Aims

To determine whether there is any difference in infection rate at 90 days between trauma operations performed in laminar flow and plenum ventilation, and whether infection risk is altered following the installation of laminar flow (LF).

The February 2015 Hip & Pelvis Roundup³⁶⁰ looks at: Hip arthroplasty in Down syndrome; Bulk femoral autograft successful in acetabular reconstruction; Arthroplasty follow-up: is the internet the solution?; Total hip arthroplasty following acetabular fracture; Salvage arthroplasty following failed hip internal fixation; Bone banking sensible financially and clinically; Allogenic blood transfusion in arthroplasty.

The leading indication for revision total hip arthroplasty (THA) remains aseptic loosening owing to wear. The younger, more active patients currently undergoing THA present unprecedented demands on the bearings. Ceramic-on-ceramic (CoC) bearings have consistently shown the lowest rates of wear. The recent advances, especially involving alumina/zirconia composite ceramic, have led to substantial improvements and good results in vitro.

Alumina/zirconia composite ceramics are extremely hard, scratch resistant and biocompatible. They offer a low co-efficient of friction and superior lubrication and lower rates of wear compared with other bearings. The major disadvantage is the risk of fracture of the ceramic. The new composite ceramic has reduced the risk of fracture of the femoral head to 0.002%. The risk of fracture of the liner is slightly higher (0.02%).

Assuming that the components are introduced without impingement, CoC bearings have major advantages over other bearings. Owing to the superior hardness, they produce less third body wear and are less vulnerable to intra-operative damage.

The improved tribology means that CoC bearings are an excellent choice for young, active patients requiring THA.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):14–17.

Aims

The goals of this study were to define the risk factors, characteristics, and chronology of fractures in 5417 revision total hip arthroplasties (THAs).

Aims

The long-term functional outcome of total hip arthroplasty (THA) performed by trainees is not known. A multicentre retrospective study of 879 THAs was undertaken to investigate any differences in outcome between those performed by trainee surgeons and consultants.

The ‘jumbo’ acetabular component is now commonly used in acetabular revision surgery where there is extensive bone loss. It offers high surface contact, permits weight bearing over a large area of the pelvis, the need for bone grafting is reduced and it is usually possible to restore centre of rotation of the hip. Disadvantages of its use include a technique in which bone structure may not be restored, a risk of excessive posterior bone loss during reaming, an obligation to employ screw fixation, limited bone ingrowth with late failure and high hip centre, leading to increased risk of dislocation. Contraindications include unaddressed pelvic dissociation, inability to implant the component with a rim fit, and an inability to achieve screw fixation. Use in acetabulae with < 50% bone stock has also been questioned. Published results have been encouraging in the first decade, with late failures predominantly because of polyethylene wear and aseptic loosening. Dislocation is the most common complication of jumbo acetabular revisions, with an incidence of approximately 10%, and often mandates revision. Based on published results, a hemispherical component with an enhanced porous coating, highly cross-linked polyethylene, and a large femoral head appears to represent the optimum tribology for jumbo acetabular revisions.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):64–7.

Objectives

The objective of this study was to determine if combining variations in mixing technique of antibiotic-impregnated polymethylmethacrylate (PMMA) cement with low frequency ultrasound (LFUS) improves antibiotic elution during the initial high phase (Phase I) and subsequent low phase (Phase II) while not diminishing mechanical strength.

Hip replacement is a very successful operation and the outcome is usually excellent. There are recognised complications that seem increasingly to give rise to litigation. This paper briefly examines some common scenarios where litigation may be pursued against hip surgeons. With appropriate record keeping, consenting and surgical care, the claim can be successfully defended if not avoided. We hope this short summary will help to highlight some common pitfalls. There is extensive literature available for detailed study.

Aims

Increasing demand for total hip and knee arthroplasty (THA/TKA) and associated follow-up has placed huge demands on orthopaedic services. Feasible follow-up mechanisms are therefore essential.

Objectives

T-cells are considered to play an important role in the inflammatory response causing arthroplasty failure. The study objectives were to investigate the composition and distribution of CD4+ T-cell phenotypes in the peripheral blood (PB) and synovial fluid (SF) of patients undergoing revision surgery for failed metal-on-metal (MoM) and metal-on-polyethylene (MoP) hip arthroplasties, and in patients awaiting total hip arthroplasty.

Periprosthetic joint infection (PJI) is a devastating complication for patients and results in greatly increased costs of care for both healthcare providers and patients. More than 15 500 revision hip and knee procedures were recorded in England, Wales and Northern Ireland in 2013, with infection accounting for 13% of revision hip and 23% of revision knee procedures.

We report our experience of using antibiotic eluting absorbable calcium sulphate beads in 15 patients (eight men and seven women with a mean age of 64.8 years; 41 to 83) as part of a treatment protocol for PJI in revision arthroplasty.

The mean follow-up was 16 months (12 to 22). We report the outcomes and complications, highlighting the risk of hypercalcaemia which occurred in three patients.

We recommend that serum levels of calcium be routinely sought following the implantation of absorbable calcium sulphate beads in orthopaedic surgery.

Cite this article: Bone Joint J 2015;97-B:1237–41.

The accurate reconstruction of hip anatomy and biomechanics is thought to be important in achieveing good clinical outcomes following total hip arthroplasty (THA). To this end some newer hip designs have introduced further modularity into the design of the femoral component such that neck­shaft angle and anteversion, which can be adjusted intra-operatively. The clinical effect of this increased modularity is unknown. We have investigated the changes in these anatomical parameters following conventional THA with a prosthesis of predetermined neck–shaft angle and assessed the effect of changes in the hip anatomy on clinical outcomes.

In total, 44 patients (mean age 65.3 years (standard deviation (sd) 7); 17 male/27 female; mean body mass index 26.9 (kg/m²) (sd 3.1)) underwent a pre- and post-operative three-dimensional CT scanning of the hip. The pre- and post-operative neck–shaft angle, offset, hip centre of rotation, femoral anteversion, and stem alignment were measured. Additionally, a functional assessment and pain score were evaluated before surgery and at one year post-operatively and related to the post-operative anatomical changes.

The mean pre-operative neck–shaft angle was significantly increased by 2.8° from 128° (sd 6.2; 119° to 147°) to 131° (sd 2.1; 127° to 136°) (p = 0.009). The mean pre-operative anteversion was 24.9° (sd 8; 7.9 to 39.1) and reduced to 7.4° (sd 7.3; -11.6° to 25.9°) post-operatively (p < 0.001). The post-operative changes had no influence on function and pain. Using a standard uncemented femoral component, high pre- and post-operative variability of femoral anteversion and neck–shaft angles was found with a significant decrease of the post-operative anteversion and slight increase of the neck–shaft angles, but without any impact on clinical outcome.

Cite this article: Bone Joint J 2015;97-B:1615–22.

The August 2015 Hip & Pelvis Roundup360 looks at: The well-fixed acetabular revision; Predicting complications in revision arthroplasty; Is infection associated with fixation?; Front or back? An enduring question in hip surgery; Muscle-sparing approaches?; Gabapentin as a post-operative analgesic adjunct; An Indian take on AVN of the hip; Weight loss and arthroplasty

If patients could recall their physical status before total hip (THA) or knee arthroplasty (TKA) accurately it could have valuable applications both clinically and for research. This study evaluated the accuracy of a patient’s recollection one year after either THA or TKA using the Oxford hip or knee scores (OHS and OKS). In total, 113 patients (59 THA, 54 TKA) who had completed the appropriate score pre-operatively were asked to complete the score again at a mean of 12.4 months (standard deviation (sd) 0.8) after surgery, recalling their pre-operative state.

While there were no significant differences between the actual and recalled pre-operative scores (OHS mean difference 0.8, sd 6.21, 95% confidence interval (CI) -0.82 to 2.42, p = 0.329; OKS mean difference -0.11, sd 7.34, 95% CI -2.11 to 1.89, p = 0.912), absolute differences were relatively large (OHS, 5.24; OKS, 5.41), correlation was weak (OHS r = 0.7, OKS r = 0.61) and agreement between actual and recalled responses for individual questions was poor in half of the OHS and two thirds of the OKS.

A patient’s recollection of pre-operative pain and function is inaccurate one year after THA or TKA.

Cite this article: Bone Joint J 2015;97-B:1070–5.

Oxidised zirconium (OxZi) has been developed as an alternative bearing surface for femoral heads in total hip arthroplasty (THA). This study has investigated polyethylene wear, functional outcomes and complications, comparing OxZi and cobalt–chrome (CoCr) as part of a three-arm, multicentre randomised controlled trial. Patients undergoing THA from four institutions were prospectively randomised into three groups. Group A received a CoCr femoral head and highly cross-linked polyethylene (XLPE) liner; Group B received an OxZi femoral head and XLPE liner; Group C received an OxZi femoral head and ultra-high molecular weight polyethylene (UHMWPE) liner. At five years, 368 patients had no statistically significant differences in short-form-36 (p = 0.176 mental, p = 0.756 physical), Western Ontario and McMaster Universities Osteoarthritis Index (p = 0.847), pain scores (p = 0.458) or complications. The mean rate of linear wear was 0.028 mm/year (standard deviation (sd) 0.010) for Group A, 0.023 mm/year (sd 0.010) for Group B, and 0.09 mm/year (sd 0.045) for Group C. Penetration was significantly higher in the UHMWPE liner group compared with both XLPE liner groups (p < 0.001) but no significant difference was noted between CoCr and OxZi when articulating with XLPE (p = 0.153). In this, the largest randomised study of this bearing surface, it appears that using a XLPE acetabular liner is more important in reducing THA component wear than the choice of femoral head bearing, at mid-term follow-up. There is a non-significant trend towards lower wear, coupling OxZi rather than CoCr with XLPE but long-term analysis is required to see if this observation changes with time and becomes significant.

Cite this article: Bone Joint J 2015;97-B:883–9.

There is no single standardised method of measuring the orientation of the acetabular component on plain radiographs after total hip arthroplasty. We assessed the reliability and accuracy of three methods of assessing anteversion of the acetabular component for 551 THAs using the PolyWare software and the methods of Liaw et al, and of Woo and Morrey. All measurements of the three methods had excellent intra- and inter-observer reliability. The values of the PolyWare software, which determines version of the acetabular component by edge detection were regarded as the reference standard. Although the PolyWare software and the method of Liaw et al were similarly precise, the method of Woo and Morrey was significantly less accurate (p < 0.001). The method of Liaw et al seemed to be more accurate than that of Woo and Morrey when compared with the measurements using the PolyWare software. If the qualified lateral radiograph was selected, anteversion measured using the method of Woo and Morrey was considered to be relatively reliable.

Cite this article: Bone Joint J 2015; 97-B:611–16.

We evaluated the accuracy with which a custom-made acetabular component could be positioned at revision arthroplasty of the hip in patients with a Paprosky type 3 acetabular defect.

A total of 16 patients with a Paprosky type 3 defect underwent revision surgery using a custom-made trabecular titanium implant. There were four men and 12 women with a median age of 67 years (48 to 79). The planned inclination (INCL), anteversion (AV), rotation and centre of rotation (COR) of the implant were compared with the post-operative position using CT scans.

A total of seven implants were malpositioned in one or more parameters: one with respect to INCL, three with respect to AV, four with respect to rotation and five with respect to the COR.

To the best of our knowledge, this is the first study in which CT data acquired for the pre-operative planning of a custom-made revision acetabular implant have been compared with CT data on the post-operative position. The results are encouraging.

Cite this article: Bone Joint J 2015; 97-B:780–5.

The purpose of this paper is to discuss the risk factors, prevention strategies, classification, and treatment of intra-operative femur fractures sustained during primary and revision total hip arthroplasty.

In this study we evaluated whether pre-operative Western Ontario and McMaster Universities (WOMAC) osteoarthritis scores can predict satisfaction following total hip arthroplasty (THA). Prospective data for a cohort of patients undergoing THA from two large academic centres were collected, and pre-operative and one-year post-operative WOMAC scores and a 25-point satisfaction questionnaire were obtained for 446 patients. Satisfaction scores were dichotomised into either improvement or deterioration. Scatter plots and Spearman’s rank correlation coefficient were used to describe the association between pre-operative WOMAC and one-year post-operative WOMAC scores and patient satisfaction. Satisfaction was compared using receiver operating characteristic (ROC) analysis against pre-operative, post-operative and δ WOMAC scores.

We found no relationship between pre-operative WOMAC scores and one-year post-operative WOMAC or satisfaction scores, with Spearman’s rank correlation coefficients of 0.16 and –0.05, respectively. The ROC analysis showed areas under the curve (AUC) of 0.54 (pre-operative WOMAC), 0.67 (post-operative WOMAC) and 0.43 (δ WOMAC), respectively, for an improvement in satisfaction.

We conclude that the pre-operative WOMAC score does not predict the post-operative WOMAC score or patient satisfaction after THA, and that WOMAC scores can therefore not be used to prioritise patient care.

Cite this article: Bone Joint J 2015;97-B:150–3.

We report the kinematic and early clinical results of a patient- and observer-blinded randomised controlled trial in which CT scans were used to compare potential impingement-free range of movement (ROM) and acetabular component cover between patients treated with either the navigated ‘femur-first’ total hip arthroplasty (THA) method (n = 66; male/female 29/37, mean age 62.5 years; 50 to 74) or conventional THA (n = 69; male/female 35/34, mean age 62.9 years; 50 to 75). The Hip Osteoarthritis Outcome Score, the Harris hip score, the Euro-Qol-5D and the Mancuso THA patient expectations score were assessed at six weeks, six months and one year after surgery. A total of 48 of the patients (84%) in the navigated ‘femur-first’ group and 43 (65%) in the conventional group reached all the desirable potential ROM boundaries without prosthetic impingement for activities of daily living (ADL) in flexion, extension, abduction, adduction and rotation (p = 0.016). Acetabular component cover and surface contact with the host bone were > 87% in both groups. There was a significant difference between the navigated and the conventional groups’ Harris hip scores six weeks after surgery (p = 0.010). There were no significant differences with respect to any clinical outcome at six months and one year of follow-up. The navigated ‘femur-first’ technique improves the potential ROM for ADL without prosthetic impingement, although there was no observed clinical difference between the two treatment groups.

Cite this article: Bone Joint J 2015; 97-B:890–8.