BackgroundInflammation is associated with the onset and progression of osteoarthritis in multiple joints. It is well known that mechanical properties differ between different joints, however, it remains unknown if the inflammatory process is similar/distinct in patients with hip vs. knee OA. Without complete understanding of the role of any specific cytokine in the inflammatory process, understanding the ‘profile’ of inflammation in a given patient population is an essential starting point. The aim of this study was to identify serum cytokine profiles in hip Osteoarthritis (OA), and investigate the association between cytokine concentrations and clinical measurements within this patient population and compare these findings to knee OA and healthy control cohorts.MethodsIn total, 250 serum samples (100 knee OA, 50 hip OA and 100 control) and 37 synovial fluid samples (8 knee OA, 14 hip OA and 15 control) were analyzed using a multiplex ELISA based approach. Synovial biopsies were also obtained and examined for specific cytokines. Pain, physical function and activity within the hip OA cohort were examined using the HOOS, SF-36, HHS and UCLA outcome measures.ResultsThe three cohorts showed distinct serum cytokine profiles. EGF, FGF2, MCP3, MIP1α, and IL8 were differentially expressed between hip and knee OA cohorts; while FGF2, GRO, IL8, MCP1, and VEGF were differentially expressed between hip OA and control cohorts. Eotaxin, GRO, MCP1, MIP1β, VEGF were differentially expressed between knee OA and control cohorts. EGF, IL8, MCP1, MIP1β were differentially expressed in synovial fluid from a sub-set of patients from each cohort. Specifically within the hip OA cohort, IL-6, MDC and IP10 were associated with pain and were also found to be present in synovial fluid and synovial membrane (except IL-6) of patients with hip OA.ConclusionOA may include different inflammatory subtypes according to affected joints and distinct inflammatory processes may drive OA in these joints. IL6, MDC and IP10 are associated with hip OA pain and these proteins may be able to provide additional information regarding pain in hip OA patients.Electronic supplementary materialThe online version of this article (10.1186/s12891-018-1955-4) contains supplementary material, which is available to authorized users.

BackgroundThe aim of the current study was to evaluate the innervation of the acetabular labrum in the various zones and to understand its potential role in nociception and proprioception in hips with labral pathology.MethodsA total of twenty hip labrums were tagged and excised intraoperatively from patients undergoing a total hip replacement. After preparation, the specimens were cut to a thickness of 10 μm and divided into four quadrants (zones) using a clock face pattern. Neurosensory structure distribution was then evaluated using Hematoxylin and Eosin (H and E), and immunoreactivity to S-100.ResultsAll specimens had abundant free nerve endings (FNEs). These were seen predominantly superficially and on the chondral side of the labrum. In addition, predominantly three different types of nerve end organs (NEOs) were identified in all twenty specimens. FNEs and NEOs were more frequently seen in the antero-superior and postero-superior zones. Four specimens had abundant vascularity and disorganised architecture of FNEs in the deeper zones of the antero-superior quadrant suggestive of a healed tear. Myofibroblasts were present in abundance in all the labral specimens and were distributed uniformly throughout all labral zones and depth.ConclusionsThe current study shows that the human acetabular labrum has abundant FNEs and NEOs. These are more abundant in the antero-superior and postero-superior zones. The labrum, by virtue of its neural innervation, can potentially mediate pain as well as proprioception of the hip joint, and be involved in neurosecretion that can influence connective tissue repair.

Abstract. Background: To assess using a retrospective case control study, whether patients undergoing primary, elective total hip or knee arthroplasty who receive blood transfusion have a higher rate of post-operative infection compared to those who do not.Materials and Methods: Data on elective primary total hip or knee arthroplasty patients, including patient characteristics, co-morbidities, type and duration of surgery, blood transfusion, deep and superficial infection was extracted from the Alberta Bone and Joint Health Institute (ABJHI). Logistic regression analysis was used to compare deep infection and superficial infection in blood-transfused and non-transfused cohorts.Results: Of the 27892 patients identified, 3098 (11.1%) received blood transfusion (TKA 9.7%; THA 13.1%). Overall, the rate of superficial infection (SI) was 0.5% and deep infection (DI) was 1.1%. The infection rates in the transfused cohort were SI 1.0% and DI 1.6%, and in the non-transfused cohort were SI 0.5% and DI 1.0%. The transfused cohort had an increased risk of superficial infection (adjusted odds ratio (OR) 1.9 [95% CI 1.2-2.9, p-value 0.005]) as well as deep infection (adjusted OR 1.6 [95% CI 1.1-2.2, p-value 0.008]).Conclusion: The odds of superficial and deep wound infection are significantly increased in primary, elective total hip and knee arthroplasty patients who receive blood transfusion compared to those who did not. This study can potentially help in reducing periprosthetic hip or knee infections.

Abstract. The aim of this study was to determine the incidence, annual trend, and perioperative outcomes and identify risk factors of early-onset (≤90 d) deep surgical site infection (SSI) following primary total hip arthroplasty (THA) for osteoarthritis. We performed a retrospective study using prospectively collected patient-level data from January 2013 to March 2020. The diagnosis of deep SSI was based on the published Centre for Disease Control/National Healthcare Safety Network (CDC/NHSN) definition. The Mann–Kendall trend test was used to detect monotonic trends. Secondary outcomes were 90 d mortality and 90 d readmission. A total of 22 685 patients underwent primary THA for osteoarthritis. A total of 46 patients had a confirmed deep SSI within 90 d of surgery representing a cumulative incidence of 0.2 %. The annual infection rate decreased over the 7-year study period (p=0.026). Risk analysis was performed on 15 466 patients. Risk factors associated with early-onset deep SSI included a BMI > 30 kg m−2 (odds ratio (OR) 3.42 [95 % CI 1.75–7.20]; p<0.001), chronic renal disease (OR, 3.52 [95 % CI 1.17–8.59]; p=0.011), and cardiac illness (OR, 2.47 [1.30–4.69]; p=0.005), as classified by the Canadian Institute for Health Information. Early-onset deep SSI was not associated with 90 d mortality (p=0.167) but was associated with an increased chance of 90 d readmission (p<0.001). This study establishes a reliable baseline infection rate for early-onset deep SSI after THA for osteoarthritis through the use of a robust methodological process. Several risk factors for early-onset deep SSI are potentially modifiable, and therefore targeted preoperative interventions of patients with these risk factors is encouraged.

There is limited knowledge regarding the anatomic relationships and functional anatomy of the Obturator Externus muscle (OE). It is described as a muscle which originates from the external bony margin of the obturator foramen with a cylindrical tendon which passes like a sling under the femoral neck and inserts in the trochanteric fossa. The primary aim of this study is to describe the OE morphology and its anatomic relationship to the acetabulum. A secondary aim is to postulate its action. Eighteen fresh human cadaveric hips were dissected to investigate the anatomy of the OE. A plastic model of the pelvis and femur was used to create a string model based on a technique previously described by Beck et al. The plastic model was used to determine the function of the OE.We conclude that the Obturator externus muscle helps to stabilise the head of the femur in the socket. The mechanical model demonstrated that the primary action of the obturator externus muscle was to externally rotate the femur when the hip was in neutral position and flexed at 90°. Its secondary function was as an adductor when the hip was in flexion.