The relationship between design-based lateralization, humeral bearing design, polyethylene angle, and patient-related factors on surgical complications after reverse shoulder arthroplasty: a machine learning analysis.

BACKGROUND: Technological advancements in implant design and surgical technique have focused on diminishing complications and optimizing performance of reverse shoulder arthroplasty (rTSA). Despite this, there remains a paucity of literature correlating prosthetic features and clinical outcomes. This investigation utilized a machine learning approach to evaluate the effect of select implant design features and patient-related factors on surgical complications after rTSA. METHODS: Over a 16-year period (2004-2020), all primary rTSA performed at a single institution for elective and traumatic indications with a minimum follow-up of 2 years were identified. Parameters related to implant design evaluated in this study included inlay vs. onlay humeral bearing design, glenoid lateralization (medialized or lateralized), humeral lateralization (medialized, minimally lateralized, or lateralized), global lateralization (medialized, minimally lateralized, lateralized, highly lateralized, or very highly lateralized), stem to metallic bearing neck shaft angle, and polyethylene neck shaft angle. Machine learning models predicting surgical complications were constructed for each patient and Shapley additive explanation values were calculated to quantify feature importance. RESULTS: A total of 3837 rTSA were identified, of which 472 (12.3%) experienced a surgical complication. Those experiencing a surgical complication were more likely to be current smokers (Odds ratio [OR] = 1.71; P = .003), have prior surgery (OR = 1.60; P < .001), have an underlying diagnosis of sequalae of instability (OR = 4.59; P < .001) or nonunion (OR = 3.09; P < .001), and required longer OR times (98 vs. 86 minutes; P < .001). Notable implant design features at an increased odds for complications included an inlay humeral component (OR = 1.67; P < .001), medialized glenoid (OR = 1.43; P = .001), medialized humerus (OR = 1.48; P = .004), a minimally lateralized global construct (OR = 1.51; P < .001), and glenohumeral constructs consisting of a medialized glenoid and minimally lateralized humerus (OR = 1.59; P < .001), and a lateralized glenoid and medialized humerus (OR = 2.68; P < .001). Based on patient- and implant-specific features, the machine learning model predicted complications after rTSA with an area under the receiver operating characteristic curve of 0.61. CONCLUSIONS: This study demonstrated that patient-specific risk factors had a more substantial effect than implant design configurations on the predictive ability of a machine learning model on surgical complications after rTSA. However, certain implant features appeared to be associated with a higher odd of surgical complications.

Knee Arthroscopy Following Total Knee Arthroplasty is Not Associated With an Elevated Risk of Infection.

BACKGROUND: Recent literature has suggested that knee arthroscopy (KA) following ipsilateral primary total knee arthroplasty (TKA) may be associated with an increased risk of periprosthetic joint infection (PJI). However, prior studies on this subject have relied on insurance databases or have lacked control groups for comparison. This study aimed to evaluate the risk of PJI in patients undergoing ipsilateral KA after primary TKA at a single institution. METHODS: Our total joint registry was queried to identify 167 patients (178 knees) who underwent ipsilateral KA for any indication other than infection following primary TKA (KA + TKA group). The average time from TKA to KA was 2.1 ± 2.3 years. The average follow-up from primary TKA and from KA was 8.4 ± 5.4 years and 6.3 ± 5.4 years, respectively. The mean patient age was 63 ± 11 years, the mean body mass index was 31 ± 5, and 64% were women. The most common indications for KA were patellar clunk or patellofemoral synovial hyperplasia (66%) and arthrofibrosis (16%). Patients in the KA + TKA group were matched to 523 patients who underwent TKA without subsequent KA (TKA group) based on age, sex, date of surgery, and body mass index. The primary outcome measure was survivorship free from PJI. RESULTS: There was no statistical difference in the overall rate of PJI between the KA + TKA group (n = 2, 1.1%) compared to the TKA group (n = 3, 0.6%) (hazard ratio 2.0, 95% confidence interval 0.3 to 12.0, P = .4). At 5 and 10 years after TKA, there was no difference in survivorship free of PJI between the 2 groups (P = .8 and P = .3, respectively). CONCLUSIONS: A PJI is a rare complication of KA after TKA. The rate of PJI in patients undergoing KA following TKA is not significantly increased. LEVEL OF EVIDENCE: III.

Sacral insufficiency fractures are a frequent and painful consequence of pubic symphysis osteomyelitis.

BACKGROUND: Pubic symphysis osteomyelitis can result from urosymphyseal fistula formation. High rates of sacropelvic insufficiency fractures have been reported in this population. The aim of this study was to describe the presentation and risk factors for sacral insufficiency fractures (SIF) associated with surgical treatment of pubic symphysis osteomyelitis. METHODS: A retrospective review was performed for 54 patients who underwent surgery for pubic symphysis osteomyelitis associated with a urosymphyseal fistula at a single institution from 2009 to 2022. Average age was 71 years and 53 patients (98%) were male. All patients underwent debridement or partial resection of the pubic symphysis at the time of fistula treatment. Average width of the symphyseal defect was 65 mm (range 9-122) after treatment. RESULTS: Twenty patients (37%) developed SIF at a mean time of 4 months from osteomyelitis diagnosis. Rate of sacral fracture on Kaplan-Meier analysis was 31% at 6 months, 39% at 12 months, and 41% at 2 years. Eleven patients developed SIF prior to pubic debridement and 12 patients developed new or worsening of pre-existing SIF following surgery. Width of pubic resection was higher in patients who developed SIF (76 mm vs. 62 mm), but this did not meet statistical significance (p = 0.18). CONCLUSION: Sacral insufficiency fracture is a common sequela of pubic symphysis osteomyelitis. These fractures are often multifocal within the pelvis and can occur even prior to pubic resection. Pubectomy further predisposes these patients to fracture. Clinicians should maintain a high index of suspicion for these injuries in patients with symphyseal osteomyelitis.

Is Bone Marrow Aspiration and Biopsy of Clinical Importance in the Initial Staging of Extraskeletal Ewing Sarcoma?

BACKGROUND: Extraskeletal Ewing sarcoma are rare tumors within the Ewing sarcoma family. Initial staging studies for extraskeletal Ewing sarcoma historically have included imaging and bone marrow aspiration and biopsy (BMAB). However, recent studies on Ewing sarcoma of bone have questioned the utility of BMAB in the initial staging of patients, but no studies of which we are aware have evaluated the role of BMAB in extraskeletal Ewing sarcoma. We suspected that BMAB was of low diagnostic yield in patients with extraskeletal Ewing sarcoma and exposed patients to potential morbidity without an impact on their clinical course. QUESTION/PURPOSE: Is BMAB a useful test in the staging of extraskeletal Ewing sarcoma? METHODS: Between January 1996 and December 2021, our institution evaluated 109 patients with a listed diagnosis of extraskeletal Ewing sarcoma. Those patients were retrospectively reviewed for this study. Of those, we considered patients with biopsy-confirmed diagnosis of extraskeletal Ewing sarcoma. Biopsy was performed based on institutional protocols, with all diagnoses assigned by a board-certified pathologist. Based on that criteria, 96% (105 of 109) were eligible. An additional 18% (20 of 109) were excluded because records of their initial diagnostic and staging workup were not available. This left 78% (85 of 109) for analysis. Of those, 52% (44 of 85) were male. The average age was 32 ± 16 years. Primary tumor locations included extremities in 26% (22 of 85), paraspinal in 20% (17 of 85), chest in 19% (16 of 85), retroperitoneum in 13% (11 of 85), intraabdominal in 12% (10 of 85), intrapelvic in 7% (6 of 85), and head or neck in 4% (3 of 85). Initial diagnostic and staging information, including the use of PET-CT, bone scan, CT chest, and BMAB, was collected. Metastatic disease at the time of presentation or during follow-up was noted. The utility of BMAB was determined by the rate of positive tests in those undergoing BMAB during the initial staging process. Descriptive statistical analysis was sufficient to address the study question, and therefore no comparative statistics were performed. RESULTS: BMAB was obtained during the initial staging process in 64% (54 of 85) of patients. This BMAB was negative in all 54 patients, including those with known metastatic disease. CONCLUSION: Diagnosing metastatic disease in extraskeletal Ewing sarcoma is important as the presence of metastases at diagnosis adversely affects prognosis. The routine use of BMAB in the staging process of extraskeletal Ewing sarcoma is of low diagnostic yield. BMAB is unlikely to diagnose metastatic involvement even in patients with known metastases to bone. We do not have enough data to suggest whether other modalities, such as PET-CT, might be more useful. Similar studies should be pursued to determine the utility of the remainder of staging modalities in patients with extraskeletal Ewing sarcoma to elucidate the most efficient and effective staging protocol. LEVEL OF EVIDENCE: Level III, diagnostic study.

Spinal Fusion in Patients With Classic Amyoplasia and General Arthrogryposis.

BACKGROUND: Arthrogryposis multiplex congenita is a group of conditions characterized by joint contractures affecting 2 or more joints. This study describes results of spinal fusion in patients with classic amyoplasia and general arthrogryposis. METHODS: IRB approved retrospective review of patients with a diagnosis of classic amyoplasia and general arthrogryposis who had a primary definitive posterior spinal fusion between 1990 and 2017 at a single pediatric institution. Patients with distal and syndromic arthrogryposis were excluded as well as patients treated with growth-sparing spinal instrumentation. The Modified Clavien-Dindo-sink (MCDS) classification system was used to describe postoperative complications. RESULTS: Over the 28-year period, 342 patients were diagnosed with amyoplasia and general arthrogryposis. Among the 342 patients, 60 (18%) had scoliosis, and 22 (6% of the cohort and 37% of those with scoliosis) were treated surgically. Six patients had growth-sparing techniques, initial fusion elsewhere, or ˂1 year of follow-up, leaving 15 patients. Of the 15, 9 (60%) had a posterior spinal fusion (PSF) and 6 (40%) had a combined anterior spinal fusion (ASF)/PSF. The ASF/PSF group was significantly younger at surgery, had a greater American Society of Anesthesiologists status, longer surgery duration, and lower implant density. The average preoperative major coronal deformity in ASF/PSF patients (108 degrees) was greater than patients treated with PSF alone (88 deg). There were 11 complications in 7 patients, with the most common being deep infection requiring reoperation (5/11, 45%). There was 1 instance (1/11, 9%) of each: prolonged intensive care unit admission (>72 h), superficial wound dehiscence, symptomatic implants requiring removal/revision, coronal plane progression requiring extension of fusion, recurrent pneumothorax requiring return to OR, and pseudoarthrosis leading to implant failure (without revision). Complications occurred in 1/9 (11%) PSF-only patients and 6/6 (100%) ASF/PSF patients with all 6 ASF/PSF patients requiring at least 1 reoperation. The average coronal correction was 48% in the PSF-only group and 28% in the ASF/PSF group. CONCLUSION: Complication rates after spinal fusion for scoliosis in arthrogryposis multiplex congenita patients are high, especially in patients undergoing ASF/PSF, deep infection is common, and major coronal plane curve correction is modest. LEVEL OF EVIDENCE: II Retrospective Study.

Does Shorter Time to Treatment of Pediatric Supracondylar Humerus Fractures Impact Clinical Outcomes?

BACKGROUND: Treatment of supracondylar humerus (SCH) fractures within 18 hours of presentation is a tracked quality metric for ranking of pediatric hospitals. This is in contrast with literature that shows time to treatment does not impact outcomes in SCH fractures. We aim to determine whether an 18-hour cutoff for pediatric supracondylar humerus fracture treatment is clinically significant by comparing the complication risks ofpatients on either side of this timepoint. Our hypothesis is that there will be no statistically significant differences based on time to treatment. METHODS: A retrospective review of clinical outcomes was performed for 472 pediatric patients who underwent surgical management of isolated supracondylar humerus fractures between 1997 and 2022 at a single level I pediatric trauma hospital. The cohort was split based on time to surgery (within or ≥18 h from Emergency Department admission). RESULTS: Surgical treatment occurred within 18 hours of arrival in 435 (92.2%) patients and after 18 hours in 37 (7.8%) patients. Mean age was 5.6±2.2 years and 51.5% of patients were female. Gartland fracture classification was type II [n=152 (32.3%)], type III [n=284 (60.3%)], type IV [n=13 (2.8%)], or flexion-type [n=18 (3.8%)]. There were no differences in demographic characteristics or fracture classification between cohorts. Fractures in the ≥18-hour cohort were treated more commonly with 2 pins (62.2% vs. 38.5%, P =0.04). There were no statistically significant differences in open versus closed reduction, utilization of medial pins, or postoperative immobilization between cohorts. We were unable to detect any differences in postoperative complications, including non-union, delayed union, stiffness, malunion, loss of reduction, iatrogenic nerve injury, or infection. This remained true when type II fractures were excluded. CONCLUSIONS: Using an arbitrary time cutoff of <18 hours does not influence clinical outcomes in the surgical treatment of SCH fractures. This held true when type II fractures were excluded. For this reason, we recommend modification to the USNWR guidelines to decrease emphasis on time-to-treatment of SCH fractures. LEVEL OF EVIDENCE: Level III.

Arthrogryposis multiplex congenita: a 28-year retrospective study.

AIM: To identify all patients with arthrogryposis multiplex congenita presenting to a specialized pediatric orthopedic institution over a 28-year period; classify them into three groups (general arthrogryposis not otherwise specified [NOS], amyoplasia, or distal arthrogryposis); report the frequency of various musculoskeletal features; and determine the rate of operative treatment. METHOD: Patients with arthrogryposis under the age of 18 years who presented between 1990 and 2017 were included. Patients were placed into one of three groups based on clinical features and family history when available. Age of presentation, joint involvement, and utilization of surgical treatment were recorded. RESULTS: There were 417 patients in total (184 females, 233 males); 235 patients (56.4%) had general arthrogryposis NOS, 107 (25.7%) had amyoplasia, and 75 (18.0%) had distal arthrogryposis. Patients with amyoplasia presented at a younger age (median 4mo) than those with general arthrogryposis NOS (median 1y 3mo, p=0.005), and had a lower rate of spine involvement than patients with general arthrogryposis NOS (p=0.004) and distal arthrogryposis (p=0.023). The average number of surgeries across all patients was 1.9 (SD 2.2). INTERPRETATION: Pediatric patients with amyoplasia present to orthopedic care earlier and are less likely to have spine involvement than other forms of arthrogryposis. Multiple surgeries are common among all patients with arthrogryposis.

Assessing the Accuracy and Reliability of the Fluoroscopic Ruler for Comminuted Femur Fractures: A Cadaveric Study.

BACKGROUND: Fixation of comminuted femur fractures may result in limb length discrepancy. Intraoperative fluoroscopic measurement of the contra-lateral femur with a ruler is commonly performed to establish a reference for femoral length. No evidence regarding the reliability and accuracy of this technique exists. This study aimed to assess the accuracy and interrater reliability of a fluoroscopic ruler in obtaining correct femoral length in a comminuted femoral shaft fracture model. MATERIALS AND METHODS: Approximately 5 cm of bone was removed from the left femoral diaphyses of 8 cadavers. Seven orthopedic surgery residents and 2 attendings measured the length of the intact contralateral femur using a ruler under fluoroscopy. The ruler was then applied to the "fractured" femur with manual traction applied until femoral length matched the measured length of the contralateral femur. The resulting gap in the "fractured" femur was compared with the length of bone that had been resected. Data were analyzed using means, SDs, and intraclass correlation coefficients (ICCs). RESULTS: Fifty-seven measurements were collected. The mean difference between the measured fracture gap and the length of bone removed was 8.0±5.8 mm (range, 0-22 mm). Femoral length was accurate to 5 mm in 40% of cases, 10 mm in 70%, 15 mm in 81%, 20 mm in 98%, and 25 mm in 100%. The overall interrater reliability was poor (ICC, 0.11; 95% CI, 0.001-0.44). CONCLUSION: Despite poor interrater reliability, the fluoroscopic ruler resulted in a mean leg length discrepancy of 8.0±5.8 mm in this cadaveric study. [Orthopedics. 202x;4x(x):xx-xx.].

Multidisciplinary Treatment of Merkel Cell Carcinoma of the Extremities: Outcomes and Factors Associated with Poor Survival in Nodal Disease.

Merkel cell carcinoma (MCC) has a tendency for lymphatic spread and locoregional recurrence, although there is little data examining the risk factors for patients with lymph node-positive extremity lesions. The purpose of the current study was to examine the outcomes and risk factors associated with nodal metastasis in extremity MCC. We retrospectively reviewed the medical record of 120 patients with extremity MCC evaluated at our institution between 1994 and 2021. The mean age of this cohort was 71 years; 33% of patients were female; and 98% were Caucasian. Seventy-eight (65%) patients presented with localized disease. Thirty-seven (31%) patients had stage III disease, and five (4%) patients had stage IV disease. Treatment of primary lesions consisted primarily of margin-negative excision and adjuvant radiotherapy. Nodal metastases were most treated with adjuvant radiation or completion lymph node dissection. Five-year disease-specific survival in our series was 88% for patients with localized disease, 89% for stage IIIa disease, 40% for stage IIIb disease and 42% for stage IV. Factors associated with worse survival included immunosuppression and macroscopic nodal disease. In conclusion, extremity MCC has a low rate of local recurrence when treated with margin-negative excision and adjuvant radiation. However, treatment of nodal metastases remains a challenge with high rates of recurrence and mortality, particularly for patients who are immunosuppressed or who have macroscopic nodal disease.

An essential N-terminal serine-rich motif in the AAV VP1 and VP2 subunits that may play a role in viral transcription.

Adeno-associated virus (AAV) is one of the most researched, clinically utilized gene therapy vectors. Though clinical success has been achieved, transgene delivery and expression may be hindered by cellular and tissue barriers. Understanding the role of receptor binding, entry, endosomal escape, cytoplasmic and nuclear trafficking, capsid uncoating, and viral transcription in therapeutic efficacy is paramount. Previous studies have shown that N-terminal regions of the AAV capsid proteins are responsible for endosomal escape and nuclear trafficking, however the mechanisms remain unknown. We identified a highly-conserved three-residue serine/threonine (S/T) motif in the capsid N-terminus, previously uncharacterized in its role in intracellular trafficking and transduction. Using alanine scanning mutagenesis, we found S155 and the flanking residues, D154 and G158, are essential for AAV2 transduction efficiency. Remarkably, specific capsid mutants show a 5 to 9-fold decrease in viral mRNA transcripts, highlighting a potential role of the S/T motif in transcription of the viral genome.