Introduction

The optimal management of severe tibial and/or femoral bone loss in a revision total knee arthroplasty (TKA) has not been established. Reconstructive methods include structural or bulk allografts, impaction bone-grafting with or without mesh augmentation, custum prosthetic components, modular metal augmentations of prosthesis and tumor prosthesis. Recently metaphyseal fixation using porous tantalum cones (Zimmer, Warsaw, IN) has been proposed as alternative strategy for severe bone loss.

Introduction

The use of antibiotic-loaded polymethylmethacrylate bone-cement spacers during two-stage exchange procedures is the standard in the treatment of patients with delayed prosthetic joint infection. The real antimicrobial activity of these spacers is unclear because the adherence of bacteria to cement might result in clinical recurrence of infection. The purpose of the study is to evaluate the in vitro formation of Pseudomonas Aeruginosa (PA) and Staphylococcus spp. biofilm on antibiotic-loaded bone cement.

High-dose antibiotic-loaded acrylic cement (ALAC) is used for managing periprosthetic joint infections (PJIs). The marked increase in resistant high-virulence bacteria is drawing the attention of physicians towards alternative antimicrobial formulations to the routinely used antibiotics. To date, few studies simultaneously investigated the elution properties of a broad range of antibiotics. The aim of thepresent in-vitrostudy was to determine the elution kinetics of 14 different high-dose ALACs.

All the ALAC samples showed a burst release of antibiotics in the first hour, progressively decreasing overtime, and elution curves strictly adhered to a non-linear regression analysis formula. Among aminoglycosides, commonly addressed as the most appropriate antibiotics to be loaded into the bone cement, the highest elution rate was that of tobramycin. Among the glycopeptides, commonly used to treat PJIs because of the prevalence of aminoglycoside resistance, vancomycin showed better elution in comparison with teicoplanin. Clindamycin, that can be associated with aminoglycosides to prepare ALACsshowed the highest absolute and relative elutions among all the tested formulations. A noticeable elution was also detected for colistin, an antibiotic of last resort for treating multi-drug resistant bacteria.

The current study demonstrates theoretical advantages in the preparation of ALAC for some antibiotics notroutinely used in the clinical setting for PJIs. The use of these antibiotics based on the infecting bacteria sensitivity may represent an useful option for physicians to eradicate PJIs. In vivo testing should be considered in the future to confirm the results of this study.

BACKGROUND:

Few studies have evaluated at a medium-term follow-up the use of semiconstrained reverse shoulder arthroplasty (RSA) for primary glenohumeral osteoarthritis, massive rotator cuff tear, or cuff tear arthropathy excluding any other shoulder disease. Moreover, data on patients' quality of life after this surgery are lacking.

BACKGROUND:

Modern total hip arthroplasty (THA) has shown a great improvement in pain, function and range of motion of patients but data on patients' quality of life after this surgery as assessed by validated tools are lacking.

The removal of cement debris at the time of primary and revision joint replacement has been facilitated through the introduction of coloured bone cements. Up to date, few studies have evaluated the effect of methilene blue dye on physical, mechanical and pharmacological properties of cements. In this light, we evaluated the effects of adding methylene blue to bone cement with or without antibiotics (gentamicin, vancomycin or both). The addition of methylene blue to plain cement significantly decreased its mean compression (95.4±3 MPa vs 100.1±6 MPa, p = 0.03) and bending (65.2±5 MPa vs 76.6±4 MPa, p < 0.001) strengths, mean setting time (570±4 seconds vs 775±11 seconds, p = 0.01), as well as its mean elastic modulus (2744±97 MPa vs 3281±110 MPa, p < 0.001). Bending resistance decreases after the supplementation of the coloured cement with vancomycin and gentamicin (55.7±4 MPa vs 65.2±5 MPa, p < 0.001). The release of antibiotics from the bone cement was significantly decreased by the methylene blue. Indeed, the release of gentamicin alone was 385.5±26 μg in comparison to 228.2±24 μg when the methylene blue was added (p < 0.001), while the release of gentamicin in combination with vancomycin was 613±25 μg vs 498.5±70 μg (p = 0.018) when the dye was added to the same formulation. With this study we demonstrated several theoretical disadvantages of the antibiotic-loaded bone cement coloured with methylene blue, although caution should be exercised in transferring our findings to the clinical context. Based on our findings, we do not recommend methylene blue supplementation of PMMA for routine clinical use.

The purposes of the present study were to assess the outcome of surgery for carpal tunnel syndrome (CTS), to evaluate histological findings of subsynovial connective tissue (SSCT) of patients with CTS in comparison with a control group, and to assess whether the histologic appearance of the flexor tenosynovium is correlated with clinical history, preoperative or postoperative physical examination, general health, symptoms and function as assessed by validated tools, or nerve conduction studies.

Materials and Methods: We studied 30 consecutive patients who had idiopathic CTS and were referred to our institution for surgery. All patients had had diagnostic neurophysiological testing. A study specific questionnaire, a historical-objective scale (Hi-Ob), the Boston Carpal Tunnel Questionnaire (BCTQ), the SF-36 questionnaire were administered to the patients preoperatively and six months after surgery. A standard open carpal tunnel release was performed and 1 cm 3 of tickened synovium was removed from the flexor digitorum superficialis tendons. Specimens of SSCT from flexor tendon at wrist were also obtained from ten fresh-frozen cadavers witrh no history of CTS. Seriated hematoxylin and eosin stained sections were obtained and conventional light microscopy at a magnification of 20X was performed. The number of cells, the number of vessels, the surface of the lumen of the vessels, the total vascular surface, the thickness of the wall of vessels in each selected image were measured with an Autocad software. The results per specimen were averaged for statistical analysis.

Results: Six months after surgery the SF-36 mental and physical summary scores (P< 0.001 and P=0.001, respectively), the Symptom severity score (P< 0.001) and the HI-Ob (P< 0.001) improved. In comparison with cadavers, the typical pathologic findings of SSCT of patients with CTS were vascular hypertrophy and vessel’s wall thickening. At multivariate linear regression analyses greater histopathological changes were important predictor of lower SF-36 scores following surgery. As for the electromyographic parameters, higher preoperative values of 3M SCV and MCV were positively associated with SF-36 BP and SF scores. The greater neurophysiological impairment of the median nerve was predictive of lower SF-36 VT at follow up. Older patients, females and patients who had had the higher number or severity of comorbidities preoperatively achieved the lower SF-36 scores following surgery.

Conclusions: We demonstrated many variables to be associated with the CTS and its surgical treatments thus confirming data from previous reports and suggesting new important associations that have not been described previously. Physicians should consider these results when discussing with patients on the likely outcomes of carpal tunnel surgery.

No studies have focused on the relationships between pathological changes in the subsynovial connective tissue and clinical or neurophysiological findings in patients suffering from carpal tunnel syndrome (CTS). Twenty-five consecutive patients (mean age 58.8±10 years; range 39–79) operated on for idiopathic CTS were evaluated before surgery and six month later. The indication for surgery was the presence of symptoms despite a three-month trial of conservative management. Mean duration of symptoms was 5.3±4.6 years (range 0.5–15). On admission, demographic and medical history data were recorded from all the patients. Subsequently, patients underwent preoperative physical examination and an outcome set including a mixed historic and objective scale (Hi-Ob), the Italian version of the Boston Carpal Tunnel Questionnaire (BCTQ) and the official Italian version of the SF-36 questionnaire was administered. The baseline diagnostic work-up included standard radiographs of the hand and wrist, blood examination and neurophysiological testing. Patients underwent open carpal tunnel release and thickened synovium from the flexor digitorum superficialis tendons was harvested. The number of cells, the number, diameter and density of the vessels, and the total surface of angiogenetic foci were measured. On the SF-36 questionnaire, the preoperative physical component summary (PCS) and mental component summary (MCS) scores averaged 36.5±4.2 and 40.8±5.7, respectively; at follow they averaged 47±10.2 and 46.8±7.3, respectively, with significant improvement for PCS. Preoperative and postoperative Hi-Ob scores measured 3.4±0.5 and 1.3±0.5, respectively. The BCTQ symptoms scale averaged 3.9±0.3 before surgery and 1.5±0.2 at follow up, whereas the BCQT functional status scale measured 3.4±0.5 at baseline and 1.4±0.3 six months after the operation. Univariate and multiple linear regression analysis were used to evaluate relationships between explanatory variables and outcomes. A high grade of preoperative neurophysiologic impairment was in direct relationship with the improvement in SF-36’s PCS score obtained with surgery (p=0.017). Conversely, no association was detected between neurophysiological grade and the postoperative improvement in Hi-Ob or BCQT scales. The univariate analysis showed a trend toward a direct association between number of vessels in the synovium and the improvement of BCTQ symptoms at follow-up (p=0.06). This trend was confirmed to a lesser extent at the multivariate analysis. With the numbers available, no other histological parameters were associated with the baseline neurophysiological findings or clinical outcomes. Although our results should be interpreted cautiously due to the small sample size, we conclude that the severity of pathological changes in the flexor synovium during CTS do not influence the baseline severity or outcome of this syndrome.