Aims. For rare cases when a tumour infiltrates into the hip joint, extra-articular resection is required to obtain a safe margin. Endoprosthetic reconstruction following tumour resection can effectively ensure local control and improve postoperative function. However, maximizing bone preservation without compromising surgical margin remains a challenge for surgeons due to the complexity of the procedure. The purpose of the current study was to report clinical outcomes of patients who underwent extra-articular resection of the hip joint using a custom-made osteotomy guide and 3D-printed endoprosthesis. Methods. We reviewed 15 patients over a five-year period (January 2017 to December 2022) who had undergone extra-articular resection of the hip joint due to malignant tumour using a custom-made osteotomy guide and 3D-printed endoprosthesis. Each of the 15 patients had a single lesion, with six originating from the acetabulum side and nine from the proximal femur. All patients had their posterior column preserved according to the surgical plan. Results. Postoperative pathological assessment revealed a negative surgical margin was achieved in all patients. At final follow-up, 13.3% (2/15) died and no recurrence occurred. The overall survival was 81.7% at five years. None of the patients showed any signs of aseptic loosening, and no wound healing issues were observed. In total, 20% (3/15) developed complications, with two cases of early hip dislocation and one case of deep infection. The cumulative incidence of mechanical and non-mechanical failure in this series was 13.7% and 9.3%, respectively, at five years. In this cohort, the mean time to full weightbearing was 5.89 (SD 0.92) weeks and the mean Musculoskeletal Tumor Society score was 24.1 (SD 4.4). Conclusion. For patients with a hip joint tumour who met the inclusion criteria and were deemed suitable for posterior column preservation, a custom-made osteotomy guide combined with 3D-printed endoprosthesis is worth performing when treating patients who require extra-articular resection of the hip joint, as it can achieve adequate margin for local control, maximize bone preservation to maintain pelvic ring integrity, reduce the risk of complications by simplifying the surgical procedure, and allow for more precise reconstruction for better function. Cite this article: Bone Jt Open 2024;5(11):1027–1036

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

Aims. The aim of this study was to evaluate the performance of first-generation annealed highly cross-linked polyethylene (HXLPE) in cementless total hip arthroplasty (THA). Methods. We retrospectively evaluated 29 patients (35 hips) who underwent THA between December 2000 and February 2002. The survival rate was estimated using the Kaplan-Meier method. Hip joint function was evaluated using the Japanese Orthopaedic Association (JOA) score. Two-dimensional polyethylene wear was estimated using Martell’s Hip Analysis Suite. We calculated the wear rates between years 1 and 5, 5 and 10, 10 and 15, and 15 and final follow-up. Results. The mean follow-up period was 19.1 years (SD 0.6; 17.3 to 20.1). The 19-year overall survival rate with the end point of all-cause revision was 97.0% (95% confidence interval (CI) 91 to 100). The mean JOA score improved from 43.2 (SD 10.6; 30 to 76) before surgery to 90.2 (SD 6.4; 76 to 98) at the final follow-up (p < 0.001). There was no osteolysis or loosening of the acetabular or femoral components. The overall steady-state wear rate was 0.013 mm/year (SD 0.012). There was no hip with a steady-state wear rate of > 0.1 mm/year. There was no significant difference in wear rates for each period. We found no significant correlation between the wear rate and age, body weight, BMI, or cup inclination. Conclusion. First-generation annealed HXLPE shows excellent wear resistance and no acceleration of wear for approximately 20 years, with low all-cause revision rates. Cite this article: Bone Joint J 2022;104-B(2):200–205

Objectives. To validate the precision of digitally reconstructed radiograph (DRR) radiostereometric analysis (RSA) and the model-based method (MBM) RSA with respect to benchmark marker-based (MM) RSA for evaluation of kinematics in the native hip joint. Methods. Seven human cadaveric hemipelves were CT scanned and bone models were segmented. Tantalum beads were placed in the pelvis and proximal femoral bone. RSA recordings of the hips were performed during flexion, adduction and internal rotation. Stereoradiographic recordings were all analyzed with DRR, MBM and MM. Migration results for the MBM and DRR with respect to MM were compared. Precision was assessed as systematic bias (mean difference) and random variation (Pitman’s test for equal variance). Results. A total of 288 dynamic RSA images were analyzed. Systematic bias for DRR and MBM with respect to MM in translations (p < 0.018 mm) and rotations (p < 0.009°) were approximately 0. Pitman’s test showed lower random variation in all degrees of freedom for DRR compared with MBM (p < 0.001). Conclusion. Systematic error was approximately 0 for both DRR or MBM. However, precision of DRR was statistically significantly better than MBM. Since DRR does not require marker insertion it can be used for investigation of preoperative hip kinematics in comparison with the postoperative results after joint preserving hip surgery. . Cite this article: L. Hansen, S. De Raedt, P. B. Jørgensen, B. Mygind-Klavsen, B. Kaptein, M. Stilling. Marker free model-based radiostereometric analysis for evaluation of hip joint kinematics: A validation study. Bone Joint Res 2018;7:379–387. DOI: 10.1302/2046-3758.76.BJR-2017-0268.R1

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.

Objectives. The high revision rates of the DePuy Articular Surface Replacement (ASR) and the DePuy ASR XL (the total hip arthroplasty (THA) version) have led to questions over the viability of metal-on-metal (MoM) hip joints. Some designs of MoM hip joint do, however, have reasonable mid-term performance when implanted in appropriate patients. Investigations into the reasons for implant failure are important to offer help with the choice of implants and direction for future implant designs. One way to assess the performance of explanted hip prostheses is to measure the wear (in terms of material loss) on the joint surfaces. Methods. In this study, a coordinate measuring machine (CMM) was used to measure the wear on five failed cementless Biomet Magnum/ReCap/ Taperloc large head MoM THAs, along with one Biomet ReCap resurfacing joint. Surface roughness measurements were also taken. The reason for revision of these implants was pain and/or adverse reaction to metal debris (ARMD) and/or elevated blood metal ion levels. Results. The mean wear rate of the articulating surfaces of the heads and acetabular components of all six joints tested was found to be 6.1 mm. 3. /year (4.1 to 7.6). The mean wear rate of the femoral head tapers of the five THAs was 0.054 mm. 3. /year (0.021 to 0.128) with a mean maximum wear depth of 5.7 µm (4.3 to 8.5). Conclusion. Although the taper wear was relatively low, the wear from the articulating surfaces was sufficient to provide concern and was potentially large enough to have been the cause of failure of these joints. The authors believe that patients implanted with the ReCap system, whether the resurfacing prosthesis or the THA, should be closely monitored. Cite this article: S. C. Scholes, B. J. Hunt, V. M. Richardson, D. J. Langton, E. Smith, T. J. Joyce. Explant analysis of the Biomet Magnum/ReCap metal-on-metal hip joint. Bone Joint Res 2017;6:113–122. DOI: 10.1302/2046-3758.62.BJR-2016-0130.R2

To confirm whether developmental dysplasia of the hip has a risk of hip impingement, we analysed maximum ranges of movement to the point of bony impingement, and impingement location using three-dimensional (3D) surface models of the pelvis and femur in combination with 3D morphology of the hip joint using computer-assisted methods. Results of computed tomography were examined for 52 hip joints with DDH and 73 normal healthy hip joints. DDH shows larger maximum extension (p = 0.001) and internal rotation at 90° flexion (p < 0.001). Similar maximum flexion (p = 0.835) and external rotation (p = 0.713) were observed between groups, while high rates of extra-articular impingement were noticed in these directions in DDH (p < 0.001). Smaller cranial acetabular anteversion (p = 0.048), centre-edge angles (p < 0.001), a circumferentially shallower acetabulum, larger femoral neck anteversion (p < 0.001), and larger alpha angle were identified in DDH. Risk of anterior impingement in retroverted DDH hips is similar to that in retroverted normal hips in excessive adduction but minimal in less adduction. These findings might be borne in mind when considering the possibility of extra-articular posterior impingement in DDH being a source of pain, particularly for patients with a highly anteverted femoral neck. Cite this article: Bone Joint J 2014;96-B:580–9

1. One hundred patients with dislocation of the hip joint have been reviewed, many having been re-examined at intervals ranging from two to five years after injury. 2. There were forty-six simple dislocations, forty-three dislocations with fracture of the acetabular rim, seven dislocations with fracture of the acetabular floor, and five dislocations with fracture of the femoral head. 3. Complete recovery, as judged by clinical and radiographic examination, was observed in 76 per cent. of simple dislocations, 63 per cent. of dislocations with fracture of the acetabular rim, and 40 per cent. of dislocations with fracture of the femoral head; in no case of dislocation with fracture of the acetabular floor was recovery complete. 4. Only in one case did myositis ossificans develop, and that was the only case treated by "massage and movements" throughout the first ten weeks after injury. 5. Avascular necrosis of the femoral head was recognised in a smaller proportion of patients than had been expected, but since the follow-up review extended only to four years after injury the results, in this respect, are unreliable. The incidence of this complication after injury to the hip joint cannot be assessed unless the follow-up period is at least five to ten years. 6. Early traumatic arthritis developed in 26 per cent. of patients—in 15 per cent. of simple dislocations, 25 per cent. of dislocations with fracture of the acetabular margin, 60 per cent. of dislocations with fracture of the femoral head, and 100 per cent. of dislocations with fracture of the acetabular floor. 7. When central or posterior dislocations are accompanied by fracture of the acetabular floor, early arthrodesis is the treatment of choice. 8. Displacement of marginal acetabular fragments is usually corrected by manipulative reduction or by traction. 9. Sciatic paralysis in dislocation of the hip joint is nearly always due to damage of the nerve by a displaced acetabular fragment. In such cases, if the fragment is not replaced accurately by manipulation or traction, operative reduction is urgently indicated

1. This is a simple clinical study of the end-results of arthrodesis of the hip joint in patients followed up and re-examined five to twenty-five years after operation. 2. The study was stimulated by our astonishment at recent reports which suggested that arthrodesis of the hip caused serious operative mortality, a high rate of wound infection, and failure of sound fusion in one of every two cases; and that even when sound fusion was gained there was always pain in the back and usually stiffness of the knee. To say that we were astonished puts it mildly. 3. This review includes 120 patients aged from ten to seventy years, treated for osteoarthritis of the hip joint by intra-articular arthrodesis with the internal fixation of a nail, usually with an iliac graft, and with immobilisation in plaster for not less than four months. 4. Of these 120 patients there was sound fusion of the joint, proved radiographically, in 94 per cent; a mortality of nil; and recovery of free movement of the knee joint to the right angle or far beyond in 91·5 per cent. Almost half of the patients regained normal movement, the heel touching the buttock. Only in eight patients was there less than right-angled flexion. 5. There was no pain in the back—none whatever—in 64 per cent of the patients. In 36 per cent there was some pain or discomfort. One alone said that the low back pain was worse than before the operation. Many others said that pain in the back had been relieved by the operation. 6. It is emphasised that these results were gained only from sound fixation of the joint in the mid-position with neutral rotation, no more abduction than is needed to correct true shortening, and no more flexion of the joint than that with which the patient lies on the table. The limb was immobilised in plaster for at least four months after operation. The stiff knee was mobilised by the patient's own exercise without passive stretching, force or manipulation. 7. Two other groups of patients are considered. There are fourteen treated by fixation of the joint with nail alone, an operation that was never intended to arthrodese the joint and which has long since been abandoned. The other small group is that of patients with old unreduced traumatic dislocation of the hip, a procedure in which the risks of operation are so great and the number of successful results so small as to dissuade us from attempting operative reduction. 8. After successful arthrodesis of the hip joint patients can return to every household activity and every recreation including ski-ing, mountaineering, rock climbing, or whatever else they want

Aims. Our aim in this study was to describe the long-term survival of the native hip joint after open reduction and internal fixation of a displaced fracture of the acetabulum. We also present long-term clinical outcomes and risk factors associated with a poor outcome. Patients and Methods. A total of 285 patients underwent surgery for a displaced acetabular fracture between 1993 and 2005. For the survival analysis 253 were included, there were 197 men and 56 women with a mean age of 42 years (12 to 78). The mean follow-up of 11 years (1 to 20) was identified from our pelvic fracture registry. There were 99 elementary and 154 associated fracture types. For the long-term clinical follow-up, 192 patients with complete data were included. Their mean age was 40 years (13 to 78) with a mean follow-up of 12 years (5 to 20). Injury to the femoral head and acetabular impaction were assessed with CT scans and patients with an ipsilateral fracture of the femoral head were excluded. Results. A total of 36 patients underwent total hip arthroplasty (THA). The overall ten-year survival of the hip joint was 86% (95% confidence interval (CI) 81% to 90%) and the 20-year survival was 82% (95% CI 76% to 87%). Injury to the femoral head and acetabular impaction were the strongest predictors of failure, with the long-term survival rate falling towards 50% in these patients. The survival fell to 0% at three years when both these risk factors were present in patients aged > 60 years. Conclusion. The long-term survival of the native hip joint after acetabular fractures was good, but the presence of injury to the femoral head and acetabular impaction proved to be strong predictors of failure, especially in patients aged > 60 years. These patients may be better treated with a combination of open reduction and internal fixation and primary arthroplasty. Cite this article: Bone Joint J 2017;99-B:834–40

The pressure distribution between the cartilaginous surfaces in the human hip joint was measured using pressure-sensitive film. Five cadaveric hip joints (aged between 58 and 87 years) were measured at three positions and loads, representing three instants in the stance phase of the walking cycle. The pressure distribution was not uniform, indicating that the cartilage did not, to any great extent, distribute the applied load. The maximum pressures recorded were about 10 MN/m2. The anterosuperior surface of the cartilage was identified as an area of high pressure

In this study we used subject-specific finite element analysis to investigate the mechanical effects of rotational acetabular osteotomy (RAO) on the hip joint and analysed the correlation between various radiological measurements and mechanical stress in the hip joint. We evaluated 13 hips in 12 patients (two men and ten women, mean age at surgery 32.0 years; 19 to 46) with developmental dysplasia of the hip (DDH) who were treated by RAO. Subject-specific finite element models were constructed from CT data. The centre–edge (CE) angle, acetabular head index (AHI), acetabular angle and acetabular roof angle (ARA) were measured on anteroposterior pelvic radiographs taken before and after RAO. The relationship between equivalent stress in the hip joint and radiological measurements was analysed. The equivalent stress in the acetabulum decreased from 4.1 MPa (2.7 to 6.5) pre-operatively to 2.8 MPa (1.8 to 3.6) post-operatively (p < 0.01). There was a moderate correlation between equivalent stress in the acetabulum and the radiological measurements: CE angle (R = –0.645, p < 0.01); AHI (R = –0.603, p < 0.01); acetabular angle (R = 0.484, p = 0.02); and ARA (R = 0.572, p < 0.01). The equivalent stress in the acetabulum of patients with DDH decreased after RAO. Correction of the CE angle, AHI and ARA was considered to be important in reducing the mechanical stress in the hip joint. Cite this article: Bone Joint J 2015;97-B:492–7

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.

1. In this series of 150 cases of arthritis of the hip joint treated by vitallium mould arthroplasty (182 arthroplasties), 80 per cent. of late results are satisfactory to both patient and surgeon. 2. Striking features are the relative painlessness, smooth hip joint movement, progressive improvement in function, and reformation of the joint lines as seen radiographically in the post-operative period. 3. Function after arthroplasty for traumatic and degenerative arthritis approaches the normal hip joint much more closely than in cases of infective and rheumatoid arthritis. 4. There is a complete absence of low back symptoms or postural difficulties, and there is no difficulty in preventing stiffness of the knee joint. 5. Different technical procedures are indicated according to the degree of absorption of the femoral head or neck, and the stability of the mould in the acetabulum. 6. The operative mortality rate in this series was nil, and during the six-year follow-up period only one case died as the result of a complication of the arthroplasty. 7. In addition to meticulous operative technique and the use of special instruments, the importance of careful and prolonged after-treatment must be stressed. 8. It must also be emphasised that secondary operative revisions are often necessary, particularly in cases of infective and rheumatoid arthritis

1. Three cases of osteochondromatosis of the hip joint are described. 2. Attention is drawn to the diagnostic importance of erosions at the junction of head and neck of the femur, and the conical shape of the femoral neck. 3. Arthrography is of particular value in diagnosis when the loose bodies are radio-translucent

1. The operation of pseudarthrosis of the hip joint is described and the results are assessed in ninety-three patients. 2. The result was good in eighty-three cases and poor in seven cases. Three patients died as a result of the operation. 3. Pseudarthrosis is the most satisfactory and the most reliable operation: 1) in ankvlosing spondylitis, and 2) in patients over sixty years of age with disabling osteoarthritis. 4. The more formidable operation of cup arthoplasty may prove to be superior in younger patients with osteoarthritis

1. Fifty cases of arthrodesis of the hip joint in tuberculous arthritis are analysed; in forty cases the late end-result has been ascertained two or more years after operation. 2. The indications for arthrodesis are discussed. The operation should not be performed when disease is active; it should not be undertaken before the age of twelve to thirteen years; it is not advisable in elderly patients; it may be contra-indicated when there are multiple foci of infection. Subject to these limitations every patient with unsound ankylosis after adequate conservative treatment should be treated by arthrodesis; painful fibrous ankylosis and late onset of deformity are definite indications. 3. Three types of operation have been used: intra-articular arthrodesis; extra-articular ilio-femoral arthrodesis; combined intra- and extra-articular arthrodesis. Extra-articular ilio-femoral arthrodesis is preferred, deformity being first corrected by traction or osteotomy. 4. Post-operation complications were few; the mortality rate was low (2 per cent.). 5. There was bone ankylosis with solid incorporation of the graft in 87·5 per cent., failure of union of the graft (to the trochanter) in 10 per cent., and destruction of the graft in 2·5 per cent. 6. Late end-results show full working capacity in 87·5 per cent. of patients, part working capacity in 2·5 per cent. and inability to work in 7·5 per cent. The writer wishes to express his thanks to Professor Harry Platt and Professor T. P.. McMurray for criticism and advice in the preparation of this paper, and to Dr F. C. S. Bradbury, Central Consultant Tuberculosis Officer of the Lancashire County Council, for permission to publish these cases

Photoelastic techniques were used to study the stresses in models which represented the central frontal plane of a normal hip joint. The pelvis and the femur were inclined and the direction of the resultant thrust on the joint was estimated. Inward tilting of the pelvis causes a force which tends to push the head of the femur out of joint. The load distribution on the joint is not significantly changed if the line of action of the load is moved relative to the joint. The directions of the lines of principal stress in both bones are shown

1. A specially designed loading apparatus and dyeing technique have been used to demonstrate the weight-bearing areas in fifty-one normal adult hip joints. 2. Under loads and positions typical of the stance phase of walking the entire articular surface of the acetabulum is involved in weight-bearing. This contact area is reproduced on the femoral head, and its position determined by the attitude of the femur to the acetabulum. 3. With loads typical of the swing phase, the dome of the acetabulum and corresponding areas on the femoral head are not involved in weight-bearing. 4. The results are compared with the conclusions of previous investigators and their possible significance with regard to joint degeneration is discussed

Objectives. The purpose of this study was to compare the thickness of the hip capsule in patients with surgical hip disease, either with cam-femoroacetabular impingement (FAI) or non-FAI hip pathology, with that of asymptomatic control hips. Methods. A total of 56 hips in 55 patients underwent a 3Tesla MRI of the hip. These included 40 patients with 41 hips with arthroscopically proven hip disease (16 with cam-FAI; nine men, seven women; mean age 39 years, 22 to 58) and 25 with non-FAI chondrolabral pathology (four men, 21 women; mean age 40 years, 18 to 63) as well as 15 asymptomatic volunteers, whose hips served as controls (ten men, five women; mean age 62 years, 33 to 77). The maximal capsule thickness was measured anteriorly and superiorly, and compared within and between the three groups with a gender subanalysis using student’s t-test. The correlation between alpha angle and capsule thickness was determined using Pearson’s correlation coefficient. Results. Superiorly, the hip capsule was significantly greater in cam- (p = 0.028) and non-FAI (p = 0.048) surgical groups compared with the asymptomatic group. Within groups, the superior capsule thickness was significantly greater than the anterior in cam- (p < 0.001) and non-FAI (p < 0.001) surgical groups, but not in the control group. There was no significant correlation between the alpha angle and capsule thickness. There were no gender differences identified in the thickness of the hip capsule. Conclusion. The thickness of the capsule does not differ between cam- and non-FAI diseased hips, and thus may not be specific for a particular aetiology of hip disease. The capsule is, however, thicker in diseased surgical hips compared with asymptomatic control hips. Cite this article: K. S. Rakhra, A. A. Bonura, R. Nairn, M. E. Schweitzer, N. M. Kolanko, P. E. Beaule. Is the hip capsule thicker in diseased hips? Bone Joint Res 2016;5:586–593. DOI: 10.1302/2046-3758.511.2000495