What’s New in Adult Reconstructive Knee Surgery

In this Guest Editorial, we review and summarize the key findings from the most noteworthy and impactful studies relating to adult reconstructive knee surgery across different areas of research over the past year. This review includes studies of various Levels of Evidence, but special attention was paid to higher Levels of Evidence and award-winning publications. Health-Care Policy and Economics As orthopaedic surgeons strive to provide improved patient outcomes, there remains a wide disparity in the equity of health-care access for the most vulnerable patient populations. There is an increased recognition of adverse outcomes based on social determinants of health (SDOH) and of the need for policy and health-care system changes to bridge the gap in patient access and the quality of care that they receive1. The International Classification of Diseases, Tenth Revision (ICD-10) contains Z code categories (Z55-Z65) to document the presence of SDOH. Although these codes currently lack financial incentives for their use, they provide data for tracking and research purposes to identify potential areas for targeted interventions1. In a large database study, Z codes were used to identify matched cohorts of patients with and without SDOH. After the propensity matching of 207,844 patients, the authors observed that patients with disparities in SDOH had higher odds of readmissions and complications within 90 days and higher rates of revision surgery and periprosthetic joint infection (PJI) within 2 years following total knee arthroplasty (TKA) compared with the control group2. One specific socioeconomic metric, the Social Vulnerability Index (SVI), uses 16 variables from the U.S. Census data to identify at-risk communities3,4. Two database studies separately demonstrated that higher SVI was associated with increased length of stay, readmissions, and complications after TKA3, whereas SVI subthemes of household composition and disability were risk factors for 90-day complications following TKA4. These studies encourage a broader adoption of the SDOH and the SVI for screening and preoperative intervention to optimize outcomes in the most vulnerable patient populations. Treatment of Knee Osteoarthritis Biologic interventions to treat knee osteoarthritis and prevent progression remain a trending topic. In a randomized controlled trial (RCT), platelet-rich plasma (PRP) injections alone were compared with exercise and PRP combined with exercise in the treatment of symptomatic grade-2 and 3 knee osteoarthritis. A commercially available kit was used to prepare the PRP injections, which were given 3 times at weekly intervals. Although improvements in patient-reported outcomes were seen in all 3 groups after 24 weeks, the exercise group and the exercise combined with PRP group were superior to the PRP group alone with respect to pain, function, and quality of life. PRP alone had no benefit in treating knee osteoarthritis compared with exercise, allowing the authors to conclude that there is no role of PRP in the treatment of mild to moderate knee osteoarthritis5. Unicompartmental Knee Arthroplasty (UKA) Indications and Utilization The utilization of UKA continues to increase as a treatment for compartment-specific osteoarthritis. A review of the American Board of Orthopaedic Surgery (ABOS) Part II Oral Examination Case List database revealed that the volume of UKAs performed by newly trained surgeons more than doubled between 2011 (18.8 per 10,000 cases) and 2021 (39.5 per 10,000 cases). UKA, compared with periarticular knee osteotomy performed for osteoarthritis, demonstrated significantly lower rates of surgical complications (7.3% compared with 23.7%; p < 0.001), reoperation (1.9% compared with 5.2%; p = 0.002), and infection (1.4% compared with 6.7%; p < 0.001)6. Similarly, a large health-care network database study demonstrated a 590% increase in utilization between 2012 (241 UKAs) and 2022 (1,662 UKAs), with a similar increase in the adoption of robotic UKA (11 in 2012 and 68 in 2022 [518%])7. Lateral UKA There is growing interest in the utilization of lateral UKA for isolated lateral compartment osteoarthritis. In a matched cohort analysis, comparing causes of lateral knee osteoarthritis, all patients had significant functional improvements with respect to the Knee Society Score, Forgotten Joint Score, and visual analog scale (VAS) for pain. Compared with patients with primary lateral knee osteoarthritis, patients who underwent lateral meniscectomy demonstrated less medial compartment osteoarthritis progression and thus significantly greater implant survivorship (97.6% compared with 83.3%) at a mean follow-up of 10 years8. Plancher et al.9 demonstrated that the presence of grade-3 or 4 chondromalacia of the lateral patellar facet did not negatively impact functional scores or survivorship of lateral UKA. Bunyoz et al.10 found a learning curve of approximately 33 cases, based on surgical duration. Oxford Knee Scores (OKS) did not reveal adverse functional outcomes during the learning curve but did reveal 95.4% revision-free survivorship at 7 years10. Similarly, a single-surgeon cohort of 161 lateral UKAs in 153 patients demonstrated revision-free survivorship of 97.4% at 5 years, 95.4% at 10 years, and 91.3% at 15 years11. Registry Data Data from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR) compared the OKS and survivorship of 3,453 medial UKAs performed with cement and 3,453 cementless medial UKAs in a propensity-matched study. The authors found a greater postoperative mean OKS (39.1 ± 8.7) in the cementless mobile-bearing Oxford UKA cohort compared with the cohort of patients who underwent UKAs performed with cement (38.5 ± 8.6), although the difference was below the minimum clinically important difference (MCID). Additionally, the cementless Oxford UKA had significantly greater 10-year survivorship (93.0%) compared with its cemented counterpart (91.3%). The differences in clinical outcomes were greater, in favor of UKAs performed without cement, when the procedures were performed by high-volume surgeons (≥30 UKAs per year)12. UKA Revision Data from the New Zealand Joint Registry indicated that there is a significantly lower threshold to revise a poorly functioning (OKS, ≤25) UKA compared with a TKA at 6 months (19.6% compared with 5.1%; p < 0.001), 5 years (12.5% compared with 4.3%; p < 0.001), and 10 years (15.0% compared with 6.4%; p = 0.024). The risk of revision for an unknown etiology was approximately 2.5 times higher for UKA compared with TKA13. Acute PJI following UKA presents a unique challenge involving a joint with a prosthetic component as well as native cartilage. A multicenter study explored the effectiveness of debridement, antibiotics, and implant retention (DAIR) in this scenario. The mean time from index UKA to PJI diagnosis was 11.1 months. The eradication rate at 1 year was 80.8% (42 of 52 UKAs), with the failures proceeding to either 1-stage or 2-stage revision to TKA. Although the surgical techniques and irrigation solutions varied widely across institutions, a wide exposure with thorough synovectomy was associated with infection eradication14. Primary TKA Antibiotic Prophylaxis and Infection Prevention Debate persists with regard to the optimal antibiotic prophylaxis for primary TKA. In a multicenter, double-blinded, placebo-controlled superiority trial, the investigators sought to evaluate the efficacy of the addition of intravenous vancomycin compared with placebo in preventing surgical site infection within 90 days postoperatively. Over 4,000 patients without known methicillin-resistant Staphylococcus aureus (MRSA) colonization were included, including 2,233 patients who underwent TKA. Patients received 2 g of cefazolin plus weight-based vancomycin or placebo. Sixty-three (5.7%) of 1,109 patients in the vancomycin group developed a surgical site infection compared with 42 (3.7%) of 1,124 patients in the placebo group (relative risk, 1.52 [95% confidence interval (CI), 1.04 to 2.23]). An additional subgroup analysis on the safety of vancomycin administration yielded a similar rate of adverse events (1.7%) in both groups15. In a systematic review of penicillin allergy in the setting of total joint arthroplasty (TJA), true allergy rates were found to be low (0.7% to 3%). The rate of allergic reaction in patients with a penicillin allergy who received a cephalosporin was 0% to 2%, leading the authors to conclude that perioperative allergy screening and testing can safely increase the usage of first-line antibiotic prophylaxis in TJA16. In a single-blinded RCT of patients undergoing tourniquetless primary TKA, 10 patients received either weight-based intravenous vancomycin 1 hour before the surgical procedure or 500-mg intraosseous vancomycin at the time of incision. Systemic samples prior to incision and at closure showed significantly greater levels of vancomycin in the intravenous group compared with the interosseous group. Intraoperative tissue samples demonstrated similar levels in the intravenous and intraosseous groups, including in samples from the distal femur (61.0 ± 16.0 and 66.2 ± 12.3; p = 0.80), proximal tibia (52.8 ± 13.5 and 57.1 ± 17.0; p = 0.84), and suprapatellar synovial tissue (10.7 ± 5.3 and 9.0 ± 3.3; p = 0.80). The authors highlighted the efficacy of intraosseous vancomycin while avoiding the possible systemic toxicity of vancomycin17. A study from the Catalan Arthroplasty Register of TKAs performed between 2011 and 2020 assessed the association of antibiotic-loaded bone cement (ALBC) and revision rates. Their analysis of 22,781 TKAs (57.6% with plain cement, and 42.4% with ALBC) revealed that the 3-month revision TKA rate for infection was significantly lower in the ALBC group (0.52% compared with 0.78%, p = 0.04)18. Conversely, in a study of 14 national or regional registries, >2 million TKAs were reviewed to compare the risk of 1-year revision for PJI between TKA using ALBC and TKA using plain bone cement. The authors reported a cumulative 1-year revision rate for PJI of <1% in both the ALBC group (range, 0.21% to 0.80%) and the plain cement group (range, 0.23% to 0.70%). There was no significant difference in revision for PJI at 1 year (hazard ratio [HR], 1.16 [95% CI, 0.89 to 1.52]) or for all causes (HR, 1.12 [95% CI, 0.89 to 1.40]) between ALBC and plain bone cement19. Blood Loss Prophylaxis The winners of the American Association of Hip and Knee Surgeons (AAHKS) Clinical Research Award, Kirwan et al.20, investigated the efficacy of extended oral tranexamic acid (TXA) in a double-blinded RCT. Patients who underwent outpatient TKA at a surgery center were randomized to receive 1.95-g oral TXA on the day of the surgical procedure after ambulation and 3 additional doses on postoperative days 1, 2, and 3. The control group took placebo pills in the same manner. The TXA group demonstrated better knee flexion (116.05° compared with 106.5°; p = 0.0308), VAS pain scores (1.35 compared with 2.8; p = 0.011), and Knee Injury and Osteoarthritis Outcome Scores for Joint Replacement) (73.33 compared with 62.47; p = 0.0019) at 6 weeks compared with the placebo group. As the adoption of perioperative TXA administration becomes more universal, an additional benefit of its use is the potential to lower the risk of PJI, with an odds ratio (OR) of 0.63 (95% CI, 0.42 to 0.96; p < 0.001) shown in a recent systematic review and meta-analysis, although it included a small number of studies. The authors hypothesized that TXA prevents PJI by reducing the need for transfusions, postoperative wound drainage, and/or hematoma and studies assessed the effectiveness of various In an RCT the efficacy of periarticular in the setting of an plus between the and of the knee a periarticular was found to be to an periarticular in of the pain and oral et demonstrated that an can be safely by the to improved pain and Their the need for or an In a double-blinded RCT of patients undergoing TKA, the addition of oral significantly improved VAS pain scores and patient compared with is a reported after TKA. The winners of the Award, et demonstrated no benefit from with respect to or patient-reported outcomes at 6 weeks or 90 days after TKA. The investigators randomized patients to the and placebo of the study in a double-blinded RCT. In a similar double-blinded et found a in patients for the 3 days following TKA, but these on that In an award-winning study, patient-reported quality to by 90 days after TKA. 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This was an RCT that assessed the efficacy of compared with placebo in patients with grade-2 and 3 osteoarthritis. The placebo of the same 2 of the used to the bone in the group. groups received injections of the and VAS pain scores significantly improved in the whereas to for the placebo group. revealed of the medial joint in the placebo group from to 6 months to months. these changes and the volume did not significantly between the 2 The authors their with treatment bone and acid injections in pain and scores at a minimum of 6 months as injections for knee a systematic review and network In this systematic review and network meta-analysis, the authors studies including that underwent injections for knee osteoarthritis. and II were included for acid was in of the by placebo in PRP in in and bone in The demonstrated that PRP injections yielded greater pain and functional improvements compared with placebo at a minimum of 6 months. of the of the included a the cumulative curve analysis was performed in the network meta-analysis, which demonstrated that PRP had the of compared with and Although was not in this study, these findings important for to in the to the treatment of knee osteoarthritis. after total knee a randomized controlled This double-blinded RCT assessed the efficacy of compared with following TKA. The investigators and patients were all to the The included preoperative and was 3 and with a progression The in the lack of and preoperative with a lower of A total of patients were the 2 The group demonstrated greater functional outcomes and patient lower VAS pain and length of compared with the group. These outcomes the efficacy of a in as outpatient TKA becomes more plasma injections for osteoarthritis of the a systematic review and of randomized controlled In this systematic review and of the authors compared the efficacy of PRP and of the 16 included and the 6 of patients were The authors assessed the index of all of the studies to the study outcomes were or this and events in a 2 2 the is 1 to of index of the study is and less The demonstrated that PRP had higher rates of the for pain, and not compared with as The mean number of events to the of the treatment was ± on this the from the and the treating in the optimal for knee osteoarthritis. total knee arthroplasty over the medial a systematic review and network This systematic review and network compared the outcomes of TKA to the surgical A total of 33 including TKAs were included for In of of the and were superior to medial in the 14 days after TKA. respect to VAS pain the was superior on postoperative day In the the medial for postoperative pain. outcomes the and although these differences all with The of the study was the of across all studies the to compare outcomes were lower at postoperative day 7 compared with postoperative days 42 or this the the of the to TKA. doses of platelet-rich plasma more than of platelet-rich plasma in the treatment of knee a systematic review and In this systematic review and of the authors sought to compare a with doses of PRP in the treatment of knee osteoarthritis. studies involving patients were The knee osteoarthritis from 1 to 3. PRP demonstrated better VAS pain scores compared with but this was based on 3 studies that showed The safety was similar between the different PRP The of this study be with of the small number of studies. Additionally, the authors to evaluate but the data from the of data of in reducing and pain after total knee a controlled multicenter Joint This RCT the efficacy of on postoperative and pain following TKA. is a from that is used to treat its to and A total of patients were randomized to either receive or not receive g per day for 14 after TKA. There was no placebo group. at the and levels was by an to the treatment group. The group demonstrated significantly less and pain with compared with the control group. There were no differences in pain at patient-reported outcomes, of or rates. Although postoperative effectiveness was demonstrated in this study, studies safety before its use be A network of randomized controlled for efficacy and following total knee This network of to compare effectiveness and after TKA between different A total of studies were combined with a the after TKA on postoperative days 1 and 2 and the on postoperative days 1 and 3 A demonstrated the on postoperative day 3 These that combined with a be a first-line for pain control following TKA.

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