The Effect of Surgical Positioning on Pneumocephalus in Subthalamic Nucleus Deep Brain Stimulation Surgery for Parkinson Disease

OBJECTIVES

This research analyzed the effect of surgical positioning on postoperative pneumocephalus and assessed additional potential risk factors of pneumocephalus in subthalamic nucleus (STN) deep brain stimulation (DBS) for Parkinson disease (PD).

MATERIALS AND METHODS

In this study, 255 consecutive patients with PD who received bilateral STN DBS under general anesthesia were retrospectively included. Of these, 180 patients underwent surgery with their heads in an elevated position, and 75 patients underwent surgery in a supine position. The postoperative pneumocephalus volume was compared between the two groups. Other potential risk factors for pneumocephalus also were analyzed.

RESULTS

The mean pneumocephalus volume for the group with elevated-head positioning (16.76 ± 15.23 cm3) was greater than for the supine group (3.25 ± 8.78 cm3) (p < 0.001). Multivariable analysis indicated that the pneumocephalus volume was related to surgical positioning, lateral trajectory angle, intraoperative mean arterial pressure (MAP), microelectrode recording (MER) passage number, brain atrophy degree, and the anterior trajectory angle. No correlation was found between pneumocephalus and age, sex, duration of PD, surgery length, or intracranial volume. In the subgroup analysis, the pneumocephalus volume exhibited a negative correlation with intraoperative MAP (r = -0.210, p = 0.005) and positive correlations with degree of brain atrophy (r = 0.242, p = 0.001) and MER passage number (r = 0.184, p = 0.014) in the elevated-head group. Specifically, an MER passage number > 3 was a significant risk factor for pneumocephalus in the elevated-head group. A positive correlation was observed between the pneumocephalus volume and the lateral trajectory angle in both groups (elevated-head positioning, r = 0.153, p = 0.041; supine positioning, r = 0.546, p < 0.001).

CONCLUSIONS

In patients with PD who were anesthetized and receiving STN DBS, supine positioning reduced pneumocephalus volume compared with patients with PD receiving STN DBS with their heads elevated. The pneumocephalus volume was negatively correlated with intraoperative MAP and positively correlated with the degree of brain atrophy, the lateral trajectory angle, and the MER passage number.

The biomechanical implications of neck position in cervical contusion animal models of SCI

Large animal contusion models of spinal cord injury are an essential precursor to developing and evaluating treatment options for human spinal cord injury. Reducing variability in these experiments has been a recent focus as it increases the sensitivity with which treatment effects can be detected while simultaneously decreasing the number of animals required in a study. Here, we conducted a detailed review to explore if head and neck positioning in a cervical contusion model of spinal cord injury could be a factor impacting the biomechanics of a spinal cord injury, and thus, the resulting outcomes. By reviewing existing literature, we found evidence that animal head/neck positioning affects the exposed level of the spinal cord, morphology of the spinal cord, tissue mechanics and as a result the biomechanics of a cervical spinal cord injury. We posited that neck position could be a hidden factor contributing to variability. Our results indicate that neck positioning is an important factor in studying biomechanics, and that reporting these values can improve inter-study consistency and comparability and that further work needs to be done to standardize positioning for cervical spinal cord contusion injury models.

Management of Femoral Shaft Fractures: The Significance of Traction or Operative Position

Background and objective Intramedullary femoral nailing (IMN) is the gold standard for managing femoral shaft fractures (FSFs). Though good clinical outcomes and union rates have been reported following this procedure, it has also been commonly associated with perioperative complications. Positioning the patient in lateral decubitus, avoiding a fracture table, or using manual traction have been touted as possible techniques to reduce perioperative complications in IMN. However, given the scarce availability of comparative research, the decision to employ any of the techniques mentioned above is often guided by surgeon preference alone. In light of this, the purpose of this study was to determine whether the use of free-leg draping using either supine or direct lateral positioning with manual traction reduces perioperative complications among trauma patients undergoing an anterograde femoral nailing surgery when compared to using a fracture table. Methods Consecutive adult patients from a level-one trauma center undergoing unilateral antegrade femoral fixation surgeries between 2016 and 2020 were retrospectively evaluated for possible inclusion in the study. Relevant perioperative and postoperative data, including length of hospital or ICU stay and perioperative complications, were included in the analysis. This study received research ethics board approval before data collection began. Results A total of 91 patients were ultimately included in the final analysis: 61 patients were included in the free-leg draping with manual traction group (FL) and 30 patients were included in the traction table group (TT). Patients in the FL group had a similar operative and fluoroscopy time, blood loss, length of stay, and time on the ventilator. Subgroup analysis comparing positioning within the FL group revealed non-significant differences in fluoroscopy time (p=0.59) and length of stay (p=0.20) between the lateral and supine groups. Moreover, no differences in operative time, blood loss, and time on the ventilator were observed between lateral and supine groups. Conclusion Based on our findings, there were no significant differences in terms of operative or fluoroscopy time, perioperative complications, or length of time in the hospital or on the ventilator between the groups. Our study was limited by its small sample size and incomplete data. Further prospective randomized research is required to reach definitive conclusions on the appropriate manner to treat patients with these complex and morbid injuries.

The biomechanical efficacy of a dressing with a soft cellulose fluff core in protecting prone surgical patients from chest injuries on the operating table

Pressure ulcers are soft‐tissue damage associated with tissue exposure to sustained deformations and stress concentrations. In patients who are proned for ventilation or surgery, such damage may occur in the superficial chest tissues that are compressed between the rib cage and the support surface. Prophylactic dressings have been previously proven as generally effective for pressure ulcer prevention. In this study, our goal was to develop a novel computational modelling framework to investigate the biomechanical efficacy of a dressing with a soft cellulose fluff core in protecting proned surgical patients from chest pressure ulcers occurring on the operating table, due to body fixation by the Relton‐Hall frame. We compared the levels of mechanical compressive stresses developing in the soft chest tissues, above the sternum and ribs, due to the trunk weight, whilst the body is supported by the Relton‐Hall frame pads, with versus without the prophylactically applied bilateral dressings. The protective efficacy index for the extremely high stresses, above the 95th‐percentile, were 40.5%, 25.6% and 24.2% for skin, adipose and muscle, respectively, indicating that the dressings dispersed elevated soft‐tissue stresses. The current results provide additional support for using soft cellulose fluff core dressings for pressure ulcer prophylaxis, including during surgery.

Subtrochanteric Fracture of the Femur Accompanying Pre-existing Ipsilateral Osteoarthritis of the Hip Successfully Treated with Intramedullary Nailing in the Lateral Decubitus Position: A Case Report

A subtrochanteric fracture of the femur accompanying pre-existing osteoarthritis of the ipsilateral hip is rare. A deformity of the hip joint complicates the insertion of the intramedullary nail and varus malreduction is anticipated when surgery is performed on a fracture table with a perineal post. We report a successful case of intramedullary fixation performed in the lateral decubitus position and discuss the importance of avoiding varus and the superiority of the lateral position in surgery.

Preventing brachial plexus injury during shoulder surgery: a real-time cadaveric study

BACKGROUND

Brachial plexopathy is not uncommon after shoulder surgery. Although thought to be due to stretch neuropathy, its etiology is poorly understood. This study aimed to identify arm positions and maneuvers that may risk causing brachial plexopathy during shoulder arthroplasty.

METHODS

Tensions in the cords of the brachial plexuses of 6 human cadaveric upper limbs were measured using load cells while each limb was placed in different arm positions and while they underwent shoulder hemiarthroplasty and revision reverse arthroplasty. Arthroplasty procedures in 4 specimens were performed with standard limb positioning (unsupported), and 2 specimens were supported from under the elbow (supported). Each cord then underwent biomechanical testing to identify tension corresponding to 10% strain (the stretch neuropathy threshold in animal models).

RESULTS

Tensions exceeding 15 N, 11 N, and 9 N in the lateral, medial, and posterior cords, respectively, produced 10% strain. Shoulder abduction >70° and combined external rotation >60° with extension >50° increased medial cord tension above the 10% strain threshold. Medial cord tensions (mean ± standard error of the mean) in unsupported specimens increased over baseline during hemiarthroplasty (sounder insertion [4.7 ± 0.6 N, P = .04], prosthesis impaction [6.1 ± 0.8 N, P = .04], and arthroplasty reduction [5.0 ± 0.7 N, P = .04]) and revision reverse arthroplasty (retractor positioning [7.2 ± 0.8 N, P = .02]). Supported specimens experienced lower tensions than unsupported specimens.

CONCLUSIONS

Shoulder abduction >70°, combined external rotation >60° with extension >50°, and downward forces on the humeral shaft may risk causing brachial plexopathy. Retractor placement, sounder insertion, humeral prosthesis impaction, and arthroplasty reduction increase medial cord tensions during shoulder arthroplasty. Supporting the arm from under the elbow protected the brachial plexus in this cadaveric model.

An in vitro simulation model to assess the severity of edge loading and wear, due to variations in component positioning in hip joint replacements

The aim of this study was to develop a preclinical in vitro method to predict the occurrence and severity of edge loading condition associated with the dynamic separation of the centres of the head and cup (in the absence of impingement) for variations in surgical positioning of the cup. Specifically, this study investigated the effect of both the variations in the medial–lateral translational mismatch between the centres of the femoral head and acetabular cup and the variations in the cup inclination angles on the occurrence and magnitude of the dynamic separation, the severity of edge loading, and the wear rate of ceramic‐on‐ceramic hip replacement bearings in a multi‐station hip joint simulator during a walking gait cycle. An increased mismatch between the centres of rotation of the femoral head and acetabular cup resulted in an increased level of dynamic separation and an increase in the severity of edge loading condition which led to increased wear rate in ceramic‐on‐ceramic bearings. Additionally for a given translational mismatch, an increase in the cup inclination angle gave rise to increased dynamic separation, worst edge loading conditions, and increased wear. To reduce the occurrence and severity of edge loading, the relative positions (the mismatch) of the centres of rotation of the head and the cup should be considered alongside the rotational position of the acetabular cup. This study has considered the combination of mechanical and tribological factors for the first time in the medial–lateral axis only, involving one rotational angle (inclination) and one translational mismatch. © 2017 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1897–1906, 2018.

The Effects of Positioning the Operative Limb on Tibial and Fibular Nerve Somatosensory Responses during Acetabulum Fracture Repair: A Report of Two Unusual Cases

Our institution uses lower extremity somatosensory evoked potentials from the fibular (peroneal) and tibial nerves during posterior open reduction and internal fixation of the acetabulum to monitor the functional integrity of the sciatic nerve. This allows identification of compromised function caused by operative maneuvers. However, nonsurgical factors can also significantly affect the responses. In this article, we present one case where positioning of the leg and foot apparently caused diminished responses and was resolved by changing the manner of wrapping and securing the leg and foot. The second case is unusual because positioning improved the responses from being absent to identifiable and stable. Investigation of changes in peripheral responses should include examination of the position of the affected leg for ischemia and edema, and particularly the stimulation site for possible compromise.

Deltoid compartment syndrome as a complication of lateral decubitus positioning for contralateral elbow surgery in an anabolic steroid abuser

Compartment syndrome as a result of patient positioning for surgery is a rare but serious complication. Compartment syndrome as a result of anabolic steroid use is more rare. We present a unique case of compartment syndrome related to anabolic steroid use and patient positioning for complex distal humerus fracture fixation and also provide a review of the literature related to this topic.