As our understanding of hip function and disease improves, it is evident that the acetabular fossa has received little attention, despite it comprising over half of the acetabulum’s surface area and showing the first signs of degeneration. The fossa’s function is expected to be more than augmenting static stability with the ligamentum teres and being a templating landmark in arthroplasty. Indeed, the fossa, which is almost mature at 16 weeks of intrauterine development, plays a key role in hip development, enabling its nutrition through vascularization and synovial fluid, as well as the influx of chondrogenic stem/progenitor cells that build articular cartilage. The pulvinar, a fibrofatty tissue in the fossa, has the same developmental origin as the synovium and articular cartilage and is a biologically active area. Its unique anatomy allows for homogeneous distribution of the axial loads into the joint. It is composed of intra-articular adipose tissue (IAAT), which has adipocytes, fibroblasts, leucocytes, and abundant mast cells, which participate in the inflammatory cascade after an insult to the joint. Hence, the fossa and pulvinar should be considered in decision-making and surgical outcomes in hip preservation surgery, not only for their size, shape, and extent, but also for their biological capacity as a source of cytokines, immune cells, and chondrogenic stem cells. Cite this article: Bone Joint Res 2020;9(12):857–869

In this in vitro study of the hip joint we examined which soft tissues act as primary and secondary passive rotational restraints when the hip joint is functionally loaded. A total of nine cadaveric left hips were mounted in a testing rig that allowed the application of forces, torques and rotations in all six degrees of freedom. The hip was rotated throughout a complete range of movement (ROM) and the contributions of the iliofemoral (medial and lateral arms), pubofemoral and ischiofemoral ligaments and the ligamentum teres to rotational restraint was determined by resecting a ligament and measuring the reduced torque required to achieve the same angular position as before resection. The contribution from the acetabular labrum was also measured. Each of the capsular ligaments acted as the primary hip rotation restraint somewhere within the complete ROM, and the ligamentum teres acted as a secondary restraint in high flexion, adduction and external rotation. The iliofemoral lateral arm and the ischiofemoral ligaments were primary restraints in two-thirds of the positions tested. Appreciation of the importance of these structures in preventing excessive hip rotation and subsequent impingement/instability may be relevant for surgeons undertaking both hip joint preserving surgery and hip arthroplasty. Cite this article: Bone Joint J 2015; 97-B:484–91

Introduction: Injuries to the ligamentum teres are being recognised more often with developments in imaging, such as MR arthrography, and the increasing use of hip arthroscopy. But they are difficult to diagnose, and it is not clear how best to treat them. Little is known about the mechanism of injury, nor the potential impact on hip stability of such injuries. The relationship between capsular and ligamentous contributions to stability has not been investigated. Methods: We examined the movement of the ligamentum teres in intact, fully reduced, cadaveric hip specimens by trans osseus arthroscopy. The movement of the ligamentum teres was captured with video throughout the excursion of the hip joint. The influence of restraining capsular structures was determined by sequential transection and repeat excursion testing. Ligamentum teres injuries were generated by extreme movements, and compared with clinically observed injuries. Results: The action of the ligamentum teres was successfully recorded in by video. The ligament was found to be the principal restraint to external rotation in extension and abduction. Injuries generated by forced rotation in this position resembled those seen in clinical practice. Conclusion: Knowledge of the action of the ligamentum teres will improve our understanding of injury to this structure. It helps to identify described mechanisms which should raise suspicion of such an injury, and may help to design investigation and treatment protocols

Aim. The aim of this study was to assess the role of hip arthroscopy in the management of hip pain in elite athletes. Patients and methods. It is a retrospective study of prospectively collected data. 31 hip arthroscopies were performed on 27 elite athletes. All the patients were assessed pre-operatively with a thorough clinical examination, radiographs and MRI scans. The modified HHS was also recorded for all the patients' pre and post-operatively. All operations were performed by the senior author, and the patients were assessed at 6 weeks, 3 months, 6 months and a year following the operation. Results. The M:F ratio was 25:2 with an average age of 38 years (Range: 18-58) in the study group. 65% of the patients were professional football players followed by cricket and tennis. The patients were referred at an average of 506 days. Two of the 27 patients demonstrated minimal acetabular dysplasia on their pre-operative radiographs. Of the 31 arthroscopies, a primary diagnosis of a labral tear was made in 20, a chondral flap and delamination in 5, early osteoarthritis in 4 and a ligamentum teres tear in 2. Along with the primary diagnosis of a labral tear, twelve of the 20 patients had a secondary diagnosis of chondral injury and or Femeroacetabular Impingement as well. There were no complications reported. Conclusions. Hip Injuries in athletes are reported late and Chondral Flaps and Ligamentum teres tears are under-diagnosed. Most athletes have a good chance to return back to the original level of sport within 4 months following hip arthroscopy. However, about 40% do continue to have some form of pain. Hip arthroscopy is a safe and effective method for diagnosis and treatment of intra-articular disorders in elite athletes

Hip arthroscopy is a relative newcomer to the arthroscopic repertoire, yet even in its current infancy has shown the hip joint in a different light. One poorly understood area is the ligamentum teres, thought by many to do little more than carry a blood vessel in the developing hip. Ligamentum injuries have only rarely been described, though in recent years have been arthroscopically classified. We present a large series of ligamentum teres abnormalities treated by hip arthroscopy. Of 925 consecutive hip arthroscopies, 68 patients (73 hips) had either a complete ligamentum tear (Type I), partial ligamentum tear (Type II), or a degenerate ligamentum (Type III). Only 4 patients had a correct diagnosis given prior to hip arthroscopy. Hyperadduction was the commonest cause of Type I tears, though not all tears had a traumatic aetiology. Complete tears have a shorter history and a higher chance of associated intra-articular damage. Partial tears typically have a long history of ill-defined hip pain. The degenerate ligamentum generally presents with the features of underlying osteoarthritis. At three-year review, Type I and II tears improved significantly following hip arthroscopy, Type III abnormalities less so. This paper thus presents the largest series of ligamentum tears to-date reported

Objectives. An experimental piglet model induces avascular necrosis (AVN) and deformation of the femoral head but its secondary effects on the developing acetabulum have not been studied. The aim of this study was to assess the development of secondary acetabular deformation following femoral head ischemia. Methods. Intracapsular circumferential ligation at the base of the femoral neck and sectioning of the ligamentum teres were performed in three week old piglets. MRI was then used for qualitative and quantitative studies of the acetabula in operated and non-operated hips in eight piglets from 48 hours to eight weeks post-surgery. Specimen photographs and histological sections of the acetabula were done at the end of the study. . Results. The operated-side acetabula were wider, shallower and misshapen, with flattened labral edges. At eight weeks, increased acetabular cartilage thickness characterised the operated sides compared with non-operated sides (p < 0.001, ANOVA). The mean acetabular width on the operated side was increased (p = 0.015) while acetabular depth was decreased anteriorly (p = 0.007) and posteriorly (p = 0.44). The cartilage was thicker, with delayed acetabular bone formation, and showed increased vascularisation with fibrosis laterally and focal degenerative changes involving chondrocyte hypocellularity, chondrocyte cloning, peripheral pannus formation and surface fibrillation. . Conclusions. We demonstrate that femoral head AVN in the young growing piglet also induced, and was coupled with, secondary malformation in acetabular shape affecting both articular and adjacent pelvic cartilage structure, and acetabular bone. The femoral head model inducing AVN can also be applied to studies of acetabular maldevelopment, which is less well understood in terms of developing hip malformation. Cite this article: Bone Joint Res 2014;3:130–8

Femoroacetabular impingement is a condition in which the femoral head/neck region abnormally contacts the acetabulum, limiting the range of motion of the hip and often associated with pain, damage, and loss of function. The pathophysiology of osteoarthritic changes stemming from impingement syndromes has been linked to the shape of the hip; however, little is known about the influence of the soft tissues to this process. In this pilot study, we used computer-assisted navigation technology to track motion on a cadaver that had mild bilateral cam-impingement lesions, and then performed a virtual simulation to locate sites of impingement. We hypothesised that soft tissues contribute to the degree and location of impingement, so we compared impingements across three different dissection states: (i) all soft tissues intact; (ii) post-capsulectomy; with only the labrum and ligamentum teres remaining; and (iii) disarticulated, with labrum and ligamentum teres removed. With ethical approval, we used one fresh frozen cadaver pelvis that was sectioned above the fifth lumbar vertebra and at the knee. The femurs and pelvis were implanted with fiducial screws as an accurate means for surface-based image registration. With all soft tissues intact, tissues were imaged using computed tomography with a slice thickness of 0.625 mm. The CT scans were imported into Mimics (v13.0, Materialise, Belgium) and carefully segmented, with particular detail to the articular regions and fiducials, to create 3D digital models of the pelvis and femurs. On each side, optical local coordinate reference (LCR) bodies were attached at the proximal femur and iliac crest to permit spatial tracking with an Optotrak Certus camera (Northern Digital Inc., Waterloo, Canada). The 3D digital models were imported into the VSS navigation system (iGO Technologies, Kingston, Canada) and scrupulously registered to the anatomy using the fiducial screws and a calibrated probe. The pose of the femur and pelvis were recorded throughout a series of twelve movements involving various combinations of flexion-extension, abduction-adduction, internal-external rotation and circumduction, as well as functional movements typical of a clinical hip screening. Soft tissues were selectively removed and the movements were repeated post-capsulectomy and completely disarticulated. The recorded pose data were applied to the 3D digital models to perform a computational simulation of the movements during the trials. The pose data were expressed in coordinates of the anterior pelvic plane to compute angles of motion in the principal directions (flexion, abduction, rotation). The motion data were further filtered so that only comparable ranges of motion were present for data analysis. Algorithms were developed to determine bone-on-bone impingement locations by finding contact points between the models. Impingement locations were plotted on the digital models of the femur and pelvis in order to establish zones of impingement. The surface area of each impingement zone was computed by using a Crust-based algorithm that triangulated impingement points encompassing a region, and then summed the surface area of each triangle to estimate the total impingement surface area. Upon visual inspection, it was immediately apparent that impingements tended to occur in well-defined regions. On the femur, these were found along aspects of the head-neck junction, especially on or near osteophytes. On the pelvis, impingement regions were found along the acetabular rim and extending into the lunate region. With soft tissues intact, both femurs and pelvis had prominent anterior and posterior impingement zones. In contrast, post-capsulectomy impingement zones were predominately confined to the anterior region. It should be noted, however, that the total impingement area decreased post-capsulectomy, representing only about 25% of the total area of impingements when all soft tissues were intact. This was also true in the disarticulated state. Both femurs had mild posterior cam lesions, the right worse than the left. Impingements were seen at these sites with soft tissues intact, but diminished almost entirely post-capsulectomy. The anterior lesions were located contra coup to these cam lesions. With soft tissues intact, impingements tended to occur in external rotation and abduction. With soft tissues removed there was a pronounced shift towards impingements occurring in internal rotation. Impingements were also noted in large flexion angles and large abduction-adduction angles in the absence of soft tissues. Although it is widely accepted that the hip is spherical in shape and has ball-and-socket kinematics, recent work suggests that the osteoarthritic hip is aspherical and that translational motion is present. On a very limited series, this work is supportive of the latter observation: if hip motion is purely spherical, a decrease in impingements post-capsulectomy is exceedingly hard to describe. However, if soft tissues cause translatory motion, then their absence logically should lead to a change in the impingement pattern (which we found). This preliminary study provides a methodology for studying the effects of soft tissue on impingements. We conclude that soft tissues do indeed play an important role in impingement and may even contribute to the development of impingement lesions. Limitations include a small sample size, so further studies are required prior to conclusively establishing impingement patterns in passive kinematics of cadaver hips

This in-vitro study finds which hip joint soft tissues act as primary and secondary passive internal and external rotation restraints so that informed decisions can be made about which soft tissues should be preserved or repaired during hip surgery. The capsular ligaments provide primary hip rotation restraint through a complete hip range of motion protecting the labrum from impingement. The labrum and ligamentum teres only provided secondary stability in a limited number of positions. Within the capsule, the iliofemoral lateral arm and ischiofemoral ligaments were primary restraints in two-thirds of the positions tested and so preservation/repair of these tissues should be a priority to prevent excessive hip rotation and subsequent impingement/instability for both the native hip and after hip arthroplasty

Open reduction of DDH is indicated in late presenting cases and those who fail Pavlik Harness treatment, if closed reduction is unsuccessful. Recognised techniques involve excision of the ligamentum teres to allow maximal medialisation of the femoral head into the acetabulum. We describe a new technique in which the ligament’s femoral attachment is preserved and the medial end is passed through the incised transverse ligament. Gentle traction on the medial end is used to aid reduction and when sutured to the anterior capsule, the reduction is stabilised. We present our operative experience and early follow up of 8 cases

Introduction. We present a single surgeon series of 20 modified Dunn osteotomies without surgical dislocation of the femoral head for slipped upper femoral epiphysis (SUFE). Method. All patients from 2007 to 2011 who had a Dunn osteotomy for SUFE had their notes reviewed and we obtained an updated Non Arthritic Hip Score. Results. 20 patients were identified, of which 5 were female, with a combined average age of 14. The average duration of symptoms prior to the procedure was 10.2 weeks (range, 4–78). Classifications divided the cases into 7 chronic slips, 7 acute-on-chronic, and 5 acute., and 7 of the cases were unstable slips with an average slip angle of 71 degrees (range 65–85). All slips were grade 3. Average follow up was 26.2 months (range, 2–62). 3 developed avasular necrosis (2 unstable, 1 stable) and 2 patients had symptomatic leg length discrepancy. Preoperative MRI scans were performed in 4 patients and showed vascular compromise, but this did not always correlate with intraoperative findings of avascularity when the head was drilled. The average Nonarthritic hip score was 71.6 (range, 60–80). Summary. Dunn osteotomies are safe in patients with chronic slips, and have a low incidence of AVN. Overall function was good, even in those patients with segmental AVN scoring highly on their hip scores. Keeping the ligamentum teres intact and not dislocating the femoral head may improve vascularity of the head. Vascularity may also be assessed by preoperative MRI scans, although radiological suggestion of an avascular head which contradicted clinical findings and postoperative outcome may be due to transient vessel spasm

We present our data on a cohort of 25 patients who had an arthroscopy of their hip between the ages of 12 and 17 out of over 1100 hip arthroscopies performed. All patients presented with pain and marked restriction of activities. Either a CT (before MRI was available) or MRI scan was done pre-operatively. 10 patients presented with a history of either Perthes disease, DDH or a defined injury causing their symptoms. In the remaining the onset of symptoms was spontaneous. The intra-operative diagnosis varied: normal (6), labral tear (6), loose bodies (2), debris and/or chondromalacia (8), synovitis (2) and damaged ligamentum teres (1). None of the patients developed a complication. The pre-operative Harris Hip Score ranged from 0 to 40 (mean 21) for pain and 0 to 47 (mean 35) for function. The follow-up ranged from 6 weeks to 9years (mean 3 years). Harris Hip Score at latest follow-up ranged from 10 to 44 (mean 33) for pain and from 31 to 47 (mean 43) for function. Conclusion: Hip arthroscopy is a very useful tool as part of the investigation and treatment of hip problems in carefully selected children and adolescents

Hip arthroscopy is a well-established technique becoming more and more an indispensable tool in institutions specialized in hip diseases. Several surgeons around the world have developed and refined the proper instruments and the surgical technique for this operation. By now, the indications have been well formulated for both diagnostic and interventional purposes. My personal experience is of 98 hip arthroscopies performed in the last 6 years. Most common preoperative indication has been chronic hip pain after failure of conservative treatment. Other indications or arthroscopic findings have been: labral pathology, hip dysplasia, synovial chondromatosis, initial osteoarthritis, calcium pyrophosphate disease, ligamentum teres damage, chondral damage, post-traumatic loose bodies, avascular necrosis, sepsis, villonodular synovitis. More recent, indications for hip arthroscopy are staging of avascular necrosis of the femoral head and shaving of polyethylene debris after total hip replacement. Contraindications to arthroscopy include recent fracture of the pelvis osteoarthritis with osteophytosis, AVN with head collapse. Hip arthroscopy can facilitate both comprehensive access to and treatment of an evolving series of conditions that affect the hip joint. Purpose of this presentation is to show the surgical technique and present the results obtained. New indications and potential future evolutions are also discussed

The cause of unremitting hip joint pain often remains undiagnosed. In the knee, MRI often accurately detects soft tissue pathology, but there is a less than 5% chance that MRI will show an abnormality such as a labral tear. Because conventional surgery can lead to such complications as avascular necrosis, muscle weakness, trochanteric nonunion, heterotopic bone formation, neurovascular injuries and DVT, diagnostic open arthrotomy is seldom performed. Further, prolonged hospitalisation is costly and commits the patient to an extended rehabilitation program. Arthroscopic hip surgery, a relatively new but well-established procedure, permits the identification of previously unrecognised disorders and in some pathologies offers definitive treatment. In young selected patients with OA it serves as a temporary palliative procedure. This presentation is based on the first 50 hip arthroscopies performed by the author. Indications for operation were chronic hip pain without radiologically-discernible cause, the presence of loose bodies following trauma, chondrocalcinosis, labral lesions, chondral injuries, ruptured ligamentum teres, avascular necrosis, early OA, biopsy for suspected RA, and non-specific synovial disease. All patients were in hospital for only a day. Mobilisation was encouraged from day one. Dramatic improvement in previous symptoms was noted postoperatively. In three patients with degenerative changes, pain returned after a mean of 6 months and THR was subsequently performed. Hip arthroscopy is a minimally invasive diagnostic and treatment technique, especially in young patients presenting with hip pain

Aims: Developmental dysplasia of the hip (DDH) is a common paediatric orthopaedic problem. Open reduction and debridement of the hip joint in neonates is necessary to ensure a congruent reduction in some patients. Despite advances in the treatment of DDH, the various surgical approaches are not without limitations and risks. The purpose of this study was: (a) to design a suitable animal model of DDH for the purpose of designing and evaluating hip arthroscopy, (b) to document the pathoanatomy of the dysplastic hip arthroscopically and (c) to deþne the methodology of performing hip arthroscopy in neonates with DDH. Methods: A novel model of producing hip dysplasia in large white cross piglets has been created. 4-week-old piglets undergo surgical þxation of the knee by retrograde passage of a 3.5mm diameter steinmann pin. After free ambulation, progressive hip dysplasia is produced. We have monitored the development of hip dysplasia at 4 and 6 weeks post þxation by plain radiographs, MRI and Hip Arthroscopy using a 2.7mm diameter arthroscope. Results: We have successfully produced hip dysplasia in an animal model of comparable size and anatomy to that seen in infants. Hip arthroscopy was performed in 20 animals. Documentation of a lax capsule, elongated ligamentum teres and pulvinar has been made. In addition arthroscopic debridement of the joint has been performed. We believe that arthroscopic debridement of the impediments to reduction in DDH is possible using the techniques learned from this model

Background: Developmental dysplasia of the hip (DDH) is a common paediatric orthopaedic problem. Open reduction and debridement of the hip joint in neonates is necessary to ensure a congruent reduction in some patients. Despite advances in the treatment of DDH, the various surgical approaches are not without limitations and risks. The development of hip arthroscopy is a new science, which we believe could be applied to the treatment of DDH. Aims: To date there have been no reports in the literature of the use of hip arthroscopy in either the neonatal hip or in infantile hips with DDH. The purpose of this study was: (a) to design a suitable animal model of DDH for the purpose of designing and evaluating hip arthroscopy, (b) to document the pathoanatomy of the dysplastic hip arthroscopically and (c) to define the methodology of performing hip arthroscopy in neonates with DDH. Method: A novel model of producing hip dysplasia in large white cross piglets has been created. 4-week-old piglets undergo surgical fixation of the knee by retrograde passage of a 3.5mm diameter steinmann pin. After free ambulation, progressive hip dysplasia is produced. We have monitored the development of hip dysplasia at 4 and 6 weeks post fixation by plain radiographs, MRI and Hip Arthroscopy using a 2.7mm diameter arthro-scope. Results: We have successfully produced hip dysplasia in an animal model of comparable size and anatomy to that seen in infants. Hip arthroscopy was performed in 20 animals. Documentation of a lax capsule, elongated ligamentum teres and pulvinar has been made. In addition arthroscopic debridement of the joint has been performed. We believe that arthroscopic debridement of the impediments to reduction in DDH is possible using the techniques learned from this model

Introduction: The Ganz periacetabular osteotomy aims to improve femoral head coverage in dysplastic hips. It is joint preserving procedure and therefore is ideally preformed before significant articular cartilage degeneration. One proposed advantage of this procedure is that it partially preserves the posterior column and does not disrupt the vascular supply of the main fragment. This study aims to 1) assess the role of MR imaging in the perioperative evaluation of articular cartilage and labrial tissues prior to Ganz osteotomies and 2) to document any alteration in the vascularity of the acetabular fragment post operatively. Patient and Methods: Twenty patients (all female, average age 18.2 years) under consideration for peracetabular osteotomy for hip dysplasia and MR Studies of the pelvis as part of the perioperative assessment. Sixteen patients had follow-up imaging at 4, 12 and 26 weeks post surgery, at which time evidence of healing, oedema, vascularity and femoral head coverage were assessed. Discussion: MR imaging has proven to be a reliable method of assessing articular cartilage health before considering pelvic osteotomy. Hopefully this will allow more appropriate selection of patients likely to benefit from this procedure. In addition MRI scanning allows clearer assessment of other articular elements, such as labium and ligamentum teres, that are difficult to visualize with plain radiographs and CT scans. A further benefit of MR scanning is that, as this study has shown the vast majority of patients who are potential candidates are female of childbearing age and it voids the use of ionizing radiation in this sensitive group of patients. This study has shown that despite some early alterations in osteotomy fragment vascularity the ultimate outcome is that vascularity is substantively unharmed by periacetabular osteotomy. Conclusion: MR imaging is extremely useful in the perioperative workup and postoperative follow-up in patients undergoing Ganz periacetabular osteotomies

Introduction: The open treatment of hip impingement is now a well-recognised technique with numerous publications about pathogenesis and surgical technique. There are very few publications of very small series discussing surgical results. We present the results of 148 hips at a mean follow-up of 20 months (range 4 – 55). Methods: This is a two surgeon series of sequential patients including the early learning curve. Patients were treated for impingement through a Ganz trochanteric osteotomy and open surgical hip dislocation. Patient data, operative findings and methods, complication and clinical follow up were recorded as a prospective audit and include Oxford and McCarthy Non Arthritic Hip scores. Results: The patient demographics are as follows:. 141 patients, 148 hips. Average age 35, range 10–65 years. Ratio Male to Female 73:75. All patients underwent femoral osteochondroplasty. 60% of cases had the labrum detached, acetabular rim recession and labral repair with bone anchors. 3 patients had the labrum reconstructed with the ligamentum teres autograft. We have had 9 failures (6%) as defined by revision to arthroplasty. 2 hips underwent successful revision open surgery for inadequately treated posterior impingement. 3 patients required arthroscopy after open surgery (2 of whom are now pain free). 7 further patients have persistent groin pain but not required further intervention. We have had the following complications: 4 trochanteric non unions requiring revision fixation, 2 deep vein thrombosis, 2 haematomas, 1 superficial infection, no deep Infections. Life table survival curve with revision to arthroplasty defined as failure. Discussion: The early to midterm results of this innovative procedure are encouraging even when including the decision making and surgical technique learning curves. We will present the hip scores and discuss the failures in detail to warn others embarking on this surgery which cases are more likely to lead to unsatisfactory outcomes

Treatment for developmental dysplasia and dislocation of the hip (DDH) presenting after one year of age is controversial. There are advocates of both open and non-operative reduction. Surgeons advocating open reduction believe in excising the obstructing soft tissues for all such cases. Others reducing non-operatively suggest that pressure from a reduced femoral head provides gradual concentric reduction with remodelling of the restraints. MR images of hips in a group of patients treated non-operatively were examined to determine the long-term development of the soft tissue around the hip. We have been treating late presented DDH by graduated traction and gentle manipulation under general anaesthetic since 1975. 10 (12 hips) of these patients were consented to have an MRI Scan of their hips. Mean age of presentation was 17 months (13–36 months). Mean follow up was 16 years (7–26 years). Mean duration of traction was 31 days (16–45 days). None of the hips had an open reduction. Subsequently 3 hips had a femoral osteotomy at a mean age of 5. 9 years (4. 1–7. 8) and 3 hips underwent a Salter-type osteotomy at a mean age of 4. 3 years (3. 7–5. 4). According to the grading of Barrett et al, 9 hips were graded clinically excellent, 2 were good and 1 hip was fair. The latest radiological result was graded according to Severin. There were 9 grade 1 hips, 2 grade II hips and 1 grade III. All the patients had coronal, sagittal and transverse scans of both their hips. All the MRI Scans showed a good coverage of the femoral head. Anterior and posterior acetabular cover was adequate in all the hips. Osseo-cartilaginous extension beyond the acetabular margin was constantly found in all the hips. Even in the hip with a Severin score of III, the cartilaginous acetabular extension produced a concentric hip joint. The anterior and the posterior labrum were found to be well developed in all the hips. None of the hips showed any evidence of inverted limbus. 3 hips showed mild evidence of avascular necrosis but there was no evidence of collapse or flattening. Thinning of the articular cartilage was seen in 3 hips but no mechanical changes observed. Capsule and ligamentum teres were found to be well developed and non-obstructive. Long-term results of non-operative treatment of late presented DDH have been found to be satisfactory. The MRI scans have shown an excellent soft tissue remodelling around the hip. Soft tissue restraints preventing initial reduction in late-presented DDH are therefore not an absolute indication for open exploration. MRI scans were found to be an excellent tool to study the effect of soft tissue remodeling in such cases

Aims

Research on hip biomechanics has analyzed femoroacetabular contact pressures and forces in distinct hip conditions, with different procedures, and used diverse loading and testing conditions. The aim of this scoping review was to identify and summarize the available evidence in the literature for hip contact pressures and force in cadaver and in vivo studies, and how joint loading, labral status, and femoral and acetabular morphology can affect these biomechanical parameters.

Aims

In the native hip, the hip capsular ligaments tighten at the limits of range of hip motion and may provide a passive stabilizing force to protect the hip against edge loading. In this study we quantified the stabilizing force vectors generated by capsular ligaments at extreme range of motion (ROM), and examined their ability to prevent edge loading.