An End-to-End Solution for Automatic Contouring of Tumor Region in Intraoperative Images of Breast Lumpectomy.

Breast-conserving surgery, also known as lumpectomy, is an early stage breast cancer treatment that aims to spare as much healthy breast tissue as possible. A risk associated with lumpectomy is the presence of cancer positive margins post operation. Surgical navigation has been shown to reduce cancer positive margins but requires manual segmentation of the tumor intraoperatively. In this paper, we propose an end-to-end solution for automatic contouring of breast tumor from intraoperative ultrasound images using two convolutional neural network architectures, the U-Net and residual U-Net. The networks are trained on annotated intraoperative breast ultrasound images and evaluated on the quality of predicted segmentations. This work brings us one step closer to providing surgeons with an automated surgical navigation system that helps reduce cancer-positive margins during lumpectomy.

The influence of osteophyte depiction in CT for patient-specific guided hip resurfacing procedures.

PURPOSE: An accurate fit of a patient-specific instrument guide during an intervention is one of the critical factors affecting accuracy of the surgical procedure. In this study, we investigated how well osteophytes, which are abnormal bone growths that form along joints, are depicted in clinical preoperative CT scans and estimated the influence of such depiction errors on the intraoperative accuracy of the guide. METHODS: In 34 hip resurfacing patients, 227 osteophyte surface points on the anterior aspect of the femoral neck were collected intraoperatively, using an optoelectronic navigation system. These points were registered to a preoperative CT scan of the patient, and distances between collected points and segmented virtual bone surface, as well as Hounsfield units for these points, were determined. We simulated the registration error of a patient-specific guide, using a modified registration algorithm, to test placement on the anterior aspect of the femoral neck without removing any osteophytes. This error was then applied to the surgical plan of the femoral central-pin position and orientation for evaluation. RESULTS: The average distance between the collected points and the segmented surface was 2.6 mm. We estimated the average error for the entrance point of the central-pin to be 0.7 mm in the distal direction and 3.2 mm in the anterior direction. The average orientation error was 2.8° in anteversion. CONCLUSIONS: The depiction of osteophytes in clinical preoperative CT scans for proximal femurs can be unreliable and can possibly result in significant intraoperative instrument alignment errors during image-guided surgeries.

Design and development of a mobile image overlay system for needle interventions.

Previously, a static and adjustable image overlay systems were proposed for aiding needle interventions. The system was either fixed to a scanner or mounted over a large articulated counterbalanced arm. Certain drawbacks associated with these systems limited the clinical translation. In order to minimize these limitations, we present the mobile image overlay system with the objective of reduced system weight, smaller dimension, and increased tracking accuracy. The design study includes optimal workspace definition, selection of display device, mirror, and laser source. The laser plane alignment, phantom design, image overlay plane calibration, and system accuracy validation methods are discussed. The virtual image is generated by a tablet device and projected into the patient by using a beamsplitter mirror. The viewbox weight (1.0 kg) was reduced by 8.2 times and image overlay plane tracking precision (0.21 mm, STD = 0.05) was improved by 5 times compared to previous system. The automatic self-calibration of the image overlay plane was achieved in two simple steps and can be done away from patient table. The fiducial registration error of the physical phantom to scanned image volume registration was 1.35 mm (STD = 0.11). The reduced system weight and increased accuracy of optical tracking should enable the system to be hand held by the physician and explore the image volume over the patient for needle interventions.

Computer-assisted guidewire insertion for hip fracture fixation.

OBJECTIVE: : This study was designed to test in a laboratory setting a novel computer-assisted fluoroscopic technique and a conventional fluoroscopic technique for open reduction and internal fixation (ORIF) of hip fractures. Our hypothesis is that a novel computer-assisted fluoroscopic technique will achieve acceptable guidewire placement in one pass, with decreased fluoroscopic time and with accuracy and precision better than conventional technique. DESIGN: Prospective, randomized trials. SETTING: Laboratory. PARTICIPANTS: Thirty, Sawbone, femur phantoms. INTERVENTION: Dynamic hip screw guidewires were inserted into 15 femur phantoms under fluoroscopic guidance by using computer-assisted fluoroscopic ORIF technique, and 15 femurs were inserted by using a conventional fluoroscopic-assisted ORIF technique. MAIN OUTCOME MEASUREMENTS: Ideal guidewire placement was defined as the center of the femoral head, 5 mm from the apical bone edge on anteroposterior and lateral views. Accuracy was measured as distance to ideal placement, and the number of passes and fluoroscopic time were noted for each trial. RESULTS: The computer-assisted technique achieved an average guidewire placement that was as accurate as the conventional technique in fewer passes, 1.1 +/- 0.2 (mean +/- standard deviation) compared with 2.4 +/- 1.1 (P < 0.0001), respectively, and with fewer fluoroscopic images, 2 +/- 0 compared with 13.5 +/- 3 (P < 0.0002), respectively. Guidewire placement in both groups was within the tip-apex distance defined by Baumgaertner et al. CONCLUSIONS: The computer-assisted technique was significantly more accurate and precise than conventional technique. It also required fewer drill tracks through the femur and exposed the patient and the surgical team to significantly less ionizing radiation.

Computer-enhanced insertion of the Oxford unicompartmental arthroplasty: a fluoroguide technique.

OBJECTIVE: To develop an accurate and reproducible technique for inserting Oxford Unicompartmental arthroplasties. MATERIALS AND METHODS: A protocol was developed to accurately position the femoral component of the Oxford Unicompartmental arthroplasty using computer-enhanced techniques. A dynamic reference body (DRB) is inserted into the femur, then antero-posterior (AP) and lateral fluoroscopic images are taken of the proximal femur. These images are digitized and entered into 3D space using a registered fluoroscopy machine. The femoral guide from the Oxford system is then placed on the medial femoral condyle in the standard manner. Holes are drilled directly towards the center of the femoral head using a registered drill. The femoral cuts are then made using the standard instruments from the Oxford set. RESULTS: This procedure was carried out on 15 sawbone femurs. Component position was determined by measuring radiographs after a trial component had been inserted. The average lateral error was 1.2 degrees (standard deviation [SD] = 1.207), compared to 4.1 degrees (SD = 2.875) with the standard technique. The average AP error was 2.5 degrees (SD = 1.767), compared to 5.1 degrees (SD = 2.219) with the standard technique. The differences in accuracy in both planes were statistically significant (p = 0.002 for AP, 0.001 for lateral). CONCLUSION: Using a Fluoroguide-assisted technique, we were able to insert the femoral component more precisely than when using the standard technique as described by the manufacturer.

A computational model of postoperative knee kinematics.

A mathematical model for studying the passive kinematics of total knee prostheses can be useful in computer-aided planning and guidance of total joint replacement. If the insertion location and neutral length of knee ligaments is known, the passive kinematics of the knee can be calculated by minimizing the strain energy stored in the ligaments at any angular configuration of the knee. Insertions may be found intraoperatively, or may come from preoperative 3D medical images. The model considered here takes into consideration the geometry of the prosthesis and patient-specific information. This model can be used to study the kinematics of the knee joint of a patient after total joint replacement. The model may be useful in preoperative planning, computer-aided intraoperative guidance, and the design of new prosthetic joints.

Fuji film and ultrasound measurement of total knee arthroplasty contact areas.

This article describes tibiofemoral contact area measurement results from tests on 1 commercial total knee arthroplasty (TKA) using 2 experimental methods-fuji film and diagnostic ultrasound. The study presents a novel diagnostic ultrasound technique developed specifically for measuring TKA contact areas. Because most experimental investigations have been concerned with interimplant comparison, this article is one of few parametric TKA studies in the literature. Fuji film and ultrasound provide lower and upper bound contact area measurements based on their physical operating principles; this implies that no single measurement method can be relied on exclusively to glean contact area data. Designers should be cautious in using contact area and contact stress as the exclusive predictors of TKA failure.

The effects of a pneumatic tourniquet on blood loss in total knee arthroplasty.

OBJECTIVE: In lower-extremity surgery there are significant risks associated with the use of tourniquets. This prospective study was done to assess to what extent these risks may be offset by the potential advantages of tourniquets, namely reductions in blood loss, length of hospital stay and complication rates. DESIGN: A prospective case study. SETTING: A major urban hospital. PATIENTS: Sixty-three consecutive patients scheduled for primary cemented total knee arthroplasty (TKA) were blindly randomized into tourniqet (n = 33) and non-tourniquet (n = 30) groups. INTERVENTION: TKA during which a pneumatic tourniquet was applied or not applied to control blood loss. MAIN OUTCOME MEASURES: Perioperative blood loss, operating time, complication rates, hospital stay and transfusion needs. RESULTS: Differences in the total measured blood loss, intraoperative blood loss and the Hemovac drainage blood loss between the 2 groups were not significantly different (p > 0.25). The calculated total blood loss was actually lower in the non-tourniquet group (p = 0.02). Between the groups there were no statistical differences in surgical time, length of hospital stay, transfusion requirements or rate of complications (although there was a trend to more complications in the tourniquet group (p = 0.06)). CONCLUSION: The effectiveness of a pneumatic tourniquet to control blood loss in TKA is questionable.

A surgical planning and guidance system for high tibial osteotomy.

OBJECTIVE: To develop a three-dimensional pre-surgical planner and an intraoperative guidance system for high tibial osteotomy. The parameters that describe the placement and orientation of the osteotomy resection planes were to be transmitted to an accompanying guidance system that allowed the surgeon to reproducibly perform the planned procedure. MATERIALS AND METHODS: The planning system and guidance system were coded using OpenGL on UNIX workstations. In vitro tests were performed to compare the reproducibility of the computer-enhanced technique to that of the traditional technique, and an in vivo pilot study was initiated. RESULTS: In vitro, the computer-enhanced technique produced a significant reduction, by one half, in both the maximum error of correction and the standard deviation of the correction error. Preliminary in vivo results on six patients suggest that similar error diminution will occur during regular clinical application of the technique. CONCLUSIONS: Both studies showed that the computer system is simple to use. The work suggests that three-dimensional planning and performance of high tibial osteotomy is essential for accurate correction of the alignment of the lower limb.

Optimizing femorotibial alignment in high tibial osteotomy.

OBJECTIVE: To study factors that affect femorotibial (F-T) alignment after valgus closing wedge tibial osteotomy. STUDY DESIGN: A review of standardized standing radiographs. Femorotibial alignment was measured 1 year postoperatively for over- and under-correction. Changes in F-T alignment and in tibial plateau angle were measured. SETTING: An urban hospital and orthopedic clinic. PATIENTS: Eighty-two patients with osteoarthritis and varus femorotibial alignment underwent valgus closing wedge tibial osteotomy. Patients having a diagnosis of inflammatory arthritis or a prior osteotomy about the knee were excluded. RESULTS: A 1 degree wedge removed from the tibia resulted in an average correction F-T alignment of 1.2 degrees. A knee that had increased valgus orientation of the distal femur had a greater degree of correction, averaging 1.46 degrees in F-T alignment per degree of tibial wedge. This resulted in excessive postoperative valgus alignment for some patients who had increased valgus tilt of the distal femur. Optimal F-T alignment of 6 degrees to 14 degrees valgus occurred when the postoperative tibial inclination was 4 degrees to 8 degrees of valgus. CONCLUSIONS: There was a trend for knees with increased valgus orientation of the distal femur to have greater correction in F-T alignment after tibial osteotomy, likely because of a greater opening up of the medial joint space during stance. Surgeons need to account for this in their preoperative planning.

Fat embolism syndrome in a patient demonstrating only neurologic symptoms.

Fat embolism syndrome (FES) is a recognized complication of both long bone fractures and intramedullary orthopedic procedures. The usual presenting features are respiratory failure, neurologic dysfunction and petechiae. In this report, a 25-year-old woman with FES presented with serious neurologic symptoms and signs in the absence of respiratory dysfunction. The diagnosis is essentially a clinical one, but nuclear magnetic resonance imaging of the brain revealed distinctive lesions that may help future diagnosis of FES.

Bone hardness testing in the trabecular bone of the human patella.

Bone hardness of 10 human patellas in 15 regions and at three depths was measured through in situ indentation tests. Indentation tests were performed perpendicular to the three articular surfaces (lateral and medial facets, and central ridge area) and, thus, parallel to the trabeculae. Multiple regression analysis demonstrated a significant reduction of bone hardness with depth. In addition, the lateral facet had a higher bone hardness than the medial facet, and the proximal and central regions demonstrated higher bone hardness than the distal region. Overall, the proximolateral region of the patella exhibited the highest hardness compared with other regions. As bone hardness is indicative of load bearing, these results may have important consequences for patellar resurfacing and patellar component design.

Juxtacortical dedifferentiated chondrosarcoma from a primary periosteal chondrosarcoma.

In this report, we describe dedifferentiation in a primary periosteal chondrosarcoma in the proximal tibia of a 73-year-old man. The diagnosis of primary periosteal chondrosarcoma was made by the characteristic radiographic, gross, and microscopic features of the tumor. The presence of dedifferentiation, however, in the form of malignant fibrous histiocytoma, was an unexpected histologic finding. Although rare, dedifferentiation is a well-recognized occurrence in secondary chondrosarcomas arising from precursor osteochondromas. This event has not been previously documented in the setting of primary periosteal chondrosarcoma.

Femoral articular shape and geometry. A three-dimensional computerized analysis of the knee.

An average, three-dimensional anatomic shape and geometry of the distal femur were generated from x-ray computed tomography data of five fresh asymptomatic cadaver knees using AutoCAD (AutoDesk, Sausalito, CA), a computer-aided design and drafting software. Each femur model was graphically repositioned to a standardized orientation using a series of alignment templates and scaled to a nominal size of 85 mm in mediolateral and 73 mm in anteroposterior dimensions. An average generic shape of the distal femur was synthesized by combining these pseudosolid models and reslicing the composite structure at different elevations using clipping and smoothing techniques in interactive computer graphics. The resulting distal femoral geometry was imported into a computer-aided manufacturing system, and anatomic prototypes of the distal femur were produced. Quantitative geometric analyses of the generic femur in the coronal and transverse planes revealed definite condylar camber (3 degrees-6 degrees) and toe-in (8 degrees-10 degrees) with an oblique patellofemoral groove (15 degrees) with respect to the mechanical axis of the femur. In the sagittal plane, each condyle could be approximated by three concatenated circular arcs (anterior, distal, and posterior) with slope continuity and a single arc for the patellofemoral groove. The results of this study may have important implications in future femoral prosthesis design and clinical applications.

A quantitative technique for reporting surface degradation patterns of UHMWPE components of retrieved total knee replacements.

A quantitative method of reporting surface degradation of the ultra-high molecular weight polyethylene (UHMWPE) tibial component from retrieved total knee replacements (TKR) was developed. Specific features include a qualitative assessment expressing the patterns in which the damage was detected as well as a quantitative summary of the observed degradation mechanisms. In addition, a method of measuring lower limb alignment changes with time is described and related to the observed damage patterns. Two case studies are presented. One case illustrated that changes in alignment resulted from factors other than wear. The damage observed on the tibial plateau appeared to occur subsequent to the changes in alignment. The second case illustrated that the wear of the UHMWPE tibial insert lead to the changes in the overall lower limb alignment. The methods described provide additional information regarding TKR failure mechanisms compared to reporting methods currently available. In particular, the collection of temporal alignment data at clinical follow-up visits enhanced the assessment of the retrieved TKR.

Valgus high tibial osteotomy. A long-term follow-up study.

One hundred twenty-eight knees in 107 patients with osteoarthrosis treated by valgus high tibial osteotomy were clinically reviewed. Patients were reviewed from three to 15 years postoperatively (mean, 7.5 years). The revision rate in the osteoarthrotic population was 10.9%. Patients who were older than 60 years of age at the time of surgery had results comparable to those patients who were younger than 60 years of age at the time of surgery. Women and men appeared to have a similar prognosis; 79.6% good and excellent results up to nine years; at ten to 15 years, 70% good and excellent.

High tibial osteotomy. A prospective clinical and roentgenographic review.

In a prospective clinical and roentgenographic analysis of 79 knees treated by a valgus closing wedge high tibial osteotomy, the average follow-up period was 5.8 years (three to nine years); 80% of the patients had good or excellent results. Correction to a femorotibial angle between 6 degrees and 14 degrees of femorotibial valgus was associated with an optimal clinical result. Undercorrection to less than 5 degrees of femorotibial valgus was associated with a high (62.5%) failure rate. Patients whose distal femur had a femoral shaft-transcondylar (FS-TC) angle of less than 9 degrees have an increased incidence of undercorrection. A poor prognosis was noted in knees whose patellofemoral joint preoperatively had moderate or severe roentgenographic evidence of osteoarthritis (OA) when compared to the group whose patellofemoral compartment had no or mild roentgenographic evidence of OA. Accurate femorotibial realignment was essential for success. The slope of the distal femoral articular surface, the FS-TC angle, affects the degree of correction and should be considered in preoperative planning.

High tibial osteotomy compared with high tibial and Maquet procedures in medial and patellofemoral compartment osteoarthritis.

The effect of adding the Maquet tibial tubercle elevating procedure to a valgus high tibial osteotomy (HTO) in combined medial and patellofemoral disease had not been established. This prospective study evaluates clinically and roentgenographically the use of this osteotomy combination versus HTO alone in dual-compartment arthritis. Forty-four patients (46 knees) with dual-compartment disease from 1979 to 1984 were evaluated. Twenty-two patients were treated with 23 HTOs by a senior surgeon, and 22 were treated with 23 combined procedures by another surgeon. The two groups were matched according to age, sex, and preoperative clinical and roentgenographic disability. The minimum follow-up period was two years. All had more than 5 degrees valgus alignment at the follow-up evaluation, with an average of 11.2 degrees in the HTO group and 10.2 degrees in the combined osteotomy group. A modified Hospital for Special Surgery assessment (maximum, 100 points) was used with an optimum pain score of 30 points. All were followed roentgenographically with grading of the three knee compartments. In both groups, the total and pain scores improved significantly postoperatively. There was no statistical difference between the two groups in terms of mean postoperative femorotibial shaft alignment or clinical and roentgenologic outcome. Although HTO was a good procedure for pain relief for dual-compartment disease, the addition of Maquet procedure did not improve the results.

Revision total hip arthroplasty with osseous allograft reconstruction. A clinical and roentgenographic analysis.

One hundred twelve irradiation-sterilized, -70 degrees frozen allografts have been used in 72 patients who were available for follow-up study in a prospective analysis of allograft revision total hip arthroplasty. Clinical objectives were achieved in 85% of patients with a follow-up period ranging from six to 72 months. Based on clinical and roentgenographic analysis, specific recommendations are made to further improve the success rate of revision total hip arthroplasty associated with protrusio, shelf, acetabular, calcar, and large fragment femoral allografts.