Tibial tunnel enlargement is affected by the tunnel diameter-screw ratio in tibial hybrid fixation for hamstring ACL reconstruction.

INTRODUCTION: There is no evidence on screw diameter with regards to tunnel size in anterior cruciate ligament reconstruction (ACLR) using hybrid fixation devices. The hypothesis was that an undersized tunnel coverage by the tibial screw leads to subsequent tunnel enlargement in ACLR in hybrid fixation technique. METHODS: In a retrospective case series, radiographs and clinical scores of 103 patients who underwent primary hamstring tendon ACLR with a hybrid fixation technique at the tibial site (interference screw and suspensory fixation) were obtained. Tunnel diameters in the frontal and sagittal planes were measured on radiographs 6 weeks and 12 months postoperatively. Tunnel enlargement of more than 10% between the two periods was defined as tunnel widening. Tunnel coverage ratio was calculated as the tunnel diameter covered by the screw in percentage. RESULTS: Overall, tunnel widening 12 months postoperatively was 23.1 ± 17.1% and 24.2 ± 18.2% in the frontal and sagittal plane, respectively. Linear regression analysis revealed the tunnel coverage ratio to be a negative predicting risk factor for tunnel widening (p = 0.001). The ROC curve analysis provided an ideal cut-off for tunnel enlargement of > 10% at a tunnel coverage ratio of 70% (sensitivity 60%, specificity 81%, AUC 75%, p < 0.001). Patients (n = 53/103) with a tunnel coverage ratio of < 70% showed significantly higher tibial tunnel enlargement of 15% in the frontal and sagittal planes. The binary logistic regression showed a significant OR of 6.9 (p = 0.02) for tunnel widening > 10% in the frontal plane if the tunnel coverage ratio was < 70% (sagittal plane: OR 14.7, p = 0.001). Clinical scores did not correlate to tunnel widening. CONCLUSION: Tibial tunnel widening was affected by the tunnel diameter coverage ratio. To minimize the likelihood of disadvantageous tunnel expansion-which is of importance in case of revision surgery-an interference screw should not undercut the tunnel diameter by more than 1 mm.

Cathodic Voltage-controlled Electrical Stimulation Plus Prolonged Vancomycin Reduce Bacterial Burden of a Titanium Implant-associated Infection in a Rodent Model.

BACKGROUND: Cathodic voltage-controlled electrical stimulation (CVCES) of titanium implants, either alone or combined with a short course of vancomycin, has previously been shown to reduce the bone and implant bacterial burden in a rodent model of methicillin-resistant Staphylococcus aureus (MRSA) implant-associated infection (IAI). Clinically, the goal is to achieve complete eradication of the IAI; therefore, the rationale for the present study was to evaluate the antimicrobial effects of combining CVCES with prolonged antibiotic therapy with the goal of decreasing the colony-forming units (CFUs) to undetectable levels. QUESTIONS/PURPOSES: (1) In an animal MRSA IAI model, does combining CVCES with prolonged vancomycin therapy decrease bacteria burden on the implant and surrounding bone to undetectable levels? (2) When used with prolonged vancomycin therapy, are two CVCES treatments more effective than one? (3) What are the longer term histologic effects (inflammation and granulation tissue) of CVCES on the surrounding tissue? METHODS: Twenty adult male Long-Evans rats with surgically placed shoulder titanium implants were infected with a clinical strain of MRSA (NRS70). One week after infection, the rats were randomly divided into four groups of five: (1) VANCO: only vancomycin treatment (150 mg/kg, subcutaneous, twice daily for 5 weeks); (2) VANCO + 1STIM: vancomycin treatment (same as the VANCO group) coupled with one CVCES treatment (-1.8 V for 1 hour on postoperative day [POD] 7); (3) VANCO + 2STIM: vancomycin treatment (same as the VANCO group) coupled with two CVCES treatments (-1.8 V for 1 hour on POD 7 and POD 21); or (4) CONT: no treatment. On POD 42, the implant, bone, and peripheral blood were collected for CFU enumeration and histological analysis, where we compared CFU/mL on the implants and bone among the groups. A pathologist, blinded to the experimental conditions, performed a semiquantitative analysis of inflammation and granulation tissue present in serial sections of the humeral head for animals in each experimental group. RESULTS: The VANCO + 1STIM decreased the implant bacterial burden (median = 0, range = 0-10 CFU/mL) when compared with CONT (median = 5.7 × 10(4), range = 4.0 × 10(3)-8.0 × 10(5) CFU/mL; difference of medians = -5.6 × 10(4); p < 0.001) and VANCO (median = 4.9 × 10(3), range = 9.0 × 10(2)-2.1 × 10(4) CFU/mL; difference of medians = -4.9 × 10(3); p < 0.001). The VANCO + 1STIM decreased the bone bacterial burden (median = 0, range = 0-0 CFU/mL) when compared with CONT (median = 1.3 × 10(2), range = 0-9.4 × 10(2) CFU/mL; difference of medians = -1.3 × 10(2); p < 0.001) but was not different from VANCO (median = 0, range = 0-1.3 × 10(2) CFU/mL; difference of medians = 0; p = 0.210). The VANCO + 2STIM group had implant CFU (median = 0, range = 0-8.0 × 10(1) CFU/mL) and bone CFU (median = 0, range = 0-2.0 × 10(1) CFU/mL) that were not different from the VANCO + 1STIM treatment group implant CFU (median = 0, range = 0-10 CFU/mL; difference of medians = 0; p = 0.334) and bone CFU (median = 0, range = 0-0 CFU/mL; difference of medians = 0; p = 0.473). The histological analysis showed no deleterious effects on the surrounding tissue as a result of the treatments. CONCLUSIONS: Using CVCES in combination with prolonged vancomycin resulted in decreased MRSA bacterial burden, and it may be beneficial in treating biofilm-related implant infections. CLINICAL RELEVANCE: CVCES combined with clinically relevant lengths of vancomycin therapy may be a treatment option for IAI and allow for component retention in certain clinical scenarios. However, more animal research and human trials confirming the efficacy of this approach are needed before such a clinical recommendation could be made.

Cathodic Electrical Stimulation Combined With Vancomycin Enhances Treatment of Methicillin-resistant Staphylococcus aureus Implant-associated Infections.

BACKGROUND: Effective treatments for implant-associated infections are often lacking. Cathodic voltage-controlled electrical stimulation has shown potential as a treatment of implant-associated infections of methicillin-resistant Staphylococcus aureus (MRSA). QUESTIONS/PURPOSES: The primary purpose of this study was to (1) determine if cathodic voltage-controlled electrical stimulation combined with vancomycin therapy is more effective at reducing the MRSA bacterial burden on the implant, bone, and synovial fluid in comparison to either treatment alone or no treatment controls. We also sought to (2) evaluate the histologic effects of the various treatments on the surrounding bone; and to (3) determine if the cathodic voltage-controlled electrical stimulation treatment had an effect on the mechanical properties of the titanium implant as a result of possible hydrogen embrittlement. METHODS: Thirty-two adult male Long-Evans rats (Harlan Laboratories, Indianapolis, IN, USA) with surgically placed shoulder titanium implants were infected with a clinical strain of MRSA (NRS70). One week after infection, eight animals received a treatment of cathodic voltage-controlled electrical stimulation at -1.8 V versus Ag/AgCl for 1 hour (STIM), eight received vancomycin twice daily for 1 week (VANCO), eight received the cathodic voltage-controlled electrical stimulation and vancomycin therapy combined (STIM + VANCO), and eight served as controls with no treatment (CONT). Two weeks after initial infection, the implant, bone, and synovial fluid were collected for colony-forming unit (CFU) enumeration, qualitative histological analysis by a pathologist blinded to the treatments each animal received, and implant three-point bend testing. RESULTS: The implant-associated CFU enumerated from the STIM + VANCO (mean, 3.7 × 10(3); SD, 6.3 × 10(3)) group were less than those from the CONT (mean, 1.3 × 10(6); SD, 2.8 × 10(6); 95% confidence interval [CI] of difference, -4.3 × 10(5) to -9.9 × 10(3); p < 0.001), STIM (mean, 1.4 × 10(6); SD, 2.0 × 10(6); 95% CI of difference, -2.1 × 10(6) to -1.8 × 10(3); p = 0.002), and VANCO (mean, 5.8 x 10(4); SD, 5.7 × 10(4); 95% CI of difference, -6.4 × 10(4) to -1.7 × 10(4); p < 0.001) group. The bone-associated CFU enumerated from the STIM + VANCO group (6.3 × 10(1); SD, 1.1 × 10(2)) were less than those from the CONT (mean, 2.8 × 10(5); SD, 4.8 × 10(5); 95% CI of difference, -9.4 × 10(4) to -5.0 × 10(3); p < 0.001) and STIM (mean, 2.6 × 10(4); SD, 2.5 × 10(4); 95% CI of difference, -4.1 × 10(4) to -1.6 × 10(3); p < 0.001) groups. The VANCO group (4.3 × 10(5); SD, 6.3 × 10(2)) also had lower bone-associated CFU as compared with the CONT (mean 95% CI of difference, -9.3 × 10(4) to -4.5 × 10(3); p < 0.001) and STIM (95% CI of difference, -4.0 × 10(4) to -1.5 × 10(3); p < 0.001) groups. In comparison to the synovial fluid CFU enumerated from the CONT group (mean, 3.3 × 10(4); SD, 6.0 × 10(4)), lower synovial CFU were reported for both the STIM + VANCO group (mean, 4.6 × 10(1); SD, 1.2 × 10(2); 95% CI of difference, -4.9 × 10(3) to -3.0 × 10(2); p < 0.001) and the VANCO group (mean, 6.8 × 10(1); SD, 9.2 × 10(1); 95% CI of difference, -4.9 × 10(3) to -2.8 × 10(2); p = 0.007). The histological analysis showed no discernable deleterious effects on the surrounding tissue as a result of the treatments. No brittle fracture occurred during mechanical testing and with the numbers available, no differences in implant flexural yield strength were detected between the groups. CONCLUSIONS: In this rodent model, cathodic voltage-controlled electrical stimulation combined with vancomycin is an effective treatment for titanium implant-associated infections showing greater than 99.8% reduction in bacterial burden on the implant, surrounding bone, and synovial fluid as compared with the controls and the stimulation alone groups. CLINICAL RELEVANCE: Cathodic voltage-controlled electrical stimulation combined with vancomycin may enable successful treatment of titanium orthopaedic implant-associated infections with implant retention. Future studies will focus on optimization of the stimulation parameters for complete eradication of infection and the ability to promote beneficial host tissue responses.

Surgical Outcomes and Analysis of Quality of Life Following Knee Arthroplasty in Very Elderly Patients.

In an aging population, the incidence of severe knee osteoarthritis in very elderly patients increases, leading to functional impairment and loss of independence. Knee replacement could be an effective treatment but is often denied due to fear of increased complication rate with advanced age. The objective of this study was to investigate complication rate, mortality, clinical outcome, and quality-adjusted life years (QALYs) of primary knee replacement in very elderly patients, defined as 83 years or older. Medical records of 85 cases, receiving a primary total (total knee arthroplasty [TKA]) or unicompartmental (unicompartmental knee arthroplasty [UKA]) knee replacement, aged 83 years or older at the time of surgery, were retrospectively reviewed for surgical and medical complications as well as survivorship. Functional outcome was obtained by Oxford Knee Score (OKS) and QALY. At a mean follow-up of 21 months (TKA) and 24 months (UKA), surgical and medical complication rates were 9.7 and 8.1% for TKA and 4.3 and 4.3% for UKA, respectively. One-year survival rate was 98.4% in TKA and 98.8% in UKA, the 5-year survival rate was 83.1 and 86.6%, respectively. OKS improved from 19 to 41 points in TKA and 23 to 40 points in UKA. Mean QALYs were 4.1 years for TKA and 3.9 years for UKA. TKA and UKA are safe and reliable surgical procedures in treating end-stage osteoarthritis in very elderly patients. Patients might benefit from improved pain, function, and quality of life. The mortality rate and overall complication rate were low, although slightly higher than reported in cohorts with younger patients. If the patient is suitable, UKA might be preferred over TKA, as the complication rate was significantly lower. Patients should not be excluded from knee replacement based on their age alone, but careful patient selection, peri- and postoperative optimization, and awareness for complications are quintessential for successful treatment.

Effect of the Reversed L-Shaped Osteotomy on the Round Sign: Not All Hallux Valgus Deformities May Need Proximal Derotation to Correct the Radiographic Appearance of Metatarsal Pronation.

Background: Metatarsal pronation has been claimed to be a risk factor for hallux valgus recurrence. A rounded shape of the lateral aspect of the first metatarsal head has been identified as a sign of persistent metatarsal pronation after hallux valgus correction. This study investigated the derotational effect of a reversed L-shaped (ReveL) osteotomy combined with a lateral release to correct metatarsal pronation. The primary hypothesis was that most cases showing a positive round sign are corrected by rebalancing the metatarsal-sesamoid complex. We further assumed that the inability to correct the round sign might be a risk factor for hallux valgus recurrence. Methods: We retrospectively evaluated 266 cases treated with a ReveL osteotomy for hallux valgus deformity. The radiologic measurements were performed on weightbearing foot radiographs preoperatively, at an early follow-up (median, 6.2 weeks), and the most recent follow-up (median, 13 months). Univariate and multivariate logistic regression analyses identified risk factors for hallux valgus recurrence (hallux valgus angle [HVA] ≥ 20 degrees). Results: A preoperative positive radiographic round sign was present in 40.2% of the cases, of which 58.9% turned negative after the ReveL osteotomy (P < .001). Hallux valgus recurred in 8.6%. Risk factors for recurrence were a preoperative HVA >30 degrees (odds ratio [OR] = 5.3, P < .001), metatarsus adductus (OR = 4.0, P = .004), preoperative positive round sign (OR = 3.3, P = .02), postoperative HVA >15 degrees (OR = 74.9; P < .001), and postoperative positive round sign (OR = 5.3, P = .008). Cases with a positive round sign at the most recent follow-up had a significantly higher recurrence rate than those with a negative round sign (22.7% vs 5.9%, P < .001). Conclusion: The ReveL osteotomy corrected a positive round sign in 58.9%, suggesting that not all hallux valgus deformities may need proximal derotation to negate the radiographic appearance of the round sign. A positive round sign was found to be an independent risk factor for hallux valgus recurrence. Further 3-dimensional analyses are necessary to better understand the effects and limitations of distal translational osteotomies to correct metatarsal pronation. Level of Evidence: Level IV, case series.

Magnesium alloy AZ91 exhibits antimicrobial properties in vitro but not in vivo.

Magnesium alloys hold great promise for developing orthopedic implants that are biocompatible, biodegradable, and mechanically similar to bone tissue. This study evaluated the in vitro and in vivo antimicrobial properties of magnesium-9%aluminum-1%zinc (AZ91) and commercially pure titanium (cpTi) against Acinetobacter baumannii (Ab307). The in vitro results showed that as compared to cpTi, incubation with AZ91 significantly reduced both the planktonic (cpTi = 3.45e8, AZ91 = 8.97e7, p < 0.001) colony forming units (CFU) and biofilm-associated (cpTi = 3.89e8, AZ91 = 1.78e7, p = 0.01) CFU of Ab307. However, in vivo results showed no significant differences in the CFU enumerated from the cpTi and AZ91 implants following a 1-week implantation in an established rodent model of Ab307 implant associated infection (cpTi = 5.23e3, AZ91 = 2.46e3, p = 0.29). It is proposed that the in vitro results were associated with an increased pH in the bacterial culture as a result of the AZ91 corrosion process. The robust in vivo buffering capacity likely diminished this corrosion associated pH antimicrobial effect. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 221-227, 2018.

How do leg press exercises comply with limited weight bearing?

OBJECTIVES: To investigate foot loadings in different leg press settings with respect to a possible graduation of weight bearing (WB). DESIGN: Case series. SETTINGS: Assessing plantar force values by means of dynamic pedobarography taken place in orthopaedic departments' rehab center. PARTICIPANTS: 15 healthy students (9 men and 6 women, age 23 ± 2, weight 75 ± 6 kg) were recruited as participants from the medical faculty. MAIN OUTCOME MEASURES: Peak force values from normal gait (referred to as 100%) and single and double leg presses (SLP, DLP) with resistances of 10 kg, 20 kg and 40 kg, obtained with pedobarographic insoles. RESULTS: Performing DLP produced foot loadings (N) of 37 ± 15 with 10 kg, 91 ± 29 with 20 kg and 203 ± 27 with 40 kg, equal to 5%, 12% and 26% of full WB. SLP result in force values of 195 ± 32 with 10 kg, 308 ± 34 with 20 kg and 516 ± 45 with 40 kg, corresponding to 25%, 40% and 67% baseline. CONCLUSIONS: Leg press exercises can be performed in accordance with a given limitation of foot loading. Above mentioned conditions allow a graduation from 5% to 67% of full WB.

Cathodic voltage-controlled electrical stimulation of titanium implants as treatment for methicillin-resistant Staphylococcus aureus periprosthetic infections.

Effective treatment options are often limited for implant-associated orthopedic infections. In this study we evaluated the antimicrobial effects of applying cathodic voltage-controlled electrical stimulation (CVCES) of -1.8 V (vs. Ag/AgCl) to commercially pure titanium (cpTi) substrates with preformed biofilm-like structures of methicillin-resistant Staphylococcus aureus (MRSA). The in vitro studies showed that as compared to the open circuit potential (OCP) conditions, CVCES of -1.8 V for 1 h significantly reduced the colony-forming units (CFU) of MRSA enumerated from the cpTi by 97% (1.89 × 106 vs 6.45 × 104 CFU/ml) and from the surrounding solution by 92% (6.63 × 105 vs. 5.15 × 104 CFU/ml). The in vivo studies, utilizing a rodent periprosthetic infection model, showed that as compared to the OCP conditions, CVCES at -1.8 V for 1 h significantly reduced MRSA CFUs in the bone tissue by 87% (1.15 × 105 vs. 1.48 × 104 CFU/ml) and reduced CFU on the cpTi implant by 98% (5.48 × 104 vs 1.16 × 103 CFU/ml). The stimulation was not associated with histological changes in the host tissue surrounding the implant. As compared to the OCP conditions, the -1.8 V stimulation significantly increased the interfacial capacitance (18.93 vs. 98.25 µF/cm(2)) and decreased polarization resistance (868,250 vs. 108 Ω-cm(2)) of the cpTi. The antimicrobial effects are thought to be associated with these voltage-dependent electrochemical surface properties of the cpTi.

Inhibition of spontaneous breast cancer metastasis by anti-Thomsen-Friedenreich antigen monoclonal antibody JAA-F11.

Thomsen-Friedenreich antigen (TF-Ag) is expressed in many carcinomas, including those of the breast, colon, bladder, and prostate. TF-Ag is important in adhesion and metastasis and as a potential immunotherapy target. We hypothesized that passive transfer of JAA-F11, an anti-TF-Ag monoclonal antibody, may create a survival advantage for patients with TF-Ag-expressing tumors by cytotoxicity, blocking of tumor cell adhesion, and inhibition of metastasis. This was tested using in vitro models of tumor cell growth; cytotoxicity assays; in vitro, ex vivo, and in vivo models of cancer metastasis; and, finally, in vivo effects in mice with metastatic breast cancer. Unlike some anti-TF-Ag antibodies, JAA-F11 did not enhance breast carcinoma cell growth. JAA-F11 did not induce the killing of 4T1 tumor cells through complement-dependent cytotoxicity or apoptotic mechanisms. However, JAA-F11 blocked the stages of metastasis that involve the adhesion of human breast carcinoma cells to human endothelial cells (human umbilical vein endothelial cells and human bone marrow endothelial cells 60) in in vitro static adhesion models, in a perfused ex vivo model, and in murine lung vasculature in an in vivo metastatic deposit formation assay. JAA-F11 significantly extended the median survival time of animals bearing metastatic 4T1 breast tumors and caused a > 50% inhibition of lung metastasis.

Chorea and rapidly progressive subcortical dementia in antiphospholipid syndrome.

Antiphospholipid antibodies are associated with a variety of neurologic manifestations, both in patients with and without concomitant systemic lupus erythematosus. We report a patient in whom chorea and rapidly progressive subcortical dementia developed in the setting of persistently high titers of antiphospholipid antibodies. While some manifestations of antiphospholipid syndrome can be clearly linked to vascular thrombosis, it is not known whether this is also true for patients affected with chorea, dementia, or both. In our patient, serial magnetic resonance imaging showed the progressive development of deep white matter lesions but no cortical infarcts. The development of widespread pulmonary arterial thrombosis and acute cerebral ischemia, evidenced clinically and on diffusion-weighted magnetic resonance imaging of the brain, provided indirect evidence for a thrombotic pathogenesis for this patient's neurologic disease. Anticoagulation should be considered as an adjunct to the treatment of patients with antiphospholipid antibodies and chorea or subcortical dementia.