Joint Immobilization

Anatomy and Physiology

Musculoskeletal trauma and injury involve at least one of the following tissues: bone, joint, ligament, or tendon. A joint is defined as a junction where two or more bones articulate with each other. Joints are further classified by the amount of motion at the articulation. The function of a joint is to allow articulation between opposing skeletal elements. The ends of bones are covered with articular cartilage, and the joint is lubricated with synovial fluid. Ligaments encapsulated the joint in a protective fibrous layer of tissue.[6]

The most common orthopedic joint injuries consist of sprains, subluxations, dislocations, fracture-dislocations, and fracture subluxations. 

• Sprains are described as a tearing injury to one or more ligaments of a joint, which occurs when the joint is extended or forced beyond its normal plane/limits of motion.
• Subluxation is a partial disruption of a joint in which some degree of contact between the articular surfaces remains.
• Dislocations are the most extreme form of subluxation where there is a complete disruption of a joint, and the articular surfaces of the bones that form the joint are no longer in contact with one another. 

The urgency of reducing a dislocation is based on neurologic or circulatory compromise, as well as the length of time since initial dislocation.[7]

The most commonly dislocated large joint is the shoulder. It is a particularly important pathology to be able to recognize in the field due to the prevalence of the injury as well as the high recurrence rate. Around 95% of shoulder dislocations are anterior, and approximately half of patients develop recurrent shoulder dislocations within 2 years.[8] It is characterized by a complete anterior displacement of the humeral head from the glenoid. It often presents with the arm abducted and externally rotated and a loss of rounded shoulder appearance. In around 5% of shoulder dislocations, patients can develop axillary nerve neuropraxia, which consists of a reduced sensation over the lateral shoulder.[8]

Specific dislocations, including the hip and knee, carry high associated risks. Hip dislocations are characterized by the femoral head being displaced completely from the acetabulum. These dislocations occur commonly with high-velocity trauma. Around 90% of these dislocations are posterior, with the other 10% being anterior. In posterior dislocations, the hip will be adducted, flexed, and internally rotated, where anterior dislocations appear abducted, flexed, and externally rotated. With hip dislocations, there is a potential for associated avascular necrosis of the femoral head. This is from the anatomy of the dislocated hip joint, disrupting the blood supply delivered through the acetabulum.[9] This complication makes hip dislocations an important injury to diagnose and manage quickly. 

Knee joint dislocations are also concerning injuries that require prompt diagnosis and management. Knee dislocations that carry potential increased risk are high-velocity dislocations.[10] High-velocity dislocations are generally caused by a sudden, extremely violent force, such as a motor vehicle collision.[9][10] The exam can vary as 50% of knee dislocations spontaneously reduce. However, in the setting of a persistent dislocation, the knee can appear grossly deformed with swelling and gross instability. The dislocations are named based on the tibial displacement relative to the femur. An anteromedial skin furrow, or what is known as a “dimple sign” at the medial joint line, is an important exam finding for patients with suspected knee joint injury. This exam finding is suggestive of a posterolateral dislocation. This subset of knee dislocations is important to identify as they are irreducible, and attempts at closed reduction can lead to skin necrosis.[10][11] 

Because of the anatomy of the knee, any dislocation to the synovial joint can result in compromise to the neurovascular bundle in the popliteal space, specifically the popliteal artery and peroneal nerve. Severing this vessel from a knee dislocation can lead to rapid bleeding within the compartment and subsequent development of compartment syndrome. In addition, if the delay of popliteal artery repair after dislocation, there is a high likelihood of limb amputation, making prompt transport even more vital in this pathology. Peroneal nerve injury has been shown to occur in up to 33% of knee dislocations and contributes to the long-term complication of foot drop.[9][10][12] Also, associated fractures are present in nearly 60% of dislocations.[9][10] In patients with neurovascular compromise, an immediate reduction is necessary. This is done by applying longitudinal traction to the extremity. After successful reduction, the knee then requires a posterior long leg splint at 15 degrees for immobilization.  

Fracture dislocations are particularly complex in that it is difficult to characterize the injury from external appearance and exam. For this reason, these injuries are tricky to manage in the prehospital setting, given the limited diagnostic tools available. For this reason, suspected fracture-dislocations should be splinted at a position of comfort and quickly transported to the nearest medical facility.[7]

Indications

An indication for splinting exists after evaluating a patient if there are findings suggestive of an underlying joint, ligamentous, or bony injury. These injuries consist of sprains, subluxations, dislocations, and fracture-dislocations, to name a few. The severity of the injury does play a role in determining whether or not to splint and by which manner; however, it is not the only determining factor. By splinting these individuals prior to transportation, it will hopefully prevent further movement into the joint barrier, which can cause worsening pain or further complications during transportation by EMS to the ED. One special population to keep in mind is individuals with multisystem trauma. By splinting early in the process after initial resuscitation, the team can ensure that these injuries are stabilized, assist in pain management, and may aid in avoiding overlooking these injuries once the patient arrives at the ED. The decision to splint should be made early on after the initial history and examination are completed.

Contraindications

Joint immobilization in the prehospital setting is a non-invasive short-term procedure, which is required emergently in most cases to facilitate transport to the ED without further harm to the injury, and as such, is without particular contraindications.

Equipment

Prehospital Splinting Options

• Arm sling - used to immobilize suspected shoulder injuries. They provide a pouch for the arm to sit with the weight of the extremity distributed to the neck and upper back.
• Shoulder immobilizer - a removable hook-and-loop fastener device that keeps the arm in a position across the upper abdomen. This splint allows for less movement and mobility than a sling and is easy to place in any setting.[8]
• Knee immobilizer - a removable circumferential material that encases the knee joint and provides stabilization from the mid-thigh to the proximal ankle. This splint inhibits the knee from flexion and keeps the knee in a fixed extended state, which is helpful for certain knee joint injuries.[13] 
• Ankle stirrup - a splint that is quickly applied in the field. It consists of an air-padded wrap with hook-and-loop fastener straps securing the splint. It is used more for stable ankle injuries; however, when there is time restriction or limited supplies can be used to stabilize the ankle joint. 
• Traction splints - are mostly used when there is a suspected fracture involving long bones. The splint consists of a metal exoskeleton that runs longitudinally on either side of the affected extremity. There are then straps between the parallel metal bars that secure the extremity to the splint. The splint extends further than the extremity and has a belt intended to be secured to the distal extremity. This strap can then provide axial traction by pulling the extremity distally to mimic normal bone stability and limb length.[14]
• Air splints - are a deflated air bladder applied in a circumferential manner around the injured extremity. Once applied, they are inflated with air pressure, which applies compressive support to immobilize the covered area.[15]
• Vacuum splints - are a deflated nylon splint filled with foam-like beads. They are applied longitudinally along the injured extremity and strapped circumferentially. The splint is then deflated with negative pressure, which allows the nylon and bead material to conform to the injured extremity providing rigid immobilization firmly.[15]
• Rigid splints - are unpadded and consist of solid materials that are less flexible than other splints. Materials can consist of different metals, wood, plastic, or any available rigid material. When the rigid material is applied, the splint can then be secured to the extremity with the circumferential application of any available bandage, straps, or materials available. These materials can be used to make sugar tong, volar, ulnar gutter, posterior, and stirrup splints, to name a few.[15]

Technique or Treatment

Immobilization of Joint Injuries

It is important to have a systematic process in place that can be relied upon when managing joint injuries. In the setting of dislocations, it is always ideal to have the joint reduced before splint placement; however, if an area of less tension or pain can be achieved and there is intact distal neurovascular function, the best course of action is to immobilize and transport to reduce further injury. One approach that can be used in this way is provided below:

• Take appropriate precautions for body fluid or infection exposure.
• Expose the area of injury by removing clothing and debris from the site.
• Assure the patient is stable. If the patient meets trauma alert criteria, then transport should not be delayed for splinting. Rather, the patient should have their spine immobilized with further splinting being provided en-route or once at the facility providing definitive care. 
• Have another member of the treatment team manually stabilize/immobilize the joint to improve comfort during examination and splint application. The team member must hold above and below the joint to provide appropriate joint immobilization. 
• Assess distal neurovascular status. Joint injuries may result in damage to the surrounding neurovascular structures; therefore, it is important to perform an exam to evaluate for baseline sensation, range of motion, pulses, strength, skin color, capillary refill, and temperature. If the site distal to the injury is pulseless or cyanotic, make one reduction attempt to improve distal perfusion and regain a distal pulse. After attempting to reduce the injury once, reassess the injury as done above and note any changes. Next, splint the extremity and promptly inform the accepting hospital about the patient's injury. If you encounter resistance to limb alignment during reduction, splint the limb immediately and avoid further manipulation.
• It is important to use an appropriate immobilization device that fits the presenting injury. To ensure appropriate immobilization, the device must be sized properly and designed to provide support above and below the injured joint. 
• Next, it is important to stabilize the injured joint while positioning and securing the splint. 
• After the splint is placed, always reassess the distal extremity for distal neurovascular status to ensure appropriate splint placement. Compare this exam to the initial exam. If there is a concern for distal neurovascular compromise following splint placement, loosen the splint and reassess distal function.[7]

Complications

Complications of joint immobilization are due to long-term immobilization, which can include muscle atrophy, contractures, etc. However, in the emergency prehospital setting, as discussed here, they are negligible. 

Clinical Significance

As with all evaluations of traumatic injuries in the prehospital setting, all EMS providers are instructed to follow advanced trauma support guidelines. This consists of a primary survey followed by a more thorough secondary survey.

After identifying a joint injury, it is imperative to promptly splint the joint and maintain proper alignment through the transport process. Joint injuries are difficult to manage, compared to other musculoskeletal injuries, given the complexities that can arise. In the prehospital setting, it can be difficult to distinguish between an isolated joint dislocation versus a joint injury with complications. Complications may include an associated fracture, injured blood vessel, or nerve injury. To provide safe management and avoid complications, it is important to treat all joint injuries in a stepwise fashion.

For stable injuries, it is important to splint the joint in the position found and avoid complications from further manipulation. In instances where the patient position does not allow for safe transport or when there is a concern for distal neurovascular compromise, subtle joint manipulation may be indicated. When considering this intervention, it is important to understand the goal of treatment. When manipulating a joint injury, the goal is not to reduce the joint but rather to return distal neurovascular function and place the extremity in the closest anatomically neutral position.[7] Once the joint positioning is optimized, the patient will not only be more comfortable, but they will also be at less risk of suffering further soft tissue and neurovascular injury. Once the joint is aligned, a proper splint can be sized and placed to maintain the joint in the appropriate position for safe transport. With immobilization of lower extremity injuries, hips are to be splinted straight, knees are maintained in 10-degrees of flexion, and ankles are to be dorsiflexed and held at 90 degrees. With upper extremity immobilization, shoulders should be directed parallel to the chest, elbows are to be held in 90 degrees of flexion, wrists should be placed in a neutral position, and the fingers should be flexed.[7]

Another important aspect of properly managing musculoskeletal injuries is pain control. Analgesic medication is an important starting point when dealing with these patients and should not be withheld if there is a suspected joint injury; however, the most effective pain management in joint injuries is provided with immobilization. When a proper splint is applied to the injured joint, the underlying cause of the pain can be treated rather than treating the symptoms alone. This is done by limiting motion, which prevents further movement into the joint barrier and the severe pain that follows.[7] It is important to keep in mind that isolated joint injuries, as well as those occurring within the context of a multi-system trauma, require proper management to ensure optimal care.[7] Appropriate stabilization and management by EMS providers can limit long-term complications, morbidity, and mortality.

Enhancing Healthcare Team Outcomes

Management of a joint injury requires an interprofessional team of healthcare providers. These providers include EMS/first responders, medical technicians, nurses, emergency physicians, and at times subspecialty physicians such as trauma and orthopedic surgeons. Without the collaboration of these medical professionals, injury management can be suboptimal and can lead to worsened clinical outcomes. When looking at joint injuries, especially when involving more significant trauma, there are possible complications such as neurovascular compromise and prolonged dislocation that can lead to severe complications. It is important for prehospital personnel not only to recognize these injuries but communicate them effectively to the emergency medicine team. This communication allows the hospital-based team to prepare for the incoming injury. This could be coordinated in the following manner:

• EMS arrives on the scene, recognizes, and stabilizes/immobilizes the injury.
• EMS calls medical command if necessary or speaks to emergency department personnel.
• Analgesic medication is given - either by EMS, primarily, or command physician.
• Emergency department physicians can coordinate with nursing, medical technologists, X-ray/radiology department, and possibly even subspecialty surgeons (vascular/orthopedics/trauma) if there is a concern for complications related to the injury.
• The patient arrives, and the initial assessment is made.
• If there is a concern for bony injury, radiology is contacted to perform imaging.
• If there is any concern for neurovascular compromise, fracture, or severe irreducible dislocation, surgical subspecialties are consulted, and the patient is taken for urgent operative repair if necessary.
• If a stable injury is present, the ED team manages care at the bedside by splinting/immobilizing the injury and preparing the patient for final disposition.

The care of joint injuries does not stop in an emergency setting. To allow for appropriate rehabilitation and return of baseline function in the affected joint, the patient's care must continue through their primary care network, subspecialty surgical follow-up (if necessary), and physical therapy. The patient should be referred to these medical providers to receive ongoing care and strengthening to ensure the best long-term outcome from the injury sustained.