Long-Term Follow-Up of Nonoperatively and Operatively Treated Acute Primary Patellar Dislocation in Skeletally Immature Patients

Purpose. The present study reports a long-term follow-up of acute primary patellar dislocation in patients with open physes. The purpose of the study was to evaluate knee function and recurrence rates after surgical and nonsurgical treatment of patellar dislocation. Methods. A total of 51 patients, including 29 girls and 22 boys, who were 9–14 years of age at the time of injury, were retrospectively evaluated. The minimum follow-up time was 5 years. Thigh muscle torque, range of motion, the squat test, the knee injury and osteoarthritis outcome score (KOOS), the Kujala score, and the recurrence rate were registered. Radiological predisposing factors at the time of injury were determined. Results. Quality of life and sports/recreation were the most affected subscales, according to KOOS, and a reduced Kujala score was also observed in all treatment groups. The surgically treated patients had a significantly lower recurrence rate. Those patients also exhibited reduced muscle performance, with a hamstring to quadriceps ratio (H/Q) of 1.03. The recurrence rate was not correlated with knee function. Conclusions. Patellar dislocation in children influences subjective knee function in the long term. Surgery appears to reduce the recurrence rate, but subjective knee function was not restored

A New Automated Way to Measure Polyethylene Wear in THA Using a High Resolution CT Scanner: Method and Analysis

As the most advantageous total hip arthroplasty (THA) operation is the first, timely replacement of only the liner is socially and economically important because the utilization of THA is increasing as younger and more active patients are receiving implants and they are living longer. Automatic algorithms were developed to infer liner wear by estimating the separation between the acetabular cup and femoral component head given a computed tomography (CT) volume. Two series of CT volumes of a hip phantom were acquired with the femoral component head placed at 14 different positions relative to the acetabular cup. The mean and standard deviation (SD) of the diameter of the acetabular cup and femoral component head, in addition to the range of error in the expected wear values and the repeatability of all the measurements, were calculated. The algorithms resulted in a mean (±SD) for the diameter of the acetabular cup of 54.21 (±0.011) mm and for the femoral component head of 22.09 (±0.02) mm. The wear error was ±0.1 mm and the repeatability was 0.077 mm. This approach is applicable clinically as it utilizes readily available computed tomography imaging systems and requires only five minutes of human interaction

Risk Factors for Periacetabular Osteolysis and Wear in Asymptomatic Patients with Uncemented Total Hip Arthroplasties

Osteolysis is a silent disease leading to aseptic loosening. This has not been studied in a cohort of asymptomatic patients. The aim of this study was to detect factors that might be associated with the development of periacetabular osteolysis and wear around an uncemented cup. We assessed 206 patients with an uncemented cup, measuring wear and periacetabular osteolysis using computed tomography with a median follow-up of 10 years after surgery (range 7-14 years). EQ5D, pain from the hip, and satisfaction were assessed. The association between periacetabular osteolysis and wear, age, gender, activity, BMI, cup type, cup age, positioning of the cup, and surface coating was investigated with a proportional odds model. Wear and male gender were associated with an increased risk for periacetabular osteolysis. There was no association with periacetabular osteolysis for time from operation, patient age, UCLA Activity Score, liner thickness at time of operation, BMI, cup positioning, and type of implant. A thin liner at time of operation is correlated to increased wear. Linear wear rate was 0.18 mm/year and 46 of 206 patients had large periacetabular osteolysis. Asymptomatic patients with these implants should be followed up on a regular basis with a sensitive method such as CT in order to detect complications early

Risk Factors for Periacetabular Osteolysis and Wear in Asymptomatic Patients with Uncemented Total Hip Arthroplasties

Osteolysis is a silent disease leading to aseptic loosening. This has not been studied in a cohort of asymptomatic patients. The aim of this study was to detect factors that might be associated with the development of periacetabular osteolysis and wear around an uncemented cup. We assessed 206 patients with an uncemented cup, measuring wear and periacetabular osteolysis using computed tomography with a median follow-up of 10 years after surgery (range 7–14 years). EQ5D, pain from the hip, and satisfaction were assessed. The association between periacetabular osteolysis and wear, age, gender, activity, BMI, cup type, cup age, positioning of the cup, and surface coating was investigated with a proportional odds model. Wear and male gender were associated with an increased risk for periacetabular osteolysis. There was no association with periacetabular osteolysis for time from operation, patient age, UCLA Activity Score, liner thickness at time of operation, BMI, cup positioning, and type of implant. A thin liner at time of operation is correlated to increased wear. Linear wear rate was 0.18 mm/year and 46 of 206 patients had large periacetabular osteolysis. Asymptomatic patients with these implants should be followed up on a regular basis with a sensitive method such as CT in order to detect complications early

A CT method for following patients with both prosthetic replacement and implanted tantalum beads: preliminary analysis with a pelvic model and in seven patients.

BACKGROUND: Radiostereometric analysis (RSA) is often used for evaluating implanted devices over time. Following patients who have had tantalum beads implanted as markers in conjunction with joint replacements is important for longitudinal evaluation of these patients and for those with similar implants. As doing traditional RSA imaging is exacting and limited to specialized centers, it is important to consider alternative techniques for this ongoing evaluation. This paper studies the use of computed tomography (CT) to evaluate over time tantalum beads which have been implanted as markers. METHODS: The project uses both a hip model implanted with tantalum beads, acquired in several orientations, at two different CT energy levels, and a cohort of seven patients. The model was evaluated twice by the same observer with a 1-week interval. All CT volumes were analyzed using a semi-automated 3D volume fusion (spatial registration) tool which provides landmark-based fusion of two volumes, registering a target volume with a reference volume using a rigid body 3D algorithm. The mean registration errors as well as the accuracy and repeatability of the method were evaluated. RESULTS: The mean registration error, maximum value of repeatability, and accuracy for the relative movement in the model were 0.16 mm, 0.02° and 0.1 mm, and 0.36° and 0.13 mm for 120 kVp and 0.21 mm, 0.04° and 0.01 mm, and 0.39° and 0.12 mm for 100 kVp. For the patients, the mean registration errors per patient ranged from 0.08 to 0.35 mm. These results are comparable to those in typical clinical RSA trials. This technique successfully evaluated two patients who would have been lost from the cohort if only RSA were used. CONCLUSIONS: The proposed technique can be used to evaluate patients with tantalum beads over time without the need for stereoradiographs. Further, the effective dose associated with CT is decreasing

Pre- and postcontrast T1 and T2 mapping of patellar cartilage in young adults with recurrent patellar dislocation

PurposeTo examine the cartilage quality in young adults with recurrent patellar dislocation in childhood using different magnetic resonance imaging parameters. MethodsSixteen young adults with unilateral recurrent patellar dislocation were investigated 5 y (mean, 8.5 y) after the first dislocation. Pre- and postcontrast T1 and precontrast T2 relaxation times were analyzed in four superficial and four deep patellar cartilage regions of both knees. Two hours after intravenous injection of 0.2 mM/kg Gd-DTPA(2-), postcontrast T1 [T1(Gd)] and R1 [1/T1 (precontrast)-1/T1 (postcontrast)] were analyzed in the regions. Muscle performance and patient-reported outcome were evaluated. ResultsWhen comparing the injured side with the noninjured side, differences were seen in the superficial half but not the deep half of the cartilage. T1(Gd) was shorter in the central part, whereas T2 was shorter in the periphery of the patellar cartilage (P<0.05). R1 demonstrated similar differences between healthy and diseased cartilage as T1(Gd) alone. The knee function was not correlated to the degenerative changes. ConclusionThe short T1(Gd) centrally indicates degenerative cartilage changes consistent with loss of glycosaminoglycans. Precontrast and R1 calculations may be excluded in clinical dGEMRIC, which simplifies the procedure. A decrease in T2 may be a very early sign of joint pathology but warrants further investigation. Magn Reson Med 74:1363-1369, 2015. (c) 2014 Wiley Periodicals, Inc

Can Na18F PET/CT bone scans help when deciding if early intervention is needed in patients being treated with a TSF attached to the tibia : insights from 41 patients.

PURPOSE: To demonstrate the usefulness of positron emission tomography (PET)/computed tomography (CT) bone scans for gaining insight into healing bone status earlier than CT or X-ray alone. METHODS: Forty-one prospective patients being treated with a Taylor Spatial Frame were recruited. We registered data obtained from successive static CT scans for each patient, to align the broken bone. Radionuclide uptake was calculated over a spherical volume of interest (VOI). For all voxels in the VOI, histograms and cumulative distribution functions of the CT and PET data were used to assess the type and progress of new bone growth and radionuclide uptake. The radionuclide uptake difference per day between the PET/CT scans was displayed in a scatter plot. Superimposing CT and PET slice data and observing the spatiotemporal uptake of 18F- in the region of healing bone by a time-sequenced movie allowed qualitative evaluation. RESULTS: Numerical evaluation, particularly the shape and distribution of Hounsfield Units and radionuclide uptake in the graphs, combined with visual evaluation and the movies enabled the identification of six patients needing intervention as well as those not requiring intervention. Every revised patient proceeded to a successful treatment conclusion. CONCLUSION: Numerical and visual evaluation based on all the voxels in the VOI may aid the orthopedic surgeon to assess a patient's progression to recovery. By identifying slow or insufficient progress at an early stage and observing the uptake of 18F- in specific regions of bone, it might be possible to shorten the recovery time and avoid unnecessary late complications.QC 20200929</p