Comparison of Conventional Technique with Suture Fixation and Subperiosteal Tight Pocket Technique on Revision Cochlear Implantation Rate.

Several fixation methods have been described to secure the cochlear implant's receiver/stimulator, but the optimal stabilization technique is still being debated. The aim of this study was to compare the conventional technique with suture fixation to the subperiosteal tight pocket technique in terms of revision cochlear implantation rate. A retrospective review was conducted on the medical records of 649 patients who underwent cochlear implantation. The study participants were divided into different groups regarding the applied surgery technique. The relationship between the fixation technique, revision rates, and the cause of revisions related to techniques was investigated. The overall revision rate was 2.9% (19 out of 649). There were 14 (3.5%) and 5 (2%) revision implantations in the subperiosteal tight pocket and conventional technique groups, respectively. The incidence of device failure was 2.5%, and it constituted the primary cause for revision surgery in both groups. Even though patients who had the subperiosteal tight pocket technique had a much higher rate of device failure, the results indicate that there was no significant difference between the groups, as evidenced by a P-value of .12. The conventional and subperiosteal tight pocket techniques can both be safely preferred with low revision rates in patients undergoing cochlear implantation.

Total Transcanal Endoscopic Ear Surgery for Cholesteatoma.

Objective: This study aimed to evaluate the outcomes of total transcanal endoscopic cholesteatoma surgery. Methods: Twenty-seven cholesteatoma patients that had undergone transcanal endoscopic ear surgery (TEES) were included in the study. Age, sex, operation date of patients, operated side, need for ossiculoplasty, graft material, and surgical technique were recorded. All patients were evaluated through otoscopic, endoscopic, and audiological examinations and followed up for at least five months after surgery. All patients were staged using the European Academy of Otology and Neurotology/Japan Otological Society (EAONO/JOS) Staging System on Middle Ear Cholesteatoma. Results: Mean age of the patients was 36.4 years (range, 4-67 years). According to the EAONO/JOS Staging System, 11 patients were stage 1, while 11 were stage 2, and five were stage 3. Two had lateral semicircular canal defect, one had facial canal dehiscence, and one had oval window defect. The average follow-up period was 19 months (range, 5-41 months), during which two patients experienced retraction pocket and hearing loss and one patient had perforation. One patient underwent revision surgery during follow-up and no recurrence or residual cholesteatoma was observed. The preoperative and postoperative air-bone gaps were 25.14±13.93 dB and 22.22±12.64 dB with no significant difference. Conclusion: TEES is a minimally invasive and safe procedure with low complication and recurrence rates. As with all surgical procedures, experience is essential, and as experience increases, the capability to perform endoscopic otologic surgery on more complex cases may become possible.

The effect of perioperative immunonutritional support on nutritional and inflammatory status in patients undergoing lung cancer surgery: a prospective, randomized controlled study.

PURPOSE: Nutritional status is affected in patients who undergo lung cancer surgery (LCS). This study is aimed at investigating the effects of the use of immunonutritional support in the perioperative period on nutritional and inflammatory status in patients undergoing LCS. METHODS: A single-center, prospective, randomized controlled clinical trial was conducted with seventy patients planning to have LCS and randomized into treatment (TG) and control groups (CG). Immunonutritional support was given orally twice a day for ten days before the operation and five days after the operation in the treatment group. The nutritional status of the patients was screened with the Patient-Generated Subjective Global Assessment (PG-SGA); the Prognostic Nutrition Index (PNI) and the Systemic Inflammation Index (SII) were calculated. The physical activity status was assessed with the Eastern Cooperative Oncology Group Performance Status (ECOG-PS). RESULTS: Post-op nutritional status of the TG patients was better than the CG group (p = 0.009). Post-operative PG-SGA score was higher than preoperative PG-SGA score in both groups (p < 0.001). In the post-operative period, nutritional status (in terms of PG-SGA score category) in the patients in the TG was better than the CG (p = 0.046). In both groups, post-op ECOG score was higher than the pre-op ECOG score (p < 0.001). Post-op physical performance status was found to be better in the TG compared to the CG (p = 0.001). PNI level decreased statistically and significantly in the post-op period compared to the pre-op period, SII levels increased. CONCLUSION: Patients who will undergo LCS should be supported in terms of immunonutrition starting from the preoperative period.

Turkish Guideline for Diagnosis and Treatment of Allergic Rhinitis (ART).

OBJECT: To prepare a national guideline for Otorhinolaryngologist who treat allergic rhinitis patients. METHODS: The study was conducted by three authors, namely the writing support team. The support team made the study plan, determined the writing instructions, chose the subgroups including the advisory committee, the advisors for authors and the authors. A workshop was organized at the very beginning to explain the details of the study to the team. Advisors took the chance to meet their coworkers in their subgroups and determined the main headings and subheadings of the guideline, together with the authors. After key words were determined by the authors, literature search was done in various databases. The authors keep in touch with the advisors and the advisors with the advisory committee and the support group at every stage of the study. National and International published articles as well as the abstracts of unpublished studies, imperatively presented in National Congresses, were included in this guideline. Only Guideline and meta-analyses published in last seven years (2013-2017) and randomized controlled studies published in last two years (2015-2017) were included. After all work was completed by the subgroups, support team brought all work together and edited the article. RESULTS: A detailed guideline about all aspects of allergic rhinitis was created. CONCLUSION: The authors believe that this guideline will enable a compact and up-to-date information on allergic rhinitis to healthcare professionals. This guideline is the first in the field of Otolaryngology in Turkey. It should be updated at regular intervals.

Audiological Results of Total Ossicular Replacement Prosthesis with Cartilage Shoe Technique.

OBJECTIVE: The aim of this study was to investigate functional results of total ossicular replacement prosthesis (TORP) shaft stabilization with a cartilage shoe in chronic otitis media patients with cholesteatoma who had undergone canal wall down tympanomastoidectomy (CWDT). In addition, it was determined whether the presence of granular and edematous mucosa in middle ear altered functional outcomes. METHODS: Sixty patients, who had undergone CWDT with the use of TORP for the reconstruction of ossicular chain, were divided into two groups. Patients with cartilage shoe were classified as Group 1 (n=30) and those without the shoe were classified as Group 2 (n=30). Patients in both groups were classified into "A" and "B" subgroups according to the middle ear risk index (MERI). Air conduction (AC) and bone conduction thresholds were evaluated preoperatively and postoperatively. RESULTS: There was no statistically significant change between preoperative AC thresholds of the groups and subgroups (p>0.05). There were statistically significant differences regarding AC thresholds and air-bone gap (ABG) values between Groups 1 and 2 at the postoperative 12th month (p<0.05). Postoperative AC thresholds and ABG values of Group 1B patients with a high MERI score were statistically significant at all frequencies than those of Group 2B patients (p<0.05). When ABG values were compared, it was observed that functional results were better in Group 1B, but a statistically significant difference was observed only at 2000 Hz (p<0.01). CONCLUSION: The cartilage shoe method for titanium TORP stabilization that is used for ossicular reconstruction during CWDT has been found to have a beneficial effect on auditory outcomes. Cartilage shoe application increases positive effects on hearing outcomes, particularly if the middle ear mucosa is granular and edematous.

[Extranasal glioma surgery in a newborn: a case report]. / Yenidoganda ekstranazal gliom cerrahisi: Olgu sunumu.

Nasal gliomas are rarely seen, congenital, benign and nonhereditary lesions. These are not true tumors that occur due to extradural malposition of ectopic glial tissue during embryologic development. These are generally diagnosed during childbirth and may have an intracranial extension with fibrous stalk. Treatment of these masses that cause nasal obstruction and cosmetic deformity according to location, is total excision. In this case report, we present an extranasal glioma case whose surgery was done when she was 11 days old. Nasal gliomas are congenital midline lesions in the newborn period and it is necessary to be careful in differential diagnosis and during surgery due to possible intracranial extension.

Comparative Fixation and Subsidence Profiles of Cementless Unicompartmental Knee Arthroplasty Implants.

BACKGROUND: Aseptic loosening is the primary cause of failure for both cemented and cementless unicondylar knee replacements (UKRs). Micromotion and subsidence of tibial baseplate are two causes of failure, due to poor fixation and misalignment, respectively. METHODS: Stair ascent activity profiles from Bergmann et al and Li et al were used. Biphasic Sawbones models were prepared according to the surgical techniques of traditional and novel cementless UKRs. Implants were tested for 10,000 cycles representing post-operative bone interdigitation period, and micromotion was observed using speckle pattern measurements, which demonstrated sufficient resolution. Additionally, the test method proposed by Liddle et al was used to measure subsidence with pressure sensors under increasingly lateralized loading. RESULTS: Mean displacement due to micromotion for mediolateral and anteroposterior plane was consistently greater for traditional cementless UKR. Mean displacement for axial micromotion was significantly higher for traditional UKR at the anterior aspect of the implant; however, values were lower for the medial periphery of the implant. Subsidence was significantly lower for the novel design with increasingly lateralized loading, and indentation was not observed on the test substrate, when compared to the traditional design. CONCLUSION: Our findings demonstrate that the novel cementless design is capable of fixation and elimination of subsidence in laboratory test settings. Both designs limit micromotion to below the established loosening micromotion value of 150 µm. The L-shaped keel design resists both micromotion and subsidence and may prevent failure modes that can lead to aseptic loosening for UKRs. These findings are highly relevant for clinical application.

The Regulation of Matrix Metalloproteinase Expression and the Role of Discoidin Domain Receptor 1/2 Signalling in Zoledronate-treated PC3 Cells.

Discoidin Domain Receptors (DDR1/DDR2) are tyrosine kinase receptors which are activated by collagen. DDR signalling regulates cell migration, proliferation, apoptosis and matrix metalloproteinase (MMP) production. MMPs degrade extracellular matrix (ECM) and play essential role in tumor growth, invasion and metastasis. Nitrogen-containing bisphosphonates (N-BPs) which strongly inhibit osteoclastic activity are commonly used for osteoporosis treatment. They also have MMP inhibitory effect. In this study, we aimed to investigate the effects of zoledronate in PC3 cells and the possible role of DDR signalling and downstream pathways in these inhibitory effects. We studied messenger RNA (mRNA) and protein expressions of MMP-2,-9,-8, DDR1/DDR2 type I procollagen (TIP) and mRNA levels of PCA-1, MMP-13 and DDR-initiated signalling pathway players including K-Ras oncogene, ERK1, JNK1, p38, AKT-1 and BCLX in PC3 cells in the presence or absence of zoledronate (10-100 µM) for 2-3 days. Zoledronate (100 µM) down-regulated DDR1/ DDR2, TIP mRNAs but did not change MMP-13 (collagenase-3) mRNA. However, zoledronate up-regulated MMP-8 (collagenase-2) mRNA. Zoledronate also inhibited mRNA expressions of K-Ras, ERK1, AKT-1, BCLX and PCA-1; but did not change JNK1, p38 mRNA levels. Zoledronate (100 µM) supressed DDR1/DDR2, TIP expressions; and gelatinase (MMP-2/MMP-9) expressions/activities. Conversely, zoledronate up-regulated MMP-8 expression in PC3 cells. Zoledronate down-regulates MMP-2/-9 expressions in PC3 prostate cancer cells. DDR1/DDR2 signalling and DDR-initiated downstream Ras/Raf/ERK and PI3K/AKT pathways may at least partially responsible for MMP inhibitory effect of zoledronate.

Atrophic rhinitis caused by Cedecea davisae with accompanying mucocele.

Atrophic rhinitis is a chronic inflammatory disease characterized by progressive atrophy of nasal mucosa. Cedecea davisae, a rare pathogen, is a new member of Enterobacteriaceae family. In this article, we report a patient with atrophic rhinitis whose culture test revealed Cedecea davisae. The patient was operated due to accompanying posterior ethmoid mucocele. Levofloxacin and nasal irrigation were administered for two months. Significant improvement was observed in patient's complaints and nasal signs at postoperative sixth month. In conclusion, Cedecea davisae has been thought to cause atrophic rhinitis and mucocele in this patient. Patient recovered with simple treatment. These bacteria should be kept in mind as a causative agent for atrophic rhinitis.

Biochemical markers of glucose metabolism may be used to estimate the degree and progression of iron overload in the liver and pancreas of patients with ß-thalassemia major.

The use of cardiac and hepatic T2* MRI measurements to predict the amount of iron accumulation in these organs has been studied extensively and was suggested to be used reliably. However, it may not be practical to screen other organs with MRI related to economical issues and also the prolonged imaging durations. Herein, we aimed to test the use of fasting glucose, fasting, and postprandial insulin, homeostasis model assessment-insulin resistance (HOMA-IR) (calculated as insulin (µIU/ml) × glucose (mg/dl)/22.5), and homeostasis model assessment B score (HOMA-B) (calculated as insulin (µIU/ml) × 20/glucose (mg/dl) - 3.5) to estimate the tissue iron measured with MRI. A total of 37 patients with ß-thalassemia major (BTM), age 20.8 ± 6.3 years (7.1-36.8), were enrolled. MRI measurements were done concomitantly to the biochemical tests for glucose metabolism. A positive correlation between HOMA-IR and hepatic iron loading and a negative correlation between pancreatic T2* and fasting blood glucose were found. A positive correlation was found between fasting insulin levels and pancreatic R2* measures. Additionally, a correlation was detected between cardiac and pancreatic iron accumulations. In centers where T2*/R2* MRI facilities are unavailable, fasting insulin, fasting glucose, and HOMA-IR measurements may be used to predict iron overload and may urge the physician for MRI assessment in case of a deterioration in these biochemical tests. Since hepatic iron loading correlated with insulin resistance development, the insulin resistance among patients with BTM may partially be explained with decreased hepatic insulin clearance from heavily iron-loaded liver.

Analysis of tumor necrosis factor α-induced and nuclear factor κB-silenced LNCaP prostate cancer cells by RT-qPCR.

Prostate cancer is the second leading cause of morbidity and mortality in males in the Western world. In the present study, LNCaP, which is an androgen receptor-positive and androgen-responsive prostate cancer cell line derived from lymph node metastasis, and DU145, which is an androgen receptor-negative prostate cancer cell line derived from brain metastasis, were investigated. TNFα treatment decreased p105 and p50 expression and R1881 treatment slightly decreased p105 expression but increased p50 expression with or without TNFα induction. As an aggressive prostate cancer cell line, DU145 transfected with six transmembrane protein of prostate (STAMP)1 or STAMP2 was also exposed to TNFα. Western blotting indicated that transfection with either STAMP gene caused a significant increase in NFκB expression following TNFα induction. In addition, following the treatment of LNCaP cells with TNFα, reverse transcription quantitative polymerase chain reaction (RT-qPCR) was performed with a panel of apoptosis-related gene primers. The apoptosis-related genes p53, p73, caspase 7 and caspase 9 showed statistically significant increases in expression levels while the expression levels of MDM2 and STAMP1 decreased following TNFα induction. Furthermore, LNCaP cells were transfected with a small interfering NFκB (siNFκB) construct for 1 and 4 days and induced with TNFα for the final 24 h. RT-qPCR amplifications were performed with apoptosis-related gene primers, including p53, caspases and STAMPs. However, no changes in the level of STAMP2 were observed between cells in the presence or absence of TNFα induction or between those transfected or not transfected with siNFκB; however, the level of STAMP1 was significantly decreased by TNFα induction, and significantly increased with siNFκB transfection. Silencing of the survival gene NFκB caused anti-apoptotic STAMP1 expression to increase, which repressed p53, together with MDM2. NFκB silencing had varying effects on a panel of cancer regulatory genes. Therefore, the effective inhibition of NFκB may be critical in providing a targeted pathway for prostate cancer prevention.

[Peripheral ossifying fibroma of maxilla]. / Üst çenede periferik ossifiye fibrom.

Peripheral ossifying fibromas are rare pathologies characterized by the replacement of bone to fibrous tissue. In this article, we report a 64-year-old female case admitted to our clinic with a mass in the oral cavity for 10 years. On physical examination, a 5x4 cm, well-defined, pedunculated mass was detected in the anterior arch of the right maxilla. Based on the clinical, radiographic and histopathological findings, the mass was diagnosed as an ossifying fibroma.

Number of erythrocyte transfusions is more predictive than serum ferritin in estimation of cardiac iron loading in pediatric patients with acute lymphoblastic leukemia.

BACKGROUND: Transfusions with packed erythrocytes is a common practice in pediatric patients with acute lymphoblastic leukemia (ALL) who are on chemotherapy. Since there is no physiological excretion mechanism for iron, the iron related to erythrocyte transfusions accumulates and may contribute to late cardiac, hepatic and endocrine complications in these patients. PROCEDURE: In order to evaluate the iron burden among pediatric patients with ALL and define the risk factors associated with higher iron loading, we evaluated 79 pediatric patients with ALL (36 were off-therapy). Cardiac and hepatic T2* were ordered to a total of 22 (28%) patients who were either transfused with erythrocytes ≥ 10 times (n=11; 50%), had serum ferritin (SF) ≥ 1000 ng/ml (n=2; 9.1%) or both (n=9; 40.9%). RESULTS: Half of the patients who were screened by T2* MRI had hepatic T2*<7 ms and six (27%) of the patients had cardiac T2*<20 ms, indicating iron loading. Patients who had serum ferritin <1000 vs ≥ 1000 ng/ml had median cardiac T2* values of 28.3 ms (15-40) vs 21 (7.9-36), (p=0.324); whereas hepatic T2* of 10.8 (5.32-27) vs 4.7 (2.2-36), (p=0.017). Patients who had erythrocyte transfusion <10 vs ≥ 10 times had median cardiac T2* values of 34 ms (28-38) vs 23 (7.93-40), (p=0.021); whereas hepatic T2* of 13.6 (6.6-36) vs 5.32 (2.2-27), (p=0.046). CONCLUSIONS: Our results indicate that pediatric patients with ALL should be screened for transfusional iron load and the amount of erythrocyte transfusions seems to be a more reliable indication than serum ferritin levels to detect cardiac iron loading in these patients.

Introducing basic molecular biology to Turkish rural and urban primary school children via hands-on PCR and gel electrophoresis activities.

This study includes the results of a 2-day education project titled "Molecular Biology Laboratory Summer School, MoBiLYO." The project was held at a University Research Center by scientists from Department of Pharmacology and graduate students. The project was composed of introductory lectures, model construction, DNA isolation, polymerase chain reaction (PCR), and gel electrophoresis. The participants were 13-year-old eighth-graders attending primary schools affiliated with Ministry of National Education in urban and rural areas of Izmir, Turkey. The purpose of this study was to introduce basic molecular biology concepts through individually performed experiments such as PCR and gel electrophoresis integrated with creative drama. The students were assessed at the beginning and the end of each project day via mini-tests, experimental and presentation skills evaluation forms. Data showed that students' knowledge about DNA structure and basic molecular biology techniques significantly increased. On the basis of experimental and presentational skills, there was no significant difference between kids from urban and rural schools or between public and boarding public schools, whereas the average score of girls was significantly higher than that of boys. In conclusion, individually performed experiments integrated with creative drama significantly increased students' perception of complex experimental procedures on basic molecular biology concepts. Data suggests that integration of these concepts into the science and technology curriculum of Turkish primary education may support the recruitment of future scientists who can handle rapidly developing genomic techniques that will affect our everyday life.

Comparison of robot surgery modular and total knee arthroplasty kinematics.

The kinematics of seven knee specimens were measured from 0 to 120 degrees flexion using an up-and-down crouching machine. Motion was characterized by the positions of the centers of the lateral and medial femoral condyles in the anterior-posterior direction relative to a fixed tibia. A modular unicompartmental knee, trochlea flange, and patella resurfacing (multicompartmental knee [MCK] system) were implanted using a surgeon-interactive robot system that provided accurate surface matching. The MCK was tested, followed by standard cruciate retaining (CR) and posterior stabilized (PS) knees. The motion of the MCK was close to anatomic, especially on the medial side, in contrast to the CR and PS knees that showed abnormal motion features. Such a modular knee system, accurately inserted, has the potential for close to normal function in clinical application.

Stability of the posteromedial fragment in a tibial plateau fracture.

The posteromedial fragment in tibial plateau fractures is considered unstable and requires specific fixation. However, if not loaded by the femur, it may remain stable and not require additional fixation. Our purpose was to determine the size of the posteromedial fragment that would remain unloaded by the femoral-tibial contact area, as a function of fracture line orientation and knee flexion angle. Seven human cadaveric knees with intact capsule and ligaments were mounted in a mechanical rig and flexed from 0 to 30, 90, 105, and 120 degrees of flexion. The fiducial points and articular surfaces were digitized, and 3-dimensional software models of the knees at each flexion angle were created. The femoral-tibial contact areas were determined using the software under high- and low-load conditions. Posteromedial fragments of various sizes and fracture line orientations relative to the posterior femoral condylar axis (PFCA) were modeled, and their locations relative to contact areas were determined. The size of unloaded fragments decreased with increased flexion angle. Fragments occupying 60% of the medial plateau were loaded at all angles, but fragments with 30% of the plateau became loaded at 90 degrees under high load and 120 degrees under low load. Fracture line orientations of 0 to 20 degrees external rotation relative to PFCA allowed for the largest fragments to remain unloaded. The size of posteromedial tibial plateau fracture fragment that remains unloaded by the femur varies with knee flexion angle and fracture line orientation. This may have implications for the management of posteromedial tibial plateau fractures.

Preclinical evaluation method for total knees designed to restore normal knee mechanics.

The objective was to develop a simple, rapid, and low-cost method for evaluating proposed new total knee arthroplasty (TKA) models and then to evaluate 3 different TKA models with different kinematic characteristics. A "desktop" knee testing rig was used to apply forces and moments over a full flexion range, representing a spectrum of positions and activities; and the positions of the femur on the tibia were measured. The average neutral path of motion (for compressive force only) and the laxities about the neutral path (for superimposed shear and torque) were determined from 8 knee specimens to be used as a benchmark for the TKA evaluations. A typical posterior-stabilized TKA did not display the normal external femoral rotation with flexion and also showed abnormal anterior sliding on the medial side. A medial-pivot type of guided-motion design showed medial stability comparable to anatomical but still did not produce external femoral rotation and posterior lateral displacement with flexion. The addition of a central cam-post produced the rotation and displacement but only after 75° of flexion. It was concluded that the test method satisfied the objective and could be used as a design tool for evaluating new and existing designs, as well as for formulating a TKA with anatomical characteristics.

Differential strain of the axially loaded scapholunate interosseus ligament.

PURPOSE: To directly measure strain changes in the scapholunate ligament via magnetic resonance imaging (MRI) when axially loading the wrist in the neutral and extended positions. METHODS: Six asymptomatic male volunteers without known history of previous wrist injury were enrolled in this MRI-based study. Each subject underwent 3 MRI scans in a 3T scanner: in resting neutral position, in neutral with axial load applied, and in extension with axial load applied. Axial load was applied via extension of an elastic band with known force/elongation curve. We analyzed images and converted them to 3-dimensional stereolithographs. Attachment points of the palmar, proximal, and dorsal sections of the scapholunate interosseus ligament (SLIL) were identified. The lengths of the resulting vectors were recorded for each position. Strain, defined as change in length divided by original length, was calculated for the axially loaded neutral and extended wrists. We used the Bonferroni adjusted multiple comparisons from an analysis of variance model, with statistical significance defined as p < .05. RESULTS: Strains were significantly greater in the palmar (p = .02) and proximal (p = .01) subregions of the SLIL in loaded extension versus loaded neutral positions. In contrast, the strain on the dorsal component in extension was not statistically greater than in the neutral position (p = .45). Axial load in neutral resulted in minimal strain of all 3 components of the SLIL complex, and these were not significantly different from each other (p > .99). With extension, the strains of the palmar (p = .03) and proximal (p = .006) regions were statistically greater than that of the dorsal component. CONCLUSIONS: In extension, strain is greatest in the palmar and proximal portions of the intact SLIL. Axial load in neutral applies minimal strain to the SLIL complex. Avoiding axial loading in extension and encouraging loading in neutral position may allow for decreased injury and more effective healing of the scapholunate ligament.

Total knees designed for normal kinematics evaluated in an up-and-down crouching machine.

We constructed a crouching machine to study the motion of the knee joint, in which a motor was used to wind the quadriceps tendon so as to move the knee from high flexion to extension and back into flexion, while springs simulated hamstrings forces. Seven human cadaveric knees were tested intact and then after anterior cruciate ligament (ACL) resection. Motions of the femur, tibia, and patella were recorded by an optical tracking system. We then inserted plastic models representing commonly used total condylar and posterior stabilized knee replacement designs. Femoral motion was described by successive positions of the transverse axis of the femur projected onto the tibial surface. In the knee replacements, motions were similar to that of an ACL-deficient knee. We then tested two new designs with features intended to prevent anterior paradoxical sliding and to promote a medial pivot motion with femoral rollback primarily on the lateral side. The motion path more closely followed that of the normal intact knee. We concluded that motion guiding features in a total knee replacement could reproduce a normal neutral path that might result in functional improvements for the patient.

Design features of total knees for achieving normal knee motion characteristics.

The goal of the study was to achieve a normal neutral anatomical path of motion with a total knee arthroplasty (TKA) using specific motion-guiding design features. Two reference TKA models were used, consisting of a partially conforming double-dished geometry and the same with a central cam-post for femoral rollback. Four experimental TKA models included features to produce femoral rollback with and without guidance for tibial rotation, and a feature to prevent paradoxical anterior femoral sliding. The femur was loaded down the tibial axis, and the femoral-tibial positions were recorded at a sequence of flexion angles. Subsequently, the positions were recorded with an anterior shear force superimposed. Software was used to reconstruct the paths of the transverse femoral axis on the tibia, during a full flexion range. The reference knees did not reproduce a normal neutral path of motion. However, this was achieved with an experimental design incorporating all of the motion-guiding features.