Aims

Hip arthroplasty does not always restore normal anatomy. This is due to inaccurate surgery or lack of stem sizes. We evaluated the aptitude of four total hip arthroplasty systems to restore an anatomical and medialized hip rotation centre.

Aims

Spinopelvic mobility plays an important role in functional acetabular component position following total hip arthroplasty (THA). The primary aim of this study was to determine if spinopelvic hypermobility persists or resolves following THA. Our second aim was to identify patient demographic or radiological factors associated with hypermobility and resolution of hypermobility after THA.

Malpositioning of the trochanteric entry point during the introduction of an intramedullary nail may cause iatrogenic fracture or malreduction. Although the optimal point of insertion in the coronal plane has been well described, positioning in the sagittal plane is poorly defined. . The paired femora from 374 cadavers were placed both in the anatomical position and in internal rotation to neutralise femoral anteversion. A marker was placed at the apparent apex of the greater trochanter, and the lateral and anterior offsets from the axis of the femoral shaft were measured on anteroposterior and lateral photographs. Greater trochanteric morphology and trochanteric overhang were graded. The mean anterior offset of the apex of the trochanter relative to the axis of the femoral shaft was 5.1 mm (. sd. 4.0) and 4.6 mm (. sd. 4.2) for the anatomical and neutralised positions, respectively. The mean lateral offset of the apex was 7.1 mm (. sd. 4.6) and 6.4 mm (. sd. 4.6), respectively. Placement of the entry position at the apex of the greater trochanter in the anteroposterior view does not reliably centre an intramedullary nail in the sagittal plane. Based on our findings, the site of insertion should be about 5 mm posterior to the apex of the trochanter to allow for its anterior offset. Cite this article: Bone Joint J 2014;96-B:1274–81

Aims

This study aimed to evaluate the accuracy of implant placement with robotic-arm assisted total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH).

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To determine the likelihood of achieving a successful closed reduction (CR) of a dislocated hip in developmental dysplasia of the hip (DDH) after failed Pavlik harness treatment We report the rate of avascular necrosis (AVN) and the need for further surgical procedures.

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A comprehensive classification for coronal lower limb alignment with predictive capabilities for knee balance would be beneficial in total knee arthroplasty (TKA). This paper describes the Coronal Plane Alignment of the Knee (CPAK) classification and examines its utility in preoperative soft tissue balance prediction, comparing kinematic alignment (KA) to mechanical alignment (MA).

Aims

Modern total knee arthroplasty (TKA) prostheses are designed to restore near normal kinematics including high flexion. Kneeling is a high flexion, kinematically demanding activity after TKA. The debate about design choice has not yet been informed by six-degrees-of-freedom in vivo kinematics. This prospective randomized clinical trial compared kneeling kinematics in three TKA designs.

Aims

Robotic-assisted total knee arthroplasty (RA-TKA) is theoretically more accurate for component positioning than TKA performed with mechanical instruments (M-TKA). Furthermore, the ability to incorporate soft-tissue laxity data into the plan prior to bone resection should reduce variability between the planned polyethylene thickness and the final implanted polyethylene. The purpose of this study was to compare accuracy to plan for component positioning and precision, as demonstrated by deviation from plan for polyethylene insert thickness in measured-resection RA-TKA versus M-TKA.

We describe a technique of femoral derotation osteotomy performed according to the Ilizarov principles of percutaneous corticotomy and fixation with a frame. We performed 24 femoral osteotomies in 16 patients, four with cerebral palsy and 12 with idiopathic femoral anteversion. All had rapid union and there were few complications. The advantages of the method include early ambulation, good control of rotation and axial alignment, and minimal scarring

Aims

Alternative alignment concepts, including kinematic and restricted kinematic, have been introduced to help improve clinical outcomes following total knee arthroplasty (TKA). The purpose of this study was to evaluate the clinical results, along with patient satisfaction, following TKA using the concept of restricted kinematic alignment.

Computerised tomography is useful in the diagnosis of abnormalities of the hip in children, particularly in assessing the size and shape of the acetabulum, the position and congruity of the femoral head relative to the acetabulum, and the degree of femoral anteversion or retroversion. It is most useful when limited hip movement and previous operations preclude adequate clinical examination and assessment by routine radiographic techniques. It is not recommended for routine use in screening congenital dislocation of the hip or in diagnosis or follow-up of Perthes' disease or slipped capital femoral epiphysis

A three-dimensional computer model of a total hip replacement was used to examine the relationship between the position of the components, the range of motion and the prosthetic joint contact area. Horizontal acetabular positions with small amounts of acetabular and femoral anteversion provide the largest contact areas, but result in limited joint movement. These data will allow surgeons to select implant positions that will provide the largest possible joint contact area for a given joint range of motion although these are conflicting goals. In some component positions a truncated spherical prosthetic head resulted in smaller contact areas than a completely spherical head

A technique for performing allograft-augmented revision total knee replacement (TKR) using computer assistance is described, on the basis of the results in 14 patients. Bone deficits were made up with impaction grafting. Femoral grafting was made possible by the construction of a retaining wall or dam which allowed pressurisation and retention of the graft. Tibial grafting used a mixture of corticocancellous and morsellised allograft. The position of the implants was monitored by the computer system and adjusted while the cement was setting. The outcome was determined using a six-parameter, quantitative technique (the Perth CT protocol) which measured the alignment of the prosthesis and provided an objective score. The final outcomes were not perfect with errors being made in femoral rotation and in producing a mismatch between the femoral and tibial components. In spite of the shortcomings the alignments were comparable in accuracy with those after primary TKR. Computer assistance shows considerable promise in producing accurate alignment in revision TKR with bone deficits

The results obtained in a consecutive series of thirty-seven Pemberton operations for congenital dislocation or subluxation of the hip are reported. Over the period under review, 1967 to 1973, it was the only type of acetabuloplasty employed at Winford. Unless the mandatory concentric reduction could be obtained with ease, preliminary open reduction was favoured, especially in cases of primary care. Femoral rotation osteotomy was added for marked anteversion. The programme was designed to be complete inside fourteen weeks, and was so for eighteen hips. Secondary acetabuloplasty was performed on hips with instability or dislocation persisting despite previous treatment. The operations were performed from eighteen months to thirteen years of age. One initial failure required a repeat operation which was successful, but one severely dysplastic hip remained so. The average follow-up was six years

Femoroacetabular cam impingement is thought to be a cause of premature osteoarthritis of the hip. The presence of cam malformation was determined in 2803 standardised anteroposterior (AP) pelvic radiographs from the Copenhagen Osteoarthritis Study by measuring the alpha (α) angle and the triangular index, a new measure of asphericity of the femoral head. In addition, the α-angle and the triangular index were assessed on the AP and lateral hip radiographs of 82 men and 82 women randomly selected from patients scheduled for total hip replacement (THR). The influence of varying femoral rotation on the α angle and the triangular index was also determined in femoral specimens under experimental conditions. From the 2803 radiographs the mean AP α-angle was 55° (30° to 100°) in men and 45° (34° to 108°) in women. Approximately 6% of men and 2% of women had cam malformation. The α-angle and triangular index were highly inter-related. Of those patients scheduled for THR, 36 men (44%) and 28 women (35%) had cam malformation identifiable on the AP radiographs. The triangular index proved to be more reliable in detecting cam malformation when the hip was held in varying degrees of rotation. The combination of the α-angle and the triangular index will allow examination of historical radiographs for epidemiological purposes in following the natural history of the cam deformity

We have compared a new technique of computer-assisted knee arthroplasty with the current conventional jig-based technique in 70 patients randomly allocated to receive either of the methods. Post-operative CT was performed according to the Perth CT Knee Arthroplasty protocol and pre- and post-operative Maquet views of the limb were taken. Intra-operative and peri-operative morbidity data were collected and blood loss measured. Post-operative CT showed a significant improvement in the alignment of the components using computer-assisted surgery in regard to femoral varus/valgus (p = 0.032), femoral rotation (p = 0.001), tibial varus/valgus (p = 0.047) tibial posterior slope (p = 0.0001), tibial rotation (p = 0.011) and femorotibial mismatch (p = 0.037). Standing alignment was also improved (p = 0.004) and blood loss was less (p = 0.0001). Computer-assisted surgery took longer with a mean increase of 13 minutes (p = 0.0001)

We have observed damage to the labrum as a result of repetitive acetabular impingement in non-dysplastic hips, in which the femoral neck appears to abut against the acetabular labrum and a non-spherical femoral head to press against the labrum and adjacent cartilage. In both mechanisms anatomical variations of the proximal femur may be a factor. We have measured the orientation of the femoral neck and the offset of the head at various circumferential positions, using MRI data from volunteers with no osteoarthritic changes on standard radiographs. Compared with the control subjects, paired for gender and age, patients showed a significant reduction in mean femoral anteversion and mean head-neck offset on the anterior aspect of the neck. This was consistent with the site of symptomatic impingement in flexion and internal rotation, and with lesions of the adjacent rim. Furthermore, when stratified for gender and age, and compared with the control group, the mean femoral head-neck offset was significantly reduced in the lateral-to-anterior aspect of the neck for young men, and in the anterolateral-to-anterior aspect of the neck for older women. For patients suspected of having impingement of the rim, anatomical variations in the proximal femur should be considered as a possible cause

The results in 102 acetabuloplasties have been assessed in eighty-six patients, with a minimum follow-up of five years. Clinical and radiological assessment was carried out according to a score system very similar to that used in previous studies, and the results were expressed as excellent, good, fair and poor according to the score obtained. Any hip requiring further stabifising procedures was automatically grouped as a failure. Subtrochanteric femoral osteotomy was used when femoral anteversion was excessive. The results revealed that 73 per cent of the hips were satisfactory (excellent or good) overall, but that a steady deterioration was evident when the five-and fifteen-year groups were compared. Few of the hips were regarded as normal on radiological grounds. Homologous bone bank rib was found to be the most satisfactory graft material. Coxa magna was the most common abnormality that was consistent with a good or excellent result. Avascular necrosis of the femoral head was found in only six hips; it was more commonly present in patients subjected to previous operation. Concentric reduction of the femoral head is essential if acetabuloplasty is to maintain stability of the hip

Aims

To compare changes in gait kinematics and walking speed 24 months after conventional (C-MLS) and minimally invasive (MI-MLS) multilevel surgery for children with diplegic cerebral palsy (CP).