Aim

Reconstruction of composite soft-tissue defects with extensor apparatus deficiency in patients with periprosthetic joint infection (PJI) of the knee is challenging. We present a single-centre multidisciplinary orthoplastic treatment concept based on a retrospective outcome analysis over 20 years.

At our institution, periprosthetic hip joint infections are treated according to a previously defined treatment algorithm. Each patient is evaluated regarding risk factors such as duration of clinical signs and symptoms, stability of the implant, condition of the soft tissue, and antimicrobial susceptibility of the microorganism. Depending on these factors, either debridement with retention, one-stage exchange, or two-stage exchange with spacer (short interval, 2–4 weeks), or without spacer (long interval, 8 weeks) is performed. Very rarely, resection arthroplasty or lifetime suppression is necessary. All surgical procedures are combined with an antimicrobial therapy for 6 or 12 weeks, depending on the surgical pathway. For infection due to staphylococci, whenever possible, rifampicin is used in combination with a fluoroquinolone. From 2002–2006, 89 patients with 95 episodes (3 patients with 2 independent episodes, 3 patients with bilateral infection) of periprosthetic hip joint infection have been treated at our hospital. Five patients died within 2 years after revision, one of them with septic shock related to the periprosthetic hip joint infection. One patient is living abroad. All other patients (n=83) had consecutive follow-up visits at least until 2 years after infection treatment without recurrence. Debridement with retention has been performed in 18 episodes, one-stage exchange in 25 episodes, two-stage exchange with temporary spacer for 2–4 weeks has been performed in 26 episodes, and two-stage exchange without spacer and an interval of 8 weeks in 19 episodes. In 4 cases, immediate resection arthroplasty was performed and 3 patients received long-term suppression therapy. After debridement with retention, 3 recurrences and one event of death occurred (4/18=22.2%), 3 of them did not fulfil the criteria of the algorithm. No failure was observed after one-stage exchange (0/25). Treatment with two-stage exchange was followed by one failure in the group with spacer and short interval (1/26=3.8%), as well as one in the group without spacer and long interval (1/19=5.3%). No recurrence occurred after resection arthroplasty or suppression therapy. All 5 patients with relapse could be cured with a one- or two-stage exchange and remained without recurrence. Comparing one-stage versus two-stage exchange, one-stage exchange is known to have better functional results. It is associated with better patient acceptance, shorter hospital stay, and therefore lower economic burden.

In conclusion, one-stage exchange implies no increasing risk of recurrence provided that the standards of our algorithm are considered.

The aim of this study was to obtain detailed long-term data on the cement-bone interface in patients with cemented stems, implanted using the constrained fixation technique. A total of eight stems were removed together with adjacent bone during post-mortem examinations of patients with well-functioning prostheses. Specimens were cut at four defined levels, contact radiographs were obtained for each level, and slices were prepared for histological analysis. Clinical data, clinical radiographs, contact radiographs and histological samples were examined for signs of loosening and remodelling. The mean radiological follow-up was 9.6 years and all stems were well-fixed, based on clinical and radiological criteria. Contact radiographs revealed an incomplete cement mantle but a complete filling of the medullary canal for all implants. Various amounts of polyethylene particles were evident at the cement-bone interface of seven stems, with no accompanying inflammatory reaction. Cortical atrophy and the formation of an ‘inner cortex’ were confirmed in six of eight stems by contact radiographs and histology, but were only visible on two clinical radiographs.

Our results confirm that a complete cement mantle is not essential for the survival of Müller straight stems into the mid term, and support our hypothesis that no benefit to long-term survival can be expected from modern cementing techniques.

The original forged Müller straight stem (CoNiCr) has shown excellent ten- to 15-year results. We undertook a long-term survival analysis with special emphasis on radiological changes within a 20-year period of follow-up.

In all, 165 primary total hip replacements, undertaken between July 1984 and June 1987 were followed prospectively. Clinical follow-up included a standardised clinical examination, and radiological assessment was based on a standardised anteroposterior radiograph of the pelvis, which was studied for the presence of osteolysis, debonding and cortical atrophy.

Survival of the stem with revision for any reason was 81% (95% confidence interval (CI), 76 to 86) at 20 years and for aseptic loosening 87% (95% CI, 82 to 90). At the 20-year follow-up, 15 of the surviving 36 stems showed no radiological changes. Debonding (p = 0.005), osteolysis (p = 0.003) and linear polyethylene wear (p = 0.016) were associated with aseptic loosening, whereas cortical atrophy was not associated with failure (p = 0.008).

The 20-year results of the Müller straight stem are comparable to those of other successful cemented systems with similar follow-up. Radiological changes are frequently observed, but with a low incidence of progression, and rarely result in revision. Cortical atrophy appears to be an effect of ageing and not a sign of loosening of the femoral component.

Polyethylene wear of acetabular components is a key factor in the development of periprosthetic osteolysis and wear at the articular surface has been well documented and quantified, but fewer data are available about changes which occur at the backside of the liner.

At revision surgery for loosening of the femoral component we retrieved 35 conventional modular acetabular liners of the same design. Linear and volumetric articular wear, backside volumetric change and the volume of the screw-head indentations were quantified. These volumes, clinical data and the results from radiological Ein Bild Röntgen Analyse migration analysis were used to identify potential factors influencing the volumetric articular wear and backside volumetric change.

The rate of backside volumetric change was found to be 2.8% of the rate of volumetric articular wear and decreased with increasing liner size. Migrated acetabular components showed significantly higher rates of backside volumetric change plus screw-head indentations than those without migration.

The backside volumetric change was at least ten times larger than finite-element simulation had suggested. In a stable acetabular component with well-anchored screws, the amount of backside wear should not cause clinical problems. Impingement of the screw-heads could produce more wear particles than those generated at the liner-shell interface. Because the rate of backside volumetric change is only 2.8% of the rate of volumetric articular wear and since creep is likely to contribute a significant portion to this, the debris generated by wear at the backside of the liner may not be sufficient to create a strong osteolytic response.

An 18-year-old girl with moderate joint laxity presented with recurrent dislocation of the calcaneocuboid joint in both feet. We achieved successful stabilisation on both sides by reconstruction of the ligaments and capsule using the plantaris tendons.