Purpose: To determine the extent to which, a medically monitored rapid weight-loss program will improve pain, psychological status and functional abilities for morbidly obese women with knee osteoarthritis.

Method: 34 women (age 40 to 65) with morbid obesity and severe osteoarthritis of the knee that presented to an orthopedic surgeon for total knee arthroplasty were offered enrollment into a medically supervised weight loss program prior to consideration of a total knee replacement. Twenty-six subjects chose to participate in the weight loss program. They were enrolled in the Dr. Bernstein diet program, (a low-calorie, low-fat diet) at no cost to them. We collected the following questionnaires at enrollment and every six weeks while they remained in the weight loss program: WOMAC, SF36, Self-Efficacy, Health Locus of control, Dieting beliefs scale, Body image state scale, and the Beck depression inventory as well as Functional tests, namely the Timed up and go (TUG) and 6 minute walk test (6MWT). Our hypothesis was that weight loss would be associated with dramatic improvements in pain, self-report quality of life measures, psychological variables, and measured functional abilities for those patients who were successful in the weight loss program.

Results: At enrollment the mean age was 58.5 years and mean BMI was 47.8.

Subjects were significantly disabled with WOMAC (total) scores of 48+/ − 7 and impaired function in both the 6 minute walk test 229+/ − 146 metres and the timed up-go test 5.9+/ − 11.

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Subjects lost an average of 32 kilograms (range 14 to 50 kg) after six months of dieting.

Weight loss was associated with dramatic improvements in pain(p < .01), self-report quality of life measures (p < .01) and measured functional abilities (p < .01).

Successful weight loss was associated with patients’ self-report of no longer requiring TKA for their knee OA.

Initially 100% of subjects felt that they required surgery. This decreased to 9.5% after six months of weight loss.

Conclusion: A low-fat, low-calorie medically monitored weight loss program (Dr. Bernstein Diet Clinics Inc.) is effective for achieving significant weight loss in women with severe knee osteoarthritis and morbid obesity. Weight loss leads to significant improvements in pain and functional abilities and alleviates or delays the need for knee replacement surgery in the majority of middle-aged, morbidly obese women.

Purpose: Intraoperative frozen section analysis in which the number of cells per high powered field (CPHF) are used to predict the presence or absence of infection has been found to be a very useful test in the setting of revision total joint arthroplasty. The purpose of this retrospective review was to determine the usefulness of this same test at the time of implantation of a total hip arthroplasty (THA) following the failure of hip fracture fixation.

Method: A retrospective review from 1999 – 2007 of twenty-two consecutive patients who had THA performed as a result of failed hip fracture fixation. The mean age of patients was seventy-two years. The number of CPHF was correlated with the results of intraoperative cultures, and other pre-operative and post-operative parameters. The mean duration of follow-up was 14 months.

Results: Two patients had a culture-proven infection (Staphylococcus aureus in one patient, and staphylococcus epidermidis and propionibacterium acnes in the other.) Both of these patients had a positive test for infection based on the frozen section having greater than ten CPHF by the pathologist. (100% agreement) Four out of the six specimens that were graded as 10 CPHF by the pathologist had negative intra-operative cultures (33% agreement). With the CPHF limit set at 10 CPHF, the sensitivity of frozen section analysis in this clinical setting was 100%, while the specificity was 19%. The positive predictive value was calculated to be 33%, and the negative predictive value was 100%. With the cutoff of 5 CPHF or greater, the sensitivity of 100% and a specificity of 52% as well as a positive predictive value of 17% and a negative predictive value of 100%.

Conclusion: Although the results are preliminary, and further study is warranted, it seems that CPHF is a useful test to rule out the presence of infection when revising failed fracture fixation to Total Hip Replacement..

Introduction: Many mini compression screws are now available for fixation in procedures such as metatarsal osteotomies or arthrodeses of the foot.

The aim of the current study is to compare the compression forces achieved by mini compression screws on cortical and cancellous bone models.

Material and Methods: The screws that were tested are listed in the table below. The compression forces were tested by inserting a pressures load measurement cell between longitudinally-split sheep tibia as a cortical bone model and longitudinally split retrieved femoral heads as a cancellous bone model.

Results: The Headed AO 3.5 mm cortical screw gave the best compression force and the Bold was the weakest, both in cortical and cancellous bone. The relative compression forces of the other tested screws were different between cortical and cancellous bone. Compression with the headless screws was lost as soon as the screw penetrated through the cortex in the cortrical bone model.

Conclusions: The indications for using headless self-tapping screws should be reserved for fixation of cancellous bone or of metatarsal or Akin osteotomies where compression is not required for union. When compression is important, such as in MPJ, tarso-metatarsal or talonavicular arthrodeses, Headed AO 3.5 mm or 2.7 mm cortical or 4 mm cancellous screws, which give better compression, should be used.

To quantify the intraoperative cerebral microemboli load during primary total knee arthroplasty (TKA) using transcranial Doppler ultrasound and to investigate whether a patent foramen ovale influences cerebral embolic load in general.

Patients undergoing primary TKA, with no history of stroke, TIA, ongoing CNS disease or alcoholism were included. All operations were carried out under a standardised general anaesthetic and performed by two consultant orthopaedic surgeons. Microemboli l oad was recorded, using transcranial Doppler ultrasound (TCD), onto VHS tape for subsequent playback and analysis. Patent foramen ovale detection was performed using bolus intravenous injection of agitated saline followed by valsalva manoeuvre technique and TCD. Timing of specific surgical steps was recorded for each operation and emboli load calculated for that period.

Results: 50 TKA patients were studied (31 females, 19 males); 28 right and 22 left TKAs were performed. Cerebral microembolisation occurred in 19 patients (42%). Mean microembolic load was 3.56 per patient (range 0–21). PFO was detected in 9 patients (18%). Two thirds of PFO positive patients displayed cerebral microemboli. However, 36.6% (n=15) of PFO negative patients also displayed microemboli intraoperatively. Deflation of the tourniquet was followed by a larger microembolic load than the other phases of the operation.

Conclusion: Intraoperative cerebral microembolisation occurs in a significant proportion of patients during total knee arthroplasty. The presence of a patent foramen ovale does not appear to influence the incidence microemboli intraoperatively. Specific surgical activities are associated with generating greater embolic loads. These questions will be comprehensively assessed in the larger study currently underway.

We evaluated the accuracy of a Magnetic Resonance Imaging (MRI)-based method to measure three-dimensional patellar tracking during loaded knee flexion. This method determines the relative positions of the knee bones by shape matching high-resolution three-dimensional geometric models of these bones to fast low-resolution scans taken during loaded flexion.

The accuracy of the method’s assessment of patellar position and orientation was determined by comparing test measurements in four cadaver specimens to measurements made in the same specimens using Roentgen Stereophotogrammetric Analysis (RSA). This MRI-based method is more accurate than current two-dimensional imaging methods.

The purpose of this study was to determine the accuracy of a MRI-based technique for measuring patellar tracking in loaded flexion.

This novel, noninvasive, MRI-based method measures three-dimensional patellar tracking during loaded knee flexion with sufficient accuracy to detect clinically significant changes.

Although abnormal patellar tracking is widely believed to be associated with pain and cartilage degeneration at the patella, these relationships have not been clearly established because most current methods assess only the two-dimensional alignment of the patella at one position. Measurements possible with this method should be sufficiently accurate to yield new insights into these relationships.

Four cadaver knee specimens were flexed through seventy-five degrees of flexion in an MRI-compatible knee loading rig. A high-resolution image was acquired with each knee in extension and then a series of low-resolution scans (in two slice directions: axial and sagittal) were acquired through a flexion cycle. Segmenting bone outlines from high-resolution scans generated models of the femur, tibia and patella. These models were shape matched to the segmented bone outlines in the low resolution scans. Patellar attitude and position were determined and compared to measurements made using RSA.

The mean measurement error in every kinematic parameter was lower for “fast” sagittal plane slices than for “fast” axial plane slices. In general, the mean measurement error was increased by decreasing the number of low-resolution slices.

This method is more accurate than many two-dimensional methods, exposes participants to no ionizing radiation, and can be used through a large range of loaded knee flexion.

Funding: Supported by an operating grant from the Canadian Institutes for Health Research and a Strategic Grant from the Natural Sciences and Engineering Research Council. NJM is supported by the Arthritis Society/CIHR Partnership Fund.

Please contact author for figures and/or tables.

Introduction: Many mini compression screws are now available for fixation in procedures such as metatarsal osteotomies or arthrodeses of the foot.

The aim of the current study is to compare the compression forces achieved by the relatively new commercial mini compression screws on cortical and cancellous bone models.

Material and Methods: The screws that were tested are listed in the table below. All screws apart from the AO screws are headless and cannulated; and all screws apart from the AO cortical screw are self-tapping. The compression forces were tested by inserting a pressures load measurement cell between longitudinally-split sheep tibia as a cortical bone model and longitudinally split retrieved femoral heads as a cancellous bone model. The screws were inserted across the 2 halves with gradual compression after allowing the reading of the cell to settle.

Results: The Headed AO 3.5 mm cortical screw gave the best compression force, both in cortical and cancellous bone and the Bold was the weakest both in cortical and cancellous bone. The relative compression forces of the other tested screws were different between cortical and cancellous bone. Compression with the headless screws was lost as soon as the screw penetrated through the cortex in the cortrical bone model.

Conclusions: The indications for using headless self-tapping screws should be reserved for fixation of cancellous bone or of metatarsal or Akin osteotomies where compression is not required for union. When compression is important, such as in MPJ, tarso-metatarsal or talo-navicular arthrodeses, Headed AO 3.5 mm or 2.7 mm cortical or 4 mm cancellous screws, which give better compression, should be used.

Introduction and Aims: High tibial osteotomy (HTO) is a corrective surgical procedure used to treat medial compartment osteoarthritis (OA). In HTO a bone wedge is resected from the upper tibia to realign the lower limb. In this study, we investigated the effect of HTO on patellofemoral joint motion using a validated new technique.

Method: We assessed patellar tracking in four subjects before and after high tibial osteotomy surgery. A high-resolution MR image was acquired of each subject’s knee. Each subject then loaded his/her knee in a custom test rig in the MR scanner, while fast, low-resolution MRI scans were acquired. This was repeated at five flexion angles. Bone outlines were identified (image segmentation) and processed (meshed) to yield bone models. Knee kinematics were determined by matching (registering) the high-resolution bone models to the low-resolution bony outlines. We compared the pre- and post-operative tracking patterns using a two-way repeated measures ANOVA.

Results: The resultant patellar tracking patterns were expressed as a function of knee flexion. Mean values for each quantity were calculated over the flexion range. High tibial osteotomy decreased patellar flexion by a mean of 5.06 degrees (p < 0.003), decreased internal patellar spin by a mean of 1.25 degrees (p < 0.001) and increased medial patellar tilt by a mean of 1.59 degrees (p < 0.001). High tibial osteotomy increased proximal patellar translation by a mean of 4.19mm (p < 0.008), but, for the number of specimens tested, we found no significant change in anterior or medial translation.

Conclusion: Our finding that HTO translated the patella proximally is consistent with findings of elevated patellae in the literature. The significant changes in patellar movement caused by high tibial osteotomy surgery suggest that the post-operative anterior knee pain associated with these procedures is due to mechanical changes at the patellofemoral joint.