Aims

The primary aim of this independent prospective randomised trial was to compare serum metal ion levels for ceramic-on-metal (CoM) and metal-on-metal (MoM) bearing surfaces in total hip arthroplasty (THA). Our one-year results demonstrated elevation in metal ion levels above baseline with no significant difference between the CoM and MoM groups. This paper reviews the five-year data.

Polyethylene wear debris can cause osteolysis and the failure of total hip arthroplasty. We present the five-year wear rates of a highly cross-linked polyethylene (X3) bearing surface when used in conjunction with a 36 mm ceramic femoral head.

This was a prospective study of a cohort of 100 THAs in 93 patients. Pain and activity scores were measured pre- and post-operatively. Femoral head penetration was measured at two months, one year, two years and at five years using validated edge-detecting software (PolyWare Auto).

At a mean of 5.08 years (3.93 to 6.01), 85 hips in 78 patients were available for study. The mean age of these patients was 59.08 years (42 to 73, the mean age of males (n = 34) was 59.15 years, and females (n = 44) was 59.02 years). All patients had significant improvement in their functional scores (p < 0.001). The steady state two-dimensional linear wear rate was 0.109 mm/year. The steady state volumetric wear rate was 29.61 mm³/year. No significant correlation was found between rate of wear and age (p = 0.34), acetabular component size (p = 0.12) or clinical score (p = 0.74).

Our study shows low steady state wear rates at five years in X3 highly cross-linked polyethylene in conjunction with a 36 mm ceramic femoral head. The linear wear rate was almost identical to the osteolysis threshold of 0.1 mm/year recommended in the literature.

Cite this article: Bone Joint J 2015;97-B:1470–4.

This study reports on the first 150 consecutive Oxford cementless unicompartmental knee arthroplasties (UKA) performed in an independent centre (126 patients). All eligible patients had functional scores (Oxford knee score and high activity arthroplasty score) recorded pre-operatively and at two- and five-years of follow-up. Fluoroscopically aligned radiographs were taken at five years and analysed for any evidence of radiolucent lines (RLLs), subsidence or loosening. The mean age of the cohort was 63.6 years (39 to 86) with 81 (53.1%) males. Excellent functional scores were maintained at five years and there were no progressive RLLs demonstrated on radiographs. Two patients underwent revision to a total knee arthroplasty giving a revision rate of 0.23/100 (95% confidence interval 0.03 to 0.84) component years with overall component survivorship of 98.7% at five years. There were a further four patients who underwent further surgery on the same knee, two underwent bearing exchanges for dislocation and two underwent lateral UKAs for disease progression. This was a marked improvement from other UKAs reported in New Zealand Joint Registry data and supports the designing centre’s early results.

Cite this article: Bone Joint J 2015;97-B:1358–63.

In a double-blinded randomised controlled trial, 83 patients with primary osteoarthritis of the hip received either a ceramic-on-metal (CoM) or metal-on-metal (MoM) total hip replacement (THR). The implants differed only in the bearing surfaces used. The serum levels of cobalt and chromium and functional outcome scores were compared pre-operatively and at six and 12 months post-operatively.

Data were available for 41 CoM and 36 MoM THRs (four patients were lost to follow-up, two received incorrect implants). The baseline characteristics of both cohorts were similar. Femoral head size measured 36 mm in all but two patients who had 28 mm heads. The mean serum cobalt and chromium levels increased in both groups, with no difference noted between groups at six months (cobalt p = 0.67, chromium p = 0.87) and 12 months (cobalt p = 0.76, chromium p = 0.76) post-operatively. Similarly, the mean Oxford hip scores, Western Ontario and McMaster Universities Osteoarthritis index and University of California, Los Angeles activity scores showed comparable improvement at 12 months.

Our findings indicate that CoM and MoM couplings are associated with an equivalent increase in serum cobalt and chromium levels, and comparable functional outcome scores at six and 12-months follow-up.

We have examined the outcome of 400 consecutive patients who underwent total knee replacement with the Low Contact Stress mobile-bearing system between 1993 and 1994 and were followed up for a minimum of ten years. All operations were performed by surgeons in Christchurch, New Zealand, who used no other knee prosthesis during the study time.

At ten years after operation 238 patients (244 knees) remained for independent clinical and radiological assessment. There was a significant improvement (p < 0.001) in the postoperative knee scores at one, three, seven and ten years, although a slight deterioration in the score occurred between seven and ten years which did not reach statistical significance. The survival for polyethylene wear or loosening was 97% (95% CI 96 to 98) and survival using reoperation for any cause was 92% (95% CI 90 to 94) at 12 years. Polyethylene wear was more common in the meniscal-bearing component, with five knees requiring revision and a further eight demonstrating early wear. Osteolysis was not seen in the rotating platform component, but was present in three of the meniscal-bearing knees.

There was no association between the radiological alignment at one year and those knees that subsequently required revision. However, there was an association between the overall limb alignment and the Western Ontario McMasters University score (p < 0.001).

The Low Contact Stress mobile-bearing total knee replacement has proved to be a reliable implant at ten years when used in primary knee replacement irrespective of the deformity and diagnosis.

We performed a prospective randomised trial on matched groups of patients with displaced tibial shaft fractures to compare conservative treatment with closed intramedullary nailing. The results showed conclusively that intramedullary nailing gave more rapid union with less malunion and shortening. Nailed patients had less time off work with a more predictable and rapid return to full function. We therefore consider that closed intramedullary nailing is the most efficient treatment for displaced fractures of the tibial shaft.

Fifty consecutive comminuted fractures of the femoral shaft were treated by closed unlocked intramedullary nailing. Twelve unstable fractures also had cast-bracing. There were no cases of infection or non-union, and satisfactory results were achieved in 38 fractures (76%). More severe comminution led to a higher incidence of unsatisfactory results, but malrotation deformity was seen more often in less comminuted fractures and appeared to be due to poor operative reduction. Shortening in severe comminution was the main complication and was not controlled by supplementary cast-bracing. Closed unlocked intramedullary nailing is effective for lesser grades of comminution, but fractures with no cortical continuity at reduction should be treated with a locking nail.

A new method of demonstrating sagittal laxity in the anterior cruciate-deficient knee is described. Seventy such knees were compared to 70 normal knees. Sagittal laxity was recorded as the average displacement of the medial and lateral femoral condyles. This displacement index was significantly different between the two groups of knees (P less than 0.0001). A range for normal and abnormal knees is discussed. Quantitative assessment of the degree of sagittal laxity by clinical evaluation is shown to be unreliable. Only the pivot-shift test demonstrated any significant correlation with the amount of sagittal displacement (P less than 0.05).

Blood flow in intact tendons in dogs was measured using 57Co-labelled microspheres and compared with the simultaneous clearance of a diffusible radionuclide, 85Sr, by the same tendons. Clearance was significantly greater than flow in all tendons, indicating that diffusion from surrounding tissues may be important in the nutrition of normal tendons.

Two cases of congenital pseudarthrosis of the ulna due to neurofibromatosis are reported. Similar radiographic changes in the ulna were found, with distortion of the capitulum and part of the trochlea and bowing of the radius. In one patient the head of the radius was dislocated and in the other it dislocated readily during pronation. A possible mechanism to explain the findings was suggested. On the basis of these and a review of the literature it is recommended that the main aim of treatment should be maintenance of the normal relative lengths of the radius and ulna by early excision of the pseudarthrosis to remove the restraining effect of the abnormal ulna. This will allow normal development of the lower end of the humerus and radius and prevent dislocation of the radial head.

The incidence of congenital dislocation of the hip in 156 children with infantile idiopathic scoliosis was 6.4 per cent, approximately 10 times its frequency in the general population. In both of these deformities there was a predominance of girls (eight girls: two boys). In unilateral dislocation of the hip the convexity of the thoracic scoliosis was on the same side as the dislocation. Eight out of the 10 children with both deformities also had plagiocephaly.