Jorma Pajamäki

Outcome of prosthesis exchange for infected knee arthroplasty: the effect of treatment approach

Background and purpose Two-stage revision remains the gold standard in the treatment of infected knee arthroplasty. Lately, good long-term results of direct exchange arthroplasty have been reported. The purpose of this literature review is to compare the clinical outcome achieved with one-stage revision and two-stage revision with different types of spacers. Methods A thorough systematic review of literature was undertaken to idenepsy reports on the treatment alternatives. Papers written in English or including an English abstract, published from 1980 through 2005, and reporting either the success rate in eradication of infection or the clinical status achieved were reviewed. 31 original articles describing the results of 154 one-stage exchange arthoplasties and of 926 two-stage exchange arthoplasties were included. The depth of detail in the description of materials and methods varied markedly, making it impossible to perform a meta-analysis. Instead, a descriptive review of the results is presented. Results With a follow-up of 12–122 months, the overall success rate in eradication of infection was 73–100% after one-stage revisions and 82–100% after two-stage revisions. Reinfection rates were the lowest in series where articulating cement spacers were used, though the follow-up was relatively short. Studies using articulating spacers reported the highest average postoperative ranges of motion. Otherwise, no correlations were observed between the clinical outcome and the length of follow-up, the type of revision, or the type of spacer. The clinical outcome (knee scores and range of motion) of the one-stage revisions was no different from that of the two-stage revisions. Interpretation Two-stage exchange is an effective treatment. Mobile spacers may further improve the range of motion. More experience in one-stage revision is required in order to define its role in the management of infected knee arthroplasties.

Revision Total Knee Arthroplasty: 1990 Through 2002

BACKGROUND National and regional arthroplasty registries have been used to study the results of primary total knee arthroplasties. The purpose of this paper was to present the results of revision total knee replacements and describe predictors of survival of those replacements, with repeat revision as the end point. METHODS The nationwide Finnish Arthroplasty Registry included 2637 revision total knee arthroplasties from 1990 through 2002. Survivorship of the revision total knee arthroplasties was analyzed, with repeat revision as the end point. The survivorship analyses comprised evaluations of the proportional hazards assumption followed by calculations of univariate and multivariate statistics and model diagnostics as appropriate. RESULTS The survival rate following the revision total knee arthroplasties was 95% (95% confidence interval, 94% to 96%) at two years (1874 knees), 89% (95% confidence interval, 88% to 90%) at five years (944 knees), and 79% (95% confidence interval, 78% to 81%) at ten years (141 knees). Multivariate regression analysis showed the most significant predictors of prosthetic survival to be the age of the patient and the life in service of the primary total knee replacement (that is, the time between the primary total knee replacement and the revision). Survivorship was also significantly predicted by the year of the first revision total knee arthroplasty and the reason for the revision. CONCLUSIONS An age greater than seventy years, revision five years or more after the primary arthroplasty, and absence of patellar subluxation are positive indicators of survival of a revision total knee replacement. We believe that normal aging as well as the deconditioning effect of disease (osteoarthritis and rheumatoid arthritis) and its treatment (primary total knee replacement) may lead to a reduced activity level, which, together with a presumed reluctance to operate on elderly patients, protects against repeat revisions. LEVEL OF EVIDENCE Prognostic Level II. See Instructions to Authors for a complete description of levels of evidence.

Spacer prostheses in two-stage revision of infected knee arthroplasty.

At present, no consensus exists on the best spacer alternative for the management of two-stage exchange arthroplasty of infected knee arthroplasties. In this retrospective study, patient records of 24 patients, who had undergone two-stage revisions in which resterilised prosthetic components were used as spacers, were reviewed. The outcome was compared to that of operations performed during the same period (1993–2003) using cement spacers (n=10). With an average follow-up of 32 months, control of infection was achieved in 26 cases (76%), with good or excellent clinical outcome in 19 cases (56%). Treatment failed and resulted in amputation at the level of the thigh before reimplantation in one case. Three patients did not undergo reimplantation. In four cases (12%) infection relapsed. The reinfection rate did not differ between the two spacer groups. Patients treated with resterilised components had a superior range of motion during the period between the two stages. Operative time was shorter and there was less blood loss in the reimplantation arthroplasty when a prosthetic spacer was used. We consider resterilised prosthetic components a safe and effective alternative to cement spacers in the management of infected knee arthroplasties.RésuméIl n’existe pas actuellement de consensus sur les meilleurs spacers à utiliser dans le traitement des reprises en deux temps des prothèses totales du genou infectées. Dans cette étude rétrospective, 24 patients ont été évalués, patients ayant bénéficié d’un changement prothétique en deux temps, le spacer utilisé pouvant être les composants prothétiques stérilisés. Nous avons comparé le devenir de cette série (1993–2003) à une autre série traitée pendant la même période et en utilisant un spacer en ciment (10 patients). Le délai moyen était de 32 mois et la guérison de l’infection a été obtenue dans 76% des cas (26) avec un excellent ou un bon résultat dans 19 cas (56%). Les échecs du traitement sont secondaires à une amputation de cuisse avant la réimplantation (un cas). Trois patients n’ont pas eu de réimplantation et dans 4 cas (12%) l’infection a récidivé. La récidive de l’infection n’est pas différente entre les deux groupes de patients quelle que soit la nature du spacer. Les patients traités avec des composants prothétiques re-stérilisés ont eu une meilleure mobilité pendant la période intermédiaire. Le temps opératoire et les pertes sanguines sont significativement diminués lorsque le spacer utilisé est la prothèse re-stérilisée. Nous considérons en conclusion, que la re-stérilisation du composant prothétique est une méthode sure, efficace et une bonne alternative au spacer en ciment lors du traitement des prothèses totales du genou infectées.

Young age and wedge stem design are risk factors for periprosthetic fracture after arthroplasty due to hip fracture: A case-control study

Background It has been suggested that a hip fracture as a primary diagnosis for arthroplasty is a risk factor for periprosthetic fracture. Patients and methods We compared 16 patients with late periprosthetic fracture of the femur to 48 controls. The primary diagnosis for all patients was hip fracture. The date of operation for hip fracture was used to select the control group of patients, all of whom were operated at the same time and in the same hospital district. No other selection criteria were used. Complications at the time of index operation, type of prosthesis, age, sex, BMI, patients diseases, medication, and surgeons experience were compared using conditional logistic regression. Results We found that low age at the time of the hip fracture operation increased the risk of periprosthetic fracture (OR = 4.9, CI = 1.2-20). The polished wedge type of prosthesis was associated with a higher risk of periprosthetic fracture than were other designs (OR = 11, CI = 1.2-97). Interpretation These findings of risk factors for peri-prosthetic fracture are new and should be confirmed by further studies using larger numbers of patients.

Comparison of extracapsular pseudotumors seen in magnetic resonance imaging and in revision surgery of 167 failed metal-on-metal hip replacements

Background and purpose — Magnetic resonance imaging (MRI) is important for detecting extracapsular pseudotumors, but there is little information on the accuracy of MRI and appropriate intervals for repeated imaging. We evaluated the sensitivity and specificity of MRI for detecting pseudotumors in 155 patients (167 hips) with metal-on-metal (MoM) hip arthroplasties that failed due to adverse reactions to metal debris (ARMD). Methods — Preoperative MRIs were performed with two 1.5 T MRI scanners and graded by a senior musculoskeletal radiologist using a previously described MRI pseudotumor grading system. Revision findings were retrieved from surgical notes, and pseudotumors were retrospectively graded as fluid-filled, mixed-type, or solid. Results — The sensitivity of MRI was 71% and the specificity was 87% for detecting extracapsular pseudotumors. The sensitivity was 88% (95% CI: 70–96) when MRI was performed less than 3 months before the revision surgery. Interestingly, when the time that elapsed between MRI and revision was more than 1 year, the sensitivity calculated was only 29% (95% CI: 14–56). Comparison between MRI and revision classifications gave moderate agreement (Cohen’s kappa = 0.4). Interpretation — A recent MRI predicts the presence of a pseudotumor well, but there is more discrepancy when the MRI examination is over a year old, most likely due to the formation of new pseudotumors. 1 year could be a justifiable limit for considering a new MRI if development of ARMD is suspected. MRI images over a year old should not be used in decision making or in planning of revision surgery for MoM hips.

Patient outcome following revision total knee arthroplasty: a meta-analysis

The purpose of this study was to summarize the literature describing patient outcome following revision total knee arthroplasty. Original studies were included if they were published between 1990 and 2002, enrolled ten or more patients, and measured patient outcome using a global knee rating scale. We found 33 studies with a total number of 1,356 patients. There were 429 men and 611 women with a mean age of 67 (45–90) years. The weighted mean follow-up time was 57 (6–108) months. The main indication of revision was loosening. The weighted mean preoperative and postoperative knee scores were 49 (15–82) and 84 (58–109) respectively. There were significant differences between preoperative and postoperative knee and function scores and motion (knee: t=12.507 p<0.001, function: t=4.704 p<0.001, motion: t=5.346 p<0.001). Loosening was also the main complication after revision surgery. In this analysis, revision total knee arthroplasty was a safe and effective procedure.RésuméLe but de cette étude était de résumer la littérature qui décrit les résultats après reprise d’arthroplastie totale du genou. Les études originales ont été incluses si elles avaient été publiés entre 1990 et 2002, avec dix malades au moins et l’utilisation d’une échelle d’appréciation globale du genou. Nous avons trouvé 33 études avec un nombre total de 1356 malades. Il y avait 429 hommes et 611 femmes avec un âge moyen de 67 (45–90) années. La moyenne pondéré de suivi était 57 (6–108) mois. La principale indication pour la révision était le descellement. Les scores moyens pondérés préopératoires et les scores postopératoires étaient 49 (15–82) et 84 (58–109) respectivement. Il y avait des différences significatives entre les scores du genou pré - et postopératoires, les scores fonctionnels et les scores d’amplitude (score du Genou: t=12.507 p<0.001, scores fonctionnels: t=4.704 p<0.001, scores d’amplitude: t=5.346 p<0.001). Le descellement était aussi la principale complication après la chirurgie de révision. La révision de l’arthroplastie totale du genou était une procédure sûre et efficace dans ces études.

Repeated magnetic resonance imaging in 154 hips with large-diameter metal-on-metal hip replacement

Background and purpose — The US Food and Drug Administration and the UK Medicines and Health Regulation Agency recommend using MRI in the evaluation of patients with large-diameter metal-on-metal (LD-MoM) hips. Such recommendations do not take into account the relevance of repeated cross-sectional imaging. We therefore investigated the natural course of pseudotumors in patients with LD-MoM hip replacements. Patients and methods — Of 888 ASR patients (1,036 hips) 674 patients (798 hips) underwent 2 follow-up visits at our institution. Of these, we identified 124 patients (154 hips) who had undergone repeated clinical assessment including MRI and whole-blood metal ion assessment. Results — A change in classification in imaging findings between the 2 MRIs was seen in 17 of the 154 hips (11%). In 13 hips (8%), a significant progression of the pseudotumor was evident, while in 4 (3 %) there was a retrogressive change. 10 of these 13 hips had had a normal first MRI. Patients with a progressive change in the scans did not differ significantly from those without a change in MRI classification regarding follow-up time, time interval between MRIs, or changes in whole-blood Cr and Co levels between assessments. Interpretation — A change in classification was rare, considering that all patients had a clinical indication for repeated imaging. Progression of the findings did not appear to correlate clearly with symptoms or whole-blood metal values.

Revision total knee arthroplasty with the Total Condylar III system: A comparative analysis of 71 consecutive cases of osteoarthritis or inflammatory arthritis

Background As revision total knee arthroplasty surgery is becoming more common, it is necessary to evaluate how individual revision prosthesis systems perform in degenerative and inflammatory arthritides. In this study, results of the use of the Total Condylar III (TC III) system in osteoarthritis (55 knees) were compared to results of its use in inflammatory arthritis (16). Methods Patients were followed radiographically for 5.9 (3.0–10.2) years and clinically for 3.0 (0.2–6.8) years, using re-revision as the endpoint. Results At 1 year after revision and at final follow-up, the total Knee Society knee score, function score and range of motion had improved (p < 0.001) with no differences between osteoarthritis and inflammatory arthritis. No knee had definite component loosening, although 23 knees had asymptomatic radiolucent lines. Complications comprised 4 infections, 1 patellar pain syndrome and 1 rupture of the patellar tendon. Using any re-revi-sion of the prosthesis as the endpoint, 5-year survival was 95% and 8-year survival was 94%. Interpretation Concentration of demanding revision knee arthroplasties to a few hands led to good or excellent knee joint knee score results in four-fifths of the patients, and showed good outcome with the TCIII system. In spite of ligamentous laxity, propensity to develop infections, bone destruction and poor general health, patients with inflammatory arthritis had results similar to those with osteoarthritis.

Good sensitivity and specificity of ultrasound for detecting pseudotumors in 83 failed metal-on-metal hip replacements

Background and purpose — Ultrasound is used for imaging of pseudotumors associated with metal-on-metal (MoM) hips. Ultrasound has been compared with magnetic resonance imaging, but to date there have been no studies comparing ultrasound findings and revision findings. Methods — We evaluated the sensitivity and specificity of preoperative ultrasound for detecting pseudotumors in 82 patients with MoM hip replacement (82 hips). Ultrasound examinations were performed by 1 of 3 musculoskeletal radiologists, and pseudotumors seen by ultrasound were retrospectively classified as fluid-filled, mixed-type, or solid. Findings at revision surgery were retrieved from surgical notes and graded according to the same system as used for ultrasound findings. Results — Ultrasound had a sensitivity of 83% (95% CI: 63–93) and a specificity of 92% (CI: 82–96) for detecting trochanteric region pseudotumors, and a sensitivity of 79% (CI: 62–89) and a specificity of 94% (CI: 83–98) for detecting iliopsoas-region pseudotumors. Type misclassification of pseudotumors found at revision occurred in 8 of 23 hips in the trochanteric region and in 19 of 33 hips in the iliopsoas region. Interpretation — Despite the discrepancy in type classification between ultrasound and revision findings, the presence of pseudotumors was predicted well with ultrasound in our cohort of failed MoM hip replacements.

Glass-ceramic-coated titanium hip endoprosthesis

Titanium alloy hip endoprostheses coated with a bioactive glass ceramic (BGC) were followed in rabbits. All test endoprostheses remained stable, and image analysis showed an average of 78% bonding of the BGC-coated implants to bone at 52 weeks. The uncoated Ti-alloy controls demonstrated an average of 37% bone coverage after 52 weeks. By scanning electron microscopy the thickness of the BGC reaction layer was found to stabilize at 60 μm after bioactive bone bonding. The results indicate that the BGC coating must be thicker than the reaction layer to prevent detachment from the core metal.