Restoration of the femoral head after collapse osteoarthrosisRestoration of the femoral head after...

Ann. rheum. Dis. (1971), 30, 406

Restoration of the femoralhead after collapse in osteoarthrosis

G. 0. STOREY AND J. W. LANDELLSHackney Hospital, London E.9, and Department of Morbid Anatomy, InstituteHospital

It has often been said that osteoarthrosis of the hipis a relatively static condition, the radiologicalappearance remaining unchanged over a number ofyears. It is now recognized, however, that in somecases destructive changes occur (Isdale, 1962;Storey, 1968); some of these may be the result ofavascular necrosis. In a proportion of these patients,'healing' may bring about re-formation of thefemoral head and reappearance of the radiological'joint space'. In the following report this course wasobserved clinically and radiologically during thelast years of the patient's life and correlated with thefindings at the postmortem examination.

Case ReportThe patient was first seen in 1966, when he was 76 yearsold. He gave a history that 8 years previously, in 1958,he had fallen on his right hip. He attended the CasualtyDepartment, where a radiograph (Fig. 1) was thought tobe normal. The pain in the hips disappeared, but returnedin 1964, especially on walking, about 18 months beforehis attendance. He also noticed that his leg had becomeshorter.

ExaminationThe shortening of the right lower limb was confirmed(1 in.; 2 5 cm.) with limitation of the movements of thehip. On December 12, 1966, a radiograph (Fig. 2)showed the presence of cystic and sclerotic changes in thehead of the right femur with some collapse. The patienthad suffered from dysphagia due to benign oesophagealstricture, and the hip changes could be seen to have beenpresent in the radiographs taken for a barium meal in1965.

TreatmentBecause of his age and because pain was not a markedfeature conservative treatment of the osteoarthrosis wasdecided upon. He was given physiotherapy, indomethacin25 mg. twice daily, and paracetamol as necessary. Thecondition of the hip remained stationary with no greatchange in the radiological appearance.

FIG. I Radiograph of right hip, 1958. Normal outline offemoral head.

ProgressThe dysphagia continued to be troublesome, and onSeptember 5, 1969, a further radiological examination inthe course of barium studies showed that the outline ofthe head of the femur had now become more defined,

Accepted for publication January 20, 1971

of Pathology, The London

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Restoration of the femoral head 407

FIG. 2 Radiograph of right hip, 1966. Sclerotic changesin upper part of head and acetabulum, with obliterationof 'joint space' and displacement of the head upwards rela-tive to acetabulum.

TerminationThe patient had become mentally confused, and he diedon September 16, 1969, after 3 weeks in hospital. Deathwas due to cerebral glioma.

Pathological examination

The right hip-joint, together with the adjacent partof the bony pelvis and the upper end of the femur,including the lesser trochanter, was excised un-opened at autopsy (Dr. J. A. U. Morgan). The wholewas divided along a coronal plane in the line of theneck of the femur, fixed, photographed, andexamined by ultra-violet light. Blocks were takenfor histology from the mid-plane, the anteriorsurface of the femoral head, three other areas of thejoint surfaces, and two loose bodies.

Gross appearance (Figs 4-6, overleaf)

The head was of nearly normal contour, a littleflattened on the upper surfac- and a little larger thannormal (5 5 cm. diameter); anteriorly, the cartilagewas rounded, whitish, greyer locally where thinner,with a broad grooved osteophyte on the lowerborder, and several small nodular osteophytes in

though altered in shape, and that a joint-space had the broad sulcus surrounding the articular surface.reappeared (Fig. 3). There was a larger osteochondral nodule below,

FIG. 3 Radiograph of right hip, 1962. The displacement of the head is still visible, but there is now a clear joint-spaceand the outline of the head, though showing sclerotic and cystic changes, is very much clearer.


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408 Annals of the Rheumatic Diseases

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FIG. 4 Anterior view ofhip at autopsy. Outline ofbone not greatly deformed; nodular osteophytes at junction with neckand synovial viili.

FIG. 5 Posterior view ofhip at autopsy. A narrowcurved band rather abovethe middle is the onlyremaining visible relic ofthe original articular car-

tilage. Osteophytic carti-lage below this and fibro-cartilage above it haverestored a remarkablysmooth outline to theposteriorpart of the head.Synovialchondromata andvilli and a defect in theacetabular cartilage arealso present.

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FIG. 6 Mid-section (a) by ordinary light, (b) by ultra-violet autofluorescence. The original outline of the neck andlower articular cartilage of the head can be made out clearly, with osteophytes below and sclerotic bone above.


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which was free of any attachment to bone or capsulebut was held in place by other nodules until thejoint was opened and the osteophyte worked out ofits cavity, the irregularities of its shape correspond-ing to that of neighbouring nodules; its descriptionas a loose body was correct in the sense that it hadno vascular or other attachment, but it was notfreely mobile inside the joint. The surfa e of thehead facing the acetabulum was slightly rougher intexture, and had a local area of exposed bone a littleabove the position of the fovea, but was in generalrounded. The acetabular cartilage, apart from asharply-cut defect down to bone near the lowerborder, was also wholly covered with a sheet of new,slightly rough blue-grey cartilage, much less slipperythan normal but equally smoothly contoured. Asecond 'loose' body was locked in position betweenthe lower edge of the head and a synovial osteo-chondroma; some smaller synovial nodules and villiwere also present.

In the mid-section, the outline of the original headcould be made out in the lower half (Fig. 6a) with asmooth osteophyte overlying the lower part of thebone and indicating a shift upwards of the headrelative to the acetabulum of about 1 cm. The edgeof the original cartilage survived as a narrow crescenton the posterior surface; below the entire surfacewas osteophytic; above, there was fibro-cartilage ofrepair covering the entire upper part of the head andthe whole of the acetabulum. In the lower part thedoubled cartilage (new inside the old) could beclearly seen.

These changes were verified by examination underultra-violet light, which provides a clear distinctionbetween hyaline articular cartilage (greyish-whiteautofluorescenoe) and fibrocartilage which, whetherit is formed in repair of defects in the originalsurface or as a surface of an osteophyte, has a strongblue autofluorescence. The calcified zone betweennormal cartilage and bone stands out as a brightchalky white, and bone trabeculae are much moredistinctly shown than by ordinary light. Unfortun-ately these colours do not reproduce satisfactorily inblack and white for publication, but something ofthe changes can be made out in Fig. 6(b).

HISTOLOGICAL EXAMINATION (Fig. 7)This confirmed that none of the surface cartilage hadthe structure of normal hyaline or even of fibrillatedosteoarthrotic cartilage, and that the normal articu-lar lamella was niissing. None of the bone of thehead was now necrotic-indeed much of it hadundergone the usual reinforcement of an osteo-arthrotic head. There was a core of dead bone,consistent with origin in the head, in one only of theloose bodies. The synovium showed the usual

FIG. 7 Photomicrograph ofnew surface cartilage ofjoint:The matrix is fibrillar and not hyaline, the cells often lyingsingly instead of in the groups of normal articular hyalinecartilage. The underlying bony sheet shows the variableactivity of a recently formed piece of bone, and not thestable inactive sheet and supporting struts of a normalarticular lamella. Haematoxylin and eosin, x 30.

villous proliferation and debris of osteoarthrosis,but was without rheumatoid features.

Evidence that a large part of the head of thefemur was in fact destroyed:(1) The x-ray photographs (Figs 1 to 3 during life, andFig. 8 of the central slice of the excised bone) show thatthe internal architecture of the trabeculae is distorted;there is no articular bony plate, and the epiphyseal lineis not traceable.(2) The present configuration of the head is explicableonly by the disappearance of the upper part of the bone,allowing the original line of the lower border to move upand an osteophyte about 1 cm. thick to form below it.This osteophytic restoration of the lower part of thebearing surface is commonly seen in osteoarthrotic hips,but is usually associated with gross defects in the uppersurface.


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FIG. 8 Radiograph of anterior part of head, showing lossof normal architecture and cystic changes.

(3) The histological structure of the new upper part of thebone is not that of normal or of osteoarthrotic articularcartilage, but resembles that seen in repair by theorthopaedic technique of arthroplasty. While part of thesuccess of the repair in this patient may be explained bythe relative lack of vigorous use of the joint in an ill,elderly man, the result in this hip is sufficiently uncommonin osteoarthrosis to suggest that there were other factorsin stabilization, in particular the large strong anteriorosteophyte which may have helped to prevent partialdislocation and fracture of the damaged bone in the weakearly stages of repair.

It is noteworthy that, although fibro-cartilage hadreformed in this patient, no improvement in hissymptoms could be detected; in other cases too inwhich there has been a reappearance of joint spaceradiologically, this has not been associated withlessening of pain.

Discussion

Although it was possible to follow the clinicalcourse in this patient, it remains uncertain whetherthe initial event was avascular necrosis precipitatedby trauma or not; but the subsequent events werethose of uncomplicated osteoarthrosis and there wasno evidence of avascular necrosis at autopsy.The occurrence of this degree of healing in

osteoarthrosis as a result of unaided natural forcesis very unusual. Harrison, Schajowicz, and Trueta(1953) said that it did occur, and believed that as aresult of the destructive process fibrous marrowmight reach the surface of the bone and theredifferentiate into fibrocartilage. Tufts of fibro-cartilage arising in this way usually remain discrete,but occasionally become confluent and resurface thebone. Jacobs (1960) illustrated one such outgrowth.Merle d'Aubigny, Postel, Mazabraud, Massias,

and Gueguen (1965) considered that small areas ofavascular necrosis could be replaced by bone, andrepair has been reported after several surgicalprocedures. Restitution of bone pattern with healingof cysts and improvement of bone outline, as well asa radiological increase in joint space, has beenreported after McMurray's osteotomy (Harris andKirwan, 1964). Adam and Spence (1958) reportedthis in 38 out of 55 cases. Robins and Piggot (1960),however, believed that the increase in joint spacewas only occasionally due to the regeneration ofarticular cartilage and that this radiological appear-ance was mainly the result of the altered position ofthe femoral head. The restoration of a surface ofnormal contour and tolerably smooth fibrocartilageis the usual end-result of the operation of cup-arthroplasty.The reasons for the infrequence of this repair in

the natural course of the disease are complex.Formation of even fibrocartilage is a slow process,and requires a steady position of the head in theacetabulum for some months if the new sheet is notto be broken up by a shift of the pressure areas oneither side of the joint. The stability of the joint inthis patient was secured probably in the main by thetwo large osteophytes, and reinforced somewhatparadoxically by the complex interlocked synovialosteocartilaginous 'large bodies', both of whichlimited the range of movement and prevented theweight of the body from compressing the head intothe acetabulum; in the usual late osteoarthrotic head,evidence of frequent shifts of pressure and malign-ment is provided by the common deep groove overthe upper part of the junction between the neck andthe head, and by microfractures in the bearingsurface, even when gross destruction of the surfaceand large cysts in the substance of the head are notpresent. Where, however, stability is provided, theextremely vigorous ossification and formation offibrous tissue and fibrocartilage (though not hyalinecartilage) which is present in every osteoarthroticjoint is fully capable in a year or two of producingand maintaining a bearing surface with sufficientelasticity to serve the patient for many years, thoughwith nothing like the friction-free character of theoriginal hyaline cartilage. Secondly, the vascularityof the healing surface must be preserved at least asfar as the relatively low requirements of fibro-cartilage are satisfied-by the weight being taken offit to some extent; in the unmodified osteoarthroticsurface sprouting capillaries are obliterated orrubbed away by the pressure and movement of theeburnated and irregular parts of the surface. It is notof great moment how the stability is achieved-bytaking the weight on another piece of the femoralneck in McMurray's operation, by taking it onosteophytes as in this patient and in a small numberof others with less complete or effective restoration,


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or by the insertion of a smooth metal cup to equalize Summaryand spread over the pressure on the bearing surface A case is described in which a smoothly-roundedwhile healing occurs; in all cases in which this is done femoral head was reformed in the natural process ofeffectively the femoral head will re-clothe itself. repair, after destruction by osteoarthrosis.

ReferencesADAM, A., AND SPENCE, A. J. (1958) J. Bone Jt Surg., 40B, 219 (Intertrochanteric osteotomy for osteoarthritis of

the hip. A review of 58 operations).HAms, N. H., AND KIRWAN, E. (1964) Ibid., 46B, 477 (Results of osteotomy for early primary osteoarthritis of

the hip).HARRSN, M. H. M., SCHAJOWICZ, F., AND TRUETA, J. (1953) Ibid., 35B, 598 (Osteoarthritis of the hip: a study of

the nature and evolution of the disease).ISDALE, I. C. (1962) Ann. rheum. Dis., 21, 23 (Femoral head destruction in rheumatoid arthritis and

osteoarthritis).JACOBS, J. H. (1960) Ann. phys. Med., 5, 318 (Osteoarthritis of the hip-joint).MERLE D'AUBIGNY, R., POSTEL, M., MAZABRAUD, A., MASSIAS, P., AND GUEGUEN, J. (1965) J. Bone Jt Surg., 47B,

612 (Idiopathic necrosis of the femoral head in adults).ROBiNS, R. H. C., AND PIcGGoT, J. (1960) Ibid., 42B, 481 (McMurray osteotomy, with a note on the 'regeneration'

of articular cartilage).STOREY, G. 0. (1968) Proc. roy. Soc. Med., 61, 961 (Bone necrosis in joint disease).


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