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Biomedical subjects

D M Daniel

Publications and source records attributed to D M Daniel.

30 records · Page 2Linked to original sources

Instrumented measurement of anterior knee laxity in patients with acute anterior cruciate ligament disruption.

Instrumented anterior/posterior laxity measurements were performed on 138 patients evaluated within 2 weeks of injury with their first traumatic knee hemarthrosis. All patients were tested with the MEDmetric Arthrometer model KT-1000 in a knee injury clinic. Seventy-five of the patients had knee arthroscopy. Thirty-three had arthrometer laxity tests under anesthesia. Eighty-seven percent of patients arthroscoped had anterior cruciate ligament (ACL) tears and 41% had meniscus tears. One hundred twenty normal subjects were tested to establish normal anterior laxity values. Three tests were used to evaluate anterior laxity: anterior displacement between a 15 and 20 pound force (compliance index), anterior displacement with a 20 pound force, and anterior displacement with a high manually applied force. Displacement measurements in normal subjects revealed a wide range of normal laxity with a small right knee-left knee difference. For example, the 20 pound anterior displacement range was 3 to 13.5 mm with a right knee-left knee difference (mean +/- SD, 0.8 +/- 0.7 mm). Eighty-eight percent of the normals had a right-left difference of less than 2 mm. In the 53 patients arthroscoped who had complete ACL tears, the anterior laxity measurements performed in the clinic were suggestive or diagnostic of pathologic anterior laxity in 50 patients.

Acute Disease↗

Soft tissue fixation to bone.

This experiment was designed to compare the immediate fixation strengths of various methods of soft tissue fixation techniques. The fixation techniques tested were the barbed staple, stone staple, suture techniques, screw with spiked plastic washer, and the screw with spiked soft tissue plate. Cadaveric soft tissue specimens were classified into three distinct morphologic types: capsular, tendinous, and extensor mechanism tissue. Each specimen was fixed to bone by one of the fixation techniques. The specimens were loaded in a cyclical fashion until fixation failure occurred. One hundred thirty-seven trials were performed. The screws with the spiked plastic washer and soft tissue plate proved superior overall for all three tissue types. The stone staple was the poorest technique tested. Therefore, if cyclic loading or tension is anticipated at the fixation site, the fixation technique of choice would be the screw with spiked plastic washer or soft tissue fixation plate.

Bone Screws↗

An in vitro study of anterior cruciate ligament graft placement and isometry.

Isometric positioning of the ACL graft or prosthesis is an important consideration in successful reconstruction of the ACL-deficient knee. This study documented the relationship between graft placement and intraarticular graft length changes and graft tension changes during knee passive range of motion. Fifteen fresh cadaveric knees were mounted in stabilizing rigs. The ACL was identified and cut in each specimen. Intraarticular reconstruction was then performed using a 6 mm polypropylene braid (3M LAD, St. Paul, MN). The following graft placements were evaluated: 1) over-the-top, 2) modified over-the-top with a femoral bone trough, 3) femoral drill hole positions, and 4) tibial drill hole positions. The proximal end of the graft was fixed to the lateral aspect of the femur with a screw and spiked washer. The distal end of the graft was attached to a turnbuckle attached to a load cell on the anterior aspect of the tibia. The knee was then extended passively from 90 degrees to 0 degrees. Two experiments were performed. In Experiment A, the turnbuckle was adjusted to keep graft tension constant and the graft length changes were recorded. In Experiment B, the graft fixation sites were not altered and tension changes with range of motion were recorded. A change in the graft distance between attachment sites with knee range of motion can be monitored either by ligament length or by tension change. With the over-the-top technique, in Experiment A, the graft distance between attachment sites increased as the knee was extended (means = 4.9 mm); in Experiment B, large tension increases were recorded with knee extension.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗

Patellofemoral problems after anterior cruciate ligament reconstruction.

UNLABELLED: Between 1982 and 1986, 126 patients who had undergone ACL reconstruction were followed in a prospective manner. One year follow-up statistics were reviewed for the presence of 13 different complications. The most prevalent complications were quadriceps weakness, flexion contracture, and patellofemoral pain. Quadriceps weakness (strength less than 80% of the normal side) was present in 65% of patients and correlated positively with flexion contracture, patellar irritabibilty, and ACL reconstructions using patellar tendon grafts. Flexion contracture of 5 degrees or more was present in 24% of patients and correlated positively with increased age and patellar irritability. Patellofemoral pain was present in 19% of patients and correlated positively with flexion contracture. CLINICAL RELEVANCE: The three most common complications of knee ligament surgery are shown to be strongly interrelated. It is likely that a causal relationship is present in which flexion contracture causes patellofemoral irritability, and that both of these factors, alone or in combination, result in quadriceps weakness. If this theory is correct, then it is crucial that postoperative rehabilitation programs place a major emphasis on the avoidance of flexion contracture.

Adolescent↗

Assessing the limits of knee motion.

Ten patients were examined clinically by 11 experienced knee surgeons and with three measurement devices (Genucom, Knee Signature System, and KT-1000). Nine of the 10 patients examined had sustained documented intraarticular ligament disruptions including eight ACL disruptions and five posterior cruciate ligament disruptions. The eight patients with ACL injuries had undergone reconstructive surgery. The clinical examination test sequence was performed as described by the International Knee Documentation Committee. Testing results were reported as estimated degrees of angulation or millimeters of displacement. Testing results were divided into two groups based on the index minus nonindex knee difference. Eighteen displacement tests were performed on each knee by each examiner. The index minus nonindex knee difference was greater than 3 mm in 16% of the tests. Only 1 of the 198 displacement tests performed on the subject who did not have a ligament disruption was recorded as an index minus nonindex difference greater than 3 mm. There was appreciable difference between measurements recorded by different examiners, particularly anterior/posterior measurements in patients who had sustained combined anterior and posterior cruciate ligament injuries. There is a need to rigorously evaluate limits of motion tests that are used to develop treatment plans and report the results of ligament surgery.

Adult↗

The effect of tibial attachment site on graft impingement in an anterior cruciate ligament reconstruction.

Anterior cruciate ligament reconstructions were performed in 14 cadaveric knee specimens using a 6-mm wide polypropylene graft. The graft was passed through a femoral tunnel at the attachment site of the anterior medial bundle of the anterior cruciate ligament. Seven tibial positions were evaluated as to the change in attachment site distance with passive range of motion and impingement on the intercondylar notch as the knee was passively ranged from 0 degree to 90 degrees of flexion. Impingement was also evaluated while the knee was extended by pulling through the quadriceps tendon. The tibial placement site affects the change in attachment site distance with passive range of motion and impingement on the intercondylar notch. Grafts passed through drill holes anterior and lateral to the insertion of the anterior fibers of the anterior cruciate ligament consistently produced impingement on the anterior outlet of the intercondylar notch. Knee extension with quadriceps tendon pull produced graft impingement in a greater arc of flexion than passive extension. Based on this study, optimum placement of the tibial hole should be at the insertion of the anterior medial fibers of the anterior cruciate ligament. Impingement recognized during surgery can be alleviated with notchplasty. With passive extension there should be a 3-mm clearance between the anterior portion of the intercondylar notch and the ligament graft to prevent the graft from impinging when the knee is actively extended.

Anterior Cruciate Ligament↗

Hamstrings--an anterior cruciate ligament protagonist. An in vitro study.

A cadaveric model that incorporated quadriceps and hamstrings muscle loads was developed to simulate the squat exercise. The addition of hamstrings load affected knee kinematics in two ways. First, anterior tibial translation during flexion ("femoral roll-back") was significantly reduced (P = 0.003) and second, internal tibial rotation during flexion was reduced (P = 0.008). However, quadriceps force was unaffected by the addition of hamstrings load. Thus, it seems likely that hamstrings muscle activity that has been observed in vivo during a squat probably functions synergistically with the anterior cruciate ligament to provide anterior knee stability. After the ACL was sectioned, anterior tibial translation was significantly increased during the squat (P = 0.04). The anterior cruciate ligament was then reconstructed using a graft instrumented with a load cell. During passive motion, maximal graft tension was at full extension. During simulated squat exercise, the addition of hamstrings caused a significant decrease in graft load (P = 0.006). During the squat, maximal graft tension was at full extension, and was equal to the graft tension at full passive extension. Thus, the squat exercise may be useful in the early stages of anterior cruciate ligament rehabilitation.

Aged↗

The anterior cruciate ligament in controlling axial rotation. An evaluation of its effect.

Changes in axial tibial rotation after anterior cruciate ligament sectioning were evaluated in 14 fresh human knee joints. Simulation of vertical stance in a quadriceps-stabilized knee was performed. Internal and external rotational torques were applied before and after anterior cruciate ligament sectioning. Pivot shift tests were done in the intact and anterior cruciate ligament sectioned knee. Results of pivot shift tests were all negative before sectioning and positive after isolated sectioning. No significant change in axial rotation occurred between the intact and sectioned knee for external rotation (P = 0.24) or internal rotation (P = 0.12). Presence of a load at the femoral housing in both the intact and ligament-sectioned knees caused a significant change in external rotation (P < 0.0001). No significant change was noted in internal rotation between loaded and unloaded states (P = 0.70). Total tibial rotation in the intact knee was noted to vary between 31 degrees at 0 degree of flexion and 42 degrees at 60 degrees of flexion. These results suggest that the anterior cruciate ligament does not play a significant role in limiting axial rotation and that rotational instability is not a major factor after isolated anterior cruciate ligament rupture.

Aged↗

Graft impingement after anterior cruciate ligament reconstruction. Presentation as an active extension "thunk".

Twelve of 215 patients with an anterior cruciate ligament reconstruction developed a "thunk," a low-pitched sound, on active extension of the operative knee at an average of 5 months after surgery. In 4 of the patients the thunk resolved without surgical treatment at an average of 4 months after onset (range, 2 to 6). In 3 of the patients an increase in anterior knee laxity was associated with resolution of the thunk. Seven of the patients were treated with arthroscopic examination. Six of the patients had graft impingement on the lateral wall or the roof of the notch with knee extension. The thunk was eliminated with an adequate notchplasty that corrected the impingement. In the other patient the thunk was secondary to fibrosis of the anterior fat pad. One patient with a persistent thunk declined surgery and was lost to followup.

Adolescent↗

Fate of the ACL-injured patient. A prospective outcome study.

We followed 292 patients who had sustained an acute traumatic hemarthrosis for a mean of 64 months. The KT-1000 arthrometer measurements within 90 days of injury revealed the injured knee was stable in 56 patients and unstable in 236. Forty-five unstable patients had an ACL reconstruction within 90 days of injury. Surgical procedures performed > 90 days after injury included ligament reconstruction in 46 patients. Factors that correlated with patients who had late surgery for a meniscal tear or an ACL reconstruction (P < 0.05) were preinjury hours of sports participation, arthrometer measurements, and patient age. Follow-up data are presented for the patients divided into four groups: I, early stable, no reconstruction; II, early unstable, no reconstruction; III, early reconstruction; and IV, late reconstruction. No patient changed occupation because of the knee injury. Hours per year of sports participation and levels of sports participation decreased in all groups. Joint arthrosis was documented by radiograph and bone scan. Joint surface injury abnormalities observed at surgery and meniscal surgery showed greater abnormalities by radiograph and bone scan scores (P < 0.05). Reconstructed patients had a higher level of arthrosis by radiograph and bone scan.

Adult↗

Instrumented measurement of patellar mobility.

To provide an objective analysis of medial and lateral patellofemoral laxity, we examined 94 uninjured athletic subjects and 22 patients with unilateral lateral patellar dislocation. We developed an instrument to measure the compliance of the medial and lateral patellar restraints. The instrument recorded the force-displacement relationship as the patella was pushed medially and laterally. Subtracting the medial displacement from the lateral displacement at a given force level allowed the tester to assess the peripatellar soft tissue "balance." The results for both the 2.5- and the 5-pound tests were significant. Paired comparisons differentiated the three groups, with significant differences between control and affected (P = 0.0001), control and contralateral (P = 0.0036), and affected and contralateral (P = 0.0157) knees. The mean result of the lateral minus medial displacement test for our sample population of control subjects was -2.1 mm for the 5-pound test. A negative value in this test indicates that medial displacement exceeds lateral displacement. This finding was present in 81% of control subjects. In contrast, the mean result for the patients' affected knees was +3.2 mm for the 5-pound test. Using the value of 0.0 mm as the diagnostic determinant for peripatellar imbalance, we found a test sensitivity of 91% and a specificity of 81%.

Adolescent↗