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In Pursuit of Alternative Antibiotics for Use in PMMA Bone Cement

The incorporation of antibiotics within polymethylmethacrylate (PMMA) has been widely used over recent decades for managing infection following skeletal trauma. Early research helped to clarify which antibiotics in which formulations were potentially clinically effective, with a common application of managing “dead space” following debridement of bone and soft tissue, addressing established infection as well as preventing deep infection. As the microbiology involved in these infections evolves, along with the antibiotics available, we have need for continued research into this important area of orthopaedics.

In the September 15, 2021 issue of JBJS, Levack et al. report on their investigation into the suitability of alternative antibiotics (amikacin, meropenem, minocycline, and fosfomycin) for use in PMMA beads,  with a particular focus on thermal stability and in vitro elution characteristics. Tobramycin was also used to validate the study methodology. Minimum inhibitory concentrations of the antibiotics were tested against S. aureus, E. coli, and Acinetobacter baumannii. Antibiotic-laden PMMA beads of different sizes were tested, with antibiotic elution determined using high-performance liquid chromatography with mass spectrometry.

The authors found that amikacin was comparable to tobramycin with respect to heat stability and elution. Meropenem showed favorable elution kinetics and thermal stability in the initial 7 days.

The investigators emphasize that “The data presented are intended to generate further study of these antibiotics to better identify potential areas of clinical utility,” and they rightly point out that their data are not intended for clinical decision-making, “as antibiotic dosages and in vivo applications, specifically with biofilms, have not been evaluated.”  Nonetheless, these new data involving the characteristics of amikacin and meropenem are intriguing. Moreover, this study serves as a great reminder of the need to regularly reevaluate established therapies as research techniques, pharmacology, and clinical conditions (such as evolving microbial pathogens) continue to change.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

Reducing Intraoperative Breast Radiation Exposure of Orthopaedic Surgeons 

The risk of radiation exposure in the operating room (OR) is of increasing interest to orthopaedic surgeons, and the advent of lead vests and aprons, thyroid shields, and lead glasses have given surgeons wearable protection in the OR. However, recent research has demonstrated that lead vests and aprons do not adequately shield the most frequent site of breast cancer, the upper outer quadrant (UOQ) of the breast, which commonly extends into the axilla.

In the September 1, 2021 issue of JBJS, Van Nortwick et al. report on the efficacy of lead vest supplements in reducing breast radiation exposure. The researchers simulated a standard OR setting, placing an anthropomorphic torso phantom, representing a female surgeon, adjacent to an OR table. Dosimeters were employed, and scatter radiation dose equivalents were measured during continuous fluoroscopy of a pelvic phantom, representing the patient. Using 2 C-arm positions (anteroposterior and cross-table lateral projections), and with the surgeon in 2 different positions (facing the table and perpendicular to it), 5 different configurations were tested:

  • No lead
  • Lead vest
  • Lead vest with wings
  • Lead vest with sleeves
  • Lead vest with axillary supplements (the wing placed on the inferior aspect of the axillary opening)

Across scenarios, the average breast UOQ radiation exposure with the use of a lead vest alone (97.4 mrem/hr) did not differ significantly from that with no lead protection (124.1 mrem/hr). However, compared with lead vest alone, significantly less exposure was seen with the use of sleeves (0.8 mrem/hr) and axillary supplements (1.3 mrem/hr). Wings (59.4 mrem/hr) decreased exposure to a lesser extent than sleeves or axillary supplements (and the difference when compared with lead vest alone was not significant). Also noted, C-arm cross-table lateral projection had higher scatter radiation than the anteroposterior projection, as has been demonstrated in previous studies.

The authors point out that, in creating the axillary supplement, a standard wing was simply attached below the axilla rather than above the shoulder, a novel approach to increasing vest protection. While comfort in using lead sleeves or axillary supplements is important to investigate further, data from this study could help inform vendor design modifications resulting in greater protection from breast radiation exposure, and ideally eliminate the need for surgeons to have to “MacGyver” a solution from existing parts.

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

A downloadable JBJS infographic summarizing this study can be found here.

 

 

Press Ganey Survey in Ambulatory Upper-Extremity Care: Assessing Nonresponse Bias  

Patient surveys are now being widely used by hospital systems to monitor patient satisfaction with the process of inpatient and outpatient musculoskeletal care. While data from the surveys can help guide quality-improvement efforts, many clinicians have some concerns with the survey results in that the patients who respond may not be representative of all patients, and patient-care experiences may differ between survey “responders” and “nonresponders.” 

In the September 1, 2021 issue of JBJS, Weir et al. delve further into this topic in their report on the response rate and factors associated with the completion of the Press Ganey Ambulatory Surgery Survey (PGAS) among patients treated with upper-extremity procedures in their outpatient surgical center. Of the 1,489 included patients, only 13.5% (201 patients) responded to the survey. The authors found significant differences between the responder and nonresponder groups with respect to baseline characteristics, including race (72% vs 57% White in the 2 groups, respectively), education (49% vs 40% with a college degree), employment status (88% vs 79% employed), income (49% vs 34% with income ≥$70,000), and marital status (54% vs 43% currently married).  The responders also had better pre-intervention PROMIS scores across multiple domains, although the authors note that these differences were not clinically meaningful.  

While emphasizing that factors influencing response rates are multifactorial and complex, the authors state that “The existence of substantial differences between responders and nonresponders raises concern for potential nonresponse bias for the PGAS.” They further point out that “surgical centers may be disproportionately missing the experiences of minority groups with lower socioeconomic status, and more focused efforts may be needed to ensure that these patients have equitable care experiences.”  

It seems to me that avenues toward increasing the collection of patient responses might include improved processes for following up with nonresponders using personalized phone calls or emails, or potentially other incentives to collect these data. Survey vendors themselves have a role to play, working with hospital systems to enhance the credibility of these commonly utilized tools. With more inclusive response, providers are likely to be more confident in applying survey feedback to the practice environment, thereby improving the process of care for our patients.  

Marc Swiontkowski, MD
JBJS Editor-in-Chief 

ACL Reconstructions: Who Needs Them? 

Anterior cruciate ligament (ACL) injuries once were career-ending for athletes. With the advent of ACL reconstruction, elite athletes have been able to continue to compete at the highest level. But a question remains regarding recreational athletes and their need for reconstruction following ACL injury. Literature has shown that there are “copers” who are able to deal with an “ACL-deficient” knee, but are these individuals destined to participate in only low-impact activities without cutting and twisting? 

In the latest issue of JBJS, Pedersen et al. shed new light on this important topic, reporting the 5-year outcomes of the Delaware-Oslo ACL Cohort Study, a longitudinal study of patients who had been active in cutting, jumping, and pivoting sports before sustaining a unilateral ACL injury. The original cohort underwent 5 weeks of rehabilitation and then participated in a shared decision-making process to determine their treatment path. Inclusion criteria included involvement in level-I sports (such as soccer, football, handball, or basketball) or level-II activities (such as tennis, skiing, softball, baseball, or gymnastics) at least 2 times per week prior to injury.  

Treatment status at 5 years was known for 262 of the original 276 patients: 167 (64%) underwent early ACL reconstruction, 30 (11%) underwent delayed ACL reconstruction after having tried the path of rehabilitation only, and 65 (25%) opted for progressive rehabilitation alone. The patients who chose progressive rehabilitation alone were significantly older, less likely to participate in level-I sports preinjury, and less likely to have injuries to the medial meniscus compared with patients in the 2 reconstruction groups.  

Interestingly, at 5 years, no significant differences were found between the 3 groups in terms of clinical, functional, or physical activity outcomes as assessed by several measures.   

There were narrow indications for inclusion in the study, including no substantial concomitant knee injuries, and patients needed to have full resolution of acute impairments before being enrolled. That being said, at follow-up, 95% to 100% of patients across groups were still active in some kind of sports. This gives hope to older guys like me that maybe we don’t need to fear an ACL injury ending our weekend careers of showing our kids “how it’s really done.” Maybe former athletes like myself would fall into that group of “copers” who can still be relatively active with an “ACL-deficient” knee? 

Click here for the related JBJS video summary of this article. 

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

Rehabilitation Strategies: Fertile Ground for Prospective Randomized Trials

Approximately 18% of JBJS scientific studies published in 2020 were Level I or II investigations. The number of high-level studies has continued to grow slowly year over year. In terms of randomized controlled trial design, we have found that the facets of care that are often the focus of study are those that are most straightforward—the use of tourniquets, resurfacing the patella with total knee arthroplasty, intraoperative and postoperative drug therapies, as examples. One under-investigated area is rehabilitation, as far as both management strategies post-injury and more detailed, comprehensive post-surgical programs.

In the latest issue of JBJS, Martínez et al. evaluate the question of duration of sling use following proximal humeral fracture in patients managed nonoperatively. This is an important patient centric question that has largely been informed by “hand me down” prescriptions from residency teaching faculty. In a very well-designed Level II trial involving an adult cohort (mean age of 70; range, 42 to 94 years), they found no significant differences in pain and function between patients randomized to 1 week of immobilization versus 3 weeks of immobilization. In addition, no significant difference in the complication rate was found.

Pain was assessed using a visual analog scale at 1 week and 3 weeks after fracture and then at the 3, 6, 12, and 24-month follow-up. Functional outcome was evaluated using the Constant score, and functional disability was evaluated with the Simple Shoulder Test, a self-reported questionnaire; both of these measures were recorded at the 3, 6, 12, and 24-month evaluation. No differences in pain and function at any time point were observed.

Many readers of JBJS have had the experience of patients abandoning the sling as soon as they are comfortable, regardless of what our original instructions were, so the findings of this study are relatable. The authors concluded that, “These fractures can be successfully managed with a short immobilization period of 1 week in order not to compromise patients’ independence for an extended period.”

It strikes me that there are numerous rehabilitation prescriptions that are ripe for evaluation using a randomized design. (Wear an orthosis when sleeping? Keep it on at all times or only when walking? Etc.) Let’s get after these questions in the manner of Martinez et al. as we seek to give our patients solid evidence to back our instructions.

A downloadable JBJS infographic regarding this study can be found here.

Marc Swiontkowski, MD
JBJS Editor-in-Chief

JBJS Essential Surgical Techniques Awards

JBJS Essential Surgical Techniques (EST) and The Journal of Bone and Joint Surgery (JBJS) give out two annual awards–one for the best Subspecialty Procedure (SP) video article, and the other for the best Key Procedures (KP) video article published during each calendar year.  

We are pleased to spotlight the 2020 Award Winners: 

Editor’s Choice Subspecialty Procedures Award 

Minimally Invasive Sacroiliac Joint Fusion: A Lateral Approach Using Triangular Titanium Implants and Navigation
by David W. Polly Jr., MD, and Kenneth J. Holton, MD 

Editor’s Choice Key Procedures Award 

Computerized Navigation: A Useful Tool in Total Knee Replacement
by Oystein Gothesen, MD, PhD; Oystein Skaden, MD; Gro S. Dyrhovden, MD; Gunnar Petursson, MD, PhD; and Ove N. Furnes, MD, PhD 

Both articles are freely available online. 

Submissions for the 2021 EST Awards are currently being accepted. 

Mental Health Phenotypes and Patient-Reported Outcomes in Upper-Extremity Care   

Pain is a remarkable and, at times, poorly understood concept. There has been extensive research showing that patients with the same conditions can experience pain differently and that pain and activity intolerance simply can’t be explained by biomedical factors alone. We have all seen examples in our own clinics as surgeons, how 2 individuals with the same pathology and treatment can have different perceived outcomes.

In the current issue of JBJSMiner et al. explore this very topic in a prospective, cross-sectional study in which they used cluster analysis to identify mental health phenotypes (combinations of various types of misconceptions—unhelpful thoughts or cognitive biases—and symptoms of anxiety or depression) that could potentially help to direct care. A total of 137 adult patients seeking upper-extremity musculoskeletal care completed a survey that included demographics and mental health questionnaires (3 regarding unhealthy thoughts about pain and 2 addressing psychological distress) along with measures of upper-extremity-specific activity tolerance, pain intensity, and pain self-efficacy.

Through a clustering algorithm, 4 mental health phenotypes were identified in the study population:

  • Low misconceptions, low distress (77 patients)
  • Notable misconceptions (36 patients)
  • Notable depression and notable misconceptions (19 patients)
  • Notable anxiety, depression, and misconceptions (5 patients)

The authors observed significant differences in activity tolerance, pain intensity, and pain self-efficacy based on mental health phenotype. Specifically, patients with low misconceptions and low distress had significantly greater activity tolerance and pain self-efficacy than those with notable misconceptions, notable symptoms of depression, and notable psychological distress. Patients with low misconceptions and low distress also had significantly lower pain intensity than those with notable symptoms of depression and notable symptoms of anxiety.

The authors did not find an association between phenotypes and socioeconomic status, as measured by participants’ zip code (used to calculate the home area deprivation index). In addition, they found no difference between phenotypes in terms of discrete traumatic conditions (35% of patients), discrete nontraumatic conditions (47%), and nonspecific diagnoses (18%), although they caution that they may not have had enough balance to detect differences based on diagnostic category.

As surgeons, we must consider psychological factors when counseling our patients. As the authors note, “musculoskeletal specialty and pre-specialty care units can benefit from strategies that anticipate mental and social-health opportunities.” As we increase our understanding of the interplay between mental and physical health, our patients stand to gain.

Co-author David Ring, MD, PhD shares his perspective on this study in the related Author Insights video, found here.

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

Outpatient Orthopaedic Surgery: Recent Trends in the Medicare Population

The performance of orthopaedic procedures in ambulatory surgery centers (ASCs) continues to increase in the US. This practice is accelerating for multiple reasons: patients want to sleep in their own beds, hospitals can present a risky environment for nosocomial infection, inpatient surgical care is more costly, and some surgical teams find greater efficiency functioning in high-volume outpatient surgery centers—to name a few explanations for the shift we’re seeing. Over the last few years it has become clear that, in properly selected patients, certain arthroplasty procedures can be safely performed in the outpatient setting  with high patient satisfaction. Resources can be saved and directed to care that must be delivered in the hospital environment. 

New data on outpatient orthopaedic procedures in the Medicare population are presented in the latest issue of JBJS by Lopez et al., who examined trends in ASC procedure volume, utilization, and reimbursements between 2012 and 2017. They note that: 

  • A total of 1,914,905 orthopaedic procedures were performed at ASCs in the Medicare system during the study period, with an 8.8% increase in annual procedure volume and a 10.5% increase in average reimbursements per case.  
  • Increasing procedure volume was driven significantly by increases in hand procedure volume. 
  • All states but Vermont were found to have ASCs, with most being located in the South (39.8%), followed by the West (26.5%), Midwest (20.1%), and Northeast (13.6%). ASC procedure utilization was strongly associated with metropolitan areas compared with rural areas.  
  • Orthopaedic procedure utilization, including for sports, hand, and spine procedures, was significantly higher in wealthier counties as well as in counties in the South. 

While an analysis of safety was outside the scope of this study, data have been reported elsewhere confirming that safety can be achieved in the outpatient setting. Our community must also address value, paying attention to implant and supply costs to trim waste and conserve resources wherever possible. It is my belief that somewhere around 80% to 85% of all orthopaedic procedures have the potential to be performed in outpatient environments if we expand the indications slowly and carefully along with the practices of regional anesthesia, home nursing care, and after-hours consultative resources to place patients and families at ease with these expanding programs over time.   

Marc Swiontkowski, MD
JBJS Editor-in-Chief 

BMI Differentially Moderates Heritability of THA and TKA for Osteoarthritis

Genetic susceptibility to orthopaedic conditions is of interest to clinicians and patients alike. While the link between genetics and certain pediatric conditions is known, studies of sets of twins are providing new insights into adult issues, such as osteoarthritis, and the impact that genetics may have.

In the current issue of JBJS, Hailer et al. report on an investigation in Sweden in which they analyzed genetic susceptibility to hip and knee osteoarthritis necessitating total hip arthroplasty (THA) or total knee arthroplasty (TKA), and whether body mass index (BMI) moderates the heritability of these outcomes. They linked nearly 30,000 twin pairs with BMI information in the Swedish Twin Registry with the Swedish National Patient Register to identify twins who had undergone THA or TKA with a primary diagnosis of osteoarthritis. Structural equation modeling was then used to calculate the heritability of osteoarthritis treated with THA or TKA and how it related to BMI, age, and sex.

The authors note that, for radiographically defined knee osteoarthritis, previous twin studies have shown that the genetic susceptibility (“the proportion of the variation of a trait that can be attributed to the variation of genetic factors”) is between 0.4 to 0.8. In twin studies using total joint replacement as the outcome, heritability has been estimated to be 0.2 for TKA and 0.5 for THA.

Hailer et al. found that, on average in their cohort, approximately half of the susceptibility to undergo THA or TKA for osteoarthritis was explained by heritability, with similar estimates demonstrated for the 2 procedures: THA, 0.65 (95% CI, 0.59 to 0.70) and TKA, 0.57 (95% CI, 0.50 to 0.64). Of note, heritability decreased with higher BMI in both men and women for THA and in men for TKA. But in women, heritability for TKA increased with higher BMI (0.37 for a BMI of 20 kg/m2 and 0.87 for a BMI of 35 kg/m2).

Although the need for THA or TKA is not a perfect indicator of osteoarthritis (plenty of osteoarthritis does not become symptomatic enough to warrant total joint arthroplasty), this large study offers further data on the question of genetic susceptibility to the development of osteoarthritis. Understanding the influence of obesity (a modifiable risk factor) becomes increasingly important and warrants continued investigation in studies exploring heritability in relation to orthopaedic conditions. 

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

Ten-Year Results of the BIRMINGHAM HIP Resurfacing Implant System 

There have been 3 historic cycles of interest in surface replacement of the hip in the last 40 years. The second cycle occurred in the 1980s into the 1990s, when very high failure rates were reported. Biomaterial and design advancements fueled the most recent cycle of interest, which began 12 to 15 years ago. However, the enthusiasm that occurred at the advent of this most recent cycle ebbed as it became increasingly apparent that patient selection is critical and that the fairly difficult hip resurfacing procedure requires experience to reproducibly place the implants correctly. 

In the latest issue of JBJS,  Su et al. report the 10-year results of the post-market-approval study of the BIRMINGHAM HIP Resurfacing (BHR) implant system, a metal-on-metal system approved by the U.S. Food and Drug Administration in 2006. The study included a cohort of 280 hips (253 patients) undergoing primary BHR procedures across 5 sites. The mean patient age at the time of surgery was 51 years; 74% of the BHRs were implanted in male patients, and 95% of the hips had a diagnosis of osteoarthritis.  

Among the findings: 

  • 10-year survivorship free from all-cause component revision was 92.9%. Among male patients <65 years of age at the time of the procedure, the rate was 96%. 
  • Twenty hips underwent revision (at a mean of 5 years).  
  • Whole-blood cobalt and chromium levels were higher at 1 year after surgery compared with preop levels; they remained stable through 5 years, and then decreased somewhat at 10 years.  
  • Improvements in the EQ-5D visual analogue scale score and Harris hip score were noted at 1 year and were maintained through 10 years.  

These outcomes are encouraging, but as Su et al. point out, the cohort is not representative of typical total hip arthroplasty populations, who tend to be older and include a greater percentage of female patients. Moreover, the surgeons who performed the procedures were all experienced. Patient selection remains key, with younger male patients being the best candidates. Data such as these can help sharpen our focus as we refine arthroplasty concepts for further improvement in patient outcomes. 

For additional perspective on this study, see the commentary by Timothy S. Brown, MD 

Marc Swiontkowski, MD
JBJS Editor-in-Chief