Abstract

Total hip arthroplasty (THA) is one of the most successful surgical procedures of modern times, however debate continues as to the optimal orientation of the acetabular component and how to reliably achieve this. We hypothesised that functional CT-based planning with patient specific instruments using the Corin Optimised Positioning System (OPS) would provide more accurate component alignment than the conventional freehand technique using 2D templating.

A pragmatic single-centre, patient-assessor blinded, randomised control trial of patients undergoing THA was performed. 54 patients (age 18–70) were recruited to either OPS THA or conventional THA. All patients received a cementless acetabular component. Patients in both arms underwent pre- and post-operative CT scans, and four functional x-rays (standing and seated). Patients in the OPS group had a 3D surgical plan and bespoke guides made. Patients in the conventional group had a surgical plan based on 2D templating x-rays, and the pre-operative target acetabular orientation was recorded by the surgeon. The primary outcome measure was the difference between planned and achieved acetabular anteversion and was determined by post-operative CT scan performed at 6 weeks. Secondary outcome measures included Hip disability and Osteoarthritis Outcome Score (HOOS), Oxford Hip Score (OHS), EQ-5D and adverse events.

In the OPS group, the achieved acetabular anteversion was within 10° of the plan in 96% of cases, compared with only 76% of cases in the conventional group. For acetabular inclination, the achieved position in the OPS group was within 10° of the plan in 96% of cases, compared with in only 84% of cases in the conventional group. These differences were not statistically significant. The clinical outcomes were comparable between the two groups.

Large errors in acetabular orientation appear to be reduced when functional CT-based planning and patient-specific instruments are used compared to the freehand technique, but no statistically significant differences were seen in the difference between planned and achieved angles. Larger studies are needed to analyse this in more detail and to determine whether the reduced numbers of outliers lead to improved clinical outcomes.

Tissue sparing hip replacements have recently gained popularity, in an attempt to provide shorter hospital stay, faster recovery time and potentially to reduce morbidity and complications. Direct anterior approaches (DAA) have been shown to allow faster recovery, but also appear to be associated with a higher incidence of complications, especially during the learning curve. Mini-posterior approaches have the advantage of increased familiarity, however may not be maximally muscle sparing.

Prospective and retrospective data was collected following a published protocol. This included patient demographic data, theatre time, units of blood transfused, length of stay, functional scores and radiological parameters. Rates of conversion to posterior approach and complications were also documented.

The results of our first 100 cases completed are presented: Within this initial cohort, three patients suffered major complications: These included an anterior dislocation, which was successfully reduced with closed reduction under general anaesthetic, an early (day 6) periprosthetic fracture, which was successfully revised to a cemented prosthesis, and a case of stem subsidence.

Our results also suggest a learning curve effect, limited to theatre time and blood loss. Complications were evenly distributed throughout the period of study and are of similar frequency to standard approaches.

As the first European centre to adopt the SuperPATH approach, we have shown that the published results from America can be reproduced. In contrast to DAA, the learning curve is not associated with higher rates of femoral fracture and other complications. The fact that the approach is extensile, being the superior part of the posterior approach, allows for all of the advantages of muscle preservation with the safety of potential extension when necessary.

The orientation of the acetabular component in metal-on-metal hip resurfacing arthroplasty affects wear rate and hence failure. Correct assessment of acetabular orientation is key in assessing the painful hip resurfacing. This study aimed to establish if interpretation of pelvic radiographs with TraumaCad software can provide a reliable alternative to computed tomography (CT) in measuring the acetabular inclination and version.

TraumaCad was used to measure the acetabular orientation on AP pelvis radiographs of 14 painful hip resurfacings. Four orthopaedic surgeons performed each measurement twice. These were compared with measurements taken from CT reformats performed by an experienced musculoskeletal radiologist. The correlation between TraumaCad and CT was calculated, as was the intra- and inter-observer reliability of TraumaCad.

There is strong correlation between the two techniques for the measurement of inclination and version (p<0.001). Intra- and inter-observer reliability of TraumaCad measurements are good (p<0.001). Mean absolute error for measurement of inclination was 2.1°. TraumaCad underestimated version compared to CT in 93% of cases, by 12.6 degrees on average.

When assessing acetabular orientation in hip resurfacing, the orthopaedic surgeon may use TraumaCad in the knowledge that it correlates well with CT and has good intra- and inter-observer reliability but underestimates version by 12° on average. This underestimation may be contributed to by the natural divergence of the X-ray beam, the short arc of the ellipse left exposed by the large diameter head, and the non-hemispherical resurfacing cup.

Introduction

Metal on metal hip resurfacing (MMHR) has been advocated for the younger patient for several reasons including for the preservation of bone stock and ease of revision to total hip replacement (THR), thus ‘buying an additional operation’ for the patient. This rationale however assumes a good functional outcome after the revision to a THR and that the results of the ‘revision primary’ will not be compromised by the resurfacing which preceded it. We present our data on a consecutive series of 68 revised MMHRs.

Informed consent is vital for good patient-surgeon communication. It allows the patient to be given an unbiased and accurate view of the procedure as well giving an opportunity for patients to gain trust in their surgical team. The consent form is written evidence of this discussion and a poor consent form implies a sub-standard consenting process. The General Medical Council (GMC) have issued guidelines for consent in surgical procedures. These state that all common risks and rare but serious risks should be disclosed as well as all information being given in clear simple and consistent language.

Currently, the consent form for a hip fracture operation is hand written. Our hypothesis was that the quality of consenting is variable and that many important complications may not be identified.

The British Orthopaedic Association (BOA) blue book, ‘The care of patients with fragility fractures,’ has given guidance of common and serious complications associated with operative management of hip fractures. In addition to these procedure specific complications, we have identified general complications from standardised joint arthroplasty consent forms in our trust, such as deep vein thrombosis. Our standards based on GMC guidance are that the consent form should be legible, free from jargon, without abbreviations and should include the specific and general complications.

We retrospectively identified and analysed 30 consecutive consent forms of patients that underwent operative management for hip fractures between March and April 2011. Of all consent forms, 59% were completely or partly illegible, 77% had used abbreviations and medical jargon. Inclusion of general complications on the consent form varied; infection 100%, bleeding 100%, deep vein thrombosis 82%, MI 18%, pneumonia 12%, death 12% and haematoma 0%. Specific operative complications were poorly included, with no patients undergoing hemiarthroplasty being advised of the risk of prosthetic loosening, acetabular wear or periprosthetic fractures. For consent of patients undergoing fracture fixation, 67% had been informed of re-operation and 40% had been told of non-union.

This data shows that consent forms are generally poorly written and subject to great variation in complications for the same surgical procedure. This data is likely to apply to some extent to all hospitals that use blank consent forms. This has implications for patient care and safety, as well as medicolegal implications for medical professionals. In our hospital, consent forms have been standardised for joint arthroplasty, with all complication pre-printed with plain English explanations below. Our proposal is that all common operations should have pre-printed consent forms. This would standardise consenting and provide a much improved documentary evidence of the consenting process.

This data has a number of lessons that can be applied to other hospitals. Firstly, we suggest that other hospitals consider standardised consent forms. Secondly, individual trainees should be clear that consent forms remain the documentary evidence of the consenting process, long after you forget the verbal details and you should ensure that you include all complications, write clearly and without jargon or abbreviations.

Urinary catheterization in the postoperative period is known to increase the risk of deep joint infection following arthroplasty. A number of studies have attempted to elucidate the individual patient factors and surgical procedural factors which predispose patients to postoperative urinary retention.

We conducted a retrospective observational study of three hundred patients to specifically determine the effect of the anaesthetic technique on the incidence of urinary retention following elective lower limb arthroplasty. One hundred consecutive patients were surveyed in each of three groups differing by the type of the anaesthetic technique and the drug administered; 1) general anaesthesia with femoral nerve block, 2) spinal anaesthesia with intrathecal fentanyl, and 3) spinal anaesthesia with intrathecal morphine.

The incidence of urinary retention requiring catheterisation in male patients receiving intrathecal morphine was 58% compared with 10% and 6% for those who had general anaesthesia with femoral nerve block and intrathecal fentanyl, respectively. This difference was statistically significant (p<0.01). The incidence of urinary retention in females across all groups was =2%. The average residual volume of urine following catheterisation was 750ml (460-1500ml).

Our findings show that the use of intrathecal morphine greatly increases the risk of postoperative urinary retention in male patients, whereas no significant increase was found amongst female patients. This risk should be carefully considered when choosing the type of intraoperative anaesthetic/analgesic combination employed in male patients and be rationalised against the intended benefits to the patient.

Purpose of study

To investigate possible advantages of uncemented over cemented femoral components in hip resurfacing.

We investigated the blood flow to the femoral head during and after Resurfacing Arthroplasty of the hip.

In a previous study, we recorded the intra-operative blood flow in 12 patients who had a posterior approach to the hip and 12 who had a trochanteric flip approach. Using a LASER Doppler flowmeter, we found a 40% drop in blood flow in the posterior group and an 11% drop in the trochanteric flip group (p<0.001). The aim of this current study was to find out whether the intra-operative fall in blood flow persists during the post-operative period.

We therefore conducted a Single Positron Emission Tomography (SPECT) scan on 14 of the same group of patients. The proximal femur was divided into four regions of interest. These were the mid-shaft, proximal shaft, inter-trochanteric and head-neck regions. The data was analysed for bone activity and comparisons made between the two groups for each region of the femur. We found that the bone activity in the mid-shaft, upper-shaft, and head-neck regions was the same eleven months after the surgery irrespective of the approach to the hip. However there was higher activity in the trochanteric flip group in the inter-trochanteric region.

We conclude that the intra-operative deficit in blood flow to the head-neck region of the hip associated with the posterior approach does not seem to persist in the late post-operative period. We believe the reason for increased bone activity in inter-trochanteric region to be due to the healing of the trochanteric flip osteotomy.

Purpose of the study

We report the problems associated with setting up an electronic arthroplasty surveillance plan and suggest some solutions which are appropriate to the modern NHS setting.

We used a laser Doppler flow-meter with high energy (20 m W) laser (Moor Instruments Ltd. Milwey, UK) to measure the blood flow to the femoral head during resurfacing arthroplasty.

Twenty-four hips were studied; 12 underwent a posterior approach and twelve a Ganz's trochanteric flip osteotomy. The approach was determined according to surgeon preference. Three patients were excluded, The exclusion criteria were previous hip surgery, history of hip fracture and avascular necrosis (AVN). All patients had the hybrid implant with cemented femoral component.

During surgery a 2.0mm drill bit was passed via the lateral femoral cortex to the superior part of the head neck junction. The position was confirmed using fluoroscopy. The measurements were taken during five stages of the operation: when the fascia lata was opened (baseline), at the end of soft tissue dissection, following dislocation of the hip, after relocation back into the socket, after inserting the implants prior to closing the soft tissues and, finally, at the end of soft tissue closure.

The results were analysed and the values were normalised to a percentage of the baseline value. We found a mean drop of 38.6 % in the blood flow during the posterior approach and a drop of 10.34% with the trochanteric flip approach. The significant drop occured between the baseline (1st stage) and the end of the soft-tissue dissection (2nd stage). In both groups the blood flow remained relatively constant afterwards.

Our study shows that there is a highly significant drop in blood flow (p<0.001) during the posterior approach compared with the trochanteric flip approach.

Introduction: Pain and mass lesions around hip resurfacing are reported with increasing frequency. The aetiology is unknown but reaction to metal wear debris and mechanical impingement have both been suggested. We are aware of a group of our patients with significant pain following resurfacing. We sought to correlate metal ion levels with X-ray findings and any local soft tissue reaction around the prosthesis.

Methods: Patients with significant groin pain following hip resurfacing were identified from routine clinics. Blood was tested for cobalt and chromium levels using inductively coupled mass spectrometry in all patients. Cup abduction angle and femoral stem version were estimated from plain radiographs. Patients underwent ultrasound scan (USS) of the affected hip joint. Bilateral prostheses were excluded to avoid confounding.

Results: 47 unilateral painful hip resurfacings (24 female) were identified. USS was performed in 42 patients and was abnormal in 25 (15 female). Abnormalities ranged from simple joint effusion with or without synovial thickening, through to cystic masses in the posterior joint and solid masses related to the ileopsoas tendon similar to the appearances previously described in pseudotumours.

A two sample t-test demonstrated cobalt and chromium ion levels were significantly higher in patients with abnormalities on USS (p=0.038, p=0.05 respectively), patients with normal USS were more likely to have a retroverted femoral component (p=0.01).

Discussion: We describe two groups of patients with a painful hip resurfacing: those with raised metal ions and local soft tissue reaction, and those with lower metal ions and no soft tissue reaction. The retroverted stems in the second group could cause an iatrogenic cam-type impingement. Metal ion levels are useful to guide further imaging. Raised levels should prompt investigation for a soft tissue abnormality with either USS or MRI, lower levels suggest investigation should look for mechanical impingement with imaging such as CT.

Introduction: There has been a substantial increase of Clostidium Difficile (C.difficile) in Europe over the last decade. This increased incidence of C.difficile has been attributed in part to the prophylactic use of antibiotics during orthopaedic and trauma surgery. The consequences of a C.difficile infection can be an increase in mortality, length of stay and cost of medical care. The mortality associated with C.difficile has been quoted to be up to 25% in frail elderly people and the cost of treating a single case of C. difficile infection has been estimated at 4500 Euros (£4000).

The antibiotic prophylaxis for orthopaedic and trauma patients undergoing metal work implantation was changed in our unit to specifically reduce the incidence of C.difficile. The aim of this study was to determine whether this change did reduce the incidence of post-operative C.difficile infections presenting on the orthopaedic ward. The secondary aim was to ensure that the change in prophylaxis did not increase the incidence of deep wound infections.

Method: The old prophylactic protocol involved a dose of Cefuroxime at induction, followed by two further doses post-operatively. The new protocol was a single dose of Gentamicin and Flucloxacillin or a single dose of Gentamicin and Teicoplanin (if MRSA positive or penicillin allergy) at induction. The incidence of C.difficile infection and deep wound infection were recorded for a six month period prior to the protocol change and for a six month period once the new antibiotic protocol had been established. Patients included into the study were those undergoing a primary arthroplasty of the knee or hip and patients undergoing metalwork implantation for a proximal femoral fracture.

Results: 1566 patients were included in the study. The overall rate of C.difficle infection reduced form 3.7% to 1.3% (p less than 0.005) after the prophylactic antibiotic protocol was changed. This was most marked in the trauma patients from 8% to 3% (p less than 0.05). There was no significant difference in the incidence of deep wound infections for the trauma patients (p equals 0.5) or the elective patients (p equals 0.7).

Conclusion: The change in antibiotic prophylaxis did significantly reduce the incidence of C.difficile in patients undergoing metalwork implantation and did not change the rate of deep wound infections.

Narrowing of the femoral neck after resurfacing arthroplasty of the hip has been described previously in both cemented and uncemented hip resurfacing. Traditionally hip resurfacing has been performed via a posterior approach though other surgical approaches including the Ganz and the anterolateral approach have been well described. In addition it is known that the blood supply of the femoral neck arises largely from posterior structures and it has been postulated that neck narrowing is a consequence of poor post-operative femoral neck vascularity. Our null hypothesis in this study was that the choice of surgical approach does not influence postoperative femoral neck narrowing. We retrospectively measured the diameter of the femoral neck in a series of 135 consecutive patients who underwent uncemented cormet hip resurfacing, with follow up from one to 3 years. Our sample included 50 females and 85 men with an average age of 56.4 years (standard deviation of 9.47). Seventy six patients had a Ganz approach, 5 had an anterolateral approach and 55 had a posterior approach. There were no failures due to femoral neck fracture and no revisions to total hip arthroplasty. Eleven patients required subsequent surgery all of which were due to complications following trochanteric osteotomy. Seven patients needed removal of metalwork and 4 patients had non-union of their osteotomy requiring revision. At one year the posterior approach group had an average of 5.2% neck narrowing versus 2.7% neck narrowing in the Ganz approach group (p value 0.06). At three years the average neck narrowing amongst all patients was 6.8% (standard deviation 3.1%) but the number of patients who had had a Ganz approach was too small to meaningfully apply inference statistics. Our study shows early results which show a statistically significant reduction in the rate of femoral neck narrowing in patients who have had a Ganz approach as compared to a posterior approach for unce-mented hip resurfacing arthroplasty. It also shows a high rate of complications inherent with the Ganz approach which in our patient group are entirely related to the trochanteric osteotomy.

Introduction: Hip resurfacing has become re-established in recent years as a viable option in younger, active individuals. The results of a multi-centre evaluation of the Cormet resurfacing device are presented.

Materials and Methods: Data has been entered from 1997 onwards from 5 centres, patients being selected as suitable by 8 individual surgeons. Pre and intraoperative details recorded including indications, patient details, implant used, Harris Hip Score (HHS) and surgical approach.

Results: A total of 781 procedures in 676 patients have been recorded (54% posterior approach, 40% antero-lateral, 6% Ganz approach). The mean follow-up is 2.5 years (0.1–9.7 yrs) and the mean postoperative HHS is 85.9 (range 25–100). The mean age at surgery was 54.2 years. 60% of implantations were on male patients. The principal diagnosis was; OA 87%, RA 5%, AVN, post-traumatic OA and DDH 2% each, Perthes 1% and the remainder 1%. It is thought likely that many cases of OA had many of the above-named pathologies as a precursor. The mean maximum flexion postoperatively was 98.6 degrees. Uncemented heads (a recent innovation) were used in 7%. Kaplan-Meier survivorship is 93% at 9 years. In the OA subgroup 3.3% have been revised, approximately equal numbers for femoral head collapse, dislocation and cup loosening, but the vast majority due to femoral neck fracture, which in turn was generally associated with the posterior approach.

Conclusions: The results of this cohort (which includes the learning period of the contributing surgeons) indicate highly satisfactory outcomes in terms of HHS and implant longevity. Sub-classification of cases into those presenting abnormal anatomy and those with ‘ordinary’ OA indicates better survivorship still in the latter group. The surgical challenge varies more with hip resurfacing than with standard hip arthroplasty and this should be considered when results of surgery are reviewed. The revision options are generally much simpler than after standard THR.

Introduction: Hip resurfacing has become re-established in recent years as a viable option in younger, active individuals. The results of a multi-centre evaluation of the Cormet resurfacing device are presented.

Methods: Data has been entered from 1997 onwards from 5 centres, patients being selected as suitable by 8 individual surgeons. Pre and intraoperative details recorded including indications, patient details, implant used, Harris Hip Score (HHS) and surgical approach.

Results: A total of 905 procedures in 782 patients have been recorded (52% posterior approach, 39% anterolateral 9% Ganz approach). The mean follow-up is 2.8 years (0.1–9.5 yrs) and the mean postoperative HHS is 86.1 (range 25–100). The mean age at surgery was 54.4 years. 61% of patients were male. The principal diagnosis was; OA 88.3%, RA 4.3%, AVN 2.1%, posttraumatic OA 1.1%, DDH 2.1%, Perthes 0.7% and the remainder 1.4%. It is thought likely that many cases of OA had many of the above-named pathologies as a precursor. The mean maximum flexion postoperatively was 98.7 degrees. Uncemented heads (a recent innovation) were used in 10%. Kaplan-Meier survivorship is 93% at 9 to 10 years. Survivorship in the OA subgroup was 96.7% with approximately equal numbers for femoral head collapse, dislocation and cup loosening, but the vast majority due to femoral neck fracture, which in turn was generally associated with the posterior approach.

Discussion: The results of this cohort (including all contributors’ learning curves) indicate highly satisfactory outcomes in terms of HHS and implant longevity. Subclassification of cases into those presenting abnormal anatomy and those with ‘ordinary’ OA indicates better survivorship still in the latter group. The surgical challenge varies more with hip resurfacing than with standard hip arthroplasty and this should be considered when results of surgery are reviewed. The revision options are generally much simpler than after standard THR.

We used Laser Doppler flowmetry to measure the effect on the blood flow to the femoral head/neck junction of two surgical approaches during resurfacing arthroplasty. We studied 24 hips undergoing resurfacing arthroplasty for osteoarthritis. Of these, 12 had a posterior approach and 12 a trochanteric flip approach. A Laser probe was placed under radiological control in the superolateral part of the femoral head/neck junction. The Doppler flux was measured at stages of the operation and compared with the initial flux. In both groups the main fall in blood flow occurred during the initial exposure and capsulotomy of the hip joint.

There was a greater reduction in blood flow with the posterior (40%) than with the trochanteric flip approach (11%).

There is an increasing interest amongst surgeons and demand from patients for hip resurfacing. One concern regarding resurfacing is the incidence of femoral neck fracture post operatively. McMinn and Treacy report an incidence of 0.4% in their series, our finding was of an incidence of over four times as high (1.9%). We looked at our database of hip resurfacings and tried to identify the risk factors for fracture.

We identified 11 fractures and compared these with 22 controls selected by choosing the cases performed by the surgeon immediately before and after the fracture case. We analysed their medical notes and x-rays. Statistical analysis was performed using a package in ™Excel. The implants were either Birmingham Hip (Midland Medical Technologies) or Cormet (Corin) resurfacings.

No statistically significant correlation was found for sex, age or body mass index. We found that fracture was twice as likely in the presence of possible or probable osteopenia. We did not find that fracture was more likely to occur in patients with a previous diagnosis of Perthes, DDH, SUFE and avascular necrosis (AVN).

We found patients with a superior overhang of the femoral component on the neck did not risk fracture, however we could not demonstrate that notching in itself increased the risk of fracture.

There was no correlation with neck-shaft and stem-shaft angle or neck lengthening and offset and subsequent neck fracture.

In 13 bilateral cases there was fracture in 3 (incidence 23%). Apart from one fracture that occurred at 18 weeks post-operatively all the others occurred before eight weeks. Five fractures occurred in patients who subsequently on histological analysis were found to have avascular necrosis.

We conclude that bilateral surgery is probably unwise. That a superior overhang seems to protect against fracture as long as this is not at the expense of creating an inferior notch. Finally, we find AVN in a number of retrieved heads, what is the true incidence of AVN and does the approach adopted cause the avascular process and if so why do we see so few fractures?