Nathanael Heckmann

Biomechanical effects of humeral neck-shaft angle and subscapularis integrity in reverse total shoulder arthroplasty

BACKGROUND The variability in functional outcomes and the occurrence of scapular notching and instability after reverse total shoulder arthroplasty remain problems. The objectives of this study were to measure the effect of reverse humeral component neck-shaft angle on impingement-free range of motion, abduction moment, and anterior dislocation force and to evaluate the effect of subscapularis loading on dislocation force. METHODS Six cadaveric shoulders were tested with 155°, 145°, and 135° reverse shoulder humeral neck-shaft angles. The adduction angle at which bone contact occurred and the internal and external rotational impingement-free range of motion angles were measured. Glenohumeral abduction moment was measured at 0° and 30° of abduction, and anterior dislocation forces were measured at 30° of internal rotation, 0°, and 30° of external rotation with and without subscapularis loading. RESULTS Adduction deficit angles for 155°, 145°, and 135° neck-shaft angle were 2° ± 5° of abduction, 7° ± 4° of adduction, and 12° ± 2° of adduction (P < .05). Impingement-free angles of humeral rotation and abduction moments were not statistically different between the neck-shaft angles. The anterior dislocation force was significantly higher for the 135° neck-shaft angle at 30° of external rotation and significantly higher for the 155° neck-shaft angle at 30° of internal rotation (P < .01). The anterior dislocation forces were significantly higher when the subscapularis was loaded (P < .01). CONCLUSIONS The 155° neck-shaft angle was more prone to scapular bone contact during adduction but was more stable at the internally rotated position, which was the least stable humeral rotation position. Subscapularis loading gave further anterior stability with all neck-shaft angles at all positions.

Spinopelvic mobility and acetabular component position for total hip arthroplasty

Aims Posterior tilt of the pelvis with sitting provides biological acetabular opening. Our goal was to study the post‐operative interaction of skeletal mobility and sagittal acetabular component position. Materials and Methods This was a radiographic study of 160 hips (151 patients) who prospectively had lateral spinopelvic hip radiographs for skeletal and implant measurements. Intra‐operative acetabular component position was determined according to the pre‐operative spinal mobility. Sagittal implant measurements of ante‐inclination and sacral acetabular angle were used as surrogate measurements for the risk of impingement, and intra‐operative acetabular component angles were compared with these. Results Post‐operatively, ante‐inclination and sacral acetabular angles were within normal range in 133 hips (83.1%). A total of seven hips (4.4%) had pathological imbalance and were biologically or surgically fused hips. In all, 23 of 24 hips had pre‐operative dangerous spinal imbalance corrected. Conclusions In all, 145 of 160 hips (90%) were considered safe from impingement. Patients with highest risk are those with biological or surgical spinal fusion; patients with dangerous spinal imbalance can be safe with correct acetabular component position. The clinical relevance of the study is that it correlates acetabular component position to spinal pelvic mobility which provides guidelines for total hip arthroplasty.

Biomechanical Evaluation of Coracoid Tunnel Size and Location for Coracoclavicular Ligament Reconstruction

PURPOSE The purpose of this study was to determine the effect of coracoid tunnel size and location on the biomechanical characteristics of cortical button fixation for coracoclavicular ligament reconstruction. METHODS Thirteen matched pairs of cadaveric scapulae were used to determine the effects of coracoid tunnel size, and 6 matched pairs were used to determine the effects of coracoid tunnel location. For tunnel size, a 4.5-mm hole was drilled in the base of the coracoid of one scapula and a 6-mm hole was drilled in the contralateral scapula. For tunnel location, 2 holes were drilled: (1) The first group received a hole centered in the coracoid base and a hole 1.5 cm distal from the first, along the axis of the coracoid. (2) The second group received holes that were offset anteromedially from the first set of holes (base eccentric and distal eccentric). A cortical button-suture tape construct was placed through each tunnel, and constructs were then loaded to failure. RESULTS For tunnel size specimens, load at ultimate failure was significantly greater for the 4.5-mm group compared with the 6-mm group (557.6 ± 48.5 N v 466.9 ± 42.2 N, P < .05). For tunnel location, load at ultimate failure was significantly greater for the centered-distal tunnel group compared with the eccentric-distal group (538.1 ± 70.2 N v 381.0 ± 68.6 N, P < .05). CONCLUSIONS A 4.5-mm tunnel in the coracoid provided greater strength for cortical button fixation than a 6-mm tunnel. In the distal coracoid, centered tunnels provided greater strength than eccentric tunnels. CLINICAL RELEVANCE When performing cortical button fixation at the coracoid process for coracoclavicular ligament reconstruction, a 4.5-mm tunnel provides greater fixation strength than a 6-mm tunnel. The base of the coracoid is more forgiving than the distal coracoid regarding location.

Preoperative risk factors for discharge to a postacute care facility after shoulder arthroplasty

BACKGROUND Shoulder arthroplasty procedures are becoming increasingly prevalent in the United States due to expanding indications and an aging population. Most patients are discharged home, but a subset of patients is discharged to a postacute care (PAC) facility. The purpose of this study was to identify the risk factors for discharge to a PAC facility after shoulder arthroplasty. METHODS The Nationwide Inpatient Sample discharge records from 2011 to 2012 were analyzed for patients who underwent a total shoulder arthroplasty (TSA) or reverse total shoulder arthroplasty (RTSA). Patient and hospital characteristics were identified. Univariate and multivariate analysis were used to determine the statistically significant risk factors for discharge to a PAC facility while controlling for covariates. RESULTS In 2011 and 2012, 103,798 patients underwent shoulder arthroplasty procedures: 58,937 TSAs and 44,893 RTSAs were identified. RTSA patients were 1.3 times as likely to be discharged to a PAC facility as TSA patients (P = .001). Medicare patients were 2 times as likely to be discharged to a PAC facility than those with private insurance (P < .001). In addition, women and patients presenting with a fracture, older age, or an increasing number of medical comorbidities were more likely to be discharged to a PAC facility (P < .001). CONCLUSION The risk factors identified in our study can be used to stratify patients at high risk for postoperative discharge to PAC, allowing for greater improvement in overall care and the facilitation of postoperative discharge planning.

Surgical management of midshaft clavicle nonunions is associated with a higher rate of short-term complications compared with acute fractures.

BACKGROUND Little is known about the perioperative complication rates of the surgical management of midshaft clavicle nonunions. The purpose of the current study was to report on the perioperative complication rates after surgical management of nonunions and to compare them with complication rates of acute fractures using a population cohort. METHODS The American College of Surgeons National Surgical Quality Improvement Program database was queried to identify patients who had undergone open reduction-internal fixation of midshaft clavicle fractures between 2007 and 2013. Patients were stratified by operative indication: acute fracture or nonunion. Patient characteristics and 30-day complication rates were compared between the 2 groups using univariate and multivariate analyses. RESULTS A total of 1215 patients were included in our analysis. Of these, 1006 (82.8%) were acute midshaft clavicle fractures and 209 (17.2%) were midshaft nonunions. Patients undergoing surgical fixation for nonunion had a higher rate of total complications compared with the acute fracture group (5.26% vs. 2.28%; P = .034). On multivariate analysis, patients with a nonunion were at a >2-fold increased risk of any postsurgical complication (odds ratio, 2.29 [95% confidence interval, 1.05-5.00]; P = .037) and >3-fold increased risk of a wound complication (odds ratio, 3.22 [95% confidence interval, 1.02-10.20]; P = .046) compared with acute fractures. CONCLUSION On the basis of these findings, patients undergoing surgical fixation for a midshaft clavicle nonunion are at an increased risk of short-term complications compared with acute fractures. This study provides additional information to consider in making management decisions for these common injuries.

Venous Thromboembolism Prophylaxis in Total Hip Arthroplasty and Total Knee Arthroplasty Patients: From Guidelines to Practice

Venous thromboembolism (VTE) prophylaxis is recommended for all patients undergoing total hip arthroplasty or total knee arthroplasty. The selection of an appropriate prophylaxis regimen represents a balance between efficacy and safety. To help orthopaedic surgeons select an appropriate VTE prophylaxis regimen for their patients, the American Academy of Orthopaedic Surgeons and the American College of Chest Physicians have developed guidelines. These guidelines do not recommend an optimal regimen, however. Rather, an individualized prophylaxis regimen that balances efficacy and safety is recommended for each patient, based on various risk factors. Because of a paucity of data and a lack of adequately powered head-to-head trials, implementing these guidelines can be challenging for the orthopaedic surgeon. Knowledge of the prophylaxis options and the VTE risk factors is paramount for developing an effective VTE prophylaxis algorithm for the surgeons practice.

Realtime Achilles Ultrasound Thompson (RAUT) Test for the Evaluation and Diagnosis of Acute Achilles Tendon Ruptures.

Background: Acute complete Achilles tendon ruptures are commonly missed injuries. We propose the Realtime Achilles Ultrasound Thompson (RAUT) test, a Thompson test under ultrasound visualization, to aid in the diagnosis of these injuries. We hypothesized that RAUT testing would provide improved diagnostic characteristics compared with static ultrasound. Methods: Twenty-two consecutive patients with operatively confirmed acute Achilles tendon ruptures were prospectively evaluated with RAUT testing and static ultrasonography. RAUT video recordings and static ultrasound images from both ruptured and uninjured sides were randomized and graded by a group of novice reviewers and a group of expert attendings. From these observations, sensitivity, specificity, positive predictive value, and negative predictive value for RAUT and static ultrasound were calculated. In addition, κ interobserver coefficients were computed. Forty-seven novice reviewers and 11 foot and ankle attendings made a total of 4136 and 528 observations, respectively. Results: For static ultrasound, sensitivity and specificity were 76.8% and 74.8% for the novice reviewers and 79.6% and 86.4% for the attendings, respectively. For RAUT testing, sensitivity and specificity were 87.2% and 81.1% for the novice group and 86.4% and 91.7% for the attending group, respectively. The κ coefficient was 0.62 and 0.27 for novice and attending RAUT reviewers, indicating substantial and fair agreement, respectively, but only 0.46 and 0.12 for static ultrasonography, representing moderate and slight agreement, respectively. Conclusion: RAUT testing was a sensitive and specific test, providing a cost-effective adjunct to the clinical examination when diagnosing acute Achilles tendon ruptures. This test can be used by surgeons with minimal training in ultrasonography. Level of Evidence: Level II, diagnostic study.

Surgical Approach and Anesthetic Modality for Carpal Tunnel Release A Nationwide Database Study With Health Care Cost Implications

Background: Carpal tunnel release (CTR) is commonly performed for carpal tunnel syndrome once conservative treatment has failed. Operative technique and anesthetic modality vary by surgeon preference and patient factors. However, CTR practices and anesthetic trends have, to date, not been described on a nationwide scale in the United States. Methods: The PearlDiver Patient Records Database was used to search Current Procedural Terminology codes for elective CTR from 2007 to 2011. Anesthetic modality (eg, general and regional anesthesia vs local anesthesia) and surgical approach (eg, endoscopic vs open) were recorded for this patient population. Cost analysis, patient demographics, regional variation, and annual changes in CTR surgery were evaluated. Results: We identified 86 687 patients who underwent carpal tunnel surgery during this 5-year time period. In this patient sample, 80.5% of CTR procedures were performed using general or regional anesthesia, compared with 19.5% of procedures performed using local anesthesia; 83.9% of all CTR were performed in an open fashion, and 16.1% were performed using an endoscopic technique. Endoscopic surgery was on average

Effect of Insurance on Rates of Total Ankle Arthroplasty Versus Arthrodesis for Tibiotalar Osteoarthritis

794 more expensive than open surgery, and general or regional anesthesia was

Utility of Postoperative Imaging in Radial Shaft Fractures.

654 more costly than local anesthesia. Conclusions: In the United States, open CTR under local anesthesia is the most cost-effective way to perform a CTR. However, only a small fraction of elective CTR procedures are performed with this technique, representing a potential area for significant health care cost savings. In addition, regional and age variations exist in procedure and anesthetic type utilized.