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Biomedical subjects

R R Wroble

Publications and source records attributed to R R Wroble.

26 records · Page 2Linked to original sources
PubMedDate not supplied

An analysis of the pivot shift phenomenon. The knee motions and subluxations induced by different examiners.

The description of the pivot shift test and its modifications is for the most part based on clinical observations. We wished to precisely determine the knee motions and medial-lateral tibiofemoral compartment subluxations that examiners induce in the knee joint to produce the pivot shift phenomenon. Eleven skilled knee surgeons performed the pivot shift test on an instrumented cadaveric lower limb. The anterior cruciate and superficial medial collateral ligaments (long fibers) of one limb were sectioned to produce an abnormal state. An instrumented spatial linkage allowed all six degrees of freedom motions to be measured. Before and after ligament sectioning we determined the limits of knee motion under defined loading conditions. The tibial and femoral bony landmarks were digitized to determine the positions of the medial and lateral tibial plateaus in reference to the femoral condyles during the pivot shift tests. Each examiner performed his pivot shift test. The analysis of the data showed that examiners typically induced a coupled anterior translation and internal tibial rotation to produce an anterior tibial subluxation, and a coupled posterior translation and external tibial rotation to induce the reduction event. The magnitude of anterior subluxation of each plateau depended upon the examiner's technique. The maximal anterior subluxation of the lateral tibial plateau varied from 14 to 19.8 mm (mean, 17.2 +/- 2.0 mm), whereas anterior subluxation of the medial tibial plateau ranged from 6 to 16.9 mm (mean, 11.2 +/- 3.3 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Femur↗
PubMedDate not supplied

The diagnosis of knee motion limits, subluxations, and ligament injury.

The clinical diagnosis of knee ligament injuries requires the clinician to: 1) estimate the abnormal motion limits that occur in one or more of the six degrees of freedom that comprise three-dimensional motion; 2) determine the abnormal position (subluxation) of the medial and lateral tibiofemoral compartments; and 3) precisely define the anatomical structures injured and degree of that injury. To determine the clinician's ability to perform these tasks, we evaluated 11 knee surgeons' clinical examination for knee instability. The positions and motions included were measured in right-left cadaveric knees by a three-dimensional instrumented spacial linkage. We compared the clinicians' estimate of knee motion limits and subluxations with the actual measured values. Before and after the clinicians' examination, the three-dimensional limits of knee motion were measured in the knees in the laboratory under defined loading conditions. Also, in one knee, the ACL and superficial medial collateral ligament were cut and the examiners, none of whom were informed of the sectioning, were asked to arrive at a diagnosis. The results for all of the clinical instability tests were similar. There was wide variability between examiners in the starting position of knee flexion and tibial rotation and in the amount of tibial translation and rotation induced. Although some examiners displaced the knee to the maximal displacement limits obtained in the laboratory, others did not, by a substantial margin. This suggests a wide variation in the loads applied by examiners to the knee joint during the tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Anterior Cruciate Ligament↗
PubMedDate not supplied

Reproducibility of the knee signature system.

To assess trial-to-trial, installation-to-installation, and day-to-day effects of the Knee Signature System, we studied anterior/posterior translation measurements in six normal subjects. The protocol consisted of testing both knees on 6 days with three installations per day and three trials per installation. We recorded anterior, posterior, and total anterior/posterior translation at +/- 20 and +/- 40 pounds of force at 30 degrees of flexion. Additionally, after measuring anterior/posterior translation during passive knee extension, active extension, and active extension with 15 pounds of weight at the ankle, we calculated the difference in anterior translation at 30 degrees of flexion between each of these three conditions. We analyzed the size of the effects and computed 90% confidence limits using analysis of variance. Means and 90% confidence limits for total anterior/posterior translation measured at +/- 20 pounds of force were: right knee, 6.8 +/- 2.3; left knee, 8.2 +/- 2.0; and right/left difference, 1.5 +/- 2.7 mm. Left knee translation means were significantly greater than right knee means in all tests. Day-to-day effects, while statistically significant for right and left knee measurements, showed no significant effects for right/left differences. Trial-to-trial and installation-to-installation effects were not significant for any parameter. Right/left differences during knee extension testing were smaller than for the stress test, measuring 0.1 mm or less, but confidence limits were larger, being +/- 3.7 mm for active extension-passive knee extension, +/- 1.5 mm for 15 pounds of weight at the ankle-active extension, and +/- 4.6 mm for 15 pounds of weight at the ankle-passive knee extension. Active extension produced 6.3 mm more anterior translation at 30 degrees of flexion than passive extension.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

The role of the lateral extraarticular restraints in the anterior cruciate ligament-deficient knee.

We measured the increases in tibiofemoral motion when lateral structures were sectioned in anterior cruciate ligament-deficient knees of 20 unembalmed cadaveric whole lower limbs. Motion was measured with a six degrees-of-freedom electrogoniometer. The lateral structures investigated were the iliotibial band and mid-lateral capsule, lateral collateral ligament, and popliteus tendon and the posterolateral capsule. Cutting the anterolateral structures increased anterior translation and internal rotation, particularly in flexion. Increases in motions were highly variable, reflecting the variation in function in the lateral collateral ligament and posterolateral structures. Cutting the lateral collateral ligament produced small changes in anterior translation and external rotation and larger increases in adduction. Cutting the posterolateral structures produced small increases in external rotation. Large increases in external rotation were found only if the lateral collateral ligament was also sectioned. The posterolateral structures act in concert with the lateral collateral ligament in restraining internal and external rotation. External rotation was affected at all flexion angles; internal rotation was affected mainly in extension. Our results can be used in the diagnosis of complex knee ligament injuries. Findings of increased anterior translation in both flexion and extension and increased internal rotation at 90 degrees of flexion are consistent with combined injury to the anterior cruciate ligament and the anterolateral structures. The anterior cruciate ligament-deficient knee with significant posterolateral compromise (posterolateral structures/lateral collateral ligament) would exhibit larger anterior translation in extension than in flexion, increased adduction, and increased external rotation in both flexion and extension.

Adult↗
PubMedDate not supplied

Role of the medial structures in the intact and anterior cruciate ligament-deficient knee. Limits of motion in the human knee.

We measured motion limits in human cadaveric knees before and after sectioning the anterior cruciate ligament and the medial structures. Sectioning the medial collateral ligament in an anterior cruciate ligament-deficient knee increased the anterior translation limit at 90 degrees of flexion but not at 30 degrees of flexion. The tibia displaced straight anteriorly without exhibiting the coupled internal rotation that occurred in intact and anterior cruciate ligament-deficient knees. A lateral 15 N-m abduction moment produced a coupled external rotation in the medial collateral ligament-deficient knee. This was in marked contrast to intact, anterior cruciate ligament-deficient, or combined medial collateral ligament and anterior cruciate ligament-deficient knees, in which an abduction moment produced a coupled internal rotation. Sectioning only the medial collateral ligament caused a small but significant increase in the abduction rotation limit, whereas larger increases in the abduction rotation limit occurred when the posterior oblique ligament and posterior medial capsule were cut in addition to the medial collateral ligament. Cutting the medial collateral ligament increased the external rotation limit. The increase was independent of whether the anterior cruciate ligament was intact or sectioned. Subsequent cutting of the posterior oblique ligament and posterior medial capsule further increased the external rotation limit.

Adult↗
PubMedDate not supplied

Histiocytosis X with scoliosis and osteolysis.

Histiocytosis X can exhibit a variety of musculoskeletal manifestations. Nonetheless, this case exhibits two striking features. Severe progressive scoliosis and massive osteolysis of both femoral shafts occurred in conjunction with the Hand-Schüller-Christian form of histiocytosis X. The scoliosis was treated successfully by posterior fusion and instrumentation. The clinical features of histiocytosis X are reviewed. Speculation as to the etiology of these features is presented.

Bone Resorption↗