Introduction

In recent years, there has been a significant advancement in our understanding of femoro-acetabular impingement and associated labral and chondral pathology. Surgeons worldwide have demonstrated the successful treatment of these lesions via arthroscopic and open techniques. The aim of this study is to validate a simple and reproducible classification system for acetabular chondral lesions.

Introduction: In recent years, there has been a significant advancement in our understanding of femoro-acetabular impingement and associated labral and chondral pathology. Surgeons worldwide have demonstrated the successful treatment of these lesions via arthroscopic and open techniques. The aim of this study is to validate a simple and reproducible classification system for acetabular chondral lesions.

Methods: In our classification system, the acetabulum is first divided into 6 zones as described by Ilizalithurri VM et al [Arthroscopy 24(5) 534–539]. The cartilage is then graded as 0 to 4 as follows: Grade 0 – normal articular cartilage lesions; Grade 1 softening or wave sign; Grade 2 – cleavage lesion; Grade 3 – delamination and Grade 4 -exposed bone. The site of the lesion is further typed as A, B or C based on whether the lesion is 1/3 distance from acetabular rim to cotyloid fossa, 1/3 to 2/3 distance from acetabular rim to cotyloid fossa and > 2/3 distance from acetabular rim to cotyloid fossa.

For validating the classification system, six surgeons reviewed 14 hip arthroscopy video clips. All surgeons were provided with written explanation of our classification system. Each surgeon then individually graded the cartilage lesion. A single observer then compared results for observer variability using kappa statistics.

Results: We observed a high inter-observer reliability of the classification system with a kappa coefficient of 0.89 (range 0.78 to 0.91) and high intra-observer reliability with a kappa coefficient of 0.91 (range 0.89 to 0.96).

Discussion: In conclusion we have developed a simple reproducible classification system for acetabular cartilage lesions.

There have been considerable recent advances in the understanding and management of femoroacetabular impingement and associated labral and chondral pathology. We have developed a classification system for acetabular chondral lesions. In our system, we use the six acetabular zones previously described by Ilizaliturri et al. The cartilage is then graded on a scale of 0 to 4 as follows: grade 0, normal articular cartilage lesions; grade 1, softening or wave sign; grade 2, cleavage lesion; grade 3, delamination; and grade 4, exposed bone. The site of the lesion is further classed as A, B or C based on whether the lesion is less than one-third of the distance from the acetabular rim to the cotyloid fossa, one-third to two-thirds of the same distance and greater than two-thirds of the distance, respectively. In order to validate the classification system, six surgeons graded ten video recordings of hip arthroscopy.

Our findings showed a high intra-observer reliability of the classification system with an intraclass correlation coefficient of 0.81 and a high interobserver reliability with an intraclass correlation coefficient of 0.88.

We have developed a simple reproducible classification system for lesions of the acetabular cartilage, which it is hoped will allow standardised documentation to be made of damage to the articular cartilage, particularly that associated with femoroacetabular impingement.

Juvenile idiopathic arthritis (JIA) affecting the hip can cause debilitating pain and walking disability in children. Total hip replacement offers the potential of a pain free joint and a significant improvement in function. There remains the concern regarding the high rates of aseptic loosening of cemented total hip replacements in this group of patients, and there is evidence that younger patients have higher failure rates.

The aim of this study was to look at the results of uncemented total hip replacement in children with Juvenile Idiopathic Arthritis and in particular to assess any problems associated with performing this surgery in the presence of open growth plates in the acetabular and trochanteric regions.

Between 1995 and 2005, 56 uncemented total hip replacements were carried out in 37 children with JIA with a mean follow up of 7.5 years (range 3 to 12.5). 25 of the hips had ceramic on ceramic bearings. The mean age at surgery was 13.9 years (range 11–16). 19 patients underwent bilateral procedures. All patients showed a significant improvement in their HSS Hip scores (p< 0.01). Two CAD CAM femoral stems were revised for gross subsidence and three acetabular components were revised for loosening. Four polyethylene liners were exchanged due to wear. 51 of 53 (96%) femoral stems and 50 (94%) acetabular components remain well fixed at latest follow up with no signs of loosening. There were no dislocations or infections.

Uncemented fixation appears to work well in this challenging group of patients even in the presence of open growth plates. Implant choice is important to avoid problems of subsidence and loosening. Ceramic bearings available for small implant sizes give promise of improved performance compared to polyethylene over the long term.

Background: Cam-type femoroacetabular impingement (FAI) is becoming more recognized. Cartilage lesions of the acetabulum and labral tears are frequently encountered. The goal of this study was to accurately describe and communicate these injuries and thus providing a standard for reporting injury, management, and outcome.

Methods: We evaluated acetabular cartilage lesions and labral tears found during hip arthroscopy in 52 patients with radiological signs of cam-type FAI. They were graded according to the morphology and extent of the lesion. The labral tears were described according to the classification by Lage.

Results: Eleven patients (21.2%) had normal cartilage, 14 (26.9%) had a grade 1, 17 (32.7%) a grade 2, 6 (11.5%) a grade 3, and 4 (7.7%) a grade 4 lesion. Labral tears were found in 31 patients (59.6%). There was a high correlation between age and the presence and extent of acetabular cartilage and labral lesions (r=0.70; p< 0.0001 and r=0.45; p< 0.001 respectively). There was also a high correlation between the extent of the acetabular cartilage lesion and the presence of labral lesions (r=0.62; p< 0.0001).

Conclusion: In our study there was a high prevalence of associated injuries (86.5%) in cam-type FAI. Despite the recognized consequences of associated lesions on treatment and outcome, no classification system includes this aspect of FAI. Based on our findings, we developed a system to grade acetabular cartilage lesions according to their morphology and extent. This should provide the surgeon with a standardized tool to better describe the full extent of the injury and treat it accordingly.

Introduction: The diagnosis of acetabular retroversion has traditionally been established by the presence of a cross-over sign on a plain pelvic radiograph. This however can be greatly influenced by the radiograph’s quality and degree of pelvic tilt. The aim of this study was to look at the relationship between cross-over and true anatomical version as measured in relation to an anatomical reference plane. The secondary aim was to determine whether in true retroversion there was excess coverage of the femoral head anteriorly.

Materials and Methods: Radiographs of 33 patients (64 hips) being investigated for symptoms of femoro-acetabular impingement were analysed. The presence of a cross-over sign was documented and the extent of cross-over was measured by noting the point on the rim where the cross-over occurs. CT scans of the same hips were analysed to determine anatomical version, and to calculate total, anterior and posterior coverage of the femoral head. This was done in relation to the anterior pelvic plane after correcting for pelvic tilt.

Results: The sensitivity, specificity and positive and negative predictive values for the cross-over sign were 92%, 55%, 59% and 91% respectively. The cross-over distance was correlated with 3D version (p=0.01). There was no significant difference in total cover of the femoral head between the anteverted and retroverted subgroups (71% vs. 72% respectively; p=0.55). Anterior cover was higher in the retroverted subgroup (35% vs. 32%; p = 0.0001), and posterior cover was significantly lower in this subgroup (37% vs. 39%; p = 0.002).

Discussion: Although the cross-over sign was sensitive enough to identify 92% of the retroverted cases, its specificity was low with just under half of the anteverted cases being labelled as retroverted. The findings for femoral head cover suggest that retroversion is characterised by posterior deficiency and increased cover anteriorly.

Introduction: There have been several recent studies outlining the role of femoroacetabular impingement (FAI) as a cause of early osteoarthritis in the non-dysplastic hip. The lesions can either be on the femoral side “cam” or acetabular “pincer”. The aim of surgical treatment of FAI is to improve the femoral head neck offset thereby improving joint clearance and preventing abutment of the femoral neck against the acetabulum. The classic treatment for FAI pioneered by Ganz involves dislocation of the femoral head through a trochanteric flip osteotomy. The procedure is extensive, technically difficult and not without complications.

Hip arthroscopic debridement of FAI lesions offers similar results to open procedures allowing for full inspection of the joint and the treatment of any chondral lesion but with a quicker recovery time. It nonetheless has a very long learning curve and even in the most experienced hands the treatment of impingement lesions is complicated and technically challenging.

The purpose of this cadaveric study was to assess the degree of exposure obtained using two different limited anterior approaches to the hip which would allow effective surgical treatment of cam and pincer FAI.

Methods: We investigated two mini anterior approaches to the hip joint based on the Heuter and direct anterior approach to compare the parts of the acetabulum and femoral head exposed for the treatment of FAI in a total of 20 hips in 10 (5 male, 5 female) cadaveric specimens. Neurovascular structures were recorded in relation to the two approaches. The area of femoral head and acetabular rim exposed via each approach was documented and quantified.

Results: We found that the two approaches were easy and reproducible. Both allowed exposure to the anterolateral aspect of the femoral head. The mean length of acetabular rim accessible via the Heuter approach was 1.9cm (1.1–2.4) and 2.2cm (1.2–3) using the direct anterior approach The area of acetabular rim accessible varied according to the approach (p< 0.001). We also found that the position of the anterior inferior iliac spine in relation to the acetabular rim also affected the area of acetabular rim exposed (p< 0.001). The most proximal nerve branch to sartorious was found 7.3cm (6.5–8.7cm) distal to the anterior inferior iliac spine. The most proximal nerve branch to rectus femoris was located 8.6cm (7–10) distal to the anterior inferior iliac spine and was consistently found to be distal to the nerve to sartorious.

Discussion: Treating impingement of the hip through a direct open approach is not a novel idea. A recent report of failed arthroscopic labral debridement, describes treatment of the underlying bony impingement in some cases by a combination of hip arthroscopy followed by anterior arthrotomy.

In summary cam and pincer impingement of the hip can be treated by either the direct anterior or Heuter approach. The choice of approach would be dictated after careful consideration as to which portion of the anterior acetabular rim required surgery, with more lateral acetabular lesions being favoured by the Heuter approach and more medial impingement sites by the anterior approach we have described.

This study examined the relationship between the cross-over sign and the true three-dimensional anatomical version of the acetabulum. We also investigated whether in true retroversion there is excessive femoral head cover anteriorly. Radiographs of 64 hips in patients being investigated for symptoms of femoro-acetabular impingement were analysed and the presence of a cross-over sign was documented. CT scans of the same hips were analysed to determine anatomical version and femoral head cover in relation to the anterior pelvic plane after correcting for pelvic tilt. The sensitivity and specificity of the cross-over sign were 92% and 55%, respectively for identifying true acetabular retroversion. There was no significant difference in total cover between normal and retroverted cases. Anterior and posterior cover were, however, significantly different (p < 0.001 and 0.002). The cross-over sign was found to be sensitive but not specific. The results for femoral head cover suggest that retroversion is characterised by posterior deficiency but increased cover anteriorly.

Introduction: The benefits of total hip replacement in patients with juvenile idiopathic arthritis are well documented. However only few results of uncemented total replacement with subsequent problems of loosening and revision surgery have been published. We report a minimum 2 year follow-up of uncemented total hip replacement in this group of patients

Material s& Methods: Between 1995 and 2003, 56 patients under the age of 29 years underwent 81 uncemented total hip replacements. 41 were females and 15 were males.1 patient died and 1 lost for follow -up. The average length of follow up was 6 years (range 2 to 10 yrs). In 67% of the patients the follow up period was 5 yrs or longer. The average age of onset of the disease was 5 yrs (range 1 to 19 yrs). The mean age at surgery was 18 yrs (range 11 to 29 yrs). Both hips were involved in 25 patients of which 18 were women and 7 were men. The mean interval between the onset of arthritis and surgery was 11 yrs. The mean interval between symptoms of hip involvement and hip replacement was 4.7 yrs. In 49% of patients the onset of arthritis was systemic, 22.6% polyarticular, 15.09% pauciarticular and 13.21% seronegative. Prior soft tissue release was performed in 6 hips(4).2 patients had previous supra-condylar femoral osteotomy for deformity correction.2 patients had total knee replacements(bilateral 1, unilateral 1). Usually a posterior approach was employed. A variety of prosthesis were used, Furlong HAC stem in 40 patients, SROM in 23 patients and CAD CAM in 17 patients. On the acetabular side, Furlong CSFHDP in 31 patients, Furlong ceramic in 15 patients, SROM cup in 21 patients, Duraloc cup in 9 patients and Muller support ring in 4 patients. The hips were graded before surgery and at follow-up using the scoring system of the Hospital for Special Surgery (Salvati and Wilson 1973)

Results: The mean improvement of HSS score for pain, ROM, mobility and function are 6.3, 3.1, 3.5 and 4.1 respectively. There was a mean improvement of 17.0 in the total HSS score. One patient had subsidence of both the CAD CAM stems at present waiting for revision. Radiolucent zones around the proximal sleeve SROM stem was noted in one patient requiring stem revision. Stress shielding of calcar was noted in 3 patients (CAD CAM 2, Furlong 1) and osteolysis around the cup in 1 patient. All patients with Furlong stem had very good osseointegration and there was no need of any revision. All patients with SROM stems also had very good osseointegration except one for which stem revision was done.

Conclusion: This study shows a lower revision rate and better radiographic appearance compared to previous reports with similar follow up of THA in Juvenile Idiopathic Arthritis.

INTRODUCTION Assessing femoral head coverage is a crucial element in acetabular surgery for hip dysplasia. CT has proven to be more accurate, practical and informative than plain radiography at analysing hip geometry. Klaue et al first used a computer-assisted model to indirectly derive representations of femoral head coverage. Jansen et al then described a CT-based method for measuring centre edge angle of Wiberg at 10 rotational increments. Haddad et al used that method to look at dysplastic hips pre- and post-acetabular osteotomy. We present a novel CT-based method that automatically gives an image of the head with the covered area precisely represented. We used this technique to accurately measure femoral head coverage (FHC) in normal hips and in a prospective study of patients with hip dysplasia undergoing peri-acetabular osteotomy. The impact of surgery on acetabular anteversion and inclination was also assessed.

METHODS Using a custom software programme, anatomical landmarks for 25 normal and 26 dysplastic hips were acquired on the 3D reconstructed CT image and used to define the frame of reference. Points were then assigned on the femoral head surface and the superior half of the acetabular rim after aligning the pelvis in the anterior pelvic plane. The programme then automatically produced an image representing the femoral head and its covered part along with the calculated femoral head coverage. To do so, the software represents the femoral head by a best-fit sphere, and the sphere and the acetabular contour are then projected onto a plane in order to calculate the load bearing fraction and area.

RESULTS In the normal hips FHC averaged 73% (SD 4), whereas anteversion and inclination averaged 16° (SD 7°) and 44° (SD 4°) respectively. In the dysplastic group the mean FHC was 50% (SD 6), with a mean anteversion of 19° (SD 10°) and mean inclination of 53° (SD 5°). Peri-acetabular osteotomy has been performed on 16 hips so far, and the FHC for those averaged 66% (SD 5), a mean improvement of 32%. The respective anteversion and inclination post-operatively were 18° (SD 12°) and 40° (SD 8°).

DISCUSSION This is the first study to our knowledge that has used a reliable and practical measurement technique to give an indication of the percent coverage of the femoral head by the acetabulum in normal hips. When this is applied to assessing coverage in surgery to address hip dysplasia it gives a clearer understanding of where the corrected hip stands in relation to a normal hip, and this should allow for better determination of the likely outcome of this type of surgery. The versatility of the method gives it significant attraction for acetabular surgeons and makes it useful not only for studying dysplastic hips but also other hip problems such as acetabular retroversion.

We present a new CT-based method which measures cover of the femoral head in both normal and dysplastic hips and allows assessment of acetabular inclination and anteversion. A clear topographical image of the head with its covered area is generated.

We studied 36 normal and 39 dysplastic hips. In the normal hips the mean cover was 73% (66% to 81%), whereas in the dysplastic group it was 51% (38% to 64%). The significant advantage of this technique is that it allows the measurements to be standardised with reference to a specific anatomical plane. When this is applied to assessing cover in surgery for dysplasia of the hip it gives a clearer understanding of where the corrected hip stands in relation to normal and allows accurate assessment of inclination and anteversion.

Introduction & Aims: A new femoral component for hip arthroplasty has been designed for a younger patient population. The design makes use of a higher femoral cut, which conserves bone stock, increasing options for future revision surgery. It uses the existing load bearing properties of the proximal femur, and therefore distributes load more evenly. The stem is longer than that of a resurfacing, so will be easier to insert at the correct orientation, minimising failure rates in inexperienced hands. The cross-sectional dimensions have been designed to produce torsional stability. The collar maximises the loading of the calcar, reducing stress resorption. The surface is hydroxyapatite coated and porous, which will produce a long-term biological fixation.

This project assessed the long-term stability of this design at different orientations, by measuring the change in surface strain distribution following its insertion.

Methods: Ten composite bones were coated in a Photoelastic material, positioned at a simplified single leg stance, and loaded at 2.3 KN. The surface strain was measured at one-centimetre intervals down the medial cortex. Then the prostheses were inserted into the bone at 135°, 145° and 125° to the femoral shaft, and the surface strains reread.

Results: The results were compared with an FEA model, and analysed statistically using the Wilcox signed rank test. The prosthesis inserted at 135° produced no significant difference in surface strain distribution compared with the intact bone.

Conclusions: This study suggests this stem design will be stable in the long term following insertion, and there were no areas of excessively high or low strain.

Introduction: Conservative hip replacements are advantageous because resection of bone in the proximal femur is minimised. This study investigated a new design of conservative hip in the goat model where the femoral head was resected and two hydroxyapatite coated ‘pegs’ were introduced into the femoral neck. The hypothesis was that the ‘pegs’ would provide a direct method of transmitting forces within the femoral neck thus resulting in less adverse bone remodelling and reduced loosening. Bone stock is also preserved should subsequent revision be required.

Methods: Eight unilateral implants were inserted into the right femur of adult female goats for 1 year. Retrieved specimens were analysed radiographically and histologically. Image analysis was used to quantify bone attachment and total bone area adjacent to the implant. Tetracycline bone markers quantified bone turnover. Operated hips were compared with non-operated hips. The students t-test was used for comparative statistical analysis where p< 0.05 were classified as significant.

Results: Radiographic analysis demonstrated bone loss beneath the cup with increased bone density at the distal end of the pins (fig.1). Light microscopy revealed areas of new and mature bone adjacent to the implant. Osseointegration to the HA coating was observed. Bone markers established significantly decreased bone formation rates (p< 0.05) in bone adjacent to the implant in the operated versus control hips.

Image analysis results demonstrated an average bone attachment of 30.94% to the implant surface (fig 2). Greatest bone attachment occurred at the end of the pins (78.99%) contributing 22% of overall attachment to the implant. Least attachment occurred beneath the prosthetic cup (13.82%) and in the medial aspect adjacent to the central pin. Greater total bone area was measured in control hips and no significant correlation between bone attachment to the ‘pegs’ and bone area beneath the prosthetic cup was identified.

Discussion: From this study we have concluded that despite the resorption of bone beneath the prosthetic cup, the conservatve hip design investigated remained well fixed in the femur during the 1 year in vivo period. It appears that an implant design that resurfaces the femoral head with two pins used to transmit forces into the femoral neck is a useful approach in conservative hip design.

Pelvic and acetabular surgery may be associated with significant blood loss because of the vascularity and anatomy of the pelvis. Concerns continue in relation to blood transfusion because of the potential for disease transmission and because of the increasing cost of providing safe blood products. The purpose of this study was to examine in a retrospective fashion the blood transfusion requirements in a consecutive series of patients undergoing peri-acetabular osteotomy for hip dysplasia.

Surgery was performed under general anaesthesia with an epidural in place in the majority of cases. A cell saver was not used and no pre operative autologous blood donation was performed. In seven cases one unit of blood was drawn off immediately prior to the operation in the anaesthetic room and re-infused towards the end of the operation. This practice was discontinued when one of these units clotted and could not be re-infused. A post-operative transfusion policy was adopted where an haemoglobin (Hb) concentration of < 7.5 g/dl was an indication for transfusion.

There were 19 females and 2 males. The average age was 26.6 (range 14 – 40). The average duration of surgery was 233mins (range 180 – 285min). Pre-operatively the average Hb concentration was 13.68 g/dl (range 12.3 – 16.2 g/dl). Overall 16 patients did not require any cross-matched transfusion. Two patients received one unit of blood and three received two units. If the transfusion policy had been correctly followed, 4 of these patients would not have received cross-matched blood. The average post-op Hb in those not receiving transfusion was 8.6 g/dl (range 7.3 – 9.9 g/dl).

This study shows that it is possible to safely perform peri-acetabular osteotomies in most cases without blood transfusion which is important in this group of patients who are generally young and female.

To assess the performance and success of joint sparing limb salvage surgery in high grade malignancy, in terms of function, complications, recurrence and survival, as compared to joint resection.

We report a ten-year experience of twenty patients with high grade malignancies of bone which did not cross the epiphyseal plate. They underwent not only limb salvage surgery but also joint preservation. The aim of this is to preserve function in the joint and to prevent the inevitable wear of prosthetic joints requiring revision surgery. The age range was 4 - 25 years (mean 13. 5). The Diagnoses were 14 Osteosarcomas and 6 Ewings sarcomas. Mean follow up was 49 months. There were 13 femoral & 7 tibial malignancies. 12 underwent complex biological fixation with a combination of reimplanted autoclaved or irradiated bone; vascularised fibular graft; femoral or humeral allograft. In 8 cases custom made hydroxyapatite coated prostheses were used to replace the resected bone. This surgery must clearly be evaluated in the context of recurrence, particularly as this is associated with an increased risk of metastases and death. Analysis of our results to date has not shown a greater rate of complications. We experienced one recurrence, and one death. The custom prostheses group had fewer complications and operations. Functionally these patients report near normal limbs and joints and do not report any limitation of activities.

Joint sparing limb salvage surgery is extremely worthwhile as it produces a significantly better functioning limb and lower morbidity, with less likelihood of revision surgery. We have not found a higher risk of post-operative complications, recurrence or death. Furthermore massive prosthetic replacement is quicker, osseointegrates reliably and is associated with a lower complication and further operation rate.

To assess the clinical features, development of metastases, and survival rate of patients with local recurrence after the resection of osteosarcoma in a large series.

Five hundred and thirty (530) patients with high-grade osteosarcoma were treated between 1989 and 1998. Fifty-four patients (10%) developed local recurrence after resection and adjuvant chemotherapy. There were 38 men and 16 women with a mean age of 19 years (range 6–50). The mean follow up was 39 months (range 7–120 months). Forty-three patients (79%) had clear resection margins microscopically, while in 8 patients (15%) microscopic tumour was found at the resection margin, and contaminated excision was performed in 3 patients. Histological response was category 1 in 24% of the patients, and category 2 in 76%. Clinical features, treatment, and prognosis were analyzed. Survival rates were examined using Kaplan-Meier Analysis.

The average interval between the first resection and local recurrence was 15 months (range 2–109 months). Forty-one patients (76%) had local recurrence in deep soft tissue, 7 in bone, and 6 in subcutaneous tissue. Twenty-six patients (49%) had lung metastasis at the time of local recurrence, while 21 patients (38%) developed it later. Thirty patients (57%) were treated with resection of the recurrent lesion and 18 (32%) were treated with amputation. 1-, 3-, and 5-year survival rates after local recurrence were 0.57, 0.38, and 0.22 respectively.

87% of patients with local recurrence developed metastases either concurrently or at a later date. Immediate amputation did achieve local tumor control. However, the survival rate was not statistically higher.

We report the results of anterior soft-tissue release of the hip for fixed flexion deformity in 17 patients (31 hips) with juvenile chronic arthritis. The mean age at operation was 8 years 6 months. All the patients were reviewed at one and three years and 11 (21 hips) were available for review at five years. The results were good as regards early pain relief and improved mobility. At one year, the average fixed flexion deformity was reduced from 35 degrees to 9.5 degrees, and at three years it was 18 degrees. This degree of improvement was maintained in the hips followed for five years. At 5 to 12 years' follow-up (mean 6.7) seven patients (14 hips) have required no further surgery and have maintained an acceptable range of motion. We discuss the influence of surgery on radiographic changes and on femoral neck anteversion.

We review the results of 96 primary total hip replacements in 54 patients with juvenile chronic arthritis at five years or longer after surgery. The mean age at operation was 16.7 years (range 11.25 to 26.6); the follow-up period averaged 11.5 years. The clinical results in terms of pain, range of movement, mobility and function are presented. A revision procedure was required in 24 hips (25%) in 18 patients at an average of 9.5 years after the primary operation. A further 17 hips had radiographic signs of loosening. The factors thought to contribute to this relatively high failure rate in patients with juvenile chronic arthritis are discussed.

Thirteen total hip replacements with titanium alloy femoral components required revision for loosening at an average of two years after implantation. At revision the soft tissues around the implant were darkly stained and a proliferative membrane had invaded the cement-bone interface. The femoral components showed polishing of parts of their shot-blasted surfaces. Histology showed a fibroblastic reaction with abundant titanium lying free and within histiocytes, and a scanty foreign-body giant-cell reaction. Surface analysis of the removed femoral components and chemical analysis of the excised tissues is described. Tissue reaction in response to the metal-wear debris may have contributed to the early failure of these implants.