Acetabulum fractures caused by civilian firearms represent a unique challenge for orthopaedic surgeons. Treatment strategies should include the assessment of infection risk due to frequently associated abdominal injuries and maintenance of joint function. Still, internationally accepted treatment algorithms are not available. The aim of the study was to increase knowledge about civilian gunshot fractures of the acetabulum by describing their characteristics and management at a high-volume tertiary hospital. All adult patients admitted to our hospital between January 2009 and December 2022 with civilian gunshot fractures of the acetabulum were included in this descriptive retrospective study. In total our institution treated 301 patients with civilian gunshot fractures of the hip joint and pelvis during the observation period, of which 54 involved the acetabulum. Most patients were young males (88,9%) with a mean age of 29 years. Thirty patients (55,6%) had associated intraabdominal or urological injuries. Fracture patterns were mostly stable fractures with minor joint destruction amenable to conservative fracture treatment (n=48, 88,9%). Orthopaedic surgical interventions were performed in 21 patients (38,9%) with removal of bullets in contact with the hip joint via arthrotomy or surgical hip dislocation as most frequent procedures. Most patients received antibiotics on admission (n=49, 90,7%). Fracture related infections of the acetabulum were noted in six patients (11,1%) while the mortality in the study population was low with one demised patient (1,9%) due to the trauma burden. Most civilian acetabulum gunshot fractures are associated with intraabdominal or urological injuries. In comparison to the literature on extremity gunshot fractures, there is an increased risk of infection in our study population. The decision for surgical wash-out and bullet removal should be based on contamination and anticipated joint destruction, while osteosynthesis or primary arthroplasty are rarely necessary for these injuries

Introduction. The success of total hip replacement (THR) is closely linked to the positioning of the acetabular component. Malalignment increases rates of dislocation, impingement, acetabular migration, pelvic osteolysis, leg length discrepancy and polyethylene wear. Many surgeons orientate the cup to inherent anatomy of the acetabulum. Detailed understanding of the anatomy and orientation of the acetabulum in arthritic hips is therefore very important. The aim of this study was to describe the anteversion and inclination of the inherent acetabulum in arthritic hips and to identify the number that fall out with the ‘safe zone’ of acetabular position described by Lewinnek et al. (anteversion 15°±10°; inclination 40°±10°). Materials and Methods. A series of 65 hips all with symptomatic osteoarthritis undergoing THR were investigated. Patients with dysplastic hips were excluded. All patients had a navigated THR as part of their normal clinical treatment. A commercially available non image based computer navigation system (Orthopilot BBraun Aesculap, Tuttlingen, Germany) was used. Anterior pelvic plane was registered using the two anterior superior iliac spines and pubic symphysis. Inner size of the empty acetabulum was sized with cup trials and appropriately size trial fixed with a computer tracker was then aligned in the orientation of the natural acetabulum as defined by the acetabular rim ignoring any osteophytes. The inclination and anteversion were calculated by the software. The acetabular inclination in all hips was also measured on pre-operative anteroposterior pelvic digital radiographs. Acetabular inclination was measured using as the angle between a line passing through the superior and inferior rim of the acetabulum and a line parallel to the pelvis as identified by the tear drops, using the method described by Atkinson et al. Results. All patients were Caucasian and had primary osteoarthritis. There were 29 males and 36 females. The average age was 68 years (SD 8). The inclination was 50.4(SD 7.4) and 58.8(SD 5.7) on navigation and radiographs respectively. The anteversion was 9.3(SD 10.3) on navigation. Anteversion for males was significantly lower than females with a mean difference of −5.5° (95% CI −10.5°, −0.5°) with a p value of 0.033. There was no significant difference with respect to inclination. Overall 69% of patients had a combined inclination and anteversion of the native acetabulum that fell outside the “safe zone” of Lewinnek. Conclusions. Inherent acetabular orientation in arthritic hips falls out with the safe zone defined by Lewinnek in 69% of cases. When using the natural acetabular orientation as a guide for positioning implants it should therefore not be assumed this will fall with in the safe zone although the validity of safe zones itself is questionable. Variation between patients must be taken into account. The difference between males and females, particularly in terms of anteversion, should also be considered

Background. CT-based navigation system in total hip arthroplasty(THA) is widely used to achieve accurate implant placement. The purpose of this study was to evaluate the influence of initial error correction according to the differences in the shape of the acetabulum, and correction accuracy associated with operation approach after localization of registration points at anterior or posterior area of the acetabulum. Methods. We set the anterior pelvic plane(APP) as the reference plane, and defined the coordinates as follows: X-axis for external direction, Y-axis for anterior direction, and Z-axis for proximal direction. APP is defined by the anterior superior iliac spines and anterior border of the pubic symphysis. We made a bone model of bilateral acetabular dysplasia of the hip, after rotational acetabulum osteotomy(RAO) on one side, and performed registration using infrared-reflective markers. At first, we registered the initial error on navigation system, and calculated the accuracy of the error correction based on each shape of the acetabulum as we increased the surface matching points. Based on the actual operation approach, we also examined the accuracy of the error correction when concentrating the matching points in anterior or posterior areas of the acetabulum. Results. For the rotational acetabular osteotomy model, the range of possible initial error correction increased as the surface matching points increased on both X-axis and Y-axis: On the X-axis, the range increased from 6mm to 10mm as the surface matching point increased from 10 to 20; and on the Y-axis, the range increased from 2mm to 10mm as the point increased 10 to 50. The range did not increase on the Z-axis. For the acetabular dysplasia model, the range of possible initial error correction increased on the X-axis(the range increased from 2mm to 8mm as the point increased from 10 to 50); however, no increase was observed for the Y- and Z-axis. Furthermore, concentrating the surface matching points in the posterior area around the acetabulum was more effective for the correction of the initial rotational error. Discussion. Because of the different anatomical shapes of the acetabulum, the error directions that were difficult to correct tended to vary between dysplasia and post-RAO. The error correction of Z-axis was difficult on both shapes of the acetabulum. Thus, the careful initial setting on Z-axis is important to minimize the error. Surface matching point on the posterior part of the acetabulum is more effective in correcting the initial rotational error compared with the anterior part of the acetabulum. It was shown that the difference in the error correction was affected by the localization of the registration points around the acetabulum. We presumed that using surface matching points on posterior area of the acetabulum improves the accuracy of the CT-based navigation system on the anterior approach. When using the system, it is important to understand the tendency that the shape of the acetabulum and the localization of the surface matching points have influence on correction of the initial error

The success of total hip replacement (THR) is closely linked to the positioning of the acetabular component. Malalignment increases rates of dislocation, impingement, acetabular migration, pelvic osteolysis, leg length discrepancy and polyethylene wear. Many surgeons orientate the cup in the same anteversion and inclination as the inherent anatomy of the acetabulum. The transverse acetabular ligament and acetabular rim can be used as a reference points for orientating the cup this way. Low rates of dislocation have been reported using this technique. Detailed understanding of the anatomy and orientation of the acetabulum in arthritic hips is therefore very important. The aim of this study was to describe the anteversion and inclination of the inherent acetabulum in arthritic hips and to identify the number that fall out with the ‘safe zone’ of acetabular position described by Lewinnek et al. (anteversion 15°±10°; inclination 40°±10°). A series of 65 hips, all with symptomatic osteoarthritis undergoing THR were investigated. Patients with developmental dysplastia of hip (DDH) were excluded. All patients had a navigated THR as part of their normal clinical treatment. A posterior approach to the hip was used. A commercially available non image based computer navigation system (Orthopilot BBraun Aesculap, Tuttlingen, Germany) was used. Rigid bodies (using active trackers) were attached to pelvis and femur. Anterior pelvic plane was registered using the two anterior superior iliac spines and pubic symphysis. The femoral head dislocated and removed and the labrum and soft tissue were excised to clear floor and rim of the acetabulum. Inner size of the empty acetabulum was sized with cup trials and appropriately size trial fixed with a computer tracker was then aligned in the orientation of the natural acetabulum as defined by the acetabular rim ignoring any osteophytes. The inclination and anteversion were calculated by the software. Surgery then proceeded with guidance of the computer navigation system. The computer software defines the anatomical values of orientation, to allow comparison with radiographs these were converted to radiological values as described by Murray et al. The acetabular inclination in all hips was also measured on pre-operative anteroposterior pelvic radiographs. This was done using digital radiographs analysed with the PACS system (Kodak, Carestream PACS Client, version 10.0). Acetabular inclination was measured using as the angle between a line passing through the superior and inferior rim of the acetabulum and a line parallel to the pelvis as identified by the tear drops, using the method described by Atkinson et al. All patients were Caucasian and had primary osteoarthritis. There were 29 males and 36 females. The average age was 68 years (SD 8). Mean anteversion was 9.3° (SD 10.3°). Anteversion for males was significantly lower than females with a mean difference of −5.5° (95%CI −10.5°,−0.5°) p = 0.033 but there was no significant difference in the number falling outside the “safe zone”. Mean inclination was 50.4° (SD 7.4°). There was no significant difference between males and females with respect to inclination angle or the number that fell outside the “safe zone”. Overall 69% of patients had a combined inclination and anteversion of the native acetabulum that fell outside the “safe zone” of Lewinnek. Mean acetabular inclination falls out with the ‘safe zone’. This trend has been seen in a recent study of arthritic hips using CT scans which found that the average angle of inclination in both males and females was greater than the upper limit of the safe zone. This study using CT also demonstrated a statistically significant 5.5° difference between males and females in terms of anteversion. This is the same as the figure we have found in our work. Inherent acetabular orientation in arthritic hips falls out with the safe zone defined by Lewinnek in 69% of cases. When using the natural acetabular orientation as a guide for positioning implants it should therefore not be assumed this will fall with in the safe zone although the validity of safe zones itself is questionable. Variation between patients must be taken into account and the difference between males and females, particularly in terms of anteversion, should also be considered

Introduction. Success of total hip replacement (THR) is closely linked to positioning of the acetabular component. Malalignment increases complication rates. Our aim was to describe the anteversion and inclination of the inherent acetabulum in arthritic hips and identify the number that fall out with the ‘safe zone’ of acetabular position described by Lewinnek et al. (anteversion 15±10 degrees; inclination 40±10 degrees). Materials/Methods. A series of 65 hips undergoing non-image based computer navigated THR for Osteoarthritis were investigated. Anteversion and inclination was measured with the help of cup trials fixed with computer trackers aligned in orientation of the natural acetabulum. The acetabular inclination in all hips was measured on pre-operative digital radiographs. Results. There were 29 males and 36 females with average age of 68 years. Anteversion of males was significantly lower than females with a mean difference of −5.5 degrees (95% CI-10.5–0.5 degrees) with p value of 0.033. There was no significant difference with respect to inclination. Overall 69 % of patients had a combined inclination and anteversion that fell outside the ‘safe zone’. Conclusion. Mean acetabular inclination falls outwith the ‘safe zone’ but mean anteversion falls within. The inherent acetabular anatomy of arthritic hips varies widely. Females have significantly more anteversion. Care should be taken when using inherent anatomy of acetabulum as a guide when doing a THR

Fracture of the acetabulum can lead to degenerative arthritis of the hip, avascular necrosis of the femoral head, or both. Total hip arthroplasty is a common form of surgical treatment when significant joint changes and pain are present. Ten patients with fracture acetabulum were treated in this study using metal on metal total hip arthoplasty. The initial fracture was posterior wall fracture in one patient, posterior column fracture in one patient, transverse fracture in 2 patients, fracture dislocation in 3 patients and fracture posterior wall and column in 3 patients. The indications of arthroplasty were secondry osteoarthritis after internal fixation or after conservative management or collapse of the femoral head. Arthroplasty was done after an average period of 1.8 years (range from 1 to 4 years). After a follow up period ranged from 3 to 7 years with a mean of 4.6 years, the Harris hip score was improved from a mean of 51 (range 20 to 65) to a mean of 92.5 (range 90 to 95). Infection occurred in one case and two stages revision was done. Another case developed loosening of the acetabular component and was revised using cementless cup fixed with screws and bone graft. Metal on metal THR after acetabular fracture are relatively uncomplicated and lead to a good outcome despite the difficulties faced during the procedure

Introduction. Acetabular bone deficiency, especially proximal and lateral deficiency, is a difficult technical problem during primary total hip arthroplasty (THA) in developmental hip dysplasia (DDH). We report a configuration-based classification of hip, including a definition of shallow acetabulum. We also report a new reconstruction method using a medial reduced cemented socket and additional bulk bone in conjunction with impaction morselized bone grafting (Ad-BBG method). We aimed to evaluate usefulness of the classification and the method's clinical/radiographic outcomes. Methods. Forty percent of 330 THAs for DDH were defined as shallow dysplastic hips. The Ad-BBG method was performed on 102 hips (78% of shallow hips). For the 24 remaining hips, THA was performed using the conventional interposition bulk bone grafting (8 hips)or without bone grafting by using rigid lateral osteophyte (16 hips). Operative Technique: Theresected femoral head was sectioned at 1–2-cm thickness, and a suitable size of the bulk bone graft was placed on the lateral iliac cortex and fixed by polylactate absorbable screws. Autogenous impaction morselized bone grafting, with or without hydroxyapatite granules, was performed along with the implantation of medial reduced cemented socket. Radiographic criteria used for determining loosening were migration or a total radiolucent zone between the prosthesis/bone cement and host bone. The follow-up period was 10.2 ± 2.6 (range, 6.0–15.0) years. Results. Acetabular component was revised in only one case with a shallow and Crowe Type IV acetabulum. Within 2 years postoperatively, most Ad-BBGs cases showed successful bone remodeling and bone graft reorientation without collapse on radiographs. Discussion and Conclusions. Osteointegration and mid-term good clinical outcomes were achieved in acetabular reconstruction for primary THA using the medial reduced cemented socket and bone grafting methods including the Ad-BBG technique in conjunction with impaction morselized bone grafting for shallow dysplastic hip

Objective. The optimal positioning of the acetabular component is a relevant prognostic factor in total hip arthroplasty (THA). Because of substantial errors of manual technique in cup placement even with experienced surgeon, computer aided navigation system has been developed in recent years. However, existence of the hardware around acetabulum likely deteriorates the accuracy of the navigation system, namely in revision THA case and postoperative status of pelvic fracture. Here we report a case who we successfully performed THA using CT based navigation system although there were multiple hardware around acetabulum due to osteosynthesis for the previous pelvic fracture. Case presentation. A forty-one years old man presented with intolerable hip pain with severe radiographic osteoarthritic findings in left hip joint. He had sustained left pelvic fracture and posterior hip dislocation due to traffic accident and undergone osteosynthesis using multiple plates and screws when he was forty years old. However, progressive collapsing of femoral head and acetabulum occurred. Then, we indicated THA for his situation and planned to apply the CT based navigation system (Stryker CT based hip Ver.1.1 softwear and Cart II system). Preoperative workup revealed incomplete union of posterior and superior acetabular wall and we had to retain plates and screws for the stable fixation of acetabular cup. The existence of the hardware made it complicated to perform three dimensional planning and templating. Meticulous surface editing of pelvis to exclude the metal artifact and fibrocartilagenous tissue was needed to achieve accurate surface registration. In the operation room, we had to use unusual way of registration to complete two steps of registration. In the first step (roughly matching between patient's physical pelvic surface and edited pelvic surface in work station using corresponding 5 points), we utilized head of screw and hole of the plate which we could easily identify intraoperatively, in addition to ASIS and innominate groove. In the second step (strict matching using more than 30 points of pelvic surface), we had to identify the pelvic bony surface, as excluding the metal surface and fibrocartilagenous tissue such as fracture callus. These efforts enabled us to accomplish substantial accuracy of registration with RMS of 0.5 mm. Final cup orientation at the end of surgery was 41° of inclination and 25° of anteversion. Postoperative CT scan revealed that cup placement angle was 40° of inclination and 25° of anteversion, almost identical with intraoperative value. Conclusion. Our experience showed that CT based navigation system provided accurate placement of the acetabular component in a case having multiple hardware as well as in normal primary THA. Although we need additional efforts such as meticulous preoperative planning, extra operation time, CT based navigation system has great advantages to minimize the mal-placement of the cup in complicated case

Mal-positioning of the acetabular component is associated with increased dislocation rate, increased wear and component impingement. Navigation provides real time feedback to the surgeon and allows the accurate position of implants. Compared to conventional techniques of total hip replacement; use of the imageless navigation system has shown to improve accuracy of implant positioning. When impacting uncemented acetabular components under navigation, there is often a deviation from the planned abduction and anteversion measurement due to deflection of the implant in the reamed cavity. Although there exists the ability to navigate the reaming of the acetabular cavity; this is not widely performed. The ability to ream the acetabular cavity in the exact orientation of the planned acetabular component may provide some theoretical advantage on the final acetabular position. The purpose of this study was to compare the effect of navigated Vs free hand acetabulum reaming on achieving the planned orientation of acetabular component. In a retrospective study we reviewed two groups of patients who underwent computer navigated placement of the acetabular component with reference to the anterior pelvic plane. We used an imageless computer navigation system for all cases (Brainlab, Munich). All procedures were performed by single surgeon (ETD) through a standard posterior approach. The patients were divided into two groups depending on the availability of the navigated reamer. In the first group (n = 57), acetabulum reaming was done under navigation and in the second group (n = 37) a non-navigated reamer was used. The acetabular cavity was reamed “line to line” or under reamed by 1 or 2mm. Intra-operative acetabular abduction and anteversion angles were planned using navigation at the discretion of the surgeon. Results of planned acetabular abduction and anteversion angles were compared with intra-operative verification using the navigation system. In the navigated reamer group, the mean error from the planned to verified abduction angle was 1.7 degrees (SD 2.1 degrees) and in the non-navigated reamer group the mean error was 2 degrees (SD 2.6 degrees). In the navigated reamer group, the mean error from the planned to verified anteversion angle was 0.5 degrees (SD 2.8), and in the non-navigated reamer group the mean error was 0.1 degrees (SD 1.6). There was no statistically significant difference in the mean error between the navigated and non-navigated reaming groups for abduction angle (p = 0.54) or anteversion angle (p = 0.24). There was no statistical difference between the mean acetabular component size in the navigated (mean 53mm) and non-navigated (53mm) reamer groups (p = 0.8). There was no statistical difference in the mean difference in reamer size and the acetabular component size in the navigated (0.8mm) and non-navigated reamer groups (0.8mm, p = 0.52). This study appears to show that performing reaming of the acetabular cavity under navigation does not improve the final orientation of the acetabular component when compared to using conventional non-navigated reamers. However, this study only considered the abduction and anteversion orientation of the component. The move to a range of movement or kinematic orientation of the acetabular component in hip arthroplasty requires control over the off-set of the acetabular component which may be more easily achieved when the reaming is performed under navigation. This study used a conventional posterior approach rather than a minimal incision technique, where the use of navigated reaming may also provide some theoretical advantage when visibility is limited. Further study is required in these two areas. There appears to be a slightly higher standard deviation for the anteversion measurement in the navigated reamer group when compared to the non navigated reamer group, although this is not significant. It is difficult to account for this as it appears to be opposite of what one would predict. One explanation for this may come in the difference in the angled geometry of the navigated reamer when compared to the straight non navigated reamer. The angled reamer can be more difficult to control forming a cavity in the correct orientation but with the possibility for the cavity to not been perfectly hemispherical. When using navigation to insert the acetabular component in a planned abduction and anteversion position during hip arthroplasty through a standard incision, navigating the reaming of the acetabular component does not appear to provide any advantage over the use of conventional non-navigated reamers in the final acetabular orientation

Introduction. Optimal alignment of the acetabulum cup component is crucial for good outcome of Total Hip Arthroplasty (THA). A patient-specific instrumentation (PSI) for cup alignment manufactured by 3D printing might improve cup alignment in conventional THAs with patient's lateral decubitus position. In this study, we developed PSI for cup alignment which transferred preoperatively planned cup alignment to the operation room as a linear visual reference(Figure 1), then investigated its accuracy in terms of fitting of PSI on the bony surface and angle deviation between pre- and post-operative cup alignments. Methods. 3-Dimensional bone models created from CT images of both sides of 6 cadaveric specimens were used in the current study. In the first experiment (first 3 specimens and six hips), we designed PSI to fit on the acetabular rim, and we inserted a Kirschner wire (K-wire) through PSI after PSI's fitting. In the second experiment (remaining 3 specimens and six hips), after the same steps like the first experiment were done, we reamed and finally impacted plastic cups with the visual reference of the K-wire. Using postoperative CT images taken after both experiments, we measured deviation of the K-wire placement for the first experiment, and measured deviation of the cup placement from planned cup alignment. Results. The angle deviation of the K-wire alignment on the basis of radiographic inclination and anteversion angles was on average 2.2°±2.5° and 1.0°±1.3° respectively in the first experiment. The angle deviation of the cup alignment with the same definition was on average 2.88°±1.63° and 4.15°±2.56°. For one cadaveric specimen data for the first experiment were missing. Conclusion. We conclude that the accuracy of acetabular cup placement can be improved by the use of patient-specific cup orientation guides

Different factors associated with an adverse functional outcome of acetabular fractures involving the posterior wall have been well documented. Among these is marginal impaction.

From 1998 until mid-2006, 105 cases were prospectively reviewed to assess the functional and radiological results of simple and complex acetabular fractures associated with a posterior wall component, with special reference to the marginal impaction. Associated posterior wall components associated with marginal impaction were compared to the pattern of fractures without marginal impaction. The exclusion criteria were non-anatomic reductions i.e. > 2 mm displacement, avascular necrosis, deep infection, heterotropic ossification grade III, IV, chondrolysis and nerve injuries. All marginal impaction fractures were identified on the pre-operative CT scan. They were openly reduced, elevated and autografted from the greater trochanter, followed by rigid internal fixation for early post-operative mobilisation i.e. CPM use.

Results were assessed clinically by the modified Merle d'Aubigné and Postel score and radiologically by Kellgren and Laurence method of grading of osteoarthritis. 40 cases were excluded for the reasons above. This left 27 cases of marginal impaction and 38 cases of control. The average period of follow-up was 35.7 months. The functional results of the marginal impaction grafting group revealed 13 (48.1%) excellent, 7 (25.9%) very good, 6 (22.2%) good and one (3.8%) fair, while the control group showed 18 (47.4%) excellent, 10 (26.3) very good, 8 (21%) good, one (2.6%) fair and one (2.6%) poor result.

The functional and radiological outcome of the posterior wall component fractures associated with marginal impaction showed very satisfactory results in comparison with a control group in the short and mid-term period. An integral part of this is careful recognition of this injury pattern and its management as part of the open reduction and fixation.

The clinical outcome and radiographic analysis of 82 patients undergoing total hip arthroplasty using a titanium acetabular component coated with a new proprietary Titanium Porous Coating inserted without cement are reported. All total hip replacements were performed by a single surgeon and utilized a porous coated, cementless femoral component. Pre clinical testing was carried out in an animal model to evaluate the new porous coating.

THR was performed using a cementless acetabular component of the same geometrical design inserted without cement. The component is coated with a new proprietary Titanium Porous Coating wherein the non-spherical bead itself is also porous. This creates a “lava rock” type of structure and gives variability in the pore sizes that aids in the in-growth and apposition of bone (fig 5). The inter-bead pore size: the pore size between each non-spherical bead = 200–525 μm while the Intra-bead pore size: the pore size within each non-spherical bead = 25–65 μm. The resulting surface is extremely rough and provides a robust initial “bite” or “stick” to the bone. Clinical results were evaluated using the Harris Hip score and were recorded prospectively preoperatively and at 6 weeks, 6 months, and 1 year postoperatively. Radiographs were evaluated for component migration, subsidence, and cortical and cancellous biologic response as well as zonal analysis of radiolucent lines, using the Muller THR template. Pre-clinical animal testing of the new porous coating was carried out in 50 sheep using a metacarpal intramedulary implant (similar to a hip stem) designed to function as a Percutaneous Osseointegrated Prosthesis (POP) for amputees and evaluated Apposition Bone Index (ABI) (fig 1), Mineral Apposition Rate (MAR) (fig 2),% Bone In-growth (fig 3), and Axial Pull-out Force (fig 4). Sheep were sacrificed at time points of 0, 3, 6, 9, and 12 months to measure and evaluate the above parameters.

Human clinical and radiographic follow up averaged 10.5 months (range 2–18 months). There were 39 females and 43 males. Average age was 59 years. The clinical results were excellent with respect to both pain and function at mid term follow up. Patient satisfaction was high. Radiographic analysis showed no migration or change in the angle of inclination at latest follow up. Femoral component subsidence was detected in 2 cases and averaged 1.8 mm. No polyethylene wear was detected. No hips dislocated. No hips underwent additional surgery. Pre-clinical test data demonstrated excellent mechanical and biological attributes. Average tensile strength of the coating surpassed the FDA minimum requirement by 3X. Animal testing in the sheep showed no evidence of stem loosening or need for revision after 12 months, and corroborated well with clinical results.

Correlation between the pre-clinical testing and the human experience was exceptional. Application of a new titanium porous coating utilizing a proprietary dual pore size structure to the surface of the acetabular component provides an extremely rough surface and robust initial fixation during cementless THR. Excellent early clinical and radiographic results are demonstrated. The addition of this new type of porous coating to other arthroplasty components may confer additional clinical advantages.

Arthroscopic hip surgery is increasingly common in Australia. Hip arthroscopy is indicated for a range of diagnostic and therapeutic purposes, including labral tears, capsular laxity and femoral-acetabular impingement (FAI). Despite this, previous cohort studies aiming to characterise hip pathology seen on arthroscopic examination are mostly limited to patients with known diagnoses of FAI. Therefore, little is known of the native articular wear patterns encountered in other disease states. Therefore, we aimed to define common osteochondral wear patterns for a cohort of patients managed via hip arthroscopy. We retrospectively analysed intraoperative data for 1127 patients managed via hip arthroscopy between 2008 and 2013, for either therapeutic or diagnostic purposes. Intraoperative data was categorized by location (A-E as defined by Fontana et al. 2016) and chondral damage (0-4 scale as defined by Beck et al. 2005) with respect to both acetabulum and femoral head. Data for 1127 patients were included. Location of acetabular chondral pathology was variable with locations C. 1. and D. 1. representing the most common regions of damage. Labral tears predominated in locations C and D. Femoral chondral pathology was evenly distributed. The degree of femoral chondral injury was predominantly grade 1, whilst acetabular wear was evenly distributed. Large proportions of wear were observed at the peripheral superior and anterior regions of the lunate surface of the acetabulum in keeping with prior works. However, we observed higher rates of central wear and lower rates of grade 4 acetabular damage extending into superior/posterior zones, in our cohort. Our work characterises common articular wear patterns encountered at the time of hip arthroscopy. Further inquiry into the natural history of osteochondral lesions is needed to better understand and manage these conditions

Femoroacetabular impingement (FAI) – enlarged, aspherical femoral head deformity (cam-type) or retroversion/overcoverage of the acetabulum (pincer-type) – is a leading cause for early hip osteoarthritis. Although anteverting/reverse periacetabular osteotomy (PAO) to address FAI aims to preserve the native hip and restore joint function, it is still unclear how it affects joint mobility and stability. This in vitro cadaveric study examined the effects of surgical anteverting PAO on range of motion and capsular mechanics in hips with acetabular retroversion. Twelve cadaveric hips (n = 12, m:f = 9:3; age = 41 ± 9 years; BMI = 23 ± 4 kg/m2) were included in this study. Each hip was CT imaged and indicated acetabular retroversion (i.e., crossover sign, posterior wall sign, ischial wall sign, retroversion index > 20%, axial plane acetabular version < 15°); and showed no other abnormalities on CT data. Each hip was denuded to the bone-and-capsule and mounted onto a 6-DOF robot tester (TX90, Stäubli), equipped with a universal force-torque sensor (Omega85, ATI). The robot positioned each hip in five sagittal angles: Extension, Neutral 0°, Flexion 30°, Flexion 60°, Flexion 90°; and performed hip internal-external rotations and abduction-adduction motions to 5 Nm in each position. After the intact stage was tested, each hip underwent an anteverting PAO, anteverting the acetabulum and securing the fragment with long bone screws. The capsular ligaments were preserved during the surgery and each hip was retested postoperatively in the robot. Postoperative CT imaging confirmed that the acetabular fragment was properly positioned with adequate version and head coverage. Paired sample t-tests compared the differences in range of motion before and after PAO (CI = 95%; SPSS v.24, IBM). Preoperatively, the intact hips with acetabular retroversion demonstrated constrained internal-external rotations and abduction-adduction motions. The PAO reoriented the acetabular fragment and medialized the hip joint centre, which tightened the iliofemoral ligament and slackenend the pubofemoral ligament. Postoperatively, internal rotation increased in the deep hip flexion positions of Flexion 60° (∆IR = +7°, p = 0.001) and Flexion 90° (∆IR = +8°, p = 0.001); while also demonstrating marginal decreases in external rotation in all positions. In addition, adduction increased in the deep flexion positions of Flexion 60° (∆ADD = +11°, p = 0.002) and Flexion 90° (∆ADD = +12°, p = 0.001); but also showed marginal increases in abduction in all positions. The anteverting PAO restored anterosuperior acetabular clearance and increased internal rotation (28–33%) and adduction motions (29–31%) in deep hip flexion. Restricted movements and positive impingement tests typically experienced in these positions with acetabular retroversion are associated with clinical symptoms of FAI (i.e., FADIR). However, PAO altered capsular tensions by further tightening the anterolateral hip capsule which resulted in a limited external rotation and a stiffer and tighter hip. Capsular tightness may still be secondary to acetabular retroversion, thus capsular management may be warranted for larger corrections or rotational osteotomies. In efforts to optimize surgical management and clinical outcomes, anteverting PAO is a viable option to address FAI due to acetabular retroversion or overcoverage

3D printing techniques have attracted a lot of curiosity in various surgical specialties and the applications of the 3D technology have been explored in many ways including fracture models for education, customized jigs, custom implants, prosthetics etc. Often the 3D printing technology remains underutilized in potential areas due to costs and technological expertise being the perceived barriers. We have applied 3D printing technology for acetabular fracture surgeries with in-house, surgeon made models of mirrored contralateral unaffected acetabulum based on the patients’ trauma CT Scans in 9 patients. The CT Scans are processed to the print with all free-ware modeling software and relatively inexpensive printer by the surgeon and the resulting model is used as a ‘reduced fracture template’ for pre-contouring the standard pelvic reconstruction plates. This allows use of the standard surgical implants, saves time on intra-operative plate contouring, and also aids in reduction to an extent. We share through this presentation the workflow of the freeware softwares to use in order to use this surgical planning and implant preparation that may remove the perceived barriers of cost and technology from surgeons that wish to explore using 3D printing technology for acetabular fracture management and may extend applications to other regions

Sacral fractures are often underdiagnosed, but are frequent in the setting of pelvic ring injuries. They are mostly caused by high velocity injuries or they can be pathological in aetiology. We sought to assess the clinical outcomes of the surgically treated unstable sacral fractures, with or without neurological deficits. unstable sacral fractures were included in the study. Single centre, prospectively collected data, retrospective review of patients who sustained vertically unstable fractures of the sacrum who underwent surgical fixation. out of a total of 432 patients with pelvis and acetabulum injuries. fifty six patients met the inclusion criteria. 18 patients had sustained zone one injuries. 14 patients had zone 2 injuries and 10 patients had zone 3 injurie. Operative fixation was performed percutaneously using cannulated screws in 18 patients.. Open fixation of the sacrum using the anterior approach in 6 patients. Posterior approach was indicates in all 10 of the zone 3 injuries of the sacrum. While in 4 patients, combined approaches were used. 3 patients had decompression and spinopelvic fixation. Neurological deficits were present in 16% of the patients. 2 patients presented with neurgenic bladder. Of the 4 patients who had neurological fall out, 3 resolved with posterior decompression and posterior fixation. All 4 neurological deficits were due to taction or compression of the nerve roots. No hardware failures or non unions observed. The rate of neurological deficit was related more to the degree of pelvic ring instability than to a particular fracture pattern. Low rates of complications and successful surgical treatment of sacral fractures is achiavable. Timeous accurate diagnosis mandatory

This technique is a novel superior based muscle sparing approach. Acetabular reaming in all hip approaches requires femoral retraction. This technique is performed through a hole in the lateral femoral cortex without the need to retract the femur. A 5 mm hole is drilled in the lateral femur using a jig attached to the broach handle, similar to a femoral nail. Specialised instruments have been developed, including a broach with a hole going through it at the angle of the neck of the prosthesis, to allow the rotation of the reaming rod whilst protecting the femur. A special C-arm is used to push on the reaming basket. The angle of the acetabulum is directly related to the position of the broach inside the femoral canal and the position of the leg. A specialised instrument allows changing of offset and length without dislocating the hip during trialling. Some instrumentation has been used in surgery but ongoing cadaver work is being performed for proof of concept. The ability to ream through the femur has been proven during surgery. The potential risk to the bone has been assessed using finite analysis as minimal. The stress levels for any diameter maintained within a safety factor >4 compared to the ultimate tensile strength of cortical bone. The described technique allows for transfemoral acetabular reaming without retraction of the femur. It is minimally invasive and simple, requiring minimal assistance. We are incorporating use with a universal robot system as well as developing an electromagnetic navigation system. Assessment of the accuracy of these significantly cheaper systems is ongoing but promising. This approach is as minimally invasive as is possible, safe, requires minimal assistance and has a number of other potential advantages with addition of other new navigation and simple robotic attachments

Abstract. Optimal acetabular component position in Total Hip Arthroplasty is vital for avoiding complications such as dislocation and impingement, Transverse acetabular ligament (TAL) have been shown to be a reliable landmark to guide optimum acetabular cup position. Reports of iliopsoas impingement caused by acetabular components exist. The Psoas fossa (PF) is not a well-regarded landmark for Component positioning. Our aim was to assess the relationship of the TAL and PF in relation to Acetabular Component positioning. A total of 22 cadavers were implanted on 4 occasions with the an uncemented acetabular component. Measurements were taken between the inner edge of TAL and the base of the acetabular component and the distance between the lower end of the PF and the most medial end of TAL. The distance between the edge of the acetabular component and TAL was a mean of 1.6cm (range 1.4–18cm). The distance between the medial end of TAL and the lowest part of PF was a mean of 1.cm (range 1,3–1.8cm) It was evident that the edge of PF was not aligned with TAL. Optimal acetabular component position is vital to the longevity and outcome following THA. TAL provides a landmark to guide acetabular component position. However we feel the PF is a better landmark to allow appropriate positioning of the acetabular component inside edge of the acetabulum inside the bone without exposure of the component rim and thus preventing iliopsoas impingement at the psoas notch and resultant groin pain

Proximal femoral focal deficiency is a congenital disorder of malformation of the proximal femur and/or the acetabulum. Patients present with limb length discrepancy and clinical features along a spectrum of severity. As these patients progress through to skeletal maturity and on to adulthood, altered biomechanical demands lead to progression of arthropathy in any joint within the lower limb. Abnormal anatomy presents a challenge to surgeons and conventional approaches and implants may not necessarily be applicable. We present a case of a 62-year-old lady with unilateral proximal femoral focal deficiency (suspected Aitken Class A) who ambulated with an equinus prosthesis for her entire life. She presented with ipsilateral knee pain and instability due to knee arthritis but could not tolerate a total knee arthroplasty due to poor quadriceps control. A custom osteointegration prosthesis was inserted with a view to converting to the proximal segment to a total hip replacement if required. The patient went on to develop ipsilateral symptomatic hip arthritis but altered acetabular anatomy required a custom tri-flange component (Ossis, Christchurch, New Zealand) and a custom proximal femoral component to link with the existing osseointegration component (Osseointegration Group of Australia, Sydney, Australia) were designed and implanted. The 18 month follow up of the custom hip components showed that the patient had Oxford hip scores that were markedly improved from pre-operatively. Knee joint heights were successfully restored to equal when the patient's prosthesis was attached. The patient describes feeling like “a normal person”, walks unaided for short distances and can ambulate longer distances with crutches. Advances in design and manufacture of implants have empowered surgeons to offer life improving treatments to patients with challenging anatomy. Using a custom acetabular tri-flange and osseointegration components is one possible solution to address symptomatic ipsilateral hip and knee arthropathy in the context of PFFD in adulthood

Abstract. Background. Conventional periacetabular pelvic resections are associated with poor functional outcomes. Resections through surgical corridors beyond the conventional margins may be helpful in retaining greater function without compromising the oncological margins. Methods. The study included a retrospective review of 82 cases of pelvic resections for pelvic tumors. Outcomes of acetabulum preservation (Group A) were compared with complete acetabular resection (Group B). Also, we compared outcomes of Type I+half resections (Group 1) with Type I+II resections (Group 2), and Type III+half resections (Group 3) with Type II+III resections (Group 4). Results. Group A (n=44) had significantly better functional outcome than Group B(n=38) with average MSTS93 score 22.3 vs 20.1 and average HHS 91.3 vs 82.5 (p<0.001). Group 1(n=14) and Group 2(n=12) had similar functional outcomes (mean MSTS93 score 22.07 vs 21.58 (p=0.597) and mean HHS 90.37 vs 86.51 (p=0.205)). Group 3(n=11) had significantly better functional outcome than Group 4(n=17), with mean MSTS93 score 22.8 vs 19.7 (p<0.001) and mean HHS 92.3 vs 80.1 (p<0.001). Oncological outcomes were similar among the groups. Conclusion. Trans-acetabular pelvic resections provide functional benefit over conventional resections without compromising oncological margins. There is a need to revisit and revise the pelvic resection planes