The efficacy of antibiotic-eluting material in a two-stage model of periprosthetic joint infection.

Periprosthetic joint infections occur in about 2% of patients who undergo primary total joint arthroplasty, a procedure performed over 1 million times in the United States. The gold standard of treatment is a two-stage revision. This study aimed to establish a two-stage procedure in a preclinical small animal model (rat) to test and compare the efficacy of an antibiotic-eluting material in managing infection. Joint replacement was simulated by transchondylarly implanting a polyethylene (PE) plug into the distal femur and a titanium screw in the proximal tibia. Methicillin-sensitive Staphylococcus aureus (MSSA) 108 CFU/mL was injected into the tibial canal and the joint space before wound closure. The control groups were killed on postoperative day (POD) 18 (n = 12) and on POD 42 (n = 4) to assess both early and later-stage outcomes in the control group. The test group underwent revision surgery on POD 18 for treatment using gentamicin-eluting polyethylene (GPE, n = 4) and was observed until POD 42 to evaluate the efficacy of treatment. Our results showed that the bone loss for the treatment group receiving GPE was significantly less than that of the control (p < 0.05), which was supported by the histology images and an AI-tool assisted infection rate evaluation. Gait metrics duty factor imbalance and hindlimb temporal symmetry were significantly different between the treatment and control groups on Day 42. This animal model was feasible for evaluating treatments for peri-prosthetic joint infections (PJI) with a revision surgery and specifically that revision surgery and local antibiotic treatment largely hindered the peri-prosthetic bone loss. Statement of clinical significance: This revision model of peri-prosthetic infection has the potential of comparatively evaluating prophylaxis and treatment strategies and devices. Antibiotic-eluting UHMWPE is devised as at tool in treating PJI while providing weight bearing and joint space preservation.

A longitudinal rat model for assessing postoperative recovery and bone healing following tibial osteotomy and plate fixation.

BACKGROUND: Rodent models are commonly employed to validate preclinical disease models through the evaluation of postoperative behavior and allodynia. Our study investigates the dynamic interplay between pain and functional recovery in the context of traumatic osteotomy and surgical repair. Specifically, we established a rat model of tibial osteotomy, followed by internal fixation using a 5-hole Y-plate with 4 screws, to explore the hypothesis that histological bone healing is closely associated with functional recovery. OBJECTIVE: Our primary objective was to assess the correlation between bone healing and functional outcomes in a rat model of tibial osteotomy and plate fixation. METHODS: Seventeen male Sprague-Dawley rats underwent a metaphyseal transverse osteotomy of the proximal tibia, simulating a fracture-like injury. The resultant bone defect was meticulously repaired by realigning and stabilizing the bone surfaces with the Y-plate. To comprehensively assess recovery and healing, we performed quantitative and qualitative evaluations at 2, 4, 6, and 8 weeks post-surgery. Evaluation methods included micro-CT imaging, X-ray analysis, and histological examination to monitor bone defect healing. Concurrently, we employed video recording and gait analysis to evaluate functional recovery, encompassing parameters such as temporal symmetry, hindlimb duty factor imbalance, phase dispersion, and toe spread. RESULTS: Our findings revealed complete healing of the bone defect at 8 weeks, as confirmed by micro-CT and histological assessments. Specifically, micro-CT data showed a decline in fracture volume over time, indicating progressive healing. Histological examination demonstrated the formation of new trabecular bone and the resolution of inflammation. Importantly, specific gait analysis parameters exhibited longitudinal changes consistent with bone healing. Hindlimb duty factor imbalance, hindlimb temporal symmetry, and phase dispersion correlated strongly with the healing process, emphasizing the direct link between bone healing and functional outcomes. CONCLUSIONS: The establishment of this tibia osteotomy model underscores the association between bone healing and functional outcomes, emphasizing the feasibility of monitoring postoperative recovery using endpoint measurements. Our overarching objective is to employ this model for assessing the local efficacy of drug delivery devices in ameliorating post-surgical pain and enhancing functional recovery.

Predicting successful outpatient total shoulder arthroplasty.

BACKGROUND: Total shoulder arthroplasty (TSA) is increasingly performed safely and efficiently as an outpatient procedure in certain patients. Patient selection is often based on surgeon choice, surgeon expertise, or institutional guidelines. One orthopedic research group released a publicly available shoulder arthroplasty outpatient appropriateness risk calculator that considers patient demographic characteristics and comorbidities with the aim of helping surgeons to predict successful outpatient TSA. This study aimed to retrospectively assess the utility of this risk calculator at our institution. METHODS: Records were obtained for patients undergoing procedure code 23472 at our institution between January 1, 2018, and March 31, 2021. Patients undergoing anatomic TSA in the hospital setting were included. Records were reviewed for demographic characteristics, comorbidities, American Society of Anesthesiologists classification, and surgery duration. These data were entered into the risk calculator to calculate the likelihood of discharge by postoperative day 1. Charlson Comorbidity Index, complications, reoperations, and readmissions were also collected from patient records. Statistical analyses assessed the model's fit with our patient cohort and compared outcome measures between inpatient and outpatient groups. RESULTS: Of the 792 patients whose records were initially obtained, 289 met the inclusion criteria of anatomic TSA performed in the hospital setting. Of these patients, 7 were excluded because of missing data, leaving 282 patients: 166 (58.9%) in the inpatient group and 116 (41.1%) in the outpatient group. We found no significant differences in mean age (66.4 years in inpatient group vs. 65.1 years in outpatient group, P = .28), Charlson Comorbidity Index (3.48 vs. 3.06, P = .080), or American Society of Anesthesiologists class (2.58 vs. 2.66, P = .19). Surgery time was longer in the inpatient group than the outpatient group (85 minutes vs. 77 minutes, P = .001). Overall complication rates were low (4.2% in inpatient group vs. 2.6% in outpatient group, P = .07). Readmissions and reoperations did not differ between groups. There was no difference in the average percentage likelihood of same-day discharge (55.4% in inpatient group vs. 52.4% in outpatient group, P = .24), and a receiver operating characteristic curve to assess fit with the risk calculator demonstrated an area under the curve of 0.55. DISCUSSION: The shoulder arthroplasty risk calculator performed similarly to chance when retrospectively predicting discharge within 1 day after TSA in our patients. Complications, readmissions, and reoperations were not higher after outpatient procedures. Risk calculators for determining whether a patient should be admitted after TSA should be used cautiously because they may not provide measurable benefit over the use of surgeon experience and expertise in discharge decision making, and other factors may be relevant in the decision to perform outpatient TSA.

An investigation into gender bias in the evaluation of orthopedic trainee arthroscopic skills.

BACKGROUND: Women surgeons receive lower compensation, hold fewer academic positions, and hold fewer leadership positions than men, particularly in orthopedic surgery. Gender bias at the trainee level has been demonstrated in various surgical subspecialties, but there is a lack of information on gender bias within the orthopedic training environment. This study investigated whether implicit gender bias is present in the subjective evaluation of orthopedic trainee arthroscopic skills. METHODS: After institutional review board approval, a web-based survey was sent to American Shoulder and Elbow Surgeons (ASES) members via the society's email listserve. Study participants were informed that the study was being done to develop a systematic evaluation method for trainees. The survey randomized participants to view and evaluate a prefellowship and a postfellowship video of "Rachel" (she/her) or "Charles" (he/him) performing a 15-point diagnostic shoulder arthroscopy. The videos for Rachel and Charles were identical except for the pronouns used in the video. Participants evaluated the trainee's skill level using questions from the Arthroscopic Surgical Skill Evaluation Tool (ASSET). Blinded and deidentified additional comments regarding the trainee's skill were classified as positive, negative, or neutral. Statistical analyses were used to compare scores and comments between Rachel and Charles. RESULTS: Of 1115 active ASES members, 181 ASES members started the survey and 106 watched both videos and were included in the analysis. Of the 106 participants completing the survey, 96 (91%) were men and 10 (9%) were women with a median (interquartile range) age of 44 (38-51). A teaching role was reported by 84 of 106 participants (79%). There was no significant difference between prefellowship scores (P = .87) or between postfellowship scores (P = .84) for the woman and man fellow. The numbers of comments classified as positive, negative, or neutral were not significantly different between the man and woman fellow (P = .19). Participants in teaching roles gave significantly lower scores to both fellows at both time points (P = .04), and participants who had fellow trainees were more likely to give negative comments to both fellows (P = .02). DISCUSSION: Trainee gender did not influence the ratings and comments participants gave for trainee arthroscopic skills, suggesting that gender bias may not play a major role in the evaluation of arthroscopic skill during orthopedic training.

Longitudinal Model of Periprosthetic Joint Infection in the Rat.

The majority of periprosthetic joint infections occur shortly after primary joint replacement (<3 months) and require the removal of all implant components for the treatment period (~4 months). A clinically relevant animal model of periprosthetic infection should, therefore, establish an infection with implant components in place. Here, we describe a joint replacement model in the rat with ultrahigh molecular weight polyethylene (UHMWPE) and titanium components inoculated at the time of surgery by methicillin-sensitive Staphylococcus aureus (S. aureus), which is one of the main causative microorganisms of periprosthetic joint infections. We monitored the animals for 4 weeks by measuring gait, weight-bearing symmetry, von Frey testing, and micro-CT as our primary endpoint analyses. We also assessed the infection ex vivo using colony counts on the implant surfaces and histology of the surrounding tissues. The results confirmed the presence of a local infection for 4 weeks with osteolysis, loosening of the implants, and clinical infection indicators such as redness, swelling, and increased temperature. The utility of specific gait analysis parameters, especially temporal symmetry, hindlimb duty factor imbalance, and phase dispersion was identified in this model for assessing the longitudinal progression of the infection, and these metrics correlated with weight-bearing asymmetry. We propose to use this model to study the efficacy of using different local delivery regimens of antimicrobials on addressing periprosthetic joint infections. Statement of clinical significance: We have established a preclinical joint surgery model, in which postoperative recovery can be monitored over a multi-week course by assessing gait, weight-bearing, and allodynia. This model can be used to study the efficacy of different combinations of implant materials and medication regimens. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:1101-1112, 2020.