Aim. Adverse tissue reactions have been a concern in relation to metal components, particularly in hip replacements. We look at a possible correlation between hip joint effusion and metal ion levels. Materials and methods. 56 patients,(42M, 14F) agreed to the study. All had metal-on-mental arthroplasties. Average age was 64.2 (SD 9.8). All patients were asymptomatic. Ultrasound examination performed by one ultrasonographer, using a Sonosite M-Turbo machine with a C60X/5-2 MHz transducer. Cobalt levels were assessed using an inductively coupled plasma mass spectrometer. Chromium levels were assessed using a graphite furnace atomic absorption spectrometer. Results. Average blood ion levels were:. Cobalt 39.02 nmol/L. (SD41.18) range 3 to 215. Chromium 52.51 nmol/L (SD47.48) range 5 to 284. Average Volume: 10.38ml (SD21.3) Range 0 to 219. Conclusion. There was no statistically significant correlation between joint effusion and metal ion levels

Aims. Treatment of high-grade limb bone sarcoma that invades a joint requires en bloc extra-articular excision. MRI can demonstrate joint invasion but is frequently inconclusive, and its predictive value is unknown. We evaluated the diagnostic accuracy of direct and indirect radiological signs of intra-articular tumour extension and the performance characteristics of MRI findings of intra-articular tumour extension. Methods. We performed a retrospective case-control study of patients who underwent extra-articular excision for sarcoma of the knee, hip, or shoulder from 1 June 2000 to 1 November 2020. Radiologists blinded to the pathology results evaluated preoperative MRI for three direct signs of joint invasion (capsular disruption, cortical breach, cartilage invasion) and indirect signs (e.g. joint effusion, synovial thickening). The discriminatory ability of MRI to detect intra-articular tumour extension was determined by receiver operating characteristic analysis. Results. Overall, 49 patients underwent extra-articular excision. The area under the curve (AUC) ranged from 0.65 to 0.76 for direct signs of joint invasion, and was 0.83 for all three combined. In all, 26 patients had only one to two direct signs of invasion, representing an equivocal result. In these patients, the AUC was 0.63 for joint effusion and 0.85 for synovial thickening. When direct signs and synovial thickening were combined, the AUC was 0.89. Conclusion. MRI provides excellent discrimination for determining intra-articular tumour extension when multiple direct signs of invasion are present. When MRI results are equivocal, assessment of synovial thickening increases MRI’s discriminatory ability to predict intra-articular joint extension. These results should be interpreted in the context of the study’s limitations. The inclusion of only extra-articular excisions enriched the sample for true positive cases. Direct signs likely varied with tumour histology and location. A larger, prospective study of periarticular bone sarcomas with spatial correlation of histological and radiological findings is needed to validate these results before their adoption in clinical practice. Cite this article: Bone Jt Open 2024;5(10):944–952

Background. Exebacase, an antistaphylococcal lysin in Phase 3 of development as a treatment for S. aureus bacteremia/right-sided endocarditis has demonstrated antibiofilm activity in vitro and has previously been used as salvage therapy in four patients with relapsing multidrug-resistant (MDR) S. epidermidis knee prosthetic joint infection (PJI) using a procedure called LysinDAIR (administration of the lysin during the performance of an arthroscopic DAIR). Materials/methods. We performed a single center, exploratory, open-label prospective study using the LysinDAIR procedure in patients with chronic (inoculation >3 months prior to treatment) coagulase-negative staphylococci (CNS) PJI of the knee with two different clinical presentations and treatment paradigms. Cohort A: first episode of CNS knee PJI, for whom the LysinDAIR was followed by clindamycin + levofloxacin planned to be prescribed for three months and then stopped; and Cohort B: relapsing episodes of MDR CNS knee PJI for whom the LysinDAIR was followed by primary antimicrobial therapy for three months, followed by suppressive antimicrobial therapy (SAT). Exebacae susceptibility testing was performed before treatment for each patient. In agreement with the French Health authority, exebacase (2 to 3.5 total mg in 30–50 ml (∼0.067 – 0.075 mg/m) was administered directly into the joint during arthroscopy. Results. Eight patients were treated. Exebacase administration was well tolerated by all patients and no serious adverse drug reactions to exebacase were reported. In cohort A (n=4), patients had susceptible S. epidermidis PJI, a painful joint effusion without fistula and without loosening, and received three months of levofloxacin + clindamycin (one patient received an alternative regimen following antibiotic adverse events) and then antibiotics were stopped. During a follow-up of 14, 19, 26 and 36 months, no relapse, no recurrence of the joint effusion and no loosening occurred. In cohort B (n=4), patients had MDR CNS, clinical signs of septic arthritis with a joint effusion without fistula and without loosening and received daptomycin + linezolid or doxycycline. One patient died from COVID-19 at week 4. SAT (tedizolide, n=2; doxycycline, n=1) was then prescribed to other patients. One experienced an infection relapse involving S. caprae under tedizolid therapy at six months. The two other patients continue to do well under SAT 8 and 12 months after the LysinDAIR procedure. Conclusions. The LysinDAIR procedure is a minimally invasive procedure, which has been shown to be easy-to-perform, safe, and has the potential for use as initial treatment or salvage therapy in patients with CNS chronic knee PJI

Aims. Pain is the most frequent complaint associated with osteonecrosis of the femoral head (ONFH), but the factors contributing to such pain are poorly understood. This study explored diverse demographic, clinical, radiological, psychological, and neurophysiological factors for their potential contribution to pain in patients with ONFH. Methods. This cross-sectional study was carried out according to the “STrengthening the Reporting of OBservational studies in Epidemiology” statement. Data on 19 variables were collected at a single timepoint from 250 patients with ONFH who were treated at our medical centre between July and December 2023 using validated instruments or, in the case of hip pain, a numerical rating scale. Factors associated with pain severity were identified using hierarchical multifactor linear regression. Results. Regression identified the following characteristics as independently associated with higher pain score, after adjustment for potential confounders: Association Research Circulation Osseous classification stage IIIa or IIIb, bone marrow oedema, grade 3 joint effusion, as well as higher scores on pain catastrophizing, anxiety, and central sensitization. The final model explained 69.7% of observed variance in pain scores, of which clinical and radiological factors explained 37%, while psychological and neurophysiological factors explained 24% and demographic factors explained 8.7%. Conclusion. Multidimensional characteristics jointly contribute to the severity of pain associated with ONFH. These findings highlight the need to comprehensively identify potential contributors to pain, and to personalize management and treatment accordingly. Cite this article: Bone Joint Res 2024;13(11):673–681

Background. Bacteriophages are natural viruses of interest in the field of PJI. A paper previously reported the PhagoDAIR procedure (use of phages during DAIR) in three patients with PJI for whom explantation was not desirable. As the need to isolate the pathogen before surgery to perform phage susceptibility testing is a strong hindrance for the development of this procedure, we developed post-operative phage injections using ultrasound, in patients infected with S. aureus and/or P. aeruginosa who were eligible for the PhagoDAIR procedure, but for whom phages were not available at the time of surgery. Materials/Methods. We performed a single center, exploratory, prospective cohort study including patients with knee PJI who received phage therapy with ultrasound after performance of a DAIR or a partial prosthesis exchange. All patients had PJI requiring conservative surgery and suppressive antimicrobial therapy (SAT) as salvage procedure. Each case was discussed in multidisciplinary meetings in agreement with French health authority, based on the clinical presentation, and the phage susceptibility testing. The cocktail of highly concentrate active phages (5 mL; about 10. e. 9 PFU/mL) was extemporaneous prepared and administered three times directly into the joint using sonography (1 injection per week during 3 weeks) during the postoperative period, before switching antibiotics to SAT. Results. Seven patients received phages under sonography after the DAIR, and one after a partial exchange (mean age 71 years). All had resection prosthesis or constrained knee prosthesis. Among these seven patients, three were infected with S. aureus (including one MRSA), two were infected with P. aeruginosa (one was a multidrug-resistant isolate), one was infected with both S. aureus and P. aeruginosa and the last one was infected with MRSA, S. epidermidis and Corynebacterium spp.. All patients received a cocktail of active phages provided by Pherecydes Pharma targeting S. aureus or P. aeruginosa. No adverse event was recorded during or after the local injections. All patients were switched to SAT after a primary postoperative antimicrobial therapy of three months. Under SAT, the patient with S. epidermidis co-infection developed a relapse due to the S. epidermidis. With a mean follow-up of 13 months after surgery (from 9 to 24 months), the outcome was favorable for all patients without any sign of infection; none of them had abnormal pain, joint effusion or loosening. Conclusions. Postoperative administration of phages using sonography is a potentially useful procedure in patients with complex PJI for whom a conservative approach is desirable

To assess the use of autogenous osteochondral graft fixation (mosaicplasty) in unstable osteochondritis dissecans (OCD) lesions (Clanton type 2 and 3) of the knee. Eleven patients with x-ray and N4R1 confirmed OCD lesion in their femoral condyle, that had remained symptomatic despite adequate conservative treatment, underwent arthroscopic mosaicplasty plug fixation of the lesion. The OCD lesions were all loose at operation and were all fixed rigidly in situ. using a number of autogenous 4. 5min osteochondral plugs harvested from the edge of the trochlear groove. The patients were prospectively assessed both clinically and by MRI scan at 3, 6 and 12 months and then six monthly. Average follow up was 2. 7 years (2 – 4. 1). Prior to operation all patients had joint effusions and were experiencing pain limiting their activities. By 6 months post-operation the IKDC score had returned to normal in all cases and none of the patients had joint effusions or pain. Serial NHU scans documented healing of the osteochondral plugs and a continuous articular cartilage surface layer in all cases by 9 months. Using mosaicplasty plug fixation we were able to obtain healing in all 1 1 unstable OCD lesions. The benefits of this technique are the ability to obtain rigid stabilization of the fragment using multiple plugs, stimulation of the subchondral blood supply and autogenous cancellous bone grafting. We conclude that mosaic-plasty plug fixation of unstable OCD lesions in the knee is a good technique and recommend its use. Eleven patients with an unstable osteochondritis dissecans lesion (OCD) in their femoral condyle underwent in situ arthroscopic osteochondral graft fixation (mosaicplasty) of the lesion using a number of 4. 5min plugs harvested from the trochlear groove. By 6 months follow-up all of the patients were pain free with no joint effusion and by 9 months all had NW evidence of plug healing and continuous articular cartilage coverage. The benefits of this technique are the ability to obtain rigid stabilization, stimulation of the subchondral blood supply and cancellous bone grafting. We conclude that mosaic-plasty fixation of OCD lesions is a useful technique

Background. Septic arthritis diagnostic is an emergency which implies a treatment with antibiotics and hospitalization. The diagnosis is based on the cytobacteriological examination of the synovial fluid (SF), but direct bacteriological examination is insensitive, and the result of the culture is obtained only after several days. Therefore, there is still a need for a rapid, simple and reliable method for the positive diagnosis of septic arthritis. Such method must allow avoiding both unrecognized septic arthritis leading to major functional consequences, and overdiagnosis that will induce unnecessary expensive hospitalization and unjustified treatment. Mid-infrared (MIR) spectroscopy, that gives a metabolic profiling of biological fluids, has been proposed for early and fast diagnosis. Objectives. To confirm the MIR spectroscopy to discriminate SF samples from patients with septic arthritis from other causes of joint effusion. Methods. Synovial fluids from 402 patients referred for suspected arthropathies were prospectively collected in six hospitals and stored at °80°C. The infrared absorption spectrum was acquired for each of the frozen samples using a chalcogenide fiber biosensor. The most informative spectral variables were selected and then used to develop an algorithm. Then, the algorithm has been validated on independent synovial fluids collected straight after arthrocentesis from 86 patients. Results. The calibration (n=402) and validation (n=86) cohorts consists of synovial fluid samples from patients exhibiting various etiologies. These samples (n=488), by using SF bacteriological analysis and culture and 16S PCR analysis were classified as septic arthritis (n=43) or non-septic arthritis (n=443). On the calibration cohort, the performances of the algorithm show a sensitivity of 90%, a specificity of 90%, a NPV of 99% and a PPV of 41%, the area under the ROC curve (AUROC) was 0.95. On the validation cohort, the performances of the algorithm show a sensitivity of 92%, a specificity of 81%, a NPV of 98% and a PPV of 46%, the area under the ROC curve (AUROC) was 0.90. Conclusions. This study confirms the diagnostic performances of MIR spectroscopy for the discrimination between septic and non-septic synovial fluids. The high negative predictive value and the very short time (within ten minutes) required to obtain the result makes it possible to quickly rule out an infection diagnosis

Introduction. There is a challenge to detect partial tear of the ACL, the number of bundle injured and the proportion of fibers torn. The MRI was shown efficient to individualize the two anteromedial (AM) and posterolateral (PL) bundles of the ACL. The purpose of this study was to assess the ability of the MRI to detect partial tears of the ACL on axial views to display the AM and PL bundles. Materials and methods. This retrospective study included 48 patients (19 partial tears of the ACL, 16 complete rupture of the ACL and 13 normal knee) who underwent both arthroscopy and MRI examinations of the knee. The conventional MRI protocol included one sagittal T1- weighted sequence and 3 proton-density fat sat. The images from MRI were analysis by a radiologist specialized in musculoskeletal imaging who was blinding to the arthroscopic findings. The criteria for the analysis of MRI were divided into primary (those involving the ACL himself) and secondary signs (associated abnormalities). The primary signs included the horizontalisation of the ACL (ACL axis), the global ACL signal intensity and the signal intensity of each AM and PL bundle. The secondary signs included bone bruise, osteochondral impaction, popliteus muscle injury, medial collateral ligament injury and joint effusion. The ACL was classified as normal, partially or totally torn. The rupture of the AM and PL bundle was specified. Results. In our study, MRI was found to have a 75% sensitivity and a 73% specificity for the diagnosis of partial tears of the ACL. The sensitivity to detect AM bundle lesion was 88% but the specificity was 50%. The lack of horizontalisation of the ACL was a very good sign, for partial tears of the ACL, with a sensitivity of 84% and a specificity of 81% (p<0.05). Regarding the secondary signs, there was no significant difference to distinguish partial and complete tear. However, we found that there was a greater probability to find a partial tear of the ACL with the lack of joint effusion, bone bruise and medial collateral ligament injury. Quantifying the proportion of injured fibers was unsuccessful and was found as a failure of the MRI. Conclusions. MRI exhibited lower sensitivity and specificity for partial tear than for complete rupture of the ACL. However 3 important arguments can guide us: the lack of horizontalisation of the ACL, a continuous ACL signal, the display of one of two bundles on the axial view

Introduction: The advantages of metal on metal bearings (MoM) include improved wear characteristics and lower dislocation rate. Metal sensitivity and Aseptic Lymphocyte Dominated Vasculitis Associated Lesion (ALVAL) reaction are becoming increasingly recognised. The BOA has recently issued a statement regarding MoM bearings. They suggested that any revisions for symptoms of pain and soft tissue reaction should be reported to the MHRA and histological specimens forwarded to the Stanmore Retrieval Centre. Methods and results: We report four patients (all females), who presented with late dislocation of a large diameter MoM bearing (three following total hip replacements and one following resurfacing). They all made good initial recovery with complete relief of pain. They developed pain around groin between one and two years following the surgery. Inflammatory markers were normal. MRI/Ultrasound scanning showed the presence of cystic lesions around the hip. They all presented with relatively late dislocation (26 months to six years). At exploration there was a large joint effusion with necrosis and detachment of the abductors. A characteristic finding was an avascular bare trochanter stripped free of any soft tissues. Histology showed a predominantly histiocytic response in keeping with the findings of Willert and Pandit. Discussion: In the absence of any obvious causes for dislocation, one should have a high index of suspicion for the possibility of metal hypersensitivity causing joint effusion, muscle necrosis and thereby leading to instability due to the progressive periosteal and soft tissue erosion. These patients should be considered for early revision of the bearing surface to prevent further damage to the muscle and bone. If the abductors are completely detached a more constrained type of bearing should be used to improve the stability. To the best of our knowledge this is the first report of this unusual complication following MoM bearings

Purpose: To review the MRI findings in transient osteoporosis of the hip (TOH) and to investigate the pattern of perfusion in dynamic studies. Material and Methods: Twenty-seven patients (29 hips), 23–66 years old, were referred for hip pain without history of trauma. In all patients the diagnosis of TOH based on x-rays (decrease bone density of the femoral head) and MRI (bone marrow edema-BME) was confirmed after complete resolution of symptoms and MRI findings after 6–18 months. MRI studies included T1-w SE, T2-w-SPIR-TSE and contrast enhanced T1-w TFE in dynamic mode and delayed SE. Imaging assessment included joint effusion, location and extent of BME (types A–D), sparing of the femoral head, subchondral linear lesions, and collapse. Results: Joint effusion was observed in 28 of 29 hips. The extent of BME in the femoral head was type A in 5/29 hips, B in 2/29, C in 16/29, D in 6/29. Associated BME of the acetabulum was depicted in 6/29 hips. In 12/29 hips the bone marrow edema was sparing the subchondral area. Subchondral line was only found in 2/29 hips. On dynamic T1–w images all hips presented with a delayed pattern of perfusion up to 40 sec. Conclusion: MRI findings are useful in diagnosing TOH and differentiating this entity from early AVN

Introduction. Closed suction intraarticular drain (CSD) use after total knee arthroplasty (TKA) has been studied with regards to wound healing and range of motion, however, no data exist on how CSD use impacts knee joint effusion and quadriceps strength. The primary purpose of this study was to determine whether CSD use influences recovery of quadriceps strength. Secondary outcomes examined effects of CSD on intraarticular effusion, lower limb swelling, knee range of motion (ROM), pain and wound healing complications. Methods. Twenty-nine patients undergoing same-day bilateral TKA were enrolled in a prospective, randomized blinded study. Subjects were randomized to receive a CSD on one lower extremity while the contralateral limb had the use of a subcutaneous drain (SCDRN) without the use of suction. Isometric quadriceps strength was collected as the primary outcome. Secondary outcomes consisted of quadriceps muscle activation, intraarticular effusion measured via ultrasound, lower extremity swelling measured with bioelectrical impendence, lower extremity girth, ROM, and pain. Outcomes were assessed preoperatively and postoperatively at day 2, 2 and 6 weeks and 3 months. Differences in limbs were determined using paired t-tests or Wilcoxon signed rank tests. Results. No significant differences were identified between limbs prior to surgery for the primary or secondary outcomes. No significant differences in quadriceps strength were seen between CSD and SCDRN limbs at postoperative day 2 (p = 0.09), two weeks (p=0.7), six weeks (p=0.3), or three months (p=0.5). Secondary outcomes, of quadriceps activation battery, intraarticular effusion, lower extremity swelling, ROM, and pain were not found to significantly differ at any time point following surgery. Conclusion. The use of CSD during TKA did not influence quadriceps strength, quadriceps activation, intraarticular effusion, bioelectrical measure of swelling, ROM, or pain. The results of this study have limited drain use by the authors in primary uncomplicated TKA

Recent studies about hip stability after total hip arthroplasties (THA) concerned differences regarding bearings: ceramic on ceramic (CoC) presenting less dislocations on the long term compared to metal or ceramic on polyethylene. The hypothesis is a difference in the healing process of periarticular tissues, with a stronger fibrous tissue for the first one, and more foreign body reaction, joint effusion with the others. NMR Imaging of the pelvis showing both hips using novel MR MAVRIC program for metal artefacts suppression, were performed in 10 patients, 15 THA and 2 non-pathological contralateral hips. Eight hips had CoC bearings, 3 of which were impacted cementless bulky ceramic implant, and 5 had a metal back. 7 hips had CoP bearings, 4 of which were cemented. Native capsules showed a mean thickness of 6.6mm. For CoC bearings, capsule thickness ranged from 7mm to 9.6 mm with a mean thickness of 8mm. For CoP bearings, capsule thickness ranged from 3mm to 8.4mm, with a mean thickness of 6.1mm. Neocapsule appeared clearly in all COC bearings observed, while for CoP, sometimes it was less dense with fatty aspect, 3 hips out of 7 having a very thin capsule under 4mm. It is possible to observe and quantify new capsule after THR and measure differences although not significant regarding bearings on limited number of samples. More patients might be included, but the tendencies observed here might explain better long term stability in vivo observed with Coc

A total knee replacement (TKR) with instability is one in which the supporting soft tissues have failed or are unable to function due to component size and/or position. Instability following TKR can lead to the need for surgery in 10–22% of revision cases. Patients may complain of symptoms of giving way, difficulty climbing stairs, and the sensation that their knee may buckle under stress. Physical findings may include soft-tissue tenderness in the peripatellar and pes anserine regions, recurrent joint effusions, and joint laxity. The cause of instability after TKR should be determined pre-operatively so the problem may be corrected at the time of revision. Instability after TKR may be due to component loosening, ligament rupture/incompetence, component malposition, mismatched flexion/extension gaps, or failure to correct ligament imbalance at the time of the index procedure. A common scenario after a cruciate-retaining TKR is that of PCL rupture, thus leading to instability in flexion and excessive posterior translation of the tibia. Other scenarios leading to TKR instability are pre-operative valgus alignment with MCL stretching, resulting in the post-operative recurrence of medial instability; or excessive resection of the posterior femoral condyles from undersizing of the femoral component, leading to laxity in flexion. The treatment of instability after TKR generally requires component revision and balancing of the flexion and extension gaps. Isolated ligament reconstruction is not successful in the setting of a prosthetic joint due to the lack of inherent joint stability. At the time of revision, the surgeon must carefully assess the flexion gap; often posterior femoral augments must be used to upsize the femoral component and tighten the flexion space relative to the extension space; for this reason, isolated polyethylene exchange is not successful for flexion instability. For instability in the varus/valgus plane, rebalancing the knee by performing ligament releases and using a more stabilizing polyethylene insert may by sufficient. The results of revision TKR for instability has been successful in the majority of cases, decreasing the symptoms of giving way and difficulty stairclimbing. A careful assessment of the varus/valgus stability of the prosthetic knee and the flexion/extension spaces at the time of revision TKR, along with the use of augments and more stabilised articulations, is mandatory in order to achieve good results

The aim of this study was determine if the detection of pathology in children with a limp can be optimised by screening with blood tests for raised inflammatory markers. The entry criteria for the study were children (0–15 years) presenting to our hospital Emergency Department from 2012–2015 with a non-traumatic limp or pseudoparalysis of a limb, and no sign of fracture or malignancy on plain radiographs. ESR and CRP blood tests were performed along with other standard investigations. Children with ESR or CRP over 10 underwent MRI scan of their area of pain or tendernesss, with those under 7 years old having general anaesthetic. MRI provided the diagnosis in cases of osteomyelitis, pyomyositis, fasciitis, cellulitis, discitis, as well as non-infective conditions such as malignancy and fracture not visible on plain radiographs. Where a joint effusion was present, the diagnosis of septic arthritis was made from organisms cultured following surgical drainage, or high white cell count in joint fluid if no organisms were cultured. The study was completed once data from 100 consecutive children was available. 64% of children had an infective cause for their symptoms (osteomyelitis, septic arthritis, pyomyositis, fasciitis, cellulitis or discitis). A further 11% had positive findings on MRI from non-infective causes (juvenile idiopathic arthritis, cancer, or occult fracture). The remaining 25% had either a normal scan, or transient synovitis. ESR was a more sensitive marker than CRP, since ESR was raised in 97% of those with abnormal scans, but CRP in only 70%. There were no complications from any of the GA MRI scans. Conclusion: This shows that MRI imaging of all children with a limp and either raised ESR or CRP is a sensitive method to minimise the chance of missing important pathology in this group, and is not wasteful of MRI resources

Aims

The aim of this study was to determine the consensus best practice approach for the investigation and management of children (aged 0 to 15 years) in the UK with musculoskeletal infection (including septic arthritis, osteomyelitis, pyomyositis, tenosynovitis, fasciitis, and discitis). This consensus can then be used to ensure consistent, safe care for children in UK hospitals and those elsewhere with similar healthcare systems.

The unwell child with an acutely irritable hip poses a diagnostic dilemma. Recent studies indicate that pericapsular myositis may be at least as common as joint infection in the septic child. MRI might therefore be a critical first step to avoid unnecessary hip drainage surgery in the septic child with hip symptoms. We reviewed our own experience with MR imaging in this setting. We searched our PACS system to retrieve MRI scans performed for children with suspected hip sepsis from August 2008 to August 2014 using the following terms: hip, septic arthritis, osteomyelitis, mysositis, abscess, femur, acetabulum. 56 cases fulfilled inclusion criteria that included acute presentation with hip symptoms and 2 or more Kocher criteria for septic arthritis. Recent unsuccessful hip washout was not a contra-indication. 56 patients presented with acute infection around the hip. 47 (84%) had MRI scans before any surgical intervention and 9 (16%) had scans promptly following unsatisfactory hip washout with failure to improve. 20 (36%) were found to have pericapsular myositis. In this group, the infection commonly involved the iliopsoas (4), gluteal (4), piriformis (5) or obturator (7) muscles. 15 (27%) children had proximal femoral or acetabular osteomyelitis and 8 (14%) were diagnosed with septic arthritis. The 13 (23%) remaining scans did not show infection around the hip. This study confirms a high rate of extracapsular foci in septic children presenting with hip irritability. Less than 20% had actual septic arthritis in this series. While drainage of a septic joint should never be delayed in the face of a large joint effusion with debris on US, there is a clear role for MRI scanning in the acute setting when the diagnosis is less certain

Aims

Knee osteoarthritis (OA) involves a variety of tissues in the joint. Gene expression profiles in different tissues are of great importance in order to understand OA.

A total knee replacement (TKR) with instability is one in which the supporting soft tissues have failed or are unable to function due to component size and/or position. Instability following TKR can lead to the need for surgery in 10–22% of revision cases. Patients may complain of symptoms of giving way, difficulty climbing stairs, and the sensation that their knee may buckle under stress. Physical findings may include soft-tissue tenderness in the peripatellar and pes anserine regions, recurrent joint effusions, and joint laxity. The cause of instability after TKR should be determined pre-operatively so the problem may be corrected at the time of revision. Instability after TKR may be due to component loosening, ligament rupture/incompetence, component malposition, mismatched flexion/extension gaps, or failure to correct ligament imbalance at the time of the index procedure. A common scenario after a cruciate-retaining TKR is that of PCL rupture, thus leading to instability in flexion and excessive posterior translation of the tibia. Other scenarios leading to TKR instability are pre-operative valgus alignment with MCL stretching, resulting in the post-operative recurrence of medial instability; or excessive resection of the posterior femoral condyles from undersizing of the femoral component, leading to laxity in flexion. The treatment of instability after TKR generally requires component revision and balancing of the flexion and extension gaps. Isolated ligament reconstruction is not successful in the setting of a prosthetic joint due to the lack of inherent joint stability. At the time of revision, the surgeon must carefully assess the flexion gap; often posterior femoral augments must be used to upsize the femoral component and tighten the flexion space relative to the extension space; for this reason, isolated polyethylene exchange is not successful for flexion instability. For instability in the varus/valgus plane, rebalancing the knee by performing ligament releases and using a more stabilizing polyethylene insert may by sufficient. The results of revision TKR for instability has been successful in the majority of cases, decreasing the symptoms of giving way and difficulty stairclimbing. A careful assessment of the varus/valgus stability of the prosthetic knee and the flexion/extension spaces at the time of revision TKR, along with the use of augments and more stabilised articulations, is mandatory in order to achieve good results

Aims

Avascular femoral head necrosis in the context of gymnastics is a rare but serious complication, appearing similar to Perthes’ disease but occurring later during adolescence. Based on 3D CT animations, we propose repetitive impact between the main supplying vessels on the posterolateral femoral neck and the posterior acetabular wall in hyperextension and external rotation as a possible cause of direct vascular damage, and subsequent femoral head necrosis in three adolescent female gymnasts we are reporting on.

Aims

This study aimed, through bioinformatics analysis, to identify the potential diagnostic markers of osteoarthritis, and analyze the role of immune infiltration in synovial tissue.