2.3 Articular fractures: principles
To access the videos, please follow the URL link
1 Introduction
Disruption of any component of a joint may result in altered joint function because of the pathological processes of arthrofibrosis or osteoarthrosis. For example, displaced intraarticular fractures are associated with gaps or steps at the joint surface that can immediately affect stability, cause pain, and disrupt effective motion of the joint and joint mechanics. The inflammatory response associated with such an injury can lead to extensive fibrosis both within the joint and in the surrounding soft tissues. This response can be exacerbated by inappropriate immobilization or surgical procedures. For these reasons, closed reduction and external immobilization were commonly unsuccessful in the early treatment of displaced intraarticular fractures. The result was commonly a bone deformity with associated stiffness, pain, and functional disability. The introduction of treatment with traction and joint mobilization improved motion but instability and incongruity of the joint persisted. To avoid these complications of nonoperative treatment, Charnley [1] proposed that perfect anatomical restoration and joint movement could only be obtained by open reduction and internal fixation. However, early implants were unable to achieve sufficient stability to allow immediate motion while preventing displacement. As a result, patients received the worst possible combination of treatments: the risks of open reduction combined with the complications of long-term external immobilization. Outcomes were poor following surgery and most experts advocated nonoperative treatment.
The advent of antibiotics, improved soft-tissue handling, improved metallurgy with new implant designs, and better understanding of the injuries by surgeons dedicated to fracture care, resulted in open reduction and internal fixation of intraarticular fractures becoming safer and more widely accepted. Application of the AO/OTA Fracture and Dislocation Classification principles of operative fracture treatment confirmed that internal fixation with absolute stability and early joint motion improved radiological and clinical results for articular fractures [2].
2 Functional considerations
The surgeon can impact three key factors that influence joint function and the risk of posttraumatic arthritis: joint incongruity, malalignment, and instability.
Incongruity of the articular surface may cause increased contact stresses in the joint [3]. If this incongruity combines with instability, it may cause abnormal movement with disproportionate increases in contact stress rate and magnitude. It can anatomically shift the articular surface-loading pattern, initiating posttraumatic osteoarthritis with secondary inflammation leading to degeneration of the joint. Although, clinical evidence linking incongruity to posttraumatic osteoarthritis is still inconclusive, it is important to attain the suitable congruity of injured joints ( Fig 2.3-1 ) [4].
Malalignment may shift the loading pattern of the articular surface in a joint, which may be crucial to subsequent progression of osteoarthritis. The new point of contact may be maladapted for cartilage loading and may be unable to rapidly accommodate the transition to load bearing via remodeling, leading to degeneration of the whole joint. Particularly in the lower extremity, the restoration of the anatomical axis is crucial [5].
Instability caused by fracture, ligament or meniscal injury can also lead to cartilage degeneration and may be important in determining outcome. An example is the high incidence of posterior subluxation, as the initial mode of failure, after operation on multifragmentary posterior wall fractures of the acetabulum ( Fig 2.3-2 ). This may indicate that posterior subluxation or instability of the hip joint is an important factor leading to degeneration after internal fixation of posterior wall fractures. In tibia plateau fractures, excising the meniscus during surgery increases loading strain and may provoke instability of knee joint. The development of osteoarthritis and poor outcomes are common and modern surgical techniques emphasize the importance of preserving the meniscus and restoring knee stability by appropriate ligament repair or reconstruction (see chapter 6.7-2).
Joint malalignment, joint instability, and articular incongruity play a role in the development of posttraumatic osteoarthritis. However, the relative contribution of each factor to the subsequent progression of arthritis has not been well characterized. A combination of these factors is likely to give a worse outcome than a single factor alone. The joint involved is also a factor and symptomatic arthritis is more likely in weight-bearing joints [6, 7].
Thus, most authors agree that it is necessary to secure an anatomical reduction of the articular surface, restore joint stability, and normal axial alignment to provide the patient with the best possible chance of permanent joint preservation.
The current philosophy of operative treatment of these injuries is based on the following observations [8]:
Plaster cast immobilization of intraarticular fractures results in joint stiffness.
Plaster cast immobilization of intraarticular fractures after open reduction and internal fixation results in much greater stiffness.
Depressed central articular fragments are impacted and will not be reduced by closed manipulation and traction.
Major articular depressions do not fill with fibrocartilage. The resulting instability is permanent.
Anatomical reduction and stable fixation of articular fragments is necessary to restore and maintain joint congruity.
Metaphyseal defects beneath reduced articular segments must be filled with structural bone graft or substitute to prevent articular fragment redisplacement.
Metaphyseal and diaphyseal displacement must be reduced to obtain proper limb alignment and prevent joint overload.
Early motion is necessary to prevent joint stiffness and to maximize articular healing and recovery. This requires stable internal fixation.
3 Mechanism of injury
There are two common mechanisms of injury for articular fractures:
Indirect application of force, producing a bending moment through the joint and drives a part of the joint into its opposing articular surface. Usually the ligaments are strong enough to initially resist this eccentric load, converting the bending moment to direct axial overload and fracturing the joint surface. Typically, this results in a partial articular fracture ( Fig 2.3-3a–b ).
Direct application of force, either to the metaphyseal/diaphyseal component of the joint or through axial transmission of force along the diaphysis ( Fig 2.3-3c–e ). This direct crushing or axial application of force causes an explosion of the bone and a dissipation of force into the soft tissues. Complete multifragmentary articular fractures, often with associated severe soft-tissue injuries, are the result ( Fig 2.3-4 ). The bone quality, the position of the limb, and the exact vector of the force determine the fracture pattern.
4 Evaluation of the patient and the injury
4.1 Clinical evaluation
Many joint injuries are caused by high-energy trauma and systematic evaluation of the whole patient is essential because there is a high risk of polytrauma. Once life-threatening injuries have been addressed, the joint injury must be evaluated in a systematic manner.
When assessing any joint injury, pay close attention to the soft-tissue envelope as intraarticular fractures may be open and can cause gross malalignment of the limb, joint subluxation, or dislocation. Associated ligament injuries must be examined initially by palpation along the course of the ligament and examined again after fixation of the fracture. The vascular status distal to the injury must be evaluated in every case and recorded clearly in the medical record. This is best done by palpation of the pulses distal to the injury. If there are no palpable pulses or if a discrepancy exists between the injured and the contralateral side, the use of a Doppler monitor and assessment of capillary refill, color, and skin temperature are necessary. The ankle-bra-chial index (ABI) provides reliable objective information regarding arterial compromise following blunt or penetrating injury in the lower limb. An ABI of less than 0.9 indicates a probable vascular injury [9]. A careful neurological examination of the limb must also be performed and documented.
Ideally, x-rays should be obtained before any closed reduction maneuver but these must be performed immediately if there is any suggestion of neurovascular compromise. If obtaining radiographs will cause a delay of more than a few minutes, the limb should be realigned. Following realignment and splinting of the limb, neurological and vascular examination must be repeated (and recorded) and a further radiograph obtained.
Extensive open wounds, lacerations, or degloving are identified in the zone of injury. Even a small disruption of the skin near a fracture must be considered an open fracture or an open joint injury until proven otherwise. Leakage of blood-stained synovial fluid, fat globules in the blood or leakage of intraarticularly injected fluid indicate that a fracture or joint injury communicates with the external environment.
Severe injury to the surrounding tissues can occur even in the absence of open wounds. Determining the mechanism of injury can help to predict the evolution of the soft-tissue injury. The presence and location of any abrasions, joint effusion, skin blistering, and soft-tissue swelling should be noted. Point tenderness at ligamentous insertions may be the only clue to ligamentous disruption. Muscular compartments should be evaluated for any evidence of compartment syndrome.
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
