Preoperative Patient Reported Outcomes Predict Postoperative Clinical Outcomes Following Rotator Cuff Repair.

PURPOSE: The purpose of this study was to determine whether preoperative patient-reported outcomes (PROs) predict postoperative PROs and satisfaction following rotator cuff repair. METHODS: We retrospectively identified patients who underwent a primary rotator cuff repair at a single institution. A receiver operating characteristics (ROC) analysis was used to reach a preoperative American Shoulder and Elbow Surgeons (ASES) score threshold predictive of postoperative ASES and satisfaction scores. We evaluated patients above and below the ROC threshold by comparing their final ASES scores, ASES change (Δ) from baseline, percent maximum outcome improvement (%MOI), and achievement of minimum clinically important differences (MCID), substantial clinical benefit (SCB), and patient-acceptable symptom state (PASS). Fischer exact tests were used to analyze categorical data, while continuous data were analyzed using t-test. RESULTS: A total of 348 patients who underwent rotator cuff repair were included in this study. The preop ASES value predictive of achieving SCB was 63 (area under the curve [AUC], 0.75; 95% confidence interval: 58-67; P < .001). Patients with preoperative ASES less than 63 were significantly more likely to achieve MCID (odds ratio [OR]: 4.7, P < .001) and SCB (OR:6.1, P < .001) and had significantly higher %MOI (63% vs 41%; P = 0.003) and Δ ASES scores (36 vs 12; P < .001). However, patients with preop ASES scores above 63 had significantly higher final ASES scores (86 vs 79; P = .003), were more likely to achieve PASS (59% vs 48%; P = .045), and had higher satisfaction scores (7.4 vs 6.7; P = .024). CONCLUSIONS: Patients with high preop ASES scores achieve less relative improvement; however, these patients may be more likely to achieve PASS and may have higher satisfaction scores postoperatively. LEVEL OF EVIDENCE: Level III, retrospective comparative prognostic trial.

Plate Fixation With Cancellous Graft for Scaphoid Nonunion With Avascular Necrosis.

PURPOSE: Currently, there is no consensus on the optimal treatment for scaphoid nonunion with avascular necrosis (AVN). Various techniques, often involving vascularized corticocancellous bone grafting, have been proposed. The authors hypothesized that similar outcomes might be possible with volar plate fixation augmented with autogenous pure cancellous graft. METHODS: The authors performed a retrospective chart review of 13 cases of scaphoid nonunions with AVN in 12 patients treated with plate fixation and pure cancellous bone grafting. Surgical management included a volar incision, reduction, impaction of cancellous bone graft from the ipsilateral olecranon and/or distal radius, and application of a volar locking plate. Postoperative outcome measures included time to union based on computed tomography, patient-reported pain and disability scores, grip strength, range of motion, and return to work and sports. RESULTS: The average patient was 32 years old (range, 17-50 years) and treated an average of 18 months after initial injury (range, 6-49 months). Two of 12 patients (15.7%) were female, 3 of 12 patients (25%) were smokers, and 5 of 12 patients (41.7%) had failed union with previous screw fixation. Twelve scaphoids (92.3%) were treated for AVN associated with a proximal pole fracture, and 1 (7.7%) for AVN proximal to a scaphoid waist fracture. Mean follow-up was 19.5 months (range, 12-29 months). Union was achieved in all patients. Two scaphoids (15%) achieved union by 12 weeks, 7 scaphoids (54%) by 18 weeks, 2 scaphoids (15%) by 24 weeks, and 2 scaphoids (15%) by 30 weeks (range, 8.9-28 weeks). Mean Disabilities of the Arm, Shoulder, and Hand score improved from 30.6 ± 6.2 before surgery to 17.2 ± 6.5 after surgery. All 11 employed patients returned to work, although 3 (27.2%) did not return to full capacity. CONCLUSIONS: Scaphoid plate fixation and pure nonvascularized cancellous bone grafting for scaphoid nonunion with AVN yields excellent union rates and good patient-reported and functional outcomes. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Biofilm Antimicrobial Susceptibility Increases With Antimicrobial Exposure Time.

BACKGROUND: The antimicrobial concentration required to kill all the bacteria in a biofilm, known as the minimum biofilm eradication concentration (MBEC), is typically determined in vitro by exposing the biofilm to serial concentrations of antimicrobials for 24 hours or less. Local delivery is expected to cause high local levels for longer than 24 hours. It is unknown if longer antimicrobial exposures require the same concentration to eradicate bacteria in biofilm. Questions/purposes Does MBEC change with increased antimicrobial exposure time? METHODS: Biofilms were grown for 24 hours using five pathogens (methicillin-sensitive Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa) and then exposed to four antimicrobials regimens: tobramycin, vancomycin, and tobramycin combined with vancomycin in 3:1 and 1:1 ratios by weight in concentrations of 62.5, 125, 250, 500, 1000, 2000, 4000, and 8000 µg/mL for three durations, 1, 3, and 5 days, in triplicate. MBEC was measured as the lowest concentration that killed all bacteria in the biofilm determined by 21-day subculture. RESULTS: MBEC was lower when antimicrobial exposure time was longer. For the staphylococcus species, the MBEC was lower when exposure time was 5 days than 1 day in 11 of 12 antimicrobial/microorganism pairs. The MBEC range for these 11 pairs on Day 1 was 4000 to > 8000 µg/mL and on Day 5 was < 250 to 8000 µg/mL. MBEC for tobramycin/P. aeruginosa was 2000 µg/mL on Day 1 and ≤ 250 µg/mL on Day 5, and for E. coli, 125 µg/mL on Day 1 and ≤ 62.5 on Day 5. CONCLUSIONS: Although antimicrobial susceptibility was lower for longer exposure times in the microorganisms we studied, confirmation is required for other pathogens. Clinical Relevance One-day MBEC assays may overestimate the local antimicrobial levels needed to kill organisms in biofilm if local levels are sustained at MBEC or above for longer than 24 hours. Future studies are needed to confirm that antimicrobial levels achieved clinically from local delivery are above the MBEC at relevant time points and to confirm that MBEC for in vitro microorganisms accurately represents MBEC of in vivo organisms in an clinical infection.

Threaded Intramedullary Nails Are Biomechanically Superior to Crossed K-wires for Metacarpal Neck Fractures.

BACKGROUND: Intramedullary nail (IMN) fixation of metacarpal fractures is an alternative to Kirschner wire (K-wire) fixation. The goal of this study was to compare the biomechanical properties of K-wire fixation with a threaded IMN (InNate; ExsoMed, Aliso Viejo, California). METHODS: The study design was based on previously described biomechanical models for evaluating metacarpal fractures. Sixteen fresh frozen small finger-matched and ring finger-matched pairs were randomized to either IMN or 0.045 in K-wire fixation after receiving a standardized neck osteotomy. Proper implant placement was confirmed with plain radiographs. Specimens then underwent loading in a 3-point bend configuration. Load to failure (LTF), stiffness, and fracture displacement were recorded. Mechanical failure was defined by a sharp change in the load-displacement curve. RESULTS: Age, sex, sidedness (left or right), and digit (ring or small finger) were evenly distributed between groups. The IMN had a significantly higher LTF than K-wires (546 N vs 154 N, P < .001). The K-wire fixation demonstrated plastic deformation between 75 and 150 N. Intramedullary nail stiffness was higher than that of K-wires (155.89 N/mm vs 59.28 N/mm, P < .001). CONCLUSIONS: When surgical fixation is indicated for metacarpal neck and shaft fractures, the threaded IMN is biomechanically superior to crossed K-wires with the application of 3-point bend.

Biomechanical comparison of tuberosity-based proximal humeral locking plate compared to standard proximal humeral locking plate in varus cantilever bending.

PURPOSE: In a prior biomechanical study using a tuberosity-based proximal humeral locking plate (TBP) an improvement in greater tuberosity (GT) fixation strength with the TBP compared to a standard proximal humeral locking plate (PHLP) was demonstrated. The purpose of this study is to compare the TBP to the PHLP with a simulated calcar gap fracture under cyclic varus cantilever forces. METHODS: Seven matched pairs of cadaveric humeri were studied and 11A2.3 proximal humerus fractures were created by a 1 cm gap osteotomy at the surgical neck. Matched pairs were randomized for fixation using either a PHLP or a TBP. The proximal articular aspect of the humerus was potted and secured to the base of a load frame. The shaft was subjected to cyclic varus cantilever loading with a roller positioned 8 cm from the osteotomy. Change in vertical displacement of the diaphyseal fragment was monitored and digital images were obtained. Failure was defined as vertical displacement greater than 20 mm. Specimens not exhibiting failure over the course of 10,000 cycles were then loaded to 20 mm of vertical displacement. Reactant forces of the specimens at these displacements were recorded. RESULTS: Four/seven TBP specimens and four/seven PHLP specimens survived 10,000 cycles. The average cycles to failure for TBP specimens was 7325 cycles and 5715 cycles for PHLP specimens (p = 0.525). For the specimens that survived 10,000 cycles, the decrease in calcar gap was superior in the TBP specimens (p = 0.018). A similar trend was seen when these specimens were loaded to failure where the percent calcar gap recovery was higher for the TBP at 74.71 ± 10.07% versus 53.22 ± 30.35% for the PHLP (p = 0.072). In specimens that were loaded to failure after survival of 10,000 cycles the average stiffness of the TBP construct was 20.51 N/mm, and 11.74 N/mm for the PHLP construct (p = 0.024). CONCLUSION: In addition to superior GT fixation shown in a prior study, the TBP construct demonstrates significantly greater stiffness at the neck fracture compared to the PHLP, when loaded to failure. In addition, there was a trend towards less collapse in this calcar gap model.

Using the Greater Tuberosity as a Reference for Placement of Proximal Humerus Plates Leads to a High Rate of Calcar Screw Malposition.

OBJECTIVES: Achieving calcar fixation is critical to minimize the failure of proximal humerus fractures repaired with proximal humeral locking plates (PHLPs). Many operative technique manuals reference the greater tuberosity (GT) for plate placement. The objective of this study was to examine the accuracy of calcar screw placement when PHLPs were placed based on distance from the GT. METHODS: Twenty cadaveric specimens were acquired representing a height distribution across the US population. Thirteen different PHLPs were applied. A drill bit was placed through the designated calcar screw hole and measured on radiographs, with the inferior 25% of the head representing an ideal placement. RESULTS: Three hundred fifty constructs were studied. In 28% of the specimens, the calcar screw was misplaced. In 20% of the specimens, it was too low, whereas in 8%, it was too high. The calcar screw missed low in 30% of patients shorter than 5 feet, 5.5 inches versus 8% of taller patients ( P = 0.007). It missed high in 13% of taller patients versus 2% of shorter patients ( P = 0.056). Calcar screws in variable-angle plates missed 0% of the time, whereas those in fixed-angle plates missed 36% of the time ( P = 0.003). CONCLUSIONS: Placement of PHLPs based on distance from the GT results in unacceptable position of the calcar screw 28% of the time and up to 36% in fixed-angle plates. This could be further compounded if the GT is malreduced. Current technique guide recommendations result in an unacceptably high rate of calcar screw malposition.

Dissociable roles of the medial prefrontal cortex and nucleus accumbens core in goal-directed actions for differential reward magnitude.

The medial prefrontal cortex (mPFC) and nucleus accumbens (NAc) are 2 structures within a larger corticolimbic network mediating goal-directed actions, especially when the procurement of different goals is sensitive to impulsive tendencies. The present study investigated the role of these structures in goal-directed action for differential reward by training rats to respond for sucrose reward at a nosepoke operandum such that longer duration nosepokes (up to 2 s) resulted in correspondingly larger volumes of reward. After 16 weeks of training, neurotoxic lesions of either the mPFC or the NAc-core were performed, followed by reassessment of sustained response behavior. Lesions of mPFC increased choice impulsivity by shifting responding away from large rewards toward rewards of smaller sizes. The total volume of reward earned remained unchanged, thereby dissociating the lesion effects on response parameters from overall motivation for reward. In contrast, NAc-core lesions decreased the total amount of responding and total volume of reward earned without altering choice impulsivity across differing nosepoke durations and reward sizes. These results suggest that the mPFC mediates the ability to maintain behavioral responding over longer durations for larger magnitude rewards, while the NAc-core mediates the initiation of responding, perhaps by affecting motivational drive, independent of reward magnitude.

A Biomechanical Study of Tuberosity-Based Locked Plate Fixation Compared with Standard Proximal Humeral Locking Plate Fixation for 3-Part Proximal Humeral Fractures.

BACKGROUND: One of the main shortcomings of current proximal humeral plate designs is their inability to reliably secure the greater tuberosity (GT) or lesser tuberosity, leading to fixation failure, nonunion, and rotator cuff dysfunction. Traditional proximal humeral locking plates (PHLPs) rely on isolated screw fixation or suture repair to maintain reduction of the greater and/or lesser tuberosities. This study evaluates a tuberosity-based plate (TBP) specifically designed to improve tuberosity fixation, which may decrease tuberosity displacement and related clinical sequelae. METHODS: Five cadaveric specimens (10 shoulders) were randomized to receive either standard PHLP or TBP fixation. The specimens were skeletonized except for the rotator cuff insertion on the GT. A reproducible 3-part osteotomy was performed for each cadaver, creating head, shaft, and GT segments. Anatomic reduction and plate fixation were performed according to the surgical technique guide for each plate system, with an equal number of screws placed in each plate both proximally and distally. GT fixation was enhanced with standardized suture augmentation through the rotator cuff in every specimen in both groups. In each trial, fracture displacement, load to failure, number of cycles endured, and mechanism of failure were noted. RESULTS: The mean load to tuberosity fixation failure for the PHLP and TBP groups was 220 and 502 N (P = 0.005), respectively. CONCLUSIONS: The TBP had a significantly higher load to failure and significantly lower mean fracture displacement compared with the PHLP.

Optimization of 89Zr PET Imaging for Improved Multisite Quantification and Lesion Detection Using an Anthropomorphic Phantom.

Our objective was to harmonize multicenter 89Zr PET imaging for oncology trials and to evaluate lesion detection. Methods: Seven PET scanners were evaluated using a custom chest oncology phantom with 9 spheric lesions 7-20 mm in diameter. A 4:1 signal-to-background ratio simulated a patient dose of 92.5 MBq. Various image reconstructions were evaluated. Images were assessed for lesion detection, and recovery coefficients and background signal variance were measured. Results: Two scanners failed to provide acceptable images and data. Optimal reconstruction algorithms enabling adequate lesion detection and reliable quantification across the other 5 scanners were determined without compromising the data quality. On average, 95% of the 10-mm lesions were detected, and the 7-mm lesion was visualized by only 1 scanner. Background variance was 8.6%-16%. Conclusion: We established multicenter harmonization procedures for 89Zr PET imaging in oncology, optimizing small-lesion (≥10 mm) detectability and accurate quantification.

A Comparison of Plate Versus Screw Fixation for Segmental Scaphoid Fractures: A Biomechanical Study.

BACKGROUND: Volar locking plate fixation may offer several advantages over headless screw fixation for scaphoid nonunion, or segmental or comminuted fractures: (1) increased surface area for bony healing; (2) preserved vascularity; and (3) maintenance of a gap for graft insertion. The purpose of this study is to compare headless screw and locking plate fixation of segmental scaphoid fractures and to determine whether either fixation provides a greater mechanical advantage in osteoporotic versus nonosteoporotic bone. METHODS: Sixteen matched-pair cadaver scaphoids were dissected from a range of osteoporotic and nonosteoporotic specimens. Scaphoids from each matched pair were randomly assigned to either volar locking plate or compression screw fixation. A 3-mm segment of bone was circumferentially excised from each scaphoid waist to simulate a segmental defect. Implants were applied, and each specimen was then loaded in axial compression. Load to failure was defined as the load required to achieve gap closure. Mechanism of failure, load to failure, and percent gap recovery were recorded for each trial. RESULTS: Gap closure occurred in all trials. Difference in load to failure was not statistically significant between plate and screw fixation in either nonosteoporotic or osteoporotic cadaver specimens. However, percent gap recovery was significantly higher for plate fixation than for screw fixation. CONCLUSIONS: In scaphoid fractures with segmental defect, plate and screw fixation demonstrate similar loads to failure, but plate fixation performs superiorly to screw fixation for gap recovery after an applied load to failure.

Determination of Tobramycin and Vancomycin Exposure Required to Eradicate Biofilms on Muscle and Bone Tissue In Vitro.

Background: Bacterial biofilms cause chronic orthopaedic infections. Surgical debridement to remove biofilm can be ineffective without adjuvant local antimicrobials because undetected biofilm fragments may remain in the wound and reestablish the infection if untreated. However, the concentrations and duration of antimicrobial exposure necessary to eradicate bacteria from clinical biofilms remain largely undefined. In this study, we determined the minimum biofilm eradication concentration (MBEC) of tobramycin and vancomycin for bacterial biofilms grown on bone and muscle in vitro. Methods: Biofilms of pathogens found in musculoskeletal infections (S. aureus, S. epidermidis, E. faecalis, P. aeruginosa, and E. coli) were established for 72 hr on rabbit muscle and bone specimens in vitro and characterized by SEM imaging and CFU counts. Biofilm-covered tissue specimens were exposed to serial log2 dilutions (4000-31.25 µg/mL) of tobramycin, vancomycin, or a 1:1 combination of both drugs for 6, 24, or 72 hr. Tissues were subcultured following antimicrobial exposure to determine bacterial survival. The breakpoint concentration with no surviving bacteria was defined as the MBEC for each pathogen-antimicrobial-exposure time combination. Results: All tested pathogens formed biofilm on tissue. Tobramycin/vancomycin (1:1) was the most effective antimicrobial regimen with MBEC on muscle (10/10 pathogens) or bone (7/10 pathogens) generally in the range of 100-750 µg/mL with 24 or 72 hr exposure. MBEC decreased with exposure time for 53.3% of biofilms between 6 and 24 hr, 53.3% of biofilms between 24 and 72 hr, and for 76.7% of biofilms between 6 and 72 hr. MBECs on bone were significantly higher than corresponding MBECs on muscle tissue (p < 0.05). In most cases, tissue MBECs were lower compared to previously published MBECs for the same pathogens on polystyrene tissue-culture plates. Conclusions: The majority of MBECs for orthopaedic infections on bone and muscle are on the order of 100-750 µg/mL of vancomycin+tobramycin when sustained for at least 24 hr, which may be clinically achievable using high-dose antimicrobial-loaded bone cement (ALBC).

Consenso latinoamericano sobre la importancia de un sistema de gestión de datos microbiológicos para apoyar el programa de optimización de uso de antimicrobianos (PROA): Recomendaciones basadas en la evidencia. Parte 1

La resistencia antimicrobiana es una amenaza para los logros de la medicina moderna y una de las medidas más efectivas para contrarrestarla son los programas de optimización del uso de antimicrobianos (PROA), en el cual el laboratorio de microbiología es uno de los principales componentes. La aplicación efectiva de tecnología de la información en los procesos es fundamental, pero existe poca información en Latinoamérica sobre el desarrollo y la articulación de las herramientas tecnológicas para apoyar los PROA. Este consenso hace recomendaciones sobre la gestión de los datos microbiológicos para la toma de decisiones. En la Parte I, se presentan las recomendaciones en cuanto al uso de un sistema informatizado de gestión de datos microbiológicos en la práctica clínica, los requerimientos de datos y de reporte en el laboratorio de microbiología, y los contenidos del sistema de gestión de calidad avanzado en el laboratorio. En la Parte II, se discuten los requerimientos de información para la gestión de PROA en estadios intermedios, iniciales y avanzados por el laboratorio y la farmacia; así como la integración del equipo de PROA con el Comité de Prevención y Control de Infecciones y la información para la gestión de PROA a nivel gerencial.

Antimicrobial resistance is a threat to the achievements of modern medicine and one of the most effective measures to counteract it is antimicrobial use optimization programs (AMS), in which the microbiology laboratory is one of the main components. The effective application of information technology in the processes is fundamental, but there is little information in Latin America on the development and articulation of technological tools to support AMSs. This consensus makes recommendations on the management of microbiological data for decision making. In Part I, recommendations on the use of a computerized microbiological data management system in clinical practice, data and reporting requirements in the microbiology laboratory, as well as the contents of the advanced quality management system in the laboratory are presented. In Part II, the information requirements for AMS management in intermediate, initial, and advanced stages by the laboratory and pharmacy are discussed; as well as the integration of the AMS team with the Infection Prevention and Control Committee and the information for AMS management at the management level.

A Biomechanical Comparison of Screw and Plate Fixations for Scaphoid Fractures.

Background Headless screw fixation is the current gold standard of surgical repair for scaphoid fractures. However, maintaining reduction of certain types of scaphoid fractures is challenging with a compression screw. Plate fixation may offer superior fixation in some scaphoid fractures, particularly those with comminution, nonunion, segmental bony defects, and osteopenic or osteoporotic bone. Purpose This study questions whether method of fixation is a determinant in load to failure in segmental scaphoid fractures, and whether any fixation provides a greater mechanical advantage in simulated normal versus osteoporotic bone. Materials and Methods Polyurethane models were fashioned to simulate scaphoids with 3-mm segmental defects. Defects were bridged by one of three constructs: a locking plate, a nonlocking plate, or a headless compression screw. Three models for each fixation construct were tested for both simulated normal and osteoporotic bone density. Load to failure was recorded as the load at which the 3-mm segmental defect was closed. Results Gap closure occurred in all trials. In simulated normal bone, there were no statistically significant differences in load to failure between fixation methods. In simulated osteoporotic bone, the locking plate had a 28% greater load to failure as compared with screw fixation. Conclusion While biomechanical testing shows that plate and screw fixations are equivalent in normal density bone for fixation of a segmental scaphoid defect, locking plates are superior to screw fixation in simulated osteoporotic bone models. Clinical Relevance Plate fixation may provide superior fixation for complex scaphoid fractures, particularly in osteopenic bone.

Does Greater Trochanter Decortication Affect Suture Anchor Pullout Strength in Abductor Tendon Repairs? A Biomechanical Study.

BACKGROUND: Greater trochanter decortication is frequently performed at the time of abductor tendon repair to theoretically increase healing potential. No previous studies have determined the effect that greater trochanter decortication has on the pullout strength of suture anchors. Hypothesis/Purpose: The purpose of this study is to determine whether greater trochanter decortication and bone mineral density affect suture anchor pullout strength in abductor tendon repair. The authors hypothesize that both will have a significant detrimental effect on suture anchor pullout strength. STUDY DESIGN: Controlled laboratory study. METHODS: Nineteen cadaveric proximal femurs with accompanying demographic data and computed tomography scans were skeletonized to expose the greater trochanter. Bone density measurements were acquired by converting Hounsfield units to T-score, based on a standardized volumetric sample in the intertrochanteric region of the femur. The gluteus medius insertion site on the lateral facet of the greater trochanter was evenly divided into 2 regions, anterior-distal and posterior-proximal, and each region was randomly assigned to receive either no decortication or 2 mm of bone decortication. A single biocomposite anchor was implanted in each region and initially tested with cyclic loading for 10 cycles at 0-50 N, 0-100 N, 0-150 N, and 0-200 N, followed by load to failure (LTF) tested at 1 mm/s. For each trial, the number of cycles endured, LTF, mechanism of failure, and stiffness were recorded. RESULTS: Greater trochanters with no decortication and 2 mm of decortication survived a mean ± SD 35.1 ± 6.4 and 28.5 ± 10.6 cycles, respectively ( P < .01). Load to failure for nondecorticated specimens was 206.7 ± 75.0 N versus 152.3 ± 60.2 N for decorticated specimens ( P < .001). In a multivariate analysis, decortication and bone density were determinants in LTF ( P < .05). CONCLUSION: Decortication and decreased bone mineral density significantly decreased the pullout strength of suture anchors in the lateral facet of the greater trochanter. CLINICAL RELEVANCE: Bone density should be considered when determining whether to perform greater trochanter decortication in abductor tendon repairs.