Aims. The aim of this study was to investigate the association between fracture displacement and survivorship of the native hip joint without conversion to a total hip arthroplasty (THA), and to determine predictors for conversion to THA in patients treated nonoperatively for acetabular fractures. Methods. A multicentre cross-sectional study was performed in 170 patients who were treated nonoperatively for an acetabular fracture in three level 1 trauma centres. Using the post-injury diagnostic CT scan, the maximum gap and step-off values in the weightbearing dome were digitally measured by two trauma surgeons. Native hip survival was reported using Kaplan-Meier curves. Predictors for conversion to THA were determined using Cox regression analysis. Results. Of 170 patients, 22 (13%) subsequently received a THA. Native hip survival in patients with a step-off ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 94% vs 70% vs 74%). Native hip survival in patients with a gap ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 100% vs 84% vs 78%). Step-off displacement > 2 mm (> 2 to 4 mm hazard ratio (HR) 4.9, > 4 mm HR 5.6) and age > 60 years (HR 2.9) were independent predictors for conversion to THA at follow-up. Conclusion. Patients with minimally displaced acetabular fractures who opt for nonoperative fracture treatment may be informed that fracture displacement (e.g. gap and step-off) up to 2 mm, as measured on CT images, results in limited risk on conversion to THA. Step-off ≥ 2 mm and age > 60 years are predictors for conversion to THA and can be helpful in the shared decision-making process. Cite this article: Bone Joint J 2023;105-B(9):1020–1029

Aims. Dislocation of the hip remains a major complication after periacetabular tumour resection and endoprosthetic reconstruction. The position of the acetabular component is an important modifiable factor for surgeons in determining the risk of postoperative dislocation. We investigated the significance of horizontal, vertical, and sagittal displacement of the hip centre of rotation (COR) on postoperative dislocation using a CT-based 3D model, as well as other potential risk factors for dislocation. Methods. A total of 122 patients who underwent reconstruction following resection of periacetabular tumour between January 2011 and January 2020 were studied. The risk factors for dislocation were investigated with univariate and multivariate logistic regression analysis on patient-specific, resection-specific, and reconstruction-specific variables. Results. The dislocation rate was 13.9% (n = 17). The hip COR was found to be significantly shifted anteriorly and inferiorly in most patients in the dislocation group compared with the non-dislocation group. Three independent risk factors were found to be related to dislocation: resection of gluteus medius (odds ratio (OR) 3.68 (95% confidence interval (CI) 1.24 to 19.70); p = 0.039), vertical shift of COR > 18 mm (OR 24.8 (95% CI 6.23 to 128.00); p = 0.001), and sagittal shift of COR > 20 mm (OR 6.22 (95% CI 1.33 to 32.2); p = 0.026). Conclusion. Among the 17 patients who dislocated, 70.3% (n = 12) were anterior dislocations. Three independent risk factors were identified, suggesting the importance of proper restoration of the COR and the role of the gluteus medius in maintaining hip joint stability. Cite this article: Bone Joint J 2022;104-B(10):1180–1188

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

Aims

To analyze whether the addition of risk-based criteria to clinical examination-based selective ultrasound screening would increase the rates of early detected cases of developmental dysplasia of the hip (DDH) and decrease the rate of late detected cases.

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

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

Aims

The aim of this study was to understand the experience of mature patients who undergo a periacetabular osteotomy (PAO), a major hip-preserving surgical procedure that treats symptomatic hip dysplasia by realigning the acetabulum. Our aim was to improve our understanding of how the operation affected the lives of patients and their families, with a long-term goal of improving their experience.

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

This is the first time that the principle of the mould—the principle of guiding the repair of nature for the purpose of recreating a destroyed or damaged structure, has been applied to surgery. The evolution of the method to its present encouraging stage is the result of the co-operative, professional family spirit of the Massachusetts General Hospital. We all share in it. We share it with the general surgeon because of his contributions to surgical technique. We share it with the "medical man" because of his pre-operative and post-operative care of the patient; because of his guidance as to when, and when not, to operate; and because of the many friendly arguments which are productive of so much good. We share it with the anaesthetist because of his clinical judgment of the patient, his selection of anaesthetic agent, and his continuous, conscientious administration of the anaesthetic throughout the operation. I am going to change from "we" to "I." I owe so much to my assistants, from the first to the last: Bill Rogers, Eddie Cave, George Van Gorder, Paul Norton, Milton Thompson, Otto Aufranc, and Carroll Larson. I want to thank them all for helping to carry the load, for remembering the things that I forgot, and for making helpful suggestions which often led to improvement in surgical technique or to the construction of a useful instrument. I want to pay tribute to the staff of the Orthopaedic Service of the Massachusetts General Hospital and to thank its members for kindly scepticism, constructive criticism, and neverfailing loyal support. The subject of this lecture, "Evolution of Mould Arthroplasty of the Hip Joint," is appropriate for a Moynihan lecture. It is not the work of one man alone. It is the work of one man, supported by a co-operative, helpful, and friendly hospital staff. This is what Lord Moynihan strove so hard to bring about at a time when surgeons viewed one another as rivals. To quote Dr William Mayo: "It is to Lord Moynihan's everlasting credit that, largely as a result of his unceasing efforts, surgeons came to consider themselves as fellow-workers in a cause."

1. The early signs of Paget's disease of the acetabulum and femur are described. 2. The pattern of arthritis is presented in 199 hips in which Paget's disease of bone occurred in either the femur, the acetabulum or both bones. Distinct patterns of disease occur with different bone involvement. 3. Selective narrowing of the medial segment of the joint is common and is particularly associated with pelvic disease. Why the narrowing occurs here preferentially is unexplained. 4. Protrusio acetabuli occurred in only 25 per cent of hips and usually when both the femur and the acetabulum were involved. This may be due to the presence simultaneously of weakened bone and coxa vara, the latter leading to an alteration in the direction of the resultant force across the hip joint. 5. Degenerative arthritis was present with Paget's disease in 14 per cent of hips but it may be a chance relationship in half of these hips

1. Congenital dislocation of the hip can be diagnosed clinically immediately after birth and the diagnosis confirmed radiologically by a special technique. 2. If the affected joint is reduced during the first two or three days after birth and held reduced for a period not exceeding three months, the joint will remain stable. 3. This treatment probably leads to normal development of the hip joint. 4. The cause of congenital dislocation of the hip may be laxity of the soft tissues of the joint and not a primary dysplasia of the acetabulum

1. The operation of "dynamic" osteotomy is designed to secure a stable and freely mobile pseudarthrosis in cases of quiescent tuberculosis of the hip joint. 2. The principles and technique of the operation are described and illustrated. 3. The results of 224 operations are presented