Impact of Prophylactic Cerclage Location on Femoral Fracture Propagation: A Biomechanical Study.

OBJECTIVES: Prophylactic cerclage cables are often placed intraoperatively about a fracture to prevent propagation. However, biomechanical data supporting optimal cable placement location are lacking. The objective of this study was to evaluate the impact of prophylactic cerclage placement location on the propagation of femoral shaft fractures. METHODS: The diaphysis of 14 fresh-frozen cadaveric femora were included. Volumetric bone mineral density in the femoral shaft was obtained from quantitative computed tomography scans. For each specimen, a 5-mm longitudinal fracture was created proximally to simulate a pre-existing fracture. After reaming of the femoral canal, a 3 degrees tapered wedge was advanced with an MTS machine at 0.2 mm/s until failure. The tests were conducted with a CoCr cable placed at varying distances (5 mm, 10 mm, 15 mm, 20 mm, and cableless) from the distal tip of the initial fracture. A compression loadcell was used to measure the cable tension during the tests. The axial force, displacement, and cable tension were monitored for comparison between groups. RESULTS: In the cableless group, the mean force needed to propagate the fracture was 1017.8 ± 450.3 N. With the addition of a cable at 5 mm below the fracture, the failure force nearly doubled to 1970.4 ± 801.1 N (P < 0.001). This also led to significant increases in stiffness (P = 0.006) and total work (P = 0.001) when compared with the control group. By contrast, in the 15 and 20 mm groups, there were no significant changes in the failure force, stiffness, and total work as compared with the control group (P > 0.05). CONCLUSIONS: Propagation of femoral shaft fracture was effectively resisted when a prophylactic cable was placed within 5 mm from the initial fracture, whereas cables placed more than 10 mm below the initial fracture were not effective in preventing fracture propagation.

Contributions of capsular releases to femoral exposure in total hip arthroplasty via the direct anterior approach.

BACKGROUND: In total hip arthroplasty via the direct anterior approach, appropriate exposure is critical to allow preparation of the femur. The objective of this study was to explore the optimal soft tissue releases needed to allow broaching of the femur through a combination of experimental tests and computer simulations. METHODS: Fourteen full-body cadaveric specimens were included in this study. Total hip arthroplasty was performed via the direct anterior approach with the femur at 20° adduction and 20°extension. Soft tissue releases were performed sequentially, namely, the transverse iliofemoral ligament, descending iliofemoral ligament, ischio-femoral ligament, conjoint tendon, and obturator externus. After each release, the femur mobility was assessed by applying a 6 Nm external rotation torque and a 120 N distraction force. Subsequently, using specimen-specific models and models of the broach and handle, the broach passage after each release was simulated, and the release that allowed broach passage was analyzed. FINDINGS: The average external rotation after releasing the transverse and descending iliofemoral ligaments increased by 14.1° ± 6.1° and 13.8° ± 5.3°. With subsequent soft tissue releases, the rotational mobility increased incrementally, though the impact decreased. Impingement between the broach passage and the pelvis was mainly at the anterior superior iliac spine and the anterior inferior iliac spine. The volume of impingement decreased from 4.8 ± 4.5 cm3 after resection of the femoral head to 1.8 ± 1.6 cm3 and 1.2 ± 1.9 cm3 after release of the transverse and descending iliofemoral ligament, respectively. INTERPRETATION: With sequential soft-tissue releases, the femur mobility increased incrementally. However, the number of releases needed for each femur varied extensively between specimens. Most (10/14) femurs became accessible after the release of the ilio-femoral or ischio-femoral ligament.

Single-Strand "Short Isometric Construct" Medial Collateral Ligament Reconstruction Restores Valgus and Rotational Stability While Isolated Deep MCL and Superficial MCL Reconstruction Do Not.

BACKGROUND: Historical MCL (medial collateral ligament) reconstruction (MCLR) techniques have focused on the superficial MCL (sMCL) to restore valgus stability while frequently ignoring the importance of the deep MCL (dMCL) in controlling tibial external rotation. The recent recognition of the medial ligament complex importance has multiple studies revisiting medial anatomy and questioning contemporary MCLR techniques. PURPOSE: To assess whether (1) an isolated sMCL reconstruction (sMCLR), (2) an isolated dMCL reconstruction (dMCLR), or (3) a novel single-strand short isometric construct (SIC) would restore translational and rotational stability to a knee with a dMCL and sMCL injury. STUDY DESIGN: Controlled laboratory study. METHODS: Biomechanical testing was performed on 14 fresh-frozen cadaveric knee specimens using a custom multiaxial knee activity simulator. The specimens were divided into 2 groups. The first group was tested in 4 states: intact, after sectioning the sMCL and dMCL, isolated sMCLR, and isolated dMCLR. The second group was tested in 3 states: intact, after sectioning the sMCL and dMCL, and after single-strand SIC reconstruction (SICR). In each state, 4 loading conditions were applied at 0°, 20°, 40°, 60°, and 90° of knee flexion: 8-N·m valgus torque, 5-N·m external rotation torque, 90-N anterior drawer, and combined 90-N anterior drawer plus 5-N·m tibial external rotation torque. Anterior translation, valgus rotation, and external rotation of the knee were measured for each state and loading condition using an optical motion capture system. RESULTS: sMCL and dMCL transection resulted in increased laxity for all loading conditions at all flexion angles. Isolated dMCLR restored external rotation stability to intact levels throughout all degrees of flexion, yet valgus stability was restored only at 0° of flexion. Isolated sMCLR restored valgus and external rotation stability at 0°, 20°, and 40° of flexion but not at 60° or 90° of flexion. Single-strand SICR restored valgus and external rotation stability at all flexion angles. In the combined anterior drawer plus external rotation test, isolated dMCL and single-strand SICR restored stability to the intact level at all flexion angles, while the isolated sMCL restored stability at 20° and 40° of flexion but not at 60° or 90° of flexion. CONCLUSION: In the cadaveric model, single-strand SICR restored valgus and rotational stability throughout the range of motion. dMCLR restored rotational stability to the knee throughout the range of motion but did not restore valgus stability. Isolated sMCLR restored external rotation and valgus stability in early flexion. CLINICAL RELEVANCE: In patients with anteromedial rotatory instability in the knee, neither an sMCLR nor a dMCLR is sufficient to restore stability.

Pelvic tilt affects superolateral coverage, but not superomedial coverage of the femoral head following periacetabular osteotomy.

BACKGROUND: Pelvic tilt is an important sagittal parameter that varies greatly among individuals. The objective of this study was to quantify the effect of pelvic tilt on femoral head coverage and range of motion in a dysplastic population following periacetabular osteotomy. METHODS: Twenty-three dysplastic hips from 19 patients (17 female, 2 male) were included in this study. Three-dimensional models were reconstructed using pre-operative CT images, and patient-specific neutral pelvic tilt was obtained on an anteroposterior X-ray. Following a simulated periacetabular osteotomy, the pelvic tilt was changed from -15° to +15°, and the effects on femoral head coverage and hip range of motion was quantified using a customized MATLAB program. FINDINGS: Pelvic tilt did not significantly affect total femoral head coverage (P > 0.2). However, a 15° anterior tilt from neutral resulted in a 17.72 ± 9.45% increase in anterolateral coverage and a 23.96 ± 7.48% decrease in posterolateral coverage (P < 0.0001), as well as an 18.2 ± 8.4° loss of internal rotation at 90° of hip flexion. Contrarily, posterior pelvic tilt led to a 26.79 ± 9.04% reduction in anterolateral coverage (P < 0.0001) and an 18.02 ± 9.57% increase in posterolateral coverage (P < 0.0001), and the maximum internal rotation increased 11.8 ± 3.7°. INTERPRETATION: While pelvic tilt did not affect total femoral head coverage, it had a significant impact on the distribution of coverage within the superolateral region of the femoral head. Anterior pelvic tilt led to increased anterolateral coverage, but also had a negative impact on hip range of motion. An optimal surgical plan should achieve adequate coverage while not significantly limiting the patient's mobility.

Variations in Trochlear Morphology of Contemporary and Legacy Total Knee Arthroplasty Prostheses: A Review of 22 Designs.

BACKGROUND: The morphology of the trochlear compartment of total knee arthroplasty (TKA) prostheses is a major determinant of postoperative patello-femoral kinematics, particularly with unresurfaced patellae. The objective of this study was to quantify and compare the trochlear morphology of a large series of contemporary and legacy TKA designs. METHODS: The 3-dimensional surface models of 22 femoral components (13 contemporary and 9 legacy) were created using high-resolution laser scanning. The trochlear profile of each component was analyzed from proximal to distal in 15° increments around the trochlear axis. In each profile, the following variables were measured: sulcus angle, medio-lateral deviation of the sulcus, the height and width of the facets, and the trochlear groove orientation. RESULTS: In the contemporary group, the sulcus angle decreased progressively along the trochlear arc to varying degrees, except for 2 symmetrical designs, whereas the sulcus angle of the legacy designs showed considerable variability. The height of the medial facet was very strongly correlated with that of the lateral facet in the contemporary group (R2 = 0.89), whereas the correlation was weak for the legacy designs (R2 = 0.36). Moreover, the trochlear sulcus deviated laterally from distal to proximal in 10 contemporary designs and 7 legacy designs, resulting in a trochlear groove orientation of 4.2 to 11.1° and 4.3 to 10.5°, respectively. In the remaining 5 designs (3 contemporary and 2 legacy), the sulcus was vertical. CONCLUSIONS: There is more consistency in trochlear morphology of contemporary TKA designs compared to that of legacy designs, yet there are still large variations between different designs.

A Cross-Source Point Cloud Registration Algorithm Based on Trigonometric Mutation Chaotic Harris Hawk Optimisation for Rockfill Dam Construction.

A high-precision three-dimensional (3D) model is the premise and vehicle of digitalising hydraulic engineering. Unmanned aerial vehicle (UAV) tilt photography and 3D laser scanning are widely used for 3D model reconstruction. Affected by the complex production environment, in a traditional 3D reconstruction based on a single surveying and mapping technology, it is difficult to simultaneously balance the rapid acquisition of high-precision 3D information and the accurate acquisition of multi-angle feature texture characteristics. To ensure the comprehensive utilisation of multi-source data, a cross-source point cloud registration method integrating the trigonometric mutation chaotic Harris hawk optimisation (TMCHHO) coarse registration algorithm and the iterative closest point (ICP) fine registration algorithm is proposed. The TMCHHO algorithm generates a piecewise linear chaotic map sequence in the population initialisation stage to improve population diversity. Furthermore, it employs trigonometric mutation to perturb the population in the development stage and thus avoid the problem of falling into local optima. Finally, the proposed method was applied to the Lianghekou project. The accuracy and integrity of the fusion model compared with those of the realistic modelling solutions of a single mapping system improved.

The Stability of Fixation of Vancouver B2 Periprosthetic Femoral Fractures: Effect of Implantation Technique.

BACKGROUND: Due to increasing volume of total hip arthroplasties, periprosthetic femoral fractures have become a common complication with increased revision burden and perioperative morbidity. The objective of this study was to evaluate the fixation stability of Vancouver B2 fractures treated with 2 techniques. METHODS: A common B2 fracture was created by reviewing 30 type B2 cases. The fracture was then reproduced in 7 pairs of cadaveric femora. The specimens were divided into 2 groups. In Group I ("reduce-first"), the fragments were reduced first, followed by implantation of a tapered fluted stem. In Group II ("ream-first"), the stem was implanted in the distal femur first, followed by fragment reduction and fixation. Each specimen was loaded in a multiaxial testing frame with 70% of peak load during walking. A motion capture system was used to track the motion of the stem and fragments. RESULTS: The average stem diameter in Group II was 16.1 ± 0.4 mm, versus 15.4 ± 0.5 mm in Group I. The fixation stability was not significantly different in the 2 groups. After the testing, the average stem subsidence was 0.36 ± 0.31 mm and 0.19 ± 0.14 mm (P = .17) and the average rotation was 1.67 ± 1.30° and 0.91 ± 1.11° (P = .16) in Groups I and II, respectively. Compared to the stem, there was less motion of the fragments and there was no difference between the 2 groups (P > .05). CONCLUSIONS: When tapered fluted stems were used in combination with cerclage cables for treatment of Vancouver type B2 periprosthetic femoral fractures, both the "reduce-first" and "ream-first" techniques showed adequate stem and fracture stability.

Systemic Inflammation Markers Associated with Bone Mineral Density in perimenopausal and Postmenopausal Women.

Objective: The aim of this research was to determine whether systemic inflammatory indicators, including aggregate index of systemic inflammation (AISI), neutrophils lymphocyte to platelet ratio (NLPR), systemic immune-inflammation index (SII), and systemic inflammation response index (SIRI), are related to bone mineral density (BMD) in perimenopausal and postmenopausal women. Methods: One hundred and eighty-one perimenopausal and 390 postmenopausal women were enrolled in this cross-sectional study. Continuous variables by analysis of variance and Kruskal Wallis test for comparing the clinical characteristics. Linear regression analysis was conducted to investigate the associations between inflammatory indicators with BMD. The comparison between the subgroups was performed using the nonparametric test and the T-test. Results: AISI, NLPR, SII, and SIRI quartile values were inversely associated with BMD in menopausal women (P = 0.021; P = 0.047; P < 0.001; P < 0.001, respectively). After adjusting for confounding factors, four inflammatory indicators remained significantly associated with BMD (all P for trend <0.001). Analysis according to menopausal status demonstrated that AISI, SII, and SIRI were significantly correlated with mean femoral neck BMD in postmenopausal women (P for trend = 0.015, 0.004, and 0.001), but not significantly associated with BMD in perimenopausal women (P for trend = 0.248, 0.054, and 0.352) after adjustment for covariates. Conclusion: The quartile values of AISI, SII, and SIRI were inversely associated with BMD in postmenopausal women, following adjustment for individual variables, hormone profiles and glucolipid metabolism profiles. AISI, SII, and SIRI have potential to be important tools for screening and prevention of bone loss in menopausal women in future clinical practice.

The hidden impact of orthopedic surgeries: Examining the psychological consequences.

Orthopedic surgery is commonly considered "quality of life care," as most orthopedic procedures have been shown to provide excellent pain relief and successful surgical outcomes for patients. Although orthopedic surgeries continue to improve patients' functional outcomes through modern surgical techniques and preoperative psychological screening, variation in patient function persists in current studies. Sub-optimal function in patients has been shown to be associated with emotional health burdens, such as anxiety and depression. Previous research has found that preoperative psychological conditions could negatively affect patients' functional outcomes. However, these studies were limited in that they did not examine novel psychological repercussions in emotionally healthy patients following surgery. To address this gap in knowledge, a narrative review was conducted to differentiate specific orthopedic surgeries that have psychological consequences on patients and to determine the current psychological support available for these patients. Data was collected from the Medical Humanities sector of the Texas Medical Center Library and the National Library of Medicine. Studies were included that examined novel psychological effects on patients after undergoing orthopedic surgery. A total of 38 articles were identified, and the majority focused on orthopedic trauma surgery while the rest examined total joint arthroplasty and orthopedic sports procedures. A key finding was that orthopedic trauma surgeries, alone and compared to total joint arthroplasty, result in a greater risk of negative psychological effects, while there was limited data on the psychological effects of orthopedic sports procedures. This narrative review suggests a need to integrate psychosocial support for patients with traumatic orthopedic intervention, regardless of the patient's preoperative psychological state. Furthermore, more research examining the mental well-being of patients following elective orthopedic surgeries is necessary to determine if these operations would benefit from postoperative psychological support as well.

Genetically predicted iron status was associated with the risk of prostate cancer.

Introduction: Observational studies have reported a relationship between iron status and the risk of prostate cancer. However, it remains uncertain whether the association is causal or due to confounding or reverse causality. To further clarify the underlying causal relationship, we conducted a Mendelian randomization (MR) analysis. Methods: We selected three genetic variants (rs1800562, rs1799945, and rs855791) closely correlated with four iron status biomarkers (serum iron, log-transformed ferritin, transferrin saturation, and transferrin) as instrumental variables. Summary statistics for prostate cancer were obtained from the Prostate Cancer Association Group to Investigate Cancer Associated Alterations in the Genome consortium including 79,148 cases and 61,106 controls of European ancestry. The inverse-variance weighted (IVW) method was conducted primarily to estimate the association of genetically predicted iron status and the risk of prostate cancer, supplemented with simple-median, weighted-median and maximum-likelihood methods as sensitivity analysis. MR-Egger regression was used to detect directional pleiotropy. We also conducted a meta-analysis of observational studies to assess the associations between iron status and the risk of prostate cancer. Results: Genetically predicted increased iron status was associated with the decreased risk of prostate cancer, with odds ratio of 0.91 [95% confidence interval (CI): 0.84, 0.99; P = 0.035] for serum iron, 0.81 (95% CI: 0.65, 1.00; P = 0.046) for log- transformed ferritin, 0.94 (95% CI: 0.88, 0.99; P = 0.029) for transferrin saturation, and 1.15 (95% CI: 0.98, 1.35; P = 0.084) for transferrin (with higher transferrin levels representing lower systemic iron status), using the inverse-variance weighted method. Sensitivity analyses produced consistent associations, and MR-Egger regression indicated no potential pleiotropy. Our replication analysis based on FinnGen research project showed compatible results with our main analysis. Results from our meta-analysis similarly showed that serum ferritin [standardized mean difference (SMD): -1.25; 95% CI: -2.34, -0.16; P = 0.024] and transferrin saturation (SMD: -1.19; 95% CI: -2.34, -0.05; P = 0.042) were lower in patients with prostate cancer compared with that in controls. Discussion: Our study suggests a protective role of iron in the risk of prostate cancer, further investigations are required to clarify the underlying mechanisms.

Insulin-like peptide 5 (INSL5) positively correlates with anti-Müllerian hormone (AMH) in women with the polycystic ovary syndrome: a case-control study.

BACKGROUND: Insulin-like peptide 5 (INSL5) is involved in both reproductive and metabolic processes in polycystic ovary syndrome (PCOS). This study aimed to evaluate the relationship between INSL5 and anti-Müllerian hormone (AMH). METHODS: A retrospective case-control study was conducted in a university-based reproductive centre between December 2019 and January 2021. We included 117 women with PCOS and 100 healthy subjects from Zhejiang Province. All subjects were divided into four groups (1st-4th) based on quartiles of serum INSL5 levels. Serum INSL5 concentration was assayed using an enzyme-linked immunosorbent assay. RESULTS: A significant direct association was observed between serum INSL5 and AMH levels in women with PCOS. The mean AMH level in the 1st-4th INSL5 level quartiles were 4.64, 5.20, 6.46, and 9.48 ng/ml, respectively (P < 0.001). After adjusting for age, body mass index, metabolic indices, and serum levels of oestradiol and total testosterone, AMH levels remained positively and significantly associated with INSL5 levels (P for trend < 0.001). The diagnostic value of AMH was better than that of INSL5. CONCLUSIONS: INSL5 and AMH levels were significantly correlated and elevated in women with PCOS. INSL5 and AMH might be associated with increased androgen secretion and chronic anovulation in PCOS.

Prevalence and Risk Factors of Workplace Violence Against Emergency Department Nurses in China.

Objectives: We aim to find out the prevalence, characteristics, and predictors of workplace violence (WPV) against current Chinese emergency department (ED) nurses. Methods: A cross-sectional survey of 20,136 ED nurses was conducted in 31 provinces in China between July and September 2019. Descriptive analyses were used to examine the prevalence and characteristics of WPV. Chi-square analysis and Binary logistic regression analysis were used to identify the predictors of WPV. Results: During the past 12 months, there are 79.39% of ED nurses exposed to any type of WPV, including 78.38% and 39.65% exposed to nonphysical and physical violence, respectively. Binary logistic regression analysis shows that ED nurses who were male, had bachelor's degrees, had average monthly salary between 5,001 and 12,000, worked in central China, had higher professional titles, were more experienced, arranging shift work, and had higher work stress were more likely to experience WPV. Conclusion: A relatively high prevalence of WPV against Chinese ED nurses has been revealed in this study. The characteristics and predictors of WPV remind us to take positive measures to reduce WPV.

Fabrication and characterization of biodegradable Zn scaffold by vacuum heating-press sintering for bone repair.

Bone repair materials with excellent mechanical properties are highly desirable, especially in load-bearing sits. However, the currently used ceramic- and polymer-based ones mainly show poor mechanical properties. Recently, biodegradable metals have attracted extensive attention due to their reliable mechanical strength and degradability. As biodegradable metals, zinc-based materials are promising due to their suitable degradation rate and good biocompatibility. Here, we fabricated biodegradable porous Zn scaffolds with relatively high mechanical properties by vacuum heating-press sintering using NaCl particles as space holders. The microstructure, actual porosity, compressive mechanical properties, in vitro degradation behavior and the vitality of osteoblasts of porous Zn scaffolds were tested and investigated. The results show the porosities of the prepared porous Zn scaffolds are ranging from 11.3 % to 63.3 %, and the pore sizes are similar to the size range of the screened NaCl particles (200-500 µm). Compressive yield strength of 14.2-73.7 MPa and compressive elastic modulus of 1.9-6.7 GPa are shown on porous Zn scaffolds, some of which approach to that of cancellous bone (2-12 MPa and 0.1-5 GPa). Compared to bulk Zn, although the porous structures cause a partial loss of strength, the reliable mechanical properties are still retained. In addition, the porous structures not only greatly increase the degradation rate, but also promote the proliferation of osteoblasts. Based on these results, biodegradable porous Zn scaffolds (porosity in the 40 %-50 %) fabricated by vacuum heating-press sintering method show high application potential for clinical bone repair.

The Length of Diaphyseal Contact of Tapered Fluted Stems is Highly Dependent on Canal Morphology.

BACKGROUND: Diaphyseal fixation remains the mainstay of revision THA. The stability of diaphyseal fixation can be quantified by the extent of contact between the stem and the endosteal cortex. This is highly affected by the morphology of the proximal femur. The purpose of this study was to examine factors affecting diaphyseal contact in the revision THA and to identify preoperative predictors of adequate fixation. METHODS: Three-dimensional femur models were created from CT scans of 33 Dorr B and C femora. The proximal 120 mm of the femur was omitted to mimic proximal bone deficiency. A tapered fluted stem (3 degrees, 150 mm) model was virtually implanted after reaming of the medullary canal. The contact length between stem and endosteal cortex was measured, in addition to other variables. The relationship between variables was evaluated using Spearman's correlation, and logistic regression analysis was used to identify predictors of the contact length (P < .05). RESULTS: The contact length varied widely between specimens (66.5 ± 16.6 mm, range: 21-98 mm). Contact increased with the depth of the isthmus below the lesser trochanter (range: 55-155 mm; r2 = 0.473, P = .005) and the distance between the isthmus and the distal edge of the damage zone (range: -9 to 96 mm; r2 = 0.508, P = .002). Stepwise regression identified the reaming length, distance between fracture and the isthmus, and isthmus diameter as independent predictors of contact length (r = 0.643). CONCLUSIONS: Contact is limited in specimens where the isthmus is more proximally located. In these cases, supplementary fixation using plating and/or longer, curved prosthesis may be considered.

Contemporary Robotic Systems in Total Knee Arthroplasty: A Review of Accuracy and Outcomes.

The success of total knee arthroplasty (TKA) depends on restoration of the stability and biomechanical efficiency of the native knee. The emergence of robotic surgical technologies has greatly increased the precision and reproducibility. We discuss contemporary robotic TKA systems by reviewing the features of the individual platforms, their accuracy, and the clinical outcomes. While early results suggest significant gains in patient outcomes, long-term evidence is still awaited from multicenter prospective clinical trials. Moreover, advances in this technology are needed to address knee laxity while individualizing the functional performance of each patient's new joint.

Micromotion and Migration of Cementless Tibial Trays Under Functional Loading Conditions.

BACKGROUND: The outcome of cementless total knee arthroplasty (TKA) relies on successful bony ingrowth into the implant surfaces. Failures due to aseptic loosening are still reported, especially in younger and more active patients. The objective of this study is to quantify the micromotion of a commercially available design of cementless tibial tray under loading conditions simulating walking and stair descent. METHOD: A commercially available design of cementless total knee arthroplasty was implanted in 7 cadaveric knees which were preconditioned with 500 cycles of 0°-100° flexion under a vertical load of 1050 N in a custom-built, multiaxial functional activity simulator. This was followed by application of the peak forces and moments occurring during walking and stair descent. During each loading procedure, 3-dimensional motion at the bone-prosthesis interface was measured using digital image correlation. RESULTS: The tray migrated 101 ± 25 µm on average during preconditioning, which was dominated by rotation in the sagittal plane (92% of total migration), combined with posterior translation (28%) and minimal rotation in the transverse plane (14%). The migration varied 2.7-fold (61-167 µm) between the 6 measurement zones. Stair descent produced significantly higher total micromotion than walking in zone #5 (62 ± 9 vs 51 ± 10 µm, P < .05) and zone #6 (68 ± 17 vs 37 ± 10 µm, P < .05). In addition, during stair descent, the tray exhibited significantly more tilting (anterior zones: 31 ± 17 vs -16 ± 20 µm, P < .05; posterior zones: -60 ± 8 vs -40 ± 7 µm, P < .05) and more anteroposterior displacement in the anterior zones (-25 ± 3 vs -13 ± 2 µm, P < .05) when compared to walking. CONCLUSION: The relative motion at the bone-prosthesis interface varied substantially around the periphery of the cementless tray. Under the loading conditions evaluated, the tray primarily underwent a rocking motion in the sagittal plane. Compared with walking, stair descent produced significantly more micromotion, especially in the posterior zones.

The continuum of hip range of motion: From soft-tissue restriction to bony impingement.

Traditional studies of hip kinematics have not identified which anatomic structures limit the range of motion (ROM) when the hip is placed in different maneuvers. In this study, we attempted to answer two questions: (a) During which maneuvers is the motion of the hip limited by bony impingement between the femur and pelvis? (b) When is hip ROM determined by the constraint of soft tissues and to what extent? ROM of eight cadaveric hips was measured in 17 maneuvers using a motion capture system. The maneuvers were recreated in silico using 3D CT models of each specimen to detect the occurrence of bony impingement. If bony impingement was not detected, the variable component of 3D hip motion was increased until a collision was detected. The difference between the virtual ROM at the point of bony impingement and the initial ROM measured experimentally was termed as the soft-tissue restriction. The results showed that bony impingement was present in normal hips during maneuvers consisting of high abduction with flexion, and high flexion combined with adduction and internal rotation. At impingement-free maneuvers, the degree of soft tissue restriction varies remarkably, ranging from 4.9° ± 3.8° (internal rotation) at 90° of flexion to 80.0° ± 12.5° (internal rotation) at maximum extension. The findings shed light on the relative contributions of osseous and soft tissues to the motion of the hip in different maneuvers and allow for a better understanding of physical exams of different purposes in diagnosing bone- or soft tissue-related diseases.

Pelvic Tilt and Range of Motion in Hips With Femoroacetabular Impingement Syndrome.

INTRODUCTION: Physiotherapy is a management option for the treatment of femoroacetabular impingement (FAI) syndrome. This study examines the influence of changes in pelvic tilt and hip adduction on the range of motion (ROM) of the hip. METHODS: Ten FAI hips were used to simulate impingement at two positions: (1) 20° internal rotation (IR) with 100° flexion and 10° adduction and (2) 40° IR with 35° flexion and 10° adduction; the amount of IR was measured at the point of bony impingement or to the defined limit. Each simulation was performed at neutral and 5° and 10° anterior and posterior pelvic tilt. Then, the hip was placed in 10° of abduction, and all simulations were repeated. RESULTS: With neutral pelvic tilt, impingement occurred at 4.3 ± 8.4° of IR at the high-flexion position. An increase in anterior pelvic tilt led to a loss of IR, that is, earlier occurrence of FAI, whereas an increase in posterior pelvic tilt led to an increase in IR, that is, later occurrence of FAI. At the high-flexion position, abduction provided more IR before impingement (neutral: 9.1 ± 5.7°, P < 0.01; 10° anterior tilt: 14.6 ± 5.2°, P < 0.01; 10° posterior tilt: 4.2 ± 3.7° IR, P = 0.01). Placing the hip in abduction and posteriorly tilting the pelvis produce a combined effect that increased IR relative to the neutrally tilted pelvis (5° posterior tilt: 11.4 ± 7.6°, P = 0.01; 10° posterior tilt: 12.8 ± 7.6°, P < 0.01). The ROM in the mid-flexion position was not affected by any combination of pelvic tilt and hip abduction or adduction (average IR: 37.4 ± 5.0°, P > 0.05). CONCLUSIONS: Abduction and posterior pelvic tilt increased the impingement-free ROM in the hips with FAI. Thus, rehabilitation aimed at altering the tilt of the pelvis may reduce the frequency of impingement and limit further joint damage.

How Flat Is the Tibial Osteotomy in Total Knee Arthroplasty?

BACKGROUND: Cementless total knee arthroplasty has been developed to decrease the incidence of failure in younger and more active patients. However, failures are still more common in cementless versus cemented components. It is hypothesized that this is triggered by incomplete bone-tray contact. The present study compares the final contact area of a cementless tray as a function of the initial osteotomy flatness. METHODS: Eight surgeons prepared 14 cadaveric knees for cementless total knee replacement using standard instrumentation. The topography of each osteotomy was captured with a laser scanner; 3-dimensional computer models of the surfaces were generated. After scanning each tibia, the surgeons implanted cementless tibial trays using a manual impactor. Each tibia was then dissected, embedded in mounting resin, and sectioned. The sectioned blocks were observed under stereomicroscopy to identify points of bone-tray contact which were incorporated into the 3-dimensional models. Maps were then generated illustrating depicting contacting and noncontacting areas. RESULTS: The mean initial flatness of all specimens was 1.1 ± 0.35 mm. After impaction, 79.4% ± 0.3% of the surface had established bony contact. Of the noncontacting areas, 17.6% were within 0.3 mm of the tray. Only 2.6% of the surface was at distances reported to impede ingrowth. Noncontacting areas were typically located centrally. A trend in decreasing percent contact area with increased flatness tolerance was observed (R2 = 0.605). CONCLUSION: (1) There is an inverse correlation between the flatness of the tibial osteotomy and the percentage of the bony surface in contact with underside of the tibial tray. (2) Almost all tray-tibia contact is generated during implantation through flattening of elevated features on the tibial surface. (3) Gaps between the tray and the tibia are consistently located in the central regions of the osteotomy proximal to the medullary canal.

Total Knee Arthroplasty in the Osteoporotic Tibia: A Biomechanical Evaluation of the Role of Stem Extensions and Cementing Techniques.

INTRODUCTION: Poor functional outcomes and aseptic loosening increase when total knee arthroplasty is performed on osteoporotic patients. This biomechanical study evaluated the effect of stem extension on the stability of tibial fixation using different cementing techniques. METHODS: A standard design tibial tray was implanted in a replica of a male osteoporotic tibia. Twenty-four implantations were performed using three variations of implant and cementing, and then mounted on a material testing machine load frame at 500 cycles of multiaxial loading simulating walking. The three-dimensional components of tray-tibia micromotion were measured. RESULTS: The primary implant total interface motion with surface cementing was 25.9 µm ± 14.7 µm and 10.6 µm ± 7.6 µm with full cementing (P = 0.001). The three-dimensional motion of fully cemented primary implants with stem extension was 4.4 µm ± 3.9 µm, which represents a decrease in micromotion of 83% in surface cemented primary implants (P < 0.0001) and 58% in the fully cemented components without stem extension (P < 0.009). CONCLUSION: Fully cemented primary implants with stem extensions demonstrated decreased micromotion and should be considered for use in osteoporotic total knee arthroplasty patients.