at 40 to 80 N for 17,500 cycles (equivalent to cyclic loading on the protected shoulder in ambulating patient for 1 week). Load to failure testing up to 1000N was then performed on the specimens that did not fail cyclical loading. Outcome measures included the mode of failure and either the number of cycles or maximum load required to create 10 mm of displacement in the construct.