Evaluation of the permeation kinetics of formamide in porcine articular cartilage.

Cryopreservation of articular cartilage will increase tissue availability for osteochondral allografting and improve clinical outcomes. However, successful cryopreservation of articular cartilage requires the precise determination of cryoprotectant permeation kinetics to develop effective vitrification protocols. To date, permeation kinetics of the cryoprotectant formamide in articular cartilage have not been sufficiently explored. The objective of this study was to determine the permeation kinetics of formamide into porcine articular cartilage for application in vitrification. The permeation of dimethyl sulfoxide was first measured to validate existing methods from our previously published literature. Osteochondral dowels from dissected porcine femoral condyles were incubated in 6.5 M dimethyl sulfoxide for a designated treatment time (1 s, 1 min, 2 min, 5 min, 10 min, 15 min, 30 min, 60 min, 120 min, 180 min, 24 h) at 22 °C (N = 3). Methods were then repeated with 6.5 M formamide at one of three temperatures: 4 °C, 22 °C, 37 °C (N = 3). Following incubation, cryoprotectant efflux into a wash solution occurred, and osmolality was measured from each equilibrated wash solution. Concentrations of effluxed cryoprotectant were calculated and diffusion coefficients were determined using an analytical solution to Fick's law for axial and radial diffusion in combination with a least squares approach. The activation energy of formamide was determined from the Arrhenius equation. The diffusion coefficient (2.7-3.3 × 10-10 m2/s depending on temperature) and activation energy (0.9±0.6 kcal/mol) for formamide permeation in porcine articular cartilage were established. The determined permeation kinetics of formamide will facilitate its precise use in future articular cartilage vitrification protocols.

Recovery and Return to Activity 1 Year After Ankle Fracture Managed With Open Reduction and Internal Fixation: A Prospective Longitudinal Cohort Study.

Background: Ankle fractures are common and frequently managed with open reduction and internal fixation (ORIF). Although these fractures can occur at any age, they are most common in younger individuals with high-energy trauma or older adults with lower-energy trauma. Our investigation focused on those aged 65 years or younger. Our primary objective was to describe recovery over the first postfracture year in (1) functional dorsiflexion using the weightbearing lunge test (WBLT), (2) patient-reported functional outcomes using the Olerud Molander Ankle Score (OMAS), (3) return to prefracture activity levels, and (4) return to work. Secondarily, we examined patient and clinical factors (including the WBLT and OMAS) associated with return to prefracture activities, including sports. Methods: Using a prospective inception cohort of 142 patients between 18 and 65 years old who underwent ORIF after ankle fracture and attended follow-up visits, we collected information from participants and their medical charts. We assessed functional dorsiflexion (using side-to-side difference in WBLT), patient-reported functional outcome (OMAS), and self-reported return to prefracture activity levels and work at 6 weeks, 6 months and 1 year postoperatively. Results: The WBLT, OMAS, and return to prefracture activity and work improved significantly over time (P < .001). However, at 1 year postoperation, the mean side-to-side difference in the WBLT was 3.22±2.68 cm, 69 (72%) reported ankle stiffness, and only 49 (52%) had returned to prefracture activity levels. Of those who were working, 97% had returned to work by 1 year postoperation. Only the OMAS (P < .001) and side-to-side difference in WBLT (P = .011) were significantly associated with return to prefracture activity levels. Conclusion: Although participants improved significantly over the first postoperative year in all outcomes, many reported limitations in functional dorsiflexion and return to prefracture activities. Those with higher OMAS scores and smaller side-to-side difference in WBLT were more likely to return to prefracture activity levels by 1 year postoperatively.Level of Evidence: Level II, prognostic study.

Factors associated with maintaining reduction following locking plate fixation of proximal humerus fractures: a population-based retrospective cohort study.

BACKGROUND: Loss of reduction (LoR) can occur after locking plate fixation of proximal humerus fractures (PHFs). This study determined biomechanical features of fracture fixation associated with preventing LoR postoperatively. One-year reoperation rates were also compared between those with/without LoR. METHODS: Population-based administrative data for 359 adults treated using a locking plate for PHF between 2010 and 2016 were examined. Two trained assessors reviewed standardized shoulder radiographs. LoR (Yes/No) was defined as any fracture displacement >0.5 cm, and/or >10° change in neck-shaft angle (NSA) alignment relative to intraoperative imaging. Multiple logistic regression assessed how the following affected maintaining reduction: (1) sex, (2) age, (3) Neer classification, (4) shaft impaction (SI), (5) shaft medialization (SM), (6) calcar reduction (CR), (7) NSA alignment, and (8) screw use. RESULTS: LoR was seen in 79 (22%) patients. LoR was significantly associated with increasing age (odds ratio [OR] = 1.06/yr, P < .001), fracture severity (4-part vs. 2-part fracture; OR = 4.63, P = .001), and varus NSA alignment (<125° vs. ≥145°: OR = 5.6, P = .02; <125° vs. 125-145°, OR = 2.2, P = .02]). Patients achieving simultaneous SI, SM, and CR were significantly less likely (OR = 0.009, P < .001) to lose reduction, after controlling for age, fracture severity, and NSA alignment. If only SI was achieved, patients were still significantly less likely to lose reduction relative to achieving none of these mechanical features (OR = 0.17, P = .006). Reoperations were higher when LoR occurred (n = 26/77 [33.4%]) compared with no LoR (n = 20/276 [7.2%]) (P < .001). CONCLUSIONS: SI was strongly associated with preventing LoR in patients treated using a locking plate for PHF. SI with concurrent SM, CR, and a neutral or valgus NSA had the lowest rates of LoR. LoR was associated with higher rates of reoperation.