Hollis G Potter

Hospital for Special Surgery, New York, New York, United States

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Publications (249)616.53 Total impact

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    ABSTRACT: The purpose of this study was to evaluate whether patients with bilateral metal-on-metal (MoM) hip replacements have symmetric adverse local tissue reactions (ALTRs) at follow-up. An MRI of both hips was performed at a mean time of six years after surgery in 43 patients. The prevalence and severity of ALTRs were found to be similar in simultaneous hips but differences were observed in sequential hips. The order and timing of sequential hip arthroplasties did not affect the severity of ALTRs. Thus, in addition to metal ion exposure from an earlier MoM implant other factors may also play a role in the progression of ALTRs. Bilateral implants should be given special consideration in risk stratification algorithms for management of patients with MoM hip arthroplasty.
    The Journal of Arthroplasty 10/2015; 30(10):1794-1798. · 2.67 Impact Factor
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    ABSTRACT: Adverse local tissue reactions (ALTRs) around hip arthroplasties are an important reason for failure of metal-on-metal (MoM) hip implants. Little is known about capsular dehiscence patterns as ALTRs decompress from the hip into the surrounding tissue planes; these patterns may also influence the onset and severity of patient symptoms. Through a multicenter study approach, we asked: (1) Is ALTR location related to the surgical approach used for arthroplasty in patients who underwent hip arthroplasty (resurfacing or THA) with a single, recalled hip arthroplasty system? (2) Do ALTR severity and location affect patient-reported outcomes in these patients? (3) Is ALTR severity different between patients who received the resurfacing version of this component (Articular Surface Replacement [ASR]) and those who received the THA implant in this system (ASR XL)? In a multicenter prospective study of patients who had undergone surgery with use of the ASR and ASR XL hip system (DePuy Orthopaedics, Warsaw, IN, USA), 288 patients (333 hips) from two centers had a metal artifact reduction sequence MRI of the hip performed at a mean time of 6 years postsurgery. Procedures included 166 hips (50%) with ASR resurfacing and 167 hips (50%) with ASR XL THA performed between 2004 and 2010. One hundred twenty-nine hips (39%) had been operated on using a direct lateral approach and 204 using a posterior approach (61%). The EQ-5D, Harris hip score, UCLA activity score, and visual analog scale pain score were obtained for each patient. ALTRs were classified using the Anderson ALTR grading system, and the location, synovial thickness, and diameter of the ATLRs were assessed. The relationship between ALTR location and surgical approach as well as for ALTR severity and patient-reported outcomes were evaluated, and logistic regression was used to identify predictors for moderate-to-severe ALTRs. Moderate or severe ALTRs were identified in 79 hips (24%); 41 of these hips had been operated on using the direct lateral approach and 38 using the posterior approach. In patients in whom the lateral approach was used, 83% had an anterior ALTR. Similarly, 71% of patients in the posterior approach group had posterior ALTRs. There were no differences in patient-reported outcome measures between patients with moderate-to-severe ALTRs and those with no ALTR findings on MRI (p > 0.09). Use of ASR XL was an independent risk factor for moderate-to-severe ALTRs (odds ratio, 2.8; 95% confidence interval, 1.4-5.5 p = 0.004) and patients with ASR XL also had a thicker synovium (median ASR XL = 3.6 mm [1.2-10.6 mm], median ASR = 2.6 mm [1.2-10.7 mm], p < 0.001) and larger maximal ALTR diameter (median ASR XL = 47.6 mm [14-109.70 mm], median ASR = 38.4 [17.2-118.0 mm], p = 0.02) than patients treated with ASR. The location of ALTRs can be predicted based on the previous surgical approach to the hip. Patients with ASR XL are more likely to develop moderate-to-severe ALTRs compared with ASR patients. An extensive range of patient-reported outcome measures may not identify all patients with ALTRs further supporting the use of MRI as a screening measure for ALTRs. Level II, therapeutic study.
    Clinical Orthopaedics and Related Research 08/2015; DOI:10.1007/s11999-015-4456-x · 2.77 Impact Factor
  • Jan Fritz · Brett Lurie · Hollis G. Potter
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    ABSTRACT: PURPOSE/AIM Discuss optimization strategies for MRI of knee arthroplasty and the utility of dedicated metal artifact reduction pulse sequences Review the normal MRI appearances of knee arthroplasty Systematically illustrate the MRI diagnoses of arthroplasty-associated complications CONTENT ORGANIZATION The role of MRI following knee arthroplasty Optimized MR imaging protocol, MR angiography and dedicated metal artifact reduction pulse sequences Normal MRI appearances and MRI diagnosis of complications: Fibrous membrane formation, bone resorption and aseptic loosening Polyethylene wear-induced synovitis and osteolysis Infection, non-specific synovitis and arthrofibrosis Impingement syndromes and patellar clunk Recurrent hemarthrosis – MR angiography assessment Stress reactions and fractures Component rotational alignment Polyethylene displacement Instability and excessive soft tissue balancing Musculotendinous abnormalities Neurovascular compromise SUMMARY Optimized and dedicated MRI techniques reduce metal artifacts and improve our ability to assess and differentiated knee arthroplasty-associated complications. MRI is accurate for the diagnosis of bone resorption, synovitis, malalignment and hemarthrosis and can detect infection, muscle, tendon and nerve abnormalities.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 08/2015
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    ABSTRACT: It has been suggested that the extent and location of cartilage deformation within a joint under compressive loading may be predictive of predisposition to further degeneration. To explore this relationship in detail requires the quantification of cartilage deformation under controlled loads on a per-patient basis in a longitudinal manner. Our objectives were (1) to design a device capable of applying controllable axial loads while ensuring repeatable within-patient tibiofemoral positioning during magnetic resonance imaging (MRI) scans and (2) to determine the duration for which load should be maintained prior to the image acquisition, for a reproducible measurement of cartilage deformation, within the restraints of a clinical setting. A displacement control loading device was manufactured from MRI-compatible materials and tested on four volunteers for the following five scans: an unloaded scan, two repeat immediate scans which were started immediately after the application of 50% body weight, and two repeat delayed scans started 12min after load application. Outcome measures included within-patient changes in tibiofemoral position and cartilage deformation between repeat loaded scans. The differences in tibiofemoral position between repeat loaded scans were <1mm in translation and <2° in rotation. Cartilage deformations were more consistent in the delayed scans compared to the immediate scans. We conclude that our loading device can ensure repeatable tibiofemoral positioning to allow for longitudinal studies, and the delayed scan may enable us to obtain more reproducible measurements of cartilage deformation in a clinical setting. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Journal of Biomechanics 08/2015; DOI:10.1016/j.jbiomech.2015.08.006 · 2.75 Impact Factor
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    ABSTRACT: Background: Osteochondral autografts and allografts have been widely used in the treatment of isolated Grade IV articular cartilage lesions of the knee. However, there is paucity in the literature with regards to the basic science investigating the direct comparison between fresh osteochondral allografts to autografts. Hypothesis: At twelve months, fresh osteochondral allografts are equal to autografts with respect to function, bony incorporation into host bone and chondrocyte viability. Study Design: Prospective comparative in-vivo animal model study Methods: Eight adult mongrel dogs underwent bilateral hind limb osteochondral graft implantation in the knee after creation of an Outerbridge Grade IV cartilage defect. One hind limb knee received an autograft, and the contralateral knee received an allograft. All dogs were sacrificed at twelve months. Graft analysis included gross examination, radiographs, magnetic resonance imaging, biomechanical testing and histology. Results: Magnetic resonance imaging demonstrated excellent bony incorporation of both autografts and allografts, except one allograft, which revealed partial incorporation. Histologic examination of cartilage showed intact hyaline appearance for both autografts and allografts, with fibrocartilage at the interface of both. Biomechanical testing demonstrated no significant difference between allografts and autografts (p=0.76). Furthermore, no significant difference was observed between allografts and the native cartilage with biomechanical testing (p=0.84). Conclusions: After 12 months from time of implantation, fresh osteochondral allograft and autograft tissue are not statistically different with respect to biomechanical properties, bony incorporation and chondrocyte viability.
    Western Orthopedic Association Annual Meeting, Couer d'Alene, Idaho; 08/2015
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    ABSTRACT: Magnetic resonance imaging (MRI) visualization of meniscal signal is particularly challenging as the highly organized ultrastructure of meniscal fibrocartilage yields very short T2 values (∼6 ms) and a paucity of signal intensity during conventional image acquisition. The purpose of this study was to evaluate the feasibility of imaging postoperative menisci using an experimental, quantitative ultrashort echo time (UTE) MRI pulse sequence. This sequence acquires short echo images (echo time (TE) ∼0.3 ms) to produce multi-echo images for quantitative T2* calculations that provide an objective measure of collagen organization. MRI scans of the knee were acquired at 6- and 12-month intervals on a clinical 3.0 T scanner following meniscal surgery in eight patients (ages 13-41), four of whom underwent repair and the other four partial meniscectomy. Conventional MRI sequences were qualitatively evaluated for meniscal morphology and signal and correlated with quantitative UTE results. A wide range of mean T2* values for both postsurgical groups was measured, and these values changed for each patient between the 6- and 12-month intervals. In many instances, the UTE sequence demonstrated quantitative differences between the two time intervals that were not detected with conventional sequences. This pilot study presents preliminary, observational data to be used as a baseline for future studies. Although the T2* values did not reveal a trend in either group or correlate with expected signal changes on conventional MRI, we speculate that the UTE sequence may detect ultrastructural alterations in meniscal composition that are otherwise not perceived with routine fast spin echo (FSE) sequences.
    HSS Journal 07/2015; 11(2):123-9. DOI:10.1007/s11420-014-9420-x
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    ABSTRACT: The enhanced posterior soft tissue repair has reduced the frequency of dislocation after primary THA performed through the posterolateral approach. However, the long-term integrity of the repair is unknown and could influence surgeon choice regarding surgical technique and THA approach. We asked: (1) What is the durability of the enhanced posterior soft tissue repair at a minimum of 49 months using MRI to evaluate soft tissue to bone integrity? (2) How does the appearance of the posterior soft tissues change during this time? (3) Are there patient characteristics associated with the long-term imaging appearance of the posterior repair? All patients without a contraindication for MRI who were undergoing unilateral primary uncemented THA through a posterior approach between February and May 2005 were eligible for inclusion. Ninety percent consented to participate (36 of 40 patients), and 30 patients were followed prospectively with MRI postoperatively and again at 3 months; of those, 22 (73%; 12 men, 10 women) completed the study by having another MRI study at a minimum of 49 months (mean, 51 months; range, 49-59 months). Each patient underwent metal-artifact-reduction sequence MRI to evaluate the integrity of the posterior soft tissues, which had been repaired anatomically during primary THA at a minimum of 4 years earlier. The results were compared with those of prior MR images obtained immediately after surgery and at 3 months postoperatively. All patients were given a self-reported modified Harris hip score at the time of the most recent MRI study (maximum score = 81). At latest followup, 21 of 22 (96%) patients had a posterior capsule in contact with bone, and 21 of 22 (96%) had an intact quadratus femoris. Twenty-one patients (96%) had soft tissue or a scar from the piriformis and conjoined tendons in continuity with bone. In these cases, the interface between the piriformis and conjoined tendons and the greater trochanter observed immediately postoperatively and at 3 months postoperatively became filled with hypointense tissue, with signal characteristics similar to tendon. Time from surgery was most associated with changes in native tendon-to-bone distances (p < 0.001) and MRI signal intensity of the repair (p < 0.001). At followup of just more than 4 years, the posterior capsule and quadratus femoris most often were healed to bone. In the majority of patients, scar tissue between the piriformis and conjoined tendons and bone matured to achieve orientation and signal intensity resembling native tendon. We believe the enhanced posterior soft tissue repair facilitates this process. Our results provide a plausible explanation for improved postoperative stability observed in patients receiving an enhanced soft tissue repair compared with those in whom a repair is not performed. Level IV, therapeutic study.
    Clinical Orthopaedics and Related Research 06/2015; 473(10). DOI:10.1007/s11999-015-4380-0 · 2.77 Impact Factor
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    ABSTRACT: Purpose To describe the magnetic resonance (MR) imaging characteristics associated with adverse local tissue reactions and tissue damage around hip arthroplasties in which the recalled Rejuvenate modular dual-taper stem was used. Materials and Methods The institutional review board of the Hospital for Special Surgery approved the study. All study patients provided informed consent. MR imaging studies were retrospectively reviewed in a cohort of 58 patients with 66 hip arthroplasties with Rejuvenate stems who had presented for imaging evaluation because of recall of the implant. Multiple regression analysis was used to examine MR imaging features, biomechanical factors, and metal ion levels as predictors of aseptic lymphocytic vasculitis-associated lesion (ALVAL) score at histologic assessment while adjusting for age and sex for 54 revised hips. Results Revision surgery was performed in 54 hips on the basis of clinical or imaging findings (24% of hips were completely asymptomatic). The median ALVAL score among the revised hips was 9 (range, 1-10). Imaging characteristics observed with high frequency in patients with ALVAL included synovitis, mixed- or solid-type synovitis, synovial thickening, and capsular dehiscence. Conclusion MR imaging provides an effective noninvasive method for assessing the presence and severity of adverse local tissue reaction, as well as the degree of pre-existing tissue damage, thereby facilitating early and accurate identification of candidates for revision surgery. (©) RSNA, 2015.
    Radiology 06/2015; DOI:10.1148/radiol.2015141967 · 6.87 Impact Factor
  • Sarah L Pownder · Parina H Shah · Hollis G Potter · Matthew F Koff
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    ABSTRACT: Analysis of fresh specimens in research studies is ideal; however, it is often necessary to freeze samples for evaluation at a later time. Limited evaluation of the effect of freeze-thawing of tendon tissue samples on inherent magnetic resonance imaging (MRI) parameters, such as ultrashort echo time (UTE) T2* values, have been performed to date. This study performed UTE MRI on 14 bovine patellar tendons at harvest and after four consecutive freeze-thaw cycles. Results demonstrated a small but significant reduction (12%) in tendon T2* values after the first freeze thaw cycle, but not after successive cycles. Tendons from juvenile animals with open physis had a significant reduction of T2* following a single freeze thaw cycle, P<0.0001. The results of this study emphasize the importance of using uniform tendon storage protocols when using UTE MRI in preclinical models.
    06/2015; 5(3):368-73. DOI:10.3978/j.issn.2223-4292.2015.03.14
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    ABSTRACT: The purpose of this study was to evaluate whether patients with bilateral metal-on-metal (MoM) hip replacements have symmetric adverse local tissue reactions (ALTRs) at follow-up. An MRI of both hips was performed at a mean time of six years after surgery in 43 patients. The prevalence and severity of ALTRs were found to be similar in simultaneous hips but differences were observed in sequential hips. The order and timing of sequential hip arthroplasties did not affect the severity of ALTRs. Thus, in addition to metal ion exposure from an earlier MoM implant other factors may also play a role in the progression of ALTRs. Bilateral implants should be given special consideration in risk stratification algorithms for management of patients with MoM hip arthroplasty. Copyright © 2015. Published by Elsevier Inc.
    The Journal of arthroplasty 05/2015; DOI:10.1016/j.arth.2015.04.036 · 2.67 Impact Factor
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    ABSTRACT: Imaging of hip in osteoarthritis (OA) has seen considerable progress in the past decade, with the introduction of new techniques that may be more sensitive to structural disease changes. The purpose of this expert opinion, consensus driven recommendation is to provide detail on how to apply hip imaging in disease modifying clinical trials. It includes information on acquisition methods/techniques (including guidance on positioning for radiography, sequence/protocol recommendations/hardware for magnetic resonance imaging (MRI)); commonly encountered problems (including positioning, hardware and coil failures, artifacts associated with various MRI sequences); quality assurance/control procedures; measurement methods; measurement performance (reliability, responsiveness, and validity); recommendations for trials; and research recommendations. Copyright © 2015 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.
    Osteoarthritis and Cartilage 05/2015; 23(5):716-731. DOI:10.1016/j.joca.2015.03.004 · 4.17 Impact Factor
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    ABSTRACT: Tunnel widening after anterior cruciate ligament reconstruction (ACL-R) is a well-accepted and frequent phenomenon, yet little is known regarding its origin or natural history. To prospectively evaluate the cross-sectional area (CSA) changes in tibial and femoral bone tunnels after ACL-R with serial MRI. Case series; Level of evidence, 4. Patients underwent arthroscopic ACL-R with the same surgeon, surgical technique, and rehabilitation protocol. Each patient underwent preoperative dual-energy x-ray absorptiometry and clinical evaluation, as well as postoperative time zero MRI followed by subsequent MRI and clinical examination, including functional and subjective outcome tests, at 6, 12, 24, 52, and 104 weeks. Tibial and femoral tunnel CSA was measured on each MRI at tunnel aperture (ttA and ftA), midsection (ttM and ftM), and exit (ttE and ftE). Logistic regression modeling was used to examine the predictive value of demographic data and preoperative bone quality (as measured by dual-energy x-ray absorptiometry) on functional outcome scores, manual and instrumented laxity measurements, and changes in tunnel area over time. Eighteen patients (including 12 men), mean age 35.5 ± 8.7 years, underwent ACL-R. There was significant tunnel expansion at ttA and ftA sites 6 weeks postoperatively (P = .024 and .0045, respectively). Expansion continued for 24 weeks, with progressive tunnel narrowing thereafter. Average ttA CSA was significantly larger than ftA CSA at all times. The ttM significantly expanded after 6 weeks (P = .06); continued expansion to week 12 was followed by 21 months of reduction in tunnel diameter. The ftM and both ttE and ftE sites decreased in CSA over the 2 years. Median Lysholm and International Knee Documentation Committee scores significantly improved at final follow-up (P = .0083 and <.0001, respectively), and patients returned to preoperative activity levels. Pivot shift significantly decreased (P < .0001). Younger age (<30 years), male sex, and delayed ACL-R (>1 year from time of injury) predicted increased tunnel widening and accelerated expansion in CSA (P < .005). Tunnel expansion after ACL-R occurs early and primarily at the tunnel apertures. Expansion may not affect clinical outcome. Younger age, male sex, and delay from injury to ACL-R may be potential risks for enlargement. © 2015 The Author(s).
    The American Journal of Sports Medicine 02/2015; 43(5). DOI:10.1177/0363546515570461 · 4.36 Impact Factor
  • Darryl B Sneag · Eric A Bogner · Hollis G Potter
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    ABSTRACT: Optimization of metal artifact reduction pulse sequences over the past decade has rendered MRI valuable in knee arthroplasty assessment. MRI can reliably predict the presence and extent of infection, component loosening and polyethylene wear, and component malrotation, and it can evaluate the integrity of surrounding soft tissue structures. Using dynamic contrast-enhanced angiographic techniques, vascular pathology such as pseudoaneurysm formation and recurrent hemarthrosis can also be assessed. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.
    Seminars in musculoskeletal radiology 02/2015; 19(1):40-8. DOI:10.1055/s-0034-1396766 · 1.09 Impact Factor
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    ABSTRACT: Reason for performing studyPostoperative imaging in subjects with orthopaedic implants is challenging across all modalities. Magnetic resonance imaging (MRI) is preferred to assess human postoperative musculoskeletal complications, as soft tissue and bones are evaluated without using ionising radiation. However, with conventional MRI pulse sequences, metal creates susceptibility artifact that distorts anatomy. Assessment of the postoperative equine patient is arguably more challenging due to the volume of metal present, and MRI is often not performed in horses with implants. Novel pulse sequences such as multi-acquisition variable resonance image combination (MAVRIC) now provide improved visibility in the vicinity of surgical-grade implants and offer an option for imaging horses with metal implants.Objectives To compare conspicuity of regional anatomy in an equine fracture-repair model using MAVRIC, narrow receiver bandwidth fast spin echo (NBW FSE), and wide receiver bandwidth (WBW) FSE sequences.Study DesignNon-randomised in vitro experiment.MethodsMAVRIC, NBW FSE and WBW FSE were performed on 9 cadaveric distal limbs with fractures and stainless steel implants in the 3rd metacarpal bone and proximal phalanx. Objective measures of artifact reduction were performed by calculating the total artifact area in each transverse image as a percentage of the total anatomic area. The number of transverse images in which fracture lines were visible was tabulated for each sequence. Regional soft tissue conspicuity was assessed subjectively.ResultsOverall anatomic delineation was improved using MAVRIC compared to NBW FSE; delineation of structures closest to the metal implants was improved using MAVRIC compared to WBW FSE and NBW FSE. Total artifact area was the highest for NBW FSE and lowest for MAVRIC; the total number of transverse slices with a visible fracture line was highest in MAVRIC and lowest in NBW FSE.ConclusionMAVRIC and WBW FSE are feasible additions to minimise artifact around implants.
    Equine Veterinary Journal 01/2015; DOI:10.1111/evj.12424 · 2.37 Impact Factor
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    ABSTRACT: Anterior cruciate ligament (ACL) reconstruction in skeletally immature patients can result in growth disturbance due to iatrogenic physeal injury. Multiple physeal-sparing ACL reconstruction techniques have been described; however, few combine the benefits of anatomic reconstruction using sockets without violation of the femoral or tibial physis.
    The American Journal of Sports Medicine 10/2014; 42(12). DOI:10.1177/0363546514552994 · 4.36 Impact Factor
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    ABSTRACT: PurposeIt has previously been demonstrated that increased overlap of spectral bins in three-dimensional multispectral imaging techniques (3D-MSI) can aid in reducing residual artifacts near metal implants. However, increasing spectral overlap also necessitates consideration of saturation effects for species with long T1 values. Here, an interleaved spectral bin acquisition strategy is presented for overlapping 3D-MSI that allows for flexible choice of repetition times while simultaneously addressing these cross talk concerns.MethodsA phantom imaging experiment is used to illustrate the amplified effect of cross talk on 3D-MSI acquisitions. A methodological approach to address cross talk across a variety of prescribed repetition times is then described. Using the presented principles, a clinical subject with a total hip replacement was imaged to generate T1, proton density, and short-tau inversion recovery contrasts. In addition, a fracture instrumentation case was imaged pre- and postcontrast using T1-weighted spectrally overlapped 3D-MSI.ResultsPhantom results demonstrate that conventional spectral interleaving approaches can generate unwanted signal characteristics in heavily overlapped 3D-MSI. Clinical images using the presented methods successfully demonstrate T1, proton density, and inversion recovery image contrasts using heavily overlapped 3D-MSI.Conclusions Through automated management of spectral bin distributions across multiple interleaves, a variety of longitudinal magnetization contrasts can efficiently be acquired without any clinically relevant cross-talk impact using heavily overlapped 3D-MSI. Magn Reson Med, 2014. © 2014 Wiley Periodicals, Inc.
    Magnetic Resonance in Medicine 10/2014; DOI:10.1002/mrm.25518 · 3.57 Impact Factor
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    ABSTRACT: Background Magnetic resonance (MR) imaging evaluation of the painful failed shoulder arthroplasty is a useful imaging modality due to advancements in metal artifact reduction techniques, which allow assessment of the integrity of the supporting soft-tissue envelope and the implant. Questions/Purposes The focus of this pictorial review is to illustrate the benefits of MR imaging, whether used alone or as an adjunct to other imaging modalities, in aiding the clinician in the complex decision making process. Methods A PubMed (MEDLINE) search focusing on the complications and imaging assessment of shoulder arthroplasty was performed. Articles were selected for review based on their pertinence to the aforementioned topics. Results We discuss the ability of MR imaging to identify why a patient’s arthroplasty may have failed. Specific causes including component loosening and implant failure, rotator cuff and deltoid integrity, infection, subtle fractures, and nerve pathology are reviewed, with illustrative sample images. Conclusion MRI is a valuable tool in the assessment for pathology in the shoulder following arthroplasty.
    HSS Journal 10/2014; 10(3):213-24. DOI:10.1007/s11420-014-9399-3
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    ABSTRACT: Tendinopathy affects individuals who perform repetitive joint motion. Magnetic resonance imaging (MRI) is frequently used to qualitatively assess tendon health, but quantitative evaluation of inherent MRI properties of loaded tendon has been limited. This study evaluated the effect of cyclic loading on [Formula: see text] values of fresh and frozen rabbit patellar tendons using ultra short echo (UTE) MRI. Eight fresh and 8 frozen rabbit lower extremities had MR scans acquired for tendon [Formula: see text] evaluation. The tendons were then manually cyclically loaded for 100 cycles to 45N at approximately 1Hz. The MR scanning was repeated to reassess the [Formula: see text] values. Analyses were performed to detect differences of tendon [Formula: see text] values between fresh and frozen samples prior to and after loading, and to detect changes of tendon [Formula: see text] values between the unloaded and loaded configurations. No difference of [Formula: see text] was found between the fresh and frozen samples prior to or after loading, p=0.8 and p=0.1, respectively. The tendons had significantly shorter [Formula: see text] values, p=0.023, and reduced [Formula: see text] variability, p=0.04, after cyclic loading. Histologic evaluation confirmed no induced tendon damage from loading. Shorter [Formula: see text] , from stronger spin-spin interactions, may be attributed to greater tissue organization from uncrimping of collagen fibrils and lateral contraction of the tendon during loading. Cyclic tensile loading of tissue reduces patellar tendon [Formula: see text] values and may provide a quantitative metric to assess tissue organization.
    Journal of Biomechanics 09/2014; 47(13). DOI:10.1016/j.jbiomech.2014.08.018 · 2.75 Impact Factor
  • Matthew F Koff · Parina Shah · Hollis G Potter
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    ABSTRACT: Objective: The purpose of this article is to explain the basic physics of imaging patients with metal implants, explain conflicting information regarding MRI scanning of "MR Conditional" devices, and relate our experience of scanning total joint arthroplasty (TJA) at our institution. Conclusion: MRI near TJA is effective with appropriate imaging protocols and standardized safety precautions. Strict adherence to MR Conditional labeling may preclude broad use of MRI for TJA assessment.
    American Journal of Roentgenology 07/2014; 203(1):154-61. DOI:10.2214/AJR.13.11991 · 2.73 Impact Factor
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    Jan Fritz · Brett Lurie · Theodore T Miller · Hollis G Potter
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    ABSTRACT: Hip arthroplasty has become the standard treatment for end-stage hip disease, allowing pain relief and restoration of mobility in large numbers of patients; however, pain after hip arthroplasty occurs in as many as 40% of cases, and despite improved longevity, all implants eventually fail with time. Owing to the increasing numbers of hip arthroplasty procedures performed, the demographic factors, and the metal-on-metal arthroplasty systems with their associated risk for the development of adverse local tissue reactions to metal products, there is a growing demand for an accurate diagnosis of symptoms related to hip arthroplasty implants and for a way to monitor patients at risk. Magnetic resonance (MR) imaging has evolved into a powerful diagnostic tool for the evaluation of hip arthroplasty implants. Optimized conventional pulse sequences and metal artifact reduction techniques afford improved depiction of bone, implant-tissue interfaces, and periprosthetic soft tissue for the diagnosis of arthroplasty-related complications. Strategies for MR imaging of hip arthroplasty implants are presented, as well as the imaging appearances of common causes of painful and dysfunctional hip arthroplasty systems, including stress reactions and fractures; bone resorption and aseptic loosening; polyethylene wear-induced synovitis and osteolysis; adverse local tissue reactions to metal products; infection; heterotopic ossification; tendinopathy; neuropathy; and periprosthetic neoplasms. A checklist is provided for systematic evaluation of MR images of hip arthroplasty implants. MR imaging with optimized conventional pulse sequences and metal artifact reduction techniques is a comprehensive imaging modality for the evaluation of the hip after arthroplasty, contributing important information for diagnosis, prognosis, risk stratification, and surgical planning. ©RSNA, 2014.
    Radiographics 07/2014; 34(4):E106-E132. DOI:10.1148/rg.344140010 · 2.60 Impact Factor

Publication Stats

6k Citations
616.53 Total Impact Points


  • 1992–2015
    • Hospital for Special Surgery
      • Department of Orthopaedic Surgery
      New York, New York, United States
  • 1989–2015
    • Cornell University
      • • Department of Orthopaedic Surgery
      • • Department of Radiology
      • • Department of Surgery
      Итак, New York, United States
  • 2014
    • Rush University Medical Center
      Chicago, Illinois, United States
  • 2000–2014
    • Weill Cornell Medical College
      • • Department of Radiology
      • • Department of Orthopaedic Surgery
      New York City, New York, United States
  • 2011
    • Advance MRI
      Frisco, Texas, United States
  • 2010
    • Brown University
      Providence, Rhode Island, United States
  • 2009
    • Pennsylvania Medical Society
      Philadelphia, Pennsylvania, United States
  • 2008
    • Harvard Medical School
      Boston, Massachusetts, United States
  • 2004
    • University of Colorado at Boulder
      Boulder, Colorado, United States
  • 2002
    • Albert Einstein College of Medicine
      New York City, New York, United States
  • 1997
    • Brigham and Women's Hospital
      • Department of Orthopaedic Surgery
      Boston, MA, United States
  • 1995
    • Philadelphia University
      Filadelfia, Pennsylvania, United States