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Biomedical subjects

J Robert Giffin

Publications and source records attributed to J Robert Giffin.

8 recordsLinked to original sources
PubMed2006

Radiographic measures of knee alignment in patients with varus gonarthrosis: effect of weightbearing status and associations with dynamic joint load.

BACKGROUND: Radiographic measures of lower limb malalignment are used to indicate abnormal loading of the knee and to plan corrective procedures. HYPOTHESES: Weightbearing status during hip-to-ankle radiographs will significantly affect malalignment measures; malalignment in single-limb standing will be most highly correlated to the external knee adduction moment during gait, a proposed dynamic measure of functional knee joint load. STUDY DESIGN: Controlled laboratory study. METHODS: Mechanical axis angle was measured in 40 patients with varus gonarthrosis from hip-to-ankle radiographs taken with patients in single-limb standing, double-limb standing, and supine positions. Kinematic and kinetic data were collected during walking and used to calculate the peak adduction moment about the knee. RESULTS: Repeated-measures analysis of variance and Scheffé post hoc tests indicated that mechanical axis angle measured on single-limb standing radiographs (-8.7 degrees +/- 4.0 degrees) was significantly greater than on double-limb standing radiographs (-7.1 degrees +/- 3.8 degrees), which was significantly greater than on supine radiographs (-5.5 degrees +/- 2.8 degrees). The peak knee adduction moment (2.8 +/- 0.8 percentage body weight x height) was only moderately correlated with mechanical axis angle on single-limb standing (r = -0.46), double-limb standing (r = -0.45), and supine (r = -0.43) radiographs. CONCLUSION: Patient position significantly affects frontal plane knee alignment. However, the peak knee adduction moment is only moderately correlated to mechanical axis angle, regardless of weightbearing status. CLINICAL RELEVANCE: These findings are inconsistent with the hypothesis that mechanical axis angle measured in single-limb standing is more representative of dynamic joint load and further highlight the differences between static and dynamic measures. Results also underscore the importance of reporting patient position during radiographs and keeping positions consistent when evaluating patients over time.

Adult↗
PubMed2005

Associations among knee adduction moment, frontal plane ground reaction force, and lever arm during walking in patients with knee osteoarthritis.

The adduction moment about the knee during walking gait has been proposed as an indirect measure of dynamic knee joint load. However, the relative contributions of the variables primarily used to calculate the knee adduction moment have not been investigated. The objectives of this paper were to: (1) describe and compare the magnitude and temporal characteristics of the knee adduction moment, frontal plane lever arm, and frontal plane ground reaction force (GRF) during gait in patients with knee osteoarthritis (OA) and, (2) examine the associations among these variables. Results indicated that both the knee adduction moment and the frontal plane GRF varied considerably throughout stance and exhibited the characteristic "double-hump" pattern, while the frontal plane lever arm magnitude varied only slightly during stance. Knees with OA had significantly greater peak knee adduction moments and frontal plane lever arms, but significantly less peak frontal plane GRF than knees without OA. Pearson product moment correlations indicated a higher association between peak knee adduction moment and peak frontal plane lever arm than between peak knee adduction moment and peak frontal plane GRF, particularly in knees with OA. These results suggest that the frontal plane lever arm assessed during walking is an important variable in the examination of knee OA, and warrants further investigation.

Adult↗
PubMed2004

Internal fixation of radial neck fractures: an in vitro biomechanical analysis.

OBJECTIVE: To assess the fixation rigidities of a custom designed blade plate, a 2.7 mm T-plate and 3.0 mm cannulated screws. DESIGN: A cadaveric non-comminuted radial neck fracture model was employed to test the three fixation methods, using a multi-directional shear loading protocol. BACKGROUND: The management of displaced radial neck fractures in adults remains unsatisfactory due to failure of internal fixation with secondary loss of reduction, and non-unions. METHODS: The stiffness of the various fixation methods was measured in five directions of loading in the transverse plane. Failure testing was performed on the final testing condition for each specimen, in a posteroulnar to anteroradial direction. RESULTS: The direction of specimen loading did not have a significant effect on the stiffness of the various methods of fixation (P = 0.4). There was no significant difference in the fixation stiffness between the 3.0 mm screws or blade plate, however, both were superior to the T-plate (P < 0.05). CONCLUSIONS: Although the 2.7 mm T-plate has been reported in the literature as a viable method of fixation for radial neck fractures, it may not be optimal from the viewpoint of fixation stability. In the setting of a non-comminuted radial neck fracture, the use of cross-cannulated screws or blade plate fixation is preferred.Relevance This study supports the use of cross-cannulated screws or blade plate fixation for non-comminuted fractures of the radial neck.

Aged↗
PubMed2004

Reliability of lower limb frontal plane alignment measurements using plain radiographs and digitized images.

This study evaluated the reliability of lower limb frontal plane alignment measures obtained from plain radiographs measured manually and digitized images measured using a custom computer software package (TheHTO Pro; Fowler Kennedy Sport Medicine Clinic, London, Ontario, Canada). Radiographic measurements used in the planning of high tibial osteotomy, including the mechanical axis angle and mechanical axis deviation, were measured on 42 hip-to-ankle radiographs on two separate occasions by two different raters (A.V.S., J.J.D.). Intraclass correlation coefficients (0.96-0.99) indicated excellent agreement between the manual and computer measurements, suggesting both methods can be used interchangeably. Although test-retest and inter-rater reliability tended to be slightly better when using TheHTO Pro, intraclass correlation coefficients were excellent for both methods (0.97-0.99). The standard errors of measurement were <1 degree for mechanical axis angle and <2 mm for mechanical axis deviation, regardless of method or rater. Based on the observed standard errors of measurement, conservative estimates for the error associated with an individual's mechanical axis angle at one point is approximately 1.5 degrees, and the minimal detectable change on reassessment is approximately 2 degrees. The error associated with an individual's mechanical axis deviation at one point is approximately 4 mm, and the minimal detectable change on reassessment is approximately 6 mm. These results suggest that manual and computer measurements of lower limb frontal plane alignment can be calculated with minimal measurement error. However, the small errors associated with both methods should be considered when making clinical decisions.

Adult↗
PubMed2004

Effects of increasing tibial slope on the biomechanics of the knee.

PURPOSE: To determine the effects of increasing anterior-posterior (A-P) tibial slope on knee kinematics and in situ forces in the cruciate ligaments. METHODS: Ten cadaveric knees were studied using a robotic testing system using three loading conditions: (1) 200 N axial compression; (2) 134 N A-P tibial load; and (3) combined 200 N axial and 134 N A-P loads. Resulting knee kinematics were determined before and after a 5-mm anterior opening wedge osteotomy. Resulting in situ forces in each cruciate ligament were determined. RESULTS: Tibial slope was increased from 8.8 +/- 1.8 degrees to 13.2 +/- 2.1 degrees, causing an anterior shift in the resting position of the tibia relative to the femur up to 3.6 +/- 1.4 mm. Under axial compression, the osteotomy caused a significant anterior tibial translation up to 1.9 +/- 2.5 mm (90 degrees ). Under A-P and combined loads, no differences were detected in A-P translation or in situ forces in the cruciates (intact versus osteotomy). CONCLUSIONS: Results suggest that small increases in tibial slope do not affect A-P translations or in situ forces in the cruciate ligaments. However, increasing slope causes an anterior shift in tibial resting position that is accentuated under axial loads. This suggests that increasing tibial slope may be beneficial in reducing tibial sag in a PCL-deficient knee, whereas decreasing slope may be protective in an ACL-deficient knee.

Aged↗
PubMed2003

Revision anterior cruciate ligament reconstruction.

Revision ACL surgery is indicated in patients who present with pathologic anterior laxity on clinical examination that reproduces their symptoms of instability during activities of daily living or athletic activities. The goals of the revision ACL surgery are to stabilize the knee, prevent further injury to the articular cartilage and menisci, and maximize the patient's function. Successful revision ACL surgery requires a thorough preoperative evaluation, including a detailed history, physical examination, and radiographic evaluation. Preoperative planning begins with a determination of the mechanisms of failure for the initial ACL reconstruction. Often a primary, as well as secondary cause, for failure can be identified. The determination of the cause of failure is the first step in a carefully-constructed treatment plan, which includes consideration of skin incisions to be used, method of graft removal, hardware removal, the need for a staged procedure or concomitant surgery, graft material selection, tunnel placement, graft fixation, and postoperative rehabilitation protocol. Despite the most meticulous planning, unanticipated findings may be encountered in the operating room, and the preoperative plan should have enough flexibility to accommodate these developments. Finally, it is crucial to counsel the patient preoperatively to limit his or her expectations regarding their surgical outcome. Given the complexity of revision ACL reconstruction, patient expectations must be adjusted to realistically match the potential for success. With proper planning, attention to detail, and appropriate patient expectations, revision ACL surgery can result in a beneficial and satisfying patient outcome.

Anterior Cruciate Ligament↗
PubMedDate not supplied

Clinical outcomes after combined meniscal allograft transplantation and anterior cruciate ligament reconstruction.

BACKGROUND: Concomitant meniscal transplantation performed at the time of ligament surgery may help to protect the anterior cruciate ligament graft. PURPOSE: To determine the objective and subjective clinical outcomes after combined anterior cruciate ligament reconstruction and meniscal allograft transplantation. STUDY DESIGN: Uncontrolled retrospective review. METHODS: Twenty-eight patients who underwent anterior cruciate ligament reconstruction along with meniscal transplantation were retrospectively evaluated postoperatively at an average of 2.8 years (range, 1.8 to 5.6). RESULTS: On the International Knee Documentation Committee overall subjective assessment, 86% had normal or nearly normal scores. The SF-36 physical and mental component summary scores were at higher levels than those of the patients' age- and sex-matched populations. Objectively, nearly 90% had normal or nearly normal Lachman and pivot shift test scores. The KT-1000 arthrometer testing at 30 pounds and maximum manual both demonstrated an average increased anterior translation of 1.5 mm compared with the contralateral knee. Joint space narrowing of the transplanted compartments was not significantly different from that of the contralateral knee. CONCLUSIONS: Meniscal transplantation with anterior cruciate ligament reconstruction can be a beneficial procedure in properly selected patients with either chronic anterior cruciate ligament insufficiency or failed anterior cruciate ligament surgery. Restoration of meniscal function may provide protection for the articular cartilage and improve joint stability.

Adolescent↗