Highlights of Papers on Adult Reconstruction Knee Topics, Part 2
Risk of PJI in TKA Patients with a History of PJI in Another Joint
A study from Mayo Clinic found that primary total knee arthroplasty (TKA) patients were at a significantly higher risk of developing a periprosthetic joint infection (PJI) if they had a history of PJI following TKA in the contralateral knee or in either hip joint following total hip arthroplasty.
Researchers evaluated outcomes in 95 patients (102 knees) who underwent primary TKA at Mayo Clinic between 2000 and 2014 and who had a history of PJI another joint. They compared the outcomes with those of 306 primary TKAs in patients who had not developed a PJI (1:3 match for age, sex, body mass index, and surgical year).
Patients with a history of PJI in another joint had a 6.1% cumulative incidence of PJI at 10 years after primary TKA, compared with 2.6% in the control group, for a 3-fold higher risk of PJI. The risk was even higher for a subset of study group patients who were on chronic suppression therapy: Six of 7 developed a PJI, for a 15-fold higher risk of infection.
Additional research is needed, the study authors said, particularly to determine why patients on chronic suppression therapy still had a very high risk for PJI.
Chalmer B, Weston J, Osmon DR, Hanssen AD, Berry DJ, Abdel MP. Prior Hip or Knee Periprosthetic Joint Infection (PJI) in Another Joint Increases Risk of PJI after Primary Total Knee Arthroplasty by Three Fold: A Matched Control Study (Paper 261). Presented at the 2019 Annual Meeting of the American Academy of Orthopaedic Surgeons, March 12-16, Las Vegas, Nevada.
Outcomes with Antibiotic-Loaded Cement IM Dowels vs. No IM Dowels
Use of articulating spacers with antibiotic-loaded cement dowels in the intramedullary (IM) canals may be clinically beneficial in patients undergoing 2-stage resection and reimplantation total knee arthroplasty (TKA) who are chronically infected or poor hosts, according to a study from Indiana University School of Medicine.
The use of these dowels is standard practice in resection TKA due to the high rate of infection – approximately 40% – in the IM canals. But is this an effective management option? To find out, the researchers from Indiana University compared outcomes with and without the use of IM dowels in a cohort of 91 patients who had undergone 2-stage resection and reimplantation for infected TKA between 2010 and 2017.
Patients were divided into 3 spacer categories:
- Static spacers with IM dowels (n=27)
- Articulating spacers with IM dowels (n=14)
- Articulating spacers without IM dowels (n=50)
Overall, patients without spacers had a higher success rate – defined as no repeat resection before reimplantation and no recurrent infection within 6 months of reimplantation – than patients with any type of spacer and IM dowels (61% vs 39%; P=0.36). But, patients with articulating pacers and IM dowels had a higher success rate than patients without IM dowels (93% vs 88%), a difference that was not statistically significant.
The researchers said that use of articulating spacers with IM dowels could be clinically significant, however. In their study, the success rate was 100% for McPherson Stage III-B/C patients (chronic infection/poor host) who had received articulating spacers with IM dowels.
Zielinski MR, Ziemba-Davis M, Warth LC, Keyes B, Meneghini RM. Do Antibiotic Impregnated Intramedullary Dowels Assist in Eradicating Infection in Total Knee Arthroplasty? (Paper 263). Presented at the 2019 Annual Meeting of the American Academy of Orthopaedic Surgeons, March 12-16, Las Vegas, Nevada.
Early Failures with the Bicruciate Knee
A bicruciate-retaining knee implant for total knee arthroplasty (TKA) was introduced as an option to preserve the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) and provide a more normal-feeling knee. But 12-month outcomes in a consecutive series of patients who received the implant found more revisions, reoperations, and radiolucencies in the bicruciate knee group than in cruciate-retaining implant control group. 
With additional follow-up now available for 175 bicruciate TKAs performed between May 2013 and October 2015, have outcomes improved?
Unfortunately, concerns about early failures are still relevant: In the latest review of outcomes from the original series, overall survivorship of the implant was 88% at 3 years, with 13.5% of patients undergoing a revision procedure at a mean of 1.6 years. Knees were revised for:
- Implant loosening
- ACL impingement
- ACL deficiency
- Chronic pain
- Arthrofibrosis with heterotopic ossification
- Unknown reasons
The researchers said that based on their findings, the implant appears to introduce a higher risk for early revision in some patients. They noted that other patients who don’t develop the early complications tend to do well with the bicruciate knee. The question – still unanswered – is whether the potential benefits outweigh the possible risks.
Sandifer PA, Anderson M, Peters CL, Gililland J, Pelt CE. Three to Five Year Survivorship of a Contemporary Bicruciate-Retaining Total Knee Arthroplasty: Higher than Anticipated Rate of Failure (Paper 644). Presented at the 2019 Annual Meeting of the American Academy of Orthopaedic Surgeons, March 12-16, Las Vegas, Nevada.
Christensen JC, Brothers J, Stoddard CJ, Anderson MB, Pelt CE, Gililland JM, Peters CL. Higher Frequency of Reoperation With a New Bicruciate-retaining Total Knee Arthroplasty. Clin Orthop Relat Res. 2017 Jan;475(1):62-69. doi: 10.1007/s11999-016-4812-5.
Clinical and Cost Benefits of a Synthetic Graft for Extensor Mechanism Reconstruction
A synthetic graft has advantages over allograft for reconstruction of extensor mechanism disruption following total knee arthroplasty, including better complication, reoperation, graft failure, and infection rates; lower costs; and comparable patient-reported outcomes and extensor lag, according to a study from 2 high-volume academic institutions in Canada.
Twenty-seven patients who underwent extensor mechanism reconstruction at 1 of the 2 institutions between 2006 and 2017 were included in the study (n=13 for synthetic graft; n=14 for allograft). The study authors reviewed data on:
- Extensor lag
- Use of ambulatory aids
- Patient-reported outcome measures
- Postoperative complications
They found no difference between groups in postoperative extensor lag or patient-reported outcome at a mean follow-up of 4.1 years. The data also showed:
- Use of ambulatory aids: 38% for the synthetic graft vs 79% for the allograft
- Complication rate: 23% for the synthetic graft vs 43% for the allograft
- Reoperation rate: 15% for the synthetic graft vs 43% for the allograft
- Mean costs (graft and reoperation): $4733.08 CAD for the synthetic graft vs $24,050.40 for the allograft
Wood T, Leighton J, Backstein D, Marsh J, Howard J, McCalden RW, MacDonald SJ, Lanting B. Synthetic Graft Compared to Allograft Reconstruction for Extensor Mechanism Disruption in Total Knee Arthroplasty: A Multicenter Cohort Study (Paper 645). Presented at the 2019 Annual Meeting of the American Academy of Orthopaedic Surgeons, March 12-16, Las Vegas, Nevada.
How Common Is UKA in the Medicare Population?
For many reasons – less-invasive procedure, shorter hospital length of stay, and faster recovery time among them – unicompartmental knee arthroplasty (UKA) has become more common in the past decade. The procedure is generally offered to older patients, but little is known about utilization among those on Medicare. Researchers from the University of Kansas Medical Center sought to find out with a study of UKA practice patterns in the US.
Using CPT code 27446, which includes UKA of the medial or lateral condyles, they identified more than 20,000 Medicare patients who had undergone UKA between 2005 and 2014, recording patients’ age, gender, and region (Midwest, Northeast, South, and West). They defined survivability as conversion to total knee arthroplasty (TKA). Among their findings:
- Most patients were ages 65 to 69 (6297), followed by ages 70 to 74 (5401).
- More UKAs were performed in the South (52%) than in any other region.
- More women than men underwent UKA: 51% vs 48%.
- Implant survivability was 90% at 8 years after surgery.
- The average time from UKA to TKA was 819 days.
- Annual utilization of UKA varied during the study period, increasing most dramatically between 2012 and 2014.
Morris BL, Reinhardt D, Hassan M, Tarakemeh A, Schroeppel JP, Mullen SM, Vopat BG. Unicompartmental Knee Arthroplasty Utilization in the Medicare Population (Paper 730). Presented at the 2019 Annual Meeting of the American Academy of Orthopaedic Surgeons, March 12-16, Las Vegas, Nevada.
Outcomes and Costs with a Home Exercise Program after TKA
Following total knee arthroplasty (TKA), patients who participated in a home exercise program achieved results equivalent to those of patients who participated in a formal outpatient program with a minimum cost savings of $1,340 per patient, according to a study from The Rothman Institute.
The researchers compared outcomes in 520 consecutive patients who underwent primary unilateral TKA between January 2016 and December 2017 and were discharged home. Outpatient physical therapy was prescribed for the 251 TKA patient who had the procedure in 2016, while a 2-week home exercise program was prescribed for the 269 TKA patients who underwent the procedure in 2017. After 2 weeks, outpatient physical therapy was prescribed for 34% of patients in the home exercise group who had a range of motion less than 90° OPT or who asked for it.
Overall, the rates of revision TKA, and manipulation under anesthesia were similar between groups, but patients who were prescribed outpatient physical therapy after the home exercise program were more likely to need manipulation under anesthesia (P=0.013). Functional outcomes scores were also similar between groups. Patients who had outpatient physical therapy after home physical therapy incurred average additional costs of $$1,340.87 (Medicare) to $1,893.42 (private insurance).
Rondon A, Tan T, Wang W, Wilsman JA, Purtill JJ. Home Exercises vs. Outpatient Physical Therapy after Total Knee Arthroplasty: Value and Outcomes following a Protocol Change (Paper 814). Presented at the 2019 Annual Meeting of the American Academy of Orthopaedic Surgeons, March 12-16, Las Vegas, Nevada.
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