Introduction

We present the outcome of 297 acetabular revisions using bone grafting and cemented acetabular components in 297 patients, with a mean follow-up of 8 years 3 months (5–20 years).

The C-Stem in its design as a triple tapered stem, is the logical development of the original Charnley flat-back polished stem. The concept, design and the surgical technique cater for a limited slip of the stem within the cement mantle transferring the load more proximally.

Five thousand two hundred and thirty three primary procedures using a C-stem have been carried out since 1993. We reviewed all 621 cases that had their total hip arthroplasty before 1998.

Sixty nine patients (70 hips) had died and 101 hips had not reached a ten-year clinical and radiological follow-up and had not been revised. Thirty-two hips had been revised before 10 years, none were revised for aseptic stem loosening and no stems. The indications for revision were Infection in 4, dislocation in 3, aseptic cup loosening in 24 and unexplained pain in 1.

The remaining 418 hips had a mean follow-up of 12 years (range 10–15 years). There were 216 women and 173 men, and 34 patients had bilateral LFAs. The patients' mean age at surgery was 53 years (range 16–83 years). Thirty four hips had been revised at the time of review. The reasons for revision were infection in 5, dislocation in 2, aseptic cup loosening in 24 and 1 for neuralgia paraesthetica where the stem was well fixed. Two hips were revised for stem fracture.

There were no revisions for stem loosening but 2 stems were revised for fracture - both with a defective cement mantle proximally. The clinical results are very encouraging and they support the concept of the Charnley cemented low friction arthroplasty, but place a demand on the understanding of the technique and its execution at surgery.

Introduction: Leg length discrepancy in general and leg lengthening in particular has emerged as a topic of interest and a common cause for litigation

Theoretical considerations: Painful mobile hip functions in abduction. The load on the hip is reduced by pelvic tilt to the symptomatic side. For this to be possible the proximal lever - the head neck and the acetabulum - must be relatively intact.

Methods: A method to identify patients at risk for limb lengthening after total hip arthroplasty by establishing the aetiology of abduction deformity of the osteoar-thritic hip.

Clinically: by pelvic tilt to the symptomatic side apparent limb lengthening, restriction of adduction.

Radiologically: by a relatively well preserved geometry of the hip and infero-medial femoral “head –drop” osteophyte.

Results: In a group of 5000 patients presenting for primary Charnley low-frictional torque arthroplasty: 182 (3.64%) 80 males, 102 females, mean age 63 (20–80) were identified as being at risk for post-operative limb lengthening.

Aetiology – Primary: Unilateral 130, Bilateral 10.

– Secondary: Post-surgery 23, post-trauma 10, spinal 6, mixed 3.

122 (67%) had apparent limb lengthening – mean 3.2% and in 43 (24%) limb lengths were equal, 91% had a well preserved architecture and the proximal lever system.

Discussion: The tell tale signs in patients at risk for limb lengthening after total hip arthroplasty are: pelvic tilt to the symptomatic side with apparent limb lengthening, restricted adduction, history of backache, well preserved hip structure and normal contralateral hip.

Conclusion: Awareness of the pattern identifying patients at risk, detailed pre-operative assessment, avoidance of capsule excision and tight hip reduction are essential.

With an increasing number of primary total hip arthroplasties being carried out worldwide, and a lack or inadequate follow-up leading to delays in revision surgery, more complex problems including periprosthetic fracture have to be dealt with at revision surgery.

Unawareness, that clinical results do not reflect the mechanical state of the arthroplasty, together with strain shielding in the femur, progressive endosteal cavitation and stem migration may result in deterioration of the periprosthetic bone stock and femoral fracture.

Acute onset due to the fracture, severe symptoms and poor medical status of the patient usually demands immediate surgical intervention.

We have developed a modular cemented femoral component for revisions where deficiency of the proximal femur, or the femoral fracture, demands a variable extra-femoral portion of the stem. The shaft of the stem is 200mm or longer allowing the extra-medullary position to vary up to 15cm. It has a double polished taper

Between 1985 and 2007 the stem has been used in 79 revisions where there was a periprosthetic fracture. The mean age at surgery was 70 years (37–93) and the mean follow-up was 4 years (0–14 years 10 months). In 86% the primary surgery had been performed at another hospital. In 80% the fracture had united at one year. The main post-operative problem was dislocation in 10 cases between 7 days and 9 years after revision and was most common where the abductors were absent. 2 patients died in the post-operative period. Five hips have been re-revised, 3 for dislocation, 1 for Infection and 1 stem loosening.

Overall revision for periprosthetic fracture using this implant has given good results.

Although the results of this type of surgery are encouraging, this must not be considered as an alternative to regular follow-up and early intervention in cases where progressive loosening and deteriorating bone stock are likely to lead to a more demanding surgery.

One of the most serious complications of THA is deep infection.

Charnley realised the problem. This led to the development of clean air enclosure, total body exhaust suits and the introduction of the instrument tray system. Subsequently antibiotics were used both systematically and also as an addition to the acrylic cement. Occasional deep infection requires further intervention, either by removing the implant, or performing one or two stage revision. It has been the senior author’s practice to undertake one-stage revision provided the bone stock was of sufficiently good quality to ensure reasonable quality of component fixation. The technique is based on the accepted principle of infection management: Removal of all foreign body material and infected tissues, application of local antiseptics/antibiotics, closure of cavities, ensuring stability, drainage, rest, continuation of antibiotics.

Between January 1974 and December 2001, 185 one-stage revisions were carried out by the senior author: 162 had a minimum follow-up of 5 years with a mean of 12.3 years (5.1–27.6 years). 138 cases (85.2%) were free from infection. Presence of a sinus at revision did not affect the outcome adversely – on the contrary – 90.4% were infection free as compared with 82.7% of those without a sinus.

Attention to detail was the essential part of the operation.

Aims: The distal radius fracture model prototype has been produced as a means for teaching reduction of a distal radius fracture. In this study we aim to test the repeatability and reproducibility of the force required to correct the shortening of the radius. In addition a questionnaire was carried out to assess face validity

Methods and materials: The distal radius fracture model prototype has been designed and manufactured to simulate reduction of a dorsally displaced, radially angulated, shortened fracture of the distal radius. We designed a mounting rig for the model and used a Hounsfield tensometer to measure the degree of movement of the distal fracture fragment when various degrees of force were applied. Force was applied to reproduce correction of radial shortening. Reproducibility was tested by resetting of the tensioning device at the rear of the model. The questionnaire was constructed using a series of 5 point, verbally anchored Likert items.

Results: Mean force required for reduction was 191.4 N (Newton) (range 189.4 – 193.4N). Standard deviation for repeated measurement was 1.65 N. Graphs of force versus extension showed one consistent point of slippage which could be explained by movement in the spring tensioner for distal radial displacement. On repeated testing the model tensioning device also showed good reproducibility of results. The results for face validity showed that most people rated the model as having an appearance consistent with that of a fractured distal radius (median score for appearance 4.7, tactile propertied 4.7) but that the biomechanical properties of the reduction were not scored as highy (median score 3.9) The median score when asked about the usefulness of the model for teaching junior staff was high (4.52)

Conclusions: This prototype produces repeatable performance parameters on reduction of the fracture. Overall experience with the prototype is good but it requires further refinement.

Introduction: The triple tapered polished cemented C-stem has evolved from the study on long-term results of the Charnley design, when first fractures of the stem and then proximal strain shielding of the femur and stem loosening were identified as the continuation of the same process. The design utilises the common engineering principle of male (stem) and female (cement) tapers engaging under load, loading the proximal femur.

Methods and Results: The C-stem was tested extensively and introduced into clinical practice in December 1993. Up to the end of October 2007, 4558 have been implanted in primary operations.

None of the 4558 stems have been revised for aseptic loosening or fracture.

The patient’s mean age at surgery was 48 years (range 15–76), and 171 hips with a mean follow-up of 11 years (range 10–13.7) have now passed 10 years. There were 97 females and 64 males in this group with 10 patients having bilateral C-stems. The main underlying pathologies were Primary Osteoarthritis 30%, Developmental Dysplasia of the hip 27% and Avascular Necrosis of the hip 19%.

Clinical outcome graded according to d’aubigne and postel for pain, function and movement has improved from 3.1, 3.1 and 2.9 to 5.9, 5.7 and 5.6 respectively.

A good quality proximal femur had been maintained in 47.1% and improved in a further 29.9%.

Discussion: The results achieved with the C-Stem design and technique are encouraging and support the concept of loading the proximal femur, but place a demand on the understanding of the technique and its execution at surgery.

Introduction. Presentation of results by survivorship analysis method offers uniformity of terminology and comparability of results, an essential aspect of scientific communication. The Swedish National Total Hip Arthroplasty Register (SNTHAR) has set the standards with revision as the failure endpoint.

We set out to examine the survivorship after primary Charnley low-frictional torque arthroplasty (LFA) with revision as the end point, but documenting all the operative findings.

Methods & Results. Between November 1962 and June 2005, 22,066 primary operations in 17409 patients had been carried out at the author’s hospital by over 330 surgeons. By June 2006, 1001 (4.5%) hips have been revised.

Survivorship with revision as the end point was: infection 95%, dislocation 98%, fractured stem 88.6%, loose stem 72.5%, loose cup 53,7%.

Infection and dislocation are early problems. With improved cementing techniques stem loosening does not become a problem until 11 years after the primary. Loosening and wear of the ultra high molecular weight polyethylene cup is a significant long-term problem.

Discussion. Since revision is an event interrupting a process, its timing will influence the survivorship analysis pattern and indications and detailed operative findings will become important issues. Since clinical results do not reflect the mechanical state of the arthroplasty to await symptoms would invariably mean that revisions are likely to be carried out late and as such the complexity of complications are likely to increase. Furthermore, if information gathered is of a single “indication for revision”, and not of the operative findings at revision, the information would be of limited value.

Our conclusion is that regular follow-up after hip replacement is essential. The frequency, judged from the revision patterns, would suggest that every two years would not be unreasonable. Recording of all operative findings at revision is essential.

The Triple-tapered cemented polished C-Stem has evolved from the study of long-term results of the Charnley low-frictional torque arthroplasty when the first fractured stem and then proximal strain shielding of the femur and stem loosening were identified as the continuation of the same process- the lack or loss of proximal stem support.

The concept, design and the surgical technique cater for a limited slip of the C-stem within the cement mantle transferring the load more proximally. With a follow-up past 12 years and 4063 primary procedures there have been no revisions for aseptic stem loosening and no stem is radiologically loose.

We have reviewed 1008 primary C-Stem hip arthroplasties performed by 23 surgeons with a minimum of 5 years clinical and radiological follow-up. The mean follow-up was 7 years (range, 5 – 12) and the mean age at surgery was 57 years (range (15 – 85). In 58% the underlying pathology was primary osteoarthritis, 20% congenital dysplasia, 10% quadrantic head necrosis, 5% rheumatoid arthritis, 5% slipped upper femoral epiphysis and 4% protrusio acetabulae.

The concept of the triple tapered stem is validated radiologically with an improved proximal femoral bone stock in over 20% of cases and a maintained bone stock in 60%.

There were no post-operative complications within 1 year in 87% and no late complications (after 1 year) in 91%. The main late complications were 3.9% aseptic cup loosening, 1% infection and 0.8% dislocation. There were no aseptic loose stems.

Twenty-eight hips have been revised (2.8%), 3 for infection, 2 for dislocation and 23 for aseptic cup loosening. There were no revisions for aseptic stem loosening.

The results support the concept but place a demand on the understanding of the technique and its execution at surgery.

We report the results of our continued review of 11 hip arthroplasties using 22.225mm alumina ceramic femoral heads (CCH) on a Charnley flanged stem articulating with a chemically cross-linked polyethylene (XLPE) cup. The initial bedding-in of up to 0.41mm, which was reached within about 2 years, has not progressed further with a follow up to 18.1 years. The mean total penetration of the XLPE cup for this group of patients is 0.31mm (0 – 0.41) and a penetration rate of 0.019 mm/year (mean 0 – 0.026). One patient with CCH/XLPE arthroplasty on the left side and a conventional metal on ultra high molecular weight polyethylene (UHMWPE) on the right side, has a ten fold difference in total penetration: 0.41mm compared with 4.1mm and a year shorter follow-up.

The mean age of the 9 patients (11 hips) attending was 47.2 years (26–58) at the operation and is now 64 years (42–73). Clinical results remain excellent with freedom from pain and normal activity level appropriate to their age and gender.

Radiographically none of the cups or stems show evidence of loosening or osteolysis and there have been no problems that could have been attributed to the materials or the design used.

Triple-tapered cemented polished C-Stem has evolved from the study of long-term results of the Charnley low-frictional torque arthroplasty when the first fractured stem and then proximal strain shielding of the femur and stem loosening were identified as the continuation of the same process: lack or loss of proximal stem support.

The C-Stem, by the concept, design and the surgical technique, caters for a limited slip of the stem within the cement mantle transferring the load more proximally. With a follow-up past 10 years and 3299 primary procedures there have been no revisions for aseptic stem loosening and no stem is radiologically loose.

Four hundred and forty eight patients had 500 LFAs using the C-Stem with the longest follow-up: 256 women and 192 men; 52 patients had bilateral LFAs. The patients’ mean age at surgery was 55.5 years (range 17–89 years) and at a mean follow-up of 5.2 years.

There was an overall improvement in the clinical outcome graded according to d’Aubigne and Postel for pain, function and movement from 3.1, 2.9 and 2.8 to 5.9, 5.7 and 5.5 respectively.

A good quality proximal femur had been maintained in 56.8% and improved in 21.8%.

The results are encouraging and support the concept but place a demand on the understanding of the technique and its execution at surgery.

Factors influencing the results of revised cemented sockets with bone grafting have been studied in 249 cases.

Freeze-dried allografts in 77 and fresh frozen in 172 cases have been used. The average follow-up was 8 years 11 months for the freeze-dried group and 2 years 11 months for the fresh frozen cases. There were 13 postoperative dislocations, 20 TNU, 4 thromboembolic complications, 4 delayed wound healing and 2 intraoperative fractures of the acetabulum. There have been 11 re-revisions: 8 for aseptic loosening, 2 for dislocation and 1 for infection. Radiographic evidence of loosening was seen in another 38 cases.

The acetabular bone stock at the time of revision and initial stability of socket fixation had a significant influence on the outcome. Direction of socket migration before surgery appeared to predict risk of failure. The primary pathology, type of bone graft and grafting technique also had an effect.

We previously reported the result of 45 Charnley LFA’s with femoral head autograft for Developmental Dysplasia of the hip with a minimum follow-up of ten years.

After an average follow-up of eleven years there was no revision. One socket migrated and four sockets were fully demarcated.

To assess our long-term results we reviewed the clinical and radiological findings in the same group of patients that had been studied previously.

To date 5 patients died from causes unrelated to the hip replacement and were excluded from the final radiological analysis. 40 Charnley LFA’s have been followed-up regularly.

The average follow-up is now 17 years 1 month / range: 15–21 years/. Three sockets have been revised: two for aseptic loosening and one for infection. Radiographic assessment showed that three sockets migrated and four had full demarcation.

Demarcation at the cement-bone interface of the socket was rare in zone one but was common in zone two.

We concluded that sound fixation of the autograft and orientations of the acetabular component are essential. We recommend that solid bone graft should be combined with impaction bone grafting in dysplastic cases. We also observed that bone grafting at primary surgery gives better chances for component fixation at the time of revision.

Introduction and Aims: The purpose of this study was to assess pre-operative bone stock and immediate postoperative cement-bone interface as factors affecting infection control and mechanical outcome after one stage revision THR for deep infection.

Method: This study included 115 cases which satisfied the following conditions: 1) One stage revision THR for deep infection was the primary intervention for infected hip replacement by a single surgeon (BMW) unless the bone stock was too poor for fixing implants; 2) follow-up of more than five years; 3) A complete series of radiographs was available for radiological study including pre-operative and immediate post-operative ones. Pre-operative bone stock was classified into four grades (Grade 0: No bone loss, Grade 1: Demarcation, Grade 2: Localised cavitation, Grade 3: Extensive bone loss). The immediate post-operative cement-bone interface was also graded into four categories (Grade A: White-out, obscure interface, Grade B: Clear line, no measurable gap, Grade C: Gap> 1mm, Grade D< 1mm). These two factors were analysed with regard to infection control and the mechanical survival of implants after surgery.

Results: Bone stock did not have significant influence on infection control, while it did affect mechanical outcome. The cement-bone interface was an affecting factor for not only the mechanical survival of implants but also the cure of infection.

Conclusion: There was a good chance of curing the infection even with extensive bone loss. Good cement fixation was an important factor with regard to infection control, as well as the mechanical survival of implants. The results suggested that it was important to shield the medullary space from the infected joint space with antibiotic-loaded cement in revision THR for deep infection.

Limb length discrepancy (LLD) is a complication of total hip arthroplasty (THR). We reviewed the x-rays of patients who underwent THR in our unit to establish the incidence and magnitude of LLD, and try to identify reasons why a length discrepancy arose. Patients with abnormalities of the opposite hip (previous THR, significant osteoarthritis) were excluded, to allow comparison with a normal contralateral side.

100 consecutive patients who fulfilled these criteria were included. There were 38 male and 62 female patients. The implants used were Charnley (89 cases), Elite (4 cases), and Exeter (7 cases). The following measurements were made on pre-and post-operative films on the hospital PACS system: centre of lesser trochanter to ischial tuberosity; tip of greater trochanter to centre of femoral head; centre of head to base of teardrop. The distance from the osteotomy in the femoral neck to the centre of the lesser trochanter was also measured. The interval from the greater trochanter to the closest margin of the pelvis, and the interval from the lesser trochanter to the base of the teardrop (compared to the normal side) were recorded as indices on adduction. Surgery was performed via a direct lateral (Hardinge) approach (95 cases) or through transtrochanteric approach (5 cases).

There was a radiographic difference between limbs of > 1cm in 43 cases; in 9 of these, the operated limb was longer, and in 34 cases it was shortened. In those cases where the operated side was lengthened, the cause was on the acetabular side in 2 patients, and on the femoral side in 25 cases, and on the femoral side in 9 cases. The shortened limb was noted to be adducted relative to the opposite side in 29 patients. There was difference noted in the incidence of discrepancy between different implants. The transtrochanteric approach was associated with significantly (p< 0.01) less length discrepancy.

Our findings suggest that shortening is much more common than lengthening following THR, and that incorrect positioning of the acetabulum is the more likely cause. Persistence of an adduction contracture may also contribute to an apparent shortening postoperatively. The transtrochanteric approach appeared to make LLD less likely. Surgeons should be aware of these findings when performing THR. The clinical effect of differing degrees of LLD is till debatable.

Breech presentation is historically associated with an increased incidence of hip Dysplasia (6.6%–9.6%), but the effect of vaginal breech delivery on the development of hip dysplasia is unknown. In the Irish Republic, the proportion of breech presentations delivered by caesarean section is now over 90%. If the mechanical trauma of vaginal delivery is a significant event in the aetiology of DDH in breech presenters, caesarean section should be protective. We tested this hypothesis by a prospective study in infants presenting in the breech position who were delivered by caesarean section, during the 2002 calendar year.

There were 108 infants in the breech position at the time of delivery during this period; all but two of these (excluded from the study) were delivered by caesarean section. 50 were male and 56 were female. The mean duration of pregnancy at delivery was 37 weeks. An initial examination was performed in all cases within the first 48 hours postpartum, and treatment in a Pavlik harness commenced where there was clinical instability. Standardised AP and BIR views of the pelvis were taken at 4 months after birth, in all 106 cases. The acetabular index (AI) was measured on both sides.

There was only one case of hip dislocation at birth (bilateral dislocation in a first-born female infant). In 7 cases the initial examination was suspicious for instability, and patients were treated in Pavlik harness; in five of these cases another recognised risk factor (first-born female, family history) was also present. Two of these cases were found to have evidence of instability at 4 months, and underwent treatment by closed reduction and spica casting. For the entire group, the mean acetabular index (212 hips) was 23 degrees (range 17 to 36 degrees). Among those with signs suggestive of instability, the mean AI was 28 degrees. Only one patient had an AI > 30 degrees. Among those with no other risk factors, the mean AI was 22 degrees (range 17 to 28).

Our prospective study suggests that the incidence of DDH is markedly lower in breech presenters delivered by caesarean section (< 3%) that that reported for breech presenters as a whole. The three patients in our group with DDH had other risk factors present. We conclude that caesarean section may be protective for the development of DDH in infants who present in the breech position.

The Extensor Digitorum Brevis is an easily visualised superficial muscle present on the dorsolateral aspect of the foot. It is innervated by the terminal branches of L5. Wasting of this muscle has been described as a sign of L5 radiculopathy, however its specificity and sensitivity as a clinical sign in patients with disc disease has never been assessed to the best of our knowledge.

The purpose of our study was to determine the effectiveness of this sign in patients with a know L5 radiculopathy. We included three groups of patients, which were prospectively assessed by a blinded single examiner. Group A were patients with a clinical L5 radiculopathy confirmed on MRI, Group B were patients with a clinical a S1 radiculopathy confirmed on MRI and Group C were a control group. There were 20 patients in each group, 10 male and 10 female, mean age 38 years (range 19 – 57 years). Our inclusion criteria were leg pain greater than 6 weeks, we excluded and patient with a history of previous disc disease or foot surgery. A positive sign was defined as a gross clinical wasting of the extensor digitorum brevis compared to the opposite foot.

The sign was negative in all 20 patients in the control group. The sign was positive in 12 patients (60%) with L5 radiculopathy and only one patient (5%) with S1 radiculopathy. Fishers exact test confirmed statistical significance between the two groups with a p value of < 0.05.

We conclude that this easily performed objective clinical sign, when used inpatients with leg pain, is highly specific in determining the pressure of an L5 root involvement.

Purpose: The purpose of this study was to assess preoperative bone stock and immediate postoperative cement-bone interface as factors affecting infection control and mechanical outcome after one stage revision total hip replacement (THR) for deep infection.

Material and methods: This study included 115 cases which satisfied following conditions; a) One stage revision THRs for deep infection were carried out by a single surgeon (BMW). b) Follow-up of more than five years was possible. c) Complete series of radiographs were available including preoperative, immediate postoperative and the latest follow-up ones. Preoperative bone stock was classified into four grades (Grade 0: No bone loss, Grade 1: Demarcation, Grade 2: Localized cavitation, Grade 3: Significant bone loss). Immediate postoperative cement-bone interface was also graded into four categories (Grade A: White-out, obscure interface, Grade B: Clear line, no measurable gap, Grade C: Gap> 1mm, Grade D< 1mm). These two factors were analysed in view of infection control and mechanical survival of implants after surgery.

Results: Preoperative bone stock did not show significant influence on infection control while it affected mechanical outcome. Immediate postoperative cement-bone interface was an affecting factor for not only mechanical survival of implants but cure of infection.

Conclusion: Preoperative bone stock and immediate postoperative cement-bone interface were assessed as influential factors in one stage revision THR for deep infection. There was a good chance of cure of infection even in cases with significant bone loss. Good cement fixation appeared to be important in view of infection control as well as mechanical survival of implants.

We report the result of 49 revisions for aseptic cup loosening using freeze-dried allografts.

We assessed the results according to the primary pathology, severity of bone loss, direction of socket migration before revision, method of bone grafting, socket position, graft incorporation and socket loosening.

Patient’s mean age at revision was 56 years 8 months. At a mean follow up of 7 years and 5 months four cups have been revised for aseptic loosening. Five sockets have migrated but remained stable while six showed full demarcation but have not migrated.

The other 34 remained stable and show radiographic evidence of graft incorporation.

Deep infection is one of the most serious complications after total hip replacement (THR). The aim of this study is to evaluate the efficacy of one stage revision THR for deep infection with a long-term follow-up.

One stage revision THR for deep infection was carried out in 285 joints on 274 patients by a single surgeon (BMW) between 1974 and 2001. All infected hip replacements are primarily treated with one stage revision THR at the authors’ unit unless bone stock is extremely poor. This study included a review of 162 revisions in 154 for which a minimum follow-up of five years had been done. The mean duration of follow-up was 12.3 years.

Trochanteric osteotomy was done for extensive resection of infected tissue and removal of cement. Both cups and stems were revised with bone cement. Antibiotic-loaded cement was used in 152 cases (93.8%). Further antibiotics were commenced systemically for 6–12 weeks postoperatively.

Failure of infection control was defined as a) reoperation for recurrent infection or b) clinically persistent infection. Infection control. One hundred and thirty eight hips (85.2%) were free of infection at the time of the latest follow-up. 1) No sinus group (N=110): Success rate was 82.7 %. 2) Sinus group (N=52): Success rate was 90.4 %.

This study presents the longest follow-up with a large number of cases in revision THR for deep infection. At least, history of discharging sinus was not considered as a contraindication. The results suggested that one stage revision was an effective treatment for deep infection of hip replacement in the long term.