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Diagnosing Infection in “Dry” Prosthetic Joints

Despite a bevy of research and intense clinical focus, definitively diagnosing periprosthetic joint infections (PJIs) remains a major challenge in many patients. There is no single test that can confirm a PJI diagnosis with absolute accuracy, and surgeons often encounter clinical factors that make the diagnostic challenge even more complex. One such scenario is when a surgeon cannot aspirate enough fluid for culture from the affected joint of a patient who may have a PJI. In such situations, important microbiological data that would come from culturing synovial fluid are unavailable, leaving treating surgeons information-poor.

In the June 5, 2019 issue of The Journal, Li et al. provide surgeons with data about a controversial solution to this so-called “dry-tap” problem. The lead author performed aspirations on nearly 300 joints that were suspicious for periprosthetic infection. Eighty-two of those aspirations (29%) yielded ≤1.0 mL of synovial fluid. In those “dry-tap” cases, 10 mL of saline solution was injected into the joint, which was then reaspirated.

When comparing cultures from the aspirates that were the result of a saline lavage to those in which no lavage was performed, the authors found overlapping 95% confidence intervals in sensitivity, specificity, positive predictive value (PPV), and negative predictive value. However, the specificity (0.991 vs 0.857) and PPV (0.987 vs 0.889) were higher in the nonlavage cohort, even if those differences did not reach statistical significance. In addition, no significant differences were found between the groups in terms of relative frequencies of specific pathogen types.

Although the authors conclude that this lavage-and-reaspiration technique “is not necessarily inappropriate,” it is important to note that no post-hoc power analysis was performed, and therefore type II error needs to be considered because the study was probably underpowered. In addition, the International Consensus Meeting (ICM) recommends against lavaging a “dry” joint to obtain fluid for culture, largely because the injected saline will dilute results if a leukocyte esterase strip test or cell count is subsequently performed as part of the PJI-diagnosis process. Still, the authors point out that the data supporting the ICM’s recommendations against this practice are relatively weak, and the specificity and sensitivity data from this study are quite satisfactory.

So does this give us another option for determining whether a periprosthetic joint infection is present in patients from whom little or no synovial fluid can be obtained? Maybe. But this technique requires further investigation before it becomes widely implemented in practice. Without validation, it risks becoming just one more variable that could reinforce our own confirmation biases in these challenging cases. With further validation, however, it could allow pre-revision collection of valuable and accurate culture information from “dry” joints.

Chad A. Krueger, MD
JBJS Deputy Editor for Social Media

FDA Approves Rapid Alpha-Defensin Test for PJI

The US FDA has approved the Synovasure Alpha Defensin Lateral Flow Test Kit for helping detect periprosthetic joint infection (PJI) in the synovial fluid of patients being evaluated for revision joint replacement.

Alpha defensins are proteins released by neutrophils in early response to infection. OrthoBuzz previously summarized a 2018 JBJS study that found this rapid alpha defensin test to have 96.9% overall accuracy.

In the FDA news release about the approval, Tim Stenzel, MD, director of the FDA’s Office of In Vitro Diagnostics and Radiological Health, said the test provides health care professionals with additional information that “could potentially reduce patient risk by avoiding unnecessary revision operations for replacement joints.”

In a Commentary on the 2018 JBJS study, Garth Ehrlich, PhD and Michael Palmer, MD said the device is a “substantive advance,” but not “a panacea.” For one thing, metallosis would still need to be ruled out with MRI, because that noninfectious etiology triggers a false-positive result with this rapid test. Synovasure is also likely to miss detection of slow-growing, chronic bacterial pathogens such as Proprionibacterium acnes, the commentators said.

The Synovasure test kit received approval through the FDA’s de novo premarket pathway, which is reserved for “low- to moderate-risk devices of a new type,” according to the agency.

Meniscal Extrusions: Imaging and Repair

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. Some of Dr. Nelson’s tips go out weekly to more than 3,000 members of the Orthopaedic Research Society (ORS), and all are distributed to more than 30 orthopaedic residency programs. Those not sent to the ORS are periodically reposted in OrthoBuzz with the permission of Dr. Nelson.

Loss of hoop stress by either medial or lateral menisci can cause meniscal extrusion, which results in increased forces on articular cartilage. The degree of meniscal extrusion is typically measured as a 2-dimensional distance with MRI. However, investigators recently used 3-D MRI to analyze the relationship between medial meniscal extrusion (MME) and femoral cartilage change in patients with these tears.1

Fifteen males (mean age of 56 years) with a medial meniscal degenerative tear (grade 3 by the Mink classification) based on MRI were included. The cartilage area was reconstructed in 3-D, and the femoral cartilage was projected in 2-D by 3-D MRI analysis. The femoral cartilage of the femorotibial joint was divided into 4 segments, and the cartilage area ratio was defined as the ratio of cartilage with thickness ≥1.0 mm in each segment. The tibial MME area (mm2) and volume (cm3), excluding osteophytes, were measured by 3-D MRI.

The projected cartilage area ratio (cartilage thickness ≥1.0 mm) at the posteromedial segment was lower than the ratio at the other 3 segments. The cartilage area ratio at the posteromedial segment was not correlated with the MME distance measured by the 2-D MRI, but it was negatively correlated with MME area (r=-0.53, p=0.045) and MME volume (r=-0.62, p=0.016) as measured by 3-D MRI. Overall, the 3-D imaging more accurately reflected cartilage damage.

Both radial tears and posterior horn degeneration can lead to meniscal extrusion. When this injury is seen acutely in younger persons, repairs are often attempted. Recently efforts have been made to do repairs in older individuals. The use of cell-seeded nanofibrous scaffolds to repair radial tears and resulting hoop-structure injuries has been studied for prevention of articular cartilage degeneration using a rabbit model.2

Synovial mesenchymal stem cells were isolated and expanded into sheets that were then wrapped onto poly(e-caprolactone) scaffolds to create stable cell/scaffold tissue-engineered constructs (TECs). Scaffold-alone or TEC + scaffold constructs were then sutured into created radial meniscal defects (12 rabbits in each group).

The TEC-scaffold group maintained the structure of the hyaline cartilage with matrix staining with Safranin O up to 12 weeks after surgery. Although the cartilage coverage decreased in both groups, the TEC-scaffold group did not become significantly worse over time, suggesting stabilization of hoop structure integrity. Only the TEC-scaffold group showed repair tissue that exhibited positive Safranin O staining in the inner zone of the meniscus.

Future studies will be required to determine the role of tissue engineering in the preservation of meniscal coverage in the face of radial tears.

References

  1. Suzuki S, Ozeki N, Kohno Y, Mizuno M, Otabe K, Katano H, Tsuji K, Suzuki K, Itai Y, Masumoto J, Koga H, Sekiya I. Medial meniscus extrusion (MME) area and MME volume determined by 3D-MRI are more sensitive than MME distance determined by 2D-MRI for evaluating cartilage loss in knees with medial meniscus degenerative tears. ORS 2019 Annual Meeting Poster No. 0514.
  2. Shimomura K, Rothrauff BB, Hart DA, Hamamoto S,  Kobayashi M,  Yoshikawa H, Tuan RS, Nakamura N. Enhanced Repair of Meniscal Hoop Structure Injuries Using An Aligned Electrospun Nanofibrous Scaffold Combined with a Mesenchymal Stem Cell-derived Tissue Engineered Construct. ORS 2019 Annual Meeting Poster No. 0519.

NYT Cites Hype of Stem-Cell Treatments for Joint Problems

An active, 71-year old man who declined joint replacement in favor of stem-cell treatment is quoted in a recent New York Times article as saying, “They’re really quick to try to give you fake joints and make a bunch of money off you.” But the NYT article goes on to suggest that making money may be the main objective of some of the many hundreds of clinics that have sprung up around the US to offer cell-based injections to people with aging or damaged joints who want relief without surgery.

The article points out that the FDA has “taken an industry-friendly approach toward companies using unproven cell cocktails” and that the scant scientific evidence about these treatments, which include injections of platelet-rich plasma, is inconclusive.

For OrthoBuzz readers who want to dive more deeply into the scientific underpinnings (or lack thereof) related to cell therapies for joint problems, please peruse the following JBJS and JBJS Reviews articles, which have been made openly available for a limited period of time:

The main message running through all these articles is this: Effective clinical assessment and safe, optimized use of cell-based therapies demands greater attention to study methods; standards for cell harvesting, processing, and delivery; and standardized reporting of clinical and structural outcomes.

VTE Prevention: Is Aspirin Really That Good?

OrthoBuzz occasionally receives posts from guest bloggers. In response to a three recent studiesthe following commentary comes from Jeffrey B. Stambough, MD.

Throughout the last decade, we’ve experienced a boom in anticoagulation options to help prevent venous thromboembolism (VTE) associated with orthopaedic procedures. The use of aggressive anticoagulation, such as warfarin and various heparin formulations, is being questioned, largely due to concerns about bleeding risks and wound complications.  Along with the newer direct oral anticoagulants such as rivaroxaban, over-the-counter aspirin (ASA) is gaining prominence as an anticoagulant due to its high efficacy, low cost, convenience for patients, favorable side-effect profile, and cardioprotective attributes.  Current guidelines include the use of all these thromboprophylactic agents, but three recent studies lend credence to using aspirin as the primary VTE prophylactic agent when performing total joint arthroplasty (TJA).

In a  March 20, 2019 JBJS study analyzing >31,000 TJAs performed at a single institution over 17 years, Rondon et al. found a 3-fold lower 30-day and 2-fold lower 1-year mortality rate in patients receiving ASA (81mg or 325 mg twice daily), compared to those who received non-aspirin thromboprophylaxis (mainly warfarin).  No mortality differences were noted between the two ASA dosing regimens.  While investigating specific causes of death, the authors discovered that the primary cause of death in the non-ASA cohort was cardiac related at all time points.

A second study, from the April 3, 2019 JBJS, looked into the effects of 3 antithrombotic agents on symptomatic VTE rates and periprosthetic infections in high-risk patients undergoing primary or revision TJA.  When compared to the two more potent agents (warfarin and low-molecular-weight heparin), ASA proved more effective at reducing pulmonary embolism (PE) and VTE rates in high-risk patients, and it was also associated with lower rates of periprosthetic joint infection when compared with warfarin.  Thus, it seems that even in patients deemed to be higher risk for developing VTE, ASA may be a safe, effective option.

Lastly, Runner et al. gleaned VTE prophylaxis data from >22,000 TJA cases submitted by surgeons sitting for Part 2 of ABOS between 2014 and 2016.  The findings, reported in the April 2019 issue of the Journal of Arthroplasty, showed similar trends to those seen in the two previously mentioned studies: Mild (distal or superficial deep vein thrombosis [DVT]), moderate (nonfatal PE, proximal DVT) and severe (fatal PE) VTE events, as well as death, were significantly less frequent in those who received ASA compared to more aggressive agents (heparin or one of its analogs, direct oral agents, or warfarin). Also, patients who received ASA with or without mechanical prophylaxis had significantly lower complication rates (95.5% vs. 93.0%, p<0.001).

One firmly held dogma in medicine is that patients who are at higher risk for VTE should be treated with stronger anticoagulation medications. However, these 3 studies support the idea that less aggressive anticoagulation medication (specifically, low-dose aspirin) may be the more effective and safer option for most patients. In our ongoing quest to improve patient outcomes and mitigate risk around the TJA episode, we should consider using aspirin for thromboprophylaxis unless there is an explicit contraindication in a specific patient.

However, we should also keep in mind that these three studies have the common limitations of all retrospective analyses. Recent randomized trials have shown aspirin to be “noninferior” to other anticoagulants for VTE prevention, and in less than 2 years, we should have even more definitive answers to this question from the randomized, multicenter PEPPER trial, with its estimated 25,000 participants.

Jeffrey B. Stambough, MD is an orthopaedic hip and knee surgeon, an assistant professor of orthopaedic surgery at University of Arkansas for Medical Sciences, and a member of the JBJS Social Media Advisory Board.

Diagnosing PJI: When The “Urine Dipstick” Outperforms Conventional Labs

Despite what seems like a new, high-quality study being published on the topic every week or so, orthopaedic surgeons still have an extremely hard time determining whether a prosthetic hip or knee is infected or not. We have an array of available tests and the relatively easy-to-follow criteria for a periprosthetic joint infection (PJI) from the Musculoskeletal Infection Society (MSIS), but a large number of these patients still fall into the gray zone of “possibly infected.” This predicament is especially thorny in patients who received antibiotics just prior to the diagnostic workup, which interferes with the accuracy of many tests for PJI.

In the April 17, 2019 issue of The Journal, Shahi et al. remind orthopaedic surgeons about a valuable tool that can be used in this scenario. Their retrospective study looked at 121 patients who had undergone revision hip or knee arthroplasty due to an MSIS criteria-confirmed periprosthetic infection. Shahi et al. sought to determine which diagnostic tests were least affected by prior antibiotic administration. The authors found that erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) level, synovial white blood cell (WBC) count, and polymorphonuclear neutrophil (PMN) percentage were all significantly lower in the 32% of patients who had received antibiotics within 2 weeks of those tests, compared with the 68% who did not receive antibiotics. The only test that was found not to be significantly affected by the prior admission of antibiotics was the urine-based leukocyte esterase strip test.

Considering the ease and rapidity with which a leukocyte esterase test can be performed and evaluated (at a patient’s bedside, with immediate results), its low cost, and the fact that it is included in the MSIS criteria, these findings are very important and useful. While we would prefer that patients with a possibly infected total hip or knee not receive antibiotics prior to their diagnostic workup, previous antibiotic exposure remains a relatively common scenario. The findings from this study can assist us in those difficult cases, and they add further evidence to support the value and reliability of the easy-to-perform leukocyte esterase test.

Chad A. Krueger, MD
JBJS Deputy Editor for Social Media

What’s New in Sports Medicine 2019

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 OrthoBuzz Specialty Update summaries.

This month, Albert Gee, MD, a co-author of the April 17, 2019 “What’s New in Sports Medicine,” selected the five most clinically compelling findings from among the 30 noteworthy studies summarized in the article.

Anterior Cruciate Ligament (ACL) Reconstruction

–Norwegian researchers randomized 120 patients to undergo either single-bundle or double-bundle ACL reconstruction and followed them for 2 years.1 They found no difference between the 2 techniques in any patient-reported outcome, knee laxity measurements, or activity levels. These results, along with the preponderance of evidence from other comparative trials over the last 5 years, strongly suggest that routine use of 2 bundles to primarily reconstruct a torn ACL adds no clinical benefit over a well-positioned single-bundle reconstruction.

Knee Cartilage Repair

–A randomized study compared long-term patient outcomes after knee cartilage repair using microfracture versus mosaicplasty.2 Included patients had 1 or 2 focal femoral lesions measuring between 2 and 6 cm2. Better outcomes after a minimum of 15 years of follow-up were found in the mosaicplasty group. Although there were only 20 patients in each arm, the Lysholm-score differences between the groups were both clinically important and statistically significant. More patients in the mosaicplasty group than in the microfracture group said they would have the surgery again, knowing their 15-year outcome.

Rotator Cuff

–UK researchers randomized 313 patients with ≥3 months of subacromial pain and an intact rotator cuff who had completed a nonoperative program of physical therapy and injection to 1 of 3 groups: arthroscopic subacromial decompression, diagnostic arthroscopy (“sham” surgery), or no intervention.3 At 6 months and 1 year, all groups demonstrated statistically significant and clinically important improvement, but patient-reported outcome scores were significantly better in both surgical groups compared with the no-treatment group. The data suggest that patients such as these improve over time, regardless of management, but that surgical decompression  may offer a slight benefit over nonoperative management because of the placebo effect.

–A randomized controlled trial investigated the effect of a formal preoperative education program (2-minute video plus handout)4 about postoperative narcotic use, side effects, dependence risk, and addiction potential among >130 patients undergoing arthroscopic rotator cuff repair surgery. The education group consumed 33% less narcotic medication at 6 weeks and 42% less at 12 weeks compared with the control group. Among the more than one-quarter of the patients who had used opioids prior to surgery, those randomized to the education group were 6.8 times more likely than controls to discontinue narcotic use during the study period.

Hip Arthroscopy

–A randomized controlled trial of >300 patients compared hip arthroscopy and “best conservative care” for treating femoroacetabular impingement (FAI).5 Only 8% of patients crossed over from conservative care to the surgical group. The mean adjusted difference in iHOT-33 scores at 1 year was 6.8, in favor of hip arthroscopy. However, adverse events were more frequent in the arthroscopy cohort, and a within-trial economic evaluation suggested that hip arthroscopy was not cost-effective compared with conservative care during the 1-year trial period.

References

  1. Aga C, Risberg MA, Fagerland MW, Johansen S, Trøan I, Heir S, Engebretsen L. No difference in the KOOS Quality of Life Subscore between anatomic double-bundle and anatomic single-bundle anterior cruciate ligament reconstruction of the knee: a prospective randomized controlled trial with 2 years’ follow-up. Am J Sports Med.2018 Aug;46(10):2341-54. Epub 2018 Jul 18.
  2. Solheim E, Hegna J, Strand T, Harlem T, Inderhaug E. Randomized study of long-term (15-17 years) outcome after microfracture versus mosaicplasty in knee articular cartilage defects. Am J Sports Med.2018 Mar;46(4):826-31. Epub 2017 Dec 18.
  3. Beard DJ, Rees JL, Cook JA, Rombach I, Cooper C, Merritt N, Shirkey BA, Donovan JL, Gwilym S, Savulescu J,Moser J, Gray A, Jepson M, Tracey I, Judge A, Wartolowska K, Carr AJ; CSAW Study Group. Arthroscopic subacromial decompression for subacromial shoulder pain (CSAW): a multicentre, pragmatic, parallel group, placebo-controlled, three-group, randomised surgical trial. Lancet. 2018 Jan 27;391(10118):329-38. Epub 2017 Nov 20.
  4. Syed UAM, Aleem AW, Wowkanech C, Weekes D, Freedman M, Tjoumakaris F, Abboud JA, Austin LS. Neer Award 2018: the effect of preoperative education on opioid consumption in patients undergoing arthroscopic rotator cuff repair: a prospective, randomized clinical trial. J Shoulder Elbow Surg.2018 Jun;27(6):962-7. Epub 2018 Mar 26.
  5. Griffin DR, Dickenson EJ, Wall PDH, Achana F, Donovan JL, Griffin J, Hobson R, Hutchinson CE, Jepson M,Parsons NR, Petrou S, Realpe A, Smith J, Foster NE; FASHIoN Study Group. Hip arthroscopy versus best conservative care for the treatment of femoroacetabular impingement syndrome (UK FASHIoN): a multicentre randomised controlled trial. Lancet. 2018 Jun 2;391(10136):2225-35. Epub 2018 Jun 1.

Microbiomes, OA, and Diabetic Foot Ulcers

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. Some of Dr. Nelson’s tips go out weekly to more than 3,000 members of the Orthopaedic Research Society (ORS), and all are distributed to more than 30 orthopaedic residency programs. Those not sent to the ORS are periodically reposted in OrthoBuzz with the permission of Dr. Nelson. 

We hear the term “microbiome” with increasing frequency nowadays. Merriam-Webster’s online dictionary defines it as “a community of microorganisms (such as bacteria, fungi, and viruses) that inhabit a particular environment and especially the collection of microorganisms living in or on the human body.” Two recent studies suggest how the microbiome can affect musculoskeletal health.

Incorporating the term “the arthritis of obesity,” Rochester, New York researchers1 used obese mice with trauma-induced knee osteoarthritis (OA) to provide evidence that there is a “gut-joint connection” in the OA degenerative process. After supplementing the diets of some of the mice with oligofructose (a prebiotic fiber), the authors found reduced systemic inflammation, reduced obesity-associated macrophage migration to the synovium, and suppressed obesity-induced joint-structure changes.

Another recent study investigated the on-body microbiome as it relates to diabetic foot ulcers (DFUs). Despite clinical signs and nonspecific biomarkers of infection, there is no specific and sensitive measure available to monitor or prognosticate the success of foot salvage therapy (FST) in patients with DFUs. These investigators hypothesized that the initial microbiomes of healed versus nonhealed DFUs are distinct and that the changes in the DFU microbiome during FST are prognostic of clinical outcome.2

Twenty-three DFU patients undergoing FST had wound samples collected at 0, 4, and 8 weeks following wound debridement and antibiotic treatment. Eleven ulcers healed and 12 did not. Healed DFUs had a larger abundance Actinomycetales and Staphylococcaceae (p < 0.05), while nonhealed ulcers had a higher abundance of Bacteroidales and Streptococcaceae (p < 0.05).

In the future, assessment of the initial microbiome and monitoring changes in the prevalence of specific microbiome constituents in patients with diabetic foot ulcers may be a clinical tool for predicting treatment response to foot salvage therapy. It’s also conceivable that microbiome analysis could eventually help patients and surgeons decide between FST and amputation.

References

  1. Schott EM, Farnsworth CW, Grier A, Lillis JA, Soniwala S, Dadourian GH, Bell RD, Doolittle ML, Villani DA, Awad H, Ketz JP, Kamal F, Ackert-Bicknell C, Ashton JM, Gill SR, Mooney RA, Zuscik MJ. Targeting the gut microbiome to treat the osteoarthritis of obesity. JCI Insight. 2018 Apr 19;3(8). pii: 95997. doi: 10.1172/jci.insight.95997. [Epub ahead of print] PMID: 29669931, PMCID: PMC593113
  2. MacDonald A, Brodell JD Jr, Daiss JL, Schwarz EM, Oh I. Evidence of differential microbiomes in healing versus non-healing diabetic foot ulcers prior to and following foot salvage therapy. J Orthop Res. 2019 Mar 25. doi: 10.1002/jor.24279. [Epub ahead of print] PMID: 30908702

RF Ablation for Knee Arthritis

Sometimes, patients with painful knee osteoarthritis do not get sufficient pain relief with conservative treatments and do not want (or are not suitable candidates for) arthroplasty. Now, with the advent of genicular nerve radiofrequency ablation (GNRFA), such patients have another option.

As described in a recent issue of JBJS Essential Surgical Techniques, GNRFA has been shown to provide consistent pain relief for 3 to 6 months. Using heat generated from electricity delivered via fluoroscopically guided needle electrodes, the procedure denatures the proteins in the 3 genicular nerves responsible for transmitting knee pain. Although there is a paucity of high-quality studies on the efficacy of this procedure, one study found that, on average, GNRFA led to improvement of >60% from baseline knee pain for at least 6 months.

In the authors’ practice, GNFRA is generally not repeated if it is ineffective the first time, but the procedure has been shown to be safe when administered repeatedly in patients who respond well. Proper positioning of the electrodes is essential, but the authors caution that without ample experience, “it may be difficult to isolate the exact anatomic location of ≥1 of the genicular nerves.”

General anesthesia is not required for the procedure, which is commonly performed by interventional pain specialists. Despite theoretical concerns, no Charcot-type joints have been reported after GNRFA. The authors emphasize, however, that the procedure provides temporary relief at best; it does not eliminate the potential for nerve regrowth and does not alter the arthritic disease process. Even more importantly, GNRFA needs to be studied with higher-level clinical research designs, ideally an adequately powered sham/placebo-controlled randomized trial.

For more information about JBJS Essential Surgical Techniques, watch this video featuring JBJS Editor-in-Chief Dr. Marc Swiontkowski.

Doc, Will My New Joint Outlive Me?

When discussing total joint replacement (TJR) with patients, I and most other surgeons who perform TJRs are invariably asked, “How long will my new hip last?’” or “Will I need to replace this new knee with another one if I live to be 90?” Although these important questions have essentially been studied since the implants and procedures were first developed, precise answers are still hard to come by. That’s largely because many factors can affect the longevity of an implant, including the implant material and design and the patient’s size/weight, activity level, and comorbidities. Also, many patients die before their joints wear out, and their data is often not captured accurately by researchers and registries. It is therefore difficult to give patients anything better than rough-estimate answers.

That is why I was interested to read two recently published systematic reviews in The Lancet. The reviews—one focused on knee replacement and the other on hip replacement—evaluated studies from six different non-US countries with robust joint registries in an effort to answer these “how long” questions. Based on the authors’ pooled analysis of registry data, the reviews found that:

  • Nearly 60% of >215,000 hip replacements lasted 25 years, 70% lasted 20 years, and almost 90% lasted 15 years.
  • The nearly 300,000 total knee replacements evaluated lasted even longer: 82% lasted 25 years, 90% lasted 20 years, and 93% lasted 15 years.

While these data are helpful, they do still not provide specific answers for the many individuals who may not be “standard” patients, and they do not take into account advances in implant designs and materials that have occurred over 25 years. However, as registry data becomes more ubiquitous and robust, especially in the United States with the growth of the American Joint Replacement Registry, I believe these questions will be answered with increased specificity for individual patients.

Chad A. Krueger, MD
JBJS Deputy Editor for Social Media