- Joint Anatomy
- Mechanism of Intraarticular Injury
- Evaluation of Intraarticular Fractures
- Treatment of Intraarticular Fractures
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Intraarticular fractures are the fractures where the fracture line crosses into the surface of a joint resulting in some degree of cartilage damage. The fractures can vary from hairline fractures to displaced fractures.
Intraarticular fractures ideally should be reduced anatomically and fixed securely so that early joint movement can be allowed.
Where this cannot be achieved, some permanent loss of motion is to be expected and the joint may develop degenerative arthritis as a result of the injury. Other problems that could be encountered are bony prominence, deformity, numbness, weakness, reflex sympathetic dystrophy and others.
Diarthrodial joints provide a smooth, stable articulation between the bones of the appendicular skeleton so that they may take on special tasks.
A synovial joint consists of two end segments of bone bound together by a fibrous capsule
The articulating end segment of bone is covered with hyaline cartilage which is resilient, elastic, but avascular. The cartilage helps to distribute force to the underlying subchondral bone. Different parts of the joint surface come into contact at different positions of joint motion.
A joint is stabilized by the shape of the joint, capsule, ligaments and muscles/tendons surrounding the joint.
Synovial fluid provides lubrication and nutrition for the articular cartilage surfaces.
Joint motion and repetitive physiological loading are essential for the health of joint.
Mechanism of Intraarticular Injury
There are two common mechanisms of injury for articular fractures:
The force that leads to a bending moment is resisted by ligaments and that resistance converts the eccentric load to direct axial overload, fracturing the joint surface. This is the most common mechanism for intraarticular fractures. Typically, this results in a partial articular fracture. Loading one side of the joint usually produces a split or shearing fracture, while a pull on the ligamentous insertions on the opposite side results in an avulsion fracture or torn ligament.
An axial loading force, which allows one component to act as a hammer on the other, producing an impaction of the articular surface or, if more severe, an impaction with a fracture of the metaphysis or even diaphysis. The bone quality, the position of the limb, and the exact vector of the force will determine the fracture pattern.
This leads to an injury which is similar to crushing and can cause multifragmentary intraarticular fractures. There is associated severe soft-tissue injuries.
Evaluation of Intraarticular Fractures
In case of high energy injuries, the patient should be evaluated for associated musculoskeletal and non-orthopedic injuries. There may be multiple bones involved or multiple systems injured.
Intraarticular fractures may cause gross deformity of the limb and an associated joint subluxation or dislocation.
The complete neurovascular examination should be done to rule out any neural or vascular injury.
Any associated compartment syndrome must be examined.
Two x-ray views perpendicular to each other should be done for the injured part and as per clinician’s evaluation.
In case of severe comminution views after applying traction to the limb should be done for a better assessment of the injury.
Additional oblique views may be ordered for further evaluation if needed.
Therefore, initial x-rays may require a physician in attendance to stabilize the limb and ensure that adequate images are obtained. For simple fractures, AP and lateral x-rays will suffice.
Computed tomography along with 3-D reconstruction provides additional information about fracture configuration, number and position of the articular fragments, the presence of impacted articular segments and any metaphyseal extension.
CT is able to show the cross-sectional anatomy of the fracture, planes of the fracture lines, and often discloses unsuspected fracture lines.
Treatment of Intraarticular Fractures
Restoration of the articular surface following fracture in adults depends on early anatomical reconstruction, stable fixation with interfragmentary compression, and early motion.
Intraarticular Fracture Guiding Principles
The current philosophy of operative treatment of these injuries is that the intraarticular fractures may result in stiffness, deformity, pain, and posttraumatic arthritis. In order to avoid deformity and stiffness, it is necessary to secure anatomical reduction of the articular surface, restore joint stability and normal axial alignment, and begin early motion.
Animal experiments have concluded that t anatomical reduction and stable fixation with interfragmentary compression of an intraarticular fracture, followed by continuous passive motion leads to hyaline cartilage healing. It is well known that defect in articular cartilage otherwise heals by fibrous cartilage formation.
Basic principles of intraarticular fracture treatment are as follows:
- Plaster cast immobilization of intraarticular fractures results in joint stiffness.
- Plaster cast immobilization of intraarticular fractures combined with open reduction and internal fixation results in much greater stiffness.
- Depressed articular fragments are impacted and will not be reduced by closed manipulation and traction.
- Major articular depressions do not fill with fibrocartilage and thus instability, which results from their displacement, is permanent.
- Anatomical reduction and stable fixation of articular fragments is necessary to restore joint congruity.
- Metaphyseal defects beneath reduced articular segments must be filled with structural bone graft or substitute to prevent displacement of the articular fragment.
- Metaphyseal and diaphyseal displacement must be reduced to obtain proper limb alignment and prevent joint overload.
- Immediate motion is necessary to prevent joint stiffness and to ensure articular healing and recovery. This requires stable internal fixation.
This treatment could be done in undisplaced fractures. The standard treatment is immobilization followed by early mobilization. Indications for non-operative treatment of intraarticular fractures is less common.
Timing of Intervention
Following intraarticular injuries need an immediate surgical procedure
- Open fractures
- Irreducible fracture dislocations
- Associated with neurovascular injuries
- Articular fractures associated with compartment syndromes
Intraarticular fractures are often associated with severe soft tissue injuries and definitive procedures may be delayed because of soft tissue conditions. Delay may vary from few days to two to three weeks.
It is important to restore length and alignment of the fracture fragments by bridging external fixation if undue delay is anticipated.
In such cases, securing reduction of the articular surfaces with minimal exposure at the time of external fixation. This should be minimal surgery to align and fix articular fragments and the implant used commonly is a lag screw.
Any metaphyseal defect or fracture is not treated at this stage in cases where the delay is anticipated.
Cases where the soft tissue conditions are better and surgery could be done within 5-7 days, both intraarticular and metaphyseal surgeries are done together.
Approach and Technique of Intraarticular Fracture Fixation
The guiding principle in the internal fixation of articular injuries is the preservation of the blood supply to the soft tissues and to all the bony fragments.
This is done by the staging of intraarticular and metaphyseal surgeries, indirect reduction techniques, percutaneous insertion of lag screws, and, where indicated, on the buttressing of these fractures in hybrid frames.
It goes without saying that at the time of surgery skin condition should be satisfactory. The key is adequate exposure but not too traumatic.
Anatomical reduction of the articular surface is the first step in the surgical reconstruction of intraarticular fractures.
Depressed portions of the articular cartilage should be elevated and fixed. It is then necessary to bone-graft the metaphyseal defect that is invariably created when the articular fragments are disimpacted and elevated.
Autogenous cancellous bone is still the gold standard in these situations.
The metaphysis must be buttressed to prevent axial overload, and the diaphyseal components must be fixed so that early motion can be started.
Other intraarticular structures may be repaired before closure.
The buttressing is usually done by plates but in case of compartment syndromes, vascular repairs and open fractures etc, hybrid external fixation could be done.
It is important not to close the skin in tension.
Synovium and capsule closure would prevent desiccation of the articular cartilage and cover any exposed tendon or nerve.
Some wounds require secondary closure about 5 days later. In cases where skin closure is not feasible, skin coverage flaps may be done.
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