New Higher Resolution Electrode Array for Intraoperative Brain Monitoring

Neurosurgeons operating on the brain often use electrode grids to monitor neural activity and to stay clear of healthy tissue. The technology hasn’t seen much progress over the past couple of decades, but now a team from University of California San Diego and Massachusetts General Hospital has developed a new electrode array that provides higher fidelity readings of the electric activity on the surface of the brain.

The new device is many times thinner than electrode arrays currently used in brain surgery, and being flexible allows it to conform to the curvaceous morphology of brain, hence placing the electrodes in better contact with the brain’s surface. The electrodes themselves are much more numerous and are placed 25 times closer to each other than in existing devices, resulting in higher quality signal resolution.

While wanting to have better signal acquisition is nothing new, using metal for the electrode material results in limitations on how small the electrodes can be made without resulting in too much extra noise. To avoid this, the researchers used PEDOT:PSS, a conductive polymer that is flexible and performs better than metal in certain cases, and electrodes made from it can be packed much closer together.

To test the new electrode grid, the researchers had UC San Diego neurosurgeons try using it during four procedures, comparing it to existing devices. They showed that the new device provides better resolution and may be more useful during various procedures.

In addition to being used during neurosurgeries, the same technology may be highly applicable for brain-computer interfaces that perform better the more data they are able to gather.

Study in journal Advanced Functional Materials: Development and Translation of PEDOT:PSS Microelectrodes for Intraoperative Monitoring…

Via: UC San Diego…

PREVENA DUO Negative Pressure Wound Therapy Treats Two Incisions at Same Time

Acelity, based in San Antonio, Texas, is releasing the PREVENA DUO Incision Management System, a disposable negative pressure wound therapy (NPWT) system that can be used to manage two surgical incisions at the same time. The company expects the PREVENA DUO to be used post vascular harvesting, breast reconstruction, and ortho trauma procedures that often result in more than one incision.

Negative pressure wound therapy has been shown effective to treat a variety of wound types and many practices have been adopting it as a regular part of post-op rehab to prevent infections and speed up healing of wounds.

PREVENA, the single site treatment device, has had extensive use already. Here’s some info from Acelity regarding the studies of the PREVENA:

Clinical studies have demonstrated the efficacy of PREVENA™ Incision Management System in significantly reducing the incidence rate of infections. According to one study led by Tim Matatov, M.D., Louisiana State University Health Sciences Center, evaluating the PREVENA™ Incision Management System in reducing the risk of groin wound infection after vascular surgery, PREVENA™ Therapy was found to reduce the incidence of groin wound infection compared to traditional skin adhesive or absorbent dressings (6 percent incidence of infection with PREVENA™ Therapy compared to 30 percent with control group). As groin incisions are prone to complications and the incidence of groin SSIs after vascular surgery can be as high as 44 percent, prevention is a key component of improving patient care. The results also indicated significant cost savings with the PREVENA™ Incision Management System. In fact, the study authors concluded that the cost of the PREVENA™ System was quickly exceeded by the traditional dressings group due to long hospitalization required for two patients with Szilagyi Grade III infections ($25,740 vs. > $45,000 respectively).

Via: Acelity…

The Great Plateau

Authors: Drs. Paul Cohen and Shihab Ali

Case 1:

A healthy 21-year-old female presents to the ED following a motor vehicle crash. She was the restrained passenger in a head-on collision at approximately 30 mph. Her only complaint is left knee pain. On exam, her left knee is tender over the anterior aspect with moderate swelling and ecchymosis. Her ligamentous exam is limited by pain, but there is no gross laxity.  Neurovascular exam is normal, and the remainder of her trauma survey is unremarkable. Plain films are obtained:  

What are the pertinent radiographic findings? 

Figure 1: Illustrative image courtesy of Dr. Mark Holland. (Radiopaedia.org, rID: 19162)

Figure 1: Illustrative image courtesy of Dr. Mark Holland. (Radiopaedia.org, rID: 19162)

Answer:

Lipohemarthrosis is a layering of fat and blood that is indicative of an intra-articular fracture.  Blood and fat from bone marrow escape into the joint space and layer on a horizontal cross-table view because they are different densities. Close inspection also reveals a subtle depression of the lateral tibial condyle consistent with a tibial plateau fracture.    

Figure 2: Radiographs demonstrating lipohemarthrosis (lateral view) and depressed lateral tibial plateau fracture (AP view).

Figure 2: Radiographs demonstrating lipohemarthrosis (lateral view) and depressed lateral tibial plateau fracture (AP view).

Case Outcome:

The diagnosis of a minimally depressed lateral tibial plateau fracture (type III) was made. The patient was evaluated by orthopedics in the ED and discharged home in a knee immobilizer with orthopedic follow-up in 2 days.

Case 2:

An active, independent 72-year-old female presents with left leg pain after a mechanical fall at home. She fell down multiple stairs onto a wooden floor. Her exam is notable for swelling and tenderness of the left knee with a normal neurovascular exam. An AP radiograph of the knee is shown below.

Figure 3. Illustrative image (Gentili A, Tibial Plateau Fracture Imaging, Emedicine)

Figure 3. Illustrative image (Gentili A, Tibial Plateau Fracture Imaging, Emedicine)

What is the diagnosis? How should this injury be managed?

Answer:

A minimally displaced lateral split tibial plateau fracture is depicted on radiographs. This injury is classified as a Schatzker type I fracture and is amenable to nonoperative treatment.

Case Outcome:

Orthopedic surgery was consulted. The patient was placed in a knee immobilizer and admitted. Given the minimal displacement of the fracture, she was managed nonoperatively. No weight-bearing was recommended and she was discharged to a skilled nursing facility with orthopedic follow-up in one week.

Overview of Tibial Plateau Fractures:

Epidemiology:

  • Most common mechanism = axial loading
  • Bimodal distribution:

o   Young adults → high-energy trauma (MVC, fall from height)

o   Elderly → low-energy compression force to osteoporotic bone

  • Majority involve lateral tibial plateau

Associated Injuries:

  • Popliteal artery injury (artery is tethered both proximally and distally at the knee) → any intra-articular disruption can cause vascular injury
  • Displacement of the lateral tibial condyle can cause peroneal nerve injury → assess for foot drop!
  • Concomitant soft tissue injuries are common (e.g., ligaments, meniscus)

o   Ligamentous injury occurs in up to 66% of patients → accurate exam limited on initial presentation due to pain, so follow-up examinations are essential

  • High risk for compartment syndrome!

Diagnostic Imaging:

  • AP and lateral radiographs for initial imaging

o   Lipohemarthrosis suggests occult fracture in the appropriate clinical setting

  • CT is useful for:

o   Diagnosing occult fracture not evident on plain radiographs

o   Improved characterization of fractures

o   Identification of articular depression which may alter management in up to 25% of cases

o   Operative planning

  • MRI shows concomitant soft tissue injury but is rarely indicated in the ED

Classification:

Figure 4: Schatzker Classification of Tibial Plateau Fractures. (Image from Zeltser et al, Classifications in Brief: Schatzker classification of tibial plateau fractures, Clinical Orthopedics and Related Research, 2013 Feb)

Figure 4: Schatzker Classification of Tibial Plateau Fractures. (Image from Zeltser et al, Classifications in Brief: Schatzker classification of tibial plateau fractures, Clinical Orthopedics and Related Research, 2013 Feb)

Management Considerations:

  • Ice and elevate!
  • Schatzker IV injuries are associated with high risk of popliteal injury → consider ABIs and/or vascular imaging (i.e. CTA)
  • Nonoperative management with a hinged knee brace and protected weight bearing is indicated for:

o   Minimally displaced split or depressed fractures

o   Nonambulatory patients

  • Surgical management is common for tibial plateau fractures, especially:

o   Segment depression > 5mm

o   Condylar widening > 6mm

o   Schatzker type ≥ IV

  • Orthopedic consultation is recommended
Figure 5: Algorithm for ED management and disposition. (Karadesh M, Tibial Plateau Fractures, Orthobullets)

Figure 5: Algorithm for ED management and disposition. (Karadesh M, Tibial Plateau Fractures, Orthobullets)

Take Home Points:

  • Tibial plateau fractures are often complex injuries with associated ligament and meniscal disruption
  • Clinical suspicion for occult tibial plateau fracture (i.e., mechanism, age, effusion) warrants CT imaging in the ED
  • Maintain vigilance for neurovascular injury and recognize risk for compartment syndrome
  • Patients with minimally displaced split or depressed fractures can often be discharged in a knee immobilizer as long with close orthopedic follow up assuming adherence to strict non-weight-bearing and adequate pain control
  • More complex fractures often require admission for operative management
  • Consult orthopedics

Faculty Reviewer: Jeffrey P. Feden, M.D.

References:

1. Chan PS, et al. Impact of CT scan on treatment plan and fracture classification of tibial plateau fractures. J Orthop Trauma 1997;11:484–489.

2. Egol KA, Tejwani NC, Capla EL, Wolinsky PL, Koval KJ. Staged management of high-energy proximal tibia fractures (OTA types 41): the results of a prospective, standardized protocol. J Orthop Trauma 2005;19:448–455.

3. Schatzker J, McBroom R, Bruce D. The tibial plateau fracture: the Toronto experience 1968-1975. Clinical Orthop Relat Res 1979;138:84-104.

4. Gentili, Amilcare. Tibial Plateau Fracture Imaging. Emedicine [Internet]. Available from: http://emedicine.medscape.com/article/396920-overview. Accessed 23 March 2017.

5. Karadsheh M.  Tibial Plateau Fractures.  Orthobullets [Internet].  Available from: http://www.orthobullets.com/trauma/1044/tibial-plateau-fractures.  Accessed 20 April 2017.

6. Pallin, Daniel J.  Tibial Plateau Fractures, Knee and Lower Leg, Chapter 57.  Rosen’s Emergency Medicine, 8th ed.  Philadelphia: Elsevier, 2014.  698-722 p.

7. Thomas Ch, Athanasiov A, Wullschleger M, Schuetz M. Current concepts in tibial plateau fractures. Acta Chir Orthop Traumatol Cech. 2009;76(5):363-73.

8. Tscherne H, Lobenhoffer P. Tibial plateau fractures. Management and expected results. Clin Orthop Relat Res 1993;292:87-100.