Does the Use of Intraoperative Pressure Sensors for Knee Balancing in Total Knee Arthroplasty Improve Clinical Outcomes? A Comparative Study With a Minimum Two-Year Follow-Up.

BACKGROUND: It is undetermined whether using sensors for knee balancing in total knee arthroplasty (TKA) improves patient outcomes. The purpose of this study was to compare clinical outcomes of sensor balance (SB) with manual balance (MB) TKA with a minimum two-year follow-up. METHODS: A consecutive series of 207 MB TKAs was compared with 222 SB TKAs between April 2014 and April 2017. A single surgeon performed all surgeries, using the same prosthesis. The primary end point was the aggregated mean change in four subscales of the Knee injury and Osteoarthritis Outcome Score (KOOS4) between preoperative and two-year time points. Secondary outcomes included mean differences between groups in all five KOOS subscales, proportions of knee balancing procedures, and rates of reoperations including revisions and manipulations for stiffness. RESULTS: The mean changes in the KOOS4 aggregated means for MB TKA (42.4; standard deviation, 29.1) and SB TKA (41.5; standard deviation, 25.0) were not significantly different (mean difference, 0.9; 95% confidence interval: -2.6 to 4.4, P = .62). There were significantly more balancing procedures in the SB group (55.9% versus 16.9%; P < .01). There were no significant differences in the number of reoperations (1.4% SB versus 1.4% MB; P = .71) or manipulations for stiffness (3.7% SB versus 4.4% MB; P = .69). CONCLUSION: The use of sensors in TKA to achieve knee balance did not result in improved clinical outcomes, despite significantly increasing the number of surgical interventions required to achieve a balanced knee. Sensors did not alter the rates of revision surgery or requirements for manipulation. It remains to be determined whether precise soft-tissue balancing improves prosthetic survivorship and joint biomechanics.

How coronal alignment affects distal femoral anatomy: an MRI-based comparison of varus and valgus knees.

PURPOSE: In contemporary total knee arthroplasty (TKA), most often, the goal is to align the femoral component to the epicondylar axis (EA). The posterior condylar axis (PCA) is easier to define than the EA, and thus the relationship of PCA to the EA is then used instead to align the femoral component to the EA. However, the relationship of PCA to EA is not constant and has been reported to differ between varus and valgus knees and with increasing deformity. The aim of this large MRI-based study was to evaluate the relationship between PCA and EA with varying coronal deformity especially with increasing valgus deformity. METHODS: EA, PCA, AP (Whiteside's line) and the mechanical axis were obtained from 474 magnetic resonance imaging (MRI) scans used to create patient-specific instrumentation (PSI) for the Biomet Signature (Warsaw, NJ) system. RESULTS: The relationship of EA relative to the PCA showed considerable heterogeneity in both varus and valgus groups. In the valgus group, there was statistically greater external rotation (P < 0.05) of the EA from the PCA with a mean of 2.52° (range - 1.9° to 6°) compared to the varus group with a mean of 2.03° (range - 3.9° to 6.9°). This relationship did not significantly change with increasing severity of coronal malalignment. Externally rotating the femoral cutting guide by 3° from the PCA, 11% (42 of 382) of varus knees would lie outside of ± 3° from EA. In valgus knees, externally rotating the femoral cutting block by 3° or 5° from the PCA, 6.5% (6 of 92) and 33.7% (31 of 92) of knees, respectively, would lie outside of ± 3° from EA. CONCLUSION: The relationship of PCA to EA is heterogeneous and is not altered significantly with increasing valgus coronal deformity. External rotation beyond 3° from PCA in valgus knees may lead to significant femoral component malrotation in a large proportion cases.

Absence of central circadian pacemaker abnormalities in humans with loss of function mutation in prokineticin 2.

CONTEXT: Loss of prokineticin 2 (PROK2) signaling in mice disrupts circadian rhythms, but the role of PROK2 signaling in the regulation of circadian rhythms in humans is undetermined. OBJECTIVE: The aim of the study was to examine the circadian rhythms of humans with a complete loss-of-function PROK2 mutation using an inpatient constant routine (CR) protocol. DESIGN AND SETTING: We conducted a case study in an academic medical center. SUBJECTS AND METHODS: Two siblings (one male and one female, ages 67 and 62 y, respectively) with isolated GnRH deficiency (IGD) due to a biallelic loss-of-function PROK2 mutation were studied using an inpatient CR protocol. Historical data from inpatient CR protocols conducted in healthy controls (ages 65-81 y) were used for comparison. MAIN OUTCOME MEASURES: We measured circadian phase markers (melatonin, cortisol, and core body temperature) and neurobehavioral performance (psychomotor vigilance task [PVT] and subjective alertness scale). RESULTS: Circadian waveforms of melatonin and cortisol did not differ between the IGD participants with PROK2 mutation and controls. In both IGD participants, neurobehavioral testing with PVT showed disproportionate worsening of PVT lapses and median reaction time in the second half of the CR. CONCLUSIONS: Humans with loss of PROK2 signaling lack abnormalities in circadian phase markers, indicating intact central circadian pacemaker activity in these patients. These results suggest that PROK2 signaling in humans is not required for central circadian pacemaker function. However, impaired PVT in the PROK2-null participants despite preserved endocrine rhythms suggests that PROK2 may transmit circadian timing information to some neurobehavioral neural networks.

High performance, LED powered, waveguide based total internal reflection microscopy.

Total internal reflection fluorescence (TIRF) microscopy is a rapidly expanding optical technique with excellent surface sensitivity and limited background fluorescence. Commercially available TIRF systems are either objective based that employ expensive special high numerical aperture (NA) objectives or prism based that restrict integrating other modalities of investigation for structure-function analysis. Both techniques result in uneven illumination of the field of view and require training and experience in optics. Here we describe a novel, inexpensive, LED powered, waveguide based TIRF system that could be used as an add-on module to any standard fluorescence microscope even with low NA objectives. This system requires no alignment, illuminates the entire field evenly, and allows switching between epifluorescence/TIRF/bright field modes without adjustments or objective replacements. The simple design allows integration with other imaging systems, including atomic force microscopy (AFM), for probing complex biological systems at their native nanoscale regimes.