HIP International

Bernese periacetabular osteotomy (PAO) was introduced by Ganz as a novel surgical technique for hip dysplasia with a congruent hip to reorient the acetabulum in skeletally mature patients. The PAO through a modified Smith-Petersen (Iliofemoral) approach, has been subject to many modifications in order to avoid complications and to minimise risks for failure.

The aim of this review was to report on the complication rates, functional and radiological outcomes in relation to surgical approaches.

A search of NICE healthcare database advanced search, was conducted from the year of inception to May 2018. We included studies that reported complications of PAO. Data extracted from case series was analysed to detect the incidence of complications, relation to surgical approach and temporal trend of complications.

40 studies including 4070 hips with a mean age of 29 years and a mean follow-up of 52.8 month, were analysed. Outcome measures demonstrated good to excellent outcome in 82%. Higher rates of LFCN and sciatic nerve injuries were found to be associated with the ilioinguinal and the 2-incision approach. Minimally invasive (MIS) modified Smith-Petersen (MSP), minimally invasive trans-sartorial and trans-trochanteric approaches were not reported to be associated with any major wound complications. Radiological correction achieved with a mean improvement in acetabular inclination of 17.90 (range 4.5–40), anterior centre-edge correction 25.40 (range 10–51), lateral centre-edge correction 23.30 (range 15–44.6) and medial translation of 6 mm (range 3.2–10).

The complication rates seem to be lower in this current review (7%) as compared to the previous review performed by Clohisy et al. (6–37%). The MIS trans-sartorial/MIS MSP and intertrochanteric approaches are associated with an even reduced complications rates. This review enables favouring the minimally invasive approaches with regard to reducing nerve injury and wound complications.

Several radiographic signs have been described to assess acetabular coverage. However, plain radiographs only have 2 dimensions (2D) and cannot accurately show acetabular coverage.

We developed the ACX Dynamics software to calculate the radial centre-edge angle (RCEA), which represents the acetabular coverage of the femoral head at each acetabular edge point on the radial plane. This study validated the accuracy of the RCEA, as calculated by ACX Dynamics, as a quantitative parameter for acetabular coverage.

We reviewed the anteroposterior (AP) pelvic radiographs and computed tomography (CT) of 650 hips from 325 patients who presented with chief complaint of symptoms at the hip joint. Of 109 hip radiographs (68 patients) that satisfied the criteria, 50 randomised, blinded AP pelvic radiographs were chosen. We determined the absolute RCEA difference (°) [= RCEA ACX (°) – RCEA CT (°)], determined the correlation between RCEA ACX (°) and RCEA CT (°), and examined the RCEA’s intra-observer and inter-observer reliability in 50 hips.

The absolute RCEA difference from A45° to P75° was 1.9–3.1°. The correlation between the RCEA ACX (°) and RCEA CT (°) was > 0.7 in all lesions (p < 0.001). Using the intraclass correlation coefficient, the intra-observer reliability of the RCEA was 0.83–0.97 in the whole range, which is a highly reproducible and reasonable parameter, and the inter-observer reliability was > 0.80 in A45°–P0°.

The RCEA ACX (°) can be used as a simple quantitative parameter for assessing acetabular coverage using AP pelvic radiograph.

We compiled evidence from a large national surgical database to identify the incidence, risk factors and postoperative impact of Clostridium difficile infection (CDI) in patients undergoing hip fracture repair.

We identified 17,474 patients who underwent hip fracture repairs in 2015 using the ACS-NSQIP database. Interventions studied were open reduction/Internal fixation, total hip arthroplasty or hemiarthroplasty being performed for traumatic hip fractures. Outcomes studied were incidence, preoperative and postoperative risk factors for occurrence of CDI were studied using descriptive and statistical analysis.

A total of 92 patients (0.53%) developed CDI within 30 days of the operation. Following adjustment using multi-variate logistic regression, preoperative and hospital-associated factors associated with development of CDI were smoking (OR 1.75 [95% CI 1.03–2.99]), hypertension (OR 1.70 [95% CI 1.01–2.85]), hyponatraemia (OR 1.65 [95% CI 1.04–2.63]), prior systemic inflammatory response syndrome (SIRS) (OR 2.18 [95% CI 1.32-3.59]) and a length of stay >7 days (OR 1.98 [95% CI 1.11–3.53]. Postoperative factors associated with occurrence of CDI were occurrence of a deep surgical site infection (SSI) (OR 5.89 [95% CI 1.31–26.6]), a stay in the hospital >30 days (OR 6.56 [95% CI 2.56–16.9]) and unplanned reoperations (OR 2.78 [95% CI 1.29–5.99]).

As we move toward an era of bundled-payment models, identification of risk factors associated with the occurrence of postoperative complications, such as CDI, will help curb excess healthcare utilisation and costs associated with the management of this complication.

Correct implant positioning is required to achieve adequate biomechanics. The greater trochanter is more medially or laterally positioned in some patients, known as trochanteric lateroversion. However, studies have not identified correlations between postoperative coronal alignment and variation in greater trochanteric lateroversion. The purpose of this study was to identify the effects of variation in greater trochanteric lateroversion on postoperative stem coronal alignment and to investigate other factors related to stem coronal alignment.

A total of 213 hips in 149 patients who underwent total hip arthroplasty were included in this prospective study. The greater trochanters were categorised into 5 groups according to the degree of variation in greater trochanteric lateroversion, and the stem coronal alignment angle and stem fit were measured on anteroposterior radiographs.

Postoperative stem varus was positively correlated with greater trochanteric lateroversion (r = 0.26065, p = 0.0001) and negatively correlated with the stem fit (r = −0.16568, p = 0.0155).

Excessive variation in greater trochanteric lateroversion was a risk factor for femoral stem varus, and the stem varus position was always accompanied by inadequate canal filling. When the tip of the trochanteric overhang exceeded the centreline of the femoral canal, the influence of lateroversion of the greater trochanter on the femoral stem remarkably increased. Appropriate measures should be implemented to avoid a stem varus position and inappropriate stem fit.

Intraoperative radiographic evaluation during total hip arthroplasty (THA) has shown to improve the accuracy of acetabular component placement, however, differences in interpretation based on radiographic technique has not been established. This study aims to determine if differences exist in the interpretation of acetabular component abduction and anteversion between different radiographic projections.

55 consecutive direct anterior THAs in 49 patients were prospectively enrolled. Target anteversion and abduction was defined by the Lewinnek zone. Fluoroscopy was used to direct acetabular component placement intraoperatively. After final cup implantation, fluoroscopic posterior-anterior hip and pelvis images were obtained for analysis. After completion of the procedure, an anterior-posterior plain pelvis radiograph was obtained in the operating room. Acetabulum component abduction and anteversion were postoperatively determined using specialised software on each of the 3 image acquisition methods.

Average acetabular cup abduction for intraoperative fluoroscopic posterior-anterior hip (FH), intraoperative fluoroscopic posterior-anterior pelvis (FP), and postoperative, standard, anteroposterior pelvis radiographs (PP) was 40.95° ± 2.87°, 38.87° ± 3.82° and 41.73° ± 2.96° respectively. The fluoroscopic hip and fluoroscopic pelvis tended to underestimate acetabular cup abduction compared to the postoperative pelvis (p < 0.001). Average acetabular cup anteversion for FH, FP, and PP was 19.89° ± 4.87°, 24.38° ± 5.31° and 13.36° ± 3.52° respectively. Both the fluoroscopic hip and fluoroscopic pelvis overestimated anteversion compared to the AP pelvis, with a 6.38° greater mean value measurement for FH (p < 0.001), and an 11° greater mean value measurement for FP (p < 0.001).

Fluoroscopic technique and differences between radiographic projections may result in discrepancies in component position interpretation. Our results support the use of the fluoroscopic posterior-anterior hip as the choice fluoroscopic imaging technique.

Individual pelvic tilt and rotation have wide variability that can affect the measurement of cup orientation in anteroposterior (AP) radiographs. The purpose of this study was to analyse the effect of pelvic tilt and rotation on radiographic measurements of cup orientation.

A total of 53 patients (63 hips) were included in this study. The patients underwent a computed tomography study with standing AP pelvis radiographs taken both preoperatively and approximately 3 months postoperatively. We used 2-dimensional/3-dimensional matching to measure the pelvic tilt and rotation, and the non-standardised and standardised cup orientation.

There was no difference in the pelvic tilt and rotation between the preoperative and postoperative radiographs. The distribution of the differences between the non-standardised and standardised cup anteversion exhibited a change within 5° in only 34/63 (54%) hips. The pelvic tilt correlated with the difference between the non-standardised and standardised cup anteversion, but the pelvic rotation did not. When all 63 hips were separated into the right and left sides, the pelvic rotation inversely correlated with the pelvic tilt-adjusted difference between the non-standardised and standardised cup anteversion of the right side but directly correlated with that of the left side.

The current study demonstrated that the measurement of cup anteversion in standing AP radiographs is significantly affected by both the pelvic tilt and pelvic rotation. An improved understanding of the pelvic orientation may eventually allow for desired cup positioning on a patient-specific basis to potentially reduce complications associated with the malposition of the cup.

Metal-on-metal total hip arthroplasty (MoM THA) is associated with the formation of pseudotumours. Studies mainly concern pseudotumour formation in large head MoM THA. We performed a long-term follow-up study, comparing pseudotumour incidence in small head metal-on-metal (SHMoM) THA with conventional metal-on-polyethylene (MoP) THA. Predisposing factors to pseudotumour formation were assessed.

From a previous randomised controlled trial comparing SHMoM (28 mm) cemented THA with conventional MoP cemented THA, patients were screened using a standardised CT protocol for the presence of pseudotumours. Serum cobalt levels and functional outcome were assessed.

56 patients (33 MoP and 23 MoM) were recruited after mean follow-up of 13.4 years (SD 0.5). The incidence of pseudotumours was 1 (5%) in the SHMoM THA cohort and 3 (9%) in the MoP THA cohort. Prosthesis survival was 96% for both SHMoM and MoP THAs. Serum cobalt levels did not exceed acceptable clinical values (<5 µg/L) whereas no differences in cobalt levels were detected at follow-up between both groups. Oxford and Harris Hip Scores were good and did not differ between SHMoM and MoP THA.

This long-term follow-up study shows a low incidence of pseudotumour formation and good functional outcome in cemented head-taper matched SHMoM and MoP THA.

Metal-on-metal (MoM) total hip arthroplasties (THAs) have been linked with increased incidence of pseudotumours and revision rate. magnetic resonance imaging (MRI) is useful in diagnosing adverse reaction to metal debris (ARMD) disease but it is not known if MRI findings correlate with cup position.

From a cohort of 79 MoM THA, 34 MRI studies were available. MRI was classified according to Anderson classification. Mean follow-up was 7.1 years. Evaluation included cup position including margin of safety, measurement of metal ion levels and evaluation of function.

44% of patients had definite ARMD. We did not find any correlation between MRI stage and Co, Cr, margin of safety (MOS) or functional scores. However, patients with a margin of safety angle < 21° had more severe findings in MRI.

Patients with MoM THA experience high degree of ARMD. In our study, the disease did not correlate with metal ion levels but correlated with cup position, evaluated with the MOS angle.

In arthroplasty surgery, positioning of the components must be accurate and reproducible to avoid complications. Conventional guides are often used to align a component, but they require surgical skill and experience, and are prone to error. To this end, a single-use, size-specific, nylon guide (single-use nylon guide) has been developed for the purpose of increasing the accuracy without adding extra cost to the operation. The effectiveness of this type of guide was evaluated in using a synthetic bone study.

A total of 66 synthetic femurs with the same osteoarthritic morphology were prepared. 3 surgeons participated in the experiments, and each surgeon created a drill hole for the femoral component by using the single-use nylon guide or a commercially-available, conventional, metal, neck-based guide (conventional guide). Anteversion, inclination, and insertion point acquired by the guide were compared between the guides, between surgeons, and to the computer-based plan.

Anteversion acquired by the single-use nylon guide (6.7° [4.9–11.5°]) was significantly closer to the plan (14.6°) than that acquired by the conventional guide (4.3° [2.4–8.6°]) (p = 0.03). The insertion point was also significantly closer to the plan for the single-use nylon guide (3.8 mm ± 1.6 mm) than the conventional guide (5.7 mm ± 2.4 mm) (p < 0.001). No significant difference was found for the inclination (p = 0.76).

A single-use, size-specific nylon guide was effective in acquiring a higher accuracy and precision in anteversion and insertion point than a conventional guide in this synthetic bone, hip resurfacing arthroplasty study. The use of single-use guides in other orthopaedic procedures should be explored.

Our main aim was to investigate whether obese patients were at increased risk of elevated metal ion levels and/or adverse local tissue reaction (ALTR) after being treated with articular surface replacement (ASR) hip arthroplasty.

This study included 360 patients who underwent metal-on-metal (MoM) hip resurfacing (HRA) or total hip arthroplasty (THA). 95 patients (26%) were underweight/normal weight (BMI < 25 kg/m²), 139 (39%) were overweight (BMI 25–30 kg/m²), and 126 (36%) were obese (BMI ⩾ 30 kg/m²). Blood metal ion levels and patient-reported outcome measures (PROMs) were obtained, and a sub-cohort of 85 patients had MARS MRI performed. Logistic regression analyses were used to assess the associations between obesity and metal ions, as well as ALTR.

BMI was not associated with either elevated metal ion levels or ALTR. In HRA patients, female gender (OR 3.0; p = 0.019) and pain (OR 2.3; p = 0.046) were associated with elevated Co levels. Female patients had increased risk of elevated Cr levels (OR 3.0; p = 0.02). In THA patients, female gender (OR 2.2; p = 0.004) and VAS satisfaction (OR 2.1; p = 0.01) were associated with elevated Co levels. Female gender (OR 3.6; p = 0.001) and time from surgery (OR 1.4; p = 0.005) were associated with Cr levels. In the sub-cohort, ALTR was associated with Co levels (OR 16.1; p = 0.002) in HRA patients.

Patients with BMI ⩾ 30 kg/m² present no increased risk for elevated metal ion levels or development of ALTR.

Taper corrosion related revisions have recently been reported in the orthopaedic literature. Cleaning procedure of the trunnions during hip revision is not standardised. The purpose of this bench top investigation was to understand the alterations in the trunnion dimensions and surface roughness characteristics as a result of corrosion product build-up.

8 titanium alloy trunnions and CoCr femoral heads assemblies were cyclically tested in a mechanical simulator. Following disassembly of the tested constructs, the trunnions were cleaned using 2 methods. The trunnion dimensions were measured using coordinate measuring machine, and surface roughness was measured using white light interferometry. The trunnions were reassembled with ceramic femoral heads and titanium sleeves following cleaning. Head/sleeve pull-off testing was conducted to understand the effects of cleaning methods on the pull-off strength.

Grade 4 corrosion was observed on all trunnions after mechanical testing. The aggressive cleaning methods had a larger impact on the surface roughness when compared to the light cleaning method. The aggressive cleaning method also decreased the taper cone angle. The pull-off strength was not affected by the cleaning method and the pull-off values were approximately 50% of the assembly loads.

The study suggests that trunnion cleaning method may alter the surface roughness and taper cone angle of the existing trunnion. However, the effects of these changes on the pull-off strength did not reach statistical significance. Complex corrosion testing under cyclic loading conditions are warranted to understand the long-term effects of these changes.

The treatment for recurrent dislocation of a total hip arthroplasty is surgical using varied techniques and technologies to reduce the chances of re-dislocation and re-revision. The goal of this study is to compare operative techniques to reduce re-dislocation and re-revision in revision hip arthroplasty due to recurrent dislocations.

A retrospective study of revision hip arthroplasties done due to recurrent dislocation prior to 01 January 2014. Electronic physician and provincial health records were used to collect patients’ initial and follow-up data. Treatment failure was defined as either aseptic re-revision or re-dislocation without revision. Time to event was considered as the re-revision date or the date of second dislocation when the latter endpoint was used.

Of 379 operations, 88 (23.2%) had aseptic repeat revision or recurrent dislocation. Of these: 66 (75.0%) due to dislocation with re-revision; 10 (11.4%) due to dislocation with no re-revision surgery; 5 (5.7%) due to aseptic loosening of components; 3 (3.4%) due to osteolysis; 3 (3.4%) due to pseudotumour; and 1 (1.1%) due to periprosthetic fracture. The following factors increase risk of failure: the use of augmented-liners (lipped, oblique and high-offset liners; HR = 1.68, 95% CI, 1.05–2.69), periprosthetic femur fracture (HR = 2.80, 95% CI, 1.39–8.21) and pelvic discontinuity (HR = 3.69, 95% CI, 1.66–8.21). Femur head sizes 36–40 mm are protective (HR = 0.54, 95% CI, 0.31–0.86). In abductor dysfunction the use of focal constrained liners decreases the risk of failure (HR = 0.13, 95% CI, 0.018–0.973).

Larger head sizes and focal constrained liners (abductors dysfunction) should be used and fully constrained liners and augmented-liners should be avoided in a revision hip arthroplasty due to recurrent dislocations.

To evaluate the predictive value of pre-fracture medication usage on 30-day mortality following a hip fracture.

Information on age, sex, fracture type, time of death and Charlson co-morbidity index (CCI) was collected from the Danish National Patient Registry on all patients above 60 years, sustaining a hip fracture during the period January 1995 to December 2013. Information on drug usage was obtained from the Danish National Prescription Database. Hazard ratios were calculated with 30-day mortality as the outcome. A univariate and 3 multivariate analyses were conducted with increasing adjustments, starting with age, sex and fracture type, adding co-morbidity and dose in the latter.

141,201 patients were included and a total of 12 drugs/drug groups were identified for analysis. Increased mortality was evident in all analyses for antiarrhythmics, beta blockers, proton pump inhibitors, loop diuretics, opioids, acetaminophen and for psycholeptics. For ACE-inhibitors, increased mortality was found in all analyses, except after adjustment for co-morbidity and dose. For thiazide diuretics, a significantly reduced mortality was evident in all but the univariate analyses while NSAIDs and statins were associated with a significantly reduced mortality in all analyses. For calcium channel blockers, an insignificant decrease was found after adjustment for dose.

Further analysis showed a dose-response relationship for all drugs except ACE-inhibitors and calcium channel blockers.

The study shows a correlation between pre-fracture usage of certain drugs and 30 day mortality after a hip fracture.

We examined the trends in the treatment of femoral neck fractures with arthroplasty in the United States from 2004–2013.

We used the National Inpatient Sample database in conjunction with codes from the International Classification of Diseases, Ninth Revision, to identify patients receiving hemiarthroplasty (HA) or total hip arthroplasty (THA) for the treatment of closed femoral neck fracture from 2004–2013. We evaluated the trend of these 2 treatments along with demographics, comorbidities, length of stay and same admission mortality.

Our study identified 1,059,414 patients who underwent arthroplasty for the treatment of femoral neck fracture. We found a 42% increase in the use of THA during the study period from 8.4% in 2004 to 12.9% in 2013. While the large majority of patients received HA (87.1%), there was an overall decline in the use of HA (89,132 in 2004 to 85,635 in 2013) and increase in the use of THA (8,177 in 2004 to 11,375 in 2013). Patients receiving THA were younger (mean age 74.7 THA vs. 80.4 HA, p < 0.001) with fewer comorbidities, higher likelihood of discharge to home (24% THA vs. 10% HA, p < 0.001) and lower inpatient mortality rates (1.5 % THA vs. 2.4 % HA, p < 0.001) in comparison to HA.

There has been a significant increase in the use of THA over the last decade. Patients receiving THA were younger and healthier with fewer comorbidities, less likely to sustain a same admission mortality and more likely to discharge to home in comparison to HA patients.