Component Fracture in the Kotz Modular Femoral Tibial Reconstruction System: An Under-Reported Complication.

BACKGROUND: Primary bone tumors of the femur are commonly reconstructed using an endoprosthesis. Different modes of implant failure have been described, including structural failure; although uncommon, this may be an under-reported complication. The purpose of this study is to examine the rates and risk factors for implant fracture of the Kotz Modular Femoral Tibial Reconstruction system (KMFTR). METHODS: Two hundred twenty-one patients (95 women and 126 men) who underwent a KMFTR reconstruction were reviewed. Twenty-seven patients (12%) sustained a prosthetic fracture. The mean time to fracture was 7 years postoperatively. The fractured component most commonly involved the distal femur (n = 21) and a screw hole in the stem (n = 12). In patients with stem fractures (n = 21), the mean intramedullary stem diameter was 12 mm and the mean extramedullary component length was 18 cm. RESULTS: Compared to patients who did not fracture, those with a prosthetic fracture had a significantly smaller stem diameter (12 vs 14 mm, P = .001) and a significantly longer extramedullary component length (18 vs 15 cm, P = .04). There was no difference between the preoperative and postoperative Toronto Extremity Salvage Scores (P = .98), Musculoskeletal Tumor Society 87 (P = .78), or Musculoskeletal Tumor Society 93 (P = 1.0) ratings for patients with or without a prosthetic fracture. CONCLUSION: This study shows that fracture is an under-reported complication associated with the KMFTR stem. We identified an endoprosthetic component fracture rate of 12%. Patients with smaller stem diameter and longer resection lengths were more likely to sustain a stem fracture. Subsequent revision provides a durable means of reconstruction, with no significant loss of patient function.

Comparing the Interobserver Reliability of 4 Methods Used to Measure Knee Laxity on Coronal Plane Stress Radiograph.

Background: Varus and valgus knee stress radiographs provide valuable information in the pre- and postoperative evaluation of joint laxity in patients with multiligament knee injuries (MLKIs). Purpose: To review the literature for described techniques of quantifying laxity on coronal stress radiographs of the knee and identify the most reliable method. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: A thorough literature search using the MEDLINE and Embase databases identified 4 studies with distinct methods for objectively measuring laxity on varus and valgus stress radiographs: Heesterbeek et al (2008), Jacobsen (1976), LaPrade et al (2004), and Sawant et al (2004). To compare these methods, 200 coronal plane stress radiographs from 50 patients with MLKIs were retrospectively reviewed from an MLKI database at a single institution. The amount of varus and valgus laxity on each radiograph was measured independently by 4 reviewers using each method. Intraclass correlation coefficients (ICCs) with 95% CIs were calculated to assess the interobserver reliability of each method overall and the varus and valgus measurements individually. Results: For all 4 methods, the overall interobserver reliability was considered at least moderate. The method by Heesterbeek et al proved to have the highest interrater reliability in all domains-overall (ICC, 0.87 [95% CI, 0.85-0.90]), valgus (ICC, 0.83 [95% CI, 0.78-0.88]), and varus (ICC, 0.87 [95% CI, 0.83-0.90])-demonstrating good to excellent reliability both overall and in varus measurements and showing good reliability in valgus measurements. The method by Sawant et al demonstrated good reliability in valgus measurements. All other measures demonstrated moderate reliability. Conclusion: Available methods for measuring knee joint laxity on varus and valgus knee stress radiographs in patients with MLKIs demonstrated moderate to good interobserver reliability. The method described by Heesterbeek et al proved to have the highest reliability overall as well as in measurements on varus and valgus views individually.

Immersive Virtual Reality and Cadaveric Bone are Equally Effective in Skeletal Anatomy Education: A Randomized Crossover Noninferiority Trial.

OBJECTIVE: Immersive virtual reality (IVR) technology is transforming medical education. Our aim was to compare the effectiveness of IVR with cadaveric bone models in teaching skeletal anatomy. DESIGN: A randomized crossover noninferiority trial was conducted. SETTING: Anatomy laboratory of a large medical school. PARTICIPANTS: Incoming first-year medical students. Participants were randomized to IVR or cadaveric groups studying upper limb skeletal anatomy, and then were crossed over to use the opposite tool, to study lower limb skeletal anatomy. Participants in both groups completed a pre-and postintervention knowledge test. The primary endpoint of the study was change in performance from the pre-to postintervention knowledge test. Surveys were completed to assess participant's impressions on IVR as an educational tool. RESULTS: Fifty first-year medical students met inclusion criteria and were randomized. Among all students, the average score on the preintervention knowledge test was 14.6% (standard deviation (SD) = 18.2%) and 25.0% (SD = 17%) for upper and lower limbs, respectively. Percentage increase in scores between pre-and postintervention knowledge test, was 15.0% in the upper limb IVR group, and 16.7% for upper limb cadaveric bones (p = 0.286). For the lower limb, score increase was 22.6% in the IVR and 22.5% in the cadaveric bone group (p = 0.936). 79% of participants found that IVR was most valuable for teaching 3-dimensional orientation, anatomical relationships, and key landmarks. Majority of participants were favorable towards combination use of traditional methods and IVR technology for learning skeletal anatomy (LSM>3). CONCLUSIONS: In this randomized controlled trial, there was no significant difference in knowledge after using IVR or cadaveric bones for skeletal anatomy education. These findings have further implications for medical schools that face challenges in acquiring human cadavers and cadaveric parts.

Adjuvant Medial Collateral Ligament Release at the Time of Knee Arthroscopy: A Controlled Percutaneous Technique.

The posterior horn of the medial meniscus can be challenging to view during arthroscopy because the medial femoral condyle obstructs vision, especially in tight medial compartments. Previous studies have described techniques for improving access, one being a percutaneous medial collateral ligament (MCL) release. This technique allows for increased medial compartment space, which offloads a tight medial compartment, minimizes iatrogenic chondral injury, incomplete meniscal resection, uncontrolled MCL rupture, and allows for accurate diagnosis and management. Studies have proven the safety of the controlled percutaneous MCL release, with no significant postoperative MCL laxity on stress views, no subjective patient instability, fewer iatrogenic cartilage lesions, and no saphenous neurovascular injury. Furthermore, retrospective studies have shown improved postoperative patient-reported outcomes with a controlled percutaneous MCL release in comparison to standard of care without a release. We hypothesize that a controlled percutaneous release of the MCL effectively alleviates some of the pressure within the medial compartment, which could potentially explain the improved postoperative clinical outcomes. This technique also facilitates improved visualization, a decreased risk of iatrogenic chondral injury, and a more complete meniscal resection. The purpose of this Technical Note is to describe our surgical technique and provide surgical pearls for a controlled percutaneous MCL release during knee arthroscopy.

Systematic Arthroscopic Treatment of Synovial Chondromatosis of the Knee.

Synovial chondromatosis is a benign metaplastic disease of the synovial joints, characterized by the development of cartilaginous nodules in the synovium. Treatment generally includes open or arthroscopic loose body removal combined with a synovectomy. An all-arthroscopic approach has been described to minimize complications and reduce morbidity while providing adequate control of local disease. The purpose of this Technical Note is to describe our techniques and technical pearls that allow for adequate excision of disease while minimizing complications and disease recurrence. The combination of patient positioning, the establishment of multiple arthroscopic portals to ensure optimal visualization and freedom of instruments, the use of a leg holder, and the use of a variety of surgical instruments to facilitate loose body removal and synovectomy is critical to optimize clinical outcomes and minimize complications. Although technically demanding, our described technique can help facilitate extensive loose body removal and complete synovectomy.

A Nonliquid Crystal Display Screen Computer for Treatment of Photosensitivity and Computer Screen Intolerance in Post-Concussion Syndrome.

Liquid crystal display (LCD) screens refresh at a rate of 60 times per second, which can be perceived by concussed individuals who have photosensitivity, leading to computer intolerance. A non-LCD computer screen that refreshes at a much lower rate could relieve this photosensitivity and computer screen intolerance in patients with post-concussion syndrome (PCS). Twenty-nine patients with PCS, computer intolerance, and photosensitivity performed a reading task for a maximum of 30 min, with an LCD computer or a non-LCD device, and were given a comprehension test after completion of the reading task. The Sport Concussion Assessment Tool 3 was administered before and after each reading task. Symptom scores, amount of time spent reading, and performance on the comprehension tests were compared between the two devices. Patients also completed a self-report questionnaire of their subjective experience. The LCD screen computer produced significantly greater symptom exacerbation (median difference = 5, W = 315, p < 0.01) and a greater number of symptoms (median difference = 1, W = 148, p < 0.01) than the non-LCD screens. The non-LCD screen resulted in a longer symptom-free reading time (median = 48 sec, W = 147, p < 0.01), but not a greater number of words read (median = 281, W = 148, p = 0.098). Females were more likely to have greater symptom exacerbation with the LCD screen (U = 14.0, p < 0.01). No significant difference was found in performance on the comprehension test. Subjective reports showed that the non-LCD experience was more favorable, and most patients stated they would recommend this device for other patients with PCS. This study is the first to show the clinical utility of non-LCD screen computers in the management of photosensitivity and computer screen intolerance in patients with PCS. The non-LCD screen computer has the potential to facilitate return-to-work or return-to-school in concussed individuals.

Identification of telomerase RNAs from filamentous fungi reveals conservation with vertebrates and yeasts.

Telomeres are the nucleoprotein complexes at eukaryotic chromosomal ends. Telomeric DNA is synthesized by the ribonucleoprotein telomerase, which comprises a telomerase reverse transcriptase (TERT) and a telomerase RNA (TER). TER contains a template for telomeric DNA synthesis. Filamentous fungi possess extremely short and tightly regulated telomeres. Although TERT is well conserved between most organisms, TER is highly divergent and thus difficult to identify. In order to identify the TER sequence, we used the unusually long telomeric repeat sequence of Aspergillus oryzae together with reverse-transcription-PCR and identified a transcribed sequence that contains the potential template within a region predicted to be single stranded. We report the discovery of TERs from twelve other related filamentous fungi using comparative genomic analysis. These TERs exhibited strong conservation with the vertebrate template sequence, and two of these potentially use the identical template as humans. We demonstrate the existence of important processing elements required for the maturation of yeast TERs such as an Sm site, a 5' splice site and a branch point, within the newly identified TER sequences. RNA folding programs applied to the TER sequences show the presence of secondary structures necessary for telomerase activity, such as a yeast-like template boundary, pseudoknot, and a vertebrate-like three-way junction. These telomerase RNAs identified from filamentous fungi display conserved structural elements from both yeast and vertebrate TERs. These findings not only provide insights into the structure and evolution of a complex RNA but also provide molecular tools to further study telomere dynamics in filamentous fungi.