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.

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.

Metal on metal hip resurfacing is increasing in popularity for the young, active patient. We present the results of a consecutive series from a single surgeon over a ten year period; 295 hip resurfacings (McMinn and Cormet; Corin, Cirencester, UK) with a minimum follow up of 2 years and a mean follow up of 4 years. There were 173 males with a mean age of 53.4 years and 121 females with a mean age of 50.3 years. Forty-six patients underwent bilateral resurfacings. All resurfacings were performed through a posterior approach.

The aetiology in this group was primary OA in 75.9%, inflammatory arthritis in 6.1%, DDH in 6.1%, AVN in 4.7%, trauma in 4.7%, Perthes in 1.7% and SUFE in 0.7%. Patients were reviewed clinically and radiographically on an annual basis. Follow-up was available on 93% of patients. 94.2% of hips have survived and the mean Harris Hip Score is 87.5. Females had a higher failure rate (10.7%) than males (2.3%). There was no clear trend between patient age and failure rate. The highest failure rate (33.3%) was seen in patients with DDH whilst only 4.5% of patients with OA failed. One patient with AVN failed but no failures occurred in patients with inflammatory arthritis, trauma, Perthes or SUFE. Failures occurred due to cup loosening (2.0%), neck fractures (1.7%), head loosening (1.0%), head collapse (0.3%), infection (0.3%) and pain (0.3%). The five patients who suffered neck fractures were symptomatic within 3 months of surgery.

We remain cautiously optimistic about the medium term results of hip resurfacing. Careful patient selection is important and caution should be taken in females and patients with DDH

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.

Management of periprosthetic femoral fractures above a Total Knee Arthroplasty remains a challenge. The different treatment options available include casting for undisplaced fractures, ORIF for a displaced fracture with a well-fixed implant or revision arthroplasty for a very distal fracture and for a fracture with a loose implant.

We describe our experience in treating a very distal displaced supracondylar fracture above a well-fixed femoral component in a 68-year-old woman who was recently diagnosed with breast carcinoma and awaiting mastectomy. There was no evidence of metastatic disease. The knee replacement was done 4 years before and the patient did not have any symptoms in the knee prior to the fall. Conventional ORIF with IM nailing or plate osteosynthesis was not possible due to the very distal site of the fracture.

We used a custom modified 95 degree angled blade plate in which a slot was cut in the middle of the blade halfway along its length to accommodate the pegs of the femoral component in the distal fragment. The fracture was reduced and fixed with the angled blade plate restoring length, alignment, and providing coronal stability. The patient had a satisfactory union at 3 months without deformity giving a good range of pain free movement in the knee.

DCS and 95 degree angled blade plate have been used in the past with mixed results. The lag screw or the blade has to be inserted more proximally to avoid the femoral component and so the distal fixation is often sub optimal. In our case modification of the blade allowed more distal placement providing optimal fixation and avoiding complex revision surgery.

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: Accurate templating prior to hip replacement requires that the magnification of the radiograph is known. This magnification is usually measured using a scale marker ball or disc of known diameter, but this method is inaccurate when the marker is not precisely positioned in the coronal plane of the hips.

Our aims were to design a novel scale marker which does not require such precise positioning, and to compare the accuracy of this new marker with a standard single ball marker.

Methods: The new marker consists of two separate markers: one behind the patient’s pelvis, the other at the front. It can be shown that the radiographic magnification of such markers is consistently related to the magnification of the hips.

The posterior marker consists of a 75x75cm square foam mat, incorporating multiple 25.4mm metal rods arranged in series down the centre. The anterior marker is made from five 25.4mm steel balls, linked in series at 20mm intervals. The mat is positioned just underneath the patient’s pelvis as they lie supine for their radiograph. The five balls are placed in the midline over the patient’s suprapubic region, and the x-ray is then taken. The radiographic dimensions of the ball and rod which are located between the hips are then measured. The magnification of the hips may then be calculated from these dimensions using a simple equation.

To validate the new “double” marker, it was compared with a conventional single marker ball. 74 hip arthroplasty patients undergoing routine radiographic follow up were recruited. Both the new double marker and the single marker were applied at the time of x-ray, the magnification according to each was calculated, and these were compared to the true radiographic magnification as determined from the known dimensions of the prosthesis. All markers were positioned by independent radiographers trained in their use.

Results: The correlation between true and predicted magnification was excellent using the double marker (r=0.90), but only moderate for the single marker (r=0.50). The median error of the single marker was 4.8%, but only 1.1% for the double marker (p< 0.001). The reliability of the double marker as a predictor of true magnification was very good (intraclass correlation coefficient, ICC=0.89), but was poor for the single marker (ICC=0.32). The accuracy of the double marker was unaffected by the patient’s body mass index. The inter and intraobserver variability of the new method were both excellent (ICC> 0.94).

Discussion: The double marker method is significantly more accurate and reliable than the single marker method when used in a clinical setting, as it does not rely on precise positioning of the marker by the user. We believe that this technique may become the gold standard method of calculating radiographic hip magnification in clinical practice.

We report serum metal ion level data in patients with unilateral and bilateral hip resurfacing over a ten-year period. In these patients there is an increase in both cobalt and chromium levels above the accepted reference ranges during the first 18 months after operation. Metal ion levels remain elevated, but decline slowly for up to five years. However, the levels then appear to start rising again in some patients up to the ten-year mark. There was no significant difference in cobalt or chromium levels between men and women. These findings appear to differ from much of the current literature.

The clinical significance of a raised metal ion level remains under investigation.

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: Two major complications of hip resurfacing arthroplasty are avascular necrosis of the femoral head and femoral neck fracture. Both are thought to be precipitated by disruption of the blood supply to the femoral head and neck during the approach to the hip joint. Ganz et al have described their technique of approaching the hip joint using a “trochanteric flip” osteotomy. This has the theoretical advantage of preserving the medial femoral circumflex artery to the femoral head. The aim of this study was to compare the intra-operative femoral head blood flow during the Ganz flip osteotomy to the blood flow during a posterior approach for resurfacing arthroplasty of the hip.

Methods: The intra-operative measurements of blood flow were performed using a DRT laser Doppler flow-meter with a 20 mW laser and a fibreoptic probe. The probe was introduced into the lateral femoral cortex and threaded into the femoral head under image intensifier control. Measurements were recorded before the approach to the hip was performed, after the approach was performed but before the head was dislocated, and after the head was dislocated.

Results: Our initial results indicate that there is on average a 50% drop in the blood flow to the femoral head after a posterior approach to the hip joint. In contrast, the trochanteric flip osteotomy produces a much smaller fall of around 18%. We have used these results to inform a sample size calculation, and are currently recruiting further patients to achieve a total of 42 in order to confirm a statistically significant effect.

Conclusion: The Ganz trochanteric flip osteotomy appears to produce less damage to the blood supply to the femoral head during resurfacing arthroplasty than the posterior approach. This study will inform surgeons in deciding on their preference for a routine approach for hip resurfacing.

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 present an independent multi-centre follow-up of metal-metal resurfacing from district regional hospitals (DGHs) in a series of ‘young’ patients with implants from a single manufacturer.

Between November 1995 and November 2002, two hundred and thirteen primary total hip resurfacings were performed in six centres. Two hundred and ten patients were followed up with none lost to follow-up. The average age of the patient group was 52.9 years range (21.9–71.3 years). Of these 210 patients 119 were male and 91 were female. There were three bilaterals and five revisions recorded with a revision rate of 2.3% at seven years. The maximum duration of follow-up was 84 months, the minimum was 3 months and the mean follow-up was 43.5 months.

The average Harris Hip score at the latest follow-up review was 78.15 (range 23–100). The Kaplan-Meier Survivorship of Cormet was 95% at 7 years and a survivorship of 97.38% at three years. These results indicate that metal-metal resurfacing meets the NICE guidelines for suvivorship at the three year benchmark in DGHs with local patients and is on course to meet the 10 year benchmark despite the extremely demanding patient group.

Metal on metal hip resurfacing is increasing in popularity for the young, active patient despite the fact that no long term results are available. The potential advantages of the conservative nature of the prosthesis coupled with the stability of the large diameter bearings and the much reduced wear compared to conventional metal-UHMWPE hips are clear. We present the results of a consecutive series from a single surgeon using a modern device from 1997 to date. All hips used cementless cups and cemented heads and were implanted using a posterior approach. All patients were reviewed annually from the time of operation.

Between September 1997 and March 2004, 345 primary Total Hip Resurfacings were performed by one surgeon. No cases were lost to follow-up. The average age of the patient group was 52 years, range (21–74 years), 190 were male (30 bilaterals) and 104 were female (21 bilaterals) & there were 11 reoperations. The follow-up ranged from 79 months to 3 months, mean follow-up was 29 months. With a Kaplan-Meier survivorship of 94% at 7 postoperative years.

Of the reoperations there were; 5 fractured necks of femur, 3 aseptic cup loosenings, 2 femoral head collapses and 1 joint infection. All 5 femoral neck fractures occurred within 3 months of the primary operation.

This series is one of the longest using a currently available device and the medium term results are encouraging with revision rates occuring within agreed national standards. It should be noted that the numbers of implantations increased as time went on which skews the follow-up slightly. We remain cautiously optimistic about the long term results of this type of device.

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?

Aims: To study clinicoradiological correlation with metal levels in patients with metal-on-metal hip resurfacings. Methods: Serum levels of Cobalt (Co) and Chromium (Cr) in 18 patients undergoing metal-on-metal resurfacing were measured preoperatively and at 6, 12, 24 and 36 months postoperatively. Implants were made of cast Co-Cr alloy. Cr analysis was by graphite furnace atomic absorption spectrometry (ETA-AAS) & Co analysis by inductively coupled plasma mass spectrometry (ICP-MS). Results: Patientsñ mean age: 51.6 years. Average preoperative levels of Cr and Co: 10.5 nmol/l & 7 nmol/l respectively. All patients showed increase in serum cobalt and chromium. Maximum Cr levels increased by 20 fold (range 5–106) and Co by 30 fold (range 3–91) after 12 months in 71% cases. In 69% cases, chromium levels were higher than cobalt levels. Downward trend was noted in 4 cases after 2 years postoperatively. Bilateral cases were similar to unilateral cases. Postoperative HHS was 77.2 (range 50.2–87.6). One dislocated hip had 171-fold increase of Cr and Co by 107 fold. No radiological abnormalities were noted. Conclusions: Increase in serum levels of both cobalt and chromium is due to ñself polishing phenomenonñ correlating with an increase of patientñs physical activity. This may stabilise or show a downward trend after 2 years. The patients with very high levels tended to be relatively young compared to others. Level of activity and age may determine amount of metal release from implanties.

This was an assessment of the clinical and radiological outcome of impaction allografting using morselised cancellous bone allograft in femoral component revision in total hip arthroplasty.

27 consecutive femoral revisions operated on by a single surgeon (SJK) since 1995 were reviewed. Morselised bone allograft was used to reconstitute bone stock deficiency. All patients had cemented Exeter X-change technique Patient selection was primarily based on the amount of preoperative bone loss that was graded according to the Endo-Klinik classification. 10 hips were Endo-Klinik grade 2, 16 hips grade 3 and 1 hip grade 4. Both the components were revised in 18 hips.

The duration of follow up was 12–56 months (average: 33 months) Clinical outcome was assessed using the Charnley modification of Merle d’Aubigné and Postel score. Radiographs were standardised & assessment was done on digitised images of the radiographs using the Image Tool program (Wilcox, Dove, McDavid and Greer, UTHSCSA, Texas, USA).

Charnley’s scores improved from a preoperative score of 2.3, 2.6 and 2.6 to 5.3, 4.2 and 4.8 respectively. Radiologically there were 2 cases of subsidence of > 10mm after 24 months postoperatively. Non progressive radiolucent lines of < 2mm were noted in 7 hips at the cement-graft interface while 3 hips had radiolucent lines at the stem-cement interface. There was satisfactory radiological evidence of bone consolidation in 26 of the cases (95%). There have been 2 re-revisions-1 for dislocation and the other for massive subsidence.

Midterm results showed good functional improvement in hips with preoperative grade 2 and 3 bone loss. We believe this technique is effective in treating major bone loss but may be highly operator dependent.

We compared the success of the screening programmes for congenital dislocation of the hip in two hospitals in the same district, as applied to 68,861 live births over 11 years. Both used only clinical tests on new-born infants. Screening was less successful when the tests were done by junior paediatric physicians than by senior physiotherapists supervised by an orthopaedic surgeon. Clinical screening can be highly effective provided that all babies are screened at birth, and high-risk cases are followed up by a properly trained team with a well-designed protocol.