Technical advances in instrument manufacture and optical technologies have, in part, made it possible for the surgeon to gain access to reliable views of increasingly smaller joint spaces.

This is an extensive approach, needing an often large incision over the side of the hip, with the detachment of the greater trochanter of the femur and its attached musculature to gain access to the joint.

The risks of infection and blood clots are always present, and Ganz and his colleagues cite complications such as heterotopic ossification (new bone formation around the hip), nerve injuries, failure of the greater trochanter to heal back properly, persistent pain following the formation of scar tissue (adhesions) in the hip joint, and a small risk of damage of the blood supply to the femoral head.

As a result, surgeons have looked to use the arthroscope more extensively in the hip joint in an attempt to avoid the possible pitfalls of large, open surgery.

The perceived advantages of this are the avoidance of large scars, decreased blood loss, faster recovery periods and less pain.

The most common indication is for the treatment of FAI (femoral acetabular impingement)[5] and its associated pathologies such as labral tears[6] and cartilage abnormalities,[7] among others (see Table 1).

To gain access to the central compartment of the hip joint (between the ball and socket), traction is applied to the affected leg after placing the foot into a special boot.

Once the surgeon is happy that they will be able to gain access to the hip joint (i.e. the ball will distract from the socket by a small amount), the patient is then painted with antiseptic and the surgical drapes applied.

[citation needed] The next step is to insert a fine needle under x-ray guidance into the hip joint.

Most surgeons will inject fluid into the joint at this stage, again to ensure that there is enough space between the ball and socket for safe instrument access.

The reason for this is so the surgeon can ensure that the needle, and subsequent cannulae do not penetrate and damage the acetabular labrum or cartilage joint surfaces (see fig.

Once the surgeon is satisfied that the cannula is in the correct position, by a combination of feel and x-ray guidance, the guide wire can be withdrawn.

Cam impingement is created by the abnormal development of the femoral head-neck junction causing what has previously been described as a 'pistol-grip deformity'.

This type of deformity is characterised by varying amounts of abnormal bone on the anterior and superior femoral neck at the head-neck junction (see fig.

The head-neck junction is at the base of the ball of the hip, where it joins the short neck, which in turn carries on downwards into the femur, or thighbone, itself.

This leads to joint damage as a result of the non-spherical femoral head being forced into the acetabulum mainly with flexion and/or internal rotation.

[9][10] Standard arthroscopic treatment of symptomatic cam FAI involves debridement (resection) or repair of any labral [10] and chondral injuries [11] in the central compartment of the hip, and subsequent reshaping of the head-neck junction of the upper femur (osteochondroplasty) in the peripheral compartment [12][13] using high-speed motorised burrs that are similar in design to a dentist's drill (see fig.

[2] The acetabulum may either have a more posterior orientation than normal, otherwise known as acetabular retroversion (seen as the crossover sign on AP radiographs), or there may be extra bone around the rim.

Repeated contact between the femoral neck and the edge of the acetabulum may lead to damage to the labrum and adjacent articular cartilage.

Methods to reduce this over coverage of the ball by the socket include labral detachment or peel back, acetabular rim trimming using burrs, often reattaching the labrum with anchors at the end of the procedure.

Recent evidence has demonstrated that this hydraulic seal is vital for maintaining stability of the ball and socket joint [16] and reducing contact pressures of the femur to the acetabulum.

The labrum may be damaged or torn as part of an underlying process, such as FAI or dysplasia (shallow hip socket), or may be injured directly by a traumatic event.

For this reason, surgeons prefer to apply as little traction as possible, for as short a time as possible, in order to gain safe access to the joint.

As with all arthroscopic procedures, because the hip arthroscopy is undertaken with fluid in the joint, there is a risk that some can escape into the surrounding tissues during surgery and cause local swelling.

A variable period on crutches after hip arthroscopy is common although physiotherapy is seen by many to play a very significant part in post-operative recovery.

If the procedure is being performed for early arthritis (wear and tear), the results are not as clear-cut, and a larger proportion may not feel benefit.

Both the ball and socket are congruous and covered with hyaline (or articular) cartilage, which allows smooth, almost frictionless gliding between the two surfaces.

A total of 27 muscles cross the hip joint, making it a very deep part of the body for arthroscopic access.

The function of this in the adult is under debate, but in childhood the ligamentum teres carries a blood vessel from the pelvis to the femoral head.