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Biomedical subjects

M E Pollard

Publications and source records attributed to M E Pollard.

6 recordsLinked to original sources
PubMed2001

Interarticular bone tunnel healing.

PURPOSE: To evaluate the healing behavior of an interarticular bone tunnel exposed continuously to a synovial environment. TYPE OF STUDY: Experimental in vivo animal model. METHODS: Twenty-six adult rabbits had 3.2-mm diameter tunnels drilled in the femur and tibia of both hind-limb stifle joints parallel to but without violation of the native anterior cruciate ligament (ACL). The animals were euthanized at 1, 2, 4, and 12 weeks postoperatively. Decalcified sections were made of the bone tunnels and new bone formation was computer quantified using histomorphometric methods at each time interval. RESULTS: In this model, bone tunnel healing velocity was most rapid between 1 and 2 weeks after surgery. Both femoral and tibial interosseous tunnels showed substantial bone ingrowth (71% of bone tunnel volume) by 2 weeks postoperatively. The peripheral tunnel segment, that third of the tunnel furthest from the joint surface, healed rapidly and was 99% occluded with bone (99% confidence interval, 93.7% to 100%) at 2 weeks. Tunnel ingrowth was delayed and incomplete in the articular third of the tunnel, especially the femoral side. At 12 weeks, by volume, only 69.1% (99% confidence interval, 52.3% to 85.7%) of the interarticular third of the femoral tunnel was ingrown with new bone. Peripheral third bone tunnel healing was significantly greater than articular third tunnel healing at all time intervals; P <. 005 for the femoral and P <. 05 for the tibial tunnel. CONCLUSIONS: Interarticular bone tunnels heal from the outside in. At 12 weeks, bone healing was slower and incomplete in the articular segment of the tunnel, closest to the joint surface. The same biologic factors that impede intersubstance ACL healing may interfere with bone tunnel healing and be another cause of bone tunnel enlargement after ACL reconstruction.

Animals↗
PubMed1995

Radiographic sizing for meniscal transplantation.

Allograft or synthetic meniscal replacement has the potential to delay the arthritic sequelae of the meniscectomized knee. Meniscal implants must, however, be side and size specific. A cadaveric study was performed in which medial and lateral menisci were painted with a radiopaque tantalum powder-cyanoacrylic mixture. Radiographs of this preparation demonstrated reproducible relationships between each meniscus and established bony landmarks. When corrected for magnification, meniscal size could be derived from plain films. Meniscal width equaled the distance (coronal) from the peak of the tibial eminence to the periphery of the tibial metaphysis on anteroposterior films. Meniscal length was measured from lateral radiographs. Medial meniscal length was 80%, and lateral meniscal length was 70% of the measured sagittal length of the tibial plateau. Measurement error averaged 7.8% by these parameters.

Arthritis↗
PubMed1987

Inositol 1,4,5-trisphosphate-induced Ca2+ release from the sarcoplasmic reticulum and contraction in crustacean muscle.

Intracellular applications of a fixed amount (0.2 to 8 nmol) of inositol 1,4,5-trisphosphate (InsP3) over a brief period (2 s) into barnacle muscle fibers induced vigorous contractures. Peak tension attained during the first application depended on [InsP3]: the maximum tension evoked by the injection of 8 nmol was 1.6 kg/cm2. Peak tension during a second application of a high dose of InsP3 (greater than 10 microM) was always smaller than that during the first application. Extracellular Ca2+ could be omitted with no measurable effects on either the amplitude or time course of the contractures evoked by InsP3. Aequorin was used to measure InsP3-evoked Ca2+ release from intracellular stores in minced muscle fibers from lobster and in skinned muscle fibers from barnacle. Provided the sarcoplasmic reticulum was preloaded with Ca2+, application of InsP3 induced a transient Ca2+ release that was [InsP3] dependent. During each transient, [Ca2+] rose rapidly to a peak value (t1/2 less than 5 s) and then slowly returned (t1/2 less than 100 s) to a basal level. Maximum Ca2+ release was obtained at [InsP3] less than 100 microM and amounted to 4 nmol Ca2+/g of muscle, enough to increase [Ca2+]i from 0.1 to 8 microM had the Ca2+ release occurred in the intact fiber. Successive applications of a fixed amount of InsP3 elicited successive transient increases in Ca2+. The effects of [Ca2+] on the incorporation of [3H]inositol into the pools of phosphatidylinositol, phosphatidylinositol 4-phosphate, and phosphatidylinositol 4,5-bisphosphate pools were measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Musculoskeletal abnormalities in velocardiofacial syndrome.

This is the first case report detailing the musculoskeletal pathology and treatment ramifications associated with velocardiofacial syndrome. Orthopaedic manifestations include scoliosis, clubfoot, Sprengel's deformity, generalized ligamentous laxity that is especially problematic about the knee, and epiphyseal dysplasia that is most notable in the lateral humeral condyle, lateral femoral condyle, and femoral head.

Abnormalities, Multiple↗