Aims

Will Hydroxyapatite ceramic coated (HAC) arthroplasty perform well in patients under the age of fifty?

Aims

Will Hydroxyapatite hip (HA) arthroplasty associated with ceramic bearings produce uncomplicated function in younger, active patients’ The incidence of aseptic loosening, dislocation and broken implants has been particularly investigated.

Debris disease from plastic debris contributes to aseptic loosening. Hard-Hard bearings should obviate this problem. Metal-metal will release ions which might be deleterious. Experience with metal-metal resurfacing has high lighted problems including pseudo-tumours. Ceramic bearings may fracture but otherwise appear free of complications.

Shoulder pain or loss of normal range of motion is a frequent complaint in the outpatient clinic. Of these presentations, rotator cuff injury is a common cause. This can range from mild, transient inflammation of the tendons, to partial tears of tendons, or even full thickness tears. Disruption of the tendons can occur from forceful forward throwing actions undertaken in some sports, for example baseball pitching, more commonly in the UK however, chronic impingement can lead eventually to a tendon tear-usually seen in an older population. Current methods of investigation of such injuries after clinical history and examination, includes plain film radiography, ultrasonography, magnetic resonance imaging and arthrography. We decided to look at how ultrasound can be used in the district general hospital for investigation of such injuries.

Introduction

One of the common frustrations for staff in hospital clinics is the frequent disruption caused by failure of patients to turn up for their booked appointments. DNA high rates have an enormous impact on the healthcare system in terms of cost and waiting time, significantly adding to delays along the patient pathway. We need to know the most common causes for non attendance and hence modify or put new protocol to deal with this problem.

Cemented Total Hip Arthroplasty gives good results for 10 or more years, but is too often complicated by a combination of mechanical loosening, wear debris and osteolysis.

Patients require an implant which will last the rest of their life. Cemented hips may not survive and a better alternative is needed.

Furlong hydroxyapatite ceramic coated (HAC) implants have been used for more than 19 years and to date there are 2248 primary hip arthroplasties.

Fixation of the implants with HA ceramic is entirely satisfactory; histological studies from post-mortem specimens have confirmed that there is good cancellous bone fixation to the HA. The hydroxyapatite behaves like bone and is replaced by creeping substitution. This results in a Perfect Fit with no intervening fibrous tissue. Fixation is therefore maintained.

Aseptic loosening is rare; eleven components. Polythene wear is a problem. Those patients with ceramic/polythene couples who have now reached about 15 years since surgery are showing wear of the liner evidenced by eccentricity of the ceramic head in the liner. Three of these have completely destroyed the liner and the titanium shell.

Ceramic/ceramic bearings do not seem to wear, although there have been occasional fractures of alumina. For the last two years Biolox Delta, a stronger compound ceramic material, has been available from Ceramtec. There are no reports of any fractures.

Patients who have a life expectancy of more than 10 or 15 years should be fitted with an HA coated implant with ceramic bearing surfaces. This may provide the answer for the long-lasting hip prosthesis.

Aims Osteolysis from polythene debris contributes to loosening of total hip components. Will ceramic/ceramic bearings in conjunction with Hydroxyapatite Ceramic Coated Hips (HAC) survive any better?

Material. Hydroxyapatite Ceramic Coated Hips were first used in Sunderland, U.K. in May 1988. More than 2400 HAC hips have been inserted.

There are 521 hips in 441 patients with ceramic/ceramic bearings. I am reporting this consecutive series.

These hips are generally inserted into patients with a 20+ year life expectancy. This ranges from 18 to 74. Mean age is 52.4 years. These young patients are mostly active and many are working.

Amongst the indications were osteoarthritis 297, hip dysplasia 76, and ankylosing spondylitis 18. Thirty eight had had previous childhood hip disorders, and 19 had rheumatoid arthritis. The series also includes 43 with AVN and 7 revisions from cemented hip replacement

All the patients are assessed using the Harris Hip Score before and after surgery. They are assessed annually. Post operative scores show 22 patients with Harris Hip Scores of less than 80, but only 9 patients have problems attributable to HAC hip surgery. These include 2 patients with infection, 3 fractured ceramic acetabular liners, two broken heads and 2 patients with loose cups, one from aseptic loosening. Apart from this one case, aseptic loosening has not been a problem.

Discussion. The results have been rewarding. There are 2400+ HAC hips in the whole series. This sub group of 521 ceramic/ceramic HAC hips is small with a maximum follow up of 14 years. However, there have been few failures which could be attributed to the HA coated device. The broken ceramic components are a concern. It is probable that third body inclusions between the modular components led to stress concentrations. It is also possible that acetabular impingement was a problem and the hips may have been subluxing a few microns with every step and not just gliding with every step. This might overload the alumina implants leading to their failure. All the earlier prostheses are alumina/alumina but 55 hips inserted since august, 2005 have an alumina/zirconia compound head (Biolox Delta®). There have been no cases of periprosthetic osteolysis.

Conclusions. Hydroxy Apatite bony bonding secures the implants. No cement or polyethylene is used which can contribute to osteolysis.

Wear in ceramic bearings will be negligible. Third body inclusions must be avoided to prevent wear or fracture.

The femoral spigot must not impinge on the acetabular margin causing subluxation which may lead to fracture.

The ceramic material has to be supported to prevent fracture.

The outcome of the patients in this sub-group has been rewarding. Alumina/alumina hip arthroplasty should be considered where life expectancy is substantial.

Aims: To ascertain whether or not Hydroxyapatite Ceramic coated implants (HAC) will survive more than ten years after implantation. Method: Since May 1988 HAC hip prostheses have been used in more than 1900 operations. The patients are assessed using the Harris Hip Score (HHS) pre- and postoperatively and then annually. Post mortem specimens are sectioned to study bone integration to the HAC. Initial X-rays are reviewed and followed by annual X-ray after þve years. Results: HHS indicates that the system works with only 7% scoring less than 90. Only seven hips had a deterioration in HHS associated with the implant including three with aseptic loosening. One had catastrophic third body wear in a plastic acetabular liner. Histology shows early bony bonding (six weeks) to HAC particularly in cancellous bone. The HAC coating behaves biologically and is ultimately replaced with bone with no intervening þbrous layer: a Perfect Fit (seen at variable times after six years)Conclusions: HAC hip prostheses provide a ten year, pain free arthroplasty. There is one case of polyethylene debris/granuloma disease. Maximum follow-up is þfteen years. Longer term results will be awaited with interest.