Although arthroscopy of the hip is being carried out increasingly, little is known about the rate of associated complications. We describe a prospective study of 640 consecutive procedures in which a consistent technique was used. The overall complication rate was 1.6%. Complications, none of which was major or long-term, included transient palsy of the sciatic and femoral nerves, perineal injury, bleeding from the portal wounds, trochanteric bursitis and intra-articular breakage of the instrument. We believe that it is possible to undertake this operation safely using the technique described.

A 35-year-old man was seen with pain in the back of the knee. MRI showed a mass in the anterior cruciate ligament. Biopsy indicated mucoid degeneration. Arthroscopic resection of the ligament was carried out, with relief of symptoms.

In impaction grafting of contained bone defects after revision joint arthroplasty the graft behaves as a friable aggregate and its resistance to complex forces depends on grading, normal load and compaction. Bone mills in current use produce a distribution of particle sizes more uniform than is desirable for maximising resistance to shear stresses.

We have performed experiments in vitro using morsellised allograft bone from the femoral head which have shown that its mechanical properties improve with increasing normal load and with increasing shear strains (strain hardening). The mechanical strength also increases with increasing compaction energy, and with the addition of bioglass particles to make good the deficiency in small and very small fragments. Donor femoral heads may be milled while frozen without affecting the profile of the particle size. Osteoporotic femoral heads provide a similar grading of sizes, although fewer particles are obtained from each specimen. Our findings have implications for current practice and for the future development of materials and techniques.

Bone loss around replacement prostheses may be related to the activation of mononuclear phagocytes (MNP) by prosthetic wear particles. We investigated how osteoblast-like cells were regulated by human MNP stimulated by particles of prosthetic material.

Particles of titanium-6-aluminium-4-vanadium (TiAlV) stimulated MNP to release interleukin (IL)-1β, tumour necrosis factor (TNF)α, IL-6 and prostaglandin E₂ (PGE₂). All these mediators are implicated in regulating bone metabolism. Particle-activated MNP inhibited bone cell proliferation and stimulated release of IL-6 and PGE₂. The number of cells expressing alkaline phosphatase, a marker associated with mature osteo-blastic cells, was reduced. Experiments with blocking antibodies showed that TNFα was responsible for the reduction in proliferation and the numbers of cells expressing alkaline phosphatase. By contrast, IL-1β stimulated cell proliferation and differentiation. Both IL-1β and TNFα stimulated IL-6 and PGE₂release from the osteoblast-like cells.

Our results suggest that particle-activated mono-nuclear phagocytes can induce a change in the balance between bone formation and resorption by a number of mechanisms.

We have reviewed a series of 56 consecutive patients treated by the Ilizarov circular fixator for various combinations of nonunion, malunion and infection of fractures. We used segmental excision, distraction osteogenesis and gradual correction of the deformity as appropriate.

Treatment was effective in eliminating 40 out of 46 nonunions and all 22 infections. There were two cases of refracture some months after removal of the frame, both of which healed securely in a second frame. Correction of malunion was good in the coronal plane but there was a tendency to anterior angulation, often occurring in the regenerate bone rather than at the original fracture site, after removal of the frame. This was associated with very slow maturation of regenerate bone in some patients, occurring largely, but not exclusively, in those who smoked heavily.

Patients expressed high levels of satisfaction with the outcome, despite relatively modest improvements in pain and function, presumably because their longstanding and intractable nonunion had been treated. None the less, the degree of satisfaction correlated strongly with the degree of improvement in pain and function.

We emphasise the importance of a multidisciplinary team in the assessment and support of patients undergoing long and demanding treatment. The Ilizarov method is valuable, but research is needed to overcome the problems of delayed maturation of the regenerate and slow or insecure healing of the docking site.

Our aim was to determine whether in vitro studies would detect differences in the cellular response to wear particles of two titanium alloys commonly used in the manufacture of joint replacement prostheses. Particles were of the order of 1 μm in diameter representative of those found adjacent to failed prostheses.

Exposure of human monocytes to titanium 6-aluminium 4- vanadium (TiAlV) at concentrations of 4 x 10⁷ particles/ml produced a mean prostaglandin E₂ release of 2627.6 pM; this was significantly higher than the 317.4 pM induced by titanium 6-aluminium 7-niobium alloy (TiAlNb) particles (p = 0.006). Commercially-pure titanium particles induced a release of 347.8 pM. In addition, TiAlV stimulated significantly more release of the other cell mediators, interleukin-1, tumour necrosis factor and interleukin-6. At lower concentrations of particles there was less mediator release and less obvious differences between materials. None of the materials caused significant toxicity.

The levels of inflammatory mediators released by phagocytic cells in response to wear particles may influence the amount of periprosthetic bone loss. Our findings have shown that in vitro studies can detect differences in cellular response induced by particles of similar titanium alloys in common clinical use, although in vivo studies have shown little difference. While in vitro studies should not be used as the only form of assessment, they must be considered when assessing the relative biocompatibility of different implant materials.

1. The use of the Metals Research Macrotome for cutting 100 μ thick sections of fresh, unfixed specimens of arthritic human femoral heads and normal goat condyles is described.

2. A technique for isolating living cells from these slices by decalcification followed by enzymic digestion is reported.

3. The microscopic appearances of the fresh slices, the decalcified slices and the isolated cells as seen by incident or transmitted fluorescent lighting, by phase-contrast microscopy, by scanning electron microscopy and by histological and cytological techniques are illustrated.

4. These techniques might be applicable to the examination of biopsy specimens of pathological bone or to basic research on bone cells.

1. Methods for culturing cells isolated from slices of arthritic human or normal mammalian cancellous bone are described.

2. The capacity of the cultured cells to take up and hydroxylate labelled proline has been investigated.

3. Sections of the partially decalcified bone and of the isolated cells have been examined by transmission electron microscopy.

4. The possible significance of the results and observations are discussed. We are deeply grateful to Dame Janet Vaughan, who very kindly read this manuscript and made several valuable suggestions and criticisms. We are much obliged to Dr Sylvia Fitton-Jackson for her advice on the techniques of tissue culture and for giving us the composition of her chemically defined medium. Dr Palfrey kindly allowed one of us, M. J. Dickens, to learn transmission electron microscopy in his department at St Thomas's Hospital Medical School under the expert tuition of Mr G. Maxwell. Mr R. Hockhan and Mr M. Hepburn of the University of Surrey Structural Studies Unit helpfully instructed in the operation of the transmission electron microscope. Our special thanks are due to Mr E. P. Morris for his competent and enthusiastic technical assistance.

1. In seventeen cases of tuberculosis of the hip in children with severe destruction of the joint arthroplasty was done using full thickness skin from the abdominal wall as the interposing material.

2. The results, after a follow-up on the average of three years, show that one-third of the cases are very satisfactory, one-third are fair and one-third show no movement.

1. Convulsions causing fractures complicated the post-operative course of two patients after parathyroidectomy.

2. One patient with primary hyperparathyroidism and osteitis fibrosa developed tetany which was controlled with difficulty with the usual measures to correct hypocalcaemia. The convulsion occurred during hypomagnesaemia. This seemed the main immediate cause of symptoms and was easily corrected when recognised.

3. The second patient had been subjected to total parathyroidectomy for treatment of renal glomerular osteodystrophy. The complications were entirely due to hypocalcaemia and the usual treatment was inadequate until oral aluminium hydroxide was given.

4. Further experience shows that aluminium hydroxide can be a valuable addition to other measures for dealing with hypocalcaemia due to the "hungry bones" phenomena.

1. Contracture of parts of the quadriceps muscle is not uncommon and is often accompanied by tightness of the ilio-tibial tract. It is suggested that this may follow intramuscular injections.

2. Recurrent dislocation of the patella can be a consequence of this muscle contracture.

3. Division of the ilio-tibial tract and lengthening of the fibrotic elements of the quadriceps can prevent further dislocation and restore good function.

1. Frostbite in a child may be severe enough to destroy the cartilage cells of the epiphysial plate of a digit, and produce clinical deformity.

2. Both the direct effect of the freezing itself and the vascular changes secondary to such frostbite appear to cause necrosis of the growing epiphysis with destruction of the epiphysis and disappearance of the epiphysial line or plate. The disappearance of the epiphysial plate is obvious, but whether the epiphysis itself is actually destroyed and disappears or simply fuses with the metaphysis is a question now being studied.

3. It is suggested that the deformities may be helped by interphalangeal fusion of severely involved joints in the position of function, and phalanges that become angled into varus or valgus may be improved by open wedge osteotomy or epiphysiodesis of the side of the epiphysis still functioning.

1. Myositis ossificans as a complication of tetanus is described.

2. Ossification in mesodermal tissue is briefly discussed.

1. Fifty-six cases of tibialis posterior transplant for drop foot are reported.

2. The results are known to be satisfactory in forty-nine of the fifty-six cases.

3. Serious complications have been few.

4. Re-education has been easy in the great majority of cases.