A novel co-culture model of murine K12 osteosarcoma cells and S. aureus on common orthopedic implant materials: 'the race to the surface' studied in vitro.

Infection is a major cause of orthopedic implant failure. There are few studies assessing both tissue cell and bacterial adherence on common orthopedic implant materials in a co-culture environment. An in vitro co-culture model was created using K12 osteosarcoma cells and Staphylococcus aureus in a medium incubated over metal disks for 48 h. The results showed that, in the presence of S. aureus, there were fewer osteosarcoma cells attached to the disks for all substrata tested. There were significantly more osteosarcoma cells adhering to the cobalt chrome than the stainless steel and titanium disks. Overall, in the presence of osteosarcoma cells, there were more bacteria adhering to the disks for all the substrata tested, with significantly more bacteria adhering to the stainless steel disks compared to cobalt chrome and titanium disks. Scanning electron microscopy verified that osteosarcoma cells and bacteria were adherent to the metal disks after incubation for 48 h. Furthermore, the observation that more bacteria were in the co-culture than in the control sample suggests that the osteosarcoma cells serve as a nutrient source for the bacteria. Future models assessing the interaction of osteogenic cells with bacteria on a substratum would be improved if the model accounted for the role of the immune system in secondary bone healing.

Factors influencing the outcome of autologous chondrocyte implantation: a systematic review.

Autologous chondrocyte implantation (ACI) is an effective method of treatment of chondral defects of the knee. ACI outcomes are influenced by patient-, knee-, and lesion-specific factors. We compiled subject-level data from current studies on ACI and quantitatively analyzed this data set for associations between patient-, knee-, and lesion-specific factors and the outcome of ACI surgery. A systematic review of studies investigating ACI treatment outcomes in the knee was performed. Only studies that published subject-level data were included. Data on patient and lesion characteristics, as well as clinical outcome scores, were collected. Thirteen studies (305 defects) were included in this review. These studies showed that ACI treatment improves clinical outcomes in different patient populations. However, subject-specific variables such as patient age, gender, body mass index, duration of preoperative symptoms, as well as defect size and location were not associated with International Knee Documentation Committee score or visual analog scale score changes (p > 0.05 for all). Covariate analysis showed that patient age was related to symptom duration prior to surgery (p = 0.009). ACI surgery has been shown to improve outcomes in patients with chondral lesions of the knee. Despite evidence in the literature showing that multiple patient-, knee-, and lesion-specific factors may influence treatment outcomes, our review shows that these factors, solely, do not affect outcomes. However, together, they may synergistically affect outcomes.

Continuous passive motion following cartilage surgery: does a common protocol exist?

Continuous passive motion (CPM) devices have the potential to improve the histological content as well as the rate and volume of chondrogenesis in repair tissue following chondral injury. However, clinical evidence is lacking to support broad implementation of CPM following cartilage restoration procedures. We searched PubMed, CINAHL, SPORTDiscus, and Cochrane for such terms as knee, continuous passive motion, CPM, ACI, ACT, autologous chondrocyte implantation, autologous chondrocyte transplantation, microfracture, marrow-stimulation technique, mosaicplasty, osteochondral autograft, and osteochondral allograft. Inclusion criteria were all English-language studies of human subjects, evidence levels I to IV, reporting the use of CPM following cartilage repair or restoration surgery in the knee. One hundred and seven studies met inclusion criteria. Sixty-three studies reported the use of CPM following autologous chondrocyte implantation; 28 reported the use of CPM following microfracture; 13 reported the use of CPM following osteochondral autograft; and 15 reported the use of CPM following osteochondral allograft (several studies reported > 1 type of cartilage procedure, which explains why the sum of all studies reporting a particular procedure [119] is greater than the number of studies included in the review [107]). Of the 5723 patients included, 60.8% were treated with autologous chondrocyte implantation, 23.1% were treated with microfracture, 6.4% were treated with osteochondral autograft, and 9.7% were treated with osteochondral allograft. Of the 6612 total defects, 5043 (76.3%) were tibiofemoral and 1569 (23.7%) were patellofemoral. Most reports of CPM use after cartilage restoration procedures did not include specific information on how it was implemented. Overall, the description of CPM protocols in published knee articular cartilage surgery studies was disappointing. The majority of studies did not describe common variables such as the duration of CPM therapy, the initiation of CPM therapy, and the initial range of motion used. The most commonly prescribed parameters within a CPM regimen are initiated on the first postoperative day, with an initial range-of-motion of 0 to 30 degrees and a frequency of 1 cycle per minute, and for 6 to 8 hours daily over 6 weeks. The lack of consistent standardized reporting of postoperative CPM protocols provides an impetus to researchers and clinicians to more clearly define and describe their use following knee articular surgery.

Articulating antibiotic spacers: the standard of care for an infected total knee arthroplasty.

Comparisons in the literature of static and articulating spacers have shown average eradication rates of approximately 90% and 92%, respectively. Therefore, we can conclude that static and articulating spacers are both effective for eradication of infection. The benefits of articulating spacers are prevention of soft-tissue contracture, promotion of range of motion, and facilitation of antibiotic delivery.

Novel rat tail discitis model using bioluminescent Staphylococcus aureus.

Management of spondylodiscitis is a challenging clinical problem requiring medical and surgical treatment strategies. The purpose of this study was to establish a rat model of spondylodiscitis that utilizes bioluminescent Staphylococcus aureus (S. aureus), thus permitting in vivo surveillance of infection intensity. Inocula of the bioluminescent S. aureus strain XEN36 were created in concentrations of 102 CFU/0.1 ml, 104 CFU/0.1 ml, and 106 CFU/0.1 ml. Three groups of rats were injected with the bacteria in the most proximal intervertebral tail segment. The third most proximal tail segment was injected with saline as a control. Bioluminescence was measured at baseline, 3 days, and weekly for a total of 6 weeks. Detected bioluminescence for each group peaked at day 3 and returned to baseline in 21 days. The average intensity was highest for the experimental group injected with the most concentrated bacterial solution (106 CFU/0.1 ml). Radiographic analysis revealed loss of intervertebral disc space and evidence of osseous bridging. Saline-injected spaces exhibited no decrease in intervertebral spacing as compared to distal sites. Histologic analysis revealed neutrophilic infiltrates, destruction of the annulus fibrosus and nucleus pulposus, destruction of vertebral endplates, and osseous bridging. Saline-injected discs exhibited preserved annulus fibrosus and nucleus pulposus on histology. This study demonstrates that injection of bioluminescent S. aureus into the intervertebral disc of a rat tail is a viable animal model for spondylodiscitis research. This model allows for real-time, in vivo quantification of infection intensity, which may decrease the number of animals required for infection studies of the intervertebral disc. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2075-2081, 2017.

Surgeon Specialty Influences Referral Rate for Osteoporosis Management following Vertebral Compression Fractures.

STUDY DESIGN: Retrospective chart review. OBJECTIVE: To evaluate the referral rate for long-term osteoporosis management following vertebral compression fracture treated by different specialties at a single academic institution. METHODS: Patients undergoing vertebral cement augmentation for painful osteoporotic compression fractures from 2009 to 2014 were identified. Medical records were reviewed to determine if the treating surgeon discussed and/or referred the patient for long-term osteoporosis management. Any referral for or mention of medical long-term osteoporosis management was counted as a positive response. Results were statistically analyzed with chi-square test. RESULTS: Two hundred fourteen patients underwent vertebral cement augmentation; 150 met inclusion criteria. Orthopedic surgeons treated 88 patients, neurosurgeons treated 39, and interventional radiology or pain management physicians treated 23. Orthopedic surgeons referred 82% of patients for osteoporosis management, neurosurgeons referred 36%, and interventional radiology/pain management referred 17%. The referral rate was significantly higher for orthopedic surgeons compared with either of the other two groups; there was no significant difference between neurosurgery and interventional radiology/pain management. CONCLUSIONS: Among physicians who treat osteoporotic vertebral compression fractures, orthopedic surgeons more frequently address osteoporosis or refer patients for osteoporosis management compared with neurosurgeons and interventional radiologists or pain management physicians. The results of this study shed light on the disparity in how different specialties approach treatment of osteoporosis in patients with fractures painful enough to require surgery and highlight potential areas for improvement in osteoporosis awareness training.

Multiple roles of tumor necrosis factor-alpha in fracture healing.

This review presents a summary of basic science evidence examining the influence of tumor necrosis factor-alpha (TNF-α) on secondary fracture healing. Multiple studies suggest that TNF-α, in combination with the host reservoir of peri-fracture mesenchymal stem cells, is a main determinant in the success of bone healing. Disease states associated with poor bone healing commonly have inappropriate TNF-α responses, which likely contributes to the higher incidence of delayed and nonunions in these patient populations. Appreciation of TNF-α in fracture healing may lead to new therapies to augment recovery and reduce the incidence of complications.

Is orthopedics more competitive today than when my attending matched? An analysis of National Resident Matching Program data for orthopedic PGY1 applicants from 1984 to 2011.

OBJECTIVE: This study evaluated supply and demand trends for orthopedic postgraduate year 1 (PGY1) positions from 1984 to 2011 for the purpose of estimating national intercandidate competition over time. DESIGN: National Resident Matching Program (NRMP) data for orthopedic surgery from 1984 to 2011 were collected. Proxy variables including (total number of orthopedic applicants/number of orthopedic PGY1 positions), (number of US senior applicants to orthopedics/number of orthopedic PGY1 positions), (number of US seniors matching into orthopedics/number of US senior orthopedic applicants), (total number of matched orthopedic applicants/total number of orthopedic applicants), and (total number of US applicants who fail to match into orthopedics/total number of US senior applicants into orthopedics) as well as average United States Medical Licensing Examination Step 1 scores were used to gauge the level of competition between candidates and were compared over time. SETTING: Academic medical center in the Midwestern United States. PARTICIPANTS: Medical professors and medical students. RESULTS: The NRMP data suggested that the number of positions per applicant decreased or remained stable since 1984 and that the percentage of applicants who did not match was no higher now than in the past. This finding was primarily because of the relative decrease in the ratio of applicants to available PGY1 positions, which stems from the number of positions increasing more rapidly than the number of applicants. CONCLUSIONS: The NRMP data from 1984 to 2011 supported our hypothesis that intercandidate competition intensity for orthopedic PGY1 positions has not increased over time. The misconception that orthopedics is becoming more competitive likely arises from the increased number of applications submitted per candidate and the resulting relative importance placed on objective criteria such as United States Medical Licensing Examination Step 1 scores when programs select interview cohorts.

A motion maintaining antibiotic delivery system.

Two-stage radical debridement with implant removal, antibiotic therapy, and delayed reimplantation remains the treatment of choice for deep infection in total joint arthroplasty. Studies have shown that articulating vs static spacers better improve functional results, increase patient satisfaction, prevent bone loss, and facilitate reimplantation without increasing risk of infection. Articulating spacers fabricated from cement provide a vehicle for prolonged local delivery of antibiotics. We currently use a mold system for creating antibiotic-laden articulating cement spacers. Disposable femoral and tibial molds are injection-filled with low-viscosity cement vacuum mixed with 3.6 to 4.8 g of tobramycin or gentamicin and 3.0 to 4.0 g of vancomycin per 40-g unit and massaged to fill any voids. After curing, the temporary spacers are removed from the molds, trimmed smooth, and cemented loosely into the joint space.