Identifying clinically meaningful subgroups following open reduction and internal fixation for proximal humerus fractures: a risk stratification analysis for mortality and 30-day complications using machine learning.

Background: Identification of prognostic variables for poor outcomes following open reduction internal fixation (ORIF) of displaced proximal humerus fractures have been limited to singular, linear factors and subjective clinical intuition. Machine learning (ML) has the capability to objectively segregate patients based on various outcome metrics and reports the connectivity of variables resulting in the optimal outcome. Therefore, the purpose of this study was to (1) use unsupervised ML to stratify patients to high-risk and low-risk clusters based on postoperative events, (2) compare the ML clusters to the American Society of Anesthesiologists (ASA) classification for assessment of risk, and (3) determine the variables that were associated with high-risk patients after proximal humerus ORIF. Methods: The American College of Surgeons-National Surgical Quality Improvement Program database was retrospectively queried for patients undergoing ORIF for proximal humerus fractures between 2005 and 2018. Four unsupervised ML clustering algorithms were evaluated to partition subjects into "high-risk" and "low-risk" subgroups based on combinations of observed outcomes. Demographic, clinical, and treatment variables were compared between these groups using descriptive statistics. A supervised ML algorithm was generated to identify patients who were likely to be "high risk" and were compared to ASA classification. A game-theory-based explanation algorithm was used to illustrate predictors of "high-risk" status. Results: Overall, 4670 patients were included, of which 202 were partitioned into the "high-risk" cluster, while the remaining (4468 patients) were partitioned into the "low-risk" cluster. Patients in the "high-risk" cluster demonstrated significantly increased rates of the following complications: 30-day mortality, 30-day readmission rates, 30-day reoperation rates, nonroutine discharge rates, length of stay, and rates of all surgical and medical complications assessed with the exception of urinary tract infection (P < .001). The best performing supervised machine learning algorithm for preoperatively identifying "high-risk" patients was the extreme-gradient boost (XGBoost), which achieved an area under the receiver operating characteristics curve of 76.8%, while ASA classification had an area under the receiver operating characteristics curve of 61.7%. Shapley values identified the following predictors of "high-risk" status: greater body mass index, increasing age, ASA class 3, increased operative time, male gender, diabetes, and smoking history. Conclusion: Unsupervised ML identified that "high-risk" patients have a higher risk of complications (8.9%) than "low-risk" groups (0.4%) with respect to 30-day complication rate. A supervised ML model selected greater body mass index, increasing age, ASA class 3, increased operative time, male gender, diabetes, and smoking history to effectively predict "high-risk" patients.

Declining Rate of International Medical Graduates Matching Into Orthopedic Surgery Residency Programs in the United States: A 17-Year Analysis.

Introduction: International medical graduates (IMGs) continue to play an important role in the US health care system, but little is known about their trends of matching into highly competitive residencies such as orthopedic surgery. The purpose of this study was to analyze temporal trends of IMG applicants matching into US orthopedic residency programs between 2008 and 2024 and compare them with US allopathic (MD) and osteopathic (DO) graduates. Methods: Orthopedic residency specific data for years 2008 to 2024 was obtained from the National Resident Match Program and Electronic Residency Application Service. Variables collected included total number of programs, total positions offered, number of applicants (MD, DO, and IMG), positions filled, and fill rate for each group. Trends were examined using simple linear regression modeling. Results: The number of orthopedic residency programs increased from 160 (2008) to 218 (2024), with total positions increasing from 636 (2008) to 916 (2024). The IMG fill rate decreased from 2.99% in 2008 to 0.87% in 2024 (p < 0.01 for linear trend; ß -0.069). This corresponds to an absolute number decrease of 19 IMGs in 2008 to 8 in 2024. More specifically, the proportion of US IMGs decreased from 0.94% to 0.66%, and the proportion of non-US IMGs decreased from 2.04% to 0.21%. Over the 17-year study period, a total of 105 US IMGs and 110 non-US IMGs matched into orthopedic surgery. The US MD applicant fill rate decreased significantly from 96.5% to 85.0% (p < 0.001; ß -0.944). The DO applicant fill rate increased significantly from 0.31% to 13.97% (p < 0.0001; ß 0.990). Conclusion: The declining rate of IMGs matching into orthopedic residency programs in the United States underscores the growing challenges faced by IMGs in accessing training in this competitive specialty. The notable increase in DO graduates securing orthopedic residency positions likely reflects the integration of a unified accreditation system for MD and DO residency programs established in 2020. Level of Evidence: Retrospective Cohort Study; IV.

Paralysis of the trapezius muscle: evaluation and surgical management.

Background: Paralysis of the trapezius muscle most commonly results from iatrogenic injury to the spinal accessory nerve. Methods: The clinical presentation and physical examination findings of trapezius palsy have been well characterized, but unfortunately the diagnosis of this condition is oftentimes missed or delayed, sometimes leading to unnecessary surgery on the rotator cuff or tendon of the long head of the biceps. Results: The diagnosis can be confirmed using electromyography with nerve conduction studies. Although nonoperative treatment may help some patients with temporary neurapraxia of the spinal accessory nerve, nerve repair with or without nerve grafting should be performed soon for patients suspected of a nerve transection. Nerve transfers can be considered within the first year after the injury when nerve repair and grafting cannot be completed. For chronic trapezius palsy, transfer of the levator scapulae and rhomboids has been refined and represents a very successful surgical procedure. Rarely, scapulothoracic arthrodesis is considered for individuals with failed tendon transfers or multiple nerve involvement. Conclusion: Trapezius palsy is oftentimes missed. An accurate diagnosis allows consideration of various treatment modalities that have been reported to provide good outcomes for properly selected patients.

Evaluation of the Dysfunctional Scapula.

Periscapular pain and dysfunction are relatively common complaints in the practice of upper extremity surgeons. However, evaluation of the dysfunctional scapula is intimidating for most. Physical examination of the periscapular muscles is very rich, and a systematic approach provides the opportunity to establish a diagnosis for most patients. Conditions underlying scapular dysfunction include trapezius palsy, serratus palsy, brachial plexus injuries, muscular dystrophy, snapping scapula, pectoralis minor syndrome, congenital undescended scapula, and functional scapular dyskinesis, among others. Patients should be examined with their torso uncovered and assessed from the front and back. Inspection, evaluation of motion, and strength testing may be followed by certain examination maneuvers specific for each condition. The scapular assistance test may help predict the outcome of treatment for certain conditions. Plain radiographs oftentimes need to be complemented with magnetic resonance of the chest to capture periscapular muscles as well as an electromyogram with nerve conduction studies. Computed tomography is particularly helpful for skeletal abnormalities. Ultrasound is used to assess certain peripheral nerve injuries and to guide diagnostic and therapeutic injections. A focused evaluation of the scapula followed by a more specific and directed approach for each condition suspected will allow upper extremity surgeons to approach the evaluation of the dysfunctional scapula with much more confidence.

Complications after reverse shoulder arthroplasty for proximal humerus nonunion.

BACKGROUND: Proximal humerus nonunion is a challenging complication of fractures that can be treated surgically with either open reduction internal fixation (ORIF) or reverse total shoulder arthroplasty (RTSA). The few studies published on this subject have shown high rates of complications and revision surgery when RTSA has been performed for proximal humerus nonunion. The purpose of this study was to determine the rates of complications and revision of this procedure at our institution, as well as to identify any variables that may impact risks of complications and reoperations. METHODS: A single-institution retrospective review of all patients who underwent RTSA for proximal humerus nonunion between 2005 and 2021 was performed. Nonunion was defined as imaging evidence of lack of union, at least 90 days after the index fracture. Patients with less than 1 year of clinical follow-up were excluded. Fifty patients were included, with the majority being female (78%). The mean age at time of RTSA was 71 (range: 54-86) years and most patients were initially treated nonoperatively (74%). Mean total follow-up was 49 (range: 11-130) months. Demographic and surgical variables were recorded. Primary outcomes were complications and reoperations. Complications were divided into surgical (those directly related to RTSA), or other (those unrelated to RTSA). Secondary outcomes included visual analog scale pain scores and range of motion. RESULTS: A total of 17 shoulders (34%) sustained complications after revision shoulder arthroplasty, with 10 (20%) requiring reoperation. Six patients (12%) sustained dislocations and 5 (10%) had radiographic evidence of humeral loosening. No variables examined, including nonoperative vs. surgical management of the index fracture, prosthesis type, or management of tuberosities, influenced the risk of dislocation. Survivorship free from reoperation at 2 years was 73%. Younger age at time of RTSA and the presence of diabetes mellitus both increased the risk of reoperation significantly (P = .013 and P = .037, respectively). There was a trend towards increased risk of reoperation in patients who were treated with initial ORIF (hazard ratio = 2.95); however, this did not reach statistical significance (P = .088). Three patients (6%) sustained a periprosthetic fracture after a fall. CONCLUSION: RTSA provides improved pain and function for properly selected patients with proximal humerus nonunion. Dislocation, humeral loosening, and reoperation rates remain high when RTSA is performed for nonunion compared to other diagnoses. In this study, younger age and diabetes mellitus increased the odds of reoperation. Every effort must be made to optimize implant stability and humeral component fixation when RTSA is performed for proximal humerus nonunion.

Operative treatment of acromial and scapular spine fracture nonunions complicating reverse total shoulder arthroplasty.

BACKGROUND: Fractures of the acromion and spine can have a major impact on the outcome of reverse shoulder arthroplasty (RSA) with respect to pain, motion, and function. Reports on internal fixation for these fractures are isolated to small series or case reports with variable outcomes. The purpose of this study was to report on the outcome of open reduction and internal fixation (ORIF) of acromion or spine fractures encountered before or after RSA and describes our evolution of fixation techniques. METHODS: Between 2011 and 2023, 22 fractures or nonunions of the acromion or spine of the scapula underwent ORIF at a single institution and were followed for a minimum of 1 year. In 16 shoulders, fractures occurred after RSA, whereas 5 shoulders underwent ORIF prior to RSA. One shoulder had undergone prior failed ORIF elsewhere and revision ORIF was performed at our institution. There were 10 males and 12 females with a mean age of 67 (SD = 15.1) years. Fixation strategies included single (n = 11) and double plate fixation (n = 11). Kruskal-Wallis one-way analyses of variance were used to analyze continuous variables and Chi-square tests employed for categorical variables. RESULTS: Of the 5 fractures treated with ORIF pre-RSA, 1 shoulder suffered an additional fracture medial to the hardware and 1 required additional bone grafting for incomplete union at the time of RSA. These 5 shoulders all underwent RSA uneventfully, but 1 fracture experienced late displacement of the scapular spine nonunion, leading to plate removal. Of the 16 post-RSA ORIF shoulders, radiographic union was confirmed in 14 and substantial residual inferior angulation identified in 3. New fractures occurred after ORIF in 5 shoulders. For patients who underwent ORIF after RSA, pain scores improved from a mean of 8 to 1.9 points, with more modest elevation gains (58.2°-91.3° pre and postoperatively, respectively). CONCLUSIONS: ORIF of acromion and scapular spine fractures or nonunions in the setting of RSA have the potential to lead to union. When these fractures and nonunions are encountered prior to RSA, ORIF allows for uneventful RSA implantation, but secondary displacement may occur. ORIF seems to lead to improvements in pain, but more modest improvements in motion and function. Our fixation strategy has evolved to (1) dual plating, (2) spanning the whole length of the spine with 1 of the plates, (3) use of hook features under the acromion or os trigonum if possible, and (4) liberal use of bone graft.

Surgical treatment and outcomes of trans-ulnar basal coronoid fracture-dislocations.

BACKGROUND: Trans-ulnar fracture-dislocations of the elbow are complex injuries that can be difficult to classify and treat. Trans-ulnar basal coronoid injuries, in which the coronoid is not attached to either the olecranon or the metaphysis, present substantial challenges to achieve anatomic reduction and stable internal fixation. The purpose of this study was to analyze the outcome of surgical treatment of trans-ulnar basal coronoid fracture-dislocations. MATERIALS AND METHODS: Between 2002 and 2019, 32 consecutive trans-ulnar basal coronoid fracture-dislocations underwent open reduction and internal fixation at our institution. Four elbows were lost to follow-up within the first 6 months after surgery and were excluded. Among the 28 elbows remaining, there were 13 females and 15 males with a mean age of 56 (range 28-78) years at the time of injury. The mean clinical and radiographic follow-up times were 37 months and 29 months, respectively. Radiographs were reviewed to determine rates of union, Hastings and Graham heterotopic ossification (HO) grade, and Broberg and Morrey arthritis grade. RESULTS: Union occurred in 25 elbows. Union could not be determined for 1 elbow at most recent follow-up and the remaining 2 elbows developed nonunion of the coronoid. Complications occurred in 10 elbows (36%): deep infection (4), ulnar neuropathy (2), elbow contracture (2), and nonunion (2). There were reoperations in 11 elbows (39%): irrigation and débridement with hardware removal (4), hardware removal (2), ulnar nerve transposition (2), contracture release with HO removal (2), and revision with iliac crest autograft (1). At most recent follow-up, the mean flexion-extension arc was 106° (range 10°-150°), and the mean pronation-supination arc was 137° (range 0°-170°). The mean Quick Disabilities of Arm, Shoulder, and Hand score was 11 (range 0-39) points with a mean Single Assessment Numeric Evaluation-Elbow score of 81 (range 55-100) points. At final radiographic follow-up, 16 elbows (57%) had HO (8 class I and 8 class II), and 20 elbows (71%) had arthritis (8 grade 1, 6 grade 2, and 6 grade 3). DISCUSSION: Trans-ulnar basal coronoid fracture-dislocations are severe injuries associated with high rates of reoperation, HO, and post-traumatic arthritis. However, the majority of elbows achieve union, a functional range of motion, and reasonable patient reported outcome measures. Over the study period, surgeons were more likely to utilize multiple deep approaches and separate fixation of the coronoid (either with lag screws or anteromedial plates) to ensure anatomic reduction.

Reverse Shoulder Arthroplasty for Proximal Humerus Fractures: A Review of Current Evidence.

PURPOSE OF REVIEW: The aim of this review is to summarize information published in the recent peer-reviewed literature on reverse shoulder arthroplasty (RSA) for proximal humerus fractures. RECENT FINDINGS: Although there is still some debate regarding which may be the best treatment for proximal humerus fractures in certain age ranges, RSA seems to offer more predictable results than other surgical treatments for elderly patients. Successful tuberosity healing seems to correlate with better outcomes. Recent trends indicate interest in cementless fixation, fracture-specific stems and a 135-degree polyethylene opening angle. RSA provides a successful surgical solution for selected proximal humerus fractures. Indications, design features, and surgical execution have continued to evolve over the last few years.

Identification of ChatGPT-Generated Abstracts Within Shoulder and Elbow Surgery Poses a Challenge for Reviewers.

PURPOSE: To evaluate the extent to which experienced reviewers can accurately discern between artificial intelligence (AI)-generated and original research abstracts published in the field of shoulder and elbow surgery and compare this with the performance of an AI detection tool. METHODS: Twenty-five shoulder- and elbow-related articles published in high-impact journals in 2023 were randomly selected. ChatGPT was prompted with only the abstract title to create an AI-generated version of each abstract. The resulting 50 abstracts were randomly distributed to and evaluated by 8 blinded peer reviewers with at least 5 years of experience. Reviewers were tasked with distinguishing between original and AI-generated text. A Likert scale assessed reviewer confidence for each interpretation, and the primary reason guiding assessment of generated text was collected. AI output detector (0%-100%) and plagiarism (0%-100%) scores were evaluated using GPTZero. RESULTS: Reviewers correctly identified 62% of AI-generated abstracts and misclassified 38% of original abstracts as being AI generated. GPTZero reported a significantly higher probability of AI output among generated abstracts (median, 56%; interquartile range [IQR], 51%-77%) compared with original abstracts (median, 10%; IQR, 4%-37%; P < .01). Generated abstracts scored significantly lower on the plagiarism detector (median, 7%; IQR, 5%-14%) relative to original abstracts (median, 82%; IQR, 72%-92%; P < .01). Correct identification of AI-generated abstracts was predominately attributed to the presence of unrealistic data/values. The primary reason for misidentifying original abstracts as AI was attributed to writing style. CONCLUSIONS: Experienced reviewers faced difficulties in distinguishing between human and AI-generated research content within shoulder and elbow surgery. The presence of unrealistic data facilitated correct identification of AI abstracts, whereas misidentification of original abstracts was often ascribed to writing style. CLINICAL RELEVANCE: With rapidly increasing AI advancements, it is paramount that ethical standards of scientific reporting are upheld. It is therefore helpful to understand the ability of reviewers to identify AI-generated content.

Comparison of reconstructive techniques for nonprimary malignancies in the proximal humerus.

BACKGROUND: Endoprostheses (EPC) are often utilized for reconstruction of the proximal humerus with either hemiarthroplasty (HA) or reverse arthroplasty (RA) constructs. RA constructs have improved outcomes in patients with primary lesions, but no studies have compared techniques in metastatic disease. The aim of this study is to compare functional outcomes and complications between HA and RA constructs in patients undergoing endoprosthetic reconstruction for proximal humerus metastases. METHODS: We retrospectively reviewed our institutional arthroplasty database to identify 66 (56% male; 38 HA and 28 RA) patients with a proximal humerus reconstruction for a non-primary malignancy. The majority (88%) presented with pathologic fracture, and the most common diagnosis was renal cell carcinoma (48%). RESULTSS: Patients with RA reconstructions had better postoperative forward elevation (74° vs. 32°, p < 0.01) and higher functional outcome scores. HA patients had more complications (odds ratio 13, p < 0.01), with instability being the most common complication. CONCLUSIONS: Patients with nonprimary malignancies of the proximal humerus had improved functional outcomes and fewer complications after undergoing reconstruction with a reverse EPC compared to a HA EPC. Preference for reverse EPC should be given in patients with good prognosis and ability to complete postoperative rehabilitation.

Supracondylar ostectomy and shortening (S.O.S.) for distal humerus nonunions.

BACKGROUND: Many distal humerus nonunions are associated with bone loss, and rigid internal fixation is difficult to obtain, especially for low transcondylar nonunions and those with severe intra-articular comminution. The purpose of this study was to analyze the results of a strategy to address this challenge utilizing internal fixation using the Supracondylar Ostectomy + Shortening (S.O.S.) procedure for distal humerus nonunions. The goals of this procedure are to (1) optimize bony contact and compression through re-shaping the nonunited fragments at the supracondylar level with selective humeral metaphyseal shortening, (2) maximize fixation using parallel-plating, and (3) provide biologic and structural augmentation with bone graft. MATERIALS AND METHODS: Between 1995 and 2019, 28 distal humerus nonunions underwent internal fixation using the S.O.S. procedure at a single Institution. There were 14 males and 14 females with mean age of 47 (range 14-78) years at the time of the S.O.S procedure and an average of 1.7 prior surgeries. Medical records and radiographs were reviewed to determine rates of union, reoperations, complications, and Mayo Elbow Performance Scores (MEPS). Patients were also prospectively contacted to update their MEPS and gather additional information on complications and reoperations. Mean clinical exam follow-up was 17 months, mean clinical contact follow-up was 19 months, and mean radiographic follow-up was 32 months. RESULTS: Four patients did not have adequate follow-up to determine union. Of the remaining 24 elbows, 22 achieved union. Two elbows developed collapse of the articular surface and were converted to a total elbow arthroplasty. There were complications in 10 elbows: contracture (5), superficial infection (2), ulnar neuropathy (1), deep infection (1), and hematoma (1). Twelve elbows underwent reoperation: 4 for contracture release, 3 for hardware removal, 2 for total elbow arthroplasty, 1 for bone grafting, 1 for hematoma evacuation, and 1 for ulnar nerve neurolysis. Compared to preoperative data, there was a significant improvement in postoperative flexion, extension and pronation (P < .01). The mean range of motion was 21° of extension, 119° of flexion, 79° of pronation, and 77° of supination. The mean MEPS was 80 points (range, 25-100 points) and 19 elbows (76%) rated as excellent or good. DISCUSSION: Stable fixation and high union rates are possible in distal humerus nonunions with bone loss using a technique that combines supracondylar humeral shortening, parallel plating, and bone grafting. Secondary procedures are commonly needed to restore function in this challenging patient population.

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.

After primary shoulder arthroplasty appropriate vancomycin antibiotic prophylaxis does not lead to increased infectious complications when compared to cefazolin.

BACKGROUND: In primary shoulder arthroplasty (SA), intravenous (IV) cefazolin has demonstrated lower rates of infectious complications when compared to IV vancomycin. However, previous analyses included SA cohorts with both complete and incomplete vancomycin administration. Therefore, it is currently unclear whether cefazolin still maintains a prophylactic advantage to vancomycin when it is appropriately indicated and sufficiently administered at the time of surgical incision. This study evaluated the comparative efficacy of cefazolin and complete vancomycin administration for surgical prophylaxis in primary shoulder arthroplasty with respect to infectious complications. METHODS: A retrospective cohort study was conducted utilizing a single institution total joint registry database, where all primary SA types (hemiarthroplasty, anatomic total shoulder arthroplasty, and reverse shoulder arthroplasty) performed between 2000 to 2019 for elective and trauma indications using IV cefazolin or complete vancomycin administration as the primary antibiotic prophylaxis were identified. Vancomycin was primarily indicated for patients with a severe self-reported penicillin or cephalosporin allergy and/or MRSA colonization. Complete administration was defined as at least 30 minutes of antibiotic infusion prior to incision. All included SA had at least 2 years of clinical follow-up. Multivariable Cox proportional hazard regression was used to evaluate all-cause infectious complications including survival free of prosthetic joint infection (PJI). RESULTS: The final cohort included 7177 primary SA, 6879 (95.8%) received IV cefazolin and 298 (4.2%) received complete vancomycin administration. Infectious complications occurred in 120 (1.7%) SA leading to 81 (1.1%) infectious reoperations. Of the infectious complications, 41 (0.6%) were superficial infections and 79 were (1.1%) PJIs. When categorized by administered antibiotics, there were no differences in rates of all infectious complications (1.6% vs. 2.3%; P = .352), superficial complications (0.5% vs. 1.3%; P = .071), PJI (1.1% vs. 1.0%; P = .874), or infectious reoperations (1.1% vs. 1.0%; P = .839). On multivariable analyses, complete vancomycin infusion demonstrated no difference in rates of infectious complications compared to cefazolin administration (hazard ratio [HR], 1.50 [95% confidence interval (CI), 0.70 to 3.25]; P = .297), even when other independent predictors of PJI (male sex, prior surgery, and Methicillin-resistant Staphylococcus aureus colonization) were considered. CONCLUSIONS: In comparison to cefazolin, complete administration of vancomycin (infusion to incision time greater than 30 minutes) as the primary prophylactic agent does not adversely increase the rates of infectious complications and PJI. Prophylaxis protocols should promote appropriate indications for the use of cefazolin or vancomycin, and when necessary, ensure complete administration of vancomycin to mitigate additional infectious risks after primary SA.

Complications of antibiotic cement spacers used for elbow infections.

BACKGROUND: Antibiotic cement spacers have been widely used in the treatment of joint infections. There are no commercially available antibiotic spacers for the elbow. Instead, they are typically fashioned by the surgeon at the time of surgery using cement alone or a combination of cement with sutures, Steinmann pins, external fixator components, or elbow arthroplasty components. There is no consensus regarding the ideal elbow antibiotic spacer and no previous studies have examined the complications associated with these handmade implants in relation to their unique structural design. METHODS: We retrospectively reviewed 55 patients who had 78 static antibiotic cement spacers implanted between January 1998 and February 2021 as part of a 2-stage treatment plan for infection of an elbow arthroplasty, other elbow surgery, or primary elbow infection. Several antibiotic spacer structures were used during the study period. For analysis purposes, the spacers were classified into linked and unlinked spacers based on whether there was a linking mechanism between the humerus and the ulna. Complications related to these spacers that occurred either during the implantation, between implantation and removal, or during removal were recorded and analyzed from chart review and follow-up x rays. Reoperations due to spacer-related complications were also recorded. RESULTS: Among the 55 patients (78 spacers), there were 23 complications, including 17 minor and 6 major complications. The most common complication of unlinked spacers (intramedullary [IM] dowels, beads and cap spacer) was spacer displacement. Other complications included IM dowel fracture and difficulty locating beads during spacer removal. The major complications of linked cement spacers included two periprosthetic humerus fractures after internal external fixator cement spacers and re-operation due to breakage and displacement of one bushing cement spacer. The major complications of unlinked cement spacers included two reoperations due to IM dowel displacement and one reoperation due to displacement of beads. Among patients who had removal of all components and those with native joints, there was no statistically significant difference between internal external fixator cement spacers and unlinked cement spacers in minor complication rates (30% vs. 16%, P = .16), major complication rates (7% vs. 8%, P = .85) and reoperation rates (0% vs. 8%, P = .12). CONCLUSIONS: Static handmade antibiotic elbow spacers have unique complications related to their structural designs. The most common complication of linked and nonlinked cement spacers were failure of the linking mechanism and displacement, respectively. Surgeons should keep in mind the possible complications of different structures of cement spacers when choosing 1 antibiotic spacer structure over another.

Efficacy of ADIPOR1 and ADIPOR2 peptide-agonist AdipoRon in preventing contracture in a rabbit model of arthrofibrosis.

AdipoRon is an adiponectin receptor 1, 2 (ADIPOR1 and ADIPOR2) agonist with potential antifibrotic effects. Whether AdipoRon can mitigate joint stiffness in a rabbit model of arthrofibrosis is unknown. We examined the efficacy of intravenous (IV) AdipoRon at mitigating contracture in a rabbit model of knee arthrofibrosis. Fifty-six female New Zealand White rabbits were divided into three dosing groups: vehicle (dimethyl sulfoxide, DMSO), 2.5 mg/kg AdipoRon, and 5 mg/kg AdipoRon. AdipoRon, in DMSO, was administered IV preoperatively and for 5 days postoperatively (30 rabbits, Aim 1). AdipoRon was again dosed similarly after Kirschner wire (K-wire) removal at 8 weeks (26 rabbits; Aim 2). The primary outcome of joint passive extension angle (PEA,°) was measured at 8, 10, 12, 16, and 24 weeks following index surgery. At 24 weeks, rabbits were euthanized and limbs were harvested to measure posterior capsular stiffness (N cm/°). In Aim 1, the 5 mg/kg treated rabbits had a significant increase in PEA when compared to controls at 16-week (p < 0.05). In Aim 2, the 5 mg/kg treated rabbits had a significant increase in PEA when compared to controls at 10-week (p < 0.05). In both aims, no significant differences were observed at later time points. Capsular stiffness was no different in any group. We are the first to report the efficacy of IV AdipoRon in a rabbit model of arthrofibrosis. We identified a significant dose-dependent decrease in joint PEA at early time points; however, no differences were observed between groups at later time points. Clinical Significance: The present investigation provided the first assessment of AdipoRon's efficacy in mitigating knee stiffness in the current gold standard rabbit model of arthrofibrosis. Results of this investigation provided further evidence as to the potential role of AdipoRon as a preventative for arthrofibrosis in large mammals.

Proximal Humerus Reconstruction for Bone Sarcomas: A Critical Analysis.

¼ The proximal humerus is a common location for primary bone tumors, and the goal of surgical care is to obtain a negative margin resection and subsequent reconstruction of the proximal humerus to allow for shoulder function.¼ The current evidence supports the use of reverse total shoulder arthroplasty over hemiarthroplasty when reconstructing the proximal humerus after resection of a bone sarcoma if the axillary nerve can be preserved.¼ There is a lack of high-quality data comparing allograft prosthetic composite (APC) with endoprosthetic reconstruction of the proximal humerus.¼ Reverse APC should be performed using an allograft with donor rotator cuff to allow for soft-tissue repair of the donor and host rotator cuff, leading to improvements in shoulder motion compared with an endoprosthesis.

A practical guide to the development and deployment of deep learning models for the orthopaedic surgeon: Part III, focus on registry creation, diagnosis, and data privacy.

Deep learning is a subset of artificial intelligence (AI) with enormous potential to transform orthopaedic surgery. As has already become evident with the deployment of Large Language Models (LLMs) like ChatGPT (OpenAI Inc.), deep learning can rapidly enter clinical and surgical practices. As such, it is imperative that orthopaedic surgeons acquire a deeper understanding of the technical terminology, capabilities and limitations associated with deep learning models. The focus of this series thus far has been providing surgeons with an overview of the steps needed to implement a deep learning-based pipeline, emphasizing some of the important technical details for surgeons to understand as they encounter, evaluate or lead deep learning projects. However, this series would be remiss without providing practical examples of how deep learning models have begun to be deployed and highlighting the areas where the authors feel deep learning may have the most profound potential. While computer vision applications of deep learning were the focus of Parts I and II, due to the enormous impact that natural language processing (NLP) has had in recent months, NLP-based deep learning models are also discussed in this final part of the series. In this review, three applications that the authors believe can be impacted the most by deep learning but with which many surgeons may not be familiar are discussed: (1) registry construction, (2) diagnostic AI and (3) data privacy. Deep learning-based registry construction will be essential for the development of more impactful clinical applications, with diagnostic AI being one of those applications likely to augment clinical decision-making in the near future. As the applications of deep learning continue to grow, the protection of patient information will become increasingly essential; as such, applications of deep learning to enhance data privacy are likely to become more important than ever before. Level of Evidence: Level IV.

Reverse shoulder arthroplasty megaprosthesis for surgical management of severe proximal humeral bone loss.

BACKGROUND: Shoulder arthroplasty in the setting of severe proximal humerus bone loss can be challenging. The purpose of this study was to evaluate the outcomes of a modular segmental megaprosthesis when implanted in a reverse configuration for complex primary arthroplasty, reconstruction at the time of oncologic resection, and revision shoulder arthroplasty. MATERIALS AND METHODS: A Joint Registry Database was queried to identify all shoulder arthroplasties performed at a single institution using the Comprehensive Segmental Revision System reverse shoulder arthroplasty (SRS-RSA; Zimmer Biomet). A retrospective review of electronic medical records and radiographs was performed to record demographic data, indication, outcomes, complications, and revision surgery. RESULTS: Between February 2012 and October 2022, a total of 76 consecutive SRS-RSAs were implanted. An analysis of patients with minimum 12-month follow-up yielded 53 patients with a mean follow-up of 4.1 ± 2.43 years. Surgical complication rate in this cohort was observed in 41.5% (22 of 53) of cases. Overall, the revision rate at final follow-up was 26.4% (14 of 53), with a significant difference between the primary and revision cohorts. The number of prior surgeries was a significant risk factor for revision surgery, with a hazard ratio of 1.789 (95% confidence interval 1.314-2.436, P < .001). When analyzing aseptic humeral loosening rates across study cohorts, a significant difference was found between the primary arthroplasty (0%, n = 0) and the revision arthroplasty cohorts (22.2%, n = 6) (P = .04). DISCUSSION: Reverse shoulder arthroplasty using a modular segmental megaprosthesis remains a reasonable salvage option for shoulder reconstruction in the setting of proximal humeral bone loss. Because of the substantial bone loss and soft tissue deficiencies typically present in these cases, surgeons should educate patients on the relatively high complication rate, particularly when used in the setting of a previous failed arthroplasty.

Rotator cuff tears.

Rotator cuff tears are the most common upper extremity condition seen by primary care and orthopaedic surgeons, with a spectrum ranging from tendinopathy to full-thickness tears with arthritic change. Some tears are traumatic, but most rotator cuff problems are degenerative. Not all tears are symptomatic and not all progress, and many patients in whom tears become more extensive do not experience symptom worsening. Hence, a standard algorithm for managing patients is challenging. The pathophysiology of rotator cuff tears is complex and encompasses an interplay between the tendon, bone and muscle. Rotator cuff tears begin as degenerative changes within the tendon, with matrix disorganization and inflammatory changes. Subsequently, tears progress to partial-thickness and then full-thickness tears. Muscle quality, as evidenced by the overall size of the muscle and intramuscular fatty infiltration, also influences symptoms, tear progression and the outcomes of surgery. Treatment depends primarily on symptoms, with non-operative management sufficient for most patients with rotator cuff problems. Modern arthroscopic repair techniques have improved recovery, but outcomes are still limited by a lack of understanding of how to improve tendon to bone healing in many patients.