Objectives. Establishing the diagnosis of implant-associated infections is often difficult, because of variable clinical presentations and lack of uniform diagnostic criteria. Sonication of removed orthopedic devices was shown to have superior sensitivity and specificity for infection. We evaluated the value of microcalorimetry as a quick and reliable tool in the diagnosis of infection in sonication fluid from removed implants. Methods. Between 10/2009 and 02/2010 we prospectively included all removed orthopaedic devices at our institution, which were subjected to sonication. Periprosthetic tissue cultures were performed as standard procedure. The removed device was sonicated in Ringer solution (40 kHz, 1 minute) and the resulting fluid was cultured and centrifuged (3000 × g, 10 minutes). The resulting pellet was resuspended in 3 ml tryptic soy broth for isothermal microcalorimetry (sensitivity of 0.25 μW). The detection time until increase of 20 μW was calculated. A 48-channel batch calorimeter (TA Instruments, New Castle, DE, USA) was used to measure the heat flow at 37°C controlled at 0.0001 °C. Results. 39 cases were included (24 males, mean age ± SD was 63 ± 16 years). 29 cases were orthopedic prostheses (14 hip, 11 knee, 1 shoulder and 1 joint spacers) and 10 cases osteosynthetic materials (6 screws, 3 plates, 1 cement-nail). 13 cases (33%) were infected, of which 10 (77%) were positive in sonication culture and 12 (92%) in microcalorimetry. The mean detection time by microcalorimetry was 11.4 h (range, 0.2 h–20.9 h). Examples for microcalorimetric signals can be seen in Fig.1. Conclusions. Microcalorimety of sonication fluid showed superior sensitivity for the diagnosis of infection with detection time of <24 h. This method is a promising diagnostic assay for a rapid and accurate diagnosis of infections associated with orthopedic devices

MOXIMED KineSpring® Knee Implant System is an Orthopaedic device designed for younger or highly active patients with osteoarthritis. The device is placed under the skin, is attached to the tibia and femur, and contains springs which help limit some of the forces that are transmitted through the knee during activities such as walking or running and thereby relieve pain that may be experienced by patients with early arthritis of the knee. The aim of this study is to determine the long term safety and efficacy of the KineSpring knee implant system. This is a prospective case series involving two centres in Glasgow. 29 patients (mean age of 45.1 years and range 18-65 years) were recruited into the study between 2011 and 2016. The Primary outcome measure was Oxford knee score (OKS) at 2, 5 and 10 years post-operatively. Secondary outcome measures include device related complications and survival, patient reported functional outcome measures, patient satisfaction, pain levels and change in radiographic classification of osteoarthritis. At 2-year follow-up, 7 implants were removed (74.1% survival). Complications include deep infection, requiring removal in 1 patient, 2 implant failures requiring removal and one spring breakage. In comparison to pre-operative measures there was an improvement in the pain (3.58 vs. 5.20, p=0.02), stiffness (4.16 vs. 4.47, p=0.6) and OKS (32.4 vs. 36.9, p=0.03). The KineSpring improves overall pain, stiffness and functional outcome at 2 years following surgery, however there was a high rate of removal and further long-term follow up analysis is required regarding its effectiveness

Background. Approximately half of all hip fractures are displaced intracapsular fractures. The standard treatment for these fractures is either hemiarthroplasty or total hip arthroplasty. The recent National Institute for Health and Care Excellence (NICE) guidance on hip fracture management recommends the use of ‘proven’ cemented stem arthroplasty with an Orthopaedic Device Evaluation Panel (ODEP) rating of at least 3B (97% survival at three years). The Thompsons prosthesis is currently lacking an ODEP rating despite over 50 years of clinical use, likely due to the paucity of implant survival data. Nationally, adherence to these guidelines is varied as there is debate as to which prosthesis optimises patient outcomes. Design. This study design is a multi-centre, multi-surgeon, parallel, two arm, standard-of-care pragmatic randomised controlled trial. It will be embedded within the WHiTE Comprehensive Cohort Study (ISRCTN63982700). The main analysis is a two-way equivalence comparison between Hemi-Thompson and Hemi-Exeter polished taper with Unitrax head. Secondary outcomes will include radiological leg length discrepancy measured as per Bidwai and Willett, mortality, re-operation rate and indication for re-operation, length of index hospital stay and revision at four months. This study will be supplemented by the NHFD (National Hip Fracture Database) dataset. Discussion. Evidence on the optimum choice of prosthesis for hemiarthroplasty of the hip is lacking. National guidance is currently based on expert opinion rather than empirical evidence. The incidence of hip fracture is likely to continue to increase and providing high quality evidence on the optimum treatment will improve patient outcomes and have important health economic implications. Cite this article: A. L. Sims. The World Hip Trauma Evaluation Study 3: Hemiarthroplasty Evaluation by Multicentre Investigation – WH. I. TE 3: HEMI – An Abridged Protocol. Bone Joint Res 2016;5:18–25. doi: 10.1302/2046-3758.51.2000473

Introduction. The origins of the uncemented tapered wedge hip stem design currently offered by several orthopaedic device companies can be linked back to the cemented Straight Mueller type stem design first used in 1977. The design, a wedge shape with a taper angle of 6 degrees, maintains a single medial curvature for all sizes and increases laterally in the width to accommodate different size femurs. Although evolutionary improvements have been made over the years the basic body geometry of the stem has stayed mainly unchanged with excellent clinical survivorship. Over the past decade, the demographics of hip replacement have changed, with a large increase in younger male patients in the age range of 40 to 60 years. In this study the femoral fit of a novel tapered stem, designed to fit a wide array of patient types, is compared to a standard predicate tapered stem design. Methods. A bone morphology study was performed on a patient population of 556 patients using three dimensional digital data from CT-scans. To characterize the fit of the stem designs we analyzed the ratio of a distal (60mm below lesser trochanter) and a proximal (10mm above lesser trochanter) cross section. The same measurements were taken with the standard tapered stem design and the novel tapered stem design, with a given constant implantation height of 20mm above the lesser trochanter. The fit of the stems was classified as Type 1, where there was both proximal and distal engagement, Type 2, proximal engagement only, Type 3, distal engagement only. The distal and proximal engagement, Type 1, was specified with a maximum engagement difference of 2mm proximal to distal. Results. The standard tapered stem showed a well balanced distal to proximal ratio in the median sizes. However, with increasing stem size the distal engagement increases. The novel tapered stem design showed a well balanced proximal to distal ratio throughout the complete size range. With respect to Type 3 fit classification the novel tapered stem design showed a reduced percentage of distal engagements (2.8%) compared to the predicate standard stem (17.2%). In the 40 to 60 year old male group the distal engagements for the standard stem increases (28.2%), whereas the distal engagements for the novel stem remains unchanged (1.3%). Discussion. The cementless, tapered wedge stem design is used in large numbers globally due to its ease of use and reproducibility. However, changing patient demographics and associated bone morphology represents a challenge for existing designs to achieve a proximal fit. The novel tapered stem design presented here was adapted to these influencing factors by optimizing the proximal to distal ratio with respect to the whole patient group resulting in a particularly marked improvement in proximal fit in the male 40–60 age group compared to predicate stem designs

Aims

The aim of this study was to perform the first population-based description of the epidemiological and health economic burden of fracture-related infection (FRI).

Aims

This study aimed to compare the change in health-related quality of life of patients receiving a traditional cemented monoblock Thompson hemiarthroplasty compared with a modern cemented modular polished-taper stemmed hemiarthroplasty for displaced intracapsular hip fractures.

We report the outcome of 84 nonunions involving long bones which were treated with rhBMP-7, in 84 patients (60 men: 24 women) with a mean age 46 years (18 to 81) between 2003 and 2011. The patients had undergone a mean of three previous operations (one to 11) for nonunion which had been present for a mean of 17 months (4 months to 20 years). The nonunions involved the lower limb in 71 patients and the remainder involved the upper limb. A total of 30 nonunions were septic. Treatment was considered successful when the nonunion healed without additional procedures. The relationship between successful union and the time to union was investigated and various factors including age and gender, the nature of the nonunion (location, size, type, chronicity, previous procedures, infection, the condition of the soft tissues) and type of index procedure (revision of fixation, type of graft, amount of rhBMP-7) were analysed. The improvement of the patients’ quality of life was estimated using the Short Form (SF) 12 score.

A total of 68 nonunions (80.9%) healed with no need for further procedures at a mean of 5.4 months (3 to 10) post-operatively. Multivariate logistic regression analysis of the factors affecting union suggested that only infection significantly affected the rate of union (p = 0.004).Time to union was only affected by the number of previous failed procedures (p = 0.006). An improvement of 79% and 32.2% in SF-12 physical and mental score, respectively, was noted within the first post-operative year.

Rh-BMP-7 combined with bone grafts, enabled healing of the nonunion and improved quality of life in about 80% of patients. Aseptic nonunions were much more likely to unite than septic ones. The number of previous failed operations significantly delayed the time to union.

Cite this article: Bone Joint J 2015;97-B:997–1003.