The effects of sequential sectioning of defined posterior cruciate ligament fiber regions on translational knee motion.

Background: Recent studies have shown that the posterior cruciate ligament (PCL) is composed of a continuum of fiber regions that display characteristic mechanical behavior under different motion and loading conditions.

Hypothesis: The anterior, central, and posterior fiber regions of the PCL differentially contribute to control of posterior translation of the tibia.

Study Design: Controlled laboratory study.

The effects of varied joint motion and loading conditions on posterior cruciate ligament fiber length behavior.

Background: The posterior cruciate ligament has been described as being composed of 2 bands that reciprocally tighten and loosen with knee flexion, but the fiber anatomy and behavior may be more complex.

Hypothesis: The mechanical effects of defined loading conditions at discrete knee joint angles can vary significantly within the substance of the posterior cruciate ligament depending on the fiber region tested.

Study Design: Controlled laboratory study.

Testing for isometry during reconstruction of the posterior cruciate ligament. Anatomic and biomechanical considerations.

The change in the distance of linear separation between each pair of osseous fiber attachment sites of the posterior cruciate ligaments was measured and plotted as a function of the knee flexion angle from 0 degree to 120 degrees. Data were collected under four sequential test conditions that had in common quadriceps relaxation, absence of tibial rotation forces, and horizontal femoral stabilization. The posterior cruciate ligament fibers were intact or transected (excursion wires left intact) with gravitational joint distraction of the lower leg unconstrained or constrained.

The effect of antecedent ischemia on the tolerance of skeletal muscle to increased interstitial pressure.

This study used an experimental model (canine hind limb) of compartment syndrome, monitored with phosphorus 31 nuclear magnetic resonance spectroscopy, to determine the pressure threshold for metabolic deterioration in skeletal muscle previously subjected to ischemia. Our results show that muscle subjected to 6 h of antecedent ischemia has a lower tolerance to increased tissue pressure than otherwise normal muscle. The threshold was found to occur at a delta P (difference between mean blood pressure and limb compartment pressure) of 40 mm Hg, compared with a delta P of 30 mm Hg in muscle that was not subjected to antecedent ischemia.

Magnetic resonance imaging of knee disorders. Clinical value and cost-effectiveness in a sports medicine practice.

To prospectively evaluate the clinical value of magnetic resonance imaging of the knee in a referral sports medicine practice, we performed a three-part study. First, we asked 72 consecutive patients a series of clinically relevant questions regarding the ordering of their magnetic resonance imaging scans. Second, we asked the treating physicians at our center if the magnetic resonance imaging findings changed the diagnosis or treatment.