Dr. Schmalzried Interview by Patricia Walter Sept. 5, 2009 in Baltimore MD at the 3rd Hip Resurfacing Course
Which Hip Resurfacing Devices do you use? I use the Cormet 2000 but have also used the C+ and the BHR.
Do you know of any problems with the conserve plus? The C+has worked very well in my hands. I have 8 year follow-up with this device.
Do all the current devices use approximately the same clearance? There is difference in the clearances – and it makes a difference in lab studies of wear – and some clinical studies – low clearance has less wear and lower ion levels.
As far as clearances are concerned, which implants do you think are best? Is implant selection something patients should be concerned about, or do you feel it’s more about the physician’s preference? The ASR has the smallest clearance. I think that the surgeon should choose.
What is the best maintenance exercises for a bilat 61 yr old with good bone? I like bicycling for exercise. Yoga is good too. Swimming never hurts. I don’t have any restrictions – so impact activities are OK if you can handle it!
Are there any particular physical therapy exercises that you like at about 5 weeks post op? I would stretch for abduction, external rotation and flexion. I like the stat. bike and swimming at this stage.
Would you consider using computer assisted surgery? Navigation can be helpful but there is no data as yet to show that the outcomes are better – in the hands of an experienced surgeon. The best benefit may be for the new surgeon.
Do cysts prevent hip resurfacing? The cyst, by itself, is usually not a problem. If your bone density is good – and the shape of your head and neck are good – resurfacing is probably a good option.
Can leg length problems be corrected with hip resurfacing? Limb length can be an issue with resurfacing – but probably less than with THR. Our data indicates that on average we gain 4mm of length.
Is it common practice for a representative of the company manufacturing thehip resurfacing device to attend the surgery? It is common to have the rep in the room at surgery.
What is your response to the recent research showing “red flags” for doing the hip resurfacing procedure on women? The Aussie registry, and the experience in several single-surgeon series show higher failure in women. More recent data indicate that it is more related to SMALL SIZE. Probably the fundamental variable is cross sectional bone mass – the short term failures are usually neck fracture. Resurfacing can be done on women with great success. It is not a gender issue per se. It is a bone mass issue. Anyone with decreased bone mass has a higher risk of FNF Femoral Neck Fracture.
What do you think of bone density drugs like fosamax? I like a combination of nutrition, exercise and – in appropriate patients, chemical treatment of osteoporosis.
When can a paatient exercise on a recumbent stationary bike after surgery? Recumbent bike – wait one week.
Do you allow your patients to engage in downhill snow skiing? I do not discourage any activities. There is no data on “appropriate” post-op. activity – and I have researched and published more on this topic than anyone.
How do you determine if a small woman is a good candidate for hip resurfacing and has good bone mass? For the petite woman – I can usually tell by looking at their hip x-rays.
When do most of the Femoral Neck Fractures occur? Most Femoral Neck Fractures occur within the first 6 months.
What generally would contribute to femoral neck fracture within 1st six months? Femoral Neck Fracture is basically a mis-match between the strength of the neck after surgery and the loads imposed on it by the patient activities. The factors include the density and size of the femoral neck, the quality of the surgery and the activity of the patient.
How many female Femoral neck fractures have you experienced? I have not had any patient have a Femoral Neck Fracture – yet!
Is there any data on rehab? Little data on rehab. The patient is the biggest source of variability.
What is metallosis and who is at risk? Symptoms? Metallosis is high wear if the bearing with the generation of lots of metal wear particles. It is usually a result of sub-optimal component positioning.
If components are positioned incorrectly, how long before metallosis can occur? If the components are well-made and well-positioned – metallosis will not happen.
How can you find out if you have elevated metal ion levels and or metallosis? Ion levels can be determined by a blood test. The issue is what level is too high?
If a hip resurfacing fails, does it complicate a subsequent revision to a THR? There are now 2 studies – Amstutz series and Mont series – indicating that the conversion of a hip resurfacing to a THR gives a good result.
Do you ever go into the surgery with the intention of doing resurfacing, but once inside, decide that a hip replacement is what is needed? I make the decision before surgery – I am pretty selective on resurfacing. We published selection criteria in 2005 and I stick pretty close to them – so I don’t have to make decisions in surgery.
How can you determine “good bone density” prior to surgery? Bone density can be assessed on the x-rays and by a DEXA scan.
Do you recommend that patients be tested for metal sensitivity before receiving MOM implants? There are no good tests for metal sensitivity to deep implants.
Do the protheses come in smaller sizes? Does the rod change size proportionately with the size of the device? Some systems have smaller sizes and some have proportionate pins. For example, the ASR and C+ have small sizes and proportionate pins.
What is your opinion about uncemented femoral implants with porous bone ingrowth surfaces? Uncemented femurs were used at UCLA in the 1980’s and they can work. There is little data on cementless femurs with the current generation implants.
Do you usually have patients do a CT scan pre-op? NO pre-op. CT.
How long is the hospital stay typically for resurfacing surgery Our usual hospital stay is 2 days.
Is there any way currently to measure bone density in femoral neck after resurfacing? Bone density can be measured by a DEXA scan and there are at least 3 published studies on this.
If a person has a metal sensitivity, what is recourse? If a patient has a metal sensitivity – they may need a conversion to a non-metal-metal bearing THR.
Do you suggest rehab following surgery? I don’t favor rehab units for my patients.
Can a person with hip dysplasia have a hip resurfacing? With dysplasia – it depends on the amount of socket bone and the anterversion of the femur. A look at x-rays can tell.
Can a person with AVN be a candidate for resurfacing? Patients with AVN can be candidates for resurfacing. Many hips with AVN have been successfully resurfaced.
Are a large number of your patients resurfaced due to AVN? I think that it is only about 10%.
How quickly must you have surgery if AVN is detected ? You should only have surgery if the pain and disability out-weigh the risks of the proposed surgery.
Do you see a lot of cam FAI in young men? Yes. Cam impingement is common. I have it in my own left hip – but have lived with it – played college basketball, tennis – and I am still managing without any surgery.
Can a person destroy their hip resurfacing by being too active early in their post op recovery? There is the possibility to over-stress the resurfacing before adequate healing.
What is adequate healing time? Adequate healing time is dependent on patient and surgical factors – it is not a definite line.
You prefer the posterior approach while some others prefer anterior (Dr. Mont). Which surgical approach is the best? Dr. Mont uses the antero-lateral approach. There are trade-offs – but the overall quality of the surgery is more important than the path into the hip joint.
Is surgery the only way to determine metal sensitivty? Metal sensitivity can be determined by an examination of tissue from around the hip – so a biopsy can give that information.