Predictors of dislocations after reverse shoulder arthroplasty: a study by the ASES complications of RSA multicenter research group.

BACKGROUND: Instability after reverse shoulder arthroplasty (RSA) is one of the most frequent complications and remains a clinical challenge. Current evidence is limited by small sample size, single-center, or single-implant methodologies that limit generalizability. We sought to determine the incidence and patient-related risk factors for dislocation after RSA, using a large, multicenter cohort with varying implants. METHODS: A retrospective, multicenter study was performed involving 15 institutions and 24 American Shoulder and Elbow Surgeons members across the United States. Inclusion criteria consisted of patients undergoing primary or revision RSA between January 2013 and June 2019 with minimum 3-month follow-up. All definitions, inclusion criteria, and collected variables were determined using the Delphi method, an iterative survey process involving all primary investigators requiring at least 75% consensus to be considered a final component of the methodology for each study element. Dislocations were defined as complete loss of articulation between the humeral component and the glenosphere and required radiographic confirmation. Binary logistic regression was performed to determine patient predictors of postoperative dislocation after RSA. RESULTS: We identified 6621 patients who met inclusion criteria with a mean follow-up of 19.4 months (range: 3-84 months). The study population was 40% male with an average age of 71.0 years (range: 23-101 years). The rate of dislocation was 2.1% (n = 138) for the whole cohort, 1.6% (n = 99) for primary RSAs, and 6.5% (n = 39) for revision RSAs (P < .001). Dislocations occurred at a median of 7.0 weeks (interquartile range: 3.0-36.0 weeks) after surgery with 23.0% (n = 32) after a trauma. Patients with a primary diagnosis of glenohumeral osteoarthritis with an intact rotator cuff had an overall lower rate of dislocation than patients with other diagnoses (0.8% vs. 2.5%; P < .001). Patient-related factors independently predictive of dislocation, in order of the magnitude of effect, were a history of postoperative subluxations before radiographically confirmed dislocation (odds ratio [OR]: 19.52, P < .001), primary diagnosis of fracture nonunion (OR: 6.53, P < .001), revision arthroplasty (OR: 5.61, P < .001), primary diagnosis of rotator cuff disease (OR: 2.64, P < .001), male sex (OR: 2.21, P < .001), and no subscapularis repair at surgery (OR: 1.95, P = .001). CONCLUSION: The strongest patient-related factors associated with dislocation were a history of postoperative subluxations and having a primary diagnosis of fracture nonunion. Notably, RSAs for osteoarthritis showed lower rates of dislocations than RSAs for rotator cuff disease. These data can be used to optimize patient counseling before RSA, particularly in male patients undergoing revision RSA.

Risk factors of acromial and scapular spine stress fractures differ by indication: a study by the ASES Complications of Reverse Shoulder Arthroplasty Multicenter Research Group.

BACKGROUND: Both patient and implant related variables have been implicated in the incidence of acromial (ASF) and scapular spine fractures (SSF) following reverse shoulder arthroplasty (RSA); however, previous studies have not characterized nor differentiated risk profiles for varying indications including primary glenohumeral arthritis with intact rotator cuff (GHOA), rotator cuff arthropathy (CTA), and massive irreparable rotator cuff tear (MCT). The purpose of this study was to determine patient factors predictive of cumulative ASF/SSF risk for varying preoperative diagnosis and rotator cuff status. METHODS: Patients consecutively receiving RSA between January 2013 and June 2019 from 15 institutions comprising 24 members of the American Shoulder and Elbow Surgeons (ASES) with primary, preoperative diagnoses of GHOA, CTA and MCT were included for study. Inclusion criteria, definitions, and inclusion of patient factors in a multivariate model to predict cumulative risk of ASF/SSF were determined through an iterative Delphi process. The CTA and MCT groups were combined for analysis. Consensus was defined as greater than 75% agreement amongst contributors. Only ASF/SSF confirmed by clinical and radiographic correlation were included for analysis. RESULTS: Our study cohort included 4764 patients with preoperative diagnoses of GHOA, CTA, or MCT with minimum follow-up of 3 months (range: 3-84). The incidence of cumulative stress fracture was 4.1% (n = 196). The incidence of stress fracture in the GHOA cohort was 2.1% (n = 34/1637) compared to 5.2% (n = 162/3127) (P < .001) in the CTA/MCT cohort. Presence of inflammatory arthritis (odds ratio [OR] 2.90, 95% confidence interval [CI] 1.08-7.78; P = .035) was the sole predictive factor of stress fractures in GHOA, compared with inflammatory arthritis (OR 1.86, 95% CI 1.19-2.89; P = .016), female sex (OR 1.81, 95% CI 1.20-2.72; P = .007), and osteoporosis (OR 1.56, 95% CI 1.02-2.37; P = .003) in the CTA/MCT cohort. CONCLUSION: Preoperative diagnosis of GHOA has a different risk profile for developing stress fractures after RSA than patients with CTA/MCT. Though rotator cuff integrity is likely protective against ASF/SSF, approximately 1/46 patients receiving RSA with primary GHOA will have this complication, primarily influenced by a history of inflammatory arthritis. Understanding risk profiles of patients undergoing RSA by varying diagnosis is important in counseling, expectation management, and treatment by surgeons.

The successful migration of total joint arthroplasty from the hospital inpatient to outpatient ASC setting.

BACKGROUND: This study was undertaken to analyze the clinical results and complication rate of patients undergoing outpatient total joint arthroplasty by a single orthopedic group. All surgeries were performed in the practice-owned ambulatory surgery center (ASC). METHODS: All patients indicated for outpatient total joint arthroplasty from 2016-2019 with complete pre and post-operative patient reported outcomes were enrolled in the study including hip, knee and partial knee replacements. Patient reported outcomes including HOOS, KOOS and VR-12 were collected at six months. Patient complication and satisfaction data was also collected. RESULTS: There were 1007 patients enrolled in the study. At six months, THA HOOS and VR-12 scores improved to 82.2 and 54.5/45. TKA KOOS and VR-12 scores improved to an average of 74.3 and 54.0/43.6. At six months, UKA scores improved to an average of 73.6 and 55.1/41.2. All HOOS, KOOS and VR-12 PCS scores improvements were statistically significant (p < 0.001) and met MCID thresholds. A separate cohort of 1898 regionally tracked cases with comprehensive global complication data exhibited 111 complications (unplanned post-operative events generating a medical expense) including manipulation 13 (0.68%), DVT/PE 4 (0.2%), medical 45 (2.4%), wound 8 (0.4%), infection 8 (0.4%). Sixty-six outpatient cases (3.5%) experienced clinical complications requiring some form of additional treatment. CONCLUSION: Outpatient joint arthroplasty performed in the ASC is safe and effective in appropriately selected patients with complication rates that compares favorably to inpatient procedures.

Unicompartmental Knee Arthroplasty Is Not Associated With Increased Revision Rates in Obese Patients.

BACKGROUND: There is controversy among arthroplasty surgeons in regard to performing unicompartmental knee arthroplasty (UKA) in obese patients based on current literature. The aim of this study is to investigate whether UKA is associated with increased complications and revision rates in obese (body mass index [BMI] > 30 kg/m2), morbidly obese (BMI > 40 kg/m2), and super morbid obese (BMI > 50 kg/m2) patients. METHODS: We retrospectively reviewed all UKAs performed at our institution from January 2008 to December 2017. A total of 2178 UKA procedures were performed during this period. The patients were categorized based on BMI to include normal weight (BMI = 20-30 kg/m2), obese (BMI ≥ 30.1-40 kg/m2), morbidly obese (BMI ≥ 40.1-50 kg/m2), and super morbid obese (BMI ≥ 50.1 kg/m2) groups. Record review was performed to obtain demographic data, need for revision (timing, type, and etiology), and complication rate and cause. RESULTS: The 2178 UKA cases were eligible for inclusion in this investigation. We performed 2028 medial UKAs and 150 lateral UKAs. The mean clinical follow-up period was 3.7 years, and the mean time from index surgery to revision was 7.2 years. Of the 2178 UKA cases, 1167 had a 3-year minimum follow-up. The overall revision rate in all patients was 2.2%. There was no significant difference (P > .05) in revision rates among normal weight (3.0%), obese (2.7%), morbidly obese (1.9%), and super morbid obese patients (1.8%). Most failures in all groups were secondary to progression of osteoarthritis requiring total knee arthroplasty. CONCLUSIONS: Similar rates of revision were found for UKAs performed on obese, morbidly obese, or super morbid obese patients (≤2.0% revision rate) vs normal BMI (2.7% revision rate) patients. Progressive osteoarthritis was the most common mechanism of UKA failure. Obesity is not a contraindication for UKA despite previous recommendations to the contrary.

A system for automated quantification of cutaneous electrogastrograms.

Clinical evaluation of cutaneous electrogastrograms (EGG) is important for understanding the role of slow waves in functional motility disorders and may be a useful diagnostic aid. An automated software package has been developed which computes metrics of interest from EGG and from slow wave recordings from the gastric mucosa and serosa in a reliable and efficient manner. In particular, the frequency and amplitude of the gastric slow waves were computed, after which signal integrity checks were performed to assess if the signals are valid. For validation, manual estimates of the frequency and amplitude were compared to automated estimates. The methods were packaged into a software executable which processes the data and presents the results in an intuitive graphical and a spreadsheet formats. Automated EGG analysis allows for clinical translation of bio-electrical analysis for potential diagnostics, as commonly used in the cardiac field.

Vertebral compression model and comparison of augmentation agents.

STUDY DESIGN: Biomechanical study. OBJECTIVES: To evaluate the compression strengths of various bone fillers used in treating vertebral compression fractures using a third-generation sawbone model and to evaluate the viability of this novel model as an alternative to actual human or animal vertebrae for biomechanical testing of vertebral-filling materials. METHODS: Cavities were created in the osteoporotic vertebral body sawbone models and filled with PMMA, SRS, MIIGX3 HiVisc, and BoneSource fillers. These were cured according to manufacturers' recommendations and then tested to failure in the compression model. Elastic modulus was calculated and compared with the control group which was not augmented. RESULTS: The mean modulus of elasticity for the control group vertebrae was 92.44 ± 19.28 MPa. The mean modulus of elasticity was highest in the polymethylmethacrylate (PMMA) group (195.47 ± 2.33 MPa) and lowest in the MIIG group (25.79 ± 4.77 MPa). The results for the SRS-tricalcium phosphate group (79.14 ± 20.20 MPa) were closest to the control group, followed by the BoneSource group (57.49 ± 8.35 MPa). Statistical analysis, for comparison of individual group means, identified significant differences between the control group and all other groups (P < .05), with the exception of the SRS-tricalcium phosphate group (P = .65, versus control). The modulus of elasticity for the PMMA group was significantly higher than all other groups (P < .001). CONCLUSION: The third-generation osteoporotic sawbones model simulates in vitro physiological specimen function. It was effective for comparing which osteoconductive agents may provide adequate strength while minimizing potential adjacent level fracture. Increased stiffness was seen with PMMA compared with the unaugmented control as well as with calcium phosphate or calcium sulfate cements suggesting that these may reduce adjacent segment fractures.

Comparison of pull out strength of resorbable screws in human cadaveric laryngeal cartilage using different drill diameters.

BACKGROUND: In a previous study at our institution, it was determined that resorbable screws with untapped drill holes resulted in the highest resistance forces to linear load when compared with titanium screws. The 1.1-mm drill diameter/2.0-mm screw diameter and 1.5/2.0 drill/screw combinations were superior to the 1.1/1.5 combinations; however, there was no conclusion as to the best screw size to drill bit diameter. The aim of this prospective study was to compare the pull out strength of resorbable screws in fresh frozen cadaveric laryngeal cartilage. The importance of drill hole diameter will also be determined. METHODS: After debridement of connective tissue and perichondrium, 12 cartilage specimens were tested. Linear pull out strength of screws was measured using a load cell. Resorbable screws of size 2.0 mm were tested using drill hole diameters of 0.0 mm, 0.8 mm, and 1.5 mm. All tested screws were 6 mm in length or greater. RESULTS: We found no strong evidence that the means for the 0.8/2.0 and 1.5/2.0 differ or that the 0.0/2.0 and 0.8/2.0 means differ. There is evidence that the 0.0/2.0 and 1.5/2.0 means differ (adjusted p value .0108), with the 0.0/2.0 combination having a smaller mean. CONCLUSIONS: Resorbable screws without pre drilled holes result in less resistance to linear loads than either the resorbable screws with the 0.8/2.0 or the 1.5/2.0 drill/screw combinations. The 1.5/2.0 drill/screw combination had the strongest pull out force, though this was not statistically significant.

Comparison of pullout strength of resorbable screws and titanium screws in human cadaveric laryngeal cartilage.

OBJECTIVES: To compare the pullout strength of titanium screws and resorbable screws from human fresh-frozen cadaveric laryngeal cartilage. The importance of drill hole diameter, screw diameter, and whether the drill hole was tapped (resorbable screws only) was also determined. STUDY DESIGN: Prospective. METHODS: Sixteen cartilage specimens were tested after debridement of connective tissue and perichondrium. Linear pullout strength of screws was measured using a load cell. Titanium and resorbable screw sizes of 1.5 and 2.0 mm were tested using drill hole diameters of 1.1 and 1.5 mm. For the resorbable-tapped group, screw diameters of 1.5 and 2.0 mm were tapped with 1.5 and 2.0 mm taps, respectively. All tested screws were 6 mm in length. RESULTS: We found a uniformly constant difference between the three screw types (P < .001). Post hoc analysis indicated a significant difference between the resorbable-untapped screw and both the resorbable-tapped screw and the titanium screw. We failed to find a significant difference, however, between the resorbable-tapped screw and the titanium screw. We also found a significant effect in regard to screw size (P = .0133), with post hoc analysis demonstrating the 1.1/1.5 mm combination to be inferior to the 1.1/2.0 and 1.5/2.0 mm combinations. There was no significant difference between the 1.1/2.0- and 1.5/2.0-mm combinations. CONCLUSIONS: Resorbable screws with untapped drill holes result in higher resistance to linear loads than both titanium screws and resorbable screws with tapped drill holes. The 1.1/2.0- and 1.5/2.0-mm drill/screw combinations are superior to the 1.1/1.5-mm combination when considering untapped resorbable screws.