1. Dissection of forty-four developing human hip joints has shown that while the embryonic acetabulum is a deeply set cavity which almost totally encloses the head it gradually becomes more shallow as birth approaches. During the same period the femoral head becomes less globular and at the end of foetal life is almost hemispherical. The cover afforded to the femoral head by the acetabulum also becomes decreased. 2. After birth these trends reverse: the acetabulum becomes deeper again and the femoral head more globular. This process continues throughout childhood. 3. The findings provide a possible explanation for the increased liability to dislocation of the infantile hip

The anatomy and development of the growing acetabulum are not clearly understood. We dissected and studied histologically two acetabula from the pelvis of a three-month-old infant. Relative rates of growth at the different growth plates were assessed by comparing the height of the proliferative layer with that of the hypertrophic layer. The three bones which form the acetabulum are surrounded by growth plates on all sides except medially. These face towards the centre of the triradiate cartilage, the limbs of the triradiate cartilage and the articular surface and each may be divided into four distinct areas according to the orientation of its cell columns which reflect the direction of growth. Growth was particularly rapid at the ischial growth plates directed towards the centre and the articular cartilage, and on both sides of the anterior limb of the triradiate cartilage. These findings may explain the mechanism by which the acetabulum changes orientation and inclination with growth

Outcomes following different types of surgical intervention for femoroacetabular impingement (FAI) are well reported individually but comparative data are deficient. The purpose of this study was to conduct a systematic review (SR) and meta-analysis to analyze the outcomes following surgical management of FAI by hip arthroscopy (HA), anterior mini open approach (AMO), and surgical hip dislocation (SHD). This SR was registered with PROSPERO. An electronic database search of PubMed, Medline, and EMBASE for English and German language articles over the last 20 years was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We specifically analyzed and compared changes in patient-reported outcome measures (PROMs), α-angle, rate of complications, rate of revision, and conversion to total hip arthroplasty (THA). A total of 48 articles were included for final analysis with a total of 4,384 hips in 4,094 patients. All subgroups showed a significant correction in mean α angle postoperatively with a mean change of 28.8° (95% confidence interval (CI) 21 to 36.5; p < 0.01) after AMO, 21.1° (95% CI 15.1 to 27; p < 0.01) after SHD, and 20.5° (95% CI 16.1 to 24.8; p < 0.01) after HA. The AMO group showed a significantly higher increase in PROMs (3.7; 95% CI 3.2 to 4.2; p < 0.01) versus arthroscopy (2.5; 95% CI 2.3 to 2.8; p < 0.01) and SHD (2.4; 95% CI 1.5 to 3.3; p < 0.01). However, the rate of complications following AMO was significantly higher than HA and SHD. All three surgical approaches offered significant improvements in PROMs and radiological correction of cam deformities. All three groups showed similar rates of revision procedures but SHD had the highest rate of conversion to a THA. Revision rates were similar for all three revision procedures.

1. The problem of instability of reduction in congenital dislocation and congenital subluxation of the hip has been studied and it has been concluded that the basic cause of this instability is the abnormal direction in which the entire acetabulum faces. 2. An operation, innominate osteotomy, has been designed to correct the abnormal direction of the entire acetabulum in children over the age of eighteen months. The principle of innominate osteotomy is redirection of the acetabulum so that the reduced dislocation or subluxation, which previously was stable only in a position of abduction and flexion, is rendered stable in the functional position of weight bearing. 3. The operative technique, and the pre-operative and post-operative management are described. 4. The indications for innominate osteotomy are outlined and the advantages of the operation are enumerated. 5. The early results of innominate osteotomy are very encouraging

Aims

The aim of the study was to compare two methods of calculating pelvic incidence (PI) and pelvic tilt (PT), either by using the femoral heads or acetabular domes to determine the bicoxofemoral axis, in patients with unilateral or bilateral primary hip osteoarthritis (OA).

We investigated differences in the location and mode of labral tears between dysplastic hips and hips with femoroacetabular impingement (FAI). We also investigated the relationship between labral tear and adjacent cartilage damage. We retrospectively studied 72 symptomatic hips (in 68 patients: 19 men and 49 women) with radiological evidence of dysplasia or FAI on high-resolution CT arthrography. The incidence and location of labral tears and modes of tear associated with the base of the labrum (Mode 1) or body of the labrum (Mode 2) were compared among FAI, mildly dysplastic and severely dysplastic hips. The locations predominantly involved with labral tears were different in FAI and mild dysplastic hips (anterior and anterosuperior zones) and in severely dysplastic hips (anterosuperior and superior zones) around the acetabulum. Significant differences were observed in the prevalence of Mode 1 versus Mode 2 tears in FAI hips (72% (n = 13) vs 28% (n = 5)) and severe dysplastic hips (25% (n = 2) vs 75% (n = 6)). The frequency of cartilage damage adjacent to Mode 1 tears was significantly higher (42% (n = 14)) than that adjacent to Mode 2 tears (14% (n = 3)). Hip pathology is significantly related to the locations and modes of labral tears. Mode 1 tears may be a risk factor for the development of adjacent acetabular cartilage damage. Cite this article: Bone Joint J 2013;95-B:1320–5

The February 2013 Hip & Pelvis Roundup. 360 . looks at: amazing alumina; dual mobility; white cells and periprosthetic infection; cartilage and impingement surgery; acetabulum in combination; cementless ceramic prosthesis; metal-on-metal hips; and whether size matters in failure

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

Aims

To identify the prevalence of neuropathic pain after lower limb fracture surgery, assess associations with pain severity, quality of life and disability, and determine baseline predictors of chronic neuropathic pain at three and at six months post-injury.

1. Prosthetic acetabular cups of the Charnley and McKee-Farrar designs were cemented into cadaveric pelves using different procedures for preparing the acetabulum. 2. The torsional moments needed to loosen these cups were measured. 3. The torsional moments so measured were found to be from about four to more than twenty times higher than the frictional moments measured in independent tests on the two designs of prosthesis. 4. It is argued that late looseness of the acetabular component after total hip replacement, in the absence of infection, seems most likely to be due to thermal damage to the bone occurring at the time of polymerisation of the cement, and to subsequent bone resorption. 5. Surgical preparation of the acetabulum should include removal of all the articular cartilage and cleaning of the acetabular fossa, but the drilling of additional holes in the floor of the acetabulum seems unimportant. 6. The possibility of fatigue fracture in bone as a factor contributing to late loosening is an argument in favour of metal-on-polyethylene prostheses with their lower frictional moments, although the importance of this factor cannot be estimated

We reviewed the results of 545 consecutive total hip replacements using a cementless non-coated high-density polyethylene acetabular component combined with a cemented Muller stem at five to 10 years. In all, 421 patients (445 hips) were available for review, 118 by questionnaire and 303 by examination and radiography. Of these, 86% had a good or excellent result. We found a high rate of radiological loosening of the cup after the sixth year, and a high rate of clinical loosening after the eighth year. Loosening was commoner in women, in younger patients and where a smaller size of acetabulum had been used. Calcar resorption was significantly related to loosening of the acetabulum. Loosening appeared to be mainly due to polyethylene debris produced by micro-movement of the acetabulum against the bone, which had resulted in a giant cell foreign body reaction and subsequent bone erosion. We have abandoned the use of this prosthesis and suggest that direct contact between bone and polyethylene should be prevented by a coating of metal or some other material

Salter innominate osteotomy is an effective reconstructive procedure for the treatment of developmental dysplasia of the hip (DDH), but some children have a poor outcome at skeletal maturity. In order to investigate factors associated with an unfavourable outcome, we assessed the development of the contralateral hip. We retrospectively reviewed 46 patients who underwent a unilateral Salter osteotomy at between five and seven years of age, with a mean follow-up of 10.3 years (7 to 20). The patients were divided into three groups according to the centre–edge angle (CEA) of the contralateral hip at skeletal maturity: normal (> 25°, 22 patients), borderline (20° to 25°, 17 patients) and dysplastic (<  20°, 7 patients). The CEA of the affected hip was measured pre-operatively, at eight to nine years of age, at 11 to 12 years of age and at skeletal maturity. The CEA of the affected hip was significantly smaller in the borderline and dysplastic groups at 11 and 12 years of age (p = 0.012) and at skeletal maturity (p = 0.017) than in the normal group. Severin group III was seen in two (11.8%) and four hips (57.1%) of the borderline and dysplastic groups, respectively (p < 0.001). . Limited individual development of the acetabulum was associated with an unfavourable outcome following Salter osteotomy. Cite this article: Bone Joint J 2014;96-B:1419–23

We have reviewed the serial radiographs of 63 hips in 53 children treated by closed reduction for congenital dislocation with a view to finding a radiological measurement which can predict subsequent acetabular development. All had been followed for more than seven years, and at latest review, 34 hips were dysplastic. Failure to obtain concentric reduction or its loss by migration of the femoral head within one year of reduction were the best predictors of persisting acetabular dysplasia and were best quantitated by the h/b ratio (Smith et al. 1968). The acetabular index at reduction or its decrease in the first year were not reliable predictors. Late treatment was less likely to lead to normal acetabular development, but avascular necrosis did not appear to have a significant influence. The average age at which the acetabulum stopped developing was five years, but ranged from 17 months to eight years. The failure of a dysplastic acetabulum to improve in each annual radiograph after closed reduction should lead to consideration of operation on the acetabulum

We examined the relationship between the size of the femoral cam in femoroacetabular impingement (FAI) and acetabular pathomorphology to establish if pincer impingement exists in patients with a femoral cam. CT scans of 37 symptomatic impinging hips with a femoral cam were analysed in a three-dimensional study and were compared with 34 normal hips. The inclination and version of the acetabulum as well as the acetabular rim angle and the bony acetabular coverage were calculated. These measurements were correlated with the size and shape of the femoral cams. While the size of the femoral cam varied characteristically, the acetabular morphology of the two groups was similar in terms of version (normal mean 23° (. sd. 7°); cam mean 22° (. sd.  9°)), inclination (normal mean 57° (. sd. 5°); cam mean 56° (. sd. 5°)), acetabular coverage (normal mean 41% (. sd. 5%); cam mean 42% (. sd. 4%)) and the mean acetabular rim angle (normal mean 82° (. sd. 5°); cam mean 83° (. sd. 4°)). We found no correlation between acetabular morphology and the severity of cam lesion and no evidence of either global or focal over-coverage to support the diagnosis of ‘mixed’ FAI. The femoral cam may provoke edge loading but removal of any acetabular bearing surface when treating cam FAI might induce accelerated wear. Cite this article: Bone Joint J 2013;95-B:314–19

We analysed the incidence of avascular necrosis in 101 hips of 90 infants with congenital dislocation treated with the Pavlik harness and followed up for more than one year. Using ultrasonography in the flexed-abducted position the hips were classified as type A when the femoral head was displaced posteriorly, but within the socket and making contact with the posterior inner wall of the acetabulum; type B when it was in contact with the posterior margin of the acetabulum, with its centre at this level or anterior to it; and type C when it was displaced out of the socket, with its centre posterior to the posterior rim of the acetabulum. Eighty-seven hips were reduced by the harness (86%), and seven of these developed avascular necrosis (8%). All 69 hips with type-A dislocation were reduced, and only one (1.4%) showed slight avascular necrosis. Eighteen (78.3%) of 23 hips with type-B dislocation were reduced, and six developed avascular necrosis (33.3%). In one hip, the femoral head was severely damaged. None of the nine hips with type-C dislocation was reduced in the harness. We conclude that the Pavlik harness is indicated for type-A, but not for type-B or type-C dislocations

A series of ten infants is reported, seven of whom showed evidence of osteomyelitis of the upper end of the femur; the remaining three did not, but presented with an acute subluxation of the hip in a febrile illness. Four sequelae among the seven more severe cases were: 1) destruction of the capital epiphysis with dislocation at the hip; 2) destruction of the capital epiphysis, the femoral neck remaining in the acetabulum; 3) destruction of the epiphysial plate with the femoral head, remaining in the acetabulum, connected to the femoral neck by a fibrous union; 4) recovery with coxa magna but no other deformity. The streptococcus plays a greater part in this osteomyelitis of infancy than in osteomyelitis of older children, but various other organisms were identified. The organism should be sought by blood culture as well as from the local lesion. Aspiration of the hip, treatment of the hip in abduction and the use of the appropriate antibiotic are recommended. If there is marked swelling and induration, freer release of the pus is strongly advised. Controlled abduction osteotomy plays a useful part in stabilising the femoral neck in the acetabulum or in stabilising the femoral neck beneath the capital epiphysis, but may usefully be preceded by an arthrograph because late ossification of a detached head sometimes occurs

Aims

Uncemented metal acetabular components show good osseointegration, but material stiffness causes stress shielding and retroacetabular bone loss. Cemented monoblock polyethylene components load more physiologically; however, the cement bone interface can suffer fibrous encapsulation and loosening. It was hypothesized that an uncemented titanium-sintered monoblock polyethylene component may offer the optimum combination of osseointegration and anatomical loading.

Aims

The objective of this study was to evaluate the clinical and radiological outcomes of patients younger than six months of age with developmental dysplasia of the hip (DDH) managed by either a Pavlik harness or Tübingen hip flexion splint.