A comparison of 3-D CT and 2-D plain radiograph measurements of the wrist in extra-articular malunited fractures of the distal radius.

Two-dimensional (2-D) plain radiographs may be insufficient for the evaluation of distal radial malunion, as it is a three-dimensional (3-D) deformity. This study introduced a 3-D measuring method that outputs radial inclination, ulnar variance, palmar tilt and axial rotation. To this end, a standardized and clearly defined coordinate system was constructed that allowed 3-D measurements closely resembling the conventional 2-D method in 35 patients. Mean differences between 3-D and 2-D measurements in affected wrists were 1.8° for radial inclination, 0.8 mm for ulnar variance and 3.7° for palmar tilt. In addition, inter- and intra-observer reproducibility of all 3-D and 2-D measurements were good or excellent (intraclass correlation coefficient >0.75), with 3-D reproducibility always better than 2-D. Axial rotation was present in all patients with a mean of 7.9° (SD 6.9). Although the differences between 2-D and 3-D measurements were small, 3-D evaluation enables the assessment of axial rotation and brings us closer to a routine 3-D evaluation of malunion.Level of evidence: III.

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) reveals potential lipid markers between infrapatellar fat pad biopsies of osteoarthritis and cartilage defect patients.

The incidence of osteoarthritis (OA) has been expected to increase due to an aging population, as well as an increased incidence of intra-articular (osteo-) chondral damage. Lipids have already been shown to be involved in the inflammatory process of OA. This study aims at revealing region-specific lipid profiles of the infrapatellar fat pad (IPFP) of OA or cartilage defect patients by matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), which could be used as biomarkers for early OA detection. A higher presence of phospholipids was found in OA patients compared with cartilage defect patients. In addition, a higher abundance of ether-linked phosphatidylethanolamines (PE O-s) containing arachidonic acid was specifically found in OA patients compared with cartilage defect patients. These lipids were mainly found in the connective tissue of the IPFP. Specific lipid species were associated to OA patients compared with cartilage defect patients. PE O-s have been suggested as possible biomarkers for OA. As these were found more abundantly in the connective tissue, the IPFP's intra-tissue heterogeneity might play an important role in biomarker discovery, implying that the amount of fibrous tissue is associated with OA.

Near-Infrared Spectral Similarity between Ex Vivo Porcine and In Vivo Human Tissue.

BACKGROUND: In vivo diffuse reflectance spectroscopy provides additional contrast in discriminating nerves embedded in adipose tissue during surgery. However, large datasets are required to achieve clinically acceptable classification levels. This study assesses the spectral similarity between ex vivo porcine and in vivo human spectral data of nerve and adipose tissue, as porcine tissue could contribute to generate large datasets. METHODS: Porcine diffuse reflectance spectra were measured at 124 nerve and 151 adipose locations. A previously recorded dataset of 32 in vivo human nerve and 23 adipose tissue locations was used for comparison. In total, 36 features were extracted from the raw porcine to generate binary logistic regression models for all combinations of two, three, four and five features. Feature selection was performed by assessing similar means between normalized features of nerve and of adipose tissue (Kruskal-Wallis test, p < 0.05) and for models performing best on the porcine cross validation set. The human test set was used to assess classification performance. RESULTS: The binary logistic regression models with selected features showed an accuracy of 60% on the test set. CONCLUSIONS: Spectral similarity between ex vivo porcine and in vivo human adipose and nerve tissue was present, but further research is required.

The preferred technique for knee synovium biopsy and synovial fluid arthrocentesis.

For knee osteoarthritis and related conditions, analysis of biomarkers hold promise to improve early diagnosis and/or offer patient-specific treatment. To compare biomarker analyses, reliable, high-quality biopsies are needed. The aim of this work is to summarize the literature on the current best practices of biopsy of the synovium and synovial fluid arthrocentesis. Therefore, PubMed, Embase and Web of Science were systematically searched for articles that applied, demonstrated, or evaluated synovial biopsies or arthrocentesis. Expert recommendations and applications were summarized, and evidence for superiority of techniques was evaluated. Thirty-one studies were identified for inclusion. For arthrocentesis, the superolateral approach in a supine position, with a 0°-30° knee flexion was generally recommended. 18-gage needles, mechanical compression and ultrasound-guidance were found to give superior results. For blind and image-guided synovial biopsy techniques, superolateral and infrapatellar approaches were recommended. Single-handed tools were preconized, including Parker-Pearson needles and forceps. Sample quantity ranged approximately from 2 to 20. Suggestions were compiled for arthrocentesis regarding approach portal and patient position. Further evidence regarding needle size, ultrasound-guidance and mechanical compression were found. More comparative studies are needed before evidence-based protocols can be developed.

Topology optimization of a mandibular reconstruction plate and biomechanical validation.

OBJECTIVES: Reconstruction plates, used to bridge segmental defects of the mandible after tumor resection or traumatic bone tissue loss, are subjected to repeated stresses of mastication. High stress concentrations in these plates can result in hardware failure. Topology optimization (TO) could reduce the peak stress by computing the most optimal material distribution in a patient-specific implant (PSI) used for mandibular reconstruction. The objective of this study was biomechanical validation of a TO-PSI. METHODS: A computer-aided design (CAD) model with a segmental defect was created based on the geometry of a polyurethane mandible model. A standard-PSI was designed to bridge the defect. A TO-PSI was then designed with a maximum stress equal to the ultimate tensile stress of Ti6Al4V (930 MPa) during a loading condition of 378 N. Finite element analysis (FEA) was used to analyze stresses in both PSI designs during loading. The standard-PSI and TO-PSI designs were produced in triplicate by selective laser melting of Ti6Al4V, fixated to polyurethane mandible models with segmental defects identical to the CAD model, and subsequently subjected to continuous compression with a speed of 1 mm/min on a universal testing machine, while recording the load. Peak loads before failure in the TO-PSI group within a 30% range of the predicted peak load (378 N) were considered a successful biomechanical validation. RESULTS: Fracture of the TO-PSI occurred at a median peak load of 334 N (range 304-336 N). These values are within the 30% range of the predicted peak load. Fracture of the mandible model in the standard-PSI group occurred at a median peak load of 1100 N (range 1010-1460 N). Failure locations during biomechanical testing of TO-PSI and standard-PSI samples corresponded to regions in the FEA where stresses exceeded the ultimate tensile strength of titanium and polyurethane, respectively. CONCLUSION: This study demonstrates a successful preliminary biomechanical validation of TO in the design process for mandibular reconstruction plates. Further work is needed to refine the finite element model, which is necessary to ultimately design TO-PSIs for clinical use.

Feasibility Study to Determine if Microfracture Surgery Using Water Jet Drilling Is Potentially Safe for Talar Chondral Defects in a Caprine Model.

OBJECTIVE: Surgical microfracture is considered a first-line treatment for talar osteochondral defects. However, current rigid awls and drills limit access to all locations in human joints and increase risk of heat necrosis of bone. Using a flexible water jet instrument to drill holes can improve the reachability of the defect without inducing thermal damage. The aim of this feasibility study is to determine whether water jet drilling is potentially safe compared with conventional microfracture awls by studying side effects and perioperative complications, as well as the quality of cartilage repair tissue. DESIGN: Talar chondral defects with 6-mm diameter were created bilaterally in 6 goats (12 samples). One defect in each goat was treated with microfracture created with conventional awls, the contralateral defect was treated with holes created with 5-second water jet bursts at a pressure of 50 MPa. Postoperative complications were recorded and after 24 weeks analyses were performed using the ICRS (International Cartilage Repair Society) macroscopic score and modified O'Driscoll histological score. RESULTS: Several practical issues using the water jet in the operating theatre were noted. Water jet drilling resulted in fibrocartilage repair tissue similar to the repair tissue from conventional awls. CONCLUSIONS: These results suggest that water jet drilling gives adequate fibrocartilage repair tissue. Furthermore, the results highlight essential prerequisites for safe application of surgical water jet drilling: stable water pressure, water jet beam coherence, stable positioning of the nozzle head when jetting, and minimizing excessive fluid extravasation.

Validation of Simendo Knee Arthroscopy Virtual Reality Simulator.

PURPOSE: To determine the face and construct validity as well as educational value and user-friendliness of the Simendo knee arthroscopy virtual reality simulator. METHODS: Sixty participants were recruited and equally divided into novices (0 arthroscopic procedures), intermediates (1-59 arthroscopic procedures), and experts (60 or more arthroscopic procedures). Participants were excluded if they had previously trained with the studied simulator. Construct validity, that is, the ability to discriminate between different levels of expertise, was examined by a navigation task. All participants were asked to perform 5 navigation trials within 10 minutes. Face validity, educational value, and user-friendliness were examined by questionnaires before and after the navigation trials. Face validity is the subjective impression of how closely the simulation replicates the real environment. RESULTS: The novices were significantly slower than the intermediates in the first (P < .001) and the third (P = .031) trial. The novices were significantly slower than the experts in all trials (P = .016), except for the fifth (P = .054). The experts were significantly faster than the intermediates in every trial except for the fourth (P = .069). Median task time for the fifth trial was 63 seconds (44-80 seconds) for novices, 58 seconds (46-80 seconds) for intermediates, and 41 seconds (33-55 seconds) for experts. Ninety-two percent of all participants agreed that the simulator can be used to train for surgical inspection, and 95% indicated sufficient user-friendliness. CONCLUSIONS: Based on the results, this knee simulator can be applied to train the basic arthroscopic hand-eye coordination skills at the start of resident education programs. Further testing is necessary to determine whether the skills are retained. CLINICAL RELEVANCE: The simulator is partly validated, which contributes to training of basic arthroscopic skills without compromising patient safety.

How do jet time, pressure and bone volume fraction influence the drilling depth when waterjet drilling in porcine bone?

Using water jets for orthopedic procedures that require bone drilling can be beneficial due to the absence of thermal damage and the always sharp cut. Previously, the influence of the water jet diameter and bone architectural properties on the drilling depth have been determined. To develop water jet instruments that can safely drill in orthopedic surgery, the impact of the two remaining primary factors were determined: the jet time (tjet [s]) and pressure (P [MPa]). To this end, 84 holes were drilled in porcine tali and femora with water jets using Ø 0.4mm nozzle. tjet was varied between 1, 3 and 5s and P between 50 and 70MPa. Drilling depths Lhole (mm), diameters Dhole (mm) and the volume of mineralized bone per unit volume (BV/TV) were determined with microCT scans. A non-linear regression analysis resulted in the predictive equation: Lhole= 0.22 * tjet(0.18) * (1.2-BV/TV) * (P-29) (R(2)=0.904). The established relation between the machine settings and drilling depth allows surgeons to adjust jet time and pressure for the patient׳s BV/TV to drill holes at a predetermined depth. For developers, the relation allows design decisions to be made that influence the dimensions, flexibility and accuracy of water jet instruments. For a pressure of 50MPa, the potential hole depth spread indicated by the 95% confidence interval is <1.6mm for all tested jet times. This maximum variance is smaller than the accuracy required for bone debridement treatments (2-4mm deep), which confirms that water jet drilling can be applied in orthopedic surgery to drill holes in bone with controlled depth.

Navigation forces during wrist arthroscopy: assessment of expert levels.

PURPOSE: To facilitate effective and efficient training in skills laboratory, objective metrics can be used. Forces exerted on the tissues can be a measure of safe tissue manipulation. To provide feedback during training, expert threshold levels need to be determined. The purpose of this study was to define the magnitude and the direction of navigation forces used during arthroscopic inspection of the wrist. METHODS: We developed a set-up to mount a cadaver wrist to a 3D force platform that allowed measurement of the forces exerted on the wrist. Six experts in wrist arthroscopy performed two tasks: (1) Introduction of the camera and visualization of the hook. (2) Navigation through the wrist with visualization of five anatomic structures. The magnitude (Fabs) and direction of force were recorded, with the direction defined as α being the angle in the vertical plane and ß being the angle in the horizontal plane. The 10th-90th percentile of the data were used to set threshold levels for training. RESULTS: The results show distinct force patterns for each of the anatomic landmarks. Median Fabs of the navigation task is 3.8 N (1.8-7.3), α is 3.60 (-54-44) and ß is 260 (0-72). CONCLUSION: Unique expert data on navigation forces during wrist arthroscopy were determined. The defined maximum allowable navigation force of 7.3 N (90th percentile) can be used in providing feedback on performance during skills training. The clinical value is that this study contributes to objective assessment of skills levels.

Design of a box trainer for objective assessment of technical skills in single-port surgery.

OBJECTIVE: Laparoscopic single-port (SP) surgery uses only a single entry point for all instruments. The approach of SP has been applied in multiple laparoscopic disciplines owing to its improved cosmetic result. However, in SP surgery, instrument movements are further restricted, resulting in increased instrument collisions compared with standard multiport (MP) laparoscopy. METHODS: Our goal was to develop a trainer that can quantitatively measure task time, force and motion data during both MP and SP training to investigate the influence of instrument configuration on performance. Custom-made abdominal force sensors and accelerometers were integrated into a new training box that can be used in an SP and an MP configuration. This new box trainer measures forces, acceleration, and tilt angles during training of SP and MP laparoscopy. With the new trainer, 13 novices performed a tissue manipulation task to test whether significant differences exist between MP and SP in maximum abdominal force, maximum tissue manipulation force, maximum acceleration, and tilt angles of the handles. RESULTS: The results show that the task time (SP-145s, standard deviation (SD) = 103 vs MP-61s SD = 16), maximum abdominal force (SP-8.4N, SD = 2.0 vs MP-left (L)-3.3N, SD = 0.8 and MP-right (R)-5.8N, SD = 2.1), tissue manipulation force (SP-10.4N, SD = 3.6 and MP-5.6N, SD = 1.3), maximum acceleration (MP-L-9m/s(2), SD = 5 vs SP-L-14m/s(2), SD = 7), and tilt angles of the left handle are significantly higher in SP. CONCLUSIONS AND DISCUSSION: This study shows that the new trainer can be used to find the most important differences in instrument and tissue handling, which is an important step toward the assessment of surgical skills needed for safe SP surgery depending on force and motion-based parameters.

Waterjet cutting of periprosthetic interface tissue in loosened hip prostheses: an in vitro feasibility study.

Waterjet cutting technology is considered a promising technology to be used for minimally invasive removal of interface tissue surrounding aseptically loose hip prostheses. The goal of this study was to investigate the feasibility of waterjet cutting of interface tissue membrane. Waterjets with 0.2 mm and 0.6 mm diameter, a stand-off distance of 5 mm, and a traverse speed of 0.5 mm/s were used to cut interface tissue samples in half. The water flow through the nozzle was controlled by means of a valve. By changing the flow, the resulting waterjet pressure was regulated. Tissue sample thickness and the required waterjet pressures were measured. Mean thickness of the samples tested within the 0.2 mm nozzle group was 2.3 mm (SD 0.7 mm) and within the 0.6 mm nozzle group 2.6 mm (SD 0.9 mm). The required waterjet pressure to cut samples was between 10 and 12 MPa for the 0.2 mm nozzle and between 5 and 10 MPa for the 0.6 mm nozzle. Cutting bone or bone cement requires about 3 times higher waterjet pressure (30-50 MPa, depending on used nozzle diameter) and therefore we consider waterjet cutting as a safe technique to be used for minimally invasive interface tissue removal.

The use of navigation forces for assessment of wrist arthroscopy skills level.

Purpose To provide an efficient learning process, feedback on performance is crucial. In skills laboratories, it is possible to measure the skills and progression of skills of the trainees objectively. This requires metrics that represent the learning curve of the trainee, which were investigated for wrist arthroscopy. The research questions were: What are the forces used by novices during wrist arthroscopy?What aspects of these navigation forces are discriminative for the wrist arthroscopy skills level?Methods A cadaver wrist was mounted in a custom-made distraction device mounted in front of a force platform (ForceTrap). Eleven novices were invited to perform two tasks on the wrist: Insertion of the scope through the 3-4 portal and the hook through the 6R portal, and visualization of the hook in the center of the imageNavigation through the wrist from radial to ulnar with probing and visualization of five predefined landmarksThe second task was repeated 10 times. The absolute force (F abs) and the direction of force were measured. The angle α is defined in the vertical plane, and the angle ß in the horizontal plane. Results The median F abs used by novices remained below the force threshold as defined from the expert data (7.3 N). However, the direction of the applied forces by novices in both planes was not consistent with expert data and showed a wider range. Also, there was no improvement after more trials. Conclusion Our study suggests by the absence of a learning curve for the novices and a significant difference between novices and experts that novices can benefit from feedback on the magnitude and direction of forces to improve their performance.

Waterjet drilling in porcine bone: the effect of the nozzle diameter and bone architecture on the hole dimensions.

Using waterjets instead of rigid drill bits for bone drilling can be beneficial due to the absence of thermal damage and a consequent sharp cut. Additionally, waterjet technology allows the development of flexible instruments that facilitate maneuvering through complex joint spaces. Controlling the drilling depth is of utmost importance to ensure clinical safety, but is challenging given the local variations in structural properties of the bone. The goal of this study was to deduce a descriptive mathematical equation able to predict the hole depth and diameter based on the local structural properties of the bone at given waterjet diameters. 210 holes were drilled in porcine femora and tali with waterjet diameters (Dnozzle) of 0.3, 0.4, 0.5 and 0.6mm at a pressure of 700bar and a 5s jet time. Hole depths (Lhole), diameters (Dhole) and bone architectural properties were determined using microCT scans. The most important bone architectural property is the bone volume fraction (BV/TV), resulting in the significant predictive equations: Lhole=34.3 (⁎) Dnozzle(2)-17.6 (⁎) BV/TV+10.7 (R(2)=0.90, p<0.001), and hole Dhole=3.1(⁎) Dnozzle-0.45(⁎)BV/TV+0.54 (R(2)=0.58, p=0.02), with Lhole, Dhole and Dnozzle in mm. Drilling to a specific depth in bone tissue with a known BV/TV is possible, thereby contributing to the safe application of waterjet technology in orthopedic surgery.

No effect of hole geometry in microfracture for talar osteochondral defects.

BACKGROUND: Débridement and bone marrow stimulation is an effective treatment option for patients with talar osteochondral defects. However, whether surgical factors affect the success of microfracture treatment of talar osteochondral defects is not well characterized. QUESTIONS/PURPOSES: We hypothesized (1) holes that reach deeper into the bone marrow-filled trabecular bone allow for more hyaline-like repair; and (2) a larger number of holes with a smaller diameter result in more solid integration of the repair tissue, less need for new bone formation, and higher fill of the defect. METHODS: Talar osteochondral defects that were 6 mm in diameter were drilled bilaterally in 16 goats (32 samples). In eight goats, one defect was treated by drilling six 0.45-mm diameter holes in the defect 2 mm deep; in the remaining eight goats, six 0.45-mm diameter holes were punctured to a depth of 4 mm. All contralateral defects were treated with three 1.1-mm diameter holes 3 mm deep, mimicking the clinical situation, as internal controls. After 24 weeks, histologic analyses were performed using Masson-Goldner/Safranin-O sections scored using a modified O'Driscoll histologic score (scale, 0-22) and analyzed for osteoid deposition. Before histology, repair tissue quality and defect fill were assessed by calculating the mean attenuation repair/healthy cartilage ratio on Equilibrium Partitioning of an Ionic Contrast agent (EPIC) micro-CT (µCT) scans. Differences were analyzed by paired comparison and Mann-Whitney U tests. RESULTS: Significant differences were not present between the 2-mm and 4-mm deep hole groups for the median O'Driscoll score (p = 0.31) and the median of the µCT attenuation repair/healthy cartilage ratios (p = 0.61), nor between the 0.45-mm diameter and the 1.1-mm diameter holes in defect fill (p = 0.33), osteoid (p = 0.89), or structural integrity (p = 0.80). CONCLUSIONS: The results indicate that the geometry of microfracture holes does not influence cartilage healing in the caprine talus. CLINICAL RELEVANCE: Bone marrow stimulation technique does not appear to be improved by changing the depth or diameter of the holes.

Trends in wrist arthroscopy.

Background Wrist arthroscopy plays a role in both the diagnosis and the treatment of wrist pathology. It has evolved in the last three decades. Questions The present status of wrist arthroscopy was investigated by answering the following questions: -What is its current position in the treatment wrist pathologies according to the literature? -What is its current position according to hand surgeons? Methods Analysis of the number of publications on wrist arthroscopy was performed and compared with the number of publications on other arthroscopy topics to assess the current position of wrist arthroscopy. The members of the EWAS (European Wrist Arthroscopy Society) and the members of eight national hand surgery societies were questioned on wrist arthroscopy in daily practice. Results From 1975 till now, 925 papers on wrist arthroscopy were found. The publications on wrist arthroscopy increased from an average of 8/year (1986) to 26/year (2012). More than half (56.9%) of the respondents of the EWAS perform fewer than 5 wrist arthroscopies per month, and only 7 (10.8%) indicate the performance of more than 10 wrist arthroscopies per month. Seventy-four percent of the orthopedic hand surgeons perform wrist arthroscopy (in 48.5% for therapeutic indications) against 36.8% of plastic surgery hand surgeons (in 23.1% for therapeutic indications). Conclusion Wrist arthroscopy has taken up a place in the armamentarium of the hand surgeon. The place of wrist arthroscopy in daily practice is related to the background of the hand surgeon.

Is technique performance a prognostic factor in bone marrow stimulation of the talus?

Although results of bone marrow stimulation in osteochondral defects of the talus (OCLT) have been satisfactory, the technique performance has not yet been subjected to review as a prognostic factor. The aim of this systematic review is to determine whether variation within technique influences outcome of bone marrow stimulation for OCLT. Electronic databases were searched for articles on OCLT treated with bone marrow stimulation techniques, providing a technique description. Six articles on microfracture were included (198 patients). Lesion size averaged 0.9 cm (2) to 4.5 cm (2), and follow-up varied from 2 to 6 years. Key elements were removal of unstable cartilage, hole depth variation between 2 and 4 mm until bleeding or fat droplets occurred, and a distance between the created holes of 3 to 4 mm. The success rate (excellent/good results by any clinical outcome score) was 81%. There is a vast similarity in the technique with similar outcomes as in previous general reviews; therefore variation in technique as currently described in the literature does not seem to influence the outcome of bone marrow stimulation for OCLT. Whether the instruments used or the hole depth and geometry influence clinical outcome remains to be determined. Microfracture is safe and effective for OCLTs smaller than 15 mm. However, in this review, only 81% of patients obtained satisfactory results. Larger clinical trials are needed with clearly defined patient groups, technique descriptions, and reproducible outcome measures to provide insight in the specific indications and the preferred technique of bone marrow stimulation.

Arthroscopic accessibility of the talus quantified by computed tomography simulation.

BACKGROUND: Anterior ankle arthroscopy is the preferred surgical approach for the treatment of osteochondral defects of the talus (OCDs). However, the ankle is a congruent joint with limited surgical access. PURPOSE: The dual purpose of this study was (1) to quantify the anterior arthroscopic reach (defined as the proportion of the talar dome articular surface located anterior to the anterior distal tibial rim) with the ankle in full plantar flexion and (2) to identify predictive factors of the arthroscopic reach. STUDY DESIGN: Descriptive laboratory study. METHODS: Computed tomography scans were obtained of 59 ankles (57 patients aged 33 ± 11 years) in full plantar flexion in a nonmetallic 3-dimensional footplate. The arthroscopic reach of both the medial and lateral talar domes was assessed on sagittal reconstructions using a custom-made software routine. Intraobserver and interobserver reliability were calculated by intraclass correlation coefficients (ICCs). Various predictive factors of the arthroscopic reach were analyzed by multivariate linear regression analysis. RESULTS: The arthroscopic reach was 48.2% ± 6.7% (range, 26.7%-60.7%) of the medial talar dome and 47.8% ± 6.5% (range, 31.2%-65.1%) of the lateral talar dome (P = .62). The intraobserver and interobserver reliability of both measurements were excellent (ICC, .99). The clinical plantarflexion angle was a statistically significant predictive factor of both the medial and lateral arthroscopic reaches (ie, increased plantar flexion corresponded to increased area of access), while joint laxity, gender, and age were not predictive. CONCLUSION: Almost half of the talar dome is accessible anterior to the anterior distal tibial rim. The plantarflexion angle is an independent predictive factor of the arthroscopic reach both medially and laterally. CLINICAL RELEVANCE: These results may facilitate preoperative planning of the surgical approach for OCDs.

Computed tomography of the ankle in full plantar flexion: a reliable method for preoperative planning of arthroscopic access to osteochondral defects of the talus.

PURPOSE: The purpose of this study was to determine whether preoperative computed tomography (CT) of the ankle joint in full plantar flexion is a reliable and accurate tool to determine the anterior arthroscopic accessibility of talar osteochondral defects (OCDs). METHODS: Twenty consecutive patients were prospectively studied. All patients had an OCD of the talar dome and had a preoperative CT scan of the affected ankle in maximum plantar flexion. Accessibility of the OCD was defined by the distance between the anterior border of the OCD and the anterior distal tibial rim. This distance was measured on sagittal CT reconstructions by 2 investigators. The reference standard was the distance between the same landmarks measured during anterior ankle arthroscopy by an orthopaedic surgeon blinded to the CT scans. Intraobserver and interobserver reliability of CT, as well as the correlation and agreement between CT and arthroscopy, were calculated. RESULTS: The measured distance between the anterior border of the OCD and the anterior distal tibial rim ranged from -3.1 to 9.1 mm on CT and from -3.0 to 8.5 mm on arthroscopy. The intraobserver and interobserver reliability of the measurements made on CT scans (intraclass correlation coefficients >0.99, P < .001), as well as the correlation between CT and arthroscopy, were excellent (r = 0.98, P < .001). CONCLUSIONS: Measurements on CT scans of the ankle in full plantar flexion are a reliable and accurate preoperative method to determine the in situ arthroscopic location of talar OCDs.

Does perception of usefulness of arthroscopic simulators differ with levels of experience?

BACKGROUND: Some commercial simulators are available for training basic arthroscopic skills. However, it is unclear if these simulators allow training for their intended purposes and whether the perception of usefulness relates to level of experience. QUESTIONS/PURPOSES: We addressed the following questions: (1) Do commercial simulators have construct (times to perform tasks) and face validity (realism), and (2) is the perception of usefulness (educational value and user-friendliness) related to level of experience? METHODS: We evaluated two commercially available virtual reality simulators (Simulators A and B) and recruited 11 and nine novices (no arthroscopies), four and four intermediates (one to 59 arthroscopies), and seven and nine experts (> 60 arthroscopies) to test the devices. To assess construct validity, we recorded the median time per experience group for each of five repetitions of one identical navigation task. To assess face validity, we used a questionnaire to judge up to three simulator characteristic tasks; the questionnaire asked about the realism, perception of educational value, and perception of user-friendliness. RESULTS: We observed partial construct validity for Simulators A and B and considered face validity satisfactory for both simulators for simulating the outer appearance and human joint, but barely satisfactory for the instruments. Simulators A and B had equal educational value according to the participants. User-friendliness was judged better for Simulator B although both were graded satisfactory. The perception of usefulness did not differ with level of experience. CONCLUSIONS: Our observations suggest training on either simulator is reasonable preparation for real-life arthroscopy, although there is room for improvement for both simulators.

Probing forces of menisci: what levels are safe for arthroscopic surgery.

PURPOSE: to facilitate effective learning, feedback on performance during arthroscopic training is essential. Less attention has been paid to feedback on monitoring safe handling of delicate tissues such as meniscus. The goal is to measure in vitro probing forces of menisci and compare them with a theoretical maximum probing force (TMPF). METHOD: menisci samples of ten cadavers were mounted on force platforms to measure probing forces up to 20 N in three directions. Nineteen subjects participated: six novices (experience <60 arthroscopies), ten intermediates (>60 arthroscopies), and three faculty (>250 a year). All had to perform three tasks on each meniscus sample with an arthroscopic probe: push three times on the superior meniscal surface, perform one continuous run on the superior meniscal surface, and push three times on the inferior meniscal surface. The absolute maximum probing force (AMPF) was determined for each condition. A multivariable linear regression analysis was performed to assess the influence of experience on the force magnitude (P < 0.05). AMPFs were compared to the TMPF (estimated to be 8.5 N). RESULTS: the AMPF of the push task was on average 2.8 N (standard deviation (SD) of 0.8 N), of the continuous run task 2.5 N (SD 0.9 N), and of the pull task 3.9 N (SD 2.0 N). Significant difference was present between experts and novices (P < 0.05). The AMPFs are in the same order of magnitude as the TMPF. CONCLUSION: the results indicate the necessity of using a safety level for tissue manipulation when training arthroscopy and a value for is magnitude.