Contributions of the Abductor Muscles to Rotational and Distractive Stability of the Hip in a Biomechanical Cadaveric Model.

Background: The gluteus minimus (GMin) and gluteus medius (GMed) are important dynamic stabilizers of the hip, but quantitative data on their biomechanical roles in stabilizing the hip are currently lacking. Purpose: To (1) establish a reproducible biomechanical cadaveric model of the hip abductor complex and (2) characterize the effects of loading the GMin and GMed on extraneous femoral rotation and distraction. Study Design: Controlled laboratory study. Methods: A total of 10 hemipelvises were tested in 4 muscle loading states: (1) unloaded, (2) the GMin loaded, (3) the GMed loaded, and (4) both the GMin and GMed loaded. Muscle loads were applied via cables, pulleys, and weights attached to the tendons to replicate the anatomic lines of action. Specimens were tested under internal rotation; external rotation; and axial traction forces at 0°, 15°, 30°, 60°, and 90° of hip flexion. Results: When loaded together, the GMin and GMed reduced internal rotation motion at all hip flexion angles (P < .05) except 60° and reduced external rotation motion at all hip flexion angles (P < .05) except 0°. Likewise, when both the GMin and GMed were loaded, femoral distraction was decreased at all angles of hip flexion (P < .05). Conclusion: The results of this study demonstrated that the GMin and GMed provide stability against rotational torques and distractive forces and that the amount of contribution depends on the degree of hip flexion. Clinical Relevance: Improved understanding of the roles of the GMin and GMed in preventing rotational and distractive instability of the hip will better guide treatment of hip pathologies and optimize nonoperative and operative therapies.

All-Arthroscopic Anatomic Length-Tension Biceps Tenodesis With Unicortical Button.

The long head of the biceps tendon is a frequent cause of persistent anterior shoulder pain. Biceps tenodesis is a popular choice for surgical management of this pathology, with myriad approach and fixation variations described. We describe an all-arthroscopic suprapectoral biceps tenodesis in the anatomic length-tension relation using a unicortical button. This technique offers an alternative method that provides proper tendon fixation at anatomic length with minimized additional surgical morbidity and postoperative complications.

Multi-ligament reconstructions as a risk factor for adverse outcomes in arthroscopic surgery.

PURPOSE: Multi-ligament knee injuries are a serious consequence of knee dislocation with a poorly evaluated post-operative complication profile due to low incidence. The aim of this study is to assess the risk of adverse post-operative events associated with operative management of multi-ligament knee injuries. METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was used to identify patients undergoing surgical procedures for multi-ligament knee injuries from 2006 to 2016 using Current Procedural Terminology codes. We evaluated data on patient demographics and used a propensity score algorithm to adjust for baseline differences in these patients and developed univariate and multivariate logistic regression models to assess effects on minor and severe 30-day post-operative complications. RESULTS: We identified 444 patients in this database who underwent multi-ligament knee reconstructions between 2006 and 2016. After propensity matching, minor and major adverse post-operative events were more frequent in patients with multi-ligament knee injuries (1.4% vs 0.2%, p < 0.001 and 2.7% vs 1.1%, p = 0.002, respectively). Patients with multi-ligament knee injuries experienced a 55-fold increase risk of need for transfusion (p < 0.001) and a fivefold increased risk of pulmonary embolism (p = 0.025), with most occurring in bicruciate reconstructions (Schenck Classification KD-III and KD-IV injuries). CONCLUSION: The surgical management of multi-ligament knee injuries confers significant increased risk of 30-day post-operative minor or severe adverse event over arthroscopic ACL reconstruction. These patients are most at risk for post-operative blood transfusion requirement, and pulmonary embolism, with patient's undergoing surgery for bicruciate ligament injuries at particularly high risk of complication. LEVEL OF EVIDENCE: IV.

Anterior Lumbar Interbody Fusion With Cement Augmentation Without Posterior Fixation to Treat Isthmic Spondylolisthesis in an Osteopenic Patient-A Surgical Technique.

BACKGROUND: Anterior lumbar interbody fusion (ALIF) has been well established as an effective surgical intervention for chronic back pain due to osteoporotic vertebral collapse. Historically, ALIF has consisted of an anterior approach to disc height restoration with a subsequent posterior pedicle screw fixation. Although the applications of cement augmentation with posterior fixation have been previously reported, treatment of patients with both isthmic spondylolisthesis and decreased bone mineral density using a stand-alone ALIF is controversial because of concerns for decreased fusion rates and increased subsidence risk, respectively. We report a case of stand-alone ALIF used to treat a low-grade isthmic spondylolisthesis in the setting of idiopathic thoraco-lumbar scoliosis in a patient with secondary degenerative changes and discuss the benefits of this surgical technique in a patient with several comorbidities. METHODS: An osteopenic 66-year-old woman with multiple medical comorbidities and 2 years of left radicular leg pain was found to have a Myerding grade I isthmic spondylolisthesis in the setting of idiopathic thoraco-lumbar scoliosis with secondary changes. The patient underwent an L5-S1 stand-alone ALIF with anterior cement augmentation without posterior pedicle screw fixation. RESULTS: The patient experienced immediate relief of radicular leg pain postoperatively and had an uneventful course. At 2 years follow-up, she remained symptom free, and radiographs showed excellent fusion and maintenance of intervertebral disc height. CONCLUSIONS: The use of stand-alone ALIF with anterior cement augmentation of the vertebral bodies is a surgical technique that could produce excellent improvement in patients with low-grade isthmic spondylolisthesis in the setting of osteopenia. The use of the all-anterior approach in similar patients with multiple medical comorbidities can also be a useful technique, as it decreases associated morbidity of surgery and complication risks associated with prolonged operative times.

S2 Alar Iliac Fixation in Long Segment Constructs, a Two- to Five-Year Follow-up.

STUDY DESIGN: Retrospective review of patients having undergone S2 alar-iliac (S2AI) fixation for long fusions with a minimum two-year follow-up. OBJECTIVES: To report on fusion rates, complications, technique-specific complications of patients having undergone S2AI fixation. SUMMARY OF BACKGROUND DATA: Sacropelvic fixation continues to be a challenge when performing long fusions to the pelvis. S2AI screws have been found to provide solid biomechanical fixation and have been found to have good clinical results in short-term follow-up for pediatric and adult patients. METHODS: Cases were retrospectively reviewed in patients who had placement of S2AI screws for long fusions with at least a two-year follow-up. Demographic data, complications, and reoperations were reviewed. Complications were broken into minor and major categories similar to previous series on pelvic fixation. RESULTS: There were 86 cases identified. Minor and major complications occurred in 29% and 24% of patients, respectively, with the majority of minor complications being intraoperative dural tears. Revision surgery for all causes was performed in 23% of the cohort. Fusion rate at L5-S1 for patients without preoperative pseudarthrosis was 95.3%. Preoperative L5-S1 pseudoarthrosis was identified in 20 patients, 17 (95%) of these went onto fusion after one surgery. There was evidence of S2AI screw lucency in 10.4% of cases. However, the majority of these were asymptomatic. CONCLUSIONS: Sacropelvic fixation using the S2AI technique provides safe, durable fixation with low rates of technique-specific complications and limited need for hardware removal. Complication rates in this series were similar to other series on long fusions to the pelvis. Additionally, fusion rates were high at L5-S1 for both patients with and without preoperative L5-S1 pseudarthrosis. It appears that the S2AI technique is a powerful option for patients with previous L5-S1 pseudarthrosis. LEVEL OF EVIDENCE: Level III.