Significant Race Disparities Found in Amputation Rates After TKA
Carlos A. Higuera Rueda, M.D. vice chair of quality and patient safety at the Orthopaedic and Rheumatologic Institute and Cleveland Clinic told OTW about a new study he and his team conducted regarding total knee arthroplasty (TKA) and complications and said, “We found that black men had the highest rate of above knee amputations (AKA) after TKA (578 AKAs per 100,000 TKAs) after adjusting for age and comorbidities.”
“Black men also had the highest rate of AKA after septic complications of TKA. Interestingly, the rates of AKA were higher in patients younger than 50 years and older than 80 years. The annual number of AKA procedures almost doubled, from 522 procedures in 2000 to 1,083 procedures in 2011. However, we did not find an increase in the amputation rate over the years suggesting that the risk of AKA may not have increased.”
Dr. Higuera Rueda is also research director at the Center for Adult Reconstruction at Cleveland Clinic. As he described it to OTW, “While the majority of complications after total knee arthroplasty (TKA) can be successfully managed by appropriate medical and surgical treatment, some complications like prosthetic joint infection (PJI) are extremely difficult to manage.”
“Treatment options are limited after multiple failed attempts to control infection, and unfortunately, above knee amputation (AKA) needs to be considered. Although racial disparities in the utilization of TKA and in the rates and level of amputation from vascular causes have been previously reported, these have not been studied with respect to AKAs resulting from complications of TKA. Given the poor functional outcomes and broad societal implications of AKAs, it is important to understand the rates of AKA after TKA among various demographic groups in the United States.”
“National arthroplasty registries in countries like UK, Canada and Australia allow the monitoring of outcomes of various procedures at a national level. However, due to the lack of such a national joint registry, an administrative database like National Inpatient Sample (NIS) had to be used in this study for estimating the national trends. Although NIS is the largest available national database, it is not without limitations. The NIS does not enable longitudinal tracking of individual patients, and covers only short-term complications. Therefore, identifying a long term complication like amputation which develops 6 to 9 years after a TKA was not directly feasible using NIS.”
“In addition, no ICD-9 procedure/diagnosis code was available to specifically identify AKAs performed for a complication of TKA. As a result, we relied on other available codes used for prosthetic joint/orthopedic implant failure to identify the AKAs resulting from complications of TKA. Although the methodology used in this study may not have been perfect, this was the best available way to get accurate national estimates about AKA after TKA. Additionally, we validated this methodology using our own institutional database which demonstrated a high accuracy for our method.”
Asked what he thinks may be causing the differences along racial lines, Dr. Higuera Rueda told OTW, “Although previous studies have reported that blacks are less likely to undergo attempts at limb salvage than their white counterparts treated for peripheral vascular disease, the reasons for racial disparities are not fully understood. A number of factors like the differences in true risks of AKA, patient and surgeon preferences, and resource availability might have influenced the differences observed in this study. There was a bimodal distribution in the rates of AKA with respect to age. Although a higher rate is expected in older patients due to underlying comorbidities, the higher rates of AKA in the younger age group could be related to the indications for TKA in this age group.”
“Patients undergoing TKA at a younger age can be expected to have a higher prevalence of morbid obesity, rheumatoid arthritis, avascular necrosis, previous joint surgeries and other medical conditions which might have predisposed them to receive a TKA at a younger age. As these comorbidities are known risk factors for infection and other complications after TKA, it is not surprising to see a higher rate of AKA in younger patients.”
“Orthopedic surgeons should be aware that gender and racial disparities exist in the rates of AKA after TKA and that these disparities are evident in the rates of AKA after both septic and aseptic complications of TKA. As AKA is a morbid procedure which can have significant social and economic impacts; surgeons and policymakers should be aware of the disparities in the rates of AKA after TKA. Further research is required to understand the potential reasons for these disparities so that effective measures can be undertaken to address these disparities.”
Using New 3D Modeling Methodology for Anatomic Graft Placement on Femur
Louis E. DeFrate, Sc.D., is the Frank H. Bassett, III, M.D. Associate Professor at Duke University. Dr. DeFrate, who holds appointments in the departments of orthopedic surgery, mechanical engineering and material science, and biomedical engineering, has recently published award-winning work on anatomic graft placement on the femur.
The research, “Effects of ACL graft placement on in vivo knee function and cartilage thickness distributions,” was published in the June 2017 edition of the Journal of Orthopaedic Research.
Dr. DeFrate told OTW, “This work was recognized with the 2016 Kappa Delta Young Investigator Award from the American Academy of Orthopaedic Surgeons and the Orthopaedic Research Society. This paper represents a series of studies regarding anterior cruciate ligament (ACL) reconstruction performed in my laboratory since I arrived at Duke University in 2006. I first began discussing the clinical problem of anatomic graft placement with Dr. Bill Garrett, an experienced orthopaedic surgeon with a real knack for research. Dr. Chuck Spritzer, a musculoskeletal radiologist helped us to get the appropriate imaging sequences and helped us to interpret the data. Dr. Ermias Abebe was one of my very first students in the lab who performed much of the analysis.”
“We provided a new methodology to evaluate ACL graft placement relative to the native ACL by using 3D modeling techniques and MRI [magnetic resonance imaging]. We reflected the contralateral knee and overlaid the 3D models of both knees to measure where the graft was placed on a subject specific basis. We then evaluated the influence of graft placement on in vivo knee motion using biplanar radiography, and evaluated changes in cartilage thickness using MRI.”
“The studies described in this paper quantified the effects of ACL graft placement on the femur on in vivo knee function. First, femoral tunnel placement was measured using two different ACL reconstruction techniques in patients. The validated techniques described in this paper used MR imaging and 3D modeling techniques to locate the graft relative to the native ACL without the need to rely on bony or radiographic landmarks. The two reconstruction techniques considered in this first study resulted in two distinct graft placement groups: one where the graft was placed anatomically on the femur and one where the graft was placed anteroproximally on the femur, near the border of the ACL attachment site.”
“Using these two different graft placement groups, we then quantified the effects of graft placement on the ability of reconstruction to restore native ACL deformation and joint kinematics in patients under in vivo weight-bearing loading conditions. Grafts that were placed anatomically more closely restored native ACL deformation and normal knee kinematics. In contrast, grafts placed anteroproximally were more vertical than the native ACL and resulted in increased anterior translation, medial translation, and internal rotation.”
“Finally, our laboratory has developed a new methodology employing MRI techniques to quantify changes in cartilage thickness in the operative knee relative to the contralateral side. We found that grafts placed anteroproximally had decreased cartilage thickness, while anatomic graft placement slowed the progression of cartilage thinning. All of these studies quantified the effects of placement on graft function, knee kinematics, and cartilage thickness in the same group of patients. Our results demonstrate that achieving anatomic graft placement on the femur is critical to restoring native ACL function and normal knee kinematics, which may slow the progression of cartilage degeneration. Thus, this work has direct clinical relevance to the long-term management of ACL injuries. Importantly, this work has changed clinical practice at Duke University Medical Center and other institutions nationally.”
“Achieving anatomic graft placement can help to restore normal knee motion under physiological conditions, and help to maintain cartilage thickness. Patients with non-anatomic grafts had abnormal knee motion, and focal cartilage thinning just 18 months after surgery.”
Steadman Research: Excellent 10-Year Results After Hip Arthroscopy for FAI
New work from the Steadman Philippon Research Institute in Vail, Colorado, has found that minimum joint space in hip arthroscopy for femoralacetabular impingement (FAI) is a key factor for 10-year survival.
The study, “Survivorship and Outcomes 10 Years Following Hip Arthroscopy for Femoroacetabular Impingement: Labral Debridement Compared with Labral Repair,” was published in the June 21, 2017 edition of The Journal of Bone and Joint Surgery.
Marc J. Philippon, M.D. is a partner at The Steadman Clinic, as well as the co-chief science officer, co-chairman of Scientific Advisory Committee, co-director of the Sports Medicine Fellowship and director of Hip Research at The Steadman Philippon Research Institute.
Dr. Philippon commented to OTW, “One of my goals when I came to Vail in 2005 was to validate, with evidence based medicine, the role of hip arthroscopy for FAI surgery. In this 10-year outcome research study, we demonstrate with this large series what physician and patients should expect in the long term following the outcome of hip arthroscopy. In addition, the survivorship analysis help educate patients on how long they can expect to continue to see the benefit of hip arthroscopy. All of this information leads to improving patient care and outcomes.”
Dr. Philippon and his colleagues wrote, “Seventy-nine patients who underwent labral repair and 75 who underwent debridement were included in the study, and 94% (145) were followed for ≥10 years. Fifty patients (34%) underwent total hip arthroplasty (THA) within 10 years following the arthroscopy. Older patients, hips with >2mm of joint space preoperatively, and patients requiring acetabular microfracture had significantly higher prevalences of THA.”
Dr. Philippon told OTW, “There are several key points. The first one is that our rule for minimum joint space (must have greater than 2mm) is a key factor for 10-year survival. If patients had 2mm or greater of joint space, only 15% converted to THA while in those with 2mm or less, 89% converted to THA. We reported on this five years ago so our indications changed then so we are excited about the improvement we are going to see in this new group. Another key result is that patients showed significant improvement at 10 years following hip arthroscopy. We did not see a decline in scores, but scores that continued near highest possible.”
“We found that the debridement group had the same outcome s as the repair group. However on closer look, we found that the debridement were a select group of patients that had less severe injuries and they did very well following hip arthroscopy.”
“The key to finding patients 10 years after surgery is to keep in touch with them over the years. For this study design, we used survival analysis to determine how different factors effected when a patient converted to THA. The graph that is in the appendix shows how survivorship varies by age. These can be good educational tools for patients who are deciding if they want to have hip arthroscopy and also have a better understanding of the procedure to have realistic expectations.”
“Hip arthroscopy can improve patient outcomes. With good patient selection, patients will survive 10 years and have excellent outcomes. It is critical to education your patients on their risk of conversion to THA and match this with their expectations.”
