Prophylactic antibiotics are important in reducing the risk of periprosthetic joint infection (PJI) following total knee arthroplasty. Their effectiveness depends on the choice of antibiotic and the optimum timing of their administration, to ensure adequate tissue concentrations. Cephalosporins are typically used, but an increasing number of resistant organisms are causing PJI, leading to the additional use of vancomycin. There are difficulties, however, with the systemic administration of vancomycin including its optimal timing, due to the need for prolonged administration, and potential adverse reactions. Intraosseous regional administration distal to a tourniquet is an alternative and attractive mode of delivery due to the ease of obtaining intraosseous access. Many authors have reported the effectiveness of intraosseous prophylaxis in achieving higher concentrations of antibiotic in the tissues compared with intravenous administration, providing equal or enhanced prophylaxis while minimizing adverse effects. This annotation describes the technique of intraosseous administration of antibiotics and summarizes the relevant clinical literature to date. Cite this article: Bone Joint J 2023;105-B(11):1135–1139

Aims. This study aimed to explore the role of small colony variants (SCVs) of Staphylococcus aureus in intraosseous invasion and colonization in patients with periprosthetic joint infection (PJI). Methods. A PJI diagnosis was made according to the MusculoSkeletal Infection Society (MSIS) for PJI. Bone and tissue samples were collected intraoperatively and the intracellular invasion and intraosseous colonization were detected. Transcriptomics of PJI samples were analyzed and verified by polymerase chain reaction (PCR). Results. SCVs can be isolated from samples collected from chronic PJIs intraoperatively. Transmission electron microscopy (TEM) and immunofluorescence (IF) showed that there was more S. aureus in bone samples collected from chronic PJIs, but much less in bone samples from acute PJIs, providing a potential mechanism of PJI. Immunofluorescence results showed that SCVs of S. aureus were more likely to invade osteoblasts in vitro. Furthermore, TEM and IF also demonstrated that SCVs of S. aureus were more likely to invade and colonize in vivo. Cluster analysis and principal component analysis (PCA) showed that there were substantial differences in gene expression profiles between chronic and acute PJI. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that these differentially expressed genes were enriched to chemokine-related signal pathways. PCR also verified these results. Conclusion. Our study has shown that the S. aureus SCVs have a greater ability to invade and colonize in bone, resulting in S. aureus remaining in bone tissues long-term, thus explaining the pathogenesis of chronic PJI. Cite this article: Bone Joint Res 2022;11(12):843–853

Aims

The preoperative grading of chondrosarcomas of bone that accurately predicts surgical management is difficult for surgeons, radiologists, and pathologists. There are often discrepancies in grade between the initial biopsy and the final histology. Recent advances in the use of imaging methods have shown promise in the ability to predict the final grade. The most important clinical distinction is between grade 1 chondrosarcomas, which are amenable to curettage, and resection-grade chondrosarcomas (grade 2 and 3) which require en bloc resection. The aim of this study was to evaluate the use of a Radiological Aggressiveness Score (RAS) to predict the grade of primary chondrosarcomas in long bones and thus to guide management.

The ability to assess the blood flow to a bone (IBF) is important for orthopaedic surgeons when deciding the fate of an injured or diseased bone. Currently there is no easy and effective method for quickly assessing the blood flow status of a bone. There is accumulating evidence that suggests that IBF may be correlated to intraosseous pressure (IOP). Therefore, we aimed to investigate whether the two variables are correlated so that the orthopaedic surgeon could confidently use IOP as an indicator of IBF. Using 8 mature female ewes (B.W. ~56 kg) we measured cardiovascular (eg. arterial blood pressure – ABP), and intraosseous (ie. IOP and IBF) responses to nor-adrenaline (0–1.5 μg/kg/min. i.v.) and nitroglycerine (0–80 μg/kg. i.v.) IBF was measured using semi-quantitative technique of laser Doppler flowmetry (LDF). Our results revealed that changes in ABP were directly correlated to changes in IOP (p < 0.001). Due to technical difficulties that were encountered when using LDF, the collected IBF data were limited. However, there was compelling evidence that there is a positive and direct correlation between IBF and IOP. This opens an exciting possibility of using IOP for quickly and accurately assessing IBF as well as providing insight into the pathological mechanisms responsible for bone and joint disorders

Background. Systemically administered vancomycin may provide insufficient target-site concentrations. Intraosseous vancomycin administration has the potential to overcome this concern by providing high target-site concentrations. Aim. To evaluate the local bone and tissue concentrations following tibial intraosseous vancomycin administration in a porcine model. Method. Eight female pigs were assigned to receive 500 mg diluted vancomycin (50 mg/mL) through an intraosseous cannula into the proximal tibial cancellous bone. Microdialysis was applied for sampling of vancomycin concentrations in tibial cancellous bone adjacent to the intraosseous cannula, in cortical bone, in the intramedullary canal of the diaphysis, in the synovial fluid of the knee joint, and in the subcutaneous tissue. Plasma samples were obtained. Samples were collected for 12 hours. Results. High vancomycin concentrations were found in the tibial cancellous bone with a mean peak drug concentration of 1,236 (range 28–5,295) µg/mL, which remained high throughout the sampling period with a mean end concentration of 278 (range 2.7–1,362.7) µg/mL after 690 min. The mean (standard derivation (SD)) peak drug concentration in plasma was 19 (2) µg/mL, which was obtained immediately after administration. For the intramedullary canal, in the synovial fluid of the knee joint, and subcutaneous tissue, comparable mean peak drug concentration and mean time to peak drug concentration were found in the range of 7.5–8.2 µg/mL and 45–70 min, respectively. Conclusions. Tibial intraosseous administration of vancomycin provided high mean concentrations in tibial cancellous bone throughout a 12-hour period, but with an immediate and high systemic absorption. The concentrations in cancellous bone had an unpredictable and wide range of peak concentration. Low mean concentrations were found in all the remaining compartments. Our findings suggest that intraosseous vancomycin administration in proximal tibial cancellous bone only is relevant as treatment in cases requiring high local concentrations nearby the intraosseous cannula

Objectives. We studied subchondral intraosseous pressure (IOP) in an animal model during loading, and with vascular occlusion. We explored bone compartmentalization by saline injection. Materials and Methods. Needles were placed in the femoral condyle and proximal tibia of five anaesthetized rabbits and connected to pressure recorders. The limb was loaded with and without proximal vascular occlusion. An additional subject had simultaneous triple recordings at the femoral head, femoral condyle and proximal tibia. In a further subject, saline injections at three sites were carried out in turn. Results. Loading alone caused a rise in subchondral IOP from 11.7 mmHg (. sd. 7.1) to 17.9 mmHg (. sd. 8.1; p < 0.0002). During arterial occlusion, IOP fell to 5.3 mmHg (. sd. 4.1), then with loading there was a small rise to 7.6 mmHg (. sd. 4.5; p < 0.002). During venous occlusion, IOP rose to 20.2 mmHg (. sd. 5.8), and with loading there was a further rise to 26.3 mmHg (. sd. 6.3; p < 0.003). The effects were present at three different sites along the limb simultaneously. Saline injections showed pressure transmitted throughout the length of the femur but not across the knee joint. Conclusion. This is the first study to report changes in IOP in vivo during loading and with combinations of vascular occlusion and loading. Intraosseous pressure is not a constant. It is reduced during proximal arterial occlusion and increased with proximal venous occlusion. Whatever the perfusion state, in vivo load is transferred partly by hydraulic pressure. We propose that joints act as hydraulic pressure barriers. An understanding of subchondral physiology may be important in understanding osteoarthritis and other bone diseases. Cite this article: M. Beverly, S. Mellon, J. A. Kennedy, D. W. Murray. Intraosseous pressure during loading and with vascular occlusion in an animal model. Bone Joint Res 2018;7:511–516. DOI: 10.1302/2046-3758.78.BJR-2017-0343.R2

Abstract. Background. Schwannomas are slow-growing, benign tumours normally originating from the Schwann cells of the nerve sheath. Intraosseous schwannoma accounts for 0.175% of primary bone tumours and extremely rare especially outside the axial skeleton. Monoclonal gammopathy has been associated with soft tissue schwannomas but never with the intraosseous variety. Presenting problem. A 55-year-old woman with a background of monoclonal gammopathy of undetermined significance (MGUS) presented with a 2-year history of right thigh pain. CT scan showed a well defined, lytic lesion with a thin peripheral rim of sclerosis in the midshaft of the femur. MRI displayed a hyperintense, well marginated and homogenous lesion. Definitive diagnosis was made based on the classical histopathological appearance of schwannoma. Clinical management. We managed our patient with local curettage and prophylactic cephalomedullary nailing on the basis of a high mirel score. Discussion. Intraosseous schwannomas are poorly understood but most commonly reported in middle-aged women. Radiologically, their differential diagnosis includes malignant bone tumours, solitary bone cysts, aneurysmal bone cysts and giant cell tumours. As a result, they are usually diagnosed incidentally on histology. Although malignant transformation is possible in soft tissue schwannomas, all intraosseous schwannomas reported to date have been benign. This case demonstrates the importance of suspecting intraosseous schwannoma as a differential diagnosis for lytic bone lesions to avoid the overtreatment of patients. We also highlight monoclonal gammopathy of undetermined significance as a potential risk factor for a poorly understood disease and make recommendations about the appropriate management of these lesions. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction. Day stay surgery for anterior cruciate ligament (ACL) reconstructions is an increasingly common practice and has driven clinicians to come up with postoperative pain regimes that allow same day mobilisation and a safe and timely discharge. There is a paucity of literature surrounding the use of intraosseous (IO) ropivacaine used as a Bier's block to provide both intraoperative and postoperative analgesia in lower limb surgery. Methods. This patient blinded, pilot study randomised 15 patients undergoing ACL reconstruction to receive either IO ropivacaine 1.5 or 2.0 mg/kg; or 300 mg of ropivacaine as local infiltration (standard of care). Toxic plasma levels of ropivacaine have been defined in the literature and therefore the primary outcome for this study was arterial plasma concentration of ropivacaine as a means to determine its safety profile. Samples were taken via an arterial line at prespecified times after tourniquet deflation. Secondary outcomes that we were interested in included immediate postoperative pain scores using the visual analogue scale (VAS) and perioperative opioid equivalent consumption. Results. Participants had a mean age of 27.8 (SD 9.2) years and 87% (13/15) were male. All patients in the intervention group receiving IO ropivacaine had plasma concentrations well below the threshold for central nervous system (CNS) toxicity (0.60 µg/ml). The highest plasma concentration was achieved in the intervention group receiving 1.5 mg/kg dose of ropivacaine reaching 3.59 mg/ml. This would equate to 0.22 µg/ml of free plasma ropivacaine. There were no differences across the three groups regarding pain scores or perioperative opioid consumption. Conclusions. This study demonstrates that IO administration of 0.2% ropivacaine is both safe and effective in reducing perioperative pain in patients undergoing ACL reconstruction. There may be scope to increase the IO dose further or utilise other analgesics via the IO regional route to improve perioperative pain relief

Aims. Debridement, antibiotics, and implant retention (DAIR) remains one option for the treatment of acute periprosthetic joint infection (PJI) despite imperfect success rates. Intraosseous (IO) administration of vancomycin results in significantly increased local bone and tissue concentrations compared to systemic antibiotics alone. The purpose of this study was to evaluate if the addition of a single dose of IO regional antibiotics to our protocol at the time of DAIR would improve outcomes. Methods. A retrospective case series of 35 PJI TKA patients, with a median age of 67 years (interquartile range (IQR) 61 to 75), who underwent DAIR combined with IO vancomycin (500 mg), was performed with minimum 12 months' follow-up. A total of 26 patients with primary implants were treated for acute perioperative or acute haematogenous infections. Additionally, nine patients were treated for chronic infections with components that were considered unresectable. Primary outcome was defined by no reoperations for infection, nor clinical signs or symptoms of PJI. Results. Mean follow-up for acute infection was 16.5 months (12.1 to 24.2) and 15.8 months (12 to 24.8) for chronic infections with unresectable components. Overall non-recurrence rates for acute infection was 92.3% (24/26) but only 44.4% (4/9) for chronic infections with unresectable components. The majority of patients remained on suppressive oral antibiotics. Musculoskeletal Infection Society (MSIS) host grade was a significant indicator of failure (p < 0.001). Conclusion. The addition of IO vancomycin at the time of DAIR was shown to be safe with improved results compared to current literature using standard DAIR without IO antibiotic administration. Use of this technique in chronic infections should be applied with caution. While these results are encouraging, this technique requires longer follow-up before widespread adoption. Cite this article: Bone Joint J 2021;103-B(6 Supple A):185–190

1. In fifteen patients with unilateral osteoarthritis of the hip bilateral measurements of the intraosseous pressure of the femoral neck and determination of femoral vein pressure were done simultaneously. These pressure examinations were followed by bilateral intraosseous phlebography of the proximal part of the femur. 2. In a second series of fifteen patients the intraosseous pressures of the femoral head and neck were measured simultaneously before operation for osteoarthritis. 3. The pressure in the femoral vein was equal on the two sides. The intraosseous pressure in the femoral neck was always higher in the arthritic hip than on the unaffected side. In hips with osteoarthritis the pressure in the femoral head was higher than the pressure in the neck. 4. Intraosseous phlebography indicated a state of intramedullary venous engorgement in osteoarthritis. The normal channels for venous drainage from the femoral head and neck were not visible in the phlebographs from the arthritic side. Instead, drainage took place through descending intramedullary vessels to the trochanteric region and down into the femoral shaft. The emptying of intraosseous contrast material from the arthritic hip was delayed. 5. The phlebographs indicated that the abnormally high intraosseous pressure observed in osteoarthritis is caused by a high resistance to flow across the cortex of the proximal part of the femur. 6. The aching rest pain typical of severe osteoarthritis was noted only in patients with intraosseous femoral neck pressure above 40 millimetres of mercury, an indication that this type of pain is caused by intramedullary hypertension. The decrease of arteriovenous pressure difference, caused by increase of resistance to venous outflow, is probably accompanied by disturbances of nutritive flow. This "venous ischaemia" may play an important role for the structural changes of cancellous bone in osteoarthritis

We report a case of systemic intraosseous lipomatosis involving the proximal femur, both ends of the tibia, and the tarsal and metatarsal bones. The lesions progressed during a five-year follow-up with a pathological fracture of the tibial plateau. CT scans were characteristic and helpful in diagnosis but MR imaging added little information. Intraosseous lipomatosis is a hamartomatous malformation due to hyperplasia of adipose tissue, and is fundamentally different from solitary benign intraosseous lipoma. Management involves reconstruction of any pathological fracture. Large progressive lesions should be treated by curettage and grafting in an attempt to prevent such fractures

The intraosseous pressure in the femur and tibia near the knee and in the internal saphenous vein at knee level was measured in fifty-three patients with suspected knee lesions. There were four groups: with and without degenerative osteoarthritis and with and without aching rest pain of the knee region. Low intraosseous pressures were found in patients with neither osteoarthritis nor rest pain, and in half the patients with osteoarthritis but without rest pain. Low pressures were found in the tibia, but very high intraosseous pressures were found in the femur in most patients with osteoarthritis and rest pain. Patients with no osteoarthritis but with rest pain mostly had high pressures in both the tibia and the femur

Aims. Infection complicating primary total knee arthroplasty (TKA) is a common reason for revision surgery, hospital readmission, patient morbidity, and mortality. Increasing incidence of methicillin-resistant Staphylococcus aureus (MRSA) is a particular concern. The use of vancomycin as prophylactic agent alone or in combination with cephalosporin has not demonstrated lower periprosthetic joint infection (PJI) rates, partly due to timing and dosing of intravenous (IV) vancomycin administration, which have proven important factors in effectiveness. This is a retrospective review of a consecutive series of primary TKAs examining incidence of PJI, adverse reactions, and complications using IV versus intraosseous (IO) vancomycin at 30-day, 90-day, and one-year follow-up. Methods. A retrospective review of 1,060 patients who underwent TKA between May 2016 to July 2020 was performed. There were 572 patients in the IV group and 488 in the IO group, with minimal 30 days of follow-up. Patients were followed up at regularly scheduled intervals (two, six, and 12 weeks). No differences between groups for age, sex, BMI, or baseline comorbidities existed. The IV group received an IV dose of 15 mg/kg vancomycin given over an hour preceding skin incision. The IO group received a 500 mg dose of vancomycin mixed in 150 ml of normal saline, injected into proximal tibia after tourniquet inflation, before skin incision. All patients received an additional dose of first generation cephalosporin. Evaluation included preoperative and postoperative serum creatinine values, tourniquet time, and adverse reactions attributable to vancomycin. Results. Incidence of PJI with minimum 90-day follow-up was 1.4% (eight knees) in the IV group and 0.22% (one knee) in IO group (p = 0.047). This preliminary report demonstrated an reduction in the incidence of infection in TKA using IO vancomycin combined with a first-generation cephalosporin. While the study suffers from limitations of a retrospective, multi-surgeon investigation, early findings are encouraging. Conclusion. IO delivery of vancomycin after tourniquet inflation is a safe and effective alternative to IV administration, eliminating the logistical challenges of timely dosing. Cite this article: Bone Joint J 2021;103-B(6 Supple A):13–17

Introduction. Intraosseous administration of low dose vancomycin has been proven to produce 6 to 20 times higher tissue concentrations compared to intravenous administration in both primary and revision knee replacement. However, these superior levels are achieved when the antibiotic given intraosseously is administered distal to a tourniquet that is inflated for the majority of the case. With increasing interest in limited, or no, tourniquet use during TKA we sought to study the tissue concentrations achieved with limited tourniquet use and intraosseously administered vancomycin compared to weight-based, time optimized intravenous administration. Methods. Twenty-four patients undergoing primary TKA were randomized to two groups. The Intravenous (IV) Group received weight based (15mg/kg) vancomycin timed to finish before incision. The Intraosseous (IO) Group received 500 mg of vancomycin injected as a bolus through a needle into the proximal tibia distal to an inflated tourniquet prior to skin incision. In the IO group, the tourniquet was deflated 10 minutes following the injection and re-inflated only for cementation. In the IV group, the tourniquet was only inflated for cementation. During the procedure, fat and bone samples were taken at regular intervals. Tissue antibiotic concentrations were measured using a validated technique involving high performance liquid chromatography. Results. Mean tissue concentrations of vancomycin in fat and bone samples from all time points were 3–10 times greater in the IO group (all results, p<0.01). At closure, mean vancomycin levels in fat were 6.0ug/g in the IV group vs 40.5ug/g in the IO group (p<0.001). Final bone levels were 8.3ug/g in the IV group vs 26.9ug/g in the IO group (p=0.009). Conclusion. In total knee replacement, IO administration of prophylactic vancomycin achieves significantly higher tissue concentrations versus IV administration given under ideal conditions despite limited tourniquet use. For figures, tables, or references, please contact authors directly

Despite modern surgical techniques, reported rates of deep infection following Total Knee Replacement (TKR) persist between 1–2.5%. Coagulase-negative staphylococcus (CNS) has become the most common causative organism, and while growth of CNS is more indolent thanstaphylococcus aureus, it has a relatively higher minimum inhibitory concentration (MIC) against cephalosporins. Tissue concentrations of prophylactic antibiotics may fall below this level during TKR with conventional ‘systemic’ dosing. Regional administration of prophylactic antibiotics via a foot vein following tourniquet inflation has been shown to provide tissue concentrations approximately 10 times higher than systemic dosing, however cannulation of a foot vein is difficult, time consuming, and may compromise sterility. Intraosseous cannulation offers an alternative method of accessing the vascular system, and the aim of this study was to assess its effectiveness in administration of prophylactic antibiotics. 22 patients undergoing primary total knee arthroplasty were randomised into two groups. Group 1 received 1g of cephazolin systemically 10 minutes prior to tourniquet inflation. In Group 2 the EZ-IO tibial cannulation system was used, and 1g of cephazolin was administered intraosseously in 200ml of normal saline following tourniquet inflation and prior to skin incision. Subcutaneous fat and femoral bone samples were taken at set intervals during the procedure, and antibiotic concentrations measured using High Performance Liquid Chromatography (HPLC). There were no significant differences in patient demographics, comorbidities, or physical parameters between groups. The overall mean tissue concentration of cephazolin in subcutaneous fat was 185.9μg/g in the intraosseous group and 10.6μg/g in the systemic group (p<0.01). The mean tissue concentration in bone was 129.9 μg/g in the intraosseous group and 11.4μg/g in the systemic group (p<0.01). These differences were consistent across all sample time points throughout the procedure. No complications occurred in either group. Intraosseous regional administration can achieve tissue levels of antibiotic over an order of magnitude higher than systemic administration. Further work is required to determine if there is clinical benefit in preventing infection, particularly against CNS. This novel mode of drug administration may also have other applications, allowing ‘surgical site delivery’ of medication while minimising systemic side effects

Introduction. Debridement, Antibiotics and Implant Retention (DAIR) remains the norm for the treatment of acute periprosthetic joint infection (PJI) despite less than optimal success rates. Intraosseous (IO) administration of vancomycin has been shown to have significantly increased local bone and tissue concentrations compared to systemic antibiotics, with lower systemic antibiotic levels compared to intravenous. The purpose of this study was to evaluate if the addition of IO regional antibiotics to our protocol at the time of DAIR would improve outcomes. Methods. A retrospective review of 35 PJI TKA patients who underwent DAIR combined with IO vancomycin (500mg) was performed with minimum 12-month follow-up. 26 patients were treated for acute perioperative or acute hematogenous infections following primary TKA. Nine were treated for chronic infections with components that were considered unresectable (ie) constructs with ingrown cones, sleeves, or long cemented stems in elderly comorbid patients. Primary outcome was defined by no reoperations for infection nor clinical signs or symptoms of PJI. Results. The average follow up for acute infection was 16.5 months (range 12.1–24.2) and 15.8 months (range 12–24.8) for chronic infections with unresectable components. Overall eradication rates for acute infection was 93.1% while only 44.4% for chronic infections with unresectable components. MSIS host grade was a significant indicator of failure (p<0.001). Conclusion. The use of IO vancomycin at the time of DAIR yielded improved results compared to standard irrigation and debridement in acute periprosthetic infections. Its use in chronic infections should remain cautious. While these results are encouraging, this technique requires longer follow-up before widespread adoption

Intraosseous schwannoma is a rare benign neoplasm, which most commonly arises in the head and neck region particularly the mandible, due to the long intraosseous path of sensory nerves in the mandible. We present a 27-year-old lady with an unusual presentation of an intraosseous schwannoma of the first metatarsal. There is only one report published previously of an intraossous schwannoma of the lesser metatarsal bone of the foot. A 27-year-old woman presented with painful left forefoot following a trip while walking. Plain radiographs demonstrated a pathological fracture through a lytic lesion of the first metatarsal of the left foot. MRI scan using axial T1-weighted spin echo and axial and sagittal T2-weighted gradient echo showed an amorphous mass occupying the medulla of the bone but with a breach of the plantar aspect of cortex with apparent localised destruction. Ultrasound-guided biopsy was performed. Haematoxylin and Eosin stained specimen sections showed a proliferation of spindle cells of alternating hypercellularity and hypocellularity. This case was managed by curettage and grafting with autograft and synthetic bone substitute. At two-year follow-up, the radiographs showed complete graft incorporation and a healed cyst. The patient was clinically asymptomatic with return of full functions. There were no clinico-radiological findings to suggest any recurrence. Due to rarity and non-specific clinico-radiological features, this case illustrates the necessity of a multi-disciplinary approach with an accurate histological diagnosis in combination with radiological and clinical appearances

Introduction. Metatarsocuneiform (MTC) fusion is a standard treatment for arthritis, instability, and deformity of these joint. The MTC fusion achieves a good clinical outcome, but nonunion rates up to 12% have been reported. There are different methods for fixation of first MTC joint arthrodesis. Our aim was to compare the biomechanical characteristic of internal and external fixation constructs. Hypothesis. Plantar plate fixation provides higher construct stiffness and endurance stability than intraosseous fixation. Materials & Methods. Seven pairs of fresh-frozen human specimens were used in a matched pair test. In one foot the MTC joint was supplied with a plantar plate. On the other foot intraosseous-screw fixation was perfomed. The specimen constructs were loaded in a 4 point bending test. Parameters obtained were initial stiffness and number of cycles to failure. Failure was defined as displacement of more than 3 mm plantar gapping. Results. The intraosseous-screw fixation group showed significantly (p=0.002) less cycles to failure (n=2946) than the plantare plate (n=7517). The initial stiffness was 131 N/mm for the plantare plate and 43 N/mm for the intraosseous implant (p=0.005). Discussion & Conclusion. Plantar plate fixation of the first MTC fusion created a stronger and stiffer construct than intraosseous fixation. This was likely due to the plantar and dorsal implant position. A stiffer construct can reduce the risk of non-union and shorten the period of nonweight-bearing

Introduction. Vancomycin is a commonly used antibiotic for prophylaxis in total joint replacement surgery. Several studies have reported superior local tissue concentration of vancomycin using intraosseous (IO) infusion compared with standard intravenous (IV) administration in total knee arthroplasty (TKA). We reviewed patients undergoing primary TKA who received IO vancomycin to a group receiving IV vancomycin. Methods. A retrospective review of 1038 patient who underwent primary TKA at our institution was performed from May 1, 2016 to May 1, 2019. This was a consecutive series of patients before and after we adopted this technique. IO vancomycin administration technique has been previously reported from our institution (500mg vancomycin in 200mL solution). Comparisons included preoperative and postoperative creatinine values, adverse reaction to vancomycin, tourniquet time, re-operation rates, periprosthetic joint infection rate at 1 year. Results. There were 482 patients in IO vancomycin group and 572 patients in IV vancomycin group. No differences between groups were present for patient age, sex, or BMI. No differences in creatinine values or tourniquet time were present and there were no adverse reactions to vancomycin in either group. Eight periprosthetic joint infections (1.4%) were reported in the IV group, and 1 (0.2%) periprosthetic joint infection was reported in the IO group at 1 year follow up, and this was statistically significant (p = 0.04, Fishers exact test). The overall reoperation rate was 1.7% (10 patients) in the IV group and 1.1% (5 patients), however, this was not statistically significant (p = 0.4371). The additional reoperations were for retained suture or small areas of poor superficial wound healing and were considered minor. Conclusion. Our study demonstrated that IO vancomycin in primary TKA reduced periprosthetic joint infection and is a safe and effective alternative to IV administration. Furthermore, IO infusion also eliminates the logistical challenges of timely prophylactic antibiotic administration before TKA

The features of two cases of intraosseous ganglion in the lower tibia are described