Impaction Grafting Research Articles

Fracture of the C-Stem cemented femoral component in revision hip surgery using bone impaction grafting technique: report of 9 cases.

We present a series of 9 fractures of a C-Stem femoral component (6 long stems and 3 conventional stems) that had been implanted with the use of impaction bone grafting (IBG). The length of the long fractured stems was 240 mm in 4 cases and 200 mm in 2. The patients presented had an average BMI of 26.5 and an average of 2.7 previous hip surgeries (range 2-5 surgeries) before the stem fracture. A total of 5 cases presented with a metal mesh fracture in addition to the fractured stem. Bending of the stems or stem defects was not observed in any case. Typical fracture waves consistent with fatigue failure were clearly visible on all the cut surfaces, starting anterolaterally and propagating to the medial side. Although fatigue fracture of a modern cemented tapered polished femoral stem is a rare event, stress due to the absence of proximal femoral bone support could be sufficient to put this stem at a higher risk for fatigue fracture in non-obese patients.

Impaction bone grafting has potential as an adjunct to the surgical stabilisation of osteoporotic tibial plateau fractures: Early results of a case series

IntroductionOsteoporotic tibial plateau fractures (TPFs) are difficult to treat with either open reduction internal fixation (ORIF) or acute total knee arthroplasty (TKA). They have high complication rates, poor outcomes and often fail in the short- to mid-term. We investigated the use of impaction bone grafting (IBG) as an adjunct to stabilise the fracture in a cohort of osteoporotic TPFs. MethodsNine consecutive osteoporotic TPFs were surgically stabilised with ORIF augmented with IBG or with IBG alone (one pure depression fracture) using on average allograft from 2 femoral heads/case (range 1–4 heads or 25–100cm3). The median bone mineral density T-score of the patients was −2.9 (−2.5 to −4.5). All patients were mobilised weight-bearing as tolerated immediately after surgery and had regular follow-up to a minimum of 2 years where functional scores were taken and gait was assessed. Fracture reduction was assessed on plain radiographs and computed tomography (CT) scans; maintenance of fracture reduction was monitored using plain radiographs, CT and radiostereometric analysis (RSA). Bone graft remodelling was assessed by comparison of immediate post-operative CT scans with scans at a minimum of 1 year. ResultsAll surgeries were uneventful. All patients progressed to full weight bearing within 6 weeks of surgery and regained a normal gait by 3 months. Seven fractures healed with a cranio-caudal migration of less than 3mm (range 0–2.6mm using RSA and 0–2mm using CT). Two fractures had an isolated posterolateral fragment depression of 13.5mm and 9mm, respectively, which did not affect the overall joint alignment or clinical outcomes at short-term follow-up. At latest CT follow-up, on average 51% of the graft area (range 36–70%) had remodelled into new host bone. ConclusionImpaction bone grafting shows promising results as an adjunct to the surgical stabilisation of osteoporotic TPFs. In this case series the technique provided enough fracture stability for patients to mobilise weight-bearing as tolerated immediately after surgery and achieve full weight-bearing by the sixth postoperative week. There was no failure of fixation and 7 of the 9 cases healed with minimal fracture displacement.

Acetabular reconstruction with impaction bone grafting and cemented polyethylene socket in total hip revision arthroplasty.

Bone deficiency in revision total hip arthroplasty is a challenge to the surgeon. One option for restoration of the bone stock is impaction bone grafting and use of a cemented socket. The aim of this study was to evaluate the mid-term clinical outcome of impaction bone grafting and cemented socket revisions. A total of 59 patients (60 hips) underwent revision arthroplasty with impaction bone grafting and application of a cemented socket on the acetabular side in the Turku University Hospital from 1999 to 2004. The study end-point was re-revision for any reason. The cumulative percentages for survival were followed and estimated with Kaplan-Meier curves. Associations between occurrence of re-revision and potential risk factors were analyzed with logistic regression. Results were quantified by odd ratios and 95% confidence intervals. The mean age of the patients was 69 years (33% male). A total of 3% of the patients had a class I Paprosky acetabular defect, 38% had class II, and 55% had class III. The overall survival rate was 73%. The mean follow-up time was 7 years. The most common reason for re-revision was aseptic loosening of the acetabular component (13 patients, 81% of re-revisions). Cox's regression analysis did not identify any risk factors for re-revision. Our results were inferior compared to some previous studies. Impaction bone grafting of acetabular defects in revision total hip arthroplasty may not always provide a reliable bone stock in long-term.

The clinical study of therapy for early-stage femoral head necrosis with technique of rotary cutting pressure-relief, bone grafting, and tantalum rod supporting

Objective To investigate new methods of osteonecrosis of femoral head (ONFH) with retrospective analysis of the clinical cases with technique of rotary cutting pressure-relief, impacted graft, and tantalum rod supporting treatment of early-stage femoral head necrosis. Methods From June 2010 to June 2014, 32 cases (38 hips, 23 males and 9 females) with ONFH were treated with technique of rotary cutting pressure-relief, impacted graft, and tantalum rod supporting, with the mean age of 24~52 (36.2±3.8) years old. According to the Association Research Circulation Osseous (ARCO) classification, there were 11 hips on ⅡA stage, 12 hips ⅡB, 8 hips ⅡC, 7 hips ⅢA. The averaged Harris score of all cases was 65~81 (72.5±5.8) points. All cases were cured with minimally invasive technique, rotary cutter pressure-relief in femoral head, thoroughly remove sequestrum and implant allogeneic bone. Postoperative patients laid in bed for 1 month, after 1 month hold crutch gradually began to functional training. Postoperative 1 month, X ray film was reviewed every 3 months. According to the clinical symptoms, imaging findings, Harris scoring system was graded to evaluate the effectiveness. Results All the cases were followed up for average of 12~32 (20.2 ±2.6) months, 31 hips Kept hips succeed, hips pain; lame line symptoms were reduced or disappeared; x-ray showed femoral head necrosis area formed new bone, Harris scoring was upgraded to 75~95 (87.7±6.4) points; and seven hips failed with operation of total hip arthroplasty. The overall good rate was promoted from 26.3% to 84.2%. Conclusions The technique treating for early-stage femoral head necrosis with minimally invasive, rotary cutting pressure-relief, impacted graft, and tantalum rod supporting had a good short-term effects. Key words: Bone transplantation; Femur head necrosis/surgery; Tantalum/therapeutic use; Decompression; Surgical procedures, minimally invasive

A 42-year-old patient presenting with femoral head migration after hemiarthroplasty performed 22 years earlier: a case report.

IntroductionTreatment of femoral neck fractures in young adults may require total hip arthroplasty or hip hemiarthroplasty using a bipolar cup. The latter can, however, result in migration of the femoral head and poor long-term results.Case presentationWe report a case of femoral head migration after hemiarthroplasty performed for femoral neck fracture that had occurred 22 years earlier, when the patient (a Japanese man) was 20 years old. He experienced peri-prosthetic fracture of the femur, subsequent migration of the prosthesis, and a massive bone defect of the pelvic side acetabular roof. After bone union of the femoral shaft fracture, the patient was referred to our hospital for reconstruction of the acetabular roof. Intra-operatively, we placed two alloimplants of bone from around the transplanted femoral head into the weight-bearing region of the acetabular roof using an impaction bone graft method. We then implanted an acetabular roof reinforcement plate and a cemented polyethylene cup in the position of the original acetabular cup. Eighteen months post-operatively, X-rays showed union of the transplanted bone.ConclusionsTreatment of femoral neck fractures in young adults is usually accomplished by osteosynthesis, but it may be complicated by femoral head avascular necrosis or by infection or osteomyelitis. In such cases, once an infection has subsided, either hip hemiarthroplasty using a bipolar cup or total hip arthroplasty may be required. However, if the acetabular side articular cartilage is damaged, a bipolar cup should not be used. Total hip arthroplasty should be performed to prevent migration of the implant.

Total hip replacement for arthritis following tuberculosis of hip.

To present the results of total hip arthroplasty (THA) for post tubercular arthritis of the hip joint. Sixty-five patients (45 male, 20 female) with previously treated tuberculosis of the hip joint underwent cementless THA for post tubercular arthritis. The average age at the time of THA was 48 years (range 29 to 65 years). Erythrocyte sedimentation rate, C reactive protein, chest X-ray and contrast enhanced magnetic resonance imaging were done preoperatively to confirm resolution of the disease and to rule out any residual disease. Intra-operative samples were taken for microbiological examination, polymerase chain reaction (PCR) and histological examination. Patients were started on anti-tubercular drugs one week before the operation and continued for 6 mo post operatively. The patients were followed up clinically using the Harris hip score as well as radiologically for any loosening of the implants, osteolysis and any recurrence of tuberculosis. Any complications especially the recurrence of the infection was also recorded. The mean interval from completion of antitubercular therapy for tuberculosis to surgery was 4.2 years (range, 2-6 years). Preoperatively, 17 patients had ankylosis whereas 48 patients had functional but painful range of motion. The mean surgical time was 97 min (range, 65-125) whereas the mean blood loss was 600 mL (range, 400-900 mL). The average follow up was 8.3 years (range 6-11 years). The average Harris Hip score improved from 27 preoperatively to 91 at the final follow up. Seventeen patients had acetabular protrusion which was managed with impaction grafting and cementless acetabular cup. The bone graft had consolidated in all these 17 patients at the follow up. Two patients developed discharging sinuses at 9 and 11 mo postoperatively respectively. The discharge tested positive for tuberculosis on the PCR. Both these patients were put on antitubercular therapy for another year. Both of them recovered and had no evidence of any loosening or osteolysis on X-rays. There were no other complications recorded. Total hip replacement restores good function to patients suffering from post tubercular arthritis of the hip.

Management of neglected acetabular fractures.

Management of neglected acetabular fractures is a difficult task. Osteosynthesis in such cases may not be an ideal solution because of the femoral head damage due to pressure by the fractured acetabular edge, avascular necrosis, difficulty in mobilizing the fragments due to callus formation, difficulty in indirect reduction of the fracture fragments and macerated acetabular fragments all contributing to inadequate fracture reduction. Majority of such fractures are now treated with total hip replacement. While treating such fractures with THR, problems associated with neglected acetabular fractures such as fracture non-union, hip dislocation, protrusio, cavitary bone defect or peripheral bone defect must be considered. 3D computed tomography scan provides a clear view about the acetabular and periacetabular bony anatomy. Impaction grafting and antiprotrusio cage or ring with a cemented acetabular cup can address most of the hip protrusio and cavitary bone defects. Segmental bone defect needs cortical strut-bone graft fixation and subsequent implantation of a cemented or uncemented acetabular cup implantation. Fracture non-union needs approximate reduction and fixation with plates followed by bone grafting and implantation of an acetabular cup. Despite these efforts, the outcome of THR in neglected acetabular fracture is considerable worse than after conventional hip replacement.

Acetabular re-revision with impaction bone grafting and a cemented polyethylene cup; a biological option for successive reconstructions.

For the revision of failed acetabular components impaction bone grafting (IBG) with a cemented cup is a well known technique. Claims have been made that this is a biological reconstruction technique, restoring the bone stock loss and thereby facilitating future revisions. However, there are no scientific data proving this claim. In this study, we present the clinical and radiographic outcome of 11 consecutive acetabular re-revisions in 10 patients with again IBG and a cemented polyethylene cup observed in a previously reported cohort of 62 acetabular IBG revisions. All data were prospectively collected. Kaplan-Meier survivorship analysis was performed. The mean follow-up after re-revision was 10 years (5-15) and 28 years (26-30) after the primary revision. No patients were lost to follow-up. The mean HHS improved from 37 (12-49) points to 71 (40-95) points at final follow-up. Survival with further cup revision for any reason as endpoint was 91% (95% confidence interval (CI) 51 to 99) at 10 years. When excluding one early cup re-revision for malpositioning 3 weeks postoperative, survivorship with further cup revision for aseptic loosening as endpoint was 100% (95% CI 37-100) at 10 years. Survival with further cup re-operation for any reason as endpoint was 82% (95% one-sided CI 45-95). In all surviving re-revisions trabecular incorporation was observed without radiolucent lines. This study shows that, due to restoring the bone stock, even successive acetabular reconstructions using IBG and a cemented cup are possible with satisfying 10 years survivorship.

Acetabular defect reconstruction in revision hip arthroplasty with a modular revision system and biological defect augmentation.

Revision of failed total hip arthroplasty with severe acetabular bone loss represents a rare but challenging problem. Anatomic reconstruction with biological defect augmentation as solid bone transplants or cancellous bone restores bone stock while providing good component stability. The objective of this study was to present short- to mid-term results of revision total hip arthroplasty with a modular ring system in a consecutive series of patients with severe acetabular bone loss. We retrospectively reviewed 39 consecutive patients (39 hips) with severe acetabular bone loss (Paprosky type 3 A and 3 B) reconstructed with revision total hip arthroplasty using the cementless modular ring system MRS-Titan®. The MRS-Titan® consists of independent ring systems that are adapted modularly to the defect situation. Combined with acetabular defect reconstruction by using cancellous bone in impaction grafting technique, the MRS-Titan® system offers a cement-free revision system that enables defect-adapted customization to individual anatomic matters, bridging of the acetabular bone defect and reconstruction of the centre of rotation. Initial stability of the implant was obtained by screw fixation. Harris hip score and sequential radiographs were used to evaluate clinical and radiographic results. At an average follow up of 31 months (range 12-69 months) 33 of 39 (84.6 %) of the implants were considered radiographically stable without signs of acetabular migration of more than 2 mm in the horizontal or vertical direction, implant rotation or screw breakage. Complications included six implant failures (15 %). We recorded one aseptic loosening of the MRS prosthesis after 20 months. Five patients (12.8 %) had to undergo revision surgery because of periprosthetic joint infection. Two patients had a dislocation postoperatively. The mean Harris hip score improved from 27 ± 14 points preoperatively to 76 ± 15 points at the time of last follow up. By achieving stable implant fixation and providing potential for biological fixation, treatment of severe acetabular bone loss in revision total hip arthroplasty with the modular ring system MRS-Titan provides a durable solution with good clinical and radiographic results and allows us to accomplish major goals of reconstruction.

Porous titanium particles for acetabular reconstruction in total hip replacement show extensive bony armoring after 15 weeks

Background and purpose — The bone impaction grafting technique restores bone defects in total hip replacement. Porous titanium particles (TiPs) are deformable, like bone particles, and offer better primary stability. We addressed the following questions in this animal study: are impacted TiPs osteoconductive under loaded conditions; do released micro-particles accelerate wear; and are systemic titanium blood levels elevated after implantation of TiPs?Animals and methods — An AAOS type-III defect was created in the right acetabulum of 10 goats weighing 63 (SD 6) kg, and reconstructed with calcium phosphate-coated TiPs and a cemented polyethylene cup. A stem with a cobalt chrome head was cemented in the femur. The goats were killed after 15 weeks. Blood samples were taken pre- and postoperatively.Results — The TiP-graft layer measured 5.6 (SD 0.8) mm with a mean bone ingrowth distance of 2.8 (SD 0.8) mm. Cement penetrated 0.9 (0.3–1.9) mm into the TiPs. 1 reconstruction showed minimal cement penetration (0.3 mm) and failed at the cement-TiP interface. There were no signs of accelerated wear, metallic particle debris, or osteolysis. Median systemic titanium concentrations increased on a log-linear scale from 0.5 (0.3–1.1) parts per billion (ppb) to 0.9 (0.5–2.8) ppb (p = 0.01).Interpretation — Adequate cement pressurization is advocated for impaction grafting with TiPs. After implantation, calcium phosphate-coated TiPs were osteoconductive under loaded conditions and caused an increase in systemic titanium concentrations. However, absolute levels remained low. There were no signs of accelerated wear. A clinical pilot study should be performed to prove that application in humans is safe in the long term.

The Evolution of the Technique of Impaction Bone Grafting in Femoral Revision Surgery has Improved Clinical Outcome. A Prospective Mid-Term Study

Ninety-three patients (97 hips) underwent impaction bone grafting (IBG) using a cemented tapered femoral stem at our institution. Forty-one hips were operated between 1993 and 1998 (group 1) and 56 hips between 1999 and 2007 (group 2). The use of an extended trochanteric osteotomy and a long stem was more frequent in group 2. Group 2 hips showed a better clinical result. One hip was revised for aseptic loosening and most failures were early periprosthetic fractures. The survival rate for reoperation for any cause was 82.9% for group 1 and 84.3% for group 2. Patients in group 1 had a higher risk for periprosthetic fractures and radiological subsidence >5mm. Experience and the evolution of the IBG technique have improved the good long-term outcome.

Incorporation of raloxifene-impregnated allograft around orthopedic titanium implants impairs early fixation but improves new bone formation

Background — The anti-osteoporotic drug raloxifene reduces the risk of vertebral fractures by increasing bone mass density. We investigated whether raloxifene offers any benefits in augmenting early fixation of orthopedic implants in the setting of impaction bone grafting. Methods — 24 non-weight-bearing grafted gap implants were inserted bilaterally into the tibia of 12 dogs. The 2.5-mm peri-implant gap was filled with either raloxifene-impregnated or untreated bone allograft. Implants were harvested after 28 days. Implant fixation was assessed by mechanical testing and histomorphometric evaluation. Results — Raloxifene-treated allograft reduced early implant fixation compared to untreated allograft, as measured by inferior maximum shear strength (p < 0.001) and apparent shear stiffness (p = 0.001). We found that the raloxifene group had more newly formed bone in the gap around the implant (p = 0.02), but also less allograft (p = 0.03). Interpretation — The accelerated allograft resorption in the raloxifene group explained the impaired early fixation, despite its stimulation of new bone formation. Our results with local and possible high-dose treatment are not consistent with current theory regarding the mechanism of how systemic raloxifene administration counteracts the decrease in BMD in postmenopausal women. Instead of being solely anti-resorptive as generally held, our results indicate a possible anabolic side of raloxifene.

Autograft reconstructions for bone defects in primary total knee replacement in severe varus knees.

Background:Large posteromedial defects encountered in severe varus knees during primary total knee arthroplasty can be treated by cementoplasty, structural bone grafts or metallic wedges. The option is selected depending upon the size of the defect. We studied the outcome of autograft (structural and impaction bone grafting) reconstruction of medial tibial bone defects encountered during primary total knee replacement in severe varus knees.Materials and Methods:Out of 675 primary varus knees operated, bone defects in proximal tibia were encountered in 54 knees. Posteromedial defects involving 25-40% of the tibial condyle cut surface and measuring more than 5 mm in depth were grafted using a structural graft obtained from cut distal femur or proximal tibia in 48 knees. For larger, peripheral uncontained vertical defects in six cases, measuring >25 mm in depth and involving >40% cut surface of proximal tibial condyle, impaction bone grafting with a mesh support was used.Results:Bone grafts incorporated in 54 knees in 6 months. There was no graft collapse or stress fractures, loosening or nonunion. The average followup period was 7.8 years (range 5-10 years). We observed an average postoperative increase in the Knee Society Score from 40 to 90 points. There was improvement in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores in terms of pain, stiffness and physical function during activities of daily living.Conclusion:Bone grafting for defects in primary total knee is justified as it is biological, available then and is cost effective besides preserving bone stock for future revisions. Structural grafts should be used in defects >5 mm deep and involving 25-40% of the cut proximal tibial condyle surface. For larger peripheral vertical defects, impaction bone grafting contained in a mesh should be done.

The Impact of Patellar Resurfacing in Two-Stage Revision of the Infected Total Knee Arthroplasty

Evidence for optimal management of the patellofemoral joint in revision surgery for the infected TKA is limited. We reviewed 69 infected TKAs undergoing two-stage revision. Fifty four patellae were resurfaced, 11 had patelloplasty performed, two were augmented with trabecular metal, one had impaction grafting, and one knee underwent patellectomy. Average follow-up was 4.5years. The patients that received patellar resurfacing at re-implantation experienced statistically significant improvements in KSS pain score, functional KSS, and patellar score (P<0.03). One further patient treated with impaction grafting improved significantly in terms of pain and function. Patients treated with patelloplasty, trabecular metal augmentation, or patellectomy did not have significant improvements in clinical or functional outcome. Patient age, use of dynamic vs. static spacer, use of extensor mechanism release, and differences in Charlson index did not seem to statistically affect outcome. We recommend that every effort should be made to minimize patellar bone loss in first stage resection, as inability to resurface the patella at time of reimplantation may adversely affect patient outcome.

Optimizing the grain size distribution of allografts in bone impaction grafting.

In bone impaction grafting, allografts in the form of bone chips are used for reconstruction of defects and to induce bone remodeling. Optimizing grain size distribution of this allograft material should help prevent implant subsidence by achieving higher primary stability of the graft. We evaluated the influence of grain size distribution on the mechanical stability of allograft material. Bone tissue was rinsed, and the grain size distribution of the allograft material was determined by performing a sieve analysis. Uniaxial compression tests were carried out before and after a standardized compaction procedure for samples with controlled grain size distribution and a control group. Allografts with controlled grain size distribution showed a yield limit almost twice as high as in the control group after a standardized compaction procedure. A better interlocking between bone particles was observed compared to the control group. Thus, grain size distribution has a major impact on the mechanical stability of bone grafts. By controlling the grain size distribution of allograft material, a tighter packing can be achieved and subsequently implant subsidence of implants could be avoided.

Correction of post-traumatic kyphosis in the thoracolumbar spine through Ponté osteotomy and interbody fusion with impacted morsellized bone graft

Objective To describe Ponte osteotomy and interbody fusion with impacted morsellized bone graft and to investigate the safety and efficacy for the correction of post-traumatic kyphosis (PTK) in the thoracolumbar spine.Methods From June 2010 to March 2013,13 patients with PTK in the thoracolumbar spine were treated through Ponte osteotomy and interbody fusion with impacted morsellized bone graft.There were 7 males and 6 females,aged from 32 to 78 years,average 54.5 years.The apex level of kyphosis was T11 in 1,T12 in 4,L1 in 5 and L2 in 3.There was failure of first surgery in seven patients,and inappropriate conservative treatment in six,that all suffered from pain,progressive deformity,and deteriorating neurologic status.During the operation,the intervertebral space was loosened radically through Ponte osteotomy and discectomy,and the kyphosis was firstly corrected using the morcellized impacted graft technique.Then the kyphosis was corrected using the correction rod technique with the hinge of the morcellized impacted graft.Radiographical assessments included localized kyphosis,thoracic kyphosis,lumbar lordosis,sacral tilt angle,sagittal vertical axis,bony fusion and the relative height of the interbody fusion vertebra.Visual analogue scale (VAS),Oswestry disability index (ODI) and ASIA were evaluated before and after surgery,and the operative duration,blood loss were recorded.Results All patients were successfully followed up for an average time of (20.0±9.1) months.Bony fusion was achieved in all patients at 12 months follow-up.Localized kyphosis was reduced from an average of 42.2° (26° to 54°) to 7.1° (-7° to 13°) with an correction rate of 83.2％ on average.Sagittal alignment from T1 to the sacrum became more physiologic from 2.91cm (-3.0 to 7.8 cm) to 1.35cm (-0.5 to 3.8 cm).Thoracic kyphosis,lumbar lordosis and sacral tilt angle all improved at followup.The average VAS score was 6.38±0.87 (range,5 to 8) before operation and 2.23±0.83 (range,1 to 4) at final follow-up.The average ODI score was 55.0± 12.1 (range,39 to 72) before operation and 20.6±7.3 (range,11 to 34) at final follow-up.Neurological function improved from C to D in two patients,from C to E in four patients,and from D to E in seven patients.Conclusion Application of Ponte osteotomy and interbody fusion with impacted morsellized bone graft for the correction of PTK in the thoracolumbar spine has several advantages:large angle correction,high fusion rate,mini-invasion,and little nerve complications. Key words: Thoracic vertebrae; Lumbar vertebrae; Spinal fractures; Kyphosis; Spinal fusion; Bone transplantation

Excessive polyethylene wear and acetabular bone defects from standard use of a hooded acetabular insert in total hip arthroplasty

In total hip arthroplasty (THA) the use of a polyethylene (PE) insert with a hooded rim can be considered to reduce dislocation risks. This benefit has to be balanced against the potential introduction of impingement of the femoral component on this rim. We present a case series of early acetabular revisions for excessive PE wear and acetabular bone defects from overuse of such a hooded rim insert. Twenty-eight patients with 34 consecutive early acetabular revisions were evaluated on failure mechanism. One type of implant was used in all cases. Standard pelvic radiographs and pre-operative CT scans were used to quantify PE wear, implant positioning and acetabular bone defects. An acetabular revision with impaction grafting was performed in all cases with a mean cup survival of ten years (range 1.3-19.3). No concurrent stem revisions were necessary. Overall implant positioning was adequate with a mean cup inclination of 45° (range 39-57) and anteversion of 25° (range eight to 45). The mean PE wear was 0.24 mm/year (range 0.00-1.17). The mean acetabular bone defect on pelvic CT scans was calculated as 352 mm² (range zero to 1107) and 369 mm² (range zero to 1300) in the coronal and transversal planes, respectively. A hooded acetabular insert was retrieved in all cases and profound PE wear, typically from the posterior hooded rim, was encountered. The use of hooded acetabular inserts may be considered to improve implant stability intra-operatively. This case series clearly presents that together with these devices, component impingement with concordant complications such as accelerated PE wear may be introduced. Standard use of these stabilizing inserts should thus be avoided.

Biologisch azetabuläre Defektrekonstruktion beim Hüftendoprothesenwechsel mittels „Impaction Grafting“ und azetabulärem Rekonstruktionsring

Management of acetabular bone defects Paprosky types IIa and IIb in revision hip arthroplasty by rebuilding the bone stock using impaction bone grafting, primary stable reconstruction with an acetabular reconstruction ring, and restoring the hip center of rotation to its anatomical position. Acetabular segmental or combined structural defects in the superior acetabular dome with superior/lateral hip center migration with intact anterior and posterior columns (Paprosky types IIa, IIb). Acute or chronic infections, severe acetabular bone defects preventing adequate anchorage of the prosthesis-particularly destruction of the posterior column. Modified transgluteal, lateral approach to the hip joint. Removal of the loose acetabular component. Complete circumferential exposure of the acetabular rim, while maintaining mechanical stability of the remaining bone. Preparation of the homologous spongiosa chips and reconstruction of the acetabular defect in impaction grafting technique. Implantation of the acetabular reconstruction ring and primary stable fixation with cancellous screws in the acetabular dome. Cemented fixation of a polyethylene inlay. Mobilization on 2underarm crutches from postoperative day1. Partial weight bearing with 20kg for 6weeks postoperatively. If plain radiographs show unchanged seating of the prosthesis after 6weeks, loading can be increased by 10kg/week until full weight bearing is achieved; thrombosis prophylaxis is continued throughout. Limitation of hip flexion to 90° during the first 6weeks, and no adduction and forced external rotation to avoid dislocation. Avoidance of sports involving jumping and axial impact loading for 12months. Radiologic checkups after 3, 6, and 12months and, thereafter, every 2years. Analysis between 2008 and 2011 involved 22 consecutive patients with a total of 23prostheses; the mean follow-up was 38 ± 11 months. Compared to the preoperative evaluation, follow-up yielded a significant improvement in the average Harris Hip Score (82.2 ± 8.7 vs. 44.7 ± 10.7) and the Merle d'Aubigné Score (14.6 ± 1.9 vs. 7.5 ± 1.3). Radiological solid osseointegration of the cup was observed in 21cases; partial radiolucent lines were seen in 2cases (9 %) in the zones I-III delineated by DeLee and Charnley. In 21cases (91 %) radiographs confirmed no measurable migration or displacement of the acetabular component and the bone graft was determined to be incorporated on the basis of osseous consolidation within the grafted area in 20cases (87 %). During follow-up 3prosthesis (13 %) required revision.

Femoral revision with impaction bone grafting and a cemented polished tapered stem

Biological repair of femoral bone loss using bone impaction grafting. Reconstruction of the centre of rotation of the hip using a cemented stem, the size and offset of which are at the discretion of the surgeon. Femoral implant loosening with bone loss. Infection, neurological disorders, noncompliant patient. Extraction of the loose femoral implant, cortical reconstruction using meshes if required, impaction bone grafting with special instruments, cement fixation of a polished tapered stem. Individualized period of bed rest and limited weight bearing. Impaction bone grafting and a cemented polished stem were used to perform 33femoral reconstructions. After a mean follow-up of 15years, no femoral reconstruction had to be revised. One unrecognized intraoperative fracture healed after nonsurgical treatment, three postoperative femoral fractures healed after plate fixation with the stem left in situ. The average Harris Hip Score improved from 49prior to surgery to 85points thereafter. Kaplan-Meier analysis with femoral revision for any reason as the end point showed a survival rate of 100 %.

The Exeter method—acetabular impaction grafting with cemented reimplantation

Restoration of acetabular anatomy and biomechanics at revision hip surgery by replacing deficient acetabular bone through impaction of allograft and/or autograft bone chips. Aseptic loosening of the socket due to osteolysis, bone loss from infection, iatrogenic bone loss due to implant removal, and in the primary setting protrusio acetabuli, dysplasia and previous acetabular fracture. Large segmental peripheral acetabular defects which cannot be contained, the presence of untreated infection, unstable acetabular fractures, previous radiotherapy to the affected hip area. Sound exposure of the acetabulum with delineation of the bony defect. Creation of a host environment suitable for bone graft and containment of segmental defects using rim mesh or porous augments. Impaction grafting using layered allograft or autograft bone chips of 0.8-1cm(3), packed using hemispherical impactors, followed by cementing of a polyethylene acetabular component with pressurisation. Partial weight bearing 6weeks, modified depending on level of containment and intra-operative findings. A successful and reproducible technique with survival up to 87 % at 20years for aseptic loosening in the revision setting.