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BMJ No 7103 Volume 315

Editorial Saturday 2 August 1997

Young adults with arthritic hips

Should be offered alternatives to total hip replacement

Total hip replacement, about 40,000 of which are performed annually in the United Kingdom, is widely believed to be the only viable surgical treatment for arthritis of the hip. While total hip replacement is extremely effective for late middle aged or elderly patients, such that more than 95% of patients will probably die with their original implant in situ, the operation has limitations in younger people. The replacement has to last much longer, and young patients, unless restricted by some more generalised disease, tend to overload artificial joints with unrestricted activity. The long term results in this age group are therefore poorer, with several series reporting 25-30% of cases needing revision by 15 years (H Malchau, P Herberts, annual meeting of American Academy of Orthopaedic Surgeons, Atlanta 1996).(1)

So, can anything else be done, and if so, when should patients be referred? Fortunately, there are several possibilities (M D Northmore-Ball, S R D'Souza, J Varughese, A M R New, meeting of European Hip Society, Helsinki 1996). Hips that fail early do so through secondary rather than primary osteoarthritis. In secondary arthritis, an insult to the hip at birth or during growth produces a joint of abnormal shape in the adult, which causes unfavourable biomechanics and overload. This overload causes cartilage breakdown and osteoarthritis.(2) The initial insult may or may not be known to the patient. With appropriate surgery the abnormality can often be corrected and the insidious arthritic process arrested and sometimes reversed.

The best example is acetabular dysplasia, a type of congenital dislocation. This is probably much more common than usually believed, one estimate giving it as the cause of over 40% of all osteoarthritis of the hip in adults.(3) The acetabulum is shallow and too vertical; the hip is overloaded and gradually subluxes. The patient, usually female, is otherwise perfectly fit, but one or both hips begin to ache. There is usually no history of hip disorder, and the hip has an excellent range of movement. Though a plain x ray examination shows a shallow maldirected acetabulum, the changes may be very slight. In view of the patient's youth and the near normal clinical picture, little may be thought appropriate. However, timely operative treatment will relieve the symptoms. By studying the dysplasia with special x ray studies and computerised tomography, extension, abduction, and rotational correction angles are estimated. The acetabulum is then disconnected from its bony attachments by a periacetabular osteotomy,(4) moved through these angles, and refixed. This restorative procedure is much more time consuming and complex than total hip replacement, but will greatly slow down or prevent the otherwise inevitable deterioration of the hip which would eventually require replacement. No controlled trials exist, but a recent case series has shown maintenance of symptomatic improvement, with no development of osteoarthritis in about 80% of patients treated by acetabular redirection at an average follow up of 10 years.(5)

Other kinds of joint-saving operations are possible. If, on referral, the dysplasia is felt to be too severe or the hip too subluxed for a periacetabular osteotomy, a Chiari transverse pelvic osteotomy can be made just above the hip,(6) bringing a load bearing iliac buttress into position just above the head, again deferring replacement. Femoral osteotomy may also sometimes be appropriate, even in the presence of marked osteoarthritis,(7) and other osteotomies have a specific place, such as rotational or intertrochanteric osteotomies for avascular necrosis.(8) As in patients with mild dysplasia, those with avascular necrosis may be misleadingly normal on clinical examination, with rather benign x ray appearances. Combined pelvic and femoral osteotomies are also sometimes indicated.

If an osteotomy is not appropriate, arthroscopy,(9) a technique still in its infancy, may have a place, although arthroscopically treatable hip problems are less common than treatable knee problems and the procedure is less straightforward.

If none of the above are possible and the patient is severely disabled, replacement after all may be the only option. However, in some young men in their late teens or twenties, arthrodesis (fusion) may be appropriate.(10) In these days of hip replacements it is not easy to persuade someone to have this done, but pain relief is good and the hip is preserved for replacement when needed, perhaps 20 or even 50 years later. Which is the best type of replacement is still controversial and beyond the scope of this editorial. Resurfacing by prosthetic double cups, which preserves the femoral head, is in theory very attractive. But many such prostheses have failed, and, though some promising new designs are available,(11) the place of resurfacing is not yet established. Further research is needed. Normally, therefore, total replacement is the only option. This is likely to be extremely effective in the short and medium term, but is a "one way street" with irreversible loss of bone stock as well as the strong likelihood of revision while the patient is still young - however carefully the replacement is carried out. In contrast, in the other procedures listed above, notably osteotomy, bone stock is preserved. Although other possibilities - such as cartilage grafting and wear resistant implants fixed, perhaps, with bioactive cement - may become possible in the future, several useful alternatives are available now and should be considered in all young adults with arthritic hips.

M D Northmore-Ball Consultant orthopaedic surgeon

Unit for Joint Reconstruction,
Robert Jones and Agnes Hunt Orthopaedic and District Hospital NHS Trust,
Oswestry,
Shropshire SY10 7AG

References

1 Collis D K. Long-term (twelve to eighteen-year) follow up of cemented hip replacements in patients who were less than fifty years old. J Bone Joint Surg (Br) 1991;73:593-7.

2 Pauwels F. Biomechanics of the normal and diseased hip. Theoretical foundation, technique and results of treatment. New York: Springer, 1976.

3 Aronson J. Osteoarthritis of the young adult hip: etiology and treatment. Instructional Course Lecture, the American Academy of Orthopaedic Surgeons, 1986;35:119-28.

4 Ganz R, Klaue K, Vinh T S, Mast J W. A new peri-acetabular osteotomy for the treatment of hip dysplasia. Techniques and preliminary results. Clin Orthopaed Related Res 1988;132:26-36.

5 De Kleuver M, Kooijman M A, Pavlov P W, Vett R D H. Triple osteotomy of the pelvis for acetabular dysplasia: results at 8-15 years. J Bone Joint Surg1997;79-B:225-9.

6 Graham S, Westin G W, Dawson E, Oppenheim W L. The Chiari osteotomy. A review of 58 cases. Clin Orthopaed Related Res 1986;208:249-58.

7 Bombelli R. Structure and function in normal and abnormal hips. How to rescue jeopardised hips. New York: Springer, 1993.

8 Mont M A, Fairbank A C, Krackow K A, Hungerford D S. Corrective osteotomy for osteonecrosis of the femoral head: the results of a long term follow up study. J Bone Joint Surg 1996; 78-A:1032-8.

9 Villar R N. Hip arthroscopy. London: Butterworth, 1992.

10 Callaghan J J, Brand R A, Pedersen D R. Hip arthrodesis. A long-term follow-up. J Bone Joint Surg (Br) 1985;9:1328-35.

11 McMinn D, Treacy R, Lin K, Pinsent P. Metal on metal surface replacement of the hip. Experience of the McMinn prosthesis. Clin Orthopaed Related Res1996;329:S89-98.

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