Abstract Purpose We describe a Canadian phase III randomized controlled trial of stereotactic body radiotherapy (SBRT) versus conventionally hypofractionated radiotherapy (CRT) for the treatment of ...stage I medically inoperable non-small cell lung cancer (OCOG-LUSTRE Trial). Methods Eligible patients are randomized in a 2:1 fashion to either SBRT (48 Gy in 4 fractions for peripherally located lesions; 60 Gy in 8 fractions for centrally located lesions) or CRT (60 Gy in 15 fractions). The primary outcome of the study is 3-year local control (LC) which we hypothesize will improve from 75% with CRT to 87.5% with SBRT. With 85% power to detect a difference of this magnitude (hazard ratio=0.46), a two-sided α=0.05 and a 2:1 randomization, we require a sample size of 324 patients (216 SBRT, 108 CRT). Important secondary outcomes include overall survival, disease-free survival, toxicity, radiation-related treatment death, quality of life, and cost-effectiveness. A robust radiation therapy quality assurance program has been established to assure consistent and high quality SBRT and CRT delivery.
Early periprosthetic fractures after total knee arthroplasty are rare but devastating complications which require revision surgery and lead to poor patient satisfaction. We present 2 siblings who ...underwent primary total knee arthroplasty on the same day and then both presented 2 weeks after surgery with atraumatic periprosthetic femur fractures. The first patient underwent revision for a cemented distal femoral replacement with stemmed tibial fixation. The second patient underwent an isolated femoral component revision with a stemmed femoral component and distal augment. Histological evaluation identified significant peri-implant osteoporosis. The variation in complexity associated with early periprosthetic femoral insufficiency fractures is highlighted by these 2 cases. Surgeons may consider using stemmed femoral components in similar patients if poor distal femoral bone stock is encountered intraoperatively.
We present a rare case of a patient who presented with complete and rapid wear-through of a ceramic femoral head through a polyethylene liner and titanium acetabular cup. In addition, this patient ...exhibited significantly elevated serum titanium ion levels, which may serve as a marker of severe metallosis in cases where the preoperative plain radiographs underestimate signs of periarticular metal debris. The unique findings of this case include the rapid (less than 1 year time) wear-through of the femoral head in interval radiographs and the dramatic progression of metallosis and pelvic and femoral osteolysis that required both component revision. In addition, the markedly elevated titanium levels secondary to cup wear-through are also of interest and demonstrate a systemic manifestation of abrasive wear of a titanium alloy component.
Abstract Background Laparoscopic psychomotor skills are challenging to learn and objectively evaluate. The Fundamentals of Laparoscopic Skills (FLS) program provides a popular, inexpensive, ...widely-studied, and reported method for evaluating basic laparoscopic skills. With an emphasis on training safety before efficiency, we present data that explore the metrics in the FLS curriculum. Materials and methods A multi-institutional ( n = 3) cross-sectional study enrolled subjects ( n = 98) of all laparoscopic skill levels to perform FLS tasks in an instrumented box trainer. Recorded task videos were postevaluated by faculty reviewers ( n = 2) blinded to subject identity using a modified Objective Structured Assessment of Technical Skills (OSATS) protocol. FLS scores were computed for each completed task and compared with demographically established skill levels (training level and number of procedures), video review scoring, and objective performance metrics including path length, economy of motion, and peak grasping force. Results Three criteria used to determine expert skill, training and experience level, blinded review of performance by faculty via OSATS, and FLS scores, disagree in establishing concurrent validity for determining “true experts” in FLS tasks. FLS-scoring exhibited near-perfect correlation with task time for all three tasks (Pearson r = 0.99, 1.00, 1.00 with P <0.00000001). FLS error penalties had negligible effect on FLS scores. Peak grasping force did not correlate with task time or FLS scores. Conclusions FLS technical skills scores presented negligible benefit beyond the measurement of task time. FLS scoring is weighted more toward speed than precision and may not significantly address poor tissue handling skills, especially regarding excessive grasping force. Categories of experience or training level may not form a suitable basis for establishing proficiency thresholds or for construct validity studies for technical skills.
Abstract Background Adverse local tissue reaction formation has been suggested to occur with the Modular Dual Mobility (MDM) acetabular design. Few reports in the literature have evaluated fretting ...and corrosion damage between the acetabular shell and modular metal inserts in this modular system. We evaluated a series of 18 retrieved cobalt chromium MDM inserts for evidence of fretting and corrosion. Methods We assessed the backsides of 18 MDM components for evidence of fretting and corrosion in polar and taper regions based on previously established methods. We collected and assessed 30 similarly designed modular inserts retrieved from metal-on-metal (MoM) total hip arthroplasties as a control. Results No specific pattern of fretting or corrosion was identified on the MDM inserts. Both fretting and corrosion were significantly greater in the MoM cohort than the MDM cohort, driven by higher fretting and corrosion scores in the engaged taper region of the MoM inserts. Conclusion MoM components demonstrated more fretting and corrosion than MDM designs, specifically at the taper region, likely driven by differences in the taper engagement mechanism and geometry among the insert designs. The lack of significant fretting and corrosion observed in the MDM inserts are inconsistent with recent claims that this interface may produce clinically significant metallosis and adverse local tissue reactions.
Abstract Background Dual mobility designs were introduced to increase stability and reduce the risk of dislocation, both being common reasons for surgical revision after total hip arthroplasty. The ...in vivo behavior of dual mobility constructs remains unclear, and to our knowledge, no data have been published describing in vivo surface damage to the polyethylene bearing surfaces. Methods We used surface damage assessed on the inner and outer polyethylene bearing surfaces in 33 short-term retrieved dual mobility liners as evidence of relative motion at the 2 bearings. A lever out test was performed to determine the force required for dislocation of the cobalt-chromium femoral head from the polyethylene liner. Results Both bearings showed damage; however, the inner polyethylene bearings had higher damage scores, lower prevalence of remaining machining marks, and higher incidence of concentric wear, all consistent with more motion at the inner polyethylene bearing. The inner polyethylene bearings also had a higher occurrence of embedded titanium debris. The damage sustained in vivo was insufficient to lead to intraprosthetic dislocation in any of the retrieved components. Lever out tests of 12 retrievals had a mean dislocation load of 261 ± 52 N, which was unrelated to the length of implantation. Conclusion Our short-term retrieval data of 33 highly cross-linked polyethylene dual mobility components suggest that although motion occurs at both bearing articulations, the motion of the femoral head against the inner polyethylene bearing dominates. Although damage was not severe enough to lead to intraprosthetic dislocation, failure may occur long term and should be assessed in future studies.
Abstract Femoral stems with dual-taper modularity were introduced to allow independent control of length, offset, and version. Corrosion and fretting related to micromotion at the neck-stem junction ...are thought to stimulate an adverse local tissue reaction (ALTR). Analysis of 60 consecutively retrieved modular-neck stem implants (Rejuvenate, Stryker) revised primarily for ALTR was done to determine the variables influencing corrosion and fretting patterns at the neck-stem interface. Taper damage evaluation was performed with stereomicrocopic analysis with two observers. Evidence of fretting and corrosion was seen at the neck-stem taper in all implants, including three implants revised for periprosthetic fractures within four weeks of the index surgery indicating that this process starts early. Femoral stems paired with the long overall neck lengths had significantly higher corrosion scores. Correlation of the corrosion severity at particular locations with the length of implantation suggests that the neck-stem junction experiences cyclic cantilever bending in vivo. The positive correlation between the length of implantation and fretting/corrosion scores bodes poorly for patients who still have this implant. Scanning electron microscopy on a subset of specimens was also performed to evaluate the black corrosion material. We strongly urge frequent follow-up exams for every patient with this particular modular hip stem.
Abstract Background The severity and location of adverse local tissue reaction seen in metal-on-polyethylene (MoP) total hip arthroplasty (THA) is not well described. Methods We retrospectively ...reviewed the records of patients who underwent a revision THA using our biomechanics database. We included all patients who underwent revision surgery for the diagnosis of ALTR with THA implants that had modularity solely at the head-neck junction and excluded patients with implant modularity at sites other than the head-neck junction. Magnetic resonance imaging (MRI) was evaluated by a fellowship trained radiologist who specializes in evaluating metal artifact reducing MRI sequences in order to quantify the ALTR lesions. Histology was evaluated for findings of ALTR using the Campbell score. Results We identified eleven patients in the database. Eight patients had a MRI ALTR grade of severe and seven did based on the histology score. The mean synovial volume was 218,658 mm3 (range 23,461-451,435 mm3) with a mean maximal synovial thickness of 15.3 mm (range 3-34.3 mm). A disruptive infiltration of the abductors due to pseudocapsule invasion was seen in 67% of the patients with three not having abductor involvement. Mean preoperative cobalt and chromium levels were 5.4 ppb (range 1-12.3) and 1.1 ppb (range 0.6-2.4) respectively. Conclusion Patients with ALTR from head-neck junction corrosion in MoP THA may present with large pseudotumors that have previously been under appreciated. Mean preoperative serum cobalt and chromium ion levels remained relatively low, and MRI was an effective way to characterize the size and location of these lesions.
Abstract A 58-year-old woman presented with onset of pain associated with a popping sound after a twisting motion 4 years after left total knee revision arthroplasty. She had a complex medical ...history, including a reported bone cement allergy, and presented to the hospital unable to bear weight. Plain radiographs revealed a broken femoral component, with the femoral metaphyseal sleeve separated from the distal articular component. During surgery, it was observed that the femoral adapter bolt and taper adapter had both fractured. Scanning electron microscopy of the fracture surfaces of the components confirmed that the implant had failed in fatigue, presumably due to high cyclic loads. Failure at this junction has not been described previously. In this type of knee design, we recommend supporting the distal articular component either with bone, augmentation, and/or bone cement to reduce the risk for this mode of failure.
Abstract Background Dual-taper modular stems have suffered from high revision rates caused by adverse local tissue reactions secondary to fretting and corrosion. We compared the fretting and ...corrosion behavior of a group of modular neck designs to that of a design that had been recalled for risks associated with fretting and corrosion at the modular neck junction. Methods We previously analyzed fretting and corrosion on 60 retrieved Rejuvenate modular neck-stem implants. Here we compare those results to results from 26 retrieved implants from 7 other modular neck designs. For the 26 additional cases, histology slides of tissue collected at revision were reviewed and graded for aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL). Multivariate analyses were performed to assess differences in fretting and corrosion, adjusting for confounding factors (e.g., length of implantation). Results The Rejuvenate design had higher damage and corrosion scores than the other seven designs (p<0.01). Histologic samples from the recalled design were 20 times more likely to show ALVAL than samples from the other designs (p<0.01). Mixed metal couples had higher fretting (p<0.01) and corrosion (p=0.02) scores than non-mixed metal couples. Conclusion Fretting and corrosion occurred on all modular neck-stem retrievals regardless of design. However, mixed metal couples suffered more corrosion than homogenous couples. This may be due to the lower modulus of the titanium alloy used for the stem, allowing for increased metal transfer and surface damage when loaded against a cobalt alloy modular neck, which in turn could account for the higher ALVAL and corrosion scores. Due to increased corrosion risk with mixed metals, and increased neck fracture risk with non-mixed metal stem and necks, we suggest that clinicians avoid implantation of modular neck-stem systems.
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