1. By the surgical division of the main capsular artery supplying the upper femoral epiphysis of the rabbit it is possible to cause changes which resemble those occurring in human osteochondritis. 2. The phase of anaemia (ischaemia and hypovascularisation) lasts in the rabbit less than fifteen days. The whole process lasts approximately ninety days, and only for one-sixth of this period does the femoral head suffer from a reduction in its blood supply. 3. After the fifteenth day until the end of the process the condition changes to one of hypervascularisation, which lasts six times longer than that of ischaemia or relative anaemia. 4. By the ninetieth day the whole process has lost its activity and only some permanent deformities remain. The vascular pattern is from then on the normal in the rabbit. 5. The "osteochondritic" changes cannot be elicited in the distal femoral epiphysis. The apparent reason is the presence of anastomoses between the main artery and other epiphysial vessels. 6. There seems to be reasonable experimental evidence, by implication, in favour of the vascular theory of osteochondritis of the upper femoral epiphysis in children

Twenty patients each with a fractured femoral neck had a prosthesis with a built-in ball-and-socket joint inserted. Movements at the built-in joint were compared with total hip movement immediately after operation, one month later and three months later. It was found that the built-in joint soon lost mobility and at three months was almost completely stiff. Consequently such joints cannot be expected to prevent the acetabular erosion which is liable to follow femoral head replacement for fracture

Of 899 patients with sickle-cell disease, aged between 6 and 28 years, who attended clinics in the Guinea Savannah of Nigeria in 1982 and 1983, 29 had symptoms of avascular necrosis of the femoral head. This group was studied in detail. Twenty-eight patients had haemoglobin-SS electrophoretic patterns and one had haemoglobin-SC. The male to female ratio was 1 to 1.6, and most of the patients were aged between 6 and 15 years at the onset of hip symptoms. These symptoms correlated with the radiographic lesions, but were not related to the age or sex of the patient. The radiographic lesions varied widely and were related to the age at onset of hip symptoms. A new radiological classification is proposed

The stages in adolescent slipping of the upper femoral epiphysis are classified in relation to treatment. The operation of open replacement of the displaced femoral head is described, and the results of a personal series of seventy-three such operations are presented. Open replacement is excellent treatment for severe chronic slipping so long as the growth plate is still open. The greater incidence of avascular necrosis in acute-on-chronic cases is probably due to damage to the blood supply of the head at the time of the acute slip or kinking of the vessels before replacement. Prolonged traction before operation may increase the risk of chondrolysis. Late onset of osteoarthritis when neither avascular necrosis nor chondrolysis has occurred may be due to misfitting of the articular cartilage because of inaccurate reduction

Articular cartilage from the femoral heads of 27 patients having an arthroplasty for subcapital fracture was studied, and its mechanical and chemical properties compared to those of a group of 33 age-matched macroscopically normal autopsy specimens. Water and proteoglycan contents were measured, as were swelling ability, compressive and tensile strength of the cartilage, and the density of the underlying bone. Cartilage from the fracture specimens had a significantly reduced proteoglycan content, as measured by fixed charge density, and increased swelling ability. These results indicate that this group differs from the "normal" population and care should be taken before they are accepted as control material for studies on osteoarthritic cartilage. Another finding was that bone density was much the same in the fracture and the normal group. This casts some doubt upon the concept that patients who sustain subcapital fractures are more osteoporotic than the average for the same age range

We evaluated 38 hip reconstructions in 36 patients at a mean follow-up of 5.9 years (range 4 to 9.1) after femoral head allografts had been used to augment severely deficient acetabular bone stock. The patients were all relatively young and had many previous operations. Their pre-operative Harris hip rating averaged 46 points (range 18 to 73). All the allografts united and there were no infections. However, 12 acetabular components (32%) became loose; six of these had needed revision using the healed allograft, and two hips had required resection arthroplasty. The 30 surviving hips had a mean Harris hip score of 82 points. Some radiographic evidence of graft resorption was seen in 23 hips, though this was mild in 17. The extent of cover provided by the allograft and the severity of graft resorption both correlated with acetabular loosening. Although structural allografts had allowed successful hip reconstructions in many of these patients with major bone loss, the failure rate had increased from zero at four years to 32% at six years; clearly they provide only a short-term solution

Ischaemia resulting from increased joint pressure may play a role in the pathogenesis of necrosis of the femoral head epiphysis. We studied the effect of temporary vascular occlusion on this epiphysis in young rabbits. Occlusion for six hours resulted in necrosis of trabecular bone and of intertrabecular marrow and vascular tissue, later followed by revascularisation and repair, as has been demonstrated previously. In contrast, raised intra-articular pressure lasting for only two hours resulted in a more complex picture: trabecular osteocytes were dead, whereas the bone-forming marrow was shown by fluorochrome labelling to remain viable, and to form appositional repair bone throughout the epiphysis. We concluded that transient vascular occlusion may cause the death of trabeculae despite intact perfusion of the bone. This type of change may be important in the pathogenesis of Perthes' disease

We have prospectively studied the wear of enhanced ultra-high molecular-weight polyethylene (Hylamer) in combination with a zirconia femoral head of 22.225 mm diameter on a cemented, triple-tapered, collarless, polished stem, the C Stem. The 71 patients who underwent total hip arthroplasty had a mean follow-up of six years (3 to 8). No patient died or was lost to follow-up. The clinical results were excellent with 96% of patients satisfied. There were no revisions. Two cups were considered to be loose radiologically. One was avulsed from the cement in a skiing accident, with a periprosthetic fracture of the femur, but has remained stable for more than seven years. One femur shows radiological appearances which are compatible with a healing infection. One femoral component is at risk of loosening. The mean rate of penetration of the cup was 0.22 mm/year (0.06 to 0.55). Our results appear to be within the guidelines set by the National Institute of Clinical Excellence. We have discontinued the use of Hylamer despite excellent clinical results and no revisions to date because the high initial rates of penetration did not settle to the expected low levels within the anticipated time

We report the five-year outcome of a randomised controlled trial which used radiostereometric analysis (RSA) to assess the influence of surface oxidised zirconium (OxZr, Oxinium) on polyethylene wear in vivo.

A total of 120 patients, 85 women and 35 men with a mean age of 70 years (59 to 80) who were scheduled for primary cemented total hip arthroplasty were randomly allocated to four study groups. Patients were blinded to their group assignment and received either a conventional polyethylene (CPE) or a highly cross-linked (HXL) acetabular component of identical design. On the femoral side patients received a 28 mm head made of either cobalt-chromium (CoCr) or OxZr.

The proximal head penetration (wear) was measured with repeated RSA examinations over five years. Clinical outcome was measured using the Harris hip score.

There was no difference in polyethylene wear between the two head materials when used with either of the two types of acetabular component (p = 0.3 to 0.6). When comparing the two types of polyethylene there was a significant difference in favour of HXLPE, regardless of the head material used (p < 0.001).

In conclusion, we found no advantage of OxZr over CoCr in terms of polyethylene wear after five years of follow-up. Our findings do not support laboratory results which have shown a reduced rate of wear with OxZr. They do however add to the evidence on the better resistance to wear of HXLPE over CPE.

Cite this article: Bone Joint J 2015;97-B:1463–9.

The inferior gluteal artery is described in standard anatomy textbooks as contributing to the blood supply of the hip through an anastomosis with the medial femoral circumflex artery. The site(s) of the anastomosis has not been described previously. We undertook an injection study to define the anastomotic connections between these two arteries and to determine whether the inferior gluteal artery could supply the lateral epiphyseal arteries alone. From eight fresh-frozen cadaver pelvic specimens we were able to inject the vessels in 14 hips with latex moulding compound through either the medial femoral circumflex artery or the inferior gluteal artery. Injected vessels around the hip were then carefully exposed and documented photographically.

In seven of the eight specimens a clear anastomosis was shown between the two arteries adjacent to the tendon of obturator externus. The terminal vessel arising from this anastomosis was noted to pass directly beneath the posterior capsule of the hip before ascending the superior aspect of the femoral neck and terminating in the lateral epiphyseal vessels. At no point was the terminal vessel found between the capsule and the conjoined tendon. The medial femoral circumflex artery receives a direct supply from the inferior gluteal artery immediately before passing beneath the capsule of the hip.

Detailed knowledge of this anatomy may help to explain the development of avascular necrosis after hip trauma, as well as to allow additional safe surgical exposure of the femoral neck and head.

Aims

The aim of this study was to evaluate the correlation between Salter’s criteria and Kalamchi’s classification of avascular necrosis in patients treated for developmental dysphasia of the hip (DDH).

1. After almost seventeen years the three metal prostheses remain in approximately the original position in which they were inserted.

2. All three patients are ambulatory and two of them pleased with the result.

3. The youngest patient, now fifty-six, has a solid ankylosis of the hip and leads an active life free of pain.

4. In view of the attritional changes which have been seen to occur as a result of the reaction of bone to metal, it is suggested that resection replacement operations should be reserved for the primary treatment of certain fractures in the elderly and in those patients who are expected to be mostly inactive for the rest of their life. As a rough guide, it is considered that the operation should not be carried out under the age of seventy.

We have reviewed 54 patients who had undergone 61 total hip replacements using bulk femoral autografts to augment a congenitally dysplastic acetabulum. There were 52 women and two men with a mean age of 42.4 years (29 to 76) at the time of the index operation. A variety of different prostheses was used: 28 (45.9%) were cemented and 33 (54.1%) uncemented. The graft technique remained unchanged throughout the series.

Follow-up was at a mean of 8.3 years (3 to 20). The Hospital for Special Surgery hip score improved from a mean of 10.7 (4 to 18) pre-operatively to a mean of 35 (28 to 38) at follow-up.

The position of the acetabular component was anatomical in 37 hips (60.7%), displaced less than 1 cm in 20 (32.7%) and displaced more than 1 cm in four (6.6%). Its cover was between 50% and 75% in 34 hips (55.7%) and less than 50% in 25 (41%). In two cases (3.3%), it was more than 75%.

There was no graft resorption in 36 hips (59%), mild resorption in 21 (34%) and severe resorption in four (6%).

Six hips (9.8%) were revised for aseptic loosening. The overall rate of loosening and revision was 14.8%. Overall survival at 8.3 years was 93.4%.

The only significant factor which predicted failure was the implantation of the acetabular component more than 1 cm from the anatomical centre of rotation of the hip.