Archive | April 2019

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.

Durability of Constrained Liners in Revision THA

The indications for treating total hip arthroplasty (THA) dislocations by cementing a constrained polyethylene liner into a well-fixed, retained acetabular component at the time of revision are narrow. That’s largely due to concerns about the durability of the resulting acetabular construct. Now, thanks to a study by Brown et al. in the April 3, 2019 issue of JBJS, hip surgeons have some hard data about the long-term outcomes of this approach.

After reviewing 125 cases in which a constrained liner was cemented into a retained, osseointegrated acetabular component during revision THA, with a mean follow-up of 7 years, the authors found that:

  • Survivorship free from revision for instability was 86% at 5 years and 81% at 10 years. The cumulative incidence of instability at 7 years was 18%.
  • Survivorship free from aseptic acetabular component revision was 78% at 5 years and 65% at 10 years. The most common failure mechanism was dissociation of the constrained liner from the retained component.
  • Harris hip scores (HHS) did not improve significantly after revision. This finding is consistent with prior research that shows better post-revision HHS scores in patients whose revisions include the entire acetabular component.
  • Position of the retained cup did not affect implant survivorship or risk of dislocation.

The authors mention alternative strategies for reducing the risk of dislocation after revision THA, such as the use of large-diameter heads and dual-mobility constructs. Still, they conclude that this constrained-liner approach, in the setting of a relatively well-positioned acetabular component, is a viable and durable THA revision option, especially for those “with a compromised abductor mechanism, recurrent instability, [and] a well-fixed and well-positioned acetabular component, for whom an acetabular revision would not be tolerated.”

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

Patient-Specific Instruments’ Effects on TKA Revision

Whenever we introduce new technology or techniques in hopes of improving orthopaedic surgery, at least one of two criteria should be met: The new technology should improve the outcome at a maintained cost, or it should decrease cost while maintaining at least an equivalent outcome. If neither of these conditions is met, we need to think twice about adopting it. To help us answer these “value” questions, we need relevant data. This is why studies such as the one by McAuliffe et al. in the April 3, 2019 issue of The Journal are so important.

The authors use the Australian Orthopaedic Association National Joint Replacement Registry to compare the rate of revision between 3 types of primary total knee arthroplasty (TKA):

  1. Those performed with image-derived instrumentation (IDI, i.e., patient-specific cutting jigs)
  2. Those performed using computer navigation
  3. Those using neither technology

McAuliffe et al. found no significant differences between groups in terms of cumulative percent revision at 5 years. Subgroup analysis revealed a higher rate of revision (hazard ratio [HR] 1.52, p = 0.01) for the IDI group relative to the computer-navigated group when patients were ≤65 years old. In addition, the IDI group had a much higher rate of patellar revision when patients received posterior-stabilized knees (HR of 5.33 when compared with the computer-navigated group, and HR of 4.16 when compared with the neither-technology group).

This study seems to suggest that whatever the benefits of IDI may be in terms of attaining a “proper” mechanical axis during TKA, IDI does not translate into a lower revision rate. And when these revision data are viewed in the face of the added costs associated with IDI, it makes little sense to advocate for the widespread use of this technology for TKA at this time.

While this study focused on TKAs, the take-home message can be extended. Orthopaedic surgery is by nature complex, requiring that multiple steps be performed in harmony to produce an optimal outcome. It is easy for us to focus on (and measure) a couple of key outcome variables and base our opinions of a technique’s or technology’s success on such findings. But when it comes to “novel” techniques and technological “breakthroughs,“ we need a lot of data on many different variables before we can make meaningful conclusions, change our practice, and advise our patients.

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

Clavicle Fracture Research: Enough Already?

Orthopaedic surgeons and their staffs are aware of the paradigm shift that has taken place in the last 10 to 15 years regarding the treatment of clavicle fractures. Interest in the outcome differences between surgical and nonsurgical treatment has grown substantially since the 2007 Canadian Orthopaedic Trauma Society publication in JBJS showed that, relative to nonoperative treatment, plate fixation of displaced midshaft clavicle fractures resulted in improved functional outcomes and fewer malunions in active adult patients. Since that time, The Journal alone has published 14 articles related to management of clavicle fractures. In addition, the orthopaedic literature contains a number of well-conducted meta-analyses on the topic, comparing both nonoperative and surgical treatment as well as different methods of surgical fixation.

So, with all this evidence, why have we published the randomized controlled trial on this topic by King et al. in the April 3, 2019 issue of The Journal? Partly because the authors build upon our knowledge by comparing a relatively new fixation device (a flexible intramedullary locked nail) to a more standard treatment (an anatomically contoured plate). These plate and nail devices are very different from one another in terms of mechanics and surgical technique, and the flexible nail used in this study is much different than the rigid, straight nails or pins that have been used in the past.

A union rate of 100% was observed in both groups, but the authors found that the flexible nail was significantly faster in terms of operative time. (A single surgeon experienced with both devices performed all 72 surgeries.) They also found that the DASH scores between the groups were similar until the 12 month follow-up, at which point the flexible intramedullary nail group had statistically better scores. The authors concede, however, that the 12-month DASH-score difference “might not be clinically relevant.”

There is one other reason why we deemed this article important: The flexible intramedullary device used in this study is substantially more expensive than prior fixation devices that have been shown to effectively treat clavicular fractures. King et al. did not compare device costs, but whenever we study a device that adds to the total cost of care we should attempt to prove that it adds enough patient benefit to warrant the added expense. As the authors conclude, both devices evaluated in this study appear to be effective at treating displaced/shortened clavicular fractures, and there are a number of other factors that both the surgeon and patient should consider (such as surgeon skill and experience and cosmetic results) when deciding which treatment to use.

Marc Swiontkowski, MD
JBJS Editor-in-Chief