Paul Jenkins

Clostridium difficile in patients undergoing primary hip and knee replacement

Antibiotic prophylaxis is routinely administered during joint replacement surgery and may predispose patients to Clostridium difficile-associated disease (CDAD). The primary aim of this study was to determine the incidence of this following joint replacement, using a cefuroxime-based regimen. Patients developing CDAD were compared with a control group of patients without CDAD. The incidence of the former was 1.7 per 1000 primary joint replacements. Those patients prescribed additional antibiotics had a higher incidence of CDAD (p = 0.047), but there was no difference between the two groups in relation to the use of gastroprotective agents (p = 0.703). A trial of a new prophylaxis regimen would require 43 198 patients in each arm to show a reduction of one case per 1000 procedures. Cefuroxime-based antibiotic prophylaxis is safe in patients undergoing primary elective joint replacement.

Socioeconomic status affects the Oxford knee score and Short-Form 12 score following total knee replacement

We assessed the effect of social deprivation upon the Oxford knee score (OKS), the Short-Form 12 (SF-12) and patient satisfaction after total knee replacement (TKR). An analysis of 966 patients undergoing primary TKR for symptomatic osteoarthritis (OA) was performed. Social deprivation was assessed using the Scottish Index of Multiple Deprivation. Those patients that were most deprived underwent surgery at an earlier age (p = 0.018), were more likely to be female (p = 0.046), to endure more comorbidities (p = 0.04) and to suffer worse pain and function according to the OKS (p < 0.001). In addition, deprivation was also associated with poor mental health (p = 0.002), which was assessed using the mental component (MCS) of the SF-12 score. Multivariable analysis was used to identify independent predictors of outcome at one year. Pre-operative OKS, SF-12 MCS, back pain, and four or more comorbidities were independent predictors of improvement in the OKS (all p < 0.001). Pre-operative OKS and improvement in the OKS were independent predictors of dissatisfaction (p = 0.003 and p < 0.001, respectively). Although improvement in the OKS and dissatisfaction after TKR were not significantly associated with social deprivation per se, factors more prevalent within the most deprived groups significantly diminished their improvement in OKS and increased their rate of dissatisfaction following TKR.

Age-related differences in the neck strength of adolescent rugby players A CROSS-SECTIONAL COHORT STUDY OF SCOTTISH SCHOOLCHILDREN

Objectives To evaluate the neck strength of school-aged rugby players, and to define the relationship with proxy physical measures with a view to predicting neck strength. Methods Cross-sectional cohort study involving 382 rugby playing schoolchildren at three Scottish schools (all male, aged between 12 and 18 years). Outcome measures included maximal isometric neck extension, weight, height, grip strength, cervical range of movement and neck circumference. Results Mean neck extension strength increased with age (p = 0.001), although a wide inter-age range variation was evident, with the result that some of the oldest children presented with the same neck strength as the mean of the youngest group. Grip strength explained the most variation in neck strength (R2 = 0.53), while cervical range of movement and neck girth demonstrated no relationship. Multivariable analysis demonstrated the independent effects of age, weight and grip strength, and the resultant model explained 62.1% of the variance in neck strength. This model predicted actual neck strength well for the majority of players, although there was a tendency towards overestimation at the lowest range and underestimation at the highest. Conclusion A wide variation was evident in neck strength across the range of the schoolchild-playing population, with a surprisingly large number of senior players demonstrating the same mean strength as the 12-year-old mean value. This may suggest that current training regimes address limb strength but not neck strength, which may be significant for future neck injury prevention strategies. Age, weight and grip strength can predict around two thirds of the variation in neck strength, however specific assessment is required if precise data is sought.

Personality, function and satisfaction in patients undergoing total hip or knee replacement

AbstractBackgroundThe aim of this study was to investigate the relationships between personality and joint-specific function, general physical and general mental health in patients undergoing total hip (THA) and knee arthroplasty (TKA).nMethodsOne hundred and eighty-four patients undergoing THA and 205 undergoing TKA were assessed using the Eysneck Personality Questionnaire, brief version (EPQ-BV). General physical and mental health was measured using the Short-Form 12 (SF-12) questionnaire and the EuroQol (EQ-5D). Joint-specific function was measured using the Oxford hip or knee score.ResultsThe “unstable introvert” personality type was associated with poorer pre-operative function and health in patients with hip arthrosis. In patients with knee arthrosis, there was poorer general health in those with “stable extrovert” and “unstable introvert” types. Personality was not an independent predictor of outcome following TKA or THA. The main predictor was pre-operative function and health. Comorbidity was an important covariate of both pre-operative and postoperative function.ConclusionsPersonality may play a role in the interaction of these disease processes with function and health perception. It may also affect the response and interpretation of psychometric and patient-reported outcome measures. It may be important to characterise and identify these traits in potential arthroplasty patients as it may help deliver targeted education and management to improve outcomes in certain groups.

A micro-architectural evaluation of osteoporotic human femoral heads to guide implant placement in proximal femoral fractures

Background and purpose The micro-architecture of bone has been increasingly recognized as an important determinant of bone strength. Successful operative stabilization of fractures depends on bone strength. We evaluated the osseous micro-architecture and strength of the osteoporotic human femoral head. Material and methods 6 femoral heads, obtained during arthroplasty surgery for femoral neck fracture, underwent micro-computed tomography (microCT) scanning at 30 μm, and bone volume ratio (BV/TV), trabecular thickness, structural model index, connection density, and degree of anisotropy for volumes of interest throughout the head were derived. A further 15 femoral heads underwent mechanical testing of compressive failure stress of cubes of trabecular bone from different regions of the head. Results The greatest density and trabecular thickness was found in the central core that extended from the medial calcar to the physeal scar. This region also correlated with the greatest degree of anisotropy and proportion of plate-like trabeculae. In the epiphyseal region, the trabeculae were organized radially from the physeal scar. The weakest area was found at the apex and peripheral areas of the head. The strongest region was at the center of the head. Interpretation The center of the femoral head contained the strongest trabecular bone, with the thickest, most dense trabeculae. The apical region was weaker. From an anatomical and mechanical point of view, implants that achieve fixation in or below this central core may achieve the most stable fixation during fracture healing.

Predicting the cost-effectiveness of total hip and knee replacement

The aim of this study was to perform a cost-utility analysis of total hip (THR) and knee replacement (TKR). Arthritis is a disabling condition that leads to long-term deterioration in quality of life. Total joint replacement, despite being one of the greatest advances in medicine of the modern era, has recently come under scrutiny. The National Health Service (NHS) has competing demands, and resource allocation is challenging in times of economic restraint. Patients who underwent THR (n = 348) or TKR (n = 323) between January and July 2010 in one Scottish region were entered into a prospective arthroplasty database. A health-utility score was derived from the EuroQol (EQ-5D) score pre-operatively and at one year, and was combined with individual life expectancy to derive the quality-adjusted life years (QALYs) gained. Two-way analysis of variance was used to compare QALYs gained between procedures, while controlling for baseline differences. The number of QALYs gained was higher after THR than after TKR (6.5 vs 4.0 years, p < 0.001). The cost per QALY for THR was £1372 compared with £2101 for TKR. The predictors of an increase in QALYs gained were poorer health before surgery (p < 0.001) and younger age (p < 0.001). General health (EQ-5D VAS) showed greater improvement after THR than after TKR (p < 0.001). This study provides up-to-date cost-effectiveness data for total joint replacement. THR and TKR are extremely effective both clinically and in terms of cost effectiveness, with costs that compare favourably to those of other medical interventions.

The natural history of unexplained early poor function following total hip replacement

PurposeThe majority of patients experience a significant improvement in quality of life and function after total hip replacement (THR). It has recently been shown that age and good pre-operative function are the best predictors of postoperative function. When patients fail to achieve a satisfactory outcome, a cause is often identified. Where there is no identifiable cause, advice, follow-up and management is not clear. The aim of this study was to determine the long-term outcome of patients who had early poor function, but no identifiable cause.MethodsFrom a regional database, we identified 1,564 patients who underwent unilateral THR between 1998 and 2004 and who were without complication or subsequent bilateral procedure at sixxa0months. These patients were divided into two groups according to their Harris hip score (HHS) at this stage: group A consisted of 270 patients with a ‘poor’ result (HHS less than 70). Group B consisted of 1,294 patients with a ‘good’ or ‘excellent’ result (HHS 70 or above). The patients were reviewed at fivexa0years. One hundred and ten patients from group A and 980 from group B completed five-year follow-up without further identifiable complication.ResultsThose with poor or fair function at sixxa0months were at an increased risk of developing an identified complication by fivexa0years including dislocation (OR 5.7, 95xa0% CI 1.8–18.2), deep infection (OR 9.8, 95%CI 2.9–37.7) and death (OR 1.6, 95xa0% CI 1.1–2.3). There was a greater rate of revision in group A versus group B (OR 5.7, 95xa0% CI 2.9–11). The overall function measured by the Harris hip score significantly improved in group A, but never reached that of those with good or excellent function at sixxa0months (HHS 76.2 versus 90.3, Pu2009<u20090.001).ConclusionsPatients with poor function at sixxa0months, but no obvious cause, are at higher risk of developing complications by fivexa0years. This group may benefit from more regular arthroplasty review and intervention.

Resurfacing hip replacement and cemented total hip replacement have equivalent outcome at one year in a disease matched population: a case-control study of patient reported outcome measures.

Resurfacing hip replacement has demonstrated good survival and outcomes for cohorts of younger male patients, but few controlled studies exist. In this study we compared patient reported outcome measures and satisfaction scores at one year following resurfacing hip replacement in 69 male patients with two control groups of equal numbers undergoing cemented total hip replacement: aged-matched patients and disease matched patients. At one year we found no difference in improvement in patient reported outcome measures between patients undergoing resurfacing hip replacement and disease matched patients, whereas patients undergoing resurfacing hip replacement had a statistically significant improvement in Oxford Hip Score compared to the age-matched controls (p<0.047) although this was below the minimally clinically detectable difference. Resurfacing hip replacement and total hip replacement both confer increase in patient reported outcome scores and high patient satisfaction at one year. The results of this study will allow better counselling of patients and help inform treatment decisions.

A selected screening programme was less effective in the detection of methicillin-resistant Staphylococcus aureus colonisation in an orthopaedic unit.

PurposeOur unit has used a selective screening policy for methicillin-resistant Staphylococcus aureus (MRSA) colonisation using standard chromogenic growth media, based upon risk stratification. The aim of this study was to examine the effectiveness of this selective screening policy.MethodsA cohort of 429 patients was assessed for their risk status for MRSA colonisation using both rapid polymerase chain reaction (PCR) swabs and traditional culture and sensitivity analysis. The sensitivity, specificity, positive predictive values and negative predictive values of the traditional selective approach were calculated compared to universal rapid screening.ResultsOne hundred eighteen patients were considered high risk and would traditionally be further screened with standard culture of swabs. The prevalence of MRSA was 15/429 (3.5xa0%). The sensitivity of selective screening was 53xa0% identifying eight of 15 cases. The false-negative rate was therefore 47xa0% and seven would have been missed. PCR results were available within four to six hours, whereas culture results were only available at 24xa0hours for the media showing no growth and not until 72xa0hours for positive MRSA cases.ConclusionsWe now advocate universal screening prior to, or on admission, using this rapid PCR test, as we consider this identifies MRSA colonisation more effectively and facilitates “ring-fencing” of orthopaedic beds.

Predicting the cost-effectiveness oftotal hip and knee replacement

The aim of this study was to perform a cost-utility analysis of total hip (THR) and knee replacement (TKR). Arthritis is a disabling condition that leads to long-term deterioration in quality of life. Total joint replacement, despite being one of the greatest advances in medicine of the modern era, has recently come under scrutiny. The National Health Service (NHS) has competing demands, and resource allocation is challenging in times of economic restraint. Patients who underwent THR (n = 348) or TKR (n = 323) between January and July 2010 in one Scottish region were entered into a prospective arthroplasty database. A health-utility score was derived from the EuroQol (EQ-5D) score pre-operatively and at one year, and was combined with individual life expectancy to derive the quality-adjusted life years (QALYs) gained. Two-way analysis of variance was used to compare QALYs gained between procedures, while controlling for baseline differences. The number of QALYs gained was higher after THR than after TKR (6.5 vs 4.0 years, p < 0.001). The cost per QALY for THR was £1372 compared with £2101 for TKR. The predictors of an increase in QALYs gained were poorer health before surgery (p < 0.001) and younger age (p < 0.001). General health (EQ-5D VAS) showed greater improvement after THR than after TKR (p < 0.001). This study provides up-to-date cost-effectiveness data for total joint replacement. THR and TKR are extremely effective both clinically and in terms of cost effectiveness, with costs that compare favourably to those of other medical interventions.