Targeted Muscle Reinnervation Helps Reduce—and Prevent—Pain in Amputees
Symptomatic neuromas have long been a problem for amputees, interfering with prosthetic comfort and causing residual pain that often requires treatment. During the last 15 to 20 years, surgeons have used targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) procedures to improve symptoms from neuromas. In TMR, surgeons transfer a mixed or sensory nerve to a “target” transected motor nerve to prevent disorganized axonal growth. RPNI is a less complicated procedure during which the free nerve end is implanted into a denervated free muscle graft, again to decrease disorganized sprouting of axons.
Advances in amputee care at US military centers, driven largely by recent overseas conflicts, have shown anecdotally that TMR and RPNI prevent neuroma formation when used prophylactically during initial amputation, and that they also relieve pain when used as secondary treatment for existing neuromas. In the April 22, 2021 issue of The Journal, Hoyt et al. reviewed records from Walter Reed National Military Medical Center to evaluate changes in pain scores, symptom resolution, and frequency of complications when TMR and/or RPNI were utilized.
The authors analyzed 87 nerve interface interventions in 80 lower extremity amputations that had at least 6 months of follow-up. Fifty-nine of the procedures (68%) were done to treat symptomatic neuromas at a median of 6.5 years after amputation, while 28 procedures (32%) were done for primary prophylaxis. Hoyt et al. found that the sciatic nerve was most likely to develop symptomatic neuromas after amputations at or above the knee, while the tibial and peroneal nerve distributions were most commonly symptomatic after amputations distal to the knee. TMR was utilized alone in 85% of the cases, and surgeons used RPNI most frequently to prevent pain in the sural and saphenous nerves.
Overall, symptom resolution after all procedures was 92% at the final follow-up. VAS pain scores improved from 4.3 to 1.7 points in the delayed-treatment group and did not vary by amputation level. The final mean pain score in the primary-prophylaxis group was 1.0 ±1.9. There were no significant differences in pain outcomes between the primary and delayed groups, but 6 patients in the delayed cohort required revision for residual limb or phantom limb pain. In patients with transtibial amputations, failure to address an asymptomatic tibial nerve during delayed TMR resulted in an increased risk of revision surgery.
Although retrospective in nature, this study shows some encouraging early data to support the primary and secondary use of TMR/RPNI in amputee care. More research is required to determine whether these results in wounded warriors can be replicated in a civilian amputee population.
Click here for a Commentary on this study by Ann R. Schwentker, MD.
Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media
Pediatric Limb-Lengthening: A Cautionary Tale
JBJS Editor-in-Chief Dr. Marc Swiontkowski brought to OrthoBuzz’s attention a recent “Family Partnerships” essay published in Pediatrics. The 4 “speakers” in the essay chronicle the suffering and pain of Lindsay Ellingworth, who was born with a congenital lower-limb deficiency. Lindsay’s young parents opted for limb lengthening over amputation plus a prosthesis after several orthopaedic consultations and an agonizing, confusing decision-making process.
Orthopaedic surgeon Dr. David Hootnick entered the picture about 10 years ago, when he first saw Lindsay, who was by then a young nursing student with ongoing problems associated with the index procedure—including scoliosis and chronic neck and back pain. The extent of the original deformity (30% femur shortening at birth) made Lindsay a “nonideal candidate for lengthening,” says Dr. Hootnick, but he adds that “Lindsay had a normal-appearing foot, making it all the more understandable that her parents balked at removing an apparently healthy part of their beloved child.”
Lindsay describes her limb-lengthening and years of treatments for complications as “a living nightmare.” Now an adult, she has concluded that “the doctors put a pretty bow on limb lengthening.” Pediatrician and bioethicist Dr. Amy Caruso Brown acknowledges in the essay the untenable bind Lindsay’s parents found themselves in when having to make a decision before their child was old enough to express preferences. “It is difficult to accept that a procedure that sounds as drastic and anachronistic as amputation might have fewer complications than the seemingly more sophisticated alternative,” Dr. Brown said.
According to Lindsay’s mother Rene Mauchin, “Although she has endured so much, Lindsay still laughs and celebrates life.” When asked for a takeaway that might help other families in similar situations, Ms. Mauchin said, “You have a right to know everything the doctors know…Don’t hesitate to see several doctors, and ask for evidence to back up their recommendations.”
Young Kids and Lawn Mowers Don’t Mix
Until I completed my pediatric orthopaedics rotation as a resident, I never thought much about pediatric lawn-mower injuries. I don’t recall how many such accidents we cared for during that time period, but I clearly remember one. It was grotesque and life-changing for the child–and definitely avoidable. That recollection was reinforced while I read the epidemiological study by Fletcher et al. in the October 17, 2018 edition of The Journal.
The authors analyzed 20 years of data from their institution in an effort to better understand these horrific injuries. They found two main demographic populations among the 157 patients who sustained mower-related injuries, which were lower-extremity injuries in 84% of all the patients. Those in the younger at-risk population (mean age of 4 years) were frequently injured by (or were passengers on) a riding lawn mower, usually operated by an older family member. This younger cohort had higher injury severity scores and higher amputation rates than the older pediatric population of mower-injured patients (mean age of 15 years). Most of those older patients were hurt while operating the lawn mower themselves. Not surprisingly, the authors found that these patients, whatever their age, underwent an average of almost three operations and spent close to a week in the hospital.
While there are a lot of important epidemiological data points in this article, the most important take-home message is the role that education must play in the prevention of these injuries. As the author state:
Education for the younger population should target the operators (parents, grandparents, older siblings) and emphasize the importance of keeping children out of the yard while lawn mowers are in use. Under no circumstance should a child of any age be the passenger on a lawn mower.
Despite ample literature on lawn-mower injuries, their incidence among pediatric patients has remained largely unchanged. I’m hopeful that this study will prompt more widespread implementation of patient education in this area. The American Academy of Orthopaedic Surgeons has information regarding lawn mower safety, and the Pediatric Orthopaedic Society of North America and the American Academy of Pediatrics are partnering on lawn-mower injury prevention. Accidents cannot be eradicated completely, but the more we avail ourselves of resources such as these—and share them with patients of all ages—the greater the likelihood of preventing these potentially devastating injuries.
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media
Use Data, Guidelines, and Intuition to Manage Infection after Toe/Forefoot Amputation
The number of articles published each year in orthopaedics that evaluate infections seems to approach, if not exceed, 1,000. Yet, despite all of these publications, consensus statements, and guidelines, we seem to have very few concrete recommendations about which every surgeon will say, “This is what needs to be done.” So we send out samples, run cultures, sonicate implants, and sometimes even perform DNA sequencing, and then we mix the data with selected recommendations and intuition to make our final treatment decisions. Foolproof? No, but it is the best we can do in many situations.
The article by Mijuskovic et al. in the September 5, 2018 edition of The Journal helps simplify this type of decision making in the setting of residual osteomyelitis after toe or forefoot amputation. The authors evaluated 51 consecutive patients with gangrene and/or infection who underwent either digit or partial foot amputations. They found that, after surgery, 41% of the patients without histological evidence of osteomyelitis (which the authors considered the reference, “true positive” analysis) had a positive culture from the same sample. In addition, only 12 patients (24%) had both positive histological findings and positive cultures, the criteria set forth by the Infectious Disease Society of America for the definitive diagnosis of osteomyelitis.
As interesting as the main findings of the study are, some of the “minor” results are even more curious. The decision regarding which patients received antibiotics after amputation seemed largely arbitrary, with 10 of the 14 patients who had a positive histological result not receiving any postoperative antibiotics. (Five of those patients ended up needing a secondary procedure.) In addition, because of the need for decalcification prior to analysis, the median time to receiving histological results was almost a week. Based on the findings in this study, in many instances patients are sent home or to a rehabilitation facility with antibiotics based only on the results of a potentially “false-positive” culture.
The authors conclude that their results “cast doubt on the strategy of relying solely on culture of bone biopsy specimens when deciding whether antibiotic treatment for osteomyelitis is necessary after toe or forefoot amputation.” But this paper also highlights the fact that we are still looking for definitive answers about which data to use and which to disregard when it comes to the detection and treatment of post-amputation osteomyelitis. We surgeons decide on which side to err, and we need to appreciate all three facets—data, guidelines, and patient factors—when discussing treatment options with patients.
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media
A Video Approach to Improving Outcomes in Digit Replantation
Arterial and venous reperfusion problems are common causes of failure in digit replantation, so excellent vascular anastomotic technique is crucial during these operations. One way to assess the patency of vascular anastomoses intraoperatively is to estimate refilling velocity with the naked eye. An even better way is described by Zhu et al. in the May 2, 2018 edition of The Journal of Bone & Joint Surgery.
The authors divided their study into two phases. During phase I, they found that a slower refilling velocity ratio (RVR) in 103 replanted digits, calculated with the aid of videos recorded at 1,000 frames per second, was associated with replantation failure. In phase II, the authors applied RVR goals established from phase I to another 79 replanted digits to determine whether the additional objective guidance increased the replantation survival rate compared with historical controls.
Based on phase I results, Zhu et al. set the arterial RVR goal to 0.4 and the venous RVR sum goal to 1.0. Using those goals for guidance, the authors found that the phase II success rate (96%) was significantly higher than that among historical controls (87%). In several phase I cases, intraoperative observations of specialists considered anastomoses to be acceptable, but the high-speed video data revealed that improvements were required.
One downside to obtaining this objective video data about anastomotic quality is that it adds 10 to 15 minutes to operative time. Consequently, the authors cite the need for a “well-designed, randomized, double-blinded clinical trial…to provide stronger evidence of this assessment technique.”
Pulsatile Lavage Harms Muscle in Rat Model of Blast Injury
Basic science investigations into clinically relevant orthopaedic conditions are very common—and often very fruitful. What’s not very common is seeing results from large, multicenter randomized trials published in the same time frame as high-quality in vivo basic-science research on the same clinical topic.
But the uncommon has occurred. In the November 1, 2017 issue of The Journal, Chiaramonti et al. present research on the effects of 20-psi pulsatile lavage versus 1-psi bulb-syringe irrigation on soft tissue in a rat model of blast injuries. With support from the US Department of Defense, Chiaramonti et al. developed an elegant animal study that found radiological and histological evidence that lavage under pressure—previously thought to be critical to removing contamination in high-energy open fractures—results in muscle necrosis and wound complications.
Although none of the rats developed heterotopic ossification during the 6-month study period, the authors plausibly suggest that the muscle injury and dystrophic calcification they revealed “may potentiate the formation of heterotopic ossification by creating a favorable local environment.” Heterotopic ossification is an unfortunately common sequela in patients who suffer blast-related limb amputations.
The aforementioned rare alignment between basic-research findings and clinical findings in people relates to a large multicenter randomized clinical trial recently published in The New England Journal of Medicine. That study found that one-year reoperation rates among nearly 2,500 patients treated surgically for open-fracture wounds were similar whether high, low, or very low irrigation pressures were used. This is a case where the clinical advice from basic-study authors Chiaramonti et al. to keep “delivery device irrigation pressure below the 15 to 20-psi range” when managing open fractures is based on very solid ground.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
No Surprise: Infection Biggest Culprit in Amputation for Failed TKA
Of the hundreds of thousands of total knee arthroplasties (TKAs) performed annually around the world, very few result in failure so irreparable that transfemoral amputation is the last resort. But what does “very few” really mean? In the December 7, 2016 issue of The Journal of Bone & Joint Surgery, Gottfriedsen et al. determine the cumulative incidence of amputation for failed TKAs among nearly 93,000 registered knee replacements performed in Denmark from 1997 to 2013.
The authors used a competing-risk model (which took into account the competing risk of death) to avoid overestimating incidence. From a total of 115 amputations performed for causes related to failed TKA, they calculated a cumulative 15-year incidence of amputation of 0.32%. They noted a tendency toward decreasing incidence during the 2008-2013 period, relative to the 1997-2002 period.
The three most common causes of post-TKA amputation were periprosthetic infection (83%), soft-tissue deficiency (23%), and severe bone loss (18%). The authors add, however, that the latter two causes are “most likely the result of long-term infection together with several revision procedures, in which soft tissue and bone stock are gradually damaged.”
The authors encourage orthopaedists to consider newer treatment options to avoid amputation (such as skin grafts and muscle flaps for soft-tissue loss), but they also assert that, in each individual case, those contemporary approaches should be balanced against the “psychological and physical strains related to repeated surgery performed in an attempt to salvage the knee.”
JBJS Reviews Editor’s Choice–Open Fracture Care During War
Injuries to the musculoskeletal system are among the most common wounds of war. Compared with extremity injuries in the civilian population, injuries sustained in combat tend to be due to high-energy explosions and are associated with a greater degree of contamination and a longer timeline for recovery and healing. Importantly, the sequelae of musculoskeletal injuries sustained during combat tend to lead to more long-term disability than those affecting other organ systems.
In this month’s Editor’s Choice article, Rivera et al. review the current literature on combat injuries of the lower extremity and suggest that explosions are the most common mechanism of injury encountered by deployed service members. While exposure to an explosion does not necessarily result in a specific limb injury, the explosion mechanism does contribute to more severe injuries. Moreover, among service members who sustain open fractures of the tibia, foot, and ankle, infection is a common complication and is associated with more severe soft-tissue injury. As a result, surgeons who are deployed in combat settings are now performing more fasciotomies for limbs that are at risk. However, the outcomes and complication rates associated with these procedures are not well established, and the causes of late amputations are not always clear.
As part of a comprehensive review of this topic, Rivera et al. pose 3 important clinical questions that are ideal for translational research investigation. First, they ask, “What is the best way to manage and transport patients who have severe open fractures in order to minimize infection?” Indeed, while negative-pressure wound therapy (NPWT) appears to be a promising wound-care technique, additional study is needed in order to know how to best augment the standard of care for battlefield medicine. Second, “What is the best way to treat fasciotomy wounds and the late sequelae of the compartment syndrome?” In order to answer this question, a broader understanding of compartment syndrome detection and the indications for surgical treatment are needed. Finally, “What is the best way to select limbs for salvage and to optimize the reconstruction of injured tissues?” This question must explore not only the patient’s perspective but also the multitude of causes that lead to late amputation.
Thomas A. Einhorn, MD
Editor, JBJS Reviews
JBJS Reviews Editor’s Choice–Team Approach to Diabetic Foot Ulcers
One of the newest features from JBJS Reviews is the “Team Approach” article. Team Approach articles highlight the individual and collective importance of the multiple physician and nonphysician providers who are involved in the care of a patient. Determining how the multidisciplinary interactions and contributions are key to the understanding of a medical condition and its treatment can be essential to a successful musculoskeletal health process.
In the July 2016 issue of JBJS Reviews, Pinzur et al. describe the team approach to the treatment of diabetic foot ulcers. The authors note that an estimated 29.1 million people in the U.S. have diabetes and that, at any point in time, 3% to 4% have a foot ulcer, both of which are sobering statistics. Diabetic foot ulcers and their associated infections lead to >70,000 lower-extremity amputations yearly. Between one-third and one-half of diabetic patients undergoing major lower-extremity amputation will die within 2 years after the amputation. In order to most effectively deal with this devastating outcome, a team approach with multidisciplinary involvement is needed.
It is now accepted that the best-performing health systems are those that address challenges by developing a strategy of population management in which patients with resource-consuming medical conditions receive care across multiple medical disciplines. This strategy begins with the identification of modifiable risk factors. The most efficient patient-safety methodology for avoiding complications following surgery is to operate on healthier patients. Indeed, if we look at our orthopaedic trauma colleagues as an example, we see that survival rates and patient outcomes following hip fracture have improved since the development of systems that rapidly optimize patients prior to operative repair. This experience has taught us how important it is to have a hospitalist co-managing our orthopaedic patients. Similarly, our arthroplasty colleagues have learned that outcomes are worse and complications rates are increased in patients who have multiple medical comorbidities. Prior to urgent surgery, many of these medical conditions can be stabilized. Thus, the most proactive health systems are those that use interventions to identify and minimize health risk. When modifiable risk factors are improved, patient safety is improved.
Pinzur et al. reintroduce the concept of the so-called diabetic educator. The responsibilities of the modern diabetic educator have progressed from simple patient education on diet, glycemic control, and lifestyle change to using the educator-patient relationship to empower the educator to serve as a patient navigator/case manager. The diabetic educator and the physician also work closely with a certified pedorthist. This provider’s knowledge and skill of health maintenance through the use of therapeutic footwear are important in the prevention and treatment of diabetic foot ulcers. Patients are taught to self-examine their feet, and this level of empowerment becomes important from a psychosocial perspective.
The primary surgeon is the “captain of the ship,” and it is his or her responsibility to coordinate the management and the function of the multidisciplinary team. It is important to identify the roles of the consultants such as the certified pedorthist (who will provide guidelines on therapeutic footwear and prefabricate a custom foot orthosis as needed), the vascular surgeon (who will be needed for patients with a nonhealing foot ulcer and a nonpalpable pedal pulse), the radiologist (who will be essential for suggesting imaging modalities for understanding the disease and its progression), the infectious disease specialist (who will guide duration of therapy and monitor associated antibiotic-induced organ-system morbidity), and the plastic surgeon (who may have unique requirements for wound care and developing relationships in clinical-care algorithms).
The multidisciplinary team approach involves the use of a consistent strategy throughout the hospital or health system. This is the first step in an attempt to decrease the negative impact on quality of life and resource consumption and is essential to diabetic foot care.
Thomas A. Einhorn, MD
Editor, JBJS Reviews
OTA Posts Disaster-Readiness Page for Surgeons
The Orthopaedic Trauma Association (OTA) just launched a page on its website devoted to disaster-preparedness resources for surgeons and first responders.
Titled “Get Prepared,” the page includes:
- A 93-slide PowerPoint presentation on orthopaedic blast injuries
- Courses from the National Disaster Life Support Foundation and the American College of Surgeons’ Committee on Trauma
- A bibliography with links to the JBJS Reviews article “Disaster Response Management Protocol for Departments of Orthopaedic Surgery” and the JBJS/JOSPT Special Report It Takes a Team—The 2013 Boston Marathon.
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