Objectives. To quantify and compare peri-acetabular bone mineral density (BMD) between a monoblock acetabular component using a metal-on-metal (MoM) bearing and a modular titanium shell with a polyethylene (PE) insert. The secondary outcome was to measure patient-reported clinical function. Methods. A total of 50 patients (25 per group) were randomised to MoM or metal-on-polyethlene (MoP). There were 27 women (11 MoM) and 23 men (14 MoM) with a mean age of 61.6 years (47.7 to 73.2). Measurements of peri-prosthetic acetabular and contralateral hip (covariate) BMD were performed at baseline and at one and two years’ follow-up. The Western Ontario and McMaster Universities osteoarthritis index (WOMAC), University of California, Los Angeles (UCLA) activity score, Harris hip score, and RAND-36 were also completed at these intervals. Results. At two years, only zone 1 showed a loss in BMD (-2.5%) in MoM group compared with a gain in the MoP group (+2.2%). Zone 2 showed loss in both groups (-2.2% for MoM; -3.9% for MoP) and zones 3 and 4 a gain in both groups (+0.1% for MoM; +3.3% for MoP). No other between-group differences were detected. When adjusting for BMD of the contralateral hip, no differences in BMD were observed. The only significant differences in functional scores at two years were higher UCLA activity (7.3 (. sd. 1.2) vs 6.1 (. sd. 1.5); p = 0.01) and RAND-36 physical function (82.1 (. sd. 13.0) vs 64.5 (. sd. 26.4); p = 0.02) for MoM bearings versus MoP. One revision was performed in the MoM group, for aseptic acetabular loosening at 11 months. Conclusions. When controlling for systemic BMD, there were no significant differences between MoM and MoP groups in peri-acetabular BMD. However, increasing reports of adverse tissue reactions with large head MoM THR have restricted the use of the monoblock acetabular component to resurfacing only

Introduction: Peri-acetabular rotational osteotomy is recognized as the non-arthroplastic treatment for Developmental Dysplasia of the Hip (DDH). This procedure has increased in popularity during the last decade. It aims to restore the acetabular cover over the femoral head and thus delay secondary osteoarthritic changes in the hip. Materials and methods: We reviewed 16 patients who underwent peri-acetabular rotational surgery at our hospital. The indication for surgery was DDH in all cases. Reinert’s approach was used for surgical exposure. Two patients underwent a valgus femoral osteotomy at the same time. Mean age was 40 years (range 15–49). The mean follow-up was 46.5 months (range 4–108). The results of the surgery were assessed with radiological indices and a patient satisfaction survey. The radiological indices recorded were Wiberg’s angle, acetabular inclination angle, femoral head extrusion index and Tonnis osteoarthritis grading. Results: The intervention failed to benefit two patients who subsequently required a total hip arthroplasty. Both patients had Tonnis grade 3 osteoarthritis. One patient developed a necrotic skin flap requiring skin grafting. The mean pre-operative Wiberg’s angle was 11 degrees (range −7 to 25) which was corrected to 35 degrees (range 17 to 58). Mean pre-operative acetabular index was 25 degrees (range 14 to 40) which was corrected to 11 degrees (range of 2 to 21). Mean pre-operative femoral head extrusion index was 37 degrees (range 18–50) which was reduced to 14 degrees (range 0–32). In all but the two patients in whom the surgery had failed, patients reported reduction in hip pain. Conclusions: Peri-acetabular rotational osteotomy is a challenging but worthwhile procedure for young patients with DDH. The early results from the procedure are encouraging providing patient selection is appropriate. We would like to initiate a debate to identify the ideal patient for this procedure

Aim. The saddle prosthesis was originally developed for reconstruction of large acetabular defects in hip revision arthroplasty. Later on the saddle prosthesis was also used for hip reconstruction after resection of peri-acetabular tumours. In case of patient survival a long-term good hip function is required of the saddle prosthesis. The goal of this study is the measurement of long-term clinical results of saddle prosthesis after reconstruction of peri-acetabular tumours. Method. Between 1987 and 2003 a total of 17 patients were treated in the Leiden University Medical Center with saddle prosthesis after resection of peri-acetabular tumours (12 chondrosarcoma, 3 osteosarcoma, 1 malignant fibrous histiocytoma, 1 metastasis). 11 of the 17 patients died, the mean survival was 37 months (range 2-59 months), and 6 patients were still alive (follow-up 12.1 year, range 8.3–16.8 year). The outcome was measured with the SF-36 questionnaire, the Toronto Extrimity Salvage Score (TESS) and the Musculo Skeletal Tumour Society (MSTS) score. In 1 patient the saddle prosthesis was removed already after 3 months because of luxation and infection. Results. In 13 of the 17 patients the use of walking devices was known: 54% required two crutches, 38% one crutch, and 8% no walking aids. The mean hip flexion was 60 degrees (range 40-100 degrees). Local complications were seen in 14 of the 17 patients: 9 wound infections, 7 luxations, and 2 leg length discrepancies requiring additional surgery. In the 5 surviving patients the MSTS score at long-term follow up was 47%, the mean TESS score was 53%, the mean composite SF-36 physical and mental scores were 43.92 and 50.64 respectively. Conclusion. Reconstruction with saddle prosthesis after peri-acetabular tumour surgery has a high risk of complications, and poor long term functional outcome with limited flexion of the hip

Introduction Peri-acetabular osteolysis is a serious complication of total hip arthroplasty (THA). The aim of this study was to determine, using quantitative computed tomography (CT), the location, volume and rate of progression of peri-acetabular osteolytic lesions, and to determine the validity of this CT technique with intra-operative measurements. Methods High-resolution spiral multislice CT scan (Somatom Volume Zoom, Siemens, Munich, Germany), with metal-artefact suppression protocol, was used to measure the volume of osteolytic lesions around 47 cementless THAs in 36 patients (median age 73 years, duration 14 years, range five to 24 years). In vitro validation was undertaken. CT scans were taken from the top of sacroiliac joint down to two centimetres below the end of the prosthesis. Reconstruction images were analysed by two different observers and progression of osteolysis with time was determined. In some patients, subsequently revised, in-vivo CT measurements were compared to intra-operative measurements. The rate of progression of osteolytic lesions was calculated. The technique was optimised and validated by extensive in-vitro studies, using bovine and human pelves. Results The incidence of lesions located in each site was: the ilium, 65%; around fixation screws, 20%; in the anterior column, nine percent; and in the medial wall, six percent. Some lesions were shown to be relatively quiescent, while others were aggressively osteolytic. Intra and inter-observer error for the CT measurement technique was four percent and 2.8%, respectively. In vitro volumetric measurements of simulated bone defects adjacent to the acetabular component and fixation screw were accurate to within 96% and precise to 98%. In addition, preliminary data obtained intra-operatively indicate the accuracy of CT in identifying the sites of osteolysis. Conclusions CT is thus a valid and reliable technique for investigating the natural history of osteolysis and the factors that may influence its progression. It will also enable assessment of non-surgical treatments of osteolysis. In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source

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

Ganz peri-acetabular osteotomy is commonly used to treat symptomatic hip dysplasia. It aims to increase the load bearing contact area of the hip to reduce the risk of subsequent osteoarthritis. In this study we assess the radiographic and clinical results of the procedure since its introduction to our unit. All patients undergoing Ganz osteotomies at our unit were followed up prospectively. Data collected included patient demographics and pre- and post-operative functional scores (Harris and Non-arthritic hip scores). In addition, acetabular correction was evaluated on pre-and post-operative radiographs (using Centre-Edge angle and Tonnis angle). Complications were also noted. Overall 50 procedures were performed between 2007 and 2013 with median follow-up of 3 years (1 – 7 years). The majority of patients (90%) were female. Average age at time of surgery was 29 years (16–49). There were significant improvements in pre- and post-operative median functional scores (Modified Harris Hip Score = 49 versus 64, p=0.001), Non-arthritic Hip Score = 42 versus 56, p=0.007). Median Centre Edge Angle improved from 16 degrees pre-operatively (range = 7–31 degrees) to 30 degrees post-operatively (18–33) degrees), p<0.0001. Similarly, pre-operative Tonnis angle improved from 18 degrees (9–38) to 7 degrees (2–14), p<0.0001. Five patients developed post-operative complications: 2 superficial wound infection, 1deep infection requiring hip washout and antibiotic treatment and 2 patients subsequently requiring total hip replacements. We have shown that the Ganz peri-acetabular osteotomy can be effective for the treatment of painful hip dysplasia improving both functional and radiographic outcomes. However, patient selection is a key factor

Ganz peri-acetabular osteotomy is commonly used to treat symptomatic hip dysplasia. It aims to increase the load bearing contact area of the hip to reduce the risk of subsequent osteoarthritis. In this study we assess the radiographic and clinical results of the procedure since its introduction to our unit. All patients undergoing Ganz osteotomies at our unit were followed up prospectively. Data collected included patient demographics and pre- and post-operative functional scores (Harris and Non-arthritic hip scores). In addition, acetabular correction was evaluated on pre-and post-operative radiographs (using Centre-Edge angle and Tonnis angle). Complications were also noted. Overall 50 procedures were performed between 2007 and 2013 with median follow-up of 3 years (1–7 years). The majority of patients (90%) were female. Average age at time of surgery was 32 years (17–39). There were significant improvements in pre- and post-operative median functional scores (Modified Harris Hip Score = 52 versus 63, p=0.001), Non-arthritic Hip Score = 49 versus 60, p=0.01). Median Centre Edge Angle improved from 15 degrees pre-operatively (range = 8–19 degrees) to 29 degrees post-operatively (22–36 degrees), p=0.02. Similarly, pre-operative Tonnis angle improved from 19 degrees (16–38) to 7 degrees (2–14), p=0.01. Four patients developed post-operative complications: 1 superficial wound infection, 1deep infection requiring hip washout and antibiotic treatment and 2 patients subsequently requiring total hip replacements. We have shown that the Ganz peri-acetabular osteotomy can be effective for the treatment of painful hip dysplasia improving both functional and radiographic outcomes. However, patient selection is a key factor

Aims. To determine whether there is any benefit using a minimally invasive trans-sartorial approach as described by Professor Søballe compared to the ilio-femoral for peri-acetabular osteotomy. Methods. 30 consecutive patients were operated on by a single surgeon. The first 15 underwent an ilio-femoral (I-F) approach whilst the following 15 had a trans-sartorial (T-S) approach. Fixation was achieved with 3 or 4 screws. All other aspects of surgery and rehabilitation were the same. Data was collected prospectively and included operation time, intra-operative blood loss and length of stay. Acetabular correction was measured using the sourcil and centre edge angle (CEA) on pre and post-operative radiographs. Results. Both groups had acceptable radiographic corrections with CEA improving from mean 14.5 to 38.7 degrees (T-S) and 14 to 39 degrees (I-F). The sourcil angle improved from mean 17.8 to 2 degrees (T-S) and 19.5 to −1.5 (I-F). Minimally invasive surgery reduced anaesthetic time by 62 minutes. Haemoglobin loss was reduced by 1 gram/L and there was no requirement for transfusion. Hospital stay reduced by 0.8 days. There were no major adverse complications although two partial femoral neurapraxias were noted early in the series. These fully resolved. Conclusion. We have found significant benefit from changing to minimally invasive PAO. Our patients have smaller wounds, a shorter operative time, reduced bleeding and a shorter length of stay. We found no adverse effects. The time savings have also corresponded to a cost saving for our institution. We recommend this technique although recognise that it has a learning curve and should be initiated by surgeons with previous PAO experience

Since acetabular osteolytic lesions following total hip arthroplasty (THA) may be asymptomatic until extensive bone loss occurs, early detection and monitoring the progression of these lesions is important. The purpose of this study was to use high resolution helical CT to determine the progression of the osteolytic lesions over time by comparing serial studies. Fifty patients (Fifty-eight hips) with primary, cementless THA done between 1984–1996 were evaluated as part of an ongoing prospective study. These patients had a history of a high level of activity that was believed to place them at increased risk for accelerated polyethylene wear. The mean age was 51 yrs, 55% male:45% female. The average time from date of surgery to initial scan was 8.0 years (4.7–16.6). If an acetabular lytic lesion was identified, the patients were offered Alendronate for potential suppression of bone resorption with a repeat CT scan for follow-up. The area of the maximum size osteolytic lesions on axial images were measured on the initial scan and compared at the same level on the subsequent study. The interval between scans averaged 15 months (10 – 27). Progression was noted on 87% hips. The mean initial area was 328 mm2 (40–1084) with the follow-up area of 386 mm2 (46–1344) with a mean of progression of 15.7%. Once established, peri-acetabular lysis appears to be a slowly progressive, relentless process. Analysis of changes on serial CT, along with an assessment of the degree and location of lysis, provides an additional tool to evaluate the need for surgical intervention

Periacetabular osteolysis is seen in response to particles (polyethylene, ceramic, metal or cement), at times in the presence of an unstable implant, and perhaps made worse by the unique host response to the particle burden. The impact of wear modes: due to either the primary bearing surface (MOP, MOM, COC) or unintended surfaces as seen in impingement, as well as the quality of the bearing counterface all influence the extent of the osteolytic response. The final common pathway appears to be via macrophage stimulation, an upregulation of cytokines leading to a resorption of bone.

The patterns of lysis range from linear resorption at the implant interface to more expansile patterns which can be more dramatic in size and may place the implant at jeopardy for loosening. Assessment of implant fixation as well as extent of the lytic process employs the use of plain radiographs (including oblique views), computerised tomography and magnetic resonance imaging. The utility of MRI for the quantification of bone loss as well as the newer phenomena of associated soft tissue lesions (pseudotumors, adverse tissue reactions) has turned out to be a valuable tool in helping determine timing and need for revision.

The basic principles in determining need for revision surgery revolve around: degree of lysis, integrity of the soft tissues, fixation of the implant, track record of the implant, as well as patient factors including symptoms, age and activity.

In cemented sockets, progressive bone loss, pain with or without overt loosening is indication for revision which is generally accomplished using an uncemented hemispherical acetabular component with bone graft and screw augmentation.

In the uncemented socket, the decision to revise is based upon a) implant stability, 2) the integrity of the locking mechanism, 3) degree of bone loss. With stable implants, polyethylene exchange and “lesional” treatment is appropriate. Well fixed implants with extensive lysis can be successfully managed with liner exchange and bone grafting as necessary. If the liner locking mechanism is compromised, cementing a liner into place is an excellent strategy. Removing a well fixed cup with extensive lysis runs the risk of encountering a large acetabular defect which may be difficult to reconstruct. Loose implants clearly require revision.

In the era of “hard bearings”, progressive soft tissue expansion leading to damage of the abductor and other soft tissue constraints about the hip is an indication for revision. Revision of MOM THR's may be performed by maintaining the femoral component and performing an isolated acetabular revision or in some instances of modular acetabular components, maintaining the shell and inserting a new liner. In all instances of implant retention, it is critical to confirm that the components are in optimised position: implants retained in suboptimal position are at risk for early failure.

Introduction

The periacetabular osteotomy (PAO) improves hip joint mechanics in patients with symptomatic dysplasia. As a consequence of the multi-planar acetabular re-orientation, the course of the iliopsoas tendon over the hip may be affected, potentially resulting in iliopsoas tendon-related pain. At present, little information regarding the incidence of iliopsoas-related pathology following PAO exists.

We aimed to identify the incidence of iliopsoas-related pain following PAO. Secondarily, we aimed to identify any risk factors associated with this pathology.

With cementless porous-coated acetabular replacements, extensive bone loss can occur without effecting implant stability. As a result, the surgeon is frequently faced with re-operating on a well-fixed cementless acetabular component with osteolysis and must decide whether or not to remove a well-fixed porous coated socket. A classification system and treatment algorithm has been developed to aid in management decisions regarding re-operation for polyethylene wear and pelvic osteolysis.

Cases are classified into one of 3 possible categories depending on the radiographic stability of the porous coated shell and the ability to replace the polyethylene liner. Type I case; stable porous coated shell, liner replaceable; Type II case; socket stable, liner not replaceable;

Type III case; socket loose, not osseointegrated.

Treatment Algorithms - Retain well-fixed shell in Type I cases and replace the liner. Debride accessible lytic lesions and graft with allograft chips. Remove the well-fixed shell in Type II case. Assess defect once the shell is removed. Reconstruction based on the bony defect present. The vast majority can be revised with a larger porous coated socket. Remove loose socket in Type III cases. Assess defect and reconstruct based on the defect. There is a greater need for more extensive grafting and the use of reconstruction rings with Type III cases.

This treatment algorithm has helped the authors successfully evaluate and treat a large series of patients with polyethylene wear and pelvic osteolysis in association with porous coated acetabular components. The stability of the acetabular component and appropriate knowledge of the implant are important factors that impact surgical management.

With cementless porous-coated acetabular replacements, extensive bone loss can occur without affecting implant stability. As a result, the surgeon is frequently faced with re-operating on a well-fixed cementless acetabular component with osteolysis and must decide whether or not to remove a well-fixed porous coated socket. A classification system and treatment algorithm has been developed to aid in management decisions regarding re-operation for polyethylene wear and pelvic osteolysis.

Cases are classified into one of 3 possible categories depending on the radiographic stability of the porous coated shell and the ability to replace the polyethylene liner. Type I case; stable porous coated shell, liner replaceable; Type II case; socket stable, liner not replaceable; Type III case; socket loose, not osseointegrated

Relative Contra-indications for Liner Exchange – Type II Case - Malpositioned socket, Severely damaged shell or lock detail (consider cementing shell in place), Poor track record of the implant, Highly crosslinked polyethylene liner of adequate thickness not available, Ongrowth (as opposed to ingrowth) fixation surface

Treatment Algorithm

Type I Case: Retain well-fixed shell in Type I cases and replace the liner. Debride accessible lytic lesions and graft with allograft chips.

Type II Case: Remove the well-fixed shell in Type II case. Assess defect once the shell is removed. Reconstruction based on the bony defect present. The vast majority can be revised with a larger porous coated socket.

Type III Case: Remove loose socket. Assess defect and reconstruct based on the defect. There is a greater need for more extensive grafting and the use of reconstruction rings with Type III cases.

This treatment algorithm has helped the authors successfully evaluate and treat a large series of patients with polyethylene wear and pelvic osteolysis in association with porous coated acetabular components. The stability of the acetabular component and appropriate knowledge of the implant are important factors that impact surgical management.

Polyethylene and femoral head exchange for wear or osteolysis is a common operation. The difficulty lies in the facts that wear and osteolysis are difficult to measure, wear does not always correlate with osteolysis, catastrophic failure (wear through, loosening, or fracture) is difficult to predict, and these problems are usually asymptomatic.

I currently recommend this procedure when complete wear through of the polyethylene is present or impending, when the patient has obvious wear and symptoms, or if there is a rapidly enlarging osteolytic lesion.

The surgical goals focus on management of debris generation and management of the osteolytic lesion. A third goal becomes avoidance of the know complications of this procedure. Management of debris generation basically involves modernising the head and polyethylene. Management of the osteolytic lesion includes debridement and when possible grafting. By far the most common complication after this procedure is dislocation. Prevention of dislocation should be accomplished by patient education, use of larger heads when possible, and capsular repair.

Prerequisites to perform this procedure are a replacement liner of adequate thickness that can be locked or cemented in place. The acetabular component must be stable. Lastly the component must be properly oriented to minimise both wear and dislocation.

Metal-on-metal liner conversion to metal-on-poly is becoming more common. Since patient satisfaction with THA is high, MoM patients may unknowingly minimise their symptoms because they are minor compared to the symptoms before surgery. The patient history should include specific questions about groin pain, swelling, hip noise, and asking the patient if they notice their hip on a daily basis. Patient symptoms, osteolysis and a pseudotumor are indications for modular conversion. Radiographically stable, well-oriented components that can accept a polyethylene liner are requirements for a successful conversion.

Polyethylene and femoral head exchange for wear or osteolysis is a common operation. The difficulty lies in the facts that wear and osteolysis are difficult to measure, wear does not always correlate with osteolysis, catastrophic failure (wear through, loosening, or fracture) is difficult to predict, and these problems are usually asymptomatic.

I currently recommend this procedure when complete wear through of the polyethylene is present or impending, when the patient has obvious wear and symptoms, or if there is a rapidly enlarging osteolytic lesion.

The surgical goals focus on management of debris generation and management of the osteolytic lesion. A third goal becomes avoidance of the know complications of this procedure. Management of debris generation basically involves modernising the head and polyethylene. Management of the osteolytic lesion includes debridement and when possible grafting. By far the most common complication after this procedure is dislocation. Prevention of dislocation should be accomplished by patient education, use of larger heads when possible, and capsular repair.

Prerequisites to perform this procedure are a replacement liner of adequate thickness that can be locked or cemented in place. The acetabular component must be stable. Lastly the component must be properly oriented to minimise both wear and dislocation.

Objective: Severe acetabular dysplasia with established dislocation of the hip represents a common problem in cerebral palsy. Once significant dysplasia is present little remodeling of the acetabulum occurs with femoral osteotomies alone. Pelvic osteotomies should address the problem of acetabular deficiency in order to restore optimal coverage of the femoral head. Standard innominate osteotomies are not recommended for neuromus-cular hip dysplasia. To address the lack of postero-lateral coverage in this population, a modified periacetabular osteotomy was performed.

Methods: Between 1991 and 2000 a total of 44 patients (52 hips) with total body involvement CP underwent this procedure at a mean age of 9,4 yrs. The modification includes only one bicortical cut at the posterior corner at the sciatic notch. The cut extends down to the trira-diate cartilage, if present, and through the former site of the triradiate cartilage after closure of the acetabu-lar growth plate in adolescence. Additional procedures included: open reduction, femoral varus osteotomy, and soft tissue releases. Follow-up included a subjective and clinical evaluation. Radiographic assessment included measurements of the migration percentage and acetab-ular index, evidence of AVN, and premature closure of the triradiate cartilage.

Results: The mean follow-up period for these patients was 3.5 years (1.0 to 8,1 yrs) after surgery, and 70% of the patients had reached skeletal maturity at that time. The median acetabular index improved from 30% pre-operatively to 18% at follow-up. The median migration percentage was 71% preoperatively, and 0 at follow-up. A re-dislocation occurred in 1 hip, and a re-subluxation in another. All other hips were stable and well contained at follow-up. There were 3 hips showing signs of postoperative femoral head defects . Premature closure of the triradiate cartilage was not noted. The caregivers had the impression that the surgery had improved personal care, positioning/transferring, and comfort.

Conclusions: This osteotomy reduces the volume of the elongated acetabulum and provides coverage by articular cartilage. It provides coverage particularly at the posterior part of the acetabulum. Compared to other techniques this modified periacetabular osteotomy has only one posterior cortical cut which extends down to the sciatic notch. Since this cut is cortical, the fragment can be mobilized extensively and it allows placement of a graft and a better posterior coverage.

The reconstruction of peri-acetabular defects after severe bone loss or pelvic resection for tumor is among the most challenging surgical intervention. The Lumic® prosthesis (Implantcast, Buxtehude, Germany) was first introduced in 2008 in an effort to reduce the mechanical complications encountered with the classic peri-acetabular reconstruction techniques and to improve functional outcomes. Few have evaluated the results associated with the use of this recent implant. A retrospective study from five Orthopedic Oncology Canadian centers was conducted. Every patient in whom a Lumic® endoprosthesis was used for reconstruction after peri-acetabular resection or severe bone loss with a minimal follow-up of three months was included. The charts were reviewed and data concerning patients’ demographics, peri-operative characteristics and post-operative complications was collected. Surgical and functional outcomes were also assessed. Sixteen patients, 11 males and five females, were included and were followed for 28 months [3 – 60]. Mean age was 55 [17–86], and mean BMI reached 28 [19.6 – 44]. Twelve patients (75%) had a Lumic® after a resection of a primary sarcoma, two following pelvic metastasis, one for a benign tumor and one after a comminuted acetabular fracture with bone loss. Twelve patients (75%) had their surgery performed in one stage whereas four had a planned two-stage procedure. Mean surgical time was 555 minutes [173-1230] and blood loss averaged 2100 mL [500-5000]. MSTS score mean was 60.3 preoperatively [37.1 – 97] and 54.3 postoperatively [17.1-88.6]. Five patients (31.3%) had a cemented Lumic® stem. All patients got the dual mobility bearing, and 10 patients (62.5%) had the largest acetabular cup implanted (60 mm). In seven of these 10 patients the silver coated implant was used to minimize risk of infection. Five patients (31.3%) underwent capsular reconstruction using a synthetic fabric aiming to reduce the dislocation risk. Five patients had per-operative complications (31.3%), four were minor and one was serious (comminuted iliac bone fracture requiring internal fixation). Four patients dislocated within a month post-operatively and one additional patient sustained a dislocation one year post-operatively. Eight patients (50%) had a post-operative surgical site infection. All four patients who had a two-stage surgery had an infection. Ten patients (62.5%) needed a reoperation (two for fabric insertion, five for wash-outs, and three for implant exchange/removal). One patient (6.3%) had a septic loosening three years after surgery. At the time of data collection, 13 patients (81.3%) were alive with nine free of disease. Silver coating was not found to reduce infection risk (p=0.2) and capsuloplasty did not prevent dislocation (p=1). These results are comparable to the sparse data published. Lumic® endoprosthesis is therefore shown to provide good functional outcomes and low rates of loosening on short to medium term follow-up. Infection and dislocation are common complications but we were unable to show benefits of capsuloplasty and of the use of silver coated implants. Larger series and longer follow-ups are needed

The reconstruction of peri-acetabular defects after severe bone loss or pelvic resection for tumor is among the most challenging surgical intervention. The Lumic® prosthesis (Implantcast, Buxtehude, Germany) was first introduced in 2008 in an effort to reduce the mechanical complications encountered with the classic peri-acetabular reconstruction techniques and to improve functional outcomes. Few have evaluated the results associated with the use of this recent implant. A retrospective study from five Orthopedic Oncology Canadian centers was conducted. Every patient in whom a Lumic® endoprosthesis was used for reconstruction after peri-acetabular resection or severe bone loss with a minimal follow-up of three months was included. The charts were reviewed and data concerning patients’ demographics, peri-operative characteristics and post-operative complications was collected. Surgical and functional outcomes were also assessed. Sixteen patients, 11 males and five females, were included and were followed for 28 months [3 – 60]. Mean age was 55 [17-86], and mean BMI reached 28 [19.6 – 44]. Twelve patients (75%) had a Lumic® after a resection of a primary sarcoma, two following pelvic metastasis, one for a benign tumor and one after a comminuted acetabular fracture with bone loss. Twelve patients (75%) had their surgery performed in one stage whereas four had a planned two-stage procedure. Mean surgical time was 555 minutes [173-1230] and blood loss averaged 2100 mL [500-5000]. MSTS score mean was 60.3 preoperatively [37.1 – 97] and 54.3 postoperatively [17.1-88.6]. Five patients (31.3%) had a cemented Lumic® stem. All patients got the dual mobility bearing, and 10 patients (62.5%) had the largest acetabular cup implanted (60 mm). In seven of these 10 patients the silver coated implant was used to minimize risk of infection. Five patients (31.3%) underwent capsular reconstruction using a synthetic fabric aiming to reduce the dislocation risk. Five patients had per-operative complications (31.3%), four were minor and one was serious (comminuted iliac bone fracture requiring internal fixation). Four patients dislocated within a month post-operatively and one additional patient sustained a dislocation one year post-operatively. Eight patients (50%) had a post-operative surgical site infection. All four patients who had a two-stage surgery had an infection. Ten patients (62.5%) needed a reoperation (two for fabric insertion, five for wash-outs, and three for implant exchange/removal). One patient (6.3%) had a septic loosening three years after surgery. At the time of data collection, 13 patients (81.3%) were alive with nine free of disease. Silver coating was not found to reduce infection risk (p=0.2) and capsuloplasty did not prevent dislocation (p=1). These results are comparable to the sparse data published. Lumic® endoprosthesis is therefore shown to provide good functional outcomes and low rates of loosening on short to medium term follow-up. Infection and dislocation are common complications but we were unable to show benefits of capsuloplasty and of the use of silver coated implants. Larger series and longer follow-ups are needed

The April 2015 Hip & Pelvis Roundup. 360 . looks at: Goal-directed fluid therapy in hip fracture; Liberal blood transfusion no benefit in the longer term; Repeated measures: increased accuracy or compounded errors?; Peri-acetabular osteotomy safer than perhaps thought?; Obesity and peri-acetabular osteotomy: poor bedfellows; Stress fracture in peri-acetabular osteotomy; Infection and tantalum implants; Highly crosslinked polyethylene really does work

Mixed Reality has the potential to improve accuracy and reduce required dissection for the performance of peri-acetabular osteotomy. The current work assesses initial proof of concept of MR guidance for PAO. A PAO planning module, based on preoperative computed tomography (CT) imaging, allows for the planning of PAO cut planes and repositioning of the acetabular fragment. 3D files (holograms) of the cut planes and native and planned acetabulum positions are exported with the associated spatial information. The files are then displayed on mixed reality head mounted device (HoloLens2, Microsoft) following intraoperative registration using an FDA-cleared mixed reality application designed primary for hip arthroplasty (HipInsight). PAO was performed on both sides of a bone model (Pacific Research). The osteotomies and acetabular reposition were performed in accordance with the displayed holograms. Post-op CT imaging was performed for analysis. Cutting plane-accuracy was evaluated using a best-fit plane and 2D angles (°) between the planned and achieved supra (SA)- and retroacetabular (RA) osteotomy and retroacetabular and ischial osteotomies (IO) were measured. To evaluate the accuracy of acetabular reorientation, we digitized the acetabular rim and calculated the acetabular opening plane. Absolute errors of planned and achieved operative inclination and anteversion (°) of the acetabular fragment, as well as 3D lateral-center-edge (LCE) angles were calculated. The mean absolute difference between the planned and performed osteotomy angles was 3 ± 3°. The mean absolute error between planned and achieved operative anteversion and inclination was 1 ± 0° and 0 ± 0° respectively. Mean absolute error between planned and achieved 3D LCE angle was 0.5 ± 0.7°. Mixed-reality guidance for the performance of pelvic osteotomies and acetabular fragment reorientation was feasible and highly accurate. This solution may improve the current standard of care by enabling reliable and precise reproduction of the desired acetabular realignment