Purpose. Anterior column screw fixation has been a useful tool in the management of acetabular fractures, either alone or in combination with other fixation techniques. Percutaneous insertion may be advantageous by limiting surgical dissection but little has been reported on its safety. The purpose of this study is to report on the efficacy and safety of percutaneous anterior column stabilization. Method. In a consecutive series of 122 operatively treated acetabular fractures, 56 patients were treated with antegrade percutaneous anterior column stabilization either alone or in combination with other fixation techniques by a single surgeon (JY). The technique was selected when the anterior column portion of the fracture was undisplaced or could be reduced via indirect methods. Intraoperative fluoroscopy was used to guide the placement of either a 6.5 mm or 7.3 mm cannulated antegrade anterior column lag screw. Postoperative radiographs (anteroposterior and Judet views) were obtained in the recovery room, prior to discharge and at clinic follow up. Results. The mean age of patients in the series was 52 years (range 17 91). Mean follow up was 13 months. There was one death from associated injuries. Based on the classification system described by Letournel, there were 22 anterior column, 8 transverse, 11 transverse / posterior wall, 9 anterior column / posterior hemitransverse, 1 associated both column and 5 T-type fractures. There were no vascular, neurologic, or urologic complications in the series. There were no cases of intraarticular screw placement. In two cases, the screw did not completely cross the entire fracture line on postoperative radiographs. There were no cases of hardware failure or loss of reduction. There were two cases of hardware removal for hardware prominence. There was one case of chronic proximal femur osteomyelitis, and two cases requiring subsequent total hip arthroplasty for associated injuries. All fractures healed. Conclusion. This study supports percutaneous anterior column stabilization as a safe and effective technique in the treatment of selected acetabular fractures

Background. Surgical site infection following spine surgery is associated with increased morbidity, mortality and increased cost for the health care system. The reported pooled incidence is 3%. Perioperative antibiotic prophylaxis is a key factor in lowering the risk of acquiring an infection. Previous studies have assessed perioperative cefuroxime concentrations in the anterior column of the cervical spine with an anterior surgical approach. However, the majority of surgeries are performed in the posterior column and often involve the lumbar spine. Accordingly, the objective was to compare the perioperative tissue concentrations of cefuroxime in the anterior and posterior column of the same lumbar vertebra using microdialysis in an experimental porcine model. Method. The lumbar vertebral column was exposed in 8 female pigs. Microdialysis catheters were placed for sampling in the anterior column (vertebral body) and posterior column (posterior arch) within the same vertebra (L5). Cefuroxime (1.5 g) was administered intravenously over 10 min. Microdialysates and plasma samples were continuously obtained over 8 hours. Cefuroxime concentrations were quantified by Ultra High Performance Liquid Chromatography Tandem Mass Spectrometry. Microdialysis is a catheter-based pharmacokinetic tool, that allows dynamic sampling of unbound and pharmacologic active fraction of drugs e.g., cefuroxime. The primary endpoint was the time with cefuroxime above the clinical breakpoint minimal inhibitory concentration (T>MIC) for Staphylococcus aureus of 4 µg/mL as this has been suggested as the best predictor of efficacy for cefuroxime. The secondary endpoint was tissue penetration (AUC. tissue. /AUC. plasma. ). Results. Mean T>MIC 4 µg/mL (95% confidence interval) was 123 min (105–141) in plasma, 97 min (79–115) in the anterior column and 93 min (75–111) in the posterior column. Tissue penetration (95% confidence interval) was incomplete for both the anterior column 0.48 (0.40–0.56) and posterior column 0.40 (0.33–0.48). Conclusions. Open lumbar spine surgery often involves extensive soft tissue dissection, stripping and retraction of the paraspinal muscles which may impair the local blood flow exposing the lumbar vertebra to postoperative infections. A single intravenous administration of 1.5 g cefuroxime resulted in comparable T>MIC between the anterior and posterior column of the lumbar spine. Mean cefuroxime concentrations decreased below the clinical breakpoint MIC for S. aureus of 4 µg/mL after 123 min (plasma), 97 min (anterior column) and 93 min (posterior column). This is shorter than the duration of most lumbar spine surgeries, and therefore alternative dosing regimens should be considered in posterior open lumbar spine surgeries lasting more than 1.5 hours

Purpose of the study. Percutanous acetabular surgery is a new and developing technique in fixation of acetabulum fractures. The most common screw used is the anterior column screw that traverses anterograde or retrograde through the anterior column of the acetabulum. Standard height and width calculations derived from CT scans do not take the trajectory of the screw into consideration. They have been shown to exaggerate the available safe bone corridor for screw passage. Posterior column screws can be placed in a retrograde fashion via the ischial tuberosity to fixate posterior column. Limited international data is available and no studies to date have been conducted on the South African population. This study assesses the anterior and posterior acetabular columns of South African individuals and ascertains the safe bone corridor sizes. Methods. Pelvic CT-scans of 100 randomly selected patients were reviewed. Specific computer software was used to virtually place anterior screws through the anterior acetabular column, in its clinical trajectory. Specific entry points inferior to the pubic tubercles significantly changed the relation of the screw trajectory to the mid- column isthmus and were incorporated in the measurement of the anterior column. All the available lengths and diameters were measured and averages were calculated for males and females. Results. On average, males have longer and larger diameter anterior columns. The entry point on the pubic tubercle has a significant impact on the relative diameter at the mid- column. Not all commercially available cannulated screw diameters are safe to place into the anterior column. Conclusion. Although the international literature shows that percutaneous anterior column fixation is of value for early mobilisation after fractures, intimate knowledge of the local data regarding the available safe corridors for screw passage is limited. This study shows the safe bone corridors that can be used to avoid breaching the cortex during screw insertion. It also recommends safe screw diameters. NO DISCLOSURES

Introduction. Mode of non-operative management of thoracolumbar spine fracture continues to remain controversial with the most common modality hinging on bracing. TLSO is the device with a relative extension locked position, and many authors suggest they may have a role in the healing process, diminishing the load transferred via the anterior column, limiting segmental motion, and helping in pain control. However, several studies have shown prolonged use of brace may lead to skin breakdown, diminished pulmonary capacity, weakness of paraspinal musculature with no difference in pain and functional outcomes between patients treated with or without brace. Aims. To identify number of spinal braces used for spinal injury and cost implications (in a DGH), to identify the impact on length of stay, to ascertain patient compliance and quality of patient information provided for brace usage, reflect whether we need to change our practice on TLSO brace use. Methods. Data collected over 18-month period (from Jan.2020 to July 2021). Patients were identified from the TLSO brace issue list of the orthotic department, imaging (X-rays, CT, MRI scans) reviewed to confirm fracture and records reviewed to confirm neurology and non-operative management. Patient feedback was obtained via post or telephone consultation. Inclusion criteria- patients with single or multi -level thoracolumbar osteoporotic or traumatic fractures with no neurological involvement treated in a TLSO brace. Exclusion criteria- neurological involvement, cervical spine injuries, decision to treat surgically, concomitant bony injuries. Results. 72 braces were issued in the time frame with 42 patients remaining in the study based on the inclusion/exclusion criteria. Patient feedback reflected that 62% patients did not receive adequate advice for brace usage, 73% came off the brace earlier than advised, and 60% would prefer to be treated without a brace if given a choice. The average increase in length of stay was 3 days awaiting brace fitting and delivery. The average total cost burden on the NHS was £127,500 (lower estimate) due to brace usage. Conclusion. If there is equivalence between treatment with/without a brace, there is a need to rethink the practice of prescribing brace for all non-operatively treated fractures and a case-by-case approach may prove more beneficial

Introduction:. The anterior column of the spine is often destroyed by trauma or disease. It is reconstructed by using autograft, allograft, or synthetic cages. The fibula strut graft provides good strength, incorporates quickly and has less risk of disease transmission, which is a big advantage in communities with high incidence of HIV. Various authors cite that its major drawback is the size of its foot print. We could not find any literature that measures its size. We undertook a study to measure the size of the footprint of the fibular in relation to the surface area of the endplate. The clinical relevance is that it may guide the surgeon in deciding how many struts of fibular are required in reconstructing the anterior column, and also quantifies the statement that the fibular strut has a small footprint. Material and Method:. CT angiograms are done frequently for peripheral vascular diseases. These angiograms also show CT scans of the lumbar and thoracic vertebrae, and fibulae of the same patient. We retrospectively examined the first 35 scans done during the year 2012 at Steve Biko Academic Hospital. From the CT we measured the surface area of the endplate of the vertebral bodies T6, 8, 12, L2, and the surface area of the cut surface of the proximal, middle and distal thirds of the fibular, all in square millimetres. We then compared the areas of the vertebral measurements to the area of the fibular measurements. Results:. The middle third of the fibular had the biggest cross sectional surface area. This fact, together with anatomical features of the fibula, explains why the middle part of the fibular is the preferred graft donor site. The ratio of the fibular surface area to that of the vertebral endplate is 1:3–6. It is difficult to advise in a biological system how many struts are required, as compared to a mechanical system. However these ratios suggest that more than one fibular strut graft is required to reconstruct the anterior column. Conclusion:. This is the first time to our knowledge that the surface area of the fibular graft is quantified against the vertebral end plate surface area. The study shows that at least 2 fibula struts are required to reconstruct the thoracic and lumbar anterior columns

Aim of the study was to define the role of surgical stabilization of the spine in treatment of pyogenic spondylitis/diskitis. We restrospectively analyzed patients referred to our department for treatment of pyogenic infection of axial skeleton. In three years period we treated 51 patients with pyogenic infection of axial skeleton, and 46 of them were surgically stabilized by means of posterior instrumentation with or without anterior column reconstruction. Reoperation rate was 7%, and was in all cases associated with failure in reconstruction of anterior column of the spine. This could be achieved either by posterior or by combined approach, and there was no significant difference in perioperative complications in either group of patients. 14 patients presented with initial neurological deficit, and that presented the indication for urgent surgical procedure. We conclude that surgical stabilization of axial skeleton should be always performed in patients with destruction of bone structure. The procedure allows easy achievement of material for bacteriological culture, and precisely targeted antibiotic treatment, and at the same time results with a stable spine, therefore allowing early rehabilitation of these patients. Though neurological deficit presents the indication for urgent decompression of neural structures, we emphasize the importance of reconstruction of all three columns of the spine in all circumstances

Operative approaches to the acetabulum are generally classified into anterior, posterior, extensile or combined approaches. The choice of approach depends upon the fracture pattern and the amount of relative displacement affecting the anterior and posterior bony structures. Occasionally, extensile or combined surgical approaches are indicated for the treatment of complex fracture patterns with extensive involvement of both the anterior and posterior acetabular anatomy. However, it is believed that these approaches may be associated with higher complication rates than more limited surgical approaches. The ilioinguinal approach described by Letournel is routinely employed in the treatment of anterior column, anterior wall, anterior column/posterior hemi- transverse and certain associated both-columns, transverse and T-type fractures. The utility of this approach is sometimes limited by difficulty in visualising, reducing and applying instrumentation to the quadrilateral plate and posterior column components of these fractures. A surgical approach described by Stoppa in 1989—and later extended to acetabular indications by Cole and Bolhofner—can be used, often in combination with the lateral window of the standard ilioinguinal approach, to effectively treat the same range of fractures as an ilioinguinal approach. Access to the quadrilateral plate and certain displaced posterior column fracture lines is enhanced by this approach—possibly eliminating the need for combined or extensile approaches in certain cases. A retrospective study undertaken at our institution demonstrated that anatomic articular reduction was achieved in 14 of 17 complex acetabular fractures treated via a Stoppa approach. All fractures in the study had at least 5 mm of posterior column displacement preoperatively

Introduction. Acetabular component positioning, offset, combined anteversion, leg length, and soft tissue envelope around the hip plays an important role in hip function and durability. In this paper we will focus on acetabular positioning of the cup. Technique. The axis of the pelvis is identified intra-operatively as a line drawn from the highest point of the iliac crest to the middle of the greater trochanter. Prior to reaming the acetabulum, an undersized trial acetabular component is placed parallel and inside the transverse ligament, inside the anterior column and projecting posterior to the axis of the pelvis. This direction is marked and the subsequent reaming and final component placement is performed in the same direction. The lateral opening is judged based on the 45-degree angle from the tear drop to the lateral margin of the acetabulum on anteroposterior pelvic radiographs. The final anteversion of the cup is adjusted based on increased or decreased lumbar lordosis and combined anteversion. Methods. Anteroposterior pelvic radiographs of 100 consecutive patients undergoing posterior THR between September 2010 and March 2011 with this method were evaluated for cup inclination angle and anteversion using EBRA software. Results. There were no malalignments or dislocations. The mean cup inclination angle and anteversion were 41 ± 5.1 degrees (range 37.1 – 48.4) and 22.1 ± 4.8 degrees (range 16.6 – 29.3), respectively. Conclusion. This is a reproducible method of cup positioning and with proper femoral component position and restoring leg length, offset, combined anteversion, and balance soft tissue around the hip. These factors affect the incidence of dislocation, infection, reduced wear, and durability

Introduction: Acetabular component positioning, offset, combined anteversion, leg length, and soft tissue envelope around the hip plays an important role in hip function and durability. In this paper we will focus on acetabular positioning of the cup. Technique: The axis of the pelvis is identified intra-operatively as a line drawn from the highest point of the iliac crest to the middle of the greater trochanter. Prior to reaming the acetabulum, an undersized trial acetabular component is placed parallel and inside the transverse ligament, inside the anterior column and projecting posterior to the axis of the pelvis. This direction is marked and the subsequent reaming and final component placement is performed in the same direction. The lateral opening is judged based on 45-degree angle from the tear drop to the lateral margin of the acetabulum on anteroposterior pelvic radiographs. The final anteversion of the cup is adjusted based on increase or decrease of lumbar lordosis and combined anteversion. Methods: Anteroposterior pelvic radiographs of 100 consecutive patients undergoing posterior THR between September 2010 and March 2011 with this method were evaluated for cup inclination angle and anteversion using EBRA software. Results: There were no malalignment or dislocation. The mean cup inclination angle and anteversion were 41 ± 5.1 degrees (range 37.1 – 48.4) and 22.1 ± 4.8 degrees (range 16.6 – 29.3), respectively. Conclusion: This is a reproducible method of cup positioning and with proper femoral component position, restores leg length, offset, combined anteversion, and balances soft tissue around the hip. These factors affect the incidence of dislocation, infection, reduced wear, and durability

Stoppa approach has recently been adapted for pelvic surgery as it allows direct intra-pelvic reduction and fixation of the quadrilateral plate and anterior column. We report our early experience, indications and complications with this exposure introduced in 2010 in our tertiary unit. A Retrospective review of all Stoppa approaches in pelvic-acetabular fixations was performed from a prospectively maintained database. Of the 25 patients, mean age 40 years (range 15–76), who underwent pelvic-acetabular fixation using Stoppa approach, 21 patients had mean follow up of 7.3 months (1–48 months). All except 24% of patients had one or more additional systemic injury some requiring additional surgery. There were 6 acetabular fractures, 13 pelvic ring injuries and 6 combined fractures. Mean injury-surgery interval was 9 days (range 3–20). 8 patients had an isolated Stoppa approach whilst the remaining others also had an additional approach. Mean surgical time was 239 minutes. Anatomical reduction was achieved in 96% (24/25) cases. There was 1 minor intra-operative vascular injury, repaired immediately successfully, and no late wound infections, or other visceral complications. One patient reported new onset sensory numbness which resolved after the first review. Two patients reported erectile dysfunction thought to be caused by the initial injury. One patient had asymptomatic plate loosening. None required revision surgery. Despite the obvious learning curve, we found this approach safe and it did not compromise accuracy of reduction in well selected patients, but early surgery within 10–14 days is recommended to aid optimal reduction

Acetabular fractures are amongst the most complex fractures. It has been suggested that pre-contouring the fixation plates may save intra-operative time, blood loss, reduce intra-operative fluoroscopy and improve the reduction. The purpose of this study was to assess if the contouring could be done reliably using the mirror image of the uninjured hemipelvis. Using the CT data of 12 specimens with no bony abnormality 3D models were reconstructed. Using computer software (AMIRA, Visage Imaging) the mirror image of the left hemipelvis and the right hemipelvis were superimposed based on landmarks. The distances between the surfaces were then calculated and displayed in the form of colour maps. The colour maps demonstrated that for the areas around were acetabular fixation plates would be placed the differences were small. For the anterior column plate 50% of the specimens had differences of less than 1mm, which based on the work of Letournel and Judet would represent an anatomical reduction. For the posterior column plate 58% had differences of less than 1mm. This study demonstrates that there is considerable symmetry between both hemipelvises and that precontouring on the mirror image of the uninjured side is an accurate, quick and reliable method for precontouring

Acetabular fractures are amongst the most complex fractures to treat. It has been suggested that pre-contouring the fixation plates may save intra-operative time, blood loss, reduce intra-operative fluoroscopy and improve the reduction. The purpose of this study was to assess if the contouring could be done reliably using the mirror image of the uninjured hemipelvis. Using the CT data of 12 specimens with no bony abnormality 3D models were reconstructed. Using computer software (AMIRA, Visage Imaging) the mirror image of the left hemipelvis and the right hemipelvis were superimposed based on landmarks. The distances between the surfaces were then calculated. The results were collected in the form of mean distance and colour maps. The mean difference between surfaces ranged from 1.76mm and 8.47mm. The colour maps demonstrated that for the areas around were acetabular fixation plated would be placed the differences were small. For the anterior column plate 6 (50%) of the specimens had differences of less than 1mm, which based on the work of Letournel and Judet would represent an anatomical reduction. (None had a difference of more than 6mm.) For the posterior column plate 7 (58%) had differences of less than 1mm. (None had a difference of more than 3mm. This study demonstrates that there is considerable symmetry between both hemipelvises and that precontouring on the mirror image of the uninjured side is an accurate, quick and reliable method for precontouring. However the symmetry is not exact and the operating surgeon needs to be aware that fine-contouring may be required intra-operatively

Certain acetabular fractures involve impaction of the weight-bearing dome and medialisation of the femoral head. Intra-operative fracture reduction is made easier by traction on the limb, ideally in line with the femoral neck (lateral traction). However, holding this lateral traction throughout surgery is very difficult for a tiring assistant. We detail a previously undescribed technique of providing intra-operative lateral femoral head traction via a pelvic reduction frame, to aid fixation of difficult acetabular fractures. The first 10 consecutive cases are reviewed (Group 1) and compared with a retrospective control (Group 2, n=18) of case-matched patients, treated prior to introducing the technique. The post-operative X-rays and CT scans were assessed to identify quality of fracture reduction according to the criteria of Tornetta and Matta. Operative time, blood loss and early complication rates were also compared. All cases in both groups were acute injuries with medial and/or superior migration of the femoral head. The majority were either associated both column or anterior column posterior hemi-transverse. There was no statistical difference between the groups in age, time to surgery, BMI or ASA grade. Fracture reduction was assessed as excellent in seven, good in three and poor in one. This was not significantly different from the control group (p=0.093). The mean operative time was 232 minutes in Group 1 and 332.78 minutes in Group 2 (p = 0.0015). There was no difference between the groups for blood loss or complication rates. We conclude that this new technique is at least equivalent to using manual traction and early results suggest it reduces operative time and technical difficulty in treating these complex acetabular fractures

Introduction. The incidence of acetabular fractures in the elderly population is increasing. Treatment with staged or acute total hip arthroplasty (THA) is occasionally required. The role of acute THA however, remains controversial. The purpose of our study was to assess the outcomes of a subgroup of elderly patients who underwent early simultaneous open reduction and internal fixation (ORIF) and primary THA for displaced acetabular fractures. Materials and Methods. 86 patients underwent ORIF for displaced acetabular fractures at The Alfred Hospital, Melbourne between August 2007 and August 2009. Eight of these patients underwent early simultaneous ORIF and primary THA. Mean age was 79 years. Mean time between injury and surgery was 4 days. Mean time of follow-up was 19 months. There were 3 both-column fractures, 2 anterior column, 1 posterior wall, 1 transverse with posterior wall and 1 T-shaped. Two patients had an associated neck of femur fracture and two had an impaction fracture of the femoral head. The Harris and Oxford hip scores were used to assess clinical outcome. Radiographs were analysed for component loosening. Results. There was one unrelated post-operative death at 5 months. There was a high rate of post-operative complications. Four patients developed heterotopic ossification, 2 extensive. There was one superficial and one deep infection. One patient has a persistent post-operative foot drop. The Harris hip scores ranged from 45 to 86 with a mean of 68. The Oxford hip scores ranged from 24 to 37 with a mean of 32. There was no evidence of acetabular component loosening. Conclusion. Acute THA for displaced acetabular fractures in the elderly is associated with significant post-operative complications and relatively poor clinical outcomes. However, we believe there may be an indication for this treatment when there is an associated ipsilateral fracture of the femoral neck or femoral head

Percutaneous cannulated screw placement (PCSP) is a common method of fixation. In pelvic trauma neurovascular structures are in close proximity to the screw path. Pre-operative planning is needed to prevent injury. This study aims to the safety margin and accuracy of screw placement with computer navigation (CAS). A control had no pathology in the pelvis but CT scans were performed for suspected trauma. The treated group had pelvic and acetabular fractures and were treated with CAS PCSP at our institution. Using a new technique involving CT 3D modelling of the whole (3D) safe corridor, the dimensions of the Posterior elements (PE) of the pelvic ring and the anterior column of the acetabulum (AC) were measured in the control group. The accuracy of screw placement (deviation between the actual screw and planned screw) was measured in treated patient using a screenshot method and post-operative CTs. There were 22 control patients and 30 treated patients (40 screws). The mean ± (standard deviation, SD) minimum measurement of the safe corridor at the PE was 15.6 ± 2.3 mm (range 11.6 mm to 20.2 mm) and at the AC was 5.9 ±1.6 mm (range 3.0 mm to 10.0 mm). The mean ± (SD) accuracy of screw placement was 6.1 ± 5.3 mm and ranged from a displacement of 1.3 mm to 16.1 mm. There was a notable correlation between Body Mass Index, duration of surgery and inaccuracy of screw placement in some patients. The largest inaccuracy of screw placement was due to reduction of the fracture during screw insertion, causing movement of the bone fragments relative to the array and therefore also the computerised screw plan. There were no screw breakages, non-unions, neurological or vascular complications. CAS PCSP is a safe and accurate technique. However, the safe corridor is variable and often very narrow. We recommend that the dimensions of the safe corridor be assessed pre-operatively in every patient using 3D modelling to determine the number and size of screw that can be safely placed

Introduction. Loss of bone stock is a technically challenging problem in revision total hip arthroplasty (RevisionTHA). Impaction bone grafting (IBG) is an attractive biological method of reconstruction. We performed acetabular revisions using IBG and cemented cup in patients with failed hip prosthesis and large defects. The purpose is to report the short term results of revision THA with using IBG. Patients & Methods. We retrospectively reviewed 19 patients/19 hips revised for aseptic loosening of a cemented or uncemented cup, three male/16 female, mean 65.5 ± 8.8 years old (43–75). Mean follow up time is 18 months. Classification of acetabular defects according to A.A.O.S classification were Type I; 5 hips, Type III; 13 hips and Type V; 1 hip. Before impacting the morselized bone allograft and cement, segmental acetabular defects were reconstructed with metallic meshes screwed to the bone bed. Morselized allograft bone chips (diameter 7ï¼ 10 mm) were impacted forcefully. All-polyethylene cups (Stryker, Crossfire) were cemented. Clinical examination was performed using Japanese Orthopaedic Association (JOA) score. Radiographic examination was performed using AP radiographs. We measured the inclination cup angle, the distance of superior migration, the presence of loosening of the implanted cup, 4 weeks postoperatively and at the last follow up. Loosening was defined as migration distance was more than 5 mm in any direction. Results. Clinical JOA score improved from 61.0±3.9 to 83.6±2.7 at the last follow up. Complication in this study included one sciatic nerve palsy and one dislocation. In the radiographical analysis, inclination angle changed 41.8 ±2.2° at 4 weeks postoperatively to 42.3±1.8° at the last follow up. The average superior migration was 1.65±0.62 mm (0–9.00), and one loosening case (9.0 mm) was founded. In the loosening case, preoperative radiograph showed the shell had penetrated into the acetabulum. The case had extensive bone defect (4 cm×4 cm) including the medial wall and anterior column. Summary. The short term result of revision THA with using IBG was reported and most cases showed excellent clinical and radiographic results. But one loosening case was founded. The limitation of IBG may be associated with the lacked bony support behind the graft

Introduction:. Acetabular revision Jumbo cups are used in revision hip surgeries to allow for large bone to implant contact and stability. However, jumbo cups may also result in hip center elevation and instability. They may also protrude through anterior wall leading to ilopsoas tendinitis. Methods:. The study was conducted using two methods:. Computer simulation study. 265 pelvic CT scans consisting of 158 males and 107 females were converted to virtual 3-dimensional bones. The average native acetabular diameter was 52.0 mm, SD = 4.0 mm (males in 52.4 mm, SD = 2.8 mm and 46.4 mm, SD = 2.6 mm in females). Images were analyzed by custom CT analytical software (SOMA™ V.3.2). 1. and over-sized reaming was simulated. Four distinct points, located in and around the acetabular margins, were used to determine the reamer sphere. Points 1, 2, 3 were located at the inferior and inferior-medial acetabular margins, and Point 4 was located superiorly and posteriorly in the acetabulum to simulate a bony defect in this location, Point 4 was placed at 10%, 20%, 30%, 40%, 50% and 60% of the distance from the superior – posterior margin of the acetabular rim to the sciatic notch to simulate bony defects of increasing size. (Figure 1). Radiographical study. Retrospective chart review of patient records for all cementless acetabular revisions utilizing jumbo cups between January 1, 1998 and March 30, 2012 at UCFS (98 patients with 57 men, 41 women). Jumbo cups: ≥66 mm in males; <62 mm in females. Reaming was directed inferiorly to the level of the obturator foramen to place the inferior edge of the jumbo cup at the inferior acetabulum. To determine the vertical position of the hip center, a circle was first made around both the jumbo and the contralateral acetabular surfaces using Phillips iSite PACS software. The center of this circle was assumed to correspond to the “hip center”. The height of the hip center was estimated by measuring the height of a perpendicular line arising from the interteardrop line (TL) and ending at the hip center. Results:. The computer simulation and radiographic analysis deomonstrated similar results. The computer simulation predicted that the hip center shifted superiorly and anteriorly as the reamer size increased. The hip center shifted 0.27 mm superiorly and 0.02 mm anteriorly for every millimeter in diameter increased for the reaming. (Figure 2) Anterior column bone removal was increased 0.86 mm for every 1 mm of reamer size increase. (Figure 3). Results of radiographical study is shown in Table bellow:. Discussion:. Use of a jumbo cup in revision THA results in elevation of the hip center. Therefore a longer femoral head may be needed to compensate for hip center elevation when a jumbo cup is used. Reaming for a jumbo cup can also result in loss of anterior bone stock and protrusion of the cup anteriorly which may cause iliopsoas tendonitis

The number of joint revision surgeries is rising, and the complexity of the cases is increasing. In 58% of the revision cases, the acetabular component has to be revised. For these indications, literature decision schemes [Paprosky 2005] point at custom pre-shaped implants. Any standard device would prove either unfeasible during surgery or inadequate in the short term. Studies show that custom-made triflanged implants can be a durable solution with good clinical results. However, the number of cases reported is few confirming that the device is not in widespread use. Case Report. A patient, female 50 yrs old, diagnosed having a pseudotumor after Resurfacing Arthroplasty for osteo-arthritis of the left hip joint. The revision also failed after 1 y and she developed a pelvic discontinuity. X-ray and Ct scans were taken and sent to a specialized implant manufacturer [Mobelife, Leuven, Belgium]. The novel process of patient-specific implant design comprises three highly automated steps. In the first step, advanced 3D image processing presented the bony structures and implant components. Analysis showed that anterior column was missing, while the posterior column was degraded and fractured. The acetabular defect was diagnosed being Paprosky 3B. The former acetabular component migrated in posterolateral direction resulting in luxation of the joint. The reconstruction proposal showed the missing bone stock and anatomical joint location. In the second step, a triflanged custom acetabular metal backing implant was proposed. The bone defect (35ml) is filled with a patient-specific porous structure which is rigidly connected to a solid patient-specific plate. The proposed implant shape is determined taking into account surgical window and surrounding soft tissues. Cup orientation is anatomically analyzed for inclination and anteversion. A cemented liner fixation was preferred (Biomet Advantage 48mm). Screw positions and lengths are pre-operatively planned depending on bone quality, and transferred into surgery using jig guiding technology (Materialise NV, Leuven, Belgium). In the third step, the implant design was evaluated in a fully patient-specific manner in dedicated engineering (FEA) software. Using the novel automated CT-based methodology, patient-specific bone quality and thickness, as well as individualised muscle attachments and muscle and joint forces were included in the evaluation. Implants and jig were produced with Additive Manufacturing techniques under ISO 13485 certification, using respectively Selective Laser Melting (SLM) techniques [Kruth 2005] in medical grade Ti6Al4V material, and the Selective Laser Sintering technique using medical grade epoxy monomer. The parts were cleaned ultrasonically, and quality control was performed by optical scanning [Atos2 scanning device, GOM Intl. AG, Wilden, Switzerland]. Sterilization is performed in the hospital. CONCLUSION. A unique combination of advanced 3D planning, patient-specific designed and evaluated implants and drill guides is presented. This paper illustrates, by means of a clinical case, the novel tools and devices that are able to turn reconstruction of complex acetabular deficiencies into a reliable procedure

INTRODUCTION:. Recent trends in total hip arthroplasty (THA) have resulted in the use of larger acetabular components to achieve larger femoral head sizes to reduce dislocation, and improve range of motion and stability. Such practices can result in significant acetabular bone loss at the time of index THA, increasing risk of anterior/posterior wall compromise, reducing component coverage, component fixation, ingrowth surface and bone stock for future revision surgery. We report here on the effects of increasing acetabular reaming on component coverage and bone loss in a radiographic CT scan based computer model system. METHODS:. A total of 74 normal cadaveric pelves with nonarthritic hip joints underwent thin slice CT scan followed by upload of these scans into the FDA approved radiographic analysis software. Utilizing this software package, baseline three-dimensional calculations of femoral head size and acetabular size were obtained. The software was used to produce a CT scan based model that would simulate reaming and placement of acetabular components in these pelves that were 125, 133 and 150% the size of the native femoral head. Calculations were made of cross sectional area bone loss from anterior/posterior columns, and loss of component coverage with increasing size. RESULTS:. Use of acetabular components that were 125, 133 and 150% the size of the native femoral head led to a average loss of 23, 27% and 33% loss of cross-sectional acetabular bone and an average 7, 16 and 27% loss of acetabular component coverage. CONCLUSION:. The CT scan/computer based model described here demonstrates that acetabular preparation and use of large components simply to gain larger femoral head size can result in significant bone loss and reduced component coverage. Operating hip surgeons attempting to utilize such large components must take great caution when attempting to maximize acetabular component size