Alteration of the patellar height following total knee arthroplasty.

INTRODUCTION: Patellofemoral related complications after total knee arthroplasty (TKA) remain clinically relevant. The hypothesis of the present study was that the patellar height changes more than 10% of its preoperative height after TKA. Possible influences of age, gender, side and navigation system on patellar height were evaluated separately in subgroups. MATERIALS AND METHODS: A total of 107 knees were enrolled after primary TKA. The patellar height was determined for each patient preoperatively, 1 week and 1 year postoperatively on routinely performed standing lateral view radiographs at 30° knee flexion. Insall-Salvati index (ISI), modified Insall-Salvati index (MIS) as well as Miura-Kawamura index (MKI) were determined for the whole cohort. RESULTS: One week after TKA the ISI, MIS and MKI changed by more than 10% in 24 (22%), 33 (30%) and 54 (50%) cases, respectively. Moreover, the 1 year follow-up revealed a decrease or increase of ISI in 30 (28%), MIS in 47 (44 %) and MK in 65 (61%) knees. The frequency of patella alta, norma and baja preoperatively as well as 1 week and 1 year postoperatively were not significantly different. Significant differences of patellar height changes were not noted between the defined subgroups. CONCLUSIONS: The present study demonstrates that TKA leads, at 1 week and 1 year follow-up, to patellar height alteration more than 10% in a significant number of knee joints. However, with the use of ISI and MIS the changes of patellar height did not exceed the defined thresholds to be classified as patella alta or baja.

Joint line changes after primary total knee arthroplasty: navigated versus non-navigated.

PURPOSE: Navigation has been introduced to achieve more accurate positioning of the implants after TKA. The scientific attention was mainly paid on limb alignment rather than restoration of the natural joint line. The aim of our study was to compare the accuracy of the joint line restoration in primary TKA with and without navigation. We hypothesized that joint line reconstruction in navigated TKA is more accurate. METHODS: A total of 493 primary TKAs operated in a single medical centre were consecutively selected and divided into two groups. 206 cases were performed computer assisted (BrainLab CI-System), whereas 287 knees were implanted conventionally. For both groups, the joint line position of the knee was determined on standardized calibrated standing pre- and postoperative digital radiographs in ap view by a modified method of Kawamura et al. A joint line shift of more than 8 mm was defined as outlier. RESULTS: In the conventional group, the joint line shift averaged 0.7 mm (±4.4 mm), whereas the findings in the computer-assisted cases were in average 0.6 mm (±4.5 mm). The joint line was located above 8 mm in 6 % of non-navigated versus 6.8 % of navigated primary TKAs. There were no statistically significant differences of joint line shift between the different component types. A statistically significant relation was not found between joint line shift and leg alignment changes. CONCLUSIONS: Conventional surgical technique allows a precise joint line reconstruction in primary TKA. Navigation did not improve the joint line reconstruction. LEVEL OF EVIDENCE: Diagnostic study, Level III.

Standardization of fetal ultrasound biometry measurements: improving the quality and consistency of measurements.

OBJECTIVE: To assess whether a standardization exercise prior to commencing a fetal growth study involving multiple sonographers can reduce interobserver variation. METHODS: In preparation for an international study assessing fetal growth, nine experienced sonographers from eight countries participated in a standardization exercise consisting of theoretical and practical sessions. Each performed a set of seven standard fetal measurements on pregnant volunteers at 20-37 weeks' gestation, and these were repeated by the lead sonographer; all measurements were taken in a blinded fashion. After this the sonographers had hands-on practice and feedback sessions on other volunteers. This process was repeated three times. Measurement differences between sonographers and the lead sonographer, expressed as a gestational-age-specific Z-score, between the first and third scans were compared using the Wilcoxon signed ranks test, and variance was assessed using Pitman's test. Interobserver agreement was also assessed using the intraclass correlation coefficient (ICC), and all images were scored for quality in a blinded fashion. RESULTS: At baseline the level of agreement and image scoring were high. A significant reduction in the differences between sonographers and the lead sonographer were seen for fetal biometry overall (head circumference, abdominal circumference and femur length) between the first and third scans (median Z-scores, 0.46 and 0.24; P = 0.005), and a reduction in the variance was also observed (P < 0.001). The ICCs for measurement pairs for every fetal measurement showed a clear trend of increasing ICC (better agreement) with consecutive training scan sessions, although no improvement in image scores was seen. CONCLUSION: Even for experienced sonographers, a standardization exercise before starting a study of fetal biometry can improve consistency of measurements. This could be of relevance for studies assessing fetal growth in multicenter sites.

The capsule quality of saline-filled smooth silicone, textured silicone, and polyurethane implants in rabbits: a long-term study.

Recently, there have been many new designs in both the surface texture and chemical composition of breast implants that claim reduced constrictive capsular formation. The purpose of this study was to utilize a quantitative method to determine the firmness of capsules formed around saline-filled smooth silicone, textured silicone, and polyurethane implants in an experimental rabbit model 1 year after implantation. Our objective was to analyze the histologic, biologic, and biochemical content of the respective capsules to account for any differences in physical behavior. Forty-five smooth silicone, textured silicone, and polyurethane implants were placed in one of three positions beneath the panniculus carnosus muscle of New Zealand White rabbits. After 1 year, all capsules were palpated and classified according to firmness. Intracapsular static and dynamic pressure measurements were obtained by placing a pressure monitor (Stryker) in an injector port attached to the individual implants. Capsular firmness was significantly greater in the textured silicone implants than in the smooth silicone or polyurethane implants after 1 year. The dynamic qualities of the periprosthetic soft tissues were measured while saline was injected into the implants. The capsules around the textured silicone implants generated significantly higher pressures than the smooth silicone or polyurethane counterparts. The capsules around the polyurethane implants were the softest and most compliant in all categories. Histologically, there is a significant inflammatory response surrounding the textured silicone implants that does not exist in the capsules around the smooth silicone implants. The capsules around the polyurethane implants have the least fibrous tissue deposition. There is a decrease in the proportion of type III collagen in the capsules around the textured silicone implants versus smooth silicone or polyurethane implants. The in vitro contraction patterns of the fibroblast-populated collagen lattices do not reveal the contraction differences observed in vivo in rabbits. However, there are many components that determine contractility. This area deserves further investigation.

Effects of macrophage colony stimulating factor and granulocyte-macrophage colony stimulating factor on osteoclastic differentiation of hematopoietic progenitor cells.

Although the hematopoietic origin of the osteoclast is generally accepted, the precise phenotype of the progenitor and the regulation of its differentiation are unclear. This study compares proliferation and differentiation of progenitors in response to macrophage colony stimulating factor (M-CSF) and granulocyte macrophage colony stimulating factor (GM-CSF). Nonadherent progenitor cells from murine long-term bone marrow cultures (LTBMC) (as a source of osteoclast progenitors) demonstrated a significant proliferative response to M-CSF. In addition, M-CSF increased the number of multinucleated cells, only a small percent of which (14-16%) were tartrate-resistant, acid phosphatase (TRAP)-positive. In contrast, cells cultured with GM-CSF generated more TRAP-positive multinucleated cells even at concentrations less stimulatory of proliferation than M-CSF. The osteoclast phenotype of these multinucleated cells was also assessed by ultrastructural characterization of ruffled borders in association with bone fragments. The bone-active hormone 1,25-dihydroxyvitamin D3 inhibited the proliferation of this subset of progenitor cells in the presence of M-CSF or GM-CSF. All of these results show effects on progenitors in the absence of the stromal cell microenvironment in this system. These results provide evidence for a divergence in the biological responsiveness of osteoclast progenitor cells to M-CSF compared with GM-CSF; they support the notion that M-CSF has a "priming" effect on osteoclast progenitors whose subsequent differentiation to osteoclastic multinucleated cells is promoted by GM-CSF.

Smooth versus textured expander implants: a double-blind study of capsule quality and discomfort in simultaneous bilateral breast reconstruction patients.

Textured silicone expanders are alleged to be less painful in the filling process, to have less capsular contracture, and to stay in position better than smooth silicone expanders. To test these three hypotheses, 6 patients undergoing bilateral simultaneous expander implant placement for breast reconstruction after mastectomy were studied. In a double-blind fashion, after smooth and textured implant placement (one in each side) and initial wound healing, each patient was sequentially expanded with equal volumes of saline. In each patient, at each expansion, pressure data, discomfort scores, and implant placement measurements were made. At implant removal, smooth and textured capsule tissues were studied for collagen type content and ability to contract the patient's own fibroblast-populated collagen lattice. In 4 of 6 patients the smooth expander was associated with lower injection pressures and less discomfort. In all patients the expanders maintained their position, except in 1 patient whose smooth implant shifted laterally. The capsular collagen typing and fibroblast-populated collagen lattice studies demonstrated no difference between smooth and textured capsules. In this double-blind clinical study in simultaneous bilateral breast reconstruction patients we could not confirm the suggestion that textured silicone expanders produce less capsular contracture and cause less pain with injection.