Aims

Deep surgical site infection (SSI) remains an unsolved problem after hip fracture. Debridement, antibiotic, and implant retention (DAIR) has become a mainstream treatment in elective periprosthetic joint infection; however, evidence for DAIR after infected hip hemiarthroplaty is limited.

Aims

We studied the impact of direct anterior (DA) versus non-anterior (NA) surgical approaches on prosthetic joint infection (PJI), and examined the impact of new perioperative protocols on PJI rates following all surgical approaches at a single institution.

Aims

A variety of surgical approaches are used for total hip arthroplasty (THA), all with reported advantages and disadvantages. A number of common complications can occur following THA regardless of the approach used. The purpose of this study was to compare five commonly used surgical approaches with respect to the incidence of surgery-related complications.

The February 2023 Knee Roundup. 360. looks at: Machine-learning models: are all complications predictable?; Positive cultures can be safely ignored in revision arthroplasty patients that do not meet the 2018 International Consensus Meeting Criteria; Spinal versus general anaesthesia in contemporary primary total knee arthroplasty; Preoperative pain and early arthritis are associated with poor outcomes in total knee arthroplasty; Risk factors for infection and revision surgery following patellar tendon and quadriceps tendon repairs; Supervised versus unsupervised rehabilitation following total knee arthroplasty; Kinematic alignment has similar outcomes to mechanical alignment: a systematic review and meta-analysis; Lifetime risk of revision after knee arthroplasty influenced by age, sex, and indication; Risk factors for knee osteoarthritis after traumatic knee injury

Aims. The aim of the present study was to assess the outcomes of the induced membrane technique (IMT) for the management of infected segmental bone defects, and to analyze predictive factors associated with unfavourable outcomes. Methods. Between May 2012 and December 2020, 203 patients with infected segmental bone defects treated with the IMT were enrolled. The digital medical records of these patients were retrospectively analyzed. Factors associated with unfavourable outcomes were identified through logistic regression analysis. Results. Among the 203 enrolled patients, infection recurred in 27 patients (13.3%) after bone grafting. The union rate was 75.9% (154 patients) after second-stage surgery without additional procedures, and final union was achieved in 173 patients (85.2%) after second-stage surgery with or without additional procedures. The mean healing time was 9.3 months (3 to 37). Multivariate logistic regression analysis of 203 patients showed that the number (≥ two) of debridements (first stage) was an independent risk factor for infection recurrence and nonunion. Larger defect sizes were associated with higher odds of nonunion. After excluding 27 patients with infection recurrence, multivariate analysis of the remaining 176 patients suggested that intramedullary nail plus plate internal fixation, smoking, and an allograft-to-autograft ratio exceeding 1:3 adversely affected healing time. Conclusion. The IMT is an effective method to achieve infection eradication and union in the management of infected segmental bone defects. Our study identified several risk factors associated with unfavourable outcomes. Some of these factors are modifiable, and the risk of adverse outcomes can be reduced by adopting targeted interventions or strategies. Surgeons can fully inform patients with non-modifiable risk factors preoperatively, and may even use other methods for bone defect reconstruction. Cite this article: Bone Joint J 2024;106-B(6):613–622

The December 2023 Trauma Roundup. 360. looks at: Distal femoral arthroplasty: medical risks under the spotlight; Quads repair: tunnels or anchors?; Complex trade-offs in treating severe tibial fractures: limb salvage versus primary amputation; Middle-sized posterior malleolus fractures – to fix?; Bone transport through induced membrane: a randomized controlled trial; Displaced geriatric femoral neck fractures; Risk factors for reoperation to promote union in 1,111 distal femur fractures; New versus old – reliability of the OTA/AO classification for trochanteric hip fractures; Risk factors for fracture-related infection after ankle fracture surgery

Aims. Previous research has demonstrated increased early complication rates following total hip arthroplasty (THA) in obese patients, as defined by body mass index (BMI). Subcutaneous fat depth (FD) has been shown to be an independent risk factor for wound infection in cervical and lumbar spine surgery, as well as after abdominal laparotomy. The aim of this study was to investigate whether increased peritrochanteric FD was associated with an increased risk of complications in the first year following THA. Methods. We analyzed prospectively collected data on a consecutive series of 1,220 primary THAs from June 2013 until May 2018. The vertical soft tissue depth from the most prominent part of the greater trochanter to the skin was measured intraoperatively using a sterile ruler and recorded to the nearest millimetre. BMI was calculated at the patient’s preoperative assessment. All surgical complications occuring within the initial 12 months of follow-up were identified. Results. Females had a significantly greater FD at the greater trochanter in comparison to males (median 3.0 cm (interquartile range (IQR) 2.3 to 4.0) vs 2.0 cm (IQR 1.7 to 3.0); p < 0.001) despite equivalent BMI between sexes (male median BMI 30.0 kg/m. 2. (IQR 27.0 to 33.0); female median 29.0 kg/m. 2. (IQR 25.0 to 33.0)). FD showed a weak correlation with BMI (R² 0.41 males and R² 0.43 females). Patients with the greatest FD (upper quartile) were at no greater risk of complications compared with patients with the lowest FD (lower quartile); 7/311 (2.3%) vs 9/439 (2.1%); p = 0.820 . Conversely, patients with the highest BMI (≥ 40 kg/m. 2. ) had a significantly increased risk of complications compared with patients with lower BMI (< 40 kg/m. 2. ); 5/60 (8.3% vs 18/1,160 (1.6%), odds ratio (OR) 5.77 (95% confidence interval (CI) 2.1 to 16.1; p = 0.001)). Conclusion. We found no relationship between peritrochanteric FD and the risk of surgical complications following primary THA. Cite this article: Bone Joint J 2020;102-B(9):1146–1150

Aims

Achievement of accurate microbiological diagnosis prior to revision is key to reducing the high rates of persistent infection after revision knee surgery. The effect of change in the microorganism between the first- and second-stage revision of total knee arthroplasty for periprosthetic joint infection (PJI) on the success of management is not clear.

Aims

The aim of this investigation was to compare risk of infection in both cemented and uncemented hemiarthroplasty (HA) as well as in total hip arthroplasty (THA) following femoral neck fracture.

Aims

This study was designed to characterize the recurrence incidence and risk factors of antibiotic-loaded cement spacer (ALCS) for definitive bone defect treatment in limb osteomyelitis.

Aims

Calcaneal osteomyelitis remains a difficult condition to treat with high rates of recurrence and below-knee amputation, particularly in the presence of severe soft-tissue destruction. This study assesses the outcomes of single-stage orthoplastic surgical treatment of calcaneal osteomyelitis with large soft-tissue defects.

Aims

Patients with a high comorbidity burden (HCB) can achieve similar improvements in quality of life compared with low-risk patients, but greater morbidity may deter surgeons from operating on these patients. Whether surgeon volume influences total hip arthroplasty (THA) outcomes in HCB patients has not been investigated. This study aimed to compare complication rates and implant survivorship in HCB patients operated on by high-volume (HV) and non-HV THA surgeons.

Aims

The aim of this study is to report the implant survival and factors associated with revision of total elbow arthroplasty (TEA) using data from the Dutch national registry.

Aims

Despite numerous studies focusing on periprosthetic joint infections (PJIs), there are no robust data on the risk factors and timing of metachronous infections. Metachronous PJIs are PJIs that can arise in the same or other artificial joints after a period of time, in patients who have previously had PJI.

Aims

Frailty has been gathering attention as a factor to predict surgical outcomes. However, the association of frailty with postoperative complications remains controversial in spinal metastases surgery. We therefore designed a prospective study to elucidate risk factors for postoperative complications with a focus on frailty.

We report a prospective single-blind controlled study of the incidence of early wound infection after internal fixation for trauma in 609 patients, of whom 132 were HIV-positive. Wounds were assessed for healing using the ASEPSIS score. There was no significant difference in the rate of infection between HIV-positive and HIV-negative patients undergoing clean surgery (4.2% vs 6%, respectively; p = 0.65). HIV-positive patients did not receive additional antibiotic prophylaxis or antiretroviral therapy as part of their management. The difference in the rate of infection between HIV-positive and HIV-negative patients with an open fracture or other contamination was not significant (33% vs 15%, respectively; p = 0.064). There was no relationship between CD4 count and infection rate. HIV status did not significantly influence the number of secondary surgical procedures (p = 0.183) or the likelihood of developing chronic osteomyelitis (p = 0.131). Although previous contamination from the time of injury was a risk factor for infection in mal- and nonunions, it was not significantly increased in HIV-positive patients (p = 0.144). We conclude that clean implant surgery in HIV-positive patients is safe, with no need for additional prophylaxis

Aims

There is conflicting evidence on the safety of intra-articular injections of hyaluronic acid (HA) or corticosteroids (CSs) before total knee arthroplasty (TKA). We performed a meta-analysis of the relationship between intra-articular injections and subsequent infection rates after TKA.

Aims

Open discectomy (OD) is the standard operation for lumbar disc herniation (LDH). Percutaneous endoscopic lumbar discectomy (PELD), however, has shown similar outcomes to OD and there is increasing interest in this procedure. However despite improved surgical techniques and instrumentation, reoperation and infection rates continue and are reported to be between 6% and 24% and 0.7% and 16%, respectively. The objective of this study was to compare the rate of reoperation and infection within six months of patients being treated for LDH either by OD or PELD.

Aims. The aim of this study was to identify risk factors for prosthetic joint infection (PJI) following total knee arthroplasty (TKA). . Patients and Methods. The New Zealand Joint Registry database was analysed, using revision surgery for PJI at six and 12 months after surgery as primary outcome measures. Statistical associations between revision for infection, with common and definable surgical and patient factors were tested. Results. A total of 64 566 primary TKAs have been recorded on the registry between 1999 and 2012 with minimum follow-up of 12 months. Multivariate analysis showed statistically significant associations with revision for PJI between male gender (odds ratio (OR) 1.85, 95% confidence interval (CI) 1.24 to 2.74), previous surgery (osteotomy (OR 2.45 95% CI 1.2 to 5.03), ligament reconstruction (OR 1.85, 95% CI 0.68 to 5.00)), the use of laminar flow (OR 1.6, 95% CI 1.04 to 2.47) and the use of antibiotic-laden cement (OR 1.93, 95% CI 1.19 to 3.13). There was a trend towards significance (p = 0.052) with the use of surgical helmet systems at six months (OR 1.53, 95% CI 1.00 to 2.34). Conclusion. These findings show that patient factors remain the most important in terms of predicting early PJI following TKA. Furthermore, we found no evidence that modern surgical helmet systems reduce the risk of PJI and laminar flow systems may actually increase risk in TKA. The use of this registry data assists the estimation of the risk of PJI for individual patients, which is important for both informed consent and the interpretation of infection rates at different institutions. . Take home message: Infection rates in TKA are related to both individual patient and surgical factors, and some modern methods of reducing infection may actually increase infection risk. . Cite this article: Bone Joint J 2016;98-B:334–40

Aims

Orthopaedic infection is a potentially serious complication of elective and emergency trauma and orthopaedic procedures, with a high associated burden of morbidity and cost. Optimization of vitamin D levels has been postulated to be beneficial in the prevention of orthopaedic infection. This study explores the role of vitamin D in orthopaedic infection through a systematic review of available evidence.

Aims

Rotating-hinge knee prostheses are commonly used to reconstruct the distal femur after resection of a tumour, despite the projected long-term burden of reoperation due to complications. Few studies have examined the factors that influence their failure and none, to our knowledge, have used competing risk models to do so. The purpose of this study was to determine the risk factors for failure of a rotating-hinge knee distal femoral arthroplasty using the Fine-Gray competing risk model.

Aims

Single-stage revision total knee arthroplasty (rTKA) is gaining popularity in treating chronic periprosthetic joint infections (PJIs). We have introduced this approach to our clinical practice and sought to evaluate rates of reinfection and re-revision, along with predictors of failure of both single- and two-stage rTKA for chronic PJI.

Aims

The new COVID-19 variant was reported by the authorities of the UK to the World Health Organization (WHO) on 14 December 2020. We aim to describe the clinical characteristics and nosocomial infection rates in major trauma and orthopaedic patients comparing the first and second wave of COVID-19 infection.

We undertook a study to determine the rates of infection and revision of total knee replacement (TKR) in patients with renal failure, renal transplantation and those undergoing renal dialysis in Scotland. The overall early and late infection rates were 1.10% and 2.19% compared with 1.06% and 2.01%, respectively, for non-renal patients. Patients with renal failure had a significantly increased risk of early infection (1.6%, relative risk 1.52, p = 0.002) and late infection (4.47%, relative risk 2.22, p < 0.001). Those on renal dialysis had significantly increased risks of late infection (8.03%, relative risk 3.99, p < 0.001) and early revision (3.70%, relative risk 4.40, p < 0.001). Renal transplant patients had a significantly increased risk of late infection, regardless of whether renal transplantation occurred before TKR (9.09%, relative risk 4.517, p = 0.027) or at any time (8.0%, relative risk 3.975, p = 0.047). There were significantly increased rates of comorbidities associated with infection for all the renal patient groups. Logistic regression analysis showed that renal failure and renal dialysis were independent risk factors for early infection and revision, respectively

Cementless knee arthroplasty has seen a recent resurgence in popularity due to conceptual advantages, including improved osseointegration providing biological fixation, increased surgical efficiency, and reduced systemic complications associated with cement impaction and wear from cement debris. Increasingly younger and higher demand patients are requiring knee arthroplasty, and as such, there is optimism cementless fixation may improve implant survivorship and functional outcomes.

Compared to cemented implants, the National Joint Registry (NJR) currently reports higher revision rates in cementless total knee arthroplasty (TKA), but lower in unicompartmental knee arthroplasty (UKA). However, recent studies are beginning to show excellent outcomes with cementless implants, particularly with UKA which has shown superior performance to cemented varieties. Cementless TKA has yet to show long-term benefit, and currently performs equivalently to cemented in short- to medium-term cohort studies. However, with novel concepts including 3D-printed coatings, robotic-assisted surgery, radiostereometric analysis, and kinematic or functional knee alignment principles, it is hoped they may help improve the outcomes of cementless TKA in the long-term. In addition, though cementless implant costs remain higher due to novel implant coatings, it is speculated cost-effectiveness can be achieved through greater surgical efficiency and potential reduction in revision costs. There is paucity of level one data on long-term outcomes between fixation methods and the cost-effectiveness of modern cementless knee arthroplasty.

This review explores recent literature on cementless knee arthroplasty, with regards to clinical outcomes, implant survivorship, complications, and cost-effectiveness; providing a concise update to assist clinicians on implant choice.

Cite this article: Bone Jt Open 2021;2(1):48–57.

Aims

For many designs of total knee arthroplasty (TKA) it remains unclear whether cemented or uncemented fixation provides optimal long-term survival. The main limitation in most studies is a retrospective or non-comparative study design. The same is true for comparative trials looking only at the survival rate as extensive sample sizes are needed to detect true differences in fixation and durability. Studies using radiostereometric analysis (RSA) techniques have shown to be highly predictive in detecting late occurring aseptic loosening at an early stage. To investigate the difference in predicted long-term survival between cemented, uncemented, and hybrid fixation of TKA, we performed a randomized controlled trial using RSA.

Aims

We aimed to report the mid- to long-term rates of septic and aseptic failure after two-stage revision surgery for periprosthetic joint infection (PJI) following total hip arthroplasty (THA).

Aims

The impact of tobacco use on readmission and medical and surgical complications has been documented in hip and knee arthroplasty. However, there remains little information about the effect of smoking on the outcome after total shoulder arthroplasty (TSA). We hypothesized that active smokers are at an increased risk of poor medical and surgial outcomes after TSA.

Aims

Arthrodesis is rarely used as a salvage procedure for patients with a chronically infected total knee arthroplasty (TKA), and little information is available about the outcome. The aim of this study was to assess the reliability, durability, and safety of this procedure as the definitive treatment for complex, chronically infected TKA, in a current series of patients.

Aims

The risk to patients and healthcare workers of resuming elective orthopaedic surgery following the peak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has been difficult to quantify. This has prompted governing bodies to adopt a cautious approach that may be impractical and financially unsustainable. The lack of evidence has made it impossible for surgeons to give patients an informed perspective of the consequences of elective surgery in the presence of SARS-CoV-2. This study aims to determine, for the UK population, the probability of a patient being admitted with an undetected SARS-CoV-2 infection and their resulting risk of death; taking into consideration the current disease prevalence, reverse transcription-polymerase chain reaction (RT-PCR) testing, and preassessment pathway.

There is no firm published evidence to support the use of closed suction drains. Over 20 years ago, large studies by the Public Health Laboratory Service and the National Research Council found that drains were risk factors for wound infection. A prospective randomised study of the use of closed suction drains after surgery for fractured neck of femur in 70 patients failed to show that drains improved wound healing. Drained cases had more complications

Aims

Prosthetic joint infection (PJI) remains a major clinical challenge. Neutrophil CD64 index, Fc-gamma receptor 1 (FcγR1), plays an important role in mediating inflammation of bacterial infections and therefore could be a valuable biomarker for PJI. The aim of this study is to compare the neutrophil CD64 index in synovial and blood diagnostic ability with the standard clinical tests for discrimination PJI and aseptic implant failure.

Aims

This paper aims to review the evidence for patient-related factors associated with less favourable outcomes following hip arthroscopy.

Aims

Although internal hemipelvectomy is associated with a high incidence of morbidity, especially wound complications, few studies have examined rates of wound complications in these patients or have identified factors associated with the consequences. The present study aimed to: 1) determine the rate of wound and other complications requiring surgery after internal hemipelvectomy; and 2) identify factors that affect the rate of wound complications and can be used to stratify patients by risk of wound complications.

Aims

Graft infection following anterior cruciate ligament reconstruction (ACLR) may lead to septic arthritis requiring multiple irrigation and debridement procedures, staged revision operations, and prolonged courses of antibiotics. To our knowledge, there are no previous studies reporting on how gentamicin pre-soaking of hamstring grafts influences infection rates following ACLR. We set out to examine this in our study accordingly.

Objectives

The optimal protocol for antibiotic loading in the articulating cement spacers for the treatment of prosthetic joint infection (PJI) remains controversial. The objective of the present study was to investigate the effectiveness of articulating cement spacers loaded with a new combination of antibiotics.

Objectives

The optimal protocol for antibiotic loading in the articulating cement spacers for the treatment of prosthetic joint infection (PJI) remains controversial. The objective of the present study was to investigate the effectiveness of articulating cement spacers loaded with a new combination of antibiotics.

Aims

Antibiotic-loaded bone cements (ALBCs) may offer early protection against the formation of bacterial biofilm after joint arthroplasty. Use in hip arthroplasty is widely accepted, but there is a lack of evidence in total knee arthroplasty (TKA). The objective of this study was to evaluate the use of ALBC in a large population of TKA patients.

Deep infection was identified as a serious complication in the earliest days of total hip arthroplasty. It was identified that airborne contamination in conventional operating theatres was the major contributing factor. As progress was made in improving the engineering of operating theatres, airborne contamination was reduced. Detailed studies were carried out relating airborne contamination to deep infection rates.

In a trial conducted by the United Kingdom Medical Research Council (MRC), it was found that the use of ultra-clean air (UCA) operating theatres was associated with a significant reduction in deep infection rates. Deep infection rates were further reduced by the use of a body exhaust system. The MRC trial also included a detailed microbiology study, which confirmed the relationship between airborne contamination and deep infection rates.

Recent observational evidence from joint registries has shown that in contemporary practice, infection rates remain a problem, and may be getting worse. Registry observations have also called into question the value of “laminar flow” operating theatres.

Observational evidence from joint registries provides very limited evidence on the efficacy of UCA operating theatres. Although there have been some changes in surgical practice in recent years, the conclusions of the MRC trial remain valid, and the use of UCA is essential in preventing deep infection.

There is evidence that if UCA operating theatres are not used correctly, they may have poor microbiological performance. Current UCA operating theatres have limitations, and further research is required to update them and improve their microbiological performance in contemporary practice.

Cite this article: Bone Joint J 2018;100-B:1264–9.

Aims

The aims of this study were to report the efficacy of revision surgery for patients with co-infective bacterial and fungal prosthetic joint infections (PJIs) presenting to a single institution, and to identify prognostic factors that would guide management.

Aims

The results of irrigation and debridement with component retention (IDCR) in the treatment of acutely infected total knee arthroplasties (TKAs) have been variable. The aim of this study was to assess the outcome after IDCR when combined with chronic antibiotic suppression. We also evaluated survivorship free from subsequent infection, removal of the components, and death, as well as the risk factors for failure.

Objectives

Nasal carriers of Staphylococcus (S.) aureus (MRSA and MSSA) have an increased risk for healthcare-associated infections. There are currently limited national screening policies for the detection of S. aureus despite the World Health Organization’s recommendations. This study aimed to evaluate the diagnostic performance of molecular and culture techniques in S. aureus screening, determine the cause of any discrepancy between the diagnostic techniques, and model the potential effect of different diagnostic techniques on S. aureus detection in orthopaedic patients.

Aims

Surgical site infection can be a devastating complication of hemiarthroplasty of the hip, when performed in elderly patients with a displaced fracture of the femoral neck. It results in a prolonged stay in hospital, a poor outcome and increased costs. Many studies have identified risk and prognostic factors for deep infection. However, most have combined the rates of infection following total hip arthroplasty and internal fixation as well as hemiarthroplasty, despite the fact that they are different entities. The aim of this study was to clarify the risk and prognostic factors causing deep infection after hemiarthroplasty alone.

Aims

Lifestyle risk factors are thought to increase the risk of infection after acute orthopaedic surgery but the evidence is scarce. We aimed to investigate whether smoking, obesity and alcohol overuse are risk factors for the development of infections after surgery for a fracture of the ankle.

Aims

To evaluate the outcomes of cemented total hip arthroplasty (THA) following a fracture of the acetabulum, with evaluation of risk factors and comparison with a patient group with no history of fracture.

Aims

Periprosthetic joint infection (PJI) remains a challenging complication following total hip arthroplasty (THA). It is associated with high levels of morbidity, mortality and expense. Guidelines and protocols exist for the management of culture-positive patients. Managing culture-negative patients with a PJI poses a greater challenge to surgeons and the wider multidisciplinary team as clear guidance is lacking.

Objectives

We used the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR) to investigate the risk of revision due to prosthetic joint infection (PJI) for patients undergoing primary and revision hip arthroplasty, the changes in risk over time, and the overall burden created by PJI.

Aims

The aim of this study was to report the outcome following primary fixation or a staged protocol for type C fractures of the tibial plafond.

Aims

In the initial development of total shoulder arthroplasty (TSA), the humeral component was usually fixed with cement. Cementless components were subsequently introduced. The aim of this study was to compare the long-term outcome of cemented and cementless humeral components in arthroplasty of the shoulder.

Prophylactic antibiotics can decrease the risk of wound infection and have been routinely employed in orthopaedic surgery for decades. Despite their widespread use, questions still surround the selection of antibiotics for prophylaxis, timing and duration of administration. The health economic costs associated with wound infections are significant, and the judicious but appropriate use of antibiotics can reduce this risk.

This review examines the evidence behind commonly debated topics in antibiotic prophylaxis and highlights the uses and advantages of some commonly used antibiotics.

Cite this article: Bone Joint J 2016;98-B:1014–19.

To prevent insufficiency of the triceps after total elbow arthroplasty, we have, since 2008, used a triceps-sparing ulnar approach. This study evaluates the clinical results and post-operative alignment of the prosthesis using this approach.

We reviewed 25 elbows in 23 patients. There were five men and 18 women with a mean age of 69 years (54 to 83). There were 18 elbows with rheumatoid arthritis, six with a fracture or pseudoarthrosis and one elbow with osteoarthritis.

Post-operative complications included one intra-operative fracture, one elbow with heterotopic ossification, one transient ulnar nerve palsy, and one elbow with skin necrosis, but no elbow was affected by insufficiency of the triceps.

Patients were followed for a mean of 42 months (24 to 77). The mean post-operative Japanese Orthopaedic Association Elbow Score was 90.8 (51 to 100) and the mean Mayo Elbow Performance score 93.8 (65 to 100). The mean post-operative flexion/extension of the elbow was 135°/-8°. The Manual Muscle Testing score of the triceps was 5 in 23 elbows and 2 in two elbows (one patient). The mean alignment of the implants examined by 3D-CT was 2.8° pronation (standard deviation (sd) 5.5), 0.3° valgus (sd 2.7), and 0.7° extension (sd 3.2) for the humeral component, and 9.3° pronation (sd 9.7), 0.3° valgus (sd 4.0), and 8.6° extension (sd 3.1) for the ulnar component. There was no radiolucent line or loosening of the implants on the final radiographs.

The triceps-sparing ulnar approach allows satisfactory alignment of the implants, is effective in preventing post-operative triceps insufficiency, and gives satisfactory short-term results.

Cite this article: 2015;97-B:1096–1101.

The August 2014 Foot & Ankle Roundup360 looks at: calcaneotibial nail in ankle fractures; reamer irrigator aspirator for ankle fusion; periprosthetic bone infection; infection in ankle fixation; cheap and cheerful OK in MTP fusion plates; sliding fibular graft for peroneal tendon pathology and fusion for failed ankle replacement.

Most of the literature on surgical site infections following the surgical treatment of fractures of the ankle is based on small series of patients, focusing on diabetics or the elderly. None have described post-operative functional scores in those patients who develop an infection. We performed an age- and gender-matched case–control study to identify patient- and surgery-related risk factors for surgical site infection following open reduction and internal fixation of a fracture of the ankle. Logistic regression analysis was used to identify significant risk factors for infection and to calculate odds ratios (OR). Function was assessed using the Olerud and Molander Ankle Score. The incidence of infection was 4% (29/717) and 1.1% (8/717) were deep infections. The median ankle score was significantly lower in the infection group compared with the control group (60 vs 90, Mann–Whitney test p < 0.0001). Multivariate regression analysis showed that diabetes (OR = 15, p = 0.031), nursing home residence (OR = 12, p = 0.018) and Weber C fractures (OR = 4, p = 0.048) were significant risk factors for infection.

A low incidence of infection following open reduction and internal fixation of fractures of the ankle was observed. Both superficial and deep infections result in lower functional scores.

Cite this article: Bone Joint J 2014;96-B:636–40.

The August 2014 Oncology Roundup³⁶⁰ looks at: Anaesthesic modality does not affect outcomes in tumour surgery; infection predictors in orthopaedic oncology; sarcoma depth unimportant in survival; photon/proton radiotherapy surprisingly effective in chondrosarcoma control; total humerus replacement a success!; LDH simple predictor of survival in sarcoma; Denosumab again! and Oops procedures in triplicate.

We undertook a retrospective case-control study to assess the clinical variables associated with infections in open fractures. A total of 1492 open fractures were retrieved; these were Gustilo and Anderson grade I in 663 (44.4%), grade II in 370 (24.8%), grade III in 310 (20.8%) and unclassifiable in 149 (10.0%). The median duration of prophylaxis was three days (interquartile range (IQR) 1 to 3), and the median number of surgical interventions was two (1 to 9). We identified 54 infections (3.6%) occurring at a median of ten days (IQR 5 to 20) after trauma. Pathogens intrinsically resistant to the empirical antibiotic regimen used (enterococci, Enterobacter spp, Pseudomonas spp) were documented in 35 of 49 cases (71%). In multivariable regression analyses, grade III fractures and vascular injury or compartment syndrome were significantly associated with infection. Overall, compared with one day of antibiotic treatment, two to three days (odds ratio (OR) 0.6 (95% confidence interval (CI) 0.2 to 2.0)), four to five days (OR 1.2 (95% CI 0.3 to 4.9)), or > five days (OR 1.4 (95% CI 0.4 to 4.4)) did not show any significant differences in the infection risk. These results were similar when multivariable analysis was performed for grade III fractures only (OR 0.3 (95% CI 0.1 to 3.4); OR 0.6 (95% CI 0.2 to 2.1); and OR 1.7 (95% CI 0.5 to 6.2), respectively).

Infection in open fractures is related to the extent of tissue damage but not to the duration of prophylactic antibiotic therapy. Even for grade III fractures, a one-day course of prophylactic antibiotics might be as effective as prolonged prophylaxis.

Cite this article: Bone Joint J 2013;95-B:831–7.

A retrospective review was performed of patients undergoing primary cementless total knee replacement (TKR) using porous tantalum performed by a group of surgical trainees. Clinical and radiological follow-up involved 79 females and 26 males encompassing 115 knees. The mean age was 66.9 years (36 to 85). Mean follow-up was 7 years (2 to 11). Tibial and patellar components were porous tantalum monoblock implants, and femoral components were posterior stabilised (PS) in design with cobalt–chromium fibre mesh. Radiological assessments were made for implant positioning, alignment, radiolucencies, lysis, and loosening. There was 95.7% survival of implants. There was no radiological evidence of loosening and no osteolysis found. No revisions were performed for aseptic loosening. Average tibial component alignment was 1.4° of varus (4°of valgus to 9° varus), and 6.2° (3° anterior to 15° posterior) of posterior slope. Mean femoral component alignment was 6.6° (1° to 11°) of valgus. Mean tibiofemoral alignment was 5.6° of valgus (7° varus to 16° valgus). Patellar tilt was a mean of 2.4° lateral (5° medial to 28° lateral). Patient satisfaction with improvement in pain was 91%. Cementless TKR incorporating porous tantalum yielded good clinical and radiological outcomes at a mean of follow-up of seven-years.

Cite this article: Bone Joint J 2014;96-B(11 Suppl A):87–92.

Previous studies of failure mechanisms leading to revision total knee replacement (TKR) performed between 1986 and 2000 determined that many failed early, with a disproportionate amount accounted for by infection and implant-associated factors including wear, loosening and instability. Since then, efforts have been made to improve implant performance and instruct surgeons in best practice. Recently our centre participated in a multi-centre evaluation of 844 revision TKRs from 2010 to 2011. The purpose was to report a detailed analysis of failure mechanisms over time and to see if failure modes have changed over the past 10 to 15 years. Aseptic loosening was the predominant mechanism of failure (31.2%), followed by instability (18.7%), infection (16.2%), polyethylene wear (10.0%), arthrofibrosis (6.9%) and malalignment (6.6%). The mean time to failure was 5.9 years (ten days to 31 years), 35.3% of all revisions occurred at less than two years, and 60.2% in the first five years. With improvements in implant and polyethylene manufacture, polyethylene wear is no longer a leading cause of failure. Early mechanisms of failure are primarily technical errors. In addition to improving implant longevity, industry and surgeons must work together to decrease these technical errors. All reports on failure of TKR contain patients with unexplained pain who not infrequently have unmet expectations. Surgeons must work to achieve realistic patient expectations pre-operatively, and therefore, improve patient satisfaction post-operatively.

Cite this article: Bone Joint J 2014;96-B(11 Suppl A):101–4.

We examined patient and surgical factors associated with deep surgical site infection (SSI) following total hip replacement (THR) in a large integrated healthcare system. A retrospective review of a cohort of primary THRs performed between 2001 and 2009 was conducted. Patient characteristics, surgical details, surgeon and hospital volumes, and SSIs were identified using the Kaiser Permanente Total Joint Replacement Registry (TJRR). Proportional-hazard regression models were used to assess risk factors for SSI. The study cohort consisted of 30 491 THRs, of which 17 474 (57%) were performed on women. The mean age of the patients in the whole series was 65.5 years (13 to 97; sd 11.8) and the mean body mass index was 29.3 kg/m² (15 to 67; sd 5.9). The incidence of SSI was 0.51% (155 of 30 491). Patient factors associated with SSI included female gender, obesity, and American Society of Anesthesiologists (ASA) score ≥ 3. Age, diagnosis, diabetes and race were not associated with SSI. The only surgical factor associated with SSI was a bilateral procedure. Surgeon and hospital volumes, use of antibiotic-laden cement, fixation method, laminar flow, body exhaust suits, surgical approach and fellowship training were not associated with risk of SSI.

A comprehensive infection surveillance system, combined with a TJRR, identified patient and surgical factors associated with SSI. Obesity and chronic medical conditions should be addressed prior to THR. The finding of increased SSI risk with bilateral THR requires further investigation.

The December 2013 Foot & Ankle Roundup³⁶⁰ looks at: Maisonneuve fractures in the long term; Not all gastrocnemius lengthening equal; Those pesky os fibulare; First tarsometatarsal arthrosis; Juvenile osteochondral lesions; Calcanei and infections; Clinical outcomes of Weber B ankle fractures; and rheumatologists have no impact on ankle rheumatoid arthritis.

Periprosthetic joint infection (PJI) is a devastating complication which can follow a total joint arthroplasty (TJA). Although rare, this ongoing threat undermines the success of TJA, a historically reputable procedure. It has haunted the orthopedic community for decades and several ongoing studies have provided insights and new approaches to effectively battle this multilayered problem.

Total knee replacement (TKR) is an effective method of treating end-stage arthritis of the knee. It is not, however, a procedure without risk due to a number of factors, one of which is diabetes mellitus. The purpose of this study was to estimate the general prevalence of diabetes in patients about to undergo primary TKR and to determine whether diabetes mellitus adversely affects the outcome. We conducted a systematic review and meta-analysis according to the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines. The Odds Ratio (OR) and mean difference (MD) were used to represent the estimate of risk of a specific outcome. Our results showed the prevalence of diabetes mellitus among patients undergoing TKR was 12.2%. Patients with diabetes mellitus had an increased risk of deep infection (OR = 1.61, 95% confidence interval (CI), 1.38 to 1.88), deep vein thrombosis (in Asia, OR = 2.57, 95% CI, 1.58 to 4.20), periprosthetic fracture (OR = 1.89, 95% CI, 1.04 to 3.45), aseptic loosening (OR = 9.36, 95% CI, 4.63 to 18.90), and a poorer Knee Society function subscore (MD = -5.86, 95% CI, -10.27 to -1.46). Surgeons should advise patients specifically about these increased risks when obtaining informed consent and be meticulous about their peri-operative care.

Cite this article: Bone Joint J 2014;96-B:1637–43.

Obesity is a global epidemic of 2.1 billion people and a well known cause of osteoarthritis. Joint replacement in the obese attracts more complications, poorer outcomes and higher revision rates. It is a reversible condition and the fundamental principles of dealing with reversible medical conditions prior to elective total joint replacement should apply to obesity. The dilemma for orthopaedic surgeons is when to offer surgery in the face of a reversible condition, which if treated may obviate joint replacement and reduce the risk and severity of obesity related disease in both the medical arena and the field of orthopaedics.

The June 2013 Hip & Pelvis Roundup³⁶⁰ looks at: failure in metal-on-metal arthroplasty; minimal hip approaches; whether bisphosphonates improve femoral bone stock following arthroplasty; whether more fat means more operative time; surgical infection; vascularised fibular graft for osteonecrosis; subclinical SUFE; and dentists, hips and antibiotics.

We report the short-term follow-up, functional outcome and incidence of early and late infection after total hip replacement (THR) in a group of HIV-positive patients who do not suffer from haemophilia or have a history of intravenous drug use. A total of 29 patients underwent 43 THRs, with a mean follow-up of three years and six months (five months to eight years and two months). There were ten women and 19 men, with a mean age of 47 years and seven months (21 years to 59 years and five months). No early (< 6 weeks) or late (> 6 weeks) complications occurred following their THR. The mean pre-operative Harris hip score (HHS) was 27 (6 to 56) and the mean post-operative HHS was 86 (73 to 91), giving a mean improvement of 59 points (p = < 0.05, Student’s t-test). No revision procedures had been undertaken in any of the patients, and none had any symptoms consistent with aseptic loosening. This study demonstrates that it is safe to perform THR in HIV-positive patients, with good short-term functional outcomes and no apparent increase in the risk of early infection.

Cite this article: Bone Joint J 2014; 96-B:462–6.

Objectives

To review the current best surgical practice and detail a multi-disciplinary approach that could further reduce joint replacement infection.

Prospective data on 6905 consecutive hip fracture patients at a district general hospital were analysed to identify the risk factors for the development of deep infection post-operatively. The main outcome measure was infection beneath the fascia lata.

A total of 50 patients (0.7%) had deep infection. Operations by consultants or a specialist hip fracture surgeon had half the rate of deep infection compared with junior grades (p = 0.01). Increased duration of anaesthesia was significantly associated with deep infection (p = 0.01). The method of fracture fixation was also significant. Intracapsular fractures treated with a hemiarthroplasty had seven times the rate of deep infection compared with those treated by internal fixation (p = 0.001). Extracapsular fractures treated with an extramedullary device had a deep infection rate of 0.78% compared with 0% for those treated with intramedullary devices (p = 0.02).

The management of hip fracture patients by a specialist hip fracture surgeon using appropriate fixation could significantly reduce the rate of deep infection and associated morbidity, along with extended hospitalisation and associated costs.

The December 2012 Trauma Roundup³⁶⁰ looks at: whether tranexamic acid stops bleeding in trauma across the board; antibiotic beads and VAC; whether anaesthetic determines the outcome in surgery for distal radial fractures; high complications in surgery on bisphosphonate-hardened bone; better outcomes but more dislocations in femoral neck fractures; the mythical hip fracture; plate augmentation in nonunion surgery; and SIGN intramedullary nailing and infections.

Staphylococcus aureus is one of the leading causes of surgical site infection (SSI). Over the past decade there has been an increase in methicillin-resistant S. aureus (MRSA). This is a subpopulation of the bacterium with unique resistance and virulence characteristics. Nasal colonisation with either S. aureus or MRSA has been demonstrated to be an important independent risk factor associated with the increasing incidence and severity of SSI after orthopaedic surgery. Furthermore, there is an economic burden related to SSI following orthopaedic surgery, with MRSA-associated SSI leading to longer hospital stays and increased hospital costs. Although there is some controversy about the effectiveness of screening and eradication programmes, the literature suggests that patients should be screened and MRSA-positive patients treated before surgical admission in order to reduce the risk of SSI.

Cite this article: Bone Joint J 2013;95-B:4–9.

We investigated the capacity of patient warming devices to disrupt the ultra-clean airflow system. We compared the effects of two patient warming technologies, forced-air and conductive fabric, on operating theatre ventilation during simulated hip replacement and lumbar spinal procedures using a mannequin as a patient. Infection data were reviewed to determine whether joint infection rates were associated with the type of patient warming device that was used.

Neutral-buoyancy detergent bubbles were released adjacent to the mannequin’s head and at floor level to assess the movement of non-sterile air into the clean airflow over the surgical site. During simulated hip replacement, bubble counts over the surgical site were greater for forced-air than for conductive fabric warming when the anaesthesia/surgery drape was laid down (p = 0.010) and at half-height (p < 0.001). For lumbar surgery, forced-air warming generated convection currents that mobilised floor air into the surgical site area. Conductive fabric warming had no such effect.

A significant increase in deep joint infection, as demonstrated by an elevated infection odds ratio (3.8, p = 0.024), was identified during a period when forced-air warming was used compared to a period when conductive fabric warming was used. Air-free warming is, therefore, recommended over forced-air warming for orthopaedic procedures.

We have conducted a case-control study over a period of ten years comparing both deep infection with methicillin-resistant staphylococcus aureus (MRSA) and colonised cases with a control group. Risk factors associated with deep infection were vascular diseases, chronic obstructive pulmonary disease, admission to a high-dependency or an intensive-care unit and open wounds. Those for colonisation were institutional care, vascular diseases and dementia. Older age was a risk factor for any MRSA infection. The length of hospital stay was dramatically increased by deep infection. These risk factors are useful in identifying higher-risk patients who may be more susceptible to MRSA infection. A strategy of early identification and isolation may help to control its spread in trauma units

There are 33 million people worldwide currently infected with human immunodeficiency virus (HIV). This complex disease affects many of the processes involved in wound and fracture healing, and there is little evidence available to guide the management of open fractures in these patients. Fears of acute and delayed infection often inhibit the use of fixation, which may be the most effective way of achieving union.

This study compared fixation of open fractures in HIV-positive and -negative patients in South Africa, a country with very high rates of both HIV and high-energy trauma. A total of 133 patients (33 HIV-positive) with 135 open fractures fulfilled the inclusion criteria. This cohort is three times larger than in any similar previously published study.

The results suggest that HIV is not a contraindication to internal or external fixation of open fractures in this population, as HIV is not a significant risk factor for acute wound/implant infection. However, subgroup analysis of grade I open fractures in patients with advanced HIV and a low CD4 count (< 350) showed an increased risk of infection; we suggest that grade I open fractures in patients with advanced HIV should be treated by early debridement followed by fixation at an appropriate time.

We reviewed our initial seven-year experience with a non-invasive extendible prosthesis in 34 children with primary bone tumours. The distal femur was replaced in 25 cases, total femur in five, proximal femur in one and proximal tibia in three. The mean follow-up was 44 months (15 to 86) and 27 patients (79%) remain alive. The prostheses were lengthened by an electromagnetic induction mechanism in an outpatient setting and a mean extension of 32 mm (4 to 80) was achieved without anaesthesia. There were lengthening complications in two children: failed lengthening in one and the formation of scar tissue in the other. Deep infection developed in six patients (18%) and local recurrence in three. A total of 11 patients required further surgery to the leg. Amputation was necessary in five patients (20%) and a two-stage revision in another. There were no cases of loosening, but two patients had implant breakage and required revision. The mean Musculoskeletal Tumor Society functional score was 85% (60% to 100%) at last known follow-up. These early results demonstrate that the non-invasive extendible prosthesis allows successful lengthening without surgical intervention, but the high incidence of infection is a cause for concern.

Necrotising fasciitis is a rare but severe infection of soft-tissue associated with rapid progression, systemic toxicity and high mortality. Monomicrobial necrotising fasciitis caused by Pseudomonas aeruginosa is exceptionally uncommon with only 12 cases reported in the literature. We describe a fatal case with an atypical presentation in a patient following spinal decompression for a metastasis from prostate cancer.

A 66-year-old man presented with an infected resurfacing hip replacement in the immediate post-operative period following an uneventful transurethral resection of the prostate. Prophylactic antibiotics had been administered on induction of anaesthesia. The hip prosthesis had been inserted seven years previously and had been hitherto asymptomatic. The hip was washed out and microbiological examination identified Enterococcus faecalis as the infecting micro-organism.

Despite current recommendations, clinicians undertaking invasive procedures which can lead to bacteraemia in patients with prosthetic joint replacements should be aware of the risk of haematogenous seeding in such prostheses, which although low, has potentially disastrous consequences.

We report the long-term results of the management of neglected chronically infected total knee replacements with a two-stage re-implantation protocol. In 18 of 34 patients (53%) a resistant organism was isolated. All cases were treated by the same surgical team in a specialist centre and had a mean follow-up of 12.1 years (10 to 14). They were evaluated clinically and radiologically using the Knee Society Score (KSS) and the American Knee Society Roentgenographic scoring system, respectively. One patient died after eight years from an unrelated cause and two were lost to follow-up. Three patients (8.8%) developed a recurrent infection for which further surgery was required. The infection was eradicated successfully in 31 patients (91.1%). There was one case of aseptic loosening after 13 years. We found a significant improvement in the KSS at final follow-up (p < 0.001).

Endoprosthetic replacement of the proximal femur may be required to treat primary bone tumours or destructive metastases either with impending or established pathological fracture. Modular prostheses are available off the shelf and can be adapted to most reconstructive situations for this purpose. We have assessed the clinical and functional outcome of using the METS (Stanmore Implants Worldwide) modular tumour prosthesis to reconstruct the proximal femur in 100 consecutive patients between 2001 and 2006. We compared the results with the published series for patients managed with modular and custom-made endoprosthetic replacements for the same conditions.

There were 52 males and 48 females with a mean age of 56.3 years (16 to 84) and a mean follow-up of 24.6 months (0 to 60). In 65 patients the procedure was undertaken for metastases, in 25 for a primary bone tumour, and in ten for other malignant conditions. A total of 46 patients presented with a pathological fracture, and 19 presented with failed fixation of a previous pathological fracture. The overall patient survival was 63.6% at one year and 23.1% at five years, and was significantly better for patients with a primary bone tumour than for those with metastatic tumour (82.3% vs 53.3%, respectively at one year (p = 0.003)). There were six early dislocations of which five could be treated by closed reduction. No patient needed revision surgery for dislocation. Revision surgery was required by six (6%) patients, five for pain caused by acetabular wear and one for tumour progression. Amputation was needed in four patients for local recurrence or infection.

The estimated five-year implant survival with revision as the endpoint was 90.7%. The mean Toronto Extremity Salvage score was 61% (51% to 95%). The implant survival and complications resulting from the use of the modular system were comparable to the published series of both custom-made and other modular proximal femoral implants.

We conclude that at intermediate follow-up the modular tumour prosthesis for proximal femur replacement provides versatility, a low incidence of implant-related complications and acceptable function for patients with metastatic tumours, pathological fractures and failed fixation of the proximal femur. It also functions as well as a custom-made endoprosthetic replacement.

When using a staged approach to eradicate chronic infection after total hip replacement, systemic delivery of antibiotics after the first stage is often employed for an extended period of typically six weeks together with the use of an in situ antibiotic-eluting polymethylmethacrylate interval spacer. We report our multi-surgeon experience of 43 consecutive patients (44 hips) who received systemic vancomycin for two weeks in combination with a vancomycin- and gentamicin-eluting spacer system in the course of a two-stage revision procedure for deep infection with a median follow-up of 49 months (25 to 83).

The antibiotic-eluting articulating spacers fractured in six hips (13.9%) and dislocated in five patients (11.6%). Successful elimination of the infecting organisms occurred in 38 (92.7%) of 41 hips with three patients developing superinfection with a new organism.

We conclude that prolonged systemic antibiotic therapy may not be essential in the two-stage treatment of a total hip replacement for Gram-positive infection, provided that a high concentration of antibiotics is delivered locally using an antibiotic-eluting system.

While frequently discussed as a standard treatment for the management of an infected shoulder replacement, there is little information on the outcome of two-stage re-implantation.

We examined the outcome of 17 consecutive patients (19 shoulders) who were treated between 1995 and 2004 with a two-stage re-implantation for the treatment of a deep-infection after shoulder replacement. All 19 shoulders were followed for a minimum of two years or until the time of further revision surgery. The mean clinical follow-up was for 35 months (24 to 80). The mean radiological follow-up was 27 months (7 to 80). There were two excellent results, four satisfactory and 13 unsatisfactory. In 12 of the 19 shoulders (63%) infection was considered to be eradicated. The mean pain score improved from 4.2 (3 to 5 (out of 5)) to 1.8 (1 to 4). The mean elevation improved from 42° (0° to 140°) to 89° (0° to 165°), mean external rotation from 30° (0° to 90°) to 43° (0° to 90°), and mean internal rotation from the sacrum to L5. There were 14 complications.

Our study suggests that two-stage re-implantation for an infected shoulder replacement is associated with a high rate of unsatisfactory results, marginal success at eradicating infection and a high complication rate.

We welcome letters to the Editor concerning articles which have recently been published. Such letters will be subject to the usual stages of selection and editing; where appropriate the authors of the original article will be offered the opportunity to reply.

Letters should normally be under 300 words in length, double-spaced throughout, signed by all authors and fully referenced. The edited version will be returned for approval before publication.

Polymethylmethacrylate remains one of the most enduring materials in orthopaedic surgery. It has a central role in the success of total joint replacement and is also used in newer techniques such as percutaneous vertebroplasty and kyphoplasty.

This article describes the current uses and limitations of polymethylmethacrylate in orthopaedic surgery. It focuses on its mechanical and chemical properties and links these to its clinical performance. The behaviour of antibiotic-loaded bone cement are discussed, together with areas of research that are now shedding light upon the behaviour of this unique biomaterial.

Our aim was to review the efficacy of the wound vacuum-assisted closure (VAC) system in the treatment of deep infection after extensive instrumentation and fusion for spinal deformity in children and adolescents.

A total of 14 patients with early deep spinal infection were treated using this technique. Of these, 12 had neuromuscular or syndromic problems. Clinical and laboratory data were reviewed. The mean follow-up was 44 months (24 to 72). All wounds healed. Two patients required plastic surgery to speed up the process. In no patient was the hardware removed and there was no loss of correction or recurrent infection.

We believe that the wound VAC system is a useful tool in the armamentarium of the spinal surgeon dealing with patients susceptible to wound infections, especially those with neuromuscular diseases. It allows for the retention of the instrumentation and the maintenance of spinal correction. It is reliable and easy to use.

Diabetes mellitus is considered an indicator of poor prognosis for acute ankle fractures, but this risk may be specific to an identifiable subpopulation. We retrospectively reviewed 42 patients with both diabetes mellitus and an acute, closed, rotational ankle fracture. Patients were individually matched to controls by age, gender, fracture type, and surgical vs non-surgical treatment. Outcomes were major complications during the first six months of treatment. We contrasted secondarily 21 diabetic patients with and 21 without diabetic comorbidities. Diabetic patients and controls did not differ significantly in total complication rates. More diabetic patients required long-term bracing. Diabetic patients without comorbidities had complication rates equal to their controls. Diabetic patients with comorbidities had complications at a higher rate (ten patients; 47%) than matched controls (three patients; 14%, p = 0.034). A history of Charcot neuroarthropathy led to the highest rates of complication. An increased risk of complications in diabetic patients with closed rotational fractures of the ankle are specific to a subpopulation with identifiable related comorbidities.