File:Figure 3. Fluoroscopic picture showing a mild amount of distraction of the hip before insertion of any instruments..Figure 3. Fluoroscopic picture showing a mild amount of distraction of the hip before insertion of any instruments File:Figure 4. A needle is passed into the joint, breaking the ‘suction seal’, and allowing further distraction of the hip joint with minimal extra traction..Figure 4. A needle is passed into the joint, breaking the 'suction seal', and allowing further distraction of the hip joint with minimal extra traction File:Figure 5. Portal placement under direct vision. The instrument is entering the joint through the hip capsule, between the femoral head (on the left) and acetabular labrum (on the right)..Figure 5. Portal placement under direct vision. The instrument is entering the joint through the hip capsule, between the femoral head (on the left) and acetabular labrum (on the right) The procedure is performed with the patient asleep (general anaesthetic) or under spinal anaesthesia. There are two widely used methods, one with the patient on their back (supine) and the other on their side (lateral decubitus). Which is used is down to the surgeon's preference. 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. (See fig. 2) There is specifically designed equipment for this, although some surgeons use a 'traction table', initially designed to help in the operative fixation of broken thigh and lower leg bones. The amount of traction (or pull) needed is assessed with the help of fluoroscopy (low-dose portable x-ray). (See fig. 3) It is usually not possible to distract the ball from the socket with traction alone by more than a few millimetres. 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. The next step is to insert a fine needle under x-ray guidance into the hip joint. This breaks the 'suction seal' of the joint and allows further distraction if necessary (see fig 4). The surgeon wishes to see the ball move out the socket by approximately 1 cm, so that access to the hip joint can be achieved with minimal risk of damage to the joint surfaces. 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. This needle is then removed. The next step is placement of the 'portals', or the small holes made to pass instruments into the joint. This is achieved by again passing a fresh hollow needle into the joint under x-ray control, usually in a slightly different position. 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. 5). Again, surgeons will have their own preferences as to their preferred placement. Through this hollow needle, a long thin flexible guide wire is passed into the joint, and the needle is removed over it, leaving the guide wire in situ. A small cut in the skin is made around the wire, to allow for larger cannulae to be placed over the wire through the portal. The wire therefore guides the larger cannulae into the joint. The most common external diameters of cannulae used are between 4.5 and 5.5 mm. 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. Once the first portal is correctly placed, any further portals may be created once the camera is in position, to ensure that they are placed with minimal risk to the joint surfaces. This process can be repeated to gain as many points of entry to the hip joint as the surgeon requires, normally between two and four. Certain of these entry points will be used for the viewing arthroscope and others for operating instruments. The operation then begins, a variety of instruments being used. While the surgeon views the interior of the hip joint through the arthroscope, other operating instruments are introduced through the other portals. Once the surgeon has completed the procedure needed between the ball and socket, often referred to as the 'central compartment' of the hip, traction is released, allowing the ball of the hip to sit back snugly into its socket. The arthroscope is then moved to the 'peripheral compartment' an area still inside the hip joint itself but outside its ball and socket portion. Commonly used arthroscopic tools are the hook probe, used to assess the integrity and consistency of the hip, radiofrequency probes that ablate soft tissue and can also smoothen tissue surfaces, and various shavers or burrs that can take away diseased tissue. If the acetabular labrum requires repair, specially designed anchors may be used. This is by no means a comprehensive list as new instruments are being developed constantly. Cam-type femoroacetabular impingement Figure 8.Cartilage delamination. A small area of acetabular cartilage has lifted from the underlying bone, being demonstrated by use of the arthroscopic probe 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. 6). 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. A bony protrusion or bump at the head-neck junction has been likened to a cam, an eccentric part of a rotating device. 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. This may impart compression and shear forces to the articular cartilage, and may lead to labral tears and peeling away of the articular cartilage from the underlying bone, so-called cartilage delamination (see fig. 8). Standard arthroscopic treatment of symptomatic cam FAI involves debridement (resection) or repair of any labral and chondral injuries in the central compartment of the hip, and subsequent reshaping of the head-neck junction of the upper femur (osteochondroplasty) in the peripheral compartment using high-speed motorised burrs that are similar in design to a dentist's drill (see fig. 9). Pincer-type femoroacetabular impingement In contrast, pincer impingement is a result of an abnormality on the acetabular side of the hip joint. 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. This results in contact of the femoral neck against the labrum and rim of the acetabulum during hip movement earlier than might otherwise be the case. Repeated contact between the femoral neck and the edge of the acetabulum may lead to damage to the labrum and adjacent articular cartilage. Bone formation, or ossification within the labrum may be commonly seen as a result of this repeated contact. It is thought that this type of impingement may also predispose to the development of osteoarthritis. The goal of the arthroscopic treatment of pincer impingement is to reduce the acetabular over coverage of the hip. 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. With the exception of cases of severe global over coverage of the hip, or situations in which the existing labrum has turned to bone (or ossified), excessive acetabular rim resection should be avoided in order to prevent iatrogenic increases in hip joint contact pressures. Labral tears The acetabular labrum is a fibrous structure, which surrounds the femoral head. It forms a seal to the hip joint, although its true function is poorly understood. Recent evidence has demonstrated that this hydraulic seal is vital for maintaining stability of the ball and socket joint and reducing contact pressures of the femur to the acetabulum. The labrum has also been shown to have a nerve supply and as such may cause pain if damaged. The underside of the labrum is continuous with the acetabular articular cartilage so any compressive forces that affect the labrum may also cause articular cartilage damage, particularly at the junction between the two, the chondrolabral junction. 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. Depending on the type of tear, the labrum may be either trimmed (debrided) or repaired. Removing or debriding the labrum is
Hip arthroscopy
Wrist arthroscopy
Back brace
Arthrogram
Bursectomy
Orthopedic plate
Hip resurfacing
Auricular splint