Intra articular fractures occupy a very special place in management of musculo skeletal injuries because of following reasons;

A joint is a very complex structure consisting of enlarged bone ends which are covered with highly specialised articular hyaline cartilage.

Joints like knee, consist of specialised intra articular structures like menisci and cruciate ligaments which are required for mobility as well as stability.

Injury to joint capsule and ligaments can not be visualised on x-rays and hence may go unnoticed resulting in poor outcome.

Hyaline cartilage lacks blood vessels hence undifferentiated mesenchymal cells which are required for repair are unable to reach and invade tissue defects and hence poor out come.

Chondrocytes being highly specialised cell do not to respond to injury by reproduction and hence hyaline cartilage defect is never restored with same quality of cartilage.

Synovial fluid of joint does not allow clot formation. It is the clot which attracts cells & gives them temporary matrix to adhere to replace with more permanent tissue. Therefore intra articular defects do not get filled up on their own.

Some defects heal & form fibrocartilage which will last for years while some defects fail to repair causing fibrillation, fragmentation & exposure of bone leading to degeneration. Unfortunately one does not know which course will be taken.

Following variables influence cartilage healing :

Injury Variable

• Small defect -->better healing.

Patient Variable

• Age : Younger the patient better is the healing.
• Weight: In heavy patient a small step will cause increased friction in the joint causing early wear and tear of the opposing joint surface leading to early arthrosis.
• Activity level : Inactivity after intra articular fracture leads to poor cartilage healing.
• Osteoporosis : will lead to poor implant fixation leading to collapse and poor outcome.

Treatment Variable

• Apposition : step more than 3mm in a weight bearing joint will end up with early painful osteo arthrosis.
• Defects in articular cartilage must not be left unattended because they never get filled up on their own resulting in poor result.
• Stabilisation of fragments :Since early mobilisation after surgery is key to success, fracture fragments must be absolutely stable to allow early mobilisation.
• Restoration of capsule and ligament balance is absolutely necessary to avoid an unstable joint which wears out very fast.
• Early mobilisation: Robert Salter, a Canadian orthopaedic surgeon proved with experiments on rabbits that if a damaged joint is mobilised continuously passively by a machine than the quality of regenerate is better and the chances of post injury stiffness are reduced.

Since joints are crossed by combined neurovascular structures, a properly selected surgical approach is essential to achieve anatomical reduction

Pre-operative assessment and planning

Special X - Rays

Since the articular end of the bone has curvaceous anatomy, to visualise it from every angle, standard A.P. and lateral views may not suffice. One may need oblique views and specialised views to see displacements of various fragments.

C.T. Scan

Especially with the possibility of generating 3 dimensional images, it has become easy to recognise various fragments and to understand the post traumatic anatomy. This helps in planning the surgical approach as well as fixation modalities.

Arthrography

The technique involves injecting a radio opaque dye in the joint and taking x-ray pictures. With advent of C.T. scan, this technique is rarely used.

DEXA

Normally one judges the quality of bone on routine hip A.P. X-ray by studying the trabecular pattern of the upper end of the femur ( Singh's Index ) but it is worthwhile in very osteoporotic bones to study the bone quality by doing Double Energy X-ray Absoptiometry because implants may not hold in grossly osteoporotic bones causing failure of fixation. In such event one may consider either functional non operative treatment or replacemet, if possible.

Computer Generated Bone Model

The most recent technique in the armamenterium is computer generated bone model. The technique consists of transferring the digital data of C.T. scan to a processing unit which generates a true to life bone model of the involved bone. The surgeon can than plan the approach, modalities of reduction and fixation and alternative treatment options. Pic to be given Info for Doctors Principles of management Based on these observation and on principles of Association of Study of Internal fixation ( A.O./A.S.I.F.), Stable fixation followed by early mobilisation is the key to success in management of intra articular injuries. Surgery should be carried out at the earliest for ease of anatomic reduction, which becomes difficult as the time elapses due mainly to ligament contraction. If the surgery is not carried out early, there are increased chances of joint stiffness.

Minimally Invasive Surgery

With availability of Image intensifier, arthroscope and C.T. guided techniques, many intra articular fractures can now be treated with minimally invasive techniques. Special surgical instruments and implants like canulated, flexible drills and canulated screws have made this possible.