ABSTRACT
BACKGROUND: Patients often prefer one knee over the other following staged bilateral total knee arthroplasty (BTKA). Our study compared patient-reported outcomes scores of each knee following BTKA and identified factors that may contribute to the identified discrepancies. METHODS: All patients who underwent staged BTKA between July 2014 and August 2022 were identified. The patient-reported outcomes were collected preoperatively and at 2 weeks, 6 weeks, 1 year, and 2 years postoperatively. Each knee's results were compared using paired t-tests and McNemar tests. Preoperative Kellgren-Lawrence Grade (KLG), postoperative range of motion (ROM), reoperation rates, and manipulations under anesthesia (MUAs) were collected. Results were stratified based on time between TKAs (< 3 months, 3 to 12 months, 1 to 2 years, and > 2 years). RESULTS: There were 911 patients who underwent staged BTKA, with a mean 4.1-year follow-up. The ROM, patient satisfaction, MUAs, and reoperations were not significantly different between knees. Comparing the KLG of the first and second knees, 71% had the same KLG for both knees, 21% had a lower KLG, and 7% of the second knees had a higher KLG. The first knee had greater pain reduction (-10.6 at 2 weeks, -27.4 at 6 weeks) compared to the second (9.3 at 2 weeks, -8.1 at 6 weeks) (P < .0001) and better improvement in Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR) score (8.5 at 2 weeks, 16.9 at 6 weeks) compared to the second (-5.8 at 2 weeks, 5.0 at 6 weeks) (P < .0001). The 1-year outcomes between first and second knees, or recovery curves, were not different when stratifying by time between TKAs. CONCLUSIONS: The second knee in a staged BTKA has less delta improvement in KOOS JR and pain scores at early follow-up, likely due to higher starting KOOS JR and Patient-Reported Outcomes Measurement Information System scores, despite similar final patient satisfaction and clinical outcome measures. Lower KLG in the second total knee arthroplasty (TKA) may contribute to these findings. An MUA after the first TKA is highly predictive of an MUA after the second TKA.
ABSTRACT
The development of chemical strategies for site-specific protein modification now enables researchers to attach polyethylene glycol (PEG) to a protein drug at one or more specific locations (i.e., protein PEGylation). However, aside from avoiding enzyme active sites or protein-binding interfaces, distinguishing the optimal PEGylation site from the available alternatives has conventionally been a matter of trial and error. As part of a continuing effort to develop guidelines for identifying optimal PEGylation sites within proteins, we show here that the impact of PEGylation at various sites within the ß-sheet model protein WW depends strongly on the identity of the PEG-protein linker. The PEGylation of Gln or of azidohomoalanine has a similar impact on WW conformational stability as does Asn-PEGylation, whereas the PEGylation of propargyloxyphenylalanine is substantially stabilizing at locations where Asn-PEGylation was destabilizing. Importantly, we find that at least one of these three site-specific PEGylation strategies leads to substantial PEG-based stabilization at each of the positions investigated, highlighting the importance of considering conjugation strategy as an important variable in selecting optimal PEGylation sites. We further demonstrate that using a branched PEG oligomer intensifies the impact of PEGylation on WW conformational stability and also show that PEG-based increases to conformational stability are strongly associated with corresponding increases in proteolytic stability.
