title: Torsional stability of uncemented femoral stems in oncologic reconstructions.
abstract: Modular oncology implants using uncemented fixation represent a popular reconstruction technique for limb salvage patients. Initial stability is critical to facilitate bony ingrowth of host bone into the stem of a press-fit oncologic modular rotating-hinge total knee arthroplasty (TKA). The impact of stem design on initial stability has not been defined. The goal of this study was to evaluate the initial stability of 3 different stem designs as defined by torsional load to failure. An analysis of imaging was also performed. The pilot study consisted of 5 femora in each of 3 groups based on stem design. The specimen was mounted on a multi-axis biomechanical test frame equipped with a Vicon 3D motion analysis 4-camera system (Vicon Motion Systems, Lake Forest, California) to track the relative motion between the implant and the femur. Torsional force was applied until failure. The straight-fluted stem design had the highest average torsional stiffness (18.3±8.2 Nm/deg) and average torque at 150 μm of implant micromotion (23.2±10.6 Nm) of the 3 stem types tested.The results of this study will help to guide surgical decision making in limb salvage cases. Further investigation is warranted.
authors.affiliation: Department of Orthopedics, The Arthur James Cancer Hospital at The Ohio State University, Columbus, OH 43210, USA. thomas.scharschmidt@osumc.edu
authors.forename: Tom
authors.initials: T
authors.lastname: Scharschmidt
authors.forename: Amy
authors.initials: A
authors.lastname: Cohen
authors.forename: Noelle
authors.initials: N
authors.lastname: Thomas
authors.forename: Randal
authors.initials: R
authors.lastname: Ching
authors.forename: Ernest
authors.initials: E
authors.lastname: Conrad
mesh_terms: D000368:Aged; D002484:Cementation; D019544:Equipment Failure Analysis; D005260:Female; D005266:Femoral Neoplasms / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011474:Prosthesis Design; D019415:Torque; D016896:Treatment Outcome