Femoral and tibial insert downsizing increases the laxity envelope in TKA.

Purpose: This study examines the effect of component downsizing in a modern total knee arthroplasty (TKA) system on the laxity envelope of the knee throughout flexion.

Methods: A robotic testing system was utilized to measure laxity envelopes in the implanted knee by in the anterior-posterior (AP), medial-lateral (ML), internal-external (IE) and varus-valgus (VV) directions. Five fresh-frozen cadavers were tested with a modern cruciate retaining TKA implantation, a 1-mm thinner polyethylene insert and a femoral component 2 mm smaller in the AP dimension.

Simulation of altered excursion of the pronator quadratus.

Background Loss of forearm rotation is frequently seen after healing of distal radius fractures. Questions/Purposes Our purpose was to determine whether restricted excursion of the pronator quadratus muscle can affect forearm rotation. Methods We evaluated the relationship between pronator quadratus excursion and forearm rotation in a cadaveric model.

Biomechanical Test of Three Methods to Treat Thumb CMC Arthritis.

Background Basilar thumb arthritis, or first carpometacarpal arthritis, is a common condition, predominantly affecting women. Surgical treatment of this condition is highly varied. One common method consists of trapezium excision and a concomitant procedure for treatment of the "floating" thumb metacarpal.

The role of the oblique popliteal ligament and other structures in preventing knee hyperextension.

Background: Ligament restraints to terminal knee extension are poorly understood.

Hypotheses: (1) As with other motions of the knee, genu recurvatum is limited primarily by a named, identifiable structure. (2) As the largest static structure of the posterior knee, the oblique popliteal ligament is uniquely suited to act as a checkrein to knee hyperextension.

The effect of a proximal tibial medial opening wedge osteotomy on posterolateral knee instability: a biomechanical study.

Background: Increased stability of posterolateral corner knee injuries has been observed clinically after proximal tibial medial opening wedge osteotomies.

Hypothesis: Static varus and external rotatory stability will be significantly improved in a knee with a grade 3 posterolateral knee injury after a proximal tibial medial opening wedge osteotomy.

Study Design: Controlled laboratory study.