Gout As a Predictor of Total Knee Arthroplasty Outcomes and Costs.

Gout is the most common inflammatory arthritis and affects approximately 4% of the U.S. population. As the prevalence of gout and the number of total knee arthroplasties (TKAs) performed continue to increase, the literature on TKA in patients with gout remains scant. The purpose of this study was to evaluate the outcomes of patients with gout following TKA at a population level, that is, how patient with gout fair after TKA. We hypothesized that patients with gout have higher rates of complications and higher costs compared with controls. A case-control study was designed to evaluate two cohorts of Medicare patients who underwent TKA whose only distinguishing feature was the presence or absence of gout. Matching was performed to decrease confounding at a 1:1 ratio based on age, gender, and Charlson comorbidity index (CCI), (10-year survival predictor). The Medicare standard analytical files were queried through International Classification of Disease and current procedural terminology codes. A total of 15,238 patients were evaluated with 7,619 in each cohort. There were no age, gender, or CCI differences and 57.4% were females. Day of surgery and 90-day post-surgery costs were both significantly greater in those with gout (p < 0.001 for both). Multivariate analysis revealed that gout patients had increased odds of infection (odds ratio [OR] 1.229, p = 0.019), cardiac arrest (OR 1.354, p = 0.002), pneumonia (OR 1.161, p < 0.001), hematoma (OR 1.204, p = 0.002), and development of capsulitis (OR 1.208, p = 0.012). Nonetheless these patients had a decreased risk of pulmonary emboli (OR 0.835, p = 0.016). Our results support our hypothesis that patients with gout have higher rates of postoperative complications and increased day of surgery and 90-day costs of care after TKA. Given the high prevalence of gout in the United States, additional study on the utility of preoperative gout optimization for TKA patients is warranted. The level of evidence of this study is III, and it is a retrospective case-control study.

Use of Adjunct Antiseptic Agents in Periprosthetic Joint Infections.

Periprosthetic joint infection is a leading cause for failure of contemporary total hip arthroplasty and total knee arthroplasty projected to nearly double in the next decade and reach an economic burden of $1.85 billion in the United Sates by 2030. Although multiple treatments for periprosthetic joint infection have been described, a thorough débridement and joint lavage to decrease bacterial bioburden and to remove biofilm remains a critical component of treatment. Various adjunct antiseptic agents such as chlorhexidine, povidone-iodine, hydrogen peroxide, acetic acid, and chlorine compounds are currently in off-label use in this capacity. Each antiseptic agent, however, has a distinct mechanism of action and targets different organisms, and some combinations of agents may lead to tissue toxicity. In this review, currently available adjunct antiseptic washes will be described in detail based on their mechanism of action and the evidence for their use will be reviewed. Furthermore, this review puts forward an evidence-based treatment algorithm based on the specific causative organism.

Addressing National Opioid Prescribing Practices for Knee Osteoarthritis: An Analysis of an Estimated 41,389,332 Patients With Knee Arthritis.

INTRODUCTION: Knee osteoarthritis (OA) is a chronic pathology that is treated across multiple specialties. Opioid prescribing practices for knee OA have not been described on a national level. The purpose of this study was to (1) investigate the trends in opioid prescriptions for knee OA, (2) characterize and identify predominant opioid based medications prescribed for knee OA, and (3) identify patient- and provider-related factors influencing opioid prescribing patterns in the treatment of knee OA in the outpatient setting. METHODS: The National Ambulatory Medical Care Survey (NAMCS) was used to identify all patients in the United States who presented to an outpatient clinic for knee OA between 2007 and 2016. New opioid prescriptions were determined using a previously published algorithm. Generalized linear models were used to assess trends. RESULTS: A total of 41,389,332 patients were included, of which 12.8% were prescribed an opioid-based medication. Opioid prescription rose from 2007/2008 to 2013/2014. Analysis of the opioid type demonstrated that the prescription of hydrocodone-based medication and "other" traditional opioids followed the aforementioned trends. However, tramadol prescription demonstrated a sustained increase throughout the years peaking at 2015/2016. Patient income in the lowest quartile, a worker's compensation status, and depression were independently associated with higher odds of opioid prescription for knee OA. CONCLUSIONS: Opioid prescription for knee OA remains high. Decreases in traditional opioid prescription have been countered by increase in tramadol prescription. The risks and addictive potential of tramadol and patient and provider risk factors should be emphasized.

A Matched Control Analysis on the Effects of Alcohol Use Disorder After Primary Total Knee Arthroplasty in Medicare Patients.

INTRODUCTION: Several studies have found the negative impact of alcohol use disorder (AUD), most notably coagulation derangements. We sought to investigate the effects of AUD after primary total knee arthroplasty (TKA) for (1) postoperative complications, (2) lengths of stay, and (3) costs of care. METHODS: This was a retrospective database analysis of Medicare patients with AUD undergoing primary TKA performed between 2005 and 2014. Patients with AUD were matched to controls in a 1:5 ratio by age, sex, and medical comorbidities. The query yielded 354,690 TKA patients: 59,126 with AUD and 295,564 without AUD. RESULTS: Patients with AUD had significantly greater odds ratio (OR) of medical complications, including venous thromboembolism (VTE) within 90 days (OR: 1.41, P < 0.0001) and at 1 year (OR: 1.51, P < 0.0001) and greater 2-year implant-related complications after primary TKA. Furthermore, patients with AUD had significantly longer lengths of stay (4 versus 3 days, P < 0.0001) and incurred a significantly higher episode of care costs ($15,569.76 versus $13,763.06, P < 0.0001). DISCUSSION: The present study demonstrated a significant association between AUD and the development of VTE. We hope this research will aid in risk stratification and tailoring of VTE chemoprophylaxis and postoperative management in this at-risk group after TKA. LEVEL OF EVIDENCE: Level III.

Synovial Cell Count Poorly Predicts Septic Arthritis in the Presence of Crystalline Arthropathy.

Introduction: A synovial cell count greater than 50,000/mm3 is the threshold most commonly used to diagnose septic arthritis. This lab value may be nonspecific in the setting of crystalline arthropathy. The purpose of this study was to evaluate the accuracy of diagnosing septic arthritis using a synovial cell count cut-off of 50,000/mm3 in the setting of crystalline arthropathy. Methods: This was a retrospective review of joint aspirations performed between July 1st, 2013 and June 30th, 2016. Synovial fluid samples were evaluated for cell count, crystals, Gram stain, and culture. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the synovial markers were calculated. Results: During the study period, 738 joint aspirations were sent for testing, of which 358 aspirations in 348 patients met inclusion criteria. There were 49 (13.7%) cases of culture-positive septic arthritis, and 47 patients underwent surgical irrigation and debridement. Gout and pseudogout crystals were present in 163 aspirates (45.5%). Three joints (0.8% overall rate) had concomitant crystalline arthropathy and septic arthritis, each of which had a synovial WBC ≥85,000/mm3. Increasing the WBC count cutoff to 85,000/mm3 demonstrated a specificity of 100%, but a PPV of 12.0%. Conclusions: A cut-off of 85,000/mm3 may be more appropriate to diagnose concomitant septic arthritis and crystalline arthropathy. We recommend medical management and observation in patients with crystal-positive joint aspirations unless the synovial cell count is elevated above 85,000/mm3. Prospective studies using this treatment guideline are needed to evaluate its validity and accuracy.

Distal Metaphyseal Osteotomy Allows for Greater Ulnar Shortening Compared to Diaphyseal Osteotomy for Ulnar Impaction Syndrome: A Biomechanical Study.

Purpose To compare the biomechanical characteristics between diaphyseal and metaphyseal ulnar-shortening osteotomy with respect to (1) maximal shortening achieved at each osteotomy site and (2) force required to achieve shortening at each site. Methods Nine fresh frozen cadaveric upper extremities were affixed through the proximal ulna to a wooden surgical board. A metaphyseal 20-mm bone wedge was resected from the distal ulna and sequential shortening was performed. A load cell was attached to a distal post that was clamped to the surgical board and used to measure the force required for each sequential 5-mm of shortening until maximal shortening was achieved. The resected bone was reinserted, and plate fixation was used to restore normal anatomy. A 20-mm diaphyseal osteotomy was performed, and force measurements were recorded in the same manner with (1) interosseous membrane intact, (2) central band released, and (3) extensive interosseous membrane and muscular attachments released. Results Metaphyseal osteotomy allowed greater maximal shortening than diaphyseal osteotomy with the interosseous membrane intact and with central band release but similar shortening when extensive interosseous membrane and muscle release was performed. Force at maximal shortening was similar between metaphyseal and diaphyseal osteotomy. Sequential soft tissue release at the diaphysis allowed for increased shortening with slightly decreased shortening force with sequential release. Conclusion Metaphyseal ulnar osteotomy allows greater maximal shortening but requires similar force compared with diaphyseal osteotomy. Sequential release of the interosseous membrane permits increased shortening at the diaphysis but requires extensive soft tissue release. Clinical Relevance Both sites of osteotomy can achieve sufficient shortening to decompress the ulnocarpal joint for most cases of ulnar impaction syndrome. The greater shortening from metaphyseal ulnar osteotomy may be reserved for severe cases of shortening, especially after distal radius malunion or in the setting of distal radius growth arrest in the pediatric population. Level of Evidence This is a Level V, basic science study.

Tendon Biomechanics and Crimp Properties Following Fatigue Loading Are Influenced by Tendon Type and Age in Mice.

In tendon, type-I collagen assembles together into fibrils, fibers, and fascicles that exhibit a wavy or crimped pattern that uncrimps with applied tensile loading. This structural property has been observed across multiple tendons throughout aging and may play an important role in tendon viscoelasticity, response to fatigue loading, healing, and development. Previous work has shown that crimp is permanently altered with the application of fatigue loading. This opens the possibility of evaluating tendon crimp as a clinical surrogate of tissue damage. The purpose of this study was to determine how fatigue loading in tendon affects crimp and mechanical properties throughout aging and between tendon types. Mouse patellar tendons (PT) and flexor digitorum longus (FDL) tendons were fatigue loaded while an integrated plane polariscope simultaneously assessed crimp properties at P150 and P570 days of age to model mature and aged tendon phenotypes (N = 10-11/group). Tendon type, fatigue loading, and aging were found to differentially affect tendon mechanical and crimp properties. FDL tendons had higher modulus and hysteresis, whereas the PT showed more laxity and toe region strain throughout aging. Crimp frequency was consistently higher in FDL compared with PT throughout fatigue loading, whereas the crimp amplitude was cycle dependent. This differential response based on tendon type and age further suggests that the FDL and the PT respond differently to fatigue loading and that this response is age-dependent. Together, our findings suggest that the mechanical and structural effects of fatigue loading are specific to tendon type and age in mice. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:36-42, 2020.

P2 porous titanium implants improve tendon healing in an acute rat supraspinatus repair model.

BACKGROUND: Current techniques in rotator cuff repair often lack structural integrity. P2 porous titanium-coated constructs (DJO Surgical, Austin, TX, USA) promote osseointegration and soft tissue ingrowth. This study examined the ability of this material to improve the structural integrity of supraspinatus tendon repair in a rat model. We hypothesized that P2 implants placed at the tendon-to-bone interface would improve mechanical and histologic measures of supraspinatus healing. METHODS: Forty rats underwent supraspinatus repairs with P2 implants in 1 shoulder and standard repair in the other. Rats were humanely killed at time 0 (n = 3), 2 weeks (n = 8), 4 weeks (n = 15), and 12 weeks (n = 14). Tendon-to-bone composite specimens were harvested and evaluated mechanically and histologically. RESULTS: Tendon cross-sectional area was decreased in the P2 implant group at 4 weeks, percentage of relaxation was increased at 2 weeks, elastic modulus was increased at 4 weeks, and maximum load and maximum stress were both increased at 2 and 4 weeks. Histologic analysis revealed no foreign body reactions within or around the P2 implant, and healthy viable bone was visible within the P2 implant. CONCLUSION: The results support our hypothesis, specifically in early healing, in this randomized controlled animal study. These data support the use of P2 porous titanium implants to improve tendon-to-bone healing.

Evaluating changes in tendon crimp with fatigue loading as an ex vivo structural assessment of tendon damage.

The complex structure of tendons relates to their mechanical properties. Previous research has associated the waviness of collagen fibers (crimp) during quasi-static tensile loading to tensile mechanical properties, but less is known about the role of fatigue loading on crimp properties. In this study (IACUC approved), mouse patellar tendons were fatigue loaded while an integrated plane polariscope simultaneously assessed crimp properties. We demonstrate a novel structural mechanism whereby tendon crimp amplitude and frequency are altered with fatigue loading. In particular, fatigue loading increased the crimp amplitude across the tendon width and length, and these structural alterations were shown to be both region and load dependent. The change in crimp amplitude was strongly correlated to mechanical tissue laxity (defined as the ratio of displacement and gauge length relative to the first cycle of fatigue loading assessed at constant load throughout testing), at all loads and regions evaluated. Together, this study highlights the role of fatigue loading on tendon crimp properties as a function of load applied and region evaluated, and offers an additional structural mechanism for mechanical alterations that may lead to ultimate tendon failure.

Regional modulation of a stochastically expressed factor determines photoreceptor subtypes in the Drosophila retina.

Stochastic mechanisms are sometimes utilized to diversify cell fates, especially in nervous systems. In the Drosophila retina, stochastic expression of the PAS-bHLH transcription factor Spineless (Ss) controls photoreceptor subtype choice. In one randomly distributed subset of R7 photoreceptors, Ss activates Rhodopsin4 (Rh4) and represses Rhodopsin3 (Rh3); counterparts lacking Ss express Rh3 and repress Rh4. In the dorsal third region of the retina, the Iroquois Complex transcription factors induce Rh3 in Rh4-expressing R7s. Here, we show that Ss levels are controlled in a binary on/off manner throughout the retina yet are attenuated in the dorsal third region to allow Rh3 coexpression with Rh4. Whereas the sensitivity of rh3 repression to differences in Ss levels generates stochastic and regionalized patterns, the robustness of rh4 activation ensures its stochastic expression throughout the retina. Our findings show how stochastic and regional inputs are integrated to control photoreceptor subtype specification in the Drosophila retina.

Contralateral deep venous thrombosis after hip arthroscopy.

Since the 1980s, hip arthroscopy has become an accepted treatment modality for a variety of hip conditions. It is generally considered a low-risk procedure with a low rate of complications. The risk of developing a deep venous thrombosis (DVT) or venous thromboembolism following these procedures is also thought to be low, and most patients undergoing these procedures receive no pharmacologic prophylaxis postoperatively. This article presents a case of a 33-year-old woman with a history of oral contraceptive use who presented 13 days after a routine hip arthroscopy with pain and swelling in the contralateral thigh. Ultrasonography revealed acute DVTs in the left common femoral, superficial femoral, and popliteal veins. She was admitted to the hospital and treated accordingly. A workup for thrombophilic disorders was negative. We believe that her history of oral contraceptive use, the use of axial traction, and asymmetric forces about the pelvis during the procedure contributed to this postoperative complication. Although this complication is rare and the use of pharmacologic prophylaxis is not common, physicians must be aware of this potential complication following hip arthroscopy.