Supplement I . Vol. 8, Aust.
N.Z. J . Med. (1978), pp. 155-159
Surgery in Rheumatoid Arthritis A.
B.
SYNOVECTOMY
J O I N T REPLACEMENT
K i n g s l e y Mills
Harry T y e r
From The Royal Melbourne Hospital, Victoria
From Royal Prince Alfred Hospital. Sydney, NSW
A.
of a Baker’s cyst with leakage of synovial fluid into the calf is an indication for synovectomy, since removal of the cyst alone almost inevitably leads to a recurrence.
Synovectomy-Kingsley
Mills
S Y N O I’ECTOMY--KINGSLEI‘ M I L L S The aim of synovectomy is to remove as much of the diseased synovium as possible. Synovial regeneration in animals commences within six weeks post-operatively and is complete within 1 10 days’; although the regenerated synovium may exhibit chronic, non-specific inflammation, it is hoped that it will not have the pathogenic potential of the original joint lining. Most follow-up studies of synovectomy show that there is a direct correlation between the changes found at surgery and the end result, so that a joint free of articular cartilage damage at the time of synovectomy can be expected to give the best clinical result. Conversely, articular cartilage damage, if present at the time of synovectomy, usually signifies a poor prognosis. Synovectomy is almost always done too late, since there are nearly always irreversible changes in tissues other than the synovial membrane. If the clinician aims for prophylactic synovectomy, it is better to risk doing some cases too early rather than too late. The indication for prophylactic synovectomy is the failure of medical management to control the disease in a joint, in the absence of demonstrable damage to other joint tissues, i.e. there is no radiological evidence of bone erosions or loss of articular cartilage. Late (non-prophylactic) synovectomy may be done to control symptoms in a joint which has a mass of painful, diseased synovium; good results may be obtained from simply removing the bulk of this diseased tissue. The Knee Early or occasionally late synovectomy may be done on the knee joint. Recurrent rupture Correspondence. Dr. H . Tyer. Royal Prince Alfred Hospital, Camperdown. Sydney, NSW 2050
Tlie Elbow Pain, swelling, limitation of movement and crepitus over the radial head may be an indication for late synovectomy. The radial head is commonly excised during the procedure, and frequently results in a pain-free and stable joint. Shouldt>rsand Feet Synovectomy in the foot and shoulder joints has little to offer. Tendon Sheaths Tendon sheath involvement is common; this may result in attenuation and sometimes spontaneous rupture of tendons. Excellent symptomatic relief may be obtained from the excision of large masses of synovium from the tendon sheaths; this may also prevent attrition rupture of the tendons. The b’rist Synovectomy of the inferior radioulnar joint, together with excision of the head of the ulna, is often a worthwhile procedure in relieving pain and preventing rupture of the extensor tendons to the ring and little fingers. SmuN Joints of’ the Hand
Synovectomy in these joints is now performed much less frequently than before. It rarely protects them from loss of articular cartilage and bony erosion and recurrence of the synovitis is frequent. Except in well-selected early cases, synovectomy in these joints is not satisfactory. Conclusion Synovectomy may, in the treatment of selected joints, give excellent results in alleviating pain and disability in the rheumatoid patient.
156
MILLS A N D TYLER
Prophylactic synovectomy has to be done at a very early stage of the disease and this is rarely practical. B. Joint Replacement-Harry
Tyer
JOINT REPLACEMENT-HARR Y T Y E R Introduction In making a decision to proceed with the replacement of any joint, the clinician should take into account whether the planned procedure is likely to remain satisfactory throughout the expected lifetime of the patient and, if not, whether it can be readily revised or salvaged. This must be balanced against the availability of alternative procedures. If a decision is made to proceed with joint replacement, the surgical and rehabilitative facilities of the unit must be adequate to cope with the procedure. Hip Of the many joint replacements currently available, hip replacement is the most successful and best documented. Nevertheless, it is important to remember that failures from infection and prosthetic loosening do occur, and revision can be a most difficult and sometimes unrewarding exercise. Many would feel that the patient who has had the misfortune to develop such complications is best treated by the simple removal of the prosthesis and fixation cement, being left with the equivalent of a Girdlestone operation. However, the literature contains a number of references to a relatively successful outcome following local irrigation of the operative site until cultures are negative, followed by further replacement covered by antibiotics administered both systemically and incorporated in the cement. Where the prosthesis has become loose, it would be necessary to use a long femoral stem or an outsized acetabular component to allow contact of the cement with fresh cancellous bone. Before attempting such a revision, it is reasonable that the patient be aware that there is a definite possibility that the joint may have to be removed at some future operation if infection is not controlled. Problems may arise which make a decision for hip replacement controversial. One example
SUPPLEMENT
1.
VOL.
8
is the patient with disabling symptoms at an age which makes it unlikely that the artificial joint would last a lifetime. A number of “holding” procedures are available, but these may complicate ultimate joint replacement. At present there is interest in designing prostheses giving many of the benefits of joint replacement, without adding to the problems of conversion to a standard type of hip replacement at a later date. One of the more interesting of this group is the Freeman prosthesis, which utilises the usual polythene cup, but where the femoral component simply recaps the reshaped head of the patient’s femur, leaving a virgin field in the shaft of the femur for a subsequent standard prosthesis. Another problem area in hip replacement has been the patient with protrusio acetabulae. All too commonly, despite variations in the siting of the cup, protrusio of the prosthesis has tended to occur. There are now a variety of acetabular rings to be used in conjunction with routine prostheses which tend to exert much of the force against the acetabular rim, rather than the weakened medial wall. Knee Joint With joints other than the hip, there is less certainty and knowledge about joint replacement. It is already clear that there is no single knee joint available which can be used effectively in all pathological situations seen by the clinician. There is no better proof of this uncertainty than the bewildering array of prostheses available. The early all-metal hinge joints with a single axis are now rarely used. They usually require the removal of so much bone as to make salvage difficult if failure occurs. The single axis of movement in a polyaxial joint inevitably means that the prosthesis will be subjected to pressure which it is unlikely to sustain over a long period of time. By the time most patients with arthritis of the knee come to arthroplasty, there has usually been moderate destruction of the joint surface. Most commonly a prosthesis is used which will retain the patient’s own ligaments, but which will replace both the medial and lateral compartments of the knee, while at the same time
JUNE
1978
SURGERY IN RHEUMATOID ARTHRITIS
leaving sufficient bone stock to allow for salvage, either by arthrodesis or conversion to some other prosthesis. The “Geomedic’,’ prosthesis is probably the one most commonly used in this country, but a number of other prostheses are available. In patients where the local destruction is less marked, or involves only one compartment, the “Geomedic” type of prosthesis may be too radical. One then has the choice of some of the modular prostheses which can be used in a single compartment as an alternative t o osteotomy and which require the removal of much less bone. However, it is important to point out that these, in common with other knee joint replacements, are lacking in long term follow-up, while at least the outlook for osteotomy is reasonably clear. There remain some knee joints which are so unstable, either from pathology or the failure of an existing replacement, that a more inherently stable prosthesis is required. To fill this gap a number of semi-constrained hinge-like joints with low friction bearing surfaces have been designed. They are sufficiently stable to dispense with ligamentous support, but disperse many of the damaging pressure effects which occur on the single axis hinge. Examples of this are the “Sheehan” and “Sphero-centric” prostheses. In those cases where retro-patella problems constitute a major part of the patient’s symptoms, it is now possible to incorporate the patello-femoral replacement with that of the knee joint itself, as in the total condylar and “Geopatellar” prostheses. It will be clear that the foregoing discussion that we at present have a spectrum of knee prostheses which must be fitted in to suit the stage of the disease in each patient and only more detailed follow-up over the next ten years will clarify the problems involved. Small Joints of the Hand Outside of the hip and knee, the area that has been most successfully managed by joint replacement has been the metacarpophalangeal joint in the hand. Here, Silastic replacement, if supported by appropriate extensor tendon repositioning, and if necessary crossed intrinsic transfers, has given excellent results. It is a field
157
requiring close personal supervision and a welltrained physiotherapy staff. The interphalangeal joints remain a problem because of the lateral instability of the Silastic prostheses. A number of semi-constrained hinges are now available and may provide the answer, but the prospect of revising failed prostheses needing methacrylate fixation in small bones of this type is a daunting one. 0ther Joints Outside of these three major areas, many joint replacements are available, but experience is insufficient to give the patient any firm reassurance about results. ( a ) Ankle and elbow: the two groups of patients most commonly requiring consideration for replacement of these joints are those with rheumatoid arthritis and those in whom trauma has occurred at a relatively young age. In the latter group it is impossible to insert a prosthesis and guarantee that it will last for a long period of time under heavy use. In the case of the ankle, an arthrodesis is at least an acceptable alternative. In rheumatoid elbows, synovectomy and excision of the head of the radius will provide a reasonable result for many patients. Osteoporosis of the talus may well preclude many rheumatoid patients from ankle replacement. From the foregoing remarks, it will be clear that the number of patients suited for replacement of these joints will be small. Nevertheless, there are patients with arthritis of the ankle who will obtain relief from the currently available semi-restrained ankle prostheses. Unfortunately it is an area prone to oedema, varicose vein problems and delayed skin healing. There are a number of low-friction hinge joints available for the elbow. The early problems of skin erosion from local pressure have been diminished by better counter-sinking of the components, but the basic difficulty of inserting a single axis hinge to a polyaxial joint remains, with the risk of loosening. It must be pointed out that such prostheses were not designed for the purpose of carrying heavy weights, or for patients with associated severe disease of the lower limbs who must use crutches.
158
MILLS AND TYLER
( b )Wrist: a suitable alternative procedure such as synovectomy with re-shaping of the ulnar head or arthrodesis is available. However, there is an occasional patient suitable for the current types of wrist replacement. (c) Shoulder: although a number of patients have shoulder joint involvement, most have rotator cuff damage which limits the benefit of joint replacement. Glenoidectomy has been suggested as an alternative procedure, but while it relieves pain, it rarely allows any effective range of shoulder movement. Some of the newer semi-constrained shoulder prostheses may provide sufficient stability to allow the deltoid muscle to act throughout the effective range of movement, regardless of the state of the rotator cuff, thereby producing an effective range of movement. Conclusion
It is promising and exciting to see the develop-
SLJPPLEMENT
1.
VOL.
8
ment of prostheses for many of the peripheral joints and undoubtedly some of these will be of great benefit to individual patients in the future. However, it is important that we retain our sense of perspective as to whether joint replacement is the ideal treatment available, what the likely results would be and whether there is any potential salvage in the case of failure. The results to date and the expectations for the future are promising but much thought is required and case documentation is obligatory.
References I MITCHEI I , N and 81ACKWFI L, P. (1968): The electron microscopy 01 regenerating ~ q n o v i u mafter subtotal synovectomq in rahhits. J . Bone J I Surfi. WA, 675 ?2 AKTIIKITISF(11'4DATIOY COMMITTtF 11h EVALUAI1I)N C R S Y h U \ ' t ( ' f l l M > (1977). Multiccntre evaluation of synovectomy in the treatment of rheumatoid arthritic. Arihr. und Rheum. 20, 765. 3. ARTHRITIS A N D RHtl'MATISM CfIUNC IL A h D BKlTlSH ORTFlOPAtlllr ASSOCIATION (1976): Controlled trial of synovectomy 01 knee and metacarpophalangeal joints In rheumatoid arthritis. Ann rheum. D m 35, 437.
D iscuss io n Webb (Melb): I think there are two points which could be made about joint replacement. Firstly, with respect to the ankle in rheumatoid arthritis, the problems are almost invariably in the sub-talar and mid-tarsal joints, and it is quite uncommon for severe disease to occur in the talo-tibia1 joint. It would seem to me, therefore, that the application of ankle joint replacement in rheumatoid arthritis will always be very limited. Secondly, with respect to metacarpophalangeal joint replacements, these usually give a hand which looks better than it did preoperatively, but very frequently function is not improved and, indeed, may be worsened. Thus the overall result for the patient can well be undesirable. Brown: Recent papers have reported rather disappointing results from multicentre trials of synovectomy in the U.S.' and U . K 3 Exacerbations of disease occurred in the synovectomised joints as frequently as in control joints, and the functional disability after three years was not much different that in controls.
Mills: In nearly all the studies I have seen, there has been no adequate definition of the extent of the disease at the time of surgery. Until this is standardised, it is very difficult to interpret the results of studies. Vernon-Roberts: You put forward the thesis that, if you did the synovectomy early enough, you would get a better result. What evidence do you base this on?
Mills: This is the general thesis and conclusion of a number of trials. Most studies assess various parameters of synovial disease before synovectomy, but only pain is assessed after synovectomy. Our experience has been that quite a few patients who have had early synovectomies still have excellent results ten years after surgery. Vernon-Roberts: It is difficult to predict how the synovectomised joint would have behaved anyway.
JUNE
1978
SURGERY IN RHEUMATOID ARTHRITIS
Mills: I agree. This is the main difficulty in assessing results of treatment in this dis,ease. It is interesting to see how the disease progresses in other joints in some patients, while the knee synovectomy remains excellent. Although some of these knees do not have severe synovitis, they do lose articular cartilage and develop deformities. However, deterioration seems to lag behind the general trend of the disease.
159
late, rheumatoid disease are better because there will be some patients with mild disease who will tend to go into natural remission. Hence, like all other treatment, synovectomy done in the early case is likely to be more successful than if done late. I think we all accept that synovectomy of the knee is not prophylactic, but it does relieve pain. We should probably continue with this operation, because even if synovectomy is done late, it may give some patients relief from pain before an arthroplasty is indicated.
Henderson: Results of treatment in early, compared with
Suuvlement 1. Vol. 8. Aust. N.Z. J. Med. (1978). VD. 159-162
Prosthetic Implant Reactions B. Vernon-Roberts From the Institute of Medical and Veterinary Science, Adelaide
All prostheses having bearing surfaces release wear products into the joint cavity surrounding the articulating components. Metal-on-metal prostheses frequently release abundant metal, metal-on-bone prostheses release lesser amounts of metal, and metal-on-plastic prostheses usually release very small amounts of metal (Table I).' High density polyethylene bearing surfaces normally release only very small amounts of plastic, but occasionally abundant wear particles of plastic are formed. Metal is released from prostheses by corrosion, and there is almost certainly rapid corrosion of metallic wear particles. Thus, under normal circumstances, there are variable amounts of metal and/or plastic wear particles and metal salts within the joint cavity surrounding a prosthesis.' Crystalline structures containing metal or composed of plastic wear particles appear within macrophages and giant cells of the articular tissues. The larger the amount of either of these crystalline materials that is formed, the greater is the extent of macrophage and giant cell proliferCorrespondence; Professor B. Vernon-Roberts, Department of Pathology, University of Adelaide, Head of Division of Tissue Pathology, Institute of Medical and Veterinary Science, Adelaide, South Australia
ation. While the plastic wear particles are ingested by the phagocytic cells and remain in unchanged form, metal-containing crystals appear to be formed within the phagocytic cells from the metal salts arising from corrosion of bearing surfaces and metallic wear particles (i.e. they are not themselves the wear particles in unchanged form). When crystalline particles of metal or plastic are present in large amounts, there is frequently evidence of cell and tissue death. Tissue death is particularly marked when abundant metal is present in the tissues. If intracellular particles containing metal (and, to a lesser degree, plastic wear particles) have a toxic effect on macrophages, particularly when present in large numbers, this could account for the death ofcells and tissues around some prostheses. In the majority of cases in which loosening is present, macrophages and giant cells containing abundant foreign material have extended into the bone forming the implant bed. Although the possibility must be considered that this cellular extension follows loosening, the appearances suggest that the proliferating cells may first enter the marrow spaces of the cancellous bone nearest to the articulation without initial loss of the bone, and that active removal of both living and
N.Z. J . Med. (1978), pp. 155-159
Surgery in Rheumatoid Arthritis A.
B.
SYNOVECTOMY
J O I N T REPLACEMENT
K i n g s l e y Mills
Harry T y e r
From The Royal Melbourne Hospital, Victoria
From Royal Prince Alfred Hospital. Sydney, NSW
A.
of a Baker’s cyst with leakage of synovial fluid into the calf is an indication for synovectomy, since removal of the cyst alone almost inevitably leads to a recurrence.
Synovectomy-Kingsley
Mills
S Y N O I’ECTOMY--KINGSLEI‘ M I L L S The aim of synovectomy is to remove as much of the diseased synovium as possible. Synovial regeneration in animals commences within six weeks post-operatively and is complete within 1 10 days’; although the regenerated synovium may exhibit chronic, non-specific inflammation, it is hoped that it will not have the pathogenic potential of the original joint lining. Most follow-up studies of synovectomy show that there is a direct correlation between the changes found at surgery and the end result, so that a joint free of articular cartilage damage at the time of synovectomy can be expected to give the best clinical result. Conversely, articular cartilage damage, if present at the time of synovectomy, usually signifies a poor prognosis. Synovectomy is almost always done too late, since there are nearly always irreversible changes in tissues other than the synovial membrane. If the clinician aims for prophylactic synovectomy, it is better to risk doing some cases too early rather than too late. The indication for prophylactic synovectomy is the failure of medical management to control the disease in a joint, in the absence of demonstrable damage to other joint tissues, i.e. there is no radiological evidence of bone erosions or loss of articular cartilage. Late (non-prophylactic) synovectomy may be done to control symptoms in a joint which has a mass of painful, diseased synovium; good results may be obtained from simply removing the bulk of this diseased tissue. The Knee Early or occasionally late synovectomy may be done on the knee joint. Recurrent rupture Correspondence. Dr. H . Tyer. Royal Prince Alfred Hospital, Camperdown. Sydney, NSW 2050
Tlie Elbow Pain, swelling, limitation of movement and crepitus over the radial head may be an indication for late synovectomy. The radial head is commonly excised during the procedure, and frequently results in a pain-free and stable joint. Shouldt>rsand Feet Synovectomy in the foot and shoulder joints has little to offer. Tendon Sheaths Tendon sheath involvement is common; this may result in attenuation and sometimes spontaneous rupture of tendons. Excellent symptomatic relief may be obtained from the excision of large masses of synovium from the tendon sheaths; this may also prevent attrition rupture of the tendons. The b’rist Synovectomy of the inferior radioulnar joint, together with excision of the head of the ulna, is often a worthwhile procedure in relieving pain and preventing rupture of the extensor tendons to the ring and little fingers. SmuN Joints of’ the Hand
Synovectomy in these joints is now performed much less frequently than before. It rarely protects them from loss of articular cartilage and bony erosion and recurrence of the synovitis is frequent. Except in well-selected early cases, synovectomy in these joints is not satisfactory. Conclusion Synovectomy may, in the treatment of selected joints, give excellent results in alleviating pain and disability in the rheumatoid patient.
156
MILLS A N D TYLER
Prophylactic synovectomy has to be done at a very early stage of the disease and this is rarely practical. B. Joint Replacement-Harry
Tyer
JOINT REPLACEMENT-HARR Y T Y E R Introduction In making a decision to proceed with the replacement of any joint, the clinician should take into account whether the planned procedure is likely to remain satisfactory throughout the expected lifetime of the patient and, if not, whether it can be readily revised or salvaged. This must be balanced against the availability of alternative procedures. If a decision is made to proceed with joint replacement, the surgical and rehabilitative facilities of the unit must be adequate to cope with the procedure. Hip Of the many joint replacements currently available, hip replacement is the most successful and best documented. Nevertheless, it is important to remember that failures from infection and prosthetic loosening do occur, and revision can be a most difficult and sometimes unrewarding exercise. Many would feel that the patient who has had the misfortune to develop such complications is best treated by the simple removal of the prosthesis and fixation cement, being left with the equivalent of a Girdlestone operation. However, the literature contains a number of references to a relatively successful outcome following local irrigation of the operative site until cultures are negative, followed by further replacement covered by antibiotics administered both systemically and incorporated in the cement. Where the prosthesis has become loose, it would be necessary to use a long femoral stem or an outsized acetabular component to allow contact of the cement with fresh cancellous bone. Before attempting such a revision, it is reasonable that the patient be aware that there is a definite possibility that the joint may have to be removed at some future operation if infection is not controlled. Problems may arise which make a decision for hip replacement controversial. One example
SUPPLEMENT
1.
VOL.
8
is the patient with disabling symptoms at an age which makes it unlikely that the artificial joint would last a lifetime. A number of “holding” procedures are available, but these may complicate ultimate joint replacement. At present there is interest in designing prostheses giving many of the benefits of joint replacement, without adding to the problems of conversion to a standard type of hip replacement at a later date. One of the more interesting of this group is the Freeman prosthesis, which utilises the usual polythene cup, but where the femoral component simply recaps the reshaped head of the patient’s femur, leaving a virgin field in the shaft of the femur for a subsequent standard prosthesis. Another problem area in hip replacement has been the patient with protrusio acetabulae. All too commonly, despite variations in the siting of the cup, protrusio of the prosthesis has tended to occur. There are now a variety of acetabular rings to be used in conjunction with routine prostheses which tend to exert much of the force against the acetabular rim, rather than the weakened medial wall. Knee Joint With joints other than the hip, there is less certainty and knowledge about joint replacement. It is already clear that there is no single knee joint available which can be used effectively in all pathological situations seen by the clinician. There is no better proof of this uncertainty than the bewildering array of prostheses available. The early all-metal hinge joints with a single axis are now rarely used. They usually require the removal of so much bone as to make salvage difficult if failure occurs. The single axis of movement in a polyaxial joint inevitably means that the prosthesis will be subjected to pressure which it is unlikely to sustain over a long period of time. By the time most patients with arthritis of the knee come to arthroplasty, there has usually been moderate destruction of the joint surface. Most commonly a prosthesis is used which will retain the patient’s own ligaments, but which will replace both the medial and lateral compartments of the knee, while at the same time
JUNE
1978
SURGERY IN RHEUMATOID ARTHRITIS
leaving sufficient bone stock to allow for salvage, either by arthrodesis or conversion to some other prosthesis. The “Geomedic’,’ prosthesis is probably the one most commonly used in this country, but a number of other prostheses are available. In patients where the local destruction is less marked, or involves only one compartment, the “Geomedic” type of prosthesis may be too radical. One then has the choice of some of the modular prostheses which can be used in a single compartment as an alternative t o osteotomy and which require the removal of much less bone. However, it is important to point out that these, in common with other knee joint replacements, are lacking in long term follow-up, while at least the outlook for osteotomy is reasonably clear. There remain some knee joints which are so unstable, either from pathology or the failure of an existing replacement, that a more inherently stable prosthesis is required. To fill this gap a number of semi-constrained hinge-like joints with low friction bearing surfaces have been designed. They are sufficiently stable to dispense with ligamentous support, but disperse many of the damaging pressure effects which occur on the single axis hinge. Examples of this are the “Sheehan” and “Sphero-centric” prostheses. In those cases where retro-patella problems constitute a major part of the patient’s symptoms, it is now possible to incorporate the patello-femoral replacement with that of the knee joint itself, as in the total condylar and “Geopatellar” prostheses. It will be clear that the foregoing discussion that we at present have a spectrum of knee prostheses which must be fitted in to suit the stage of the disease in each patient and only more detailed follow-up over the next ten years will clarify the problems involved. Small Joints of the Hand Outside of the hip and knee, the area that has been most successfully managed by joint replacement has been the metacarpophalangeal joint in the hand. Here, Silastic replacement, if supported by appropriate extensor tendon repositioning, and if necessary crossed intrinsic transfers, has given excellent results. It is a field
157
requiring close personal supervision and a welltrained physiotherapy staff. The interphalangeal joints remain a problem because of the lateral instability of the Silastic prostheses. A number of semi-constrained hinges are now available and may provide the answer, but the prospect of revising failed prostheses needing methacrylate fixation in small bones of this type is a daunting one. 0ther Joints Outside of these three major areas, many joint replacements are available, but experience is insufficient to give the patient any firm reassurance about results. ( a ) Ankle and elbow: the two groups of patients most commonly requiring consideration for replacement of these joints are those with rheumatoid arthritis and those in whom trauma has occurred at a relatively young age. In the latter group it is impossible to insert a prosthesis and guarantee that it will last for a long period of time under heavy use. In the case of the ankle, an arthrodesis is at least an acceptable alternative. In rheumatoid elbows, synovectomy and excision of the head of the radius will provide a reasonable result for many patients. Osteoporosis of the talus may well preclude many rheumatoid patients from ankle replacement. From the foregoing remarks, it will be clear that the number of patients suited for replacement of these joints will be small. Nevertheless, there are patients with arthritis of the ankle who will obtain relief from the currently available semi-restrained ankle prostheses. Unfortunately it is an area prone to oedema, varicose vein problems and delayed skin healing. There are a number of low-friction hinge joints available for the elbow. The early problems of skin erosion from local pressure have been diminished by better counter-sinking of the components, but the basic difficulty of inserting a single axis hinge to a polyaxial joint remains, with the risk of loosening. It must be pointed out that such prostheses were not designed for the purpose of carrying heavy weights, or for patients with associated severe disease of the lower limbs who must use crutches.
158
MILLS AND TYLER
( b )Wrist: a suitable alternative procedure such as synovectomy with re-shaping of the ulnar head or arthrodesis is available. However, there is an occasional patient suitable for the current types of wrist replacement. (c) Shoulder: although a number of patients have shoulder joint involvement, most have rotator cuff damage which limits the benefit of joint replacement. Glenoidectomy has been suggested as an alternative procedure, but while it relieves pain, it rarely allows any effective range of shoulder movement. Some of the newer semi-constrained shoulder prostheses may provide sufficient stability to allow the deltoid muscle to act throughout the effective range of movement, regardless of the state of the rotator cuff, thereby producing an effective range of movement. Conclusion
It is promising and exciting to see the develop-
SLJPPLEMENT
1.
VOL.
8
ment of prostheses for many of the peripheral joints and undoubtedly some of these will be of great benefit to individual patients in the future. However, it is important that we retain our sense of perspective as to whether joint replacement is the ideal treatment available, what the likely results would be and whether there is any potential salvage in the case of failure. The results to date and the expectations for the future are promising but much thought is required and case documentation is obligatory.
References I MITCHEI I , N and 81ACKWFI L, P. (1968): The electron microscopy 01 regenerating ~ q n o v i u mafter subtotal synovectomq in rahhits. J . Bone J I Surfi. WA, 675 ?2 AKTIIKITISF(11'4DATIOY COMMITTtF 11h EVALUAI1I)N C R S Y h U \ ' t ( ' f l l M > (1977). Multiccntre evaluation of synovectomy in the treatment of rheumatoid arthritic. Arihr. und Rheum. 20, 765. 3. ARTHRITIS A N D RHtl'MATISM CfIUNC IL A h D BKlTlSH ORTFlOPAtlllr ASSOCIATION (1976): Controlled trial of synovectomy 01 knee and metacarpophalangeal joints In rheumatoid arthritis. Ann rheum. D m 35, 437.
D iscuss io n Webb (Melb): I think there are two points which could be made about joint replacement. Firstly, with respect to the ankle in rheumatoid arthritis, the problems are almost invariably in the sub-talar and mid-tarsal joints, and it is quite uncommon for severe disease to occur in the talo-tibia1 joint. It would seem to me, therefore, that the application of ankle joint replacement in rheumatoid arthritis will always be very limited. Secondly, with respect to metacarpophalangeal joint replacements, these usually give a hand which looks better than it did preoperatively, but very frequently function is not improved and, indeed, may be worsened. Thus the overall result for the patient can well be undesirable. Brown: Recent papers have reported rather disappointing results from multicentre trials of synovectomy in the U.S.' and U . K 3 Exacerbations of disease occurred in the synovectomised joints as frequently as in control joints, and the functional disability after three years was not much different that in controls.
Mills: In nearly all the studies I have seen, there has been no adequate definition of the extent of the disease at the time of surgery. Until this is standardised, it is very difficult to interpret the results of studies. Vernon-Roberts: You put forward the thesis that, if you did the synovectomy early enough, you would get a better result. What evidence do you base this on?
Mills: This is the general thesis and conclusion of a number of trials. Most studies assess various parameters of synovial disease before synovectomy, but only pain is assessed after synovectomy. Our experience has been that quite a few patients who have had early synovectomies still have excellent results ten years after surgery. Vernon-Roberts: It is difficult to predict how the synovectomised joint would have behaved anyway.
JUNE
1978
SURGERY IN RHEUMATOID ARTHRITIS
Mills: I agree. This is the main difficulty in assessing results of treatment in this dis,ease. It is interesting to see how the disease progresses in other joints in some patients, while the knee synovectomy remains excellent. Although some of these knees do not have severe synovitis, they do lose articular cartilage and develop deformities. However, deterioration seems to lag behind the general trend of the disease.
159
late, rheumatoid disease are better because there will be some patients with mild disease who will tend to go into natural remission. Hence, like all other treatment, synovectomy done in the early case is likely to be more successful than if done late. I think we all accept that synovectomy of the knee is not prophylactic, but it does relieve pain. We should probably continue with this operation, because even if synovectomy is done late, it may give some patients relief from pain before an arthroplasty is indicated.
Henderson: Results of treatment in early, compared with
Suuvlement 1. Vol. 8. Aust. N.Z. J. Med. (1978). VD. 159-162
Prosthetic Implant Reactions B. Vernon-Roberts From the Institute of Medical and Veterinary Science, Adelaide
All prostheses having bearing surfaces release wear products into the joint cavity surrounding the articulating components. Metal-on-metal prostheses frequently release abundant metal, metal-on-bone prostheses release lesser amounts of metal, and metal-on-plastic prostheses usually release very small amounts of metal (Table I).' High density polyethylene bearing surfaces normally release only very small amounts of plastic, but occasionally abundant wear particles of plastic are formed. Metal is released from prostheses by corrosion, and there is almost certainly rapid corrosion of metallic wear particles. Thus, under normal circumstances, there are variable amounts of metal and/or plastic wear particles and metal salts within the joint cavity surrounding a prosthesis.' Crystalline structures containing metal or composed of plastic wear particles appear within macrophages and giant cells of the articular tissues. The larger the amount of either of these crystalline materials that is formed, the greater is the extent of macrophage and giant cell proliferCorrespondence; Professor B. Vernon-Roberts, Department of Pathology, University of Adelaide, Head of Division of Tissue Pathology, Institute of Medical and Veterinary Science, Adelaide, South Australia
ation. While the plastic wear particles are ingested by the phagocytic cells and remain in unchanged form, metal-containing crystals appear to be formed within the phagocytic cells from the metal salts arising from corrosion of bearing surfaces and metallic wear particles (i.e. they are not themselves the wear particles in unchanged form). When crystalline particles of metal or plastic are present in large amounts, there is frequently evidence of cell and tissue death. Tissue death is particularly marked when abundant metal is present in the tissues. If intracellular particles containing metal (and, to a lesser degree, plastic wear particles) have a toxic effect on macrophages, particularly when present in large numbers, this could account for the death ofcells and tissues around some prostheses. In the majority of cases in which loosening is present, macrophages and giant cells containing abundant foreign material have extended into the bone forming the implant bed. Although the possibility must be considered that this cellular extension follows loosening, the appearances suggest that the proliferating cells may first enter the marrow spaces of the cancellous bone nearest to the articulation without initial loss of the bone, and that active removal of both living and
