Designing a Rational Follow-Up Schedule for Patients with Extremity Soft Tissue Sarcoma.

Purpose: The risk of tumor recurrence after resection of soft tissue sarcoma (STS) necessitates surveillance in follow-up. The objective of this study was to determine the frequency/timing of metastasis and local recurrence following treatment for soft tissue sarcoma, and to use these data to justify an evidence-based follow-up schedule.

Methods: Utilizing a prospective database, a retrospective single center review was performed of all patients with minimum 2-year follow-up after resection of a localized extremity STS.

Validation of three-dimensional models of the distal femur created from surgical navigation point cloud data for intraoperative and postoperative analysis of total knee arthroplasty.

Purpose: Despite the success of total knee arthroplasty, there continues to be a significant proportion of patients who are dissatisfied. One explanation may be a shape mismatch between pre- and postoperative distal femurs. The purpose of this study was to investigate methods suitable for matching a statistical shape model (SSM) to intraoperatively acquired point cloud data from a surgical navigation system and to validate these against the preoperative magnetic resonance imaging (MRI) data from the same patients.

Changes in the functional flexion axis of the knee before and after total knee arthroplasty using a navigation system.

Long term satisfaction of patients with total knee arthroplasty (TKA) has lagged behind that of total hip arthroplasty. One possible reason is the failure of the artificial joint to recreate natural kinematics of the knee. This study evaluated the pre and post implant functional flexion axis in the knees of 285 total knee arthroplasty patients using a surgical navigation system.

Pre-operative muscle activation patterns during walking are associated with TKA tibial implant migration.

Background: Gait biomechanical variables have been associated with total knee arthroplasty tibial implant migration measured with Radiostereometric Analysis (RSA), but no studies have examined the role of the periarticular musculature, which is responsible for a high proportion of the forces on the joint. The purpose of this study was to measure the pre-operative electromyography (EMG) patterns of the periarticular knee muscles during gait and determine the association of these patterns with the post-operative tibial implant migration measured with RSA. We hypothesized that pre-operative muscle activation patterns (specifically the activation patterns of the vastus and gastrocnemius muscle groups) measured with EMG are associated with migration at 6months.

The knee adduction moment during gait is associated with the adduction angle measured during computer-assisted total knee arthroplasty.

Computer-assisted surgery can be used to measure 3-dimensional knee function during arthroplasty surgery; however, it is unknown if the movement of the knee measured during surgery is related to the in vitro, dynamic state of the knee joint, specifically the knee adduction moment during gait, which has been related to implant migration. The purpose of this study was to determine if the preoperative adduction moment is correlated with the knee abduction/adduction angle measured intraoperatively. A statistically significant correlation was found between the mean (r(2) = 0.

Continued stabilization of trabecular metal tibial monoblock total knee arthroplasty components at 5 years-measured with radiostereometric analysis.

Background And Purpose: The trabecular metal tibial monoblock component (TM) is a relatively new option available for total knee arthroplasty. We have previously reported a large degree of early migration of the trabecular metal component in a subset of patients. These implants all appeared to stabilize at 2 years.

Early failure of a polyethylene acetabular liner cemented into a metal cup.

In 2002, a patient underwent revision total hip arthroplasty for polyethylene wear. The acetabular cup was well fixed, and it was decided to cement a new polyethylene liner into the existing cup. In 2006, the patient presented with inability to weight bear and easy subluxation of the hip.

Preoperative gait patterns and BMI are associated with tibial component migration.

Background And Purpose: There is no standard for patient triage in total knee arthroplasty (TKA) based on joint functional characteristics. This is largely due to the lack of objective postoperative measurement of success in TKA in terms of function and longevity, and the lack of knowledge of preoperative metrics that influence outcome. We examined the association between the preoperative mechanical environment of the patients knee joint during gait and the post-TKA stability of the tibial component as measured with radiostereometric analysis (RSA).

Inducible displacement of a trabecular metal tibial monoblock component.

Radiostereometric analysis is a highly accurate technique that can be used for measuring micromotion at the bone-implant interface. The purpose of this study was to compare the inducible displacement of the uncemented Trabecular Metal (TM; Zimmer, Warsaw, Ind) tibial monoblock component with that of a cemented implant. Inducible displacement of 14 uncemented TM components and 11 cemented components was measured 24 to 48 months postoperatively.