Metal-on-metal hip resurfacing arthroplasty provides excellent long-term survivorship and function in patients with a good-sized femoral head : results of a single, non-designer surgeon's cohort.

AIMS: To establish the survivorship, function, and metal ion levels in an unselected series of metal-on-metal hip resurfacing arthroplasties (HRAs) performed by a non-designer surgeon. METHODS: We reviewed 105 consecutive HRAs in 83 patients, performed by a single surgeon, at a mean follow-up of 14.9 years (9.3 to 19.1). The cohort included 45 male and 38 female patients, with a mean age of 49.5 years (SD 12.5). RESULTS: At the time of review 13 patients with 15 hips had died from causes unrelated to the hip operation, and 14 hips had undergone revision surgery, giving an overall survival rate of rate of 86.7% (95% confidence interval (CI) 84.2 to 89.1). The survival rate in men was 97.7% (95% CI 96.3 to 98.9) and in women was 73.4% (95% CI 70.6 to 75.1). The median head size of the failed group was 42 mm (interquartile range (IQR) 42 to 44), and in the surviving group was 50 mm (IQR 46 to 50). In all, 13 of the 14 revised hips had a femoral component measuring ≤ 46 mm. The mean blood levels of cobalt and chromium ions were 26.6 nmol/l (SD 24.5) and 30.6 nmol/l (SD 15.3), respectively. No metal ion levels exceeded the safe limit. The mean Oxford Hip Score was 41.5 (SD 8.9) and Harris Hip Score was 89.9 (14.8). In the surviving group, four patients had radiolucent lines around the stem of the femoral component, and one had lysis around the acetabular component; eight hips demonstrated heterotopic ossification. CONCLUSION: Our results confirm the existing understanding that HRA provides good long-term survival and function in patients with adequate-sized femoral heads. This is evidenced by a 97.7% survival rate among men (larger heads) in our series at a mean follow-up of 14.9 years. Failure is closely related to head sizes ≤ 46 cm. Cite this article: Bone Jt Open 2022;3(1):68-76.

The Medial Rotation Knee replacement: Clinical and radiological results of a multi-centre surveillance study at five years.

BACKGROUND: The Medial Rotation Knee (MRK) has one of the lowest revision rates of total knee replacement designs in the National Joint Registry. While survival is one metric of performance of implants, patient-reported outcomes, combined with clinical and radiological evaluation, allow more complete analysis. We report the five-year results of a prospective, multi-centre surveillance study of the MRK. METHODS: A 16-surgeon, three-centre series of 520 total knee replacements were performed in 486 patients, comprising 182 males and 304 females. The mean age was 70.3 years (46-96) and BMI 29.5 kg/m2 (18-57). Study subjects were given questionnaires pre-operatively, at six months, and annually thereafter. Clinical and radiological reviews were scheduled pre-operatively, at six months, three and five years. RESULTS: At five years, 395 of the original 486 patients (427 of 520 knees) remained under active review. Twenty-six patients (27 knees) had withdrawn, 44 patients/knees had died and one was excluded. Thirteen patients (14 knees) were lost to follow-up, but were not revised. Seven knees were revised, equating to a survival probability of 98.6% at five years. There were significant improvements in mean Oxford Knee Score (21.23-35.79), EQ-5D (0.440-0.694) and Knee Society Score (Knee 43.00-83.97; Function 49.45-71.39). Of the radiographs available for evaluation, radiolucency was identified in 25 knees (14.6%) with one case of osteolysis of the tibial component. CONCLUSION: In addition to excellent survivorship, mid-term patient-reported, clinical and radiological results at five years are satisfactory, and consistent with other medial pivot designs.

Obsessive-compulsive symptoms and attentional bias: An eye-tracking methodology.

BACKGROUND AND OBJECTIVES: Cognitive models suggest that attentional biases are integral in the maintenance of obsessive-compulsive symptoms (OCS). Such biases have been established experimentally in anxiety disorders; however, the evidence is unclear in Obsessive Compulsive disorder (OCD). In the present study, an eye-tracking methodology was employed to explore attentional biases in relation to OCS. METHODS: A convenience sample of 85 community volunteers was assessed on OCS using the Yale-Brown Obsessive Compulsive Scale-self report. Participants completed an eye-tracking paradigm where they were exposed to OCD, Aversive and Neutral visual stimuli. Indices of attentional bias were derived from the eye-tracking data. RESULTS: Simple linear regressions were performed with OCS severity as the predictor and eye-tracking measures of the different attentional biases for each of the three stimuli types were the criterion variables. Findings revealed that OCS severity moderately predicted greater frequency and duration of fixations on OCD stimuli, which reflect the maintenance attentional bias. No significant results were found in support of other biases. LIMITATIONS: Interpretations based on a non-clinical sample limit the generalisability of the conclusions, although use of such samples in OCD research has been found to be comparable to clinical populations. Future research would include both clinical and sub-clinical participants. CONCLUSIONS: Results provide some support for the theory of maintained attention in OCD attentional biases, as opposed to vigilance theory. Individuals with greater OCS do not orient to OCD stimuli any faster than individuals with lower OCS, but once a threat is identified, these individuals allocate more attention to OCS-relevant stimuli..

Intensive physiotherapy for vegetative and minimally conscious state patients: a retrospective audit and analysis of therapy intervention.

PURPOSE: To analyse physiotherapy interventions and evaluate their effectiveness in the prevention and management of contracture with patients admitted in either vegetative or minimally conscious state in a UK Inpatient Regional Acquired Brain Injury Rehabilitation Service. METHOD: Retrospective audit of dependency levels and physiotherapy interventions in ten vegetative or minimally conscious state patients admitted over a 3-year period (2006-2009). Admission and discharge patient dependency status, Wessex Head Injury Matrix data and passive range of movement measurements on admission and discharge from physiotherapy were recorded. RESULTS: All patients presented with hypertonicity including contractures and all initially received a manual stretching/passive movement programme. Casting/splinting was employed in 8 cases and 7 received botulinum toxin injections. Standing regimes were initiated for 8 patients. No patient emerged out of either vegetative or minimally conscious state. Although they remained fully dependent for care needs, carer burden was reduced and all patients were able sustain a seating regimen. No minimal clinically important difference was observed in 85 out of 120 joint ranges measured (70.8%). Positive outcomes were observed in only 14 joints (11.7%) and negative outcomes in 21 joints (17.5%). CONCLUSION: At present, there is a paucity of evidence regarding physiotherapy efficacy to inform the management of patients in vegetative or minimally conscious state. Clearer agreed definitions of clinically important difference in passive range of movement are required to allow better interpretation of outcomes. Interventions should be aimed at minimising carer burden and developing individualised disability management programmes. Further research documenting the long-term outcomes in such patients is warranted.

Evaluation of the posterior tibial slope on MR images in different population groups using the tibial proximal anatomical axis.

We measured the posterior tibial slope for the medial and lateral tibial plateau separately in MR images of 143 knees (71 women, 72 men) and compared the measurements between genders and different ethnic groups. For the whole population the mean medial slope was 5.7 degrees and the mean lateral slope 5.6 degrees. There was a significant difference between the medial and lateral posterior tibial slope in the Asian patients compared with other ethnic groups (p < 0.001). We have shown that measurement of the posterior tibial slope (PTS) could be reliably performed on MR images, revealing a gender difference. These findings might have clinical relevance when performing reconstructive surgery at the knee in determining ideal placement of the tibial component.

Design considerations and life prediction of metal-on-metal bearings: the effect of clearance.

BACKGROUND: Clinical observations suggest that metal-on-metal arthroplasties that have been implanted for more than twenty years do fail. It is proposed that there are not two, but three distinct phases of wear life for any metal-on-metal implant system: bedding-in, steady state, and end point. In this study, we asked two questions: can we explain late failure due to wear, and will there be a late failure mechanism due to a change in the frictional torque? METHODS: In order to characterize wear failure, an analysis was made of five retrieved metal-on-metal couples that were mapped with use of a roundness machine. A geometrical model was developed on the basis of these observations, and wear at the end point was calculated. The literature on first-generation metal-on-metal implants retrieved for aseptic loosening was reviewed to assess the agreement with the retrieval findings as well as the wear model. RESULTS: A wear patch of an appreciable and constant size could be measured in all five retrieved couples. The end point of revision was observed to occur when the wear progression reached a contact area corresponding to approximately 75% of the projected diameter of the ball. The wear volume was calculated from the geometry. The available literature describing the wear characteristics of retrieved bearings after successful clinical use showed good agreement with the calculated wear model. CONCLUSIONS: During the implant life of long-term successful metal-on-metal devices, a wear patch develops, as evident from retrieved failed devices. Failure often occurs through loosening, and the observed wear patch is similar in size for devices measured by us and for those described in the literature. We hypothesized that failure by loosening occurs through the accumulation of wear, which eventually leads to high friction within the bearing and increased torsional forces across the joint and its fixation.

Use of prepolymerized cement spacers to augment the femoral component in revision total knee arthroplasty: a clinical outcome report and laboratory experiment.

A technique for revision total knee arthroplasty managing posterior femoral condylar bone loss with prepolymerized polymethyl methacrylate cement spacers as augments to the femoral component is described in 10 consecutive cases. The maximum follow-up time is 63 months. This method allows for maintenance of the posterior joint line, which in turn facilitates appropriate flexion-extension gap balancing. The cement spacers are inexpensive compared with metal augments. An experimental study confirms that the cement spacers produce a chemical and physical bond with fresh cement. This eliminates the risk of particulate debris production between the cement augment and the fixation cement. Although the cement spacers have been produced to match one manufacturer's implants, they could be applied to other knee systems.