Search

Background: Reverse total shoulder arthroplasty changes the lines of action of the shoulder muscles, resulting in increases in the moment arms of the major abductors and flexors of the glenohumeral joint; however, at present little is known about the axial rotation capacity of the musculature after this procedure. The purpose of this study was to measure the instantaneous axial rotation moment arms of all of the major muscles spanning the glenohumeral joint during abduction and flexion after reverse total shoulder arthroplasty. Methods: Reverse total shoulder arthroplasty was performed on eight entire cadaveric upper extremities. Specimens were mounted onto a testing apparatus, and the internal/external rotation moment arms of eighteen major muscle subregions involving the subscapulars, supraspinatus, infraspinatus, teres minor, teres major, deltoid, pectoralis major, and latissimus dorsi were measured during abduction and flexion. These muscle moment arms were compared with those measured preoperatively in the anatomical shoulders (i.e., before the arthroplasty). Results: Reverse total shoulder arthroplasty resulted in loss of external rotation function in the posterior deltoid sub-region. Postoperatively, the inferior subscapulars subregion had the largest internal rotation moment arm overall, whereas the teres minor and the inferior infraspinatus subregion had the greatest external rotation moment arms. The teres minor, infraspinatus, and deltoid subregions were external rotators during abduction, whereas only the teres minor, infraspinatus, and to a small extent the posterior deltoid subregion were external rotators during flexion. Conclusions: Reverse total shoulder arthroplasty results in an overall decrease in the external rotation moment arm of the deltoid and increases in the moment arms of the major internal rotators, including the latissimus dorsi and pectoralis major. Reverse total shoulder arthroplasty may result in complete loss of external rotation function if the teres minor and infraspinatus muscles are damaged. Clinical Relevance: Care should be taken to avoid damaging the infraspinatus and the teres minor during a reverse shoulder arthroplasty, as these are the only major external rotators after that procedure. Greater external rotation may be achieved postoperatively when the humerus is positioned in the coronal plane rather than the sagittal plane. [ABSTRACT FROM AUTHOR]

Background: Reverse total shoulder arthroplasty is known to increase the moment arm of the middle subregion of the deltoid during shoulder abduction; however, at present, comprehensive data regarding the shoulder muscle moment arm through the full range of abduction and flexion are not available. The purpose of this study was twofold: (1)to measure the instantaneous moment arms of thirteen subregions of major muscles spanning the glenohumeral joint during abduction and flexion of the shoulder after reverse total shoulder arthroplasty and (2) to compare these data with the muscle moment arms previously measured preoperatively in the anatomical shoulders. Methods: Reverse total shoulder arthroplasty was performed on eight entire cadaveric upper extremities. The specimens were mounted onto a dynamic testing apparatus, and the instantaneous abductor/adductor and flexor/extensor moment arms of subregions of the deltoid, latissimus dorsi, pectoralis major, teres major, and subscapularis muscles (a total of thirteen subregions) were measured with use of the tendon excursion method. These muscle moment arms were compared with those measured preoperatively in the anatomical shoulders. Results: Reverse total shoulder arthroplasty resulted in significant increases in the abductor moment arms of the anterior subregion of the deltoid (mean increase = 10.4 mm; 95% confidence interval = 7.5 to 13.3 mm) and the middle subregion of the deltoid (mean increase = 15.5 mm; 95% confidence interval = 10.8 to 20.3 mm) as well as recruitment of the posterior subregion of the deltoid as an abductor. The superior subregion of the pectoralis major (the clavicular fibers) and anterior subregion of the deltoid were the most effective flexors and had a substantial potential to initiate flexion. The adductor and extensor moment arms of the teres major, latissimus dorsi subregions, and inferior and middle subregions of the pectoralis major increased substantially after the arthroplasty. The subscapularis subregions behaved as extensors, abductors, and adductors after the arthroplasty; this was in contrast to their roles in the anatomical shoulder, in which they were mainly flexors and adductors. Conclusions: Reverse total shoulder arthroplasty increases the moment arms of the major abductors, flexors, adductors, and extensors of the glenohumeral joint, thereby reducing muscle effort during common tasks such as lifting and pushing. [ABSTRACT FROM AUTHOR]

Instruments that are useful in clinical or research practice will, when the object of measurement is stable, yield similar results when applied at different times, in different situations, or by different users. Studies that measure the relation of differences between patients or subjects and measurement error (reliability studies) are becoming increasingly common in the orthopaedic literature. In this paper, we identify common aspects of reliability studies and suggest features that improve the reader's confidence in the results. One concept serves as the foundation for all further consideration: in order for a reliability study to be relevant, the patients, raters, and test administration in the study must be similar to the clinical or research context in which the instrument will be used. We introduce the statistical measures that readers will most commonly encounter in reliability studies, and we suggest an approach to sample-size estimation. Readers interested in critically appraising reliability studies or in developing their own reliability studies may find this review helpful. [ABSTRACT FROM AUTHOR]

Objectives: There is substantial variation in the classification and management of scapula fractures. The first purpose of this study was to analyze the interobserver reliability of the OTA/AO classification and the New International Classification for Scapula Fractures. The second purpose was to assess the proportion of agreement among orthopaedic surgeons on operative or nonoperative treatment., Design: Web-based reliability study., Setting: Independent orthopaedic surgeons from several countries were invited to classify scapular fractures in an online survey., Participants: One hundred three orthopaedic surgeons evaluated 35 movies of three-dimensional computerized tomography reconstruction of selected scapular fractures, representing a full spectrum of fracture patterns., Main Outcome Measurements: Fleiss kappa (κ) was used to assess the reliability of agreement between the surgeons., Results: The overall agreement on the OTA/AO classification was moderate for the types (A, B, and C, κ = 0.54) with a 71% proportion of rater agreement (PA) and for the 9 groups (A1 to C3, κ = 0.47) with a 57% PA. For the New International Classification, the agreement about the intraarticular extension of the fracture (Fossa (F), κ = 0.79) was substantial and the agreement about a fractured body (Body (B), κ = 0.57) or process was moderate (Process (P), κ = 0.53); however, PAs were more than 81%. The agreement on the treatment recommendation was moderate (κ = 0.57) with a 73% PA., Conclusions: The New International Classification was more reliable. Body and process fractures generated more disagreement than intraarticular fractures and need further clear definitions.

Objectives: To evaluate the effect of negative pressure wound therapy (NPWT) on deep infection rate in open tibial fractures., Design: Retrospective cohort study. Data was collected from medical records and radiographs., Setting: Two level-1 trauma centers., Patients/participants: Patients who sustained an open tibial fracture which underwent delayed soft tissue coverage between January 2002 and December 2007 were included. Exclusion criteria included open fractures receiving a combination of NPWT and conventional dressings, fractures which were treated with a primary amputation, and fractures associated with mortality., Intervention: : NPWT with reticulated open cell foam or conventional dressings at surgeon's discretion., Main Outcome Measurement: Deep infection rate., Results: A total of 229 open tibial fractures in 220 patients met the inclusion criteria and received either NPWT (166/229-72%) or conventional dressings (63/229-28%). There was a decreased rate of deep infection in the NPWT group compared with the conventional dressing group [8.4% (14/166) vs. 20.6% (13/63); P = 0.01]. Univariate predictors of deep infection included Gustilo type {odds ratio (OR): 3.13 [95% confidence interval (CI): 1.74-5.64]; P < 0.001} and use of NPWT [OR: 0.35 (95% CI: 0.16-0.80); P = 0.01]. When adjustment was performed for Gustilo type with multivariate analysis, use of NPWT was found to reduce the risk of deep infection by almost 80% [OR: 0.22 (95% CI: 0.09-0.55); P = 0.001]., Conclusions: These results suggest that NPWT reduces the rate of deep infection when used for the dressing of traumatic wounds in open tibial fractures., Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Background: An intramedullary screw (Portland Orthopaedics, St. Clair, MI) and Inion (Tampere, Finland) Orthopaedic Trauma Plating System (OTPS) mesh for use for internal fixation of fractured ribs have not previously undergone biomechanical testing. The aim of this study is to compare the biomechanics of intact ribs undergoing four-point bending to the biomechanics of fractured ribs fixed with each of the two devices to determine which device provides superior fixation., Study: Thirty fresh-frozen porcine ribs (ribs 6-8) were submitted to four-point bending to failure, at a rate of 2.5 mm/min, to determine stiffness and force at failure. The ribs were then randomized to receive fixation with either Inion OTPS mesh or an intramedullary screw. The fixated ribs were again submitted to four-point bending to failure., Results: Ribs fixated with OTPS mesh were significantly stiffer and failed at a significantly higher load than ribs fixated with intramedullary screws (p = 0.0001). Ribs fixated with OTPS mesh were less stiff than intact ribs but failed at a similar force to intact ribs., Conclusion: The Inion OTPS mesh system provides superior fixation of fractured ribs compared with an intramedullary screw when tested with four-point bending. The OTPS mesh system also has the added advantage of being absorbable. The intramedullary screw needs to undergo modification and further testing before use in humans. Future studies should focus on more physiologic methods of loading.

Objective: To determine predictors of moderate or severe pain 6 months after orthopaedic injury., Design: Prospective cohort study., Setting: Two adult level 1 trauma centers in Victoria, Australia., Participants: A total of 1290 adults admitted with orthopaedic injuries and registered by the Victorian Orthopaedic Trauma Outcomes Registry., Main Outcome Measures: Participant self-reported pain and health status using an 11-point numerical rating scale and the 12-item Short-Form health survey, respectively., Results: The prevalence of moderate or severe pain was 48% [95% confidence interval (CI), 45-51] at discharge and 30% (95% CI, 28-33) at 6 months postinjury. Failure to complete high school [adjusted odds ratio (AOR) 1.5 (95% CI, 1.1-1.9)], self-reported preinjury pain-related disability [AOR 1.8 (95% CI, 1.3-2.5)], eligibility for compensation [AOR 2.1 (95% CI, 1.6-2.8)], and moderate or severe pain at discharge from the acute hospital [AOR 2.4 (95% CI, 1.8-3.1)] were found to be independent predictors of moderate or severe pain at 6 months postinjury., Conclusions: Moderate or severe pain is commonly reported 6 months after orthopaedic trauma. Pain intensity at discharge and the effects of a "no-fault" compensation system are potentially modifiable factors that might be addressed through intervention studies to reduce the burden of persistent pain after orthopaedic trauma.