The Current Epidemiology of Revision Total Knee Arthroplasty in the United States From 2016 to 2022

Comparing Survivorship of Symmetric Versus Asymmetric Tibial Augments in Aseptic Revision Total Knee Arthroplasty

BACKGROUND

This study evaluated the presence of radiolucency in patients who underwent aseptic revision total knee arthroplasty (arTKA) using either symmetric or asymmetric modular tibial augments and compared 5-year all-cause and non-septic revision-free survivorship between groups. The authors hypothesized that tibial constructs with asymmetric augments would be more prone to radiolucency, but that there would be no difference between groups regarding implant survivorship at five years.

METHODS

An institutional database was queried from January 2013 to September 2023 to identify patients who underwent arTKA where tibial augments were utilized. Patients who had proximal tibial reconstructions (PTRs), distal femoral reconstructions (DFRs), or hinge constructs, as well as patients who did not have a minimum of one year of follow-up, were excluded. Included patients were then stratified into symmetric and asymmetric tibial augment groups. Postoperative radiographs were reviewed for radiolucent lines through available follow-up. Kaplan-Meyer survivorship curves were then created to compare rates of revision between both groups over five years. A total of 76 patients who had symmetrical augments and 27 patients who had asymmetrical augments were analyzed at a mean follow-up time of 3.5 years (range, 1.0 to 10.1) and 4.4 years (range, 1.0 to 8.8), respectively.

RESULTS

Radiolucency was noted in 44.4% (12 of 27) of patients who had asymmetric augments and 44.7% (34 of 76) of those who had symmetric augments (P = 1.0). Overall, the 5-year all-cause revision-free survivorship for the entire cohort was 76.6%. The 5-year all-cause and non-septic revision-free survival were lower in patients who had asymmetric tibial augments compared to symmetric (56.1 versus 85.5%; P = 0.021 and 64.8 versus 89%; P = 0.019, respectively). Patients who had symmetric tibial augments had 84% less risk of non-septic revision when compared to patients who had asymmetric tibial augments (P = 0.035). Sub-analysis demonstrated that asymmetric tibial augment constructs with metaphyseal cones had similar 5-year non-septic revision-free survivorship to symmetric tibial augment constructs with (75.0 versus 97.0%; P = 0.13) or without metaphyseal cones (75.0 versus 82.5%; P = 0.54).

CONCLUSION

Patients who had symmetric tibial augment constructs exhibited similar rates of radiolucency, but higher survivorship compared to those who had asymmetric constructs overall. However, when metaphyseal cones were utilized, survivorship was equivalent. Therefore, their use in asymmetric tibial augment constructs is likely beneficial.

Why are Primary Total Knee Arthroplasties Failing? A Systematic Review and Meta-Analysis

INTRODUCTION

Revision total knee arthroplasty (TKA) is a burden to patients and the healthcare system. The purpose of this systematic review is to identify the most likely causes for requiring a revision of TKA over the last 14 years.

METHODS

A comprehensive search of multiple electronic databases was performed for all articles pertaining to this topic from 2010 to 2024. A total of 16 studies were included in this review.

RESULTS

Our final cohort consisted of 1,383,181 revision arthroplasties. Approximately 31% of revisions had unspecified etiology. The most common documented etiologies for revision were periprosthetic joint infection (22.3%) and aseptic loosening (20.5%). Other common etiologies were instability (7%), implant breakage (3.6%), dislocation (3%), osteolysis (2.4%), and polyethylene wear (2%). The most common causes for early (< two years) and late (> two years) revision were infection and aseptic loosening, respectively.

DISCUSSION

Infection and aseptic loosening were the most common causes for early and late revision TKA, respectively. Future studies should assess the role of advancements in surgical techniques and component design to alter these revision risks.

Superior Clinical Results with Intraosseous Vancomycin in Primary Total Knee Arthroplasty

INTRODUCTION

Periprosthetic joint infection (PJI) remains a feared complication after total knee arthroplasty (TKA). This study reports updated outcomes of the incidence of PJI, adverse reactions, and complications of our cohort with increased clinical follow-up of our previous study reported in 2021.

METHODS

A retrospective review of 1,923 knees that received either IV or IO vancomycin during primary TKA between May 2016 and May 2023 with a minimum 90-day follow-up (mean 913 ± 611 days). There were 564 cases in the IV group and 1,359 in the IO group. The IV group received a weight-based dose of vancomycin before incision, and the IO group received 500 mg of vancomycin in the proximal tibia after tourniquet inflation. All patients received a weight-based dose of IV cefazolin perioperatively. The 2018 International Consensus Meeting criteria were used to diagnose PJI. Acute kidney injury (AKI) was defined as a creatinine increase of 0.3 mg/dL.

RESULTS

The IO group demonstrated a significantly lower incidence of PJI compared to the IV group at 90-day (0.5 versus 1.6%, P = 0.018), 1-year (0.7 versus 1.8%, P = 0.048), and 2-year (0.9 versus 2.4%, P = 0.032) follow-up. Additionally, there was a lower incidence of non-operative wound complications requiring oral antibiotics in the IO group at 30-day (2.3 versus 4.3%, P = 0.023) and at 90-day (2.5 versus 5.4%, P = 0.003) follow-up. There was a lower incidence of AKI in the IO group (1.6 versus 3.2%, P = 0.078), but this did not reach statistical significance. There was no difference in the incidence of deep vein thrombosis, pulmonary embolism, or operative wound complications.

CONCLUSIONS

Intraosseous vancomycin demonstrated superior clinical outcomes over IV vancomycin with a reduced incidence of PJI at 90-day, 1- and 2-year follow-up after primary TKA. Additional benefits of IO vancomycin were a reduction in non-operative wound complications through 90-day follow-up and a non-statistically significant reduction in the incidence of AKI.

Exosomes Derived from Bone Marrow Mesenchymal Stem Cells Encapsulated in M2 Macrophage Cell Membrane Targeted to Inhibit Joint Periprosthetic Inflammation

Periprosthetic osteolysis (PPOL) is a serious complication following total joint replacement surgery, and exploring treatments for this complication is of significant societal importance. Exosomes derived from bone marrow mesenchymal stem cells (BMSC-Exos, Exos) have diverse cellular functions, such as inhibiting osteoclast formation, suppressing inflammation progression, and promoting M2 macrophage polarization. However, standalone Exosomes are easily recognized and phagocytosed by the immune system, have a short half-life, and lack specificity. This study is based on the homing effect possessed by M2 macrophages under the regulation of various factors. By combining this with cell membrane encapsulation technology and embedding BMSC-Exos within the membrane of M2 macrophages (M2M-Exos), the aim is to inhibit inflammation and treat PPOL. It was found that M2M-Exos can target the PPOL area, enhancing the therapeutic effects of the BMSC-Exos and reducing wear particle-induced cranial osteolysis. Additionally, M2M-Exos provide immune camouflage through the cell membrane, allowing the BMSC-Exos to evade clearance by the mononuclear macrophage system in the body. Therefore, the study demonstrates the targeting ability of M2M-Exos and their unique role in preventing PPOL. These biomimetic nanoparticles establish a targeted nanodrug delivery system for PPOL treatment.

Effect of Converting Kinematic Aligned Total Knee Arthroplasty to Mechanical Axis Revision Total Knee Arthroplasty on Gap Measurements

BACKGROUND

Implants and fixation in revision total knee arthroplasty (rTKA) are based on intramedullary referencing and mechanical axis (MA) restoration. Alternative alignment strategies to primary MA total knee arthroplasty (TKA) are increasing in popularity and often place implants in positions of joint line obliquity. The deviation in implant position could result in significant bony defects when being revised to MA-based revision reconstructions. The purpose of this study was to analyze the medial and lateral, as well as flexion and extension gaps, following a standardized workflow to revise a kinematically aligned total knee arthroplasty (KA TKA) to an MA rTKA.

METHODS

Seven cadaveric lower extremities that previously underwent caliper-verified KA TKA were converted to MA rTKA utilizing a series of sequential soft tissue releases followed by a tibial osteotomy set perpendicular to the tibial mechanical axis. Gap measurements following each step were recorded using a digital gap-balancing device.

RESULTS

After conversion from KA TKA to MA rTKA, statistically significant increases were observed in the medial extension, medial flexion, lateral extension, and lateral flexion spaces of 1.6 mm (p=0.033), 3. 6mm (p<0.001), 5.6 mm (p<0.001) and 6.9 mm (p<0.001), respectively. Release of the posterior cruciate ligament (PCL) resulted in isolated flexion space opening by 2.4 mm (p=0.002) and 2.3 mm (p=0.022), respectively, for the medial and lateral flexion gaps.

CONCLUSION

Soft tissue releases seen in rTKA have minimal effect on the medial laxity in extension. In specimens with only mild deviation from neutral alignment and joint line obliquity, the conversion from caliper-verified KA TKA to MA rTKA still resulted in large increases in the lateral-sided gaps, especially in the flexion space. This may create issues with current implant offerings, and surgeons should anticipate substantial augmentation or joint line adjustments when revising implants that were placed with intentional joint line obliquity.

Characterizing the Cost Trends of Readmissions After Aseptic Revision Total Knee Arthroplasty

BACKGROUND

A rise in total knee arthroplasty (TKA) volume has led to an increased incidence of aseptic revision TKA (rTKA), resulting in major associated health care costs. This study evaluated the economic impact and clinical factors associated with readmission following aseptic rTKA, aiming to identify key drivers of cost and risk factors for readmission.

METHODS

This retrospective analysis used data from a large national database from January 1, 2009, to June 30, 2022. Patients undergoing aseptic rTKA were identified via Current Procedural Terminology codes. Readmissions within 90 days postoperatively were analyzed. Baseline characteristics, comorbidities, and readmission costs were compared, and significant risk factors for readmission were identified. Of 34,144 aseptic rTKA patients, 1,953 (5.7%) were readmitted within 90 days (56.1% medical, 29.2% surgical, and 14.8% unknown).

RESULTS

The median cost of all readmissions was $25,181. Readmissions requiring reoperation had a higher cost (median $40,524 versus $20,907, P < 0.001). Among readmissions for surgical complications, periprosthetic joint infection was the most common cause (36.3%) and was associated with the greatest cost (median $38,104). The most common medical causes of readmission were rehabilitative care, ischemic cardiac events, and acute kidney injury. Significant risk factors for all-cause readmission included men, index revision for periprosthetic fracture, and comorbidities, including diabetes, coronary artery disease, renal disease, and congestive heart failure.

CONCLUSIONS

Readmission after aseptic rTKA results in a major economic burden to the health care system, particularly in readmission pertaining to surgical complications and requiring reoperation. This study highlights the need for targeted strategies aimed at effectively reducing the rate and costs associated with readmission post-rTKA with a goal of cost containment and improved patient outcomes.

AI classification of knee prostheses from plain radiographs and real-world applications

PURPOSE

Total knee arthroplasty (TKA) is considered the gold standard treatment for end-stage knee osteoarthritis. Common complications associated with TKA include implant loosening and periprosthetic fractures, which often require revision surgery or fixation. Challenges arise when medical records related to the knee prosthesis are lost, making it difficult to plan for revision surgery effectively. This study aims to develop an artificial intelligence (AI) system to classify the types of knee prosthetic implants using plain radiographs.

METHODS

This retrospective experimental study includes seven types of knee prostheses commonly used in our hospital. The artificial intelligence (AI) system was trained using YOLO (You Only Look Once) version 9, utilizing a dataset of 3228 post-operative and follow-up knee arthroplasty X-ray images. The plain radiographic images were augmented, resulting in a dataset of 25,800 images. Model parameters were fine-tuned to optimize performance for implant classification.

RESULTS

The mean age of the patients was 62.8 years. Right knee arthroplasty was performed in 48.3% of cases, while left knee arthroplasty was performed in 51.7%. The images of knee prostheses comprised 50.9% of the dataset from the anteroposterior (AP) view and 49.1% from the lateral view. The AI model demonstrated exceptional performance metrics, achieving precision, recall, and accuracy rates of 100%, with an F1 score of 1. Additionally, the area under the curve (AUC) of the receiver operating characteristic (ROC) curve was calculated to be 100%.

CONCLUSION

This AI model successfully classifies knee prosthetic implants from plain radiographs. This capability serves as a valuable tool for surgeons, enabling precise planning for revision surgeries and periprosthetic fracture fixation surgery, ultimately contributing to improved patient outcomes. The high accuracy achieved by the AI underscores its potential to enhance surgical efficiency and effectiveness in managing knee arthroplasty complications.

A cross-linked coating loaded with antimicrobial peptides for corrosion control, early antibacterial, and sequential osteogenic promotion on a magnesium alloy as orthopedic implants

Magnesium (Mg)-based alloys have been recognized as desirable biodegradable materials for orthopedic implants. However, their clinical application has been limited by rapid degradation rates, insufficient antibacterial and osteogenic-promotion properties. Herein, a MgF2 priming layer was first constructed on AZ31 surface. Then, dopamine and polyphenols (EGCG) were cross-linked onto this AZ31-F surface to promote osteogenesis and further enhance corrosion protection, followed by chemical grafting of antimicrobial peptides (AMPs) via Michael-addition and Schiff-base reaction to confer antibacterial properties. In vitro electrochemical corrosion tests showed that icorr of AZ31-FE/AMPs (4.36×10-7 A/cm2) is two orders of magnitude lower than that of AZ31 (4.17×10-5 A/cm2). In vitro immersion degradation showed that AZ31-FE/AMPs exhibited the lowest hydrogen release (2.38 mL) after 400 h immersion with the lowest hydrogen evolution rate among them. Further, AZ31-FE/AMPs displayed inhibitory effects against S. aureus and E. coil in the initial stage and even after 7 days immersion in PBS (antibacterial rate > 85 %). AZ31-FE/AMPs promoted ALP secretion and calcium nodule formation in MC3T3-E1 cells. Transcriptome sequencing results indicated that osteogenic promotion mechanism of AZ31-FE/AMPs in MC3T3-E1 may involve the PI3K-Akt signalling pathway. Further, AZ31-FE/AMPs enhanced new bone formation when implanted in a rat femoral bone defect model. This coating strategy addresses initial antibacterial and later osteogenesis needs based on the corrosion control, which is crucial for the surface design of Mg-based implants. STATEMENT OF SIGNIFICANCE: It is critical for magnesium-based orthopedic implants to achieve sequential functions in the bone repair process while controlling an appropriate degradation rate. A MgF2 priming layer/phenolic-amine grafted AMPs (antimicrobial peptides) duplex coating was constructed on AZ31 surface in this study. The MgF2 layer provided a basic corrosion protection to magnesium substrate, and dopamine and polyphenols (EGCG) were then cross-linked to the MgF2 pretreated AZ31 to promote osteogenesis and enhance corrosion resistance, followed by chemical grafting of AMPs to confer antibacterial property. This strategy effectively meets the initial need for infection resistance and later osteogenic promotion on the basis of controlling the substrate corrosion rate, thus holding significant implications for the surface design of magnesium-based implants.

Does Timing of Hindfoot Reconstruction Before or After Primary Total Knee Arthroplasty Impact Reoperation Rates?

Background

Total knee arthroplasty (TKA) and hindfoot reconstruction (HFR) are often used to treat osteoarthritis and deformities of the knee and hindfoot. Despite the proven clinical effectiveness of these treatments, postoperative patient dissatisfaction is high. The knee and ankle are adjacent joints in the lower extremity, and angular deformity of either joint is known to affect positioning of the anatomical and mechanical axes of the entire limb. Although it is understood this relationship exists, there are limited studies evaluating outcomes of ipsilateral procedures on patients with pathologies of both knee and hindfoot. This article aims to evaluate whether TKA or TAA/HFR sequencing influences postoperative outcome. The study hypothesis is that TKA prior to TAA/HFR results in lower reoperation.

Methods

A retrospective chart review using Current Procedural Terminology (CPT) codes was performed encompassing all patients who underwent TKA in conjunction with a variety of hindfoot procedures. All procedures were performed at a single academic medical site between 2000 and 2022. Exclusion criteria included those patients not having both ipsilateral TKA and hindfoot procedures or those lacking conclusive postoperative data. The primary outcome of this study was to identify significant reoperations such as adjacent joint arthrodeses, hardware removal, or unrelated ipsilateral limb surgery. Secondary outcomes included identification of revision procedures including revision TKA or revision HFR and other postoperative complication data.

Results

This study included 158 patients, with 79 patients in each group. In the TKA-first group, the mean follow-up time was 10.24 years (range, 1.10-22.42 years) and the mean time to HFR was 5.94 years. In the HFR-first group, the mean follow-up time was 9.01 years (range, 1.01-23.55 years) and the mean time to TKA was 5.51 years.In patients who underwent TKA first, the mean reoperation rate was not significantly different from those who underwent HFR/TAA first, 30.4% vs 19.0% (P = .12). In patients who underwent TKA first, the rate of HFR reoperations (22.78%) was greater than TKA reoperations (7.59%) (P < .01). The revision rate was higher in the TKA-first group (17.7%) when compared to the HFR-first group (6.3%) (P = .03). Additionally, there were more revision HFR procedures in the TKA-first group (9/79) compared with the HFR-first group (1/79) (P = .009).

Conclusion

In contrast to the study hypothesis that TKA first would result in less reoperation, our study found that TAA or HFR performed before TKA had an overall lower complication rate. However, these findings should be interpreted cautiously as the sample size was limited.

Level of Evidence

Level III, retrospective cohort study.

Analysis of Synovial Fluid Aspirations in Aseptic Loosening and Instability After Total Knee Arthroplasty

BACKGROUND

Aseptic total knee arthroplasty (TKA) complications can be challenging to diagnose. Many studies have defined periprosthetic joint infection (PJI) using synovial aspirations, but few studies have described aspiration characteristics in aseptic TKA problems. The aim of this study was to determine the synovial fluid characteristics of patients who had TKA failure caused by two common aseptic diagnoses: aseptic loosening and instability. We sought to compare the characteristics between these groups in addition to the failure caused by PJI.

METHODS

A retrospective study was performed in which consecutive patients who had a preoperative knee aspiration and underwent TKA revision for one of three diagnoses (PJI, aseptic loosening, or instability) were evaluated. Clinical notes were used to obtain demographics, comorbidity data, aspiration cell count, and differential to compare among the groups. There were 399 patients included: 240 PJI, 103 aseptic loosening, and 56 instability.

RESULTS

There were significant differences between mean white blood cell (WBC) count and polymorphonuclear, lymphocyte, and monocyte percentages between all groups. Findings consistent with a diagnosis of aseptic loosening included a mean WBC count of 1,021.9 cells/μL with 29.7% polymorphonuclear (PMNs), 32.7% lymphocytes, and 44.6% monocytes, and relatively elevated PMN/lymphocyte (2.1) and PMN/monocyte (3.5) ratios. Findings consistent with a diagnosis of instability included a mean WBC count of 1,261.2 cells/μL with 23.5% PMNs, 35.6% lymphocytes, and 50.0% monocytes, and a relatively lower PMN/lymphocyte (1.1) and PMN/monocyte (1.5) ratios compared to aseptic loosening. In both aseptic loosening and instability, there were significantly more lymphocytes and monocytes than in PJI. In addition, instability cases had a higher mean red blood cell count of 405,996.9 cells/μL (P = 0.012).

CONCLUSIONS

Differentiating between instability and aseptic loosening in TKA remains a diagnostic challenge. This study provides insight into the cellular pathophysiology of aseptic TKA complications and can be used to aid in clarifying the diagnosis of aseptic loosening versus instability.

Assessing osteoporosis screening compliance in total joint surgery: a retrospective chart review

CONTEXT

Osteoporosis is a prevalent concern, particularly among aging populations, leading to increased risk of fractures, including those related to hip and knee arthroplasty procedures. Screening for osteoporosis, especially with dual X-ray absorptiometry (DXA) scans, is crucial for early detection and management.

OBJECTIVES

This study aimed to assess adherence to osteoporosis screening guidelines among patients aged 65 and older undergoing elective total hip arthroplasty (THA) or total knee arthroplasty (TKA) within a single health network. Factors influencing screening adherence were also explored.

METHODS

A retrospective chart review of 2,160 patients undergoing elective THA or TKA between January 2019 and January 2023 was conducted. Demographic data, osteoporosis screening status, and occurrence of periprosthetic fractures were analyzed. Statistical analysis included descriptive statistics and chi-square tests.

RESULTS

Only 24.1 % of eligible patients underwent a DXA scan prior to surgery. Females were more likely to undergo screening than males, and race was also associated with screening status. A total of 45 periprosthetic fractures were identified, with no significant correlation between osteoporosis status, DXA screening, and fracture occurrence.

CONCLUSIONS

Adherence to osteoporosis screening guidelines among geriatric patients undergoing elective total joint arthroplasty remains low within the studied health network. Despite the lack of correlation between screening and fracture occurrence in this study, the importance of screening and potential optimization in high-risk patients is emphasized. Further research is needed to assess outcomes associated with different care pathways in bone health screening and management for elective geriatric total joint patients.

Trends and Epidemiology in Revision Total Knee Arthroplasty: A Large Database Study

BACKGROUND

As the volume of primary total knee arthroplasty (TKA) continues to grow, the clinical and financial burden of revision total knee arthroplasty (rTKA) is expected to increase. The purpose of this investigation was to characterize contemporary indications and complications for rTKA.

METHODS

Patients undergoing rTKA between 2010 and 2021 were identified within an administrative claims database. Adjusted rTKA incidence was calculated by dividing the annual rTKA volume by the annual primary TKA and multiplying by 100,000. Mann-Kendall trend tests were utilized to trend revision volume, etiology, 90-day postoperative complications, and patient demographics.

RESULTS

A total of 397,367 rTKA were identified over our study period, of which 287,492 (72.4%) had coding regarding revision etiology. The volume of annual rTKA (31,091 to 33,850; P = 0.451) did not change over the study period. The adjusted incidence of rTKA decreased (25,568.3 to 19,272.2 per 100,000 annual TKA; P = 0.011). The leading causes of revision TKA were infection (21.2%), aseptic implant loosening (19.3%), and instability (9.8%). The rate of septic revision (4,710.5 to 4,426.1 per 100,000 annual TKAs) and aseptic implant loosening (4,502.5 to 3,636.4 per 100,000 annual TKAs) did not change (both P values > 0.05). The rates of instability increased (1,369.2 to 2,609.85 per 100,000 annual TKAs; P = 0.007). The rates of postrevision surgical site infection, periprosthetic joint infection, deep vein thrombosis, and transfusion decreased over the study period, while rates of emergency department visits and readmission increased (all P values <0.05).

CONCLUSIONS

The incidence of revision TKA may be slowing. While the risk of revision for infection and aseptic loosening remains unchanged, revision for instability has increased. The rates of postoperative complications appear to have decreased. Improved surgical technique, implant design, and perioperative protocols may have contributed to these findings. Continued work is necessary to reduce the risk of failure and postoperative complications.

A Murine Model of Non-Wear-Particle-Induced Aseptic Loosening

BACKGROUND

The current murine models of peri-implant osseointegration failure are associated with wear particles. However, the current clinical osseointegration failure is not associated with wear particles. Here, we develop a murine model of osseointegration failure not associated with wear particles and validate it by comparing the cellular composition of interfacial tissues with human samples collected during total joint arthroplasty revision for aseptic loosening.

MATERIALS AND METHODS

Thirty-two 16-week-old female C57BL/6 mice underwent implantation with a press-fitted roughened titanium implant (Control, n = 11) to induce normal osseointegration and a press-fitted smooth polymethylmethacrylate implant (PMMA, n = 11), a loosely fitted smooth titanium implant (Smooth-Ti, n = 5) or a loosely fitted roughened titanium implant (Overdrill, n = 5) to induce osseointegration failure. Pullout testing was used to determine the strength of the bone-implant interface (n = 6 of each for Control and PMMA groups) at 2 weeks after implantation. Histology (n = 2/group) and immunofluorescence (n = 3/group) were used to determine the cellular composition of bone-implant interfacial tissue, and this was compared with two human samples.

RESULTS

Osseointegration failure was confirmed with grossly loosening implants and the presence of fibrous tissue identified via histology. The maximum pullout load in the PMMA group was 87% lower than in the Control group (2.8 ± 0.6 N vs. 21 ± 1.5 N, p < 0.001). With immunofluorescence, abundant fibroblasts (PDGFRα+ TCF4+ and PDGFRα+ Pu1+) were observed in osseointegration failure groups and the human samples, but not in controls. Interestingly, CD146+PDGFRα+ and LepR+PDGFRα+ mesenchymal progenitors, osteoblasts (OPN+), vascular endothelium (EMCN+) cells were observed in all groups, indicating dynamic osteogenic activity. Macrophages, only M2, were observed in conditions producing fibrous tissue.

CONCLUSIONS

In this newly developed non-wear-particle-related murine osseointegration failure model, the cellular composition of human and murine interfacial tissue implicates specific populations of fibroblasts in fibrous tissue formation and implies that these cells may derive from mesenchymal stem cells.

Multimodal positron emission tomography (PET) imaging in non-oncologic musculoskeletal radiology

Musculoskeletal (MSK) disorders are associated with large impacts on patient's pain and quality of life. Conventional morphological imaging of tissue structure is limited in its ability to detect pain generators, early MSK disease, and rapidly assess treatment efficacy. Positron emission tomography (PET), which offers unique capabilities to evaluate molecular and metabolic processes, can provide novel information about early pathophysiologic changes that occur before structural or even microstructural changes can be detected. This sensitivity not only makes it a powerful tool for detection and characterization of disease, but also a tool able to rapidly assess the efficacy of therapies. These benefits have garnered more attention to PET imaging of MSK disorders in recent years. In this narrative review, we discuss several applications of multimodal PET imaging in non-oncologic MSK diseases including arthritis, osteoporosis, and sources of pain and inflammation. We also describe technical considerations and recent advancements in technology and radiotracers as well as areas of emerging interest for future applications of multimodal PET imaging of MSK conditions. Overall, we present evidence that the incorporation of PET through multimodal imaging offers an exciting addition to the field of MSK radiology and will likely prove valuable in the transition to an era of precision medicine.