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.

INTRODUCTION: 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 intraarticular 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 (i.e. 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 (TEA). 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<0.01). 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 to 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.

Non-cefazolin antibiotic prophylaxis is associated with higher rates of elbow periprosthetic joint infection.

BACKGROUND: Periprosthetic joint infection (PJI) is a common source of failure following elbow arthroplasty. Perioperative prophylactic antibiotics are considered standard of care. However, there are no data regarding the comparative efficacy of various antibiotics in the prevention of PJI for elbow arthroplasty. Previous studies in shoulder, hip, and knee arthroplasty have demonstrated higher rates of PJI with administration of non-cefazolin antibiotics. The elbow has higher rates of PJI than other joints. Therefore, this study evaluated whether perioperative antibiotic choice affects rates of PJI in elbow arthroplasty. MATERIALS AND METHODS: A single-institution, prospectively collected total joint registry database was queried to identify patients who underwent primary elbow arthroplasty between 2003 and 2021. Elbows with known infection prior to arthroplasty (25) and procedures with incomplete perioperative antibiotic data (7) were excluded, for a final sample size of 603 total elbow arthroplasties and 19 distal humerus hemiarthroplasties. Cefazolin was administered in 561 elbows (90%) and non-cefazolin antibiotics including vancomycin (32 elbows, 5%), clindamycin (27 elbows, 4%), and piperacillin/tazobactam (2 elbows, 0.3%) were administered in the remaining 61 elbows (10%). Univariate and multivariate analyses were conducted to determine the association between the antibiotic administered and the development of PJI. Infection-free survivorship was estimated using the Kaplan-Meier method. RESULTS: Deep infection occurred in 47 elbows (7.5%), and 16 elbows (2.5%) were diagnosed with superficial infections. Univariate analysis demonstrated that patients receiving non-cefazolin alternatives were at significantly higher risk for any infection (hazard ratio [HR] 2.6, 95% confidence interval [CI] 1.4-5.0; P < .01) and deep infection (HR 2.7, 95% CI 1.3-5.5; P < .01) compared with cefazolin administration. Multivariable analysis, controlling for several independent predictors of PJI (tobacco use, male sex, surgical indication other than osteoarthritis, and American Society of Anesthesiologists score), showed that non-cefazolin administration had a higher risk for any infection (HR 2.8, 95% CI 1.4-5.3; P < .01) and deep infection (HR 2.9, 95% CI 1.3-6.3; P < .01). Survivorship free of infection was significantly higher at all time points for the cefazolin cohort. DISCUSSION: In primary elbow arthroplasty, cefazolin administration was associated with significantly lower rates of PJI compared to non-cefazolin antibiotics, even in patients with a greater number of prior surgeries, which is known to increase the risk of PJI. For patients with penicillin or cephalosporin allergies, preoperative allergy testing or a cefazolin test dose should be considered before administering non-cefazolin alternatives.

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.

INTRODUCTION: Technological advancements in implant design and surgical technique have focused on diminishing complications and optimizing performance of reverse shoulder arthroplasty (RSA). 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 RSA. METHODS: Over a 16-year period (2004 - 2020), all primary RSA 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 (NSA), and polyethylene NSA. Machine learning models predicting surgical complications were constructed for each patient and Shapley additive explanation (SHAP) values were calculated to quantify feature importance. RESULTS: A total of 3,837 RSAs 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 non-union (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 RSA with an area under the receiver operating characteristic curve (AUC ROC) 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 RSA. 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.

INTRODUCTION: 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, 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 7,177 primary SA, 6,879 (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.

Trans-ulnar fracture dislocations of the elbow: a systematic review and clarification of classification systems.

BACKGROUND: Complex elbow dislocations in which the dorsal cortex of the ulna is fractured can be difficult to classify and therefore treat. These have variably been described as either Monteggia variant injuries or trans-olecranon fracture dislocations. Additionally, O'Driscoll et al classified coronoid fractures that exit the dorsal cortex of the ulna as "basal coronoid, subtype 2" fractures. The Mayo classification of trans-ulnar fracture dislocations categorizes these injuries in 3 types according to what the coronoid remains attached to: trans-olecranon fracture dislocations, Monteggia variant fracture dislocations, and trans-ulnar basal coronoid fracture dislocations. The purpose of this study was to evaluate the outcomes of these injury patterns as reported in the literature. Our hypothesis was that trans-ulnar basal coronoid fracture dislocations would have a worse prognosis. MATERIALS AND METHODS: We conducted a systematic review to identify studies with trans-ulnar fracture dislocations that had documentation of associated coronoid injuries. A literature search identified 16 qualifying studies with 296 fractures. Elbows presenting with basal subtype 2 or Regan/Morrey III coronoid fractures and Jupiter IIA and IID injuries were classified as trans-ulnar basal coronoid fractures. Patients with trans-olecranon or Monteggia fractures were classified as such if the coronoid was not fractured or an associated coronoid fracture had been classified as O'Driscoll tip, anteromedial facet, basal subtype I, or Regan Morrey I/II. RESULTS: The 296 fractures reviewed were classified as trans-olecranon in 44 elbows, Monteggia variant in 82 elbows, and trans-ulnar basal coronoid fracture dislocations in 170 elbows. Higher rates of complications and reoperations were reported for trans-ulnar basal coronoid injuries (40%, 25%) compared to trans-olecranon (11%, 18%) and Monteggia variant injuries (25%, 13%). The mean flexion-extension arc for basal coronoid fractures was 106° compared to 117° for Monteggia (P < .01) and 121° for trans-olecranon injuries (P = .02). The mean Mayo Elbow Performance Score was 84 points for trans-ulnar basal coronoid, 91 for Monteggia (P < .01), and 93 for trans-olecranon fracture dislocations (P < .05). Disabilities of the Arm, Shoulder and Hand and American Shoulder and Elbow Surgeons scores were 22 and 80 for trans-ulnar basal coronoid, respectively, compared to 23 and 89 for trans-olecranon fractures. American Shoulder and Elbow Surgeons was not available for any Monteggia injuries, but the mean Disabilities of the Arm, Shoulder and Hand was 13. DISCUSSION: Trans-ulnar basal coronoid fracture dislocations are associated with inferior patient reported outcome measures, decreased range of motion, and increased complication rates compared to trans-olecranon or Monteggia variant fracture dislocations. Further research is needed to determine the most appropriate treatment for this difficult injury pattern.

Invariant NKT cells metabolically adapt to the acute myeloid leukaemia environment.

Acute myeloid leukaemia (AML) creates an immunosuppressive environment to conventional T cells through Arginase 2 (ARG2)-induced arginine depletion. We identify that AML blasts release the acute phase protein serum amyloid A (SAA), which acts in an autocrine manner to upregulate ARG2 expression and activity, and promote AML blast viability. Following in vitro cross-talk invariant natural killer T (iNKT) cells become activated, upregulate mitochondrial capacity, and release IFN-γ. iNKT retain their ability to proliferate and be activated despite the low arginine AML environment, due to the upregulation of Large Neutral Amino Acid Transporter-1 (LAT-1) and Argininosuccinate Synthetase 1 (ASS)-dependent amino acid pathways, resulting in AML cell death. T cell proliferation is restored in vitro and in vivo. The capacity of iNKT cells to restore antigen-specific T cell immunity was similarly demonstrated against myeloid-derived suppressor cells (MDSCs) in wild-type and Jα18-/- syngeneic lymphoma-bearing models in vivo. Thus, stimulation of iNKT cell activity has the potential as an immunotherapy against AML or as an adjunct to boost antigen-specific T cell immunotherapies in haematological or solid cancers.

Platelet-Rich Plasma and Marrow Venting May Serve as Cost-Effective Augmentation Techniques for Isolated Meniscal Repair: A Decision-Analytical Markov Model-Based Analysis.

PURPOSE: To evaluate the cost-effectiveness of 3 isolated meniscal repair (IMR) treatment strategies: platelet-rich plasma (PRP)-augmented IMR, IMR with a marrow venting procedure (MVP), and IMR without biological augmentation. METHODS: A Markov model was developed to evaluate the baseline case: a young adult patient meeting the indications for IMR. Health utility values, failure rates, and transition probabilities were derived from the published literature. Costs were determined based on the typical patient undergoing IMR at an outpatient surgery center. Outcome measures included costs, quality-adjusted life-years (QALYs), and the incremental cost-effectiveness ratio (ICER). RESULTS: Total costs of IMR with an MVP were $8,250; PRP-augmented IMR, $12,031; and IMR without PRP or an MVP, $13,326. PRP-augmented IMR resulted in an additional 2.16 QALYs, whereas IMR with an MVP produced slightly fewer QALYs, at 2.13. Non-augmented repair produced a modeled gain of 2.02 QALYs. The ICER comparing PRP-augmented IMR versus MVP-augmented IMR was $161,742/QALY, which fell well above the $50,000 willingness-to-pay threshold. CONCLUSIONS: IMR with biological augmentation (MVP or PRP) resulted in a higher number of QALYs and lower costs than non-augmented IMR, suggesting that biological augmentation is cost-effective. Total costs of IMR with an MVP were significantly lower than those of PRP-augmented IMR, whereas the number of additional QALYs produced by PRP-augmented IMR was only slightly higher than that produced by IMR with an MVP. As a result, neither treatment dominated over the other. However, because the ICER of PRP-augmented IMR fell well above the $50,000 willingness-to-pay threshold, IMR with an MVP was determined to be the overall cost-effective treatment strategy in the setting of young adult patients with isolated meniscal tears. LEVEL OF EVIDENCE: Level III, economic and decision analysis.

Improved Yet Varied Clinical Outcomes Observed With Comparison of Arthroscopic Superior Capsular Reconstruction Versus Arthroscopy-Assisted Lower Trapezius Transfer for Patients With Irreparable Rotator Cuff Tears.

PURPOSE: To evaluate the outcomes of arthroscopic superior capsular reconstruction (SCR) and arthroscopy-assisted lower trapezius tendon transfer (LTT) for posterosuperior irreparable rotator cuff tears (IRCTs). METHODS: Over an almost 6-year period (October 2015 to March 2021), all patients who underwent IRCT surgery with a minimum 12-month follow-up period were identified. For patients with a substantial active external rotation (ER) deficit or lag sign, LTT was preferentially selected. Patient-reported outcome scores included the visual analog scale (VAS) pain score, strength score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score, Single Assessment Numeric Evaluation (SANE) score, and Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) score. RESULTS: We included 32 SCR patients and 72 LTT patients. Preoperatively, LTT patients had more advanced teres minor fatty infiltration (0.3 vs 1.1, P = .009), a higher global fatty infiltration index (1.5 vs 1.9, P = .035), and a higher presence of the ER lag sign (15.6% vs 48.6%, P < .001). At a mean follow-up of 2.9 ± 1.3 years (range, 1.0-6.3 years), no differences in patient-reported outcome scores were observed. Postoperatively, SCR patients had a lower VAS score (0.3 vs 1.1, P = .017), higher forward elevation (FE) (156° vs 143°, P = .004), and higher FE strength (4.8 vs 4.5, P = .005) and showed greater improvements in the VAS score (6.8 vs 5.1, P = .009), FE (56° vs 31°, P = .004), and FE strength (1.0 vs 0.4, P < .001). LTT patients showed greater improvement in ER (17° vs 29°, P = .026). There was no statistically significant between-cohort difference in complication rate (9.4% vs 12.5%, P = .645) or reoperation rate (3.1% vs 10%, P = .231). CONCLUSIONS: With adequate selection criteria, both SCR and LTT provided improved clinical outcomes for posterosuperior IRCTs. Additionally, SCR led to better pain relief and restoration of FE whereas LTT provided more reliable improvement in ER. LEVEL OF EVIDENCE: Level III, treatment study with retrospective cohort comparison.

Virtual surgical planning and mirrored, 3-dimensionally printed guides for corrective clavicle osteotomies in clavicle malunions and nonunions.

BACKGROUND: The objective of this study was to retrospectively review clinical and radiographic outcomes of patients who underwent corrective osteotomies for clavicle malunion and internal fixation for nonunion using a combination of virtual surgical planning, patient-specific 3-dimensional (3D)-printed clavicles, and 3D-printed cutting guides manufactured at the point of care. METHODS: Between 2015 and 2021, 18 patients underwent corrective osteotomy for a clavicle malunion (7 shoulders) or internal fixation for a clavicle nonunion (11 shoulders). There were 11 male and 7 female individuals with an average patient age of 43.9 (range 19-76) years. All patients underwent computed tomography evaluation of both clavicles. The DICOM files were manually segmented, virtual surgical planning was performed selectively using commercially available software, and a mirrored version of the normal clavicle was 3D printed along with a 3D-printed replica of the affected clavicle. Three-dimensionally printed mirrored clavicles were used in all cases to ensure adequate restoration of the shape and length of the clavicle and to precontour fixation plates. Virtual surgical planning and 3D-printed cutting guides for osteotomy were used in 4 of 18 (22%) patients. Either cancellous or structural intercalary bone grafting was used in 15 of 18 (83%) cases. Patients were contacted postoperatively to determine clinical outcome scores. Preoperative, early postoperative, and late postoperative radiographs were reviewed to assess for union and complications. The average follow-up time was 24.9 months. RESULTS: Radiographic evaluation at the most recent follow-up demonstrated adequate restoration of length and successful union for all shoulders. There were no complications or reoperations. Postoperative patient-reported outcomes could be obtained in 16 of 18 (88.9%) patients. At the most recent follow-up, the mean visual analog scale for pain was 2.38 points (range, 1-7), the mean shoulder American Shoulder and Elbow Surgeons score was 73.2 points (range, 25-100), and the mean Patient-Reported Outcome Measurement Information System Upper Extremity score was 26 points (range, 7-35). All (100%) the patients were satisfied with their outcome (9 very satisfied, 7 satisfied), and their mean subjective shoulder value was 73% (range, 10%-100%). However, 2 patients complained of hardware-related symptoms, and 1 patient had return of preoperative symptoms after an interim 2 years of pain relief. CONCLUSION: The use of mirrored 3D-printed clavicles combined with virtual surgical planning and patient-specific 3D guides provides a reliable technique for restoring native anatomy when performing corrective osteotomies for clavicle malunion or internal fixation for clavicle nonunion, with a high rate of satisfactory clinical and radiographic outcomes.

Shoulder arthroplasty after prior external beam radiation therapy: a matched cohort analysis.

BACKGROUND: External beam radiation therapy (XRT) is a commonly used therapeutic modality for the treatment of various chest wall and axillary malignancies. Despite the known risk of local soft tissue dysfunction, and possibly compromised bone ingrowth for cementless implants, there remains limited data on the impact of prior XRT in a shoulder arthroplasty (SA) cohort. This study evaluated the outcomes of primary SA in patients with prior XRT compared to a matched cohort (MC). METHODS: Over a 27-year time period (1993-2020), 80 primary SAs (7 hemiarthroplasties [HAs], 29 anatomic total shoulder arthroplasties [aTSAs], and 44 reverse shoulder arthroplasties [rTSAs]) with previous XRT to the upper chest or axillary region and a minimum of 2-year follow-up were included. This cohort was matched (1:2) according to age, sex, body mass index (BMI), implant, and year of surgery with patients who had undergone HA or TSA for osteoarthritis or RSA for cuff tear arthropathy. Clinical outcomes including pain, active shoulder range of motion (ROM), strength, complications, and reoperations inclusive of revision surgery were assessed. RESULTS: The XRT cohort consisted of 71 (88.8%) women with a mean age of 70.9 (range, 43-87) years, BMI of 30.9 ± 7.6, and follow-up period of 6.6 years (range, 2.0-28.2). In these patients, SA led to substantial improvements in pain, ROM, and strength across the entire cohort. When compared to the MC, the XRT group demonstrated a lower final postoperative forward elevation (FE) (111° vs. 126°; P = .013) and less improvements in pain (5.3 vs. 6.2; P = .002), FE (34° vs. 54°; P = .002), and external rotation (13° vs. 24°; P < .001). There were 14 (17.5%) complications and 7 reoperations in the XRT group, with rotator cuff failure after HA or TSA (n = 4 of 36; 11.1%) as the most common complication and no instances of loose humeral components. The XRT group had a higher rate of complications (17.5% vs. 8.1%; P = .03) but not reoperations (8.8% vs. 3.1%; P = .059). When evaluated by implant, rTSA demonstrated the lowest rate of reoperations followed by aTSA and HA (2.3% vs. 10.3% vs. 42.9%; P = .002). CONCLUSIONS: Primary SA is an effective treatment modality for the improvement of pain, motion, and strength in patients with a history of prior XRT. However, when compared to patients without prior XRT, less clinical improvement and a higher rate of postoperative complications were observed.

Computed tomography provides effective detection of traumatic arthrotomy of the elbow.

BACKGROUND: Failure to identify a traumatic arthrotomy of the elbow (TAE) can lead to septic arthritis with devastating complications. The gold standard for TAE detection remains controversial, and evidence is limited. While multiple clinical and cadaveric studies have validated the use of computed tomography (CT) to detect traumatic arthrotomies about the knee, other studies have called into question whether the use of CT to detect traumatic arthrotomy is applicable to the elbow. A prior cadaveric study utilizing a direct posterior (transtendon) traumatic arthrotomy model failed to detect traumatic arthrotomy via CT in 100% of cases. The aim of this study was to determine the sensitivity and specificity for detecting TAE with CT, utilizing a lateral traumatic arthrotomy model. METHODS: Ten fresh-frozen upper extremity transhumeral cadaveric specimens were utilized. Only specimens with an intact elbow joint and no known elbow surgery or injury were included. CT scans were performed to screen for intra-articular air prior to arthrotomy. A full-thickness 10 mm incision was performed over the soft spot, just distal to the lateral epicondyle. The elbow was taken through full range of motion in flexion and extension, as well as forearm pronation and supination 10 times. CT scans were then repeated and screened for the presence of intra-articular air. Lastly, a saline load test was performed on all specimens, and the volume of saline required to detect the arthrotomy was recorded. RESULTS: Of the 10 specimens, 0% (n = 0) demonstrated intra-articular air of the elbow joint on CT scan prior to arthrotomy and 100% (n = 10) demonstrated intra-articular air on CT scan following arthrotomy. CT scan demonstrated 100% sensitivity and 100% specificity for TAE. For the saline load test, 90% (n = 9) were positive for TAE at an average of 12 mL (range: 4 mL-47 mL), providing 90% sensitivity. CONCLUSION: In this cadaveric study utilizing a more commonly observed direct lateral traumatic laceration, CT was able to detect 100% (n = 10) of TAEs with 100% sensitivity and specificity. These results show that CT scans can effectively diagnose lateral traumatic arthrotomy in a cadaveric model and can be a viable option for diagnosis in a clinical setting. Clinical correlation is required to confirm in these in vitro findings.

Understanding risk for early dislocation resulting in reoperation within 90 days of reverse total shoulder arthroplasty: extreme rare event detection through cost-sensitive machine learning.

BACKGROUND: Reliable prediction of postoperative dislocation after reverse total shoulder arthroplasty (RSA) would inform patient counseling as well as surgical and postoperative decision making. Understanding interactions between multiple risk factors is important to identify those patients most at risk of this rare but costly complication. To better understand these interactions, a game theory-based approach was undertaken to develop machine learning models capable of predicting dislocation-related 90-day readmission following RSA. MATERIAL & METHODS: A retrospective review of the Nationwide Readmissions Database was performed to identify patients who underwent RSA between 2016 and 2018 with a subsequent readmission for prosthetic dislocation. Of the 74,697 index procedures included in the data set, 740 (1%) experienced a dislocation resulting in hospital readmission within 90 days. Five machine learning algorithms were evaluated for their ability to predict dislocation leading to hospital readmission within 90 days of RSA. Shapley additive explanation (SHAP) values were calculated for the top-performing models to quantify the importance of features and understand variable interaction effects, with hierarchical clustering used to identify cohorts of patients with similar risk factor combinations. RESULTS: Of the 5 models evaluated, the extreme gradient boosting algorithm was the most reliable in predicting dislocation (C statistic = 0.71, F2 score = 0.07, recall = 0.84, Brier score = 0.21). SHAP value analysis revealed multifactorial explanations for dislocation risk, with presence of a preoperative humerus fracture; disposition involving discharge or transfer to a skilled nursing facility, intermediate care facility, or other nonroutine facility; and Medicaid as the expected primary payer resulting in strong, positive, and unidirectional effects on increasing dislocation risk. In contrast, factors such as comorbidity burden, index procedure complexity and duration, age, sex, and presence or absence of preoperative glenohumeral osteoarthritis displayed bidirectional influences on risk, indicating potential protective effects for these variables and opportunities for risk mitigation. Hierarchical clustering using SHAP values identified patients with similar risk factor combinations. CONCLUSION: Machine learning can reliably predict patients at risk for postoperative dislocation resulting in hospital readmission within 90 days of RSA. Although individual risk for dislocation varies significantly based on unique combinations of patient characteristics, SHAP analysis revealed a particularly at-risk cohort consisting of young, male patients with high comorbidity burdens who are indicated for RSA after a humerus fracture. These patients may require additional modifications in postoperative activity, physical therapy, and counseling on risk-reducing measures to prevent early dislocation after RSA.

A coronoid-centric classification system of proximal trans-ulnar fracture-dislocations has almost perfect intraobserver and interobserver agreement.

BACKGROUND: Fracture-dislocations of the elbow, particularly those that involve a fracture through the proximal ulna, are complex and can be difficult to manage. Moreover, current classification systems often cannot discriminate between Monteggia-variant injury patterns and trans-olecranon fracture-dislocations, particularly when the fracture involves the coronoid. The Mayo classification of proximal trans-ulnar fracture-dislocations categorizes these fractures into 3 types according to what the coronoid is still attached to: trans-olecranon fracture-dislocations (the coronoid is still attached to the ulnar metaphysis); Monteggia-variant fracture-dislocations (the coronoid is still attached to the olecranon); and ulnar basal coronoid fracture-dislocations (the coronoid is not attached to either the olecranon or the ulnar metaphysis). The purpose of this study was to evaluate the intraobserver and interobserver agreement of the Mayo classification system when assessing elbow fracture-dislocations involving the proximal ulna based on radiographs and computed tomography scans. METHODS: Three fellowship-trained shoulder and elbow surgeons and 2 fellowship-trained orthopedic trauma surgeons blindly and independently evaluated the radiographs and computed tomography scans of 90 consecutive proximal trans-ulnar fracture-dislocations treated at a level I trauma center. The inclusion criteria included subluxation or dislocation of the elbow and/or radioulnar joint with a complete fracture through the proximal ulna. Each surgeon classified all fractures according to the Mayo classification, which is based on what the coronoid remains attached to (ulnar metaphysis, olecranon, or neither). Intraobserver reliability was determined by scrambling the order of the fractures and having each observer classify all the fractures again after a washout period ≥ 6 weeks. Interobserver reliability was obtained to assess the overall agreement between observers. κ Values were calculated for both intraobserver reliability and interobserver reliability. RESULTS: The average intraobserver agreement was 0.87 (almost perfect agreement; range, 0.76-0.91). Interobserver agreement was 0.80 (substantial agreement; range, 0.70-0.90) for the first reading session and 0.89 (almost perfect agreement; range, 0.85-0.93) for the second reading session. The overall average interobserver agreement was 0.85 (almost perfect agreement; range, 0.79-0.91). CONCLUSION: Classifying proximal trans-ulnar fracture-dislocations based on what the coronoid remains attached to (olecranon, ulnar metaphysis, or neither) was associated with almost perfect intraobserver and interobserver agreement, regardless of trauma vs. shoulder and elbow fellowship training. Further research is needed to determine whether the use of this classification system leads to the application of principles specific to the management of these injuries and translates into better outcomes.

Allograft prosthetic composite reconstruction using a reverse total shoulder arthroplasty for failed oncologic proximal humerus reconstruction.

INTRODUCTION: Endoprosthetic or allograft reconstruction are the preferred reconstruction techniques for proximal humeral bone tumors. Failure of these reconstructions may occur, but historically revision is performed rarely due to the lack of reliable options. Reverse shoulder arthroplasty with an allograft prosthetic composite (rAPC) may provide a revision option. The purpose of the current study was to evaluate our institutional outcome of these procedures. METHODS: Eleven (6 male, 5 female) patients (mean age 51 ± 17 years) underwent revision of a failed oncologic reconstruction of the proximal humerus utilizing a rAPC. The most common indication for revision was subluxation (n = 6) and the most common previous implant was an endoprosthesis (n = 5). RESULTS: Revision resulted in improvements in shoulder elevation (39° vs. 62°, p = 0.02), external rotation (13° vs. 25°, p = 0.04), American Shoulder and Elbow Surgeons score (39 vs. 58, p = 0.004) and Musculoskeletal Tumor Society Scores (51% vs 69%, p = 0.002). There were 2 re-revision procedures performed. One for an allograft fracture and one for allograft resorption and loosening. CONCLUSIONS: Revision with a rAPC can effectively restore patient function. Due to the complexity of the cases, we advocate for these procedures to be performed by subspecialty upper extremity surgeons trained in complex revision shoulder arthroplasty.

Superior Capsular Reconstruction: A Salvage Option for Massive Irreparable Rotator Cuff Tears with Pseudoparalysis or Subscapularis Insufficiency.

PURPOSE: We sought to examine superior capsular reconstruction (SCR) outcomes after minimum 2-year follow-up and determine risk factors that were predictive of outcomes. METHODS: Forty consecutive patients (mean age 57.3 years, 87.5% male) who underwent SCR for massive irreparable rotator cuff tears (RCT) met the inclusion criteria. Minimum 2-year follow-up was obtained for 32 patients (80% follow-up). Patient demographics and preoperative clinical findings were collected. Postoperative data, including complications, patient satisfaction, strength and range-of-motion (ROM), and patient-reported outcomes were collected. RESULTS: The Hamada score was ≤2 in 88% with average acromiohumeral interval distance of 6.8 mm. Preoperatively, 6 patients had external rotation lag (19%) and 6 had pseudoparalysis (19%). Intraoperative assessment of the subscapularis demonstrated true insufficiency in 38%. There was significant improvement in forward elevation (FE) (31° increase; P = .007) and strength in all planes (all P < .05). Patient-reported outcomes significantly improved (American Shoulder and Elbow Surgeon [ASES] 34-point increase; visual analog scale [VAS] 2.9-point decrease; single alpha-numeric evaluation [SANE] 48-point increase; all P < .05). Twenty-six patients (81%) were completely or somewhat satisfied with surgery. At time of final follow-up, 3/32 patients (9%) failed SCR and converted to reverse total shoulder arthroplasty. There were 4 (13%) reported complications (2 patients had postoperative falls; 1 patient had persistent severe pain; 1 had persistent stiffness). One patient was deceased. Patients with pseudoparalysis (n = 6) had significant improvement in post-operative FE (28 vs 154°; P < .0001) and SANE score (P = .016) with 66% patient satisfaction. However, outcome scores overall remained lower than SCR without pseudoparalysis. Regarding subscapularis insufficiency (n = 12), significant improvement was seen in postoperative FE (108 vs 158°; P = .019) and patient-reported outcome scores (P < .005). In patients converted from SCR to reverse total shoulder arthroplasty (n = 3), there were no distinguishing characteristics present. CONCLUSION: Superior capsular reconstruction is an effective salvage operation for massive irreparable RCT. Patients with pseudoparalysis or subscapularis insufficiency demonstrate significant postoperative improvement in FE and patient-reported outcomes. LEVEL OF EVIDENCE: IV, retrospective cohort.

Identifying modifiable and nonmodifiable cost drivers of ambulatory rotator cuff repair: a machine learning analysis.

INTRODUCTION: Implementing novel tools that identify contributors to the cost of orthopedic procedures can help hospitals maximize efficiency, minimize waste, improve surgical decision-making, and practice value-based care. The purpose of this study was to develop and internally validate a machine learning algorithm to identify key drivers of total charges after ambulatory arthroscopic rotator cuff repair and compare its performance with a state-of-the-art statistical learning model. METHODS: A retrospective review of the New York State Ambulatory Surgery and Services Database was performed to identify patients who underwent elective outpatient rotator cuff repair (RCR) from 2015 to 2016. Initial models were constructed using patient characteristics (age, gender, insurance status, patient income, Elixhauser Comorbidity Index) as well as intraoperative variables (concomitant procedures and services, operative time). These were subsequently entered into 5 separate machine learning algorithms and a generalized additive model using natural splines. Global variable importance and partial dependence curves were constructed to identify the greatest contributors to cost. RESULTS: A total of 33,976 patients undergoing ambulatory RCR were included. Median total charges after ambulatory RCR were $16,017 (interquartile range: $11,009-$22,510). The ensemble model outperformed the generalized additive model and demonstrated the best performance on internal validation (root mean squared error: $7112, 95% confidence interval: 7036-7188; logarithmic root mean squared error: 0.354, 95% confidence interval: 0.336-0.373, R2: 0.53), and identified major drivers of total charges after RCR as increasing operating room time, patient income level, number of anchors used, use of local infiltration anesthesia/peripheral nerve blocks, non-White race/ethnicity, and concurrent distal clavicle excision. The model was integrated into a web-based open-access application capable of providing individual predictions and explanations on a case-by-case basis. CONCLUSION: This study developed an ensemble supervised machine learning algorithm that outperformed a sophisticated statistical learning model in predicting total charges after ambulatory RCR. Important contributors to total charges included operating room time, duration of care, number of anchors used, type of anesthesia, concomitant distal clavicle excision, community characteristics, and patient demographic factors. Generation of a patient-specific payment schedule based on the Agency for Healthcare Research and Quality risk of mortality highlighted the financial risk assumed by physicians in flat episodic reimbursement schedules given variable patient comorbidities and the importance of an accurate prediction algorithm to appropriately reward high-value care at low costs.

Persistent and profound peripheral nerve injuries following reverse total shoulder arthroplasty.

BACKGROUND: Peripheral nerve injuries associated with reverse total shoulder arthroplasty (rTSA) are rarely reported and are often dismissed as neuropraxias, particularly in the setting of perioperative nerve blocks. The purpose of this study was to evaluate nerve injuries following rTSA to determine if there is a pattern of injury and to evaluate outcomes of patients who sustain an intraoperative nerve injury. METHODS: A retrospective review was performed identifying patients who underwent rTSA and had a concomitant major nerve injury who were referred to a multidisciplinary peripheral nerve injury clinic. Demographic data, preoperative nerve block use, physical examination, electrodiagnostic studies, injury pattern, and time from injury to referral was collected. Radiographs, Quick Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH) score, and outcomes surveys were obtained at final follow-up. RESULTS: Twenty-two patients were identified with postoperative nerve injuries. Average time from injury to referral was 9.0 months, with 18.8 months' follow-up. Eight patients had undergone prior shoulder surgery, and 11 patients had prior shoulder trauma. Injury patterns were variable and involved diffuse pan-plexopathies with severity localized to the posterior and medial cords (11), the upper trunk (5), lateral cord (2), and axillary nerve (4). The average postoperative acromiohumeral distance (AHD) was 3.7 cm, with an average change of 2.9 cm. The average postoperative lateral humeral offset (LHO) was 1.1 cm, with an average change of 0.2 cm. Seventeen patients were confirmed to have undergone preoperative nerve blocks, which were initially attributed as the etiology of nerve injury. Eighteen patients were initially treated with observation: 11 experienced residual debilitating neuropathic pain and/or disability, and 7 had substantial improvement. One patient underwent nerve transfers, whereas the others underwent procedures for hand dysfunction improvement. The average QuickDASH score was 53.5 at average of 4 years post rTSA. CONCLUSIONS: Although uncommon, permanent peripheral nerve injuries following rTSA do occur with debilitating effects. Preoperative regional blocks were used in most cases, but none of the blocks could be directly attributed to the nerve injuries. Nerve injuries were likely secondary to traction at the time of arthroplasty and/or substantial distalization and lateralization of the implants. Patients with medial cord injuries had the most debilitating loss of hand function. Surgeons should be cognizant of these injuries and make a timely referral to a peripheral nerve specialist.

Acute versus delayed radial head arthroplasty for the treatment of radial head fractures.

BACKGROUND: Radial head arthroplasty (RHA) is an important tool in the acute treatment of comminuted radial head and neck fractures. RHA is also performed in a delayed manner after failed open reduction and internal fixation, for fracture malunion or nonunion, and other chronic post-traumatic elbow disorders where restoration of the lateral column of the elbow is considered necessary. The relative efficacy and longevity of acute vs. delayed RHA is unknown. We sought to compare clinical, radiographic, and patient-reported outcomes between these groups. METHODS: We identified patients ≥18 years old who underwent an RHA between 2000 and 2018 and then extracted 135 total elbows with a mean follow-up of 2.3 years that sustained isolated radial head fractures (30%), terrible triad injuries (66%), or Essex-Lopresti injuries (4%). The acute cohort (RHA: <12 weeks) contained 101 elbows that underwent surgery at a mean of 0.6 weeks (range, 0 days to 7 weeks, 96% <2 weeks) from injury, whereas the delayed cohort (RHA: 12 weeks to 2 years) contained 34 elbows that underwent surgery at a mean of 36 weeks (range, 14-82 weeks) from injury. Patients in the acute group had a higher percentage of terrible triad injuries (75% vs. 40%, P < .001) and Mason 3 fractures (98% vs. 45%, P < .001). RESULTS: At the final follow-up, 13 of 101 patients in the acute cohort (13%) and 7 of 34 patients in the delayed cohort (21%) required implant revision or resection. A total of 25 patients (25%) in the acute cohort and 12 patients (35%) in the delayed cohort required a reoperation. Kaplan-Meier 2-year survival estimates free of implant resection or revision (90% acute, 86% delayed) and reoperation (76% acute, 70% delayed) were similar between groups. In patients with 5-year follow-up, there was an increased rate of revision or resection in the delayed group (30% vs. 13%). Two-year survival estimates free of radiographic loosening were 80% in the acute cohort vs. 57% in the delayed cohort (P = .04). Mayo Elbow Performance Score at 2 years demonstrated mean scores of 83 and 79 in the acute and delayed groups, respectively, with 71% of the acute cohort and 64% of the delayed cohort achieving good or excellent scores. CONCLUSIONS: Our results demonstrated that although 2-year Kaplan-Meier survival free of revision or resection estimates and reoperation rates was equivalent between the groups, the delayed group experienced worse Mayo Elbow Performance Score outcomes, a higher revision or resection rate at 5 years, and an increased rate of radiographic loosening.

AMPK activation induces mitophagy and promotes mitochondrial fission while activating TBK1 in a PINK1-Parkin independent manner.

Mitophagy is a key process regulating mitochondrial quality control. Several mechanisms have been proposed to regulate mitophagy, but these have mostly been studied using stably expressed non-native proteins in immortalized cell lines. In skeletal muscle, mitophagy and its molecular mechanisms require more thorough investigation. To measure mitophagy directly, we generated a stable skeletal muscle C2C12 cell line, expressing a mitophagy reporter construct (mCherry-green fluorescence protein-mtFIS1101-152 ). Here, we report that both carbonyl cyanide m-chlorophenyl hydrazone (CCCP) treatment and adenosine monophosphate activated protein kinase (AMPK) activation by 991 promote mitochondrial fission via phosphorylation of MFF and induce mitophagy by ~20%. Upon CCCP treatment, but not 991, ubiquitin phosphorylation, a read-out of PTEN-induced kinase 1 (PINK1) activity, and Parkin E3 ligase activity toward CDGSH iron sulfur domain 1 (CISD1) were increased. Although the PINK1-Parkin signaling pathway is active in response to CCCP treatment, we observed no change in markers of mitochondrial protein content. Interestingly, our data shows that TANK-binding kinase 1 (TBK1) phosphorylation is increased after both CCCP and 991 treatments, suggesting TBK1 activation to be independent of both PINK1 and Parkin. Finally, we confirmed in non-muscle cell lines that TBK1 phosphorylation occurs in the absence of PINK1 and is regulated by AMPK-dependent signaling. Thus, AMPK activation promotes mitophagy by enhancing mitochondrial fission (via MFF phosphorylation) and autophagosomal engulfment (via TBK1 activation) in a PINK1-Parkin independent manner.