Fracture Immobilization in an Austere Environment: A Comparative Study of Military Special Operations Medical Personnel using a SAM Splint vs a One-Step Spray on Foam

Category: Trauma Introduction/Purpose: Improved body-armor and mine resistant vehicles have improved battlefield survivability, but now nearly 50% of casualties have a musculoskeletal extremity injury. The purpose of the current study was to evaluate current SAM splint techniques utilized for a distal Tib/Fib fracture verse a new one-step spray on foam immobilization technique. Methods: A cadaveric model with a distal third combined tibia-fibula fracture was used for testing. The specimens were placed in an austere environment and participants immobilized the injury with standard equipment (SAM splint, 6in Ace wrap). The test group immobilized the injury with a one-step in-situ spray on foam splint. Results: Twenty-one military Joint Special Operations Command (JSOC) medical personnel (11 Medics, 4 PAs, 6 Physicians) participated with an average of 7.7 years as a provider and 25.4 months deployed in a combat theater. Each participant was observed and scored by a single orthopedic foot and ankle surgeon using a Likert scale based on 10 splinting criteria. Standard SAM splinting resulted in an average score of 32.2 (range, 5-50), with significant deficiencies in fracture traction (1/5), fracture motion (2.9/5), protection of neurovascular structures (3/5), and soft tissue manipulation (3/5). The average time to completion was (203 sec), with one splint failure. The spray on foam splinting technique yielded a significantly higher score of 48.5 while completing the task significantly faster at 68 sec with no failures. Conclusion: JSOC medical personnel demonstrated overwhelming success in immobilizing a complex extremity fracture with a SAM splint. Testing demonstrated the inherent inability of the SAM splint to provide longitudinal traction while simultaneously allowing excessive fracture motion and potential injury to the soft tissues. In addition, our spray-on foam proof of concept technique eliminated motion and provided traction by allowing in-situ application with adequate rigidity.

The Effect of Thumb Immobilization on Fractures of the Hook of the Hamate: A Cadaver Study

Background: Fractures of the hook of the hamate are rare. Nonoperative management has historically been immobilization in a short arm cast (SAC) without thumb immobilization with a high reported incidence of nonunion. The high prevalence of nonunion following nonoperative treatment may be secondary to motion at the fracture site. The transverse carpal ligament’s attachment to the hook of the hamate results in movement at the fracture site during thumb motion. Methods: A cadaveric study using 8 fresh frozen cadaver arms amputated at the mid-humeral level was performed. Computed tomography (CT) imaging was used to assess the bony anatomy and assure no preexisting fractures were present. Osteotomy of the hook of the hamate was performed through a skin incision proximal to the hook of the hamate and the transverse carpal ligament. Each arm was then mounted in a jig designed to hold and stabilize the arm and hand in supination. CT scans were performed without cast immobilization with the thumb in extension and abduction, with SAC without thumb carpometacarpal joint immobilization, and SAC with thumb carpometacarpal joint immobilization. Results: Motion of the fractured hook of the hamate was found to occur in all noncasted specimens, greatest with base fractures. SAC without thumb immobilization had little to no effect in eliminating fracture motion. SAC including the thumb reduced fracture motion in all specimens. Conclusions: Previous poor experience with nonoperative management of fractures of the hook of the hamate may be partially due to inability to adequately immobilize the fracture fragment. Fracture motion of the hamate hook occurs during thumb movement, likely from traction on the fracture fragment by the transverse carpal ligament.

A biomechanical evaluation of cortical onlay allograft struts in the treatment of periprosthetic femoral fractures

Periprosthetic femoral fractures are increasingly addressed through the use of cortical onlay allografting. This study was designed to determine the effect of allograft cortical strut length, configuration, cable number, cable tension and the use of wire or cable on the fixation of periprosthetic femoral fractures. Ten cadaveric femora-strut constructs were tested using anteroposterior and axial loads to simulate the forces at the hip during gait. A transverse fracture at the level of the tip of the femoral stem was simulated. A biaxial servohydraulic testing machine was used to apply one hundred cycles of craniocau-dal load of 1.53 × bodyweight at a frequency of one Hz, along with an anteroposterior load of 0.15 × bodyweight at one half Hz. Variables for different constructs included the strut length (twelve cm, sixteen cm, or twenty cm), the number of cables (two, three, or four above and below the fracture site), cable tension, strut configurations and orientation (single strut or two struts, adjacent or opposite), and the use of wires instead of cables. Cable tension was measured using a calibrated tensioner. Movement at the fracture site was measured using a precision optoelectronic camera system. There was significantly less motion when cables were used rather than wires (p<0.05). Increasing the number of cables decreased fracture motion in some directions (p<0.05) and increasing cable tension showed a trend towards decreased fracture motion. We observed strut fractures in four cases when a single strut alone was used to stabilise the fracture. There was a significant decrease in fracture motion if two struts were used rather than one (p<0.01), but there was no significant difference between the anterior and lateral, and the medial and lateral strut configurations. Decreasing the strut length from twenty cm to twelve cm led to a significant decrease in axial rotation (p<0.05). Our data strongly favour the use of two struts, rather than a single strut alone. Cables enhance fracture stability compared to wires, presumably due to increased tension and to different surface characteristics. Increasing the cable tension gave greater stability although this may not fully translate to the clinical situation because the cable may garrotte or fracture the strut. Increased cable number and decreased strut length also enhanced fracture stability. The cortical struts essentially represent biological bone plates. If appropriately selected and prepared they can be customised to fit any femur. Our improved understanding of this technique should contribute to high rates of fracture union with an increase in bone stock and overall bone strength.

Stabilization of Ankle Syndesmosis Injuries With a Syndesmosis Screw

A retrospective review was made of 30 patients who had disruption of the ankle syndesmosis that was treated at Santa Clara Valley Medical Center with a transfixation screw. Follow-up ranged from 3 months to 3 years. There were 21 pronation external rotation injuries and 9 Maisonneuve fractures. Screw size ranged from 3.5 cortical to 6.5 cancellous Synthes screws. Most were placed transversely from 1.5 to 3.5 cm above the joint line. Intraoperative difficulties with screw placement occurred in 2 patients, resulting in one bent screw and one screw placed directly into the ankle joint. Most patients were mobilized prior to screw removal; lucent lines developed around the syndesmosis screw before it was removed in two-thirds of the patients. No screw broke prior to removal. In 6 patients, calcification of the interosseous membrane was seen and, in 4, this progressed to a distal tibiofibular synostosis. It was found that transfixation screws provided satisfactory stability of the syndesmosis to permit stable healing of the interosseous membrane and distal ligaments after ankle fracture. Motion between the tibia and fibula developed despite screw fixation, as shown by the lytic bony changes that occurred with time.