Three-dimensional analysis of spinal deformity correction in adolescent idiopathic scoliosis: comparison of two distinct techniques.

PURPOSE: To compare 3D postoperative deformity correction using two distinct commonly utilized techniques for the treatment of adolescent idiopathic scoliosis (AIS). METHODS: AIS patients with major thoracic (Lenke 1-2) curves at two sites who underwent deformity correction via posterior spinal instrumented fusion using one of two distinct techniques were retrospectively reviewed. Patients were matched 1:1 between sites for Lenke type (95% Lenke 1) and follow-up time. The "band site" performed posteromedial translation using thoracic sublaminar bands and 5.5-mm rods. The "screw site" performed spine derotation using differential rod contouring with pedicle screws and 5.5-mm rods. 3D measures of deformity from spinal reconstructions were compared between sites. RESULTS: Preoperatively, the groups had similar thoracic curve magnitudes (band, 55 ± 12° vs. screw, 52 ± 10°; p > 0.05); the "screw site" had less T5-T12 kyphosis (2 ± 14° vs. 7 ± 12°, p = 0.05) and greater thoracic apical rotation (- 19 ± 7° vs. - 14 ± 8°, p = 0.007). Postoperatively, the "screw site" had greater percent correction (61% vs. 76%, p < 0.001) and kyphosis restoration (p = 0.002). The groups achieved a similar amount of apical derotation (p = 0.9). The "band site" used cobalt chromium rods exclusively; the "screw site" used cobalt chromium (3%) and stainless steel (97%; p < 0.001). The "band site" performed significantly longer fusions. CONCLUSIONS: Significant variations were found between two commonly utilized techniques in AIS surgery, including rod material, correction mechanisms, and fusion levels. Significantly, a greater 3D deformity correction of the coronal and sagittal planes was observed at the "screw site" compared to the "band site", but with no difference in axial plane correction.

Decoupled epineurial and axonal deformation in mouse median and ulnar nerves.

INTRODUCTION: Peripheral nerves accommodate mechanical loads during joint movement. Hypothesized protective features include increased nerve compliance near joints and axonal undulation. How axons perceive nerve deformation is poorly understood. We tested whether nerves increase local axonal undulation in regions of high epineurial strain to protect nerve fibers from strain-induced damage. METHODS: Regional epineurial strain was measured near the elbow in median and ulnar nerves of mice expressing axonal fluorescence before and after decompression. Regional axonal tortuosity was quantified under confocal microscopy. RESULTS: Nerves showed higher epineurial strain just distal to the medial epicondyle; these differences were eliminated after decompression. Axonal tortuosity also varied regionally; however, unlike in the epineurium, it was greater in proximal regions. DISCUSSION: In this study we have proposed a neuromechanical model whereby axons can unravel along their entire length due to looser mechanical coupling to the peri/epineurium. Our findings have major implications for understanding nerve biomechanics and dysfunction. Muscle Nerve 59:619-619, 2019.

Comparison of Surgical Outcomes Between a Triplane Proximal Femoral Osteotomy and the Modified Dunn Procedure for Stable, Moderate to Severe Slipped Capital Femoral Epiphysis.

BACKGROUND: Recent studies have demonstrated the intra-articular cartilage and labral damage that can occur from the proximal femoral cam-like deformity of a moderate to severe slipped capital femoral epiphysis (SCFE). The approach to treating this deformity in a symptomatic Loder stable hip is controversial. The purpose of this study was to compare radiographic outcomes, complication rates, and revision rates between Imhauser type triplane proximal femoral osteotomy (TPFO) and the modified Dunn procedure (MDP). METHODS: Twenty-six subjects with minimum 1-year follow-up were included (12 treated with a TPFO, and 14 treated with the MDP). A chart review was performed to capture data related to complications, revision procedures, surgical time, and body mass index. Radiographs were measured preoperatively and at final follow-up to evaluate epiphyseal-slip angle, neck-shaft angle, articular surface to trochanter distance, and medial proximal femoral angle. RESULTS: Surgical time was shorter for the TPFO group (150.0±57.4 min) compared with the MDP group (203.8±30 min) (P=0.005). All preoperative and postoperative radiographic measures were similar between the 2 groups except postoperative neck-shaft angle, which was significantly less in the TPFO group (129.7±8.6 vs. 140.9±9.4 degrees) (P=0.005). There were no cases of femoral head avascular necrosis (AVN) in the TPFO group. The modified Dunn group had a 29% AVN rate (P=0.1). The overall complication rate was similar between the TPFO (33%) and modified Dunn (36%) groups (P=1.0) and the reoperation rate was slightly greater in the TPFO group (33%) as compared with the modified Dunn group (21%) (P=0.67). CONCLUSIONS: The complex 3-dimensional proximal femoral deformity of a moderate to severe SCFE can be difficult to treat with relatively high complication/reoperation rates observed in both TPFO and MDP groups. All 4 instances of AVN in this study of stable slips, however, were in the MDP group. As this can be a devastating complication leading to early total hip arthroplasty, we advise against the MDP in stable SCFE patients. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Dynamic "Homemade" Digital External Fixators for Proximal Interphalangeal Joint Injuries.

The purpose of this article is to discuss the indications and surgical techniques of "homemade" digital external fixators constructed from easily available and inexpensive hardware (K-wires and dental rubber bands).

How Do Preoperative Medications Influence Outcomes After Total Joint Arthroplasty?

BACKGROUND: Recent health care policy changes require hospitals and physicians to demonstrate improved quality. In 2012, a prospective database was formed with the Blue Cross and Blue Shield of Michigan to improve quality of care. The purpose of this study was to analyze patient preoperative medication as predictors of outcomes after total joint arthroplasty. METHODS: Data were collected on patient's preoperative medications from 2012 to 2015 using a total joint arthroplasty database. Medications were categorized as antiplatelet, antimicrobial, anticoagulant, narcotic, steroid, insulin, or oral diabetes medication. Outcomes included hospital length of stay (LOS), discharge disposition/destination, and 90-day readmission. Univariate and multivariate regression analyses were performed. RESULTS: A total of 3959 patients were studied. Eighty percent (3163 patients) were discharged home. The remainder (795) went to an extended-care facility (ECF). Patients discharged to an ECF were taking more medications (1.13 vs 0.80 in total knee arthroplasty; 1.18 vs 0.83 in total hip arthroplasty; P <.001). Patients who were readmitted took more medications (1.0 vs 0.85; P <.01). There were more discharges to an ECF in narcotic, steroid, and diabetes medication users. Patients taking anticoagulants, narcotics, insulin, and antiplatelets had greater readmission rates. There was a significant correlation between the number of medications and an increased LOS. CONCLUSION: Patients taking more medications were more frequently discharged to an ECF and had increased LOS and readmission rates. Narcotics and diabetic medications had the greatest influence. Category and quantity of preoperative medications can be used as predictors of outcomes after arthroplasty surgery.

The Effect of Comorbidities on Discharge Disposition and Readmission for Total Joint Arthroplasty Patients.

BACKGROUND: As the annual demand and number of total joint arthroplasty cases increase, so do concerns of outcomes of patient with specific comorbidities relative to outcomes and costs of care. METHODS: The study cohort included 2009 primary total knee arthroplasty (TKA) patients and 905 total hip arthroplasty patients. Discharge disposition was classified as discharge to any facility or home. The comorbidities of the patients who were readmitted and those without a 90-day event were also evaluated. RESULTS: In the TKA population, age, female gender, nonsmoking status, venous thromboembolism (VTE) history, and diabetes were significantly associated with discharge to extended care facility (ECF) on univariate analysis, unlike body mass index. With multivariate analyses, female gender, age, VTE history, and diabetes were associated with ECF placement, but smoking was not. In the total hip arthroplasty population, age, female gender, and nonsmoking status were significantly associated with discharge to ECF on univariate analysis, whereas body mass index, diabetes, and VTE history were not. On multivariate analyses, female gender and age were associated with ECF, but smoking was not. The only significant finding for the readmission data was an increased rate of readmission for TKA patients of older age. CONCLUSION: The potential of projecting patient discharge and readmission allows physicians to counsel patients and improve patient expectations.

The Evaluation of Comorbidities Relative to Length of Stay for Total Joint Arthroplasty Patients.

BACKGROUND: The ability to identify those at risk for longer inpatient stay helps providers with postoperative planning and patient expectations. Decreasing length of stay (LOS) in the future will be determined by appropriate patient selection, risk stratification, and preoperative patient optimization. The purpose of this study was to identify factors that place patients at risk for extended postoperative LOSs. METHODS: The study cohort included 2009 primary total knee arthroplasty (TKA) patients and 905 total hip arthroplasty (THA) patients. Patient comorbidities were prospectively identified and the LOS for each patient was tracked after a primary arthroplasty. Statistical analysis was performed to correlate which comorbidities were associated with longer inpatient stays. RESULTS: In the TKA population, gender, smoking status, venous thromboembolism history, body mass index, and diabetes status were not found to be a significant predictor for the LOS. Age was found to be a factor in univariate regression testing (P < .001). In the THA population, univariate testing showed female gender (P < .001), smoking status (P = .002), and age (P < .001) to be factors, but like the TKA population, venous thromboembolism history or diabetes status was not significant. In THA multivariate analysis, age (P < .001) and female gender (P = .018) continued to be factors, but smoking was determined to be a confounding variable. CONCLUSION: Age and gender were associated with a longer LOS after THA, whereas only age was a significant factor after TKA. Development of age-adjusted LOS models may help aid patient expectations and risk management.

Regional Ulnar Nerve Strain Following Decompression and Anterior Subcutaneous Transposition in Patients With Cubital Tunnel Syndrome.

PURPOSE: Simple decompression and anterior subcutaneous transposition are effective surgical interventions for cubital tunnel syndrome and yield similarly favorable outcomes. However, a substantial proportion of patients demonstrate unsatisfactory outcomes for reasons that remain unclear. We compared effects of decompression and transposition on regional ulnar nerve strain to better understand the biomechanical impacts of each strategy. METHODS: Patients diagnosed with cubital tunnel syndrome and scheduled for anterior subcutaneous transposition surgery were enrolled. Simple decompression, circumferential decompression, and anterior transposition of the ulnar nerve were performed during the course of the transposition procedure. Regional ulnar nerve strain around the elbow was measured for each surgical intervention based on 4 wrist and elbow joint configurations. RESULTS: With elbow extension at 180°, both circumferential decompression and anterior transposition resulted in approximately 68% higher nerve strains than simple decompression. Conversely, with elbow flexion, simple decompression resulted in higher average strains than anterior transposition. Limited regional differences in strain were observed for any surgical intervention with elbow extension. However, with elbow flexion, strains were higher in distal and central regions compared with the proximal region within all surgical groups, and proximal region strain was higher after simple decompression compared with anterior transposition. CONCLUSIONS: As predicted by the altered anatomic course, anterior transposition results in lower ulnar nerve strains than simple decompression during elbow flexion and higher nerve strains during elbow extension. Irrespective of anatomic course, circumferential release of paraneurial tissues may also influence nerve strain. Nerve strain varies regionally and is influenced by surgery and joint configuration. CLINICAL RELEVANCE: Our data provide insight into how surgery resolves and redistributes traction on the ulnar nerve. These findings may help inform which surgical procedure to perform for a specific patient, guide rehabilitation protocols, and suggest regions of anatomic concern during index and revision surgery.

Intraoperative Periprosthetic Femur Fracture: A Biomechanical Analysis of Cerclage Fixation.

Intraoperative periprosthetic femur fracture is a known complication of total hip arthroplasty (THA) and a variety of cerclage systems are available to manage these fractures. The purpose of this study was to examine the in situ biomechanical response of cerclage systems for fixation of periprosthetic femur fractures that occur during cementless THA. We compared cobalt chrome (CoCr) cables, synthetic cables, monofilament wires and hose clamps under axial compressive and torsional loading. Metallic constructs with a positive locking system performed the best, supporting the highest loads with minimal implant subsidence (both axial and angular) after loading. Overall, the CoCr cable and hose clamp had the highest construct stiffness and least reduction in stiffness with increased loading. They were not demonstrably different from each other.

The Effect of Abnormal Vitamin D Levels in Athletes.

Vitamin D is a lipophilic prohormone integral to musculoskeletal, autoimmune, oncologic, cardiovascular, and mental health. Of particular importance to the orthopedic surgeon is the role of vitamin D in the regulation of bone mass, muscle strength, and physical performance. Although vitamin D-related skeletal pathologies are rare in industrialized nations, emerging research in the field has shown that most American adults have inadequate levels of vitamin D. Even among athletes, there is a high prevalence of vitamin D deficiency, which may place competitors at risk of stress fractures, illness, and delayed muscle recovery. Adequately identifying vitamin D-deficient individuals in need of supplementation is important to help optimize performance and prevent future injury. The goal of this review is to describe the epidemiology of vitamin D deficiency and its effects on athletic performance and musculoskeletal health. Future double-blinded studies of vitamin D supplementation in athletes are needed. We recommend treating athletes who have insufficient or deficient vitamin D levels.