Treatment of distal third humeral shaft fractures with posterior minimally invasive plate osteosynthesis (MIPO) with segmental isolation of the radial nerve: minimum one-year follow-up.

Background: Open reduction and internal fixation with plate is one of the most widely used treatments for distal third humeral shaft fractures. The purpose of this study was to report the outcomes of the treatment of distal third humeral shaft fractures with posterior minimally invasive plate osteosynthesis (MIPO) with segmental isolation of the radial nerve. Methods: We performed an observational, retrospective, consecutive, monocentric, continuous multioperator study. We reviewed 22 distal third humeral shaft fractures treated with posterior MIPO in our institution with an extra-articular distal humerus plate from 2018 to 2021. Inclusion was limited to functionally independent patients with displaced fractures involving the junction of the middle and distal thirds of the humerus and minimum 12-month follow-up for implant removal. We assessed clinical outcomes including range of motion; QuickDASH score; Mayo Elbow Performance Score; and Constant-Murley score. Results: The average follow-up period of the sample was 31.7 ± 11.6 months (range, 15.7-51.3 months). The average elbow flexion and extension were 146.4° ± 7.3° (range, 120°-150°) and -0.7° ± 3.3° (range, -15° to 0°), respectively. The average shoulder anterior flexion, elevation, and abduction were 178.6° ± 3.6° (range, 170°-180°), 179.1° ± 2.9° (range, 170°-180°), and 140.9° ± 14.8° (range, 110°-160°), respectively. The average external rotation was 88.6° ± 6.4 (range, 65°-90°). The mean visual analog scale score for pain was 1.0 ± 1.6 (range, 0-5) and the mean Mayo Elbow Performance Score was 90.5 ± 9.9 (range, 70-100). The mean QuickDASH and Constant-Murley scores were 4.7 ± 6.8 (range, 0-20.5) and 95.5 ± 5.1 (range, 81-100), respectively. Two patients presented with relevant compromise of radial nerve motor function postoperatively (M3 and M2; the more compromised was preoperative injury). All patients recovered radial nerve neuropraxia within six weeks postoperatively. All fractures achieved union. The average anteroposterior and lateral axis were 175.0 ± 3.6 (168.0°-180.0°) and 177.5 ± 2.0 (173.0°-180.0°), respectively. No superficial or deep infection was reported. No cases of re-displacement of fracture, implant failure, or any other implant-related complication in follow-up were reported. No patient required plate withdrawal. Conclusion: The results of this study demonstrate that the posterior MIPO technique is a reliable option for treating distal third shaft humeral fractures. The radial nerve must be identified and protected in all cases to prevent palsy.

Straight antegrade humeral nailing and risk of iatrogenic injury of supraspinatus tendon footprint: An MRI study.

Background: Straight antegrade humeral nailing (SAHN) is associated with excellent clinical results in proximal humerus fractures. The optimal entry point is the top of the humeral head. However, the anatomy is variable, and the entry point can affect supraspinatus tendon footprint (SSP-F) or fracture reduction. The aim of this study was to analyze the relationship between the SSP-F and SAHN entry point by analyzing magnetic resonance imaging (MRI) studies of the humerus. Methods: In total 58 MRI studies of entire humerus were reviewed. The mean age was 51.6 ± 12.4 years, with 40 female patients. The distance between the SSP-F and the SAHN insertion point (critical distance: CD), the width of the footprint, and the neck-shaft angle (NSA) were measured. Univariate and multivariate analysis were performed. Results: The mean CD was 7.51 mm ± 2.81 (0-12.9 mm) with 51.7% of proximal humerus "critical type" (CD <8 mm). The CD was found to be lower in females, with no difference found with varying age (62.5% "critical type"). CD correlated with NSA (linear regression). "Critical type" correlated with female gender and NSA (logistic regression). Discussion: More than half of the humerus are "critical types" as to SAHN and may, therefore, be at risk for procedure-related complications.

The Reverse Shoulder Arthroplasty Angle in MRI: Impact of the Articular Cartilage in the Estimated Inclination of the Inferior Glenoid.

Purpose: To describe the reverse shoulder arthroplasty angle (RSA angle) in magnetic resonance imaging (MRI) and compare the angle formed using bony landmarks (Bony RSA angle or B-RSA angle) with another angle formed using the cartilage margin as reference (Cartilage RSA angle or C-RSA angle). Methods: Adult patients with a shoulder MRI obtained in our hospital between July 2020 and July 2021 were included. The C-RSA angle and B-RSA angle were measured. All images were independently assessed by 4 evaluators. Intraclass correlation coefficient (ICC) was determined for the B-RSA and C-RSA to evaluate interobserver agreement. Results: A total of 61 patients were included with a median age of 59 years (17-77). C-RSA angle was significantly higher than B-RSA (25.4° ± 0.7 vs 19.5° ± 0.7, respectively) with a P-value <.001. The overall agreement was considered "good" for C-RSA (ICC = 0.74 [95% CI 0.61-0.83]) and "excellent" for B-RSA angle (ICC = 0.76 [95% CI 0.65-0.85]). Conclusions: C-RSA angle is significantly higher than B-RSA angle. In cases without significant glenoid wear neglecting to account for the remaining articular cartilage at the inferior glenoid margin may result in superior inclination of standard surgical guides.

Establishing safe zones to avoid nerve injury in the posterior minimally invasive plate osteosynthesis for humerus fractures: a magnetic resonance imaging study.

Background: Safety zones to avoid nerve injury at proximal incision of posterior minimally invasive plate osteosynthesis for humerus fracture have been scarcely studied. The purpose of this study was to describe the location of axillary and radial nerves (RN) in magnetic resonance imaging to establish safety zones. Methods: Fifty-two magnetic resonance imaging studies of the entire humerus were reviewed. The mean age was 50.6 ± 12.1 years, with 37 female patients. The distance of the axillary nerve (AN; distal portion, humeral midpoint) and RN (medial border, midpoint, and lateral border of the humerus) was measured in relation to the posterolateral acromion angle, acromioclavicular axis, and transepicondylar axis. Univariate analysis (Student's t test) and a multivariate analysis (linear regression) were performed. P values < .05 were considered significant. Results: The AN location at the humerus was 54.9 ± 6.4 mm (20.1% humeral length [HL]) in relation to posterolateral acromion angle and 63.2 ± 6.1 mm (23.2% HL) in relation to acromioclavicular axis. The RN location was 100.2 ± 17.1 mm (36.6% HL) at the humerus medial border, 118.0 ± 21.5 mm (43.1% HL) at the humerus midpoint, and 146.0 ± 24.4 mm (53.6% HL) at the humerus lateral border. In relation to transepicondylar axis, it was 175.4 ± 15.6 mm (64.3% HL), 156.0 ± 19.0 mm (57.2% HL), and 127.4 ± 21.2 mm (46.7% HL), respectively. Nerves location was related to HL, independent of gender. Conclusion: The main finding of our study is that the location of the AN and RN in relation to the humerus is related to the HL and can be used to predictably define the safe zones to avoid nerve injury in the proximal incision of posterior minimally invasive plate osteosynthesis for humerus fractures.

Glenoid neck length in a healthy population and its association with scapular notching.

BACKGROUND: Scapular notching is a radiographic finding associated with the use of a reverse shoulder prosthesis. The morphological characteristics of the glenoid neck have been scarcely explored as a relevant factor in relation to scapular notching. The objective of this study is to measure the length of the glenoid neck in a three-dimensional CT reconstruction of a healthy population and to simulate the scapular notching free range of motion for the "long neck" and for the "short neck" groups. METHODS: CT scans of 214 shoulders were reviewed, excluding incomplete, poor quality, or altered studies. 100 CT scans were finally processed. The mean age was 51.7 years (SD 19.4; range, 15-84 years), with 49 female and 51 male patients. For each of the scapulae, four morphometric measurements were obtained: anterior glenoid neck (AGN), middle glenoid neck (MGN), posterior glenoid neck (PGN) and alternative posterior glenoid neck (aPGN). Using 3D software, we simulated a reverse shoulder prosthesis, and the scapular notching free range of motion was registered. Differences between measurements were evaluated with an unpaired t-test using StataIC16®. P-values < 0.05 were considered significant. The intraobserver and interobserver correlation was evaluated with the intraclass correlation coefficient. RESULTS: The AGN measured 7.43 ± 2.52 mm (range, 1.72-13.3 mm); MGN measured 8.05 mm ± 1.93 (range, 2.92-13.2 mm); PGN measured 7.26 ± 2.6 mm (range, 2-13.4 mm); and aPGN measured 8.97 ± 2.3 mm (range, 4.08-15.4 mm). The scapular notching free range of motion for the "long neck" group was 74.98° ± 7.35 (range, 55-83°) and for the "short neck" group, it was 62.93° ± 6.84 (range, 45-70°) (p = 0.0004). CONCLUSIONS: Measurement of posterior glenoid neck length exhibits excellent reliability and reproducibility, as well as being associated to the scapular notching free range of motion. STUDY DESIGN: Basic, retrospective, CT images research.

Increasing incidence of rotator cuff surgery: A nationwide registry study in Chile.

BACKGROUND: The rotator cuff surgery (RCS) incidence is rising rapidly in North America, Europe, Asia, and Australia. Despite this, multiple factors limit patients' access to surgery. In Latin America, barriers to orthopedic surgery have been largely ignored. The purpose of this study was to calculate the rate of RCS in Chile between 2008 and 2018, investigating possible associated factors to access such as age, sex, and the health insurance. METHODS: An ecological study was carried out with nationwide data obtained from the Database of Hospital Discharges of the Department of Statistics. All Chilean inhabitants aged 25 years or more were included. We used the ICD-10 codes M751, M754, and S460. The annual incidence rate of surgeries and the incidence rate for the period studied per 100,000 inhabitants were calculated. Data were analyzed stratified by age, sex, year of study, and the health insurance. Negative binomial regression was used to compare rates. Statistical analyzes were performed with Stata v.14 software. RESULTS: 39,366 RCSs were performed, with a total rate for the period of 32.36 per 100,000 inhabitants. The annual rate of surgeries from 2008 to 2018 increased from 24.55 to 49.11 per 100,000/year. When adjusting for year, an annual increase in surgery rates of 8.19% (95% CI 6.7-9.6) and 101% growth between 2008 and 2018 (95% CI 90-109%, p < 0.001) was observed. When comparing the global rates according to the health insurance, the public system corresponds to 21.3 per 100,000 and the private system to 72 per 100,000, the latter being 3.4-times higher (95% CI 2.7-4.4; p < 0.001). CONCLUSION: RCS rates are increasing in Chile concordantly with previous reports of other western countries. The most important factor associated with RCS rate found was the patients' health insurance, with higher rates observed for the private sector.

Fractura de clavícula distal con cortical superior indemne: cirugía mínimamente invasiva / Distal clavicle fracture with intact upper cortex: minimally invasive surgery

INTRODUCCIÓN Las fracturas de clavícula distal desplazadas son manejadas generalmente de manera quirúrgica dada la alta probabilidad de no-unión con el tratamiento ortopédico. El propósito de este trabajo es evaluar el uso del sistema de fijación con doble botón cortical para la reducción y estabilización de la fractura de clavícula distal que presenten indemnidad de la cortical superior. MÉTODOS: Estudio retrospectivo observacional clínico-imagenológico de pacientes con fractura desplazada de clavícula distal operados con técnica mínimamente invasiva mediante reducción con sistema de fijación con doble botón cortical. Se describe como criterio radiológico de "Cortical Superior Indemne (CSI)" la presencia del rasgo de fractura a 1cm o más, hacia distal desde el tubérculo conoide, identificándose ese criterio como característica necesaria para la indicación del tratamiento propuesto. Se describen las complicaciones post-operatorias, progresión radiológica y resultados funcionales. RESULTADOS: 21 pacientes fueron tratados con esa técnica con un seguimiento promedio de 23,4 meses. No hubo casos de no unión, infección o herida dehiscente y ningún paciente requirió el retiro del dispositivo. Se encontró un Simple Shoulder Test (SST) promedio de 79,4 (66 - 91,7) y QuickDASH de 11 (6,8 - 15,9). El 87,5% de las fracturas desplazadas de clavícula distal tenían indemnidad de la cortical superior. CONCLUSIÓN: La técnica mínimamente invasiva para la reducción y fijación de la fractura de clavícula distal desplazada con botones corticales es una alternativa simple, reproducible, con pocas complicaciones y excelentes resultados funcionales.

BACKGROUND: Displaced distal clavicle fractures are commonly managed through surgery due to a high probability of nonunion with conservative treatments. The purpose of this study is to evaluate the use of Flip-buttons as a minimally invasive method for fixing and stabilizing displaced distal clavicle fractures when the upper cortical it́s intact. METHODS: A retrospective observational study of radiological and clinical results of patients with displaced distal clavicle fracture that were treated with the Flip-button technique. The indication for using this surgical method was based on the radiological criteria of "Intact Upper Cortical (IUC)" described by the authors as the presence of the fracture 1cm or more, distally to de conoid tubercle. Post-operative complications, radiologic and functional progress were recorded. RESULTS: 21 patients were treated with this technique, all with complete bony union. No patients presented infection or wound dehiscence and implant removal was not necessary in any case. The mean follow-up was of 23,4 months. The mean score in Simple Shoulder Test (SST) was 79,4 (66 - 91,7) and a mean QuickDASH of 11 (6,8 - 15,9). 87,5% of all the displaced distal clavicle fractures had IUC. CONCLUSION: The minimally invasive technique for the reduction and fixation of the displaced distal clavicle fracture with cortical buttons is a simple and reproducible alternative, with few complications and excellent functional results.

[The molecular basis of infections associated to orthopedic implants]. / Bases moleculares de la infección asociada a implantes ortopédicos.

Infections associated with the use of orthopedic implants are still the major complication associated with these devices and an unsolved challenge. The frequency of infection associated with orthopedic implant is relatively low, estimated to range between 0.5 to 5%. However, it has devastating consequences for the patient and health institutions. The majority of infections is secondary to gram-positive aerobic microorganisms belonging to the genus Staphylococcus. These bacteria establish chronic infections due to its ability of adhesion and biofilm formation. Biofilms are complex communities in a polysaccharide matrix. This structure retains nutrients and protects the bacteria against the immune response and antimicrobial agents. The study of molecular characteristics and biofilm formation regulation is vital for the understanding of judicious clinical management and the development of novel strategies for the prevention of infection.

Bases moleculares de la infección asociada a implantes ortopédicos / The molecular basis of infections associated to orthopedic implants

Infections associated with the use of orthopedic implants are still the major complication associated with these devices and an unsolved challenge. The frequency of infection associated with orthopedic implant is relatively low, estimated to range between 0.5 to 5%. However, it has devastating consequences for the patient and health institutions. The majority of infections is secondary to gram-positive aerobic microorganisms belonging to the genus Staphylococcus. These bacteria establish chronic infections due to its ability of adhesion and biofilm formation. Biofilms are complex communities in a polysaccharide matrix. This structure retains nutrients and protects the bacteria against the immune response and antimicrobial agents. The study of molecular characteristics and biofilm formation regulation is vital for the understanding of judicious clinical management and the development of novel strategies for the prevention of infection.

La infección asociada a la utilización de implantes ortopédicos es la principal complicación asociada a estos dispositivos y es un desafío aún sin resolver. La frecuencia de infección asociada a implante ortopédico es relativamente baja, estimada en un rango de 0,5 a 5%. Sin embargo, sus consecuencias son devastadoras para el paciente y las instituciones de salud. La mayoría de las infecciones son causadas por microorganismos aerobios grampositivos pertenecientes al género Staphylococcus. Estas bacterias establecen infecciones crónicas gracias a su capacidad de adhesión y formación de biopelículas, complejas comunidades en una matriz de polisacáridos. La biopelícula retiene nutrientes y protege a las bacterias contra la respuesta inmune y agentes antimicrobianos. El estudio de las características moleculares y la regulación de la formación de biopelículas es vital para el entendimiento del manejo clínico juicioso y el desarrollo de estrategias novedosas para la prevención de infección.