In 2005, we demonstrated that the polished triple-tapered C-stem at two years had migrated distally and rotated internally. From that series, 33 patients have now been followed radiologically, clinically and by radiostereometric analysis (RSA) for up to ten years. The distal migration within the cement mantle had continued and reached a mean of 2 mm (0.5 to 4.0) at ten years. Internal rotation, also within the cement mantle, was a mean 3.8° (external 1.6° to internal 6.6°) The cement mantle did not show any sign of migration or loosening in relation to the femoral bone. There were no clinical or radiological signs indicating that the migration or rotation within the cement mantle had had any adverse effects for the patients.

Cite this article: Bone Joint J 2014;96-B:604–8.

We used roentgen stereophotogrammetric analysis to follow 33 C-stem femoral components for two years after primary total hip arthroplasty. All components migrated distally and posteriorly within the cement mantle. The mean distal migration was 1.35 mm (. sd. 0.62) at two years and the mean posterior migration was 1.35 mm (. sd. 0.69) at two years. All the femoral components rotated into retroversion with a mean rotation at two years of 1.9° (. sd. 1.1). For all other directions, the prosthesis was stable up to two years. Compared with other tapered prostheses, the distal migration of the C-stem is the same, but posterior rotation and posterior migration are greater

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

This is a prospective study looking at 116 consecutive total hip replacements in 110 patients using the C-Stem total hip replacement system (Depuy International, Leeds, UK) between March 2000 and October 2002. This is the first documented study of results of the C-Stem outside Wrightington Hospital where it was developed. There were 69 females and 41 male patients. Average age was 66 years (Range 32 – 89 years). 64 patients had a right hip replacement, 52 patients had a left hip replacement and 6 were bilateral. The duration of follow up was from 24 to 55 months, with an average of 38.75 months. All patients had a cemented C-stem via a posterior approach. 107 with a metal head and 9 with a ceramic head. Cemented, all polyethylene cups were used. 82 hips had an Opera cup inserted and 34 had an Ogee cup inserted. Palacos R with Gentamicin was used for the cement. 103 femoral stems were neutral.12 stems were in varus (5–10 degrees) and 1 stem was in valgus (5–10degrees). No stems were greater than 10 degrees in either direction. There were no lucencies in any of the zones described by Gruen. The average amount of subsidence of the stem was 0.86mm (range 0–4mm). The average cup angle was 44.29 degrees (SD = +/− 4.85). 8 acetabular components had a 0.5mm lucent area in zone 1 and 2 acetabular components had 1mm lucent area in zone 1. All of these lucencies were present on the immediate postoperative x-ray and none were progressive. There were no lucencies in the other zones. There have been no incidences of deep infection, fatal P.E, dislocation or revision. We conclude that the C-Stem has produced excellent results in the short term in keeping with the criteria of the NICE guidelines

Introduction: The C-stem total hip replacement system was devised in Wrightington in 1993 and represented the first triple tapered stem. There is little literature about the follow up outside of Wrightington and therefore we present our data on the C-Stem at a district general hospital. Methods: This is a prospective radiological follow up of patients between March 2000 and November 2004, 250 primary hips were performed by a single surgeon using a posterior approach. Cemented all polyethylene cups were used. Initial and annual x-rays were reviewed and the following measurements were recorded: cup angle; radiolucent lines in the bone-cement interface of the acetabulum; heterotopic ossification; stem subsidence, radiolucent lines or osteolysis in the femoral component and stem orientation. Results: Data is available on 206 hips performed on 185 patients. 107 patients were female and 78 patients were male. 72 were left sided, 92 were right sided and 21 were bilateral. The average age was 66yrs (25–89). Average follow up was 41 months (12–68). The average cup angle was 44.7 degrees. 24 patients had 0.5 mm lucencies in zone 1 of the acetabulum and 1 patient had 1mm lucency in zone 1. No lucencies were progressive. There were no lucencies in any of Gruens’s zones. 18 patients had Grade 1 heterotopic ossification, 2 Grade 2 and 1 Grade 4. 17 stems were in varus and 1 stem in valgus. Average stem subsidence was 0.83mm. Complications were 1 fractured greater trochanter wired intra-operatively and 1 femoral nerve palsy which resolved in 3 months. There were no PE’s, dislocations or deep infections. No hip replacement has required revision. Discussion: We conclude that at a maximum follow up of 5.5 years the C-Stem is performing to standards required by NICE and is on course to achieve the benchmark of 10% revision at 10 years

‘Force-closed’, tapered, polished, collar-less stems, (e.g. C-stem, Exeter), are designed to subside in response to expansion of the cement/bone complex over time. Above a certain threshold, distal migration may predict medium-to-long-term failure of ‘shape-closed’ stems. However, no such threshold exists for ‘force-closed’ stems, and these may continue to migrate after 3 years. We believe that the tendency towards stabilisation 2–3 years postoperatively, could be the best predictor of good long-term performance. Twenty OA patients (12F, mean age 66.6 years) were recruited for primary hip replacement with beaded C-stem femoral components. Tantalum marker beads were injected into the proximal femur, and stems were inserted using CMW1 cement and the latest generation cementing technique via a posterior approach: 17, and a lateral, trochanteric approach: 3. RSA X-ray examinations were performed at 1 week, 6 weeks, and at 3, 6, 12, 24 and 36 months postoperatively. The UmRSA system was used to measure and analyse the radiographs. At 36M the mean stem centroid subsidence was 1.05 mm and had levelled off to a low rate. The mean internal rotation of 2.5° at 36M had not significantly changed during the final year (p = 0.08). At 36M the mean posterior migration of the stem centroid was 0.54 mm (rate of 0.11 mm/y) and posterior migration of the femoral head was 1.66 mm (rate of 0.25 mm/y). At 36M the mean subsidence rate was very low and the mean posterior migration was about one third of that reported for another RSA study of the C-stem. Although the mean internal rotation was greater than that reported for the Exeter stem, there was no significant change during the final year. These low rates of migration at 3 years are consistent with the good results found in clinical studies of this femoral component

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: C-stem is a triple taper polished femoral stem. The rationale for this design is to achieve an evenly distributed proximal loading of the cement mantle. This design is thought to enhance stability of the stem inside the mantle and lead to bone remodelling medially. There is to our knowledge no randomized trial comparing this stem to a well documented stem. We chose to compare it to the best documented stem in the Norwegian arthroplasty register, the Charnley monoblock. Methods: 70 patients scheduled for total hip replacement were randomized to either C-stem or Charnley monoblock. All received a 22 mm stainless steel head, OGGEE cup and Palacos Cement with Gentamycin. We used a transgluteal approach in all cases. Harris and Oxford hip scores were measured preoperatively and after two years. Standard X-rays were taken postoperatively and after two years. Radiostereometry (RSA) was done postoperatively and after 3,6,12 and 24 months. Results: There was no significant difference in Harris or Oxford hip scores after two years. RSA after two years: (table deleted). Discussion: Polished tapered stems are designed to sink inside the mantle. Our results confirm this theory for the C-stem. The subsidence is comparable to other collarless tapered stems with good long-term survival. For all other migrations/rotations the C-stem is as stable as the Charnley monoblock. This predicts good long-term results for this stem

Fractures of the femoral stem component in total hip Arthroplasty have been a well documented complication. The incidence over recent years has decreased due to improvements in both surgical technique and implant design and manufacture. We report two cases of femoral stem fracture. Both occurred in CDH stems from the C-stem system (Depuy International, Leeds, UK). Both patients were women weighing 83kgs and 89kgs at the time of fracture. The fractures occurred at 46 and 24 months respectively. The design of the CDH stem is fundamentally different from the rest of the primary stems with absence of the medial strut. In addition to this factor, both stems fractured through the insertion hole, which acted as a stress raiser. Also of note was the fact that both patients BMI’s were above 25. No weight restrictions have been imposed by the company on this implant. We conclude that if at all possible, a primary C-stem should be inserted but if a CDH stem is used attention to patients’ weight is paramount

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

Introduction: “Force-closed”, tapered, polished, collarless stems, (e.g. C-stem, Exeter), are designed to subside in response to a gradual expansion of the cement/bone complex. Above a certain threshold, distal migration may predict medium-to-long-term failure of “shape-closed” (collared, textured) stems. However, no such threshold exists for “force-closed” stems, and these may continue to migrate after 3 years. We believe that the tendency towards stabilisation 2–3 years postoperatively could be the best predictor of good long-term performance. Method: Twenty OA patients (12F, mean age 66.6 years) were recruited for primary hip replacement with beaded C-Stem femoral components. Tantalum marker beads were injected into the proximal femur, and stems were inserted using CMW1 cement and the latest generation cementing technique via: a posterior approach (17), and a lateral, trochanteric approach (3). RSA X-ray examinations were performed at 1 week, 6 weeks, and at 3, 6, 12, 24 and 36 months postoperatively. The UmRSA system was used to measure and analyse the radiographs. Results: By 36M the mean stem subsidence (1.05 mm) had levelled off to a low rate, and the mean internal rotation (2.5°) had not significantly changed during the final year (p = 0.08). The mean posterior migration of the stem centroid was 0.54 mm and posterior migration of the femoral head was 1.66 mm (0.25 mm/y during final year). Discussion: At 36M the mean subsidence rate was very low, and the mean posterior migration was about one third of that reported by Sundberg et al. (BHS Meeting, 2007). Although the mean internal rotation was greater than that reported for the Exeter stem, it had stabilised during the final year. These low rates of migration at 3 years are consistent with the good results found in clinical studies of this femoral component

Introduction: The C-stem (DePuy, Leeds, UK) is triple tapered, polished and collarless. These features can facilitate distal stem migration within the cement mantle, a phenomenon first noticed on radiographs and later confirmed by radiostrereometric analysis (RSA) for the double tapered polished Exeter stem (Stryker, Mahwah, NJ). Low revision rates are reported for the Exeter stem and the view that early migration predicts later failure has not been confirmed with double tapered designs. If a triple tapered stem has any advantages is however not known. Patients and methods: 33 primary hip arthroplasties with a median age of 66 (46–74) years were followed for 2 years with radiostereometric analysis (RSA) at 3 months, 6 months, 1, 2 and 3 years. The diagnosis was primary osteoarthrosis in all hips. Both migration and rotation were studied. Results: All the stems migrated distally and posteriorly within the cement mantle. The median distal migration was 1.47 mm at 3 years and the median posterior migration was 1.56 mm at 3 years. All the stems rotated towards retroversion and median rotation at 3 years was 2.0°. For all the other directions the prosthesis was stable up to 3 years. Discussion: The C-stem migrates and rotates more than cemented prostheses of other designs. Compared with other tapered prostheses the distal migration is at the same level but posterior rotation is higher and furthermore it migrates posteriorly, which the other tapered stems do not. If this migration/rotation pattern is tolerable without risk of prosthetic failure needs to be studied further, but at present there is no indication from the available clinical results for the C-Stem that this pattern is deleterious

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:. 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. Method: 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. Results:. Sixty nine patients (70 hips) had died and 106 hips had not reached a ten-year clinical and radiological follow-up and had not been revised. In 22 hips, the stem had been changed before the 10 year follow-up, with infection, dislocation and loosening of the cup being the reasons for revision. None of the stems were loose. The remaining 423 hips had a mean follow-up of 11 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 eight hips had been revised at the time of review. The reasons for revision were infection in 5: dislocation in 2: loose cup in 28: wear in 2 and 1 for meralgia paresthetica where the stem was found to be well fixed. In 1 case which had not been revised there was radiological loosening of the stem in a patient with Gaucher’s disease. Discussion: With only 1 stem radiologically loose and no revisions for stem loosening 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

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

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

We present the results of the polished triple tapered C-stem femoral component. Prospective data was collected on a consecutive single surgeon series of 326 hip replacements in 293 patients performed between 2000 and 2005. All operations were performed via the posterior approach with a cemented all polyethylene acetabular component and third generation cementing of the femoral component. There were 169 (58%) female patients and 124 (42%) males. There were 111 (34%) left sided procedures, 149 (46%) right sided and 33 bilateral (10%). Average age at time of surgery was 66.3yrs (25 – 89), with an average duration of follow-up of 50 months (12 – 78). The majority of the replacements were for osteoarthritis (271 hips 83%). Nine patients (10 hips) died during the follow-up period at an average of 36 months (18 – 52), but outcome data was available on all patients and none were lost to follow-up. There was 1 temporary femoral nerve palsy, 2 non-fatal pulmonary emboli and 3 undisplaced trochanteric fractures. There were no dislocations, fatal pulmonary emboli, deep infections or revisions for any reason. The stem was neutral in 90%, varus in 8% and valgus in 2%. There were no progressive radiolucencies in any Gruen zones and no distal femoral cortical hypertrophy. The average subsidence was 0.83mm, with none in 21%, < 0.5mm in 28%, 0.5 – 1mm in 41%, 1 – 2mm in 8% and 2 – 4mm in 2%. There were no revisions and no stems demonstrated any features suggestive of current or future loosening. The study and prospective data collection is ongoing

The use of polished femoral implants employing the taper-slip philosophy now dominates the cemented portion of the hip arthroplasty market in the United Kingdom. Despite this fact, there have been very few published or presented series reporting the medium to long-term results of double tapered implants and only one previously reported series looking at the results of the triple tapered stem. We present the results of 500 consecutive polished triple tapered C-stem femoral components performed in 455 patients. All operations were performed using a posterior appproach, with cemented all polyethylene acetabular components and the use of third generation femoral cementing techniques, restrictors, centralisers and Pala-cos-R cement. There were 282 female patients (62%) and 173 males (38%). The average age at the time of surgery was 68.3 years (23 to 92), with an average duration of follow-up of 71 months (36 to 112). 47 patients (51 hips) died during the follow-up period at an average of 54 months (1–87). There were 3 dislocations, 2 on one occasion and one twice, at an average of 4 years. There were 2 deep infections, one of which required revision, and 4 non-fatal pulmonary emboli. There were 3 undisplaced trochanteric cracks treated by cerclage wiring and 3 nerve palsies: 2 femoral (temporary) and one sciatic (permanent). There was only one case of significant heterotopic ossification (Brooker Class 4). The stem was neutral in 89% of cases, varus in 7% and valgus in 4%. Subsidence within the cement mantle occurred in 79% of cases, with an average of 0.87mm. 9 stems subsided 2 to 4mm but all stopped at 2 years and there was no further subsidence thereafter. One hip was revised for deep infection but none of the remaining implants demonstrated any progressive radiolucencies in any Gruen zones and none demonstrated any features suggestive of current or future loosening. There was no evidence of negative bone remodelling. The data was collected prospectively and the study is ongoing

Introduction: The C-Stem was introduced in the endeavour to achieve greater stability, improved fixation, minimise subsidence and improve loading of the proximal femur to maintain bone quality and avoid stress shielding. Since promising early results in 2001, no studies including a large patient population from a single surgeon series have been published. Methods: Health records and imaging modalities of 260 patients, operated between 2001 and 2004 were retrospectively evaluated by 2 independent reviewers. All patients had antero-lateral approach in supine position. Clearing of the calcar was carried out to allow adequate cement mantle proximally and posteromedially. Tip of the stem was allowed to penetrate in to the intramedullary bone block. All patients were followed up regularly with clinical and radiological information being updated. Results: 90 men and 170 women, 30 bilateral cases were identified. Mean age at the time of surgery was 61.8 years (50–91). Commonest diagnosis was primary OA (56%) followed by secondary OA due to AVN or childhood pathology (30%) and previous trauma. 43 patients had previous operations in the form of failed internal fixation, osteotomy or hemiarthroplasty. Assessment included oxford hip score. Radiographs digitalised on DICOM software were analysed for subsidence (0.7 mm), alignment (94% satisfactory), bone-cement interface changes (35% progressive improvement) and proximal femur stress shielding (2.1%). At the time of final follow up 89% were independently mobile. 4 % thigh pain, 3 revisions for recurrent dislocations, 3 nonfatal and 2 fatal pulmonary embolism. Taking death or revision for any reason as endpoints, 97.8% survivorship was noted using Kaplan-miere analysis. Discussion: The strength of the study includes large patient population, completeness of follow up and single surgeon series eliminating compounding factors. Bone cement interface improvement was noted in younger patients with high activity level. The study consolidates the soundness of the concept of C-Stem