Montri D. Wongworawat

New Definition for Periprosthetic Joint Infection: From the Workgroup of the Musculoskeletal Infection Society

Based on the proposed criteria, definite PJI exists when: (1) There is a sinus tract communicating with the prosthesis; or (2) A pathogen is isolated by culture from at least two separate tissue or fluid samples obtained from the affected prosthetic joint; or (3) Four of the following six criteria exist: (a) Elevated serum erythrocyte sedimentation rate (ESR) and serum C-reactive protein (CRP) concentration, (b) Elevated synovial leukocyte count, (c) Elevated synovial neutrophil percentage (PMN%), (d) Presence of purulence in the affected joint, (e) Isolation of a microorganism in one culture of periprosthetic tissue or fluid, or (f) Greater than five neutrophils per high-power field in five high-power fields observed from histologic analysis of periprosthetic tissue at ×400 magnification. PJI may be present if fewer than four of these criteria are met.

High-pressure pulsatile lavage propagates bacteria into soft tissue

Initial wound treatment is critical in the treatment of open fractures, contaminated wounds, and abscesses.19 Ample evidence suggests that high-pressure pulsatile lavage damages bone structure and disrupts soft tissue. We compared the depth of penetration and amount of retention of bacteria in contaminated soft tissue subjected to one of two lavage methods: high-pressure pulsatile and low-pressure gravity flow. Fresh ovine muscle was harvested, contaminated with fluorescently stained Staphylococcus aureus, and subjected to lavage treatment. Specimens in each lavage method group were subdivided based on orientation across or in line with the muscle fibers. High-pressure lavage causes increased depth of bacterial penetration (across: 3,835 μm; in line: 4,220 μm) when compared with low-pressure lavage (across: 1,680 μm; in line: 2,095 μm). Furthermore, both high-pressure treatment groups had higher numbers of retained bacteria as counted in 50 μm × 7,500 μm × 5 μm sections of tissue after lavage (across: 197; in line: 188) when compared with the low-pressure groups (across: 94; in line: 40). These results show that high-pressure pulsatile lavage causes deeper penetration of bacteria and results in greater bacterial retention in soft tissue when compared with low-pressure lavage.

Accuracy in the Measurement of Compartment Pressures: A Comparison of Three Commonly Used Devices

BACKGROUND In situations in which accurate physical diagnosis is inconclusive, an objective method for measuring compartment pressure can aid in the diagnosis of compartment syndrome. Previous studies have compared measurement devices with each other but not with an accurately determined gold standard. The purpose of the present study was to devise a reproducible in vitro model of compartment pressure and to compare commonly used measurement devices in order to determine their accuracy. METHODS With a graduated cylinder being used to generate a known pressure, freshly harvested ovine muscle was placed into a chamber for testing. The cylinder was incrementally filled with saline solution (in fifty-five steps), and measurements of tissue pressure were obtained with use of the Stryker Intracompartmental Pressure Monitor System, an arterial line manometer, and the Whitesides apparatus. Each device was tested with a straight needle, a side-port needle, and a slit catheter, for a total of nine setups in all. Five trials were done with each setup. Control pressures were calculated on the basis of the height of the saline solution column (test range, 0.13 to 10.80 kPa). Multiple regression analysis was used to compare measured tissue pressures with calculated control pressures. RESULTS Most methods demonstrated excellent correlation (R2> 0.95) between calculated and measured pressures. The arterial line manometer with the slit catheter showed the best correlation (R2= 0.9978), and the Whitesides apparatus with the side-port needle showed the worst (R2= 0.9115). Furthermore, the Stryker system with the side-port needle demonstrated the least constant bias (+0.06 kPa). Straight needles tended to overestimate pressure. Two of the three needle configurations involving the Whitesides apparatus overestimated pressure. The data for the Whitesides methods had the highest standard errors, showing clinically unacceptable scatter. CONCLUSION Side-port needles and slit catheters are more accurate than straight needles are. The arterial line manometer is the most accurate device. The Stryker device is also very accurate. The Whitesides manometer apparatus lacks the precision needed for clinical use.

Editorial: Fairness to all: Gender and sex in scientific reporting

Women do not benefit from medical research as much as men do [2, 5]. This problem stems both from research design (which scientists largely control), and from scientific reporting in journals (which editors can influence). Starting with the latter, we first must learn to talk about sex. Sex (female or male) refers to the genotype, while gender (woman or girl, man or boy) refers to the social constructs that overlie the genotype. Gender tends to be culturally laden, and as such, separating sex from gender in certain kinds of research is nearly impossible. Do women as a cultural norm have less pain after knee replacement, or is it a condition innate to the biology of the female sex? If the former, might this be driven by women reporting pain differently on standardized scoring instruments (or to their surgeons, who are more likely to be men)? Or are there important physiological differences in pain signaling between males and females? Other explanations are possible — for example, it is likely that women’s responses are interpreted differently by surgeons of either gender — and it is not always possible to know whether sex, gender, or both account for the observed effect. But when possible, we will seek clarity in authors’ explanations: Are the differences gender-driven, sex-driven, or is it not possible to tell? This is not just a semantic issue. It is a health issue, both for women and men. Women have been underrepresented in medical research, and therefore the evidence that drives their care is less robust [2, 5]. Pharmacokinetics and responses to important therapeutic interventions differ between men and women [3], and women are more likely to experience adverse drug reactions [6]. Surgeons may believe this is a “medical thing” and not a problem in orthopaedic surgery. That is wrong. Women consume approximately 85% of the Cox-II-specific NSAIDs that are prescribed and the side effect profiles of these drugs — including important, life-threatening side effects — differ between men and women [6]. Yet, the treatment of women with NSAIDs is based on Cox-II trials consisting disproportionately of men [1]. We learned only belatedly that women are at much greater risk of complications and failure after total hip resurfacing arthroplasty [4], and the result suggests that clearer scientific reporting would have prevented harm to many women. We probably do not know the full extent of the harm we may be causing because the reporting of results by gender is so inconsistently performed in medical and surgical trials in our specialty. This must change. Accordingly, we recommend that investigators writing for CORR®: Design studies that are sufficiently powered to answer research questions both for males and females (or men and women) if the health condition being studied occurs in both sexes/genders. Provide sex- and/or gender-specific data where relevant in all clinical, basic science, and epidemiological studies. Analyze the influence (or association) of sex or gender on the results of the study, or indicate in the Patients and Methods section why such analyses were not performed, and consider this topic as a limitation to cover in the Discussion section. Readers need to know whether the results generalize to both sexes/genders. Indicate (if sex or gender analyses were performed post-hoc) that these analyses should be interpreted cautiously because they may be underpowered (leading to a false conclusion of no difference). If there are many such analyses, indicate that they may lead to spurious significance, and an erroneous conclusion of a sex- or gender-related difference. We present these as recommendations, rather than requirements for publication because the topic is relatively new to the collective consciousness of our specialty. Our editorial board will continue to evaluate whether and when guidelines like these should become requirements. For now, we will consider the scientific reporting of sex- and gender-related findings an important element of the papers we consider for publication. Our research needs to reflect that we treat both men and women, and that both are equally entitled to the benefits of care based on good, applicable evidence.

Biomechanical Characteristics of 9 Arthroscopic Knots

PURPOSE To determine the optimal arthroscopic slipknot through comparison of ease of placement, loop security, knot security, and amount of suture material needed using a new suture material. METHODS Nine commonly used arthroscopic knots (Dines, Field, Nicky, Hu, San Diego, Snyder, Tennessee slider, Triad, and Tuckahoe) were tested by use of modern suture material, FiberWire (Arthrex, Naples, FL), with the Instron materials testing machine (Instron, Norwood, MA) for ease of knot placement (forward and backward sliding), loop security, and knot security. The amount of suture material needed to create the knot was compared by use of the knot weight. Analysis of variance with Kruskal-Wallis analysis and Bonferroni correction (alpha < .01) was used to compare different knots. RESULTS The Tennessee slider knot sustained the greatest force at failure (269 N), the greatest knot resistance (32 N), and the smallest mass (8.5 mg). The Dines was the only knot superior in all 3 knot placement categories. The Nicky held the most loop force (66 N), and the Tuckahoe had the greatest loop resistance (20 N) (P < .01 for all except mass [P < .05]). CONCLUSIONS Our study comprehensively presents ease-of-placement and security characteristics of 9 common and new arthroscopic knots using modern FiberWire suture. The Tennessee slider knot showed superior characteristics in knot security and knot mass. The Dines knot was the most ideal knot to place. However, the surgeon will need to review the individual knot characteristics and select the knot most suited to application. CLINICAL RELEVANCE This study analyzed 9 arthroscopic knots with modern suture material and identified those with superior characteristics.

Evaluation of simple and looped suture and new material for flexor tendon repair.

Flexor tendon repair strength is proportional to the number of suture strands crossing the repair site but it is not clear if each strand needs to result from a separate pass through the tendon. We examined whether one throw of looped suture across a repair site equals two separate throws of suture and whether fewer passes with stronger material such as Fiberwire is equivalent to more passes with a comparatively weaker material such as Supramid. When evaluating the repairs for force required to generate a 2 mm gap and for gap formed at the instant prior to failure, looped suture cannot substitute for two separate passes of suture (Supramid Kessler looped vs. separate passes, 14 N vs. 35 N and 8.8 mm vs. 4.1 mm, respectively; Fiberwire Kessler looped vs. separate passes, 25 N vs. 43 N and 7.6 mm vs. 4.6 mm, respectively; all p<0.05). Two-stranded Fiberwire Kessler repair equalled four-stranded cruciate repair with Supramid for all tested parameters (force at 2 mm gap: 17 N vs. 22 N, respectively; force at failure: 42 N vs. 46 N; and gap formed prior to instant of failure: 6.9 mm vs. 5.6 mm; all p>0.05).

The Roles and Mechanisms of Actions of Vitamin C in Bone: New Developments

Vitamin C is an important antioxidant and cofactor that is involved in the regulation of development, function, and maintenance of several cell types in the body. Deficiencies in vitamin C can lead to conditions such as scurvy, which, among other ailments, causes gingivia, bone pain, and impaired wound healing. This review examines the functional importance of vitamin C as it relates to the development and maintenance of bone tissues. Analysis of several epidemiological studies and genetic mouse models regarding the effect of vitamin C shows a positive effect on bone health. Overall, vitamin C exerts a positive effect on trabecular bone formation by influencing expression of bone matrix genes in osteoblasts. Recent studies on the molecular pathway for vitamin C actions that include direct effects of vitamin C on transcriptional regulation of target genes by influencing the activity of transcription factors and by epigenetic modification of key genes involved in skeletal development and maintenance are discussed. With an understanding of mechanisms involved in the uptake and metabolism of vitamin C and knowledge of precise molecular pathways for vitamin C actions in bone cells, it is possible that novel therapeutic strategies can be developed or existing therapies can be modified for the treatment of osteoporotic fractures.

The accuracy of the saline load test in the diagnosis of traumatic knee arthrotomies.

Objectives: When open joint injury is suspected in a knee laceration, the saline load test has been recommended as a diagnostic modality, especially in small wounds, where inspection and palpation cannot confirm joint violation. The goals of this study are: 1) to correlate fluid volume needed for positive diagnosis with demographic factors, 2) to assess the sensitivity of using the commonly recommended volume of 50 mL, and 3) to identify the minimum fluid volume necessary to obtain 95% sensitivity. Design: Prospective cohort. Setting: University medical center. Patients/Participants: Thirty consecutive patients scheduled for elective outpatient knee arthroscopy were prospectively enrolled. Exclusion criteria include history of open traumatic injury, presence of active infection, or limited range of motion as evidence of arthrofibrosis. Intervention: A standard lateral parapatellar portal was made with a no. 11 blade scalpel, and a 5.8 mm diameter cannula-trochar was inserted and withdrawn to create a standard arthrotomy size of 26.4 mm2. Using an 18-gauge needle, saline was injected through a separate lateral suprapatellar site until outflow was noted. Main Outcome Measurements: Upon fluid outflow, the volume of injected saline was recorded. Results: The volume injected until outflow was similar between men and women (P = 0.87). No correlation was observed between the volume injected and age (P = 0.85), height (P = 0.18), weight (P = 0.46), and body mass index (P = 0.91). Injection of 50 mL successfully identified only 46% of known arthrotomies. A saline load of 194 mL was required to achieve 95% sensitivity. Conclusions: For small lacerations around the knee, saline loads of less than 194 mL are of questionable sensitivity, and surgeons should not use the saline load test to rule out open knee injuries.

Biomechanical Comparison of Krackow Locking Stitch Versus Nonlocking Loop Stitch With Varying Number of Throws

Background: Common suture configuration techniques used for ligament and tendon grafts and repair are the Krackow locking stitch and a nonlocking loop stitch, such as a whipstitch. Clinically, the preferences of orthopaedic surgeons vary. Hypothesis: The Krackow locking stitch and the nonlocking whipstitch, with varying suture loops, produce different biomechanical and physical effects on the tendon end. Study Design: Controlled laboratory study. Methods: A total of 52 fresh-frozen porcine flexor digitorum tendons were used and assigned into 10 groups. Two stitch configurations (Krackow stitch [K] and whipstitch [W]) with varying number of loops (2 throws, n = 6; 4 throws, n = 5; 6 throws, n = 5; 8 throws, n = 5; 10 throws, n = 5) were tested. No. 2 FiberWire was used. Each sample was preloaded to 5 N and then cyclically loaded for 200 cycles to 200 N at 1 Hz, and then the tendon-suture construct was analyzed for gap formation, tendon elongation, and tendon end width. Next, each tendon was loaded to failure, and ultimate strength and mode of failure were recorded. Data were evaluated with 2-way analysis of variance. Results: For gap formation, the Krackow stitch produced less gap compared with the whipstitch (15.2 ± 4.0 mm [K] vs 18.9 ± 6.8 mm [W]; P = .012). Gap formation was larger when the number of loops increased from 2 to ≥6 (P = .015). For elongation, the Krackow technique increased the tendon length after cyclic loading. In contrast, the whipstitch was noted to shorten the length of the tendon (1.17 ± 0.97 mm [K] vs −0.14 ± 1.13 mm [W]; P < .001). For tendon end width, the Krackow better preserved the transverse width (–0.64 ± 0.81 mm [K] vs −1.39 ± 0.64 mm [W]; P = .001). Both stitch types had similar ultimate strength (322.1 ± 20.3 N [K] vs 319.7 ± 20.4 N [W]; P = .676) and modes of failure (all by suture breakage; therefore, no statistical calculation was performed). There was no statistical difference in tendon elongation, width, failure load, or mode regardless of the number of throws. Conclusion/Clinical Relevance: Given the finding that the Krackow suture had less gap formation and better preservation of tendon architecture (length and width) compared with the whipstitch, coupled with the finding that ultimate strength is similar with both types of sutures, the Krackow stitch is recommended for tendon reconstruction when these parameters are important.

Failure of a new intramedullary device in fixation of clavicle fractures: a report of two cases and review of the literature

Operative fixation is gaining popularity in the treatment of displaced midshaft clavicle fractures. Plates have traditionally been used in the surgical stabilization of these fractures. External fixators are rarely used, mainly being used in cases of open clavicular fracture or septic nonunion. Intramedullary devices behave as internal splints that maintain alignment of the fracture without rigid fixation. They are theoretically advantageous when compared with plate/screw devices because they entail minimal soft-tissue dissection and periosteal stripping, shorter hospital stays, cosmetic surgical exposure, and no skin prominence at the fracture site, and they avoid stress shielding. Intramedullary devices are now becoming streamlined to the anatomic specificities of the clavicle. The sigmoid shape of the clavicle dictates that intramedullary clavicle pins must be narrow and flexible enough to be installed through the curved medullary canal. The Sonoma CRx intramedullary clavicular pin (Sonoma Orthopedic Products, Santa Rosa, CA) is a new clavicle fixation pin that addresses the challenges of intramedullary fixation with a flexible head, grippers, and a buttressing screw. The flexible head contains grippers that extend within the medial fragment once the device is in place. Activation of the grippers transforms the flexible head into a rigid structure shaped according to the anatomic contours of the medullary canal. The locking screw is