Wearing a Surgical Vest With a Sterile Surgical Helmet System Decreases Contamination of the Surgical Field.

BACKGROUND: Sterile surgical helmet systems are frequently utilized in total knee arthroplasty procedures to protect the surgeon while maintaining a comfortable working environment. However, common helmet systems pressurize the space between the surgical gown and the surgeon's skin. In gowns with a back seam, this may allow contaminated skin particles to escape into the surgical field. By measuring bacterial colony-forming units (CFUs), this study sought to determine if occlusion of the open back seam reduced the risk of potential contamination. METHODS: First, qualitative analysis depicting airflow variations between gown configurations was performed using the Schlieren Spherical Mirror imaging system. Each gown configuration consisted of a sterile surgical helmet and one of 3 gown configurations: a standard gown with rear-tied closure, a standard gown with a surgical vest, and a zippered Toga-style gown. Next, a surgeon then performed simulated surgical activities for 60 minutes within a 1.4 m3 isolation chamber with work surfaces and controllable filtered air exchanges. During each procedure, contaminated particles were collected on sets of agar settle plates positioned directly behind the surgeon. Upon completion, the agar plates were incubated in a biolab, and the number of bacterial and fungal CFUs was counted. The experimental procedure was repeated 12 times for each gown configuration, with sterilization of the chamber between runs. Contamination rates were expressed as CFUs/m2/h. RESULTS: The mean contamination rate measured with the standard gown was 331.7 ± 52.0 CFU/m2/h. After the addition of a surgical vest, this rate decreased by 45% to 182.2 ± 30.8 CFU/m2/h (P = .02). Similarly, with the Toga-style gown, contamination rates dropped by 49% to 170.5 ± 41.9 CFU/m2/h (P = .01). CONCLUSIONS: When used in conjunction with surgical helmet systems, conventional surgical gowns do not prevent potential contamination of the surgical field. We recommend that staff within the surgical field cover the back seam of standard gowns with a vest or don a zippered Toga-style gown.

The potential of suspended chitosan nanoparticles as a surgical irrigation fluid.

In this study, we sought to synthesize chitosan nanoparticles (CS-NPs) and characterize their morphology, efficacy in inhibiting bacterial attachment, and efficacy in eradicating bacteria established on implantable hardware. CS-NPs possess desirable properties, including antibacterial properties in biofilm-mediated infections. CS-NPs were produced using ionic gelation and characterized via scanning electron microscope imaging. Staphylococcus aureus was incubated with CS-NPs at various concentrations and compared to a 1% povidone-iodine with 1% H2 O2 control in 24-well plates. Stainless steel bone screws were placed in six-well plates and inoculated with S. aureus. After 24 h, the screws were transferred to one of three solutions (saline, 40 mg/mL CS-NP, or 1% povidone-iodine with 1% H2 O2 ). Four screws from each group were vortexed in saline and plated. The remaining screw from each group was prepped and imaged to map the location of persistent bacteria. Synthesized CS-NPs had a mean diameter of 0.39 ± 0.13 µm and circularity of 0.87 ± 0.05. The percent inhibition of bacterial attachment was 73% at 20 mg/mL, 73% at 30 mg/mL, 75% at 40 mg/mL, 79% at 50 mg/mL, and 78% at 60 mg/mL. When compared to saline, the 40 mg/mL CS-NP solution reduced bacteria on the screws by 76%. No bacteria were retrieved from the 1% povidone-iodine with 1% H2 O2 group. This study demonstrated that CS-NP solution effectively inhibited S. aureus bacterial attachment and was more effective than saline in eradicating bacteria from orthopedic hardware, suggesting that CS-NPs have the potential for prevention and treatment of musculoskeletal infections as a component of an intraoperative surgical irrigation solution.

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.

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.

Development of a personalized shared decision-making tool for knee osteoarthritis and user-testing with African American and Latina women.

Background: Patients with chronic knee pain are often unaware of treatment options and likely outcomes-information that is critical to decision-making. A consistent framework for communicating patient-personalized information enables clinicians to provide consistent, targeted, and relevant information. Our objective was to user-test a shared decision-making (SDM) tool for chronic knee pain. Methods: A cross-functional team developed a Markov-based health economics model and tested the model outputs with patient panels, patient and clinician focus groups, and clinical specialists. The resulting SDM tool was user-tested in a parallel-designed, randomized controlled study with 52 African American and 52 Latina women from geographically representative areas of the US. Participants were randomized to counseling with or without the SDM tool. Feedback was collected at intervention and at 1 month after intervention and analyzed with Student's t-tests and Chi-squared analyses (alpha = 0.05). Results: Qualitative results indicated patients understood the material, rated the overall experience highly, and were likely to recommend the physician. The SDM group reported high satisfaction with the tool. A greater proportion of the SDM group (56%) reported increased physical activity over baseline at 1 month compared with the control group (33%) (P = 0.0005). New use of medications for knee pain (58% SDM; 49% control) did not differ significantly between groups (P = 0.15). Conclusion: Use of this innovative SDM tool was associated with high satisfaction and a significant increase in self-reported physical activity level at 1 month. The SDM tool may elicit behavioral changes to promote musculoskeletal health.

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.

Do Ultraviolet Air Disinfection Units Reduce Contamination by Particulates in Total Knee Replacement Procedures?

BACKGROUND: Prosthetic joint infections have become the leading cause of joint replacement failure. The primary sources of contamination are skin flora and bacteria from airborne particles. Portable ultraviolet air disinfection units are used in the Operating Room (OR) to prevent contamination from airborne particles; however, their effectiveness is not proven. The purpose of this study was to compare the rate of contamination of sites with and without Ultraviolet (UV) air disinfection units during active surgeries. METHODS: Sedimentation rates of viable particles were measured during 40 primary TKA procedures. Half of the procedures were performed with ultraviolet air disinfection units. Air-borne particles were collected on nitrocellulose membranes at 5 locations within the OR. After incubation, all microbial colonies were counted and the sedimentation rates were reported in CFUs/m2/hr. 10 additional trials were performed in an empty OR with no staff present. RESULTS: The average contamination rate of all sites was 22 ± 1.1 CFUs/m2/hr in the empty OR vs. 21.3 ± 4.6 CFUs/m2/hr with UV units and 20.3 ± 4.9 CFUs/m2/hr without (P = .03, P = .03, P = .964). Viable contaminates were found in the sterile field in 25% of UV cases vs 45% non-UV. These differences were not statistically significant. There were differences found however, according to the number of staff in the room (6 vs 7 staff: P = .036, 6 vs 8 staff: P = .004). CONCLUSION: There was no statistical difference in contamination rate with the usage or non-usage of UV units. These 40 cases shows that the largest variables affecting the contamination rate were the number of staff present and size of the OR.

Evaluation of bone formation on orthopedic implant surfaces using an ex-vivo bone bioreactor system.

Recent advances in materials and manufacturing processes have allowed the fabrication of intricate implant surfaces to facilitate bony attachment. However, refinement and evaluation of these new design strategies are hindered by the cost and complications of animal studies, particularly during early iterations in the development process. To address this problem, we have previously constructed and validated an ex-vivo bone bioreactor culture system that can maintain the viability of bone samples for an extended period ex-vivo. In this study, we investigated the mineralization of a titanium wire mesh scaffold under both static and dynamic culturing using our ex vivo bioreactor system. Thirty-six cancellous bone cores were harvested from bovine metatarsals at the time of slaughter and divided into five groups under the following conditions: Group 1) Isolated bone cores placed in static culture, Group 2) Unloaded bone cores placed in static culture in contact with a fiber-mesh metallic scaffold, Group 3) Bone cores placed in contact with a fiber-mesh metallic scaffold under the constant pressure of 150 kPa, Group 4) Bone core placed in contact with a fiber-mesh metallic scaffold and exposed to cyclic loading with continuous perfusion flow of media within the ex-vivo culture system and Group 5) Bone core evaluated on Day 0 to serve as a positive control for comparison with all other groups at weeks 4 and 7. Bone samples within Groups 1-4 were incubated for 4 and 7 weeks and then evaluated using histological examination (H&E) and the Live-Dead assay (Life Technologies). Matrix deposits on the metallic scaffolds were examined with scanning electron microscopy (SEM), while the chemical composition of the matrix was measured using energy-dispersive x-ray spectroscopy (EDX). We found that the viability of bone cores was maintained after seven weeks of loading in our ex vivo system. In addition, SEM images revealed crystallite-like structures on the dynamically loaded metal coupons (Group 4), corresponding to the initial stages of mineralization. EDX results further confirmed the presence of carbon at the interface and calcium phosphates in the matrix. We conclude that a bone bioreactor can be used as an alternate tool for in-vivo bone ingrowth studies of new implant surfaces or coatings.

Designing and validation of an automated ex-vivo bioreactor system for long term culture of bone.

Several different bioreactors have been developed to study bone biology. Keeping a bone viable for long-term studies is still a challenge. We have developed an ex-vivo bone bioreactor that can keep the ex-vivo live bone viable for more than 4 weeks. Keeping a bone viable for over a month can be used as an alternative model for in-vivo experiments in animals. We hypothesize that the perfusion flow and mechanical load on the bone provide a real-time environment for the bone to survive. Cancellous bones were harvested from the bovine metatarsals and were placed in the dynamic culture with cyclic loading at regular intervals. After a period of week 4, the bone cores were retrieved from the bioreactor and tested for viability using calcein-AM and ethidium homodimer -1 fluorescent dyes and were compared with the cores that were placed in static culture with and without any loads on them and Day 0 bone core that acted as a positive control. The bone blocks were then fixed in 10% formalin, and bone mineral density was evaluated using a DXA scanner before staining them for H&E to study the morphological changes. Results revealed that the bone cultured in the bioreactor was viable as compared to the one in the static culture with and without constant load. Bone cores cultured in our ex-vivo bioreactor system also maintained their morphology and no statistical difference was found in the bone mineral density compared to positive controls and the statistical difference was found when compared with the cores cultured in static culture. This tool can be used to study bone biology for various applications such as bone ingrowth studies, to study the effect of drugs, hormones, or any growth factors, and much more.

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.

The envelope of active hip motion in different sporting, recreational, and daily-living activities: A systematic review.

BACKGROUND: In treating patients with limitations of hip motion, it is generally assumed that correction of bony morphology will provide the patient with the joint motion required to resume their activities. However, the positions of impingement and the specific excursions of joint motion required by each sport may vary. This systematic review aimed to define the envelope of active hip joint motion for participation in different sporting, recreational, and daily-living activities. METHODS: The EMBASE, PubMed, Google Scholar, and Cochrane databases were searched to identify studies that reported kinematics of the hip in sporting, recreational, and daily-living activities. Inclusion criteria were (1) peer-reviewed articles reporting hip kinematics in a certain type of activity, and (2) presented in English. To synthesize the kinematic data, the peak values of kinematic components (i.e. flexion/extension, abduction/adduction, and internal/external rotation) during an activity, as well as the concurrent values in a certain phase of the activity were collected from each study. RESULTS: A total of 67 studies met the inclusion criteria, involving 32 different types of activities. Seventeen activities required at least one component of supra-physiologic hip motion, however, there were eight different combinations of flexion/extension, abduction/adduction, and internal/external rotation observed. Specifically, three activities (sex, sitting cross-legged, and grand ecart lateral of ballet dancing) required simultaneous extreme degrees of all three components, five activities (arabesque, developpe devant right, and developpe a la seconde right of ballet dancing, picking up something, and taekwondo) required high degrees of two components, most commonly hip abduction combined with flexion or internal rotation. SIGNIFICANCE: This review highlighted that many activities place supraphysiologic demands on hip joint motion, however, the kinematic components affected differ dramatically with the specific activity. This suggests that the demands of each patient's individual activities must be assessed before recommending or planning treatment rather than assuming that a fixed value of "normal" hip motion is applicable to all.

2018 international consensus meeting on musculoskeletal infection: Summary from the biofilm workgroup and consensus on biofilm related musculoskeletal infections.

Biofilm-associated implant-related bone and joint infections are clinically important due to the extensive morbidity, cost of care and socioeconomic burden that they cause. Research in the field of biofilms has expanded in the past two decades, however, there is still an immense knowledge gap related to many clinical challenges of these biofilm-associated infections. This subject was assigned to the Biofilm Workgroup during the second International Consensus Meeting on Musculoskeletal Infection held in Philadelphia USA (ICM 2018) (https://icmphilly.com). The main objective of the Biofilm Workgroup was to prepare a consensus document based on a review of the literature, prepared responses, discussion, and vote on thirteen biofilm related questions. The Workgroup commenced discussing and refining responses prepared before the meeting on day one using Delphi methodology, followed by a tally of responses using an anonymized voting system on the second day of ICM 2018. The Working group derived consensus on information about biofilms deemed relevant to clinical practice, pertaining to: (1) surface modifications to prevent/inhibit biofilm formation; (2) therapies to prevent and treat biofilm infections; (3) polymicrobial biofilms; (4) diagnostics to detect active and dormant biofilm in patients; (5) methods to establish minimal biofilm eradication concentration for biofilm bacteria; and (6) novel anti-infectives that are effective against biofilm bacteria. It was also noted that biomedical research funding agencies and the pharmaceutical industry should recognize these areas as priorities. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

The Impact of Suture Caliber and Looped Configurations on the Suture-Tendon Interface in Zone II Flexor Tendon Repair.

PURPOSE: To evaluate the impact of suture caliber and looped configurations on the integrity of 4-strand modified Kessler zone II flexor tendon repairs during progressive cyclic loading. METHODS: Seventy-two flexor digitorum profundus tendons from 18 fresh human cadaver hands were divided into 4 repair groups. Thirty-six matched tendons underwent repair using either a 4-0 looped or 4-0 single-stranded suture, and an additional 36 tendons underwent 3-0 looped or 3-0 single-stranded repairs. Repair strength was tested by progressive cyclic loading. The force generating 2-mm gap formation, ultimate failure, and the mechanism of failure were recorded for each test. The impact of looped versus single-stranded configurations and the effect of tendon cross-sectional area on repair integrity were analyzed for each suture caliber. RESULTS: There was no statistically significant difference between groups regarding the force to 2-mm gap formation or ultimate failure, and all values exceeded the minimum threshold of 27 N required to withstand an early active range of motion rehabilitation protocol. The use of a 3-0 caliber suture resulted in a significantly higher proportion of repairs failing by suture pullout through the tendon substance, including 63.5% of looped and 38.9% of single-stranded core sutures. By comparison, this occurred in 11.1% of 4-0 looped and 0% of 4-0 single-stranded sutures. Larger tendon cross-sectional areas were associated with more robust repairs, particularly in the 3-0 looped group. CONCLUSIONS: In a human cadaver flexor tendon repair model, there was no significant difference in the mean force to failure between all 4 flexor tendon repair constructs under progressive cyclic loading. However, the 3-0 caliber suture failed more frequently by suture pullout, particularly with the use of a looped suture. CLINICAL RELEVANCE: Four-strand flexor tendon repairs using a 3-0 caliber suture are more prone to early failure by suture pullout under progressive cyclic loading compared with a 4-0 caliber suture.

Does Capsular Laxity Lead to Microinstability of the Native Hip?

BACKGROUND: Hip "microinstability" is commonly cited as the cause of symptoms that occur in the presence of translation of the femoral head away from conformity with the acetabular fossa. However, there is still no consistent objective criteria defining its presence and biomechanical basis. One hypothesis is that abnormal motion of the articular surfaces occurs because of capsular laxity, ultimately leading to clinical symptoms. PURPOSE: To determine the relationship between capsular laxity and abnormal rotation and translation of the hip. STUDY DESIGN: Controlled laboratory study. METHODS: Eight cadaveric hips were dissected down to the capsule and mounted in a customized multiaxial hip activity simulator. Each specimen was loaded with 5 N·m of internal and external rotational torque in full extension and 0°, 30°, 60°, and 90° of flexion. During testing, the relative position and rotation of the femur and the pelvis were monitored in real time with a 6-camera motion analysis system. The testing was repeated after capsular laxity was generated by placing a regular array of incisions ("pie crusting") in the iliofemoral, pubofemoral, and ischiofemoral ligaments. Joint rotation and femoral head translation were calculated with specimen-specific models. A hip microinstability index was defined as the ratio between the length of the locus of the femoral head center and the radius of the femoral head during rotation from extension to 90° of flexion. RESULTS: In intact hips, the components of femoral head translation were within 0.5 mm in positions close to neutral (<30° of flexion). Capsular modification led to significant increases in internal and external rotation ( P < .01) and in the translation of the femoral head center at different positions ( P < .05). Compared with intact hips, the femoral head was inferiorly displaced during external rotation and anteroinferiorly during internal rotation. The length of the locus of the femoral head center increased from 3.61 ± 1.30 mm to 5.35 ± 1.83 mm for external rotation ( P < .05) and from 6.24 ± 1.48 mm to 8.21 ± 1.42 mm for internal rotation ( P < .01). The correlations between rotational laxity and the total translation of the femoral head were not significant, with coefficients of 0.093 and 0.006 in external and internal rotation, respectively. In addition, the hip microinstability index increased from 0.40 ± 0.08 for intact hips to 0.55 ± 0.09 for modified hips ( P < .01). CONCLUSION: The native hip approximates a concentric ball-and-socket joint within 30° of flexion; however, beyond 30° of flexion, the femoral head translation reached as high as 4 mm. Capsular laxity leads to microinstability of the hip, as indicated by significantly increased joint rotations and femoral head translations and an abnormal movement path of the femoral head center. However, there was no correlation between rotational laxity and the increase in femoral head translation. CLINICAL RELEVANCE: Capsular laxity alters normal kinematics (joint rotation and femoral head translation) of the hip, potentially leading to abnormal femoral-acetabular contact and joint degeneration.

Hypothermia in Total Joint Arthroplasty: A Wake-Up Call.

BACKGROUND: Total joint patients are particularly vulnerable to perioperative hypothermia (PH) (combined effects of anesthesia, radiation, and convective heat loss from exposed skin surfaces and cool temperatures in the operating room). There are limited studies on PH in these patients. METHODS: In a retrospective review of 204 patients undergoing primary hip and 179 undergoing primary knee replacement surgeries, time and temperature parameters were collected from the electronic health records from preoperative and postoperative recovery room nursing assessments, intraoperative anesthesia records, and floor nursing notes. Basic patient demographic data was recorded. Chi-squared and paired t-tests were used to compare between hypothermic and normothermic groups. RESULTS: At the time of incision, 60 of 179 (34%) total knee arthroplasty (TKA) patients and 80 of 204 (39%) total hip arthroplasty (THA) patients were hypothermic. In THA patients, 65% remained hypothermic for the duration of anesthesia compared to 33% of TKA patients. The largest drop in core body temperature in both THA and TKA patients occurred between preoperative holding and induction of anesthesia. In THA patients, spinal anesthesia had a significantly higher occurrence of PH. No significant patient factor was found to increase risk. CONCLUSION: Emphasis on preoperative holding protocols, decreasing time from operating room entry to incision, and increasing ambient room temperature could reduce risk of hypothermia in total joint replacement patients.