Revision for instability has supplanted revision for aseptic loosening and revision for osteolysis since the advent of improved polyethylene inserts with changes in both sterilization techniques and cross-linking. Having the ability to judiciously choose a higher level of constraint may be beneficial in complex primary total knee arthroplasty (TKA) scenarios which can not be balanced through traditional surgical methods. The purpose of this work was to investigate short term outcomes and survivorship in cases where a greater stabilizing insert was used with a posterior stabalizing (PS) femur to address instability in flexion or extension. Two high volume TKA centers retrospectively reviewed cases in which a greater stabilizer insert was used with a primary PS knee system. The studied insert had +/− 2 degrees of varus-valgus coronal restraint as opposed the standard with no coronal constraint. The study inserts had 7 degrees of transverse plane rotational freedom. The inserts were used when extension balance was not achieved despite the usual soft tissue releases and a thicker insert resulted in a flexion contracture statically during the procedure. This situation typically occurred in the following patient groups: valgus knees with medial collateral (MCL) stretching, iatrogenic MCL injury, varus knees with lateral ligament complex stretching, the “double-varus” knee, and patients with a previous high tibial osteotomy. Intra-operatively patients were taken through a range of motion and trial implants were then placed. A cruciate retaining trial insert was then used to assess stability so that a true assessment could be made of ligament balance. Bone cuts were checked before ligament release. The usual releases were then performed to achieve balance including subperiosteal releases medially and laterally and pie-crusting when indicated. Repeat trial reductions were then performed once the final implants were cemented in place again using the cruciate retaining insert. If the soft tissue releases did not achieve balance and a thicker insert resulted in a flexion contracture then the greater stabilizer insert was selected over the PS insert. Knee Society Score and plain radiographs were collected at pre-op, 2 year and 5 year follow-up.Introduction
Methods
Acetabular revision surgery remains a technically demanding procedure with higher failure rates than primary total hip arthroplasty (THA). An acetabular component with three dimensional porous titanium and anatomic screw holes (Figure 1) was designed to allow the cup to be positioned anatomically and provide reliable fixation. A prospective multicenter study of 193 cases (190 patients) was conducted to assess the midterm clinical outcomes of the revision titanium acetabular shell. Radiographs, demographics, Harris Hip Score (HHS), and Short Form 36 (SF-36) were collected preoperatively, at 6 weeks, 3 months, and annually thereafter to 5 years. The mean duration of follow-up was 3.36 years. The Paprosky classification was assessed intraoperatively. Short Form 6D (SF-6D) utility values were obtained by transforming SF-36 scores through the Brazier method and were analyzed for effect size.Introduction
Methods
