Hip Arthroscopy – set up and access to central compartment

The hip joint needs to be distracted to allow access of arthroscope and instruments. Various specialist hip distractors are available to apply traction although a standard fracture traction table will suffice.
Although many arthroscopists prefer to perform arthroscopy with the patient in a lateral position, the preferred position for most is supine.
The most critical aspect of the procedure is to ensure that the perineal post is very well padded. Failure to provide adequate padding may result in skin bruising and damage to pudendal nerve. Impotence has been reported in males. This is attributed to insufficient padding and/or prolonged traction. Traction should never be applied for more than 2 hours. One of the most common complications of hip arthroscopy is neurological injury. The exact incidence is not known but may be up to 7%. The pudendal nerve is most frequently affected but femoral, sciatic, obturator and lateral cutaneous have all been described. Fortunately the vast majority are neuropraxia’s and resolve over the course of a few weeks.

The feet are placed in boots. Traction injuries can result in sores and soft tissue damage to the feet. Feet have to be well padded and several purpose designed foam pads are available.
It is imperative that the heel of the foot is engaged fully in the base of the traction boot.
The retaining straps on the boot need to be tightened as much as possible otherwise there is possibility that the foot will disengage when traction is applied.

Traction is first applied to the non operative leg. This will stop the pelvis tilting when applied to the opposite limb. Pelvic tilt will force the operative hip into relative abduction. This will hinder distraction of the joint and also make access difficult since the greater trochanter will be in a higher position. It will be difficult to pass the spinal needle above the trochanter and into the joint.

A trial of traction should be undertaken before skin preparation and surgical set up. This confirms that access to the central compartment will be possible. It also helps to reduce total traction time. An image intensifier is advanced between the legs.

Traction is initially applied by pulling on handles on the apparatus.

Further traction is applied by the handle on the end of the apparatus. This should be gradual and performed with intermittent radiological assessment using image intensifier.

Ensure that the image intensifier is positioned to provide a well centred radiograph of the hip joint and ensure that there will be enough space above the greater trochanter for passage of spinal needle into the joint. This may be improved by adducting the hip. Varus hips can be difficult.

Adequate distraction of the joint is necessary. Ideally one should aim to distract 10mm. If there is insufficient space the risk of iatrogenic damage to the labrum or chondral surfaces will be high. Occasionally the joint will suddenly open with a ‘pop’ as the vacuum in the joint is released. If distraction is difficult the vacume can be released by passing a spinal needle into the joint.

Adduction/abduction can be altered to improve access as can rotation. Very occasionally it is impossible to distract the hip sufficiently to safely access the central compartment (particularly in very muscular male patients). An alternative option is then to access the peripheral compartment first which does not require joint distraction. The capsule can be released so that the central compartment can then be accessed under direct vision.

After confirming that the joint does distract the traction is released. The scrub nurse should then apply skin prep whilst the surgeon scrubs.
The greater trochanter is marked as is the anterior superior iliac spine. A straight ;line is drawn from the ASIS to the head of the fibula. Instruments should only be introduced lateral to this line to reduce risk of damage to the lateral cutaneous nerve.

The standard portals used for central compartment arthroscopy are the anterolateral (AL) and anterior portals (A). The first portal to be created is the anterolatral. This is placed approximately 1cm above and 1cm in front of the tip of the greater trochanter. This may need to be moved slightly depending on the shape and contour of the femoral neck. If there is considerable valgus the entry point may need to be slightly higher and conversely lower for varus femoral neck.
The anterior portal is approximately 5cm in front of AL. The distance will depend upon the size of the patient. In an obese patient the spacing of the portals on the skin will need to be further apart.
Many surgeons will prefer to use the mid anterior portal (MAP). This is not quite as far medial as the anterior portal and is distal by 2-3cm. This portal allows a more oblique access to the anterior acetabulum which is ideal for placing suture anchors if labral repair is indicated.The posterolateral portal is less frequently utilised but can be useful for addressing posterior pathology in the central compartment. Care should be taken not to injury the sciatic nerve.
The proximal mid anterior portal (PMAP) and distal anterolateral portal (DALA) are used to access the peripheral compartment.

Traction is reapplied and the spinal needle introduced in the anterolateral portal under II control.

Visualisation in the coronal plane is simple using II. In the saggital plane this can be difficult. If the needle is more anterior or posterior than anticipated it will pass through the labrum.
If the needle is directed at the femoral neck it is possible to judge placement in the saggital plane. If the needle hits the neck at its apex/horizon it can be assumed that the placement is correct.

The spinal needle can be ‘walked’ up the femoral neck to access the joint.
As the vacuum is broken the joint will often open further and the labrum may be visible (as in this case). It would appear that the needle has been passed through the labrum but this should not cause any damage providing it is repositioned. Do not start passing obturators if there is a suggestion that the needle has passed through the labrum

When passing the needle into its definitive position it is safer to head nearer the femoral head than the acetabulum. If the bevel on the needle is initially pointing towards the labrum (see image) this will give an extra millimetre of clearance.

As soon as the needle is in the joint turn it through 180 degrees so that the bevel is towards the femoral head. The extra clearance will reduce risk of scuffing the femoral head.

A nytinol guide wire is passed through the spinal needle.

Sequential dilatation over the nytinol wire is performed. This should be done with care. The main restriction is the joint capsule. Sudden longitudinal force will cause the obturator to plunge through the capsule. This may result in bending and breakage of the wire or damage to the condral surface of the femoral head or acetabulum.

The 70 degree arthroscope is inserted with the light lead and camera lead facing towards the floor. By doing this one ensures that the initial image is the front of the hip (looking forwards). This helps to orientate the surgeon. Saline should not be turned on at this point. Blood drops to the back of the hip joint due to gravity. Inserting saline when there is no outflow means that the blood mixes with the saline and makes visualisation difficult. Saline should not be turned on until an outflow has been established.

The initial view is somewhat cloudy but after a few seconds the aterosuperior aspect of the hip can be visualised. On the right one can see the femoral head. On the left the acetabulum. The capsule forms a ‘V’ shape. This is the area at which one needs to aim with the second spinal needle from the anterior portal or mid anterior portal.

The anterior portal guide wire should be inserted medial to the line drawn from the ASIS to the fibula head. One needs to aim towards the tip of the arthroscope.

The wire should enter the joint through the capsule as far anteriorly as possible without passing through the labrum. Again, sequential dilatation is performed but this time it is under direct vision. Aim to get green or blue obturator (Smith & Nephew) into the joint.

Once access is achieved saline can be turned on. This should be under pressure (60mmHg).

The next step is to enlarge the anterior portal to allow access of the slotted cannula. A banana blade knife can be passed through the canula.

The slotted canula allows easy exchange of instruments but the portal does need to be enlarged to allow access.

The banana blade is inserted and the cannula removed. Take care to ensure that the blade does not damage the femoral head or labrum. The capsule can be very thick and difficult to cut in some subjects. Enlarge the capsulotomy both forwards and towards the anterolateral portal.

Once there is enough room for the slotted cannula a shaver can then be introduced. This allows clearance of synovium. The size of capsulotomy required is determined by what is to be undertaken. A modest capsulotomy will suffice for a diagnostic ’round’ of the central compartment. If labral repair is to be performed a much more extensive capsulotomy will be necessary essentially connecting the anterior and anterolateral portals.

Whilst the shaver is effective at removing synovium and capsule, it can lead to bleeding. A 50 or 90 degree arthrowand can next be inserted to both secure haemostasis and to expand the capsulotomy.

The capsule can be very thick but when muscle fibres are visible one can be sure that the capsule has been fully divided.

The nextstep is to move the 70 degree arthroscope to the anterior portal and expand the anterolateral portal under vision.Turn the arthroscope through 180 degrees to visualise the anterolateral portal.

The process is repeated with banana blade, shaver and arthrowand.

Eventually the capsulotomy will be completed. Tis allows good access and manipulation of instruments in the central compartment.

A diagnostic ’round’ of the hip can now be performed.The labrum and articular cartilage of acetabulum and femoral head can be inspected. In this case a probe has been introduced into a partial thickness tear of the anterosuperior labrum.

By turning the arthroscope through 180 degrees the posterior aspect of the joint can be inspected. Note the freeing of the posterior labrum.

In the depths of the joint the fovea and ligamentum teres can be inspected.

The peripheral compartment (intra capsular area of femoral neck outside acetabulum) can be accessed in different ways.
If an adequate capsulotomy is performed it is possible to move directly from the central compartment to the peripheral compartment. As traction is released the femoral head neck junction will come into view. It is frequently necessary to excise part of the capsule (capsulectomy) to provide adequate visualisation. The capsulectomy may need to be extended down the femoral neck in a ‘T’ fashion.