Concomitant latissimus dorsi tendon transfer during reverse total shoulder arthroplasty does not improve active external rotation or clinical outcomes in patients with external rotation deficit.

BACKGROUND: To assess the role of latissimus dorsi tendon transfer (LDT) concomitant with reverse total shoulder arthroplasty in patients with external rotation (ER) deficit secondary to severe rotator cuff deficiency with and without glenohumeral arthritis. METHODS: Patients with a positive external lag sign and <10° of active external rotation (aER) treated with reverse shoulder arthroplasty at a single institution with a minimum 12-month follow-up were retrospectively identified from a prospective database. Basic demographic information along with preoperative and postoperative range of motion (ROM) measures, American Shoulder and Elbow Surgeons score (ASES), Visual Analog Scale (VAS) pain, and Subjective Shoulder Value scores were obtained. Statistical analysis was performed to compare ROM and functional outcomes between patients who underwent concomitant LDT and those with no transfer (NT). RESULTS: The LDT (n = 31) and NT (n = 33) groups had similar age, sex distributions, and follow-up length average (24 vs. 30 months). No differences were found between groups at baseline, final follow-up, or magnitude of change for ASES, VAS pain, and Subjective Shoulder Value scores. Baseline ROM measures were similar, except for the LDT group having slightly less aER (-8° vs. 0°; P = .004). In addition, all postoperative ROM measures including aER were similar, except for a slight improvement in active internal rotation in the NT group. The majority of patients were satisfied with their outcome (LDT 84% (n = 26); NT 87% (n = 27); P = .72). CONCLUSION: Patients with ER deficit secondary to severe rotator cuff deficiency with and without glenohumeral arthritis undergoing reverse total shoulder arthroplasty do not have significantly improved ER or patient-reported outcome measures with LDT.

Management of the subscapularis tendon during total shoulder arthroplasty.

Use of total shoulder arthroplasty has significantly increased during the past decade. For anatomic total shoulder arthroplasty, controversy exists regarding the best technique for detachment and repair of the subscapularis tendon. Options include tendon tenotomy, peel, lesser tuberosity osteotomy, and even subscapularis-sparing techniques. Inadequate healing of the subscapularis tendon can lead to postoperative pain, weakness, and instability. This review discusses the subscapularis pathoanatomy, different techniques for releasing and repairing the tendon, and reports biomechanical and clinical outcomes for each technique after total shoulder arthroplasty.

Patient factors influencing return to work and cumulative financial claims after clavicle fractures in workers' compensation cases.

BACKGROUND: This study analyzed workers' compensation patients after surgical or nonoperative treatment of clavicle fractures to identify factors that influence the time for return to work and total health care reimbursement claims. We hypothesized that return to work for operative patients would be faster. METHODS: The International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes and Current Procedural Terminology codes were used to retrospectively query the Workers' Compensation national database. The outcomes of interest were the number of days for return to full work after surgery and total reimbursement for health care-related claims. The primary independent variable was treatment modality. RESULTS: There were 169 claims for clavicle fractures within the database (surgical, n = 34; nonoperative, n = 135). The average health care claims reimbursed were $29,136 ± $26,998 for surgical management compared with $8366 ± $14,758 for nonoperative management (P < .001). We did not find a statistically significant difference between surgical (196 ± 287 days) and nonoperative (69 ± 94 days) treatment groups in their time to return to work (P = .06); however, there was high variability in both groups. Litigation was an independent predictor of prolonged return to work (P = .007) and higher health care costs (P = .003). CONCLUSION: Workers' compensation patients treated for clavicle fractures return to work at roughly the same time whether they are treated surgically or nonoperatively, with surgery being roughly 3 times more expensive. There was a substantial amount of variability in return to work timing by subjects in both groups. Litigation was a predictor of longer return to work timing and higher health care costs.

An analysis of adult patient risk factors and complications within 30 days after arthroscopic shoulder surgery.

PURPOSE: To identify risk factors of adult patients predisposing them to the most common complications that occur within 30 days after arthroscopic shoulder surgery. METHODS: The National Surgical Quality Improvement Program database was queried for arthroscopic shoulder procedures. Complications and their frequency were calculated. Multivariate analysis was used to identify risk factors of adult patients predisposing them to complications. Risk factors for reoperation and characteristics of patients undergoing repair procedures were also analyzed. RESULTS: Among 10,255 cases of shoulder arthroscopy, 119 complications were reported in 103 cases within 30 days of surgery. The rates of any, major, and minor complications were 1%, 0.57%, and 0.53%, respectively. Return to the operating room (29% of all complications) was the most frequent complication. With risk adjustment, the odds of complications developing were higher for patients older than 60 years (adjusted odds ratio [AOR], 3.47; P = .03), patients with a surgical time greater than 1.5 hours (AOR, 1.93; P = .01), patients with chronic obstructive pulmonary disease (COPD; AOR, 2.76; P = .03), patients with an inpatient status (AOR, 2.72; P < .01), patients with disseminated cancer (AOR, 21.9; P < .01), and current smokers (AOR, 1.94; P = .01). The presence of COPD (AOR, 4.67; P = .04) was a significant predictor for reoperation within 30 days. Repair procedures did not increase the risk of complications compared with non-repair. Male patients, patients aged younger than 30 years, nondiabetic patients, and nonsmokers were more likely to undergo repair procedures (P < .05 for all). CONCLUSIONS: Shoulder arthroscopy has a 1.0% thirty-day complication rate, with the most common complication being return to the operating room (29% of all complications). Age older than 60 years, surgical time greater than 90 minutes, COPD, inpatient status, disseminated cancer, and current smoking all increased a patient's risk of complications. Patients undergoing repair procedures were not at increased risk. Pulmonary comorbidity increases the risk of reoperation within 30 days. Patients undergoing repair procedures tend to be younger and carry fewer risk factors for complications. LEVEL OF EVIDENCE: Level IV, prognostic case series.

Scapular dyskinesis following displaced fractures of the middle clavicle.

PURPOSE: To evaluate the rate of scapular dyskinesis and resulting patient outcomes after treatment of displaced midshaft clavicle fractures. METHODS: Skeletally mature patients with isolated, displaced midshaft clavicle fractures treated with or without surgery over a 16-month period were recruited. The minimum length of follow-up at study examination was 12 months. Patient outcomes were documented using the SICK (scapular malposition, inferomedial border prominence, coracoid pain and malposition, and dyskinesis of scapular movement) Scapula Rating Scale, the Simple Shoulder Test, 3 visual analog scales (VAS) for pain, and shoulder range-of-motion and strength measurements. Of the 32 eligible patients, 24 (75%) were successfully recruited. RESULTS: The mean participant age was 46 ± 17 years, with a mean length of follow-up at study evaluation of 1.7 ± 1 years. Surgical fixation was performed in 12 patients (50%). Scapular dyskinesis was present in 37.5% of patients (n = 9). Patients with scapular dyskinesis had worse SICK scapula scores (5.8 ± 2.2 vs 3.1 ± 2.4, P = .01), worse Simple Shoulder Test scores (10.5 ± 1.6 vs 11.7 ± 0.8, P = .029), higher maximum VAS pain scores (4.1 ± 3.1 vs 0.97 ± 1.2, P = .002), and worse average VAS pain scores in the week before the examination (2.7 ± 2.5 vs 0.2 ± 0.4, P < .001) compared with patients without scapular dyskinesis. Range of motion and abduction strength were similar between the groups. Scapular dyskinesis developed in 1 patient treated with surgery (8% [1 of 12]) compared with 8 patients treated nonoperatively (67% [8 of 12]) (P = .009). CONCLUSIONS: Scapular dyskinesis is common after displaced middle-third clavicle fractures, and these patients have more pain and worse functional outcomes compared with patients without scapular dyskinesis. Surgical treatment may reduce a patient's risk of scapular dyskinesis developing and improve short-term outcomes.

Effects of varying locations for biceps tendon tenotomy and superior labral integrity on shoulder stability in a cadaveric concavity-compression model.

PURPOSE: The purpose of this study was to examine the location of biceps tenotomy and the integrity of the superior labrum as they relate to superior glenohumeral joint stability in a cadaveric concavity-compression model. METHODS: Eight cadaveric glenoid labrums were mounted individually onto a load cell with the corresponding humerus fixed to the loading arm in the hanging-arm position. All surrounding soft tissue was removed except the labrum and proximal stump of the long head of the biceps (LHB) tendon, simulating a biceps tenotomy. A compressive load of 22 N was applied across the glenohumeral joint. The humerus was then translated superiorly until it subluxated over the glenoid labrum. The force resisting superior translation was characterized for each of 50 cycles. Each specimen was tested under the following conditions: (1) with a 4 cm biceps stump after tenotomy, (2) with a 0 cm biceps stump, (3) after full detachment of the superior labrum, and (4) after repair of the labrum. RESULTS: Biceps tenotomy performed at the biceps-labral junction resulted in an average decrease in force required to superiorly subluxate the humeral head by 8.6% (P = .01) when compared with leaving 4 cm of biceps stump. Resection of the entire superior labrum resulted in a future decrease to 15.2% (P < .001) from baseline. Repair of the labrum resulted in restoration of stability with a mean of 101.1% (P = .82) and was not statistically different from baseline. The kinematics of the glenohumeral joint was affected by labral repair, with an earlier upslope on the force-to-displacement curve and alteration in the total energy required to cause subluxation of the humeral head noted. CONCLUSIONS: In this study, location of the biceps tenotomy and integrity of the superior labrum affected glenohumeral stability during axial loading in the hanging-arm position. Repair of the labrum restored stability for superior subluxation but also changed the kinematics of the subluxation event. CLINICAL RELEVANCE: Preservation of superior labrum after biceps tenotomy provides increased resistive force to superior translation in a unidirectional biomechanical model.

Perioperative complications after hemiarthroplasty and total shoulder arthroplasty are equivalent.

BACKGROUND: Total shoulder arthroplasty (TSA) results in superior clinical outcomes to hemiarthroplasty (HA); however, TSA is a more technical and invasive procedure. This study retrospectively compares perioperative complications after HA and TSA using the National Surgical Quality Improvement Program (NSQIP) database. METHODS: The NSQIP user file was queried for HA and TSA cases from the years 2005 through 2010. Major complications were defined as life-threatening or debilitating. All complications occurred within 30 days of the initial procedure. We performed multivariate analysis to compare complication rates between the two procedures, controlling for patient comorbidities. RESULTS: The database returned 1,718 patients (HA in 30.4% [n = 523] and TSA in 69.6% [n = 1,195]). The major complication rates in the HA group (5.2%, n = 29) and TSA group (5.1%, n = 61) were similar (P = .706). Rates of blood transfusions for postoperative bleeding in patients undergoing HA (2.3%, n = 12) and TSA (2.9%, n = 35) were indistinguishable (P = .458). Venous thromboembolism was a rare complication, occurring in 0.4% of patients in each group (2 HA patients and 5 TSA patients, P > .999). On multivariate analysis, the operative procedure was not associated with major complications (P = .349); however, emergency case, pulmonary comorbidity, anemia with a hematocrit level lower than 36%, and wound class of III or IV increased the risk of a major complication (P < .05 for all). CONCLUSION: Multivariate analysis of patients undergoing TSA or HA in the NSQIP database suggests that patient factors-not the procedure being performed-are significant predictors of major complications. Controlling for patient comorbidities, we found no increased risk of perioperative major complications in patients undergoing TSA compared with HA.

A comparison of cortical button with interference screw versus suture anchor techniques for distal biceps brachii tendon repairs.

BACKGROUND: Distal biceps brachii tendon repairs performed by a "tension slide technique" with a cortical button and interference screw (CB) are stronger than repairs by suture anchor (SA) techniques in biomechanical studies. However, clinical comparison of the 2 techniques is lacking in the literature. METHODS: Distal biceps tendon ruptures repaired with either a CB or SA technique through a single incision were identified from 2008 to 2013 at a single institution. Patients more than a year out from surgery completed a Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire. In addition, patients were assessed for range of motion, strength, and complications. All assessments were performed by individuals blinded to the surgical technique. Strength and motion values from the operative extremity minus the nonoperative arm values yielded differential values that were averaged and used to compare treatment groups. RESULTS: The CB (n = 20) and SA (n = 17) groups had similar demographics, except for the time from the surgery to evaluation (18 ± 5 vs 32 ± 15 months, respectively; P = .007). Range of motion differed slightly between the groups. The CB group demonstrated better pronation (0° ± 5° vs -4° ± 10°; P < .05), and the SA group demonstrated better flexion (2° ± 0° vs -3° ± 5°; P < .05) and supination (-2° ± 5° vs -7° ± 12°; P < .05). Strength did not differ significantly between the groups. DASH scores did not significantly differ between the groups with univariate analysis, but multivariate analysis demonstrated slightly better DASH scores with the CB technique (4.5 ± 4.4 vs 10.3 ± 14.9; P < .0009). Complication rates were similar between groups (CB 30%, SA 35%; P > .05). CONCLUSION: CB and SA techniques provide good clinical results with similar complication rates.

Revision rates and cumulative financial burden in patients treated with hemiarthroplasty compared to cannulated screws after femoral neck fractures.

INTRODUCTION: This study compares re-operation rates and financial burden following the treatment of femoral neck fractures treated with hemiarthroplasty compared to non-displaced femoral neck fractures treated with cannulated screws. METHODS: Data was retrospectively analyzed from a prospective database at a university hospital setting on patients undergoing hemiarthroplasty after femoral neck fractures and those with non-displaced femoral neck fractures treated with cannulated screws over a 7-year period. Re-operation rates were determined and financial data was analyzed. Charges refer to amounts billed by the hospital to insurance carriers, while costs refer to financial burden carried by the hospital during treatment. RESULTS: There were 491 femoral neck fractures (475 patients) that underwent hemiarthroplasty (HA) and 120 non-displaced fractures (119 patients) treated with cannulated screw (CannS) fixation. Both groups had similar age, sex, Charlson co-morbidity scores, pre-operative Parker mobility scores, and 12-month mortality. There were 29 (5.9 %) reoperations in the HA group and 16 (13.3 %) in the CannS group (P = 0.007). The majority of re-operations occurred within 12 months for both groups [21/29 (72 %) HA group; 15/16 (94 %) CannS group; P = 0.13]. Average hospital charges per patient for the index procedure were higher in the HA group ($17,880 ± 745) compared to the CannS group ($14,104 ± 5,047; P < 0.001). After accounting for additional procedures related to their initial surgical fixation, average hospital charges and costs remained higher in the HA group. CONCLUSION: Patients treated with hemiarthroplasty for femoral neck fractures have lower re-operation rates than patients treated with cannulated screws for non-displaced femoral neck fractures, with 80 % of re-operations occurring in the first 12 months. Hospital charges and costs to the hospital for treating patients undergoing hemiarthroplasty were higher than patients treated with cannulated screws for the index procedure alone, and after accounting for re-operations.

Humeral Component Version Has No Effect on Outcomes Following Reverse Total Shoulder Arthroplasty: A Prospective, Double-Blinded, Randomized Controlled Trial.

BACKGROUND: Controversy exists regarding the ideal humeral component version to optimize humeral rotation and patient outcomes in reverse total shoulder arthroplasty (rTSA). METHODS: Patients undergoing primary rTSA for rotator cuff tear arthropathy, a massive rotator cuff tear, or primary osteoarthritis with a rotator cuff tear were randomized to placement of the humeral component in neutral version or 30° of retroversion. Shoulder active range of motion and strength and visual analog scale (VAS) pain, American Shoulder and Elbow Surgeons (ASES), and Patient-Reported Outcomes Measurement Information System Global 10 (PROMIS-10) scores were collected up to 2 years postoperatively. The goal of the study was to determine whether humeral external rotation and internal rotation are affected by humeral component version following rTSA at 2 years postoperatively. RESULTS: Sixty-six patients were included in the analysis. The median follow-up was 26 months for the neutral and 27 months for the 30° retroversion group. No differences between the groups were observed with respect to the primary diagnosis, sex, age, body mass index, or American Society of Anesthesiologists (ASA) class. The 2 groups did not differ significantly in terms of improvement at 2 years in active shoulder abduction (p = 0.969), forward elevation (p = 1.000), internal rotation measured as the highest spinal level reached (p = 1.000), internal rotation with the arm abducted 90° (p = 0.451), external rotation (p = 0.362), or muscle strength in forward elevation (p = 1.000), abduction (p = 1.000), external rotation (p = 0.617), or internal rotation (p = 1.000). The 2 groups did not differ significantly in terms of improvement in postoperative ASES (p = 1.000), PROMIS-10 physical (p = 1.000), or VAS pain scores (p = 0.718) at the time of final follow-up. In the neutral version group, 1 patient underwent revision for instability and 1 for stiffness. One acromial stress fracture occurred in the 30° humeral retroversion group. Scapular notching was observed in 7 (21.2%) of the patients in neutral version group and 5 (15.2%) of the patients in the 30° retroversion group (p = 0.750). CONCLUSIONS: Securing the humeral component at neutral version or 30° of retroversion in rTSA resulted in similar active shoulder external rotation, internal rotation, forward elevation, abduction, and strength measurements, complication rates, and VAS pain, PROMIS-10 physical, and ASES scores at 2 years postoperatively. LEVEL OF EVIDENCE: Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

The Modified Shields Classification and 12 Families with Defined DSPP Mutations.

Mutations in Dentin Sialophosphoprotein (DSPP) are known to cause, in order of increasing severity, dentin dysplasia type-II (DD-II), dentinogenesis imperfecta type-II (DGI-II), and dentinogenesis imperfecta type-III (DGI-III). DSPP mutations fall into two groups: a 5'-group that affects protein targeting and a 3'-group that shifts translation into the −1 reading frame. Using whole-exome sequence (WES) analyses and Single Molecule Real-Time (SMRT) sequencing, we identified disease-causing DSPP mutations in 12 families. Three of the mutations are novel: c.53T>C/p.(Val18Ala); c.3461delG/p.(Ser1154Metfs*160); and c.3700delA/p.(Ser1234Alafs*80). We propose genetic analysis start with WES analysis of proband DNA to identify mutations in COL1A1 and COL1A2 causing dominant forms of osteogenesis imperfecta, 5'-DSPP mutations, and 3'-DSPP frameshifts near the margins of the DSPP repeat region, and SMRT sequencing when the disease-causing mutation is not identified. After reviewing the literature and incorporating new information showing distinct differences in the cell pathology observed between knockin mice with 5'-Dspp or 3'-Dspp mutations, we propose a modified Shields Classification based upon the causative mutation rather than phenotypic severity such that patients identified with 5'-DSPP defects be diagnosed as DGI-III, while those with 3'-DSPP defects be diagnosed as DGI-II.

Analysis of in vivo corrosion of 316L stainless steel posterior thoracolumbar plate systems: a retrieval study.

STUDY DESIGN: One hundred eighteen patients retrieved 316L stainless steel thoracolumbar plates, of 3 different designs, used for fusion in 60 patients were examined for evidence of corrosion. A medical record review and statistical analysis were also carried out. OBJECTIVE: This study aims to identify types of corrosion and examine preferential metal ion release and the possibility of statistical correlation to clinical effects. SUMMARY OF BACKGROUND DATA: Earlier studies have found that stainless steel spine devices showed evidence of mild-to-severe corrosion; fretting and crevice corrosion were the most commonly reported types. Studies have also shown the toxicity of metal ions released from stainless steel corrosion and how the ions may adversely affect bone formation and/or induce granulomatous foreign body responses. METHODS: The retrieved plates were visually inspected and graded based on the degree of corrosion. The plates were then analyzed with optical microscopy, scanning electron microscopy, and energy dispersive x-ray spectroscopy. A retrospective medical record review was performed and statistical analysis was carried out to determine any correlations between experimental findings and patient data. RESULTS: More than 70% of the plates exhibited some degree of corrosion. Both fretting and crevice corrosion mechanisms were observed, primarily at the screw plate interface. Energy dispersive x-ray spectroscopy analysis indicated reductions in nickel content in corroded areas, suggestive of nickel ion release to the surrounding biological environment. The incidence and severity of corrosion was significantly correlated with the design of the implant. CONCLUSIONS: Stainless steel thoracolumbar plates show a high incidence of corrosion, with statistical dependence on device design.

Stemless Total Shoulder: A Review of Biomechanical Fixation and Recent Results.

Introduction: Anatomic total shoulder arthroplasty is the replacement of the humeral head and glenoid surfaces with the goal of replicating normal anatomy. It is commonly utilized for patients with osteoarthritis, rheumatoid arthritis, and osteonecrosis, who have decreased range of motion (ROM), persistent pain, and loss of strength. Total shoulder Arthroplasty (TSA) is the third most common joint replacement in the United States. The incidence of TSA has been increasing, some data suggest that by the year 2025, TSA incidence may rise to 439,206 operations per year. In recent years, stemless total shoulder implants have become available. Results: These implants preserve bone stock while decreasing complications such as osteolysis, stress shielding and periprosthetic fracture. Stemless implants improve anatomic reconstruction and biomechanical function of the shoulder joint. Conclusion: Increasing amounts of data suggest stemless TSA to be a safe and effective technology that will become more common in the coming year.

Patient Outcomes After Revision of Anatomic Total Shoulder Arthroplasty to Reverse Shoulder Arthroplasty for Rotator Cuff Failure or Component Loosening: A Matched Cohort Study.

PURPOSE: To compare outcomes after conversion of anatomic total shoulder arthroplasty (aTSA) to reverse total shoulder arthroplasty (RTSA) and a matched cohort. METHODS: Patients converted from aTSA to RTSA for rotator cuff failure or component loosening and a primary RTSA matched cohort were retrospectively identified from a prospective database. Demographics and preoperative and postoperative outcomes were obtained and compared. RESULTS: Age, sex, body mass index, follow-up length, and preoperative function were similar between revision (n = 35) and primary (n = 70) groups. At final follow-up, visual analog scale pain (2.4 ± 2.8 versus 1.7 ± 2.8; P = 0.24) and American Shoulder and Elbow Surgeons (68 ± 26 versus 76 ± 24; P = 0.14) scores were similar. The revision group had worse subjective shoulder value scores (63 ± 30 versus 79 ± 21; P = 0.002), satisfaction (74% versus 90%; P = 0.03), and more complications (31% versus 13%; P = 0.02). CONCLUSION: Revision of aTSA to RTSA for component loosening or rotator cuff failure results in function comparable to primary RTSA; however, more complications, worse subjective shoulder value scores, and lower patient satisfaction should be expected. LEVEL OF EVIDENCE: Level III, retrospective comparative.

Venous Thromboembolism After Shoulder Arthoplasty and Arthroscopy.

Venous thromboembolism (VTE) in the orthopaedic literature largely focuses on lower extremity trauma and arthroplasty, with relatively few investigations of VTE after shoulder surgery. Because the rate of shoulder surgery, especially arthroplasty, continues to expand, it is important for practicing surgeons to understand the magnitude of risk, potential consequences, and prevention methods with regard to VTE. VTE after shoulder surgery has been a topic of increasing interest over the past decade, and the purpose of this review is to examine the recent literature on pathophysiology, risk factors, incidence, diagnosis, sequelae, prevention, treatment, and current recommendations regarding VTE after shoulder surgery.

Rhythm generation by the pre-Bötzinger complex in medullary slice and island preparations: effects of adenosine A(1) receptor activation.

BACKGROUND: The pre-Bötzinger complex (preBötC) is a central pattern generator within the ventrolateral medulla oblongata's ventral respiratory group that is important for the generation of respiratory rhythm. Activation of adenosine A(1) receptors (A(1)R) depresses preBötC rhythmogenesis. Although it remains unclear whether A(1)R activation is important for organisms in a normal metabolic state, A(1)R activation is important to the response of the preBötC to metabolic stress, such as hypoxia. This study examined mechanisms linking A(1)R activation to depression of preBötC rhythmogenesis in medullary slice and island preparations from neonatal mice. RESULTS: Converting medullary slices to islands by cutting away much of the medullary tissue adjacent to the preBötC decreased the amplitude of action potential bursts generated by a population of neurons within the preBötC (recorded with an extracellular electrode, and integrated using a hardware integrator), without noticeably affecting burst frequency. The A(1)R agonist N6-Cyclopentyladenosine (NCPA) reduced population burst frequency in slices by ca. 33% and in islands by ca. 30%. As in normal (drug-free) artificial cerebrospinal fluid (aCSF), NCPA decreased burst frequency in slices when GABA(A)ergic or GABA(A)ergic and glycinergic transmission were blocked, and in islands when GABA(A)ergic transmission was antagonized. Converting slices to island preparations decreased synaptic input to inspiratory neurons. NCPA further decreased the frequency of synaptic inputs to neurons in island preparations and lowered the input resistance of inspiratory neurons, even when chemical communication between neurons and other cells was impeded. CONCLUSION: Together these data support the suggestion that depression of preBötC activity by A(1)R activation involves both decreased neuronal excitability and diminished inter-neuronal communication.

Carbenoxolone induced depression of rhythmogenesis in the pre-Bötzinger Complex.

BACKGROUND: Carbenoxolone (CBX), a gap junction uncoupler, alters the functioning of the pre-Bötzinger Complex (preBötC), a central pattern generating neuronal network important for the production of respiratory rhythm in mammals. Even when isolated in a 1/2 mm-thick slice of medulla oblongata from neonatal mouse the preBötC continues producing periodic bursts of action potentials, termed population bursts that are thought to be important in generating various patterns of inspiration, in vivo. Whether gap junction communication contributes to preBötC rhythmogenesis remains unresolved, largely because existing gap junction uncouplers exert numerous non-specific effects (e.g., inhibition of active transport, alteration of membrane conductances). Here, we determined whether CBX alters preBötC rhythmogenesis by altering membrane properties including input resistance (Rin), voltage-gated Na+ current (INa), and/or voltage-gated K+ current (IK), rather than by blocking gap junction communication. To do so we used a medullary slice preparation, network-level recordings, whole-cell voltage clamp, and glycyrrhizic acid (GZA; a substance used as a control for CBX, since it is similar in structure and does not block gap junctions). RESULTS: Whereas neither of the control treatments [artificial cerebrospinal fluid (aCSF) or GZA (50 muM)] noticeably affected preBötC rhythmogenesis, CBX (50 muM) decreased the frequency, area and amplitude of population bursts, eventually terminating population burst production after 45-60 min. Both CBX and GZA decreased neuronal Rin and induced an outward holding current. Although neither agent altered the steady state component of IK evoked by depolarizing voltage steps, CBX, but not GZA, increased peak INa. CONCLUSION: The data presented herein are consistent with the notion that gap junction communication is important for preBötC rhythmogenesis. By comparing the effects of CBX and GZA on membrane properties our data a) demonstrate that depression of preBötC rhythmogenesis by CBX results from actions on another variable or other variables; and b) show that this comparative approach can be used to evaluate the potential contribution of other non-specific actions (e.g., Ca++ conductances or active transport) of CBX, or other uncouplers, in their alteration of preBötC rhythmogenesis, or the functioning of other networks.

A Review of a Workers' Compensation Database 2003 to 2013: Patient Factors Influencing Return to Work and Cumulative Financial Claims After Rotator Cuff Repair in Geriatric Workers' Compensation Cases.

BACKGROUND: Workers' compensation status is associated with poor outcomes after rotator cuff repair surgery. The purpose of this study was to analyze a database of geriatric workers' compensation patients after surgical repair of the rotator cuff and identify both medical and nonmedical patient factors that influence the time it takes for them to return to work at full duty, including a comparison of arthroscopic and open techniques. METHODS: An all workers' compensation database was queried for rotator cuff claims that were surgically managed using arthroscopic, open, or both approaches from 2003 to 2013 in patients aged ≥60. Primary outcomes were the number of days for return to full work (RTW) following surgery and the total reimbursement for health care. Multivariate analysis was performed, and data are presented as average ± standard deviation. RESULTS: The database yielded 1903 claims for surgically treated rotator cuff conditions (arthroscopic n = 935; open n = 926; both n = 42). In multivariate RTW analyses, we did not find a significant difference between groups (RTW in days was 153 ± 134 for arthroscopy [P = .81], 160 ± 160 for open [Ref], and 140 ± 82 days for both [P = .75]). However, multivariate analysis of reimbursement claims found arthroscopic surgery claims to be 13% higher compared to claims for open surgery only (US $29 986 ± 16 259 for arthroscopy vs US $26 495 ± 13 186 for open, P < .001). Patients aged ≥65 had more medical expenses than patients aged 60 to 64 (P = .03). Potentially modifiable variables that significantly prolonged RTW timing and higher health-care claims included need for vocational rehabilitation services and filing of a legal suit. CONCLUSIONS: Return to full-duty work in geriatric workers' compensation patients after rotator cuff repair takes about 5 months regardless of surgical approach and costs significantly more in patients aged ≥65. Arthroscopic repairs generated 13% more cumulative health-care costs than open surgery alone. More efficient vocational rehabilitation services and minimizing legal suits may help get patients back to work sooner and reduce overall costs.

Previous Rotator Cuff Repair Is Associated With Inferior Clinical Outcomes After Reverse Total Shoulder Arthroplasty.

BACKGROUND: Although recent evidence suggests that any prior shoulder surgery may cause inferior shoulder arthroplasty outcomes, there is no consensus on whether previous rotator cuff repair (RCR) is associated with inferior outcomes after reverse total shoulder arthroplasty (RTSA). PURPOSE: To retrospectively compare outcomes in patients who underwent RTSA with and without previous RCR. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Patients with prior RCR and those without previous shoulder surgery (control) who underwent RTSA for cuff tear arthropathy or irreparable cuff tear were retrospectively identified from a prospective database. Exclusion criteria included revision arthroplasty, fractures, rheumatoid arthritis, dislocations, infection, prior non-RCR procedures, less than 12 months of follow-up, and latissimus dorsi tendon transfer. The American Shoulder and Elbow Surgeons (ASES) score, ASES Activities of Daily Living (ADL) score, visual analog scale (VAS) score for pain, Subjective Shoulder Value (SSV), and range of motion (ROM) were compared between groups. RESULTS: Patients with previous RCR (n = 83 shoulders) were younger (mean ± SD, 67 ± 10 vs 72 ± 8 years; P < .001) and more likely to be male (46% vs 32%, P = .033) than controls (n = 189 shoulders). No differences were found in follow-up duration (25 ± 13 vs 26 ± 13 months, P = .734), body mass index, or any preoperative outcome variable or ROM measure. At final follow-up, patients with previous RCR had significantly lower ASES (76.5 [95% CI, 71.2-81.7] vs 85.0 [82.6-87.5], P = .015), lower SSV (76 [72-81] vs 86 [83-88], P < .001), worse pain (2.0 [1.4-2.6] vs 0.9 [0.6-1.1], P < .001), and less improvement in the ASES, ASES ADL, VAS, SSV, and forward elevation measures than controls. Multivariable linear regression analysis demonstrated that previous RCR was significantly associated with lower postoperative ASES score (B = -9.5, P < .001), lower ASES improvement (B = -7.9, P = .012), worse postoperative pain (B = 0.9, P = .001), worse improvement in pain (B = -1.0, P = .011), lower postoperative SSV (B = -9.2, P < .001), lower SSV improvement (B = -11.1, P = .003), and lower forward elevation ROM improvement (B = -12.7, P = .008). CONCLUSION: Patients with previous RCR attempts may experience fewer short-term gains in functional and subjective outcome scores after RTSA compared with patients with no history of shoulder surgery who undergo RTSA. However, the differences between groups were small and below the minimal clinically important differences for the outcome measures analyzed.

Peroneal Tendon Instability in Intra-Articular Calcaneus Fractures: A Retrospective Comparative Study and a New Surgical Technique.

OBJECTIVE: To compare the prevalence of peroneal tendon instability as determined by intraoperative evaluation versus preoperative computed tomography (CT) scans, and to identify specific risk factors that correlate with tendon instability. DESIGN: Retrospective comparative study. SETTING: Level 1 trauma hospital. PATIENTS: Patients with operatively treated intra-articular calcaneus fractures managed between January 1, 2002 and December 31, 2012 were reviewed for evidence of peroneal tendon instability. Of 254 fractures, 155 intra-articular calcaneus fractures met inclusion criteria and were available for final analysis. INTERVENTION: Operative notes were reviewed to confirm intraoperative testing for superior peroneal retinaculum (SPR) integrity and peroneal tendon stability. Preoperative CT scan and plain radiographs were evaluated for presence of peroneal tendon dislocation, fibular fracture or "fleck" sign, excessive lateral wall displacement, and/or calcaneal fracture-dislocation. MAIN OUTCOME MEASURES: Peroneal tendon stability was determined with intraoperative assessment of the intact SPR and its confluence with the peroneal tendon sheath. The incidence of peroneal tendon instability on intraoperative assessment was compared with preoperatively identified tendon dislocation on CT scan. Prevalence of peroneal tendon dislocation was determined using each diagnostic method. Risk factors for tendon instability were identified using a multivariate regression model. RESULTS: There was significantly higher prevalence of peroneal tendon instability as determined by preoperative imaging (30%; n = 47/155) compared with intraoperative retinaculum testing (11.6%; n = 18/155) (P < 0.001). Intraoperative tendon instability was significantly associated with increased fracture classification severity, fibular fracture/"fleck" sign, and fracture-dislocation. CONCLUSIONS: Intraoperative evaluation of the SPR should be used in conjunction with preoperative imaging for diagnosis of peroneal instability in the setting of operatively treated, intra-articular calcaneus fractures. LEVEL OF EVIDENCE: Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.