Cementless Tapered Wedge Femoral Stems Decrease Subsidence in Obese Patients Compared to Traditional Fit-and-Fill Stems.

BACKGROUND: Femoral component stability and resistance to subsidence is critical for osseointegration and clinical success in cementless total hip arthroplasty. The purpose of this study was to radiographically evaluate the anatomic fit and subsidence of 2 different proximally tapered, porous-coated modern cementless femoral component designs. METHODS: A retrospective cohort study of 126 consecutive cementless total hip arthroplasties was performed. Traditional fit-and-fill stems were implanted in the first 61 hips with the remaining 65 receiving morphometric tapered wedge stems. Preoperative bone morphology was radiographically assessed by the canal flare index. Canal fill in the coronal plane, subsidence, and the sagittal alignment of stems was measured digitally on immediate and 1-month postoperative radiographs. RESULTS: Demographics and canal flare indices were similar between groups. The percentage of femoral canal fill was greater in the tapered wedge compared to the fit-and-fill stem (P = .001). There was significantly less subsidence in the tapered wedge design (0.3 mm) compared to the fit-and-fill design (1.1 mm) (P = .001). Subsidence significantly increased as body mass index (BMI) increased in the fit-and-fill stems, a finding not observed in the tapered wedge design (P = .013). CONCLUSION: An anatomically designed morphometric tapered wedge femoral stem demonstrated greater axial stability and decreased subsidence with increasing BMI than a traditional fit-and-fill stem. The resistance to subsidence, irrespective of BMI, is likely due to the inherent axial stability of a tapered wedge design and may be the optimal stem design for obese patients.

Modern abbreviated computer navigation of the femur reduces blood loss in total knee arthroplasty.

Computer assisted surgery (CAS) optimizes component position in total knee arthroplasty (TKA), yet effects specifically on blood loss are less known. This study purpose was to determine whether a modern abbreviated CAS protocol would reduce blood loss in TKA compared to conventional instrumentation. One hundred consecutive TKAs were retrospectively reviewed comparing abbreviated CAS versus conventional IM instrumentation. Blood loss was determined using drain output, change in hemoglobin, and calculated blood loss. The CAS group demonstrated less hourly drain output (P=0.02), hemoglobin change (P=0.001), and estimated blood loss (P=0.001) versus conventional instrumentation. With proven advantages of accurate component placement and improved functional outcome after TKA, CAS provides additional value by reducing blood loss in TKA.

The use of exparel (liposomal bupivacaine) to manage postoperative pain in unilateral total knee arthroplasty patients.

Efforts continue to improve pain after total knee arthroplasty (TKA) in order to allow for accelerated rehabilitation. The purpose of this study was to evaluate pain control after TKA. A randomized prospective study of 80 consecutive patients was performed comparing Exparel versus femoral nerve block (FNB). Inpatient pain control was the primary outcome. Secondary outcome measures included ROM (extension and flexion), nausea and vomiting, narcotic consumption, ambulation distance, and length of stay (LOS). There were no statistically significant differences between the groups with regard to pain, nausea and vomiting, and narcotic consumption. The FNB group had greater flexion but the Exparel group had improved early ambulation and decreased LOS. Exparel provided similar pain relief to a FNB after TKA without compromising early rehabilitation.

High CD49f expression is associated with osteosarcoma tumor progression: a study using patient-derived primary cell cultures.

Overall prognosis for osteosarcoma (OS) is poor despite aggressive treatment options. Limited access to primary tumors, technical challenges in processing OS tissues, and the lack of well-characterized primary cell cultures has hindered our ability to fully understand the properties of OS tumor initiation and progression. In this study, we have isolated and characterized cell cultures derived from four central high-grade human OS samples. Furthermore, we used the cell cultures to study the role of CD49f in OS progression. Recent studies have implicated CD49f in stemness and multipotency of both cancer stem cells and mesenchymal stem cells. Therefore, we investigated the role of CD49f in osteosarcomagenesis. First, single cell suspensions of tumor biopsies were subcultured and characterized for cell surface marker expression. Next, we characterized the growth and differentiation properties, sensitivity to chemotherapy drugs, and anchorage-independent growth. Xenograft assays showed that cell populations expressing CD49f(hi) /CD90(lo) cell phenotype produced an aggressive tumor. Multiple lines of evidence demonstrated that inhibiting CD49f decreased the tumor-forming ability. Furthermore, the CD49f(hi) /CD90(lo) cell population is generating more aggressive OS tumor growth and indicating this cell surface marker could be a potential candidate for the isolation of an aggressive cell type in OSs.

Comparison of limb-length discrepancy after THA: with and without computer navigation.

Limb-length discrepancy following total hip arthroplasty (THA) is often cited as a reason for patient dissatisfaction and for hip instability. Various intraoperative techniques have been described to help restore normal limb length after THA. The purpose of this study was to assess whether a computer-navigated surgical technique would help restore limb-length equality following THA.A retrospective study of 150 consecutive patients compared a free-hand (non-navigated) THA technique vs a computer-navigated THA technique. Each group contained 75 patients. The primary outcome measurement was limb-length discrepancy, which was evaluated using a digital anteroposterior pelvic radiograph. Secondary outcome measurements included a Harris Hip Score questionnaire and a single question evaluating the subjective feeling of the operative limb (longer, shorter, or equal). At a minimum 1-year follow-up, results showed that computer-navigated THA helped restore limb-length equality. An average leg-length difference of 0.3 mm (SD=0.3 mm) was found with computer-navigated THA compared with a leg-length difference of 1.8 mm (SD=0.7 mm) when a non-navigated THA was used. This was statistically significant. Both groups had similar Harris Hip Scores (computer-navigated group, 84.8; non-navigated group, 84.2; P=.835), and no difference was found between the 2 groups regarding the patient's perception of the operative limb length.This study demonstrated that computer-navigated THA resulted in improved restoration of normal limb length and limited significant outliers but did not show improvement in Harris Hip Scores or patient's perception of limb-length equality.