Perioperative Considerations for Use of Custom Metallic Implants in Limb Reconstruction

SUMMARY

The surgical management of critical bone defects remains challenging. Regardless of whether bone loss is acute or the result of staged surgical resection, current surgical management often requires advanced reconstructive techniques, many of which require multiple surgical procedures and consistent patient involvement with applied internal or external orthopaedic devices. The utilization of three-dimensional (3D) printing technology has continued to expand across orthopaedic subspecialties; in orthopaedic trauma, custom metallic implants are being used in the management of critical bone defects. Implementation of this technique may be advantageous in certain clinical situations. The perioperative considerations for placement of a custom bone defect printed metallic implant are presented in conjunction with demonstrative clinical cases.

Systemic Absorption Resulting from Tobramycin-Loaded Antibiotic Cement Spacers Used in the Treatment of Prosthetic Joint Infection

Purpose

Antimicrobial cement spacer (ACS) placement has been a cornerstone of two-stage management of prosthetic hip and knee infection. Pharmacokinetic modelling has described peak systemic antibiotic concentrations within the first 24-48 h post-operatively, followed by rapid clearance. A few studies have, however, identified detectable tobramycin levels in patients with a post-operative decline in creatinine clearance. Our study sought to determine how frequently detectable serum tobramycin levels occurred within the first 72 h following ACS placement in all patients regardless of baseline or subsequent changes in renal function, whether these levels correlated with tobramycin spacer dosage, creatinine clearance, or potential nephrotoxicity risk factors, and whether any patients developed acute kidney injury within the 14-day post-operative period.

Methods

We prospectively enrolled patients with prosthetic hip or knee infections and subsequent ACS placement from October 2017 to February 2020. Patient comorbidities (chronic kidney disease, diabetes mellitus, chronic liver disease, chronic obstructive pulmonary disease, and atrial fibrillation), Charleston Comorbidity Index score, risk factors for post-operative nephrotoxicity (perioperative hypotension and nephrotoxic agent receipt), total tobramycin dosage, post-operative days 1 and 3 serum tobramycin concentrations, and serum creatinine and creatinine clearance throughout a 14-day post-operative period were recorded.

Results

A total of 20 patients were enrolled, comprising 20 spacers with a median total tobramycin dosage of 4.80 g with an interquartile range (IQR) of 4.13-7.20 g. Thirteen patients had a median detectable post-operative day 1 serum tobramycin concentration of 0.80 (IQR 0.50-1.60) mcg/mL. Five of these 13 patients had a median detectable post-operative day 3 serum tobramycin concentration of 0.80 (IQR 0.50-1.10) mcg/mL. A correlation was not found between serum tobramycin drug levels and patient comorbidities, receipt of nephrotoxic medications, or baseline and subsequent post-operative creatinine clearance up to day 14.

Conclusion

The majority of patients who underwent tobramycin ACS placement had detectable serum tobramycin levels in the immediate post-operative period, but most reached undetectable levels within 72 h. There were no reliable perioperative predictors of detectable drug levels.

Management of Midfoot Fractures and Dislocations

PURPOSE OF REVIEW

To outline the classic and recent literature of midfoot fractures and dislocations.

RECENT FINDINGS

There has been an evolution of implant technology to include mini-fragment fixation, suture fixation, and staples. Their efficacy is still being elucidated in the literature. Also, there has been a recent push for primary fusion, which we will discuss. Open reduction internal fixation of the midfoot remains to be the gold standard treatment, to which all other treatments are compared. It remains to be seen if adjunct fixation techniques are efficacious enough to provide a good result. Further study is needed to determine which patients are likely to progress to debilitating arthrosis and require fusion.

Coronary artery disease and cerebrovascular disease prevention in diabetes mellitus: early identification and aggressive modification of risk factors

Risk factor modification for CVD is an established, effective strategy in patient care. Risk stratification is used to set treatment goals. Lifestyle modification and supplemental pharmacologic therapy are used to accomplish the goals. Patients with DM start with one risk factor, often have additional risk factors, and have higher rates of existing CVD. Vigilance is required in identifying risk factors and persistence in management is often necessary to successfully modify the important risk factors.

Self-awareness, alcohol consumption, and reduced cardiovascular reactivity

Seventy-two healthy males were divided into Type A and Type B groups using the Jenkins Activity Survey. Subjects were subdivided further into high and low self-awareness categories on the private self-consciousness factor of the Self-Consciousness Scale. After random assignment to consume alcohol (0.85 g/kg) or a placebo, subjects were exposed to four stressors presented at random: a self-disclosing speech, aversive noise, insoluble anagrams, and mental arithmetic. Blood pressure, heart rate, and finger pulse amplitude were monitored throughout. Among the major findings was increased systolic blood pressure (SBP) reactivity during the speech among Type As low in private self-consciousness. Alcohol dampened autonomic responsiveness only in this group. When self-involvement was measured as the ratio of first-person pronouns to total words spoken during the speech, sober Type As displayed a strong correlation between self-references and SBP reactions during the speech and arithmetic tasks. Alcohol attenuated the correlation, resulting in SBP response dampening, but it did not affect pronoun use. These results have implications for the study of individual differences in cardiovascular reactivity, sensitivity to alcohol effects, and the relation of alcohol consumption to coronary heart disease.

The effect of menstrual cycle on blood alcohol levels and behavior

To determine whether the behavioral effects of alcohol were altered by menstrual cycle phase, 10 women between the ages of 21 and 24 who reported regular menstrual cycles of 28-31 days participated in three experimental sessions, the dates of which coincided with the flow, midcycle and premenstrual phases of their cycles. In each session, the effects of alcohol (.65 g/kg) were measured on memory for words, standing steadiness, coding vigilance and blood alcohol level (BAL). The following measures were obtained in each of three testing rounds: baseline, the ascending limb of the BAL curve and the descending limb of the BAL curve. Peak BALs of 83 +/- 2 mg/d1 were obtained. On coding vigilance, the subjects were observed to perform better during the flow phase of their cycle than they did in either the midcycle or premenstrual phase. No significant phase by alcohol effects were obtained, however. These results suggest that neither the pharmacokinetics of alcohol nor certain behaviors affected by alcohol were affected by menstrual cycle phase. These results are generally consistent with previous research, and they question the logic of excluding women subjects from studies on the effects of alcohol on behavior, at least for the variables used in this study.