Hip arthroscopy

What is a labrum?  The word is simply a Latin word meaning “lip”.  It is a cartilage fluid seal that runs all the way around the hip socket. It “sucks” on to the femoral head, trapping the oily synovial fluid in the joint when we load the hip.  Dr Richard Field, a UK hip surgeon, did some great work to identify how the hip fluid pump works.  The lining of the hip is called synovium.  These cells make the greasy joint fluid.  The fluid collects in the peripheral part of the joint around the femoral neck.  As we walk, the capsule winds up and twists, squeezing fluid from the peripheral compartment into the central compartment under the transverse ligament.  The labrum keeps the fluid there, allowing us to walk around on a very thin pressurized layer of joint fluid. Removing the labrum almost doubles the force transmitted through the gliding surface cartilage.

Removing the meniscus in the knee also doubles cartilage forces and causes a 17-fold acceleration of arthritic progression.  Does losing the hip labrum do the same?  We don’t know.  It is a possible explanation for why a 60 year-old patient can present with bad arthritis in one hip while the other is perfect.  Perhaps the labrum was damaged when they were young?  This is guesswork however and at present we cannot make a prediction that a patient with a labral tear will go on to arthritis.

The labrum may be damaged with certain twisting movements of the hip which bring the neck of the femur (the part of the thigh bone attached to the ball of the hip joint) in to contact with the labrum. The labrum can be torn from its attachment to the edge of the socket.

There are a number of risk factors

1. Cam shaped femoral neck
2. Hip socket is too deep (pincer)
3. Hip socket is facing the wrong way (retroversion)
4. Hip socket is too shallow (dysplasia)
5. Micro-instability
6. Osteoarthritis

There are several ways a labral tear can develop.  With cam or pincer impingement, the labrum can tear slowly over many years.  It is even possible for this to happen with no symptoms.  It is also possible to tear acutely.  Two common mechanisms are:

1. Hard flexion up and across the body
2. Forced extension with external rotation. This is more common and is what usually happens with an awkward fall while out running, slipping over on a slippery surface or accidentally doing the splits.  In this position the femoral head can ride up onto the rim of the socket and produce large stretching forces on the labrum.  Being loose-jointed makes this even more likely.

 A labru tear can produce mechanical symptoms such as clicking and catching in the hip as well as pain which is frequently felt in the groin.  The pain can be during activities such as walking or jogging but is also felt at rest with patients complaining of aching in the hip at night in bed or while sitting with the hip flexed such as while resting in a low chair.

The labrum probably does have some healing potential and it is usual to wait three to six months to see if symptoms abate. Frequently however, by the time my patients come to see me the injury is at least six months old.

Labrum tears are more commonly seen in young athletes who participate in sports requiring a large range of hip motion.  Examples of this would be gymnastics, dancing and martial arts.  If the athlete is very flexible it is easier to bring the femoral neck in contact with the labrum at extreme ranges of flexion and internal rotation of the hip. 

Labral tearing is also part and parcel of osteoarthritis.  The rough joint damages and frays the labrum.  Patients may be sent to see me having been told they have a labral tear.  The natural reaction is to want this fixed.  However if the tear is part of the wear of osteoarthritis, then repairing the labrum will not help at all.  The pain and disability is due to the joint wearing out rather than the labrum hurting.

The history is usually one of an unexpected twisting injury followed by persistent groin pain that will not settle.  The common position of the injured hip is slipping into extension (behind you) and external rotation (toes pointed outwards).  A frequent example is slipping into the “splits” position with one leg going forwards and one leg going backwards. Sometimes, an athlete such as a squash player or a soccer player will have a history of recurrent groin strains which fail to settle.

Examination often reveals a reduction in internal rotation and pain when the hip is flexed up, internally rotated and brought across the body (Quadrant test).

Greater loss of motion in all directions often signifies the onset of more significant arthritis.

An x-ray may show the bony shape of the hip and predisposing factors, but will not show the labrum tear itself as the labrum is made of cartilage.  Common risk factors are a hip socket that is too deep or does not face forward enough (pincer), a femoral neck that is too thick at the front (cam) and an individual who is excessively flexible (hyperlaxity).

An MR arthrogram is the best test to show a labral tear.  An MRI scan uses strong magnets rather than x-rays and shows the soft tissues such as cartilage and muscle very clearly.  An MR arthrogram is an MRI scan taken after the injection of a contrast agent (Gadolinium) into the hip joint prior to the scan. 

The contrast agent is nontoxic and is excreted in the urine a short time after but can make the hip ache a little more over the next 24-48 hours.  The Gadolinium fluid fills the gap between the edge of the socket and the torn labrum, thus outlining the tear. 

The MR arthrogram may also demonstrate some of the predisposing bony factors. However, I also sometimes order a CT scan with three dimensional reconstructions which is the most accurate way to show any bony predisposing factors. 

Cortisone acts like a strong anti-inflammatory.  It can be injected into the hip joint under ultrasound control. I use it in the following circumstances

1. I am not sure if the hip joint is the true source of the pain.  An injection of local anaesthetic and cortisone can help answer this question. Did the local take the pain away for 6 hours?  Did the cortisone reduce the pain for 6-12 weeks?
2. An athlete injures their hip mid-season. A one-off cortisone injection may allow them to complete the season and consider surgical repair in the off-season.
3. As definitive treatment.  Research shows us that if an individual injures their labrum and have no risk factors (pincer, cam, hyperlaxity) there is a 50% chance of long-term relief with a cortisone shot.  This situation is not common.

If a period of rest followed by rehabilitation and alteration of aggravating activities does not result in the pain settling then surgery can be considered. This type of surgery is now performed arthroscopically and can be done as a daystay or more commonly, an overnight procedure. 

 The arthroscope is inserted through one puncture hole and the operating instruments through a second puncture hole.  The edge of the labral tear is cleaned up and the edge of the bony socket is likewise cleaned ready for repair.  A small 3mm absorbable anchor is inserted into the edge of the hip socket and a strong suture is placed around or through the labrum and tied firmly down.

The number of anchors required depends on the size of the labrum tear, but is roughly equivalent to one anchor per 1cm of labral tear.  The anchors are made from an absorbable material called poly-lactic acid.  The sutures are very strong and are not absorbable.

Sometimes the labrum is too small or too damaged to repair.  I make this decision based on whether the labrum can sit firmly against the cartilage of the femoral head and act as an effective fluid seal.  If the answer is no, then repair is probably not the best option.  My first hip arthroscopy mentor, Dr Marc Philippon, developed a great technique to make a new labrum from a rolled-up strip of the ilio-tibial band.  As a reminder, this is the very wide, strong sheet of fibrous tissue that runs the length of the side of our thigh and connects our gluteus maximus (butt muscle) to our shin bone.

Via a 3-4cm incision, a strip of ITB measuring 10cm x 2cm can be removed without compromising the ITB function.  This can be rolled up to make a tube of 10mm diameter.

The damaged labrum is then removed.  This is usually the front 6-9cm of the labrum.  The back part of the labrum is usually fine.  The rim of the socket is roughened and the new “labrum” is inserted and carefully stitched to the edge of the socket.  The surgery is all keyhole.

Does it work?  Surprisingly well.  The average iHOT score (score of pain and function levels) for my 2000 patients is 74 out of 100. The reconstruction group currently has an average of more than 80.

I recognize my own bias as Dr Philippon performed a labral reconstruction on my own left hip in 2011.  This has allowed me to return to regular sport including multisport racing, triathlon, mountain biking and even a couple of ultra-marathons.  The two years prior to this with no labrum was miserable with my maximum walking distance of about 500m.  I am very grateful to Marc for restoring my hip to a great level of function.

The patient is able to go home the next morning and can usually weight bear immediately.  Nonetheless, patients use crutches for between 7-10 days until they can walk without a limp.  Typically most people would need to take 7 days off work.  If the job was very physical such as a construction worker or builder, two or three weeks may be required. 

Using an exercycle or cycling is an excellent early rehabilitation and can be started as early as two or three days post-operatively.  There will also be exercises to strengthen the hip muscles and the core muscles (abdominal and back muscles).  A physiotherapist can often prove very helpful in helping with these exercises. 

Time back to sport is more commonly three to four months. 

Success rates in the published literature with 80 or 90% of patients showing a substantial benefit and in most cases returning to their sport of choice. What we cannot say is how these patients will fare long term (5-20 years plus).  As this technique is relatively new most published studies have two year follow-up and occasionally five year follow-up.

Femoroacetabular impingement or FAI simply describes the action of the femoral neck hitting the edge of the hip socket.  We can use the simple example of a tennis ball pierced with a broom stick. If the tennis ball is placed inside a large teacup the broom stick can be moved through a range of motion before it hits the edge of the teacup.  If we replace the broomstick with a vacuum cleaner pipe (much thicker) we will be able to move it through a smaller range of motion before the pipe will hit the edge of the teacup.  This could be considered the equivalent of CAM impingement.  If we return to using the broomstick, however place the tennis ball inside a deeper coffee mug, again we will be able to move it through a smaller range before the broomstick will hit the edge of the coffee mug.  This could be considered the equivalent of Pincer impingement. 

A and B: The cam lesion comes forward and hits the labrum
C and D: The normal femoral neck comes forward and strikes the “Pincer”

Returning to the human example, there is a wide range of normal anatomy.  Some people have a narrow femoral neck and thus their hip has to move a long way before it will impinge.  Others have a much thicker femoral neck, especially at the front and in these patients, they do not have to flex their hip very far before it will impinge.  This thick bony bump at the junction of the femoral head and the femoral neck at the front is known as a CAM lesion.  It is not a medical term but a simple engineering term. It simply gets this name from the same principle as a CAM shaft in a car engine representing an asymmetric bump.  In the case of a Pincer lesion, it simply denotes a hip socket that is very deep or an isolated  prominent rim at the front or back.  In a normal pelvis the hip sockets face forward, but in some patients they face sideways or even slightly backwards (retroverted acetabulum).  In these patients, the front rim of the socket is prominent and impinges relatively easily. 

The bony cam lesion is easily seen on this 3D CT scan

Are there differences between men and women?
CAM type impingement is more common in men.  Pincer impingement is more common in women.  However, a significant number of patients have a mixture of both. 

This depends on the type of impingement.  When a patient with a CAM lesion flexes up their hip too far, the bony bump must be accommodated with in the rigid hip socket.  This is like trying to get an egg into an egg cup sideways. It just won’t work.  The bump pushes the labrum aside and then starts to shear the articular cartilage (gliding surface gristle of the hip).  I use the analogy of pushing a heavy chair across a rug on the floor.  The chair will catch the rug and push it up off the floor in folds.  The gliding surface of the hip is well fixed to the underlying bone but if the CAM lesion strikes with sufficient force the cartilage gliding surface is pushed away from the underlying bone and is thus permanently damaged.  Unfortunately the human body has no way to repair damaged articular cartilage.  The flap of damaged cartilage can become painful and the area of damaged cartilage can become larger and larger with time.  This eventually leads to osteoarthrosis and for a number of patients, a total hip joint replacement.  Eventually the labrum too becomes damaged.  It is remarkable that some young men can have significant damage to the articular cartilage even before the hip becomes painful.  I suspect that in some of these young men, the pain comes eventually when the labrum becomes damaged as it does contain plenty of pain nerve fibres.   

Unfortunately the cam lesion has permanently damaged the white gliding surface (articular cartilage)  The yellow is the underlying bone.  

With a Pincer type of impingement (a deep cup or a prominent hip socket rim) the pattern is different.  The labrum is often the first structure to be damaged and pain comes on very early in the process.  When the femoral neck forcibly hits the labrum, it is squashed and bruised (contused). This alone can be very painful. It can be torn from the edge of the socket and pain can be accompanied by popping, clicking and catching.  The patient also develops nagging background groin pain that is often troublesome at night in bed.  The pain can be felt also at the side of the hip in the buttock and also sometimes down the leg.

The answer is not very well.  Cartilage research is a billion dollar business and as yet no one can reproduce the beautiful hyaline cartilage we are born with.  We get one layer and it has to last a lifetime!  Cartilage has just enough cells to survive but no capacity for repair. 

When damage is partial thickness, we leave it alone.  Any cartilage is better than repair cartilage.

When damage is full thickness we perform a procedure called microfracture. The bare bone is carefully scraped then 1-2mm holes are punched in the underlying bone.  This allows bone marrow stem cells to escape and form a blood clot. Eventually this hardens into fibro-cartilage (fibrous cartilage or scar tissue cartilage)  My analogy is filling a pot hole in the road.  It is not as good as a new road but is better than a pot hole. 

The cartilage is not as durable and can wear out in 3-5 years.  Surprisingly microfracture does much better in the hip than in the knee.  One study showed no difference in the level athletes reached post op when patients who required a microfracture were compared to those who did not.

One big difference is the time on crutches.  Patients who require a microfracture get 6 weeks on crutches instead of the usual 2 weeks.  We also ask them to avoid impact loading (jogging, running sport, walking for fitness) for 6 months.  The healing cartilage takes a long time to harden.

Here is a microfracture.  Socket on the left, ball on the right.  You can see the three small holes punched in the bare bone. Come back in a year and it will look like white glossy cartilage.

You may read about expensive cartilage transplant techniques being performed overseas. At present these complicated procedures are showing results that are no different to microfracture.

The answer is yes….and no!

The most destructive pattern of FAI is a large cam-shaped femoral neck with a relatively shallow socket (centre-edge angle <30 degrees). In this case, the cam can penetrate deep into the socket and tear up the precious articular cartilage. The athlete is usually male and this is one instance that I will strongly recommend stopping all risky sport or consider surgery.  The hip can be irreversibly damaged even when the athlete is in their early 20s.

A deep socket is relatively protective.  The cam can no longer penetrate as deeply into the socket and also there is a greater area of cartilage to get by on.  If a patient has a deep socket and the MRI does not show arthritic wear, I can be reassuring that time is on our side.  There is no need for a quick decision and a “see how it goes” approach is very reasonable.

Roughly 15% of New Zealanders will one day need a hip replacement, usually when they are very old.  Looking at patients who need a hip replacement before the age of 65 years, FAI would be the biggest cause.  We cannot look at a young patient and predict “You will get arthritis”  unless arthritis is already present.  All we can say is “You are at greater risk of arthritis.” Most patients with FAI risk factors in the shape of their hip do not get arthritis.  It will depend on:

1. How severe the risk factors are.  How big is the cam / pincer?
2. What activities are undertaken.  A couch potato will be unlikely to get arthritis even if they have a big cam or pincer.  Athletes do more damage especially in risky sports such as squash, football and martial arts.
3. The genetically inherited quality of the articular cartilage.  This is not something we can measure yet but if family members have needed hip replacements young then it is likely the cartilage is “B” grade rather than “A” grade!

We don’t know.  To answer this question we may need 10-20 more years of long term follow-up and careful research.  This currently should not be part of the decision-making process.  We do know the surgery is very successful at reducing pain and restoring function.  Pain and function should remain the basis for deciding to have surgery.

We do know that extensive damage to the hip is a poor predictor of outcome with the magic number being around 30% of the gliding surface of the hip socket. If damage exceeds 30% of the area then it becomes likely that arthritis will progress no matter what we do.  If the gliding surface is still in good shape or considerably less than 30% damaged, the outlook is a lot brighter long term. 

It is a case of “so far, so good” and as surgeons we are optimistic we will reduce further damage.  Surgeon optimism should not be mistaken for science!  Anterior cruciate ligament reconstruction in the knee was presented for a period as an “arthritis-preventing” surgery as an unstable knee leads to cartilage damage and meniscal tears.  Unfortunately large studies did not support this “surgeon optimism” and showed a roughly 50% late arthritis rate whether or not surgery was chosen.

At the time of writing this I have completed well over 2000 hip arthroscopies and 58 hips have been replaced over the past 13 years.  This is a rate of about 2.8%.  This is lower than any other currently published international result (6-15%)  It reflects my care in counseling patients who already have arthritis away from keyhole surgery and being well over the 500 case learning curve.  My conversion to hip replacement rate in my first 500 cases was 4%.

It depends…..

If hip replacement is subsequently required in the first two years after hip arthroscopy, the most common cause is too much arthritis at the time of surgery. I try very hard to scrutinize imaging looking for bone cysts, bone spurs (osteophytes), bone bruising (oedema) and cartilage loss, especially from the femoral head.  If I see these signs I will often recommend against keyhole surgery.

There are also surgical reasons which can result in rapid deterioration of the hip. This includes if the surgeon:

1. Removes the labrum or repairs it in a manner that it can no longer press against the femoral head as a suction seal
2. Takes too much bone from the edge of the socket making it too shallow
3. Takes too much bone from the edge of the femoral head
4. Does not repair the stabilizing capsule in a very lax individual

Remember that no injured joint in the body can ever be regarded as “normal” again, whether or not surgery is undertaken. Thus it is likely that all patients who have damage to their articular cartilage will carry a higher lifetime risk of requiring a hip replacement.

Labral and cartilage tears can and do occur in the adolescent athlete.  The most common age for a patient with CAM type impingement to present would be a young man in his 20’s.   Kicking sports and sports such as squash where the athlete lunges onto the flexed hip are a common presenting feature.  The most common age for the Pincer type impingement to present would be a woman in her 30’s or early 40’s. 

Typically the older the patient and the longer the history, the worse the damage to the hip joint at presentation.  Unfortunately a more damaged hip joint has a worse prognosis whether or not treatment is considered. 

If the joint space of the hip on xray has narrowed, it usually means the arthritic process is too advanced and the patient will not benefit from arthroscopic treatment.  If I am unsure, I will sometimes order a CT scan which shows even tiny reductions in joint space.

If this is the case, we recommend non-impact exercise such as cycling, weight loss (where appropriate), platelet-rich plasma injections, anti-inflammatory tablets and eventually total hip replacement may be required.

This young male athlete still has a good joint space on the left but unfortunately the right hip is well past the stage when arthroscopic surgery would be helpful.  This is a good example of the destructive power of the large cam with a shallow socket.

When there is ANY evidence of osteoarthritis, the conversation needs to be different.  The hip now has a permanently altered internal environment. It cannot be made normal. Even if hip arthroscopy is still justified, expectations need to be lowered.

Reinhold Ganz is a Swiss surgeon who was one of the first to clearly understand the impingement mechanism.  Surgeons before him had recognized that certain patterns of hip shape would predictably lead to arthritis but Ganz provided an eloquent explanation.  He first described the CAM and Pincer type impingement and was also the first to outline a surgical treatment.  Ganz and his colleagues figured out a way to dislocate the hip joint surgically without damage to the blood supply to the femoral head. Once the hip was dislocated they would have full access to the bony bump (CAM lesion) as well as the labrum and edge of the hip socket (removal of Pincer and repair of labrum).  This was, however, a considerable operation with a similar surgical trauma to a total hip joint replacement.  Nonetheless, he has published good results with this technique and it is still used in many centres today. 

In the last fifteen years arthroscopic surgery of the hip has developed very rapidly to the stage where we are able to repair a labrum, remove a Pincer lesion or remove a CAM lesion.  This has the major advantage of causing the patient less pain and allowing a quicker recovery.  We can even make a new labrum from a strip of ilio-tibial band.

An arthroscopic motorized burr removing the cam lesion

Typically the operation can take anywhere from 90 minutes to 2 1/2 hours and the patient will stay one night in hospital.  Immediate partial weight bearing is usually allowed and crutches are used for  about 2 weeks days until the patient can walk without a limp.  Hyperlax patients require four weeks crutches and patients with a shallow socket or a microfracture for damaged cartilage require 6 weeks crutches.  Most patients can return to work after a quiet 1-2 weeks at home.  If the job is very physical such as manual labouring or a builder, it may be necessary to take 12 weeks off full duties.  Time back to sport is anywhere from 3-6 months although fitness activities such as going to the gym or riding a bicycle can start almost immediately. 

Short to medium term follow-up (two to five years) have been published with excellent results.  My own patients are all prospectively followed filling out three hip scores (nonarthritic hip score, WOMAC score and iHOT score) before their operation as well as 6, 12 and 24 months after their operation.  There are significant improvements in both pain and function at the six month follow-up and this continues to improve all the way through to one year. 

These are the six month scores of my own patients. (A low score is better!)

Having completed well over 2000 hip arthroscopies I would be amongst the top 20 surgeons internationally by volume.  But what about the results?

 UK Non-Arthritic Hip Registry 2018

This excellent graph illustrates the results from hip arthroscopists in the UK with almost 10,000 cases in their database.  The graph shows a very wide range of scores at every time point.  The iHOT score is perhaps the “hardest” score with 100 being a prefect score.  The average starting score is about 36 points.  My own results show an almost identical starting score.  The average 1 year score is around 59 points.  The minimum useful improvement is around 6 points.

These are my results divided into age groups.  The average finishing iHOT score is 74 points. It is difficult to directly compare to the UK results as I am one high-volume surgeon and the UK results are many surgeons.  Also there may be cultural difference….perhaps kiwis are tougher and report better scores?  Against this, starting scores are the same.

 Anyway, at the very least it suggests my results compare favourably with others.

Up until a few short years ago, I could not have answered this question.  It is now a central topic at our annual international meeting of hip arthroscopists.

When I was training, we were taught that the hip joint is a joint of almost pure rotation.  After all, it is a deep ball and socket joint right?  We now know that an individual of normal laxity will still have 1-2mm of sideways movement of the ball in the socket (translation). A very lax individual can have up to 5mm!  This means the ball is quite literally wobbling in the socket. 

Micro-instability often presents in the teenage girl.  Typically dance or gymnastics select for more flexible athletes and then the activities themselves require further stretching and range of motion.  The result can be a “wobbly painful hip”.  I have had young women who have had a “normal” x-ray and MRI and have seen many doctors, surgeons and other health professionals.  Some have been referred to the pain service as a “chronic pain sufferer” and even to psychiatrists.

The first clue is the “Beighton’s score”.  This is a 9-point scale of flexibility where a score over 4 is considered hyperlax.  There are other clues such as:

1. Positive dial test (foot flops into external rotation on the bed)
2. Very wide range of hip rotation (greater than 100 degrees)
3. Positive instability test, pushing the hip into abduction and external rotation
4. Labral tear right at the front (3 o’clock) under the ilio-psoas tendon
5. Gadolinium contrast agent pooling in the back of the hip joint on the sagittal cuts on MRI
6. Athlete reports hip feels unstable and clicks / pops / gives way

There is no single definitive test.

Studies have shown that rehab (strong gluteal muscles and core) helps but does not take the problem away.  This is similar to shoulder instability where having strong muscles will not prevent the shoulder from subluxing or dislocating.

Surgical treatment involves tightening the front of the capsule. When I perform hip arthroscopy I make a curved 30mm cut in the front of the capsule to gain entry to the hip.  I routinely close about 60% of this cut with two dissolving stitches.  In order to tighten (plicate) the capsule, about 3mm of one side of the cut is removed (making an ellipse) and the cut is sewn firmly shut in a deliberately crooked fashion.  This is like buttoning up your shirt crooked.  One side is hoisted higher.  In this case the very important ilio-femoral ligament (a thickening of the capsule) is pulled tighter.

Dancers worry that this will permanently remove their hard-fought range of motion.  There is no need to worry.  Most people feel tight for 3-6 months but inevitably full range returns.  I am not sure I could make a lax person permanently tighter even if I was trying to. 

Does the instability return?  Thus far the answer is no.  I have plicated about 150 patients, mostly women, and have not had to perform revision on any as of Dec 2018.

The good news for unstable patients is that recovery is relatively quick.  By the three month check the hip is usually going really well.  The hip usually only has minor cartilage damage despite the major symptoms.  Final outcome scores are some of the best.

An arthroscope is a small telescope that allows the surgeon to investigate and treat a joint without making a large incision.  The part of the telescope that is inserted into the joint is roughly the same size and length as a pencil.  The telescope is attached to a small video camera that produces a high resolution image on a television screen. 

 Another small puncture incision is made to allow instruments to access the joint.  Specialised instruments such as scissors, graspers and cutters are used as well as motorised shavers and burrs.  More recently radiofrequency devices have been developed which can both cut and coagulate with minimal damage to the surrounding tissue.

The patient can be positioned on the operating table either on their back or on their side with traction applied to the leg.  A muscle relaxant is included in the anaesthetic to facilitate distraction of the hip joint.  The traction device has a large padded bolster that protects the patient’s groin and a traction boot that looks similar to a ski boot allowing traction to be applied the affected limb. In this way the hip joint can be distracted by 1-2 centimetres allowing the insertion of instruments to proceed without damage to the surrounding joint.   

The two puncture holes are roughly 1cm in size and are located about 10cm apart on either side of the bump of the hip bone.

One important factor which I have noticed from the beginning and has now been researched and published is that men and women experience different amounts and types of pain.  Men are often quite comfortable right from Day 1, especially if they are well muscled. Men report pain levels as low as 1-2/ 10 on Day 1 whereas female patients may report something closer to 3-5/10. Male patients tend to be fairly comfortable within one or two weeks whereas female patients may take anywhere from six to twelve weeks to feel really good.  Often the progress can feel like two steps forward followed by one step backwards.  Recovery is not a steady progression. 

During the arthroscopic surgery the capsule (fibrous bag that contains the hip joint) must be cut open to gain access to the hip.  This is stitched closed at the end of the procedure but still has to gradually heal over twelve weeks after the surgery.  As the capsule finally heals, the hip can often feel more stiff and sore.  This often happens somewhere between ten and twelve weeks post-op.  I see all patients around twelve weeks because around one in five patients gets very stiff and sore and benefits from an xray guided cortisone injection to reduce their stiffness and get them back on track.

I suspect that the sex differences may be due to the wider female pelvis having different force vectors and females also typically carrying less muscle around their hip.  Nonetheless, with the passage of time the female results catch up to their male counterparts. 

During the twelve week early healing phase the patient may be completely comfortable while walking, sitting or lying, but get a sharp jab of pain with a sudden twisting movement.  This is likely stretching the healing capsule.  An example would be trying to do a breaststroke kick in a swimming pool two weeks post-op would almost certainly be painful.  Swimming freestyle, however, would likely be no problem. 

It is important to acknowledge the amount of pain suffered prior to surgery. If a patient reports high levels of pain (6-9/10) pre-op then they will experience worse pain post op.  Studies have shown that patients who require strong narcotic pain relief pre-op do not do as well post op.

It is most unlikely that you would need strong pain relief.  Most of my patients go home with a prescription for simple Paracetamol and perhaps an anti-inflammatory such as Diclofenac (Voltaren). The anti-inflammatory also has a very important second function: it is very effective in stopping bone forming abnormally in the soft tissues around the hip (heterotopic ossification or HO for short).  We thus ask that the anti-inflammatory be continued for 28 days irrespective of pain. In the first 48 hours a stronger pain relief such as Tramadol is provided, but often it is not required.

Again, patients who need strong pain relief pre-op will probably need strong pain relief post op

I have found that an exercise bike is often better than pain pills.  I ask all patients to have one set up in a nice warm place like the living room right in front of the TV!  If the hip is a bit stiff and sore, especially right before bed, a two minute spin on the bike with no resistance often resolves the pain with no need for pills.

In most cases the answer to this question is yes.  The time that I voice a word of caution is when damage to the hip is already extensive and there are significant areas of the acetabular gliding surface already damaged.  In these cases I suggest avoiding impact loading (running sport) for twelve months then repeating an x-ray and a bone scan to detect any advancing arthritis in the hip.  Any damage to the hip is clearly documented with photographs during the operation.  I keep electronic copies but the printed copies are handed to the patient. 

Studies so far have shown that the bone removed does not appear to grow back.  I have not seen this in any of my patients nor have my overseas colleagues.  The commonest reason for having to repeat the surgery would be if the surgeon has taken insufficient bone and the hip continues to impinge.

 My revision rate in the first 500 cases was 10%.  The commonest reason was inadequate bone removal.   Knowing that removing too much bone is irreversible and catastrophic, I erred on the side of caution.

My revision rate for the past 1500+ patients is 2.7%  The commonest reason for revision now is excessive scarring around the labrum (capsule-labral adhesions)  Our natural tendency to make scar tissue is probably genetically determined and very variable.  In some patients they report no improvement at all at 12-18 months post op despite the xray and MRI looking good.  In such a case, adhesions / scar tissue is usually the answer.  Revision surgery can still be very successful and in my hands the answer is to reconstruct the labrum using a 6-8cm strip of ilio-tibial band. This has produced surprisingly good results with the average iHOT score for the reconstruction patients being a little higher than the whole patient cohort.

Comparing my results to those around the world again suggests I am doing OK. Revision rates in the state of New York (insurance database) is around 5% with a hip replacement conversion rate of 10%.  Similar results have been shown in the UK.  The ideal revision rate is zero but if I can continue to keep the revision rate below 3% then I will be doing much better than most of the world.

Fortunately complications are few but can be listed as follows:

Traction injuries:  The traction boot can cause pressure areas on the ankle or the heel and also around the genital area in women and behind the scrotum in men (The perineum).  Other than some redness of the skin which resolves within an hour or so, I have had one skin blister in one female patient near her sit bone.  The nerves to the genitals can be compressed.  Around 1 in 100 patients may get some genital numbness but in my experience, this usually only lasts one to two days.  I have had one young man who reported numb genitals for about 3 weeks with full resolution.

Anaesthetic complications:  In a healthy person a modern general anaesthetic is exceedingly safe with rare and catastrophic problems such as very severe drug reactions being around 1 in 500,000.  How risky is that?  Probably safer than driving your car!

Stress fracture:  By removing bone from the femoral neck, theoretically the femoral neck is weakened. I have had one patient out of 2000+ who has experienced a stress fracture which healed after a period of six weeks on crutches.  He was very active walking long distances daily and cycling 400km per week plus and experienced an increase in groin pain around six weeks post-op.  The message here is that we gradually increase loading on the hip over the first twelve weeks without doing too much too soon.

Avascular necrosis of the femoral head:  This is perhaps the worst complication but fortunately is extremely rare.  It has been described in the overseas literature but to the best of my knowledge has not occurred in New Zealand yet.  At the time of arthroscopic surgery we take great care to avoid the three or four blood vessels that supply blood to the femoral head. Theoretically if all four of these blood vessels are damaged the femoral head will gradually die and crumble over the next one to two years necessitating hip replacement.  The four blood vessels are in a fairly constant location and this is clearly in our mind when we are removing bone to keep well away from them.

Adhesive capsulitis (Frozen Hip): This is most certainly the most common complication I see and usually manifests sometime between eight and twelve weeks post-op.  The healing capsule becomes thick, tight and inflamed.  The patient feels as though they are making good progress over the first six to eight weeks but then gradually the hip becomes more restricted and painful.  In my experience this responds best to an xray guided cortisone injection which fairly quickly gets the patient back on track.  As with frozen shoulder it is more common with women than men.

Removing too much or too little bone:  In the early international arthroscopic experience frequently too little bone was removed as in the magnified setting of an arthroscopy it can be difficult to orientate and the amount of bone we remove looks enormous when often it is only be a few millimetres.  To avoid this I perform an impingement test where the patient’s hip is flexed to around 90°and internally rotated during the course of the operation as I watch the femoral neck come close to the labrum. I know my resection is adequate when impingement no longer occurs.  We also use the xray machine during the operation to guide us.

Removing too much bone is a disaster.  I suspect this is behind the poor results and high conversion rates to hip replacement reported around the world with pincer resection.  The prevailing wisdom has been that trimming a socket that is too deep does not do so well. This has not been my experience and when we have looked carefully at our results we find they are just as good. The difference is I minimize my socket resection.  I aim for a socket depth that is just inside the normal range rather than at the shallow end of normal.

Studies have been performed to show 30% of the femoral neck can be removed without too much loss of strength.  This would be a massive resection and it would be usual for us to remove considerably less than this.  Nonetheless, this remains challenging surgery and this is one of the major reasons why the New Zealand experience has been concentrated in the hands of only a few surgeons.

Nerve Injury

The surgery does not go near any significant nerves.  I operate with my patient lying on their side.  This means I am well away from the main skin nerve to the front of the thigh. Surgeons who operate with the patient lying on their back tend to be much closer to this nerve.  If a patient experiences any numbness in the limb, it will be the result of the traction on the limb rather than a cut or damaged nerve. Because of this, recovery is quick and almost universal.

 Deep Vein Thrombosis

 I have had 7 patients experience a clot in the veins of the calf muscle.  Only one was less than 40 years old.  Our routine prevention is

1. Get out of bed on day of surgery
2. Compression stockings
3. Clexane (blood thinners) and mechanical compression boots for those with personal or family risk factors for DVT

 Treatment for these patients is usually oral blood thinner tablets for 3 months

A study from the University of Oxford showed that 95% of female patients with a labral tear have difficulty / hip pain with sex pre-op.  The study also looked at how long it took to return to normal function.  For women it was about 12 weeks and for men about half this time.  There are no strict rules regarding when a patient can re-start their sex life post op but with a sore hip containing scar tissue some common sense is important.  The hip will hurt (a lot) if it is suddenly pushed beyond the comfortable range of motion.