Dislocation following revision THA remains a leading cause of failure. Integrity of the abductor muscles is a major contributor to stability. Large diameter heads (LDH), Dual Mobility (DM) and Constrained Acetabular Liners (CAL) are enhanced stability options but the indication for these choices remains unclear.

We assessed an algorithm based on Gluteus Medius (GM) deficiency to determine bearing selection. Default choice with no GM damage was a LDH. GM deficiency with posterior muscle intact received DM and CAL for GM complete deficiency with loss of posterior muscle.

Consecutive revision THA series followed to determine dislocation, all-cause re-revision and Oxford Hip Score (OHS).

311 revision THA with mean age 70 years (32–95). At a mean follow-up of 4.8 years overall dislocation rate 4.1% (95%CI 2.4–7.0) and survivorship free of re-revision 94.2% (95%CI 96.3–91.0). Outcomes:

Group 1 - LDH (36 & 40mm) n=164 / 4 dislocations / 7 re-revisions

Group 2 - DM n=73 / 3 dislocations / 4 re-revisions

Group 3 - CAL n=58 / 5 dislocations / 7 re-revisions

Group 4 - Other (28 & 32mm) n=16 / 1 dislocation / no re-revisions

Mean pre-op OHS: 19.6 (2–47) and mean post-op OHS: 33.9 (4–48). Kaplan-Meier analysis at 60 months dislocation-free survival was 96.1% (95% CI: 93.0–97.8). There was no difference between survival distributions comparing bearing choice (p=0.46).

Decision making tools to guide selection are limited and in addition soft tissue deficiency has been poorly defined. The posterior vertical fibres of GM have the greatest lateral stabiliser effect on the hip. The algorithm we have used clearly defined indication & implant selection. We believe our outcomes support the use of an enhanced stability bearing selection algorithm.

Dual mobility (DM) is an established bearing option in Total Hip Arthroplasty (THA). The traditional mono-block DM designs have limited ability for additional fixation, whereas the modular DM designs allow additional screw fixation but limit internal diameter and have the potential to generate metal debris. We report the early results of a CoCrMo alloy mono-block implant manufactured by additive technology with a highly porous ingrowth surface to enhance primary fixation and osseointegration.

Prospective follow-up of the Duplex^TM implant first inserted in March 2016 enrolled into Beyond Compliance (BC). Primary outcome measure was all-cause revision and secondary outcomes dislocation, peri-prosthetic fracture (PPF) and Oxford Hip Score (OHS). Patients were risk stratified and all considered to be high risk for instability. Complications were identified via hospital records, clinical coding linkage using national database and via BC website.

159 implants in 154 patients with a mean age 74.0 years and a maximum F/U of 7 years. Survivorship for all-cause revision 99.4% (95% CI 96.2–99.8). One femoral only revision. Mean gain in OHS 27.4. Dislocation rate 0.6% with a single event. Patients with a cemented Polished taper stem (PTS) had a Type B PPF rate of 2.1% requiring revision/fixation. Compared to conventional THA this cohort was significantly older (74.0 vs 68.3 years), more co-morbidity (ASA 3 46.5% vs 14.4%) and more non-OA indications (32.4% vs 8.5%). Every patient had at least one risk factor for falling and >50% of cohort had 4 or more risk factors using NICE tool.

We believe our results demonstrate that risk stratification successfully aids implant selection to prevent dislocation in high-risk patients. This novel design has provided excellent early results in a challenging cohort where individuals are very different to the “average” THA patient. NJR data on DM has reported an increase in revision for PPF. A “perfect storm” maybe created using DM in high-risk falls risk population. This re-enforces the need to consider all patient and implant factors when deciding bearing selection.

Contemporary acetabular reconstruction in major acetabular bone loss often involves the use of porous metal augments, a cup-cage construct or custom implant. The aims of this study were: To determine the reproducibility of a reconstruction algorithm in major acetabular bone loss. To determine the subsequent success of reconstruction performed in terms of re-operation, all-cause revision and Oxford Hip Score (OHS) and to further define the indications for custom implants in major acetabular bone loss.

Consecutive series of Paprosky Type III defects treated according to a reconstruction algorithm. IIIA defects were planned to use a superior augment and hemispherical cup.

IIIB defects were planned to receive either augment and cup, cup-cage or custom implant.

105 procedures in cohort 100 patients (5 bilateral) with mean age 73 years (42–94).

IIIA defects (50 cases) − 72.0% (95%CI 57.6–82.1) required a porous metal augment the remainder treated with a hemispherical cup alone. IIIB defects (55 cases) 71.7% (95%CI 57.6–82.1) required either augments or cup-cage. 20 patients required a hemispherical cup alone and 6 patients received a custom-made implant.

Mean follow up of 7.6 years. 6 re-revisions were required (4 PJI, 2 peri-prosthetic fractures & 1 recurrent instability) with overall survivorship of 94.3% (95% CI 97.4–88.1) for all cause revision. Single event dislocations occurred in 3 other patients so overall dislocation rate 3.8%. Mean pre-op OHS 13.8 and mean follow-up OHS 29.8.

Custom implants were used in: Mega-defects where AP diameter >80mm, complex discontinuity and massive bone loss in a small pelvis (i.e., unable to perform cup-cage)

A reconstruction algorithm can >70% successfully predict revision construct which thereafter is durable with a low risk of re-operation. Jumbo cup utilized <1/3 of cases when morphology allowed. The use of custom implants has been well defined in this series and accounts for <5% of cases.

Aims

This study evaluates risk factors influencing fracture characteristics for postoperative periprosthetic femoral fractures (PFFs) around cemented stems in total hip arthroplasty.

Dislocation and instability remain leading cause of failure following THA. We present a single-surgeon 10-year experience with use of Dual Mobility (DM) bearings in Primary and Revision THA using posterior approach.

127 DM bearings were implanted between September 2006 – September 2016; 102 in high-risk primary THA's and 25 revision THA's for either treatment or prevention of instability. Selection for DM bearing followed individual patient risk assessment. Criteria for use of DM bearing were presence of multiple risk factors.

Mean age was 72.9 years. 100 Mono-block DM implants, 22 Modular DM implants and 5 custom-made DM devices were implanted. Revision cohort included those used in conjunction with a cage or porous metal augments. 2 dislocations (1.6%) were observed, both in the Revision group, 1 was recurrent requiring revision to constrained liner. Primary group had 2 revisions; 1 peri-prosthetic fracture and 1 deep infection. No DM bearing specific complications were observed. A constructed life table calculated survival function with endpoint set as revision for any reason demonstrated a cumulative survival of 94% at 7.4 years.

In high-risk patients, DM bearings are successful at preventing and treating dislocation in THA. Primary cohort in this study all had multiple risk factors for instability but no dislocations or bearing specific complications were observed. Dislocations observed in Revision group were associated with major soft tissue deficiency.

This study adds to the promising results already reported with DM THA articulations and should be considered for patients at risk of dislocation or instability.

Runner Up – Best Paper Award

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.

Introduction

The Corail stem is a fully HA coated tapered implant that has demonstrated long-term success. On the NJR it has become one of the most commonly used implants in the UK. The aim of our study was to document our experience of the revision of this implant together highlighting some important technical considerations.

Objectives: To ascertain the frequency and causes of both re-admissions and re-visits (i.e. those not requiring overnight stay) to the hospital following primary and revision TKRs.

Methods: All TKRs performed between April 2007 and March 2008 were included in the study. Mean follow-up period was 9 months (range 3–15 months). Patient data was accessed via computerized patient information systems giving access to the details of inpatient admissions, A& E attendances, laboratory results, radiology reports and clinic letters. Pattern of re-hospitalisation with regards to the cause and time period post-surgery was recorded as well.

Results: Total number of primary TKRs performed in the year was 839 and the re-admission and re-visit rates were 8.22% and 4.17% respectively. The overall re-hospitalisation rate was 12.4%. Most common causes for readmission were pain/stiffness requiring MUA (1.67%) and superficial infections (1.55%). Majority of the revisits were for continuing joint pain (1.67%) and suspected DVT.

Total number of revision TKRs was 136 with a readmission and re-visit rate of 9.7% and 1.49% respectively. The total re-hospitalisation rate was 11.19%. Deep Infections were a prominent cause of readmission (4.4%).

Discussion: Around half (49.5%) of re-hospitalisations were seen in an Orthopaedic setting, the remainder presented to A& E (19.23%), Medical Assessment Units (16.35%) or General Medical Wards (7.7%). Following a primary TKR DVT/PE rates were less than 1% (0.83%). A vast majority (48.6%) of all re-admissions however, occurred within 28 days of discharge. The tradition of seeing patients for the first time in clinic postoperatively after 6–12 weeks may not be appropriate if the majority of re-admissions occur within 28 days.

Conclusion: Idiopathic joint pain and early infections are a major cause of re-hospitalisation. Re-scheduling the first follow-up appointment within the first month after a joint replacement can decrease the overall re-hospitalisation rates and also decrease the impact of these patients on other departments.

144 total hip replacements were performed by Swedish Orthopaedic Surgeons at Weston NHS Treatment Centre between 2004–2006, in an attempt to reduce the waiting list in Cardiff. Following concerns regarding the outcome of knee arthroplasty patients, the Welsh Assembly funded a clinical and radiographic review of all hip arthroplasty patients from the same unit.

100 hips were reviewed at a mean follow-up of 24 months. The mean Oxford Hip Score was 30 (range 12–60).

Radiolucencies were seen in acetabular zone 1 in 34, and all 3 zones in 28 hips. Femoral component position was > 4 degrees varus in 41 cases. Medial floor breach with intrapelvic cement was seen in 12 cases. 10 cases had > 1cm leg length discrepancy. There were 3 early dislocations, 1 intraoperative distal femoral fracture, 1 Pulmonary Embolus and 2 superficial infections.

4 patients have received further treatment so far, and 12 have been listed for acetabular component revision for loosening. 1 has been listed for stem revision for symptomatic leg length discrepancy of 2.5cm.

There is an unacceptably high early failure rate in this group of patients. The cost of further investigation and revision surgery far outweighs cost-savings achieved by outsourcing treatment to a distant centre.

Introduction: We report our experience with the ZMR Hip System (Zimmer Inc.). The system accommodates a number of femoral fixation philosophies including spline, porous and taper stem options. The tapered stem is designed to achieve a distal wedge fit and also allow bone on-growth via the corundumized titanium alloy surface. The modular mid-stem junction allows a selection of body designs to be selected providing significant intra-operative flexibility and version adjustment.

Method: This study considers 64 cases performed in 63 patients with a mean age at the time of surgery of 70 years (range 55–89) utilising the taper stem design. The indication for revision surgery was aseptic loosening in 33 patients (Paprosky types II – 12, IIIA-10, IIIB-11) 22 peri-prosthetic fractures (Vancouver types B2-15, B3-7), 8 for infection and 4 patients with instability.

Results: The cohort had a minimum three-year follow-up with a mean of 50 months (range 36–72) and clinical assessment included Oxford score and thigh pain assessment. Engh’s criteria was utilised in the radiological evaluation when considering femoral component fixation. Femoral stem subsidence and femoral bone stock were also appraised on serial follow-up radiographs.

Discussion: The survival rate at follow-up with stem revision being the end point was 100%. When re-operation for any reason and radiological loosing are considered as the end point the survival rate was 95%.

Conclusion: We conclude excellent medium term results with the use of a cementless modular taper stem in challenging femoral revision surgery.

The use of exhaust suit systems is commonplace in arthroplasty surgery where isolation of the surgical team is desirable in an attempt to reduce the risk of infection transmission. Elevated carbon dioxide levels have been reported in the non-clinical setting with such systems the consequences of which can include fatigue, diaphoresis, nausea, headache and irritability.

The aim of our study was to determine the levels of carbon dioxide present within an exhaust suit system during hip arthroplasty and to compare these with the recommended occupational exposure limit levels published by the Health and Safety Executive (HSE).

Data was collected during ten primary hip replacements performed by the same surgeon whilst wearing the Stryker Steri-Shield Helmet Exhaust System. This is a self-contained unit with an integrated blower used in conjunction with a full-length gown. In addition the helmet was fitted with an air-sampling probe connected to a portable infrared CO₂ monitor and also a temperature probe. Thus continuous monitoring of both CO₂ and temperature level during surgery was possible.

The mean initial CO₂ concentration in the helmet at the beginning of surgery was 3000 parts per million (ppm) and the mean maximum CO₂ level recorded was 13,000 ppm. The mean time the surgeon was within an exhaust suit to perform a primary hip replacement was 1 hr 54 mins and for 86% of this time period the CO₂ level within the helmet exceeded the recommended level of 5000 ppm as stipulated by the HSE.

In conclusion we have demonstrated significantly elevated CO₂ levels within the Stryker Steri-shield Exhaust Suit System during hip surgery. Surgeons who use this system should be aware of this together with the physical symptoms that may result.