Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in one of 13 subspecialties. Click here for a collection of all OrthoBuzz subspecialty summaries. This month, Michael J. Taunton, MD, author of the January 16, 2019 “What’s New in Adult Reconstructive Knee Surgery,” selected the five most compelling findings from among the more than 100 noteworthy studies summarized in the article.
Cementless vs Cemented TKA Fixation
—A matched case-control study of 400 primary total knee arthroplasties (TKAs) found that cementless TKAs had a 0.5% rate of aseptic loosening over a mean follow-up of 2.5 years, while cemented TKAs had an aseptic loosening rate of 2.5%.1
TKA Component Size in Obese Patients
—Among 35 revision-TKA patients with a varus collapse of the tibia, 29 weighed >200 lbs. Fehring et al. found that patients with implants at the small end of the range of the manufacturer’s tibial size offering and with >5° of preoperative varus were at increased risk of tibial-component failure.2
—A retrospective multivariate analysis of >4,300 patients who underwent outpatient TKA and >128,900 patients who underwent inpatient TKA found that, within 1 year, those who had outpatient procedures were more likely to experience a tibial and/or femoral component revision due to a noninfectious cause, irrigation and debridement, explantation of the prosthesis, and stiffness requiring manipulation under anesthesia.
—In a randomized trial of patients undergoing TKA, one group received 15 mg/kg of systemic intravenous vancomycin, and a second group received intraosseous regional administration of 500 mg vancomycin into the tibia. Mean tissue concentrations of the antibiotic were 34.4 mg/g in the intraosseous group and 6.1 mg/g in the intravenous group, suggesting that intraosseous administration provides a significantly higher tissue concentration of that antibiotic. 3
TKA Anesthesia Protocol
—A retrospective review of 156 consecutive patients who underwent primary TKA found that procedures performed with mepivacaine spinal anesthesia led to fewer episodes of urinary catheterization and shorter mean length of stay compared with procedures performed with bupivacaine spinal anesthesia.4
- Miller AJ, Stimac JD, Smith LS, Feher AW, Yakkanti MR, Malkani AL. Results of cemented vs cementless primary total knee arthroplasty using the same implant design. J Arthroplasty.2018 Apr;33(4):1089-93. Epub 2017 Dec
- Fehring TK, Fehring KA, Anderson LA, Otero JE, Springer BD. Catastrophic varus collapse of the tibia in obese total knee arthroplasty. J Arthroplasty.2017 May;32(5):1625-9. Epub 2017 Jan 30.
- Chin SJ, Moore GA, Zhang M, Clarke HD, Spangehl MJ, Young SW. The AAHKS Clinical Research Award: intraosseous regional prophylaxis provides higher tissue concentrations in high BMI patients in total knee arthroplasty: a randomized trial. J Arthroplasty.2018 Jul;33(7S):S13-8. Epub 2018 Mar 15.
- Mahan MC, Jildeh TR, Tenbrunsel TN, Davis JJ. Mepivacaine spinal anesthesia facilitates rapid recovery in total knee arthroplasty compared to bupivacaine. J Arthroplasty.2018 Jun;33(6):1699-704. Epub 2018 Jan 16.
The practice of orthopaedic surgery is moving fairly rapidly to the outpatient environment. Advances in less invasive surgical procedures, regional anesthesia, and postoperative pain management have provided the foundation for this transition. The migration to outpatient surgery centers enables surgeons to use surgical teams more focused on orthopaedic technology and practice parameters. The concern that arises in everyone’s mind, though, is the issue of safety.
In the October 19, 2016 issue of JBJS, Qin et al. analyzed the NSQIP database and found that the outpatient surgical treatment of patients with a closed ankle fracture and minimal comorbidities resulted in lower risk of pneumonia and no difference in surgical morbidity, reoperations, and readmissions when compared with inpatient surgery.
The NSQIP dataset is voluntary and, as with any database, confounding variables are unavoidable. But these authors used propensity score matching and Bonferroni correction to minimize selection bias and manage multiple comparisons.
The study excluded emergency cases, cases with preoperative sepsis, and cases of open ankle fracture, and I can still foresee that patients with more severe fracture patterns, soft tissue compromise, and unstable medical comorbidities would be better off treated as inpatients. Nevertheless, it is reassuring that this study found no differences in complication or readmission rates. These findings reinforce the movement of orthopaedic surgical practice to the outpatient setting, and in my experience that movement is wholly welcomed by patients and their families.
Marc Swiontkowski, MD