Orthopedic radiometry. Quantitation and correlation.
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Orthopedics↗
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Results for “Photogrammetry”
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Micromotion of the total knee.
Eight patients with gonarthrosis were operated on with a noncemented all-polyethylene ICLH endoprosthesis. Radiographic examination up to 2 years postoperatively included roentgen stereophotogrammetric analysis (RSA), which demonstrated micromotion of all the implants. However, the mean subsidence was only 0.4 mm for both the tibial and the femoral components.
Aged↗
Stapling for tibial-growth deformity. A case report on roentgen stereophotogrammetric analysis.
A 9-year-old boy sustained a Salter-Harris Type IV fracture in the proximal tibia. The injury resulted in a progressive valgus deformity, detected already after 3 months by roentgen stereophotogrammetry. After temporary stapling medially, the growth rate increased laterally and the deformity was corrected. Unilateral stapling is an alternative procedure for correcting angular deformity following a physeal injury.
Child↗
Roentgen stereophotogrammetry. Review of orthopedic applications.
Roentgen stereophotogrammetry is based on radiographic examinations of calibration cages and object markers implanted in the skeleton. Accurate measurements of radiographs and computer-assisted calculations can provide a three-dimensional motion analysis. Since its introduction 15 years ago, roentgen stereophotogrammetry has found an increasing number of orthopedic applications, which are reviewed here: growth, prosthetic fixation, joint kinematics and stability, fracture stability, and the healing course of spinal fusion and pelvic and tibial osteotomies.
Bone and Bones↗
Chronic lateral instability of the ankle. Roentgen stereophotogrammetry of talar position.
Using roentgen stereophotogrammetric analysis (RSA), we investigated the talar mobility in 54 ankles during the anterior drawer and adduction tests. Talar tilt was increased in ankles with unilateral symptoms of chronic lateral instability. No other difference in talar tilt and anterior drawer sign was noted comparing ankles with and without symptoms. We conclude that mechanical tests cannot always verify the diagnosis "chronic lateral instability of the ankle".
Adolescent↗
Cold flow reduced by metal backing. An in vivo roentgen stereophotogrammetric analysis of unicompartmental tibial components.
Thirty-six cases of unicompartmental arthroplasty for gonarthrosis were followed for 6 years. The arthroplasties were prepared for roentgen stereophotogrammetric analysis (RSA) by marking the tibial components and the tibial methaphysis with tantalum balls. Nineteen out of 24 cases with a polyethylene tibial component had an increase in intermarker distances signifying progressive enlargement of the prosthesis due to cold flow. The enlargement was up to 2.8 percent of the circumference and was greater for 9 mm than for 12 mm thick components. Twelve cases with a metal-backed tibial component showed no cold flow. No correlation between cold flow and demographic, clinical, or radiographic data was found.
Aged↗
Early detection of prosthetic-hip loosening. Comparison of low- and high-viscosity bone cement.
In 1987, we reported the 1-year migration of the prosthetic components in 16 hips followed by roentgen stereophotogrammetry after fixation with either low- or high-viscosity cement. We now report the migration of these prosthetic components during another 2 postoperative years. Eight acetabular components, four in each group, migrated cranially; and four femoral components, three in the low-viscosity and one in the high-viscosity group, migrated distally. All but two migrations were obvious 4 months postoperatively, which indicates that what is called late loosening is the result of late detection rather than of late occurrence of loosening. Low-viscosity cement did not provide improved prosthetic fixation.
Bone Cements↗
Brace effects on the unstable knee in 21 cases. A roentgen stereophotogrammetric comparison of three designs.
Three designs of knee braces were investigated in 21 knees with arthroscopically verified old tears of the anterior cruciate ligament. Anterior-posterior and rotatory instability with and without anterior traction were recorded with roentgen stereophotogrammetric analysis. Two of the designs examined reduced the anterior-posterior instability (ECKO, modified Lenox Hill), but not to normal levels. At 20 degree of flexion, none of the braces decreased the internal rotatory instability, whereas one type (modified Lenox Hill) reduced the external rotatory instability.
Adult↗
Wear and loosening of the hip prosthesis. A roentgen stereophotogrammetric 3-year study of 14 cases.
Fourteen patients were followed by roentgen stereophotogrammetry for 3 years after hip arthroplasty. In 11 of the 14 acetabular components, definite wear was identified. The mean wear rate was 0.13 mm per year. There was no correlation between the wear and loosening of either the acetabular or the femoral component. Our findings indicate that products of wear do not initiate prosthetic loosening.
Follow-Up Studies↗
Stability of femoral neck fracture. Roentgen stereophotogrammetry of 29 hook-pinned fractures.
The stability of hook-pin fixation during weight bearing was studied in 29 femoral neck fractures using roentgen stereophotogrammetric analysis. Twenty-three fractures became stable within 1 to 9 months, whereas redisplacement or continuing movement of the fracture occurred in 6 cases. Displaced fractures shortened about 7 mm more than undisplaced ones before healing. The rotations of the femoral heads were greatest in the forward/backward direction, followed by varus-valgus tilting in both fracture groups. Rotation about the longitudinal axis was recorded in the displaced fractures, mainly as a retroversion, whereas no rotation occurred about this axis in the undisplaced fractures. Healing after 6 months, intermediate fracture fragments, and a decreased Pauwels' angle seemed to imply increased fracture compression or rotatory instability. Fractures that subsequently developed healing complications displayed an increased distal displacement of the femoral head during the first postoperative month.
Adult↗
Abnormal kinematics of the artificial knee. Roentgen stereophotogrammetric analysis of 10 Miller-Galante and five New Jersey LCS knees.
The in vivo kinematics of two types of unconstrained, posterior cruciate ligament retaining knee prostheses were analyzed 1 year postoperatively using roentgen stereophotogrammetric analysis. Ten knees had the Miller-Galante and five the New Jersey LCS design. The Miller-Galante knees displayed decreased adduction during active flexion when compared with normal knees. In both types of prostheses, there was decreased medial and increased proximal and posterior displacement. The abnormal kinematics probably reflect the design of the articular surfaces, the absence of the anterior cruciate ligament, and the dysfunction of the posterior cruciate ligament.
Aged↗
Fixation and loosening of hip prostheses. A review.
Studies using roentgen stereophotogrammetry and bone scintigraphy support a narrow definition of prosthetic fixation (viz., nonmigration), and consequently a broad definition of loosening. Roentgen stereophotogrammetric research indicates that if loosening occurs, it is initiated at an early stage; insufficient initial fixation or loss of fixation by resorption of a layer of heat-injured bone may cause prosthetic instability and progressive bone resorption. Migration of one or both prosthetic components can be revealed by roentgen stereophotogrammetry in many asymptomatic hips during the first postoperative year--some of these components will probably fail in the future. The femoral component is exposed to greater shear stresses than the acetabular component, and it is uncertain whether fixation of the femoral component can be achieved more than occasionally without the use of bone cement.
Bone Cements↗
Polyethylene wear in knee arthroplasty. A review.
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Corrosion↗
The accuracy of measurements of femoral neck fractures. Conventional radiography versus roentgen stereophotogrammetric analysis.
Postoperative displacement of the femoral head center was measured in 60 intracapsular hip fractures at repeated conventional radiographic (CR) and roentgen stereophotogrammetric (RSA) examinations. The measurements of the conventional radiographs (405 pairs) were done on a digitizing table. Totally, 105 pairs of these radiographs (AP and lateral, CR) were measured by 2 observers. Manual measurements were also made on 176 pairs of the conventional radiographs. Conventional radiographs tended to overestimate or underestimate the average displacements up to about 2 mm. Two standard deviations of the differences (RSA-CR) varied from 5.8 to 9.6 mm depending on the direction of the movements. The accuracy of the measurements on conventional radiographs did not differ between the 2 examiners. The digitizing table was found to be more accurate than the manual measurements. The accuracy of conventional radiography can most likely be improved by using a strictly standardized examination technique.
Femoral Neck Fractures↗
Scintimetry after total knee arthroplasty. Prospective 2-year study of 18 cases of arthrosis and 15 cases of rheumatoid arthritis.
33 consecutive patients (18 arthrosis, 15 rheumatoid arthritis), operated on with total knee arthroplasty and randomized to cemented (18 knees) or cementless fixation (15 knees), were investigated with scintimetry 3, 6, 12, and 24 months postoperatively. Migration was evaluated with simultaneous roentgen stereophotogrammetric (RSA) examinations. The scintimetric activity in the ipsilateral femoral diaphysis decreased and the activity in the tibial diaphysis increased during the observation period. Constant and low activity was recorded in front of the femoral component. This region was chosen as a reference. Three months after surgery, high activity was noted under the tibial component in knees with a preoperative varus deformity. After 2 years, the activity had decreased to the same level as in the patients with a valgus deformity. Diagnosis and mode of fixation did not influence the activity. Low postoperative activity was recorded in the tibial metaphyses if no rotatory displacement of the tibial component occurred.
Adult↗
Laxity and graft fixation after reconstruction of the anterior cruciate ligament. A roentgen stereophotogrammetric analysis of 11 patients.
The sagittal laxity of the knee was measured in 11 consecutive patients with chronic anterior cruciate ligament deficiency before and 1 year after ligament reconstruction with a free bone-tendon-bone graft from the patellar tendon (modified Clancy technique). Tantalum markers were implanted in the femur, in the tibia, and in the graft for roentgen stereophotogrammetric analysis (RSA) of the sagittal laxity and the migration of the bony ends of the graft. The precision in measurements of total anterior-posterior displacement (+/- 2 SD of the differences between repeated measurements) was 2.2 mm. A decrease in total anterior-posterior displacement from 12 mm before reconstruction of 5 mm 1 year postoperatively using a stress load of 150 N was found. The bony ends of the free graft migrated maximally 0.7 mm, implying adequate fixation.
Adolescent↗
Laxity after cruciate ligament injury in 94 knees. The KT-1000 arthrometer versus roentgen stereophotogrammetry.
We examined 94 knees with chronic anterior cruciate ligament injuries, 55 of which had been operated with ligament reconstruction, using the KT-1000 arthrometer (89 N anterior force) and roentgen stereophotogrammetry (RSA, 150 N anterior, 80 N posterior force). In intact knees the tibial displacement did not differ between the methods. In injured knees, operated or not, the KT-1000 recorded smaller AP translations and side-differences than RSA. Thus, the stabilizing effect of reconstructive surgery may be overrated, if evaluated with the standard KT-1000 technique.
Adolescent↗
Biodegradable fixation of ankle fractures. A roentgen stereophotogrammetric study of 32 cases.
We performed a prospective randomized study comparing fixation with biodegradable polyglycolic acid (PGA) rods (n 15) or screws (n 17) in 32 selected displaced supination-eversion fractures. Immediate postoperative weight bearing in a walking cast was encouraged. An exact reconstruction of the ankle mortise was achieved in 26/32 ankles. Roentgen stereophotogrammetric analysis (RSA) revealed rather small movements in the ankle mortise during fracture healing. A better stability was achieved by using screws. After 6 months the clinical results did not differ. One case of sinus formation and one with local effusion occurred; both healed without impairing the clinical result. To compare the results with a nondegradable osteosynthesis technique, a reference group of supination-eversion fractures previously operated on with cerclage-wires, staples and pins was used. RSA showed better fracture stability with nondegradable fixation. The clinical results, however, did not differ.
Adult↗