In a prospective study we assessed the accuracy of 3D-CT in defining the acetabular deficiency in developmental dysplasia of the hip (DDH), comparing pre-operative 3D-CT with plain radiographs, intraoperative stability testing and intraoperative acetabular morphology. Twenty children (25 hips) with DDH who had open reduction and/or pelvic osteotomy from 1999 to 2001 were studied. On 3C-CT the morphology of the deficiency was described as normal, anterolateral deficient (overlapping shadows), lateral (increased acetabular index only) and global (double acetabulum). At open reduction, the position in which the hip was most stable with axial loading was assessed (Zadeh and Caterall, 2001). The surgeon’s assessment of the acetabular morphology intraoperatively was the standard against which the other modalities were tested. One hip was normal, five had a global and 19 an anterolateral deficiency. 3D-CT correlated well with the acetabular morphology (84%). Plain radiography correlated poorly, especially with the global type (60%). Mid-superior appearance on 3D-CT and lateral appearance on plain radiograph equated with an anterolateral deficiency morphologically. In the global type the hip was unstable in all positions, while the anterolateral type, while in the anterolateral type the hip was always stable in flexion and abduction and in only 31% of hips stable also in abduction and internal rotation. The mean age at surgery was 3 years (1 to 7). The one hip with a normal acetabulum required open reduction only, the five global types an acetabuloplasty (Tonnis), and the 19 hips with anterolateral deficiency a redirectional (Salter) osteotomy. 3D-CT is helpful in appropriate osteotomy for a specific type of acetabular deficiency in DDH

Background. In total hip arthroplasty (THA), preservation of the short external rotator muscles are considered to be important because they contribute to joint stability and prevent postoperative dislocation. Recently, we reported that there are bony impressions on the greater trochanter that indicate the insertions of the short external rotator tendons. In this study, we reported a method to visualize the bony impressions using preoperative CT images, and evaluate the reliability and accuracy of this method. Methods. Thirty-three hips from 24 consecutive patients undergoing THA were enrolled. The mean age was 65.3 years. Preoperative diagnoses included hip osteoarthritis in 27 hips, rheumatoid arthritis in 4 hips, idiopathic osteonecrosis in 1 hip, femoral neck fracture in 1 hip. Preoperative CT of the hip region was obtained and three-dimensional (3D) reconstruction of the greater trochanter was performed to visualize the bony impressions, that we called the obturator tendon attachment (OTA), indicating the attachment area of the obturator internus and externus muscles. Results. 3D reconstructed images of the greater trochanter were observed from medial side at 50 degrees of external hip rotation and 20 degrees of abduction (OTA view). Using OTA view, the bony impressions indicating the attachment area of the obturator internus and externus muscles can be identified in all hips. Conclusions. The bony impressions indicating the attachment area of the obturator internus and externus muscles can be visualized using preoperative 3D-CT. We considered that the findings in the present study could be helpful for surgery because the alignment of the short external rotator muscles can be estimated preoperatively and the extent of the damage to the OA during the rasping or reaming can be estimated

[Background]

Factors determining improvement of the long-term outcome of total knee arthroplasty include accurate reproduction of lower limb alignment. To acquire appropriate lower limb alignment, tibial component rotation is an important element for outcomes. We usually determine the tibial component rotation using the anatomical rotaional landmark of the proximal tibia and range of motion technique. In addition we followed by confirmation of overall lower limb alignment referring to the distal tibial index. When the tibia have a rotational mismatch between its proximal and distal AP axis, a larger error of the distal tibial index than those of other rotational landmark is of concern. The purpose of this study is to evaluate the reliability of the distal tibial AP axis as a reference axis of tibial compornent rotation in the intraoperative setting.

First-time anterior dislocation of the shoulder is associated with the development of recurrent instability. It is recognised that patients with recurrent instability often have osseous defects. Using 3D computerised tomography (3DCT) it is possible to quantify these defects. Whether these defects are present after the primary dislocation or occur progressively from multiple dislocations is unclear. We correlated the presence of Hill-Sachs lesions and anterior glenoid bone loss with evidence of recurrent dislocation and clinical outcomes.

78 patients were followed up for two years. All underwent a 3DCT within a week of injury. Standardised images of the humeral head and glenoid were produced. Using standardised digital techniques bone loss was measured.

39% of the patients developed further instability. Average Hill-Sachs circumferential length = 15.23%. Average Hill-Sachs surface area = 5.53%. The length and surface area of the Hill-Sachs lesions were significantly associated with further instability. (p=0.019 and p=0.003). Average en face glenoid surface area loss=1.30% with no association to instability (p=0.685). There was poor correlation between the size of the glenoid lesion and the size of the Hill-Sachs lesion.

Results showed that age and increasing size of the Hill-Sachs lesions result in a higher rate of instability. Interestingly glenoid bone loss was relatively low and did not predict recurrent instability. The size of the Hill-Sachs lesion does not have a linear relationship with glenoid bone loss. Further work defining the morphology of the Hill-Sachs lesion and its engagement with a glenoid defect is required.

Vascular injury associated with hip surgery is a rare but serious complication. Hip surgeons need to understand the vascular anatomy around the acetabulum to avoid vascular injury. The aim of this study was to visualize the pelvic vascular structures thorough the osseous acetabulum using 3DCT angiography and to describe the three-dimensional relationship between the vessels and the acetabulum. A total of 100 patients who took 3DCT with intravenous contrast for intra-pelvic neoplastic disease were randomly chosen. Those patients with hip disease were excluded. Three examinations were performed.

First, dual-phase helical CT data were transferred to a workstation (M900;Zio,Tokyo,Japan) and 3D visualizations of the vascular structures through the pelvis were reconstructed.

Second, location of the external iliac, femoral and obturator vessels were investigated in axial CT images. Finally, influence of the age factor on the anatomical courses of the external iliac vessels was assessed.

Reconstructed 3D images were able to provide spatial relationship between courses of the pelvic vascular structures and the acetabulum. We could visualize the pelvic vascular structures thorough the pelvis from similar operative viewpoints. Axial CT examinations revealed the external iliac vessels locate very closely to the pelvis as they exit the pelvic cavity.

Especially, the left side vessels and vein were closer to the pelvis. The femoral vessels became closer to the acetabular edge with traveling distally. At the distal half of the acetabulum, the femoral vessels located just ventrally to the anterior acetabular edge. The obturator vessels courses inferiorly along the quadrilateral surface behind the acetabulum, they became very close to the inner cortex or the acetabulum. Straight type of the anatomical course of the external iliac vessels was the most common configuration in young patients, curved and the tortuous types were present in older patients.

The results of this study are useful to understand the anatomical orientation of the vessels around the acetabulum. To avoid vascular injuries in hip surgery, knowledge of the vascular orientation is of critical importance for the hip surgeon.

We used immediate post-operative in vivo three-dimensional computed tomography to compare graft bending angles and femoral tunnel lengths in 155 patients who had undergone single-bundle reconstruction of the anterior cruciate ligament using the transtibial (n = 37), anteromedial portal (n = 72) and outside-in (n = 46) techniques.

The bending angles in the sagittal and axial planes were significantly greater but the coronal-bending angle was significantly less in the transtibial group than in the anteromedial portal and outside-in groups (p < 0.001 each). The mean length of the femoral tunnel in all three planes was significantly greater in the transtibial group than the anteromedial portal and outside-in groups (p < 0.001 each), but all mean tunnel lengths in the three groups exceeded 30 mm. The only significant difference was the coronal graft- bending angle in the anteromedial portal and outside-in groups (23.5° vs 29.8°, p = 0.012).

Compared with the transtibial technique, the anteromedial portal and outside-in techniques may reduce the graft-bending stress at the opening of the femoral tunnel. Despite the femoral tunnel length being shorter in the anteromedial portal and outside-in techniques than in the transtibial technique, a femoral tunnel length of more than 30 mm in the anteromedial portal and outside-in techniques may be sufficient for the graft to heal.

Cite this article: Bone Joint J 2014;96-B:743–51.

Orientation of the acetabular component influences wear, range of movement and the incidence of dislocation after total hip replacement (THR). During surgery, such orientation is often referenced to the anterior pelvic plane (APP), but APP inclination relative to the coronal plane (pelvic tilt) varies substantially between individuals. In contrast, the change in pelvic tilt from supine to standing (dPT) is small for nearly all individuals. Therefore, in THR performed with the patient supine and the patient’s coronal plane parallel to the operating table, we propose that freehand placement of the acetabular component placement is reliable and reflects standing (functional) cup position. We examined this hypothesis in 56 hips in 56 patients (19 men) with a mean age of 61 years (29 to 80) using three-dimensional CT pelvic reconstructions and standing lateral pelvic radiographs. We found a low variability of acetabular component placement, with 46 implants (82%) placed within a combined range of 30° to 50° inclination and 5° to 25° anteversion. Changing from the supine to the standing position (analysed in 47 patients) was associated with an anteversion change < 10° in 45 patients (96%). dPT was < 10° in 41 patients (87%). In conclusion, supine THR appears to provide reliable freehand acetabular component placement. In most patients a small reclination of the pelvis going from supine to standing causes a small increase in anteversion of the acetabular component.

Cite this article: Bone Joint J 2013;95-B:1326–31.

The February 2024 Children’s orthopaedics Roundup. 360. looks at: Hip impingement after in situ pinning causes decreased flexion and forced external rotation in flexion on 3D-CT; Triplane ankle fracture patterns in paediatric patients; Improved forearm rotation even after early conversion to below-elbow; Selective dorsal rhizotomy and cerebral palsy (CP) hip displacement; Abduction bracing following anterior open reduction for developmental dysplasia of the hip does not improve residual dysplasia or reduce secondary surgery; 40% risk of later total hip arthroplasty for in situ slipped capital femoral epiphysis (SCFE) pinning; Does brace treatment following closed reduction of developmental dysplasia of the hip improve acetabular coverage?; Waterproof hip spica casts for paediatric femur fractures

In this paper we propose a new classification of neurogenic peri-articular heterotopic ossification (HO) of the hip based on three-dimensional (3D) CT, with the aim of improving pre-operative planning for its excision. . A total of 55 patients (73 hips) with clinically significant HO after either traumatic brain or spinal cord injury were assessed by 3D-CT scanning, and the results compared with the intra-operative findings. At operation, the gross pathological anatomy of the HO as identified by 3D-CT imaging was confirmed as affecting the peri-articular hip muscles to a greater or lesser extent. We identified seven patterns of involvement: four basic (anterior, medial, posterior and lateral) and three mixed (anteromedial, posterolateral and circumferential). Excellent intra- and inter-observer agreement, with kappa values > 0.8, confirmed the reproducibility of the classification system. We describe the different surgical approaches used to excise the HO which were guided by the 3D-CT findings. Resection was always successful. . 3D-CT imaging, complemented in some cases by angiography, allows the surgeon to define the 3D anatomy of the HO accurately and to plan its surgical excision with precision. Cite this article: Bone Joint J 2015; 97-B:899–904

Femoral stem version has a major influence on impingement and early post-operative stability after total hip arthroplasty (THA). The main objective of this study was to evaluate the validity of a novel radiological method for measuring stem version. Anteroposterior (AP) radiographs and three-dimensional CT scans were obtained for 115 patients (female/male 63/72, mean age 62.5 years (50 to 75)) who had undergone minimally invasive, cementless THA. Stem version was calculated from the AP hip radiograph by rotation-based change in the projected prosthetic neck–shaft (NSA*) angle using the mathematical formula ST = arcos [tan (NSA*) / tan (135)]. We used two independent observers who repeated the analysis after a six-week interval. Radiological measurements were compared with 3D-CT measurements by an independent, blinded external institute. We found a mean difference of 1.2° (. sd. 6.2) between radiological and 3D-CT measurements of stem version. The correlation between the mean radiological and 3D-CT stem torsion was r = 0.88 (p < 0.001). The intra- (intraclass correlation coefficient ≥ 0.94) and inter-observer agreement (mean concordance correlation coefficient = 0.87) for the radiological measurements were excellent. We found that femoral tilt was associated with the mean radiological measurement error (r = 0.22, p = 0.02). . The projected neck–shaft angle is a reliable method for measuring stem version on AP radiographs of the hip after a THA. However, a highly standardised radiological technique is required for its precise measurement. . Cite this article: Bone Joint J 2015; 97-B:306–11

We studied the intra- and interobserver reliability of measurements of the position of the components after total knee replacement (TKR) using a combination of radiographs and axial two-dimensional (2D) and three-dimensional (3D) reconstructed CT images to identify which method is best for this purpose. A total of 30 knees after primary TKR were assessed by two independent observers (an orthopaedic surgeon and a radiologist) using radiographs and CT scans. Plain radiographs were highly reliable at measuring the tibial slope, but showed wide variability for all other measurements; 2D-CT also showed wide variability. 3D-CT was highly reliable, even when measuring rotation of the femoral components, and significantly better than 2D-CT. Interobserver variability in the measurements on radiographs were good (intraclass correlation coefficient (ICC) 0.65 to 0.82), but rotational measurements on 2D-CT were poor (ICC 0.29). On 3D-CT they were near perfect (ICC 0.89 to 0.99), and significantly more reliable than 2D-CT (p < 0.001). 3D-reconstructed images are sufficiently reliable to enable reporting of the position and orientation of the components. Rotational measurements in particular should be performed on 3D-reconstructed CT images. When faced with a poorly functioning TKR with concerns over component positioning, we recommend 3D-CT as the investigation of choice

Introduction. The achieved anteversion of uncemented stems is to a large extent limited by the internal anatomy of the bone. A better understanding of this has recently become an unmet need because of the increased use of uncemented stems. We aimed to assess plan compliance in six degrees of freedom to evaluate the accuracy of PSI and guides for stem positioning in primary THAs. Materials and Methods. We prospectively collected 3D plans generated from preoperative CTs of 30 consecutive THAs (17 left and 13 right hips), in 29 patients with OA, consisting of 16 males and 13 females (median age 68 years, range 46–83 years). A single CT-based planning system and cementless type of implant were used. Post operatively, all patients had a CT scan which was reconstructed using state-of-the-art software solution: the plan and CT reconstruction models were. Outcome measures: 1) discrepancy between planned and achieved stem orientation angles Fig.2&3; 2) clinical outcome. Results. 1) The mean (±SD) discrepancy was low for: Varus-valgus −1.1 ± 1.4 deg (IQR −2.2 – 0.3 deg); Anterior-posterior 0.1 ± 1.6 deg (IQR −0.7 – 1.3 deg). The discrepancy was higher for femoral version −1.4 ± 8.2 deg (IQR −8.3 – 7.2 deg). 3D-CT planning correctly predicted sizes in 93% of the femoral components. 2) There was no intra-operative fracture, no case showed evidence of early periprosthetic osseous injury. Discussion. Surgeons and engineers should be cautious with their expectation of achieving the planned femoral stem version of an uncemented femoral stem from the pre-operative 3D-CT plan. Conclusion. This is the first study to 3D-mensionally evaluate 3D-printed patient-specific instrumentation and guides for achieved femoral stem component orientation vis-à-vis to the plan. The tools allow accurate implant orientation, however there is still potential for improvement. For any figures or tables, please contact the authors directly

We evaluated (1) wear rate, (2) prevalence and volume of osteolysis using 3D-CT scan, (3) other bearing-related complications, (4) HHS and survivorship free from revision at 15 years after THA using first-generation XLPE (1G XLPE). One-hundred sixty THAs were evaluated regarding bearing-related complication, HHS and survivorship. Among them, 112 hips underwent 3D-CT to analyze wear rate and osteolysis. All THAs were performed by single surgeon using cup of identical design, a 28-mm metal head and 1G XLPE (10 Mrad). Average age were 57 years and mean follow-up was 15.2 years. 3D-CT scan was performed at average of 13.0 years. Clinical evaluation included HHS and radiographic analysis was performed regarding stem alignment, cup anteversion and inclination angle, component stability, wear rate and osteolysis. Wear was measured using digital software. The prevalence and volume of osteolysis were also evaluated. Complications included XLPE dissociation/rim fracture, dislocation, periprosthetic fracture, infection, HO and any revision. Survivorship free from revision at 15 years was estimated. Average inclination and anteversion angle of cups were 40.7° and 20.6°. Mean stem alignment was 0.1° valgus. Average bedding-in and annual wear rate wear rate was 0.085 mm and 0.025 mm/yr. Eleven hips (10%) demonstrated osteolysis; pelvic osteolysis with average volume of 1.4 cm. 3. in six and femoral osteolysis with mean size of 0.4 cm. 2. in seven hips. Of 160 THAs, 5 hips (3%) dislocated. Overall, bearing-related complications occurred in 16 hips (10%). Other complications included postoperative periprosthetic fracture in 4 (3%), infection and HO in 3 hips, respectively. No hip demonstrated loosening, XLPE rim fracture/dissociation. Seven THAs (4%) were revised; recurrent dislocation in 5 and periprosthetic joint infection in 2 hips. Average HHS at last follow-up improved from 47.7 preoperatively to 91.2 points (p<0.001). Estimated survivorship free from revision at 15 years was 95.6 %. THA using 1G XLPE demonstrated low wear rate as well as low incidence of osteolysis at average follow-up of fifteen years. Longer-term studies will be necessary to determine if XLPE will continue to demonstrate this improved osteolysis characteristics

INTRODUCTION. Short femoral nail is the most popular instrumentation for femoral trochanteric fractures. PFNA is in widely use and good results are reported. In these papers, fracture classification and evaluation of surgical results were based on plain X-ray. However, some cases of delayed union, non-union, and blade cut out showed no critical problems in immediate postoperative X-ray. Cause of these complications was not able to solve in X-ray analysis. CT scan provides more information about fracture pattern and position of nail and blade. CT analysis is likely to solve the cause of these complications. MATERIALS & METHODS. 20 cases of 36 femoral trochanteric fractures treated with PFNA-II were evaluated by CT scan (pre and post surgery). Four males and 16 females, and average age at surgery was 80.5 (65–100). Eleven cases were A1 fracture and 9 cases were A2 fracture in AO classification. Nail insertion hole was made by custom made Hollow Reamer. Fracture classification with 3D-CT (Nakano's classification), position of nail insertion hole (relationship between neck or head), and postoperative evaluation with 3D-CT insertion part of nail and blade were investigated. RESULTS. Nakano classified femoral trochanteric fracture into 7 types in 3D-CT. Two subtype in 2 part fracture, 4 subtype in 3 part fracture and 4part fracture. Seven cases were two part fracture, 11 were three part, and 2 were four part in our series. Five cases of 11 in 3 part fracture was considered unstable type. Nail insertion hole of six cases was made posteriory to the connecting line between neck center and head center. Fracture line of greater trochnater in lateral wall opened in 4 cases because of nail insertion. DISCUSSION. Femoral trochanteric fracture was classified by Evans classification or AO classification. However, it is very difficult to classify the fracture by plain X-P. Classification with 3D-CT is very usefull to distinguish which the fracture is stable or unstable. CT analysis will solve the postoperative complications in stable type in X-P classification

Introduction. In the evaluation of patients with pre-arthritic hip disorders, making the correct diagnosis and identifying the underlying bone pathology is of upmost importance to achieve optimal patient outcomes. 3-dimensional imaging adds information for proper preoperative planning. CT scans have become the gold standard for this, but with the associated risk of radiation exposure to this generally younger patient cohort. Purpose. To determine if 3D-MR reconstructions of the hip can be used to accurately demonstrate femoral and acetabular morphology in the setting of femoroacetabular impingement (FAI) and development dysplasia of the hip (DDH) that is comparable to CT imaging. Materials and Methods. We performed a retrospective review of 14 consecutive patients with a diagnosis of FAI or DDH that underwent both CT and MRI scans of the same hip with 3D reconstructions. 2 fellowship trained musculoskeletal radiologists reviewed all scans, and a fellowship trained hip preservation surgeon separately reviewed scans for relevant surgical parameters. All were blinded to the patients' clinical history. The 3D reconstructions were evaluated by radiologists for the presence of a CAM lesion and acetabular retroversion, while the hip preservation surgeon also evaluated CAM extent using a clock face convention of a right hip, location of femoral head blood supply, and morphological anterior inferior iliac spine (AIIS) variant. The findings on the 3D CT reconstructions were considered the reference standard. Results. Of 14 patients, there were 9 females and 5 males with a mean age 32 (range 15–42). There was no difference in the ability of MRI to detect the presence of a CAM lesion (100% agreement between 3D-MR and 3D-CT, p=1), AIIS morphology (p=1, mode=type 1 variant), or acetabular retroversion (85.7%, p=0.5). 3D-MR had a sensitivity and specificity of 100 in detecting a CAM lesion relative to 3D-CT. Four CT studies were inadequate to adequately evaluate for presence of a CAM. Five CT studies were inadequate to evaluate for location of the femoral head vessels, while MRI was able to determine location in those patients. In the 10 remaining patients for presence of CAM, and nine patients for femoral head vessel location, there was no statistically significant difference between 3D-MR and 3D-CT in determining the location of CAM lesion on a clock face (p=0.8, mean MRI = 12:54, mean CT: 12:51, SD = 66 mins MR, 81 mins CT) or in determining vessel location (p=0.4, MR mean 11:23, CT mean 11:36, SD 33 mins for both). Conclusion. 3D MRI reconstructions are as accurate as 3D CT reconstructions in evaluating osseous morphology of the hip, and may be superior to CT in determining other certain clinically relevant hip parameters. 3D-MR was equally useful in determining the presence and extent of a CAM lesion, acetabular retroversion, and AIIS morphologic variant, and more useful than 3D CT in determining location of the femoral head vessels. In evaluating FAI or hip dysplasia, a 3D-MR study is sufficient to evaluate both soft tissue and osseous anatomy, sparing the need for a 3D CT scan and its associated radiation exposure and cost

The August 2012 Children’s orthopaedics Roundup. 360. looks at: whether 3D-CT gives a better idea of coverage than plain radiographs; forearm fractures after trampolining accidents; forearm fractures and the Rush pin; the fractured distal radius; elastic stable intramedullary nailing for long-bone fractures; aponeurotic recession for the equinus foot; the torn medial patellofemoral ligament and the adductor tubercle; slipped capital femoral epiphysis; paediatric wrist arthroscopy; and Pirani scores and clubfoot

The radiographic analysis of over 5000 metal on metal (MoM) hips using Ein Bild Roentgen Analyse (EBRA) software have been recently published in an attempt to determine the influence of cup orientation on bearing function. The validation of this software relies one study, conducted in a phantom pelvis without a femoral head in situ. Three dimensional computed tomographic (3D-CT) has been shown to be more accurate for hip and knee arthroplasty than plain radiographs for measurements of component orientation and position. The accuracy of EBRA when compared to 3D-CT for MoM hips specifically is unclear. We measured the cup orientation of 96 large diameter MoM hips using EBRA analysis of plain radiographs and compared this to 3D-CT. All measurements were made using the radiographic definition of cup orientation. The mean difference in version between the two imaging modalities was 8°; with wide limits of agreement of −21.2° and +5.6°. Three retroverted cups were not detected by EBRA. The mean difference in inclination values was 0.3°, but there was up to 9°difference between imaging modalities. When measured by 3D CT, 64% of hips were within a 10° safe zone around 45° inclination and 20° version, compared to only 24% when measured by EBRA (Fishers Exact test, p< 0.0001). The measurement of cup orientation of MoM hips using EBRA software is insufficiently accurate, particularly for the assessment of cup version. The cup rim is obscured by the large diameter femoral head on plain radiographs. Research studies using EBRA analysis for version have limited value if accuracy of more than 20 degrees is required to draw conclusions. This software may not be suitable to measure the performance of a device or surgeon. The limitations of EBRA can be overcome, if 3D-CT with an extended Hounsfield scale for data capture is used

Purpose. In total elbow arthroplasty (TEA), especially for elbows with condyle defect due to rheumatoid arthritis or trauma, determination of rotation alignment of implants is often difficult. To develop a navigation system for TEA, selecting bony landmarks that can be identified intraoperatively is important. Therefore, we developed a new roentgen free navigation system such as special alignment jigs for TEA based on CT data of normal elbows. The aim of this study was to evaluate alignments of implants after MIS-TEA using the new systems. And also, we reported that 6 bony landmarks on the elbow showed small variability in normal elbows by CT examinations and were considered to be usable as intraoperative landmarks for determining rotational position of implants last year. Especially in RA elbow, posterior aspect of humerus and ulnar aspect of proximal part of ulna were able to be identified even if there is a large bone defect that extends to the lateral or/and medial epicondyle. We used a new roentgen free navigation system in TEA with using Solar elbow from 2009. The aim of this study was to evaluate alignments of implants after MIS-TEA using the new systems by CT examinations. MATERIALS AND METHODS. For determination of alignment and anatomical landmarks to develop the jigs, 3D-CT data of 11 normal elbows was investigated. The posterior aspect of humeral shaft and ulnar aspect of proximal ulna were selected as bony landmarks. Because these can be identified intraoperatively and remain in elbows with extensive bone loss. MIS-TEA with Solar Elbow (Stryker) using these new systems were investigated with postoperative 3D-CT in 14 elbows of 13 patients. Their average age was 68.8 years old. Basic diseases were 10 rheumatoid arthritis and 4 distal humerus injuries. The alignments of humeral and ulnar component were measured on postoperative 3D-CT. RESULTS. Rotational alignment (humerus / ulna) was pronation 6.8° ± 5.7° / pronation 4.6° ± 9.1°; frontal alignment was valgus 0.1° ± 2.7° / valgus 0.1° ± 3.7°; and sagittal alignment was extension 0.6° ± 3.0° / extension 8.9° ± 2.5°. In condyle-defect group (n=5), comparable alignment with condyle-preserved group was obtained. DISCUSSION. The new systems were effective in determining intraoperative alignment even in elbows with extensive bone defect. Extension alignment of the ulna component is because the short component of Solar Elbow was placed along the center axis of the proximal ulna, which inclines in the extension direction relative to the axis of distal ulna

Objectives. Our principle is to bring the socket back to the true acetabulum position. A large structural bone graft is required for severe subluxation. We obtained good long-term results with structural bone grafts. It is necessary to evaluate the bone graft 3 dimensionally, not 2 dimensionally. M and M. We evaluated our 305 primary THAs operated from April 2010 to Mar 2014. Structural bone grafts were utilized on the acetabulum in 39 cases (12.8%). We measured the CE angle on post-operative plain coronal x-rays. 3D-CT evaluation was carried out on the cases with CE angles of 0 degrees or less. We checked the position of the graft and see how much surface area the graft occupies of the total area that receives the load. Result. Mean CE angle on the post-op plain coronal x-rays was −1.5°. 15 cases (38.5%) had 0 degree or less CE angles on the post-op plain coronal x-rays. 11 cases (−15°≤CE<0°), and 4 cases (−30°≤CE<−15°). Mean CE angle was +3.7° on coronal CT of the apex of the socket. Graft position on the acetabulum on 3D-CT was anterosuperior in 13 cases and posterosuperior in 2 cases, wile none showed wide positioning from anterosuperior to posterior. Conclusion. The contact surface area between the graft and the socket is not necessarily large 3 dimensionally, even if the CE angle is 0 degrees in the plain coronal X-rays. Depending on the graft position, sufficient support is considered to be obtained, even though a large size graft is used

INTRODUCTION. An accelerometer-based portable navigation system (KneeAlign2, OrthAlign Inc., Aliso Viejo, CA) is expected to improve mechanical axis and component alignment compared to conventional instrumentation in total knee arthroplasty (TKA). However, past reports have evaluated its accuracy using only radiographic measurements. The purpose of this study was to analyze the accuracy of the KneeAlign2 system with radiography and more detailed three-dimensional (3D) CT. METHODS. We targeted 22 patients (24 knees) with severe osteoarthritis who underwent primary TKA using the KneeAlign2 system. Cemented, fixed-bearing, cruciate-retaining prostheses were implanted in all patients. We used postoperative standing-position full-length radiographic evaluation of the lower limbs to measure the hip-knee-ankle angle (HKA), frontal femoral component angle (FFC), and frontal tibial component angle (FTC). However, lower limb rotation and knee flexion could affect radiographic measurement of HKA and the component positioning angle. We used 3D bone models reconstructed from pre- and postoperative CT images to precisely analyze the 3D component positioning. For a 3D matching bone model made from these models, a 2D projection of the pre- and postoperative component positioning planes was made, and the projection angle was measured as angle error compared to the preoperative planned position (Figure 1). Average surgery time and total blood loss on postoperative day 7 were also recorded. RESULTS. There were 24 knees available for analysis. Mean HKA was 0.1° ± 2.2 varus; 16.7% of knees had coronal outliers exceeding 3°. Mean FFC was 0.9° ± 1.9 varus; 29.2% of femoral components were placed with coronal outliers exceeding 2°. Mean FTC was 1.2° ± 1.6 valgus; 20.8% of tibial components were placed with coronal outliers exceeding 2°. In 3D-CT evaluation, mean femoral coronal and sagittal alignment were 1.2° ± 1.7 varus (outliers exceeding ±2°: 37.5%) and 0.8° ± 2.4 flexion (outliers exceeding ±2°: 20.8%), respectively. Mean tibial coronal and sagittal alignment were 1.1° ± 1.4 valgus (outliers exceeding ±2°: 33.3%) and 0.1° ± 1.6 flexion (outliers exceeding ±2°: 20.8%), respectively. Average surgical time was 96 ± 7.7 minutes, and blood loss was 400 g ± 113 on postoperative day 7. CONCLUSIONS. With radiographic and 3D-CT evaluation, the mean angle error values for the femoral and tibial components were less than 2° in the coronal plane, and less than 1° in the sagittal plane. KneeAlign2 is highly accurate in positioning the femoral and tibial components in TKA. For figures/tables, please contact authors directly.