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INTRODUCTION: The purpose of this study was to describe the outcomes after operative repair of ballistic femoral neck fractures. To better highlight the devastating nature of these injuries, we compared a cohort of ballistic femoral neck fractures to a cohort of young, closed, blunt-injury femoral neck fractures treated with open reduction and internal fixation (ORIF). METHODS: Retrospective chart review identified all patients presenting with ballistic femoral neck fractures treated at three academic trauma centers between January 2016 and December 2021, as well as patients aged ≤50 with closed, blunt-injury femoral neck fractures who received ORIF. The primary outcome was failure of ORIF, which includes the diagnosis of non-union, avascular necrosis, conversion to total hip arthroplasty, and conversion to Girdlestone procedure. Additional outcomes included deep infection, postoperative osteoarthritis, and ambulatory status at last follow-up. RESULTS: Fourteen ballistic femoral neck fractures and 29 closed blunt injury fractures were identified. Of the ballistic fractures, 7 (50%) patients had a minimum of 1-year follow-up or met the failure criteria. Of the closed fractures, 16 (55%) patients had a minimum of 1-year follow-up or met the failure criteria. Median follow-up was 21 months. 58% of patients with ballistic fractures were active tobacco users. Five of 7 (71%) ballistic fractures failed, all of which involved non-union, whereas 8 of 16 (50%) closed fractures failed (p=0.340). No outcomes were significantly different between cohorts. CONCLUSION: Our results demonstrate that ballistic femoral neck fractures are associated with high rates of non-union. Large-scale multicenter studies are necessary to better determine optimal treatment techniques for these fractures. LEVEL OF EVIDENCE: Level III. Retrospective cohort study.

BackgroundThere is significant variability both in how proximal humerus fractures (PHFs) are treated and the ensuing patient outcomes. The purpose of this study was to investigate which surgeon- and patient-specific factors contribute to decision-making in the treatment of adult PHFs. We hypothesized that orthopedic sub-specialty training creates inherent bias and plays an important role in management algorithms for PHFs.MethodsWe performed a prospective cohort investigation in 2 groups of surgeons-traumatologists (N = 25) and shoulder & elbow/sports surgeons (SES) (N = 26)-and asked them to provide treatment recommendations for 30 distinct clinical cases with standardized radiographic and clinical data. This is a population-based sample of surgeons who take trauma call and treat PHFs with different sub-specializations and practice settings including academic, hospital-employed, and private. Surgeons characterized based on subspecialty (trauma vs. SES), experience level (>10 vs. ≤10-years), and employment type (hospital- vs. non-hospital-employed). Chi-square analyses, logistic mixed-effects modeling, and relative importance analysis were used to evaluate the data.ResultsOf the patient-specific factors, we found that the management of PHFs is largely dependent on initial radiographs obtained. Traumatologists were more likely to offer open reduction internal fixation (ORIF) and less likely to offer arthroplasty: 69% ORIF (traumatologists) vs. 51% ORIF (SES, P

IntroductionIt is our hypothesis that physician-specific variables affect the management of distal radius (DR) fractures in addition to patient-specific factors.MethodsA prospective cohort study was conducted evaluating treatment differences between Certificate of Additional Qualification hand surgeons (CAQh) and board-certified orthopaedic surgeons who treat patients at level 1 or level 2 trauma centers (non-CAQh). After institutional review board approval, 30 DR fractures were selected and classified (15 AO/OTA type A and B and 15 AO/OTA type C) to create a standardized patient data set. The patient-specific demographics and surgeon's information regarding the volume of DR fractures treated per year, practice setting, and years posttraining were obtained. Statistical analysis was done using chi-square analysis with a postanalysis regression model.ResultsA notable difference was observed between CAQh and non-CAQh surgeons. Surgeons in practice longer than 10 years or who treat >100 DR fractures/year were more likely to choose surgical intervention and obtain a preoperative CT scan. The two most influential factors in decision making were the patients' age and medical comorbidities, with physician-specific factors being the third most influential in medical decision making.DiscussionPhysician-specific variables have a notable effect on decision making and are critical for the development of consistent treatment algorithms for DR fractures.

BackgroundPatients with psychiatric comorbidities represent a significant subset of those sustaining pilon fractures. The purpose of this study is to examine the association of psychiatric comorbidities (PC) in patients with pilon fractures and clinical outcomes.MethodsA multi-institution, retrospective review was conducted. Inclusion/exclusion criteria were skeletally mature patients with a tibia pilon fracture (OTA Type 43B/C) who underwent definitive fracture fixation utilizing open reduction internal fixation (ORIF) with a minimum of 24 weeks of follow-up. Patients were stratified into two groups for comparison: PC group and no PC group.ResultsThere were 103 patients with pilon fractures that met the inclusion/exclusion criteria of this study. Of these patients, 22 (21.4%) had at least one psychiatric comorbidity (PC) and 81 (78.6%) did not have psychiatric comorbidities (no PC). There was a higher percentage of female patients (PC: 59.1% vs no PC: 25.9%, p=0.0.005), smokers (PC: 40.9% vs no PC: 16.0%, p=0.02), and drug users (PC: 22.7% vs no PC: 8.6%, p=0.08) amongst PC patients. Fracture comminution (PC: 54.5% vs no PC: 32.1%, p=0.05) occurred more frequently in PC patients. The PC group had a higher incidence of weightbearing noncompliance (22.7% vs 7.5%, p=0.04) and reoperation (PC: 54.5% vs no PC: 29.6%, p=0.03).ConclusionPatients with psychiatric comorbidities represent a significant percentage of pilon fracture patients and appear to be at higher risk for postoperative complication. Risk factors that may predispose patients in the PC group include smoking/substance use, weightbearing noncompliance, and fracture comminution. Level of Evidence: III.

The incidence of reinjury after treatment of rotator cuff tears (RCTs) remains very high despite the variety of nonoperative treatments and the high volume of surgical interventions performed. Muscle stem cells (MuSCs), also known as satellite cells, have risen to the forefront of rotator cuff tear research as a potential adjuvant therapy to aid unsatisfactory surgical outcomes. MuSCs are adult stem cells exhibiting the capacity to proliferate and self-renew, both symmetrically and asymmetrically. As part of this niche, they have been shown to adopt an activated phenotype in response to musculoskeletal injury and decrease their cellular populations during aging, implicating them as key players in both pathologic and normal physiological processes. While commonly connected to the regenerative phase of muscle healing, MuSCs also have the potential to differentiate into adverse morphologies. For instance, if MuSCs differentiate into adipocytes, the ensuing fatty infiltration serves as an obstacle to proper muscle healing and has been associated with the failure of surgical management of RCTs. With the potential to both harm and heal, we have identified MuSCs as a key player in RCT repair. To better understand this dichotomy, the following review will identify key studies regarding the morphology, function, and behavior of MuSCs with respect to RCTs and healing.

PurposeLimited data exist regarding volumetric trends and management of upper-extremity emergencies during periods of social restriction and duress, such as the coronavirus disease 2019 pandemic. We sought to study the effect of shelter-in-place orders on emergent operative upper-extremity surgery.MethodsAll patients undergoing emergent and time-sensitive operations to the finger(s), hand, wrist, and forearm were tracked over an equal number of days before and after shelter-in-place orders at 2 geographically distinct Level I trauma centers. Surgical volume and resources, patient demographics, and injury patterns were compared before and after official shelter-in-place orders.ResultsA total of 58 patients underwent time-sensitive or emergent operations. Mean patient age was 42 years; mean injury severity score was 9 and median American Society of Anesthesiologist score was 2. There was a 40% increase in volume after shelter-in-place orders, averaging 1.4 cases/d. Indications for surgery included high-energy closed fracture (60%), traumatic nerve injury (19%), severe soft tissue infection (15%), and revascularization of the arm, hand, or digit(s) (15%). High-risk behavior, defined as lawlessness, assault, and high-speed auto accidents, was associated with a significantly greater proportion of operations after shelter-in-place orders (40% vs 12.5%; P < .05). Each institution dedicated an average of 3 inpatient beds and one intensive care unit-capable bed to upper-extremity care daily. Resources used included an average of 115 minutes of daily operating room time and 8 operating room staff or personnel per case.ConclusionsHand and upper-extremity operative volume increased after shelter-in-place orders at 2 major Level I trauma centers across the country, demanding considerable hospital resources. The rise in volume was associated with an increase in high-risk behavior.Type of study/level of evidenceTherapeutic IV.

BackgroundPeripheral nerve compression and entrapment can be debilitating. Using a validated animal model of peripheral nerve compression, we examined the utility of 2 drugs approved for other uses in humans, 4-aminopyridine (4-AP) and erythropoietin (EPO), as treatments for surgically induced ischemia and as adjuvants to surgical decompression.MethodsPeripheral nerve compression was induced in wild-type mice by placing an inert silicone sleeve around the sciatic nerve. Decompression surgery was performed at 6 weeks with mice receiving 4-AP, EPO, or saline solution either during and after compression or only after decompression. A nerve conduction study and morphometric analyses were performed to compare the extent of the injury and the efficacy of the therapies, and the findings were subjected to statistical analysis.ResultsDuring peripheral nerve compression, there was a progressive decline in nerve conduction velocity compared with that in sham-treatment animals, in which nerve conduction velocity remained normal (∼55 m/s). Mice treated with 4-AP or EPO during the compression phase had significantly smaller declines in nerve conduction velocity and increased plateau nerve conduction velocities compared with untreated controls (animals that received saline solution). Histomorphometric analyses of newly decompressed nerves (i.e., nerves that underwent decompression on the day that the mouse was sacrificed) revealed that both treated groups had significantly greater proportions of large (>5-µm) axons than the untreated controls. Following surgical decompression, all animals recovered to a normal baseline nerve conduction velocity by day 15; however, treatment significantly accelerated improvement (in both the 4-AP and the EPO group), even when it was only started after decompression. Histomorphometric analyses at 7 and 15 days following surgical decompression revealed significantly increased myelin thickness and significantly greater proportions of large axons among the treated animals.ConclusionsBoth the 4-AP and the EPO-treated group demonstrated improvements in tissue architectural and electrodiagnostic measurements, both during and after peripheral nerve compression, compared with untreated mice.Clinical relevancePeripheral nerve decompression is one of the most commonly performed procedures in orthopaedic surgery. We believe that there is reason for some optimism about the translation of our findings to the clinical setting. Our findings in this murine model suggest that 4-AP and EPO may lessen the effects of nerve entrapment and that the use of these agents after decompression may speed and perhaps otherwise optimize recovery after surgery.

BackgroundThe numbers of people requiring total arthroplasty is expected to increase substantially over the next two decades. However, increasing costs and new payment models in the USA have created a sustainability gap. Ad hoc interventions have reported marginal cost reduction, but it has become clear that sustainability lies only in complete restructuring of care delivery. The Perioperative Surgical Home (PSH) model, a patient-centered and physician-led multidisciplinary system of coordinated care, was implemented at UC Irvine Health in 2012 for patients undergoing primary elective total knee arthroplasty (TKA) or total hip arthroplasty (THA). This observational study examines the costs associated with this initiative.MethodsThe direct cost of materials and services (excluding professional fees and implants) for a random index sample following the Total Joint-PSH pathway was used to calculate per diem cost. Cost of orthopedic implants was calculated based on audit-verified direct cost data. Operating room and post-anesthesia care unit time-based costs were calculated for each case and analyzed for variation. Benchmark cost data were obtained from literature search. Data are presented as mean ± SD (coefficient of variation) where possible.ResultsTotal per diem cost was $10,042 ± 1,305 (13%) for TKA and $9,952 ± 1,294 (13%) for THA. Literature-reported benchmark per diem cost was $17,588 for TKA and $16,267 for THA. Implant cost was $7,482 ± 4,050 (54%) for TKA and $9869 ± 1,549 (16%) for THA. Total hospital cost was $17,894 ± 4,270 (24%) for TKA and $20,281 ± 2,057 (10%) for THA. In-room to incision time cost was $1,263 ± 100 (8%) for TKA and $1,341 ± 145 (11%) for THA. Surgery time cost was $1,558 ± 290 (19%) for TKA and $1,930 ± 374 (19%) for THA. Post-anesthesia care unit time cost was $507 ± 187 (36%) for TKA and $557 ± 302 (54%) for THA.ConclusionsDirect hospital costs were driven substantially below USA benchmark levels using the Total Joint-PSH pathway. The incremental benefit of each step in the coordinated care pathway is manifested as a lower average length of stay. We identified excessive variation in the cost of implants and post-anesthesia care.

BACKGROUND: Chronic nerve compression neuropathies result in decreased blood flow at the site of compression. Surgical decompression of the nerve often has variable postoperative results. The current study examines whether the timing of surgical intervention is an important variable in reversing the compression-induced ischemia and associated changes in biochemical markers. METHODS: An established model of chronic nerve compression injury was created in 100 C57BL/6 mice, and serial electrophysiological examinations were used to confirm the creation of a chronic nerve compression injury. Laser speckle imaging was used to measure neural blood flow. Nerves in the animals that did not undergo decompression were harvested at two, four, and six weeks after injury and analyzed for hypoxia-inducible factor 1α (HIF1α), catalase, superoxide dismutase (SOD), and matrix metalloproteinases (MMPs) 2 and 9. Surgical decompression in other animals was performed at either an early (two-week) or late (six-week) time point after injury, with specimens harvested at multiple time points after decompression. One-way analysis of variance with Bonferroni correction was performed. RESULTS: Chronic nerve compression injury initially induced hyperemia (1.37 ± 0.50 times that in the contralateral, uninjured nerve) followed by a decline in neural blood flow by four weeks (0.66 ± 0.14, p = 0.0313). In parallel, HIF1α, catalase, and SOD were elevated early after compression, whereas extracellular matrix-altering proteins were elevated later in the disease. Although early decompression yielded a return of blood flow to a hyperemic state (1.35 ± 0.16, p = 0.0057), late decompression did not result in reversal of the abnormal neurovascular flow. With late decompression, an MMP9-mediated structural alteration of the extracellular matrix was seen, producing irreversible changes in blood flow parameters. Although nerve conduction velocity measurements returned to normal two weeks after decompression irrespective of the timing of the surgical intervention, distal latency returned to normal only after early decompression (0.97 ± 0.06 msec compared with 1.22 ± 0.06 msec for late decompression, p = 0.009). CONCLUSIONS: Chronic nerve compression injuries decreased neurovascular flow and induced ischemia by upregulating HIF1α, catalase, and MMP9. Early surgical intervention offered better return to normal electrophysiological parameters compared with late intervention. CLINICAL RELEVANCE: These data present a clinical correlate to the variable functional outcomes seen following surgical release of chronic nerve compression injuries and provide early support for using distal latency as a predictor of outcomes following surgical release.

ObjectiveChronic nerve compression (CNC) injuries occur when peripheral nerves are subjected to sustained mechanical forces, with increasing evidence implicating Schwann cells as key mediators. Integrins, a family of transmembrane adhesion molecules that are capable of intracellular signaling, have been implicated in a variety of biological processes such as myelination and nerve regeneration. In this study, we seek to define the physical stimuli mediating demyelination and to determine whether integrin plays a role in the demyelinating response.MethodsWe used a previously described in vitro model of CNC injury where myelinating neuron-Schwann cell cocultures were subjected to independent manipulations of hydrostatic pressure, hypoxia, and glucose deprivation in a custom bioreactor. We assessed whether demyelination increased in response to applied manipulation and determined whether integrin-associated signaling cascades are upregulated.ResultsBiophysical stimulation of neural tissue induced demyelination and Schwann cell proliferation without neuronal or glial cytotoxicity or apoptosis. Although glucose deprivation and hypoxia independently had minor effects on myelin stability, together they potentiated the demyelinating effects of hydrostatic compression, and in combination, significantly destabilized myelin. Biophysical stimuli transiently increased phosphorylation of the integrin-associated tyrosine kinase Src within Schwann cells. Silencing this integrin signaling cascade blocked Src activation and prevented pressure-induced demyelination. Colocalization analysis indicated that Src is localized within Schwann cells.InterpretationThese results indicate that myelin is sensitive to CNC injury and support the novel concept that myelinating cocultures respond directly to mechanical loading via activating an integrin signaling cascade.

Surgical treatment for degenerative conditions of the hip, knee, and spine has an impact on overall healthcare spending. Surgical rates have increased dramatically and considerable regional variation has been observed. The reasons behind these increasing rates and variation across regions have not been well elucidated.We therefore identified demographic (D), social structure (SS), health belief (HB), personal (PR) and community resources (CR), and medical need (MN) factors that drive rates of hip, knee, and spine surgery.We conducted a systematic review to include all observational, population-based studies that compared surgical rates with potential drivers (D, SS, HB, PR, CR, MN). We searched PubMed combining key words focusing on (1) disease and procedure; (2) study methodology; and (3) explanatory models. Independent investigators selected potentially eligible studies from abstract review and abstracted methodological and outcome data. From an initial search of 256 articles, we found 37 to be potentially eligible (kappa 0.86) but only 28 met all our inclusion criteria.Age, nonminority, insurance coverage, and surgeon enthusiasm all increased surgical rates. Rates of arthroplasty were higher for females with higher education, income, obesity, rurality, willingness to consider surgery, and prevalence of disease, whereas spinal rates increased with male gender, lower income, and the availability of advanced imaging.Regional variation in these procedures exists because they are examples of preference-sensitive care. With strategies that may affect change in factors that are potentially modifiable by behavior or resources, extreme variation in rates may be reduced.

Compression neuropathies are highly prevalent, debilitating conditions with variable functional recovery following surgical decompression. Due to the limited amount of human nerve tissue available for analysis, a number of animal models have been created to help investigators understand the molecular and cellular pathogenesis of chronic nerve compression (CNC) injury. Evidence suggests that CNC injury induces concurrent Schwann cell proliferation and apoptosis in the early stages of the disorder. These proliferating Schwann cells downregulate myelin proteins, leading to local demyelination and remyelination in the region of injury. In addition, the downregulation of myelin proteins, in particular myelin-associated glycoprotein, allows for axonal sprouting. Interestingly, these changes occur in the absence of both morphological and electrophysiological evidence of axonal damage. This is in direct contrast to acute injuries, such as transection or crush, which are characterized by axonal injury followed by Wallerian degeneration. Because the accepted trigger for Schwann cell dedifferentiation is axonal injury, an alternate mechanism for Schwann response must exist in CNC injury. In vitro studies of pure Schwann cells have shown that these cells can respond directly to mechanical stimuli by downregulating myelin proteins and proliferating. These studies suggest that although the reciprocal relationship between neurons and glial cells is maintained, chronic nerve compression injury is a Schwann cell-mediated disease. (DOI: 10.3171/FOC.2009.26.2.E7)

Background and purposeThe New Zealand white rabbit subscapularis tendon passes under a bony arch to insert on the lesser tubercle of the humerus in a manner analogous to the supraspinatus tendon in humans. We assessed whether this unique anatomy may provide a new animal model of the shoulder to improve our understanding of rotator cuff pathology.MethodsThe dimensions of the rotator cuff insertions (subscapularis, supraspinatus, and infraspinatus) were measured on 10 fresh frozen cadaveric New Zealand white rabbit shoulders. Mechanical testing was performed on 8 fresh frozen subscapularis insertions (4 matched pairs). Video analysis of the gait cycle was performed on 2 live animals.ResultsThe origins, insertions, and innervations of the rabbit rotator cuff musculature are analogous to those in humans. However, the rabbit acromion is a rudimentary structure with only the infraspinatus and teres minor muscles passing beneath. Furthermore, at the point where the infraspinatus passes under the arch, it is muscular rather than tendinous. The anterior aspect of the glenohumeral joint contains an additional bony tunnel with its boundaries being the tuberculum supraglenoidale laterally, the coracoideus process superiorly, the tuberculum infraglenoidale inferiorly, and the coracobrachialis muscle medially. The origin of the rabbit subscapularis muscle resides on the anterior scapula. The subscapularis tendon then traverses this bony tunnel prior to its insertion on the lesser tubercle of the humerus. Video analysis and anatomic dissections confirmed excursion of the subscapularis tendon within this bony tunnel throughout the gait cycle. The subscapularis footprint on the proximal humerus measured 6.8 mm (SD 0.29) x 2.5 mm (SD 0.17). Mechanical testing of the subscapularis tendon showed the stiffness to range from 57 to 117 N/mm (SD 23). Ultimate yield ranged from 88 to 215 N (SD 518). The elastic modulus of the rabbit tendon was 56 MPa. 6 of the 8 subscapularis tendons failed at the tendon mid-substance; the other 2 failed at the bony insertion.InterpretationThe unique anatomic architecture and the mechanical characteristics of the rabbit subscapularis muscle provide an opportunity to improve our understanding of rotator cuff pathology.