Erin A. Baker

Analysis of retrieved agility total ankle arthroplasty systems.

Background: First generation total ankle arthroplasty (TAA) systems showed high rates of failure. The Agility™ (DePuy, Warsaw, IN) TAA system, a second generation design, had improved outcomes; however, implant failure due to loosening of the metallic components persisted. The purpose of this study was to analyze the damage modes and radiographic mode(s) of failure observed in retrieved Agility™ TAA. Materials and Methods: Ten devices were collected and each component was analyzed for common damage modes using microscopy. Clinical damage was analyzed with postoperative implant and preoperative revision procedure radiographs. Results: Analyses revealed damage/wear to retrieved components, including abrasion, dishing, and pitting. These third-body wear particles may be a precursor to wear debris induced osteolysis which could cause component loosening. Seven TAA systems were removed due to loosening or subsidence, suggesting component damage/wear may lead to clinically observed component loosening. Retrieval analysis indicated the polyethylene experiences edge loading, resulting in increased contact stresses to polyethylene in the primary articulation region and wear. Conclusion: Since poor clinical outcomes have been associated with component instability and osteolysis, analyzing retrieved components wear and damage may be an important step toward improving implant design, thereby decreasing wear debris induced osteolysis and improving clinical outcomes. Level of Evidence: IV, Case Series

T1ρ magnetic resonance imaging for detection of early cartilage changes in knees of asymptomatic collegiate female impact and nonimpact athletes.

Objective:To determine if T1&rgr; magnetic resonance imaging (T1&rgr; MRI) could assess early articular cartilage changes in knees of asymptomatic female collegiate athletes. It was hypothesized that impact cohort would demonstrate greater changes than nonimpact cohort. Design:An institutional review board–approved prospective cohort study. Blinded MRI analyses. Setting:Participants from collegiate athletic program. Imaging at university hospital, February 2008 to July 2009. Participants:Inclusion criteria were female collegiate athletes in athletic season and asymptomatic. Exclusion criteria were previous/current knee injuries/surgeries. Twenty-one female NCAA Division I athletes, 11 impact (basketball players) and 10 nonimpact (swimmers) participants were consented and imaged with 3.0-T MRI (Siemens) and T1&rgr; sequence (University of Pennsylvania). One patient was removed (injury diagnosis). Final roster was 10 impact and 10 nonimpact participants. No difference in cohort body mass index, height, or weight. Main Outcome Measures:Average T1&rgr; relaxation times (ART) for patellar and femoral cartilage to analyze defined regions and depth and modified International Cartilage Repair Society classification. Results:Statistical analyses showed that ART of radial zone of central third weight-bearing region of cartilage in basketball players was significantly greater (P = 0.041) than swimmers and ART of the superficial zone in basketball players was significantly less (P = 0.003) than that of swimmers. For both groups, the ART of superficial zones were significantly greater than that of radial zones (P < 0.001). Four impact athletes showed macroscopic changes (none in nonimpact cohort). Conclusions:T1&rgr; MRI detected early changes in articular cartilage of asymptomatic collegiate female impact athletes, with significant differences between cohorts in radial zone of central third weight-bearing region and superficial zones ART. Both cohorts showed increased ART in superficial zone. Four impact athletes showed macroscopic changes. Clinical Relevance:This study demonstrates a quantitative MRI sequence able to detect signal differences in articular cartilage in asymptomatic athletes.

Case Series With Histopathologic and Radiographic Analyses Following Failure of Fresh Osteochondral Allografts of the Talus

Background: Fresh osteochondral allografting of the talus is one treatment option for large chondral defects. Following positive early term results, failure rates of up to 35% have been reported. A retrieval study was performed to characterize failed talar allografts. Methods: Failed fresh osteochondral allografts of the talus were retrieved on revision. Cases of deep infection were excluded. After tissue fixation, samples were decalcified, embedded, and stained with Safranin-O/Fast Green, osteocalcin, tumor necrosis factor alpha (TNF-α), CD4, CD8, and CD68. Slides were graded according to the modified Mankin scoring system or severity scale. Medical record review was performed. Results: Eight allografts (7 patients) were retrieved from patients, following an average term of implantation of 31 months (range, 12-58). There were 3 types of allografts in this series (hemidome, n=5; segmental, n=2; bipolar, n=1). Reasons for transplantation were post-traumatic arthritis or osteonecrosis; reasons for revision were graft failure/collapse, nonunion, progressive arthritis, and/or pain. Prior to revision, all grafts exhibited collapse and subchondral lucencies. At the graft host interface, Safranin-O staining demonstrated substantial loss of sulfated glycosaminoglycans, Osteocalcin immunostaning was nearly absent, CD68 (indicating osteoclast activity) was predominantly exhibited, and CD4+ helper T cells as well as CD8+ cytotoxic T cells and NK cells—cell types commonly implicated in allogeneic organ transplant rejection—were found in high concentrations. TNF-α was present throughout the graft. Conclusion: A histopathologic analysis of 8 retrieved, failed talar allografts was performed. Graft failure appeared to be primarily biologic, with an extensive loss of viable cartilaginous and osseous tissue at the graft-host interface. This study provides the first evidence of a potential CD4+ and CD8+ lymphocyte-mediated failure mechanism in fresh osteochondral allografts that were revised following collapse. Level of Evidence: Level IV, case series.

Missed Peritalar Injuries An Analysis of Factors in Cases of Known Delayed Diagnosis and Methods for Improving Identification

Because of the complex anatomy of the foot, rarity of fractures of the foot, and subtle radiographic cues, foot injuries are commonly overlooked and mis/undiagnosed. This study seeks to investigate a patient population whose peritalar injuries, including fractures and dislocations, were missed on initial examination, in order to analyze factors of known, missed injuries and provide insight into methods for reducing the incidence of missed diagnoses. Surgical cases between January 1999 and May 2011 were queried and retrospectively reviewed to identify missed peritalar injuries. Of 1682 surgical cases reviewed, 27 patients with missed peritalar injury(ies), which were subsequently confirmed by imaging studies, were identified. Using the Orthopaedic Trauma Association classification, fracture and dislocation subtypes were classified. A medical record review was performed to assess demographic and surgical data elements. In this study population, 7 types of peritalar injuries (talus, calcaneal, navicular, and cuboid fractures as well as subtalar, calcaneocuboid, and talonavicular joint dislocations) were diagnosed in 27 patients. All patients required surgical intervention. Talus fractures were the most commonly missed injury. In patients with multiple peritalar injuries, there was a strong correlation between talus and navicular fractures (r = −0.60; P < .01) as well as a moderate correlation between talus fractures and calcaneocuboid dislocations (r = −0.46; P = .02). The presence of a calcaneal fracture significantly decreased the time to definitive diagnosis (P = .01). Male patients’ diagnoses were delayed an average of 324 days and females 105 days (P = .04). A moderate correlation was found between patient age at injury and time to diagnosis (r = −0.47; P = .04), with a decreased time to diagnosis as patient age increased. Significant factors were identified in this patient population, including patient sex and age, which may contribute to missed or delayed diagnosis in the clinical setting. Prompt and accurate diagnosis of peritalar injuries may improve long-term outcomes. Levels of Evidence: Care Management, Level V

The adult paralytic foot.

&NA; The adult paralytic foot is a common clinical entity. It has numerous neurologic, systemic, and traumatic causes that result in muscle imbalance and foot deformity. A thorough physical examination and diagnostic work‐up, as well as an understanding of the relevant functional anatomy, are essential to proper management. Treatment goals include the establishment of a plantigrade foot, elimination of deforming forces, and, when possible, restoration of active motor control.

Analysis of in vivo corrosion of 316L stainless steel posterior thoracolumbar plate systems: a retrieval study.

Study Design One hundred eighteen patients retrieved 316L stainless steel thoracolumbar plates, of 3 different designs, used for fusion in 60 patients were examined for evidence of corrosion. A medical record review and statistical analysis were also carried out. Objective This study aims to identify types of corrosion and examine preferential metal ion release and the possibility of statistical correlation to clinical effects. Summary of Background Data Earlier studies have found that stainless steel spine devices showed evidence of mild-to-severe corrosion; fretting and crevice corrosion were the most commonly reported types. Studies have also shown the toxicity of metal ions released from stainless steel corrosion and how the ions may adversely affect bone formation and/or induce granulomatous foreign body responses. Methods The retrieved plates were visually inspected and graded based on the degree of corrosion. The plates were then analyzed with optical microscopy, scanning electron microscopy, and energy dispersive x-ray spectroscopy. A retrospective medical record review was performed and statistical analysis was carried out to determine any correlations between experimental findings and patient data. Results More than 70% of the plates exhibited some degree of corrosion. Both fretting and crevice corrosion mechanisms were observed, primarily at the screw plate interface. Energy dispersive x-ray spectroscopy analysis indicated reductions in nickel content in corroded areas, suggestive of nickel ion release to the surrounding biological environment. The incidence and severity of corrosion was significantly correlated with the design of the implant. Conclusions Stainless steel thoracolumbar plates show a high incidence of corrosion, with statistical dependence on device design.

Multidrug-Resistant Organisms in the Setting of Periprosthetic Joint Infection—Diagnosis, Prevention, and Treatment

BACKGROUND Periprosthetic joint infection (PJI) is a rare yet challenging problem in total hip and knee arthroplasties. The management of PJI remains difficult primarily due to the evolution of resistance by the infecting organisms. METHODS This review profiles acquired mechanisms of bacterial resistance and summarizes established and emerging techniques in PJI diagnosis, prevention, and treatment. RESULTS New techniques in PJI diagnosis and prevention continue to be explored. Antibiotics combined with 1 or 2-stage revision are associated with the higher success rates and remain the mainstay of treatment. CONCLUSION With higher prevalence of antibiotic-resistant organisms, novel antibiotic implant and wound care materials, improved methods for organism identification, and well-defined organism-specific treatment algorithms are needed to optimize outcomes of PJI.

Single-Surgeon Experience and Complications of a Fixed-Bearing Total Ankle Arthroplasty

Background: Total ankle arthroplasty (TAA) has historically resulted in inferior survivorship rates compared with total hip and knee arthroplasty, because of technical issues unique to ankle anatomy. In this study, a single-surgeon series of intra- and postoperative complications as well as resultant reoperations/revisions of the Tornier Salto Talaris, a fixed-bearing TAA prosthesis, were reviewed. Methods: Medical records from index procedure to latest follow-up of primary TAA were reviewed. Complications were categorized according to the Glazebrook classification; additional complications were documented. Concurrent procedures were recorded, and radiographs were analyzed for alignment, subsidence, and cyst formation. Time to complication onset and learning curve analyses were performed. One hundred four Salto Talaris TAA prostheses (96 patients), with an average follow-up of 46 months, were included. Results: Thirty-five complications were identified in 32 ankles with a 34% complication rate, resulting in 11 reoperations (5 TAA revisions). Technical error (n = 12), wound healing (n = 9), and aseptic loosening (n = 4) were the most common complications, and there were no statistically significant differences in demographics or follow-up duration between cases with versus without complications. In both the cohorts with and without complications, there were moderate, negative correlations between radiographically observed keel osteopenia and lucency (ρ = −0.548, P = .00125, and ρ = −0.416, P = .000303, respectively); also, in the complication cohort, a weak, positive correlation between subsidence and lucency (ρ = 0.357, P = .0450) was found. Conclusion: Salto Talaris TAA survivorship and reoperation rates in our series were comparable with previous reports, using either the same or similar mobile-bearing prostheses; new information regarding complication, radiographic, and learning curve analyses was presented. Level of Evidence: Level IV, retrospective case series.

Review of Mechanical, Processing, and Immunologic Factors Associated With Outcomes of Fresh Osteochondral Allograft Transplantation of the Talus:

Osteochondral lesions of the talus (OLTs) are an increasingly implicated cause of ankle pain and instability. Several treatment methods exist with varying clinical outcomes. Due in part to successful osteochondral allografting (OCA) in other joints, such as the knee and shoulder, OCA has gained popularity as a treatment option, especially in the setting of large lesions. The clinical outcomes of talar OCA have been inconsistent relative to the positive results observed in other joints. Current literature regarding OCA failure focuses mainly on 3 factors: the effect of graft storage conditions on chondrocyte viability, graft/lesion size, and operative technique. Several preclinical studies have demonstrated the ability for bone and cartilage tissue to invoke an immune response, and a limited number of clinical studies have suggested that this response may have the potential to influence outcomes after transplantation. Further research is warranted to investigate the role of immunological mechanisms as an etiology of OCA failure. Level of Evidence: Level V, expert opinion.

Effect of Component Design in Retrieved Bipolar Hip Hemiarthroplasty Systems

Primary articulation of bipolar hemiarthroplasty systems is at the femoral head-liner interface. The purpose of this study was to compare observed damage modes on 36 retrieved bipolar systems with implant, demographic, intraoperative, and radiographic data to elucidate the effects of component design, specifically locking mechanism, on clinical performance. Retrieved bipolar hip hemiarthroplasty systems of 3 different design types were obtained, disassembled, and evaluated macro- and microscopically for varying modes of wear, including abrasion, burnishing, embedding, scratching, and pitting. Clinical record review and radiographic analysis were performed by a senior orthopedic surgery resident. Average bipolar hip hemiarthroplasty system term of service was 46 months (range, 0.27-187 months). All devices contained wear debris captured within the articulating space between the femoral head and liner. In 31% of patients without infection, lucency was observed on immediate prerevision radiographs. The system with a leaf locking mechanism showed significantly increased radiographically observed osteolysis (P=.03) compared with a system with a stopper ring locking mechanism. In addition, implant design and observed damage modes, including pitting and third-body particle embedding, were significantly associated with radiographically observed osteolysis.