Periprosthetic tissue metal content but not serum metal content predicts the type of tissue response in failed small-diameter metal-on-metal total hip arthroplasties.

Background: Tissue responses to periprosthetic metal wear debris are complex and poorly understood. There are two predominant tissue responses: a nonspecific macrophage-mediated granulomatous response and lymphocyte-dominated response, which has immunological memory and is mediated by T cells. Delayed hypersensitivity-type responses may accelerate aseptic loosening of arthroplasty implants.

Does ligament balancing technique affect kinematics in rotating platform, PCL retaining knee arthroplasties? A prospective randomized study.

The goal of this prospective, randomized, blinded trial was to determine if ligament balancing techniques for rotating platform TKA affect postoperative knee kinematics. Sixteen patients with unilateral rotating platform TKA consented to participate in this institutional review board approved study. Eight patients were randomly selected to receive ligament balancing with an instrumented joint spreader device and eight patients received ligament balancing using fixed thickness spacer blocks.

[Importance of blade geometry for stability of fixation with short intramedullary nailing systems for the proximal end of the femur (gliding nail)].

Three biomechanical examinations of the double-T blade of the gliding nail were performed. Under alternating load, also after 100,000 cycles and 2000 N load, no instability occurred after gliding nail osteosynthesis. The best relationship between the introduction forces of the blade (1.

Isometry of the posterior cruciate ligament. Effects of functional load and muscle force application.

The effects of functional load and muscle force application on isometry of the posterior cruciate ligament were determined. Eight fresh-frozen cadaver knees were mounted in a custom-designed rig. A full range of motion and muscle forces were applied through the quadriceps, hamstring, and gastrocnemius tendons during a simulated static squat maneuver.

Collagen shortening. An experimental approach with heat.

Decreasing joint laxity is a clinical goal of ligament reconstructions. This in vitro study examined the structural and histologic effects of heat shrinkage of human collagen. Two preliminary studies were performed to assess the effect of heat on fresh frozen human tendons obtained from a local tissue bank.

Surgical management of intra- and postoperative fractures of the femur about the tip of the stem in total hip arthroplasty.

Six techniques for the surgical management of fractures of the femur about the tip of the stem of a total hip arthroplasty were evaluated. Seven embalmed human femurs were prepared to receive the correct-size femoral component of a total hip system. A transverse osteotomy was performed at the level of the tip of the stem.

Reconstruction with tenodesis in an adult flatfoot model. A biomechanical evaluation of four methods.

Six fresh-frozen adult cadaveric specimens were mounted in an Instron materials testing machine with use of a cemented intramedullary rod. Angular relationships between the first metatarsal and the talus were recorded with a sonic digitizer. A flatfoot deformity was created by dividing the talonavicular joint capsule (superiorly, medially, and inferiorly), the spring ligament, the anteromedial aspect of the subtalar joint capsule, and the plantar fascia.

Dynamic support of the human longitudinal arch. A biomechanical evaluation.

This study was designed to evaluate the dynamic support provided to the human longitudinal arch by the leg muscles active in the stance phase of gait and by the plantar aponeurosis. Ten fresh adult cadaveric specimens were mounted in a materials testing machine. The tendons of the posterior tibialis, flexor digitorum longus, flexor hallucis longus, peroneus longus, peroneus brevis, and Achilles tendon were attached to force transducers.

Translation of the glenohumeral joint with simulated active elevation.

Translation of the glenohumeral joint was measured with a dynamic shoulder model during elevation of the arm in 8 cadaveric specimens. Controlled hydrodynamic actuator forces were applied to the deltoid muscle and the rotator cuff through wire cables. Using a constant force ratio, the glenohumeral joint was elevated to 90 degrees.

Corneal tensile strength in fully healed radial keratotomy wounds.

Purpose: To investigate the susceptibility to rupture of a human donor cornea with fully healed radial keratotomy (RK) incisions using biomechanical measurement methods and finite element analysis.

Methods: A human cornea 8 years after RK was cut into four strips and subjected to tensile testing until rupture occurred. The fellow cornea was pressurized on an artificial anterior chamber beyond the initiation of wound gape.

A comparison of various loading configurations of the proximal femur for the evaluation of reconstructive surgical procedures.

The study was designed to evaluate the effect of different loading configurations on stem and bone stresses in simulated total hip arthroplasty. The traditional experiment design of loading the model through the head of the prosthesis by the resultant joint force was compared with a more realistic model which included an abductor strap to simulate the abductor muscle force. In addition, an alternative experiment design was evaluated in which a loading arm was clamped directly on to the head of the prosthesis.