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Video Summary: Diagnostic Utility of a Point-of-Care Test of Calprotectin for PJI After TKA

A new JBJS video summary is available now. View the video below, and read the full article here.

Multiligamentous Knee Injury May Not Be Synonymous with Knee Dislocation

Terminology is important in orthopaedics. When teaching, for instance, we stress the need for trainees to be able to articulate what a radiograph is showing using descriptive terms and classification systems.

Over the years, “multiligamentous knee injury” (MLKI) and “knee dislocation” have increasingly been used interchangeably within the orthopaedic vernacular, in part  because of the high energy required to sustain such injuries, but also because of the potentially devastating complications that can be associated with both.

Kahan et al. sought to better characterize these injuries and their associated complications in a study now reported JBJS. They retrospectively evaluated cases treated at their Level-I trauma center between 2001 and 2020.

A total of 123 patients with MLKI were included in the analysis: 45 patients with and 78 patients without a documented knee dislocation. MLKI was defined as disruption of at least 2 of the following: the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments. Cruciate ligament injuries and isolated injuries of the superficial medial collateral ligament were not included unless there was disruption of the posteromedial corner, semimembranosus, or medial patellofemoral ligament, indicating a more extensive medial-sided injury.

The investigators found that medial-sided injuries were more common in the dislocation group (53% vs 30%; p = 0.009), and the dislocation group had higher rates of peroneal nerve injury (38% vs 14%; p = 0.004) and vascular injury (18% vs 4%; p = 0.018). Of the 11 total patients with a vascular injury, 8 (73%) were in the dislocation group; 10 of the 11 underwent a vascular surgical procedure.

Not all cases of MLKI are a result of a knee dislocation, and in this adequately powered study, there were differences in the injury pattern and associated injuries between those with and without true dislocation. It is important to note that, although higher rates of neurovascular injury were seen in the dislocation group, such events also occurred in the group without dislocation, so a high index of suspicion must be maintained with these complex injuries. As the authors suggest, it may be better to consider cases of knee dislocation a subset of MLKI with the potential for increased neurovascular compromise.

Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media

 

 

 

Reimbursement for Revision TKA Has Not Kept Pace with Inflation

I was once told that if you don’t have any cases with complications, you either aren’t operating enough or aren’t following your patients. Although we in the orthopaedic community make every effort to minimize the occurrence of patient complications, one that remains difficult to eradicate is periprosthetic joint infection (PJI), which is a leading cause of revision total knee arthroplasty (TKA). The welfare of our patients requires successfully addressing this potentially devastating outcome, but reimbursement for these complex cases has decreased over the past decade.

In the upcoming issue of JBJS, Jella et al. offer insight on temporal trends in Medicare physician reimbursement for revision TKA. They queried the Medicare Physician Fee Schedule Look-Up Tool for pricing information corresponding to 1 and 2-stage revision TKAs and used monetary data from Medicare Administrative Contractors to calculate nationally representative means. The authors evaluated aseptic revision of 1 component, 1-stage revision (aseptic or septic), and both the first and second stages of a 2-stage septic revision.

They found that, from 2002 to 2019, there was a mild increase in the physician fee for each CPT code, with the exception of that for second-stage implantation. However, after adjusting for inflation, total Medicare reimbursements declined for both septic and aseptic revision TKAs (between 23% and 33%), with a significantly greater decline observed for septic revision.

The authors also found that Medicare spending on aseptic revision TKA nearly doubled from 2004 to 2017, while spending on septic revision TKA increased only slightly. They note that a main driver of the discrepancy between septic and aseptic revision may be the reimbursement for the second stage of the former procedure using CPT 27447 instead of a revision procedure code (27487).

We know that an increase in revision TKAs (both septic and aseptic) is expected as the number of primary TKA procedures continues to rise. If reimbursement doesn’t keep pace, it is likely to drive certain surgeons away from tackling the sometimes difficult cases, in turn, leaving our patients with fewer available resources when faced with PJI.

Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media

Better TKA Outcomes When Depression Is Addressed

In the past decade, we’ve learned through a multitude of studies that patient factors can have a substantial impact on the outcomes of orthopaedic interventions. Medical comorbidities, body habitus, and level of fitness are just a few factors we have evaluated. We also now better understand the impact of socioeconomic status and education level on access to care and the results of that care. And importantly, contemporary research is giving us a more complete picture of the relationship between a patient’s mental status and functional outcomes.

Geng et al. provide further insight into this relationship in a recent JBJS report. In a randomized controlled trial conducted at their institution in the People’s Republic of China, the authors investigated whether psychological intervention for patients with depression improved outcomes of total knee arthroplasty (TKA). Among 600 patients prospectively screened, 53 were identified with depressive disorders; 49 remained in the final analysis (24 randomized to standard TKA care and 25 randomized to perioperative psychotherapeutic interventions administered by a mental health professional). Those in the intervention group not only had a significantly higher rate of satisfaction compared with the control group, but they also showed greater improvements in functional outcome scores, range of motion, and scores on depression scales.

As Pablo Castañeda, MD emphasizes in a related Commentary on this article, “Total knee replacement cannot be seen as an isolated intervention without considering the many other factors that contribute to outcomes.” I know that mental health concerns—especially depression—can be difficult to identify during all-too-brief orthopaedic consultations with patients. But they will reap important benefits if we learn to better recognize depression, engage patients in conversations related to mental health, and team with our mental health colleagues for referrals and support. The study by Geng et al. points to a model of care with potential for wider adoption. Considering our community of highly motivated orthopaedic surgeons who are dedicated to the holistic welfare of patients, I believe it is possible to raise our skills in this area close to the level of our ability to examine a knee radiograph.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

Trimming the Fat (Pad) in Knee OA

This post comes from Fred Nelson, MD, an orthopaedic surgeon in the Department of Orthopedics at Henry Ford Hospital and a clinical associate professor at Wayne State Medical School. It has been sent to >3,000 members of the Orthopaedic Research Society (ORS). For more information about the ORS, visit http://www.ors.org

The knee joint is comprised of cartilage, fibrocartilage, bone, synovium, ligaments, a fibrous capsule, and adipose tissue, the last of which includes the large anterior infrapatellar fat pad (IFP). The role of synovial inflammatory cells and cytokines in knee osteoarthritis (OA) has been well studied. The IFP is also rich in stem cells and inflammatory cells. Because Hartley guinea pigs naturally develop a form of knee OA that is similar to human disease, researchers recently used them as a model for elucidating a possible role of the IFP in knee OA.1

Ten 3-month-old guinea pigs had a unilateral IFP excision from one knee, with sham surgery performed on the opposite knee. Hartley guinea pigs typically develop OA after three months, and this intervention sought to determine whether IFP excision protected against OA. Gait analysis data were collected prior to surgery and then monthly until the animals were harvested at 7 months of age, at which point researchers performed microcomputed tomography (microCT) and histopathology on all 20 knee joints.

In knees with IFP resection, fibrous connective tissue replaced the adipose tissue. Stride length was not statistically different for either hindlimb throughout the study. Joints with resected IFPs had a decreased microCT score compared to contralateral intact knees (p <0.0001), indicating healthier cartilage. Histopathologically, the mean modified Mankin score of knees with IFPs removed was 2.556 versus 12.56 in contralateral knees (p <0.0004).

Surgeons commonly resect the fat pad during reconstructive knee surgery in humans, with no known reports of adverse effects beyond decreased range of motion due to local fibrosis. A recent review of the contribution of the IFP and synovium to knee OA pain2 suggests that synovial tissue and adipose tissue may act as a “functional unit” and have a combined effect on OA pathogenesis and, in all probability, OA pain and progression.

References

  1. Afzali MF, Radakovich LB, Pixler ZC, Campbell MA, Sanford JL, Marolf AJ, Donahue T, Santangelo, Kelly S. Early removal of the infrapatellar fat pad beneficially alters the pathogenesis of primary osteoarthritis in the Hartley guinea pig ORS 2020 Annual Meeting Paper No.0166
  2. Belluzzi E, Stocco E, Pozzuoli A, Granzotto M, Porzionato A, Vettor R, De Caro R, Ruggieri P, Ramonda R, Rossato M, Favero M, Macchi V. Contribution of Infrapatellar Fat Pad and Synovial Membrane to Knee Osteoarthritis Pain. Biomed Res Int. 2019 Mar 31;2019:6390182. doi: 10.1155/2019/6390182. eCollection 2019.PMID: 31049352

Outpatient Knee/Hip Arthroplasty Yields Fewer Adverse Events

The National Surgical Quality Improvement Program (NSQIP) database contains more than a half-million records of patients who received a total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), or total hip arthroplasty (THA) from 2009 through 2018. Fewer than 4% of those procedures were done in an outpatient setting, but patient demand for outpatient arthroplasty is rising rapidly.

With retrospective data like that from NSQIP, the most meaningful comparisons between inpatient and outpatient procedures come through a propensity score-matched analysis. Propensity score matching pairs up patients in each group according to multiple factors thought to influence outcome. In a recent study in The Journal of Bone & Joint Surgery, Lan et al. used propensity score matching to compare inpatient and outpatient arthroplasty in terms of adverse events and readmissions.

What the Researchers Did:

  • Matched each outpatient case of TKA, UKA, and THA from the database with 4 unique inpatient cases based on age, sex, ASA class, race, BMI, type of anesthesia, and history of hypertension, smoking, congestive heart failure, and diabetes
  • Compared inpatient vs outpatient rates of 30-day adverse events (both minor and severe) and readmissions
  • Identified risk factors for adverse events and readmissions

What the Researchers Found:

  • For all 3 arthroplasty types, patients who underwent an outpatient procedure were less likely to experience any adverse event, when compared with those who underwent an inpatient procedure.
  • The above adverse-event findings held true when TKAs, UKAs, and THAs were analyzed separately.
  • Outpatient procedure status was an independent protective factor against the risk of adverse events.
  • For all 3 procedures, readmission rates were similar among inpatients and outpatients. (The 2 most common reasons for readmission were infections and thromboembolic events.)
  • Clinicians are probably (and reasonably) selecting healthier patients to undergo outpatient procedures, but 42% of the outpatient cohort had an ASA class ≥3, and 55% had a BMI ≥30 kg/m2.

In their abstract, the authors cited “increased case throughput” as one rationale for outpatient arthroplasty, but this study provides convincing evidence that adverse-event reduction is another compelling reason for certain patients to consider outpatient knee and hip procedures.

Better 24-Hour Pain Control with Periarticular vs. IV Steroids in TKA

Corticosteroids are commonly used in total knee arthroplasty (TKA) to reduce pain and prevent nausea. But are the effects of steroids different when administered locally rather than systemically? Hatayama et al. investigate this question in JBJS, where they report on a randomized controlled trial comparing periarticular injection with intravenous (IV) administration of corticosteroids. The authors assessed the drugs’ effects on pain control, the prevention of postoperative nausea, and inflammation and thromboembolism markers following TKA.

The 100 included patients were 50 to 85 years of age and underwent primary, unilateral TKA for osteoarthritis. Fifty patients were randomized to the intravenous group (10 mg dexamethasone IV 1 hour pre- and 24 hours postoperatively, along with periarticular placebo injection during the procedure), and 50 were randomized to the periarticular injection group (a 40-mg injection of triamcinolone acetonide during surgery, along with IV placebo 1 hour pre- and 24 hours postoperatively).

Patients in the periarticular injection group experienced better pain control at 24 hours postoperatively, both at rest and during walking. The antiemetic effect was similar and notable in both groups. The IV group showed a better anti-thromboembolic effect, as measured by prothrombin fragment 1.2 levels, but the incidence of deep venous thrombosis was low overall, each group having only 2 cases.

The authors also reported that, at 24 and 48 hours, interleukin-6 levels did not differ between the groups, while C-reactive protein (CRP) levels were significantly lower in the IV group. In contrast, 1 week after surgery, patients in the periarticular group had a significantly lower CRP. These inflammatory-marker findings lead Hatayama et al. to postulate that “the better [24-hour] pain control in the periarticular injection group was not because of reduced inflammation,” and they note that locally administered corticosteroids directly inhibit signal transmission in nociceptive fibers.

Accuracy of Rapid Alpha Defensin Test Confirmed

In June 2019, OrthoBuzz reported on the FDA approval of a rapid, lateral-flow alpha defensin test that helps detect periprosthetic joint infections (PJIs) from synovial fluid. In the January 20, 2021 issue of The Journal of Bone & Joint Surgery, Deirmengian et al. report findings from the Level II diagnostic-accuracy study that led to this FDA approval.

The authors compared diagnostic sensitivity and specificity of the lateral-flow alpha defensin test with the “gold-standard” PJI diagnostic criteria endorsed by the Musculoskeletal Infection Society (MSIS) in 2013. They made the comparison with 2 groups: a prospective patient cohort of 305 patients with a failed hip or knee arthroplasty (57 of whom were determined by MSIS criteria to have a PJI) and among a “control” cohort of 462 synovial fluid samples (65 of which met MSIS criteria for PJI).

After excluding 17 patients from the prospective cohort who had grossly bloody aspirates, the authors found a sensitivity of 94.3% and a specificity of 94.5% for the lateral-flow test in that group. Among the control cohort, the lateral-flow test’s sensitivity was 98.5% and its specificity was 98.2%. Furthermore, after combining data from the 2 cohorts, Deirmengian et al. found no performance difference between the lateral-flow test (which yields results in 10 to 15 minutes) and the lab-based alpha defensin ELISA test (which typically yields results in 24 hours). Finally, in a nonstatistical descriptive comparison between the 2 alpha defensin tests and 4 other individual lab tests used in the MISI criteria to diagnose PJI (such as synovial fluid white blood cell count and erythrocyte sedimentation rate), the authors concluded that “alpha defensin tests led to the highest raw number of correct diagnoses (accuracy).”

The 2018 International Consensus Meeting on Orthopaedic Infections included alpha defensin as a minor criterion. That decision, along with these findings and the FDA approval of the lateral-flow test, should lead to increased adoption of the rapid test—and to more data being published on its clinical utility.

What’s New in Adult Reconstructive Knee Surgery 2021

Every month, JBJS publishes a review of the most pertinent and impactful studies published in the orthopaedic literature during the previous year in 13 subspecialties. Click here for a collection of all such OrthoBuzz specialty-update summaries.

This month, author Michael J. Taunton, MD summarizes the 5 most compelling findings from the 130 studies highlighted in the January 20, 2021 “What’s New in Adult Reconstructive Knee Surgery.”

Waiting for a Knee Replacement
–Patient wait times for joint arthroplasty, exacerbated in many places by the COVID-19 pandemic, continue to increase. As measured by the EQ-5D, the health among 12% of 2,168 patients awaiting total knee arthroplasty (TKA) in a recent cross-sectional analysis was rated as “worse than death.”1 Joint-specific function and various comorbidities were associated with these findings.

UKA vs TKA
–The multicenter randomized TOPKAT trial2 compared unicompartmental knee arthroplasty (UKA) with TKA for treating medial compartment osteoarthritis. At the 5-year follow-up, there was no between-group difference in Oxford knee scores, but UKA was more cost-effective and provided an additional 0.24 quality-adjusted life year.

Perioperative Patient Optimization
–An observational study analyzing >1,000 total joint arthroplasties3 found that implementing a “perioperative orthopaedic surgical home”—a surgeon-led screening and optimization initiative targeting 8 common modifiable comorbidities—resulted in a 1.6% 30-day readmission rate (versus 5.3% among patients not involved in the initiative).

Pain Management and Opioids
–A randomized controlled trial of >300 patients undergoing primary total knee or hip arthroplasty4 demonstrated that reducing the number of 5-mg oxycodone pills prescribed at discharge from 90 to 30 resulted in the following findings 30 days postoperatively:

  • Similar between-group pain scores
  • No between-group differences in patient-reported outcomes
  • Significant reductions in unused opioid pills and in pain pills taken in the 30-pill group

Periprosthetic Joint Infection
–Patients undergoing primary TKA who had a history of periprosthetic joint infection (PJI) in another joint had a significantly higher risk of PJI after the primary TKA, compared with the risk among a matched cohort with no history of PJI.5

References

  1. Scott CEH, MacDonald DJ, Howie CR. ‘Worse than death’ and waiting for a joint arthroplasty. Bone Joint J.2019 Aug;101-B(8):941-50.
  2. Beard DJ, Davies LJ, Cook JA, MacLennan G, Price A, Kent S, Hudson J, Carr A, Leal J, Campbell H, Fitzpatrick R, Arden N, Murray D, Campbell MK; TOPKAT Study Group. The clinical and cost-effectiveness of total versus partial knee replacement in patients with medial compartment osteoarthritis (TOPKAT): 5-year outcomes of a randomised controlled trial. 2019 Aug 31;394(10200):746-56. Epub 2019 Jul 17.
  3. Kim KY, Anoushiravani AA, Chen KK, Li R, Bosco JA, Slover JD, Iorio R. Perioperative orthopedic surgical home: optimizing total joint arthroplasty candidates and preventing readmission. J Arthroplasty.2019 Jul;34(7S):S91-6. Epub 2019 Jan 18.
  4. Hannon CP, Calkins TE, Li J, Culvern C, Darrith B, Nam D, Gerlinger TL, Buvanendran A, Della Valle CJ. The James A. Rand Young Investigator’s Award: large opioid prescriptions are unnecessary after total joint arthroplasty: a randomized controlled trial. J Arthroplasty.2019 Jul;34(7S):S4-10. Epub 2019 Feb 4.
  5. Chalmers BP, Weston JT, Osmon DR, Hanssen AD, Berry DJ, Abdel MP. Prior hip or knee prosthetic joint infection in another joint increases risk three-fold of prosthetic joint infection after primary total knee arthroplasty: a matched control study. Bone Joint J.2019 Jul;101-B(7_Supple_C):91-7.

When Does I&D Beat 2-Stage Exchange in Second rTKA?

It’s hard to contemplate “conservative treatment” in the case of a revised total knee arthroplasty (rTKA) with extensive instrumentation that needs a reoperation due to periprosthetic joint infection (PJI), because all the treatment options in that scenario are pretty complex. In the January 6, 2021 issue of JBJS, Barry et al. report on a retrospective review of 87 revisions of extensively instrumented rTKAs that found that irrigation and debridement (I&D) with chronic antibiotic suppression was as effective as 2-stage exchange in preventing another reoperation for infection—and more effective in terms of maintaining knee function.

The average follow-up of the cases studied was 3.2 years, and the authors carefully defined “extensive instrumentation.” Among the 56 patients who were managed with I&D and suppression and the 31 who were managed with the initiation of 2-stage exchange (average age in both groups approximately 67 years), no significant differences were found in the rates of reoperation for infection or mortality. However, 9 of the 31 patients (29%) in the 2-stage group never underwent the second-stage reimplantation. Among those 9, 3 died prior to reimplantation and 2 underwent amputation due to failure of infection control.

Moreover, at the time of the latest follow-up, a significantly higher percentage of patients in the I&D group were ambulatory (76.8% vs 54.8% in the 2-stage group) and were able to functionally bend their knee (85.7% vs 45.2% in the 2-stage group). The authors surmise that these 2 findings are related to the soft-tissue damage and bone loss that typically occur during stage-1 removal of rTKA components.

Barry et al. conclude that in similar situations “deviating from the so-called gold standard of 2-stage exchange and accepting the modest results of I&D may be in the best interest of the patient,” as long as there are no loose implants in the existing construct. But the “sobering” mortality rates in the study (39.3% in the I&D group and 38.7% in the 2-stage group) remind us that this clinical scenario is extremely challenging for patients and surgeons, no matter which option is selected.

Click here to view an “Author Insights” video about this study with co-author Jeffrey Barry, MD.