Aims

To investigate the longevity of uncemented fixation of a femoral component in total hip arthroplasty (THA) in patients with Dorr type C proximal femoral morphology.

This paper describes the preliminary results of a proximal tibial endoprosthesis which spares the knee joint and enables retention of the natural articulation by replacing part of the tibial metaphysis and diaphysis. In eight patients who had a primary malignant bone tumour of the proximal tibia, the distal stem, which had a hydroxyapatite-coated collar to improve fixation, was cemented into the medullary canal. The proximal end had hydroxyapatite-coated extracortical plates which were secured to the remaining proximal tibial metaphysis using cortical screws. The mean age of the patients at operation was 28.9 years (8 to 43) and the mean follow-up was for 35 months (4 to 48). The mean Musculoskeletal Tumour Society score was 79% (57% to 90%), the mean Oxford Knee score was 40 points of 48 (36 to 46) and the mean knee flexion was 112° (100° to 120°). In one patient, revision to a below-knee amputation through the prosthesis was required because of recurrence of the tumour. Another patient sustained a periprosthetic fracture which healed with a painful malunion. This was revised to a further endoprosthesis which replaced the knee.

In the remaining six patients the prosthesis allowed preservation of the knee joint with good function and no early evidence of loosening. Further follow-up is required to assess the longevity of these prostheses.

We report the ten-year survival of a cemented total knee replacement (TKR) in patients aged < 55 years at the time of surgery, and compare the functional outcome with that of patients aged > 55 years. The data were collected prospectively and analysed using Kaplan-Meier survival statistics, with revision for any reason, or death, as the endpoint. A total of 203 patients aged < 55 years were identified. Four had moved out of the area and were excluded, leaving a total of 221 TKRs in 199 patients for analysis (101 men and 98 women, mean age 50.6 years (28 to 55)); 171 patients had osteoarthritis and 28 had inflammatory arthritis. Four patients required revision and four died. The ten-year survival using revision as the endpoint was 98.2% (95% confidence interval 94.6 to 99.4). Based on the Oxford knee scores at five and ten years, the rate of dissatisfaction was 18% and 21%, respectively. This was no worse in the patients aged < 55 years than in patients aged > 55 years.

These results demonstrate that the cemented PFC Sigma knee has an excellent survival rate in patients aged < 55 ten years post-operatively, with clinical outcomes similar to those of an older group. We conclude that TKR should not be withheld from patients on the basis of age.

We compared two methods of reconstruction of the abductor mechanism in 15 patients after prosthetic replacement of the upper femur, to assess abductor strength and function.

Six patients in group I had direct fixation of the gluteus medius tendon and a segment of the original bone to the prosthesis. Nine patients in group 2 had the abductor tendon fixed to the iliotibial band. We assessed clinical function, isometric muscle strength and muscle cross-sectional area for each patient.

The patients in group 1 had better clinical and functional results (p = 0.059), with average peak torques for hip abduction of 92% of that in the non-operated leg in group 1, and of 57% in group 2. Group 1 had a mean muscle cross-sectional area of 69% and a mean value of strength per cross-sectional area of 134% when compared with the control side. The respective values for group 2 were 52% and 91%.

Direct fixation of the abductor muscles to the prostheses gave improved function and higher isometric abductor muscle force.

We report our results in 24 children with malignant primary bone tumours of the distal femur treated with a Stanmore extendible endoprosthesis (SEER). This consists of a femoral component that can be lengthened, a constrained knee and an uncemented sliding tibial component which crosses the proximal tibial physeal plate perpendicularly.

The average age of the patients at diagnosis was ten years and the mean follow-up was 4.7 years (2.5 to 7.9). The mean growth of the affected tibia was 76% (18 to 136) and of the fibula 83% (15 to 750) of the growth of the unaffected limb.

Measurement of growth arrest lines showed that the mean growth of the proximal tibial physis on the affected side was 69% (43 to 100) of that of the normal side. The great variability in the growth of the physis cannot yet be explained.

We examined the relationships between the serum levels of chromium and cobalt ions and the inclination angle of the acetabular component and the level of activity in 214 patients implanted with a metal-on-metal resurfacing hip replacement. Each patient had a single resurfacing and no other metal in their body. All serum measurements were performed at a minimum of one year after operation. The inclination of the acetabular component was considered to be steep if the abduction angle was greater than 55°.

There were significantly higher levels of metal ions in patients with steeply-inclined components (p = 0.002 for chromium, p = 0.003 for cobalt), but no correlation was found between the level of activity and the concentration of metal ions. A highly significant (p < 0.001) correlation with the arc of cover was found. Arcs of cover of less than 10 mm were correlated with a greater risk of high concentrations of serum metal ions. The arc of coverage was also related to the design of the component and to size as well as to the abduction angle of the acetabular component. Steeply-inclined acetabular components, with abduction angles greater than 55°, combined with a small size of component are likely to give rise to higher serum levels of cobalt and chromium ions. This is probably due to a greater risk of edge-loading.

Despite the use of ultraclean air, there are still cases of infection in total joint arthroplasty. One possible route by which bacteria may enter the wound is indirectly by contamination of instruments during skin preparation and draping.

We found that bacterial air counts were 4.4 times higher during preparation and draping for hip or knee arthroplasty using an unscrubbed, ungowned leg holder than during the operation itself. With the leg holder scrubbed and gowned during preparation and draping, the air counts were reduced but were still 2.4 fold greater than intraoperatively. On some occasions, the air counts during preparation and draping exceeded the standards for ultraclean air irrespective of the attire of the leg holder.

We recommend that the leg is held by a scrubbed and gowned member of the team. More importantly, we consider that instrument packs should be opened only after skin preparation and draping have been completed.

We reviewed 12 patients six years after they had undergone total hip replacement with a cementless prosthesis, the Ribbed Hip System (Waldemar Link GmbH & Co, Hamburg, Germany). Aseptic loosening of one or both components had necessitated revision surgery in seven patients, in five within two years of operation. In view of our experience we question the wisdom of allowing the uncontrolled use of new prosthesis without postoperative surveillance.

We assessed 41 patients with rheumatoid arthritis (47 hips) who had had revision hip arthroplasty, at an average follow-up of 7 years 4 months (2 to 19). The clinical results were excellent or satisfactory in 43 hips. Radiologically, 45 stems were secure. Fifteen sockets (36.6%) were radiologically loose. Three hips required rerevision. Socket failure is the predominant problem in rheumatoid patients after cemented revision arthroplasty.

Seven psoas bursae filled with purulent fluid and inspissated debris were revealed at revision operations for failed resurfacing hip arthroplasties, an incidence of 5.8% in such revisions. Histological and microbiological investigations demonstrated that the psoas bursa collections resulted from the tissue response to polyethylene wear debris. None was due to infection.

We report the short-term results of 100 cementless total hip replacements in 52 severely dysplastic and 48 totally dislocated hips, with some new technical solutions to the problems involved. In cases with a very narrow iliac bone, the acetabular screw ring is seated below the true cotyloid area. In hips with tight flexor and abductor muscles or with deformities of the proximal femur, various osteotomies were performed. Special attention was paid to careful pre-operative planning and precise operative technique. In spite of a high complication rate the results were generally good and even patients who required reoperation were satisfied with the final result.

In a prospective study, a double crossover wire with a compression spring was used to re-attach 52 un-united trochanters at revision operations on total hip arthroplasties. Bony union was achieved in 42 (81%) and was not influenced by the duration of the nonunion or the separation gap. The new method compared favourably with earlier revisions at which other methods of trochanteric re-attachment had been used.

In 30 rabbits, the medial meniscus was used to replace the anterior or posterior cruciate ligament. The changes that took place were followed in histological sections, obtained both from the area of insertion into bone and from the intra-articular part of the graft. There was a gradual differentiation to chondroid tissue, with subsequent calcific deposition and no appearance of normal ligamentous tissue. The strength of the graft after 52 weeks was only one-quarter of that of the normal ligament. Our results do not justify the use of the meniscus to replace a torn cruciate ligament.

An experimental evaluation was made of the efficacy of an unflanged cup, an ogee-flanged cup and the Exeter pressuriser in the pressurisation of acetabular cement. Only a very modest injection pressure could be generated through an unflanged socket and even this was readily lost as the socket "bottomed out". The ogee-flanged socket gave a consistently high injection pressure which could be maintained throughout the process of polymerisation. The Exeter pressuriser gave marginally better results. Of the two cements tested, Palacos with gentamicin showed better intrusion than CMW Type 1 cement, but it also allowed greater extrusion once pressure was released. The importance of maintaining a continuous pressure on the cement throughout polymerisation is emphasised.

Four types of prosthetic replacement for the anterior cruciate ligament (carbon fibre, carbon fibre and Dacron composite, Dacron alone and bovine xenograft) were assessed at three, six and 12 months after implantation in the knees of New Zealand white rabbits. The synovium and both intra-articular and intra-osseous portions of the ligaments were examined macroscopically, by light microscopy and by scanning electron microscopy. All the knees showed mild synovitis, and there was no significant growth into the intra-articular part of any ligament. Carbon fibre and xenograft did not appear to be suitable materials in this animal model. The composite ligament showed short-term ingrowth of fibrous tissue only into the periphery of the sheath in its intra-osseous portion, whereas the Dacron ligament showed progressive fibrous tissue ingrowth with some bony incorporation of its outer fibres.

We report the use of a new approach for elbow arthroplasty in 58 cases over a 20-year period. A wide exposure, obtained by elevating the triceps attachment and dividing the radial collateral ligament, allows the excision of diseased tissue, articular irregularities and osteophytes. Normal anatomy is restored and active mobilisation can be started 10 days after operation. Good or fair results, with over 70 degrees of joint movement, were achieved in 88% of cases.

Sixty unconstrained elbow replacements of a new design have been followed prospectively for three to nine years. Review showed that 50% had excellent relief of pain and return of function, 27% had had major complications requiring removal or revision of the prosthesis and 23% had minor complications which marred the result. Further research in this field seems worthwhile.