We sought to determine the relationship between patient preoperative psychological factors and postoperative THA outcomes.

We performed an electronic search up to December 2021 using the following terms: “(mental OR psychological OR psychiatric) AND (function OR trait OR state OR predictor OR health) AND (outcome OR success OR recovery OR response) AND total joint arthroplasty)”. Peer-reviewed, English language studies regarding THA outcomes were analyzed for preoperative patient mental health metrics and objective postoperative results regarding pain, functionality and surgical complications. We extracted study data, assessed the risk of bias of included studies, grouped them by outcome measure and performed a GRADE assessment.

Seventeen of 702 studies fulfilled inclusion criteria and were included in the review. Overall, compared to cohorts with a normal psychological status, patients with higher objective measures of preoperative depression and anxiety reported increased postoperative pain, decreased functionality and greater complications following THA. Additionally, participants with lower self-efficacy or somatization were found to have worse functional outcomes. Following surgery, both early and late pain scores remained higher in patients with preoperative depression and anxiety.

Preoperative depression and anxiety may negatively impact patient reported postoperative pain, physical function and complications following THA. A meta-analysis was not performed because of the heterogeneity of studies, specifically the use of differing pain scales and measures of physical and psychological function as well as varied follow-up times. Future research could test interventions to treat pre-operative depression or anxiety and explore longitudinal outcomes in THA patients. Surgeons should consider the preoperative psychological status when counseling patients regarding expected surgical outcomes and attempt to treat a patient's depression or anxiety prior to undergoing total hip arthroplasty.

This study aimed to assess the effect of flexion and external rotation on measurement of femoral offset (FO), greater trochanter to femoral head centre (GT-FHC) distance, and neck shaft angle (NSA). Three-dimensional femoral shapes (n=100) were generated by statistical shape modelling from 47 CT-segmented right femora. Combined rotations in the range of 0–50° external and 0–50° flexion (in 10° increments) were applied to each femur after they were neutralised (defined as neck and proximal shaft axis parallel with detector plane). Each shape was projected to create 2D images representing radiographs of the proximal femora.

As already known, external rotation resulted in a significant error in measuring FO but flexion alone had no impact. Individually, neither flexion nor external rotation had any impact on GT-FHC but, for example, 30° of flexion combined with 50°of external rotation resulted in an 18.6mm change in height. NSA averaged 125° in neutral with external rotation resulting in a moderate increase and flexion on its own a moderate decrease. However, 50° degrees of both produced an almost 30 degree increase in NSA.

In conclusion, although the relationship between external rotation and FO is appreciated, the impact of flexion with external rotation is not. This combination results in apparent reduced FO, a high femoral head centre and an increased NSA. Femoral components with NSAs of 130° or 135° may historically have been based on X-ray misinterpretation. This work demonstrates that 2D to 3D reconstruction of the proximal femur in pre-op planning is a challenge.

Unknown femur orientation during X-ray imaging may cause inaccurate radiographic measurements. The aim of this study was to assess the effect of 3D femur orientation during radiographic imaging on the measurement of greater trochanter to femoral head centre (GT-FHC) distance.

Three-dimensional femoral shapes (n=100) of unknown gender were generated using a statistical shape model based on a training data of 47 CT segmented femora. Rotations in the range of 0° internal to 50° external and 50° of flexion to 0° of extension (at 10 degree increments) were applied to each femur. A ray tracing algorithm was then used to create 2D images representing radiographs of the femora in known 3D orientations. The GT-FHC distance was then measured automatically by identifying the femoral head, shaft axis and tip of greater trochanter.

Uniaxial rotations had little impact on the measurement with mean absolute error of 0.6 mm and 3.1 mm for 50° for pure external rotation and 50° pure flexion, respectively. Combined flexion and external rotation yielded more significant errors with 10° around each axis introducing a mean error of 3.6 mm and 20° showing an average error of 8.8 mm (Figure 1.). In the cohort we studied, when the femur was in neutral orientation, the tip of greater trochanter was never below the femoral head centre.

Greater trochanter to femoral head centre measurement was insensitive to rotations around a single axis (i.e. flexion or external rotation). Modest combined rotations caused the tip of greater trochanter to appear more distal in 2D and led to deviation from the true value. This study suggests that a radiograph with the greater trochanter appearing below femoral head centre may have been acquired with 3D rotation of the femur.

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Introduction

The results of the original mobile bearing Oxford unicompartmental knee replacement (UKR) in the lateral compartment have been disappointing because of high dislocation rates (11%). This original implant used a flat bearing articulation on the tibial tray. To address the issue of dislocation a new implant (domed tibia with biconcave bearing to increase entrapment) was introduced with a modified surgical technique. The aim of this study was to compare the risk of dislocation between a domed and flat lateral UKR.

A computer-based model of the knee was used to study forces in the cruciate ligaments induced by co-contraction of the extensor and flexor muscles, in the absence of external loads. Ligament forces are required whenever the components of the muscle forces parallel to the tibial plateau do not balance. When the extending effect of quadriceps exactly balances the flexing effect of hamstrings, the horizontal components of the two muscle forces also balance only at the critical flexion angle of 22 degrees. The calculations show that co-contraction of the quadriceps and hamstring muscles loads the anterior cruciate ligament from full extension to 22 degrees of flexion and loads the posterior cruciate at higher flexion angles. In these two regions of flexion, the forward pull of the patellar tendon on the tibia is, respectively, greater than or less than the backward pull of hamstrings. Simultaneous quadriceps and gastrocnemius contraction loads the anterior cruciate over the entire flexion range. Simultaneous contraction of all three muscle groups can unload the cruciate ligaments entirely at flexion angles above 22 degrees. These results may help the design of rational regimes of rehabilitation after ligament injury or repair.

We recovered 23 meniscal bearings from 18 failed bicompartmental Oxford knee prostheses. They had been implanted for one to nine years. The minimum thickness of the retrieved bearings was measured and compared with the thickness of 25 unused bearings. The mean penetration rate, calculated by two methods, was either 0.043 or 0.026 mm per annum. This compares with 0.19 mm per annum reported for the Charnley hip. The use of a fully congruous meniscal bearing prosthesis can reduce wear in knee arthroplasty to a very low rate.

We measured the sagittal laxity in 70 knee replacements at least six months after surgery, using a KT 1000 arthrometer. With an unconstrained prosthesis (the Oxford meniscal knee) anteroposterior stability was normal in joints known to have intact cruciate ligaments. There was increased laxity in those which lacked an anterior cruciate ligament. In knees with an intact anterior cruciate ligament, sagittal laxity did not increase with time.

The Oxford Knee, a resurfacing prosthesis with a meniscal bearing, can be used for either bicompartmental or unicompartmental arthritis. The first 103 unicompartmental cases are presented at a mean time since operation of 36 months (range 21 to 56 months). In those cases with surviving arthroplasties, pain was relieved in 96%. The full range of pre-operative flexion was maintained and flexion deformity was improved from a mean of 6.7 to 5.4 degrees. Stability and alignment were restored to normal in nearly all the knees. Absence of the anterior cruciate ligament was associated with a significantly greater incidence of failure. Six failures occurred in 37 knees lacking a normal anterior cruciate ligament (16.2%); three occurred in 63 knees with a normal anterior cruciate ligament (4.8%) (p less than 0.02). Criteria for the future selection of patients have been deduced from our experience. The operation is recommended for knees with severe unicompartmental osteoarthritis in which all the ligaments are still intact.

We have studied the kinematics of the knee in the sagittal plane, using a four-bar linkage as model, and assuming that a "neutral fibre" in each ligament remains isometric throughout flexion. We devised a computer program to calculate the distance separating any pair of points, one on each bone, for various cruciate attachments at various angles of flexion. The parameters for the linkage in four cadaveric knees were obtained by marking the centre of attachment of the cruciate ligaments with tacks and taking lateral radiographs. The movements of the bones were then calculated, in the computer model, for various attachments of "replacement" ligament fibres, the distance between the attachment sites being plotted against the angle of flexion. It was then possible to define zones around the isometric attachment points within which changes in length would be predictable. Our results show that the position of the femoral sites of attachment of both anterior and posterior cruciate replacement was more critical than that of the tibial attachments.

After a unicompartmental Oxford knee replacement, a clear lateral radiographic view of the components may be obtained without the shadow of prosthetic components in the other compartment. Radiographs of 20 knees were studied; with the patient supine and the muscles relaxed, views with the knee at full extension and 90 degrees of flexion were obtained and the movement of the meniscal bearings over this range of flexion was measured. The bearings were found to move backwards on the tibia through an average distance of 4.4 mm (range 0.0 to 13.5 mm) in the medial compartment and 6.0 mm (range 1.6 to 13.0 mm) in the lateral compartment. These movements were in the same direction as that observed in cadaver specimens but smaller in magnitude. At 90 degrees of flexion, radiographs were obtained with the tibia twisted manually to the limits of medial and lateral rotation. The average movement of the bearings between these extremes was found to be 6.6 mm in the medial compartment and 5.1 mm in the lateral; their movements on the tibia were in opposite directions in the two compartments. Bearing movement was still present in knees examined five years after operation.

Arthrogryposis multiplex congenita is believed to be a specific clinical entity which is aetiologically unrelated to the "arthrogryposis-like" deformities of known neurological diseases such as myelomeningocele and myelodysplasia. The observation that the condition appeared to be three times as common in Melbourne, Australia, as in four centres in the United Kingdom (Wynne-Davies and Lloyd-Roberts 1976), prompted this survey of 132 patients: 73 from the United Kingdom, 34 from Australia and 25 from Wilmington, Delaware, USA. The survey aimed to established the same criteria for diagnosis in the three countries and to search for prenatal and genetic aetiological factors. It was shown that all centers treated more newborn children with this disorder during the 1960s than either before or after that period. All cases were sporadic and there was no family association with talipes equinovarus, congenital dislocation of the hip or hereditary neuromuscular disease. "Environmental" findings from all three centers were similar and it was concluded that arthrogryposis multiplex cogenita is a non-genetic disease of early pregnancy, associated with a variety of unfavourable intra-uterine factors. In addition, an unknown but possibly viral environmental agent may have been present to a significant extent only during recent decades and is now declining.

The mechanisms controlling and limiting movement and serving to transmit load between the femur and the tibia are discussed. Having accounted for the transmission of all components of force and couple across the joint and noted the load-bearing role of the menisci, some principles which might guide the design of knee prostheses are deduced. It is shown that current designs transgress some of these principles. An experimental prosthesis is then described, which incorporates analogues of the natural menisci. The possible practical application of this novel principle has been studied in cadaveric human joints and in living patients.

1. A predictable pattern of degeneration occurs on both the femoral head and the acetabulum and this pattern is age dependent.

2. The degenerative areas on the femoral head are related to habitual non-use.

3. The hip is shown to be anatomically incongruent, and the dome of the acetabulum, a predictable area of degeneration, is shown also to be an area of habitual non-use.

4. The possible relationships between age-dependent degenerative changes and senile degenerative joint disease is discussed and the importance of changing geometry stressed.