Introduction. Orthopaedic rehabilitation of adolescences and young adults with high dislocation of the femur is rather challenging. The role of palliative salvage procedures is controversial enough in the cohort of patients. Materials and Methods. Treatment outcomes of 10 patients with congenital hip dislocation were analyzed. Mean age at intervention was 17,8 years (15–22). The grade of dislocation were assessed according to Eftekhar: type C − 2, type D − 8. The mean baseline shortening was 4.7±0.36 cm. All subjects underwent PSO with the Ilizarov method. Another osteotomy for lengthening and realignment was produced at the boundary of the upper and middle third of the femur. The mean time in the Ilizarov frame was 5.3 months. Results. The mean follow-up was 2.6±.1 years (range, 15 to 32 years). Limb shortening of 1 cm to 1. 1. /. 2. cm was observed in four cases. Functional outcomes according to d'Aubigne-Postel were: Pain 4,4±0,15 points. ROM − 4,1±0,3 points. Walking ability − 4,5±0,2 points. Two cases had good results (15–17 points), and seven patients had fair outcomes (12–14 points). A poor result (7 points) was recorded in one female patient 28 years after PSO followed by THA. Conclusions. Hip reconstruction with the Ilizarov method can be used in specific clinical situations as an alternative salvage procedure to delay THR in young patients with high dislocation of the femur

Purpose. The aim of this study was to identify if perioperative outcomes were different in patients with cerebral palsy undergoing unilateral or bilateral hip reconstruction. Method. All consecutive hip reconstructions for cerebral palsy performed by the senior author (FNT) within a tertiary-referral centre were identified between January 2012 and July 2016. Patients were stratified by age, gender, GMFCS and side of procedure. Length of surgery, pre- and post- operative haemoglobin, length of stay and immediate post-operative complications were measured. Results. 158 procedures were performed; 96 bilateral and 62 unilateral (37 left, 25 right). In bilateral procedures, operative time was 14 minutes longer (p= 0.07) and haemoglobin decrease was 1.85g/l greater (p= 0.34) with equivalent length of stay (average 6.4 days) and complication rate when compared to those undergoing unilateral procedures. Irrespective of procedure, those with a GMFCS level V had a longer length of stay (p< 0.05) and post-operative complication rate (p< 0.05) when compared to patients with GMFCS level IV. Conclusion. No significant differences were noted in the outcome measures when comparing unilateral and bilateral hip reconstructions in our group of patients with cerebral palsy. This suggests that concurrent prophylactic surgical management of the radiologically stable hip is a safe surgical option in this high-risk group of paediatric patients in an appropriate tertiary care setting with multidisciplinary team support

Introduction: The purpose of this study was to evaluate the predictors of outcome of hip reconstruction in cerebral palsy patients. Methods: 71 hip reconstructions in 38 patients [mean age 9.7] were reviewed retrospectively. Information regarding pre- and postoperative status, and operative details were retrieved from the clinical records. Preoperative, postoperative and annual follow up radiographs were reviewed to document acetabular index, Rimmer’s migration percentage (MP) and CE angle. Results: The mean MP improved from 84% to 43.8%. In 17 patients who underwent bilateral reconstruction the MP of the secondarily affected hips was improved from 38% to 12.2% The early follow up measurements of acetabular index, MP and CE angle had a significant correlation with the eventual postoperative outcome (p< 0.05). In a group of 22 patients hip pain was improved in 18 patients, sitting tolerance in 14, and perineal hygiene improved in 7 patients. There was no correlation between preoperative pelvic obliquity and open versus closed reduction with the eventual outcome. Discussion: The final outcome of the reconstruction can be predicted consistently from the first postoperative radiograph (MP). The quality of reduction at the time of operation is of paramount significance in ensuring long-term survival of the reconstruction. Subluxed hips in general did better than dislocated hips. The hips showed gradual deterioration over time

Introduction. Dislocation is one of the most important complications after primary total hip replacement (THR). The low incidence of this finding makes it difficult to analyse the possible risk factors. The surgical technique can also influence this rate through cup position or an adequate reconstruction of the hip. We assessed the demographic data and radiological reconstruction of the hip related to the appearance of dislocation after primary THR. Material and Methods. 1414 uncemented THRs were recorded from our Local Joint Registry. The mean age of the patients was 60.1 years old (range, 14 to 95), and the mean weight was 73.3 kg (42 to 121). There were 733 men and 974 patients were classified with an activity level of 4 or 5 according to Devane. The most frequent diagnosis was primary osteoarthritis, 795 hips, followed by avascular necrosis 207 hips. An alumina-on-alumina THR was implanted in 703 hips and a metal-on-polyethylene THR in 711 hips. A femoral head size of 28 mm was used in 708 hips and 32 mm in 704. Radiological cup position was assessed using the acetabular abduction angle, the height of the center of the hip, and the horizontal distance of the cup. Cup anteversion was measured according to Widmer and the reconstruction of the center of rotation of the hip according to Ranawat. The radiographic reconstruction of the abductor mechanism was measured using two variables: the lever arm and the height of the greater trochanter. Results. There were 38 dislocations (2.6%) and 11 hips were revised for recurrent instability (0.8%). The probability of not having a dislocation at 20 years was 97.3%. 22 hips that had dislocated were within a box for a cup position of a version between 10º to 25º and an acetabular abduction angle between 35º to 55º (p<0.001). The probability of not having a dislocation at 20 years was 98.48% for the cups within the box and 93.9% for cups outside the box (p<0.001, Log Rank test). 21 hips that had dislocated were within a box for a height of the greater trochanter between −2 mm to 5 mm and a lever arm between 56 to 64 mm (p<0.001). The probability of not having a dislocation at 20 years was 98.33% for the hips within the box and 94.6% for hips outside the box (p<0.001, Log Rank test). Adjusted Cox regression analysis showed that alumina-on alumina THR tended to dislocate less than metal-on-polyethylene THRs (p=0.061, Hazard Ratio: 2.238, Confidence Interval 95% 0.964–5.195), and hips outside the box evaluated for cup position and outside the lever arm and height of the greater trochanter box) had a higher risk for dislocation (p<0.001, HR: 3.418, CI 95% 1.784–6.549, and, p<0.001, HR:2.613, CI 95% 1.357–5.032, respectively). Conclusions. A proper reconstruction of the hip is essential to decrease the risk for dislocation after primary THR. The choice of the bearing surface may affect this risk. The weakness of the abductor muscles of the hip may be one of the most important causes for dislocation

Introduction: The purpose of this study was to evaluate the predictors of outcome of hip reconstruction in cerebral palsy and to review the trend in recovery over five years following operations. Methods: 39 reconstructions in 22 patients [mean age 9.9 SD 2.1] with a mean follow up of 4.7 years were reviewed retrospectively. Information regarding diagnosis, preoperative function and symptoms, details of operation and the postoperative status were retrieved from the clinical records. Preoperative, postoperative and yearly follow up radiographs were reviewed to document acetabular index, Rimmer’s migration percentage (MP) and CE angle. 17 patients underwent simultaneous bilateral hip reconstruction. Femoral osteotomy was performed in all cases in the primary hip and in 17 cases in second hip. Acetabuloplasty was performed in 18 patients in the worst hip and only in 5 cases in the second hips. Results: The mean preoperative MP in the worst hip was 81%. This improved to 30.7%. In the second hip it improved from 38% to 12.2%. The follow up measurements of the acetabular indices, MP and CE angle had a significant correlation with the postoperative measurements (p< 0.05). In 18 patients hip pain improved and in 14 patients sitting tolerance improved. Perineal hygiene improved in 7 patients following the operation. Graphs of trends in the MP and CE angle are presented. There was no correlation between preoperative presence of pelvic obliquity and post operative outcome. There was no significant difference in outcome in the groups of patients based on open reduction at the time of surgery. Discussion and Conclusions: The final outcome of the reconstruction can be predicted consistently from the first postoperative radiograph. The quality of reduction at the time of operation is of paramount significance in ensuring long-term survival of the reconstruction

In cemented total hip arthroplasty, the cement-bone interface can be considerably degraded in less than one year in-vivo service (Figure 1). This makes the interface much weaker relative to the direct post-operative situation. Retrieval studies show that patients do, to a certain extent, not suffer from the degraded cement-bone interface itself. It is, however, unknown whether the degraded cement-bone interface affects other failure mechanisms in the cemented hip reconstruction. A good understanding of the mechanics of the cement-bone interface is therefore essential. The aim of this study was to investigate the mechanics of the cement-bone interface in the direct post-operative and degraded situation by the utilization of finite element analysis (FEA) and laboratory experiments. It was subsequently analyzed how the mechanics of the cement-bone interface affect failure of the cement mantle in terms of crack formation. In order to investigate the mechanical response of the cement-bone interface, laboratory prepared (direct post-operative state) and postmortem (degraded state) specimens were loaded in various directions in the laboratory and FEA environment. From all specimens, multiple interface morphology parameters were documented, which were related to the interfacial response and subsequently converted to a numerical cohesive model. As a validation, this cohesive model was implemented into two FEA models of transverse sections of cemented hip reconstructions with distinct mechanical characteristics (Figure 2). Finally, the differences in fatigue crack formation in a complete hip reconstruction were determined by varying the cement-bone interface compliance (Figure 3). When loaded in multiple directions, the interface compliance could not be related to the cement interdigitation depth (r. 2. =0.08). However, compliance did correlate to the gap thickness between the bone and cement (r. 2. =0.81) and the amount of interfacial contact (r. 2. =0.50). Surprisingly, for the same amount of contact, the interface was more compliant in degraded state than in the direct post-operative state. The mechanical response of the experimental and FEA cement-bone interface tests could, independent on the direct post-operative or degraded state, successfully be described by a cohesive model. The cohesive model was even more confirmed by the successful reproduction of the mechanics of the retrieved transverse sections. When the cohesive model was implemented in a complete reconstruction, we found that a compliant cement-bone interface resulted in considerably more fatigue cracks in the cement mantle than a very stiff interface. This study showed that an increased compliancy of the cement-bone interface results in an increase of cement cracks in the cement mantle. It is therefore crucial to minimize the interfacial gaps and, as a result, increase the amount of contact between the bone and cement to generate a stiff cement-bone interface. It is, unfortunately, unknown how this well fixed interface can be maintained. We finally conclude that the derived cohesive model of the cement-bone interface can be used for multiple applications in orthopaedics, including pre-clinical of implants and patient specific studies of failed cemented reconstructions

Background. Ilizarov hip reconstruction is a salvage option traditionally done with fixators, which often face limited compliance. We aimed at reviewing our early results of a novel technique with internal devices. Material and Methods. Retrospective evaluation of 7 patients was done that underwent Milch Batchelor procedure with dual plates followed by a second stage femoral lengthening by retrograde magnetic nail. The mean patient age was 13.8 years. A mean valgus of 410 (range, 300 to 550) and extension of 220 (range, 100 to 300) were created proximally. Results. At their mean recent follow-up of 19 months, all extremities were aligned with a mean Pelvic Mechanical Axis Angle (PMAA) of 83.80 and lateral Mechanical Axis Deviation (MAD) of 25.3 mm. The mean Lower-extremity Length Discrepancy (LLD) improved from 3.7 cm (range, 3 to 5 cm) preoperatively to 0.7 cm (range, 0 to 2 cm). The Trendelenburg sign was eliminated in five and delayed in 2. According to a predesigned clinical scoring system, there were 3 (43%) excellent, 2 (28.5%) good, 2 (28.5%) fair, and no poor results. One patient at 9 weeks broke plates, however went for healing. Conclusion. PSHR with internal devices is a patient-friendly alternative to fixators

Purpose of study: To assess functional, clinical and radiological outcomes of 30 children (60 hips) with whole body cerebral palsy with a mean follow-up of ten years. Method: Bilateral simultaneous combined soft-tissue and bony hip surgery was performed at a mean age of 7.7 years (3.1–12.2). Evaluation at ten years involved interviews with patient/carers and clinical examination. Plane radiographs of the pelvis assessed migration percentage and centre-edge angle. Results: Twenty two patients were recalled. Five had died of unrelated causes and three were lost to follow-up. Pain was present in only 1 patient (4.5%). Improved handling was reported in 18 of 22 patients (82%). Carer handling problems were attributed to growth of the patients. All patients/carers considered the procedure worthwhile. The range of hip movements improved, with a mean windsweep index of 36 (50 pre-operatively) Radiological containment improved, with mean migration percentage of 20 degrees (50 preoperatively) and mean centre-edge angle of 29 degrees (−5 preoperatively) No statistical difference was noted between the three year and ten year follow-up results, demonstrating sustained improvement in the clinical and radiological outcome. Conclusions: Bilateral simultaneous combined hip reconstruction in whole body cerebral palsy provides painless, mobile and anatomically competent hips in the longer term. The majority of the available literature considers the short term outcome of surgical reconstruction of the hips in this condition. This paper demonstrates that the initial improvements in structure and function are maintained in the longer term

The results of a functional, clinical and radiological study of 30 children (60 hips) with whole body cerebral palsy are presented with a mean follow-up of ten years. Bilateral simultaneous combined soft-tissue and bony surgery was performed at a mean age of 7.7 years (3.1–12.2). Evaluation involved interviews with patient/carers and clinical examination. Plain radiographs of the pelvis assessed migration percentage and centre-edge angle. Twenty two patients were recalled. Five had died of unrelated causes and three were lost to follow-up. Pain was uncommon, present in 1 patient (4.5%). Improved handling was reported in 18 of 22 patients (82%). Carer handling problems were attributed to growth of the patients. All patients/carers considered the procedure worthwhile. The range of hip movements improved, with a mean windsweep index of 36 (50 pre-operatively). Radiological containment improved, with mean migration percentage of 20 degrees (50 preoperatively) and mean centre-edge angle of 29 degrees (−5 preoperatively) No statistical difference was noted between the three year and ten year follow-up results demonstrating maintained clinical and radiological outcome improvement. In conclusion, we consider that bilateral simultaneous combined hip reconstruction in whole body cerebral palsy provides painless, mobile and anatomically competent hips in the long term

Purpose: Clinical studies still show significant variability in offset and leg length reconstruction after 28mmTHA. Precise restoration of hip biomechanics is important since it reduces wear and improves stability, abductor function and patient satisfaction. There is a tendency to increase offset and leg length to ensure stability of 28mmTHA. This may not be needed with the more stable LDHTHA and hip resurfacing implants, therefore potentially improving the precision of the hip reconstruction. The aim of this study was to verify this assumption. Method: Leg length and femoral offset were measured on standardized digital radiographs with a computer software in 254 patients (49 HR, 74 LDHTHA, 132 28mmTHA) with unilateral hip involvement and compared to the normal contralateral side. Results: Femoral offset was increased in 72% of 28mmTHA (mean +3.3mm), 56% of LDHTHA (mean +1.0mm) and 8% of HR (mean −3.2mm) (intergroup differences p< 0.05). The mean LLI was greater after 28mmTHA (+2,29mm) vs. (−0.45mm for LDHTHA and −1.8mm for HR). The percentage of patients with increased leg length > 4mm was greater for 28mmTHA (11%) compared to LDHTHA (2.7%) and HR (2%). Conclusion: The stability afforded by the larger head of LDHTHA reduces the surgeon’s tendency to increased leg length and femoral offset to avoid instability as during 28mmTHA. In addition, compared to HR, LDHTHA allows more precise restoration of equal leg length and femoral offset in patient with greater pre operative deformities (low femoral offset and LLI > 1cm). LDHTHA may represent the most precise method of hip joint reconstruction

Custom acetabular components have become an established method of treating massive acetabular bone defects in hip arthroplasty. Complication rates, however, remain high and migration of the cup is still reported. Ischial screw fixation (IF) has been demonstrated to improve mechanical stability for non-custom, revision arthroplasty cup fixation. We hypothesise that ischial fixation through the flange of a custom acetabular component aids in anti-rotational stability and prevention of cup migration.

Electronic patient records were used to identify a consecutive series of 49 custom implants in 46 patients from 2016 to 2022 in a unit specializing in complex joint reconstruction. IF was defined as a minimum of one screw inserted into the ischium passing through a hole in a flange on the custom cup.

The mean follow-up time was 30 months. IF was used in 36 cups. There was no IF in 13 cups. No difference was found between groups in age (68.9 vs. 66.3, P = 0.48), BMI (32.3 vs. 28.2, P = 0.11) or number of consecutively implanted cups (3.2 vs. 3.6, P = 0.43). Aseptic loosening with massive bone loss was the primary indication for revision. There existed no difference in Paprosky grade between the groups (P = 0.1). 14.2% of hips underwent revision and 22.4% had at least one dislocation event.

No ischial fixation was associated with a higher risk of cup migration (6/13 vs. 2/36, X2 = 11.5, P = 0.0007). Cup migration was associated with an increased risk for all cause revision (4/8 vs. 3/38, X2 = 9.96, P = 0.0016, but not with dislocation (3/8 vs. 8/41, X2 = 1.2, P = 0.26).

The results suggest that failure to achieve adequate ischial fixation, with screws passing through the flange of the custom component into the ischium, increases the risk of cup migration, which, in turn, is a risk factor for revision.

Osteolysis, fractures, and bone destruction caused by osteomyelitis or metastasis can cause large bone defects and present major challenges during acetabular reconstruction in total hip arthroplasty. We sought to evaluate the survivorship and radiographic outcomes of an acetabular reconstruction consisting of a polyethylene liner (semi-constrained) embedded in cement filling bone defect(s) reinforced with screws and/or plates for enhanced fixation (HiRISC).

Retrospective chart review of 59 consecutive acetabular reconstructions as described above performed by 4 surgeons in a single institution (10/18/2018-1/5/2023) was performed. After radiographs and operative reports were reviewed, cases were classified following the Paprosky classification for acetabular defects. Paprosky type 1 cases (n=26) were excluded, while types 2/3 (n=33) were included for analysis. Radiographic loosening was evaluated up to latest follow-up. Mean follow-up was: 487 days (range, 20–1,539 days).

Out of 33 cases, 2 (6.1%) cases were oncological (metastatic disease) and 22 (66.7%) had deep infection diagnosis (i.e., periprosthetic joint infection [PJI] or septic arthritis). In total, 7 (21.2%) reconstructions were performed on native acetabula (3 septic, 4 aseptic). At a mean follow-up of 1.3 years, 5 (15.2%) constructs were revised: 4 due to uncontrolled infection (spacer exchange) and 1 for instability. On follow-up radiographs, only 1 non-revised construct showed increased radiolucencies, but no obvious loosening. When compared to patients with non-revised constructs, those who underwent revision (n=5) were significantly younger (mean 73.8 vs. 60.6 years, p=0.040) and had higher body mass index (24.1 vs. 31.0 Kg/m², p=0.045), respectively. Sex, race, ethnicity, American-Society-of-Anesthesiologist classification, infection diagnosis status (septic/aseptic), and mean follow-up (449.3 vs. 695.6 days, respectively, p=0.189) were not significantly different between both groups.

HiRISC construct may be a viable short-term alternative to more expensive implants to treat large acetabular defects, particularly in the setting of PJI. Longer follow up is needed to establish long term survivorship.

Introduction

Metal-on-polycarbonate urethane (MPU) is a cutting-edge new bearing technology for hip arthroplasty. The acetabular component consists of a 2.7mm-thick polycarbonate-urethane liner inserted into a specially manufactured uncemented titanium shell coated with hydroxyapatite [(HA) Fig. 1]. The liner is pliable and biomechanically mimics human cartilage. In vitro studies have shown minimal wear, fluid film lubrication, physiological load transmission and shock absorption capacity equal to the normal hip. This system includes prosthetic heads of a diameter 12mm less than the socket diameter. The aim of this study was to clinically assess patients treated with this novel technology in a retrospective single centre study.

The childhood hip conditions of Developmental Dysplasia, Legg-Calve-Perthes Disease and Slipped Capital Femoral Epiphysis have a wide spectrum of anatomical outcomes following childhood treatment; ranging from morphologies, which result in normal hip function throughout life, to severely deranged morphologies, which result in pain and disability during childhood and adolescence. Some of these outcomes are as a result of well-intentioned interventions that result in catastrophic complications.

In 2003, after years of working with impingement complicating periacetabular osteotomies and building on the work of William Harris, Reinhold Ganz published his concepts of ‘cam’ and ‘pincer’ hip impingement, and how these anatomical morphologies resulted in hip arthritis in adulthood. These concepts of impingement were added to his previous published work on hip instability to provide a comprehensive theory describing how hip arthritis develops on the basis of anatomical abnormalities. Surgical techniques have been developed to address each of these morphological pathologies.

Ganz's concepts of hip impingement and instability may be applied to severe paediatric hip deformities to direct reconstructive joint preserving surgery to both the femur and the acetabulum. Ganz's surgical approaches have also been refined for use in paediatric hip surgery to allow radical reshaping salvage osteotomies to be performed on the developing femoral head with minimal risk of the devastating consequence of vascular Necrosis.

Introduction. Tantalum is a pure metallic element and is attractive for use in orthopaedic implants because it is one of the most biocompatible metals available for implant fabrication. The potential advantages for the use of porous tantalum in total hip arthroplasty include: 1) excellent bone and tissue ingrowth observed histologically; 2) direct polyethylene intrusion into the metal substrate. This allows the elimination of any potential backside wear in the monoblock cup; 3) The two-piece design consist of a tantalum shell with screw holes for fixation into the dome of the ilium and posterior column. A polyethylene liner is cemented into the tantalum shell to eliminates backside motion. In addition, acetabular augments of porous tantalum have been developed for use in restoration of major bone deficiencies.

Prospective study on a case serie of 113 THA’s performed by two surgeons in a single institution.

Material & Methods. From 2000 to December 2003, 113 hips have undergone arthroplasty using porous tantalum implants consisting of 54 primary hip arthroplasties and 59 revision THA’s. The patients where evaluated clinical and radiographically every 3 month during the first year, and after yearly. Mean patient age was 64,2 years, (range 44–87); with 59% males and 41% females.

Results. No patients died or lost to follow-up. No further surgeries of the involved hip. No radiographic signs of loosening of the acetabular component according to the criteria of Hodgkinson et al. No problems specifically from the use of acetabular augments or extra screws has been noted. Of the revision series, a total of 16 cases have received acetabular augments.

Complications included 1 superficial infection, 2 dislocations. No vasculo-nervous complication; and in 2 cases technical difficulties to achieve good fixation due to ethiology of the THA (desarthrodesis).

The average Harris hip score improved from 48 to 89 following primary surgery.

Discussion and Conclusions Tantalum acetabular components for primary and revision hip surgery have performed well for up to 3 years, and have excellent stability.

The two-piece acetabular shell and augments permits the reconstruction of every acetabular bone defect.

Introduction

Instability accounts for one third of revision total hip arthroplasty(rTHA) performed in the United Kingdom. Removal of well-fixed femoral stems in rTHA is challenging with a risk of blood loss and iatrogenic damage to the femur. The Bioball Universal Adaptor (BUA) (Merete, Germany), a modular head neck extension adaptor, provides a mechanism for optimisation of femoral offset, leg length and femoral anteversion. This can avoid the need for femoral stem revision in selected cases. There is a relative paucity of clinical data available with the use of this device.

Aim

The Pelvic Support Osteotomy (PSO) or Ilizarov Hip Reconstruction(IHR) is well described for the treatment of septic sequelae of infancy. The purpose of this study was to clinically, functionally and radiographically assess our short-term results of this procedure.

The Pelvic Support Osteotomy (PSO) or Ilizarov Hip Reconstruction(IHR) is well described for the treatment of septic sequelae of infancy. The purpose of this study was to clinically, functionally and radiographically assess our short-term results of this procedure.

25 patients (16 boys, 9 girls) who had undergone a IHR using the Ilizarov/TSF construct over a period of 10 years for a variety of pathologies were reviewed. The mean age at surgery was 15 years 4 months. The pre-operative diagnoses were SCFE(10), hip sepsis (6), DDH (6) and Perthes (3). All had significant leg length discrepancies, 16 had a painful stiff hip, 6 had a painful mobile hip and 3 had a painless unstable hip. At surgery, a mean measured proximal valgus angle of 51° and a mean extension angle of 15° was achieved. Distal femoral lengthening averaged 4.2 cm and distal varus correction was a mean of 8°. The mean fixator time was 173 days.

At a mean of 2 years and 7 months follow-up the lower-extremity length discrepancy had improved from a mean of 5.6 cm apparent shortening to 2.3 cm. Trendelenberg sign was eliminated in 18/25 cases. Improvements in range of hip movements and gait parameters were observed. Stance time asymmetry, step length asymmetry, pelvic dip and trunk lurch improved significantly. One patient had conversion to a total hip replacement after 7 years, 4 patients required re-do PSO due to remodelling of the proximal osteotomies, two had heterotopic ossification and two had significant knee stiffness due to lack of compliance.

The early results of IHR are encouraging to equalise limb lengths, negate trendelenburg gait, provide a mobile hip with a reasonable axis and the possibility of conversion to THR in the future if needed. Complications need to be anticipated and the effects of remodelling and maintaining adequate knee range of motion must be emphasised.

A retrospective single-center review has been performed to gather clinical data on the use of polycarbonate-urethane (PCU) as an articulating bearing material inside a cobalt-chrome (Co-Cr) press-fit acetabular shell.

As of January 2010, the Co-Cr shell and PCU liner have been implanted into 25 total hip patients which were retrospectively followed. The indications for use were in 24 cases of osteoarthritis, and 1 revision case. No patient was lost to follow-up. The average follow-up time was 17.6 months (range 8-27). The average age of these patients was 67.9 (range 44-84), the sex distribution was 14 female and 11 male patients, of whom 15 were right and 10 left side. 24 patients received a total hip replacement with the metal acetabular system and a cementless femoral stem and 1 patient received the metal acetabular shell coupled to a cemented resurfacing head.

None of the cases has had a dislocation, revision, dislodgement, or infection. At follow-up, the mean Harris hip score was 98 points (80-99). X-rays showed good bone-implant contact without any osteolysis or bone rarefaction.

A detailed review of the clinical data of these patients shows that a PCU liner inserted into a Co-Cr acetabular shell is as safe and effective as other commonly used acetabular shells in other total hip systems currently available. No new or unintended adverse or device-related events were discovered with the clinical use of PCU in a Co-Cr acetabular shell.

We investigated the feasibility of using porous titanium particles (TiP) to reconstruct femoral bone defects in revision hip replacement surgery in stead of using morzelised bone grafts. Questions regarding handling, initial stability and titanium particle release were addressed.

Seven composite femurs (Sawbones) were reamed and filled, stepwise, with 32 grams of large (Ø 3.15 – 4 mm) and 9 grams of smaller (Ø 2.8 – 3.15 mm) pure, 85% porous TiP. Subsequently an Exeter stem was cemented into the graft layer. All reconstructions were loaded axially (0–3000 N) for 300,000 loading cycles at 2 Hz. Subsidence of the stem was measured with radio stereometric analysis (RSA) and possible titanium particle release was measured using the laser diffraction technique.

The TiP were impacted into a > 3 mm (SD 1.43 mm) thick, highly entangled, graft layer. An average cement mantle of > 2 mm (SD 0.86 mm) was measured and little cement penetration was observed. The average subsidence of only 0.45 mm (SD 0.04 mm) was measured after 300 000 loading cycles. Most titanium particles were found directly after impaction. Most of these particles (87%) were smaller than 10 μm and could therefore be potentially harmful since they can induce osteolysis.

We can conclude that:

A graft layer of impacted TiP can be constructed,

These data warrant further animal tests to assess the biological response to these released impaction particles. Also, animal tests should clarify possible particle release upon loading and its effects.