Hip aspiration culture: analysing data from a single operator series investigating periprosthetic joint infection

Introduction: We undertook this study to know the sensitivity, specificity and post-test probabilities of hip aspiration when diagnosing periprosthetic hip infections. We also examined “dry tap” (injection with saline and aspiration) results and aspiration volumes. Methods: This is a retrospective cohort study of patients aspirated for suspected periprosthetic joint infection between July 2012 and October 2016. All aspirations were carried out by one trained surgical care practitioner (SCP). All aspirations followed an aseptic technique and fluoroscopic guidance. Aspiration was compared to tissue biopsy taken at revision. Aspiration volumes were analysed for comparison. Results: Between January 2012 and September 2016, 461 hip aspirations were performed by our SCP. Of these 125 progressed to revision. We calculated sensitivity 59 % (confidence interval (CI) 35 %–82 %) and specificity 94 % (CI 89 %–98 %). Pre-test probability for our cohort was 0.14. Positive post-test probability was 0.59 and negative post-test probability 0.06. Aspiration volume for infected (n=17) and non-infected (n=108) joints was compared and showed no significant difference. Dry taps were experienced five times; in each instance the dry tap agreed with the biopsy result. Conclusions: Our data show that hip aspiration culture is a highly specific investigation for diagnosing infection but that it is not sensitive. Aspiration volume showed no significant difference between infected and non-infected groups. Each time a joint was infiltrated with saline to achieve a result, the result matched tissue sampling.

Performance and learning curve of a surgical care practitioner in completing hip aspirations

INTRODUCTION The roles of non-medically trained practitioners within the NHS are expanding; they are now being employed by many specialties, including surgery, to relieve pressures on healthcare teams. AIMS To investigate the learning curve and competence of an orthopaedic surgical care practitioner (SCP) in performing hip aspirations. METHODS Data were retrospectively collected on 510 orthopaedic hip aspirations, of which 360 were completed by a single SCP and 150 were completed by surgeons before the SCP took over routine aspiration. The 360 aspirations completed by an SCP were separated into groups of 30 by date, so any trend in failure rate could be analysed. Ordinal χ² analysis was used to analyse this trend and Pearson χ² analysis was used to analyse differences in failure rates between professionals. RESULTS The hip aspiration failure rate for the SCP was significantly lower than for the surgeons; 8.6% vs 20.7% (P<0.001). With the experience gained in completing the first 210 procedures, the failure rate of the SCP dropped to 3.3% for the remaining 150 procedures. This downward trend in hip aspiration failure rate, with advancing experience of the SCP, was shown to be statistically significant (P=0.006). DISCUSSION SCPs who complete hip aspirations on a regular basis have significantly lower failure rates than surgeons, probably as a result of the learning curve, which this study demonstrated. Other trusts should consider delegating routine hip aspiration work to a designated SCP to lower failure rates.

Pre-operative templating for trauma hemiarthroplasty (Thompson's)

INTRODUCTION

Surgical complications may be avoided by preoperative templating in trauma hemiarthroplasty.

MATERIALS AND METHODS

Digital templates for the Stryker™ range of Thompson's prostheses were created and fifty trauma patients that had undergone cemented hemiarthroplasty were retrospectively templated by 2 blinded surgeons.

RESULTS

Templating for prosthesis size was highly accurate with excellent Inter and intra-observer reproducibility. Sensitivity for identifying femoral canals too narrow for a Thompsons was 100%.

CONCLUSIONS

Templating is a valuable tool and should be standard practice in trauma. We have demonstrated that it is possible to generate custom templates to allow accurate templating.

Complications and survival analyses of hip arthroscopies performed in the national health service in England: a review of 6,395 cases

PURPOSE

Our study aimed to identify the complications of hip arthroscopies with particular emphasis on the 30-day readmission rate; 90-day deep vein thrombosis (DVT) and pulmonary embolism (PE) rate and mortality rate; revision hip arthroscopy rate; and in particular, survivorship with conversion to total hip replacement (THR) as the endpoint.

METHODS

The records of patients undergoing hip arthroscopy were extracted from the administrative hospital admissions database covering all admissions to the National Health Service hospitals in England using ICD-10 (International Statistical Classification of Diseases and Related Health Problems, 10th Revision) and OPCS-4 (Office of Population Censuses and Surveys Classification of Surgical Operations and Procedures, fourth revision) codes.

RESULTS

A total of 6,395 hip arthroscopies were included in the study period. The 30-day readmission rate was 0.5%; both the 90-day DVT rate and PE rate were 0.08%; and the 90-day mortality rate was 0.02%. THR was performed in 680 patients (10.6%) at a mean of 1.4 years after the index operation, and 286 patients (4.5%) underwent revision hip arthroscopy at a mean of 1.7 years. Kaplan-Meier survival analysis showed an 8-year survival rate of 82.6% (95% confidence interval [CI], 80.9% to 84.2%), whereas Cox proportional hazard analysis adjusting for age, gender, and Charlson comorbidity score showed an 8-year survival rate of 86%. Female patients had a 1.68 times (95% CI, 1.41 to 2.01) higher risk of conversion to THR than male patients, and patients aged 50 years or older had a 4.65 (95% CI, 3.93 to 5.49) times higher risk of requiring hip replacement than patients younger than 50 years.

CONCLUSIONS

In this large series of 6,395 hip arthroscopies looking at the national data from the English National Health Service, our null hypothesis has been supported, and we have determined that the rate of short-term complications, in particular the risk of DVT and PE after this operation, is low. Higher age and female gender are significant predictors of conversion to THR, with Cox proportional hazard analyses showing a survivorship rate of 86% at 8 years after adjustment for confounding variables.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Reduced short-term complications and mortality following Enhanced Recovery primary hip and knee arthroplasty: results from 6,000 consecutive procedures

BACKGROUND AND PURPOSE

Enhanced Recovery (ER) is a well-established multidisciplinary strategy in lower limb arthroplasty and was introduced in our department in May 2008. This retrospective study reviews short-term outcomes in a consecutive unselected series of 3,000 procedures (the "ER" group), and compares them to a numerically comparable cohort that had been operated on previously using a traditional protocol (the "Trad" group).

METHODS

Prospectively collected data on surgical endpoints (length of stay (LOS), return to theater (RTT), re-admission, and 30- and 90-day mortality) and medical complications (stroke, gastrointestinal bleeding, myocardial infarction, and pneumonia within 30 days; deep vein thrombosis and pulmonary embolism within 60 days) were compared. Results ER included 1,256 THR patients and 1,744 TKR patients (1,369 THRs and 1,631 TKRs in Trad). The median LOS in the ER group was reduced (3 days vs. 6 days; p = 0.01). Blood transfusion rate was also reduced (7.6% vs. 23%; p < 0.001), as was RTT rate (p = 0.05). The 30-day incidence of myocardial infarction declined (0.4% vs. 0.9%; p = 0.03) while that of stroke, gastrointestinal bleeding, pneumonia, deep vein thrombosis, and pulmonary embolism was not statistically significantly different. Mortality at 30 days and at 90 days was 0.1% and 0.5%, respectively, as compared to 0.5% and 0.8% using the traditional protocol (p = 0.03 and p = 0.1, respectively).

INTERPRETATION

This is the largest study of ER arthroplasty, and provides safety data on a consecutive unselected series. The program has achieved a statistically significant reduction in LOS and in cardiac ischemic events for our patients, with a near-significant decrease in return to theater and in mortality rates.

Enhanced recovery program for hip and knee replacement reduces death rate

BACKGROUND AND PURPOSE

Multimodal techniques can aid early rehabilitation and discharge of patients following primary joint replacement. We hypothesized that this not only reduces the economic burden of joint replacement by reducing length of stay, but also helps in reduction of early complications.

PATIENTS AND METHODS

We evaluated 4,500 consecutive unselected total hip replacements and total knee replacements regarding length of hospital stay, mortality, and perioperative complications. The first 3,000 underwent a traditional protocol while the other 1,500 underwent an enhanced recovery protocol involving behavioral, pharmacological, and procedural modifications.

RESULTS

There was a reduction in 30-day death rate (0.5% to 0.1%, p = 0.02) and 90-day death rate (0.8% to 0.2%, p = 0.01). The median length of stay decreased from 6 days to 3 days (p < 0.001), resulting in a saving of 5,418 bed days. Requirement for blood transfusion was reduced (23% to 9.8%, p < 0.001). There was a trend of a reduced rate of 30-day myocardial infarction (0.8% to 0.5%. p = 0 .2) and stroke (0.5% to 0.2%, p = 0.2). The 60-day deep vein thrombosis figures (0.8% to 0.6%, p = 0.5) and pulmonary embolism figures (1.2% to 1.1%, p = 0.9) were similar. Re-admission rate remained unchanged during the period of the study (4.7% to 4.8%, p = 0.8).

INTERPRETATION

This large observational study of unselected consecutive hip and knee arthroplasty patients shows a substantial reduction in death rate, reduced length of stay, and reduced transfusion requirements after the introduction of a multimodal enhanced recovery protocol.

Hip resurfacing revision rates: radiological audit of risk factors

INTRODUCTION

We performed a retrospective radiological audit of the hip resurfacings carried out in our trust over a five-year period. Abnormal cup inclination angle (CIA) and stem shaft angle (SSA) are recognised risk factors for revision in hip resurfacing. Our aims were to identify the CIA and SSA for hip resurfacings in our trust, to determine the revision rate in a CIA of ≥60° and an SSA of >0° varus, thereby identifying a high risk group for close, long-term follow up.

METHODS

A total of 247 patients underwent hip resurfacing in our trust between April 2003 and March 2008. The CIA and SSA were recorded. Of the 247 patients, 26 were excluded as there were no appropriate radiographs and so results were analysed for 221 patients.

RESULTS

The mean CIA was 47.6°. Over a third of the patients (34%) had a CIA of >50° and 13% had >60°. The mean SSA was 1.4° varus. Over two-thirds of the patients (67%) had a varus SSA. There were six revisions but one was excluded as it was secondary to infection. The revision rate was 10% in patients with a CIA of ≥60° and 1% in those with a CIA of <60° (p=0.017), and 1% in a varus and 4% in a valgus SSA ((p)>0.05) respectively.

CONCLUSIONS

The measurement of the CIA and SSA in hip resurfacings has identified a high risk group for close long-term follow up. There is already a 10% revision rate in those patients with a CIA of >60°. Hip resurfacing may generate a large revision burden in the 'average' surgeon's hands and all hospitals/surgeons should review their radiological outcomes critically and identify those at risk of revision.

Return to theatre following total hip and knee replacement, before and after the introduction of rivaroxaban: a retrospective cohort study

Rivaroxaban has been recommended for routine use as a thromboprophylactic agent in patients undergoing lower-limb arthroplasty. However, trials supporting its use have not fully evaluated the risks of wound complications. This study of 1048 total hip/knee replacements records the rates of return to theatre and infection before and after the change from a low molecular weight heparin (tinzaparin) to rivaroxaban as the agent of chemical thromboprophylaxis in patients undergoing lower-limb arthroplasty. During a period of 13 months, 489 consecutive patients undergoing lower-limb arthroplasty received tinzaparin and the next 559 consecutive patients received rivaroxaban as thromboprophylaxis. Nine patients in the control (tinzaparin) group (1.8%, 95% confidence interval 0.9 to 3.5) returned to theatre with wound complications within 30 days, compared with 22 patients in the rivaroxaban group (3.94%, 95% confidence interval 2.6 to 5.9). This increase was statistically significant (p = 0.046). The proportion of patients who returned to theatre and became infected remained similar (p = 0.10). Our study demonstrates the need for further randomised controlled clinical trials to be conducted to assess the safety and efficacy of rivaroxaban in clinical practice, focusing on the surgical complications as well as the potential prevention of venous thromboembolism.

Wear analysis of failed acetabular polyethylene: a comparison of analytical methods

There are many methods for analysing wear volume in failed polyethylene acetabular components. We compared a radiological technique with three recognised ex vivo methods of measurement. We tested 18 ultra-high-molecular-weight polyethylene acetabular components revised for wear and aseptic loosening, of which 13 had pre-revision radiographs, from which the wear volume was calculated based upon the linear wear. We used a shadowgraph technique on silicone casts of all of the retrievals and a coordinate measuring method on the components directly. For these techniques, the wear vector was calculated for each component and the wear volume extrapolated using mathematical equations. The volumetric wear was also measured directly using a fluid-displacement method. The results of each technique were compared. The series had high wear volumes (mean 1385 mm(3); 730 to 1850) and high wear rates (mean 205 mm(3)/year; 92 to 363). There were wide variations in the measurements of wear volume between the radiological and the other techniques. Radiograph-derived wear volume correlated poorly with that of the fluid-displacement method, co-ordinate measuring method and shadowgraph methods, becoming less accurate as the wear increased. The mean overestimation in radiological wear volume was 47.7% of the fluid-displacement method wear volume. Fluid-displacement method, coordinate measuring method and shadowgraph determinations of wear volume were all better than that of the radiograph-derived linear measurements since they took into account the direction of wear. However, only radiological techniques can be used in vivo and remain useful for monitoring linear wear in the clinical setting. Interpretation of radiological measurements of acetabular wear must be done judiciously in the clinical setting. In vitro laboratory techniques, in particular the fluid-displacement method, remain the most accurate and reliable methods of assessing the wear of acetabular polyethylene.

Perioperative management of trauma patients admitted on clopidogrel (Plavix). A survey of orthopaedic departments across the United Kingdom

BACKGROUND

Clopidogrel (Plavix) is an anti-platelet drug recommended as lifelong treatment by NICE for all patients following stroke, MI, and peripheral vascular disease. It is also indicated for short-term use following cardiac stent insertion. It irreversibly inhibits platelets for up to 7 days. Current recommendations are to stop treatment 7 days before elective surgery. Current evidence shows that delay to surgery more than 4 days in patients with hip fractures increases postoperative mortality.

OBJECTIVES

To determine current practice of orthopaedic surgeons in their management of patients taking clopidogrel admitted following a hip fracture to trauma units in the UK with respect to its peri-operative withdrawal and subsequent timing of surgery. To perform a review of the available literature and produce a suggested protocol for the peri-operative management of this rapidly increasing cohort of patients.

DESIGN

National postal survey.

PARTICIPANTS

Orthopaedic consultants representing each unit receiving trauma patients in the United Kingdom.

RESULTS

There was a 57% response rate (139/244 UK trauma units). 41% (56) stop clopidogrel and operate immediately, 11% (15) stop clopidogrel for between 5 and 10 days pre-operatively, 10% (14) stop clopidogrel for 10 days preoperatively, 19% (26) continue clopidogrel and operate immediately, 19% (26) have another protocol. 15% (20) have written departmental guidelines. 2%(3) quoted published evidence for their practice.

CONCLUSIONS

This study demonstrates that there are a wide variety of practices, largely based on anecdotal evidence. Most units (85%) have no formal guidelines. There is evidence in the cardiac literature of increased intra-operative bleeding in patients operated on while taking clopidogrel. There is likely to be an exponential rise in such patients presenting to trauma units and further research is required to guide best practice. Following review of the literature we propose an interim protocol for the withdrawal and resumption of clopidogrel peri-operatively in patients with hip fractures.

Wound complications in elective orthopaedics: are current British national data relevant?

INTRODUCTION

The UK Nosocomial Infection National Surveillance Service (NINSS) collects data on surgical wound infection in a variety of procedures, including arthroplasty, to allow comparison between institutions.

PATIENTS AND METHODS

We have compared the results of a 6-month data collection by NINSS within our department with our own grading system of wound complications in elective arthroplasty surgery.

RESULTS

In this period, NINSS has reported one wound infection in our patients. However, we have recorded five patients who were returned to theatre for wound debridement, and yielded positive cultures from multiple specimens. Seven patients received antibiotic therapy alone for wound problems.

CONCLUSIONS

We present our wound grading system as suitable for the collection of data on wound complications in elective orthopaedic surgery.

Pre-heating of components in cemented total hip arthroplasty

Fatigue fractures which originate at stress-concentrating voids located at the implant-cement interface are a potential cause of septic loosening of cemented femoral components. Heating of the component to 44 degrees C is known to reduce the porosity of the cement-prosthesis interface. The temperature of the cement-bone interface was recorded intra-operatively as 32.3 degrees C. A simulated femoral model was devised to study the effect of heating of the component on the implant-cement interface. Heating of the implant and vacuum mixing have a synergistic effect on the porosity of the implant-cement interface, and heating also reverses the gradients of microhardness in the mantle. Heating of the implant also reduces porosity at the interface depending on the temperature. A minimum difference in temperature between the implant and the bone of 3 degrees C was required to produce this effect. The optimal difference was 7 degrees C, representing a balance between maximal reduction of porosity and an increased risk of thermal injury. Using contemporary cementing techniques, heating the implant to 40 degrees C is recommended to produce an optimum effect.

Premature wear and osteolysis in an HA-coated, uncemented total hip arthroplasty

The ABG I cementless hip prosthesis has demonstrated unacceptably high rates of wear and osteolysis in our patients. We performed a retrospective study of 97 hips implanted between 1992 and 1998. Radiographic analysis revealed high rates of wear of the polyethylene liner with marked peri-acetabular osteolysis. Clinical examination indicated that many of these patients were initially asymptomatic. Wear-related problems have required ten hips to be revised and a furher 13 are awaiting revision. This gives a failure rate of 24% at a mean follow-up of 69 months. Contributing factors are likely to include poor wear characteristics of the polyethylene liners which were gamma irradiated in air, and increased wear debris caused by a poor fit of the polyethylene liner within the shell. We believe that all ABG I implants should be immediately reviewed and remain under careful, long-term follow-up.

Extramedullary or intramedullary tibial alignment guides: a randomised, prospective trial of radiological alignment

We undertook a prospective, randomised study of 135 total knee arthroplasties to determine the most accurate and reliable technique for alignment of the tibial prosthesis. Tibial resection was guided by either intramedullary or extramedullary alignment jigs. Of the 135 knees, standardised postoperative radiographs suitable for assessment were available in 100. Correct tibial alignment was found in 85% of the intramedullary group compared with 65% of the extramedullary group (p = 0.019). We conclude that intramedullary guides are superior to extramedullary instruments for alignment of the tibial prosthesis.

Diagnostic injection around the shoulder: hit and miss? A cadaveric study of injection accuracy

In a cadaver study the success of injections in the subacromial space and acromioclavicular joint was studied. Twenty-four shoulders were dissected after separate dye injection was performed with the patient in the supine position. Subacromial bursa injection was successful in 83% (20 shoulders), but in 15 shoulders other structures were also infiltrated, including seven injections in the rotator cuff. Acromioclavicular joint injection was successful in 67% (16 shoulders), but half involved other structures. The authors believe that misplaced injections may be diagnostically misleading and potentially harmful.

Twenty-three years of experience with sphincterotomy and sphincteroplasty for stenosis of the sphincter of Oddi

A 23 year experience with papillotomy, sphincterotomy and sphincteroplasty for stenosis of the sphincter of Oddi shows sphincteroplasty to be the best procedure, with 79% of the patients obtaining a good result. The procedure was done for a demonstrable organic change in the sphincter, often associated with acute cholecystitis in older patients, the postcholecystectomy syndrome in those in whom a long cystic stump had been left at the first operation or in patients with chronic recurring pancreatitis. The study included 138 private patients observed from two months to 22 years. There were four postoperative deaths, an operative mortality of 2.9%, as two patients had been operated upon twice. The poor results were associated with recurring attacks of pancreatitis not cured by the procedure or developing subsequent to it, probably being attributable to persistent obstruction of the terminal part of the pancreatic duct. The results suggest that sphincteroplasty, if performed on suitably selected patients, is a safe procedure which should give good results in more than 75% of the patients.