Abstract

This study reports the ten-year polyethylene liner wear rates, incidence of osteolysis, clinical outcomes and complications of a three-arm, multicentre randomised controlled trial comparing Cobalt-Chrome (CoCr) and Oxidised Zirconium (OxZr) femoral heads with ultra-high molecular weight polyethylene (UHMWPE) versus highly cross-linked polyethylene (XLPE) liners in total hip arthroplasty (THA).

Patients undergoing THA from four institutions were prospectively randomised into three groups. Group A received a CoCr femoral head and XLPE liner; Group B received an OxZr femoral head and XLPE liner; and Group C received an OxZr femoral head and UHMWPE liner. Blinded observers recorded predefined outcomes in 262 study patients at regular intervals for ten years following THA.

At ten years follow-up, increased linear wear rates were recorded in group C compared to group A (0.133 ± 0.21 mm/yr vs 0.031 ± 0.07 mm/yr respectively, p<0.001) and group B (0.133 ± 0.21 mm/yr vs 0.022 ± 0.05 mm/yr respectively, p<0.001). Patients in group C were associated with increased risk of osteolysis and aseptic loosening requiring revision surgery compared with group A (7/133 vs 0/133 respectively, p=0.007) and group B (7/133 vs 0/135 respectively, p=0.007). There was a non-significant trend towards increased liner wear rates in group A compared to group B (0.031 ± 0.07 mm/yr vs 0.022 ± 0.05 mm/yr respectively, p=0.128). All three groups were statistically comparable preoperatively and at ten years follow-up when measuring normalised Western Ontario and McMaster Universities Osteoarthritis Index(p=0.410), short-form-36 (p = 0.465 mental, p = 0.713 physical), and pain scale scores (p=0.451).

The use of UHMWPE was associated with progressively increased annual liner wear rates after THA. At ten years follow-up, this translated to UHMWPE leading to an increased incidence of osteolysis and aseptic loosening requiring revision THA, compared with XLPE. Femoral heads composed of OxZr were associated with a non-significant trend towards reduced wear rates compared to CoCr, but this did not translate to any differences in osteolysis, functional outcomes, or revision surgery between the two treatments groups.

This study reports the ten-year outcomes of a three-arm, multicentre randomised controlled trial comparing Cobalt-Chrome (CoCr) and Oxidised Zirconium (OxZr) femoral heads with ultra-high molecular weight polyethylene (UHMWPE) versus highly cross-linked polyethylene (XLPE) liners in total hip arthroplasty (THA).

Patients undergoing THA from four institutions were prospectively randomised into three groups. Group A received a CoCr femoral head and XLPE liner; Group B received an OxZr femoral head and XLPE liner; and Group C received an OxZr femoral head and UHMWPE liner. The outcomes of 262 study patients were analysed at ten years follow-up.

At ten years, increased linear wear rates were recorded in group C compared to group A (0.133 ± 0.21 mm/yr vs 0.031 ± 0.07 mm/yr respectively, p<0.001) and group B (0.133 ± 0.21 mm/yr vs 0.022 ± 0.05 mm/yr respectively, p<0.001). Patients in group C had increased risk of osteolysis and aseptic loosening requiring revision surgery compared with group A (7/133 vs 0/133 respectively, p=0.007) and group B (7/133 vs 0/135 respectively, p=0.007). There was a non- significant trend towards increased liner wear rates in group A compared to group B (0.031 ± 0.07 mm/yr vs 0.022 ± 0.05 mm/yr respectively, p=0.128). All three groups were statistically comparable preoperatively and at ten years follow-up from a clinical score perspective.

The use of UHMWPE was associated with progressively increased annual liner wear rates. At ten years follow-up, this translated to an increased incidence of osteolysis and aseptic loosening requiring revision, compared with XLPE. Femoral heads composed of OxZr were associated with a non-significant trend towards reduced wear rates compared to CoCr, but this did not translate to any differences in osteolysis, functional outcomes, or revision surgery between the two treatments groups.

Cemented total hip replacement (THR) provides excellent outcomes and is cost-effective. Polished taper-slip (PTS) stems demonstrate successful results and have overtaken traditional composite-beam (CB) stems. Recent reports indicate they are associated with a higher risk of postoperative periprosthetic femoral fracture (PFF) compared to CB stems. This study evaluates risk factors influencing fracture characteristics around PTS and CB cemented stems.

Data were collected for 584 PFF patients admitted to eight UK centres from 25/05/2006-01/03/2020. Radiographs were assessed for Unified Classification System (UCS) grade and Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) type. Statistical comparisons investigated relationships by age, gender, and stem fixation philosophy (PTS versus CB). The effect of multiple variables was estimated using multinomial logistic regression to estimate odds ratios (OR) with 95% confidence intervals (CI).

Median (IQR) age was 79.1 (72.0–86.0) years, 312 (53.6%) patients were female, and 495 (85.1%) stems were PTS. The commonest UCS grade was type B1 (278, 47.6%). The commonest AO/OTA type was spiral (352, 60.3%). Metaphyseal-split fractures occurred only with PTS stems with an incidence of 10.1%. Male gender was associated with a five-fold reduction in odds of a type C fracture (OR 0.22, 95% CI 0.12 to 0.41, p<0.001) compared to a type B fracture. CB stems were associated with significantly increased odds of transverse fracture (OR 9.51, 95% CI 3.72 to 24.34, p <0.001) and wedge fracture (OR 3.72, 95% CI 1.16 to 11.95, p <0.05) compared to PTS stems.

This is the largest study investigating PFF characteristics around cemented stems. The commonest fracture types are B1 and spiral fractures. PTS stems are exclusively associated with metaphyseal-split fractures, but their incidence is low. Males have lower odds of UCS grade C fractures compared to females. CB stems had higher odds of bending type fractures (transverse and wedge) compared to PTS stems. Biomechanical testing is needed for validation and investigation of modifiable factors which may reduce the risk of unstable fracture patterns requiring complex revision surgery over internal fixation.

Aims

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

Background

In a number of disciplines, positive correlations have been reported between volume and clinical outcome. This has helped drive the evolution of specialist centres to deal with complex or high risk medical conditions. Hip fractures are a common injury associated with high morbidity and mortality.

Introduction

Open and arthroscopic hip debridement may be used for treatment of femoral acetabular impingement (FAI). There is a paucity of evidence regarding the efficacy of one over the other.

Introduction

Open hip debridement surgery has been used for treatment of femoral acetabular impingement pain for over ten years in our unit. While literature has reported promising short-term outcomes, longer term outcomes are more sparsely reported.

Hip fracture is a common injury with a high associated mortality. Many recommendations regarding timing of operative intervention exist for patients with such injuries. The Best Practice Tariff was introduced in England and Wales in 2010, offering financial incentives for surgery undertaken within 36 hours of admission. The England and Wales National Institute for Health and Clinical Excellence (NICE) Guidance states that surgery should be performed on the day or day after admission. Due to lack of clear evidence, this recommendation is based on Humanitarian grounds. NICE have called for further research into the effect of surgical timing on mortality.

We utilised data from the National Hip Fracture database prospectively collected between 2007 and 2015, comprising 413,063 hip fractures. Using 11 variables, both Cox and Logistic regression analysis was used to establish the effect on mortality of each 12 hour interval from admission to surgery.

For each 12 hour time frame from admission to surgery a trend for improved 30 day survival was demonstrated the earlier the surgery was performed. However, this did not reach significance until beyond 48 hours (Hazard ratio of 1.12, 95% CI: 1.04–1.20). Surgery after 48 hours suffered significantly higher chance of mortality compared to surgery done within 12 hours.

This is the largest analysis undertaken to date. Lowest mortality rates are found within the 0–12 hour window. After 48 hours there is a significant increased risk of mortality compared to the 0–12 hour time frame. As such, expeditious surgery within 48 hours can be justified both on humanitarian and survivorship grounds.

Hip fracture surgery performed within 48 hours is associated with reduced mortality when compared to that beyond this time. This is in agreement with Blue Book recommendations and extends the currently recommended NICE and Best Practice Tariff targets of 36 hours.

Introduction

Open hip debridement surgery has been used for treatment of femoral acetabular impingement pain for over ten years in our unit. While literature has reported promising short term outcomes, longer term outcomes are more sparsely reported. We aim to assess survivorship and functional outcome at ten years, in patients who have undergone open hip debridement.

Introduction

Incidence of adverse soft tissue reaction following metal on metal hip has a reported incidence of up to 48%. The current imaging modality of choice is metal artefact reduction sequence (MARS) MRI. Consensus is that large, symptomatic pseudotumours should be treated surgically, changing the bearing surfaces to other materials. There is debate as to how asymptomatic pseudotumours should be monitored and managed.

Routine postoperative radiographs following hip hemiarthroplasty are commonly undertaken despite it being suggested that they can cause delays to discharge, discomfort to patients and unnecessary radiation. Our study considered the necessity of these post-operative radiographs.

A retrospective search was conducted of all hemiarthroplasty procedures on the Royal Cornwall Hospital database. These were reviewed for cases where re-operation was conducted within 6 weeks. Notes and post-operative check radiographs of those who underwent re-operation were reviewed to determine how essential radiographs were in diagnosing complications requiring re-operations.

A total of 1557 hemiarthroplasty operations were identified. There were 37 incidences of re-operation within 6 weeks. 29 cases had normal check radiographs. 8 dislocations were picked up on post-operative radiographs. In all but one of these cases, clinical suspicion of complication had been raised prior to the radiograph. In the remaining case documentation was poor and no firm conclusion as to clinical suspicion could be drawn.

Our review of over 1500 hemiarthroplasty cases, demonstrated one incident where the check radiograph solely diagnosed an abnormality needing intervention that might not have been apparent clinically. We thus suggest that check radiographs following hip hemiarthroplasty should not be routinely ordered for all patients.

Introduction

In Total Hip Arthroplasty (THA), polyethylene wear reduction is key to implant longevity. Oxidized Zirconium (OxZi) unites properties of a ceramic bearing surface and metal head, producing less wear in comparison to standard Cobalt-Chromium (CoCr) when articulating with Cross-linked polyethylene (XLPE) in vitro. This study investigates in vivo polyethylene (PE) wear, outcomes and complications for these two bearing couples in patients at 5 year follow-up

Background and Purpose

Serum lactate has been shown to be an indicator of adverse clinical outcomes in patients admitted secondary to general trauma or sepsis. We retrospectively investigated whether admission serum venous lactate can predict in-hospital mortality in patients with hip fractures.

Introduction

Motion analysis is a validated method of assessing technical dexterity within surgical skills centers. A more accessible and cost-effective method of skills assessment is to use a global rating scale (GRS). We aimed to perform a validation experiment to compare an arthroscopic GRS against motion analysis for monitoring orthopaedic trainees learning simulated arthroscopic meniscal repairs.

Large studies have reported high dislocation rates (7 to 24%) following revision total hip arthroplasty (THA), particularly when the revision is undertaken in the presence of pre-existing instability. We retrospectively reviewed the clinical and radiographic outcome of 155 consecutive revision THA's that had been performed using an unconstrained dual-mobility acetabular implant. It features a mobile polyethylene liner articulating with both the prosthesis head and a metal acetabular cup, such that the liner acts as the femoral head in extreme positions. It can be implanted in either a press fit or cemented manner. Mean follow-up was 40 months (18–66) and average age 77 (42–89). Uncemented (n=122) and cemented (n=33) implants with a reinforcing cage, were used. Indications were aseptic loosening (n=113), recurrent instability (n=29), periprosthetic fracture (n=11) and sepsis (n=2). Three of the 155 cases (1.9%) dislocated within 6 weeks of surgery and were successfully managed with closed reduction. The 3 dislocations occurred in the groups revised for recurrent dislocation and periprosthetic fracture. There were no cases of recurrent dislocation and no revisions for implant failure. Despite a pantheon of options available, post-operative dislocation remains a challenge especially in patients with risk factors for instability. The use of large diameter heads is proven to improve stability but there are concerns regarding wear rates, metal toxicity and recurrent dislocation in the presence of abductor dysfunction. With constrained liners there are concerns regarding device failure and aseptic loosening due to implant overload. Our dislocation rates of 1.9% and survivorship to date compare favourably with alternative techniques and are also in line with studies from France using implants of a similar design. In our hands, where there are risk factors for dislocation, the use of a dual-mobility implant has been very effective at both restoring and maintaining stability in patients undergoing revision THA.

Background: Our multi-centre international randomized controlled trial compared the one-year incidence of dislocation between a 36 mm and 28 mm metal on highly cross-linked polyethylene articulation in primary and revision total hip replacement (THR).

Patients: 644 patients were entered into the study. Surgical approach was posterior in primary THR and posterior, transfemoral or transtrochanteric in revision THR. Patients were stratified according to a number of factors which may influence dislocation risk and polyethylene wear. Patients were randomized intra-operatively to either a 28 or 36 mm articulation.

Results: The 12-month incidence of dislocation was statistically significantly lower in patients undergoing THR with a 36 mm articulation than in those with a 28 mm articulation (1.3% vs 5.4%, p=.004). When primary and revision THR were examined separately, the 12-month incidence of dislocation was statistically significantly lower in patients undergoing primary THR with a 36 mm articulation than in those with a 28 mm articulation (0.8% vs 4.4%, p=.007). Of the 12 primary THR patients with a 28 mm articulation who dislocated within one year, four experienced recurrent dislocation and two were revised for dislocation. Two patients with a 36 mm articulation dislocated, one of whom experienced recurrent dislocation and was revised. The incidence of dislocation after revision THR with a 36 mm articulation was 4.9%, compared to 12.2% with a 28 mm articulation. Three of the five patients who dislocated following revision THR with a 28 mm articulation experienced recurrent dislocation and were revised within one year of surgery. Two patients dislocated following revision THR with a 36 mm articulation but neither experienced recurrent dislocation or further revision.

This large randomized study unequivocally shows for the first time that, compared to a 28 mm articulation, a 36 mm articulation in THR is efficacious in reducing the incidence of dislocation in the first year following THR.

In revision of cemented femoral components, removal of cement can be challenging. This study evaluates the use of an ultrasonic device (OSCAR, Orthosonics Ltd UK) for cement removal.

30 consecutive patients that attended our outpatients\’ clinic between May 2008 and September 2008, who underwent revision THR by the senior author or his fellows, were retrospectively reviewed. Minimum follow up was 12 months (average 34.9 months).Indications were aseptic loosening and recurrent dislocation. A posterolateral approach was used routinely. Cement was removed with osteotomes and OSCAR. An uncemented modular femoral component was used. At follow-up, radiographs were evaluated for the evidence of extended trochanteric osteotomy (ETO), fracture, cortical perforation, component loosening, migration, and adequacy of cement removal.

None of the cases required an ETO or cortical windowing. In 5 cases prophylactic cabling of the proximal femur was performed. There was one intraoperative femoral shaft fracture (3.33%). There was incomplete cement removal in 7 cases. There was no cortical perforation and no postoperative fracture. There was no case with loosening or migration of the implant.

In all cases that OSCAR was used ETO and cortical windowing were avoided. At an average 34.9 month follow up there was no evidence of thermal tissue damage. In the cases that cement was retained in the canal, this did not affect the stability of the implant. The fracture and the incomplete cement removal were in cases performed by a fellow illustrating the learning curve of the technique.

Aim: To evaluate the possible increase to surgical/operating room capacity by increasing the percentage of uncemented total hip replacement

Introduction: Globally there is growing demand for increased efficiency and productivity from medical care. In hip arthroplasty there has been increased interest in the use of uncemented components with several studies and registry data showing them to perform well clinically 1, 2. One concern with their increased use has been increased costs 3. We have examined the issue of operative timing and discuss the possible role these components may have in increasing theatre utilisation times and so offsetting their cost.

Methods: This was a prospective, cohort study of every hip replacement performed in a dedicated arthroplasty unit within a district general hospital over one year. All care of patients was standardised using pathways, including all surgeons using a posterior approach with posterior repair. This allowed us to determine the relative effect of prosthesis type on quality, safety and efficiency. Demographic, anaesthetic, operative and timing details on all cases performed were collected prospectively and independently of the surgical team. Patients were reviewed at six weeks and one year post op. All readmissions to any hospital were noted and any further surgery recorded.

Results: There were 1248 cases performed in one year. Of these 194 were uncemented (both components) and 286 cemented total hip replacements. Patient demographics were similar (mean age 70.9 years, range 28–92). Both hip types showed no difference in quality or safety factors as assessed by hip scores, patient mobilisation times, complication rates or revision rates. The only difference was in the surgical times. These were (in minutes):

– Mean Standard Deviation Minimum Maximum

(*p< 0.0005)

Conclusions: Our data demonstrates an average time saving of 17 minutes per case performed. If, over the next year, we converted to all uncemented hips we would release 136 hours of operative time, giving an opportunity to get 100 more cases done. This represents a 20% increase in productivity with no compromise to safety or quality.

Early revision is an important risk factor for repeated revision and poor results after primary total hip replacement and instability is a major cause of early revision. Larger articulations with cross-linked polyethylene are proposed as a solution, but these are not without risk, including fracture of the thin polyethylene rim of the liner. The aim of our study was to examine implant-related revisions among primary total hip replacement patients with up to six year follow-up in a randomized controlled trial which compared 28 mm and 36 mm metal on highly cross-linked polyethylene articulations in total hip replacement.

557 patients undergoing primary total hip replacement were included in this study. Risk factors for dislocation and wear were controlled by stratification and patients were then randomized intra-operatively to either a 28 or 36 mm articulation.

To date, 10 hips have been revised for implant-related problems following primary total hip replacement. Seven hips with a 28 mm articulation were revised to a larger articulation because of instability. Four of these were for recurrent dislocation, one for an irreduceable first dislocation and two for subluxation. In contrast, only one patient who had undergone total hip replacement with a 36 mm articulation was revised for recurrent dislocation. One hip with a 36 mm articulation in a well-positioned cup was revised to a 32 mm articulation because of elevated lip liner fracture. Another 36 mm articulation hip was revised for acetabular component loosening.

This study shows that a 36 mm metal on highly cross-linked polyethylene articulation reduces the need for early revision for instability after primary total hip replacement. However, these benefits need to be weighed against the potential risks associated with these articulations, including rare fracture of the relatively thin poly-ethylene liner.