Assessment of malreduction standards for the syndesmosis in bilateral CT scans of uninjured ankles.

AIMS: Malreduction of the syndesmosis has been reported in up to 52% of patients after fixation of ankle fractures. Multiple radiological parameters are used to define malreduction; there has been limited investigation of the accuracy of these measurements in differentiating malreduction from inherent anatomical asymmetry. The purpose of this study was to identify the prevalence of positive malreduction standards within the syndesmosis of native, uninjured ankles. METHODS: Three observers reviewed 213 bilateral lower limb CT scans of uninjured ankles. Multiple measurements were recorded on the axial CT 1 cm above the plafond: anterior syndesmotic distance; posterior syndesmotic distance; central syndesmotic distance; fibular rotation; and sagittal fibular translation. Previously studied malreduction standards were evaluated on bilateral CT, including differences in: anterior, central and posterior syndesmotic distance; mean syndesmotic distance; fibular rotation; sagittal translational distance; and syndesmotic area. Unilateral CT was used to compare the anterior to posterior syndesmotic distances. RESULTS: A difference of anterior to posterior syndesmotic distance > 2 mm was observed in 89% of ankles (n = 190) on unilateral CT assessment. Using bilateral CT, we found that 35% (n = 75) of normal ankles would be considered malreduced by current malreduction parameters. In 50 patients (23%), only one parameter was anomalous, 18 patients (8%) had two positive parameters and seven patients (3%) had three. Difference in fibular rotation had the lowest false positive rate of all parameters at 6%, whereas posterior syndesmotic distance difference had the highest at 15%. CONCLUSION: In this study, 35% of native, uninjured syndesmoses (n = 75) would be classified as malreduced by current diagnostic standards on bilateral CT and 89% had an asymmetric incisura on unilateral CT (n = 190). Current radiological parameters are insufficient to differentiate mild inherent anatomical asymmetry from malreduction of the syndesmosis. Cite this article: Bone Joint J 2021;103-B(1):178-183.

Bilateral Low-Dose Computed Tomography Assessment for Post-Operative Rotational Malalignment After Intramedullary Nailing for Tibial Shaft Fractures: Reliability of a Practical Imaging Technique.

INTRODUCTION: The purpose of this study is to evaluate the intra- and inter-observer reliability of low-dose protocolled bilateral postoperative Computed Tomography (CT)-assessment of rotational malalignment after intramedullary nailing (IMN) of tibial shaft fractures. MATERIALS AND METHODS: 156 patients were prospectively included with tibial shaft fractures that were treated with IMN in a Level-I Trauma Centre. All patients underwent post-operative bilateral low-dose CT-assessment (effective dose of 0.03784 - 0.05768 mGy) as per hospital protocol. Four observers performed the validated reproducible measurements of tibial torsion in degrees, based on standardized techniques. The Intra-Class Coefficient (ICC) was calculated to evaluate intra- and inter-observer reliability. The intra- and inter-observer reliability was categorized according to Landis and Koch. RESULTS: Intra-observer reliability for quantification of rotational malalignment on post-operative CT after IMN of tibial shaft fractures was excellent with 0.95 (95% CI = 0.92-0.97). The overall inter-observer reliability was 0.90 (95% CI = 0.87-0.92), also excellent according Landis and Koch. CONCLUSION: Firstly, bilateral post-operative low-dose -similar radiation exposure as plain chest radiographs- CT assessment of tibial rotational alignment is a reliable diagnostic imaging modality to assess rotational malalignment in patients following IMN of tibial shaft fractures and it allows for early revision surgery. Secondly, it may contribute to our understanding of the incidence-, predictors- and clinical relevance of post-operative tibial rotational malalignment in patients treated with IMN for a tibial shaft fracture, and facilitates future studies on this topic.

Assessment of Loosening and Rotational Malalignment Following Knee Endoprosthesis or Other Surgical Components.

Total knee arthroplasty (TKA) has significant medical and economic implications. The correct placement of the femoral and tibial components is vital to ensure a functional knee and also low failure and revision surgery rates. This article provides the most relevant information regarding knee endoprosthesis from a radiologic point of view. Basic information on the recommended alignment of the femoral and tibial components in TKA and how to measure them are discussed. We then present the most important axial plane rotational references for the femoral and the tibial components. The optimal coronal alignment, illustrating the axes of the lower limb, and loosening as the major complication are also discussed. Finally, we offer a detailed example of rotational assessment.

MRI Assessment of Supra- and Infratrochanteric Femoral Torsion: Association With Femoroacetabular Impingement and Hip Dysplasia.

OBJECTIVE: The objective of our study was to evaluate a novel measurement technique for assessing the supra- and infratrochanteric components of femoral torsion, establish reference values in healthy volunteers, and compare supra- and infratrochanteric torsion angles in patients with hip dysplasia and patients with femoroacetabular impingement (FAI) with those in healthy volunteers. MATERIALS AND METHODS: Femoral torsion was assessed in 380 patients and 61 healthy volunteers on MRI. For assessing supra- and infratrochanteric torsion, three measurement techniques (i.e., Kim, simplified Kim, and centroid methods) were evaluated by two readers on 100 patients. The technique with the highest interreader reliability was selected to perform measurements on all patients and volunteers. Supra- and infratrochanteric torsion angles of patients were stratified by hip disorders, which were diagnosed by specialized hip surgeons, and were compared with reference values of healthy volunteers. Statistical analysis included the independent t test, Mann-Whitney U test, and intraclass correlation coefficient (ICC). RESULTS: The centroid method showed the highest interreader reliability for measuring supra-and infratrochanteric torsion with an ICC of 0.979. The supra- and infratrochanteric torsion values of the volunteers were 31.5° ± 7.4° (mean ± SD) and -18.3° ± 9.9°, respectively. In comparison with the volunteers, patients with hip dysplasia had significantly higher supraand infratrochanteric torsion values of 37.5° ± 10.3° (p = 0.001) and -9.6° ± 11.7° (p < 0.001) and patients with pincer-type FAI had significantly higher supratrochanteric torsion values of 37.8° ± 8.0° (p = 0.002). CONCLUSION: The supra- and infratrochanteric components of femoral torsion differ substantially between hip disorders: Patients with hip dysplasia have predominantly increased infratrochanteric torsion, whereas patients with pincer-type FAI have increased supratrochanteric torsion. Quantification of separate supra- and infratrochanteric torsion angles allows a more detailed analysis of hip disorders and may influence treatment planning.

Pathoanatomy of the Tongue-Type Calcaneus Fracture: Assessment Using 2- and 3-Dimensional Computed Tomography.

OBJECTIVE: To define the pathoanatomy of the tongue-type calcaneus fracture and assess the appropriateness of percutaneous techniques in addressing all planes of deformity in this injury. DESIGN: Retrospective cohort. SETTING: ACS Level I trauma center. PATIENTS/PARTICIPANTS: Fifty-six displaced Sanders 2B and 2C tongue-type calcaneus fractures identified from an initial cohort of 1118 calcaneus fractures treated over a 16-year period. MAIN OUTCOME MEASUREMENTS: We reviewed cross-sectional imaging and documented the presence of a varus/valgus (coronal plane) or adduction/abduction (axial plane) position of the tongue fragment in relation to the intact posterior facet, with greater than 10 degrees of angulation being diagnostic of displacement. RESULTS: When assessing for displacement and angulation in the coronal plane, 98% of tongue fragments were either in a position of valgus (77%) or neutral (21%), with a mean valgus angulation of 17.3 degrees. In the axial plane, 98% of tongue pieces were in a position of adduction (64%) or neutral (34%), with an average angulation into adduction of 15.0 degrees. Sanders 2B fractures were more likely to be in a position of valgus and adduction than those of 2C fractures. DISCUSSION: The tongue-type calcaneus fracture most often displaces into a position of plantarflexion, valgus, and adduction. Knowledge of this deformity may aid in achieving successful closed reduction when using the Essex-Lopresti maneuver or other less invasive techniques.

Radiographic assessment of knee-ankle alignment after total knee arthroplasty for varus and valgus knee osteoarthritis.

BACKGROUND: There are unanswered questions about knee-ankle alignment after total knee arthroplasty (TKA) for varus and valgus osteoarthritis (OA) of the knee. The aim of this retrospective study was to assess knee-ankle alignment after TKA. METHODS: The study consisted of 149 patients who had undergone TKA due to varus and valgus knee OA. The alignment and angles in the selected knees and ankles were measured on full-length standing anteroposterior radiographs, both pre-operatively and post-operatively. The paired t-test and Pearson's correlation tests were used for statistical analysis. RESULTS: The results showed that ankle alignment correlated with knee alignment both pre-operatively and postoperatively (P<0.05). The pre-operative malalignment of the knee was corrected (P<0.05), and the ankle tilt angle was accordingly improved in the operative side after TKA (P<0.05). In addition, TKA had little effect on knee-ankle alignment on the non-operative side (P>0.05). CONCLUSION: These findings indicated that routine TKA could correct the varus or valgus deformity of a knee, and improve the tilt of the ankle. Ankle alignment correlated with knee alignment both pre-operatively and postoperatively. Both pre-operative knee and ankle malalignment can be simultaneously corrected following TKA. LEVEL OF EVIDENCE: Level III.

The cohort study for the determination of reference values for spinopelvic parameters (T1 pelvic angle and global tilt) in elderly volunteers.

PURPOSE: T1 pelvic angle (TPA) and global tilt (GT) are spinopelvic parameters that account for trunk anteversion and pelvic retroversion. To investigate spinopelvic parameters, especially TPA and GT, in Japanese adults and determine norms for each parameter related to health-related quality of life (HRQOL). MATERIALS AND METHODS: Six hundred and fifty-six volunteers (262 men and 394 women) aged 50-92 years (mean, 72.8 years) were enrolled in this study. The incidence of vertebral fracture, spondylolisthesis and coronal malalignment were measured. Five spinopelvic parameters (TPA, GT, sagittal vertical axis [SVA], pelvic tilt [PT], and pelvic incidence-lumbar lordosis [PI-LL]) were measured using whole spine standing radiographs. The mean values for each parameter were estimated by sex and decade of life. HRQOL measures, including the Oswestry Disability Index (ODI) and EuroQuol-5D (EQ-5D), were also obtained. Pearson's correlation coefficients were determined between each parameter and HRQOL measure. Moreover, the factors contributing to the QOL score were calculated using logistic regression with age, sex, the existence of vertebral fracture and spondylolisthesis, coronal malalignment (coronal curve >30°) and sagittal malalignment (SVA >95 mm) as explanatory variables and the presence of disability (ODI >40) as a free variable. RESULTS: The mean values for the spinopelvic parameters were as follows: TPA, 17.9°; GT, 23.2°; SVA, 50.2 mm; PT, 18.6°; and PI-LL, 7.5°. TPA and GT strongly correlated with each other (r = 0.990) and with the other spinopelvic parameters. TPA and GT correlated with ODI (r = 0.339, r = 0.348, respectively) and EQ-5D (r = -0.285, r = -0.288, respectively), similar to those for SVA. TPA, GT, PT, and PI-LL were significantly higher in women than in men. PT and PI-LL gradually increased with age, while TPA, GT, and SVA tended to deteriorate after the 7th decade. Based on a logistic regression analysis, the deterioration of ODI was mostly affected by the sagittal malalignment. The TPA and GT cut-off values for severe disability (ODI >40) based on linear regression modeling were 26.0° and 33.7°, respectively. CONCLUSIONS: We determined reference values for spinopelvic parameters in elderly volunteers. Similar to SVA, TPA and GT correlated with HRQOL. TPA, GT, PT, and PI-LL were worse in women and progressed with age.

Radiographic Assessment of Femoral Stem Torsion in Total Hip Arthroplasty-A Comparison of a Caput-Collum-Diaphyseal Angle-Based Technique With the Budin View.

BACKGROUND: Correct assessment of femoral stem torsion is crucial in total hip arthroplasty (THA). In this study, we aimed to compare a recently published novel method based on anteroposterior (AP) hip radiographs using the projected caput-collum-diaphyseal (CCD) angle (AP CCD) with the modified posteroanterior Budin view. METHOD: AP radiographs, modified Budin views, and 3-dimensional computed tomography (3D-CT) images were obtained in 30 patients after minimally invasive, cementless THA. Radiographic measurements performed by 4 observers twice in a 6-week interval were compared with 3D-CT measurements. Furthermore, correlations between the radiographic deviation to 3D-CT and patient specific characteristics were evaluated. RESULTS: We found a mean difference of 2.2 ± 6.8° between AP CCD and 3D-CT measurements of femoral stem torsion and -0.5 ± 4.2° between the modified Budin view and 3D-CT. We found a high correlation between mean radiographic and 3D-CT stem torsion (r = 0.78, P < .001 for AP CCD and r = 0.84, P < .001 for Budin view). The observers had excellent agreements within (intraclass correlation coefficient, ≥0.88 for AP CCD and intraclass correlation coefficient, ≥0.94 for Budin view) and between (mean concordance correlation coefficient, ≥0.79 for AP CCD and concordance correlation coefficient, ≥0.86 for Budin view) their radiographic measurements. CONCLUSION: Both radiographic methods enable a simple orientation and a practical conventional radiographic estimation of stem torsion on hip radiographs after THA. However, CT remains the golden standard for exact estimation of stem torsion.

Hip-Knee-Ankle Radiographs Are More Appropriate for Assessment of Post-Operative Mechanical Alignment of Total Knee Arthroplasties than Standard AP Knee Radiographs.

Weight-bearing hip-knee-ankle (HKA) radiographs are the gold standard for measuring lower limb alignment after total knee arthroplasty (TKA), however the majority of UK units use standardised anteroposterior (AP) knee radiographs. This study aimed to determine whether standardised AP knee radiographs adequately assess lower limb alignment after TKA. HKA radiographs from 50 post-operative TKAs were cropped to the size of a standardised AP knee radiograph allowing comparison of mechanical and anatomical alignment measurements between the two views. Repeatability of alignment measurements was significantly better for HKA radiographs, however, there was poor agreement of the mechanical alignment measured between the two views. Standardised AP knee radiographs are insufficient to assess the mechanical alignment of post-operative TKA and we recommend routinely using HKA radiographs.

Radiological outcome and intraoperative evaluation of a computer-navigation system for femoral nailing: a retrospective cohort study.

AIM: Intraoperative determinations of femoral antetorsion and leg length during fixation of femoral shaft fractures present a challenge. In femoral shaft fracture fixations, a computer-navigation system has shown promise in determining antetorsion and leg length discrepancies. This retrospective cohort study aimed to determine whether the use of computer navigation during femoral nailing procedures reduced postoperative femoral malrotation and leg length discrepancy, as well as the number of revision cases. We also sought to determine whether radiation exposure time was reduced when computer navigation was used. MATERIALS AND METHODS: Of 246 patients treated for femoral shaft fractures between 2004 and 2012, we selected those that received postoperative computed tomography for rotation and leg length control. We included 24 patients who received navigation-assisted treatments and 48 who received unassisted treatments, matched for age, sex, and fracture type. All patients were treated by femoral nailing. RESULTS: The groups showed significant differences in the mean (standard deviation (SD) delay before surgery (navigation-assisted vs. unassisted groups: 8.5 ± 3.2 vs. 5.2 ± 5.8 days; P<0.05) and surgery times (163.7 ± 43.94 vs. 98.3 ± 28.13 min; P<0.001). The groups were significantly different in the mean (SD) radiation exposure time (4.43 ± 1.35 vs. 3.73 ± 1.5 min; P=0.042), and were not significantly different in the postoperative femoral antetorsion difference (8.83 ± 5.52° vs. 12.4 ± 9.2°; P=0.056), or in the postoperative length discrepancy (0.92 ± 0.75 vs. 0.95 ± 0.94 cm; P=0.453). Four (16.7%) navigation-assisted and 15 (31.25%) unassisted surgeries got revision for torsion and/or length corrections. CONCLUSION: Our results showed that, compared to unassisted femoral surgery, the computer-navigation system did not improve postoperative results or reduce radiation exposure. In the future, improvements in handling and application could facilitate the workflow and may provide better postoperative results. Currently, computer navigation may provide advantages for complicated or sophisticated cases, such as complex three-dimensional deformity corrections. LEVEL OF EVIDENCE: Level III.

Reliability of a rating scale for assessing alignment of the posterior facet after surgical repair of joint depression fractures of the calcaneus.

Radiographs are frequently used to classify joint depression calcaneal fractures and assess the degree of repair of such injuries. To associate the degree of repair with clinical outcomes such as foot-related quality of life and subjective patient satisfaction, it would be useful to have a valid measuring instrument that has been shown to reliably categorize the alignment of the posterior facet of the calcaneus. To be considered valid, the measurement must have inter-rater and intrarater reliability. In an effort to demonstrate the validity of a coronal plane computed tomographic measurement for categorizing the alignment of the posterior facet after repair of joint depression fractures of the calcaneus, we measured the inter-rater and intrarater reliability of the classification system.

Assessment of the loading history of patients after high tibial osteotomy using SPECT/CT--a new diagnostic tool and algorithm.

BACKGROUND: Single photon emission computerized tomography and conventional computerized tomography (SPECT/CT) tracer uptake has been shown to reflect the loading history of the tibiofemoral knee joint and correlate with the mechanical and anatomical alignment. It was our primary purpose to develop a novel standardized SPECT/CT algorithm for patients undergoing high tibial osteotomy, evaluate the inter- and intra-observer reliability (OR), and assess the clinical applicability for follow-up of patients before and after high tibial osteotomy. METHODS: The localization scheme defines 9 femoral, 8 patellar, and 13 tibial zones to accurately map the examined tracer uptake volume in each anatomical area of interest. Maximum values for each area (mean ± standard deviation, median, and range) of the localization scheme were recorded as well as normalized values for the intensity of SPECT/CT tracer uptake calculated. The inter- and intra-OR was assessed for SPECT/CT localization and tracer activity. Pre- and postoperative mechanical alignment was assessed in SPECT/CT using a custom-made specialized software. The median inter- and intra-observer differences of the measured mechanical alignment were calculated along with the inter- and intra-OR. RESULTS: The localization scheme showed near-perfect inter- and intra-OR (intra-class correlation coefficient (ICC) > 0.9) for the measurement of tracer activity and localization in all anatomical regions. For measurements of mechanical alignment, there was a strong agreement between the two observers (an inter-OR of ICC = 0.99 and an intra-OR of ICC = 0.98). CONCLUSIONS: The presented SPECT/CT algorithm is highly reliable and clinically feasible. Combined with mechanical alignment analysis, it provides the surgeon with helpful information about realignment effects of high tibial osteotomies (HTOs) and might help identify the optimal personalized degree of correction in HTO surgery.

Assessment of the role of fibular fixation in distal-third tibia-fibula fractures and its significance in decreasing malrotation and malalignment.

BACKGROUND: In the treatment of distal-third tibia/fibula fractures treated by interlocking nailing, the role of fibular fixation is not clearly defined. This study aimed to assess the benefits of fibular fixation in such fractures. METHODS: Sixty patients with fractures of the lower third of the leg were enrolled into the study and divided into two groups based on whether the fibula was fixed (group A) or not (group B). Fracture tibia was treated with interlocked intramedullary nailing and fibular fixation was done using a 3.5-mm Limited Contact Dynamic Compression Plate (LC-DCP). The two groups were compared for differences in rotation at ankle, angulation at the fracture site, time of union and complications. Clinical and functional outcomes were assessed regularly. Merchant-Dietz criteria were used to assess ankle function. RESULTS: The demographics of the two groups were similar. Average valgus angulation was significantly less in group A (average 5°) versus group B (average 9°). The degree of rotational malalignment at the ankle in group A was average 7° versus average 15° in group B. The outcome of two groups for clinical ankle score, time of union and complications showed no significant differences. CONCLUSION: Fixation of the fibula along with interlocking nailing of the tibia decreases the malalignment of the tibia and malrotation of the ankle in distal-third fractures of the tibia and fibula as compared with only interlocking nailing.

Assessment of loading history of compartments in the knee using bone SPECT/CT: a study combining alignment and 99mTc-HDP tracer uptake/distribution patterns.

This study investigates if the mechanical/anatomical alignment influences the intensity values as well as the distribution pattern of SPECT/CT tracer uptake. Eighty-five knees (mean age 48 ± 16) undergoing 99mTc-HDP-SPECT/CT due to pain were prospectively included. SPECT/CTs were analyzed using a previously validated localization method. The maximum intensities in each femoral, tibial, and patellar joint compartment (medial, lateral, central, superior, and inferior) were noted using a color-coded grading scale (0-10). The Kellgren-Lawrence osteoarthritis score (KL) was assessed on standardized radiographs. Long leg radiographs were used to assess the mechanical/anatomical leg alignment, which was classified as varus, valgus, or neutral. The alignment and KL was correlated with the intensity of tracer uptake in each area of interest (p < 0.05). The intensity of SPECT/CT tracer uptake in the medial and lateral knee compartment significantly correlated with varus or valgus alignment of the knee. A higher degree of osteoarthritis was significantly related to higher tracer uptake in the corresponding joint compartments. SPECT/CT reflects the specific loading pattern of the knee with regard to its alignment. It is also related to the degree of osteoarthritis. Hence, SPECT/CT should be considered for follow-up of patients after realignment treatments, osteotomies, deloader devices, or insoles.

Assessment of inter- and intra-observer reliability in the determination of radiographic version and inclination of the cup in metal-on-metal hip resurfacing.

PURPOSE: Determination of the cup orientation after metal-on-metal hip resurfacing may provide important information in the postoperative follow-up. We present a mathematical method based on a previously described approach to assess the version and inclination of the cup in the metal-on-metal bearing without a separate software computation from plain radiographs. The aim of the study was to assess the intra- and inter-observer reliability of this method. METHODS: Calculation of version and inclination were done twice for 20 hip resurfacings by four observers. Intra-observer reliability was estimated by mean error and correlation of the two sets of measurement for version and inclination. Bland-Altman plots, intra-class coefficient and mean error were used to assess the inter-observer reliability of the measurements. RESULTS: Intra-observer correlation for version measurement ranged from 0.74 to 0.94. Correlation for inclination varied between 0.94 and 0.97. Upper and lower limits of agreement in Bland-Altman plots for version measurements between observers ranged from 4.1 to 7.2 degrees and from -3.2 to -8.3 degrees, respectively. For inclination measurements the upper and lower limits ranged from 3.1 to 5.3 degrees and from -2.7 to -6.0 degrees. CONCLUSIONS: Mean errors, correlation coefficients and 95% limits of agreement were on an acceptable level. We believe that this method is applicable for clinical use.

Immediate recovery room radiographs after primary total knee arthroplasty-why do we keep doing them?

Recovery room radiographs (RRR) are routinely performed after total knee arthroplasty (TKA). This study investigates the utility of these radiographs. Twenty four arthroplasty surgeons were surveyed to rank the value of RRRs. Since RRRs were primarily valued for educational purposes, we examined the ability of 49 orthopaedic trainees to determine the coronal alignment of TKA performed in cadaveric specimens based on these radiographs in neutral, 10° internal and external rotations. Surgeons rated the quality of the RRRs to be significantly lower than the radiographs taken in the radiology suite (5.5 ± 2.5 versus 8.9 ± 0.9, p < 0.0001). Of an estimated 65,910 TKAs performed by these surgeons, only eight cases (0.01%) required same day revision based on the RRR. Neutral alignment was significantly more accurately (p < 0.0001) interpreted than valgus or varus (69.4% versus 42.9% and 16.3%, respectively). Surprisingly, internal rotation of the limb significantly improved interpretation of both varus (from 16.3% to 40.8%, p = 0.014) and valgus (from 42.9% to 63.3%, p = 0.048). Increased level of orthopaedic training did not significantly affect the accuracy of interpretation (p = 0.46). Interpretation of RRRs for coronal malalignment is inaccurate and has a limited educational value.

Assessment of knee alignment after bicompartmental knee arthroplasty.

A key factor in successful knee arthroplasty is restoration of correct knee alignment. Although traditional total knee arthroplasty effectively restores alignment, it is unclear whether similar results can be consistently obtained with more conservative procedures. The purpose of this study was to assess alignment after implantation of the Journey Deuce Bi-Compartmental Knee System (Smith & Nephew, Inc, Memphis, Tenn). Mechanical axis was assessed in 137 cases. Preoperatively, 77 (56%) of 137 patients had a mechanical axis passing far medial to the center of the knee, consistent with varus deformity. Postoperatively, 130 (95%) of 137 patients had a mechanical axis passing through the center of the knee. These results suggest that the Journey Deuce Bi-Compartmental Knee System supports correction of varus deformity, previously thought to require total knee arthroplasty or osteotomy.

[Assessment of implant position of CTX-custom-made stems with EBRA-FCA in 107 cases of total joint replacement]. / Bewertung der Implantatposition von 107 individuellen CTX-Hüftendoprothesenschäften mit EBRA-FCA.

AIM: The aim of this study was to assess the ratio of correct and malpositioned stems in a THR population with custom-made stems. Furthermore, any relation of the extent of deviation from the exact stem position and defined patient variables was evaluated. METHODS: Preoperatively, in three-dimensional virtual reality, CTX-individual hip stems were positioned in femora reconstructed from the individual patient's CT data until a stable cortical fit was achieved. Postoperative femoral stem position was measured with EBRA-FCA (EinzelBildRontgenAnalyse-Femoral Component Analysis). Differences of planned and actual depth of stem position were calculated for 107 CTX-custom-made hip stems implanted at one institution. RESULTS: Compared to preoperative planning 59 hip stems were placed too high, while 16 were placed exactly to within one millimeter and 32 were positioned too low. Deviations of postoperative stem position from preoperative planning did not correlate with previous femoral osteotomy found in one-third of femora or femoral anteversion exceeding 25 degrees as present in two-thirds of patients. CONCLUSION: In 71 % the intraoperative stem position did match the preoperative CTX-implant fitting into virtual patient femora. 29 % of implanted stems were malpositioned, i. e., deviations were greater plus or minus 5 mm to preoperative computer planning. None of the examined variables such as body mass index, previous femoral osteotomy, surgical approach, abnormal anteversion angle served as a predictive value for CTX-stem position in this cohort.

[Accuracy of an image-free cup navigation system--an anatomical study]. / Genauigkeit eines bildfreien Navigationssystemes für die Hüftpfannenimplantation--eine anatomische Studie.

The position of the acetabular cup is of decisive importance for the function of a total hip replacement (THR). Using the conventional surgical technique, correct placement of the cup often fails due to a lack of information about pelvic tilt. With CT-based and fluoroscopically-assisted navigation procedures the accuracy of implantation has been significantly improved. However, additional radiation exposure, high cost and the increased time requirement have hampered the acceptance of these techniques. The present anatomical study evaluates the accuracy of an alternative procedure--image-free navigation. This method requires little extra effort, does not substantially delay surgery, and needs no additional imaging. Press-fit cups were implanted in 10 human cadaveric hips with the help of the image-free navigation system, and the position of the cups was checked intraoperatively with a CT-based navigation system and postoperatively by computed tomography. All cups were implanted within the targeted safe zone with an average inclination of 44 degrees (range 40 degrees-48 degrees, SABW 2.7 degrees) and an average anteversion of 18 degrees (range 12-24 degrees, SABW 4.1 degrees). Analysis of accuracy of the image-free navigation software revealed only a small, clinically tolerable deviation in cup anteversion and cup inclination in comparison with the CT-based navigation system and the post operative CT scans. The evaluated image-free navigation system appears to be a practicable and reliable alternative to the computer-assisted implantation of acetabular cups in total hip arthroplasty.

Radiographic assessment of the hindfoot and ankle.

This article is an introduction to a complex topic on radiographic views as they relate to alignment of the ankle and hindfoot to the lower leg. Patient positioning as it relates to obtaining full-length lower extremity radiograph views are discussed along with contralateral radiographs, which are useful and important for comparative purposes.