Aims. The antidiabetic agent metformin inhibits fibrosis in various organs. This study aims to elucidate the effects of hyperglycaemia and metformin on knee joint capsule fibrosis in mice. Methods. Eight-week-old wild-type (WT) and type 2 diabetic (db/db) mice were divided into four groups without or with metformin treatment (WT met(-/+), Db met(-/+)). Mice received daily intraperitoneal administration of metformin and were killed at 12 and 14 weeks of age. Fibrosis morphology and its related genes and proteins were evaluated. Fibroblasts were extracted from the capsules of 14-week-old mice, and the expression of fibrosis-related genes in response to glucose and metformin was evaluated in vitro. Results. The expression of all fibrosis-related genes was higher in Db met(-) than in WT met(-) and was suppressed by metformin. Increased levels of fibrosis-related genes, posterior capsule thickness, and collagen density were observed in the capsules of db/db mice compared with those in WT mice; these effects were suppressed by metformin. Glucose addition increased fibrosis-related gene expression in both groups of mice in vitro. When glucose was added, metformin inhibited the expression of fibrosis-related genes other than cellular communication network factor 2 (Ccn2) in WT mouse cells. Conclusion. Hyperglycaemia promotes fibrosis in the mouse knee joint capsule, which is inhibited by metformin. These findings can help inform the development of novel strategies for treating knee joint capsule fibrosis. Cite this article: Bone Joint Res 2024;13(7):321–331

Aims. Developmental dysplasia of the hip (DDH) is a complex musculoskeletal disease that occurs mostly in children. This study aimed to investigate the molecular changes in the hip joint capsule of patients with DDH. Methods. High-throughput sequencing was used to identify genes that were differentially expressed in hip joint capsules between healthy controls and DDH patients. Biological assays including cell cycle, viability, apoptosis, immunofluorescence, reverse transcription polymerase chain reaction (RT-PCR), and western blotting were performed to determine the roles of the differentially expressed genes in DDH pathology. Results. More than 1,000 genes were differentially expressed in hip joint capsules between healthy controls and DDH. Both gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that extracellular matrix (ECM) modifications, muscle system processes, and cell proliferation were markedly influenced by the differentially expressed genes. Expression of Collagen Type I Alpha 1 Chain (COL1A1), COL3A1, matrix metalloproteinase-1 (MMP1), MMP3, MMP9, and MMP13 was downregulated in DDH, with the loss of collagen fibres in the joint capsule. Expression of transforming growth factor beta 1 (TGF-β1) was downregulated, while that of TGF-β2, Mothers against decapentaplegic homolog 3 (SMAD3), and WNT11 were upregulated in DDH, and alpha smooth muscle actin (αSMA), a key myofibroblast marker, showed marginal increase. In vitro studies showed that fibroblast proliferation was suppressed in DDH, which was associated with cell cycle arrest in G0/G1 and G2/M phases. Cell cycle regulators including Cyclin B1 (CCNB1), Cyclin E2 (CCNE2), Cyclin A2 (CCNA2), Cyclin-dependent kinase 1 (CDK1), E2F1, cell division cycle 6 (CDC6), and CDC7 were downregulated in DDH. Conclusion. DDH is associated with the loss of collagen fibres and fibroblasts, which may cause loose joint capsule formation. However, the degree of differentiation of fibroblasts to myofibroblasts needs further study. Cite this article: Bone Joint Res 2021;10(9):558–570

Purpose. Recent work has shown that joint contracture severity can be decreased with the mast cell stabilizer ketotifen in association with decreased numbers of myofibroblasts and mast cells in the joint capsule of a rabbit model of post-traumatic contractures. Neuropeptides such as Substance P (SP) can induce mast cells to release growth factors. Using a gel contraction assay, we test the hypothesis that joint capsule cell-mediated contraction of a collagen gel can be enhanced with SP, but the effect is magnified in the presence of mast cells. Method. Anterior elbow joint capsules were obtained at the time of surgical release from 2 men (age 34 and 54) and 1 woman (age 40) with chronic (> 1 year) post-traumatic joint contractures. The human mast cell line HMC-1 (Mayo Clinic, Rochester), SP and the NK1 receptor antagonist RP67580 (Sigma, Oakville, ON) were used. NK1 is the SP receptor. Neutralized Collagen solution composed with 58% Vitrogen 100 purified collagen mixed with HMC-1 cells only (7.5 105), human capsule cells (2.5 105), or human capsule cells (2.5 105) and 7.5 105 mast cells (1:3) were cast into 24- well tissue culture plates. In some experiments, SP (1 × 10. −5. M) +/− RP67580 (0.5 mM) were added. The gels were maintained with 0.5 ml DMEM composed with 2% BSA and incubated at 37C for 12 h for gelation to occur. The gels were then detached from the wall and the bottom of culture plate wells, and photographed at regular intervals up to 72 hours. Gel contraction studies were carried out on passage 4 and done in triplicate for each patient. The average value of each patients triplicate was combined to give a mean contraction at each time point. Statistical analysis involved an ANOVA with posthoc Bonferroni correction. P < 0.001 was significant. Results. Mast cells alone or with SP were unable to contract collagen gels. Joint capsule cells were able to contract the collagen gels and this was enhanced in the presence of SP, although not statistically significant. Joint capsule cells combined with mast cells enhanced the gel contraction more than joint capsule cells alone or with SP (p<0.001). The addition of SP accelerated the joint capsule cell-mediated gel contraction in the presence of mast cells the greatest (p<0.001 over all other conditions). The inhibitor RP67580 completely abolished the collagen gel contraction of the joint capsule cells in all conditions. Conclusion. The in vitro experiment shows that joint capsule cell function, in the form of collagen gel contraction, is modified by the presence of mast cells and neuropeptides. These findings are significant as they strengthen the hypothesis that a myofibroblast mast cell neuropeptide fibrosis axis may be contributing to the joint capsule changes underling the loss of motion in post-traumatic joint contractures. In vivo studies with the rabbit model of post-traumatic contractures will be performed using the compounds examined in the current study

Until today it is unknown whether preservation of the joint capsule positively affects patient reported outcome (PROs) in DAA-THA. A recent RCT found no clinical difference at 1 year. Since 2015 we preserve the capsule suture it at the end. We here evaluate whether this change had any effect on PROs and revisions, 2 years post-operatively. Two subsequent cohorts operated by the senior author were compared. The capsule was resected in the first cohort (January 2012 – December 2014) and preserved in the second cohort (July 2015 – December 2017). No other technical changes have been introduced between the two cohorts. Patient demographics, Charlson Comorbidity Index (CCI), and surgical data were collected from our clinical information system. 2-years PROs questionnaires (OHS, COMI Hip) were obtained. Data was analyzed with generalized multiple regression analysis. 430 and 450 patients were included in the resected and preserved cohorts, respectively. Demographics, CCI surgical time and length of stay were equal in both groups. Blood loss was less in the preserved cohort (p<.05). Four patients had a revision (1 vs 3, n.s.). Once corrected for demographics, capsule preservation had significant worse PROs: +0.24 COMI (p<.001) and −1.6 OHS points (p<.05), however, effects were much smaller than the minimal clinically important difference (0.95 and 5 respectively). The date of surgery (i.e. surgeon's age) was not a significant factor. In this large retrospective study, we observed statistically significant, but probably clinically not relevant, worse PROs with capsule preservation. It might be speculated that the not resected hypertrophied capsule could have caused this difference

Purpose: To determine if cells isolated from the rabbit joint capsule in post-traumatic joint contractures have altered responses to stimuli and inhibitors. Method: The right knee of three rabbits had cortical windows removed from the femoral condyles followed by 4 weeks of immobilization, a recently developed model of post-traumatic contractures. The contralateral knee served as an unoperated control. Primary cells (2.5 × 105 cells/ml) isolated from the posterior capsule were mixed with neutralized bovine collagen solution and then cast into tissue culture plate wells. Gelation occurred overnight and then the cells were treated with 1% serum replacement (control), 10 ng/mL TGF-beta1, and the TGF-beta1 receptor kinase inhibitor SB431542 at 10 microM or 0.1 microM. Gel contraction was measured at 24 post release from the edges of the well using captured images of the gels and computer software. Results: In all groups the contracture (injured) knees displayed significantly greater collagen gel contraction than control capsule cells. The addition of the TGF-beta1 increased, while SB431542 at the higher dose decreased, the extent of contraction by contracture and control cells. The TGF-beta1 contraction effect was neutralized by the addition of the inhibitor at the higher dose. In terms of sensitivity to the manipulations, the contracture capsule cells had greater responses to the stimulant and inhibitor. Conclusion: This work is significant as this is the first description of joint capsule cell properties. In post-traumatic contractures, these cells have an intrinsically increased contraction ability at baseline conditions (serum replacement), and these cells also have heightened responses to TGF-beta1 and the TGF-beta1 receptor kinase inhibitor SB431542, a known pathway associated with fibrosis. These results support future work modifying this pathway directly, or by manipulating cells that liberate TGF-beta1. One such strategy would be to prevent mast cells from degranulating as they are a source of TGF-beta1 and other profibrotic growth factors, cytokines and enzymes

Purpose. While changes in lower limb alignment and pelvic inclination after total hip arthroplasty (THA) using certain surgical approaches have been studied, the effect of preserving the joint capsule is still unclear. We retrospectively investigated changes in lower limb alignment, length and pelvic inclination before and after surgery, and the risk of postoperative dislocation in patients who underwent capsule preserving THA using the anterolateral-supine (ALS) approach. Methods. Between July 2016 and March 2018, 112 hips (non-capsule preservation group: 42 hips, and capsule preservation group: 70 hips) from patients with hip osteoarthritis who underwent THA were included in this study. Patients who underwent spinal fusion and total knee arthroplasty on the same side as that of the THA were excluded. Using computed tomography, we measured lower limb elongation, external rotation of the knee, and femoral neck/stem anteversion before operation and three to five days after operation. We examined the pelvic inclination using vertical/transverse ratio of the pelvic cavity measured by X-ray of the anteroposterior pelvic region in the standing position before and six to 12 months after operation. All operations were performed using the ALS approach and taper wedge stem. Results. No dislocation was found in both groups. Lower limb elongation was 14.5±6.3 (mean±SD) mm in the non-capsule preservation group and 9.4±8.8 mm in the capsule preservation group. A significant reduction was found in the capsule preservation group (p<0.05). Changes in knee external rotation was 7.2±10.5 degrees in the non-capsule preservation group and 3.5±10.3 degrees in the capsule preservation group. A trend toward decreased knee external rotation in the capsule preservation group (p=0.07) was observed. There was no difference in femoral neck/stem anteversion and vertical/transverse ratio of the pelvic cavity between both groups. Discussion. Patients in the capsule preservation group tended to have reduced external rotation of lower limb, which might prevent postoperative anterior dislocation due to preservation of anterior structures. The capsule preservation group had significantly reduced lower limb elongation, suggesting that preservation of the hip joint capsule ligament contributes to joint stability. There was no significant difference in the pelvic inclination between both groups. Long-term changes will be assessed by regular follow up after operation

Purpose: Elbow osteoarthritis (OA) is characterized by a loss of elbow motion secondary to joint capsular hypertrophy and osteophyte formation. Previous work on joint capsules in post-traumatic (PT) elbow joint contractures has shown that alterations in cell populations (increased number of alpha-SMA positive myofibroblasts), matrix molecule and enzyme, and growth factor mRNA profiles are associated with loss of elbow motion in this condition. The objective of this study was to determine whether alterations in joint capsule parameters were similar or different in two etiologies of human elbow contractures, primary OA and PT. Method: Posterior elbow joint capsules were obtained from eight male patients with primary elbow OA (age 52±12 yr ), five male patients with chronic (> 1 year) PT (age 47±12 yr ) and four male organ donors free of OA and contractures (age 43±10 yr ). RNA was extracted for subsequent real-time PCR for alpha-SMA, interleu-kin-1beta, MMP-1, MMP-3, collagen type III, biglycan, versican, tenascin C, TIMP-1, MMP-2, iNOS, COX-2, glyceraldehyde – 3 phosphate dehydrogenase (GAPDH) and 18S. 18S was used to normalize gene expression. Statistical comparisons used a oneway ANOVA followed by posthoc Tukey test. Significance was p < 0.05. Results: The mRNA levels in the OA and PT capsules were increased compared to controls in most cases. This includes the major matrix molecule collagen I and the myofibroblast marker alpha-SMA, the growth factors TGF-beta1 and CTGF plus decorin, the injury response elements (collagen III, biglycan, versican, tenascin C) as well as TIMP-1 and MMP-2. The housekeeping gene GAPDH was similar in all 3 groups as was COX-2, while iNOS was elevated in both groups characterized by contractures. When comparing the two contracture groups, the mRNA levels were similar for some molecules while differences were evident in other instances. In PT, alpha-SMA and collagen I were greater than in OA. Conversely, in the OA group, the growth factors and matrix enzyme systems exhibited higher levels than PT. Conclusion: In this study of human elbow joint capsules, we have shown that relative mRNA levels for markers of myofibroblasts, major matrix components, injury response elements and selected growth factors are significantly elevated in elbow OA and post-traumatic contractures when compared to age matched organ donor controls free of contractures. When comparing the OA and PT groups, the injury response molecules were elevated to similar relative levels. The OA group had greater increases in the growth factors and many of the matrix enzymes / inhibitors measured, while the PT group had greater increases in the myofibroblast marker alpha-SMA and the major matrix molecule collagen I. Thus in general matrix, growth factor and cellular properties appear to be preferentially altered in the two conditions studied when compared to control tissues, strengthened by the fact that the housekeeping gene GAPDH had similar relative levels in all 3 groups

Objectives. We have encountered patients who developed large joint fluid collections with massive elevations in chromium (Cr) and cobalt (Co) concentrations following metal-on-metal (MoM) hip arthroplasties. In some cases, retrieval analysis determined that these ion concentrations could not be explained simply by the wear rates of the components. We hypothesized that these effects may be associated with aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL). Patients and Methods. We examined the influence of the ALVAL grade on synovial fluid Co and Cr concentrations following adjustment for patient and device variables, including volumetric wear rates. Initially restricting the analysis to include only patients with one MoM hip resurfacing device, we performed multiple regression analyses of prospectively collected data. We then repeated the same statistical approach using results from a larger cohort with different MoM designs, including total hip arthroplasties. Results. In the resurfacing cohort (n = 76), the statistical modelling indicated that the presence of severe ALVAL and a large fluid collection were associated with greater joint fluid Co concentrations after adjustment for volumetric wear rates (p = 0.005). These findings were replicated in the mixed implant group (n = 178), where the presence of severe ALVAL and a large fluid collection were significantly associated with greater fluid Co concentrations (p < 0.001). Conclusion. The development of severe ALVAL is associated with elevations in metal ion concentrations far beyond those expected from the volumetric loss from the prosthetic surfaces. This finding may aid the understanding of the sequence of events leading to soft-tissue reactions following MoM hip arthroplasties. Cite this article: D. J. Langton, R. P. Sidaginamale, T. J. Joyce, J. G. Bowsher, J. P. Holland, D. Deehan, A. V. F. Nargol, S. Natu. Aseptic lymphocyte-dominated vasculitis-associated lesions are related to changes in metal ion handling in the joint capsules of metal-on-metal hip arthroplasties. Bone Joint Res 2018;7:388–396. DOI: 10.1302/2046-3758.76.BJR-2018-0037

Purpose: To determine if mast cell activity is vital to the induction of joint capsule fibrosis and contracture formation in a rabbit model of posttraumatic joint contracture. Method: To reproducibly induce joint contractures, we used a model of surgical injury and immobilization of the knee in skeletally mature New Zealand white rabbits. Four animals groups were studied: a non-operative control group (CON), an operative contracture group (ORC) and two-operative groups treated with a mast cell stabilizer, Ketotifen fumarate at doses of 0.5mg/kg (KF0.5) and 1.0mg/kg (KF1.0) twice daily subcutaneously, respectively. Animals were sacrificed after 8 weeks of immobilization. Flexion contractures (biomechanics), cellular counts of myofibroblasts and mast cells within the joint capsule (immunohistochemistry) and the joint capsule protein expression of TGF-β1, collagen I and III were quantified (western blots). Biomechanical data was interpreted using a linear regression analysis of repeated measures and an ANOVA analysis of variance was used for molecular data. Significance was defined at p< 0.05 for all statistical tests. Results: Flexion contractures were most severe in the ORC group and treatment with Ketotifen (both KF0.5 and KF1.0) significantly reduced contracture severity by 52% and 42%, respectively (p< 0.03). Joint capsule myofibroblast and mast cell hyperplasia was a prominent feature of the more severely contracted ORC group and myofibroblast and mast cell numbers were dramatically reduced in both Ketotifen groups (p< 0.001). The expression of TGF-β1 and collagen I was also increased in the ORC group and significantly reduced in both Ketotifen groups (p< 0.01). Conclusion: Joint capsule fibrosis, characterized by hyperplasia of myofibroblasts and mast cells and enhanced collagen deposition, is a prominent feature of posttraumatic joint contractures in this animal model. Treatment with a mast cell stabilizer reduced the molecular markers of joint capsule fibrosis and the resultant biomechanical severity of contracture formation. These results suggest mast cell activity may be an important process in the development of posttraumatic contractures and future work is needed to determine if pharmacological inhibition of mast cell activity has a preventative or therapeutic role in humans

Aims: The aim of the study was to investigate the cap-suloligamentous structures of the shoulder joint and their association with rotator cuff tendons. Methods: Twenty seven alcohol-formalin-glycerol þxed right shoulder joints (age range 65 Ð 78 years) were investigated. The Ligg. coracohumerale, coracoglenoidale, glenohumeralia, semicirculare humeri and gleno-capsulare were dissected in þne detail. To visualise the rotator interval, the Processus coracoideus was cut at its base and moved together with the Ligg. coracohumerale and coracoglenoidale posteriorly. The analysis of the ligamentous structures and their relations with the rotator cuff tendons was performed. Results: The Lig. coracohumerale originated from Processus coracoideus and Lig. coracoglenoidale. It inserted into the Lig.semicirculare humeri Ð a capsular ligament spread between Tubercula minus et majus. Lig. glenocapsulare originated posterior to the Tuberculum supragle-noidale and inserted into the Lig. semicirculare humeri. The Mm. supra- and infraspinatus inserted into the Lig. semicirculare humeri. The anterior capsule was strengthened in addition to the three Ligg. glenohumeralia with a Lig. glenohumerale spirale. It originated from the Tuberculum infraglenoidale, coursed craniolaterally and inserted together with the M. subscapularis tendon at the Tuberculum minus. Conclusions: The shoulder joint capsule is strengthened with the Ligg. coracohumerale, coracoglenoidale, glenohumeralia superior, medium, inferior et spirale and Ligg. semicirculare humeri et glenocapsulare. The close relation of the ligamentous structures with the tendons of the rotator cuff brings a new insight into the different glenohumeral pathologies

The role of inflammatory cells in aseptic loosening and failure of cemented joint replacements is unclear. Inflammatory cells from the revision joint capsule of four failed hip arthroplasties were examined to determine their nature and resorptive capacity. The capsules contained numerous macrophages and abundant foreign-body macrophage polykaryons, distinguished from osteoclasts by their antigenic phenotype and lack of response to calcitonin. When cultured on cortical bone slices in vitro, both macrophages and macrophage polykaryons produced small resorption pits and were associated with areas of superficial resorption of the bone surface. These results indicate that foreign-body induced macrophages and macrophage polykaryons are capable of a type of low-grade bone resorption which may be of pathogenic significance in the loosening of cemented joint prosthetic components

We aimed to determine if there are mechanoreceptors in hip joint capsule and ligamentum capitis femoris of the patients with developmental dysplasia of the hip. We took capsule and ligamentum capitis femoris biopsies from 20 hips of 20 patients who were operated because of developmental dysplasia of the hip. Meanage was 10.2 months (ranges 6-20 months) on the time of surgery. There were 12 girls and 8 boys. Teratologic and secondary hip dislocations were not included in this study. 0.5x 0.5 cm full thickness anterior capsule and liga-mentum capitis femoris portions were taken for biopsy specimen. Specimens were stained with hemotoxylin eosin and examined immunohistochemically using poly-clonal antibodyagainst S-100 Protein. In both analysis no mechanoreceptors was found in any samples of capsule and ligamentum capitis femoris. Conclusion: We think that there is a possibility that developmental dysplasia of the hip can be caused from a defect in formation of mechanoreceptors on localized capsule and ligamentum capitis femoris and we emphasize the need for further studies on the subject

In terms of function, range of movement is an important measure of outcome. The purpose of this study was to determine whether or not stripping the capsule of the distal femur at the time of primary total knee arthroplasty had a significant effect on the range of knee movement achieved at the end of the operation. An improvement of 5 degrees or more was considered significant. One hundred and twenty-five patients (47 males; 78 females) presenting for primary total knee arthroplasty were recruited. All operations were performed by the senior author using the LCS rotating platform system without patellar resurfacing. Preoperatively, the tip of the greater trochanter, the lateral femoral epicondyle and the anterior border of the lateral malleolus were marked. Using a digital camera, images of the limb proposed for surgery were taken with the knee in extension, forced extension, flexion and forced flexion. Camera set up was standardised for all photographs. Using a random numbers program, patients were randomised either to have release of the posterior knee joint capsule or not. The surgeon was informed at the time of the operation. At the end of the procedure the digital images were repeated. Total arc of knee movement preoperatively ranged from 41° to 161° (average, 115°). Postoperatively, this varied from 95° to 157° (average, 124°). Average arc of knee movement was 125° for the no release group and 123° for the released group. Of the 78 patients where the increase in total arc of knee motion was significant, 41 had been released and 37 had not. No statistically significant difference was noted. In conclusion, we report that releasing the posterior capsule of the knee joint routinely during primary total knee arthroplasty conveys no significant advantage in terms of the range of knee motion achieved immediately following surgery. Consequently, it is unlikely to increase the long-term range of movement

The hypothesis is that cells isolated from capsules of joints with contractures will contract collagen gels at a faster rate when compared to cells obtained from capsules of joints free of contractures. Post-traumatic joint contractures were produced by removing cortical bone windows from the femoral condyles of three skeletally mature rabbits and immobilizing the knees for four weeks with a K-wire. The contralateral knees served as an unoperated control. At sacrifice, the posterior capsules were immediately placed in medium and the tissue was minced. Upon confluence, cells were trypsinised and gel contraction studies were carried out on passage four cells. Five x 105 cells/ml were mixed with 58% neutralised bovine collagen solution and five hundred microlitres of collagen gel/cells solution were then cast into wells of a tissue culture plate. Gelation occurred overnight at 37C in a humidified incubator containing 5% CO2. At cultured day zero, day one, day three, the gels were released from the well walls. The areas of the gel were measured using an image analyzer immediately after release (zero hour), and one hour, two hour, three hour and four hour post-release. The amount the collagen gels were contracted depended on the time of preincubation of cells and collagen before release and the source of the joint capsule cells. In general, increasing the time of preincubation heightened the contractile response of the cells. The collagen gel contraction was small for the day zero groups over the first four hours, but for the day three groups the rate of contraction was markedly increased. In all cases the collagen gel contraction was larger for the contracture capsule cells when compared to the control capsule cells. The patterns of the contraction over the four hours post release were similar for contracture and control groups. Cells from capsules of joints with post-traumatic contractures have intrinsically heightened in vitro contractile properties when compared to normal cells. Future work will determine whether the response is exaggerated to fibrotic stimuli such as TGF-beta1 in these capsule cells from post-traumatic joint contractures

Several studies have evaluated the risk of peroneal nerve (PN) injuries in all-inside lateral meniscal repair using standard knee magnetic resonance imaging (MRI) with the 30 degrees flexed knee position which is different from the knee position during actual arthroscopic lateral meniscal repair. The point of concern is “Can the risk of PN injury using standard knee MRIs be accurately determined”. To evaluate and compare the risk of PN injury in all-inside lateral meniscal repair in relation to both borders of the popliteus tendon (PT) using MRIs of the two knee positions in the same patients. Using axial MRI studies with standard knee MRIs and figure-of-4 with joint fluid dilatation actual arthroscopic lateral meniscal repair position MRIs, direct lines were drawn simulating a straight all-inside meniscal repair device from the anteromedial and anterolateral portals to the medial and lateral borders of the PT. The distance from the tip of each line to the PN was measured. If a line touched or passed the PN, a potential risk of iatrogenic injury was noted and a new line was drawn from the same portal to the border of the PN. The danger area was measured from the first line to the new direct line along the joint capsule. In 28 adult patients, the closest distances from each line to the PN in standard knee MRI images were significantly shorter than arthroscopic position MRI images (all p-values < 0.05). All danger areas assessed in the actual arthroscopic position MRIs were included within the danger areas as assessed by the standard knee MRIs. We found that the standard knee MRIs can be used to determine the risk of peroneal nerve injury in arthroscopic lateral meniscal repair, although the risks are slightly overestimated

Aims. Surgical approaches that claim to be minimally invasive, such as the direct anterior approach (DAA), are reported to have a clinical advantage, but are technically challenging and may create more injury to the soft-tissues during joint exposure. Our aim was to quantify the effect of soft-tissue releases on the joint torque and femoral mobility during joint exposure for hip resurfacing performed via the DAA. Methods. Nine fresh-frozen hip joints from five pelvis to mid-tibia cadaveric specimens were approached using the DAA. A custom fixture consisting of a six-axis force/torque sensor and motion sensor was attached to tibial diaphysis to measure manually applied torques and joint angles by the surgeon. Following dislocation, the torques generated to visualize the acetabulum and proximal femur were assessed after sequential release of the joint capsule and short external rotators. Results. Following initial exposure, the ischiofemoral ligament (7 to 8 o’clock) was the largest restrictor of exposure of the acetabulum, contributing to a mean 25% of overall external rotational restraint. The ischiofemoral ligament (10 to 12 o’clock) was the largest restrictor of exposure of the proximal femur, contributing to 25% of overall extension restraint. Releasing the short external rotators had minimal contribution in torque generated during joint exposure (≤ 5%). Conclusion. Adequate exposure of both proximal femur and acetabulum may be achieved with minimal torque by performing a full proximal circumferential capsulotomy while preserving short external rotators. The joint torque generated and exposure achieved is dependent on patient factors; therefore, some cases may necessitate further releases. Cite this article: Bone Joint J 2024;106-B(3 Supple A):59–66

Osteoarthritis (OA) of the hip is the most common indication for total hip replacement (THR). Obesity is a risk factor for the development of OA and has recently resulted in patients requiring THRs at much younger ages to relieve pain at the joint capsule and restore mobility. However, the impact of obesity on THR mortality is not well understood. An updated systematic review was performed to identify whether an obese BMI should influence patient selection for surgery. Specifically, the impact of obesity on short-term mortality, long-term mortality, and peri- and post-operative complications was assessed with a particular focus on BMI classes. A comprehensive literature search of Ovid Medline and EMBASE in November 2022 identified relevant papers in accordance with PRISMA methodology. After removing duplicates, 2988 articles underwent strict inclusion and exclusion criteria, resulting in 12 papers for analysis. There was no statistically significant difference in mortality risk between obese and non-obese populations. Obesity was associated with a lower risk of short-term mortality than in the normal weight control group, however there was an increased mortality risk in obese patients long-term likely due to comorbidities. Obese patients were significantly younger than normal BMI and underweight patients. However, the paper found increased mortality risk in underweight and morbidly obese patients. Obese patients did not have an increased risk of mortality when compared to non-obese patients following THR. Obesity may have a protective effect on mortality up to a BMI of 40kg/m2, although this may be influenced by the obesity paradox which states only the healthiest obese individuals are selected for surgery, which could attribute to a lower mortality risk. The greatest risk of mortality and complication was associated with underweight patients. As a result, a BMI greater than 30kg/m2 may not necessitate a hip replacement contraindication. It is important surgeons apply careful consideration and comprehensive risk assessment on patients who require a THR, especially at the BMI extremes

The diagnosis of infection following shoulder arthroplasty is notoriously difficult. The prevalence of prosthetic shoulder infection after arthroplasty ranges from 3.9 – 15.4% and the most common infective organism is Cutibacterium acnes. Current preoperative diagnostic tests fail to provide a reliable means of diagnosis including WBC, ESR, CRP and joint aspiration. Fluoroscopic-guided percutaneous synovial biopsy (PSB) has previously been reported in the context of a pilot study and demonstrated promising results. The purpose of this study was to determine the diagnostic accuracy of percutaneous synovial biopsy compared with open culture results (gold standard). This was a multicenter prospective cohort study involving four sites and 98 patients who underwent revision shoulder arthroplasty. The cohort was 60% female with a mean age was 65 years (range 36-83 years). Enrollment occurred between June 2014 and November 2021. Pre-operative fluoroscopy-guided synovial biopsies were carried out by musculoskeletal radiologists prior to revision surgery. A minimum of five synovial capsular tissue biopsies were obtained from five separate regions in the shoulder. Revision shoulder arthroplasty was performed by fellowship-trained shoulder surgeons. Intraoperative tissue samples were taken from five regions of the joint capsule during revision surgery. Of 98 patients who underwent revision surgery, 71 patients underwent both the synovial biopsy and open biopsy at time of revision surgery. Nineteen percent had positive infection based on PSB, and 22% had confirmed culture positive infections based on intra-operative tissue sampling. The diagnostic accuracy of PSB compared with open biopsy results were as follows: sensitivity 0.37 (95%CI 0.13-0.61), specificity 0.81 (95%CI 0.7-0.91), positive predictive value 0.37 (95%CI 0.13 – 0.61), negative predictive value 0.81 (95%CI 0.70-0.91), positive likelihood ratio 1.98 and negative likelihood ratio 0.77. A patient with a positive pre-operative PSB undergoing revision surgery had an 37% probability of having true positive infection. A patient with a negative pre-operative PSB has an 81% chance of being infection-free. PSB appears to be of value mainly in ruling out the presence of peri-prosthetic infection. However, poor likelihood ratios suggest that other ancillary tests are required in the pre-operative workup of the potentially infected patient

Ligaments, menisci and joint capsules were obtained from experimental knees with post-traumatic joint contractures and their unoperated contralateral controls in 6 rabbits. Relative mRNA expression was altered for six of seven matrix molecules, growth factors and _-SMA (myofibroblast marker) in the joint capsule, four of seven molecules in the ACL, and two of seven molecules in the MCL and medial meniscus. The joint capsule had the most molecules with altered expression corresponding to it’s acknowledged key role in joint contracture development. Changes in molecular expression of several joint structures in post-traumatic contractures is similar to changes seen following ligament injury. To evaluate alteration of mRNA expression in ligaments, meniscus and joint capsules in post-traumatic contractures. mRNA expression was altered most frequently in the joint capsule. The mRNA expression alterations in the joint capsule reflect it’s significant contribution to contractures. The right knee had a stable intraarticular fracture coupled with Kirschner wire immobilization while the left knee was not surgically manipulated. The rabbits (n=6) were sacrificed two weeks later, and the ACL, MCL, posterior joint capsule and medial meniscus were obtained from both knees. Semiquantitative RT-PCR was used to evaluate relative mRNA expression of selected matrix molecules, growth factors and _-smooth muscle actin (_-SMA), a myofibroblast marker. Glyc-eraldehyde-3-phosphate dehydrogenase, a housekeeping gene, served as a normalization. Optical density measures of the gels were used for analysis. Statistical comparisons were made with a paired t-test. Statistical significance was p< 0.05. Relative mRNA expression was altered for six of seven molecules in the joint capsule, four of seven molecules in the ACL, and two of seven molecules for the MCL and meniscus. For the joint capsule, relative mRNA expression in the contracture capsule was 2-4x greater than the expression in the control capsules, except for TIMP one where the expression in the contracture capsule was 1/3 of the control capsules. As has been noted with other joint injuries (ligament instability), several structures in the joint display altered molecular expression as was found in this model of joint injury, post-traumatic joint contractures. Please contact author for tables and/or graphs

In developmental dysplasia of the hip, a deficient acetabulum may be augmented by placing local autogenous iliac osseous graft, or the ilium itself, over the head of the femur with the expectation that the added bone will function as a bearing surface. We analysed this bone obtained en bloc during subsequent surgery which was performed for degenerative osteoarthritis in three patients at 6, 25 and 30 years after the initial augmentation procedure. In each patient, the augmentation comprised of red cancellous bone covered on its articulating surface by a distinct layer of white tissue. Microscopy of this tissue showed parallel rows of spindle-shaped cells lying between linearly arranged collagen bundles typical of joint capsule. Biochemical analysis showed type I collagen, the principal collagen of joint capsule and bone, with no significant quantity of type II collagen, the principal collagen of cartilage. While the added bone produced by acetabular augmentation was durable, histological and biochemical analyses suggested that it had not undergone cartilage metaplasia. The augmented acetabulum articulates with the head of the femur by means of an interposed hip joint capsule