Surgeon's Overview
The principle of gaining access to a hip is simple, once one understands that anatomy and suction are responsible for hip stability. It is overcoming the suction that is important. Distraction is not a matter of pulling incessantly until the joint eventually gives way. Essentially, to make sufficient space for an arthroscope requires the creation of an iatrogenic effusion. Distension is the secret, not distraction.
You can use either a standard orthopaedic traction table or a specialist distracter. I prefer the latter, though realise that most units not undertaking a large number of hip arthroscopies may be unable to justify the expense of a specialist device. I find that a standard traction table allows me access to most hips, but I am unable to do very much once inside. For the `difficult' hip, or where I need to operate (for example, labral resection), I find the specialist device invaluable.
The sequence of events is as follows:
- Position the patient while unscrubbed and obtain a good AP image intensifier view, making sure the hip joint is as near the top of the screen as you can.
- Be certain to pad and protect the patient carefully, particularly the perineum. Pressure necrosis is a real risk.
- Apply traction. It is sometimes best to ask an assistant to do this while the surgeon is positioned by the hip. Keep pulling until the image intensifier view shows the tiniest amount of distraction. This is usually a radiolucent `halo' that appears over the upper part of the femoral head, the so-called `vacuum phenomenon'. Once you have seen the halo, you know you will be able to get into the hip. If you do not see a halo, it is likely you will have difficulties. All patients should be warned beforehand that you may not gain access to the hip. I also suggest you tell them there is a slightly less than 5% chance of making them worse!
- Release the traction. The halo will disappear. The 'trial of traction' is now complete.
- Go and scrub up while your theatre sister or orderly prepares and drapes the patient for you. This saves a vast amount of traction time and reduces the risk of complications.
- Once all drapes are applied and instruments readied ask that traction is reapplied. Regain the halo on the image intensifier view.
- Pass a thin spinal needle (22-gauge) into the hip joint and remove the trocar. You should hear a gentle `hiss' as air passes into the joint. The hip will distract, sometimes with a jerk, and an image intensifier view will show an air arthrogram to confirm your position. You may have to inject air to achieve this.
Halo apparent and spinal needle in position.
- Inject normal saline. As you do so, you will see a fluid level move laterally, slowly eliminating your air arthrogram. Put in as much fluid as you can. 20 mls is usual.
Halo has gone now that 20 mls of saline has been instilled.
- Once the hip is distracted, remove the 22-gauge needle and insert a broader, 15-gauge needle into the hip by eye.
- Insert a second 15-gauge needle approximately 3-4 cms away from your first one. Assuming you are using a supratrochanteric approach, I favour the first needle being directly above the tip of the greater trochanter, the second anterior to this. The posterior area is kept for an operative portal, if needed.
Two 15-gauge needles are now in the joint.
- Pass a long, blunt-ended, flexible guide wire down the posterior of the two needles (check it will fit before surgery starts) and remove the needle.
- Make a stab incision around the base of the guide wire.
- Take a cannulated, sharp, 4.5mm arthroscopy trocar and cannula and pass over the guide wire with gentle pushing and twisting movements. Check the image intensifier view from time to time, but be certain only to penetrate the capsule with the sharp trocar. You will feel the instruments lurch into the hip as you perforate the joint. It is important that you do not lurch so far as to damage the acetabulum. You do not need an extended arthroscope for the average hip arthroscopy. You will need one for a particularly obese patient, but it is debatable whether you should be arthroscoping such patients anyway. If you do not have cannulated instrumentation hip arthroscopy is still possible, but requires greater use of the image intensifier and is harder.
Sharp trocar, having been passed over the guide wire, has just penetrated
the capsule and is about to be exchanged for a blunt trocar. - Once through the capsule, exchange your sharp trocar for a blunt one and insert fully into the joint. Remove the blunt trocar and guide wire as one.
- Insert a 70-degree arthroscope. This takes some getting used to, particularly if you are accustomed to a 30-degree arthroscope for the knee.
- Connect your camera and fluid management system. The latter is ideal as bleeding can be a genuine problem at hip arthroscopy, as can fluid extravasation. Make your fluid inflow through the more anteriorly placed 15-gauge needle and the outflow via the arthroscope.
- You're there!
- Should you need to pass a hook or other instrument into the joint I suggest you insert a 15-gauge needle first, under direct arthroscopic view. Ensure the needle tip is positioned immediately beside the area you are trying to reach. If you cannot get a needle onto it there is little hope of being able to instrument it subsequently. Much pathology is found in the anterior part of the joint. It may thus be possible to use your anterior irrigation needle to develop your instrument port, rather than inserting a separate needle altogether.
- Once the 15-gauge needle is positioned where you want it, pass a guide wire down the needle, remove the needle, make a stab incision, and then insert a 1cm plastic cannula using a sharp, cannulated trocar, again only going through the capsule before exchanging the sharp trocar for a blunt one. The trocars are best specially made to fit the cannula. Those for the arthroscope are likely to be too thin.
- Pass whatever instrument you wish down the plastic cannula. Extended, curved, incisor blades (concave and convex cutting) and suction forceps are particularly useful.
Partial labrectomy in action using a curved incisor blade
passed down a 1cm plastic cannula. - When all is over remove everything except one 15-gauge needle. Use this to take off any residual saline and to inject 10mls of 0.5% bupivacaine (plain). There is no need to suture or Steristrip the wounds. A dry dressing is all that is required.
- I keep patients non-weight bearing for four days after surgery, purely as a precaution. I have no evidence this is essential. It just seems a reasonable thing to do!
- Physiotherapy is essential and should continue for at least a month. Patients can expect discomfort for a fortnight and should be warned that there will be ups and downs for up to three months. As a rough guide, the three-month result matches that seen at two years