Primary total hip replacement (THR) in patients with abnormal/altered proximal femoral anatomy/narrow canals presents a technical challenge. There are only limited standard prosthetic stems available to deal with narrow canals or abnormal morphology. Many prefer to use expensive custom implants which often have a lag time to manufacture and do not always have long term published outcomes. We present results of the Asian C-stem (which is a standard implant available on the shelf) used in patients predominantly of Caucasian origin with abnormal proximal femoral anatomy. We retrospectively reviewed clinic-radiological results of 131 patients (131 stems) who underwent primary THR using Asian C-stem at Wrightington Hospital till their latest follow up. Revision for any reason was considered as primary end point. Mean age at surgery was 50.8 years (16 – 80). The 2 commonest indications were primary osteoarthritis (66 patients) and hip dysplasia (54 patients). Mean follow up was 43.5 months with a minimum follow up of 12 months and maximum follow up of 97 months. There were 2 recurrent dislocations and 1 hip subluxed twice. One dislocation needed revision surgery. 1 patient underwent acetabular revision for loosening. There was no stem failure, obvious loosening or loss of fixation in any patients in our series with regards to the Asian C-stem. There were no infections and intra-operative perforations or fractures. C-stem Asian is a reliable implant for patients undergoing THR with abnormal proximal femoral anatomy or narrow canals. Long term follow up is essential

Negative remodelling of the femoral cortex in the form of calcar resorption due to stress-shielding, and femoral cortical hypertrophy at the level of the tip of the implant due to distal load transfer, is frequenly noted following cemented total hip replacement, most commonly with composite beam implants, but also with polished double tapered components. The C-stem polished femoral component was designed with a third taper running from lateral to medial across and along the entire length of the implant, with the aim of achieving more proximal and therefore more natural loading of the femur. The implant is designed to subside within the femoral cement mantle utilising the cement property of creep, generating hoop stresses, which are transferred more proximally to the femoral bone, starting at the level of the medial calcar. The intention is to load the proximal femur minimising stress-shielding and calcar resorption, as well as reducing distal load transfer as signified by the lack of distal femoral cortical hypertrophy. We present the results of a consecutive series of 500 total hip replacements using C-stem femoral components, performed between March 2000 and December 2005 at a single institution. Data was collected prospectively and all patients remain under annual follow-up by a Specialist Arthroplasty Practitioner. The operations were performed using a standard surgical technique with third generation cementing using Palacos-R antibiotic loaded cement. 500 arthroplasties were performed on 455 patients with an average age at the time of surgery of 68.3 years (23-92). There were 282 (62%) female and 173 (38%) male patients with osteoarthritis being the predominant diagnosis. 77 patients have died (73 hips) and the average duration of follow-up for the entire series is 81 months (52-124). Only 2 femoral implants have been revised - one for deep sepsis and the other as part of a revision procedure for a loose acetabulum, although the femoral component itself was not loose. One implant is currently loose following a periprosthetic fracture treated by internal fixation, but none of the remaining implants demonstrates any progressive radiolucencies in any Gruen zones or any features suggestive of current or future loosening. Calcar rounding has been observed, but there have been no cases with obvious loss of calcar height and no cases of distal femoral cortical hypertrophy. The C-stem femoral component has therefore performed well in clinical practice and the objective of eradicating negative bone remodelling has been achieved. The study is ongoing

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. Negative remodelling of the femoral cortex in the form of calcar resorption due to stress shielding and cortical hypertrophy at the level of the tip of the implant, due to distal load transfer, is frequently noted following cemented total hip replacement, most commonly with composite beam implants, but also with polished double tapers. The C-stem polished femoral component was designed with a third taper running from lateral to medial across and along the entire length of the implant, with the aim of achieving more proximal and therefore more natural loading of the femur. The hoop stresses generated in the cement mantle are transferred to the proximal bone starting at the calcar, which should theoretically minimise stress-shielding and calcar resorption, as well as reducing distal load transfer, as signified by the development of distal femoral cortical hypertrophy. Materials/Methods. We present the results of a consecutive series of 500 total hip replacements performed between March 2000 and December 2005 at a single institution, using a standard surgical technique and third generation cementing with Palacos-R antibiotic loaded cement. Data was collected prospectively and the patients remain under annual follow-up. 500 arthroplasties were performed on 455 patients with an average age of 68.3 years (23–92). 77 patients have died (73 arthroplasties) and the average duration of follow-up for the entire series is 81 months (52–124). Results. Only 2 femoral implants have been revised - one for deep sepsis and the other as part of a revision procedure for a loose acetabulum, although the femoral component itself was not loose. One implant is currently loose following a periprosthetic fracture treated by internal fixation, but none of the other remaining implants demonstrates any progressive radiolucencies in any Gruen zones, or any features suggestive of current or future loosening. Rounding of the calcar has been observed, but there have been no cases with obvious loss of calcar height and no cases of distal femoral cortical hypertrophy. Conclusion. The C-stem femoral component has therefore performed well in clinical practice and the objective of eradicating negative bone remodelling has been achieved. The study is ongoing

Triple-tapered cemented stems were developed in the hope that they would reduce aseptic loosening and prevent calcar bone loss. Between March 2005 and April 2008, a consecutive series of 415 primary C-stem AMT hip arthroplasties in 386 patients were performed under the care of three surgeons at our institution. When all the patients had reached the 5-year anniversary of surgery, functional questionnaires were sent out by mail. In the event of non-response, reminders were sent by post before the patients were contacted by telephone. Postoperative radiographs were also reviewed. Follow-up ranges from 60 to 99 months, with a mean of 76 months. 32 hips (8%) were lost to follow-up. The median OHS was 40, median SF-12 mental component score (MCS) was 50, and median SF-12 physical component score (PCS) was 39. Radiographic review showed that aseptic femoral component loosening has yet to be observed. At 99 months follow up, stem survivorship is 96.9% (95% confidence interval (CI) 82.5 to 99.5). Adverse events such as calcar fracture, greater trochanter fracture and dislocation were rare at <1%. The C-stem AMT demonstrates excellent implant survivorship at 5–8 year follow-up, as well as good midterm functional outcome

The triple taper polished cemented stem (C-stem, DePuy) was developed to promote calcar loading, and reduce proximal femoral bone resorption and aseptic loosening. We aimed to evaluate the changes in peri-prosthetic bone mineral density using Dual Energy X-ray Absorbtiometry (DEXA) after total hip arthroplasty (THA) using the C-stem prosthesis. One hundred and three patients were recruited voluntarily through and single institution for THA. The prosthesis used was the triple-taper polished cemented C-Stem (De Puy, Warsaw, Indiana, USA). DEXA scans were performed pre- operatively, then at day for, three months, nine months, 18 months and 24 months post-operativley. Scans were analysed with specialised software (Lunar DPX) to measure bone mineral density (BMD) in all seven Gruen zones at each time interval. Changes in calcar BMD were also correlated with patient age, sex, surgical approach, pre-operative BMD and post-operative mobility to identify risk factors for periprosthetic bone resorption. One hundred and three patients underwent 103 primary THA over a five-year period (98 osteoarthritis; 5 AVN). No femoral components were loose at the two year review and none were revised. The most marked bone resorption occured in Gruen zones 1 and 7, and was best preserved in zone 5. BMD decreased rapidly in all zones in the first three months post-operatively, after which the rate of decline slowed substantially. BMD was better preserved medially (zones 6 and 5) than laterally (zones 2 and 3) at 24 months. There was delayed recovery of BMD in all zones except zones 4 and 5. High pre-operative T-scores (>2.0) in the spine, ipsilateral and contralateral femoral neck were associated with the higher post-operative BMD and less bone resorption at all time intervals in Gruen zone 7. Pre-operative osteopenia and osteoporosis were associated with low BMD and accelerated post-operative bone resorption in zone 7. Patients whose mobility rendered them housebound had lower post-operative BMD, and accelerated post-operative BMD loss in zone 7 when compared to non-housebound patients. Females had a lower post-operative BMD and greater loss of BMD in zone 7. Patient age and surgical approach did not effect post-operative BMD or rate of bone resorption in zone 7. The triple-taper femoral stem design did not show an increase in periprosthetic bone density at the proximal femur at two years post-operative. Calcar bone resorption is accelerated by low pre-operative BMD, poor post-operative mobility, and in females. Age and surgical approach do not have significant effects on calcar bone remodelling

The choice of stem length in total hip revision with impaction bone grafting of femur is essentially based upon the grade of cavitation of femur and surgeon's preference. The standard length stem has been often critiqued for the apprehension of peri-prosthetic fracture. Our study highlights the importance of proximal bone stock rather than distal cavitation in determining the length of femoral stem. 168 total hip revisions of 162 patients with impaction bone grafting and cemented standard C-stem (done with standardized technique) between 1995 and 2008 at a tertiary referral centre were included. Revisions for infection and segmental bone defects were excluded. Serial radiographs were retrospectively analysed by two people independently, using Endoklinik classification, Gruen zones and more and outcomes were analysed. Mean follow-up of the 168 revision hips was 10.5 years (range 5 – 19.1 years). 14 patients (8.3%) were re-revised, reasons being, persistent deep infection (1.8%), repeated dislocations (1.2%), cup loosening (4.8%) and stem loosening (1.2%). Only 1 patient (0.6%) was re-revised due to stem loosening alone. No peri-prosthetic fractures or stem breakage were identified. Use of standard stem length in hip revisions with impaction bone grafting doesn't increase the risk of peri-prosthetic fractures even during long term follow up period. This questions the principle of bypassing the distal cavitation of femur by 2 cortical diameters with the use of long stem. In our experience, a good proximal femur support aids in the performance of standard length cemented stems in revision for aseptic loosening irrespective of grade of distal cavitation for cavitory defects of femur treated with impaction bone grafting

Background. We occasionally come across cortical atrophy of the femur with cemented collarless polished triple-taper stem, a short time after the operation. This study aimed to estimate the radiographs of cemented collarless polished triple-taper stem taken at three, six, twelve, and twenty-four months after the initial operation. Methods. Between May 2009 and April 2011, 97 consecutive patients underwent primary total hip arthroplasty and hemiarthroplasty using a SC-stem or C-stem implant. During the 24 month follow-up, radiographic examination was performed on a total of 95 patients (98 hips). Out of those 95 patients, 52 hips had total hip arthroplasty, 45 had osteoarthritis, 5 had idiopathic osteonecrosis, there were two 2 other cases and 46 hips had hemiarthroplasty for femoral neck fractures. The cementing grade was estimated on the postoperative radiographs. The 24 month postoperative radiographs were analyzed for changes in stem subsidence, cortical atrophy and cortical hypertrophy. According to the Gruen zone, cortical atrophy and cortical hypertrophy were classified on the femoral side. We defined no cortical atrophy as grade 0, cortical atrophy less than 1 mm as grade 1, more than 1 mm and less than 2 mm as grade 2, and more than 2 mm as grade 3. We defined Grade 1 as 1 point, Grade 2 as 2 points, and Grade 3 as 3 points. The points in every zone were calculated, and the average per zone was determined. Result. The mean points of the cortical atrophy adjacent to the stem was 1.19 in THA, and 1.58 in BHA in zone II, 0.98 in THA, and 1.15 in BHA in zone III, 0.34 in THA, and 0.6 in BHA in zone V, and 0.63 in THA, and 0.93 in BHA in zone VI. Statistical significance was found between the two groups (THA and BHA). Stem subsidence slightly increased with time. During the following 2 years there was not a single case with over 1.5mm of stem subsidence. The average stem subsidence after 24 months was 0.72 in THA, and 0.78 in BHA. Cortical hypertrophy was only demonstrated in 5 cases. Discussion. Cortical atrophy was recognized more in the femoral neck fracture group than in the THA group, and cortical atrophy was recognized in zone 2 and zone 3 more frequently than in zone 5 and zone 6. According to the finite element analysis of the SC-stem, more stress is received on the medial aspect of the stem during weight bearing, so it is suspected that more cortical atrophy on the lateral aspect is associated with stem design. These findings are compatible with the cortical hypertrophy reported with Exeter stem in zone 5. Conclusion. Cortical atrophy (cancellizaton) was recognized in 70% of THA group, and in 80% of BHA group, 2 years after the operation. Cortical atrophy in most cases was recognized in Gruen Zones 2 & 3 (P<0.01). Cortical atrophy was found more severely and more frequently in the femoral neck fracture group than the THA group (P<0.01)

Introduction. The long-term wear performance of highly cross-linked polyethylene (HXLPE) in cemented total hip arthroplasty (THA) has rarely been reported. Here we report a prospective randomized comparative analysis of radiographic wear after a minimum follow-up of 10 years in cemented THAs with either HXLPE or conventional polyethylene (CPE), and assess its clinical relevance. Patients and Methods. From 1999 to 2001, we conducted 94 primary cemented THAs with a 22.225-mm head at our hospital as part of a prospective randomized trial. All surgeries were performed using a direct lateral approach with a trochanteric osteotomy (Dall's approach). The patients were divided into 4 groups. Twenty-six hips in group A were implanted with CPE sockets against zirconia heads and Charnley-type stems. HXLPE sockets (Aeonian, Kyocera Medical Corp) were implanted in all hips in the other 3 groups. Twenty-five hips in group B were implanted with zirconia heads and KC stems (Kyocera Medical Corp), 23 hips in group C with zirconia heads and distal cylindrical stems, and 20 hips in group D with stainless steel heads and C-stem (DePuy Inc). The sockets were highly cross-linked by gamma irradiation at a dose of 35 kGy, heat annealed at 110ºC, and sterilized with 25 kGy of gamma irradiation in nitrogen. For radiographic evaluation, anteroposterior radiograms were taken for each patient annually, and every two years postoperatively for wear analyses. Two-dimensional head penetration was measured on each postoperative radiogram using a computer-aided technique. Results. Wear measurements were performed for 59 cases followed up over 10 years. Linear wear rates were 0.138±0.074 (mm/year±SD) for group A, 0.010±0.015 for group B, 0.013±0.020 for group C, and 0.012±0.027 for group D. Linear wear rates differed significantly between group A and other groups, and no significant difference was found among groups B, C, and D. There were four revision cases. Among them, two sockets of group A were revised for aseptic loosening at 7 and 14 years postoperatively with linear wear rates of 0.749 and 0.153 mm, respectively. Two stems of group B and C were revised for aseptic loosening at 10 and 9 years postoperatively with linear wear rates of 0.007 and 0.041 mm, respectively. There were no other cases with aseptic loosening in any group. Osteolysis was found in 10 cases (group A: 7, group B: 1, group C: 1, group D: 1), and there was a significant difference in linear wear rates between the cases with and without osteolysis (0.157±0.083 and 0.030±0.053 mm/year±SD respectively). Discussion. The two revision cases of HXLPE did not have aggressive socket wear, and possibly cement fracture caused osteolysis and stem instability. The results of this study indicate that there is a significant difference in wear rate between CPE and HXLPE, and it was evident that PE wear was associated with osteolysis and aseptic loosening of the socket

Introduction. Varus malpositioning of femoral stems has been recognised as a poor prognostic feature with regard to loosening and failure of cemented composite beam implants, but there have been no published results of the long-term effect on taper-slip designs. Objectives. To determine the results of varus placement of a polished triple tapered femoral stem. Methods. We have prospectively analysed the results of 350 consecutive polished triple-tapered C-Stem implants performed on 322 patients between March 2000 and July 2004, using a standard posterior approach and Palacos-R cement. All patients underwent annual clinical and radiological review. Results. The average duration of follow-up in surviving patients is 140 months (120–172 months). There were 49 femoral implants in 49 patients implanted with more than 5 degrees of varus (14%) with respect to the long axis of the femur, and 14 in 14 patients in more than 5 degrees of valgus (4%). Alignment within 5 degrees of neutral was achieved in 82% of cases. The average age in the varus group was 69.2 years (41–92), which was higher than in the neutral group (67.4 years: 25–89), more patients were male (49% v 36%) but the average BMI was similar (29 v 28). The average duration of follow-up was the same. There was only one re-operation in the varus group, which was a revision for deep infection. There was one dislocation successfully treated by closed reduction and one acetabular component is currently loose. In the neutral group there have been four dislocations, one of which required application of a PLAD; five revisions for aseptic loosening of the acetabular component associated with high wear rates, with a further three currently being loose; four intra-operative, undisplaced fractures of the greater trochanter; two peri-prosthetic femoral shaft fractures treated by internal fixation and two temporary nerve palsies. There has been no aseptic loosening of the femoral components in either group. Subsidence of the femoral stem within the cement mantle was noted in 96% of the entire series. There was no significant difference between the groups with respect to the degree of subsidence. In the varus group 78% subsided less than 2mm compared to 75% in the neutral group. None of the femoral implants in either group subsided more than 4mm and none demonstrated evidence of aseptic loosening or negative bone remodelling. Conclusion. Varus implantation of the femoral component was more common in older, male patients, but there was no increased risk of subsidence or loosening at a minimum follow-up of ten years

Background. We occasionally came across cortical atrophy of femurs with cemented collarless polished triple-taper stem in a short term period. This study aimed to estimate radiographs of cemented collarless polished triple-taper stem taken 6 months after the initial operation. Methods. Between May 2009 and April 2011, 97 consecutive patients underwent primary total hip arthroplasty and hemiarthroplasty using SC-stem or C-stem implants. At the 6 month follow-up, a radiographic examination was performed on 70 patients (71 hips). 44 hips had Total Hip Arthoplasty, 35 had osteoarthritis, 5 had idiopathic osteonecrosis, 2 had other diseases and 27 hips had hemiarthroplasty for femoral neck fractures. The postoperative radiographs were used to estimate the cementing grade. Then the 6 month postoperative radiographs were analyzed for changes in stem subsidence, cortical atrophy and cortical hypertrophy. According to the system of Gruen- cortical atrophy and cortical hypertrophy were classified on the femoral side. We defined no cortical atrophy as grade 0, cortical atrophy less than 1 mm as grade 1, more than 1 mm and less than 2 mm as grade 2, more than 2 mm as grade 3. Result. A cortical atrophy adjacent to the stem was found in zone II according to Gruen on grade 0 thirty-five radiographs (49%), grade 1 twenty (28%), grade 2 eleven (16%), grade 3 five (7%). in zone III grade 0 twenty-seven (38%), grade 1 thirty (42%), grade 2 ten (14%), grade 3 four (6%), in zone V grade 0 fifty (70%), grade 1 twenty (28%), grade 2 one (1%), grade 3 zero (0%), in zone VI grade 0 forty-nine (69%), grade 1 twenty (28%), grade 2 two (3%), grade 3 zero (0%). Cortical hypertrophy was only demonstrated in zone V in one case. In all cases the stem subsidence was less than 1 mm. Cortical atrophy including grade 1 was recognized in 38% of THA, and in 52% of femoral neck fractures. In one case the slight radiolucent line of the postoperative X-ray disappeared after 6 months. Discussion. Cortical atrophy was recognized more in the femoral neck fracture group than in the THA group. And Cortical atrophy was recognized in zone 2 and zone 3 more frequently than in zone 5 and zone 6. According to the finite element analysis of SC-stem more stress is received on the medial aspect of the stem during weight bearing, so it is suspected that more cortical atrophy on the lateral aspect is associated with stem design. This is compatible with the cortical hypertrophy reported with Exeter stem in zone 5. Conclusion. Cortical atrophy, including minor degree atrophy, occurred in 65% of cemented collarless polished triple-taper stem in short term periods after implantation. Cortical atrophy occurred in the lateral aspect of the stem more severely and more frequently than in the medial aspect. Cortical atrophy was also recognized in the femoral neck fracture group more more severely and more frequently than in the THA group