Objectives

Prosthetic joint infection (PJI) is the most common cause of arthroplasty failure. However, infection is often difficult to detect by conventional bacterial cultures, for which false-negative rates are 23% to 35%. In contrast, 16S rRNA metagenomics has been shown to quantitatively detect unculturable, unsuspected, and unviable pathogens. In this study, we investigated the use of 16S rRNA metagenomics for detection of bacterial pathogens in synovial fluid (SF) from patients with hip or knee PJI.

Objectives

Prosthetic joint infection (PJI) diagnosis is a major challenge in orthopaedics, and no reliable parameters have been established for accurate, preoperative predictions in the differential diagnosis of aseptic loosening or PJI. This study surveyed factors in synovial fluid (SF) for improving PJI diagnosis.

Fresh-frozen allograft bone is frequently used in orthopaedic surgery. We investigated the incidence of allograft-related infection and analysed the outcomes of recipients of bacterial culture-positive allografts from our single-institute bone bank during bone transplantation. The fresh-frozen allografts were harvested in a strict sterile environment during total joint arthroplasty surgery and immediately stored in a freezer at -78º to -68º C after packing. Between January 2007 and December 2012, 2024 patients received 2083 allografts with a minimum of 12 months of follow-up. The overall allograft-associated infection rate was 1.2% (24/2024). Swab cultures of 2083 allografts taken before implantation revealed 21 (1.0%) positive findings. The 21 recipients were given various antibiotics at the individual orthopaedic surgeon’s discretion. At the latest follow-up, none of these 21 recipients displayed clinical signs of infection following treatment. Based on these findings, we conclude that an incidental positive culture finding for allografts does not correlate with subsequent surgical site infection. Additional prolonged post-operative antibiotic therapy may not be necessary for recipients of fresh-frozen bone allograft with positive culture findings.

Cite this article: Bone Joint J 2015;97-B:427–31.

Objectives

The objective of this study is to determine an optimal antibiotic-loaded bone cement (ALBC) for infection prophylaxis in total joint arthroplasty (TJA).

We investigated the antibiotic concentration in fresh-frozen femoral head allografts harvested from two groups of living donors. Ten samples were collected from patients with osteoarthritis of the hip and ten from those with a fracture of the neck of the femur scheduled for primary arthroplasty. Cefazolin (1 g) was administered as a pre-operative prophylactic antibiotic. After storage at −80°C for two weeks the pattern of release of cefazolin from morsellised femoral heads was evaluated by an in vitro broth elution assay using high-performance liquid chromatography. The bioactivity of the bone was further determined with an agar disc diffusion and standardised tube dilution bioassay. The results indicated that the fresh-frozen femoral heads contained cefazolin. The morsellised bone released cefazolin for up to four days. The concentration of cefazolin was significantly higher in the heads from patients with osteoarthritis of the hip than in those with a fracture. Also, in bioassays the bone showed inhibitory effects against bacteria.

We concluded that allografts of morsellised bone from the femoral head harvested from patients undergoing arthroplasty of the hip contained cefazolin, which had been administered pre-operatively and they exhibited inhibitory effects against bacteria in vitro.

We evaluated 31 patients with bilateral dysplastic hips who had undergone periacetabular osteotomy for early (Tönnis grade 0 or 1) or moderate (Tönnis grade 2) osteoarthritis in one hip and total hip replacement for advanced (Tönnis grade 3) osteoarthritis in the other. At a mean follow-up of 5.5 years (2 to 9) after periacetabular osteotomy and 6.7 years (3 to 10) after total hip replacement, there was no difference in the functional outcome in hips undergoing osteotomy for early or moderate osteoarthritis and those with a total hip replacement, as determined by the Merle d’Aubigné and Postel score and the Western Ontario and McMaster Universities osteoarthritis index. More patients preferred the spherical periacetabular osteotomy to total hip replacement (53% vs 23%; p = 0.029). Osteoarthritis secondary to hip dysplasia is often progressive. Given the results, timely correction of dysplasia by periacetabular osteotomy should be considered whenever possible in young patients since this could produce a favourable outcome which is comparable with that of total hip replacement.

Multiple drilling is reported to be an effective treatment for osteonecrosis of the head of femur, but its effect on intra-osseous pressure has not been described. We undertook multiple drilling and recorded the intra-osseous pressure in 75 osteonecrotic hips in 60 patients with a mean age of 42 years (19 to 67). At a mean follow-up of 37.1 months (24 to 60), 42 hips (56%) had a clinically successful outcome. The procedure was effective in reducing the mean intra-osseous pressure from 57 mmHg (SD 22) to 16 mmHg (SD 9). Hips with a successful outcome had a mean pressure of 26 mmHg (SD 19). It was less effective in preventing progression of osteonecrosis in hips with considerable involvement and in those with a high intra-osseous pressure in the intertrochanteric region (mean 45 mmHg (SD 25)). This study is not able to answer whether a return of the intra-osseous pressure to normal levels is required for satisfactory healing.

We have carried out in 24 patients, a two-stage revision arthroplasty of the hip for infection with massive bone loss. We used a custom-made, antibiotic-loaded cement prosthesis as an interim spacer. Fifteen patients had acetabular deficiencies, eight had segmental femoral bone loss and one had a combined defect.

There was no recurrence of infection at a mean follow-up of 4.2 years (2 to 7). A total of 21 patients remained mobile in the interim period. The mean Merle D’Aubigné and Postel hip score improved from 7.3 points before operation to 13.2 between stages and to 15.8 at the final follow-up. The allograft appeared to have incorporated into the host bone in all patients. Complications included two fractures and one dislocation of the cement prosthesis.

The use of a temporary spacer maintains the function of the joint between stages even when there is extensive loss of bone. Allograft used in revision surgery after septic conditions restores bone stock without the risk of recurrent infection.

We retrospectively reviewed 45 hip arthroplasties which were performed over a period of 20 years in 38 patients with cirrhosis of the liver. There was a high perioperative 30-day complication rate (26.7%). Advanced cirrhosis was associated with a higher risk of complications (p = 0.004) as also was increased age, a high level of creatinine, a low level of albumin, a low platelet count, ascites, encephalopathy and an increased operative blood loss. The survival of the prosthesis at five years was 77.8% and infection was a major cause of failure.

In view of the high rate of early complications and the limited longevity of the prosthesis, surgeons who perform hip arthroplasty on such patients should counsel them appropriately preoperatively.