A narrative review of endoscopic spine surgery: history, indications, uses, and future directions.

Background and Objective: The concept of endoscopic surgery began in the 1930s and has since undergone numerous advancements in both technology and surgical indications. Its main benefit is providing the opportunity to perform surgery while minimizing disruption to surrounding structures. The purpose of this review is to summarize the history, uses, and future directions for spine endoscopic surgery. Methods: A review of national databases was performing using key terms "endoscopic", "spine" and "surgery" for literature from 1900 to 2023. Studies that aimed to describe the utilities of endoscopic surgeries, associated outcomes, limitations, and future directions were included. Studies that were not in English were excluded. Key Content and Findings: This review includes a brief overview of the history of endoscopic surgery and its current two main approaches, transforaminal and interlaminar approaches. It then summarizes the main indications and utilization of endoscopic surgery in the lumbar, cervical and thoracic spine, as well as expansion in managing spine tumors, infections, and outpatient surgical cases. Conclusions: There are many rising indications and uses for endoscopic spine surgery in nearly every aspect of the spine. Compared to conventional spine surgery, there is early evidence showing endoscopic surgery is associated with less post-operative pain, shorter hospital stays, and possibly quicker recovery times. As current trends in spine surgery move towards minimally invasive techniques, it is anticipated that the use of endoscopic surgery will continue to expand.

Obesity in children with low back pain: implications with imaging phenotypes and opioid use.

BACKGROUND CONTEXT: Low back pain (LBP) is common in children and adolescents, carrying substantial risk for recurrence and continuation into adulthood. Studies have linked obesity to the development of pediatric LBP; however, its association with lumbar spine degeneration, alignment parameters, and opioid use remains debated. PURPOSE: Considering the increasing prevalence of pediatric obesity and LBP and the inherent issues with opioid use, this study aimed to assess the association of obesity with lumbar spine degeneration, spinopelvic alignment, and opioid therapy among pediatric patients. STUDY DESIGN/SETTING: A retrospective study of pediatric patients presenting to a single institute with LBP and no history of spine deformity, tumor, or infection was performed. PATIENT SAMPLE: A totasl of 194 patients (mean age: 16.7±2.3 years, 45.3% male) were included, of which 30 (15.5%) were obese. OUTCOME MEASURES: Prevalence of imaging phenotypes and opioid use among obese to nonobese pediatric LBP patients. Magnetic resonance and plain radiographic imaging were evaluated for degenerative phenotypes (disc bulging, disc herniation, disc degeneration [DD], high-intensity zones [HIZ], disc narrowing, Schmorl's nodes, endplate phenotypes, Modic changes, spondylolisthesis, and osteophytes). Lumbopelvic parameters including lumbar lordosis, pelvic tilt, sacral slope, pelvic incidence and pelvic incidence-lumbar lordosis (PI-LL) mismatch were also examined. METHODS: Demographic and clinical information was recorded, including use of opioids. The associations between obesity and lumbar phenotypes or opiod use were assessed by multiple regression models. RESULTS: Based on multivariate analysis, obesity was significantly associated with the presence of HIZ (adjusted OR: 5.36, 95% CI: 1.30 to 22.09). Further analysis demonstrated obesity (adjusted OR: 3.92, 95% CI: 1.49 to 10.34) and disc herniation (OR: 4.10, 95% CI: 1.50 to 11.26) were associated with opioid use, independent of duration of symptoms, other potential demographic determinants, and spinopelvic alignment. CONCLUSIONS: In pediatric patients, obesity was found to be significantly associated with HIZs of the lumbar spine, while disc herniation and obesity were associated with opioid use. Spinopelvic alignment parameters did not mitigate any outcome. This study underscores that pediatric obesity increases the risk of developing specific degenerative spine changes and pain severity that may necessitate opioid use, emphasizing the importance of maintaining healthy body weight in promoting lumbar spine health in the young.

Elliptical heads result in increased glenohumeral translation along with micro-motion of the glenoid component during axial rotation in total shoulder arthroplasty.

INTRODUCTION: Elliptical-shaped humeral head prostheses have recently been proposed to reflect a more anatomic shoulder replacement. However, its subsequent effect on micro-motion of the glenoid component is still not understood. MATERIALS AND METHODS: Six fresh-frozen, cadaveric shoulders (mean age: 62.7 ± 9.2 years) were used for the study. Each specimen underwent total shoulder arthroplasty using an anatomic stemless implant. At 15°, 30°, 45° and 60° of glenohumeral abduction, 50° of internal and external rotations in the axial plane were alternatingly applied to the humerus with both an elliptical and spherical humeral head design. Glenohumeral translation was assessed by means of a 3-dimensional digitizer. Micro-motion of the glenoid component was evaluated using four high-resolution differential variable reluctance transducer strain gauges, placed at the anterior, posterior, superior, and inferior aspect of the glenoid component. RESULTS: The elliptical head design showed significantly more micro-motion in total and at the superior aspect of glenoid component during external rotation at 15° (total: P = 0.004; superior: P = 0.004) and 30° (total: P = 0.045; superior: P = 0.033) of abduction when compared to the spherical design. However, during internal rotation, elliptical and spherical heads showed similar amounts of micro-motion at the glenoid component at all tested abduction angles. When looking at glenohumeral translation, elliptical and spherical heads showed similar anteroposterior and superoinferior translation as well as compound motion during external rotation at all tested abduction angles. During internal rotation, the elliptical design resulted in significantly more anteroposterior translation and compound motion at all abduction angles when compared to the spherical design (P < 0.05). CONCLUSION: In the setting of total shoulder arthroplasty, the elliptical head design demonstrated greater glenohumeral translation and micro-motion at the glenoid component during axial rotation when compared to the spherical design, potentially increasing the risk for glenoid loosening in the long term. LEVEL OF EVIDENCE: Controlled Laboratory Study.

Does a relationship exist between preoperative expectations and overall satisfaction in spine surgery patients?-a prospective cohort study.

Background: The role of preoperative patient expectation in spine surgery is not completely understood, but could be essential in predicting patient outcomes. The purpose of this study was to create a standard means to assess patient preoperative expectations and its effect on postoperative satisfaction in the midterm follow-up period. Methods: This is a prospective cohort study design. Forty-five patients undergoing elective cervical or lumbar spine surgery were asked to participate in the study. Using a 10 cm visual analog scale (VAS) score, patients were asked to rate their preoperative pain along with what they expect it to be after surgery. Pre- and postoperative Oswestry Disability Index (ODI) and Neck Disability Index (NDI) were recorded. Overall satisfaction with surgery was recorded along with if they would have surgery again. The patients' preoperative expectations were compared to their postoperative ODI/NDI scores at terminal follow-up around 1 year. Postoperative satisfaction was also correlated as to whether they would have surgery again. Results: Patients who would have surgery again had an average expected decrease in their disability by 37 (±23) compared to 26 (±19) in patients who would not (P=0.201). For patients who would have surgery again, their postoperative pain more closely matched their preoperative expectations. Conclusions: In conclusion, the authors found that patients who were satisfied with their spine surgery improved functionally to a much greater degree from baseline, tended to have higher expectations with regards to level of disability improvement, and had lower expectations with regards to improvement in neck/back pain.

Narrative review: erector spinae block in spine surgery.

Background: Lumbar spine surgery is an ever-increasing procedure with multiple analgesia techniques utilized for postoperative pain control. More recently, erector spinae plane (ESP) blocks have been used to limit the use of opioids after surgery. The authors aimed to review the current literature on ESP blocks and its potential use in the outpatient setting. Methods: Several randomized controlled trials were evaluated that compared erector spinae block to traditional anesthesia where the primary outcome of postoperative opioid use was assessed. Randomized control trials comparative studies were also evaluated to assess erector spinae block effect on outpatient procedures. Secondary outcomes include, postoperative pain, patient satisfaction, patient length of stay, and post-operative complications. Key Content and Findings: Erector spinae block was found in general to lower postoperative opioid use compared to traditional anesthesia. In addition, the authors found improved patient satisfaction and less postoperative pain in the erector spinae cohort. Post-operative complications were lower in the erector spinae block group compared to traditional anesthesia, especially in regards to vomiting and nausea. Conclusions: While these studies do possess their limitations due to the low number of randomized control studies on erector spinae block, early data does suggest that erector spinae block appears to be superior to that of traditional anesthesia for those undergoing spine surgery.

Modifiable Patient Factors Demonstrate No Increased Risk for 30-Day Complication Rate for Elective 1-2 Level Posterior Lumbar Fusion Surgery: A Comparison Between a National Database and Local Registry.

BACKGROUND: While national databases provide large datasets that can be used to understand trends over time, their correlation with prospectively collected data from local registries has not been established. The purpose of the study was to compare differences in patient demographics and adverse events for patients undergoing elective posterior spinal fusion (PSF) between a national database and institutional registry. METHODS: A retrospective chart review was performed. A total of 14,618 patients (13,678 patients from the National Surgical Quality Improvement Program [NSQIP] database and 940 patients from the institutional registry) who underwent elective 1- to 2-level PSF were included in the study. Preoperative patient demographics and comorbidities of each cohort were compared. In addition, postoperative 30-day complications and readmission were collected. A multivariate analysis was performed to examine for differences in risk factors for 30-day adverse events between the 2 cohorts. RESULTS: A total of 13,678 patients from the NSQIP database and 940 patients from the institutional cohort were included for analysis. Mean age was similar between patient cohorts (60.8 ± 13.1NSQIP vs 58.8 ± 12.9registry), with NSQIP having significantly more patients over the age of 65 (41.4% vs 33.2%, P < 0.001). Overall complication rate was similar between NSQIP (6.8%) and the institutional registry (8.4%). Both found age and female sex to be significant predictors of 30-day adverse events, while obesity, hypertension, and smoking were only found to be predictive in the NSQIP database. CONCLUSIONS: Age and female sex were found to be independent risk factors for 30-day adverse events between both cohorts, while only NSQIP found modifiable comorbidities to be significant predictors. Although large databases allow for trends in quality over time, subtleties in practice variation and data collection methods at the individual institution level need to be considered when generalizing findings, especially as it pertains to modifiable factors. CLINICAL RELEVANCE: Quality metrics and risk factors for patient outcomes are often derived from national databases. This study highlights the differences between study results when outcomes are derived from an institutional registry compared to a national database.

Biomechanical comparison of lower trapezius and latissimus dorsi transfer for irreparable posterosuperior rotator cuff tears using a dynamic shoulder model.

BACKGROUND: In the setting of irreparable posterosuperior rotator cuff tears (PSRCTs), lower trapezius transfer (LTT) may be anatomically better positioned for restoring the muscular force couple compared with latissimus dorsi transfer (LDT). The purpose of the study was to evaluate the effect of LTT and LDT on glenohumeral kinematics using a dynamic shoulder model. METHODS: Ten fresh-frozen cadaveric shoulders (mean age: 56.5 ± 17.2 years) were tested using a dynamic shoulder simulator. The maximum abduction angle (MAA), superior humeral head migration (SHM), and cumulative deltoid forces (CDFs) were compared across 4 conditions: (1) native; (2) irreparable PSRCT; (3) LTT using an Achilles tendon allograft; and (4) LDT. MAA and SHM were measured using 3-dimensional motion tracking. CDF was recorded in real time throughout the dynamic abduction motion by load cells connected to actuators. RESULTS: Compared to the native state, the PSRCT resulted in a significant decrease (Δ-24.1°; P < .001) in MAA, with a subsequent significant increase after LTT (Δ13.1°; P < .001) and LDT (Δ8.9°; P < .001). LTT achieved a significantly greater MAA than LDT (Δ4.2°; P = .004). Regarding SHM, both LTT (Δ-9.4 mm; P < .001) and LDT (Δ-5.0 mm; P = .008) demonstrated a significant decrease compared with the PSRCT state. LTT also achieved significantly less SHM compared with the LDT (Δ-4.4 mm; P = .011). Further, only the LTT resulted in a significant decrease in CDF compared with the PSRCT state (Δ-21.3 N; P = .048), whereas LTT and LDT showed similar CDF (Δ-11.3 N; P = .346). However, no technique was able to restore the MAA, SHM, and CDF of the native shoulder (P < .001, respectively). CONCLUSION: LTT and LDT both achieved a significant increase in MAA along with significantly less SHM compared with the PSRCT state. Although LTT required significantly less compensatory deltoid forces compared with the PSRCT state, this was not observed for the LDT. Further, the LTT prevented loss of abduction motion and SHM more sufficiently. In the challenging treatment of irreparable PSRCTs, LTT may restore native glenohumeral kinematics more sufficiently, potentially leading to improved postoperative functional outcomes.

Delayed Postoperative Spinal Cord Injury with Complete Paralysis After Adolescent Idiopathic Surgery: A Case Report.

CASE: We report a 14-year-old girl with adolescent idiopathic scoliosis who experienced bilateral lower extremity paralysis related to postoperative hypotension 10 hours after posterior spinal fusion. She returned to the operating room for spinal cord decompression and hardware removal. Six weeks later, reinstrumentation was performed, and complete neurologic recovery was achieved. CONCLUSION: Delayed presentation of neurologic injury after scoliosis surgery is particularly uncommon. Close postoperative monitoring, with an emphasis on hypotensive etiologies and a low threshold to remove the instrumentation, is essential to rapidly diagnose and treat these catastrophic events.

A reduced concentration femoral nerve block is effective for perioperative pain control following ACL reconstruction: a retrospective review.

INTRODUCTION: Femoral nerve block (FNB) is a routinely used regional analgesic technique for anterior cruciate ligament (ACL) reconstruction. One method to balance the analgesic effect and functional impairment of FNBs may be to control the concentration of local anesthetics utilized for the block. MATERIALS AND METHODS: Retrospective chart review was performed on 390 consecutive patients who underwent ACL reconstruction between June 2014 and May 2017. Patients were divided into those who received a standard (0.5%-bupivacaine) or low (0.1-0.125%-bupivacaine) concentration single-shot FNB performed with ultrasound guidance. Maximum postoperative VAS, Post-Anaesthesia Care Unit (PACU) time prior to discharge, need for additional 'rescue' block, and intravenous postoperative narcotic requirements were recorded. RESULTS: A total of 268 patients (28.4 ± 11.9 years) were included for final analysis, with 72 patients in the low-concentration FNB group and 196 patients receiving the standard concentration. There were no differences in the maximum postoperative VAS between the low (6.4 ± 2.5) and standard (5.7 ± 2.9) concentration groups (P = 0.08). Similarly, the time from PACU arrival to discharge was not different between groups (P = 0.64). A sciatic rescue block was needed in 22% of patients with standard-dose FNB compared to 30% of patients receiving the low-concentration FNB (P = 0.20). Patients with a hamstring autograft harvest were more likely to undergo a postoperative sciatic rescue block compared to a bone-patellar tendon autograft (P = 0.005), regardless of preoperative block concentration. Quadriceps activation was preserved with low-concentration blocks. CONCLUSIONS: Using 1/5th to 1/4th the standard local anesthetic concentration for preoperative femoral nerve block in ACL reconstruction did not significantly differ in peri-operative outcomes, PACU time, need for rescue blockade, or additional immediate opioid requirements. LEVEL OF EVIDENCE: III.

Rotational range of motion of elliptical and spherical heads in shoulder arthroplasty: a dynamic biomechanical evaluation.

INTRODUCTION: Elliptical shape humeral head prostheses have been proposed to reflect a more anatomic shoulder replacement. Its effect on the rotational range of motion (ROM) compared to a standard spherical head is still not understood. The purpose was to investigate if there would be a difference in rotational ROM when comparing elliptical and spherical prosthetic heads in a dynamic shoulder model. The authors hypothesized that the use of elliptical heads would result in significantly more rotational ROM compared to the spherical head design. MATERIALS AND METHODS: Six fresh-frozen, cadaveric shoulders were evaluated using a dynamic shoulder model. After being tested in the native condition, each specimen underwent 6 conditions in the hemiarthroplasty state: (1) matched-fit spherical head, (2) oversized spherical head, (3) undersized spherical head, (4) matched-fit elliptical head, (5) oversized elliptical head, and (6) undersized elliptical head. Following conversion to total shoulder arthroplasty (TSA), the 6 prior conditions were rerun. Each condition was tested at 0°, 30° and 60° of glenohumeral abduction. Rotational ROM was quantified using 3-dimensional tracking, while dynamically applying alternating forces for internal and external rotation via the rotator cuff tendons. RESULTS: Elliptical and spherical prosthetic heads showed no significant difference in the degree of the total, internal, and external rotational ROM for both the hemiarthroplasty and TSA state. Conversion from hemiarthroplasty to TSA resulted in less degree of total rotational ROM for both head designs in all abduction positions, without reaching statistical significance. There was a significant decrease in total, internal, and external rotational ROM for both elliptical and spherical heads in every replacement condition, when comparing 0° to 30° and 60° of abduction (P < 0.05, respectively). CONCLUSION: In a dynamic shoulder model, elliptical and spherical prosthetic head designs showed no significant difference in the degree of the total, internal, and external rotational ROM in both the hemiarthroplasty and TSA state. LEVEL OF EVIDENCE: Controlled laboratory study.

Biconcave glenoids show 3 differently oriented posterior erosion patterns.

BACKGROUND: Posterior glenoid wear remains a challenge in anatomic and reverse total shoulder arthroplasty (rTSA) because of an asymmetric erosion with altered retroversion. The purpose of this study was to assess glenoid morphology and evaluate the influence of acromial orientation in posterior glenoid erosion patterns by using 3-dimensional (3D) models. MATERIAL AND METHODS: Computed tomographic (CT) shoulder scans from 3 study centers of patients awaiting rTSA between 2017 and 2018 were converted into 3D models and analyzed by 2 observers. Morphology, orientation and greatest depth of erosion, inclination, current retroversion and premorbid retroversion, surface areas of the glenoid, and external acromial orientation and posterior acromial slope were assessed. Measurements were compared between wear patterns, glenoid erosion entities, and genders. RESULTS: In the complete cohort of 68 patients (63.8 ± 10.0 years; 19 female, 49 male), a mean of 85.9° (±22.2°) was observed for the glenoid erosion orientation. Additionally, a further distinct classification of the glenoid erosion as posterior-central (PC, n = 39), posterior-inferior (PI, n = 12), and posterior-superior (PS, n = 17) wear patterns was possible. These wear patterns significantly (P < .001) distinguished by erosion orientation (PC = 86.9° ± 12.0°, PI = 116.3° ± 10.3°, PS = 62.3° ± 18.9°). The greatest depth of erosion found was 7.3 ± 2.7 mm in PC wear patterns (PC vs. PI: P = .03; PC vs. PS: n.s.; PI vs. PS: n.s.). Overall, the observed erosion divided the glenoid surface into a paleoglenoid proportion of 48% (±11%) and a neoglenoid proportion of 52% (±12%). For the complete cohort, glenoid inclination was 85.4° (±6.6°), premorbid glenoid retroversion was 80.7° (±8.1°), and current glenoid retroversion was 73.4° (±7.4°), with an estimated increase of 6.9° (±6.0°). The mean external acromial orientation was 118.2° (±8.9°), and the mean posterior acromial slope was 107.2° (±9.6°). There were no further significant differences if parameters were compared by wear patterns, entities, and gender. CONCLUSION: Three significantly differently oriented wear patterns (posterior-superior, posterior-central, and posterior-inferior) were distinguished in shoulders demonstrating posterior wear on axillary imaging. No significant differences between the observed erosion patterns or any relevant correlations were found regarding the orientation of the acromion.

Effectiveness of topical adjuvants in reducing biofilm formation on orthopedic implants: an in vitro analysis.

BACKGROUND AND HYPOTHESIS: The treatment of periprosthetic joint infection is complicated by the presence of residual biofilm, which resists eradication owing to bacterial adherence to orthopedic implants. The purpose of this study was to compare Bactisure (Zimmer Biomet, Warsaw, IN, USA), povidone-iodine (Betadine), and chlorhexidine gluconate solution (Irrisept; Irrimax, Gainesville, FL, USA) in reducing biofilm formation of Staphylococcus aureus, Staphylococcus epidermidis, and Cutibacterium acnes inoculated on cobalt-chrome, titanium, and stainless steel disks, representing metals commonly used for shoulder arthroplasty. The hypothesis was that there would be no significant difference in biofilm reduction among the 3 topical adjuvants. METHODS: Strains of S aureus (ATCC 35556), S epidermidis (ATCC 35984), and C acnes (LMG 16711) were grown on cobalt-chrome, titanium, and stainless steel disks. For each strain, the disks were divided into 4 groups: (1) control, (2) povidone-iodine (Betadine), (3) chlorhexidine gluconate (Irrisept), and (4) Bactisure. Bacteria were grown on 5% sheep blood agar plates. Biofilm eradication was quantified using adenosine triphosphate bioluminescence and compared with controls 48 and 72 hours after implementation of the topical adjuvant. RESULTS: At 72 hours after implementation of the topical adjuvant, a statistically significant reduction in colony-forming units was observed for all topical adjuvants across all tested metals, as compared with their respective control. With respect to the topical adjuvants themselves, Bactisure more consistently demonstrated the most significant reduction in colony-forming units across all bacteria when the tested medium was adjusted for, with the exception of S aureus, which showed similar results to Betadine at 72 hours. CONCLUSION: By use of commonly encountered topical adjuvants on S aureus-, S epidermidis-, and C acnes-inoculated disks of various implant metals, a significant reduction in biofilm production was observed. Bactisure, a recent Food and Drug Administration-approved topical adjuvant, demonstrated the overall greatest efficacy of the agents studied.

Nucleated Cell Count Has Negligible Predictive Value for the Number of Colony-Forming Units for Connective Tissue Progenitor Cells (Stem Cells) in Bone Marrow Aspirate Harvested From the Proximal Humerus During Arthroscopic Rotator Cuff Repair.

PURPOSE: To evaluate whether nucleated cell count (NCC) could serve as an approximation for the number of colony-forming units (CFUs) in concentrated bone marrow aspirate (cBMA) obtained from the proximal humerus. METHODS: Bone marrow aspirate (BMA) was harvested from the proximal humerus in 96 patients (mean age 56.2 ± 7.0 years) during arthroscopic rotator cuff repair. Following concentration of the aspirate, nucleated cells of each sample were counted. The total number of CFUs was evaluated under the microscope at their first appearance, usually after 5 to 10 days in culture. Fluorescence-activated cell sorting analysis and assays for osteogenic, adipogenic, and chondrogenic differentiation were performed. Linear regression was assessed to predict the number of CFUs by using NCC. Age, sex, and body mass index (BMI) were evaluated as independent variables. RESULTS: The average volume of the obtained BMA was 86.7 ± 35.2 mL. The cBMA contained a mean of 26.3 ± 6.8 × 106 nucleated cells per mL, which yielded a mean of 1421.7 ± 802.7 CFUs in cell culture. There were no significant differences in NCC or number of CFUs when sex, volume of BMA, age, or BMI was examined independently (P >.05, respectively). Linear regression found that NCC was of limited predictive value for the total number of CFUs being yielded after cell culture (r2 = 0.28 with a root mean square error of 679.4). CONCLUSION: NCC was of negligible predictive value for the total number of CFUs for connective tissue progenitor cells in BMA harvested from the proximal humerus during arthroscopic rotator cuff repair. CLINICAL RELEVANCE: NCC is often used to assess the quality of cBMA samples for biological augmentation during surgery. The limited predictive value of this measurement tool is of clinical importance, because effectiveness of BMA applications has been suggested to depend on the concentration of progenitor cells within the sample.

Conversion to anatomic coracoclavicular ligament reconstruction (ACCR) shows similar clinical outcomes compared to successful non-operative treatment in chronic primary type III to V acromioclavicular joint injuries.

PURPOSE: To compare the clinical outcomes of patients who underwent successful nonoperative treatment for type III-V acromioclavicular joint (ACJ) injuries to those who eventually required conversion to anatomic coracoclavicular ligament reconstruction (ACCR) at a minimum 5-year follow-up. METHODS: Patients with primary, chronic type III-V ACJ injuries who either underwent successful conservative treatment or conversion to ACCR after failing a trail of conservative management between 2003 and 2014 with a minimum 5-year follow-up were included in the study. Clinical outcome measures comprised the American Shoulder and Elbow Surgeons (ASES) and Simple Shoulder Test (SST) score, collected preoperatively and at final visit for the ACCR group. Outcome scores for patients with successful conservative treatment were only collected at final visit. A Self- Assessment Numeric Evaluation (SANE) score was obtained at terminal follow-up for both groups. RESULTS: Twenty-two patients (mean age: 40.1 ± 15.6 years) with successful nonoperative treatment and twenty-one patients (mean age: 43.6 ± 12.0 years) who required conversion to ACCR were included in the study. At final follow-up, patients with successful non-operative treatment achieved similar ASES (93.0±12.0NonOP vs. 86.1±16.8ACCR), SST (11.2±1.4NonOP vs. 10.7±2.0ACCR) and SANE scores (80.9±19.7NonOPvs. 90.5±14.7ACCR) compared to those who were converted to ACCR. Additionally, patients who underwent conversion to ACCR showed significant improvement in ASES (49.8±18.1pre vs. 86.1±16.8post; Δ36.3±19.7) and SST scores (6.5±3.2prevs. 10.7±2.0post; Δ4.2±4.0) from pre- to postoperative. CONCLUSION: At a minimum 5-year follow-up, patients with successful non-operative treatment for type III-V ACJ injuries achieved similar clinical outcomes compared to those who were converted to ACCR. In patients with chronic severe ACJ dislocation a trial of conservative treatment may be attempted, astime from injuryto eventual conversion to ACCR had no significant influence on postoperative clinical outcomes. LEVEL OF EVIDENCE: Level IV.

Anatomic coracoclavicular ligament reconstruction (ACCR) using free tendon allograft is effective for chronic acromioclavicular joint injuries at mid-term follow-up.

PURPOSE: To evaluate the clinical and radiographic outcomes of patients undergoing anatomic coracoclavicular ligament reconstruction (ACCR) using free tendon allografts for the treatment of chronic acromioclavicular joint (ACJ) injuries with a minimum 1-year follow-up. METHODS: Patients who underwent ACCR for chronic ACJ injuries between 2003 and 2017 were analyzed. Clinical outcome measures included American Shoulder and Elbow Surgeons (ASES), Constant-Murley (CM), Simple Shoulder Test (SST), and Single Assessment Numerical Evaluation (SANE) scores. Radiographic loss of reduction during follow-up was evaluated by calculating the difference (mm) in the coracoclavicular distance (CCD) of the involved side immediately postoperatively and at terminal follow-up. RESULTS: Forty-two patients (mean age: 42.7 ± 12.8 years) were included in the study with an average follow-up of 3.8 ± 3.1 years (range: 1.1-11.5 years). Patients achieved significant improvement in ASES (50.2 ± 20.1 pre to 85.2 ± 16.3 post), CM (60.2 ± 18.5 pre to 88.2 ± 9.1 post), SST (6.1 ± 3.2 pre to 9.5 ± 3.7 post), and SANE (24.0 ± 25.7 pre to 89.0 ± 12.7 post) scores (P < 0.001, respectively). There were no significant differences in functional improvement when comparing type III and V injuries (n.s.). Mean increase in CCD of the involved side from immediately postoperative to final radiographic follow-up was 4.1 ± 3.9 mm, with no significant correlation to clinical outcomes scores. Complications occurred in 33.3% of cases, with postoperative heterotopic ossification being most frequent (14.3%). CONCLUSION: Patients undergoing ACCR using free tendon allografts for chronic ACJ injuries achieved significant improvement in shoulder function at a mean follow-up of 3.8 years. No correlation was observed between the amount of loss of reduction and clinical outcome scores. Free tendon allografts may be a reliable alternative to autografts in the treatment of chronic ACJ dislocations. LEVEL OF EVIDENCE: IV.

Chronic Atlantoaxial Rotatory Subluxation in an Adult Following a Traumatic Event: A Case Report.

BACKGROUND: Traumatic rotatory subluxation of the atlantoaxial joint is a rare but potentially life-threatening injury in adults. While acute cases have been shown to be managed successfully with closed reduction, chronic injuries in skeletally mature patients have rarely been reported. METHODS: We present management of a 64-year-old female who presents 2.5 years after a traumatic cervical injury with neck pain and torticollis. Imaging revealed rotatory subluxation of C1-C2 without cord impingement. A focused appraisal of the reported literature was also performed. RESULTS: Successful reduction was achieved with halo cervical traction, followed by definitive treatment with atlantoaxial arthrodesis. CONCLUSIONS: Cases of fixed, chronic C1-C2 rotatory subluxation after traumatic etiology may be amenable to closed reduction with skeletal traction and fusion. LEVEL OF EVIDENCE: 4. CLINICAL RELEVANCE: Chronic, post-traumatic atlantoaxial rotatory subluxation in the adult population is extremely rare, without a well-described treatment algorithm. The purpose of this case report is to highlight the reduction and fixation of someone with this injury.

Posterior Rotational and Translational Stability in Acromioclavicular Ligament Complex Reconstruction: A Comparative Biomechanical Analysis in Cadaveric Specimens.

BACKGROUND: Persistent posterior instability of the acromioclavicular (AC) joint is a reported complication after isolated coracoclavicular (CC) reconstruction. Thus, multiple techniques have been proposed attempting to restore biomechanics of the AC ligament complex (ACLC). PURPOSE/HYPOTHESIS: The purpose was to evaluate the posterior translational and rotational stability of an ACLC reconstruction with a dermal allograft (ACLC patch) as compared with 3 suture brace constructs. It was hypothesized that the ACLC patch would better restore AC joint posterior stability. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 28 cadaveric shoulders (mean ± SD age, 57.6 ± 8.3 years) were randomly assigned to 1 of 4 surgical techniques: ACLC patch, oblique brace, anterior brace, and x-frame brace. The force and torque to achieve 10 mm of posterior translation and 20° of posterior rotation of the AC joint were recorded in the following conditions: intact, transected ACLC, ACLC patch/brace repair, ACLC patch/brace repair with dissected CC ligaments, and ACLC patch/brace repair with CC ligament repair. RESULTS: For posterior translation, transection of the ACLC reduced resistance to 16.7% of the native. With the native CC ligaments intact, the ACLC patch (59.1%), oblique brace (54.1%), and anterior brace (60.7%) provided significantly greater stability than the x-frame brace (33.2%; P < .001, P = .008, P < .001, respectively). ACLC patch, oblique brace, and anterior brace continued to have significantly higher posterior translational resistance than the x-frame (35.1%; P < .001, P = .003, P < .001) after transection and subsequent CC ligament repair. For posterior rotation, transection of the ACLC decreased the resistance to 5.4% of the intact state. With the CC ligaments intact, the ACLC patch (77.1%) better restored posterior rotational stability than the oblique (35.3%), anterior (48.5%), and x-frame (23.0%) brace repairs (P < .001, P = .002, P < .001). CC ligament transection and subsequent repair demonstrated the ACLC patch (41.0%) to have improved stability when compared with the oblique (16.0%), anterior (14.0%), and x-frame (12.7%) repairs (P = .006, P = .003, P = .002). CONCLUSION: ACLC reconstruction with a dermal allograft better restored native posterior rotational stability than other brace constructs, with translational stability similar to the oblique and anterior brace technique at the time of surgery. CLINICAL RELEVANCE: Horizontal stability of the AC joint is primarily controlled by the ACLC. Inability to restore AC joint biomechanics can result in persistent posterior instability and lead to functional impairment.